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Biomedical subjects

P Gerber

Publications and source records attributed to P Gerber.

At least 73 records · Page 4Linked to original sources
PubMed1985

Medical consultation--contract versus tort?

A surgeon was sued for breach of contract for a failed sterilization, resulting in an unwanted pregnancy. It was conceded that the operation was carried out skillfully and with due care. The major ground relied on was that, whilst there may be no common law duty to warn of the small risk of spontaneous recanalization, the contract in the present case was for the male plaintiff to be sterilized, so that the failure to achieve this result constituted a breach of contract.

Australia↗
PubMed1985

Evidence for intravascular coagulation in systemic onset, but not polyarticular, juvenile rheumatoid arthritis.

After observing a child with systemic onset juvenile rheumatoid arthritis (S-JRA) who developed purpura fulminans in association with disseminated intravascular coagulation, with subsequent gangrene and autoamputation, we undertook a prospective study of coagulation parameters in children with JRA. Ten consecutive children with S-JRA, 10 children with rheumatoid factor-negative, polyarticular juvenile rheumatoid arthritis (P-JRA), and 10 age- and sex-matched controls were studied. Routine coagulation screening tests were performed, as were tests for plasma fibrinopeptide A (a sensitive measure of intravascular thrombin generation), factor VIII-related antigen (an endothelial cell protein), and platelet factor 4 (a platelet-secreted protein). Our studies suggest that activation of intravascular coagulation is common in systemic onset JRA, but not in rheumatoid factor-negative, polyarticular disease. The coagulopathy may cause severe morbidity. In addition, marked elevations of plasma factor VIII-related antigen suggest perturbation of endothelial cells and vascular involvement in S-JRA, but not in P-JRA. Normal ranges of platelet factor 4 indicate that intravascular platelet consumption does not occur in either type of JRA, despite the thrombocytosis common in both.

Adolescent↗
PubMed1984

Brain death, murder and the law.

The withdrawal of all nourishment and hydration from a patient who had suffered severe brain damage as a result of a cardiorespiratory arrest was recently held by a Californian court of appeal not to constitute an unlawful killing. The possible implications of this decision, both at common law and under the various criminal codes in Australia, are considered.

Australia↗
PubMed1984

Informed consent.

The requirements of consent to medical treatment, including the legal capacity of minors, psychotic patients, and prisoners to give binding consent to medical intervention, have increasingly presented a confused and anxious problem. A series of legal decisions of a binding or persuasive nature are analysed and five "rules", outlining the extent of the duty to advise and the degree of disclosure demanded by law, are advanced.

Adolescent↗
PubMed1984

Evidence that desensitization to the negative estrogen feedback is a prepubertal and not a postpubertal event in female rats.

Female rats were ovariectomized at 31 days of age, on the day of proestrus, or on the day of the first vaginal estrus if corpora lutea were seen in the ovaries. Immediately after castration, estradiol-17 beta (E2) or oil was administered via s.c. silastics capsules, or a 1:240 mixture of estradiol benzoate (EB) and cholesterol or cholesterol alone was unilaterally implanted into the hypothalamic ventromedial-arcuate region. Forty-eight hours after surgery the rats were decapitated and the serum concentrations of LH and FSH estimated. In rats implanted s.c. with E2 in anestrus, proestrus or estrus, estrogen treatment reduced the circulating LH level to 9.4; 60.4 and 33.6% and that of FSH to 49.5; 120.3 and 63%, respectively, of the concentration recorded in the corresponding controls implanted with oil. Following the intrahypothalamic implantation of EB, the serum concentration of LH was lowered to 20.8; 67.4 and 68.1% and that of FSH to 48.8; 87.0 and 62.0% as compared to the cholesterol-implanted controls. The findings clearly suggest that a major part of the change in sensitivity to the negative feedback of estrogen occurs prior to the first preovulatory surge of gonadotrophins.

Anestrus↗
PubMed1984

Evidence that inhibition of medial preoptic dopaminergic activity may be involved in the prepubertal desensitization to the negative oestrogen feedback in female rats.

