Search PubMed⌕ Search

Biomedical subjects

R H Penny

Publications and source records attributed to R H Penny.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effects of hyperthermia on the myelograms of adult and fetal guinea-pigs.

The myelograms of adult guinea-pigs at various stages after brief exposure to hyperthermia were compared with those of control animals. The proportions of neutrophil and eosinophil metamyelocytes and of intermediate normoblasts were significantly reduced for at least 24 h after exposure and the proportions of neutrophil polymorphs and lobulated eosinophils were significantly increased over this period. The mitotic index was reduced for up to 5 h. Morphological changes in cells included hypersegmentation of nuclei, pyknosis, necrobiotic changes, development of pseudopodia, and abnormalities of mitosis. The myelograms of newborn guinea-pigs which had been heated on days 20-23 of pregnancy showed no significant changes.

Animals↗
PubMed1984

Effect of a dietary supplement of biotin on pig hoof horn strength and hardness.

Supplementary biotin (1 mg d-biotin/kg feed) increased the compressive strength of the mid-abaxial sidewall region of pig's hoof from 9.3 (+/- 0.5) X 10(6) N/m2 to 12.0 (+/- 0.5) X 10(6) N/m2 (P less than 0.05). It also increased the hardness of this region, measured on the Shore A and D hardness scales (P less than 0.05). The leading edge of the hoof wall was significantly stronger than the sidewall (P less than 0.001) with a compressive strength of 14.5 (+/- 0.7) X 10(6) N/m2. This site showed no significant improvement in compressive strength or hardness in response to biotin. Biotin also produced a significant decrease in the hardness of the heel bulb on the Shore A scale (P less than 0.05). There would therefore appear to be a rational biomechanical basis for the finding by others that biotin reduces lameness. The Shore A and D hardness testers are sensitive to the improvement produced by biotin and may be useful as small, hand-held hoof testing devices for use in field conditions by the practising veterinarian.

Animals↗
PubMed1982

Metabolism and excretion of [14C] verruculogen in a sheep.

[14C] Verruculogen (75 micrograms/kg) was given intravenously to a sheep under barbiturate anaesthesia to prevent the severe tremor and convulsions which would otherwise have occurred. Two hours later 28 per cent of the tremorgenic mycotoxin was detected in the liver, bile and small intestine. Approximately 0.5 per cent was excreted in the urine. Trace amounts of radiolabel were detected in the cortex and corpus striatum of the brain. Verruculogen was metabolised by the liver and converted completely to four more polar products, including two isomeric forms of desoxy-verruculogen and the weakly tremorgenic mycotoxin TR-2. The principal and most polar metabolite excreted is probably an isomer of TR-2.

Animals↗
PubMed1982

A comparative study of sheep and pigs given the tremorgenic mycotoxins verruculogen and penitrem A.

The moulds Penicillium simplicissimum and P crustosum and the tremorgenic mycotoxins, verruculogen and penitrem A, isolated from them, were given to sheep and pigs to compare their potencies. Pigs were generally less susceptible and in both species penitrem A was less potent than verruculogen. Five-month-old lambs seemed more susceptible to mycelium containing verruculogen than were 15-month-old sheep given a similar oral dose relative to bodyweight. Repeated daily dosing of lambs and sheep for five days with P simplicissimum failed to enhance the effect, indicating that verruculogen toxicity was not cumulative. Long and short acting barbiturate anaesthesia blocked the effects of lethal doses of tremorgens. Sedation with diazepam diminished, but did not block, mycotoxin-induced tremors suggesting that there was no specific action of this anticonvulsant sedative on tremorgens.

Animals↗
PubMed1981

INfluence of biotin supplementation on sow reproductive efficiency.

A herd of 116 sows was divided into two groups. Animals in one group had their food supplemented with 1160 micrograms/day of biotin in pregnancy and 2320 micrograms/day in lactation, over a 12-month period. The other group served as a control. Those receiving biotin farrowed significantly more live pigs in parities 2 and 4 than in the control animals; the increase in parity 3 only just failed to reach significance. There was no consistent effect on the weaning to service internal although a significant difference (P = 0.05) was seen with the third litters.

Animals↗
PubMed1980

Foot rot of pigs: the influence of biotin supplementation on foot lesions in sows.

A herd of 116 sows with a high frequency of foot lesions and lameness was divided into two groups, A and B. Group B was supplemented with 1160 microgram per day of biotin in pregnancy and 2320 microgram per day in lactation, over a 12-month period. No improvement occurred in the condition of the feet or skin. Gilts introduced as replacements to the herd were allocated alternately to the groups. Those receiving biotin (group B) showed significantly fewer lesions of heel erosion, white-line, heel bruising and "corn", and the severity and number of lesions of the lateral hind claws were also significantly improved.

