摘要:

SUMMARYThe effect of TRH (200 μg) on blood pressure, pulse rate, TSH and GH release was investigated in 10 acromegalics, four patients with non‐GH secreting pituitary tumours, and seven normal controls. TRH produced a rapid‐onset, short‐lived pressor response in the acromegalic group (A mean blood pressure 33 mmHg) compared to the two control groups (P<0.001). There was no response to the same volume of saline. The pressor response in the acromegalic group was not different in those who did or did not release GH. The pressor response to TRH was linearly related over the range 50–200 μg. Measurement of plasma noradrenaline and plasma renin activity during TRH testing in six acromegalics indicated that the pressor effect was neither mediated by adrenergic mechanisms, nor the renin‐angiotensin system. Echocardiographic monitoring in five of these six patients showed that there was a significant increase in directly measured end systolic, end diastolic dimensions and heart rate (allP<002), and calculated stroke volume (P<0001) and cardiac output (P<0.01) without changes in systemic vascular resistance. These data suggest that increase in preload, probably via venoconstriction, is the most likely factor producing the pressor response to TRH in a

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00807.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYLow serum total T4 associated with subnormal concentrations of thyroxine binding globulin (TBG) has been reported in up to 40% of euthyroid Australian aborigines. It has been suggested that these subjects show both diminished concentration of TBG and reduced TBG affinity for T4 (Sameet al., 1985). We have compared 12 euthyroid aborigines with low T4 (total T4 44±5 nmol/1) and aborigines with normal T4 (T4 99±9 nmol/1,n= 12) using measurements of free T4 and T3 by equilibrium dialysis. TBG was measured both by RIA (Henning, Berlin, FRG) and a method dependent on T4 binding (Corning Immophase). Aborigines with low T4 showed lower levels of free T4 (12.6±0.6 cf. 18.7±1.0 pM), free T4 index (66±8 cf. 98±13), total T3 (1.1±0.2 cf. 1.6±0.3 nmol/1), TBG RIA (140±0.6 cf. 25.0±1.2 ng/1), and TBG Immophase (9.0±0.5 cf. 22.0±1.2 mg/1) (P±0.01), but free T3 (5.3±0.4 cf. 4.7±0.4 pM) and TSH (1.9±0.2 cf. 1.8±0.2 mU/1) were not significantly different from the values found in aborigines with normal T4. Scatchard analysis of T4 and T3 binding was performed using serum diluted 1:20 000 for T4 and 1:500 for T3 (barbitone buffer pH 8.6, 4°C, dextran‐coated charcoal separation). In euthyroid low T4 aborigines compared to those with normal T4, both T4 capacity (106±14 cf. 238±13 nM,P±0.01) and affinity (5–05±1010cf. 8.47±1010M−1,P±0.05) were significantly reduced. Similarly, both T3 capacity (62±10 cf. 154±16 nM, P±0.01) and affinity (1.67×109cf. 2.28×109M−1,p<0.02) were reduced. A substantial minority of euthyroid Australian aborigines have a TBG variant characterized by both reduced capacity and affinity of T4 and T3. These findings suggest that TBG may be both qualitatively and quant

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00808.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYRadical transsphenoidal surgery in 58 patients with large non‐functioning pituitary tumours relieved pressure symptoms and disconnection hyperprolacti‐naemia without loss of pituitary function, and verified the diagnosis. Preoperative bromocriptine did not cause any shrinkage of non‐functioning tumours (n= 8), even up to 48 weeks. Thirty‐two patients not given postoperative radiotherapy are being followed‐up, and although two show minor CT scan evidence of tumour regrowth, for the others the delay in radiotherapy is enabling reproduction where required. In 20 patients with non‐invasive macroprolactinomas radical sugery caused no loss of pituitary function but cured eight, of whom one has relapsed; none of eight invasive prolactinomas was cured by surgery. Pre‐operative bromocriptine caused marked size reduction in seven of seven macroprolactinomas, but if continued beyond 6 weeks induced tumour fibrosis and uneven shrinkage which made surgery dangerous and unproductive. Selective transsphenoidal surgery relieved hyper‐prolactinaemia in 70% of patients with meso‐ (n= 15) or microprolactinoma (n= 24) usually without loss of pituitary function: the relapse rate was 1 per 88 patient years of follow‐up. Invasive prolactinomas, and macroprolactinomas showing uneven shrinkage with a short (up to 4 weeks) course of bromocriptine should have radiotherapy rather than surgery, while the patients most suited to surgery are those with mesoprolactinomas, or some macroprolactinomas with compact intrasellar shrinkage after short‐term bromocriptine. Microprolacti‐nomas generally did not benefit from surgery as compared to conservative therapy. In none of the tumour groups were the surgical findings an accurate predictor of postopera

