Metabolism of cysteine and cysteinesulfinate in rat and cat hepatocytes

The metabolism of cysteine and cysteinesulfinate was studied in freshly isolated hepatocytes from fed rats and cats. In incubations of rat hepatocytes with cysteinesulfinate, the rate of hypotaurine plus taurine production was approximately the same as the rate of conversion of the 1-carbon of cysteinesulfinate to CO2. In contrast, no significant production of hypotaurine plus taurine occurred in incubations of cat hepatocytes with cysteinesulfinate. These data are consistent with the species difference in the activity of hepatic cysteinesulfinate decarboxylase, which converts cysteinesulfinate to hypotaurine. In incubations of either rat or cat hepatocytes with cysteine, no hypotaurine plus taurine production was detected. However, the 1-carbon of cysteine was converted to CO2 and the production of urea plus ammonia nitrogen was significantly increased over the rates observed in incubations of cells without substrate. Our results suggest that most cysteine oxidation by hepatocytes occurs by pathways that do not involve formation of cysteinesulfinate.     

Collateral vessel regression in a child with primary congenital glaucoma.

The presence of collateral vessels in a young child with glaucoma is rare. The authors describe a case of collateral vessel regression with intraocular pressure reduction in a child with primary congenital glaucoma. Six months following 180 degrees goniotomies in each eye, the intraocular pressure was reduced, dilation of the retinal arteries and veins resolved, and collateral vessels in both eyes regressed. Intraocular pressure reduction may lead to the regression of collateral vessels in children with primary congenital glaucoma.     

Comparison of positive allergy skin tests among asthmatic children from rural and urban areas living within small geographic area.

BACKGROUND: Evidence of increased asthma and allergic response among urban versus rural residents has been reported. OBJECTIVE: To evaluate the prevalence of allergic response among asthmatic children from urban and rural areas living within close proximity. METHODS: In all, 448 asthmatic children from urban (363) and rural (85) areas were studied. The study group consisted of 234 9-year-olds and 214 12-year-olds. A health questionnaire was completed on each child who subsequently underwent allergic skin prick tests (SPTs). RESULTS: There was significantly more positive SPT response to house-dust mite, mold, cat, and cypress among asthmatic children from urban areas compared with children living in rural areas: 58.3% versus 37.6%, 46.1% versus 31.8%, 17.45 versus 5.9%, and 26.2% versus 15.3%, respectively. Positive SPT for indoor allergens were significantly greater among asthmatic urban residents than asthmatic rural residents: 63.3% versus 45.5%, respectively (P < 0.02). Positive SPT response to all the allergens checked was higher among the 12-year-old age group when compared with the 9-year-olds, 34.6% versus 22.7%, respectively (P = 0.05). CONCLUSIONS: Allergic response measured by SPT is significantly more common among asthmatic children from urban areas as opposed to rural, even though both areas are within small distance of one another. Further, asthmatic children living in urban areas demonstrated more allergic response to both indoor and outdoor allergens. The allergic response tends to increase with increased age in both urban and rural asthmatic children.     

Attenuation of insulin-induced drinking by beta-adrenoceptor antagonists.

Insulin-induced drinking (IID) in male Wistar rats, evoked by administering 5 U/kg of crystalline porcine insulin i.p., was significantly decreased by propranolol (0.1 and 0.5 mg/kg s.c.) after 1 and 2 h. The blood glucose of rats treated with a much higher dose of propranolol (10 mg/kg body weight) and insulin did not differ from that of rats treated solely with insulin after 30 and 120 min. Atenolol (0.5 mg/kg s.c.) caused a reduction in IID after 1 and 2h. Butoxamine (1 mg/kg s.c.) also reduced IID after 1 and 2h, and at 0.5 mg/kg after 1h. The alpha-blocker, phenoxybenzamine (10 mg/kg s.c.), had the opposite effect, stimulating IID after 2h. There is no direct evidence that insulin activated the sympathetic system at the doses used in these experiments. Nevertheless, the results reported here seem to be compatible with the involvement of the sympathetic system in IID, possible through the renin-angiotensin system.     

Effect of ritanserin, specific 5HT-2 antagonist, on PRL secretion in normal subjects and in different hyperprolactinaemic conditions

The availability of a new specific anti 5HT-2 compound, ritanserin (RTS), led us to further investigate the role of serotonin in controlling PRL secretion. The drug was administered to normoprolactinaemic subjects and to patients with differing hyperprolactinaemic conditions. While RTS failed to modify PRL levels in normoprolactinaemic subjects and in patients with PRL-secreting pituitary adenomas, a marked decrease in the hormone was obtained in patients with functional and puerperal hyperprolactinaemia. The lack of effect of RTS in PRL-secreting pituitary adenomas suggests that the reported suppression of PRL by other antiserotoninergic drugs, such as metergoline, is probably due to their concomitant dopaminergic activity.     

Evidence that tolerance to cultured thyroid allografts is an active immunological process. Protection of third-party grafts bearing new antigens when associated with tolerogenic antigens.

We studied the tolerance phenomenon that develops in long-term recipients of cultured thyroid allografts. Allogeneic mouse thyroids were cultured under hyperbaric oxygen or acidic conditions and then transplanted beneath the kidney capsule of C57BL/6 recipients. Donors differed from the recipients in minor antigens alone, major histocompatibility complex antigens alone, or both. At 35-77 weeks after the first cultured graft, recipients received two more cultured grafts under the capsule of the opposite kidney and were immunized with donor spleen cells (SC). At 5 weeks after the second transplantation, we observed that whereas second grafts carrying new antigens alone were rejected, second grafts carrying new antigens in association with antigens in the first graft were significantly protected. In another set of experiments, normal mice became tolerant to cultured allografts after 2 weeks in parabiosis with tolerant individuals. Tolerant mice showed reduced specific in vivo and in vitro cytotoxic T lymphocyte responses. However, the frequency of CTL precursors of tolerant mice was the same as in normal mice. The reduced in vitro CTL responses were restored to normal levels by the addition of a lymphokine rich medium. Also, we observed that the injection of specifically activated immune SC caused the rejection of cultured allografts in normal but not in tolerant recipients. We conclude that the tolerance that develops in recipients of cultured allografts is an active immunological process that affects the activation and effector function of CTL.