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Biomedical subjects

D Gauthier

Publications and source records attributed to D Gauthier.

At least 37 records · Page 2Linked to original sources
PubMed1986

The influence of season and shade on oestrous behaviour, timing of preovulatory LH surge and the pattern of progesterone secretion in FFPN and Creole heifers in a tropical climate.

The aim of this work was to study the duration of oestrous behaviour, timing of the LH surge and the progesterone pattern with and without shelter during January and again in July in FFPN and Creole heifers in a tropical environment. From days 21 to 28 after a synchronization treatment (progesterone + PMSG), ten Creole heifers and ten FFPN heifers were checked for oestrus and sampled for blood every 3 h to assay plasma LH levels and every day from that oestrus to the following one to assay plasma progesterone content. Five heifers in each group were housed in a covered corral and five were exposed to the sun in a corral without shelter. The mean duration of oestrus for all the heifers was 14.0 h. There was a significant breed/season interaction: 21 h in July and 15 h in January for FFPN heifers. Sun exposure did not significantly affect the mean duration of oestrus. The distribution of onset of heat with respect to time of day was not uniform: 29% of the oestruses began between 5 and 8 a.m. and 19% between 8 and 11 p.m. The mean interval between onset of heat and maximal LH value (3.58 h) only varied significantly with the season (1.6 h in January and 6.0 h in July; P less than 0.05) but was equivalent to those obtained by other authors. The plasma progesterone levels of both breeds were lower than those described for cows in temperate countries and were lower for shaded FFPN heifers in January (2.8 ng/ml) than in July (3.93 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Effect of underfeeding on testosterone-LH feedback in the bull.

This study was conducted to investigate the hypothesis that the low LH pulsatility induced by underfeeding may result from an altered negative-feedback response to testosterone in cattle. Eight 21-month-old Aubrac bulls were divided into two equal groups. The first group (group H) received a high level of nutrition (producing a gain in weight of 570 g/day) and the second group (group L) a low level of nutrition (producing a loss in weight of 330 g/day). After 52 days of underfeeding the bulls were hemicastrated, castrated 7 days later and then injected with 30 mg testosterone daily for 14 days, 10 mg daily for 7 days and 2.5 mg daily for 7 days. After hemicastration, LH pulsatility was higher (P less than 0.001) in group H (9.0 pulses in 24 h) than in group L (5.3 pulses in 24 h). After castration this value was the same in the two groups (24 pulses in 24 h). When the bulls were injected daily with 30 or 10 mg testosterone, the number of LH pulses in 24 h was lower (P less than 0.05) in group L (14.3 and 9.8 pulses in 24 h with 30 mg, and 17.3 pulses in 24 h with 10 mg) than in group H (27.8 and 25.5 pulses in 24 h with 30 mg, and 24.0 pulses in 24 h with 10 mg). When the animals received 2.5 mg testosterone daily, the number of LH pulses was the same in both groups (20.3 pulses in 24 h). These results indicate that the negative-feedback response of the LH-releasing system to testosterone is modified by underfeeding in the bull.

Animals↗
PubMed1985

Lung angiotensin converting enzyme activity in chronically hypoxic rats.

A study was carried out to test the hypothesis that the reduced lung angiotensin converting enzyme (ACE) activity which occurs in chronic hypoxia is related to the development of pulmonary hypertension rather than to hypoxia per se. Right ventricular mean systolic pressure (Prvs, mm Hg) and ACE activity (nmol/mg protein/min) in lung tissue homogenates were measured in seven groups of four rats placed in a hypobaric chamber (380 mm Hg; 51 kPa) for two to 24 days. Identical measurements were made on 11 groups of four rats, which were placed in the chamber for 24 days and then allowed to recover in room air for one to 153 days. After two days of hypoxia the mean Prvs (25.5 (SD 3.7] and the mean lung ACE activity (56 (4.6] did not differ significantly from control values. Exposure to hypoxia for four to 24 days caused a progressive increase in mean Prvs to 44.4 (5.9) and a progressive reduction in mean lung ACE activity to 34 (4.0). During recovery lung ACE activity increased and Prvs decreased, so that normal values were achieved by 15 and 56 days respectively. Decreased lung ACE activity may be related to haemodynamic factors associated with pulmonary hypertension rather than to hypoxia.

Animals↗
PubMed1985

[Induction of post-partum ovulation in creole cows by using a Norgestomet implant and temporary removal of the calf].

