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Biomedical subjects

G M Roomans

Publications and source records attributed to G M Roomans.

At least 181 records · Page 10Linked to original sources
PubMed1983

Cystic fibrosis - ultrastructural and microanalytical studies.

This review summarizes the contribution of electron microscopy and X-ray microanalysis to the study of the pathogenesis and the diagnosis of cystic fibrosis (CF). Light and electron microscopical studies of the most severely affected exocrine glands of CF patients (pancreas, tracheobronchial submucosal glands) generally show dilatation of the ducts and inspissation of mucous material. The ultrastructure of the acinar cells, however, is normal. Functional abnormalities in the gland can be demonstrated by X-ray microanalysis of the secreted fluid. In the search for the basic defect in CF use is often made of cultured fibroblasts. The ultrastructure of CF fibroblasts is basically normal. X-ray microanalysis shows significantly lower Na and higher Ca levels in CF fibroblasts. Several of the biological effects of the 'CF factor(s)', supposedly present e.g. in the serum of CF patients or in CF fibroblast culture medium, can be demonstrated by electron microscopy or X-ray microanalysis. Ultrastructural and X-ray microanalytical studies of 'animal models' for CF have shown that pathological changes in exocrine glands resembling some of those seen in CF patients, can be induced by interference with the nervous regulation of exocrine secretion.

Animals↗
PubMed1983

Quantitative biological X-ray microanalysis of bulk specimens: an analysis of inaccuracies involved in ZAF-correction.

In this paper the need for a biological approach to ZAF-correction is elucidated. Programming details are given for the compostion of a ZAF-correction program, specifically designed for biological specimens. BIOFLEX was written and set up as a working program to investigate two specific inaccuracies involved in quantitative X-ray microanalysis of biological bulk specimens: These are the poorly known composition of the organic matrix of the specimen as well as the poorly known specimen-beam spectrometer geometry. The outcome of our calculations, which is based on hypothetical (but representative) data, indicates that the organic matrix composition should be specified in elemental miss fractions. Moreover it was found that a poorly known geometry will give errors in concentrations of about 1 - 2%.

Animals↗
PubMed1983

X-ray microanalysis of cultured chondrocytes.

Methodological aspects of X-ray microanalysis of cultured chondrocytes from rabbit auricular cartilage were investigated. The cells were grown on a Formvar-film covered carbon specimen holder with a hole, which allowed examination in STEM. Several different fluids for washing away the culture medium from the cells were used. The effect of these fluids on the elemental composition of the cells was studied. The composition of cultured chondrocytes was compared with that of auricular chondrocytes in situ. Washing with 0.3 M sucrose gave the most satisfactory results. Subsequently, the specimen holders could be frozen in liquid nitrogen and the cells freeze-dried. The effects of human growth hormone on rabbit chondrocytes were investigated by X-ray microanalysis and transmission electron microscopy. Although no ultrastructural effects of hormone treatment could be observed, marked changes in the elemental concentrations in nucleus and cytoplasm of the chondrocytes were detected.

Animals↗
PubMed1983

Elemental changes at irritant reactions due to chromate and nickel in guinea-pig epidermis.

The present investigation was performed to examine the possibility of using energy dispersive X-ray microanalysis (EDX) to obtain information on epidermal reactions at irritant dermatitis. The elemental redistribution in the stratum germinativum and stratum spinosum of the guinea-pig epidermis after intradermal injection of a chromate and a nickel solution was studied in thick cryo-sections. The two solutions caused different changes in elemental content in both cell layers. Nickel sulfate caused a conspicuous decrease in K levels whereas Na and Cl were elevated in both cell layers. Potassium chromate caused an increase in Cl but lowered the P values. The result of this study show that it is possible to use EDX-analysis of thick skin sections to obtain information on physiologically relevant alterations in epidermis at irritant dermatitis.

Animals↗
PubMed1983

Acetylcysteine and its derivatives: functional and morphological effects on tracheal mucosa in vitro.

The effect of acetylcysteine and its derivatives on the mucociliary activity was investigated using a rabbit tracheal in vitro model system. High concentrations of N-acetyl-L-cysteine (Mucomyst), acetylcysteine, cysteine and glutathione significantly reduced the mucociliary activity. Application of Mucomyst (50 and 100 mg/ml) caused (within 1 h) marked changes in the ultrastructure of the ciliated epithelium of the rabbit trachea: compound cilia were commonly found and the epithelial cells showed signs of autolysis and were eventually shed. Although these lesions were obtained with higher concentrations than those generally present after inhalation or instillation, our results indicate the need of long-term in vivo studies of this drug.

Acetylcysteine↗
PubMed1982

Quantitative x-ray microanalysis of spleen lysosomes after acid phosphatase reaction.

A quantitative X-ray microanalytical study of 80 spleen lysosomes after histochemical reaction for acid phosphatase was carried out. Lysosomal Fe concentrations showed a skewed distribution, with most lysosomes having relatively low concentrations. The concentration of Pb in the lysosomes (indicative of acid phosphatase activity) showed a close to normal distribution. Although the plot of lysosomal Pb concentrations against Fe concentrations showed a marked scattering of the points, there is a statistically highly significant correlation between accumulated metal and acid phosphatase activity as determined from the Pb concentrations. The relation between concentrations of P and those of Pb in the lysosomes points to the possibility that Pb(H2PO4)2 is the main reaction product of the histochemical acid phosphatase reaction.

