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Biomedical subjects

W H Hackeng

Publications and source records attributed to W H Hackeng.

At least 55 records · Page 3Linked to original sources
PubMed1987

The effect of age on the renal response to PTH infusion.

The renal responses to PTH infusion were compared in two age groups of healthy subjects. Basal nephrogenous cyclic AMP (NcAMP) was higher (1.68 +/- 0.74 vs. 0.97 +/- 0.50 nmol/dl GF; P less than 0.05) and TmPO4/GFR was lower (0.93 +/- 0.21 vs. 1.16 +/- 0.14 mmol/liter; P less than 0.025) in 10 elderly subjects compared with 12 young adults. Creatinine clearance was decreased in the elderly (84.8 +/- 25.7 vs. 144.7 +/- 43.2 ml/min; P less than 0.005) and serum iPTH tended to be increased (0.15 +/- 0.11 vs. 0.11 +/- 0.03 pmol/liter). Following the infusion of 3 IU bPTH/kg bodyweight, no significant differences in delta NcAMP and delta TmPO4/GFR were seen between the groups. When responses were expressed as percentual change of basal level, elderly subjects showed a % NcAMP of 1831 +/- 1200 which was comparable with 2038 +/- 1503% in young adults. However, the percentual change in TmPO4/GFR was significantly higher in elderly persons (24.2 +/- 11.9 vs. 11.9 +/- 8.0%; P less than 0.01). In young subjects, virtually absent TmPO4/GFR responses were found in 3 cases with a relatively low basal TmPO4/GFR (between 0.92 and 0.98 mmol/liter), but these cases showed normal increases in NcAMP. Elderly subjects retained a considerable delta TmPO4/GFR notwithstanding a basal TmPO4/GFR below 0.92 in seven out of 10 cases. These results confirm the existence of a slight increase in parathyroid activity in the elderly. In addition, they suggest an augmented sensitivity of the renal tubule concerning PO4 reabsorption in elderly subjects. It is speculated that this phenomenon is related to the fall in bone mineral retention in senescence and might reflect a defense mechanism against phosphate overload.

Adult↗
PubMed1987

Human medullary thyroid carcinoma in tissue culture; secretion of calcitonin and carcinoembryonic antigen.

Monolayer cultures of medullary thyroid carcinoma (MTC) cells were prepared from 5 patients with familial and 4 with sporadic MTC. Basal calcitonin (CT) release decreased rapidly during 17 days in culture. Addition of extra calcium (2 mmol/l) or dibutyryl cyclic AMP (dBcAMP, 3 mmol/l) increased CT release in all investigated cultures (p less than 0.01). No significant differences were observed between cell suspensions prepared from familial and those from sporadic MTC. Carcinoembryonic antigen (CEA) was found in 3 out of 5 MTC cell suspensions from patients with familial tumors and in 2 out of 2 sporadic tumors. Only two cultures secreted measurable amounts of CEA, which decreased with culture time but at a much slower rate than that of CT release. CEA release was not affected by the addition of calcium and dBcAMP. This study shows an absent relation between basal and stimulated CT and CEA release by cultured MTC cells.

Bucladesine↗
PubMed1987

Multiple endocrine neoplasia syndrome type 2: the value of screening and central registration. A study of 15 kindreds in The Netherlands.

Since 1975, 10 families with the multiple endocrine neoplasia (MEN)-2A syndrome and five with the MEN-2B syndrome, making a total of 101 patients, have been identified in The Netherlands. Twenty-three of the MEN-2A patients died before the start of the screening program. The average age of the patients whose death was due to pheochromocytoma (n = 11) or medullary thyroid carcinoma (n = 12) was 34.9 and 49.2 years, respectively. Eighty-seven patients with the MEN-2A syndrome and eight with the MEN-2B syndrome underwent thyroidectomy for C-cell hyperplasia and/or medullary thyroid carcinoma. Eighteen patients had signs or symptoms caused by MEN-2A (group A), 60 were relatives of these patients who had been found to be affected at the first screening of the family (group B), and nine relatives had had negative screening results that later became positive (group C). Five patients had signs or symptoms due to MEN-2B (group A) and three were relatives of these patients who had been found to be affected at the initial screening (group B). To assess the effect of screening, we compared these groups with respect to the occurrence of metastatic medullary thyroid carcinoma at thyroidectomy and the results of the postoperative calcitonin tests. Among the MEN-2A families, 72 percent of group A, 33 percent of group B, and none of group C were found to have metastatic medullary thyroid carcinoma at surgery. In the MEN-2B families, all five patients in group A and one of the three patients in group B had metastatic disease. The "cure rates" in these three groups with MEN-2A, as determined by stimulated calcitonin assessment, were 11, 57, and 100 percent, respectively. One of the five patients with MEN-2B in group A and two of the three patients in group B showed normalization of the stimulated calcitonin value after surgery. From these results, it may be concluded that screening can lead to the detection of medullary thyroid carcinoma in an earlier stage, which in turn may permit curative treatment and improvement of both prognosis and life expectancy. The need for supervision of affected families by central registration to promote periodic examination and to guarantee the continuity of such screening is discussed.

