Aim: To evaluate the effect of tamoxifen citrate on male reproductive system of rat. Methods: Groups of male rats were gavaged with tamoxifen at doses of 200 mg·kg-1·d-1, 400 mg·kg-1·d-1 or 800 mg&...Aim: To evaluate the effect of tamoxifen citrate on male reproductive system of rat. Methods: Groups of male rats were gavaged with tamoxifen at doses of 200 mg·kg-1·d-1, 400 mg·kg-1·d-1 or 800 mg·kg-1·d-1 in 0.1 mL olive oil for 10 consecutive days. Controls were treated with 0.1 mL olive oil. Rats were anesthetized and killed on d 3, d 15 or d 35 after the last dose. Testes were collected, processed for paraffin embedding, sectioned at 5 μm thickness, stained with H&E and analyzed microscopically. Results: There was a dose-dependent increase in the occurrence of seminiferous tubular distortion with germinal cell sloughing. The highest dose increased the number of multinucleated giant cells on d 3 and d 15. Conclusion: Tamoxifen citrate induces multinucleated giant cells and germinal epithelial sloughing in a dose-dependent manner and these changes are detrimental to male fertility.展开更多
As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be tre...As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be treated as a ma- terial of varying transverse isotropy. In this Part, the elastic stress-strain relations and the quadratic strength criterion are established in the form of having varying transverse isotropy, in the framework of micromechanics to take into account of the effect of the microstructures-dentin tubules. Simplified forms for isotropic and ho- mogeneous cases, as well as the corresponding plane stress form of the stress-strain relations are also given. These theoretical models are very well supported by the experiments shown later in the continued paper (Part Ⅱ).展开更多
Precise regulation of stem cell self-renewal versus differentiation is important for the maintenance of tissue ho- meostasis. Early loss of stem cell activity results in premature ageing, while excess stem cell activi...Precise regulation of stem cell self-renewal versus differentiation is important for the maintenance of tissue ho- meostasis. Early loss of stem cell activity results in premature ageing, while excess stem cell activity leads to over- proliferation and cancer initiation （Fuchs et al., 2004; Scadden, 2006; Jones and Wagers, 2008; Morrison and Spradling, 2008）. Thus, understanding the mechanism con- trolling stem cell self-renewal and differentiation is critical for development of potential clinic therapy in the future.展开更多
Imitating a real tooth and the periodontal supporting tissues, we have established a 2D finite element model and carried out a numerical analysis based on the inhomogeneous and anisotropic (IA) stress-strain relation ...Imitating a real tooth and the periodontal supporting tissues, we have established a 2D finite element model and carried out a numerical analysis based on the inhomogeneous and anisotropic (IA) stress-strain relation and strength model of dentin proposed in the preceding Parts Ⅰ and Ⅱ, and the conventional homogeneous and isotropic (HI) model, respectively. Quite a few cases of loadings for a non-defected and a defected tooth are considered. The numerical results show that the stress level predicted by the IA model is remarkably higher than that by the HI model, revealing that the effect of the dentin tubules should be taken into a serious consideration from the viewpoint of biomechanics.展开更多
To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it ...To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin.In this paper,by the digital speckle correlation method,tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules.With the theoretically predicted elastic stress-strain relations,an optimiza- tion method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations.The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5GPa and 0.44,respectively,in the optimization sense.展开更多
Objective: To demonstrate the relation sh ip between actin phosphorylation and actin sequestration in ATP-depleted rabbi t renal proximal tubules. Methods: Using two-dimensional electr ophoreses and Western blotting t...Objective: To demonstrate the relation sh ip between actin phosphorylation and actin sequestration in ATP-depleted rabbi t renal proximal tubules. Methods: Using two-dimensional electr ophoreses and Western blotting to analyze the phosphorylation state of the seque stered actin in rabbit renal proximal tubules. Results: The anal ytical result of the sequestered actin indicated that nearly half of the actin w as phosphorylated on serine residue(s). Conclusion: Result sugge sted a close correlation between actin sequestration and actin phosphorylation i n ATP-depleted rabbit renal proximal tubules.展开更多
Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment ...Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment success despite many chemical and physical therapies. Methods: Four coronal dentin disks 2 mm thick were cut with a low-speed diamond saw from four freshly extracted intact first molars. The coronal dentin surface of each disk was divided into four regions, each approximately 2 mm × 3 mm. The dentin surfaces were treated with 27% EDTA then the four regions irradiated separately in a randomized pattern with a Nd:YAG laser (120 mJ, 5 Hz), using irradiation times of 0 s, 20 s, 40 s and 60 s, representing laser energies of 0 J/cm2, 200 J/cm2, 400 J/cm2 and 600 J/cm2, respectively. SEM photomicro-graphs were taken at 1500× and 3000× to calculate the dentinal tubule orifice occlusion rates and to measure the tubule diameters, respectively. Results: For the laser irradiation times of 0 s, 20 s, 40 s and 60 s, the corresponding dentinal tubule occlusion rates were 2.05 (SD 0.29)%, 10.01 (1.71)%, 23.58 (2.51)% and 90.23 (2.24)%, respectively;and the tubule diameters were 4.18 (0.32) μm, 3.46 (0.24) μm, 1.69 (0.32) μm and 0.12 (0.02) μm, respectively. There were significant differences among all groups for both measured variables (p ≤ 0.005). Conclusions: Within the limitations of this in Vitro study, when using a Nd:YAG laser at 120 mJ and 5 Hz, an irradiation time of 60 s achieved the best sealing of the coronal dentinal tubule orifices.展开更多
The morphological transition of molecular assemblies in aqueous solutions for a new amphiphilic diblock copolymer induced by changing the initial solvent conditions was studied by transmission electron microscopy (TEM...The morphological transition of molecular assemblies in aqueous solutions for a new amphiphilic diblock copolymer induced by changing the initial solvent conditions was studied by transmission electron microscopy (TEM). The copolymer was polystyrene(77)-b-poly[2-(beta -D-glucopyranosyloxy)ethyl acrylate (6)] (PSt(77)-b-PGEA(6)) and the solvent was a mixture of DMF and THF. PSt(77)-b-PGEA(6) yields vesicles and tubules when it is initially dissolved in THF and DMF respectively. The morphological transition between vesicles and tubules can be achieved by simply varying the amounts of THF and DMF, or changing the temperature at which the aggregates were prepared.展开更多
Objective To investigate whether germ like cells isolated from embryoid body formed by mouse embryonic stem cells could survive and initiate spermatogenesis in seminiferous tubules of adult mice. Methods SSEA-1＋ cell...Objective To investigate whether germ like cells isolated from embryoid body formed by mouse embryonic stem cells could survive and initiate spermatogenesis in seminiferous tubules of adult mice. Methods SSEA-1＋ cells were isolated from embryoid bodies prepared from mouse EGFP-ES cells, after retinoic acid treatment, the cells were detected for the expression of alkaline phosphatase, Rnh2, stella, fragilis, Tex14, Sry, Hsp90-a, Stra8 and integrin a6, and then, the cells were transplanted into seminiferous tubules of busulfan-treated adult mice. Results Six days after retinoic acid treatment, alkaline phosphatase expressing cells could still be found in embryoid body （EB） derived cells, indicating the existence of retinoic acid-resistant primordial germ cells. When the SSEA-1＋ cells isolated from embryoid bodies were stimulated with retinoic acid for 6 days, some of these cells expressed cell markers of Hsp90-a, Stra8 and integrin a6, resembling the expression profile of spermatogonial stem cells. Forty-five days after cell transplantation, a little amount of GFP-expressing cells attached to the basement membrane of seminiferous tubule and formed small colonies; Three months later, these cells started amplification in the form of cell chains with varied length, and moving towards the lumen of the seminiferous tubules. Five months after the transplantation, multilayered cell mass was found in seminiferous tubules of two, out of four recipient mice. There was no GFP-expressing cells existed in non-cell-transplanted seminiferous tubules. Conclusion In our study, although full-termed spermatogenesis was not observed in all of the recipients, the results did indicate that the embryoid body contains germ like cells, and these cells can survive and initiate amplification in seminiferous tubules of adult mouse.展开更多
Since the first electron micrograph of“lace-like structures”over 75 years ago,the endoplasmic reticulum(ER)is now viewed as a highly dynamic,constantly remodeling,continuous network of tubules and cisternae that pla...Since the first electron micrograph of“lace-like structures”over 75 years ago,the endoplasmic reticulum(ER)is now viewed as a highly dynamic,constantly remodeling,continuous network of tubules and cisternae that plays an important role in a broad range of cellular activities from calcium regulation to protein synthesis and trafficking.In neurons,the ER extends from the soma through the axon to presynaptic terminals,and throughout the dendritic arbor into as many as half of all postsynaptic dendritic spines at any given time(Falahati et al.,2022).展开更多
Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental e...Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental evidence supports the statements.Here,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine hypersensitivity.The in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine hypersensitivity.Furthermore,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine hypersensitivity.Therefore,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical applications.The proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.展开更多
