by Shinichi Watanabe. / Vita. / Thesis (M.S.) - Florida State University. / Bibliography: leaves 87-96.

To determine the effects of different social conditions on play and agonistic behaviour, 25-day old golden hamsters and Mongolian gerbils were divided into four groups which differed with respect to social experience after weaning. Every day, from 26 to 61 days of age, the young hamsters were observed for numbers and durations of fight-type interactions in a 15-minute period. Every third or sixth day from 27 to 60 days of age, the gerbils were similarly tested. Seven to 14 percent of play fights between hamsters involved more than two animals simultaneously. Communally reared hamsters mixed with strangers played with strangers 71 percent of the time, while 90 percent of real fights involved strangers. Neither of these measures involved the effects of early social experience. Isolation causes earlier cessation of play and earlier onset of real fights in golden hamsters. Isolation also leads to a significant increase in the amount of play and real fighting in these animals. Gerbils raised in isolation with a toy show significantly more play than do gerbils reared under different social conditions. Gerbils reared communally with the mother fight significantly more with strangers than they do with familar animals, and fight significantly more than do animals reared communally with siblings, or in isolation with or without a ping pong ball. / Science, Faculty of / Zoology, Department of / Graduate

Decreased respiratory muscle strength and/or excessive loads imposed on the respiratory muscles by disease may result in respiratory muscle fatigue and ventilatory failure. Once the respiratory muscles fatigue, the only treatment is rest by mechanical ventilation. However, no one has yet determined the best protocol of rest. The purpose of these studies was to develop an animal model in the hamster in order to examine the time course of recovery following fatigue of the diaphragm and specifically, to test whether mechanical ventilation or spontaneous unloaded breathing was a better mode for functional recovery. The studies required the initial development of an anesthetic regimen which produced minimal respiratory depression in the hamster. A new method of stimulating the diaphragm in small animals was developed by apposing plate electrodes directly against the diaphragm. The validity of this technique was examined and comparison of the mechanical and electrophysiological response to that of phrenic nerve stimulation were similar at maximal stimulation. The histological characteristics of the normal hamster diaphragm were determined for fibre type proportions and sizes, oxidative capacity and glycogen levels in the costal and crural regions of this muscle. The examination revealed three distinct areas of the diaphragm with different histological features: the abdominal surface of the crural region, the thoracic surface of the crural region and the sternal and costal region. Diaphragmatic fatigue was induced in vivo by repetitive electrical stimulation which resulted in both high and low frequency fatigue. The fatigue stimulus also produced muscle fibre damage, primarily along the abdominal surface of the diaphragm over the electrodes, and glycogen depletion in the type lib fibres. Rest by continuous mechanical ventilation resulted in recovery of high frequency fatigue in the hamster diaphragm whereas rest by spontaneous unloaded breathing resulted in no recovery. Sham fatigue groups rested by either mechanical ventilation or spontaneous breathing demonstrated progressive deterioration in transdiaphragmatic pressure throughout the rest period. Decreased muscle fibre damage but increased inflammation and glycogen depletion was demonstrated in all four fatigue/sham fatigue and rest groups compared to that demonstrated by the fatigue/sham fatigue only groups. The results suggest that passive rest by continuous mechanical ventilation promotes recovery following fatigue induced by electrical stimulation. Additional factors such as prolonged fasting, loads imposed on the diaphragm by the plate electrode apparatus, positive pressure ventilation, and cumulative effects of intraperitoneal urethane likely contributed to the progressive deterioration of diaphragmatic function demonstrated in the animals of the two sham groups rested by either spontaneous breathing or mechanical ventilation, and confounded the results shown by the two fatigue groups rested by either spontaneous breathing or mechanical ventilation. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Apparatus has been developed for the irradiation of V79-379A Chinese hamster lung fibroblast cells with 3.6 MeV protons from the Van de Graaff accelerator at the National Accelerator Centre in Faure. The original intention of this work was to investigate and measure a possible dose rate effect on the survival of V79 cells, in the dose range from zero to 25 Gy, at dose rates of about 3 Gy/s and 300 Gy/s. The survival curves initially obtained were anomalous in that they showed abnormally high levels of survival and a tendency to remain at a constant survival level for doses above 10 Gy. Systematic attempts to correct this observed anomaly, involved the following; apparatus improvements were made, a means of measuring the beam profile was devised, the current measuring device and the dosimetry were improved and a possible dose rate effect on intracellular oxygen was investigated. After these improvements, the anomalous effect was much reduced, but not entirely eliminated. The final results showed no significant difference between the survival of cells irradiated at dose rates of about 3 Gy/s and 300 Gy/s; qualitative differences were however noticeable. After correction for the effect of a non-uniform beam profile, the survival curves were significantly different to published work. This difference suggested a possible dose rate effect between dose rates of about 0.1 Gy/s and dose rates above 3 Gy/s.

