Carnosine modulates zinc and copper effects on amino acid receptors and synaptic transmission

Carnosine is a dipeptide which is highly concentrated in mammalian olfactory sensory neurons along with zinc and/or copper, and glutamate. Although carnosine has been proposed as a neurotransmitter or neuromodulator, no specific function for carnosine has been identified. We used whole-cell current- and voltage-clamp recording to examine the direct effects and neuromodulatory actions of carnosine on rat olfactory bulb neurons in primary culture. Carnosine did not evoke a membrane current or affect currents evoked by glutamate, GABA or glycine. Copper and zinc inhibited NMDA and GABA receptor-mediated currents and inhibited synaptic transmission. Carnosine prevented the actions of copper and reduced the effects of zinc. These results suggest that carnosine may indirectly influence neuronal excitability by modulating the effects of zinc and copper.     

Conclusive evidence for distinct transporters for 5-hydroxytryptamine and noradrenaline in pulmonary endothelial cells of the rat

The aims of this study were to obtain conclusive evidence about the roles of a 5-hydroxytryptamine [5-HT] transporter and uptake1 in the dissipation of 5-HT in the lungs of the rat and to compare the properties of the 5-HT transporter in rat lungs with that in other tissues, including brain and platelets. In the first part of the study, the IC50 values of a range of selective inhibitors and substrates of the 5-HT transporter or uptake1 were determined for inhibition of uptake of 5-HT or noradrenaline in intact perfused lungs of rats. Monoamine oxidase was inhibited and, in experiments with noradrenaline, catechol-O-methyltransferase was also inhibited. Initial rates of uptake of 5-HT or noradrenaline were measured in lungs perfused with 2 nmol/l 3H-5-HT or 3H-noradrenaline for 2 min, in the absence or presence of at least three concentrations of paroxetine, citalopram, fluoxetine, 7-methyltryptamine, tryptamine, nisoxetine, imipramine, 5-HT, desipramine, (+)-oxaprotiline, cocaine or tyramine. The results showed that pharmacologically distinct transporters are involved in the uptake of 5-HT and noradrenaline in rat lungs, since there was no significant correlation between the IC50 values for inhibition of 5-HT and noradrenaline uptake in the lungs. However, there were significant correlations between the IC50 values for (a) inhibition of 5-HT uptake in rat lungs and of uptake by the 5-HT transporter in rat brain and (b) inhibition of noradrenaline uptake in rat lungs and of uptake1 in rat phaeochromocytoma PC-12 cells. The results support the conclusion that 5-HT uptake in rat lungs occurs, at least predominantly, by a 5-HT transporter which is very similar to or the same as that in other tissues, such as the brain, and provide further evidence for transport of noradrenaline by uptake1. Further experiments were carried out to determine whether there is any transport of 5-HT by uptake1 or of noradrenaline by the 5-HT transporter in rat lungs. Lungs were perfused with 2 nmol/l 3H-5-HT or 3H-noradrenaline for 2 min in the absence or presence of 1 mumol/l citalopram, desipramine, or citalopram and desipramine. The results showed that there was no evidence of any transport of 5-HT in the lungs by uptake1 or of noradrenaline by the 5-HT transporter, in that desipramine had no effect on 5-HT uptake (in the absence or presence of citalopram) and citalopram had no effect on noradrenaline uptake (in the absence or presence of desipramine). The final series of experiments was carried out to determine whether, at high concentrations of the amine, there is any interaction of 5-HT with uptake1 or of noradrenaline with the 5-HT transporter. Noradrenaline, at a concentration of 10 mumol/l, did not affect 5-HT uptake in lungs perfused with 2 nmol/l 3H-5-HT for 2 min (uptake1 inhibited), but 50 mumol/l 5-HT inhibited noradrenaline uptake by 56% in lungs perfused with 2 nmol/l 3H-noradrenaline for 2 min (5-HT transporter inhibited). These and the above results show that the 5-HT transporter appears to be exclusively responsible for 5-HT uptake in rat lungs, despite the possible interaction of 5-HT at high concentrations with the uptake1 transporter in the cells. On the other hand, noradrenaline is transported exclusively by uptake1 in the lungs, and there is no evidence that it interacts with the 5-HT transporter, even at high concentrations.     