Two treatments were used to attempt to induce ovulation in anoestrous post-partum creole cows. The use of a Norgestomet implant for 7 days followed by removal of the calf for 48 h induced ovulation in 91, 83 and 71% of anoestrous creole cows treated respectively at 37, 48 and 51 days post partum (implant insertion). In the same time, the cycling rates of the control groups were 30, 35 and 35%, respectively. But calf removal for 48 h at 60 and 80 days without progestagen priming failed to increase the number of cycling cows compared to the control group. Whatever the treatment and the post-partum day, calf growth was not different between the treated and the control groups at 30, 60 and 90 days post-partum, and there was no mastitis.

Animals↗
PubMed1985

[Influence of rearing conditions on the frequency of diarrhea in newborn calves and the efficacy of oral treatment].

A survey was carried out in 181 holdings of various production types to measure the influence of calf housing conditions and feeding of cows during late pregnancy on the frequency of calf diarrhea and an oral treatment efficiency. A second objective was to compare the efficiency of the different oral rehydratants used. The frequency of diarrhea was 51%. Slightly more than half the cases occurred during the first week of life. The dam's unadequate feeding increased morbidity (53% versus 47% with adequate feeding). We were unable to measure the efficiency of good housing conditions, because only five holdings fitted the quality criteria which had been initially specified. In the other holdings, the cohabitation was found to be less harmful than separation in bad conditions: too many calves together, too small an area per animal, draughts or deficient air removal. Therapy efficiency was not significantly higher when appropriate feeding was given than with unadequate feeding. Treatment efficiency by an oral rehydratant only was lower with calves which were housed with their dam's than when they were outdoors. Three rehydratants, Electydral ND, Biodiet ND, Ionidiar ND had similar results that were significantly higher than those of the others. With the sodium acetate-based formula, Electydral ND, 30% of the calves recovered when it was given alone for 36 hours, 96% recovered when it was given for 72 hours, combined with oral antibiotic therapy for 36 hours.

Animal Husbandry↗
PubMed1984

Fluctuating levels of serum IgA in individuals with selective IgA deficiency.

Monitoring of donors with selective IgA deficiency, i.e., with less than 0.5 mg IgA/l, led to the observation that serum IgA levels wer not constant. Small but significant fluctuations in IgA levels were noted (coefficient of variance: 143%) which were greater than the variability inherent in the testing methodology (coefficient of variance: 10%). These fluctuations created difficulties in terms of defining IgA-deficient blood products and had implications with respect to the mechanisms involved in IgA deficiency. With respect to supplying IgA-deficient blood products, in our experience a cutoff level of 0.5 mg/l should be the maximum permissible IgA concentration in order to ensure that no adverse reactions occur in individuals with class-specific anti-IgA.

Autoantibodies↗
PubMed1983

Influence of dietary intake and weight variation on LH release after a gonadotrophin-releasing hormone (GnRH) injection during the post-partum period of the nursing cow.

The experiment was conducted to measure the effects of restricting dietary intake on LH release following a GnRH injection during the post-partum period in nursing cows. Eighteen multiparous Charolais cows were fed a low ration from 45 days pre-partum to 45 days post-partum, and received an intravenous injection of synthetic GnRH (55 micrograms) at 5, 15 and 30 days post-partum. Plasma LH concentration was measured during the 4 hrs following each injection. The cows were separated into 2 groups depending on whether their mean daily gain was negative (group 1) or positive (group 2). The peak plasma LH concentration and the total release of LH after a GnRH injection tended to increase during the post-partum period irrespective of the group. The maximum LH value and the total LH release following GnRH were higher in Group 1 than in Group 2 (p less than 0.05), at 5, 15 and 30 days post-partum. Furthermore, the maximal plasma LH concentrations recorded after GnRH were highly correlated with the mean daily weight gain post-partum (day 15, r = -0.50; day 30, r = -0.54).

Animals↗
PubMed1982

FSH and LH variations in beef cows during the postpartum period.

