Modulating effect of cerulein on benzodiazepine receptors

Subcutaneous administration of caerulein (100-500 micrograms/kg) significantly reduced the development of picrotoxin (8 mg/kg) seizures in male mice. The same doses of caerulein inhibited 3H-flunitrazepam binding in in vivo experiments. Proglumide, an antagonist of cholecystokinin receptors, in low dose (5 mg/kg) potentiated the effects of caerulein (100 micrograms/kg), whereas the administration of proglumide in high dose (25 mg/kg) reduced the action of caerulein on 3H-flunitrazepam binding and picrotoxin seizures. Caerulein (5-1000 nM) decreased 3H-flunitrazepam binding in in vitro experiments only after supplementation of the binding medium with 120 mM NaCl and 5mM KCl. The results suggest the possible interaction of caerulein with chloride ionophor. It seems probable that the direct interaction of caerulein with chloride ionophor in involved in the inhibitory effect of caerulein on picrotoxin seizures and 3H-flunitrazepam binding.     

Analogs of oxytocin containing a modified peptide bond

Analogs of deamino-oxytocin and deamino-oxypressin containing a CH2-NH group instead of an amide bond between positions 8 and 9 were synthesized. All tested compounds exhibit significantly lowered biological activities.     

Maximization of pulmonary hygroscopic aerosol deposition

A newly developed computer model is used to predict the aqueous salt solution concentration, breathing pattern, and inhaled droplet size distribution parameters that will maximize pulmonary deposition of hygroscopic medicinal aerosols. The parameter values providing maximum pulmonary deposition include 1) a NaCl concentration in the aerosolized solution of 0.035 g/ml or higher if the subject can tolerate it, 2) as nearly a monodispersed inhaled aerosol size distribution as possible, 3) an aerosol mass median diameter of 2-3 micron, and 4) slow (7 breaths/min) uninterrupted breathing of 1.5-2 liters of aerosol/breath. With these values, the model predicts that pulmonary deposition can be increased by greater than 100% relative to the deposition achieved in conventional inhalation therapy with isotonic saline-based medications.     

Reinnervation of experimental superficial wounds in rats

Sensory reinnervation of a superficial skin wound in the rat was studied by labeling sensory axons with anterogradely transported wheat germ agglutinin-horseradish peroxidase. Reinnervation starts after 3 days from the edge of the wound as well as from beneath the wound. About 2 weeks after the production of the wound, some hyperinnervation appears to be present, but after a few additional weeks, the innervation pattern is essentially normal. The results indicate that structural recovery of sensory axons is rapid and probably complete when skin wounds heal with no or minimal scar formation.     

Purification and properties of thyrotrophin releasing hormone (TRH)-containing particles from the rat hypothalamus

The subcellular distribution of the TRH-like immunoreactivity in the rat hypothalamus and brain was studied. In differential centrifugation, the 900 g for 10 min supernatant (S1) of the hypothalamus or brain contained 61--79% of the total TRH. At 11,000 g for 20 min, 51--73% of the TRH in S1 was sedimented. When the hypothalamic S1 was fractioned under non-equilibrium conditions at 25 degrees C, two populations of TRH-containing particles were observed in several types of continuous linear density gradients. Metrizamide and sucrose gradients affected TRH-assay. TRH-particles were very light in Percol-gradients. Isotonic dextran 40,000-sucrose gradients gave the most reproducible results. In these gradients, the large TRH-particles (35%) equilibrated at 1.055--1.060 kg/l and the small ones (23%) at 1.041--1.047 kg/l. Working at 4 degrees C decreased the amount of large TRH-particles. The apparently larger particles contained cytoplasmic and mitochondrial enzymes and were sensitive to hypoosmotic shock like synaptosomes. Electron micrographs confirmed that these particles were synaptosomes. The true nature of the small particles remained unclear but morphologically a part of them were also synaptosomes. Treatment of the animals with reserpine (10 mg/kg i.p., 24 h), with 6-hydroxydopamine (100 microgram/rat i.c.v.) or with 5,7-dihydroxytryptamine (200 microgram/rat i.c.v.) did not affect significantly TRH-recovery or distribution in the hypothalamus.     

