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B L Gupta

Publications and source records attributed to B L Gupta.

At least 37 records · Page 2Linked to original sources
PubMed1988

Fetal antigen retained by mature neurons and ependyma studied with a monoclonal antibody (6B9).

A mouse monoclonal antibody (MAb 6B9, isotype IgM) was raised against autopsy tissue samples from the central nervous system (CNS) of multiple sclerosis (MS) patients. By immunofluorescence microscopy, MAb 6B9 intensely stains most or all cells in fetal rats. However, MAb 6B9 differentially stains various cell types in adult rats. Neurons, ependymal cells, and adrenal chromaffin cells are stained intensely, whereas astrocytes and oligodendrocytes are not stained. The 6B9-reactive antigen (6B9 antigen) is sensitive to periodic acid, but insensitive to treatment with protease, RNase, or hyaluronidase. Results from immunofluorescence microscopy on semithin sections and cultured neuroblastoma cells indicate that 6B9 antigen is intracellular. This is supported by immunoelectron microscopy, where labeling for 6B9 antigen appears in the cytoplasm distinct from any identifiable organelle. Further studies on 6B9 antigen should reveal its chemical nature as well as the significance of developmental changes in its distribution.

Animals↗
PubMed1985

Electron probe X-ray microanalysis of the effects of Bacillus thuringiensis var kurstaki crystal protein insecticide on ions in an electrogenic K+-transporting epithelium of the larval midgut in the lepidopteran, Manduca sexta, in vitro.

An alkaline hydrolysate of Bacillus thuringiensis var kurstaki HD1 (Btk) parasporal crystals was administered at 25 micrograms ml-1 (f.c.) to isolated, short-circuited, midguts of tobacco hornworm (Manduca sexta) larvae. The short-circuit current (s.c.c.), a precise measure of K+ active transport, was inhibited by 78% in 10 min in Btk-treated midguts as compared to controls. The elemental concentrations of K, together with Na, Mg, P, S, Cl and Ca, as well as the water content, were determined by electron probe X-ray microanalysis (EPXMA) in the muscle cells, columnar cells and goblet cells, as well as in the extracellular goblet cavity and the bathing media. The average K concentration in the goblet cell cavity was 129 mmol/kg wet wt in control midguts but only 37 mmol/kg wet wt in Btk-treated midguts. The elemental concentrations, including that of K, in other cell compartments were much less affected by Btk, but a rise in total cell calcium is suggested. It has been previously suggested that in vitro Btk acts specifically on limited regions of the apical membrane of the midgut epithelial cells. The simplest interpretation of the EPXMA results would be that initially Btk interacts specifically with the goblet cell apical membrane, which bounds the goblet cavity and contains the K+ pump responsible for the s.c.c. and high transepithelial potential difference (p.d.). Such interaction results in a rapid disruption of K+ transport across the goblet cell apical membrane, leading to dissipation of the K+ gradient and loss of p.d. The histopathological changes previously reported by other workers would then be a consequence of K+ pump inhibition causing changes in the intracellular pH, Ca2+ etc. Some possible molecular bases for these specific interactions between Btk and cell membrane are discussed.

Animals↗
PubMed1984

X-ray microanalysis of elements in frozen-hydrated sections of an electrogenic K+ transport system: the posterior midgut of tobacco hornworm (Manduca sexta) in vivo and in vitro.

The lepidopteran midgut is a model for the oxygen-dependent, electrogenic K+ transport found in both alimentary and sensory tissues of many economically important insects. Structural and biochemical evidence places the K+ pump on the portasome-studded apical plasma membrane which borders the extracellular goblet cavity. However, electrochemical evidence implies that the goblet cell K+ concentration is less than 50 mM. We used electron probe X-ray microanalysis of frozen-hydrated cryosections to measure the concentration of Na, Mg, P, S, Cl, K, Ca and H2O in several subcellular sites in the larval midgut of Manduca sexta under several experimental regimes. Na is undetectable at any site. K is at least 100 mM in the cytoplasm of all cells. Typical in vivo values (mM) for K were: blood, 25; goblet and columnar cytoplasm, 120; goblet cavity, 190; and gut lumen, 180. The high K concentration in the apically located goblet cavity declined by 100 mM under anoxia. Both cavity and gut fluid are Cl deficient, but fixed negative charges may be present in the cavity. We conclude that the K+ pump is sited on the goblet cell apical membrane and that K+ follows a nonmixing pathway via only part of the goblet cell cytoplasm. The cavity appears to be electrically isolated in alimentary tissues, as it is in sensory sensilla, thereby allowing a PD exceeding 180 mV (lumen positive) to develop across the apical plasma membrane. This PD appears to couple K+ pump energy to nutrient absorption and pH regulation.

Animals↗
PubMed1984

The application of EDXS to the biological sciences.

The distribution of chemical elements in soft tissues may be faithfully preserved by very rapid freezing. Most often the material is then cryosectioned and the sections frozen-dried prior to analysis, but direct analysis in the hydrated state is an established alternative. For bulk specimens, the shape of the analysed volume is uncertain. But whichever current model is accepted, analytical spatial resolution must generally be limited to the order of 1 micron. Such specimens can be suitable for the specific analysis of cytoplasm, cell nuclei and large extracellular spaces but not for study on a finer scale. Analytical spatial resolution in the range 200-500 nm is obtainable with sections cut approximately 1 micron thick. In the frozen-hydrated state, small extracellular spaces can be analysed but multiple scattering obscures intracellular detail in the STEM image. The irradiation required for an EDXS analysis, approximately 50 nanoCoulomb (50 nanoAmpere seconds), need not produce intolerable radiation damage when spread over an area 200 nm or more in diameter. Finer structure, for example mitochondria and regions of rough or smooth endoplasmic reticulum, can be identified and analysed in frozen-dried cryosections cut approximately 100 nm thick. Recently such features have been visualized in 100 nm frozen-hydrated sections where the water is vitreous. This opens the prospect of analysing material where elemental distributions have been preserved on a very fine scale, since one might avoid even the ionic shifts from aqueous solution to supramolecular structures which must occur on freeze-drying. But radiation damage may be prohibitive when an irradiation of 50 nanoCoulomb is concentrated into a hydrated area less than 200 nm in diameter.

Animals↗
PubMed1983

Ionic distribution in dopamine-stimulated NaCl fluid-secreting cockroach salivary glands.

The compound, racemose, innervated salivary glands of the cockroach Periplaneta americana closely resemble in structure and function the mammalian salivary glands (C.R. House, Biol. Rev. 55: 417-473, 1980). The quantitative distribution of Na, K, Cl, Ca, Mg, P, and S was investigated in the P-cells secreting isotonic NaCl and in duct lumens by using electron probe X-ray microanalysis of frozen-hydrated and frozen-dried cryosections. In the unstimulated glands in vitro the cells had (mmol/l cell-H2O) Na, 10; K, 110; Cl, 39 while the primary saliva had Na, 153; K, 4; Cl, 151. With 1 mumol dopamine in the bathing Ringer solution the P-cells had Na, 25; K, 177; Cl, 58 and the primary saliva, Na, 153; K, 26; Cl, 172. During passage through the ducts, the primary saliva was modified by an absorption of NaCl: more in unstimulated than in stimulated glands. It is proposed that the cells have a Na-K-ATPase both in the apical and basal cell membrane, as in vertebrate choroid plexus, and dopamine might increase the K and Na conductance of the basal cell membrane.

Animals↗
PubMed1982

Use of the FBX dosemeter for the calibration of cobalt-60 and high-energy teletherapy machines.

