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Biomedical subjects

S Ghosh

Publications and source records attributed to S Ghosh.

At least 37 records · Page 2Linked to original sources
PubMed1992

Failure of kinetochore development and mitotic spindle formation in okadaic acid-induced premature mitosis in HeLa cells.

The mitotic events associated with okadaic acid (OA)-induced premature chromosome condensation (PCC) in S-phase-blocked HeLa cells were studied at the light microscope, immunofluorescence, and electron microscope level. The development of PCC in these cells has been compared with that in multinucleate cells and also in uninucleate hamster cells induced by caffeine. In OA-induced PCC, the nuclear envelope breaks down and chromosomes condense, but the mitotic spindle and trilaminar kinetochores fail to develop. In S-phase PCC in multinucleate cells, only the mitotic spindle does not develop, whereas in caffeine-induced PCC, all these events are found to be associated. The possible difference in their pathways of induction and, in this connection, the dissociability of the early mitotic events have been discussed.

Caffeine↗
PubMed1992

Isolation of a cDNA encoding a glutathione S-transferase (GST) class-pi from the bovine ocular ciliary epithelium.

We have used a polyclonal antiserum to bovine ciliary epithelium, a secretory tissue involved in the formation of aqueous humor, to immunoscreen a directional lambda gt11 Sfi-Not cDNA expression library prepared from bovine ciliary epithelium poly(A)+ RNA. After immunoscreening 6 x 10(5) independent clones, 41 cDNA clones positive for ciliary epithelium were isolated and characterized. About one-third of the positive cDNA clones were found to be identical and to encode a glutathione S-transferase (GST) class-pi. The largest bovine GST cDNA clone isolated, pCN11, contains an open reading frame of 630 bases, encoding a protein of 210 amino acids with a calculated molecular weight of 23,335 Da. The corresponding amino acid sequence showed an overall identity of 85.6% with the human, and 85.2% with the rat and mouse GST class-pi. Northern analysis of bovine ocular tissues revealed that the GST class-pi gene encodes a 0.8-kilobase mRNA which is expressed most abundantly in cornea, ciliary epithelium and retina, and in lower levels in iris and lens. Cell lines derived from non-pigmented or pigmented bovine ciliary epithelium also showed high levels of GST-pi mRNA expression. These results provide additional evidence for differential gene expression of GST class-pi mRNA in various areas of the bovine eye.

Animals↗
PubMed1992

HSV-1-inducible proteins bind to NF-kappa B-like sites in the HSV-1 genome.

Several putative NF-kappa B-binding sites in the ICP0 and Vmw65 herpes simplex virus type-1 (HSV-1) genes have been identified. Oligonucleotides encoding some of these sites bind specifically to purified NF-kappa B protein and an NF-kappa B-like protein in nuclear extracts of phorbol ester- or cycloheximide-induced human embryonic lung (HEL) cells. HSV-1 infection of HEL cells induced a nuclear factor that binds specifically to kappa B sites in the ICP0 and Vmw65 gene regions and comigrates with complexes formed by purified NF-kappa B. The HSV-1-inducible nuclear factor bound to the authentic immunoglobulin (Ig) kappa B site. Transient expression of chloramphenicol acetyltransferase (CAT) plasmids containing two copies of the Ig kappa B site upstream of the c-fos promoter (kappa B2-CAT) showed activity in HEL cells. HSV-1 infection of kappa B2-CAT-transfected HEL cells, however, induced a dramatic increase in CAT activity; mutation in the NF-kappa B-binding site of kappa B2-CAT abolished the inducibility of CAT gene expression. Our results demonstrate that the HSV-1 ICP0 and Vmw65 gene regions contain binding sites for NF-kappa B, and that HSV-1-inducible proteins bind to NF-kappa B-like sites in the HSV-1 genome.

Base Sequence↗
PubMed1992

Microsatellites for linkage analysis of genetic traits.

Microsatellites are tandem repeats of simple sequence that occur abundantly and at random throughout most eukaryotic genomes. Since they are usually less than 100 bp long and are embedded in DNA with unique sequence, they can be amplified in vitro using the polymerase chain reaction. Microsatellites are easy to clone and characterize and display considerable polymorphism due to variation in the number of repeat units. This polymorphism is sufficiently stable to use in genetic analyses. Microsatellites are therefore ideal markers for constructing high-resolution genetic maps in order to identify susceptibility loci involved in common genetic diseases.