To study the plasma gonadotrophin profiles of 9 cows after parturition, blood samples were obtained every 20 min for 12 hrs on three occasions between 5 and 50 days postpartum and analysed by RIA techniques. The time of the first ovulation, as judged by plasma progesterone levels, varied from 30 to more than 60 days postpartum. Variations in mean levels of FSH and LH were not significantly correlated with the postpartum interval. However, the mean levels of plasma FSH and number of LH pulses were lower in females which had not ovulated than in those which had. The cows could be classified into four groups: group 1 with less than 4 LH pulses in 12 hrs and a mean plasma FSH level less than 138 ng/ml; group 2 with more than 4 LH pulses in 12 hrs and varying plasma FSH levels; group 3 with less than 4 LH pulses in 12 hrs and a mean plasma FSH level greater than 138 ng/ml; group 4 which had ovulated. This classification indicated that the LH and FSH levels progressed significantly (2.46 to 3.56 ng/ml, P less than 0.05; 120 to 159 ng/ml, P less than 0.01, respectively) from groups 1 to 3, and that they decreased in the females which had ovulated (group 4). Since the time of the first ovulation after parturition varied, it was not possible to demonstrate any relationship between that interval and the mean plasma gonadotrophin profiles. However, when ovulation was considered as time zero there was a clear increase in plasma gonadotrophin before ovulation.

Animals↗
PubMed1982

The influence of nutritional levels and shade structure on testicular growth and hourly variations of plasma LH and testosterone levels in young Creole bulls in a tropical environment.

Twelve Creole bulls 13.3 months of age were divided into three groups according to live weight. The first group received a low nutritional level and was housed in a shaded stable; the second group received a high nutritional level and was housed in the same stable as the first group; the third group received the same ration as the second group but was exposed to solar radiation. Live weight and testicular diameter were recorded fortnightly. After 65 days, the blood of the bulls was sampled every 20 min for 12 h. Plasma LH and testosterone were quantified by radioimmunoassay. There was no significant influence of solar radiation on the testicular growth or the hormonal levels. Underfeeding decreased testicular growth and the average plasma LH and testosterone levels. However, this action was effective only in decreasing the number of hormonal pulses per day (0.63 vs 2.55 LH pulses per day and 0.75 vs 2.50 testosterone pulses per day); it did not change the basal hormone levels. It is suggested that this decrease in LH pulsatility might be responsible for the slow testicular growth in the underfed bulls.

Animals↗
PubMed1982

Angiotensin converting enzyme activity and evolution of pulmonary vascular disease in rats with monocrotaline pulmonary hypertension.

We have investigated the role of angiotensin converting enzyme (ACE) in the development of pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular disease in rats given a single subcutaneous injection of the pyrrolizidine alkaloid monocrotaline. Thirty-six young female Wistar rats were divided into a test group of 27 animals and a control group of nine animals. Each test rat was given a single subcutaneous injection of monocrotaline (60 mg/kg body weight). On the first, third, fifth, seventh, tenth, twelfth, fourteenth, seventeenth, and twenty-second days after the injection of monocrotaline the mean right ventricular systolic blood pressure was measured in one control and three test rats. The animals were then killed and we measured the specific activity of ACE in serum and lung homogenate. We also evaluated muscularisation of pulmonary arterioles, medial hypertrophy of muscular pulmonary arteries, and right ventricular hypertrophy. The sequence of changes was as follows: muscularisation of pulmonary arterioles and medial hypertrophy of muscular pulmonary arteries were apparent seven days after administration of monocrotaline; pulmonary hypertension and reduced lung ACE activity occurred after 10 days; right ventricular hypertrophy was detected after 12 days. Serum ACE activity was unchanged. It is concluded that the reduction in lung ACE activity is a result rather than a cause of the pulmonary hypertension. This reduction in lung ACE activity may be a protective mechanism designed to limit the elevation of the pulmonary arterial pressure.

Animals↗
PubMed1982

Lung angiotensin converting enzyme activity in rats with pulmonary hypertension.