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00809.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYAn in‐vitro perifusion system was used to investigate spontaneous ACTH release from human fetal (21–23 weeks gestation) and adult pituitaries. The pattern of ACTH release from fetal pituitaries (n= 7) exhibited a remarkable pulsatile character with a mean (± SEM) pulse interval of 11.3 ± 0.8 min. The mean pulse amplitude was 49.7 ± 6.3 pg, with a nadir to peak increment of 90.7 ± 10.4%. The mean ACTH release rate was 87.2±13.3 pg/2 min. Addition of the calcium chelator EGTA (4 nM) to the perifusion medium induced a significant (p±0.01) decrease in both ACTH release rate (from 102.0 ± 8.5 to 52.0 ± 9.9 pg/2 min) and ACTH pulse amplitude (from 57.7 ± 2.8 to 31.3 ± 4.6 pg) (n= 3). Administration of either 2 nM corticotrophin releasing factor (CRF) or 56 mM KCl induced 10‐ and 2‐fold increases in ACTH secretion, respectively (n= 2). Quarters of adult human pituitaries (n– 6) also secreted ACTH in a pulsatile fashion, with a pulse interval of 14.8±1.7 min, pulse amplitude of 86.7± 10.0 pg, nadir to peak increment of 84.5 ± 9.8%, and overall release rate of 167.2 ± 8.8 pg/2 min. These studies demonstrate that ACTH release from the isolated human pituitaryin vitrois characterized by high frequency/low amplitude pulses, independent of hypothalamic stimulation. Accordingly, this spontaneous calcium‐dependent pulsatile ACTH release apparently reflects the activity of an intrinsic intrapituitary p

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00810.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYContrary to the accepted view, a recent study using Sephadex column separation suggested that thyroxine binding globulin (TBG) binds T4 and T3 with similar affinity, but with a much larger capacity for T4 than T3. We have evaluated this finding by comparing this separation method with equilibrium dialysis, taking account of the effect of serum dilution with each method. Estimates of free T4 fraction by equilibrium dialysis (with magnesium chloride precipitation) were valid over a wide range of serum dilutions. In contrast, Sephadex column separation gave a major overestimate of free hormone (underestimate of binding) in less diluted serum, indicating that this method cannot be used to establish a value for T4 affinity independent of serum dilution. Such a systematic error will result in a greater underestimate of affinity for the ligand with higher affinity when two ligands are compared at a single serum dilution. By equilibrium dialysis at 37°C, the affinity of T4 for TBG was ∼13‐fold higher than that of T3, while the capacity of TBG for both T4 and T3 was close to the concentration of immunoreactive TBG. The previous report of similar T4 and T3 affinities appears to be due to a dilution‐dependent underestimate of T4 affinity inherent in Sephadex column separation. Direct comparison of binding kinetics of various ligands requires a separation method that is valid over a wide range of binding protein concentr

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00811.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYA total lack of neuroendocrine and vegetative circadian rhythms was observed in a patient with a familial degeneration of the anterior and dorso‐medial thalamic nuclei. Our findings support the role of the thalamus in regulating the periodicity of endocrine and vegetative function

