Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles...Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles. During this study, identification of lipid microinclusions having the form of such lipid-protein structural microformations as lipid-protein microdomains, vesicles and membrane tubular structures (cytoplasmic transvacuolar strands and nanotubes) located in organelle membranes or bound up with them was conducted. Such membrane probes as laurdan, DPH, ANS and bis-ANS were used. Comparison of fluorescence intensity of these membrane probes was conducted. This investigation of the morphological properties of lipid-protein structural microformations was accompanied with analysis of 1) the phase state and 2) dynamics of microviscosity variations in the membrane elements of isolated plant cell organelles. Distributions of laurdan fluorescence generalized polarization (GP) values for the membrane on the whole and for the intensively fluorescing membrane segments were obtained. It was discovered that the microviscosity of intensively fluorescing membrane segments essentially differed from the microviscosity of the rest part of the membrane. In conclusion, some results of the study of peculiar properties of lipid-protein structural microformations related to the structure of organelle membranes and the discoveries made in this investigation are discussed.展开更多
Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionall...Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.展开更多
Objective:To compare the two methods of rapid diagnostic tests(RDTs)and microscopy in the diagnosis of malaria.Methods:RDTs and microscopy were carried out to diagnose malaria. Percentage malaria parasitaemia was calc...Objective:To compare the two methods of rapid diagnostic tests(RDTs)and microscopy in the diagnosis of malaria.Methods:RDTs and microscopy were carried out to diagnose malaria. Percentage malaria parasitaemia was calculated on thin films and all non-acute cases of plasmodiasis with less than 0.001%malaria parasitaemia were regarded as negative.Results were simply presented as percentage positive of the total number of patients under study.The results of RDTs were compared to those of microscopy while those of RDTs based on antigen were compared to those of RDTs based on antibody.Patients' follow-up was made for all cases.Results: All the 200 patients under present study tested positive to RDTs based on malaria antibodies(serum)method(100%).128 out of 200 tested positive to RDTs based on malaria antigen(whole blood)method(64%),while 118 out of 200 patients under present study tested positive to visual microscopy of Lieshman and diluted Giemsa(59%).All patients that tested positive to microscopy also tested positive to RDTs based on antigen.All patients on the second day of follow-up were non-febrile and had antimalaria drugs.Conclusions;We conclude based on the present study that the RDTs based on malaria antigen(whole blood)method is as specific as the traditional microscopy and even appears more sensitive than microscopy.The RDTs based on antibody(serum)method is unspecific thus it should not be encouraged.It is most likely that Africa being an endemic region,formation of certain levels of malaria antibody may not be uncommon.The present study also supports the opinion that a good number of febrile cases is not due to malaria. We support WHO's report on cost effectiveness of RDTs but,recommend that only the antigen based method should possibly,be adopted in Africa and other malaria endemic regions of the world.展开更多
The deficit of organ donors has fueled the need for advances in tissue engineering and regenerative medicine. Microencapsulation in alginate immuno-isolation membranes has been used to treat many disabling metabolic d...The deficit of organ donors has fueled the need for advances in tissue engineering and regenerative medicine. Microencapsulation in alginate immuno-isolation membranes has been used to treat many disabling metabolic disorders, namely, phenylketonuria, kidney failure and diabetes mellitus. Systematic nutrient flux determinations are hindered by the lack of experimental data on alginate-based membrane topography and the pore size thus preventing the full therapeutic potential of the bio-membranes to be reached. In this study, samples of cross-linked alginate membranes were subjected to the following analytical characterization: 1) pore size characterization using atomic force microscopy operated in contact mode to detect and measure pore size;2) differential scanning calorimetry to confirm biopolymer cross-linking;and 3) diffusivity measurements using spectrophotometry and fluorescence microscopy to confirm the presence of through pores and to calculate reflection coefficients. The pore sizes for the pre-clinical standard formulation of 1.5% (w/v) medium viscosity alginate cross-linked with 1.5% CaCl2 and 0.5% (w/v) alginate and chitosan cross-linked with 20% CaCl2 are 5.2 nm ± 0.9 nm and 7.0 nm ± 3.1 nm, respectively. An increase in the glass transition temperatures as a function of cross-linker concentration was observed. Diffusivity values obtained from the inward diffusivity of creatinine into macrocapsules (d = 1000 μm ± 75 μm) and the outward diffusivity of FITC dextrans from macrocapsules (d = 1000 μm ± 75 μm) and microcapsules (d = 40 μm ± 5 μm) were shown to correlate strongly (R2 = 0.9835) with the ratio of solute to pore sizes, confirming the presence of through pores. Reflection coefficients approaching and exceeding unity correlate with the lack of permeability of the membranes to MW markers that are 70 kDa and greater.展开更多
For the past thirty years, intense efforts have been made to record atomic scale movies that reveal the movement of atoms in molecules, the fast dynamical processes in biological tissues and cells, and the changes in ...For the past thirty years, intense efforts have been made to record atomic scale movies that reveal the movement of atoms in molecules, the fast dynamical processes in biological tissues and cells, and the changes in the structure of a solid confined to nano-scale volumes. A combination of sub-nanometer spatial resolution with picosecond or even femtosecond temporal resolution is required for such atomic movies. Additional important information can be obtained when the energy of the electron beam transmitted through the sample is measured. The four dimensional (4D) spatially and temporally resolved ultrafast electron microscopy method is made possible by the extremely high detection efficiency that is reached in 4D electron microscopy. Using ultra-short electron bunches for the visualization of biological tissue can also improve the spatial resolution compared to conventional electron microscopes, thereby enabling the study of complex biological samples of relevance to the life sciences. Of particular interest to a broad audience is the possibility to create a video, and in the future, a real atomic movie, using 4D electron tomography.展开更多
Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often ...Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.展开更多
The physiology and ecology of planktonic organisms are influenced by the concentration, chemical speciation and resulting bioavailability of some trace metals. The determination of the elemental structure of phytoplan...The physiology and ecology of planktonic organisms are influenced by the concentration, chemical speciation and resulting bioavailability of some trace metals. The determination of the elemental structure of phytoplankton is important for interpretation of physiological and functional states of coastal ecosystems. The present study is focused on the structure and elemental composition of the phytoplankton assemblages from the different coastal zones by instrumental neutron activation analysis (INAA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). For the first time these complementary techniques were simultaneously applied to study the Black Sea phytoplankton. The concentrations of 45 elements in the coastal phytoplankton communities used as bioindicator of inorganic contamination of the Black Sea coastal area near Sevastopol, Ukraine, were determined. Phytoplankton samples were collected by total tows of the plankton net with 35 μm pore size at 3 stations situated in polluted and relatively pristine water areas of the Sevastopol coastal zone during autumn period of the phytoplankton growth. The concentration of Mg, Al, Sc, Ti, V, Mn, As, Rb, Ba, Th and Fe, Cr increases exponentially from relatively pristine station to more polluted station and 10-times and 3-times greater, respectively, in the phytoplankton of the Sevastopol Bay. The rare-earth elements have relatively the same concentration values less than 1 μg/g and tend to accumulate in the phytoplankton from the polluted station in the Sevastopol Bay. The obtained results are in a good agreement with the elemental concentration data in the oceanic plankton, plankton communities from the White Sea and the Black Sea. Using energy-dispersive X-ray spectrometry the mineral particles of unknown origin and impurities of copper (0.42% by weight) in the phytoplankton at the polluted station and zinc (0.57% by weight) at the relatively pristine station were determined.展开更多
Urea-formaldehyde (UF) resin is widely used as an adhesive for the manufacture of a range of wood and fiber based products. Although the microstructure of this resin has been examined at high resolution by field-emiss...Urea-formaldehyde (UF) resin is widely used as an adhesive for the manufacture of a range of wood and fiber based products. Although the microstructure of this resin has been examined at high resolution by field-emission scanning electron microscopy and atomic force microscopy, transmission electron microscopy (TEM) has thus far not been used, perhaps because of difficulties in ultrathin sectioning this resin in cured (polymerized) state. In the technical note presented here, a novel sample preparation method is described which enabled us to examine the microstructural morphology of UF resin by transmission electron microscopy in ultrathin sections, revealing the presence of spherical particles within the resin. Our initial attempt to ultrathin section the resin directly was not successful as it was too brittle to trim blocks for sectioning. Then, we developed a sample preparation technique that involved impregnation ofPinus radiatawood tissues with the UF resin, and then embedding of resin impregnated wood tissues with Spurr’s low viscosity embedding medium, which has been widely employed in plant and wood ultrastructure work. The TEM images illustrated and the information on the microstructural morphology of the UF resin presented are based on this novel sample preparation approach.展开更多
Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W...Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W⋅cm−2 to expose test objects. The optimum parameters needed for obtaining high accurate information on the samples under test namely: the minimum energies and irradiances at a range of angles between the incoming laser beam and the normal to the resist, the depth of exposure of the photoresist as a function of incident laser energy (and irradiance) were concluded in this work.展开更多
To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these me...To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.展开更多