Adrenal Gland Neoplasms↗
PubMed1987

Decrease of serum testosterone by cyproterone acetate accompanied by an unexpected increase of calcitonin secretion capacity.

The interaction between testosterone and calcitonin secretion capacity was studied in 9 patients with prostatic cancer. Treatment with the antiandrogenic agent cyproterone acetate resulted in an expected decrease in serum testosterone but an unexpected and unexplained increase in calcitonin secretion capacity. The previous statement that a positive correlation between sex hormones and calcitonin secretion capacity can be recognized probably requires revision. This unexpected effect of cyproterone acetate had possible additive beneficial advantages for treatment, such as bone mass sparing and its analgesic effect.

Aged↗
PubMed1987

Stimulation of calcitonin secretory capacity by increased serum levels of testosterone in men treated with tamoxifen.

Previous studies have suggested that sex steroids, including both oestrogen and testosterone, influence calcitonin secretion. However, a negative effect of gonadotrophins on calcitonin has not been excluded. Twelve men with infertility and low-normal serum levels of testosterone were studied before and during tamoxifen therapy. Increases in the serum levels of LH, FSH, testosterone and calcitonin were observed after treatment. Our findings suggest that testosterone has a direct influence on calcitonin secretion.

Calcitonin↗
PubMed1987

Bromocriptine is unable to suppress TRH-stimulated beta-endorphin/beta-lipotropin and cortisol secretion in normal pregnant women after delivery.

The course of plasma beta-endorphin/beta-lipotropin, cortisol and prolactin (PRL) levels was followed from 0.5 till 5 h after normal delivery in 13 healthy women. Six subjects who did not want to breast-feed their child received 2.5 mg bromocriptine orally 1 h after delivery. After 3 h the effect of the intravenous administration of 200 micrograms thyrotropin-releasing hormone (TRH) was also measured. Elevated plasma beta-endorphin and cortisol levels decreased after delivery in a (log) linear fashion which was not influenced by bromocriptine. TRH elicited a significant short-lived identical increase in plasma beta-endorphin/beta-lipotropin concentrations in the control and the bromocriptine-treated subjects. TRH similarly delayed the rapid decline in plasma cortisol levels in both groups of women. Basal and TRH-induced PRL levels were rapidly suppressed by bromocriptine. These studies show the presence of a paradoxical increase of beta-endorphin/beta-lipotropin and cortisol levels in response to TRH occurring shortly after delivery in normal women. This response cannot be mediated by the placenta. The absence of an inhibiting effect of bromocriptine on basal and TRH-induced beta-endorphin and cortisol release does not lend support to the hypothesis of the presence of a functionally active intermediate pituitary lobe in man early in puerperium.

Bromocriptine↗
PubMed1986

The renal sensitivity for endogenous parathormone in patients with primary hyperparathyroidism, vitamin D deficiency and renal stones.

Baseline levels and increases in urinary cyclic AMP excretion (UcAMP) and immunoreactive parathormone (iPTH) were studied before and during infusion of EDTA in euparathyroid patients with renal stones (n=11), patients with primary hyperparathyroidism (PHP; n=14) and patients with vitamin D deficiency (n = 12). In all three groups, EDTA evoked a significant rise in iPTH and UcAMP. In patients with PHP and in those with vitamin D deficiency, there was a sufficiently close relationship between increments in iPTH (delta iPTH) and in UcAMP (delta UcAMP) (r = 0.90, P less than 0.001 and r = 0.67, P less than 0.02, respectively) to use this model to assess renal sensitivity for changes to endogenous PTH levels. We quantified sensitivity of the kidney for PTH, by calculating the ratio delta UcAMP/delta TPTH for the three studied groups. The ratio was comparable in patients with renal stones (16.7 +/- 10.3) and PHP (13.8 +/- 4.9, P greater than 0.10), but was significantly increased in patients with vitamin D deficiency (33.2 +/- 17.9; P less than 0.01 versus patients with renal stones and P less than 0.01 versus patients with PHP). Within the group of patients with PHP there was no correlation between baseline serum calcium concentrations and the ratio delta UcAMP/delta TPTH. It is concluded that in patients with vitamin D deficiency, renal sensitivity to PTH is increased compared with patients with PHP and euparathyroid patients with renal stones, perhaps an expression of a teleological useful adaptation of end organ sensitivity.

