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A Ghosh

Publications and source records attributed to A Ghosh.

At least 19 recordsLinked to original sources
PubMed1992

Involvement of subplate neurons in the formation of ocular dominance columns.

During development of the mammalian visual system, axon terminals of lateral geniculate nucleus (LGN) neurons, initially intermixed within layer 4 of the visual cortex, gradually segregate according to eye preference to form ocular dominance columns. In addition to LGN axons and layer 4 neurons, subplate neurons may also participate in interactions leading to column formation. Deletion of subplate neurons before the formation of ocular dominance columns prevents the segregation of LGN axons within layer 4. Thus, interactions between LGN axons and layer 4 neurons are not sufficient; subplate neurons are also required for formation of ocular dominance columns in the visual cortex.

Animals↗
PubMed1992

Occurrence of wax esters and 1-O-alkyl-2,3-diacylglycerols in goat epididymal sperm plasma membrane.

Two unusual lipid classes were detected by thin-layer chromatography in the neutral lipids derived from goat cauda-epididymal sperm plasma membrane. The lipids were identified as wax esters and 1-O-alkyl-2,3-diacylglycerols based on chromatographic properties, identity of their hydrolysis products, and infrared/1H nuclear magnetic resonance spectral evidence. The membrane contained ca. 3 and 5 micrograms/mg protein of wax esters and alkyldiacylglycerols, respectively. The relative proportions of wax esters and alkyldiacylglycerols in the total neutral lipids were 1.5% and 2.4%, respectively. The lipids contained fatty acids with chain lengths of C14 to C22. The major fatty acids of the wax esters were 14:0, 16:0, 16:1 omega 7, 18:0 and 18:1 omega 9. The fatty acids in alkyldiacylglycerol were 16:0, 18:0, 22:5 omega 3 and 22:6 omega 3. Alkyldiacylglycerol was particularly rich in docosahexaenoic acid (22:6 omega 3) representing 30% of the total fatty acids. The alcohols of wax ester were all saturated with C20-C29 carbon chains. The deacylated products derived from alkyldiacylglycerols were identified as hexadecyl, octadecyl and octadec-9'-enyl glycerol ethers.

Animals↗
PubMed1992

Relative protection given by extract of Phyllanthus emblica fruit and an equivalent amount of vitamin C against a known clastogen--caesium chloride.

Aqueous extracts of Phyllanthus emblica L. fruit and an equivalent amount of vitamin C were administered orally by gavage to laboratory-bred Swiss albino mice for 7 days in order to evaluate the protection afforded by the two extracts against clastogenic effects of different doses of caesium chloride (CsCl) on bone marrow cells of Mus musculus in vivo. Both pretreatments significantly reduced the frequency of chromosome aberrations induced by CsCl given at three different doses, indicating that vitamin C, an essential component of P. emblica extract, was the effective agent in protecting against the clastogenicity of the metal salt.

Animals↗
PubMed1992

Rapid and sensitive detection of Leishmania kinetoplast DNA from spleen and blood samples of kala-azar patients.

Following sequence analysis of a Leishmania donovani kinetoplast DNA (kDNA) minicircle, we have developed synthetic oligonucleotides for use in the polymerase chain reaction (PCR). With these primers, we have amplified L. donovani kDNA from splenic aspirates and blood samples taken from kala-azar patients. Treatment of the samples for PCR requires only limited DNA purification by lysis in SDS, digestion with proteinase K, phenol extraction and ethanol precipitation of the resulting nucleic acid. We have obtained amplified product routinely with DNA prepared from the equivalent of 2.5-25 microliters of splenic aspirate or of 50-500 microliters of blood from infected patients. In dilution experiments a visible product has been obtained on amplification of DNA from the equivalent of 2.5 x 10(-7) microliters of splenic material. We therefore propose the amplification of L. donovani kDNA by PCR as a rapid and highly sensitive method for the diagnosis of kala-azar.

Animals↗
PubMed1992

Recombinant human interleukin 4 (IL-4) given as daily subcutaneous injections--a phase I dose toxicity trial.

Recombinant Interleukin 4 was administered by subcutaneous injection at daily doses of 0.5, 1.0 or 5.0 micrograms kg-1 to nine patients as part of a Phase I Dose Toxicity Study. Dose limiting toxicity was reached at 5 micrograms kg-1 day-1. Symptoms of toxicity included fatigue, 'flu like symptoms and elevated liver enzymes. Modest but significant elevations of neutrophil and platelet counts occurred. No clear evidence of antitumour effects emerged although pain in metastatic lymph nodes and a small fall in myeloma paraprotein levels during dosing were observed. In vitro and murine in vivo studies indicate that patients with lymphoproliferative disease should be selected for Phase II trials.

