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Biomedical subjects

H Metzger

Publications and source records attributed to H Metzger.

At least 199 records · Page 11Linked to original sources
PubMed1976

Critical-point drying and gold sputtering as applied to scanning electron microscopy of human reproductive tissues.

Improved techniques have been developed for washing, pinning, fixation, dehydration and critical-point drying of tissues of female and male reproductive tracts, gametes, for viewing by scanning electron microscopy. The sputtering method, performed by an ion gun, is applied to shadow and produce a thin film of gold. Technical details and metal coating are noted which are suitable to improve images of surface ultrastructure of cilia and microvilli. Studies using scanning electron microscopy, histological and histochemical techniques, and cinematography are described.

Desiccation↗
PubMed1976

Some physical chemical aspects of receptor-ligand interactions.

Quantitative evaluations of a variety of binding reactions of interest to immunologists have usually assumed that the reactants are homogenously dispersed in solution for purposes of calculation. In fact, many of these reactions involve cell-bound "receptors" which are present at exceedingly high local concentrations on discrete particles. We describe how such a distribution can influence the experimentally measured binding constants. We also briefly consider the additional complexities introduced when multipoint attachment between the ligand and cell-bound receptors is possible, and discuss the possible biological implications.

Binding Sites, Antibody↗
PubMed1976

Disparity of IgE binding between normal and tumor mouse mast cells.

The binding constants of rat and mouse IgE to normal and neoplastic rat and mouse mast cells have been measured. None of the cells distinguishes between rat and mouse IgE. Rat normal and neoplastic mast cells and mouse mastocytoma cells show very similar binding properties: k1 approximately 10(5), k-1 approximately 10(-5) and, therefore, KA approximately 10(10). Normal mouse mast cells also show a forward rate constant, k1, of 10(5) but the dissociation rate constant, k-1, is 50 times higher (5 X 10(-4)). The detergent-solubilized receptors reflect the properties of the cell-bound receptors. The discrepancy in binding by normal and neoplastic mouse mast cells remains unexplained but appears to be a reproducible finding for the cells from three strains of normal mice and three different mastocytomas studied.

Animals↗
PubMed1975

Human endometrial fluid kinetics as observed by scanning electron microscopy.

Segments of human endometrium, obtained during different stages of the menstrual cycle, were fixed in glutaraldehyde, processed by critical point drying, coated with carbon and gold, than observed with a scanning electron microscope under magnifications varying from 20 to 200,000. The endometrium was basically made of two different types of cells: secretory nonciliated cells and ciliated cells. Different types of secretory cells at different stages of secretory cycles were observed. The endometrial secretion is apocrine: the apical cell membrane of the endometrial cell ruptures, releasing secretory material. The rupture of cells within a given segment of the endometrium is asynchronous. Development of aptical microvilli, synthesis, storage, and release of endometrial secretory granules, and ciliogenesis are hormone dependent. The response of the ciliated and secretory cells of the endometrium varies throughout the menstrual cycle. This is particularly noted in cell specialization, the development of apical microcilli, and ciliogenesis.

Body Fluids↗
PubMed1975

Cell cycle-associated changes in receptors for IgE during growth and differentiation of a rat basophilic leukemia cell line.

The rat basophilic leukemia cell line (RBL-1) showed an inverse relationship between growth rate and expression of receptor activity for IgE. After prolonged exponential growth, the number of receptors per cell stabilized at 4-6 times 10-5. Cells in stationary cultures, which are arrested in the G1 phase of the cell cycle, continued to accumulate up to 0.9-1.7 times 10-6 receptors/cell with no increase in volume. Upon resuspension in fresh medium at low density, these cells were shown to lose up to 70% of the receptor activity within 4 h. Assessment of cultures synchronized by double thymidine block and cells fractionated by centrifugation of a Ficoll gradient indicated that the RBL-1 cells acquire receptors in the G1 phase of the cell cycle. No accumulation of active receptors occurred during the S and G2 phases, though the average cell volume increased. Cell division resulted in a drop in number of receptors per cell while the number of cell-bound receptors in the culture remained unchanged. This indicates that during mitosis receptors were simply distributed to daughter cells.

Animals↗
PubMed1975

Serum IgE levels during the potentiated reagin response to egg albumin in rats infected with Nippostrongylus brasiliensis.

Rats were immunized with 10 mug EA and alum; a low titer IgE anti-EA response was observed; subsequent infection with N. brasiliensis greatly potentiated this response. Serum from these rats was tested for its IgE content by a recently developed radioimmunoassay for rat IgE. The average serum level of IgE was 1.15 mug/ml; this level was not altered by immunization, but infection with N. brasiliensis was accompanied by an 80-fold increase in concentration of serum IgE. This increase could not be accounted for by IgE anti-EA or anti-worm antibodies. Infection with N. brasiliensis appears to have an adjuvant effect on IgE antibody responses to diverse environmental antigens as well as the experimentally induced IgE anti-EA response.