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00812.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe uterine cross‐sectional area (UXA) of women with polycystic (PCO) or multifollicular ovaries (MFO) is significantly larger and smaller, respectively, than those of normal women during the early‐mid‐follicular phase of the menstrual cycle. In the present study the distribution of oestradiol in plasma from normal women and women with PCO or MFO was measured to determine if differences in the available fractions of oestradiol could account for the differences in UXA of women with PCO or MFO. No differences in plasma levels of oestradiol were detected and the concentrations of oestradiol present in a free state or bound to albumin were similar in normal women and women with PCO or MFO. The concentration of oestrone was significantly higher in plasma from women with PCO (516 ± 120 pmo1/1, mean ± SD) than in plasma from women with MFO (389 ± 91 pmo1/1) or normal women (376 ± 89 pmo1/1). Differences in UXA for women with PCO or MFO as compared with normal women cannot therefore be attributed to differences in available oestradiol concentrations. It is possible that abnormalities in oestrogen metabolism within uterine or other tissues may account for the UXA of women with PCO or MFO. Increased plasma oestrone levels in women with PCO may provide more substrate for conversion to oestradiol within the uterus whilst the smaller UXA of women with MFO may reflect both lack of normal cyclical increases of oestradiol and formation of biologically inactive oestradiol me

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00813.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYWe have measured GH and PRL changes following separate and combined administration of insulin and GH releasing factor (GRF) in six normal males. Peak GH responses to separate administration of insulin and GRF were comparable (71 4 ± 10.2 vs 70.1 ± 27.7 mU/1; mean ± SEM). However, the peak GH response following combined administration was significantly higher (120.8 ± 29.7,P<0.05) as was the total GH released as calculated by measuring the area under the curve (P<005). In contrast the PRL response to hypoglycaemia was not altered by the combined administration of insulin and GRF. This effect was not due to any direct action of hypoglycaemia or insulin at pituitary level since basal and 10−8M GRF stimulated GH release from rat anterior pituitary cellsin vitrowas not influenced by varying glucose and insulin levels. Our findings support the hypothesis that GRF and insulin‐induced hypoglycaemia release GH via different pathways which are, at least in part, a

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00814.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYOvulation was induced by a pulsatile infusion of GnRH in a patient with hypogonadotrophic amenorrhoea. In order to investigate the effect of short‐term withdrawal of gonadotrophin support in the luteal phase, the pulsatile infusion was stopped 3 d after ovulation and restarted 48 h later. After stopping the pump gonadotrophin and progesterone concentrations fell rapidly to very low levels, but when the infusion was restarted progesterone concentrations returned to normal mid‐luteal values. Menstruation occurred 14 d after the LH surge. We conclude that normal progesterone secretion by the corpus luteum can be restored after temporary withdrawal of gonadotrophin supp

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00815.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe physiological regulation of PRL secretion seems to involve the central serotonin system, since plasma PRL levels are enhanced by serotoninergic agonists and serotonin re‐uptake blockers. The aim of this study was to evaluate whether the influence of oestrogens on PRL is mediated by the hypothalamic serotonin system. The PRL response to fenfluramine, a serotonin agonist that releases the amine and inhibits its re‐uptake, was assessed in 10 normal men (aged 18–25 years) and in six castrated men (aged 18–24 years). In both groups, the effect of fenfluramine on PRL secretion was also evaluated on the sixth day after receiving clomiphene citrate, an oestrogen antagonist and partial agonist. In castrated men, fenfluramine administration was also performed on the seventh day after the last dose of testosterone enanthate (200 mg i.m. every 3 weeks for 4 months). Our results demonstrate that in normal men fenfluramine treatment significantly enhances plasma PRL levels, and clomiphene citrate treatment significantly reduces this effect. In castrated men, fenfluramine is also able to enhance PRL secretion but to a lesser extent; after clomiphene citrate treatment the increase of plasma PRL levels induced by fenfluramine rises to the normal range. We therefore suggest that in man oestrogens and aromatizable androgens influence PRL secretion at least in part by involving the activation of the hypothalamic serotonin

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1987.tb00816.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY