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Biomedical subjects

W M Palmer

Publications and source records attributed to W M Palmer.

At least 19 recordsLinked to original sources
PubMed1992

Seasonal profiles of melatonin in adult rams.

The objective of this study was to investigate the seasonal changes in melatonin profiles based on frequently collected samples in adult rams maintained under simulated natural photoperiod. In a group of six rams, the seasonal changes of melatonin were characterized in samples collected at 10-min intervals for an equal period before and after the median of the scotophase during the spring (March) and the autumn (September) equinoxes, and also during the summer (June) and the winter (December) solstices. In an additional two rams, the rapid changes in melatonin concentrations were investigated in samples drawn at 2-min intervals for a 2-hr period before and after the median of the scotophase, but only during the summer and the winter solstices. The results show that in adult rams there is a distinct seasonal variation in the nightly rise of melatonin (P less than 0.01). Mean concentrations in June and September were higher than in March or December (P less than 0.05). There was no difference between the means in June or September. However, the means in March were lower than in December (P less than 0.05). Rapid changes in melatonin concentrations occurred in samples collected either at 10-min or 2-min intervals. In rams sampled at 2-min intervals, mean melatonin values in June were also higher than in December (P less than 0.01). The results suggest that there are distinct seasonal changes in melatonin concentrations in the ram and that rapid changes in melatonin concentrations reflect pulsatile secretion.

Analysis of Variance↗
PubMed1988

Effects of heat stress on serum progesterone in cyclic ewes and on progesterone and cortisol response to ACTH in ovariectomized ewes.

The daily mean of serum progesterone in cyclic ewes (N = 5) as well as the profile characteristics of progesterone and cortisol in response to an acute single dose (5 i.u./kg liveweight 0.75) of adrenocorticotrophic hormone (ACTH) into ovariectomized ewes (N = 4) was investigated during exposure to a constant thermoneutral temperature of 18 +/- 1 degree C or to a daily cyclic heat stress temperature of 18 degrees C-35 degrees C-18 degrees C, in an environmental chamber. Serum collected daily from the cyclic ewes was assayed for progesterone, while serum collected more frequently for 10 h, on the 14th day of exposure to the respective temperature, from the ovariectomized ewes was assayed for progesterone and cortisol by RIAs. In cyclic ewes, heat stress increased the area under the daily progesterone curve (P less than 0.09) but had no effect on progesterone concentration after the regression of the CL. In ovariectomized ewes, ACTH significantly elevated the response of both cortisol and progesterone (r = 0.75, P less than 0.001) within 10-15 min of injection. In the ovariectomized ewes and during heat stress, the responses of progesterone and cortisol to ACTH were characterized by an initial acute rise, a transient drop, a steep elevation and a gradual but prolonged decline. During thermoneutral temperatures, this biphasic response pattern was not observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1984

Seasonal changes in the endocrine responsiveness of the pituitary and tests of male sheep in relation to their patterns of gonadotropic hormone and testosterone secretion.

Pituitary and testicular endocrine responses to exogenous gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH), respectively, were assessed for adult rams in an investigation of the regulation of seasonal changes in the patterns of episodic LH and testosterone secretion. Concurrent variations in testis size and in circulating levels of follicle stimulating hormone (FSH) and prolactin (PRL) were also examined. On 10 occasions throughout the year, serum hormone levels were assessed over 6- to 8-h periods during which time rams were left untreated (day 1) or were injected (iv) with single doses of either 10 micrograms synthetic GnRH (day 2) or 30 micrograms NIH-LH-S18 (day 3); blood samples were collected from the jugular vein at 10- to 20-min intervals. Testicular redevelopment during the summer, as indicated by increasing testis diameter measurements, was associated with increases in mean FSH level and was preceded by a springtime rise in mean PRL level; "spontaneously" occurring LH pulses and those produced in response to GnRH treatment were relatively large during this period. Increases in the magnitude of testosterone elevations in response to both endogenously and exogenously produced LH pulses occurred in August. Mean testosterone levels were elevated fourfold in the fall as a consequence of relatively frequent and small LH pulses stimulating a more responsive testis to produce more frequent and larger testosterone elevations; endogenous LH pulses, however, did not appear to stimulate the testes maximally at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Seasonal changes in the secretion of gonadotropic hormones and in the endocrine response of the pituitary of male sheep in the absence of gonadal influence.