Adsorption↗
PubMed1975

Electrical sizing of liver cell nuclei by the particle beam method. Mean volume, volume distribution and electrical resistance.

Electrical sizing of liver cell nuclei gives similar results as histological techniques for the mean volume, the volume distribution and the proportions of the different nuclear volume populations. The electrical method has, compared to histological technics, however, the advantage of higher rapidity and accuracy. Due to the good volume resolution of the improved electrical sizing method two populations of nuclei with different mean volumes can be distinguished in rat liver tissue besides di-, tetra- and octoploid cell nuclei. In addition to the volume distribution curves, the mean electrical resistance of isolated liver nuclei can be determined by the electrical sizing method. A newly developed micromehod provides enough cell nuclei for electrical sizing from only 10 mg liver tissue in a few minutes. This should enable the measurement of nuclear volume distribution curves of human biopsy material from the liver and gastrointestinal tract for diagnostic purposes on a larger scale.

Animals↗
PubMed1975

Ionophore A-23187 induced histamine release from rat mast cells and rat basophil leukemia (RBL-1) cells.

Ionophore A-23187 releases histamine from normal mast cells apparently by promoting Ca++ influx (Foreman et al, Nature 245: 249, 1973). In our hands at concentrations of greater than 0.2 mug/ml release occurs in 1 to 2 min, is blocked by metabolic inhibitors, and is unaccompanied by cytotoxicity (trypan-blue uptake, lactic dehydrogenase (LDH) release). At higher doses (0.5 mug/ml) histamine release is followed by significant cytotoxicity, but again Ca++ is required. In parallel studies, we examined cultured rat basophilic leukemia (RBL-1) cells. These cells, which apparently have normal surface receptors for IgE, contained approximately 700 ng histamine/10(6) cells but did not release histamine when IgE-mediated release was looked for. They do not respond to doses of ionophore which would be expected to give non-cytotoxic histamine release. At higher doses histamine release is preceded by progressive LDH release: LDH release is 75% complete at 5 min whereas 10 min are required for 75% maximal histamine release. This reaction requires Ca++ and is temperature dependent but is not inhibited by metabolic poisons (2-deoxyglucose, dinitrophenol, CN-). These studies suggest that either Ca++ does not enter into these cells normally or that one or more mechanisms which are ordinarily triggered by the changes in Ca++ flow are unresponsive in the RBL-1 cells. These studies also underline the importance of ruling out cytotoxicity in ionophore-induced phenomena.

Animals↗
PubMed1974

The interaction of IgE with rat basophilic leukemia cells. II. Quantitative aspects of the binding reaction.

Previous studies indicated that cultured rat basophilic leukemia cells have surface receptors which bind IgE with high specificity. In this paper we describe some quantitative aspects of the phenomenon. The reaction mechanism appears to consist of a simple reversible binding reaction with k(1) = 9.6 x 10(4) M(-1) sec(-1) and k(-1) 1.6 x 10(-5) sec(-1) at 37 degrees C. The calculated K(A) is therefore 6 x 10(9) M(-1). The activation energy of binding was found to be 7.8 kcal/mol. The number of binding sites/cell varied between 3 x 10(5) to over 1 x 10(6). The binding was insensitive to pH's between 6-8 but at pH 3.0 complete dissociation of bound IgE occurred in approximately 1 min at 0 degrees C leaving the receptors for IgE intact. Ca(++) plus EDTA and Mg(++) plus EDTA produce a fairly marked reduction in binding capacity though these reagents alone produce much smaller effects.

Animals↗
PubMed1974

The interaction of IgE with rat basophilic leukemia cells. I. Evidence for specific binding of IgE.

A rat basophilic leukemia cell line originally described by Eccleston et al. (3) has been successfully transplanted into eight Wistar strains and adapted to suspension cell culture without noticeable morphological changes. The cells deplete the reaginic activity of mouse and rat immune sera to an extent roughly equivalent to that reported for normal rat mast cells. Studies utilizing radioiodinated antilight-chain antibodies and radioiodinated partially purified rat IgE indicate that the cells bind IgE to their surface membrane with high specificity. Heating or mildly reducing the rat IgE destroyed its binding activity. The binding is unaffected by the presence or absence of Ca(++) and Mg(++), and is markedly inhibited by reaginic but not by normal rat or mouse serums. The affinity of these cells for human IgE, if present at all, is substantially lower than for rat IgE.

Animals↗