Cyclic AMP↗
PubMed1986

Absence of effect of 24,25-dihydroxyvitamin D3 in primary hyperparathyroidism.

Nineteen patients with primary hyperparathyroidism were treated with 25 micrograms 24,25-dihydroxyvitamin D3 or placebo daily for 3 months according to double-blind cross-over protocol. Serum immunoreactive PTH, total and ionized calcium, urinary calcium excretion, tubular reabsorption of phosphate/glomerular filtrate, and urinary hydroxyproline excretion did not change significantly. Serum 24,25-dihydroxyvitamin D3 levels increased significantly from 1.4 +/- 2.2 (SD) nmol/liter to 38 +/- 11 nmol/liter during the treatment period. Serum 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 levels did not change. We conclude that pharmacological doses of 24,25-dihydroxyvitamin D3 have no suppressive effect on parathyroid function in primary hyperparathyroidism.

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Clinical implications of estimation of intact parathyroid hormone (PTH) versus total immunoreactive PTH in normal subjects and hyperparathyroid patients.

We describe a clinical study comparing the value of measurements of intact human PTH [hPTH(1-84)] and total PTH immunoreactivity [hPTH-(1-84) plus fragments]. A two-step immunochemical method was used to separate plasma hPTH-(1-84) from all circulating PTH fragments. The first step involved extraction and concentration of plasma PTH using solid phase antiamino-terminal PTH antibodies. After elution, the PTH immunoextract was analyzed using a sensitive mid- and C-region immunoassay. Complete separation in the immunoextraction step was proven by Sephadex G-75 gel filtration. hPTH-(1-84) values in fasting patients showed a clear distinction between those with primary hyperparathyroidism and those with nonparathyroid hypercalcemia, in contrast with small overlap in total immunoreactive PTH values. The hPTH-(1-84) values increased faster and more substantially in response to long EDTA and calcium infusion tests, compared with total PTH immunoreactivity, in normal subjects. Infusion of EDTA (10 mg/kg BW) in 5 min) elicited a readily measurable response of hPTH-(1-84) between 5 and 10 min after starting the infusion. Ingestion of 1000 mg calcium caused a decrease in hPTH-(1-84) in 1 h or less. More than 50% of patients with terminal renal failure had normal hPTH-(1-84) values despite elevated total immunoreactive PTH concentrations. We conclude that the two-step hPTH-(1-84) assay is more specific and sensitive than most regional PTH assays. Measurements of hPTH-(1-84) levels may identify disorders of parathyroid function at an early stage and provide a useful tool for the study of parathyroid physiology.

Administration, Oral↗
PubMed1986

Secretion of adrenocorticotropin, beta-endorphin and calcitonin by cultured medullary thyroid carcinoma cells. Effects of synthetic corticotropin-releasing factor and lysine vasopressin.

The present study was performed to investigate the potential of human medullary thyroid carcinoma (MTC) cells to secrete ACTH, beta-LPH/beta-EP. In addition, these studies might shed further light on the possible synthesis of a common precursor molecule for calcitonin (CT), ACTH and beta-LPH/beta-EP. MTC tissue was obtained from 10 patients (6 familial, 4 sporadic) without clinical and biochemical signs of Cushing's syndrome. Single cell suspensions were cultured for 1 to 2 weeks. Mean basal release of beta-LPH/beta-EP was 0.76 +/- 0.29 (SE) ng/10(6) cells/4 h (n = 10). Dibutyryl cyclic AMP (3 mM) stimulated beta-EP release significantly in 3 out of 7 cultures, while Ca2+ (2 mM) had no effect at all. The effects of the physiological regulators of pituitary ACTH and beta-LPH/beta-EP secretion, synthetic corticotropin-releasing factor (CRF-41) and vasopressin (LVP) were also studied in these MTC cell cultures. LVP (100 nM) had no effect on beta-EP release from MTC cells of all 8 cultures investigated. CRF-41 (10 nM) stimulated beta-EP release from 5 cultures and was without effect on 4. Maximal stimulation was noticed with 10 nM, while the effect of 100 nM CRF-41 was lower or absent. Stimulation was most outspoken in 3 cultures of familial MTC, whereas in 2 cultures of sporadic MTC CRF-41 stimulated beta-EP release marginally only after a 24 h incubation. LVP and/or CRF-41 stimulated CT release significantly in 3 cultures from sporadic MTC, while in these cultures the effect of CRF-41 on beta-EP release was either very small or absent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1986

End-organ resistance to PTH infusion in hypercalcaemic and normocalcaemic patients with solid tumours.