Malpighian tubules (MTs)are moregulatory organs of insects.However, usually considered the key excretory and os- increasing evidence has suggested that MTs perform many more functions than just osmoregulation.Until no...Malpighian tubules (MTs)are moregulatory organs of insects.However, usually considered the key excretory and os- increasing evidence has suggested that MTs perform many more functions than just osmoregulation.Until now,the molecular and physiological functions of MTs in the cotton bollworm (Helicoverpa armigera),a very important agricultural pest,are largely unknown.In this study,the transcriptomes of H. armigera MTs from larvae,male adults and female adults were sequenced using RNA-Seq technology,and comparative analyses of transcriptomes between two life stages (larval and adult)and between adult sexes were conducted.We generated a total of 84 643 high-quality unigenes,and identified a large number of abundant transcripts putatively encoding proteins involved in diuresis,detoxification,immunity,carbohydrate transport and metabolism,development and reproduction.We found that the expression pattern of unigenes was relatively similar between female and male adult MTs,but different between larval and adult MTs.Our data suggest that insect MTs may take multiple physiological fimctions as versatile organs.The extensive alterations in gene expression in MTs occurred from larvae to adults reflect an ecological adaptation to different feeding habits.Sexual dimorphism in the cotton bollworm is somewhat indicated by the transcriptional difference of genes related to carbohydrate metabolism,detoxification,immunity and reproduction in the MTs of male and female adults.展开更多
Ⅰ. INTRODUCTION Ever since Sabatini improved on the fixing method for the electron microscope with glutaradehyde instead of osmic acid and permanganate potassinm, the microtubules have been generally found in eukaryo...Ⅰ. INTRODUCTION Ever since Sabatini improved on the fixing method for the electron microscope with glutaradehyde instead of osmic acid and permanganate potassinm, the microtubules have been generally found in eukaryocytes, as reported by Tilney and Heplar et al. A microtubule is a fine tubule of about 210—270 in diameter and it is an important cell organelle, supporting the cells and making them move. It is said to be 'the展开更多
Acute kidney injury(AKI)is a significant global health issue with limited current treatment options.This study focused on the mechanism by which exosomes derived from bone marrow mesenchymal stem cells(BMSCs)promote r...Acute kidney injury(AKI)is a significant global health issue with limited current treatment options.This study focused on the mechanism by which exosomes derived from bone marrow mesenchymal stem cells(BMSCs)promote renal tubule regeneration in AKI through the regulation of the PTEN signaling pathway by miR-21.BMSCs were isolated and characterized,and their exosomes were purified.In vitro,renal tubular epithelial cell injury models were established,and the co-culture of exosomes and cells demonstrated enhanced cell proliferation and reduced apoptosis.In vivo,AKI animal models showed improved renal function and histopathological changes after exosome treatment.miR-21 was found to be upregulated in exosomes and recipient cells,targeting PTEN and activating the PI3K/AKT pathway.The signaling network also interacted with other pathways related to renal tubule regeneration.The study highlights the potential of exosome therapy for AKI and provides insights into the underlying molecular mechanisms,although further research is needed to address remaining challenges and translate these findings into clinical applications.展开更多
Dear Editor,I would like to congratulate Mamsen et al.i on their extensive and scientifically valuable work.I analyzed their raw data presented in Table 1 of the original article from a different perspective and disco...Dear Editor,I would like to congratulate Mamsen et al.i on their extensive and scientifically valuable work.I analyzed their raw data presented in Table 1 of the original article from a different perspective and discovered an effect not mentioned in the article.My analysis showed that luteinizing hormone(LH)levels are significantly lower in patients at high infertility risk(HIR),whose testes lack A dark(Ad)spermatogonia and display an abnormal ratio of germ cells per crosssectional tubule(G/T).展开更多
Renal tubules regulate blood pressure and humoral homeostasis. Mediators that play a significant role in regulating the transport of solutes and water include angiotensin Ⅱ （AngⅡ） and nitric oxide （NO）. AngⅡca...Renal tubules regulate blood pressure and humoral homeostasis. Mediators that play a significant role in regulating the transport of solutes and water include angiotensin Ⅱ （AngⅡ） and nitric oxide （NO）. AngⅡcan signifcantly raise blood pressure via effects on the heart, vasculature, and renal tubules. AngⅡ generally stimulates sodium reabsorption by triggering sodium and fuid retention in almost all segments of renal tu-bules. Stimulation of renal proximal tubule （PT） trans-port is thought to be essential for AngⅡ-mediated hy-pertension. However, AngⅡ has a biphasic effect on in vitro PT transport in mice, rats, and rabbits： stimulation at low concentrations and inhibition at high concentra-tions. On the other hand, NO is generally thought to inhibit renal tubular transport. In PTs, NO seems to be involved in the inhibitory effect of AngⅡ. A recent study reports a surprising fnding： AngⅡ has a mono-phasic stimulatory effect on human PT transport. De-tailed analysis of signalling mechanisms indicates that in contrast to other species, the human NO/guanosine 3’,5’-cyclic monophosphate/extracellular signal-regulat-ed kinase pathway seems to mediate this effect of Ang Ⅱ on PT transport. In this review we will discuss recent progress in understanding the effects of AngⅡ and NO on renal tubular transport.展开更多