Introduction: Reports indicate that fluorescent staining of smears increases sensitivity of direct microscopy;so ZN staining is being replaced with fluorescent microscopy in RNTCP in India. Chemical processing and spu...Introduction: Reports indicate that fluorescent staining of smears increases sensitivity of direct microscopy;so ZN staining is being replaced with fluorescent microscopy in RNTCP in India. Chemical processing and sputum concentration may also improve sensitivity of microscopy. Objective: To compare the sensitivity and specificity of microscopy for AFB using ZN and fluorescent stains in direct and concentrated specimen with culture as gold standard. Methods: Morning sputum specimen of patients, suspected of having pulmonary tuberculosis, over a period of 6 months was subjected to direct microscopy using fluorescent stain;the same slide was over-stained with ZN stain. Same sputum sample was concentrated by Petroff’s method and subjected to fluorescent microscopy followed by ZN microscopy and finally to culture for AFB. Results: Sensitivity of fluorescent stained concentrated sputum samples was maximum and of ZN stained unprocessed sputum samples was minimum. Specificity of three of the methods was equal at 0.96 but of ZN stained concentrated sputum smears was 0.97. Sensitivity of total fluorescent stains was 0.85 (Specificity 0.96) and sensitivity of total ZN stained smears was 0.80 (Specificity 0.96). Discussion: We used same smear for fluorescent and ZN stains, so smear related variability is decreased. Blinding for microscopy was practically complete. Conclusion: The sensitivity of sputum microscopy for AFB can be increased by concentrating the sputum and using fluorescent microscopy. The specificity remains high in all the methods.展开更多
The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclus...The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclusively observed in thin films under atmospheric pressure,underscoring the critical role of the heterointerface.展开更多
Thrombus formation in the artificial heart blood pump is a complex problem. The most important factor of thrombosis in the blood pump is the quality of blood contacting surface which is related to hemocompatibility of...Thrombus formation in the artificial heart blood pump is a complex problem. The most important factor of thrombosis in the blood pump is the quality of blood contacting surface which is related to hemocompatibility of materials and micromorphololgy or roughness of the surface. So it is necessary to understand the morphology of the surface inside of blood pump in order to develop and improve a good quality blood pump. The authors observed and analysed the inner surface of blood pumps (both preimplanted and postimplanted) with scanning electron microscopy (SEM) providing a means for evaluating the blood pumps and for developing good quality of blood pumps. It was observed that there were four kinds of surface defects on the inner surface of the blood pumps: air bubble domes, open bubble craters, contaminated dust and gel particles. Microcrakes had also been found on the diaphragm of the postimplanted pump. But in the newly improved blood pump that had been imlanted for 16 days, there were few defects on the blood contacting surface, and only a little fibrinous layer observed. It could be considered that the current design and modifications are reasonable. Since some problems associated with the surface defects and thrombosis still existed, further improvement in fabrication process and quality control procedures with SEM are under way.展开更多
Common bean (Phaseolus vulgaris L.) is an economic important crop and one of the major grain legumes for human consumption in Latin America, Africa and Asia. A morphological study of shoot induced from embryonic axes ...Common bean (Phaseolus vulgaris L.) is an economic important crop and one of the major grain legumes for human consumption in Latin America, Africa and Asia. A morphological study of shoot induced from embryonic axes development in four Costa Rican bean varieties (Brunca, Huetar, Guaymi and Bribri) cultivated on MS media with or without 5 mg·L–1 de N6-benzylaminopurine (BAP) by scanning electron microscopy (SEM) was developed in the present work. Micrographs showed similarities and differences in the ultrastructure of the apical dome, epidermal surface, stomata and different types of trichomes in the varieties cultivated on organogenesis media. Genotypes with advantageous morphological characteristics for genetic transformation, in particular an exposed apical dome, were identified. This work will contribute to the optimization of the in vitro regeneration of four common bean varieties.展开更多
Melanosomes, isolated by centrifugal separation from culture broth of B16 melanoma cells derived from mouse, were observed by scanning electron microscopy (SEM), and by transmission electron microscopy (TEM). Some int...Melanosomes, isolated by centrifugal separation from culture broth of B16 melanoma cells derived from mouse, were observed by scanning electron microscopy (SEM), and by transmission electron microscopy (TEM). Some interesting structural features were found inside and outside of the melanosomes. By SEM observation, the melanosomes were ellipsoid shape, their surface was not smooth and was covered with rough substructure, 10 to 20 nm particles. By TEM, uneven structure and micro particles were observed in the melanosomes. Furthermore, three-dimensional analysis was tried by using the ultra-high voltage electron microscopy(UHVEM). Micrographs of the melanosomes were taken at various tilted angles by UHVEM, after preparing 500 nm thickness specimens stained with lead citrate. From the micrographs collected, the three-dimensional structures were reconstructed by using i-mode software. Melanin stained by lead and non stained parts was clearly observed in the reconstructed structure. Non stained parts were round, regular size, and distributed widely in the melanosomes.展开更多
