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Biomedical subjects

G M Roomans

Publications and source records attributed to G M Roomans.

At least 163 records · Page 9Linked to original sources
PubMed1985

Effects of calcitonin on elemental distribution and ultrastructure of rat submandibular gland acinar cells.

The effect of calcitonin on rat submandibular gland acinar cells was investigated by X-ray microanalysis and electron microscopy. Calcitonin caused a transient increase of the cellular calcium and magnesium concentration, but did not affect the intracellular concentration of other electrolytes. The relative volume of intracellular mucus increased from 45% in control glands to 72% at 6 h after administration of calcitonin. Calcitonin caused an inhibition of the cellular response of the acinar cells to beta-adrenergic and cholinergic agonists. The changes in elemental composition and ultrastructure of the gland cells are probably due to inhibition of mucus release from the cells.

Animals↗
PubMed1985

X-ray microanalysis of exocrine glands in animal models for cystic fibrosis.

Elemental distribution and ultrastructure of the submandibular gland, the parotid gland and the pancreas were investigated in three suggested animal models of the disease cystic fibrosis: the chronically reserpinized rat, the chronically isoproterenol-treated rat, and the chronically pilocarpine-treated rat. To elucidate the cellular mechanism underlying the effects of these treatments, chronic effects of specific alpha - and beta -adrenergic agonists, as well as acute effects of reserpine and various agonists were also investigated. Reserpine, isoproterenol, and pilocarpine cause an increase in the calcium concentration in submandibular gland acinar cells, due to an increased calcium content of the intracellular mucus. In the parotid gland, reserpine and isoproterenol cause a decrease of the calcium concentration in acinar cells, due to a lower calcium content of the zymogen granules. In the submandibular gland, a decreased cellular Na concentration was noted after chronic treatment with isoproterenol or pilocarpine, and after a single dose of reserpine or isoproterenol. Ultrastructural changes in the exocrine glands investigated included excessive accumulation of intracellular secretory material and formation of abnormal uncondensed secretion granules. A common pattern in the 'animal models' appears to be (1) inhibition of secretion resulting in intracellular accumulation of secretory material, (2) synthesis of secretory macromolecules with altered cation-binding properties.

Adrenergic beta-Agonists↗
PubMed1985

Effect of metabolic acidosis on glycolysis in rat submandibular glands.

A decreased intracellular pH of exocrine glands could be an important factor in the pathogenesis of cystic fibrosis. Metabolic acidosis was induced in rats by adding ammonium chloride to the drinking water. An increased content of both total proteins and glycoproteins was found in the submandibular glands of the treated animals. The activities of the glycolytic enzymes - hexokinase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase - were also increased in these glands, whereas the activity of creatine phosphokinase was unchanged. The changes of protein concentration and enzyme activities in the submandibular gland of acidotic rats agree with findings in patients with cystic fibrosis and cultured fibroblasts from these patients. The acidotic rat might be a new promising animal model for cystic fibrosis research. The finding of increased enzyme activities in acidotic rats is, however, contrary to findings in other animal models of the disease.

Acidosis↗
PubMed1985

Post-mortem storage of tissue for X-ray microanalysis in pathology.

Possible alternatives to rapid freezing in liquid nitrogen of tissue for X-ray microanalysis of electrolytes at the cellular level were investigated. These alternatives might be used in cases where tissue becomes available for examination, e.g., at autopsy, but liquid nitrogen is not immediately available. Rat submandibular gland was used as a test tissue. Freezing of pieces of tissue in a conventional freezer at -80 degrees C or even at -20 degrees C retained the elemental distribution at the cellular level, and also retained the difference between a 'normal' and a 'pathological' (mimicked by an injection of a high dose of isoproterenol) situation. Storage of tissue in a refrigerator, or delaying the autopsy in anticipation of the arrival of liquid nitrogen is not recommended. Significant changes in the cellular ion content occurred if the tissue was left in the animal for 24h post-mortem.

Animals↗
PubMed1985

Recent advances in X-ray microanalysis in dermatology.

Electron microprobe and proton microprobe X-ray analysis can be used in several areas of dermatological research. With a proton probe, the distribution of trace elements in human hair can be determined. In contrast to sulfur, which is homogeneously distributed, calcium, iron, and zinc appear to be non-homogeneously distributed over the hair cross-section. Electron microprobe analysis on freeze-dried cryosections of guinea-pig and human epidermis shows a marked gradient of Na, P and K over the stratum granulosum. In sections of freeze-substituted human skin this gradient is less steep. This difference is likely to be due to a decrease in water content of the epidermis towards the stratum corneum. Electron microprobe analysis of the epidermis can, for analysis of trace elements, be complemented by the proton microprobe. Quantitative agreement between the two techniques can be obtained by the use of a standard. Proton microprobe analysis was used to determine the distribution of Ni or Cr in human epidermis exposed to nickel or chromate ions. Possible differences in water content between the stratum corneum of patients with atopic eczema and normal stratum corneum was investigated in skin freeze-substituted with Br-doped resin. No significant differences were observed. Proliferative reactions in the epidermis appear to be associated with increased levels of the elements P and K. Such changes were found in guinea-pig skin after exposure to sodium lauryl sulfate, and in plaques of skin from patients with psoriasis.