A theoretical investigation on the structural and elastic properties of ZnO nanotubes is carried out by using atomistic calculations based on an inter-atomic pair potential within the shell-model approach. The calcula...A theoretical investigation on the structural and elastic properties of ZnO nanotubes is carried out by using atomistic calculations based on an inter-atomic pair potential within the shell-model approach. The calculation results are presented for the bond length, bond angle, radius dilation, strain energy, Young modulus and Poisson ratio as a function of tube radius. For small tube radius these properties depend on the helicity of the tube, while for the tube radius larger than 6.0A, they are independent of the tube radius and helicity except for the strain energy which decreases with increasing tube radius.展开更多
Aim: To study the contraceptive effect of the crude extracts of Curcuma longa in male albino rats. Methods: Rats were fed orally with Curcuma longa aqueous and 70 % alcoholic extract for 60 days (500 mg·kg-1·...Aim: To study the contraceptive effect of the crude extracts of Curcuma longa in male albino rats. Methods: Rats were fed orally with Curcuma longa aqueous and 70 % alcoholic extract for 60 days (500 mg·kg-1· day-1). Results: A reduction in sperm motility and density was observed in both the treated groups. Conclusion: Curcuma longa may have affected the androgen synthesis either by inhibiting the Leydig cell function or the hypo-thalamus pituitary axis and as a result, spermatogenesis is arrested.展开更多
Background:Female sperm storage(FSS),the maintenance of sperm inside the female reproductive tract for an extended period of time,is pervasive among organisms with internal fertilization.Because FSS enables asynchrono...Background:Female sperm storage(FSS),the maintenance of sperm inside the female reproductive tract for an extended period of time,is pervasive among organisms with internal fertilization.Because FSS enables asynchronous mating and fertilization,it could be extremely important to reproduction.However,the physiological mechanisms underlying prolonged preservation and maintenance are poorly understood.Here,we used chicken,a typical oviparous animal,to determine the mechanisms ensuring sperm functionality in sperm storage tubules(SSTs).Results:We performed an insemination experiment on over two thousand hens at two periods,and found that the FSS capabilities varied widely among individuals.Except for the differences in the SST density between the two groups with distinct FSS abilities,we quantitatively profiled small-molecule metabolites derived from SST cells,and identified 28 metabolites with differential expression.In particular,high levels of lipids,fatty acids and lipid peroxidation product were observed in hens with low FSS capability.Pathway analysis showed that these differential metabolites were significantly enriched in the biosynthesis of unsaturated fatty acids.Moreover,we detected the total antioxidant capacity and lipid peroxidation level of SSTs,and found that chickens with a lower FSS ability had a significantly higher content of lipid peroxidation end-product,which was 2.4-fold greater than chickens with a higher FSS capability,and no significant difference was found in the total antioxidant capacity between these two groups.Conclusions:Our findings reveal that the long-term storage of sperm and the maintenance of their function in the female reproductive tract require an adequate microenvironment.The superabundance of fatty acids secreted by SST cells had detrimental effects on sperm storage in the female reproductive tract.Lipid peroxidation produces toxic biological substances that may cause irreversible damage to resident spermatozoa,resulting in short-term sperm retention and decreased fertility.Our findings provide new avenues for studying sperm storage and sustaining fertility.展开更多
Carbon monoxide（CO）,as a vital small molecule in signaling pathways,is found to be involved in ischemia-reperfusion injury（IRI） in renal transplantation.CO-releasing molecule-2（CORM-2）,a CO-releasing molecule,is...Carbon monoxide（CO）,as a vital small molecule in signaling pathways,is found to be involved in ischemia-reperfusion injury（IRI） in renal transplantation.CO-releasing molecule-2（CORM-2）,a CO-releasing molecule,is a type of metal carbonyl complexes which can quickly release CO in vivo.In this study,an in vitro oxidative stress injury model was established to examine the effect of CORM-2 pretreatment on the nuclear-cytoplasmic translocation of high mobility group box 1 protein（HMGB1） in mouse primary renal proximal tubular epithelial cells（RPTECs）.Immunofluorescence staining showed that HMGB1 in the medium-and CORM-2-treated groups was predominantly localized in the nucleus of the cells,whereas higher amounts of HMGB1 translocated to the cytoplasm in the H2O2-and inactive CORM-2（i CORM-2）-treated groups.Western blotting of HMGB1 showed that the total amounts of cytoplasmic HMGB1 in the H2O2-treated（0.59±0.27） and i CORM-2-treated（0.57±0.22） groups were markedly higher than those in the medium-treated（0.19±0.05） and CORM-2-treated（0.21±0.10） groups（P〈0.05）.Co-immunoprecipitation showed that the levels of acetylated HMGB1 in the H2O2-treated（642.98±57.25） and i CORM-2-treated（342.11±131.25） groups were markedly increased as compared with the medium-treated（78.72±74.17） and CORM-2-treated（71.42±53.35） groups（P〈0.05）,and no significant difference was observed between the medium-treated and CORM-2-treated groups（P〉0.05）.In conclusion,our study demonstrated that in the in vitro oxidative stress injury model of primary RPTECs,CORM-2 can significantly inhibit the nuclear-cytoplasmic translocation of HMGB1,which is probably associated with the prevention of HMGB1 acetylation.展开更多