Animals↗
PubMed1980

Actions of tremorgenic fungal toxins on neurotransmitter release.

The neurochemical effects of the tremorgenic mycotoxins Verruculogen and Penitrem A, which produce a neurotoxic syndrome characterised by sustained tremors, were studied using sheep and rat synaptosomes. The toxins were administered in vivo, either by chronic feeding (sheep) or intraperitoneal injection 45 min prior to killing (rat), and synaptosomes were subsequently prepared from cerebrocortical and spinal cord/medullary regions of rat, and corpus striatum of sheep. Penitrem A (400 mg mycelium/kg) increased the spontaneous release of endogenous glutamate, GABA (gamma-aminobutyric acid), and aspartate by 213%, 455%, and 277%, respectively, from cerebrocortical synaptosomes. Verruculogen (400 mg mycelium/kg) increased the spontaneous release of glutamate and aspartate by 1300% and 1200%, respectively, but not that of GABA from cerebrocortical synaptosomes. The spontaneous release of the transmitter amino acids or other amino acids was not increased by the tremorgens in spinal cord/medullary synaptosomes. Penitrem A pretreatment reduced the veratrine (75 microM) stimulated release of glutamate, aspartate, and GABA from cerebrocortical synaptosomes by 33%, 46%, and 11%, respectively, and the stimulated release of glycine and GABA from spinal cord/medulla synaptosomes by 67% and 32% respectively. Verruculogen pretreatment did not alter the veratrine-induced release of transmitter amino acids from cerebrocortex and spinal cord/medulla synaptosomes. Penitrem A pretreatment increased the spontaneous release of aspartate, glutamate, and GABA by 68%, 62%, and 100%, respectively, from sheep corpus striatum synaptosomes but did not alter the synthesis and release of dopamine in this tissue. Verruculogen was shown to cause a substantial increase (300-400%) in the miniature-end-plate potential (m.e.p.p.) frequency at the locust neuromuscular junction. The response was detectable within 1 min, rose to a maximum within 5-7 min, and declined to the control rate over a similar period. No change in the amplitude of the m.e.p.p.'s was observed. These effects of the tremorgens on transmitter release are interpreted in terms of their mode of action.

Amino Acids↗
PubMed1979

Clinical studies on tremorgenic mycotoxicoses in sheep.

The clinical responses of sheep dosed orally over seven to 14 weeks with the dried mycelium of a soil-borne mould containing the tremorgenic mycotoxin penitrem A are described. An initial tremoring response was gradually overshadowed by an incoordination syndrome similar to that seen in ryegrass staggers. In spite of protracted staggers symptomatology, correlated with in vitro changes in the release of neurotransmitter amino acids from corpus striatum nerve ending preparations, no histopathology was evident in the wide range of neural and other tissue studied. The biochemical nature of this reversible mycotoxicosis is discussed.

Animals↗
PubMed1976

Priorities for pig research.

A postal survey was carried out by the Pig Veterinary Society to establish the opinions of its members on priorities for pig research: 153 members, 64 per cent of the total--returned analysable questionnaires. The survey shows that problems of highest priority for members are atrophic rhinitis, non-infectious infertility, neonatal enteritis, economics of disease, preventive medicine programmes and swine dysentery. The membership was classified by the nature of their work into five groups and the six subjects listed above cover the top three priorities of all groups. A classification of the papers listed in the Index of Current Research on Pigs XXII 1976 suggests that some of the six subjects are under researched.

Animals↗
PubMed1975

Atrophic rhinitis of pigs: abattoir studies.

The snouts of 2701 pork, bacon and heavy pigs killed at five abattoirs in England and Scotland during March to July 1974 were examined for evidence of atrophic rhinitis. Lesions were graded 1 to 5 according to severity. Suspicious lesions were present in 75-7 per cent of the sample. There was obvious atrophy of the turbinates in 44-7 per cent (grade 2 to 5) and severe atrophy in 17-5 per cent (grades 3 to 5). Foreign bodies were found in or between the posterior cheek teeth of 5-3 per cent of the sample. There was frequently an associated gingivitis. Other lesions seen included black discolouration of the teeth, severe tooth wear and osteoarthrosis of the temporomandibular joint. It was concluded that the incidence of atrophic rhinitis could have increased markedly since the last survey of the United Kingdom was undertaken in 1956/57 and some form of disease-monitoring service was urgently needed.

Abattoirs↗