Immature female rats were bilaterally lesioned in the medial preoptic area (MPOA) or hypothalamic ventromedial-arcuate region (VMAR) at 21 days of age and daily injected with the dopamine (DA) agonist bromocriptine (CB-154) through day 26. Estimation of the serum LH and FSH concentrations following ovariectomy and two injections of 0.05 micrograms oestradiol benzoate (OB)/100 g b.w. revealed that the desensitization to the negative feedback effect of OB induced by lesioning of the MPOA was almost completely prevented by CB-154. A similar effect of the drug was not found in rats lesioned in the VMAR. The DA antagonist alpha-methyldopa (alpha-MD) was then bilaterally implanted in the MPOA or VMAR of 28-day-old females. Evaluation of the gonadotrophin-inhibiting effect of OB on days 30-31 showed that medial preoptic, but not hypothalamic implants of alpha-MD reduced the sensitivity to the inhibitory action of OB. It is proposed that diminution of the dopaminergic activity in the MPOA may play a role in the prepubertal desensitization to the negative oestrogen feedback in female rats.

Animals↗
PubMed1984

Medial preoptic area, estrogen, and the peripubertal desensitization to the negative estrogen feedback in female rats.

Bilateral lesions placed in the medial preoptic area (MPOA) markedly diminished the luteinizing hormone-(LH-) and follicle-stimulating hormone- (FSH-) inhibiting effects of s.c. injected or intrahypothalamically implanted estradiol benzoate (EB) in ovariectomized immature rats. Desensitization to the negative estrogen feedback was also recorded in immature rats implanted into the MPOA with a mixture of 1 part EB and 240 or 360 parts cholesterol. Estrogen implants located in the hypothalamic ventromedial-arcuate region were ineffective in this regard. Whereas precocious puberty resulted from the implantation of EB into the MPOA, a delay of puberty onset was induced by medial preoptic implants of the antiestrogen clomiphene citrate which also enhanced the LH-suppressing effect of s.c. administered EB in prepubertal females. It is proposed that an increase of the estrogen concentration in the MPOA inactivates medial preoptic neurons that exert a restraining influence on tonic LH (and FSH) secretion by sensitizing the mediobasal hypothalamus to the negative feedback action of estrogen. This mechanism may be involved in the control of the onset of puberty in female rats.

Animals↗
PubMed1984

Varying sensitivity to the negative oestrogen feedback during the ovarian cycle of female rats: evidence for the involvement of oestrogen and the medial preoptic area.

The gonadotrophic response to a single injection of oestradiol benzoate (OB) was studied in acutely ovariectomized adult rats during the different stages of a 4-day ovarian cycle. The results showed a sudden decline of the sensitivity to the gonadotrophin-inhibiting effect of OB between metoestrus and dioestrus. This desensitization to the negative oestrogen feedback was probably caused by an oestrogen action on the medial preoptic area (MPOA). In rats ovariectomized and implanted with OB in the MPOA in metoestrus, an s.c. injection of OB on the presumptive day of pro-oestrus did not lower the circulating LH and FSH levels, whereas a clear suppression of gonadotrophin secretion was seen in females implanted with cholesterol in the MPOA or implanted with OB in the hypothalamic ventromedial-arcuate region. Similar findings were obtained in rats which had been ovariectomized 3-4 weeks before implantation. A final experiment demonstrated that bilateral lesioning of the MPOA also reduced the sensitivity to the negative feedback action of oestrogen in long-term ovariectomized rats. In all experiments performed, diminution of the oestrogen-induced inhibition of LH secretion was more marked than that of suppression of FSH secretion. It is proposed that desensitization to the negative oestrogen feedback, probably resulting from an inhibitory oestrogen action on medial preoptic neurones, is a prerequisite for adequate gonadotrophic support of preovulatory follicle maturation in the presence of a continuously rising oestrogen concentration in the blood.

Animals↗
PubMed1984

[Significance and mechanism of desensitization to the gonadotropin-inhibiting effect of estrogen. 1. Studies on prepubertal desensitization].

In immature female rats, both a distinctive diminution of the gonadotrophin-inhibiting effect of s. c. or intrahypothalamically implanted estradiol and a simultaneous rise of the estrogen and gonadotrophin levels in the blood were revealed during the last days preceding the onset of puberty. Based on these findings, studies on the neurohormonal mechanism underlying this prepubertal desensitization to the negative estrogen feedback were performed. Bilateral lesioning of the medial preoptic area (MPOA) which induced precocious puberty also diminished significantly the gonadotrophin-inhibiting effect of s. c. or intrahypothalamically administered estrogen. Similar responses were recorded following the implantation of very low quantities of estrogen into the MPOA, whereas medial preoptic implants of the antiestrogen clomiphene citrate impaired the spontaneous prepubertal desensitization and delayed the onset of puberty. It is concluded from the results that the prepubertal increase of the estrogen concentration in the blood itself induces the desensitization to estrogen by an inhibitory effect on medial preoptic neurons. Preliminary clinical and experimental findings suggest that a comparable mechanism may be operative in humans, too.

Animals↗