Circulating levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL) were assessed in four long-term castrate rams at monthly intervals for 1 year beginning in March. Each month, rams were bled from the jugular vein at 10-min intervals for an 8-h period; 10 micrograms synthetic gonadotropin releasing hormone (GnRH) was injected into the jugular vein following 6 h of sampling. Changes in natural daylength were associated with seasonal variations in mean serum levels of LH (r = 0.57, P less than 0.05) and PRL (r = 0.94, P less than 0.01). LH levels declined 55% between June and October as LH peaks became more frequent and progressively smaller in magnitude, and base-line levels decreased; these trends were reversed by December. In comparison, FSH levels increased 40% between June and September and then returned to relatively low values in October. Seasonal variations in the magnitude of endogenous LH pulses were not associated with definitive changes in the LH response of the pituitary to exogenous GnRH. Although LH and FSH levels in the castrate rams were typically high, many of the seasonal-directional changes in the secretory characteristics of these hormones (i.e., LH peak frequency and magnitude, and mean FSH level) were similar to those reported for the intact ram. Data indicate that photoperiodic regulation of hypothalamic function of rams is in part via direct or steroid-independent means.

Animals↗
PubMed1981

Characterization of a radioimmunoassay for ovine FSH utilizing an anti-bovine FSH serum.

The sensitivity of the assay, utilizing a bovine FSH antiserum and 125I-labelled bovine FSH tracer, is 5 ng NIH-FSH-S6/ml, and cross-reactivities of other ovine pituitary glycoprotein and protein hormones (LH, TSH, growth hormone and prolactin) are less than 1.0%. Both pituitary and serum FSH of the sheep cross-react in a manner parallel with that of standard NIH-FSH-S6. Serum FSH concentrations in 4 ewes at various times after the onset of oestrus peaked more or less coincidently with the preovulatory increase of serum LH. The serum levels of FSH and LH did not correlate proportionally but fluctuated considerably in individuals animals. The radioimmunoassay system appears to be sensitive and specific for measuring serum concentrations of FSH in rams and ewes in different physiological states.

Animals↗
PubMed1981

Cellulitis: treatment with cefoxitin compared with multiple antibiotic therapy.

Cefoxitin, a parenteral cephamycin beta-lactam antibiotic was prospectively evaluated as a single drug alternative in 31 children with cellulitis and the results of therapy were compared retrospectively with those from prevailing multiple antibiotic therapy for cellulitis in 56 children. Periorbital and lower extremity cellulitis accounted for more than 60% of the cases in both study groups. The most common bacterial agents included Haemophilus influenzae, Staphylococcus aureus, and group A beta-hemolytic Streptococcus. In as many as 50% of the cases, no etiologic agent could be found. In addition to blood cultures, cellulitis leading edge aspirate cultures were helpful in establishing the etiologic diagnosis. Of 52 patients sampled in the combined studies, 21% had positive aspirate cultures in the presence of negative blood cultures. The outcome and mean duration of hospital stay were similar in both groups. No severe adverse reactions were encountered. The mean number of antibiotics used in the retrospective study was three (range 1 to 7) whereas cefoxitin alone was used in the prospective study. All organisms isolated in the prospective study were susceptible to cefoxitin. Single antibiotic therapy with cefoxitin appears to be as safe and as effective in the treatment of cellulitis in children as multiple antibiotic therapy.

Anti-Bacterial Agents↗
PubMed1979

Clinical and bacteriological evaluation of cefoxitin therapy in children.