No description available.

No description available.

Pineal-mediated depressions in prolactin cell activity after light deprivation were studied in the male and female Golden Syrian hamster. Prolactin cell activity was determined by measuring radioimmunoassayable prolactin, newly synthesized prolactin and prolactin mRNA levels in the pituitary. Serum prolactin was also measured by radioimmunoassay. Use of the recombinant DNA plasmid, pPRL-1, which contains the rat prolactin complimentary DNA sequence, was validated in this dissertation for measuring prolactin mRNA in the hamster. Male hamsters blinded for 11, 21, or 42 days showed significant and progressively greater declines in prolactin mRNA levels which were completely prevented by pinealectomy. The decline seen after 11 days is the earliest depression in prolactin cell activity reported after light deprivation in the hamster. Female hamsters blinded for 28 days, however, showed no such decreases in prolactin cell activity if they continued to display estrous cyclicity. This supports the hypothesis that, unlike the male, there is not a gradual decline in prolactin cell activity after blinding in the female hamster and that loss of estrous cyclicity may precede or possibly accompany declines in prolactin cell activity. After 12 weeks of blinding, females were acyclic and had dramatically depressed levels of prolactin cell activity. However, pinealectomy did not completely prevent this decline due to blinding unless the females continue to display estrous cyclicity. Thus, when pinealectomy was ineffective in preventing the loss of estrous cyclicity due to blinding, it was also ineffective in preventing declines in prolactin cell activity. In ovariectomized females, blinding caused a decline in prolactin cell activity. Pinealectomy was not consistently effective in preventing this decline after 12 weeks of treatment, although, in females blinded for 4 weeks (at which time all animals were cycling) and then ovariectomized for an additional 4 weeks, pinealectomy completely prevented this decline in prolactin cell activity. In a separate study, significant changes in prolactin cell activity during the estrous cycle were seen in untreated normally cycling female hamsters. These changes in prolactin mRNA, prolactin synthesis, and radioimmunoassayable prolactin in the pituitary were measured in the morning, when, consistent with other reports, no differences in serum prolactin were observed.

