Ventricular, paraventricular and circumventricular structures involved in peptide-induced satiety

Cholecystokinin, bombesin or gastrin (2 microliter of 50 ng/microliter) was injected stereotaxically into the paraventricular nucleus of the hypothalamus, the arcuate/ventromedial area, the subfornical organ, the area postrema and the cerebral aqueduct of Sprague-Dawley rats and the effects of these injections on food and water intake were studied. While the injection of cholecystokinin reduced food intake when it was injected into both hypothalamic loci, food and water intake were most severely affected by the injection of this peptide into the cerebral aqueduct. Bombesin reduced food intake after its injection into all areas except the subfornical organ and reliable reductions in water intake were seen after injection of this peptide into all areas except the paraventricular nucleus. Minor reductions in food intake were seen following gastrin injection into the paraventricular nucleus while increased water consumption was observed after this peptide was injected into the paraventricular nucleus and cerebral aqueduct. In a second study 6-hydroxydopamine injections (2 microliter of 8 micrograms/microliter were made into the five areas studied 10 days before animals were injected with 100 micrograms/kg of cholecystokinin (i.p.). All 6-hydroxydopamine-injected animals reduced their food and water intake in response to the cholecystokinin challenge as did intact controls. These results indicate that while the changes in food and water intake produced by the central injection of cholecystokinin, bombesin or gastrin may involve central catecholamine systems, those occurring after its systemic administration do not. Therefore, if the release of gastrointestinal peptides during natural feeding is part of a homeostatic mechanism regulating hunger and satiety, this mechanism may operate without directly involving central catecholamine systems.     

Gibberellin A13 7-aldehyde: A proposed intermediate in the fungal biosynthesis of gibberellin A3

Gibberellin A₁₃ 7-aldehyde, previously proposed as an intermediate in the fungal biosynthesis of gibberellin A₃, has been prepared from gibbere     

Analysis of gamma-carboxyglutamic acid via amino acid analysis.

Modifications of the analysis of protein-bound residues of γ-carboxyglutamic acid (Gla) via alkaline hydrolysis are presented. The method described allows easier sample manipulation than that heretofore required and insures quantitative recovery of hydrolyzed amino acids. A possible explanation of the shoulder which sometimes appears near Gla on some amino acid analyzers is presented.     

Effects of intraventricular injection of gastrin on release of LH,prolactin, TSH and GH in conscious ovariectomized rats

Conscious ovariectomized (OVX) rats bearing a cannula implanted in the 3rd ventricle were injected with 2 μl of 0.9% NaCl containing varying doses of synthetic gastrin and plasma gonadotropin, GH and TSH levels were measured by RIA in jugular blood samples drawn through an indwelling silastic catheter. Control injections of saline iv or into the 3rd ventricle did not modify plasma hormone levels. Intraventricular injection of 1 or 5 μg gastrin produced significant suppression of plasma LH and prolactin (Prl) levels within 5 min of injection. Injection of 1 μg gastrin had no effect on plasma GH, but increasing the dose to 5 μg induced a progressive elevation, which reached peak levels at 60 min. By contrast, TSH levels were lowered by both doses of gastrin within 5 min of injection and the lowering persisted for 60 min. Intravenous injection of gastrin had no effect on plasma gonadotropin, GH and TSH, but induced an elevation in Prl levels. $\text{In}$$\text{vitro}$ incubation of hemipituitaries with gastrin failed to modify gonadotropin, GH or Prl but slightly inhibited TSH release at the highest dose of 5 μg gastrin. The results indicate that synthetic gastrin can alter pituitary hormone release in unrestrained OVX rats and implicate a hypothalamic site of action for the peptide to alter release of a gonadotropin, Prl and GH. Its effect on TSH release may be mediated both via hypothalamic neurons and by a direct action on pituitary thyrotrophs.     

Metronidazole in prevention and treatment of bacteroides infections in elective colonic surgery.

A double-blind randomised trial was carried out among 46 patients undergoing elective colonic surgery; 27 patients received prophylactic metronidazole and 19 received placebo. Anaerobic infections did not develop in any of the metronidazole-treated patients, but did develop in 11 (58%) of 19 controls who were subsequently successfully treated with metronidazole.     

Delayed allograft rejection in mice transgenic for a soluble form of the IL-4 receptor.

Accumulating evidence suggests that in serum and other biological fluids, cytokine binding is a property associated with soluble proteins, including a high-affinity soluble version of the IL-4 receptor (sIL-4R). While it is tempting to speculate that sIL-4R might act as a serum carrier protein or serve to inhibit or modulate IL-4 action, specific biological roles for sIL-4R remain to be established. To further assess the immunoregulatory and therapeutic potential of sIL-4R and other soluble receptors, we have created transgenic mice which constitutively express elevated levels of biologically active sIL-4R. Phenotypic characterization of lymphoid organs in sIL-4R transgenic mice revealed normal numbers of B and T cells and normal surface marker expression. Splenic lymphocytes displayed normal in vitro activities as measured by the PFC response and generation of cytotoxic T cells. In addition, antigen-specific IgE and IgG1 in vivo responses were similar in control and transgenic mice. Despite the apparent developmental normality of the sIL-4R transgenic mice, these animals were markedly deficient in the ability to reject cardiac allografts, suggesting that IL-4 is critical for the generation of alloreactivity. The results further suggest that the ability of sIL-4R to regulate IL-4 activities may be under the control of complex interactions that remain to be elucidated.     

The renal actions of oxytocin in the conscious rat

The renal actions of oxytocin were studied in the conscious unrestrained rat infused with 0.077 M saline at a rate of 150 microliters/min. During the control period volume and sodium excretion reached stable equilibria, the rates being equal to those infused. Administration of oxytocin at 200 pmol/min produced plasma oxytocin levels of 26.0 +/- 2.1 pmol/l and caused a significant diuresis and natriuresis. Renal responses could also be seen with a lower dose of 30 pmol/min which produced plasma levels of 5.1 +/- 0.5 pmol/l while a dose of 15 pmol/min which produced no significant increase in the plasma oxytocin had no renal effect. It appears that oxytocin has a natriuretic action in concentrations within the physiological range.     

Fluorescence decay kinetics of the tryptophyl residues of myoglobin: effect of heme ligation and evidence for discrete lifetime components

The fluorescence decay kinetics of the tryptophyl residues of sperm whale and yellowfin tuna myoglobin have been determined by using time-correlated single photon counting, with picosecond resolution. Purification by HPLC techniques resulted in the isolation of samples that exclusively displayed picosecond decay kinetics. Lifetimes of 24.4 ps for Trp14 and 122.0 ps for Trp7 were found for oxy sperm whale myoglobin (pH 7), which agree with theoretical predictions [Hochstrasser, R. M., & Negus, D. K. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 4399-4403]. The effects of ligand binding and pH on the decay kinetics were investigated, and the results were shown to be consistent with the known crystal structures. Data for the met form of sperm whale myoglobin were analyzed both in terms of a sum of discrete exponential components and as a continuous gamma distribution of exponential decays. The results were not found to support the existence of multiple, structurally distinct conformation states in myoglobin.     

Accumulation of epidermal growth factor within cells does not depend on receptor recycling

Quiescent cells seemingly have a constant number of surface epidermal growth factor receptors. However, exposure of cells to agents which interfere with normal protein turnover suggests that these receptors are internalized and degraded with an apparent half-life of ～6 hours. We show that the time course of maximal accumulation of ligand-receptor complexes is not altered under conditions where degradation of the ligand is inhibited, indicating that no degradation occurs during its first hour of exposure to cells. We also conclusively demonstrate that epidermal growth factor receptors are not recycled during the initial uptake of the ligand, and that a component of pinocytosis of this growth factor is dependent on $\text{de}\text{novo}$ protein synthesis.