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Biomedical subjects

W J Henderson

Publications and source records attributed to W J Henderson.

17 recordsLinked to original sources
PubMed1979

Role of endogenous somatostatin in the secretion of parathyroid hormone and calcitonin.

Our previous in vitro and in vivo studies demonstrated that exogenous somatostatin inhibited secretion of both parathyroid hormone (PTH) and calcitonin (CT). This study evaluates the possible role of endogenous somatostatin in PTH and CT secretion. Rats receiving somatostatin antiserum i.v. had significantly greater circulating levels of serum immunoreactive PTH (iPTH) and CT (iCT) than rats receiving normal rabbit serum. In in vitro studies with bovine parathyroid tissue, the addition of somatostatin antiserum to the medium significantly increased PTH secretion from basal, low calcium-stimulated and high calcium-suppressed parathyroid tissue. These combined observations strongly suggest that endogenous somatostatin must have a suppressive effect on PTH and CT secretion. The in vitro observations with isolated parathyroid tissue suggest that somatostatin is synthesized by cells within this tissue. These data strongly suggest that somatostatin is a locally-synthesized hormone that has a role in modulation of both PTH and CT secretion.

Animals↗
PubMed1979

Silica and silicates in femoral lymph nodes of barefooted people in Ethiopia with special reference to elephantiasis of the lower legs.

Electron microscopy of femoral lymph nodes of barefooted Ethiopians show the presence of numerous particles of colloid-size and electron-density in the lysosomes of the macrophages in the gland. On diffraction analysis, the particles are found to be amorphous. Elemental microanalysis of the X-ray spectrum indicate the predominance of Si, Al and Fe. In elephantiasics some particles contain silicon alone, presumably silica. The distribution of the Al/Si ratios of the particles in subjects with elephantiasis of the lower legs show a difference from that of non-elephantiasics which is statistically "highly significant" at p less than 0.001. The importance of this as a possible aetiological factor in the disease is discussed. The hypothesis that the disease is discussed. The hypothesis that the disease is a silicosis of the peripheral lymphatics of the lower limbs is supported by the present study.

Aluminum↗
PubMed1979

Mepacrine pigmentation in systemic lupus erythematosus. New data from an ultrastructural, biochemical and analytical electron microscopic investigation.

A case of mepacrine pigmentation occurring in a patient with systemic lupus erythematosus has been investigated by fluorescent light microscopy, gas--liquid chromatography and analytical electron microscopy. There is strong evidence for the presence of mepacrine itself within the typical granules, which have been shown by electron microscopy to be membrane bound and intracellular. Analytical electron microscopy also showed that the granules contain large quantities of iron and smaller quantities of sulphur.

Adolescent↗
PubMed1978

Oxygen incineration and electron microscope x-ray microanalysis of mineral particles in biological tissues.

Techniques employed for the recovery from biological tissues of noncombustible fine particles such as asbestos, talc, kaolin and diatomaceous material were assessed by electron microscope x-ray microanalysis. Recovery procedures which have been proven successful for lung tissue were found to be impracticable for more solid types of tissues. Digestion techniques employing acids, alkalis or enzymes and standard incineration procedures were found to be unsatisfactory for human adrenal, cervix, liver and ovarian tissues when the resultant residues were examined by electron microscope microanalysis. The recovered particles were often completely masked with residues which were shown to be composed of organic elements. The use of oxygen during the incineration process completely removed this contaminating material in nearly all cases studied. When such procedures were used, clearly defined particles were recovered from the tissue, thereby permitting x-ray analysis. A quantitative analysis could then be made to estimate the particle content in a variety of tissues.

Electron Probe Microanalysis↗
PubMed1978

Effect of somatostatin on parathyroid hormone and calcitonin secretion.