O hamster sírio é utilizado como modelo experimental que permite explorar aspectos fisiopatológicos e avaliar a resposta terapêutica em diversas cardiopatias, algumas delas não tão bem reproduzidas em ratos. A avaliação cardiológica inclui a observação de aspectos fisiológicos e hemodinâmicos, assim como a utilização de exames complementares para análise estrutural e funcional cardíaca in vivo. Dentre esses exames destaca-se a ecocardiografia, que possibilita a avaliação da estrutura e função com elevada acurácia. Uma das formas de análise da função sistólica é por meio do cálculo da fração de ejeção do ventrículo esquerdo (FEVE), que leva em consideração os volumes estimados diastólico final e sistólico final do ventrículo esquerdo. Outro importante parâmetro de análise de função sistólica é a avaliação da deformação miocárdica. Os índices de deformação miocárdica podem ser obtidos utilizando o método de rastreamento de pontos. No entanto, até o presente momento, não existem dados a respeito de valores de referência a serem utilizados para a deformação miocárdica em hamsters. Diante disso, o presente estudo teve como objetivo definir a exequibilidade, os intervalos de referência e a variabilidade de parâmetros derivados da ecocardiografia convencional e da técnica de rastreamento de pontos em hamsters sírios adultos. Métodos: Foram incluídos no estudo 135 hamsters sírios fêmeas, anestesiados com ketamina/xilazina e submetidos à ecocardiografia em aparelho dedicado a pequenos animais, Vevo® 2100 utilizando transdutor linear de 30 MHz. Resultados: A exequibilidade da realização das medidas de ecocardiografia convencional foi superior a 93%. A análise da deformação endocárdica apresentou exequibilidade de 84% no eixo longo e, de 80% no eixo curto. A avaliação da deformação epicárdica nos eixos longo e curto apresentou baixa exequibilidade (42% e 62%, respectivamente). A FEVE pelo modo M, obtida no eixo longo, foi significativamente superior à obtida pelos métodos de área comprimento e de rastreamento de pontos (59,0±5,8; 53,8±4,7; 46,3±5,7; p<0,0001). Houve razoável correlação positiva da FEVE obtida pelos métodos de área comprimento e de rastreamento de pontos (r= +0,43; p<0,0001). A deformação longitudinal endocárdica global foi de -13,6(-7,5; -20,4)%, a deformação circunferencial endocárdica global foi de -20,5±3,1% e a deformação radial endocárdica global foi de +34,7±7,0%. A análise de regressão linear evidenciou influência da frequência cardíaca nos valores de deformação longitudinal e circunferencial, mas não da deformação radial (p=0,0003; p<0,0001 e p=0,83, respectivamente). Conclusões: Demonstrou-se que as medidas de ecocardiografia convencional e pelo método de rastreamento de pontos são exequíveis em hamsters. Foram definidos intervalos de referência para variáveis de ecocardiografia convencional e da deformação endocárdica global longitudinal, circunferencial e radial neste modelo experimental animal. / The Syrian hamster is an experimental model to study pathophysiology and to assess therapeutic response in several heart diseases, some of them not well reproduced in rats. The cardiologic evaluation includes observation of physiological and hemodynamic patterns, and complementary tests are used for in vivo cardiac structural and functional analysis. Among these, echocardiography allows the evaluation of structure and function with high accuracy. Analyzing systolic function can be done by calculating the left ventricular ejection fraction. Another important parameter of systolic function analysis is the assessment of the myocardial strain. Myocardial strain indices can be obtained using speckle tracking. However, there are no data regarding reference values for myocardial strain in hamsters. The present study aimed to determine feasibility, reference intervals and variability of parameters derived from conventional and speckle tracking echocardiography in adult Syrian hamsters. Methods: The study included 135 female Syrian hamsters anesthetized with ketamine/xylazine and submitted to a small animal dedicated echocardiography, Vevo® 2100 using a 30 MHz linear transducer. Results: The analysis of the endocardial strain presented a feasibility of 84% in the long axis and 80% in the short axis. The evaluation of the epicardial strain in the long and short axes presented low feasibility (42% and 62%, respectively). The M-mode left ventricular ejection fraction obtained on the long axis was significantly higher than that obtained by the area-length and Speckle tracking methods (59.0±5.8, 53.8±4.7, 46.3±5.7, p<0.0001). There was a reasonable positive correlation of left ventricular ejection fraction obtained by the area length method and the Speckle tracking method (r=+0.43; p<0.0001). The endocardial longitudinal strain was -13.6(-7.5;-20.4)%, the endocardial circumferential strain was -20.5±3.1% and the endocardial radial strain was +34,7±7.0%. Linear regression analysis showed influence of heart rate on the values of longitudinal and circumferential strain, but not on radial strain (p=0.0003, p<0.0001 and p=0.83, respectively). Conclusions: it has been shown that measurements of conventional echocardiography and speckle tracking are feasible in hamsters. Reference intervals for conventional echocardiographic variables and longitudinal, circumferential and radial global endocardial strain were obtained in this experimental animal model.

