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Biomedical subjects

G Kumar

Publications and source records attributed to G Kumar.

At least 73 records · Page 4Linked to original sources
PubMed1995

Clinical profile of cholera in young children--a hospital based report.

Clinical profile of cholera was studied in children attending Diarrhea Training and Treatment Unit from January-December 1993. Out of a total 8714 cases of acute watery diarrhea, 64 children (0.7%) were suspected to have cholera on the basis of acute onset loose water/rice watery stools, high purge rate with or without excessive vomiting and/or severe dehydration. Stool culture was positive for cholera in 33 cases (51.6%). All the isolates were V. cholerae 01 biotype El Tor serotype Ogawa. Sixty four per cent of stool culture positive cases were below 5 years of age. The results assume importance because out of 28 children < 2 years with clinical suspicion of cholera, 11 cases (39.3%) were culture positive for V. cholerae, youngest child being 3 months old. Comparison of various parameters revealed that presence of vomiting > 4 episodes/ day (p < 0.005), frequency of stools >12/24 hours (p <0.002), rice watery stools (p < 0.01) and presence of severe dehydration (p < 0.01) were significant parameters associated with positive stool culture. Beside examination of stool sample by hanging drop method was an excellent diagnostic tool (p < 0.001) with a sensitivity of 51.5%, specificity 100% and positive predictive value of 100%. The isolates of V. cholerae were susceptible to furazolidone, cephelexin, nalidixic acid, norfloxacin and gentamicin. Our observations indicate that cholera is not uncommon in infants and young children. Like children in the older age group, acute onset diarrhea with watery/rice watery stools and high purge rate with or without excessive vomiting and/or rapid development of severe dehydration should arouse suspicion of cholera in younger children also. They should be investigated for cholera even in non-endemic areas and in the absence of cholera outbreaks.

Age Distribution↗
PubMed1994

Involvement of Janus kinases, p52shc, Raf-1, and MEK-1 in the IL-6-induced mitogen-activated protein kinase cascade of a growth-responsive B cell line.

We have previously shown that the IL-6R in a growth-responsive B cell line, AF10, induces activation of mitogen-activated protein (MAP) kinase. Here we demonstrate the activation of Raf-1 and MEK-1, which act as a MAP kinase kinase kinase and a MAP kinase kinase, respectively, in the MAP kinase cascade induced by IL-6 in AF10 cells. IL-6 also induced tyrosine phosphorylation of the signaling transducing subunit of the IL-6R in AF10 cells, along with tyrosine phosphorylation of the gp130-associated tyrosine protein kinase JAK1 and the adaptor molecule p52shc. Although induction of tyrosine phosphorylation and activation of MAP kinase by IL-6 in a differentiation-responsive B cell line, SKW 6.4, were below the limits of detection, the phorbol ester PMA did activate Raf-1, MEK-1, and MAP kinase without inducing the phosphorylation of gp130, JAKs, or p52shc. These results suggest that JAK kinase family members associated with the IL-6R may participate in the activation of MAP kinase in AF10 cells by way of an adaptor protein and Ras-dependent kinase cascade.

Adaptor Proteins, Signal Transducing↗
PubMed1994

A 70- to 80-kDa glial cell protein interacts with the AGGGAAGGGA domain of the JC virus early promoter only in the presence of the neighboring cis DNA elements.

The neurotropic virus JC (JCV) causes the demyelinating disease progressive multifocal leukoencephalopathy. JCV is transcriptionally regulated by both positive and negative cis elements. Previous studies have shown that the AGGGAAGGGA sequence, in isolation, interacts with a 53- to 56-kDa cellular protein and acts as a silencer for the late promoter. We have reexamined the role of the AGGGAAGGGA element in the glial cell-specific transcriptional regulation of JCV by studying it in a longer natural context of elements of the JCV early promoter. Transcriptional analysis in C6 glial cells of selectively mutated AGGGAAGGGA domains within the nt 98-153 region of the JCV early promoter revealed that both GGG regions in the AGGGAAGGGA sequence are required for glial cell-specific transcription. The interactions of cellular proteins with the AGGGAAGGGA domain were also found to be dependent upon the presence or absence of neighboring cis elements. The TATA region was found to facilitate the interaction of specific proteins with the AGGGAAGGGA domain. Domain-specific photocrosslinking studies revealed the binding of a glial cell protein of approximately 70-80 kDa to the AGGGAAAGGGA domain only when it was flanked by its neighboring cis elements, the TATA and NF-1 domains of the JCV promoter.