Bone Marrow↗
PubMed1992

Prognostic significance of p53 overexpression in gastric and colorectal carcinoma.

p53 expression was examined in 55 gastric and 107 colorectal carcinomas with an immunoperoxidase technique, using the polyclonal antibody CM1 on routinely fixed, paraffin embedded tissue. p53 protein was detected in 47% gastric and in 46% colorectal carcinomas and found to correlate with stage of disease and unfavourable clinical outcome (P less than 0.001). Thus, the proportion of positively reacting neoplasms increased as the stage progressed, tumours which had invaded regional lymph-nodes overexpressed p53 more frequently than localised carcinomas and an elevated level of p53 was associated with early relapse and death. In colorectal carcinoma p53 positivity was also linked with site and macroscopic configuration of the primary tumour and was most frequently expressed in carcinomas from the rectum and in ulcerative tumours. p53 overexpression was irrespective of tumour grade. Uniform negative reactivity with anti-p53 antibody was seen in normal epithelium adjacent to carcinoma, intestinal metaplasia, atrophic gastritis and in colonic adenomas. There was a good correlation between immunohistochemical staining on paraffin and frozen sections. These studies suggest that in gastric and colorectal carcinoma, immunohistochemical detection of p53 protein in routinely fixed tissue can be used along with other established parameters to assess prognostic outcome, especially to identify patients with poor short-term prognosis.

Adult↗
PubMed1992

Expression of human papillomavirus type 16 E6 protein by recombinant baculovirus and use for detection of anti-E6 antibodies in human sera.

Existing assays to detect antibodies to human papillomavirus type 16 (HPV-16) proteins in sera from cervical carcinoma patients rely primarily on bacterially produced recombinant proteins or synthetic peptides for use as target antigens. These methods have had limited success in the detection of antibodies against the E6 protein. To produce more authentic E6 protein for use in serological assays, we have employed a recombinant baculovirus vector to synthesize the protein in insect cells. Cells infected with the vector containing E6 gene sequences expressed a stable protein doublet comprising 18.5K and 19.1K bands. This protein reacted in Western blots with an antiserum raised against a purified E6 fusion protein produced in Escherichia coli. This antiserum, and several others raised against E. coli-derived E6 fusion proteins, were unable to recognize the baculovirus E6 protein in radioimmunoprecipitation assays (RIPAs). However, serum from a cervical carcinoma patient readily immunoprecipitated the baculovirus E6 protein, suggesting that the baculovirus-derived protein represented a realistic antigenic target. A RIPA was developed for the detection of anti-E6 protein antibodies in human sera. The assay was tested on a selected group of sera from carcinoma patients and controls, in comparison with a Western blotting method using bacterial fusion proteins. The baculovirus E6 protein-based RIPA showed a marked increase in detection rate over the Western blotting method. These findings suggest that serum antibodies to HPV-16 E6 protein may be more prevalent than has previously been shown.

Antibodies, Viral↗
PubMed1992

Starch digestion and adsorption by beta-amylase of Emericella nidulans (Aspergillus nidulans).

A mutant strain of Emericella nidulans MNU 82 was isolated by multistep mutation. The beta-amylase produced by the mutant was able to digest raw starch. It was readily and strongly adsorbed onto raw starch at pH 5.0. The enzyme to starch ratio was 1950 U/g starch. The enzyme showed no correlation between the capacity of raw starch digestion and adsorption of the enzyme.

Adsorption↗
PubMed1992

Intra-operative blood loss during elective lower segment caesarean section.

OBJECTIVE: To measure intra-operative blood loss at elective lower segment caesarean section and to compare estimated with measured blood loss. DESIGN: Prospective observational study. Blood loss was measured in patients who underwent lower segment caesarean section in the course of routine hospital activity. SETTING: Tsan Yuk Hospital (Hong Kong), which is affiliated to the University of Hong Kong, 1990-1991. SUBJECTS: Forty women (mean age 29 years) with singleton pregnancies (mean gestation 38 weeks) delivered by elective lower segment caesarean section under general anaesthesia (mean birthweight 3177 g). MAIN OUTCOME MEASURE: Intra-operative blood loss measured by the alkaline haematin method (intra-assay co-efficient of variation 2.2%). RESULTS: The mean measured blood loss was 487 ml (SE 40, range 164-1438). The mean estimated blood loss was 425 ml (SE 31) range 100-1300; mode 400). Observer error in estimating blood loss was higher if measured blood loss greater than 600 ml. One patient received a blood transfusion and another had a post-operative haemoglobin level less than 10.0 g/dl. CONCLUSION: Blood loss at elective lower segment caesarean section was usually less than 500 ml and was estimated with reasonable accuracy. However, there was a tendency to under-estimate blood loss when the measured loss exceeded 600 ml.