文摘Aim: To evaluate the effect of tamoxifen citrate on male reproductive system of rat. Methods: Groups of male rats were gavaged with tamoxifen at doses of 200 mg·kg-1·d-1, 400 mg·kg-1·d-1 or 800 mg·kg-1·d-1 in 0.1 mL olive oil for 10 consecutive days. Controls were treated with 0.1 mL olive oil. Rats were anesthetized and killed on d 3, d 15 or d 35 after the last dose. Testes were collected, processed for paraffin embedding, sectioned at 5 μm thickness, stained with H&E and analyzed microscopically. Results: There was a dose-dependent increase in the occurrence of seminiferous tubular distortion with germinal cell sloughing. The highest dose increased the number of multinucleated giant cells on d 3 and d 15. Conclusion: Tamoxifen citrate induces multinucleated giant cells and germinal epithelial sloughing in a dose-dependent manner and these changes are detrimental to male fertility.
基金The project supported by the National Natural Science Foundation of China (19525207).
文摘As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be treated as a ma- terial of varying transverse isotropy. In this Part, the elastic stress-strain relations and the quadratic strength criterion are established in the form of having varying transverse isotropy, in the framework of micromechanics to take into account of the effect of the microstructures-dentin tubules. Simplified forms for isotropic and ho- mogeneous cases, as well as the corresponding plane stress form of the stress-strain relations are also given. These theoretical models are very well supported by the experiments shown later in the continued paper (Part Ⅱ).
基金supported by the grants from the National Natural Science Foundation of China(Nos.31271582 and 31471384)Temasek Life Sciences Laboratory and Singapore Millennium FoundationBeijing Municipal Commission of Education (No.010135336400)
文摘Precise regulation of stem cell self-renewal versus differentiation is important for the maintenance of tissue ho- meostasis. Early loss of stem cell activity results in premature ageing, while excess stem cell activity leads to over- proliferation and cancer initiation （Fuchs et al., 2004; Scadden, 2006; Jones and Wagers, 2008; Morrison and Spradling, 2008）. Thus, understanding the mechanism con- trolling stem cell self-renewal and differentiation is critical for development of potential clinic therapy in the future.
基金The project supported by the National Natural Science Foundation of China (19525207, 19891180)the Tsinghua University Fundamental Research Foundation (Jc1999033)
文摘Imitating a real tooth and the periodontal supporting tissues, we have established a 2D finite element model and carried out a numerical analysis based on the inhomogeneous and anisotropic (IA) stress-strain relation and strength model of dentin proposed in the preceding Parts Ⅰ and Ⅱ, and the conventional homogeneous and isotropic (HI) model, respectively. Quite a few cases of loadings for a non-defected and a defected tooth are considered. The numerical results show that the stress level predicted by the IA model is remarkably higher than that by the HI model, revealing that the effect of the dentin tubules should be taken into a serious consideration from the viewpoint of biomechanics.
基金The project supported by the National Natural Science Foundation of China(19525207)
文摘To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work(Part Ⅰ),we per- form a set of experiments.Because of the very fine tooth size,it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin.In this paper,by the digital speckle correlation method,tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules.With the theoretically predicted elastic stress-strain relations,an optimiza- tion method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations.The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5GPa and 0.44,respectively,in the optimization sense.
基金National Institute of Diabetes and Digestive and Kidney Diseases (R15DK56599 01)(USA) to Dr. Jing Chen
文摘Objective: To demonstrate the relation sh ip between actin phosphorylation and actin sequestration in ATP-depleted rabbi t renal proximal tubules. Methods: Using two-dimensional electr ophoreses and Western blotting to analyze the phosphorylation state of the seque stered actin in rabbit renal proximal tubules. Results: The anal ytical result of the sequestered actin indicated that nearly half of the actin w as phosphorylated on serine residue(s). Conclusion: Result sugge sted a close correlation between actin sequestration and actin phosphorylation i n ATP-depleted rabbit renal proximal tubules.