Animals↗
PubMed1992

Intrasellar tuberculoma.

Intrasellar tuberculoma mimicking a secreting adenoma is a rare occurrence. Although clinical and radiological features were suggestive of pituitary adenoma, histopathological examination following surgery showed a tuberculoma. There were no clinico-radiological features pathognomonic of an intrasellar tuberculoma.

Adult↗
PubMed1992

Quinalphos-induced suppression of spermatogenesis, plasma gonadotrophins, testicular testosterone production, and secretion in adult rats.

Quinalphos (O,O-diethyl-O-[quinoxalinyl-(2)-thionophosphate]) is a well-known organophosphorus insecticide used extensively in agriculture that adversely interferes with the activity of testicular steroidogenic enzymes in rats. To investigate its effects on spermatogenesis, the other function of testes, quantitative evaluation of different varieties of germ cells at stage VII of the seminiferous epithelium cycle, namely, type A spermatogonia (ASg), preleptotene spermatocytes (pLSc), midpachytene spermatcytes (mPSc), and step 7 spermatids (7Sd), along with the radioimmunoassay of plasma FSH, LH, testosterone, and testicular testosterone, were performed in Wistar rats following treatment with quinalphos (250 micrograms/kg, ip) for approximately one (13 days) and two cycles (26 days) of the seminiferous epithilium. Massive degeneration of all varieties of germ cells at stage VII, remarkable reduction in the sperm count, and significant reductions in plasma concentrations of FSH and testosterone, along with testicular testosterone, were observed after quinalphos treatment. Significant reduction in the plasma concentration of LH was observed only after treatment for two cycles. Administration of human chorionic gonadotrophin for 26 days in rats injected with quinalphos partially prevented the degeneration of germ cells and increased testosterone production. It is suggested that quinalphos may have a suppressive influence on gonadotrophin release but its direct detrimental action at the level of the testes may also be responsible for the observed changes in spermatogenesis and in testicular testosterone production in rats.

Animals↗
PubMed1992

Okadaic acid inhibits sister chromatid separation in mammalian cells.

Mitotic HeLa cells were treated with different concentrations of okadaic acid inhibiting phosphatase 2A activity alone or in addition to phosphatase 1 activity. Phosphatase 2A inhibition alone had no visible effect on mitosis, but inhibition of both phosphatase 1 and 2A produced mitotic abnormalities, including inhibition of anaphase mimicking the effect of colchicine. Recovery experiments in okadaic acid-free medium showed formation of diplochromosomes, indicating a failure of sister chromatid separation in the treated mitotic cells. The universality of the phosphatase 1 requirement in sister chromatid separation is discussed.

Chromatids↗
PubMed1992

Localization of chromatin in "persistent" nucleoli in okadaic acid treated HeLa cells.

In okadaic acid treated HeLa cells, the chromosomes sometimes condense without being accompanied by nuclear envelope breakdown. These cells show "persistent" nucleoli. Within these "persistent" nucleoli the intranucleolar chromatin condenses and can be observed in the region of the dense nucleolar component (DNC) of the nucleoli. Other nucleolar components, namely the fibrillar centre (FC) and the granular component (GC) remain unchanged. These observations strongly speak for the localization of nucleolar chromatin (ribosomal cistrons) within the dense nucleolar component of the interphase nucleolus.

Cell Nucleolus↗
PubMed1992

Chondrosarcoma of the maxilla.

A patient was referred to us with a mass in her upper jaw. This was diagnosed to be a chondrosarcoma of the maxilla. The mass was removed surgically. We present the case here and discuss the salient features.

Chondrosarcoma↗
PubMed1992

A single human monoclonal antibody that confers total protection from tetanus.

