Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Injection of rats with cyclophosphamide (CY) after their consumption of a novel saccharin-flavored drinking solution results in a conditioned aversion to saccharin and a conditioned suppression of immune responses. In this study, female Lewis X Brown Norwegian F1 rats were conditioned by pairing saccharin with 50 mg/kg CY. Seven weeks later (day 0), a graft-vs-host response (GvHR) was induced in these animals by injecting splenic leukocytes from Lewis donors into a rear footpad. At this time, some conditioned animals were reexposed to saccharin, the conditioned stimulus. During the 7-wk interval between conditioning and immunization, subgroups of conditioned rats were given 0, 4, 9, or 18 extinction trials (saccharin followed by saline injections). Animals receiving 4, 9, or 18 extinction trials showed a greater preference for saccharin on day 0 than did animals receiving no extinction trials, but these groups did not differ among themselves; all conditioned groups showed a lower preference for saccharin than placebo-treated animals. There was a clear effect of number of extinction trials on the GvHR. Animals receiving 9 or 18 extinction trials did not differ from controls, whereas animals receiving 0 or 4 trials had a milder GvHR than did conditioned rats that were not reexposed to saccharin at the time of immunization. These results confirm a previous report of conditioned suppression of a GvHR, demonstrate that conditioned immunopharmacologic responses are subject to experimental extinction, and indicate that conditioned immunosuppression can be dissociated from conditioned taste aversion.
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PMID:Acquisition and extinction of conditioned suppression of a graft-vs-host response in the rat. 660 62

Heterotopic, vascularized small intestine transplants were performed in inbred strains of rats to investigate the structural, functional, and immunologic consequences of intestinal transplantation with and without immunosuppression with cyclosporine (CyA). Lewis X Brown Norway F1 intestine was rejected by untreated Lewis recipients in 7 to 10 days. Structurally, rejected intestine was characterized by shortened crypts and villi lined by damaged attenuated epithelial cells. Functionally, rejection was associated with impaired epithelial active ion transport as indicated by decreased potential difference and with diminished epithelial barrier function as reflected by decreased transepithelial resistance. Administration of CyA for 7 days prevented clinical rejection and partially prevented the structural and functional defects. Lewis intestine transplanted into Lewis X Brown Norway F1 recipients caused fatal graft versus host disease (GVHD) in 9 to 17 days. Treatment with CyA for 7 days failed to prevent GVHD routinely, but prolonged administration delayed fatal GVHD until CyA was discontinued. Intestine from Lewis "B" rats made deficient of T cells by thymectomy, irradiation, and reconstitution with syngeneic T cell-depleted bone marrow failed to cause GVHD in Lewis recipients. Reconstitution of the "B" rats with T cells before transplantation restored the GVHD response. These results may be relevant in the consideration of clinical small intestinal transplantation.
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PMID:Small intestine transplantation in the rat--immunology and function. 661 97

This laboratory has used a composite tissue allograft model as a vehicle for studies on a new type of bone marrow transplant, the vascularized bone marrow transplant. The model consists of a rat hind limb transplant that incorporates integumentary musculoskeletal, and lymphopoietic tissues. These transplants, in comparison with conventional marrow transplants, have the advantage of providing a syngeneic microenvironment and immediate engraftment of both mature and progenitor hemopoietic cells at the time of transplantation. The characteristics of graft-versus-host disease were studied in this model. Lewis X Brown Norway F1 (LBN RT-1(1+n)) rats received hind limbs from Lewis (LEW RT-1(1)) donors (n = 19). Animals were observed daily for signs of graft-versus-host disease. Necropsies were performed. A minority of animals developed lethal disease (7 of 19 recipients) and demonstrated cachexia with concomitant histopathologic changes of the disease. Acute and chronic groups emerged with distinct clinical courses, which are similar to other models of this disease. Recipients of vascularized bone marrow transplants (limb transplants) showed clinical and histopathologic changes of the disease. The transplants may be used as a model of graft-versus-host disease in humans. Most interestingly, the transplant has a lower incidence of disease compared with other methods of bone marrow transplantation and represents an alternative to conventional bone marrow transplantation, which deserves further exploration. It may be possible to develop a new technique for bone marrow transplantation based on this surgical approach. It is proposed that the transfer of vascularized blocks of bone/marrow into prospective recipients as opposed to cellular bone marrow transplants may be preferable.
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PMID:Composite tissue allografts in rats: IV. Graft-versus-host disease in recipients of vascularized bone marrow transplants. 1051 19

Presbycusis, or age-related hearing loss is a growing problem as the general population ages. In this longitudinal study, the influence of noise or styrene exposure on presbycusis was investigated in Brown Norway rats. Animals were exposed at 6 months of age, either to a band noise centered at 8 kHz at a Lex,8h = 85 dB (86.2 dB SPL for 6 h), or to 300 ppm of styrene for 6 h per day, five days per week, for four weeks. Cubic distortion product otoacoustic emissions (2f1-f2 DPOAEs) were used to test the capacity of the auditory receptor over the lifespan of the animals. 2f1-f2DPOAE measurements are easy to implement and efficiently track the age-related deterioration of mid- and high-frequencies. They are good indicators of temporary auditory threshold shift, especially with a level of primaries close to 60 dB SPL. Post-exposure hearing defects are best identified using moderate, rather than high, levels of primaries. Like many aging humans, aging rats lose sensitivity to high-frequencies faster than to medium-frequencies. Although the results obtained with the styrene exposure were not entirely conclusive, histopathological data showed the presbycusis process to be enhanced. Noise-exposed rats exhibit a loss of spiral ganglion cells from 12 months and a 7 dB drop in 2f1-f2DPOAEs at 24 months, indicating that even moderate-intensity noise can accelerate the presbycusis process. Even though the results obtained with the styrene exposure are less conclusive, the histopathological data show an enhancement of the presbycusis process.
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PMID:Impact of noise or styrene exposure on the kinetics of presbycusis. 2161 32


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