Background: Confirmatory diagnosis of Trypanosoma brucei gambiense human African trypanosomiasis (HAT) is based on demonstration of parasites by microscopy. However, the sensitivity of routine microscopy methods is ve...Background: Confirmatory diagnosis of Trypanosoma brucei gambiense human African trypanosomiasis (HAT) is based on demonstration of parasites by microscopy. However, the sensitivity of routine microscopy methods is very low, and many cases are missed and left untreated. A clinical study was conducted in the Democratic Republic of the Congo to evaluate the accuracy of improved microscopy methods in diagnosis of HAT. These included examination by fluorescence microscopy (FM) of acridine orange (AO) stained smears of whole blood and smears made following a new procedure for concentrating trypanosomes by selective lysis of red blood cells (RBC). Methodology/Principal Findings: Venous blood was collected from 213 HAT cases, 101 HAT suspects and 95 controls and used to determine the accuracy of four microscopy methods: bright field microscopy of Giemsa-stained thick blood smears, FM of AO-stained thick blood smears, FM of AO-stained thick blood smears prepared after RBC lysis and concentration, and FM of AO-stained thin blood smears prepared after RBC lysis and concentration. The sensitivity of FM using thick blood smears stained with AO was 3 times higher than bright field microscopy using Giemsa-stained thick blood smears [19.7% (95% CI: 14.9% - 25.6%) versus 6.1% (95% CI: 3.6% - 10.2%)]. When the RBC lysis and concentration procedure was included, sensitivity of the test was further enhanced to 23.0% (95% CI: 17.9% - 29.1%) with thick blood smears and 34.3% (95% CI: 28.2% - 40.9%) with thin blood smears. Specificity of all four microscopy methods was 100% (95% CI: 96.1% - 100.0%). However, the miniature anion exchange chromatography technique (mAECT) and capillary tube centrifugation (CTC) method remained more sensitive. Conclusions: These new methods have practical advantages, including shorter staining time, ease of demonstration of parasites, and the possibility of archiving slides. They could, therefore, be alternative methods to improve case detection where concentration procedures such as mAECT or CTC are not performed.展开更多
Diagnosis of Trypanosoma brucei rhodesiense human African trypanosomiasis requires demonstration of parasites in body fluids by microscopy. The microscopy methods that are routinely used are difficult to deploy in res...Diagnosis of Trypanosoma brucei rhodesiense human African trypanosomiasis requires demonstration of parasites in body fluids by microscopy. The microscopy methods that are routinely used are difficult to deploy in resource-limited settings due to practical challenges, including lengthy and tedious procedures, and the need for specific equipment to centrifuge samples in glass capillary tubes. We report here on a study that was conducted in a rural region of eastern Uganda to evaluate new methods that take advantage of a field-deployable LED fluorescence microscope. Examination of acridine orange-stained blood smears by LED fluorescence microscopy resulted in a diagnostic accuracy that was similar to that of routine methods, while the time needed to identify parasites was shortened significantly. These findings make these new microscopy methods attractive alternatives to procedures that are currently used for diagnosis of T. b. rhodesiense human African trypanosomiasis.展开更多
The aim of the investigation was to develop the use of topographic and nano-adhesion atomic force microscopy(AFM) studies as a means of monitoring the coalescence of latex particles within films produced from a pharma...The aim of the investigation was to develop the use of topographic and nano-adhesion atomic force microscopy(AFM) studies as a means of monitoring the coalescence of latex particles within films produced from a pharmaceutically relevant aqueous dispersion(Eudragit~?NE30 D). Films were prepared via spin coating and analysed using AFM, initially via tapping mode for topographic assessment followed by force-distance measurements which allowed assessment of site-specific adhesion. The results showed that colloidal particles were clearly observed topographically in freshly prepared samples, with coalescence detected on curing via the disappearance of discernible surface features and a decrease in roughness indices. The effects of temperature and humidity on film curing were also studied, with the former having the most pronounced effect. AFM force measurements showed that the variation in adhesive force reduced with increasing curing time, suggesting a novel method of quantifying the rate of film formation upon curing. It was concluded that the AFM methods outlined in this study may be used as a means of qualitatively and quantitatively monitoring the curing of pharmaceutical films as a function of time and other variables, thereby facilitating rational design of curing protocols.展开更多
AIM: To assess potential contributions of biliary IgA for crystal agglomeration into gallstones, we visualized cholesterol crystal binding of biliary IgA. METHODS: Crystal binding biliary proteins were extracted from ...AIM: To assess potential contributions of biliary IgA for crystal agglomeration into gallstones, we visualized cholesterol crystal binding of biliary IgA. METHODS: Crystal binding biliary proteins were extracted from human gallbladder bile using lectin affinity chromatography.Biliary IgA was isolated from the bound protein fraction by immunoaffinity chromatography. Pure cholesterol monohydrate crystals were incubated with biliary IgA and fluoresceine isothiocyanate (FITC)conjugated anti IgA at 37 degree. Samples were examined under polarizing and fluorescence light microscopy with digital image processing. RESULTS: Binding of biliary IgA to cholesterol monohydrate crystals could be visualized with FITC conjugated anti IgA antibodies.Peak fluorescence occurred at crystal edges and dislocations. Controls without biliary IgA or with biliary IgG showed no significant fluorescence. CONCLUSION: Fluorescence light microscopy provided evidence for cholesterol crystal binding of biliary IgA. Cholesterol crystal binding proteins like IgA might be important mediators of crystal agglomeration and growth of cholesterol gallstones by modifying the evolving crystal structures in vivo.展开更多