Acid Phosphatase↗
PubMed1982

Removal of zinc from subcellular regions of human spermatozoa by EDTA treatment studied by X-ray microanalysis.

The distribution of zinc in the head, neck and mid-piece of human ejaculated spermatozoa was investigated with energy-dispersive X-ray microanalysis. EDTA treatment within 1 h after ejaculation caused removal of 80-90% of the zinc in these regions. Storage for 24 h in own seminal plasma did not alter sperm zinc content. However, these aged spermatozoa only lost 35% of their zinc content on EDTA treatment. The stronger binding of zinc, occurring upon storage in seminal plasma, developed in all 3 parts of the cell investigated. These results are discussed in the light of the role of zinc in nuclear chromatin decondensation ability and sperm head-tail connection.

Edetic Acid↗
PubMed1982

Increased calcium content in cultured fibroblasts from trisomy patients: comparison with cystic fibrosis fibroblasts.

The elemental composition of cultured fibroblasts from trisomy patients, cystic fibrosis patients, and from healthy controls was compared by means of electron probe X-ray microanalysis. Significantly higher relative Ca concentrations (relative to phosphorus) and higher Ca/K ratios, were found in both trisomy and CF fibroblasts. Significantly lower relative Na concentrations and lower Na/K ratios were only found in CF fibroblasts; the Na content of trisomy fibroblasts was normal. Challenge with prostaglandin E2 did not cause any further rise in cell calcium in trisomy fibroblasts, nor did it cause elevated calcium levels in the control. If the mechanism causing elevated calcium levels in trisomy fibroblasts is similar to that causing abnormally high levels of calcium in CF fibroblasts, it might be located at the membrane level. The analytical results are discussed in the light of the observation that cyclic AMP levels are abnormally inducible in CF and trisomy fibroblasts.

Calcium↗
PubMed1982

Calcium and magnesium in exocrine secretion--an X-ray microanalytical study.

Calcium and magnesium distribution in mammalian exocrine glands under resting, stimulated and pathological conditions was investigated by X-ray microanalysis of thick and ultrathin cryosections. Ultrathin sections were cut from tissue frozen in the presence of a polymer cryoprotectant, dextran. The effect of this treatment on isolated rabbit pancreas. Dextran caused a disturbance in water and ion transport, partly due to an osmotic effect and the impermeability of the pancreatic epithelium to dextran; this does, however, not necessarily invalidate intracellular measurements on frozen-dried sections. Cholinergic stimulation of the rat pancreas caused a change of Ca distribution from the basal to the apical part of the cell; this may be a component of the secretory Ca flux. Kinetic considerations make a significant Ca movement via the ER-Golgi endomembrane space less likely. The mitochondrial Ca concentration is low, and not significantly changed by cholinergic stimulation. X-ray microanalysis was carried out on submandibular glands of rats after chronic treatment with reserpin and/or isoproterenol (an animal model for cystic fibrosis, CF). The acinar cells had elevated Mg and Ca and lowered K concentrations. Analysis of ultrathin cryosections showed high levels of Ca and Mg in secretory granules, mucus globules and the ER. Ca and Mg in the ER may be transported intracellularly with secretory proteins to secretion granules or mucus globules. The decrease in cell K may be due to efflux of K caused by elevated cytoplasmic Ca levels. A similar decrease in cell K was caused by incubation of rat salivary glands with diluted serum from CF patients, a treatment which has been reported to mimic the effect of a rise in cytoplasmic Ca.

Animals↗
PubMed1981

Effects of cystic fibrosis serum and cell culture medium on the mucociliary activity of the respiratory tract. An in vitro study in rabbits.

As previously reported a cystic fibrosis factor (CFF) is associated with the dyskinetic ciliary motion induced by serum and cell culture medium from patients with cystic fibrosis (CF). In this study a sensitive, standardization method, for the photoelectric recording of mucociliary activity was used to examine the effect of sera and media from cell cultures taken from patients with CF and healthy controls, on the mucociliary activity of rabbit trachea in vitro. No signs of decreased mucociliary activity were observed and electron microscopy showed normal ultrastructure and orientation of cilia.

Animals↗
PubMed1981

Quantitative electron probe x-ray microanalysis of biological bulk specimens.

X-ray microanalysis of thick biological specimens is of considerable practical interest. Quantitative analysis of this kind of specimens poses some difficulties, and quantitative methods are less well developed than for thin sections. In this tutorial, the various parts of the ZAF-corrections are examined in some detail, and special attention is given to possible problems with the use of the ratio model. In quantitative analysis of metals (Z greater than 20) in biological bulk specimens, attention should be given to secondary fluorescence by the continuum. Various types of standards are compared, both with respect to homogeneity and with respect to their effect of quantitation with the ZAF-correction method. In both respects, organic standards of the 'gelatin' or 'resin' type perform better than do crystal standards. The use of relative intensities (P/B-ratios) in quantitative analysis of biological bulk specimens is considered. In most, but not all, cases use of P/B-ratios has advantages over the use of absolute X-ray intensities.