Adult↗
PubMed1992

Sports medicine.

Explore the source record for details and available documents.

Humans↗
PubMed1992

Pathfinding and target selection by developing geniculocortical axons.

During development of the mammalian cerebral cortex, thalamic axons must grow into the telencephalon and select appropriate cortical targets. In order to begin to understand the cellular interactions that are important in cortical target selection by thalamic axons, we have examined the morphology of axons from the lateral geniculate nucleus (LGN) as they navigate their way to the primary visual cortex. The morphology of geniculocortical axons was revealed by placing the lipophilic tracer Dil into the LGN of paraformaldehyde-fixed brains from fetal and neonatal cats between embryonic day 26 (E26; gestation is 65 d) and postnatal day 7 (P7). This morphological approach has led to three major observations. (1) As LGN axons grow within the intermediate zone of the telencephalon toward future visual cortex (E30-40), many give off distinct interstitial axon collaterals that penetrate the subplate of nonvisual cortical areas. These collaterals are transient and are not seen postnatally. (2) There is a prolonged period during which LGN axons are restricted to the visual subplate prior to their ingrowth into the cortical plate; the first LGN axons arrive within visual subplate by E36 but are not detected in layer 6 of visual cortex until about E50. (3) Within the visual subplate, LGN axons extend widespread terminal branches. This represents a marked change in their morphology from the simple growth cones present earlier as LGN axons navigate en route to visual cortex. The presence of interstitial collaterals suggests that there may be ongoing interactions between LGN axons and subplate neurons along the entire intracortical route traversed by the axons. From the extensive branching of LGN axons within the visual subplate during the waiting period, it appears that they are not simply "waiting." Rather, LGN axons may participate in dynamic cellular interactions within the subplate long before they contact their ultimate target neurons in layer 4. These observations confirm the existence of a prolonged waiting period in the development of thalamocortical connections and provide important morphological evidence in support of the previous suggestion that interactions between thalamic axons and subplate neurons are necessary for cortical target selection.

Aging↗
PubMed1991

Purification and properties of DNA gyrase from Vibrio cholerae.

The DNA gyrase was purified from Vibrio cholerae strain 569B. It appeared to be composed of two subunits of Mr 120,000 and 97,000 and had a great deal of similarity to the Escherichia coli gyrase. Unlike the E. coli enzyme, however, it could neither relax supercoiled DNA nor induce a cleavage of double-stranded DNA, under experimental conditions in which E. coli gyrase could do so.

DNA↗
PubMed1991

The role of ATP and free ADP in metabolic coupling during fuel-stimulated insulin release from islet beta-cells in the isolated perfused rat pancreas.

The isolated perfused rat pancreas was used to test the hypothesis that total cellular ATP or the ratio of ATP/free ADP plays the primary role in coupling intermediary metabolism to the biophysical events that are the basis of glucose-stimulated insulin release. The pancreas was preperfused for 20 min with 4.0 mM of a physiological mixture of 20 amino acids plus 4.2 mM glucose, and insulin release was then stimulated for 150 s by suddenly increasing the glucose to 8.3 mM. The pancreas was sampled at 24, 48, 72, and 150 s after the switch. The content of total ATP, ADP, AMP, Pi, phosphocreatine, and creatine were measured in beta-cell enriched cores of pancreatic islets microdissected from freeze-dried pancreas cryostat sections. Metabolites were measured by quantitative histochemical enzymatic cycling techniques. Modeling studies were carried out to assess the impact of biochemical analytical results on the membrane potential of the beta-cells. The level of free ADP was calculated using the creatine kinase equilibrium reaction and an intracellular pH of 7.2. First phase insulin release was stimulated at least 10-fold with the maximum reached 45 s after adding high glucose. The biochemical analytical data demonstrate that the total cellular level of the putative coupling factor ATP and of the ratios ATP/free ADP and ATP/free ADP x Pi are not significantly influenced by a glucose level change that causes a more than 10-fold surge of insulin release. The strength and limitations of the present experimental strategy and the implications of the results for our understanding of metabolic coupling in glucose-stimulated insulin release are discussed.

Adenosine Diphosphate↗
PubMed1991

Neural influence on oxytocin-induced changes of adrenomedullary catecholamines in the pigeon.