Protective human monoclonal antibodies (HuMAbs) are superior to hyperimmune sera and murine monoclonal antibodies as far as human immunotherapy is concerned. In this report, we describe the successful generation of triomas secreting HuMAbs to tetanus toxin (tt). Lymphoblastoid cell lines secreting anti-tt antibodies were stabilized by back-fusion with a mouse x human heterohybrid myeloma partner, SBC-H20. One of the antibodies so produced, confers total protection of mice from tetanus, unlike a few recent reports where only partial protection (delay in the onset of tetanus) was achieved with single HuMAbs. Experiments to localize the neutralizing epitope(s) of the toxin using the protective monoclonal antibodies revealed that the antibody recognizes a conformational determinant that is destroyed on SDS-treatment. Preliminary studies show that Fab preparations of the protective antibody are capable of neutralizing tetanus toxin, suggesting that it might be possible to clone and express the Fab in a stable vector for large scale production.

Animals↗
PubMed1992

Learning during general anaesthesia: implicit recall after methohexitone or propofol infusion.

Forty-four patients undergoing coronary artery surgery were allocated randomly to receive an infusion of propofol or methohexitone as a hypnotic supplement to a fentanyl-based anaesthetic technique. A taped message was played to the patients, consisting of 10 words associated with prompt sentences and a suggestion for a specific postoperative behavioural response. Twenty patients (10 propofol and 10 methohexitone) (perioperative group) were exposed to the taped message during surgery and in the immediate postoperative period and the other 24 patients (postoperative group) were exposed to the tape only in the postoperative period, after return to the intensive care unit (ICU). No patient had explicit recall of any events during the period when the tape was played. The patients in the propofol group who heard the tape during surgery had significant implicit recall of the word associations compared with the equivalent 10 methohexitone patients (P = 0.004), when tested 48 h after surgery. The patients who were played the tape whilst receiving identical infusion regimens for sedation in the ICU did not demonstrate implicit recall of the word associations in either the propofol or the methohexitone groups. There was no evidence of a response to the specific behavioural suggestion during the postoperative interview. The results confirm that auditory perception can occur during clinically adequate anaesthesia, and that suppression of auditory awareness or learning is a function of both the pharmacological degree of sedation and the degree of surgical stimulation.

Anesthesia, General↗
PubMed1992

Molecular cloning of the bovine CD9 antigen from ocular ciliary epithelial cells.

The ciliary epithelium is a bilayer of epithelial cells responsible for the formation and secretion of aqueous humor in the mammalian eye. We have isolated a cDNA clone from a lambda gt11 cDNA library of bovine ocular ciliary epithelial cells encoding the CD9 antigen, a member of a new family of transmembrane proteins. The bovine CD9 clone contains an open reading frame of 226 amino acids (M(r) 24,860). The deduced amino acid sequence from the bovine CD9 cDNA clone shows 83.5% identity with the human counterpart isolated from megakaryocytes, and a lower degree of identity with a group of related antigens (TAPA-1, C0-029, CD53, MRC OX-44, ME491, CD63, CD37, and Sm23) involved in growth regulation. Analysis of bovine ocular tissues reveals that the CD9 gene encodes a 1.4 kb mRNA which is detectable predominantly in cornea and at low levels in ciliary epithelium, retina, iris, and lens. Normal and transformed cell lines established from the ocular ciliary epithelium exhibited significant levels of CD9 transcripts. These results raise questions regarding possible roles of CD9 in the anterior segment of the eye.

Amino Acid Sequence↗
PubMed1992

Independent modes of transcriptional activation by the p50 and p65 subunits of NF-kappa B.

Recombinant subunits of the transcription factor NF-kappa B, p50 and p65, were analyzed both for binding to various kappa B motifs and in vitro activation. The subunits preferentially form a heterodimer that activates transcription. Although p50 and p65 bind DNA individually as homodimers and are structurally related, their activation mechanisms are distinct. p65 activates transcription by its unique carboxy-terminal activation domain. (p50)2 displays higher affinity DNA binding than (p65)2 for many distinct kappa B motifs and provides strong transcriptional activation only when adopting a chymotrypsin-resistant conformation induced by certain kappa B motifs but not others. Thus, (p50)2 acts as a positive regulator in vitro, consistent with its isolation as a putative constitutive regulator of MHC class I genes. Both subunits of NF-kappa B, therefore, contribute independently to provide regulation at given kappa B motifs.

Base Sequence↗
PubMed1992

Immunological characterization of neutral cholesteryl ester hydrolase from rat liver cytosol.