Crystallization↗
PubMed1981

Ultrastructural studies on cultured fibroblasts from patients with cystic fibrosis.

The ultrastructure of cultured fibroblasts of patients with cystic fibrosis (CF) was investigated and compared with control cultures. CF-fibroblasts showed a significantly increased number of pinocytotic vesicles along the plasma membrane. Other differences in ultrastructure between CF-fibroblasts and controls could not be observed. Cytochemical localisation of calcium was studied after fixation in the presence of oxalate. In CF-fibroblasts, oxalate precipitates (presumably indicating the presence of calcium) were found in the cytoplasm, often associated with membranes of the endoplasmic reticulum and Golgi vesicles, and in association with nuclear membrane and plasma membrane. In control fibroblasts, oxalate precipitates were scarce. The results are in accordance with earlier findings of elevated calcium in fibroblasts from CF-patients, and point to a localisation of at least part of the excess calcium in the cytoplasm and microsomal fraction.

Adult↗
PubMed1980

Post-mortem elemental redistribution in rat studied by x-ray microanalysis and electron microscopy.

Post-mortem elemental redistribution in various tissues from rat was studied by means of electron probe X-ray microanalysis, and correlated with morphological changes in these tissues. Pancreas, liver and cardiac muscle were removed from the animal either immediately, or after some hours after death. Elemental distribution at the cellular level was studied by X-ray microanalysis of thick cryosections. Calcium redistribution at the subcellular level was studied using tissue fixed with glutaraldehyde/oxalate. In all tissues, post-mortem redistribution of electrolytes had taken place within 2 h. The cellular concentrations of Na, Cl and Ca increased markedly, those of Mg and K decreased; no significant changes were found in the concentrations of P and S. The number of oxalate precipitates (indicating the presence of calcium) increased both in the mitochondria and in the cytoplasm and endoplasmic reticulum, reaching a maximum at 2 h. Morphological changes included mitochondrial swelling and vesiculation of the endoplasmic reticulum. Since the post-mortem ion shifts are similar to those encountered in some diseases and types of cell injury, great care has to be taken in the interpretation of X-ray microanalytical results from autopsy material.

Animals↗
PubMed1980

Problems in quantitative x-ray microanalysis of biological specimens.

Use of quantitative methods in X-ray microanalysis of biological specimens has expanded the scope of this technique. Reliable quantitation in biological microanalysis is, however, not simple, and a number of difficulties are typical for biological specimens. The purpose of this tutorial is to signal problems in quantitative X-ray microanalysis of biological specimens and to discuss possible solutions. First of all, the instrumental configuration has to be optimized and the contribution of extraneous sources to the spectrum minimized. Contamination and mass loss during irradiation have to be reduced. After the spectrum is obtained, background subtraction and deconvolution routines are applied. The contribution of extraneous sources to the spectrum has to be accurately determined and subtracted from the initial spectrum. Standards have to be prepared that contain the elements of interest in a known amount and are homogeneous. The intensities in specimen and standard are then compared and corrections are applied to correct for differences in composition between specimen and standard that are relevant to the resulting X-ray spectrum. These corrections are relatively simple for thin specimens but may be more intricate for bulk specimens. It is then important to know under which conditions the quantitative procedure can be simplified.

Biology↗
PubMed1979

Elemental analysis of histochemically defined cells in the earthworm Lumbricus terrestris.

A method for preparation of biological specimens for electron probe X-ray microanalysis is described, that aims at retaining the original elemental distribution within the tissue at the cellular level. The tissue is without any chemical fixation, quench-frozen, and 16-micron sections are prepared with a conventional cryomicrotome, transferred to a carbon specimen holder and freeze-dried. Adjacent serial sections, collected on glass slides and stained with various histological procedures, are used to correlate the data obtained by X-ray microanalysis with other histochemical information on the same cell or tissue. To demonstrate the possibilities of the method, sections of the earthworm Lumbricus terrestris were analyzed. In the chloragogenous cells, high concentrations of Ca, Zn and P were found. The inner and outer muscle layer show slightly different properties, both with regard to elemental composition and to myofibrillar ATPase activity.

Animals↗
PubMed1979

Interaction of cations with phosphate uptake by Saccharomyces cerevisiae. Effects of surface potential.

The effect of bivalent cations on phosphate uptake by Saccharomyces cerevisiae was investigated. Phosphate uptake via the Na+-dependent transport system at pH 7.2 is stimulated by bivalent cations. The apparent affinity of phosphate for the transport mechanism is increased, but the apparent affinity for Na+ is decreased. Uptake of phosphate via the Na+-independent transport system is accompanied by a net proton influx of 2H+ and an efflux of 1 K+ for each phosphate ion taken up. At pH 4.5 phosphate uptake via the Na+-independent system is stimulated by bivalent cations, whereas at pH 7.2 uptake is inhibited. The effect of bivalent cations on phosphate uptake can be ascribed to a decrease in the surface potential.

Binding Sites↗