Affinity Labels↗
PubMed1994

The T-cell antigen receptor utilizes Lck, Raf-1, and MEK-1 for activating mitogen-activated protein kinase. Evidence for the existence of a second protein kinase C-dependent pathway in an Lck-negative Jurkat cell mutant.

T-cell antigen receptor (TCR) ligation of an Lck-deficient Jurkat mutant, J.CaM1, with anti-CD3 or anti-TCR beta monoclonal antibodies failed to induce tyrosine phosphorylation and activation of p42MAPK. The same stimuli activated mitogen-activated protein (MAP) kinase in J.CaM1 cells transfected with Lck, demonstrating that Lck plays a critical role in MAP kinase activation. Utilizing immunocomplex kinase assays, we demonstrated that TCR/CD3 ligation activated a MAP kinase kinase kinase (Raf-1) as well as a MAP kinase kinase (MEK-1) in Jurkat but not in J.CaM1 cells. It was possible, however, to activate Raf-1, MEK-1, and p42MAPK in J.CaM1 cells during treatment with the phorbol ester phorbol 12-myristate 13-acetate, which activates protein kinase C (PKC). This demonstrates the presence of a PKC-dependent pathway which functions independently from Lck in MAP kinase activation. Stimulation of Jurkat cells with either anti-TCR beta or anti-CD3 monoclonal antibody failed to induce substantial tyrosine phosphorylation of Shc proteins or their association with Grb2 which forms a complex with the guanine nucleotide exchange factor hSOS. However, the same stimuli induced tyrosine phosphorylation of another putative guanine nucleotide exchange factor, p95Vav, in Jurkat but not J.CaM1 cells. Moreover, Lck was reversibly co-immunoprecipitated with p95Vav, and the stoichiometry of binding increased in anti-CD3-treated Jurkat cells. Phorbol 12-myristate 13-acetate did not induce tyrosine phosphorylation of p95Vav. These data show that the TCR activates MAP kinase by way of a signaling cascade, which depends upon Lck, and may be mediated by downstream events involving PKC or p95Vav which act on Raf-1 and MEK-1.

Cell Line↗
PubMed1994

Maturation of the cholinergic response of tracheal smooth muscle in the piglet.

Maturational changes of the contractile properties of airway smooth muscle have been suggested to occur during the late prenatal and early postnatal period in the piglet. However, the timing and mechanisms involved remain elusive. Therefore, we studied isometric contraction of tracheal smooth muscle (TSM) to evaluate the effects of maturation on 1) the response of TSM to the muscarinic agonist acetylcholine (Ach); and 2) the regulatory activity of acetylcholinesterase (AChE) during the early postnatal period in the piglet. Studies were performed in 1-5-day-old (n = 6) and 14-22-day-old (n = 8) anesthetized, mechanically ventilated piglets. Changes in tracheal tension were measured in vivo from an open tracheal segment and normalized for both longitudinal length of the tracheal segment and cross-sectional area. Dose-response curves to locally applied Ach were obtained before and after the intravenous administration of the AChE inhibitor physostigmine (Phys). Ach-induced changes in tracheal tension significantly increased with maturation during the first 3 weeks of life (P < 0.01), regardless of normalization method. The addition of Phys significantly increased the cholinergic responses of TSM in both age groups (P < 0.02). However, this increase was comparable between age groups. There was also no difference in AChE activity measured in tracheal smooth muscle homogenates between the 1-5 and 14-22-day-old animals. These data indicate that maturation significantly enhances the cholinergic responses of tracheal smooth muscle in the early postnatal period in the piglet.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Expression and role of c-myc protooncogene in murine preimplantation embryonic development.

PURPOSE: The present study was conducted to investigate the expression and possible role of the c-myc protooncogene in preimplantation embryos by using reverse-transcriptase/polymerase chain reaction (RT-PCR) technique and microinjection of synthetic antisense c-myc oligonucleotide probe, respectively. Total RNA was extracted from oocytes and two cell-, four cell-, early morula-, late morula-, early blastocyst-, and late blastocyst-stage embryos, and cDNA was constructed using MMLV reverse transcriptase. Sense primer (P1) and antisense primer (P2) used were based on the c-myc gene sequence bp 1609-1629 and bp 3279-3299, respectively, that span a 1.37-kb intron. PCR-amplified products of cDNA from oocyte-, two cell-, four cell-, early and late morula-, and blastocyst-stage embryos demonstrated the expected 313-bp product in Southern blot hybridization using a c-myc specific DNA probe, with an indication of lower levels in oocytes and early morulae. RESULTS: Cytoplasmic injection of the antisense c-myc oligonucleotide probe (P2) and not the sense probe (P1) into pronuclear-stage zygotes caused a significant (P = 0.02 to 0.0001) inhibition of development to blastocysts in a concentration-dependent manner, with a maximal inhibition at the first cleavage of zygotes to two cell-stage embryos. There was no effect on the P2 antisense injection on pronucleus formation. CONCLUSION: These results indicate that the c-myc protooncogene is expressed in preimplantation embryos and may have an essential role in normal embryogenesis in mice.