Surface coatings provide protection to wood products against weathering and other deteriorating factors, such as moisture uptake and microbial invasion. The effectiveness of coatings depends on many factors, including...Surface coatings provide protection to wood products against weathering and other deteriorating factors, such as moisture uptake and microbial invasion. The effectiveness of coatings depends on many factors, including how well the applied coatings adhere to the wood surface. Coating adhesion to wood involves both chemical and physical interactions between the coating and wood tissues in contact, and the particular focus of this mini-review will be on the advances being made in understanding the physical aspects of the interaction by probing wood-coating interface using novel and high resolution imaging techniques, including confocal laser scanning microscopy (CLSM), SEM-backscattered electron imaging and correlative microscopy employing light, confocal and scanning electron microscopy.展开更多
文摘Peculiar properties of morphological structures of organelle membranes were studied by fluorescent confocal microscopy. The list of objects in our experiments was represented by mitochondria, chloroplasts and vacuoles. During this study, identification of lipid microinclusions having the form of such lipid-protein structural microformations as lipid-protein microdomains, vesicles and membrane tubular structures (cytoplasmic transvacuolar strands and nanotubes) located in organelle membranes or bound up with them was conducted. Such membrane probes as laurdan, DPH, ANS and bis-ANS were used. Comparison of fluorescence intensity of these membrane probes was conducted. This investigation of the morphological properties of lipid-protein structural microformations was accompanied with analysis of 1) the phase state and 2) dynamics of microviscosity variations in the membrane elements of isolated plant cell organelles. Distributions of laurdan fluorescence generalized polarization (GP) values for the membrane on the whole and for the intensively fluorescing membrane segments were obtained. It was discovered that the microviscosity of intensively fluorescing membrane segments essentially differed from the microviscosity of the rest part of the membrane. In conclusion, some results of the study of peculiar properties of lipid-protein structural microformations related to the structure of organelle membranes and the discoveries made in this investigation are discussed.
文摘Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.
文摘Objective:To compare the two methods of rapid diagnostic tests(RDTs)and microscopy in the diagnosis of malaria.Methods:RDTs and microscopy were carried out to diagnose malaria. Percentage malaria parasitaemia was calculated on thin films and all non-acute cases of plasmodiasis with less than 0.001%malaria parasitaemia were regarded as negative.Results were simply presented as percentage positive of the total number of patients under study.The results of RDTs were compared to those of microscopy while those of RDTs based on antigen were compared to those of RDTs based on antibody.Patients' follow-up was made for all cases.Results: All the 200 patients under present study tested positive to RDTs based on malaria antibodies(serum)method(100%).128 out of 200 tested positive to RDTs based on malaria antigen(whole blood)method(64%),while 118 out of 200 patients under present study tested positive to visual microscopy of Lieshman and diluted Giemsa(59%).All patients that tested positive to microscopy also tested positive to RDTs based on antigen.All patients on the second day of follow-up were non-febrile and had antimalaria drugs.Conclusions;We conclude based on the present study that the RDTs based on malaria antigen(whole blood)method is as specific as the traditional microscopy and even appears more sensitive than microscopy.The RDTs based on antibody(serum)method is unspecific thus it should not be encouraged.It is most likely that Africa being an endemic region,formation of certain levels of malaria antibody may not be uncommon.The present study also supports the opinion that a good number of febrile cases is not due to malaria. We support WHO's report on cost effectiveness of RDTs but,recommend that only the antigen based method should possibly,be adopted in Africa and other malaria endemic regions of the world.
文摘The deficit of organ donors has fueled the need for advances in tissue engineering and regenerative medicine. Microencapsulation in alginate immuno-isolation membranes has been used to treat many disabling metabolic disorders, namely, phenylketonuria, kidney failure and diabetes mellitus. Systematic nutrient flux determinations are hindered by the lack of experimental data on alginate-based membrane topography and the pore size thus preventing the full therapeutic potential of the bio-membranes to be reached. In this study, samples of cross-linked alginate membranes were subjected to the following analytical characterization: 1) pore size characterization using atomic force microscopy operated in contact mode to detect and measure pore size;2) differential scanning calorimetry to confirm biopolymer cross-linking;and 3) diffusivity measurements using spectrophotometry and fluorescence microscopy to confirm the presence of through pores and to calculate reflection coefficients. The pore sizes for the pre-clinical standard formulation of 1.5% (w/v) medium viscosity alginate cross-linked with 1.5% CaCl2 and 0.5% (w/v) alginate and chitosan cross-linked with 20% CaCl2 are 5.2 nm ± 0.9 nm and 7.0 nm ± 3.1 nm, respectively. An increase in the glass transition temperatures as a function of cross-linker concentration was observed. Diffusivity values obtained from the inward diffusivity of creatinine into macrocapsules (d = 1000 μm ± 75 μm) and the outward diffusivity of FITC dextrans from macrocapsules (d = 1000 μm ± 75 μm) and microcapsules (d = 40 μm ± 5 μm) were shown to correlate strongly (R2 = 0.9835) with the ratio of solute to pore sizes, confirming the presence of through pores. Reflection coefficients approaching and exceeding unity correlate with the lack of permeability of the membranes to MW markers that are 70 kDa and greater.
