Changes in plasma steroid levels after single administration of hCG or LHRH agonist analogue in dog and rat

The present study was designed to investigate the effect of acute administration of gonadotropin on testicular steroid secretion in dog and rat. Animals received a subcutaneous injection of 25 IU/kg of hCG or 1.5 microgram/kg of [D-Trp6, des-Gly-NH2(10)]LHRH ethylamide (LHRH-A). Testosterone is the predominant steroid measured, in dog plasma, under basal conditions. After LHRH-A injection, testosterone levels are not significantly changed while dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol (delta 5-steroids) levels are stimulated by almost 20-fold (P less than 0.01). When dogs were injected with hCG, we also observed a marked stimulation of dehydroepiandrosterone levels (20-fold; P less than 0.01) accompanied by a small increase of plasma testosterone concentration (2-fold, P less than 0.01). In rats injected with either hCG or the LHRH analogue, an increment of plasma testosterone (7-fold, P less than 0.01) is detected in the first hour while plasma dehydroepiandrosterone levels are slightly stimulated. Moreover, in rats injected with hCG, low plasma steroid levels are present between 4-12 h after injection due to testicular desensitization. This marked decrease is then followed by a second peak of steroid secretion 24 h later. Acute testicular steroidogenic responsiveness to hCG on the dog is, however, different: after stimulation, the levels of plasma dehydroepiandrosterone are maintained at a plateau and slowly decline after 24-48 h. Our data indicate that in dogs, stimulation of testicular steroidogenesis leads to an increase of plasma delta 5-steroid levels while the same stimuli cause, in the rat, a stimulation of delta 4-androgen, particularly testosterone.     

Optimal stimulation of paralyzed muscle after human spinal cord injury.

Muscle properties change profoundly as a result of disuse after spinal cord injury. To study the extent to which these changes can be reversed by electrical stimulation, tibialis anterior muscles in complete spinal cord-injured subjects were stimulated for progressively longer times (15 min, 45 min, 2 h, and 8 h/day) in 6-wk intervals. An index of muscle endurance to repetitive stimulation doubled (from 0.4 to 0.8), contraction and half-relaxation times increased markedly (from 70 to approximately 100 ms), but little or no change was measured in twitch or tetanic tension with increasing amounts of stimulation. The changes observed with 2 h/day of stimulation brought the physiological values close to those for normal (control) subjects. A decrease in the stimulation period produced a reversal of the changes. No effects were observed in the contralateral (unstimulated) muscle at any time, nor was there evidence of decreased numbers of motor units in these subjects secondary to spinal cord injury. Motor unit properties changed in parallel with those of the whole muscle. The occasional spasms occurring in these subjects are not sufficient to maintain normal muscle properties, but these properties can largely be restored by 1-2 h/day of electrical stimulation.     

THE IDENTITY OF THE SWEDE MIDGE, WITH NOTES ON ITS BIOLOGY

A brief historical summary is given of the literature concerning Contarinia nasturtii Kieffer, C. torquens de Meijere and C. geisenheyneri Riibsaamen, three gall midges (Cecidomyidae) which have been associated respectively with leaf damage on Brassica spp. in England, identical malformation on the Continent and swollen and closed flowers of Brassica spp. in Europe.
Following the discovery in England of the true Contarinia nasturtii causing swollen and closed flowers oiRorippa amphibia, preliminary experiments have shown that midges from this source will also cause similar damage to swede flowers and that they are the same species as those attacking R. amphibia blossom in the Netherlands.
Further preliminary experiments have shown that swede midge derived from rape leaf axils will also cause identical damage to radish flowers in addition to breeding successfully on the leaves of turnip, swede, cabbage and radish.
Male midges derived from Rorippa blossom have been mated with females from rape leaf axils, and their offspring have been reared on Rorippa flowers and on turnip leaves.
This biological evidence confirms the previous supposition based on morphological grounds that the swede midge is Contarinia nasturtii Kieffer and will cause either flower or leaf damage. Consequently, C. torquens de Meijere and C. geisenheyneri Riibsaamen must remain synonyms.
The shortest time for a generation (from parent to first offspring midge) to develop was 24–39 days in an unheated open glasshouse during June-July in 1949 at Harpenden. Under the same conditions, the shortest time for the next generation from late July to August was 29–32 days. C. nasturtii is the first Contarinia species in which unisexual families have been discovered.