Animals↗
PubMed1994

The effects of corticosteroid and reduced glutathione on the endothelial viability during culture in MK medium. A light microscopy study.

The effect of addition of dexamethasone and reduced glutathione to MK medium, in a concentration of 10(-3) Molar and 0.92 g/l, respectively, was evaluated. The post preservation corneal endothelial viability was assessed using light microscopy. Our results showed that the addition of dexamethasone to MK medium increased the preservation time of dog cornea from 7 to 10 days and that reduced glutathione could further increase the storage period to 12 days. It can be concluded that the addition of reduced glutathione to MK medium is an excellent means for intermediate term corneal preservation.

Animals↗
PubMed1993

Recombinant IL-6 activates p42 and p44 mitogen-activated protein kinases in the IL-6 responsive B cell line, AF-10.

IL-6 is a multi-functional cytokine that utilizes 80-kDa ligand-binding and 130-kDa signal-transducing subunits to stimulate diverse cellular responses. Although IL-6R ligation has been associated with tyrosine protein phosphorylation and activation of an unidentified serine/threonine kinase, very little is known about the intermediary signaling events between the cell membrane and the nucleus. rIL-6 treatment of the human B cell line, AF-10, induced MAP kinase (mitogen-activated protein kinase) activity as determined by in vitro phosphorylation of microtubule-associated protein-2 (MAP-2) and the synthetic peptide APRTPGGRR, corresponding to amino acids 95-98 of bovine myelin basic protein. The kinetics of the response was rapid and dependent on the dose of rIL-6. The response was cytokine specific, did not require the presence of extracellular Ca2+, and was minimally affected by the presence of staurosporine. MAP kinase activation in AF-10 cells occurred in parallel with appearance of 42- and 44-kDa tyrosine phosphoproteins (p42 and p44). Moreover, MAP kinase activation was diminished when AF-10 cells were stimulated with rIL-6 in the presence of tyrosine protein kinase inhibitors, genistein and geldanomycin. p42 and p44 co-electrophoresed on SDS-PAGE with extracellular signal-related kinase (ERK)-2, and ERK-1, respectively; both are members of the ERK family. In addition to p42MAPK and p44MAPK, rIL-6 also activated a MAP-2 kinase that eluted at a lower salt concentration (20 to 60 mM NaCl, peak I) from Mono-Q resin than p42MAPK (120 to 180 mM NaCl, peak II). The identify of this kinase is unknown but it is not an MPB kinase or a protein that exhibits immunoreactivity with anti-ERK antisera. In another IL-6-responsive B cell line, SKW6.4, rIL-6-activated peak I MAP-2 kinase but failed to activate ERK-2. The protein kinase C agonist, PMA, did, however, activate ERK-2 in SKW6.4 cells. These results show that the pleiotrophic cytokine, IL-6, activates p42MAPK/ERK-2 and at least one other serine/threonine kinase in B cell lines.

Amino Acid Sequence↗
PubMed1993

Localization of adjacent binding domains for cellular proteins over the minute virus of mice P4 promoter by site-specific photoaffinity labelling.

A photoaffinity labelling (PHL) procedure was used to localize the specific binding sites for A92L fibroblast nuclear proteins on the minute virus of mice (MVM) P4 promoter. We describe a chemical and biochemical method for the construction of precisely modified photoreactive (phr) DNA probes. In this method, a phenylazide group is attached to the DNA fragment by coupling SASD [sulfosuccinimidyl-2-(p-azidosalicyl-amido)ethyl-1,3'-dithiopro pio nate] to the primary amino group of the linker arm present at any predetermined position. These phr probes would identify, upon photocrosslinking, only those proteins which bind to the location of the phr group. Specifically, two phr probes representing the 139-172 bp region of the MVM P4 promoter were constructed in which the highly phr phenylazide group was attached with a linker at nucleotide 168, towards the side of the GC box proximal to the TATA box. The PHL studies with these photoprobes revealed that although the proteins of 95 and 120-kDa bind near nt 168 of the P4 promoter, the 120-kDa protein requires the region between the TATA box and the GC box for binding to the MVM P4 promoter.

Affinity Labels↗
PubMed1993

Self-reported suicidal ideation in adolescent psychiatric inpatients.