This study evaluated the effect of somatostatin on immunoreactive parathyroid hormone (iPTH) and calcitonin (iCT) secretion in vivo in rats and monkeys and on iPTH secretion in vitro by normal bovine parathyroid tissue and by a human parathyroid adenoma. Somatostatin infusion promptly (within 0.5 h) suppressed both iPTH and iCT in both species studied in vivo, the suppression being progressive during the infusion period. In in vitro studies, somatostatin caused significant dose-related decreases in basal, low Ca-stimulated, and high Ca-suppressed PTH secretion from normal bovine parathyroid tissue and from basal and low Ca-stimulated PTH secretion from a human parathyroid adenoma. Therefore, somatostatin 1) suppresses both PTH and CT secretion in vivo; 2) acts directly on the parathyroid cell and presumably directly on the C-cell also; 3) acts upon normal and adenomatous parathyroid tissue; 4) suppresses basal, low Ca-stimulated and high Ca-suppressed PTH secretion; and 5) has a dose-related effect. The possible role of somatostatin in the physiological control of PTH and CT secretion (and therefore in Ca homeostasis), and in the pathogenesis of abnormalities of Ca homeostasis, requires further evaluation.

Animals↗
PubMed1978

Comparative effect of calcium and of the adrenergic system on calcitonin secretion in man.

This study evaluated the effects of adrenergic agents on immunoreactive calcitonin (iCT) secretion in normal man, and compared the time course and magnitude of these adrenergic effects with those caused by modifying calcium (Ca) ion concentration. Ca infusion (15 mg Ca++/kg iv in 4 h) significantly increased plasma iCT within 1 h, reaching 140 +/- 8% of baseline at 4 h. EDTA (50 mg/kg iv in 2 h) significantly decreased plasma iCT within 15 min, with nadir value of 53 +/- 4.9% of baseline at 2 h. The beta-adrenergic agonist, isoproterenol, significantly increased plasma iCT with 5 min, reaching 136 +/- 5.9% of baseline at 30 min. The alpha-adrenergic antagonist, phentolamine, significantly increased iCT within 15 min, reaching 132 +/- 8.6% of baseline at 45 min. The beta-adrenergic antagonist, propranolol, significantly suppressed iCT with 15 min, reaching 51.8 +/-6.3% of baseline at 2 h. Therefore, 1) the adrenergic system (without induced change in serum Ca) can modify CT secretion to as great a degree as can change in Ca ion concentration induced by standard Ca and EDTA infusion tests and 2) even basal secretion of CT can be modified by adrenergic influences. These data strongly suggest 1) that the adrenergic system is an effective modifier of CT secretion and 2) that the adrenergic system, as well as Ca ion concentration, may play an improtant physiological role in control of CT secretion in man.

Adult↗
PubMed1975

Role of adrenergic stimuli in parathyroid hormone secretion in man.

The role of adrenergic stimuli in the secretion of parathyroid hormone (PTH) in man was evaluated. Intradermal injections of isoproterenol, 0.15 mg, or epinephrine, 0.3 mg, caused significant prompt increases in serum PTH levels. These increases were not accompanied by any changes in serum calcium (Ca) during the period of observation. Phenylephrine, 1.5 mg, intradermally, did not cause any significant changes in serum PTH or serum Ca. Propranolol infusion alone significantly inhibited the basal secretion of PTH. This inhibition by propranolol was overcome by isoproterenol administration. The results indicate that 1) beta adrenergic agents increase PTH secretion whereas alpha adrenergic agents have no effect, 2) beta adrenergic stimuli probably play an important physiological role in basal PTH secretion in man.

Adrenergic Agonists↗
PubMed1975

Parathyroid hormone secretion in the rat: effect of aminophylline (38536).

Administration of aminophylline to intact rats did not cause a change in serum Ca, but did cause a significant increase in serum PTH. Administration of EDTA alone caused hypocalcemia, and a greater increase in PTH than that caused by aminophylline alone. Aminophylline plus EDTA given togeather caused no greater hypocalcemia, but a significantly greater increase in PTH than that by EDTA alone. Therefore, aminophylline increased PTH secretion when given alone, and also enhanced the PTH secretion stimulated by EDTA-induced hypocalcemia in vivo.

Aminophylline↗