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Biomedical subjects

A Ghosh

Publications and source records attributed to A Ghosh.

At least 253 records · Page 14Linked to original sources
PubMed1993

Biophysical characterization of Vibrio El Tor typing phage e5.

Vibrio cholerae typing phage e5, which can lyse only the El Tor strains of V. cholerae, was characterized. The phage had a polyhedral head 51 nm in diameter and a short tail 13 nm in length. It contained 13 structural polypeptides, with the molecular mass of the major component being 50 kDa. Phage chromosome comprised a 38.5-kb linear double-stranded DNA molecule with unique termini, as determined by restriction fragment analysis and electron microscopy, and had a G+C content of 35.5%. A physical map was constructed with the restriction endonucleases HaeII and HpaII. Adsorption of the phage to its host followed a biphasic kinetics and its intracellular growth was characterized by a latent period of 15 min and a burst size of 100 particles per infected cell. The phage was found to be moderately thermotolerant.

Bacteriophages↗
PubMed1993

Screening techniques for the detection of inborn errors of bile acid metabolism by direct injection and micro-high performance liquid chromatography-continuous flow/fast atom bombardment mass spectrometry.

Two methods, direct injection-continuous flow fast atom bombardment (DI-CF/FAB) mass spectrometry and micro-high-performance liquid chromatography (mu HPLC)-CF/FAB) mass spectrometry were developed for the clinical analysis of urinary bile acids and their conjugates, specifically for the diagnosis of disorders of bile acid metabolism. The method based upon DI of urine extracts into the CF/FAB flow stream was developed for the rapid screening of large numbers of patient samples. It allows injections to be made at 4 min intervals for high sample throughput. Analyses of standard mixtures of bile salts demonstrate that linear response curves are obtained over more than a hundred-fold concentration range with a minimum detectable amount in the picogram range. Oxo bile salts are identified by reduction with sodium borodeuteride followed by reanalysis for detection of any reduction products. This methodology has been used for the analysis of over 1000 specimens. A reverse-phase mu HPLC-CF/FAB mass spectrometric method was also developed for use in the confirmation or further investigation of screening results. With no additional sample preparation this method permits the separation, identification and quantitation of urinary bile salt isomers within a 45 min analysis time.

Bile Acids and Salts↗
PubMed1993

Expression of human papillomavirus type 16 E7 protein by recombinant baculovirus and use for the detection of E7 antibodies in sera from cervical carcinoma patients.

Although the presence of serum antibodies against the human papillomavirus type 16 (HPV-16) E7 protein has been linked with cervical cancer, currently available assays detect antibodies in only ca. 40% of carcinoma patients. The dependence of these serological assays on synthetic target antigens which present only linear epitopes may be a limiting factor. In order to produce a more realistic target antigen for use in serological assays, we have expressed the HPV-16 E7 protein in insect cells using a recombinant baculovirus vector. Two major E7 forms of ca. 18kDa and 16kDa were produced and characterised. The 16kDa component was shown to be truncated at the N-terminus. A radioimmunoprecipitation assay was developed for the detection of anti-E7 antibodies in human sera. This assay showed a marked increase in detection rate compared with a western blotting method based on bacterially derived E7 fusion proteins.

Amino Acid Sequence↗
PubMed1993

Recombinant human interleukin-4 (rhu IL-4) administered by the intravenous and subcutaneous routes in patients with advanced cancer--a phase I toxicity study and pharmacokinetic analysis.

19 patients with advanced cancer were entered into a phase I study of recombinant human interleukin-4 (rhu IL-4). The predominant clinical side-effects included flu-like symptoms, gastrointestinal upset, lethargy and transient hypotension. In addition, there were several cases of capillary leak syndrome. 2 cases of gastrointestinal haemorrhage occurred; this was life threatening in 1 patient. The maximum tolerated dose (MTD) was 400 micrograms/m2/day. Biochemical toxicity was limited to asymptomatic elevation of liver enzymes suggesting IL-4 induced liver damage. Pharmacokinetic analysis following the intravenous bolus injection has shown that IL-4 is rapidly cleared (mean T1/2 = 19 +/- 8.7 min) from a small compartment (mean Vd = 4.9 +/- 3.68 l) probably indicating that IL-4 is retained in the systemic circulation or at most the extracellular fluid volume. 2 patients with non-Hodgkin lymphomas (NHL) showed a transient response to IL-4 whilst a third patient with NHL showed transient disease progression.

Adult↗
PubMed1993

Enzymatic amplification of mini-exon-derived RNA gene spacers of Leishmania donovani: primers and probes for DNA diagnosis.

