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Biomedical subjects

N Zervas

Publications and source records attributed to N Zervas.

6 recordsLinked to original sources

Fluosol and experimental spinal cord ischemia.

Spinal cord ischemia was produced by temporary aortic occlusion for 12.5 min in 27 rabbits. Animals were divided into three groups: Group A received Fluosol DA 20% and 100% oxygen; Group B Fluosol and room air only, and Group C Dextran 40 and 100% oxygen. There was no difference in neurological outcome or in the extent and severity of histologically documented infarction of the spinal cord in the three groups. There was also no difference between these groups and untreated controls previously studied by us.

Animals↗

Synchronization of oestrus in ewes with Provera sponges/PMSG, prostaglandin F2 alpha or the prostaglandin analogue, ICI 80996, and fertility following natural mating or artificial insemination.

Following the synchronization of oestrus with different treatments during the breeding season, the fertility of naturally-mated ewes has been compared to that of ewes artificially inseminated with fresh semen. The following treatments were used: I. sponges impregnated with progestagen (50--60 mg of medroxyprogesterone acetate) left in situ for 14 days and an i.m. injection of 500 IU of PMSG at sponge withdrawal; II. injections of prostaglandin F2 alpha (dose: 15 mg/injection) at intervals varying from 9 to 14 days (see tables); III. injections of the prostaglandin F2 alpha analogue, ICI 80996 (dose: 100 micrograms/injection), with the same time intervals as in treatment II. Lambing rate and prolificacy after natural service at the induced oestrus was 55 and 140 p. 100, 32.5 and 153 p. 100 and 60 and 133 p. 100 for ewes receiving treatments I, II or III, respectively, compared to 62.5 and 120 p. 100 for the untreated controls. Double artificial insemination (AI) 48 and 58 h after the sponge/PMSG treatment resulted in a lambing rate of 25 p. 100 and a prolificacy of 133 p. 100. The lambing rate and prolificacy of ewes inseminated 58 and 68 h after the final injection of PGF2 alpha or ICI 80996 were 27.8 and 149 p. 100 and 45.5 and 165 p. 100, respectively. Single AI 55 h after sponge withdrawal gave a lambing rate of 37.8 p. 100. The lambing rate of ewes inseminated 56 h after the final ICI 80996 injection was higher (54.8 p. 100) than that of ewes inseminated at 60 h (37.5 p. 100) or 66 h (30.8 p. 100). However, two inseminations 56 and 66 h after the final ICI 80996 injection gave an even more elevated lambing rate (61.9 p. 100). These results demonstrate that ICI 80996 can successfully control oestrus in the ewe during the breeding season, thus offering an alternative to sponges/PMSG and that the fertility subsequent to both natural mating and AI is equivalent to that of the controls.

Animals↗

Induced lactation in dairy ewes by various brief hormone treatments.

Hormonal induction of lactation in 40 nonpregnant dairy ewes was attempted by daily injecting subcutaneously 25 mg estradiol-17 beta and 70 mg progesterone for 7 consecutive days. After an interval of 7 days the following treatments were applied: group I (10 ewes), nothing; group II, (10 ewes), 10 mg dexamethasone and 30 mg prednisolone; group III (10 ewes), 10 mg dexamethasone, 30 mg prednisolone, 400 IU insulin; and group IV (10 ewes), 10 mg dexamethasone, 30 mg prednisolone, 400 IU insulin, and 40 mg prostaglandin F2 alpha. Hand milking was initiated at day 16. Thereafter, ewes were milked twice daily for 60 days, and milk yields were recorded and sampled twice weekly for measuring fat, pH, acidity, specific gravity, total solids, lactose, and chloride content. Mean yield of milk of ewes in II was larger than of ewes in I and IV. Four ewes in I, 8 ewes in II, 5 ewes in III, and 3 ewes in IV out of 10 ewes in each group produced more than 200 ml milk daily. The peak milk yield of ewes in I was at day 43, in II at day 28, in III at day 7, and in IV at day 11 of the milking period. Injection of corticoids in the induction scheme of estrogen and progesterone resulted in greater lactogenic response and yields of milk, but injections of insulin or insulin and prostaglandin F2 alpha diminished these responses.

Animals↗

Rotational behavior in gerbils following unilateral common carotid artery ligation.

Unilateral cerebral infarctions are produced in 30-50% of all gerbils subjected to ipsilateral ligation of a common carotid artery. It has previously been shown that this infarction is associated with a major depletion if ipsilateral brain dopamine. The present studies characterize the spontaneous and drug-induced rotational behavior manifested by these animals and attempt to relate it to the functional activity of dopaminergic synapses. The tendency of animals to turn towards the side of the lesion 2-3 hours after surgery was found to correlate highly with the unilateral dopamine depletion observed after 24 hours. Two patterns of rotational responses were observed among animals showing symptoms that were treated with d-amphetamine or apomorphine; these could be correlated with mortality 24 hours after surgery.

Amphetamine↗