文摘Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment success despite many chemical and physical therapies. Methods: Four coronal dentin disks 2 mm thick were cut with a low-speed diamond saw from four freshly extracted intact first molars. The coronal dentin surface of each disk was divided into four regions, each approximately 2 mm × 3 mm. The dentin surfaces were treated with 27% EDTA then the four regions irradiated separately in a randomized pattern with a Nd:YAG laser (120 mJ, 5 Hz), using irradiation times of 0 s, 20 s, 40 s and 60 s, representing laser energies of 0 J/cm2, 200 J/cm2, 400 J/cm2 and 600 J/cm2, respectively. SEM photomicro-graphs were taken at 1500× and 3000× to calculate the dentinal tubule orifice occlusion rates and to measure the tubule diameters, respectively. Results: For the laser irradiation times of 0 s, 20 s, 40 s and 60 s, the corresponding dentinal tubule occlusion rates were 2.05 (SD 0.29)%, 10.01 (1.71)%, 23.58 (2.51)% and 90.23 (2.24)%, respectively;and the tubule diameters were 4.18 (0.32) μm, 3.46 (0.24) μm, 1.69 (0.32) μm and 0.12 (0.02) μm, respectively. There were significant differences among all groups for both measured variables (p ≤ 0.005). Conclusions: Within the limitations of this in Vitro study, when using a Nd:YAG laser at 120 mJ and 5 Hz, an irradiation time of 60 s achieved the best sealing of the coronal dentinal tubule orifices.
基金This work was partially supported by the National Natural Science Foundation of China (No. 29995648-4 and 59603004).
文摘The morphological transition of molecular assemblies in aqueous solutions for a new amphiphilic diblock copolymer induced by changing the initial solvent conditions was studied by transmission electron microscopy (TEM). The copolymer was polystyrene(77)-b-poly[2-(beta -D-glucopyranosyloxy)ethyl acrylate (6)] (PSt(77)-b-PGEA(6)) and the solvent was a mixture of DMF and THF. PSt(77)-b-PGEA(6) yields vesicles and tubules when it is initially dissolved in THF and DMF respectively. The morphological transition between vesicles and tubules can be achieved by simply varying the amounts of THF and DMF, or changing the temperature at which the aggregates were prepared.
基金supported by grants from the Natural Science Foundation of Guangdong Province (No. 5001351)
文摘Objective To investigate whether germ like cells isolated from embryoid body formed by mouse embryonic stem cells could survive and initiate spermatogenesis in seminiferous tubules of adult mice. Methods SSEA-1＋ cells were isolated from embryoid bodies prepared from mouse EGFP-ES cells, after retinoic acid treatment, the cells were detected for the expression of alkaline phosphatase, Rnh2, stella, fragilis, Tex14, Sry, Hsp90-a, Stra8 and integrin a6, and then, the cells were transplanted into seminiferous tubules of busulfan-treated adult mice. Results Six days after retinoic acid treatment, alkaline phosphatase expressing cells could still be found in embryoid body （EB） derived cells, indicating the existence of retinoic acid-resistant primordial germ cells. When the SSEA-1＋ cells isolated from embryoid bodies were stimulated with retinoic acid for 6 days, some of these cells expressed cell markers of Hsp90-a, Stra8 and integrin a6, resembling the expression profile of spermatogonial stem cells. Forty-five days after cell transplantation, a little amount of GFP-expressing cells attached to the basement membrane of seminiferous tubule and formed small colonies; Three months later, these cells started amplification in the form of cell chains with varied length, and moving towards the lumen of the seminiferous tubules. Five months after the transplantation, multilayered cell mass was found in seminiferous tubules of two, out of four recipient mice. There was no GFP-expressing cells existed in non-cell-transplanted seminiferous tubules. Conclusion In our study, although full-termed spermatogenesis was not observed in all of the recipients, the results did indicate that the embryoid body contains germ like cells, and these cells can survive and initiate amplification in seminiferous tubules of adult mouse.
基金supported by AHA Career Development Award 938683 (to PJD)NIH grant R01MH123700 (to MLD)
文摘Since the first electron micrograph of“lace-like structures”over 75 years ago,the endoplasmic reticulum(ER)is now viewed as a highly dynamic,constantly remodeling,continuous network of tubules and cisternae that plays an important role in a broad range of cellular activities from calcium regulation to protein synthesis and trafficking.In neurons,the ER extends from the soma through the axon to presynaptic terminals,and throughout the dendritic arbor into as many as half of all postsynaptic dendritic spines at any given time(Falahati et al.,2022).
基金We thank the National Key R&D Program of China(No.2020YFA0710401)the National Natural Science Foundation of China(Nos.82225012,81922019,82071161,81991505,22122207,21988102,and 52075138)+1 种基金the Young Elite Scientist Sponsorship Program by CAST(No.2020QNRC001)the Beijing Nova Program(No.211100002121013).