Animals↗
PubMed1984

X-ray microanalysis of the rat parotid gland after chronic sympathectomimetic stimulation.

The effects of chronic treatment with isoproterenol, reserpine, prenalterol, and terbutaline on rat parotid gland were investigated by electron microscopy and X-ray microanalysis. Chronic isoproterenol treatment induced lower potassium and calcium concentrations in the acinar cells. The cells were enlarged and contained more and larger zymogen granules than acinar cells in the controls. The zymogen granules contained markedly less sulfur, potassium, and calcium than in control animals. Prenalterol had effects similar to those of isoproterenol, but less pronounced, whereas terbutaline had no significant effects. Chronic treatment with reserpine caused a decrease in calcium levels but did not affect potassium levels. The changes in elemental composition in parotid acinar cells after chronic treatment with isoproterenol and reserpine differed from those induced by the same treatment in the submandibular gland of the rat.

Animals↗
PubMed1984

The chronically isoproterenol-treated rat in the study of cystic fibrosis: X-ray microanalysis of the submandibular gland.

The chronically isoproterenol-treated rat has been proposed as an animal model for cystic fibrosis. Ultrastructural studies showed enlarged cells with abnormally large mucus granules that were more often fused than in control animals. X-ray microanalysis of mucous acinar cells showed a significant increase in calcium levels, but unaffected magnesium levels. Combined treatment with isoproterenol and reserpine caused a very large increase in cellular calcium levels that appeared to be an addition of the single effects and increased magnesium levels (as in glands of rats treated with reserpine only). Chronic treatment with isoproterenol, reserpine, or both substances tended to decrease cellular potassium levels. Chronic exposure to the specific beta 1-agonist prenalterol or the specific beta 2-agonist terbutaline did not affect cellular calcium or potassium levels. It is concluded that chronic isoproterenol treatment affects the elemental composition of mucous acinar cells of rat submandibular gland differently from chronic reserpine treatment. The increase in cellular calcium concentration after chronic isoproterenol treatment does not appear to be due to an effect via beta-adrenergic receptors.

Animals↗
PubMed1984

Elemental analysis on freeze-dried sections of human skin: studies by electron microprobe and particle induced X-ray emission analysis.

The possibility of using the proton microprobe (PMP) in the elemental analysis of dermatological material, under conditions where the spatial resolution can be restricted to a few micrometers, was demonstrated. Comparison with the electron microprobe (EMP) technique using duplicate sections from the same human skin biopsies revealed that the PMP and EMP techniques are complementary and yield closely corresponding elemental distributions for elements of dermatological interest. The concentrations of phosphorus and potassium were low in the dermis, high in the stratum basale and stratum spinosum, and decreased markedly in the stratum granulosum to a low level in the stratum corneum. The sulfur concentration was highest in the stratum corneum.

Electron Probe Microanalysis↗
PubMed1984

X-ray microanalysis of rat exorbital lacrimal gland.

X-ray microanalysis was carried out on resting and stimulated rat exorbital lacrimal gland. The acinar cells of the resting gland are rich in calcium, which is localized in the secretory granules. In vitro stimulation with the cholinergic agonist carbachol leads to decreased cellular concentrations of K and increased concentrations of Na and Cl, concomitantly with intracellular vacuole formation. In vivo stimulation with pilocarpine leads after 90 min to loss of virtually all secretory material and also of the major part of the intracellular calcium. The secretory material is replenished after 24 h, and calcium levels in the acinar cells are then comparable to those in the resting gland. Chronic pilocarpine treatment induces significantly elevated calcium levels in the acinar cells of rat lacrimal gland.

Animals↗
PubMed1984

Effect of metabolic acidosis on acinar cells of rat submandibular gland.

Metabolic acidosis of the exocrine glands could be an important factor in the pathogenesis of the disease cystic fibrosis, a generalized exocrinopathy. Acidosis was induced in rats by addition of ammonium chloride to the drinking water. X-ray microanalysis of the mucous acinar cells of the submandibular gland showed increased intracellular calcium concentrations, and an increased intracellular potassium to sodium ratio. Transmission electron microscopy showed a swelling of the cells, and an increase in the relative cellular mucus content. The changes in structure and composition of the submandibular gland cells in the acidotic rat resemble those found in cells from cystic fibrosis patients and in pharmacologically induced animal models of the disease.

Acidosis↗
PubMed1984

X-ray microanalysis of single and cultured cells.

X-ray microanalysis of single or cultured cells is often a useful alternative or complement to the analysis of the corresponding tissue. It also allows the analysis of individual cells in a cell population. Preparation for X-ray microanalysis poses a number of typical problems. Suspensions of single cells can be prepared by either of two pathways: (1) washing - mounting - drying, or (2) centrifugation - freezing or fixation - sectioning. The washing step in the preparation of single or cultured cells presents the most severe problems. Cultured cells are generally grown on a substrate that is compatible with both the analysis and the culture, washed and dried. In some cases, sectioning of cultured cell monolayers has been performed. Special problems in quantitative analysis occur in those cases where the cells are analyzed on a thick substrate, since the substrate contributes to the spectral background.