Insulin-like growth factor-binding protein (IGFBP)-3 and IGFBP-5 share a common nuclear transport pathway in T47D human breast carcinoma cells

Insulin-like growth factor-binding proteins (IGFBPs) play an integral role in modifying insulin-like growth factor actions in a wide variety of cell types. Recent evidence suggests that IGFBP-3 and IGFBP-5 also have effects on cell growth that are insulin-like growth factor-independent. In investigating possible mechanisms for this effect, the intracellular trafficking of IGFBP-3 and IGFBP-5, both of which contain sequences with the potential for nuclear localization, was studied in T47D cells. Nuclear uptake of fluorescently labeled IGFBP-3 and IGFBP-5 was observed in a proportion of T47D cells that appeared to be rapidly dividing. IGFBP-1 and IGFBP-2, which do not possess the putative domain for nuclear translocation, were not transported to the nuclei of T47D cells. When T47D cells were preincubated with excess unlabeled IGFBP-3, nuclear localization of labeled IGFBP-3 or IGFBP-5 was not detected, indicating that their nuclear translocation involves a common pathway. Inhibition of receptor-mediated endocytosis did not affect nuclear uptake of IGFBP-3, suggesting that it uses an alternative non-classical import pathway for transport across the plasma membrane. In addition, a variant form of IGFBP-3 with a mutation in the putative nuclear localization sequence was unable to translocate to the nuclei of T47D cells, suggesting that nuclear translocation of IGFBP-3 was dependent on these carboxyl-terminal basic residues.     

Danazol for systemic lupus erythematosus with refractory autoimmune thrombocytopenia or Evans' syndrome

OBJECTIVE: To determine the efficacy of danazol for refractory autoimmune thrombocytopenia or Evans' syndrome complicating systemic lupus erythematosus (SLE). METHODS: We studied 16 consecutive patients with SLE and corticosteroid refractory autoimmune thrombocytopenia; 3 patients had coexisting autoimmune hemolysis (Evans' syndrome). Five patients had undergone splenectomy. Danazol was commenced at 200 mg/day, and increased stepwise (maximum 1200 mg/day) until benefit or toxicity was observed. After remission the danazol dose was gradually reduced to 200-400 mg/day. RESULTS: All 16 patients achieved a complete remission (platelet count >100 x 10(9)/l, hematocrit >39%) 2 months after starting danazol (range 6 weeks-8 months). Remission persisted during continued danazol therapy (mean followup 18.2 months, range 2-49 months). One patient with Evans' syndrome required discontinuation of danazol because of jaundice and biopsy proven minimal hepatic necrosis: hemolysis recurred after discontinuation of danazol. CONCLUSION: Danazol is effective for the treatment of autoimmune thrombocytopenia or Evans' syndrome complicating SLE irrespective of splenectomy status. Longer followup will be needed to determine whether the remission persists after withdrawal of danazol.     

Treatment with progesterone and 17 beta-oestradiol to induce emergence of a newly-recruited dominant ovulatory follicle during oestrus synchronisation with long-term use of norgestomet in Brahman heifers

The aim of this study was to determine the effect on ovarian follicular growth and atresia, of acute treatment with either 100 mg of progesterone (n = 10), 200 mg of progesterone (n = 10), 10 mg of oestradiol + 100 mg of progesterone (n = 10), 10 mg of oestradiol (n = 10) or no treatment (n = 10), given on Day 10 of a 17-day treatment with a norgestomet implant in randomly cycling Bos indicus heifers. The fate of the dominant follicle on Day 10, emergence of the new cohort of follicles and the intervals from implant removal to ovulation were recorded by ultrasonography. Plasma concentrations of Luteinizing hormone (LH), progesterone and oestradiol were determined during the time when the norgestomet implant was in place. All treatments resulted in the emergence of a new cohort of follicles within 5 days of administration. The day of emergence of the ovulatory follicle tended to be delayed after treatment with 100 mg of progesterone (2.7 +/- 0.3 days after treatment), 200 mg of progesterone (3.7 +/- 0.5 days after treatment), 10 mg of oestradiol + 100 mg of progesterone (4.4 +/- 0.2 days after treatment) and 10 mg of oestradiol (4.6 +/- 0.4 days after treatment) compared to control heifers (1.4 +/- 1.4 days after time of treatment). The mean interval from implant removal to onset of oestrus was significantly shorter after treatment with 100 mg of progesterone (38.4 +/- 2.6 h) than after treatment with 200 mg of progesterone (61.5 +/- 3.9 h) but otherwise, the mean interval from implant removal to onset of oestrus did not differ. Oestrus synchrony, measured by the sample standard deviation of oestrus onset, was tighter in all treatment groups compared to untreated control heifers. The mean interval from implant removal to ovulation did not differ significantly between groups. The synchrony of ovulation, measured by the sample standard deviation of the interval from implant removal to ovulation, was significantly tighter after treatment with 100 mg of progesterone, 200 mg of progesterone and 10 mg of oestradiol compared to control heifers. Treatment with 10 mg of oestradiol resulted in ovulation in seven of 10 heifers before implant removal, three of which failed to ovulate after implant removal. Progesterone administered on Day 10 lowered plasma LH concentrations (P < 0.05), whereas treatment with oestradiol caused a surge of LH and ovulation. Progesterone administered with oestradiol prevented the LH surge. A combination treatment of oestradiol and progesterone given on Day 10 of a 17-day norgestomet treatment in a range of follicular states resulted in the consistent emergence of a new cohort of follicles which included the eventual ovulatory follicle.     