文摘Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental evidence supports the statements.Here,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine hypersensitivity.The in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine hypersensitivity.Furthermore,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine hypersensitivity.Therefore,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical applications.The proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.
基金grants fom National Natural Science Foundation of China[No.31601644] and the State Key Laboratory of Integrated Management of Pest Insects and Rodents[No.ChineseIPM1502].
文摘Malpighian tubules (MTs)are moregulatory organs of insects.However, usually considered the key excretory and os- increasing evidence has suggested that MTs perform many more functions than just osmoregulation.Until now,the molecular and physiological functions of MTs in the cotton bollworm (Helicoverpa armigera),a very important agricultural pest,are largely unknown.In this study,the transcriptomes of H. armigera MTs from larvae,male adults and female adults were sequenced using RNA-Seq technology,and comparative analyses of transcriptomes between two life stages (larval and adult)and between adult sexes were conducted.We generated a total of 84 643 high-quality unigenes,and identified a large number of abundant transcripts putatively encoding proteins involved in diuresis,detoxification,immunity,carbohydrate transport and metabolism,development and reproduction.We found that the expression pattern of unigenes was relatively similar between female and male adult MTs,but different between larval and adult MTs.Our data suggest that insect MTs may take multiple physiological fimctions as versatile organs.The extensive alterations in gene expression in MTs occurred from larvae to adults reflect an ecological adaptation to different feeding habits.Sexual dimorphism in the cotton bollworm is somewhat indicated by the transcriptional difference of genes related to carbohydrate metabolism,detoxification,immunity and reproduction in the MTs of male and female adults.
文摘Ⅰ. INTRODUCTION Ever since Sabatini improved on the fixing method for the electron microscope with glutaradehyde instead of osmic acid and permanganate potassinm, the microtubules have been generally found in eukaryocytes, as reported by Tilney and Heplar et al. A microtubule is a fine tubule of about 210—270 in diameter and it is an important cell organelle, supporting the cells and making them move. It is said to be 'the
文摘Acute kidney injury(AKI)is a significant global health issue with limited current treatment options.This study focused on the mechanism by which exosomes derived from bone marrow mesenchymal stem cells(BMSCs)promote renal tubule regeneration in AKI through the regulation of the PTEN signaling pathway by miR-21.BMSCs were isolated and characterized,and their exosomes were purified.In vitro,renal tubular epithelial cell injury models were established,and the co-culture of exosomes and cells demonstrated enhanced cell proliferation and reduced apoptosis.In vivo,AKI animal models showed improved renal function and histopathological changes after exosome treatment.miR-21 was found to be upregulated in exosomes and recipient cells,targeting PTEN and activating the PI3K/AKT pathway.The signaling network also interacted with other pathways related to renal tubule regeneration.The study highlights the potential of exosome therapy for AKI and provides insights into the underlying molecular mechanisms,although further research is needed to address remaining challenges and translate these findings into clinical applications.
文摘Dear Editor,I would like to congratulate Mamsen et al.i on their extensive and scientifically valuable work.I analyzed their raw data presented in Table 1 of the original article from a different perspective and discovered an effect not mentioned in the article.My analysis showed that luteinizing hormone(LH)levels are significantly lower in patients at high infertility risk(HIR),whose testes lack A dark(Ad)spermatogonia and display an abnormal ratio of germ cells per crosssectional tubule(G/T).
文摘Renal tubules regulate blood pressure and humoral homeostasis. Mediators that play a significant role in regulating the transport of solutes and water include angiotensin Ⅱ （AngⅡ） and nitric oxide （NO）. AngⅡcan signifcantly raise blood pressure via effects on the heart, vasculature, and renal tubules. AngⅡ generally stimulates sodium reabsorption by triggering sodium and fuid retention in almost all segments of renal tu-bules. Stimulation of renal proximal tubule （PT） trans-port is thought to be essential for AngⅡ-mediated hy-pertension. However, AngⅡ has a biphasic effect on in vitro PT transport in mice, rats, and rabbits： stimulation at low concentrations and inhibition at high concentra-tions. On the other hand, NO is generally thought to inhibit renal tubular transport. In PTs, NO seems to be involved in the inhibitory effect of AngⅡ. A recent study reports a surprising fnding： AngⅡ has a mono-phasic stimulatory effect on human PT transport. De-tailed analysis of signalling mechanisms indicates that in contrast to other species, the human NO/guanosine 3’,5’-cyclic monophosphate/extracellular signal-regulat-ed kinase pathway seems to mediate this effect of Ang Ⅱ on PT transport. In this review we will discuss recent progress in understanding the effects of AngⅡ and NO on renal tubular transport.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10025420, 10574121 and 90406024, the Ministry of Education of China, and Chinese Academy of Sciences.