Oxytocin (0.25 IU/100 g body wt) was injected intraperitoneally only once to unilaterally splanchnic denervated pigeons. The effects were investigated after 0.5, 4, 12, 24, 72, 144 and 216 h of administration. The findings revealed that oxytocin caused the release of more norepinephrine (NE) from the denervated glands up to 24 h after treatment. In contrast, oxytocin-induced release of epinephrine (E) showed no significant difference in between the innervated and the denervated glands after 0.5 h of treatment. Strikingly, oxytocin brought about release of more E from the denervated glands after 24 h of treatment. This indicates that the first phase of NE release and the second phase of E release are neurally regulated. The findings further revealed that the resynthesis of both NE and E was faster in the innervated glands after 216 h of oxytocin treatment. This clearly points out that the splanchnic nerve accelerates resynthesis of both NE and E induced by oxytocin.

Adrenal Medulla↗
PubMed1991

Lipid changes of goat sperm plasma membrane during epididymal maturation.

Highly purified plasma membranes of maturing goat caput-, corpus- and cauda-epididymal spermatozoa were isolated by aqueous two-phase polymer methods and their lipid constituents were analysed. Phospholipid (approx. 75% w/w), neutral lipid (approx. 15% w/w) and glycolipid (approx. 10% w/w) were the major sperm membrane lipids. There was a significant decrease in the total lipids (approx. 25% w/w), phospholipid (approx. 30% w/w) and glycolipid (approx. 80% w/w) contents of sperm membrane during epididymal maturation. On the contrary, the mature cauda-sperm membrane showed greater (approx. 50% w/w) neutral lipid content than that of the immature caput sperm. Phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin were the phospholipids of the sperm membrane, the former two being the major lipids. Both PC and PE fractions consisted of three species--diacyl, alkylacyl and alkenylacyl forms, the last one being the dominant species in both PC and PE. Of all the phospholipids, diacyl PE decreased most strikingly (approx. 65% w/w) during sperm maturation. The neutral lipid fraction contained sterols, wax esters, 1-O-alkyl-2,3-diacylglycerol, triacylglycerol and fatty acids. Sterols represented nearly 75% w/w of the neutral lipids and cholesterol was the major component (approx. 95% w/w) of the sterol fraction. The sperm maturity was associated with marked increase of sterol (approx. 60% w/w) and steryl ester (approx. 200% w/w) and decrease (approx. 50-65% w/w) of the other membrane-bound neutral lipids. The glycolipid was identified as monogalactosyldiacylglycerol. The fatty acid profile of the various membrane lipids underwent marked alteration during the epididymal transit of the male gametes. Cholesterol/phospholipid and saturated/unsaturated fatty acid ratios increased greatly in the maturing sperm membrane. The altered lipid profile of the mature sperm membrane leads to changes in its fluidity that play an important role in determining the structure and functions of the biomembrane.

Animals↗
PubMed1991

Cytogenetic damage induced in vivo to mice by single exposure to cesium chloride.

Female laboratory bred albino mice (2n = 40) were orally administered cesium chloride (CsCl) in aqueous solution as a single dose and the damage induced at the chromosomal level was observed in bone marrow cells after 6, 12, 18, and 24 hours of exposure. The concentrations of the chemical given were calculated as fractions of the LD50, namely 1/5, 1/10, and 1/20. The cytogenetic endpoints screened for were chromosomal aberrations (CA) and divisional frequency or mitotic index (MI). The frequency of chromosomal aberrations induced was directly proportional to the concentration of the chemical administered. The highest dose was the most toxic and was considered to be the maximum tolerance level. Effects on divisional frequency were variable, the highest concentration being significantly mitostatic, the middle one ineffective, and the lowest slightly mitogenic. In general, the observations indicate that CsCl is clastogenic when administered orally to mice in vivo and the effects are dose-dependent.

Analysis of Variance↗
PubMed1991

Recurrent congenital chylothorax.

Congenital chylothorax is an uncommon but well-described condition. Recurrent congenital chylothorax is extremely rare. Yancy and Spock (1967) reviewed 31 reported cases of spontaneous chylothorax which occurred in the first 2 months of life and noted that male infants were affected twice as commonly as females. Two other cases of recurrent congenital chylothorax in male offspring (Defoort and Thiery, 1978; Reece et al., 1987) led to the suggestion of possible X-linked recessive inheritance. We describe a case of recurrent congenital chylothorax in which two consecutive female infants in a sibship were affected. The underlying cause of this disorder remains unknown. Inheritance as an X-linked recessive is not possible and this case is suggestive of autosomal recessive inheritance. The case also serves to emphasize the need for caution in counselling for recurrence risks when the underlying aetiology of the disorder is unknown.

Adult↗