Recombinant rat surfactant-associated protein D inhibits human T lymphocyte proliferation and IL-2 production

Components of the airspace-lining material may contribute to the local regulation of immune function within the lung. We report here that recombinant rat pulmonary surfactant-associated protein D (SP-D) inhibits the lectin- and anti-CD3-stimulated proliferation of human PBMCs. Inhibition was associated with a decreased production of IL-2, and the addition of human rIL-2 blocked the inhibitory action of SP-D. These effects were not inhibited by maltose, indicating that the inhibitory activity was not dependent upon the lectin activity of SP-D. Studies employing mutant SP-D lacking N-linked sugars or defective in multimerization further indicated that inhibition was not dependent upon cellular interactions with the N-linked oligosaccharide on SP-D or the oligomerization of trimeric SP-D subunits. Although a peptide containing an inverted DGR showed similar IL-2-dependent effects on anti-CD3-stimulated proliferation, deletion of the conserved DGRDGR sequence near the amino-terminal end of the collagen domain did not decrease the suppressive activity of SP-D. We hypothesize that SP-D can dampen lymphocyte responses to exogenous stimuli and protect the lung against collateral immune-mediated damage.     

A review of the principles of pulse oximetry and accuracy of pulse oximeter estimates during exercise

OBJECTIVE: The outcomes of patients with squamous cell carcinoma of the anal canal treated by either sphincter-preserving procedures or radical surgery were evaluated, with the goals of identifying factors predicting treatment failure and quantifying results of salvage therapy in patients with recurrent disease. BASIC PROCEDURES: A population-based study on all patients in all 159 hospitals of the Department of Veterans Affairs (VA) from 1987 to 1991 was carried out. Data were compiled from several national computerized VA data sets. Supplementary information from local tumor registrars also was obtained, including demographic information, discharge summaries, operative reports, pathology reports, and medical oncology and radiation oncology summaries. From these sources, information on tumor histology, tumor stage, tumor grade, presence of regional or distant metastases, surgical procedures, use of chemotherapy and radiation therapy (RT), toxicity of chemotherapy and RT, development of recurrent disease, treatment of recurrence, survival, and cause of death were obtained. MAIN FINDINGS: Four hundred five patients with anal cancer were identified by computer search, and 204 (51%) were evaluable; 164 of 204 (80%) had squamous cell carcinoma, 137 of whom (84%) were treated with sphincter-preserving procedures, and 27 of whom (16%) were treated by by radical surgery. One hundred fourteen of 138 (83%) were treated by multimodality therapy, which we defined as local excision followed by chemotherapy and RT. The mean dose of RT among patients treated by multimodality therapy was 4200 +/- 540 cGy and 82% of those treated with multimodality therapy received 5-FU/mitomycin C. Recurrent disease was diagnosed in 43 of all 149 patients (29%) with potentially curable disease. (stages I-III) Multivariate analysis revealed that stage at diagnosis (p = 0.04) and method of treatment (p = 0.03) were the sole predictors of recurrence. Fifty-three percent of patients who underwent salvage abdominoperineal resection (APR) are alive, whereas only 19% who underwent salvage chemotherapy with or without RT are alive. PRINCIPAL CONCLUSIONS: These data indicate that multimodality therapy currently is being employed in the majority of patients with squamous cell carcinoma of the anal canal in the VA system. Tumor stage and method of treatment appear to affect the likelihood of development of recurrent disease. Salvage APR has curative potential. Results with salvage chemotherapy and RT are disappointing.