文摘For the past thirty years, intense efforts have been made to record atomic scale movies that reveal the movement of atoms in molecules, the fast dynamical processes in biological tissues and cells, and the changes in the structure of a solid confined to nano-scale volumes. A combination of sub-nanometer spatial resolution with picosecond or even femtosecond temporal resolution is required for such atomic movies. Additional important information can be obtained when the energy of the electron beam transmitted through the sample is measured. The four dimensional (4D) spatially and temporally resolved ultrafast electron microscopy method is made possible by the extremely high detection efficiency that is reached in 4D electron microscopy. Using ultra-short electron bunches for the visualization of biological tissue can also improve the spatial resolution compared to conventional electron microscopes, thereby enabling the study of complex biological samples of relevance to the life sciences. Of particular interest to a broad audience is the possibility to create a video, and in the future, a real atomic movie, using 4D electron tomography.
基金supported by the Project of Health Committee of Hunan Province(D202304128868),China.
文摘Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.
文摘The physiology and ecology of planktonic organisms are influenced by the concentration, chemical speciation and resulting bioavailability of some trace metals. The determination of the elemental structure of phytoplankton is important for interpretation of physiological and functional states of coastal ecosystems. The present study is focused on the structure and elemental composition of the phytoplankton assemblages from the different coastal zones by instrumental neutron activation analysis (INAA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). For the first time these complementary techniques were simultaneously applied to study the Black Sea phytoplankton. The concentrations of 45 elements in the coastal phytoplankton communities used as bioindicator of inorganic contamination of the Black Sea coastal area near Sevastopol, Ukraine, were determined. Phytoplankton samples were collected by total tows of the plankton net with 35 μm pore size at 3 stations situated in polluted and relatively pristine water areas of the Sevastopol coastal zone during autumn period of the phytoplankton growth. The concentration of Mg, Al, Sc, Ti, V, Mn, As, Rb, Ba, Th and Fe, Cr increases exponentially from relatively pristine station to more polluted station and 10-times and 3-times greater, respectively, in the phytoplankton of the Sevastopol Bay. The rare-earth elements have relatively the same concentration values less than 1 μg/g and tend to accumulate in the phytoplankton from the polluted station in the Sevastopol Bay. The obtained results are in a good agreement with the elemental concentration data in the oceanic plankton, plankton communities from the White Sea and the Black Sea. Using energy-dispersive X-ray spectrometry the mineral particles of unknown origin and impurities of copper (0.42% by weight) in the phytoplankton at the polluted station and zinc (0.57% by weight) at the relatively pristine station were determined.
文摘Urea-formaldehyde (UF) resin is widely used as an adhesive for the manufacture of a range of wood and fiber based products. Although the microstructure of this resin has been examined at high resolution by field-emission scanning electron microscopy and atomic force microscopy, transmission electron microscopy (TEM) has thus far not been used, perhaps because of difficulties in ultrathin sectioning this resin in cured (polymerized) state. In the technical note presented here, a novel sample preparation method is described which enabled us to examine the microstructural morphology of UF resin by transmission electron microscopy in ultrathin sections, revealing the presence of spherical particles within the resin. Our initial attempt to ultrathin section the resin directly was not successful as it was too brittle to trim blocks for sectioning. Then, we developed a sample preparation technique that involved impregnation ofPinus radiatawood tissues with the UF resin, and then embedding of resin impregnated wood tissues with Spurr’s low viscosity embedding medium, which has been widely employed in plant and wood ultrastructure work. The TEM images illustrated and the information on the microstructural morphology of the UF resin presented are based on this novel sample preparation approach.
文摘Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W⋅cm−2 to expose test objects. The optimum parameters needed for obtaining high accurate information on the samples under test namely: the minimum energies and irradiances at a range of angles between the incoming laser beam and the normal to the resist, the depth of exposure of the photoresist as a function of incident laser energy (and irradiance) were concluded in this work.
基金supported by University of Macao,China,Nos.MYRG2022-00054-FHS and MYRG-GRG2023-00038-FHS-UMDF(to ZY)the Macao Science and Technology Development Fund,China,Nos.FDCT0048/2021/AGJ and FDCT0020/2019/AMJ and FDCT 0011/2018/A1(to ZY)Natural Science Foundation of Guangdong Province of China,No.EF017/FHS-YZ/2021/GDSTC(to ZY)。
文摘To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.
