Visualization of one-dimensional diffusion and spontaneous segregation of hydrogen in single crystals of VO2

Hydrogen intercalation in solids is common, complicated, and very difficult to monitor. In a new approach to the problem, we have studied the profile of hydrogen diffusion in single-crystal nanobeams and plates of VO2, exploiting the fact that hydrogen doping in this material leads to visible darkening near room temperature connected with the metal-insulator transition at 65 �C. We observe hydrogen diffusion along the rutile c-axis but not perpendicular to it, making this a highly one-dimensional diffusion system. We obtain an activated diffusion coefficient ∼ 0.01 e-0.6eV/kBT cm2s-1, applicable in metallic phase. In addition, we observe dramatic supercooling of the hydrogen-induced metallic phase and spontaneous segregation of the hydrogen into stripes implying that the diffusion process is highly nonlinear, even in the absence of defects. Similar complications may occur in hydrogen motion in other materials but are not revealed by conventional measurement techniques. � 2016 IOP Publishing Ltd

Antagonistic activity of analogs of luteinizing hormone-releasing hormone (LH-RH) in vitro

The ability of eighteen analogs of LH-RH to inhibit LH-RH-induced LH release was tested in primary cultures of rat anterior pituitary cells. [Des-His 2]LH-RH, [Des-His 2, D-Leu 6]LH-RH and [Des-His 2, D-Phe 6]LH-RH inhibited 50% of LH-RH-induced LH release at molar ratios ( MR 50s) of 3000, 500 and 60, respectively, while [D-Phe 2]LH-RH, [D-Phe 2, D-Leu 6]LH-RH and [D-Phe 2, D-Phe 6]LH-RH had similar effects at MR 50s of 1000, 150 and 25, respectively. This indicates that substitution of D-phenylalanine for histidine at position 2 of LH-RH leads to compounds approximately 3-fold more potent than the corresponding [Des-His 2]-analogs. [D-Phe 2, D-Phe 6]LH-RH, the most potent antagonist tested has however a slight agonistic activity (0.003% that of LH-RH itself). [D-Phe 2, D-Phe 6, Phe 7]LH-RH, [D-Phe 2, Phe 3, D-Phe 6]-LH-RH and [D-Phe 2, Phe 5, D-Phe 6]LH-RH inhibit 50% of LH-RH action at MR 50s of 400, 100 and 75, respectively. All of the analogs mentioned in the last group have LH-releasing activities below 1/100,000 that of LH-RH itself

Control of gonadotropic hormone release in trout: Influence of synthetic LHRH and LHRH analogues [formula omitted][formula omitted] and [formula omitted][formula omitted]

Studies were conducted to determine the influence of some LHRH analogues on gonadotropic hormone (GtH) secretion in two species of trout. The observations indicated that synthetic LHRH and various stimulatory LHRH analogues are approximately equipotent in these fish. This is an unexpected result considering the superactive properties of these analogues demonstrated in mammals. An inhibitory LHRH analogue was also tested in the trout with the result that powerful inhibition of LHRH induced GtH release was obtained

The effects of β-(TYR 9)melanotropin-(9–18) and H-PHE-ILE-TYR-HIS-SER-TYR-LYS-OH on the analgesic action of morphine

β-(Tyr 9)melanotropin-(9–18), which itself has no analgesic action, as measured by the tail-flick and hot-plate methods, decreased morphine-induced analgesia following intracerebroventricular injection. H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH heptapeptide, which has weak CRF-like activity, had no action on analgesia and was not able to modify morphine-induced analgesia. Compared with ACTH 1–24, which in a subcutaneous dose of 100 μg/rat decreased morphine-induced analgesia, the same dose of H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH was ineffective

Effects of H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH on the in vitro uptake and release of radiolabelled dopamine, noradrenaline and serotonin in rat brain hypothalamic slices

The effects of H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH, a hypothalamic heptapeptide with weak CRF activity were investigated on the in vitro uptake and release of radiolabelled dopamine (DA), noradrenaline (NA) and serotonin (5-HT) in rat brain hypothalamic slices. In a doses of 5×10 −6 M and 10 −5 M the heptapeptide significantly increased the 5-HT uptake, whereas it had no effect on the DA and NA uptakes. The same doses (5×10 −6 M, 10 −5 M) significantly increased the DA release without affecting the NA and 5-HT release. These results suggest that H-Phe-Ile-Tyr-His-Ser-Tyr-Lys-OH as a hypothalamic peptide is able to modulate selectively the activity of the serotonergic and dopaminergic transmission without influencing the noradrenergic system in the hypothalamus

Use of the Mouse Vas deferens Assay to Evaluate the Action of Somatostatin Peptides on Gastric Acid Secretion

Six closely related analogues of somatostatin were tested for their ability to inhibit electrically induced contractions of the mouse vas deferens. Their inhibiting activities tended to parallel their reported effects on gastric acid secretion in vivo, while no correlation to their in vitro growth hormone release-inhibiting activities was observed. It is suggested that information derived from the vas deferens assay may provide a relatively rapid and inexpensive assessment of the effects of somatostatin analogues on gastric acid secretion. The vas deferens assay was also used to test several somatostatin analogues for antagonistic activity, which was not found

Effects of β-(Tyr 9)melantropin-(9–18) decapeptide on passive and active avoidance behavior and on open-field activity of rats

The effects of the administration of β-(Tyr 9)melanotropin-(9–18) into the lateral ventricle in a dose of 1.0 μg in 2 μl were studied on passive avoidance behavior, extinction of active avoidance behavior, and open-field activity in rats. β-(Tyr 9)melanotropin-(9–18) given 30 min pretrial facilitated the acquisition of passive avoidance behavior; however, it was ineffective on retention when the material was given immediately posttrial or 30 min before retention testing. The extinction of active behavior was delayed. In open-field activity, the ambulation rate and rearing activity were increased 30 min following administration. The data suggest that β-(Tyr 9)melanotropin-(9–18) has distinct neurotropic properties, and is able to modify behavioral reactions

Luteinizing hormone-releasing hormone analogs with increased anti-ovulatory activity

A series of LH-RH antagonist analogs has been developed in which inhibitory activities have been increased to a potentially clinically useful level. The new peptides, which are typified by [N-acetyl-D-p-Cl-Phe 1,2, D-Trp 3, D-Phe 6,D-Ala 10]-LH-RH and [N-acetyl-D-Trp 1,3,D-p-Cl-Phe 2,D-Phe 6, D-Ala 10]-LH-RH, most importantly contain new modification to positions 1, 2 and 10, and induce full blockade of ovulation at single doses as low as 10 μg per rat (50 μg/kg). Various ring substituents on D-Trp or D-Phe in position 1 or other D-amino acid replacements in position 10 did not significantly improve anti-ovulatory activity. Incorporation of N-Me-Leu in position 7 was slightly detrimental to activity