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Biomedical subjects

S Ghosh

Publications and source records attributed to S Ghosh.

At least 829 records · Page 46Linked to original sources
PubMed1990

Neurosecretory cells in Diptera.

The neurosecretory cells were studied in 20 dipteran species belonging to three suborders. The NSC are localized in (a) the frontal ganglion (in 10 of the 20 species studied), (b) the pars intercerebralis region of the protocerebrum (in the median and lateral groups), (c) the tritocerebral region of the brain (in 8 of the 20 species studied) and (d) the suboesophageal ganglion. In one species, NSC were also seen in the prothoracic ganglion. The NSC were classified as types A, B and C/D. The NSC of the median group of the pars intercerebralis were unusually large compared with the size of the brain. The number, size and distribution of the cells are discussed.

Animals↗
PubMed1990

Clinicobacteriological study of empyema thoracis in infants and children.

Forty-one cases of empyema thoracis admitted in hospital during April, 1985 to August, 1987 were studied. Majority were males (65.9%) and were of less than 2 years of age (70.7%). Right side (60.9%) was predominantly involved. Abdominal distension (43.9%) was very characteristic, with other usual features like fever, cough and respiratory distress. A large majority of them were victims of malnutrition (73.2%) and anaemia (53.7%) with haemoglobin level ranging from 5-9 g/dl. Mortality was high (17.1%). Therapy with parenteral cloxacillin and gentamicin and continuous intercostal tube drainage accounted for loss of 15.8 bed days (average period of hospitalisation). Staph aureus was the principal aetiopathogen (68.3%). No anaerobe could be isolated. Strains of staphylococci were mostly resistant to penicillin and ampicillin but sensitive to gentamicin, cloxacillin and erythromycin.

Child, Preschool↗
PubMed1990

Immunologic and survival studies in mice immunised with cryodestroyed ascites fibrosarcoma (AFS) cells.

Adult mice weighing 20 g, divided into 5 groups, were immunised with single and three cycle cryodestroyed ascites fibrosarcoma cells using different modes of immunisation with respect to dose and administration frequency. Survival against subsequent challenge with the same tumour cells and immune response given by leucocyte migration inhibition, were studied in these animals. It appears from the present study that animals with relatively low antigenic load have a significantly (P less than 0.001) high mean survival time and/or survival index compared with controls than those with relatively high antigenic load. Survival in animals immunised with three cycle cryodestroyed tumour cells is significantly (P less than 0.001) higher than that with single cycle even in face of a greater challenging tumour dose with mode of immunisation remaining the same. Preliminary observations on percentage leucocyte migration inhibition showed that there exists no difference in percentage inhibition with either viable or cryodestroyed tumour cell antigens added to migration chamber excepting in animals immunized with three cycle cryodestroyed tumour cells where percentage inhibition was significantly (P less than 0.001) greater with viable than with cryodestroyed tumour cell antigen without altering the percentage inhibition between the two groups. Factors maximising immune response and their modulating effects are discussed.

Animals↗
PubMed1990

Cronkhite-Canada syndrome with hypothyroidism.

An elderly man with non-familial gastrointestinal polyposis, malabsorption and progressive hypoproteinemia is reported. Associated alopecia, cutaneous hyperpigmentation and nail dystrophy with loss of nails were consistent with the diagnosis of Cronkhite-Canada syndrome. Hypothyroidism was present in this patient and the rare association of these two conditions is discussed.

Aged↗
PubMed1989

Further characterization of eukaryotic initiation factor 5 from rabbit reticulocytes. Immunochemical characterization and phosphorylation by casein kinase II.