文摘Introduction: Reports indicate that fluorescent staining of smears increases sensitivity of direct microscopy;so ZN staining is being replaced with fluorescent microscopy in RNTCP in India. Chemical processing and sputum concentration may also improve sensitivity of microscopy. Objective: To compare the sensitivity and specificity of microscopy for AFB using ZN and fluorescent stains in direct and concentrated specimen with culture as gold standard. Methods: Morning sputum specimen of patients, suspected of having pulmonary tuberculosis, over a period of 6 months was subjected to direct microscopy using fluorescent stain;the same slide was over-stained with ZN stain. Same sputum sample was concentrated by Petroff’s method and subjected to fluorescent microscopy followed by ZN microscopy and finally to culture for AFB. Results: Sensitivity of fluorescent stained concentrated sputum samples was maximum and of ZN stained unprocessed sputum samples was minimum. Specificity of three of the methods was equal at 0.96 but of ZN stained concentrated sputum smears was 0.97. Sensitivity of total fluorescent stains was 0.85 (Specificity 0.96) and sensitivity of total ZN stained smears was 0.80 (Specificity 0.96). Discussion: We used same smear for fluorescent and ZN stains, so smear related variability is decreased. Blinding for microscopy was practically complete. Conclusion: The sensitivity of sputum microscopy for AFB can be increased by concentrating the sputum and using fluorescent microscopy. The specificity remains high in all the methods.
基金supported by the National Natural Science Foundation of China[52125307(to P.G.),12404192(to R.C.S),12274061(to L.Q.)]Key Research and Development Program from the Ministry of Science and Technology(2023YFA1406301)the support from the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclusively observed in thin films under atmospheric pressure,underscoring the critical role of the heterointerface.
文摘Thrombus formation in the artificial heart blood pump is a complex problem. The most important factor of thrombosis in the blood pump is the quality of blood contacting surface which is related to hemocompatibility of materials and micromorphololgy or roughness of the surface. So it is necessary to understand the morphology of the surface inside of blood pump in order to develop and improve a good quality blood pump. The authors observed and analysed the inner surface of blood pumps (both preimplanted and postimplanted) with scanning electron microscopy (SEM) providing a means for evaluating the blood pumps and for developing good quality of blood pumps. It was observed that there were four kinds of surface defects on the inner surface of the blood pumps: air bubble domes, open bubble craters, contaminated dust and gel particles. Microcrakes had also been found on the diaphragm of the postimplanted pump. But in the newly improved blood pump that had been imlanted for 16 days, there were few defects on the blood contacting surface, and only a little fibrinous layer observed. It could be considered that the current design and modifications are reasonable. Since some problems associated with the surface defects and thrombosis still existed, further improvement in fabrication process and quality control procedures with SEM are under way.
文摘Common bean (Phaseolus vulgaris L.) is an economic important crop and one of the major grain legumes for human consumption in Latin America, Africa and Asia. A morphological study of shoot induced from embryonic axes development in four Costa Rican bean varieties (Brunca, Huetar, Guaymi and Bribri) cultivated on MS media with or without 5 mg·L–1 de N6-benzylaminopurine (BAP) by scanning electron microscopy (SEM) was developed in the present work. Micrographs showed similarities and differences in the ultrastructure of the apical dome, epidermal surface, stomata and different types of trichomes in the varieties cultivated on organogenesis media. Genotypes with advantageous morphological characteristics for genetic transformation, in particular an exposed apical dome, were identified. This work will contribute to the optimization of the in vitro regeneration of four common bean varieties.
文摘Melanosomes, isolated by centrifugal separation from culture broth of B16 melanoma cells derived from mouse, were observed by scanning electron microscopy (SEM), and by transmission electron microscopy (TEM). Some interesting structural features were found inside and outside of the melanosomes. By SEM observation, the melanosomes were ellipsoid shape, their surface was not smooth and was covered with rough substructure, 10 to 20 nm particles. By TEM, uneven structure and micro particles were observed in the melanosomes. Furthermore, three-dimensional analysis was tried by using the ultra-high voltage electron microscopy(UHVEM). Micrographs of the melanosomes were taken at various tilted angles by UHVEM, after preparing 500 nm thickness specimens stained with lead citrate. From the micrographs collected, the three-dimensional structures were reconstructed by using i-mode software. Melanin stained by lead and non stained parts was clearly observed in the reconstructed structure. Non stained parts were round, regular size, and distributed widely in the melanosomes.