Ten hypercalcaemic patients with solid tumours were studied to evaluate the renal response on PTH infusion as assessed by nephrogenous cAMP excretion and maximum tubular re-absorption of phosphate. In addition, 20 normocalcaemic patients, 11 with an adenocarcinoma and 9 with a squamous cell carcinoma, were studied. All cancer patients had moderately extensive disease. Results were compared with those of 9 patients with primary hyperparathyroidism and with 10 elderly controls. All groups studied had comparable renal function, magnesium and 25-hydroxy-vitamin D levels. Comparable results were obtained in patients with an adenocarcinoma and in controls. cAMP response (delta nephrogenous cAMP) was significantly lower in the hypercalcaemic patients with a solid tumour compared with the controls (8.13 +/- 4.68 nmol/100 ml glomerular filtrate vs 29.52 +/- 25.62 nmol/100 ml glomerular filtrate; P less than 0.005). In the group of patients with primary hyperparathyroidism delta nephrogenous cAMP was 13.41 +/- 7.54 nmol/100 ml glomerular filtrate (P less than 0.06 vs controls). The group of patients with a squamous cell cancer showed an intermediate value of 14.83 +/- 10.74 nmol/100 ml glomerular filtrate (P less than 0.025 vs the normocalcaemic adenocarcinoma patients, but NS vs controls). In two hypercalcaemic patients with a solid tumour in whom PTH infusion was repeated after normalization of serum calcium no influence on renal responsiveness was observed. Responses of maximum tubular re-absorption of phosphate were lowest in the group of hypercalcaemic patients with a solid tumour and in the patients with primary hyperparathyroidism compared with controls (0.11 +/- 0.10 vs 0.22 +/- 0.09 mmol/l and 0.09 +/- vs 0.22 +/- 0.09 mmol/l; P less than 0.025 and P less than 0.005, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1986

Intact parathyroid hormone (1-84) in primary hypertension.

Intact parathyroid hormone (1-84) (PTH) concentrations were measured in serum of 83 hypertensive and 83 normotensive subjects, aged 20 to 69 years, matched for age and gender, and selected from the same open population. No significant differences in serum intact-PTH levels were found between the total group nor between groups based on three age strata. However, PTH was negatively associated with body weight and after adjustment for differences in body weight, significantly higher intact-PTH levels were found in hypertensive than in normotensive subjects, aged 20-39 years, but not in those aged 40 to 69 years. Our findings suggest that body weight is a confounding variable when comparing differences in intact-PTH between groups. Intact-PTH levels may be increased in a subgroup of young primary hypertensive subjects.

Adult↗
PubMed1984

A close correlation between the amount of met-enkephalin-immunoreactivity and epinephrine in adrenal pheochromocytoma tissue from patients with Sipple's syndrome.

The concentration of epinephrine, norepinephrine, dopamine, met-enkephalin-, ACTH-, calcitonin- and somatostatin-like immunoreactivity (IR) were determined in the extracts of 9 adrenal pheochromocytomas from 7 patients. Six of these patients had Sipple's syndrome. There was a close correlation between the amounts of met-enkephalin-IR and of epinephrine present in the tumor tissue (p less than 0.01). Such a correlation was not found between catecholamines and the other polypeptide hormones investigated. The relevance of the close parallel in the occurrence of met-enkephalin-IR and epinephrine in human adrenal pheochromocytoma tissue is unknown, but it underlines earlier observations in the normal bovine and rat adrenal medulla on a co-storage and co-release of these substances in normal circumstances.

Adolescent↗
PubMed1984

Hyperprolactinemia exerts a negative effect on the beta-endorphin content of the rat neurointermediate pituitary lobe.