Eukaryotic initiation factor (eIF)-5, isolated from rabbit reticulocyte lysates, is a monomeric protein of Mr = 58,000-62,000. Immunochemical methods were employed to identify eIF-5 in crude cell lysates. Antisera against purified denatured eIF-5 were prepared in rabbits and characterized by immunoblotting and immunoprecipitation techniques using native and denatured eIF-5 as antigens. Monospecific antibodies to denatured eIF-5 were affinity-purified using eIF-5 blotted onto aminophenylthioether paper. Rabbit reticulocytes, HeLa cells and mouse L cells were lysed directly into a denaturing buffer containing 3% sodium dodecyl sulfate. The denatured proteins were analyzed by polyacrylamide gel electrophoresis followed by immunoblotting with anti-eIF-5 antibodies. With each lysate, one major immunoreactive polypeptide was observed whose molecular weight corresponded to that of purified eIF-5 (Mr = 58,000-62,000). No degradation products or precursor forms of molecular weight higher than 62,000 were detected in any lysate. These results indicate that isolated eIF-5 is the same size as that found in crude lysates. Additional characterization of eIF-5 indicates that purified eIF-5 can be phosphorylated at serine residues in vitro by casein kinase II. Furthermore, in vitro phosphorylated eIF-5 retains full biological activity in catalyzing the joining of 60 S ribosomal subunits to a preformed 40 S ribosomal initiation complex to form an 80 S initiation complex. Based on its specific activity, we demonstrate that 1 pmol of rabbit reticulocyte eIF-5 mediates the formation of approximately 180 pmol of 80 S initiation complex under the conditions of in vitro initiation reactions.

Animals↗
PubMed1989

Perturbation of tryptophan residues by point mutations in bacteriophage T4 lysozyme studied by optical detection of triplet-state magnetic resonance spectroscopy.

We have investigated perturbations of the triplet-state properties of Trp residues in bacteriophage T4 lysozyme caused by point mutations using low-temperature phosphorescence and optical detection of triplet-state magnetic resonance (ODMR) spectroscopy. Five temperature-sensitive mutants have been studied in detail. These include lysozymes with the point mutations Gln-105----Ala, Gln-105----Gly, Gln-105----Glu, Ala-146----Thr, and Trp-126----Gln. Changes in phosphorescence 0,0 band wavelength, intensity, the triplet-state zero-field splitting (ZFS), and the wavelength dependence of the ZFS were detected only from Trp-138 in each mutant. In the case of the Q105A mutation, the perturbations on Trp-138 have been ascribed to the combination of an increase in the polarizability of the environment and to the loss of hydrogen bonding of the enamine nitrogen of indole. For the Q105G mutation, we believe that Q is replaced by a solvent molecule in H bonding, leading to relatively small changes. In the Q105E mutation, the perturbation results largely from the introduction of a charged residue. In the case of the mutation A146T, the perturbation is associated with a local conformational change in which Trp-138 is shifted to a more solvent-exposed location. On the other hand, no significant spectroscopic changes in Trp-126 and Trp-158 were found in any of the mutants, suggesting that the perturbations are probably localized near Trp-138 for the mutations of positions 105 and 146. However, in the mutation W126Q, which occurs approximately 16 A away from Trp-138, significant changes of Trp-138 are detected, suggesting that the effects of this mutation are propagated over large distances.

Luminescent Measurements↗
PubMed1989

The LSP1-alpha gene of Drosophila melanogaster exhibits dosage compensation when it is relocated to a different site on the X chromosome.

The LSP1-alpha gene of Drosophila melanogaster is located on the X chromosome at 11B yet is not dosage compensated. In order to determine if this gene is inherently incapable of dosage compensation or if it does not compensate because the appropriate regulatory cis-acting sequences are absent from its chromosomal domain, we have undertaken to relocate it to ectopic sites on the X chromosome. To differentiate between the transcripts produced by the transduced gene and those produced by the indigenous gene, we inserted a 500-bp sequence of mouse DNA into the LSP1-alpha clone prior to using it for transformation. Our results show that the LSP1-alpha gene exhibits equivalent levels of transcripts in the two sexes when it is relocated to either an autosomal site or to an ectopic site on the X chromosome. We conclude that the LSP1-alpha gene is capable of dosage compensation.

Animals↗
PubMed1989

Expression of Na,K-ATPase alpha subunit isoforms in the human ciliary body and cultured ciliary epithelial cells.