Animals↗
PubMed1983

Quantitative X-ray microanalysis of semi-thick cryosections.

Methodological aspects of quantitative X-ray microanalysis of semi-thick cryosections (2--6 micrometers) of biological soft tissue were investigated. The preparation of a low background specimen holder is described. Scanning and scanning transmission images of the sections could be obtained, allowing identification and separate analysis of nuclei and cytoplasm. Parallel observations of histochemically stained adjacent sections in the light microscope allowed correlation of the microanalytical data with tissue morphology and histochemistry. Quantitative analysis could be carried out with the help of a standard: a gelatin/glycerol matrix containing mineral salts in known quantities, frozen and sectioned in the same way as the specimen. Mass loss under the electron beam was found to be comparable in specimen and standard. Comparison of various theoretical models for quantitative analysis showed that the 'P/B-method' (determination of the background intensity under the characteristic peak) is the most suitable for semi-thick sections. Factor determining the choice of accelerating voltage were analyzed. The usefulness of this specimen type is illustrated in some biological applications (human oral mucosa, rat salivary gland).

Animals↗
PubMed1983

Elemental redistribution and ultrastructural changes in guinea pig epidermis after dinitrochlorobenzene (DNCB) exposure.

Energy dispersive x-ray microanalysis and transmission electron microscopy were used to study ultrastructural and chemical changes occurring in the keratinocytes at the primary irritant dinitrochlorobenzene (DNCB) reaction. The results of the microanalysis showed a similarity between dose- and time-dependent effects of DNCB and were in accordance with the ultrastructural findings. With increasing cell injury (as judged by the ultrastructure) there was an increasing loss of phosphorus, potassium, and magnesium from the cells and an increase of cellular calcium content. Sodium and chloride were only moderately changed. Results recorded when the skin was exposed to a weak DNCB dose were in accordance with a stimulation of the basal keratinocyte cell population.

Animals↗
PubMed1983

Effect of the polymeric cryoprotectant dextran on fluid secretion in the isolated rabbit pancreas.

Physiological effects of the polymeric cryoprotectant dextran on an ion-transporting epithelium were investigated. In the isolated rabbit pancreas, dextran caused inhibition of fluid secretion and an increase of the concentrations of Na+, K+ and Cl-in the secreted fluid. Dextran did not affect the basal or pancreozymin-stimulated enzyme secretion. These effects of dextran can partially be explained by the fact that it is osmotically active and does not permeate through the epithelium. The effect of dextran on water transport can be compensated by lowering the ion concentrations in the solvent of the cryoprotectant. It is concluded that in cryoprotected ion-transporting epithelia the absolute ion concentration values obtained by X-ray microanalysis of frozen-hydrated specimens may not be completely correct, but that valid conclusions about intracellular ion distribution may still be drawn.

Animals↗
PubMed1983

Effects of culture medium on cystic fibrosis and normal fibroblasts studied by X-ray microanalysis.

The effect of culture medium from fibroblast cultures of cystic fibrosis (CF) patients and healthy controls on the elemental composition of fibroblasts was investigated by X-ray microanalysis. Exposure of normal fibroblasts to culture medium from CF fibroblasts caused an increase in calcium level. Exposure of CF fibroblasts to culture medium from normal cells caused an increase of the sodium content of CF cells to approximately normal levels; the calcium level of the CF fibroblasts, however, remained abnormally high. The results may indicate that CF fibroblasts lack a factor needed for the regulation of sodium transport. CF fibroblast medium apparently contains a factor that interferes with the regulation of calcium transport.

Biological Transport↗
PubMed1983

Effects of cystic fibrosis serum and fibroblast culture medium on ion distribution in rat submandibular gland.

The effects of cystic fibrosis (CF) serum and culture medium from CF fibroblasts on ion distribution in rat submandibular gland cells were investigated by X-ray microanalysis. These effects were compared to the effects of normal serum and culture medium from normal fibroblasts, of cholinergic and adrenergic agonists, and of the uncoupler 2,4-dinitrophenol. Incubation of gland tissue with CF serum or normal serum caused a significant decrease in potassium and calcium concentrations and an increase in sodium in mucous acinar and serous granular duct cells. CF serum gave a significantly larger decrease of the potassium level than normal serum. Culture medium from CF fibroblasts altered the cellular ion content in a way similar to CF serum. Exposure to medium from cultured normal fibroblasts did not affect the elemental composition of the gland cells significantly, compared to incubation with fresh medium or buffer. Hence, fibroblast culture medium is more suitable than serum to test specific effects of CF-associated factors. The changes in elemental composition of gland cells caused by CF serum or CF fibroblast culture medium mimic some of the effects of the agonist carbachol. They could, however, also in part result from nonspecific changes in membrane permeability.

Adolescent↗