Introdução Os feijões comuns, da espécie Phaseolus vulgaris, são amplamente produzidos e consumidos no Brasil. As variedades, carioca e preto ganham destaque na região Sudeste do país. Encontra-se descrita na literatura a ação hipocolesterolemizante de algumas leguminosas, tais como, soja, tremoço e feijão caupi, que podem estar associados à redução do risco de doenças cardiovasculares. Objetivo Avaliar o potencial efeito da adição de farinhas de feijões carioca e preto (Phaseolus vulgaris) no metabolismo lipídico de hamsters alimentados com dieta contendo gordura saturada e colesterol. Métodos A produção das farinhas dos feijões envolveu as etapas de autoclavagem, congelamento, liofilização e moagem. As propriedades hipocolesterolemizantes destas farinhas foram avaliadas por meio de dois ensaios biológicos. Foram utilizados hamsters Golden Syrian, machos com 21 dias, pesando 60 ± 4g, que receberam as dietas experimentais ad libitum. No Ensaio A, os animais foram separados em 3 grupos, diferenciados pela dieta. Todas as dietas eram hipercolesterolemizantes [13.5 por cento de gordura de coco e 0.1 por cento colesterol] e tinham as mesmas quantidades de proteínas, carboidratos, fibras, vitaminas e minerais. O Grupo Controle (C) tinha como fonte protéica a caseína; no Grupo Feijão Carioca (FC) a farinha de feijão carioca representou 15 por cento do peso total da dieta e no Grupo Feijão Preto a farinha de feijão preto representou 15 por cento do peso total da dieta. No Ensaio B, os animais foram separados em três grupos novamente. Desta vez, a única diferença entre os grupos foi quanto a fonte protéica, para o grupo controle (C) somente caseína, para o grupo feijão carioca (FC), 67 por cento de feijão e 7,5 por cento de caseína e para o grupo feijão preto (FP), 62 por cento de feijão e 7,5 por cento de caseína. Nos dois ensaios, após 21 dias de experimento, foi realizada coleta de materiais biológicos (plasma, fígado e fezes). Resultados O processo de produção das farinhas de feijões cozidas liofilizadas não alterou a composição centesimal das matérias-primas. A análise de fibras alimentares revelou que não há diferenças entre os cultivares Pérola e Uirapuru. No Ensaio A, as concentrações de colesterol não HDL e HDL colesterol foram maiores nos grupos que receberam feijão de maneira significativa. Quanto aos demais parâmetros plasmáticos não foram observadas diferenças entre os grupos. No Ensaio B as concentrações plasmáticas de triglicerídeos foram maiores no grupo FP. As concentrações de HDL colesterol foram maiores nos grupos FP e FC, sendo estatisticamente significativa para o feijão carioca em relação ao grupo controle. As excreções fecais de ácidos biliares foram maiores no grupo FC e a de colesterol no grupo C. A determinação de lipídeos totais no fígado não revelou diferenças entre os grupos, dados que corroboraram com a análise do grau de esteatose nos fígados, a qual demonstrou desenvolvimento de acúmulo de lipídeos nos hepatócitos dos animais dos três grupos. O teste qui quadrado mostrou que as variáveis grau de esteatose e tipo de dieta, assim como tipo de dieta e grau de inflamação portal hepática são independentes. Já o grau de inflamação parenquimatosa hepática está associado ao tipo de dieta e o feijão carioca mostrou-se capaz de reduzir em 30 por cento o risco de desenvolver esteatoepatite severa. Conclusões Os feijões não foram capazes de proteger contra o aumento do colesterol total, triglicérides e colesterol não HDL no plasma, mas mesmo na presença de gordura saturada e colesterol na dieta, o feijão carioca foi capaz de aumentar a HDL, mostrando que o mecanismo de remoção do colesterol plasmático foi preservado. O feijão carioca mostrou-se eficaz na proteção contra a inflamação parenquimatosa hepática severa. / Carioca and black beans are the varieties of Phaseolus vulgaris most consumed on Brazil Southwest. It is well described that some legumes, as soy and cowpea beans, have hypocholesterolaemic effects. To test cholesterol-lowering properties of carioca and black beans, two biological assays were conducted. Golden Syrian hamsters, 21 days old, were housed individually under 12 h light-dark cycle and temperature-controlled environment, with free access to food and water. There was a adaptation period of 6 days, before the start of experimental period. In Assay A, the animals (n=19) were randomly assigned to three distinct groups. All groups received a hypercholesterolaemic diet (13.5 per cent coconut oil and 0.1 per cent cholesterol) and similar amounts of proteins, carbohydrates, fiber, vitamins and minerals to suit the animal requirements. Control group received casein as the only protein source; Carioca bean group received 15 per cent of carioca bean flour and casein to complement protein requirement and Black bean group received 15 per cent of black bean flour and casein to complement protein requirement. After 21 days, the experimental period was over and liver, blood and feces were collected. In Assay B, all groups also received a hypercholesterolaemic diet (13.5 per cent coconut oil and 0.1 per cent cholesterol). In this assay the only difference between groups (n=27) was protein source: casein for control group, and the others received carioca (67 per cent ) or black bean whole seed flour (62 per cent ) plus 7,5 per cent of casein. The beans flours obtained showed no differences in chemical composition. In Assay A, plasma HDL cholesterol and non-HDL cholesterol were higher in Carioca bean group and Black bean group. The other plasma parameters had no differences. In assay B, plasma triglyceride was higher in Black bean group. The HDL cholesterol was increased in both beans groups, and was significant in Carioca group. Fecal excretion of bile acids was higher in animals of Carioca bean group. Fecal excretion of cholesterol was higher in Control group. There were no differences between groups in total liver lipid concentration, data supporting the steatosis analysis in livers. The chi-square test showed that the type of experimental diet and steatosis grade were independents, also the portal hepatic inflammation was not associated with the experimental diets. The parenchymal inflammation of the liver was associated with Carioca bean group, which showed that the chance of developing severe inflammation was 30 per cent lower in carioca bean group compared with Control group. Beans had no cholesterol-lowering effect, but the HDL increases in plasma and lower inflammation in Carioca bean group deserves further investigation.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.