The doses from the cobalt-60 teletherapy machines were measured using the FBX and secondary-standard dosemeters of Farmer-Baldwin type. The FBX dosemeter contained 0.20 mM ferrous ammonium sulphate, 5.0 mM benzoic acid and 0.20 mM xylenol orange in 0.05 N sulphuric acid. The values were compared with the values from a Fricke dosemeter and a graphite chamber used as primary standards. The values of the FBX, Fricke and graphite chambers agreed. There were, however wide differences among the different secondary-standard dosemeters themselves and with the FBX dosemeter. The FBX dosemeter was used for the measurement of central axis depth dose distributions for 5, 8, 10, 20 and 30 MeV electron and 42 MV x-ray beams.

Cobalt Radioisotopes↗
PubMed1982

Quantification for the x-ray microanalysis of cryosections.

Some problems of the quantitative analysis of diffusible elements in cryosections are reviewed. The two prevalent methods for obtaining concentrations from X-ray data, one based on characteristic radiation alone and the other on continuum-normalization, are recapitulated. Both methods seem suitable at cellular level while the latter seems preferable at finer spatial resolution. Recourse to both methods together is desirable in the analysis of frozen-hydrated sections especially when there is no peripheral standard. Selective local contamination is a particular hazard in the analysis of chlorine. In the case of sodium, physical parameters set restrictive limits to the minimum concentration measurable by 'energy-dispersive' X-ray spectrometry (about 20 mM kg-1) and to the spatial resolution attainable by diffractive X-ray spectrometry (approximately 0.2 micrometer). One obvious danger to meaningful quantitative analysis is inadvertent redistribution of diffusible elements during the moments preceding the freeze-quenching of a tiny piece of tissue. Data are presented to show that concentration changes due to simple evaporation are a real hazard prior to the quenching of sub-millimetre size samples.

Animals↗
PubMed1981

The x-ray microanalysis of frozen-hydrated sections in scanning electron microscopy: an evaluation.

The present status of the technique to measure concentrations of electrolyte elements and dry mass in or approximately 1 mum thick frozen-hydrated sections of soft biological tissues with electron probe X-ray microanalysis in a scanning electron microscope is critically reviewed. The technique is to quench-freeze fresh specimens to less than -180 degrees C, cut approximately 1 mum thick hydrated cryosections ( less than or equal to -70 degrees C), transfer on to a cold stage (less than -170 degrees C) of a suitable microanalytical arrangement, obtain scanning transmission images to identify the cell and tissue compartments, locate an electron probe (several mum2 to 100 nm) on the areas of interest and collect X-ray quanta. The X-ray quanta collected with suitable spectrometers (WDS and EDS) and processed with a computer using a comprehensive programme based on continuum normalization procedures ('Hall' programme). The cryosections are analysed first in a hydrated state and second after dehydration within the microanalyser column to obtain directly elemental concentrations in muM kg-1 wet wt and muM kg-1 dry wt of the compartments identified under the beam. The local water-fractions are estimated and the elemental concentrations converted into muM 1(-1) water. In the past 7 years the technique has been applied to obtain fully quantitative information on Na, K, Cl, P, S, Ca and H2O in more than ten types of tissue.

Animals↗
PubMed1981

Novel role of calcium in exocytosis: mechanism of nematocyst discharge as shown by x-ray microanalysis.

Mature nematocysts of the sea anemones Rhodactis rhodostoma and Anthopleura elegantissima contain a fluid that has a high concentration of solutes and is extraordinarily rich in calcium (ca. 500-600 mmol/kg wet weight); this contrasts with the surrounding cytoplasm which is rich in potassium but poor in calcium. The undischarged capsule is surrounded by a membrane that probably acts as a selective permeability barrier between the cytoplasm and the nematocyst fluid. During discharge the nematocyst moves to the surface of the nematocyte and comes into contact with the external sea water medium. Calcium, which may be bound to proteins in the undischarged state, is rapidly lost from the fluid; at the same time, sea water enters the capsule. In vitro experiments have already shown that calcium loss increases the osmotic pressure of the capsular fluid, causing an influx of water from the external medium; this influx appears to increase the hydrostatic pressure inside the capsule to the point that the thread everts explosively.

Animals↗
PubMed1980

Microprobe study of toad urinary bladder in absence of serosal K+.