Cefoxitin, a parenteral cephamycin beta-lactam antibiotic, was evaluated for safety and efficacy in children with bacterial infections other than meningitis. Twentysix patients between 3 months and 7 years of age were treated with 80 to 160 mg/kg per day. The most common diagnoses were cellulitis (13 patients), pneumonia (5 patients), and bone and joint infection (4 patients). Nine patients were bacteremic. The most frequently recovered pathogens were Staphylococcus aureus (six patients), Haemophilus influenzae (four patients), and Streptococcus pneumoniae (three patients). All organisms were susceptible to cefoxitin. All 26 children were considered improved or cured. No severe adverse reactions were encountered. Phlebitis (4%), eosinophilia (12%), and elevated liver function tests (4%) were associated with therapy. Cefoxitin appears to be a safe, effective, and well-tolerated antibiotic when used in children with susceptible bacterial infections other than meningitis.

Bacterial Infections↗
PubMed1976

Pantothenic acid, coenzyme A, and human chronic ulcerative and granulomatous colitis.

To investigate further an apparent relationship between chronic ulcerative and granulomatous colitis and pantothenic acid deficiency, colonic tissues obtained at the time of colectomy in 29 patients with these disorders were assayed for pantothenic acid and for coenzyme A (CoA) activity. For comparison, normal colonic tissues free of pathological lesions were obtained from 31 patients having colectomy for carcinoma or diverticulitis. Plasma, red blood cells, and colonic mucosa were assayed microbiologically for free and total pantothenic acid. The activity of CoA in colonic mucosa was determined by assaying the acetylation of sulfanilamide. Concentrations of free, bound, and total pantothenic acid in blood and in colonic mucosa did not differ between the two groups of patients. Bound pantothenic acid increased linearly with total pantothenic acid. Colonic mucosa concentrated free pantothenic acid to about 50 times the level of blood, and pantothenic acid in red cells was similar to the concentration in plasma. Compared to normal gut mucosa, CoA activity was markedly low in mucosa from patients with chronic ulcerative or granulomatous disease despite the presence of normal amounts of free and bound pantothenic acid. A block in the conversion of bound pantothenic acid to CoA in diseased mucosa is suggested.

Adult↗
PubMed1975

Luteinizing hormone, oestrogen and progesterone levels in peripheral serum of anoestrous and cyclic ewes as determined by radioimmunoassay.

Jugular vein blood was collected daily from four mature ewes throughout anoestrus and the first oestrous cycle of the breeding season until 4 days after the second oestrus. The levels of oestrogen, progesterone and LH were determined by radioimmunoassay. There were fluctuations in the LH level throughout most of the observed anoestrous period with a mean plus or minus S.E. value of 2-3 plus or minus 0-9 ng/ml. High LH values of 20-0, 41-2 and 137-5 ng/ml were observed in three ewes on Day - 24 of anoestrus. A brief minor rise in progesterone level was also observed around this period. Progesterone levels were consistently low (0.11 plus or minus 0-01 ng/ml) before Day - 25 of anoestrus. A major rise occurred on Day - 12 of anoestrous and this was followed by patterns similar to those that have been previously reported for the oestrous cycle of the ewe. Random fluctuations of oestrogens deviating from a mean level of 4-40 plus or minus 0-1 pg/ml were observed during anoestrus and the mean level during the period from the first to the second oestrus was 5-2 plus or minus 0-3 pg/ml. A well-defined peak of 13-3 plus or minus 0-7 pg/ml was seen in all ewes on the day of the second oestrus. Results of the present study suggest that episodic releases of LH occur during anoestrus and periods of low luteal activity. The fluctuations in LH levels, as observed during the period of low luteal activity, i.e. before Day - 25 of anoestrus, were less pronounced during the periods of high luteal activity. The view that luteal activity precedes the first behavioural oestrus of the breeding season is supported.

Animals↗