We have studied serum and lung tissue angiotensin converting enzyme (ACE) activity in female Wistar rats with pulmonary hypertension induced by two different methods. Chronic pulmonary hypertension was produced in one group of 10 rats (CH) by confinement in a hypobaric chamber (380 mmHg) for three weeks, and in another group fo 10 rats (M) by a single subcutaneous injection of monocrotaline (60 mg/kg body weight). In these two groups of tests rats and in 20 untreated controls (C), we evaluated right ventricular mean systolic blood pressure (Prvs mmHg), right ventricular hypertrophy, and serum ACE (n mol/ml/min). In lung tissue homogenate, we measured the specific activity of ACE (n mol/mg protein/min), alkaline phosphatase (AP) (IU/mg protein) and lactic dehydrogenase (LDH) (IU/mg protein). The Prvs in groups, C, CH, and M was 25 +/- 7 SD, 41 +/- 7, and 51 +/- 5, respectively. The ratio of right ot left ventricular weight (RV/(LV + S)%) in groups, C, CH, and M was 29 +/- 4, 52 +/- 5, and 56 +/- 7, respectively. The lung tissue ACE in groups C, CH, and M was 85 +/- 11, 65 +/- 20, and 22 +/- 5, respectively. In groups CH, and M the Prvs and RV/(LV + S)% were significantly elevated above control values while lung ACE was significant decreased (p less than 0.05). There was a significant inverse relationship between lung ACE on one hand, and Prvs (r = - 0.73) and RV/(LV + S)% (r = - 0.71) on the other hand. Serum ACE and lung AP were unchanged. In group M there was a slight but significant reduction in lung LDH. Chronic pulmonary hypertension, irrespective of its method of production, is associated with decreased lung ACE. The reduction in lung ACE is inversely proportional to the severity of pulmonary hypertension and right ventricular hypertrophy.

Alkaline Phosphatase↗
PubMed1982

[Seasonal variations in creole heifer cyclicity: effect of growth, age and emotivity].

The ovarian and estrous activities in creole heifers have been studied in Guadeloupe in a tropical environment. We carried out two experiments. In the first one, all the heifers from the research station's herd were blood-sampled twice every 2 months at a 10-day interval to determine their ovarian activity. The observations were ranked in order of ascending live weight, and the percentage of heifers showing ovarian activity was calculated for consecutive 10-kg increments in live weight from 115 to 275 kg. The percentage showing ovarian activity (Y) was subjected to probit transformation and related to live weight (X); probit Y = 12.4 log10 X - 23.7. The equation for observations ranked in order of ascending age and the percentage of heifers showing ovarian activity calculated for age increments over 2 consecutive months was: probit Y = 7.06 log10 X - 3.9. Furthermore, the percentage of cyclic heifers in the herd varied from 40 p. 100 in September 1979 to 0 p. 100 in July 1980 and then to 30 p. 100 in September 1980. The percentage of cyclic heifers at a given period of observation was highly correlated with the mean daily increase in body weight (r = 0.86). In the second experiment, 12 heifers with a high feed level were blood-sampled weekly and checked for estrous daily with an androgenized female with a chin ball mating harness. The mean duration of a "normal cycle" (interval between two estruses: more than 15 but less than 31 days) was 21 days. There was no variation of ovarian activity with the month of the year, but the incidence of silent ovulation was high (23.7 p. 100). The seasonal variation of this percentage is shown. Female emotivity was also an important factor: emotional heifers had a higher percentage of silent ovulations than unemotional heifers (27 vs 17 p. 100) and a smaller mean daily gain (180 vs 280 g).

Age Factors↗
PubMed1981

[Influence of undernutrition in the lactating cow on ovulation induction by serum gonadotropins (PMSG) during the post-partum period].

Two experiments were carried out to assess the influence of undernutrition on postpartum ovulation in nursing Charolais cows after PMSG injection. In each experiment, the nursing cows were divided into 2 groups: one fed at a low nutritional level and the other at a normal nutritional level. In the first experiment, 19 animals were injected on post-partum days 15 and 30 with 600 IU of PMSG; in the second experiment, 34 received the same injection on post-partum day 54 after 9 days of priming with a Norgestomet implant. On post-partum day 15, only one cow in each group ovulated. At post-partum day 30, 1 out of 8 cows at the low nutritional plane ovulated vs 5 out of 9 at the normal nutritional plane (P less than 0.05). Likewise, on post-partum day 54, 5 out of 14 cows at the low nutritional plane ovulated vs 17 out of 17 at the normal nutritional level (P less than 0.05). Therefore, there is a time during the post-partum period when the nursing cow ovary does not respond to PMSG by ovulation. The length of this time is increased by undernutrition.

Animals↗
PubMed1979

Expanded linkage map of Vibrio cholerae.

An expanded linkage map of the Vibrio cholerae classical strain 162 chromosome has been prepared using a variety of new auxotrophic mutants. The chromosome consists of a single, linear linkage group. The map consists of 17 markers, which have been ordered; 20 mutational sites, which are tentatively ordered; five markers (ura-1, ser-2, mal-1, man-1, suc-1), which are linked but unordered; and three mutations (aro-2, cys-2 and cys-6) which showed little or no linkage. A proposal is made to standardize genetic nomenclature in V. cholerae genetic studies.

Chromosome Mapping↗