The multicopy mini-exon-derived RNA (med RNA) locus of Leishmania donovani was enzymatically amplified by the polymerase chain reaction (PCR). The major 180 bp PCR product contained conserved med RNA gene sequences flanking the variable intergenic spacer from the med RNA gene tandem repeat. The oligonucleotide primers cross-reacted with other Leishmania species. In serial dilution experiments, positivity in the PCR assay was observed down to the genomic DNA equivalent of less than a single Leishmania cell. When the major PCR products from Indian L. donovani isolates were cloned and used as probes in dot hybridization analyses, they discriminated between L. donovani and L. amazonensis, L. major and L. infantum under high stringency conditions. DNA from spleen biopsies and blood samples of confirmed kala azar patients was positive, as were two skin biopsies from patients with post-kala azar dermal leishmaniasis (PKDL). These observations demonstrate that PCR amplification of med RNA intergenic spacers is sufficiently sensitive for clinical diagnosis of kala azar and PKDL, and furthermore, that cloned intergenic spacer probes may be useful for identification and classification of L. donovani.

Animals↗
PubMed1993

Outcome and management of babies with prenatal ultrasonographic renal abnormalities.

Between January 1987 and December 1990, 60 fetuses were found to have renal abnormalities on antenatal ultrasonography. Six fetuses were aborted because of major renal abnormalities with or without associated chromosomal aberrations. Twelve babies with major renal abnormalities died in the immediate neonatal period. Forty-two babies were studied after birth and followed up. Babies who were found to have mild dilation of the renal pelvis of 6 to 10 mm during fetal life revealed either normal renal findings in the postnatal period or complete resolution of the abnormalities within the first year. Significant pelvic dilation of more than 10 mm occurred in 32 babies. A significant proportion (34%) had transitional hydronephrosis that resolved spontaneously during the follow-up period (mean, 2 1/2 years; range, 1 1/2 to 4 1/2 years). Extrarenal pelvis, another benign condition, accounted for 15.6%. Most babies with pelviureteral junction obstruction (15%) and vesicoureteral junction obstruction (6.2%) required early neonatal surgery. The technetium-99m diethylenetriamine renal scan with the diuretic renogram half-time was found to be a very useful tool to distinguish between obstructive and nonobstructive hydronephrosis. With early diagnosis and intervention, the prognosis for many of these renal abnormalities is much more favorable and such information is invaluable for antenatal counseling.

Female↗
PubMed1993

Primary liver carcinoma complicating pregnancy.

Primary hepatic carcinoma complicating pregnancy has been sporadically reported in the literature. Its association with grossly raised serum alphafetoprotein values is of particular interest to obstetricians who perform routine maternal alphafetoprotein screening in the second trimester. A case with favourable maternal and fetal outcome is presented.

Adult↗
PubMed1993

A role for subplate neurons in the patterning of connections from thalamus to neocortex.

During cerebral cortical development, ingrowing axons from different thalamic nuclei select and invade their cortical targets. The selection of an appropriate target is first evident even before thalamic axons grow into the cortical plate: initially axons accumulate and wait below their cortical target area in a zone called the subplate. This zone also contains the first postmitotic neurons of the cerebral cortex, the subplate neurons. Here we have investigated whether subplate neurons are involved in the process of target selection by thalamic axons by ablating them from specific cortical regions at the onset of the waiting period and examining the subsequent thalamocortical axon projection patterns. Subplate neurons were ablated at the onset of the waiting period by intracortical injections of kainic acid. The effect of the ablation on the thalamocortical projection from visual thalamus was examined by DiI-labeling of the LGN days to weeks following the lesion. At two to four weeks post-lesion, times when LGN axons would have normally invaded the cortical plate, the axons remained below the cortical plate and grew past their appropriate cortical target in an anomalous pathway. Moreover, examination of LGN axons at one week post-lesion, a time when they would normally be waiting and branching within the visual subplate, indicated that the axons had already grown past their correct destination. These observations suggest that visual subplate neurons are involved in the process by which LGN axons select and subsequently grow into visual cortex. In contrast, subplate neurons do not appear to play a major role in the initial morphological development of the LGN itself. Subplate ablations did not alter dendritic growth or shapes of LGN projection neurons during the period under study, nor did it prevent the segregation of retinal ganglion cell axons into eye-specific layers. However, the overall size of the LGN was reduced, suggesting that there may be increased cell death of LGN neurons in the absence of subplate neurons. To examine whether subplate neurons beneath other neocortical areas play a similar role in the formation of thalamocortical connections, subplate neurons were deleted beneath auditory cortex at the onset of the waiting period for auditory thalamic axons. Subsequent DiI labeling revealed that in these animals the majority of MGN axons had grown past auditory cortex instead of innervating it. Taken together these observations underscore a general requirement for subplate neurons throughout neocortex in the process of cortical target selection and ingrowth by thalamic axons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
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↗