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Biomedical subjects

W J Fulkerson

Publications and source records attributed to W J Fulkerson.

53 records · Page 3Linked to original sources
PubMed1982

Pattern of cortisol release in sheep following administration of synthetic ACTH or imposition of various stressor agents.

This paper describes experiments with sheep, in which changes in plasma cortisol, after imposition of various stressor agents, were compared to the changes following administration of synthetic ACTH. The influence of stress associated with shearing, yarding, oestrogen administration (30 microgram oestradiol benzoate, i.v.), feeding and fasting on the plasma concentration of cortisol was monitored in four mature Merino ewes. They were placed in the experimental environment for 21 days before monitoring began. The ewes were treated in pairs, each pair being visually and acoustically isolated from the other. One pair of ewes was exposed to the particular stress and the remaining pair acted as their own controls. The treatments were reversed 2 days later. In the second part of the experiment, 0, 0.01, 0.1, 1.0 or 10.0 i.u. synthetic ACTH were injected as an intravenous bolus, after endogenous secretion had been suppressed by administration of synthetic glucocorticoid. All blood samples were taken via an indwelling jugular catheter. A comparison of cortisol release--estimated from a plot of cortisol in plasma versus time--following imposition of various stressor agents and administration of synthetic ACTH, allowed stress to be defined in terms of synthetic ACTH equivalents. The most severe stress was associated with shearing (0.84 i.u. synthetic ACTH equivalents), less stress was imposed by yarding and handling (0.45 i.u.), and there appeared to be no effect attributable to feeding, fasting or oestrogen administration. The similarity in the pattern of cortisol release following ACTH administration offers the possibility of defining acute, but not chronic, stress in terms of ACTH equivalents.

Adrenocorticotropic Hormone↗
PubMed1981

Sperm output by rams and distribution amongst ewes under conditions of continual mating.

Variables associated with mating in rams were compared before and after continuous mating for 6 days. The effect of behaviour and sperm output of individual rams on the number of spermatozoa received by each ewe was measured. Spermatozoa were collected by an intravaginal device which is described and validated. Fourteen rams, isolated from ewes for at least 2 months previously, were each allowed to mate continually with 4 fresh oestrous ewes on each day for 6 days. The number of spermatozoa per ejaculate fell from 3900 +/- 908 x 10(6) to 77 +/- 39 x 10(6). In 8 rams the number of ejaculates per 24 h fell from 17.25 +/- 2.5 to 11.5 +/- 1.5. Five of these 8 rams were then mated with 1, 4 or 8 ewes during each of the next 3 days. At all times rams preferred certain ewes and no more than 5 ewes were mated per day by each ram regardless of the number available. The mean number of ejaculates per ewe varied from 0 to 12.1 for continuously worked rams and from 0.3 to 10.5 for fresh rams. There were 7.0 +/- 1.8, 11.5 +/- 1.5 and 12.1 +/- 1.1 ejaculates/day in the presence of 1, 4 and 8 oestrous ewes, respectively.

Animals↗
PubMed1980

Investigations of ultradian and circadian rhythms in the concentration of cortisol and prolactin in the plasma of dairy cattle.

This experiment analysed the circadian and ultradian pattern of secretion of cortisol and prolactin in cattle, and from this a meaningful sampling technique for these hormones has been suggested. Two Friesian and two Jersey heifers, non-pregnant and 18 months of age, were bled (2 ml blood) every 10 min for 24 h via an indwelling jugular cannula inserted 6 h before sampling commenced. The concentration of cortisol in plasma showed an ultradian rhythm with an amplitude of approximately 30 ng/ml and a frequency of about 0.6 cycles/h. Elimination of the ultradian component of variation, by taking the mean of the rolling means (last three values) for individual heifers, indicated a diurnal variation in cortisol concentration which was high between midnight and midmorning and low in the afternoon. There were frequent sporadic "bursts' of prolactin secretion but these were inconsistent. There was no evidence of diurnal variation in prolactin concentration, or of a temporal relationship between cortisol and prolactin secretion.

Animals↗
PubMed1979

Ultradian and circadian rhythms in the plasma concentration of cortisol in sheep.