The bulk of the intracellular potassium in mucosal epithelial cells from toad urinary bladder has been previously reported to exchange very slowly with the serosal medium, with a half-time of some 9 hr. This observation, based on chemical analyses of mucosal cell scrapings, has been reexamined with stimultaneous diffractive and energy dispersive electron probe X-ray microanalysis. Fifty-three intracellular sites in hydrated sections and 286 sites in dehydrated sections were studied in bladders from eight toads under baseline conditions and after removal of serosal K+ for 83-133 min, with or without 10(-2) M ouabain. The baseline data confirm and extend previous examinations of the intracellular ionic composition, and provide the most direct measure of intracellular water thus far available for this tissue. Removal of serosal K+ reduced the intracellular K+ content by 20%, increased intracellular Na+ content threefold, and slightly reduced the intracellular Cl- and water contents, qualitatively consistent with published chemical analyses. The intracellular Na+ content of mucosal origin, measured by radioactive tracers and chemical analyses of cell scrapings, has been reported to be unchanged under these conditions. Simultaneous addition of ouabain and removal of external K+ produced a dramatic fall in intracellular K+ of more than 80% in a third of the cells and reduced the mean intracellular K+ content by 60%; 20% of the cells appeared to retain K+ more effectively than the bulk of the epithelial cell population. We conclude that: (i) the low rate of net exchange of intracellular K+ with the serosal bulk solution primarily reflects recycling of K+ across the basolateral membranes, (ii) radioactive tracer and chemical measurements of the intracellular Na+ pool of mucosal origin substantially understimate the total intracellular Na+ content under certain experimental conditions, and (iii) the epithelial cells display a functional heterogeneity of response to the effects of adding ouabain and withdrawing external K+.

Animals↗
PubMed1980

Surgery in angina.

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Angina Pectoris↗
PubMed1979

The quantitative measurement of electrolyte elements in nuclei of maturing erythrocytes of chick embryo using electron-probe X-ray microanalysis.

Na, K and Cl measurements have been made on frozen sections of chick red blood cells throughout embryonic development, using electron-probe microanalysis. There is an apparent fluctuation in the levels of these elements during maturation, although the Na/K ratio remains fairly constant. The nuclear Na concentration resembles that of the cytoplasm, rather than that of the medium, at all stages. Inhibitor studies indicate that when cytoplasmic Na, K and Cl levels are altered, their corresponding nuclear levels are similarly affected. Additionally, the measurements in nuclei isolated in anhydrous media from lyophilized cells have shown artefactual accumulation of high Na, K, Ca and Mg.

Animals↗
PubMed1979

Quantitative electron probe X-ray microanalysis of electrolyte elements within epithelial tissue compartments.

The electron probe X-ray microanalysis of 1-micron thick frozen-hydrated sections provides a method to measure local concentrations of electrolyte elements (and H2O) in and around the cells in situ with an analytical spatial resolution of better than 0.2 micron and a sensitivity limit better than 10 mM with a standard error of less than 10%. Our microprobe studies on several epithelia transporting isotonic fluids have provided strong evidence that the electrolyte concentration in the interspaces suspected to be the sites of solute-solvent coupling may, on average, be as much as 35% more than in the bathing fluid. There also appear to be distinct concentration gradients in interspaces, the profiles of which differ according to the tissue geometry but particularly according to the location of the leaky cell junctions, suggesting that the osmotic equilibration of the transported fluid may require substantial mass flow through the junctions. In addition, there is evidence a) that the major electrolytes in the cytoplasm of the epithelial cells are not uniformly distributed but may have distinct axial and radial concentration gradients that depend on active solute transport (e.g., that abolished by ouabain); b) that in some epithelia (e.g., rabbit ileum) there is a peripheral cytoplasmic zone that may support fast convective flow for transcellular fluxes; c) that the extracellular structures like the glycocalyx and basement membrane preferentially sequester potassium (and calcium) and could have a non-zero reflection coefficient; and d) that in normal cells, nuclei have ionic composition similar to that of the circumnuclear cytoplasm.

Animals↗