Animal models of middle ear surgery help us to explore disease processes and intervention outcomes in a manner not possible in patients. This review begins with an overview of animal models of middle ear surgery which...Animal models of middle ear surgery help us to explore disease processes and intervention outcomes in a manner not possible in patients. This review begins with an overview of animal models of middle ear surgery which outlines the advantages and limitations of such models. Procedures of interest include myringoplasty/tympanoplasty, mastoidectomy, ossiculoplasty, stapedectomy, and active middle ear implants. The most important issue is how well the model reflects the human response to surgery. Primates are most similar to humans with respect to anatomy; however, such studies are uncommon now due to expense and ethical issues. Conversely, small animals are easily obtained and housed, but experimental findings may not accurately represent what happens in humans. We then present a systematic review of animal models of middle ear surgery. Particular attention is paid to any distinctive anatomical features of the middle ear, the method of accessing the middle ear and the chosen outcomes. These outcomes are classified as either physiological in live animals,(e.g., behavioural or electrophysiological responses), or anatomical in cadaveric animals,(e.g., light or electron microscopy). Evoked physiological measures are limited by the disruption of the evoking air-conducted sound across the manipulated middle ear. The eleven identified species suitable as animal models are mouse, rat, gerbil, chinchilla, guinea pig, rabbit, cat, dog, sheep, pig and primate. Advantages and disadvantages of each species as a middle ear surgical model are outlined, and a suggested framework to aid in choosing a particular model is presented.展开更多
Introduction:Ethiopia has made efforts to tackle the challenges of low crop and livestock productivity and degradation of land resources through various rural development strategies.However,increasing demands for food...Introduction:Ethiopia has made efforts to tackle the challenges of low crop and livestock productivity and degradation of land resources through various rural development strategies.However,increasing demands for food,animal feed,fuel,and income-generating activities are putting pressure on the land.In this paper,we describe the production pressure and competition between crop and livestock production,quantify rates of land-use/cover(LULC)changes,and examine driving forces and consequences of land conversion.Methods:The study was conducted in Gudo Beret watershed,North Shewa Zone of Amhara region,Ethiopia.It used a combination of methods including remote sensing,household interviews,field observations,focus group discussions,and key informant interviews.Supervised and unsupervised image classification methods were employed to map LULC classes for 31 years(1984–2016).Results:The results of satellite remote sensing revealed that 51%of the land in the study area was subject to accelerated land conversions.The household survey results indicated that feed resources and grain production pressures were 1.43 and 1.34 t ha^(−1) respectively.The observed annual changes in plantation and settlement areas were 2.6%and 2.9%.This was mainly at the expense of bushland and grazing land systems.Cropland increased(0.4%year^(−1))while grazing land reduced(3.5%year^(−1))under contrasting dynamics and competitive changes.An increase in human and livestock populations and farm expansion were major drivers of land conversion that adversely affected household livelihoods and the natural ecosystem.The consequences of these pressures resulted in a lack of animal feed,low crop-livestock productivity,and a reduction in natural vegetation coverage.Conclusions:We suggest that sustainable land resource management,more integrated crop-livestock production,and the use of productivity-enhancing technologies could play a role in managing competition for land resources.展开更多
文摘Animal models of middle ear surgery help us to explore disease processes and intervention outcomes in a manner not possible in patients. This review begins with an overview of animal models of middle ear surgery which outlines the advantages and limitations of such models. Procedures of interest include myringoplasty/tympanoplasty, mastoidectomy, ossiculoplasty, stapedectomy, and active middle ear implants. The most important issue is how well the model reflects the human response to surgery. Primates are most similar to humans with respect to anatomy; however, such studies are uncommon now due to expense and ethical issues. Conversely, small animals are easily obtained and housed, but experimental findings may not accurately represent what happens in humans. We then present a systematic review of animal models of middle ear surgery. Particular attention is paid to any distinctive anatomical features of the middle ear, the method of accessing the middle ear and the chosen outcomes. These outcomes are classified as either physiological in live animals,(e.g., behavioural or electrophysiological responses), or anatomical in cadaveric animals,(e.g., light or electron microscopy). Evoked physiological measures are limited by the disruption of the evoking air-conducted sound across the manipulated middle ear. The eleven identified species suitable as animal models are mouse, rat, gerbil, chinchilla, guinea pig, rabbit, cat, dog, sheep, pig and primate. Advantages and disadvantages of each species as a middle ear surgical model are outlined, and a suggested framework to aid in choosing a particular model is presented.
基金This study was financially supported by the United States Agency for International Development(USAID)through Africa RISING research program.
文摘Introduction:Ethiopia has made efforts to tackle the challenges of low crop and livestock productivity and degradation of land resources through various rural development strategies.However,increasing demands for food,animal feed,fuel,and income-generating activities are putting pressure on the land.In this paper,we describe the production pressure and competition between crop and livestock production,quantify rates of land-use/cover(LULC)changes,and examine driving forces and consequences of land conversion.Methods:The study was conducted in Gudo Beret watershed,North Shewa Zone of Amhara region,Ethiopia.It used a combination of methods including remote sensing,household interviews,field observations,focus group discussions,and key informant interviews.Supervised and unsupervised image classification methods were employed to map LULC classes for 31 years(1984–2016).Results:The results of satellite remote sensing revealed that 51%of the land in the study area was subject to accelerated land conversions.The household survey results indicated that feed resources and grain production pressures were 1.43 and 1.34 t ha^(−1) respectively.The observed annual changes in plantation and settlement areas were 2.6%and 2.9%.This was mainly at the expense of bushland and grazing land systems.Cropland increased(0.4%year^(−1))while grazing land reduced(3.5%year^(−1))under contrasting dynamics and competitive changes.An increase in human and livestock populations and farm expansion were major drivers of land conversion that adversely affected household livelihoods and the natural ecosystem.The consequences of these pressures resulted in a lack of animal feed,low crop-livestock productivity,and a reduction in natural vegetation coverage.Conclusions:We suggest that sustainable land resource management,more integrated crop-livestock production,and the use of productivity-enhancing technologies could play a role in managing competition for land resources.