In an investigation of the psychosocial correlates of suicidal ideation in adolescent inpatients, the Beck Scale for Suicide Ideation (BSI) was administered to 108 inpatients between 12 and 17 years of age who were diagnosed with mixed psychiatric disorders. A series of multiple regression analyses that controlled for gender, ethnicity, age, diagnosis of a mood disorder, and a history of a past suicide attempt were then used to examine the relationships of the Beck Depression Inventory, Anxiety Inventory, and Hopelessness Scale (BHS) with the BSI. Regardless of the series, the BHS contributed unique variance to the explanation of the BSI scores. The results are discussed as supporting the use of the BSI with adolescent inpatients and indicating that hopelessness is related to suicidal ideation when depression is controlled for.

Adolescent↗
PubMed1993

Oncostatin-M stimulates tyrosine protein phosphorylation in parallel with the activation of p42MAPK/ERK-2 in Kaposi's cells. Evidence that this pathway is important in Kaposi cell growth.

Oncostatin-M (OSM) is a potent mitogen for Kaposi's sarcoma (KS) cells. We studied signaling by the OSM receptor in three AIDS-related KS lines and show induction of tyrosine phosphorylation of 145-, 120-, 85-, and 42-kD substrates. The 42-kD substrate was identified as p42MAPK (mitogen-activated protein kinase), also known as ERK-2. This serine/threonine kinase relays mitogenic signals from receptor tyrosine protein kinases (TPKs) or receptor-associated TPKs to transcriptional activators. The OSM dose dependence for MAP kinase activation and induction of KS cell growth were almost identical, suggesting functional linkage. MAP kinase activation was dependent on tyrosine phosphorylation, and both OSM-induced MAP kinase activity and KS cell growth could be suppressed by TPK inhibitors, genistein and geldanomycin. OSM also stimulated tyrosine phosphorylation of similar substrates and MAP kinase activity in human vein endothelial cells. While it has been proposed that the OSM receptor may include the gp130 subunit of the IL-6 receptor and alpha-chain of leukemia inhibitory factor (LIF) receptor, neither LIF nor r.IL-6 induced tyrosine protein phosphorylation or p42MAPK activation in KS cells. However, r.IL-6 did stimulate tyrosine phosphorylation and p42MAPK activity in the human B cell line, AF-10, while OSM and LIF exerted no effects. Our results indicate that, although the OSM and IL-6 receptors share a common signaling pathway, this pathway is selectively activated by OSM in Kaposi's cells.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Hopelessness in adolescent psychiatric inpatients.

To study hopelessness in adolescent inpatients, we administered the Beck Hopelessness Scale to 108 inpatients between 12 and 17 years old who were diagnosed with mixed psychiatric disorders. Moderate to severe pessimism about the future was described by 42.6%. A principal components analysis of the correlations among the scale's 20 items was conducted, and three components reflecting rejection of the possibility of a hopeful future, acceptance of the inevitability of a hopeless future, and resignation to the futility of changing the future were identified. These dimensions were comparable to those previously reported for adults, and the usefulness of the scale for evaluating hopelessness in adolescent inpatients was discussed.

Adolescent↗
PubMed1993

c-MYC mRNA is present in human sperm cells.

Stage-specific expression of proto-oncogenes, including c-myc, has been demonstrated during spermatogenesis in testis. Some of these proto-oncogenes are expressed postmeiotically, especially in the round spermatid stage. Recently, we demonstrated the presence of c-myc protein in mature ejaculated sperm cells with a possible role in sperm cell function. Since the half-life of c-myc protein has been shown to be short, we suspected the presence of c-myc mRNA in human sperm cells. In the present study, the presence of the c-myc mRNA transcript in human sperm cells was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and in situ hybridization. Total RNA, 5-10 micrograms, was extracted from 0.2-0.5 ml of pelleted human sperm cells by NP-40 lysis procedure, and was used to construct cDNA with pd(N)6 random primer and Moloney Murine Leukemia Virus (MMLV) reverse transcriptase. The PCR with sperm cDNA and primers #P1 and #P2, both from exon 3, resulted in amplification of the expected 322 bp product. Primers #P3 and #P4, which are located in exon 2 and exon 3, respectively, and are 1.37 kb apart, gave the expected PCR amplified 313 bp product ruling out the possibility of DNA contamination. The presence of c-myc mRNA in human sperm cells was further confirmed by in situ hybridization using a digoxigenin labelled DNA probe, containing exon 2 of the c-myc gene sequence. The c-myc specific DNA probe reacted with the postacrosomal mid-piece and tail regions of both noncapacitated as well as capacitated methanol-fixed sperm cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