We have analyzed the expression of Na,K-ATPase alpha subunit isoforms in the transporting ciliary processes of the human eye and in cultured cells derived from non-pigmented (NPE) and pigmented (PE) ciliary epithelium. Northern hybridization analysis shows that the mRNAs encoding all the three distinct forms of Na,K-ATPase alpha subunit [alpha 1, alpha 2, and alpha 3] are expressed in the human ciliary processes in vivo. Immunohistochemical analysis using antibodies specific for each of the three alpha subunit isoforms confirms that these polypeptides are present in the microsomal fraction from the human ciliary processes. The monoclonal antibody McB2, which is specific to the Na,K-ATPase alpha 2 subunit isoform, has been found to decorate specifically the basolateral membrane domains of NPE cells but not of the PE cells, suggesting its expression in vivo only in the ocular NPE ciliary epithelium. However, cultured cells derived from the NPE and PE layers exhibit a different pattern of expression of mRNA and protein for the Na,K-ATPase alpha subunit isoforms when compared to the tissue. Both the NPE and PE cells express alpha 1 and alpha 3 mRNA and polypeptide, whereas alpha 2 mRNA and polypeptide are undetectable in these cells. The established cell lines derived from the NPE layer express comparable levels of the alpha 1 and alpha 3 isoforms of Na,K-ATPase as detected in the primary culture. However, the established NPE cell lines are also distinguishable from the normal PE cells when analyzed by Western blot analysis with A x 2 antibodies. The results presented here clearly show that the NPE and PE cells in the ciliary body have a distinct expression of Na,K-ATPase alpha subunit isoforms as compared to cultured cells.

Blotting, Western↗
PubMed1989

Multiple inputs to a population of thalamocortical neurons projecting to cat somatosensory cortex.

Ninety thalamocortical (TC) neurons were recorded extracellularly in ventrobasal thalamus of halothane-anesthetized cats. Projections of all of these neurons to specific subdivisions of somatosensory cortex were identified by their antidromic invasion following intracortical microstimulation restricted to these subdivisions. Collision-extinction tests were used to document excitatory inputs to TC neurons from afferent fibers of forelimb nerves stimulated electrically. Thirty-nine TC neurons (43% of sample) were excited from at least one forelimb nerve. Fifteen TC neurons were activated from two or more forelimb nerves. Combinations of effective nerves included ones innervating topographically different regions of forelimb. Neurons projecting to area 1-2 were least likely to be activated from more than one nerve. Seven TC neurons activated by electrical stimulation of nerve trunks were tested also with two distinct forms of mechanical somatic stimuli, i.e., hair bending and vibration, and with intradermal electrical stimuli. These tests revealed convergent inputs from hairy and glabrous skin. We conclude that there is a population of neurons, located in ventrobasal thalamus, which is capable of conveying multiple inputs to each of the subdivisions of primary somatosensory cortex. These neurons could be involved in forming properties of feature-extracting neurons of somatosensory cortex.

Action Potentials↗
PubMed1989

Activation of rat liver cholesterol ester hydrolase by cAMP-dependent protein kinase and protein kinase C.

Short term regulation of hepatic cholesterol ester hydrolase by reversible phosphorylation is described. Two different kinase systems seem to be involved in this regulation. The addition of ATP, cyclic AMP and Mg2+ to rat liver 104,000 X g supernatant (S104) produced a 100-140% increase in cholesterol ester hydrolase activity. This stimulation was abolished when protein kinase inhibitor was added prior to the addition of ATP, cyclic AMP and Mg2+. Cholesterol ester hydrolase activity was also stimulated when calcium ions, phosphatidylserine, and diolein were added to S104 along with ATP and Mg2+. Diolein in this reaction could be substituted by phorbol 12-myristate 13-acetate. Preincubation of S104 with alkaline phosphatase resulted in a deactivation of cholesterol ester hydrolase. The addition of increasing concentrations of Mg2+ to S104 produced increasing inhibition of cholesterol ester hydrolase activity, and this effect was blocked by NaF. It is suggested that rat liver cholesterol ester hydrolase is activated by cyclic AMP dependent protein kinase and protein kinase C. Deactivation is accomplished by dephosphorylation catalyzed by a phosphoprotein phosphatase, dependent on Mg2+.

Adenosine Triphosphate↗