Three Merino ewes, adapted for about 3 weeks to their environment, were bled at 10 min intervals through a jugular venous cannula. Radioimmunoassay of plasma samples for cortisol revealed marked diurnal variations with peak levels just after midnight and lowest values in the afternoon. This rhythm appeared to result from a changing amplitude associated with a distinct ultradian rhythm (frequency 0.8-1.2 cycles/h) in the plasma level of cortisol. Calculation of the daily rate of secretion of cortisol from the hormone profiles gave a mean value of 8.49 mg. Arguments are put forward in favour of this method for obtaining the true rate of secretion of cortisol.

Animals↗
PubMed1979

The failure of a prostaglandin F2 alpha analogue, cloprostenol, to initiate lactation in cattle.

An experiment was designed to determine if the analogue of prostaglandin F2 alpha, cloprostenol, at a dose sufficient to cause luteolysis, was lactogenic in cattle. The mammary glands of eight Friesian heifers were developed by treatment with progesterone plus oestrogen. Lactation was then initiated by administration of cloprostenol and subsequent milk production was compared to that of heifers lactating after a normal pregnancy. Injection of cloprostenol failed to initiate lactation. The level of prolactin but not cortisol in blood was substantially elevated following treatment. The results cast further doubt on the importance of prolactin in the lactogenic process but indicate the likely involvement of glucocorticoids.

Animals↗
PubMed1977

Artificial induction of lactation in ewes: the use of prostaglandin.

Injections of an anlogue of prostaglandin F2alpha (T.F.101) initiated secretion of copious amounts of fluid resembling normal ovine milk when given to non-pregnant ewes with developed mammary glands. Injections of T.F.101 elicited a substantial but transient increase in the levels of prolactin in plasma. Results for intact and ovariectomized ewes were similar.

Animals↗
PubMed1976

The relationship between the transfer of immunoglobulins, sodium and potassium into mammary secretion of the parturient ewe.

The experiment comprised two sections. First, radiotracer techniques were used to study the metabolism of IgG1 and IgG2 in 5 non-pregnant and 4 pregnant ewes. In the pregnant ewes, the rates of synthesis for IgG1 and IgG2 were similar to the rates observed in non-pregnant animals. However, the irreversible loss of IgG1 was significantly greater than IgG2 in pregnant ewes and IgG1 in non-pregnant ewes. Additionally, it was found that most of the IgG1 and virtually all of the IgG2 in mammary secretion was serum derived. Secondly, the levels of sodium, potassium and lactose and the selective index for IgG1 in mammary secretions of 5 pregnant ewes were monitored over the parturient period. The values of all the measures remained relatively constant until one day before parturition. From one day pre-partum, the levels of potassium and lactose in mammary secretion began to increase and had risen 2-3 fold by 5 days post-partum. Over the same period, the selective index for IgG1 decreased 20 fold, wehreas the level of sodium fell from approximately 32 mmol/l to 18 mmol/l. The concentration of IgG1 in plasma slowly declined from approximately 23 g/l to 15 g/l over the last 10 days of pregnancy. During the parturient period, the decline in plasma IgG1 levels, in comparison with IgG2, without alteration in the rates of synthesis of either immunoglobulin, supports the hypothesis that selective transport of IgG1 into mammary secretion occurs without degradation. The results also indicate that the transport of sodium and potassium into mammary secretions are altered over the parturient period.

Animals↗
PubMed1976

Artificial induction of lactation in ewes: the involvement of progesterone and prolactin in lactogenesis.

An attempt has been made to evaluate the importance of prolactin and 'progesterone withdrawal' for lactogenesis. The experimental model system used was the ovariectomized, non-pregnant ewe induced to lactate artifically by treatment with trigger hormone (either oestrogen, glucocorticoid or oxytocin) alone or in combination with progesterone. It appears from the results that prolactin is important in the lactogenic responses elicited by oestrogen and oxytocin but not as important in the response elicited by glucocorticoid. Moreover, the results suggest that, in the ewe, an appropriate positive hormonal stimulus will overcome the inhibitory influence of progesterone on lactogenesis.