文摘Background: Confirmatory diagnosis of Trypanosoma brucei gambiense human African trypanosomiasis (HAT) is based on demonstration of parasites by microscopy. However, the sensitivity of routine microscopy methods is very low, and many cases are missed and left untreated. A clinical study was conducted in the Democratic Republic of the Congo to evaluate the accuracy of improved microscopy methods in diagnosis of HAT. These included examination by fluorescence microscopy (FM) of acridine orange (AO) stained smears of whole blood and smears made following a new procedure for concentrating trypanosomes by selective lysis of red blood cells (RBC). Methodology/Principal Findings: Venous blood was collected from 213 HAT cases, 101 HAT suspects and 95 controls and used to determine the accuracy of four microscopy methods: bright field microscopy of Giemsa-stained thick blood smears, FM of AO-stained thick blood smears, FM of AO-stained thick blood smears prepared after RBC lysis and concentration, and FM of AO-stained thin blood smears prepared after RBC lysis and concentration. The sensitivity of FM using thick blood smears stained with AO was 3 times higher than bright field microscopy using Giemsa-stained thick blood smears [19.7% (95% CI: 14.9% - 25.6%) versus 6.1% (95% CI: 3.6% - 10.2%)]. When the RBC lysis and concentration procedure was included, sensitivity of the test was further enhanced to 23.0% (95% CI: 17.9% - 29.1%) with thick blood smears and 34.3% (95% CI: 28.2% - 40.9%) with thin blood smears. Specificity of all four microscopy methods was 100% (95% CI: 96.1% - 100.0%). However, the miniature anion exchange chromatography technique (mAECT) and capillary tube centrifugation (CTC) method remained more sensitive. Conclusions: These new methods have practical advantages, including shorter staining time, ease of demonstration of parasites, and the possibility of archiving slides. They could, therefore, be alternative methods to improve case detection where concentration procedures such as mAECT or CTC are not performed.
文摘Diagnosis of Trypanosoma brucei rhodesiense human African trypanosomiasis requires demonstration of parasites in body fluids by microscopy. The microscopy methods that are routinely used are difficult to deploy in resource-limited settings due to practical challenges, including lengthy and tedious procedures, and the need for specific equipment to centrifuge samples in glass capillary tubes. We report here on a study that was conducted in a rural region of eastern Uganda to evaluate new methods that take advantage of a field-deployable LED fluorescence microscope. Examination of acridine orange-stained blood smears by LED fluorescence microscopy resulted in a diagnostic accuracy that was similar to that of routine methods, while the time needed to identify parasites was shortened significantly. These findings make these new microscopy methods attractive alternatives to procedures that are currently used for diagnosis of T. b. rhodesiense human African trypanosomiasis.
文摘The aim of the investigation was to develop the use of topographic and nano-adhesion atomic force microscopy(AFM) studies as a means of monitoring the coalescence of latex particles within films produced from a pharmaceutically relevant aqueous dispersion(Eudragit~?NE30 D). Films were prepared via spin coating and analysed using AFM, initially via tapping mode for topographic assessment followed by force-distance measurements which allowed assessment of site-specific adhesion. The results showed that colloidal particles were clearly observed topographically in freshly prepared samples, with coalescence detected on curing via the disappearance of discernible surface features and a decrease in roughness indices. The effects of temperature and humidity on film curing were also studied, with the former having the most pronounced effect. AFM force measurements showed that the variation in adhesive force reduced with increasing curing time, suggesting a novel method of quantifying the rate of film formation upon curing. It was concluded that the AFM methods outlined in this study may be used as a means of qualitatively and quantitatively monitoring the curing of pharmaceutical films as a function of time and other variables, thereby facilitating rational design of curing protocols.
文摘AIM: To assess potential contributions of biliary IgA for crystal agglomeration into gallstones, we visualized cholesterol crystal binding of biliary IgA. METHODS: Crystal binding biliary proteins were extracted from human gallbladder bile using lectin affinity chromatography.Biliary IgA was isolated from the bound protein fraction by immunoaffinity chromatography. Pure cholesterol monohydrate crystals were incubated with biliary IgA and fluoresceine isothiocyanate (FITC)conjugated anti IgA at 37 degree. Samples were examined under polarizing and fluorescence light microscopy with digital image processing. RESULTS: Binding of biliary IgA to cholesterol monohydrate crystals could be visualized with FITC conjugated anti IgA antibodies.Peak fluorescence occurred at crystal edges and dislocations. Controls without biliary IgA or with biliary IgG showed no significant fluorescence. CONCLUSION: Fluorescence light microscopy provided evidence for cholesterol crystal binding of biliary IgA. Cholesterol crystal binding proteins like IgA might be important mediators of crystal agglomeration and growth of cholesterol gallstones by modifying the evolving crystal structures in vivo.
文摘Surface coatings provide protection to wood products against weathering and other deteriorating factors, such as moisture uptake and microbial invasion. The effectiveness of coatings depends on many factors, including how well the applied coatings adhere to the wood surface. Coating adhesion to wood involves both chemical and physical interactions between the coating and wood tissues in contact, and the particular focus of this mini-review will be on the advances being made in understanding the physical aspects of the interaction by probing wood-coating interface using novel and high resolution imaging techniques, including confocal laser scanning microscopy (CLSM), SEM-backscattered electron imaging and correlative microscopy employing light, confocal and scanning electron microscopy.
