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Identification and Targeting of Collagen in the Capsule of Rat Knees with Immobilization-Induced Flexion ContracturesWong, Kayleigh January 2015 (has links)
Immobility causes joint contractures, loss in range of motion (ROM), notably in elderly and bed-ridden patients. In a rat knee immobilization flexion contracture (FC) model, the posterior capsule contributes to irreversible limitation of ROM. Through microarray, extracellular matrix and collagen pathways were identified as differentially expressed in the posterior capsule of knees with FC. We hypothesized that intra-articular injection of collagenases in rats with knee FC will interfere with collagen in the capsule and allow increased ROM. After four weeks of hind-limb immobilization, rats develop knee FC; two weeks of remobilization with collagenase treatment showed increased ROM compared to buffer injected knees of 8.043° (p-value=0.046). Histological analysis of knee sections revealed changes in collagen content of the extracellular matrix in posterior capsule. In vitro incubation of rat capsules with collagenases confirmed changes in collagen. Along with current rehabilitation methods, treatment with collagenase may augment ROM recovery from knee joint contractures.
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A study of the brush border peptidases of the rat small intestineJackson, Mel C. January 1988 (has links)
No description available.
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Applications of a radioimmunoassay technique to the study of luteinizing hormone secretion in the ratQuerido, David 14 April 2020 (has links)
A sensitive and reproducible double antibody radioimmunoassay technique, requiring 50ul of unknown serum or plasma per assay tube, is described for use with 125I and rabbit anti-rat LH serum. The assay system was applied to the study of LH secretion in rats under both normal and experimentally manipulated conditions. Particular attention was focussed upon comparison of circulating LH levels in conscious, unstressed animals with those in anaesthetized animals, with or without surgical stress. Thereafter, the effects of acoustic stimulation and of exogenous LRH administration were studied in conscious and anaesthetized animals. Urethane anaesthesia exerted a profound effect upon the LR-secretory response to exogenous LRH in male rats. Available evidence suggests that the blood sampling
method, surgical stress and anaesthesia are each capable of significantly influencing LH secretion, thereby emphasizing the value of studies using conscious, unstressed animals. While a direct effect of urethane on the pituitary gland cannot be excluded, attention is drawn to the possible mediation of a urethane-sensitive inhibitory influence in the mechanism controlling LH secretion in the rat.
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Factors influencing hydroxylations of labeled steroid precursors by different rat adrenal preparationsLee, David S. January 1970 (has links)
No description available.
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Hypothalamic hypoactivity prevented but not reversed by subdiaphragmatic vagotomy.Eng, Ricardo 01 January 1978 (has links) (PDF)
No description available.
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Emergence of stimulus bound drinking with a reinforcement contingency,Lewis, Herman Henderson 01 January 1975 (has links) (PDF)
No description available.
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A Laboratory Evaluation of NorbormideMedina, Abraham B. January 1966 (has links)
No description available.
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An Experimental Study of Dispersal of the Cotton Rat, SIGMODON HISPIDUSStafford, Stephen R. 01 April 1981 (has links) (PDF)
Dispersal of cotton rats was examined over an annual cycle of abundance by removal trapping in pine flatwoods. All cotton rats live-trapped at biweekly intervals on two 0.49 ha grids were removed, whereas rats on an adjacent control grid were tagged an released alive on site. The null hypothesis was that dispersing cotton rats would represent a random sample of sex and weight (age) classes from source populations, e.g. the control grid. Likewise, it was assumed that dispersal rates would be proportional to numerical changes in abundance on the control grid. Dispersing animals were clearly most prevalent on the removal grids during November and December 1979 when numbers of rats on the control grid were increasing. Breeding ceased in December and fewer animals dispersed between January and May. The cumulative number of individual animals captured or removed from the study grids (control and removals) was remarkably similar. The proportion of individuals removed according to weight class was not significantly different among grids. Sex ratios of rats on the control and removal grids were not different from 50:50 (P > 0.05). The conclusion is that dispersing cotton rats represented a cross-section of age groups and sexes. The results support the rank-order template hypothesis as the dispersal strategy of the cotton rat. Genetic and behavioral differences between dispersers and source populations could not be discriminated with the methodology employed.
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Nest-Building Behavior and Food Habits of the Rice Rat, Oryzomys Palustris Natator from Merritt Island, Brevard County, FloridaHarrison, Margaret Hart 01 January 1974 (has links) (PDF)
No description available.
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Neocortical Long-Term Depression and Depotentiation in the Adult Freely Moving RatFroc, David January 2002 (has links)
Information is believed to be stored in the brain by constructing new neural circuits, and these circuits are shaped by changes in the strength of the synaptic connections between the neurons making up the circuit. According to most theories of memory, new circuits can be formed by either increasing or decreasing the strength of synaptic connections. Bidirectional modifications in synaptic efficacy are also central components in recent computer simulations of learning and memory. While long-term potentiation (LTP) has been the focus of extensive research into the mechanisms underlying information storage in the mammalian brain, long-term depression (LTD) and depotentiation, its depressive counterparts, have not. Furthermore, most of the LTD research has involved the use of anaesthetized animals and in vitro slice preparations, making it more difficult to determine the role of this synaptic phenomenon in learning and memory in the intact behaving animal. This thesis provides the first detailed examination of: 1) the induction and decay of both LTD and depotentiation in the neocortex of the awake, freely moving animal; 2) the effects of N-methyl D-Aspartate receptor (NMDAR) blockade on the induction of LTD, LTP, and depotentiation (NMDA receptor activation is known to play a major role in most forms of LTP); and 3) the interactions between these synaptic phenomena. LTD was expressed as a significant reduction in the amplitude of both short and long-latency field potential components. Depotentiation was expressed as a long lasting decrease in the amplitude of a previously enhanced late component. LTD was found to be greater in magnitude and longer lasting when the conditioning stimulation was repeated. However, unlike LTP induction, the conditioning stimulation was equally effective whether spaced over hours or days. NMDA receptor antagonism blocked LTP induction and instead produced a depression effect similar to LTD. Unlike LTP, LTD and depotentiation were found to be NMDAR-independent in the neocortex of the freely moving rat. LTP and LTD are both reversible phenomena and LTD-inducing stimulation can modulate the effects of LTP-inducing stimulation. LTD-inducing stimulation, when delivered following to LTP-inducing stimulation, attenuates the induction rate for potentiation. LTD and depotentiation may play important roles in the ongoing experience-induced modification of neuronal connectivity. Furthermore, these results are consistent with the hypothesis that potentiation and depression reflect the physiological instantiation of a bidirectional learning rule. / Thesis / Doctor of Philosophy (PhD)
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