Animals↗
PubMed1975

Artificial induction of lactation in cattle by use of dexamethasone trimethylacetate.

Injections of dexamethasone trimethylacetate initiated lactation in nulliparous Ayrshire heifers previously given a series of injections of oestradiol benzoate plus progesterone to develop mammary glands. Essentially normal lactation occurred following injection of 20 mg/day dexamethasone for 3 days, whereas injection of 40 mg/day for 4 days initiated secretion of smaller volumes of milk-like fluid containing relatively high levels of lipid. Milking alone failed to initiate lactation.

Animals↗
PubMed1975

Artificial induction of lactation in ewes: the relative importance of oxytocin and the milking stimulus.

Eight ovariectomized and four intact ewes were given oestrogen plus progesterone to develop the mammary glands. The intact ewes (group A) and four ovariectomized ewes (group B) then received four injections each day of 1 i.u. syntocinon for 5 days whereas the other four ovariectomized ewes (group C) received placebo injections of 0-9% saline. Milking commenced the day after the last of these injections. Yields of mammary secretion on the first day of milking--representing secretion accumulated during the injection of syntocinon or saline--for ewes in groups A and B were significantly higher than yields from group C (control) ewes. After 12 days of milking, yields of secretion from group A ewes were significantly higher than yields from group B ewes which in turn were significantly higher than yields from ewes in group C.

Animals↗
PubMed1975

Artificial induction of lactation in ewes: the role of prolactin.

The mammary glands of 30 non-pregnant, intact ewes were developed by subcutaneously injecting oestrogen plus progesterone at intervals of 3 days from day 0 to day 27. Two days later (day 29), 15 ewes were injected subcutaneously with 18 mg ergocryptine, to inhibit specifically secretion of prolactin. Then groups of ewes, each comprising five ergocryptiine-treated and five untreated ewes, were injected from days 30 to 34 with either four intravenous injections each day of 1 i.u. syntocinon, one subcutaneous injection each day of 10 mg dexamethasone trimethylacetate, or two subcutaneous injections each day of 2-5 mg oestradiol benzoate plus 6-25 mg progesterone. All ewes were milked by hand on days 30-50. Within 24 h of injecting ergocryptine, levels of prolactin in serum were reduced to negligible values (less than 2 ng/ml). Comparison of results for ewes not receiving ergocryptine showed that syntocinon, dexamethasone and oestradiol benzoate plus progesterone, at the doses used, were equally effective in initiating milk secretion. Peak yields of 0-23-0-27 kg/day were achieved. On the other hand, ewes treated with ergocryptine before syntocinon or dexamethasone produced peak yields of only 0-12-0-13 kg/day and ewes treated with ergocryptine before oestradiol benzoate plus progesterone produced negligible amounts of secretion. The results suggest that syntocinon and dexamethasone were either lactogenic per se or effected the release of hormones of the lactogenic complex other than prolactin. However, oestradiol benzoate plus progesterone appeared to be lactogenic by virtue of the influence of oestrogen on the secretion of prolactin.

Animals↗
PubMedDate not supplied

Giant cell interstitial pneumonia in a hard-metal worker. Cytologic, histologic and analytical electron microscopic investigation.

A case of biopsy-proven giant cell interstitial pneumonia in a patient with occupational exposure to hard-metal dust is reported. Bronchial washings performed several days prior to open-lung biopsy yielded an almost exclusive population of nonpigmented alveolar macrophages and pleomorphic, phagocytic multinucleated giant cells. Microorganisms, viral inclusions in the giant cells, epithelioid histiocytes and well-formed granulomas were not seen. This cytologic picture strongly suggests the presence of giant cell interstitial pneumonia in a patient with restrictive lung disease, particularly when exposure to hard-metal dust is known or suspected. A specific diagnosis early in the course of the disease may facilitate removal of the individual from the workplace and forestall the development of end-stage interstitial fibrosis. Additionally, the working environment may be modified to minimize inhalational exposure. Recognition of this entity by the cytopathologist may direct diagnostic efforts toward accurate histologic evaluation and the identification of particulates by microprobe analysis of either cellular or biopsy material.

Adult↗