Rabbit polyclonal antibodies were raised against rat liver bile salt-independent neutral cholesteryl ester hydrolase (CEH) and used for subcellular localization and immunological comparison with isoforms from other tissues. Antibodies exhibited a high degree of specificity for the liver CEH through all stages of purification and neutralized 70-80% of the activity of liver cytosolic CEH. They exhibited various levels of cross-reactivity with cytosolic proteins from other tissues, but reacted weakly with pancreatic and intestinal proteins and did not inhibit pancreatic CEH. Cytosol contained 78% of total cellular CEH activity and 75% of CEH immunoreactive protein. Washed microsomes contained 3% of CEH activity and 5% of CEH protein.

Animals↗
PubMed1992

Parallel processing of tactile information in the cerebral cortex of the cat: effect of reversible inactivation of SI on responsiveness of SII neurons.

1. Localized cortical cooling was employed in anesthetized cats for the rapid reversible inactivation of the distal forelimb region within the primary somatosensory cortex (SI). The aim was to examine the responsiveness of individual neurons in the second somatosensory area (SII) in association with SI inactivation to evaluate the relative importance for tactile processing of the direct thalamocortical projection to SII and the indirect projection from the thalamus to SII via an intracortical path through SI. 2. Response features were examined quantitatively before, during, and after SI inactivation for 29 SII neurons, the tactile receptive fields of which were on the glabrous or hairy skin of the distal forelimb. Controlled mechanical stimuli that consisted of l-s trains of either sinusoidal vibration or rectangular pulses were delivered to the skin by means of small circular probes (4- to 8-mm diam). 3. Twenty-three of the 29 SII neurons (80%) showed no change in response level (in impulses per second) as a result of SI inactivation. These included seven neurons activated exclusively or predominantly by Pacinian corpuscle (PC) receptors, six that received hair follicle input, four activated by convergent input from hairy and glabrous skin, and six driven by dynamically sensitive but non-PC inputs from the glabrous skin. 4. Six SII neurons (20%), also made up of different functional classes, displayed a reduction in response to cutaneous stimuli when SI was inactivated. 5. Stimulus-response relations, constructed by plotting response level in impulses per second against the amplitude of the mechanical stimulus, showed that the effect of SI inactivation on individual neurons was consistent over the whole response range. 6. The reduced response level seen in 20% of SII neurons in association with SI inactivation cannot be attributed to direct spread of cooling from SI to the forelimb area of SII, as there was no evidence for a cooling-induced prolongation in SII spike waveforms, an effect that is known to precede any cooling-induced reduction in responsiveness. 7. As SI inactivation produced a fall in spontaneous activity in the affected SII neurons, we suggest that the inactivation removes a source of background facilitatory influence that arises in SI and affects a small proportion of SII neurons. 8. Phase-locking and therefore the precision of impulse patterning were unchanged in the responses of SII neurons to vibration during SI inactivation. This was the case whether response levels of neurons were reduced or unchanged by SI inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Effects on serum lipids of adding fruits and vegetables to prudent diet in the Indian Experiment of Infarct Survival (IEIS).

In a randomized, single-blind and controlled trial, the effects of the administration of fruits and vegetables (mean 582 vs. 188 g/day) for 12 weeks were compared as adjuncts to a prudent diet in the management of 202 group A and 204 group B patients with acute myocardial infarction (AMI). Fruits and vegetables decreased total serum cholesterol level (26.4 vs. 13.8 mg/dl, p less than 0.01) low-density lipoprotein cholesterol (20.0 vs. 9.8 mg/dl, p less than 0.01), triglycerides (20.6 vs. 10.6 mg/dl, p less than 0.01) and fasting blood glucose (22.4 vs. 12.6 mg/dl, p less than 0.01) levels more significant in the intervention group than changes in the control group. Adherence to dietary advice was assessed by questionnaires. Total adherence score in group A was significantly higher than in group B. Group A patients also had a significantly smaller rise in lactate dehydrogenase cardiac enzyme which indicates that the protective effects of such a diet may be observed within 1 week. There was a significantly greater decrease in mean blood pressure in group A than changes in group B. These data suggest that fruits and vegetables, because of their high soluble dietary fibre and possibly high antioxidant contents, may be a useful and safe adjunct to a prudent diet in the treatment of patients with AMI. The use of fruits and vegetables may be preferred over oat bran, psyllium and guar gum because of their high content of vitamins and minerals.

Cholesterol↗