Implantation of the PRL, ACTH, beta-endorphin (beta-EP), and beta-lipotropin (beta-LPH)-secreting transplantable rat pituitary tumor 7315a resulted in a suppression of the PRL and the ACTH content of the anterior pituitary gland and also of the beta-EP/beta-LPH content of the neurointermediate (NI) lobe. Treatment with bromocriptine further diminished the anterior lobe PRL content, whereas haloperidol partially inhibited this tumor-mediated diminution. The administration of these drugs did not influence the suppressed ACTH content of the anterior pituitary lobe. The diminished beta-EP/beta-LPH content of the NI lobe of tumor-bearing rats became completely normal after treatment with haloperidol, whereas bromocriptine administration further diminished the NI lobe beta-EP/beta-LPH content. There was a close correlation between the anterior pituitary lobe PRL content and the beta-EP/beta-LPH content of the NI lobe in all four groups of rats taken together (including nontumor-bearing controls, control tumor rats, and tumor rats treated with bromocriptine or haloperidol; P less than 0.01). Implantation of the pure PRL-secreting pituitary tumor 7315b resulted in hyperprolactinemia and a suppression of the PRL content of the anterior lobe and the beta-EP/beta-LPH content of the NI lobe, without affecting the ACTH content of the anterior pituitary lobe. There was a negative correlation between the level of the circulating PRL concentration and the beta-EP/beta-LPH content of the NI lobe. These results suggest a possible relationship between the synthesis of PRL by the anterior pituitary lactotroph and of the hormones of the NI lobe. The level of the circulating PRL concentration may play, directly or indirectly, a role in the regulation of both systems.

Adrenocorticotropic Hormone↗
PubMed1984

Corticotropin-releasing factor (ovine) and vasopressin exert a synergistic effect on adrenocorticotropin release in man.

The effects of ovine CRF, lysine vasopressin (LVP), and their interrelationships, and rat hypothalamic extract (HME), on ACTH and beta-endorphin release by human pituitary tumor cells from two patients with Nelson's syndrome and one with Cushing's disease and on ACTH and cortisol secretion in vivo were studied. In cultured pituitary tumor cells, both LVP and CRF greatly stimulated ACTH and beta-endorphin release at maximally active concentrations of 0.1 microM and 10 nM, respectively. At these concentrations, the combination of the two substances had an additive or synergistic effect on hormone release. Low concentrations of HME potentiated and/or were synergistic with CRF-mediated ACTH release. In vivo, the combination of CRF (1 microgram/kg) and LVP (10 pressor units) induced greater ACTH release than the sum of the responses to CRF and LVP alone. This synergistic effect of CRF plus LVP concerned only ACTH release, while cortisol release after CRF plus LVP was equivalent to the sum of the maximal increments in this hormone after CRF and LVP alone. The peak levels of cortisol after a combination of CRF and LVP probably reflect the maximum stimulatory capacity of the adrenal cortex. These data support the concept that in man, both ovine CRF and vasopressin are corticotropin-releasing factors which act synergistically. Both substances might well regulate, at the pituitary level, the responsiveness of the pituitary-adrenal axis to stimuli reaching the hypothalamus. A test using ovine CRF and LVP together might provide a better index of total pituitary ACTH reserve than one using the two compounds separately.

Adrenocorticotropic Hormone↗
PubMed1984

ACTH and beta-endorphin secretion by three corticotrophic adenomas in culture. Effects of culture time, dexamethasone, vasopressin and synthetic corticotrophin releasing factor.

Dispersed corticotrophic cells of 3 patients with Nelson's syndrome were studied in tissue culture for up to 25 days. During this culture period a parallel decrease with time was seen in ACTH and beta-endorphin-like immunoreactivity ( LIR ) release. A concomitant decline was observed for intracellular hormones. The time course of hormone release showed a parallel secretion of ACTH and beta-endorphin- LIR up to 8 h. Both the release of ACTH and beta-endorphin LIR were stimulated by 0.1 microM lysine vasopressin (LVP) in all three adenoma cell cultures. Dexamethasone (0.1 and 1 microM) suppressed basal hormone secretion for 4 h. Synthetic ovine corticotrophin-releasing factor (CRF) at 10 and 100 nM stimulated the secretion of ACTH and beta-endorphin LIR maximally. This stimulation was higher than observed with maximal stimulative concentration of LVP (0.3 microM). The CRF-mediated hormone secretion was calcium-dependent. Dexamethasone (0.1 microM) blocked the stimulating effect of 10 nM CRF completely. Gel-filtration chromatography demonstrated the cells to secrete both beta-lipotrophin (beta-LPH) and beta-endorphin. The ratio of beta-LPH to beta-endorphin released remained constant upon stimulation by LVP and CRF. HPLC studies demonstrate the possibility that several beta-endorphin fragments, including alpha-endorphin and gamma-endorphin, were secreted by cells from a Nelson tumour. CRF caused a simultaneous parallel stimulation of the release of these peptides.

Adenoma↗