A comparison of the antimuscarinic effects of pirenzepine and N-methylatropine on ganglionic and vascular muscarinic receptors in the rat

The antimuscarinic properties of pirenzepine and N-methylatropine were evaluated in two intact preparations by measuring A) the inhibition of increase in mean arterial pressure evoked by McN-A-343 in pithed rats through activation of ganglionic muscarinic receptors and B) the inhibition of fall in arterial pressure evoked by methacholine in anaesthetized rats through activation of vascular muscarinic receptors. To characterize the antimuscarinic potencies of pirenzepine and N-methylatropine, for both antagonists doses were calculated that produce a 10-fold shift to the right of the dose-response curves for A) the pressor response to McN-A-343 (i.v. administration) in pithed rats (D10-p.r.) and B) for the depressor effect to methacholine (i.v. administration) in anaesthetized rats (D10-an.r.), respectively. Whereas N-methylatropine was virtually equieffective in blocking both muscarinic responses (D10-an.r./D10-p.r. approximately equal to 1), pirenzepine, however, was considerably more potent at ganglionic than at vascular muscarinic receptors (D10-an.r./D10-p.r. approximately equal to 16). These data confirm the existence of excitatory ganglionic muscarinic receptors with high affinity for pirenzepine (M1) and provide evidence for the presence of M2 receptors - receptors which show a low sensitivity to pirenzepine - on vascular smooth muscle cells. To further characterize the anticholinergic properties of pirenzepine, its effect on the pressor response to DMPP, a nicotinic ganglionic stimulant, was investigated in pithed rats. A high dose of pirenzepine (1.13 mumol/kg), given i.v., did not affect nicotinic ganglionic transmission.     

COMPARISON OF DNA RENEWAL IN GERM-FREE AND CONVENTIONAL MICE USING [125I]IODODEOXYURIDINE AND [3H]THYMIDINE

Germ-free (GF) and conventional (CV) C3H mice received a single injection of 1 μCi [³H]thymidine and 3 μCi [¹²⁵I]iododeoxyuridine to provide simultaneous labeling of DNA with the two precursors. Thymus, spleen, mesenteric lymph nodes, bone marrow (femora), small intestine, colon and skin were examined for total organ activity and rate of DNA renewal 1–8 days after injection. Precursor incorporation, assayed on day 1, was lower in the thymus, mesenteric lymph nodes and femora (and, to a lesser extent, in the spleen and colon) of GF mice as compared to CV animals. The opposite was observed in the small intestine and skin, i.e. total organ activity was higher in GF animals. Differences in precursor incorporation were partly due to differences in organ weights between the two groups of mice. In comparison to CV animals, DNA renewal rates were diminished in the mesenteric lymph nodes, bone marrow, colon (following a 3-day plateau) and spleen of GF mice. Little, if any, difference was observed between the two groups with respect to the rate of DNA turnover in the thymus and skin. Radioactivity of the small intestine remained constant for 2 days. Thereafter intestinal activity in GF mice declined at an initial slow rate between days 2 and 5 followed by a rapid decrease between days 5 and 8. In CV mice the first phase of activity loss was short with the rapid decline in intestinal activity beginning on day 3. From the slopes of the regression lines, the percentage thymidine reutilization was estimated. Reutilization varied from 0 to 63% in the various organs examined, with the greatest difference between GF and CV mice occurring in the mesenteric lymph nodes.     

Rapid chromosome territory relocation by nuclear motor activity in response to serum removal in primary human fibroblasts

Background  

Radial chromosome positioning in interphase nuclei is nonrandom and can alter according to developmental, differentiation, proliferation, or disease status. However, it is not yet clear when and how chromosome repositioning is elicited.