文摘A theoretical investigation on the structural and elastic properties of ZnO nanotubes is carried out by using atomistic calculations based on an inter-atomic pair potential within the shell-model approach. The calculation results are presented for the bond length, bond angle, radius dilation, strain energy, Young modulus and Poisson ratio as a function of tube radius. For small tube radius these properties depend on the helicity of the tube, while for the tube radius larger than 6.0A, they are independent of the tube radius and helicity except for the strain energy which decreases with increasing tube radius.
文摘Aim: To study the contraceptive effect of the crude extracts of Curcuma longa in male albino rats. Methods: Rats were fed orally with Curcuma longa aqueous and 70 % alcoholic extract for 60 days (500 mg·kg-1· day-1). Results: A reduction in sperm motility and density was observed in both the treated groups. Conclusion: Curcuma longa may have affected the androgen synthesis either by inhibiting the Leydig cell function or the hypo-thalamus pituitary axis and as a result, spermatogenesis is arrested.
基金This work was supported by Programs for Changjiang Scholars and Innovative Research in Universities(IRT_15R62)China Agriculture Research Systems(No.CARS_40).
文摘Background:Female sperm storage(FSS),the maintenance of sperm inside the female reproductive tract for an extended period of time,is pervasive among organisms with internal fertilization.Because FSS enables asynchronous mating and fertilization,it could be extremely important to reproduction.However,the physiological mechanisms underlying prolonged preservation and maintenance are poorly understood.Here,we used chicken,a typical oviparous animal,to determine the mechanisms ensuring sperm functionality in sperm storage tubules(SSTs).Results:We performed an insemination experiment on over two thousand hens at two periods,and found that the FSS capabilities varied widely among individuals.Except for the differences in the SST density between the two groups with distinct FSS abilities,we quantitatively profiled small-molecule metabolites derived from SST cells,and identified 28 metabolites with differential expression.In particular,high levels of lipids,fatty acids and lipid peroxidation product were observed in hens with low FSS capability.Pathway analysis showed that these differential metabolites were significantly enriched in the biosynthesis of unsaturated fatty acids.Moreover,we detected the total antioxidant capacity and lipid peroxidation level of SSTs,and found that chickens with a lower FSS ability had a significantly higher content of lipid peroxidation end-product,which was 2.4-fold greater than chickens with a higher FSS capability,and no significant difference was found in the total antioxidant capacity between these two groups.Conclusions:Our findings reveal that the long-term storage of sperm and the maintenance of their function in the female reproductive tract require an adequate microenvironment.The superabundance of fatty acids secreted by SST cells had detrimental effects on sperm storage in the female reproductive tract.Lipid peroxidation produces toxic biological substances that may cause irreversible damage to resident spermatozoa,resulting in short-term sperm retention and decreased fertility.Our findings provide new avenues for studying sperm storage and sustaining fertility.
基金supported by the National Natural Science Foundation of China(No.81300574)
文摘Carbon monoxide（CO）,as a vital small molecule in signaling pathways,is found to be involved in ischemia-reperfusion injury（IRI） in renal transplantation.CO-releasing molecule-2（CORM-2）,a CO-releasing molecule,is a type of metal carbonyl complexes which can quickly release CO in vivo.In this study,an in vitro oxidative stress injury model was established to examine the effect of CORM-2 pretreatment on the nuclear-cytoplasmic translocation of high mobility group box 1 protein（HMGB1） in mouse primary renal proximal tubular epithelial cells（RPTECs）.Immunofluorescence staining showed that HMGB1 in the medium-and CORM-2-treated groups was predominantly localized in the nucleus of the cells,whereas higher amounts of HMGB1 translocated to the cytoplasm in the H2O2-and inactive CORM-2（i CORM-2）-treated groups.Western blotting of HMGB1 showed that the total amounts of cytoplasmic HMGB1 in the H2O2-treated（0.59±0.27） and i CORM-2-treated（0.57±0.22） groups were markedly higher than those in the medium-treated（0.19±0.05） and CORM-2-treated（0.21±0.10） groups（P〈0.05）.Co-immunoprecipitation showed that the levels of acetylated HMGB1 in the H2O2-treated（642.98±57.25） and i CORM-2-treated（342.11±131.25） groups were markedly increased as compared with the medium-treated（78.72±74.17） and CORM-2-treated（71.42±53.35） groups（P〈0.05）,and no significant difference was observed between the medium-treated and CORM-2-treated groups（P〉0.05）.In conclusion,our study demonstrated that in the in vitro oxidative stress injury model of primary RPTECs,CORM-2 can significantly inhibit the nuclear-cytoplasmic translocation of HMGB1,which is probably associated with the prevention of HMGB1 acetylation.
