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Biomedical subjects

M Kumar

Publications and source records attributed to M Kumar.

At least 19 recordsLinked to original sources
PubMed1997

Expression of lacZ reporter gene under the control of the polyhedrin promoter of Spodoptera litura nuclear polyhedrosis virus.

Promoter function of the putative polyhedrin-encoding gene (polh) of Spodoptera litura nuclear polyhedrosis virus (S1MNPV) was determined by transferring it to the Autographa californica nuclear polyhedrosis virus (AcMNPV) through the AcNPV polh based vector, pVL1393. Three transfer vectors pCBT2, pCBT3 and pCBT4 were constructed by substituting the promoter and the neighbouring sequences of AcNPV in pVL1393 by that of S1NPV. The Escherichia coli lacZ gene was placed downstream from the S1NPV polh promoter in the hybrid transfer vector (pCBT) constructs. Co-transfection of Spodoptera frugiperda cells (Sf9) with each of the pCBTlacZ vector and wild-type AcNPV DNAs led to synthesis of beta-galactosidase (beta Gal). The plaque-purified recombinant viruses (S1AcNPV.lacZ) expressing lacZ under the polh promoter of S1NPV are stable. The highest beta Gal activity was obtained with S1AcNPV4.lacZ. Production of beta Gal with recombinant virus, S1AcNPV3.lacZ in which S1NPV polh promoter is in the reverse orientation in the AcNPV genome, is 83% of that produced by S1AcNPV4.lacZ. These results indicate that the S1NPV polh promoter is active in the genetic environment of AcNPV; the polh of S1NPV is phylogenetically related to AcNPV like other baculoviruses.

Animals↗
PubMed1997

Nuclear antisense RNA induces extensive adenosine modifications and nuclear retention of target transcripts.

Antisense RNA may regulate the expression of a number of eukaryotic genes, but little is known about its prevalence or mechanism of action. We have used a model system in which antisense control can be studied both genetically and biochemically. Late in polyoma virus infection, early-strand mRNA levels are down-regulated by nuclear antisense RNA from the late strand. Analysis of early-strand transcripts isolated late in infection revealed extensive base modifications. In many transcripts almost half of the adenosines were altered to inosines or guanosines. These results suggest modification of RNA duplexes by double-stranded RNA adenosine deaminase or a related enzyme. Probes that detect only modified RNAs revealed that these molecules are not highly unstable, but accumulate within the nucleus and are thus inert for gene expression. Antisense-induced modifications can account for most or all of the observed regulation, with the lowered levels of early-strand RNAs commonly observed late in infection resulting from the fact that many transcripts are invisible to standard hybridization probes. This work suggests that similar antisense-mediated control mechanisms may also operate under physiological conditions in uninfected eukaryotic cells, and leads to the proposal that there is a novel pool of nuclear RNAs that cannot be seen with many molecular probes heretofore used.

3T3 Cells↗
PubMed1997

Novel gene delivery to liver cells using engineered virosomes.

We have demonstrated for the first time that the reconstituted Sendai viral envelopes containing only the fusion protein (F-virosomes) are efficient vehicles for the delivery of foreign genes specifically into human hepatoblastoma cells (HepG2) in culture. The membrane fusion-mediated entry of CAT (chloramphenicol acetyl transferase) gene into the cells was confirmed and the amount delivered to various subcellular fractions was quantitated. The dose dependence and kinetics of expression of biologically active CAT protein in HepG2 cells was measured. The CAT expression level in F-virosome-mediated delivery was significantly higher than that of Lipofectin or liganded proteo-liposome-mediated gene transfer. This kind of targeted delivery by means of membrane fusion induced by viral envelope glycoprotein may have wide applications to various gene transfer strategies both in vitro and in vivo.

Animals↗
PubMed1997

The effect of selected classical music and spontaneous imagery on plasma beta-endorphin.

This study explored the effect of music and imagery on plasma beta-endorphin in 78 undergraduates. Subjects screened for relevant psychological and health criteria were assigned to music imaging, silent imaging, music listening, and control conditions. Subjects donated 15 ml of blood prior to and following the 2-hr intervention period. There were no group differences in potential confounding variables. Split-plot factorial analysis controlling for individual differences in pretest level of beta-endorphin revealed that those in the music imaging group experienced a significant pre-post decline in beta-endorphin, while no other group demonstrated any significant pre-post difference. These data suggest that music imaging may lower peripheral beta-endorphin levels in healthy subjects. Further exploration of the effects of music and imagery interventions on physiology and health may be warranted.

Analysis of Variance↗
PubMed1997

Cognitive-behavioral stress management decreases dysphoric mood and herpes simplex virus-type 2 antibody titers in symptomatic HIV-seropositive gay men.

This study tested the effects of a 10-week group cognitive-behavioral stress management (CBSM) intervention on mood and immunologic parameters in HIV-seropositive gay men whose disease had progressed to a symptomatic stage. Men were randomized to either CBSM or a modified waiting-list control group. The CBSM intervention significantly decreased self-reported dysphoria, anxiety, and total distress. Individuals who practiced relaxation more consistently had significantly greater drops in dysphoria. The intervention also decreased herpes simplex virus-Type 2 (HSV-2) immunoglobulin G antibody titers. The control group showed no significant changes in either mood or antibody titers. Individual difference analyses revealed that decreases in dysphoria significantly predicted lower HSV-2 antibody titers by the end of the 10-week period. Neither group displayed changes in HSV-Type 1 antibody titers or in CD4+ or CD8+ cell numbers.

Adult↗
PubMed1997

Toxicity associated with high-dose cytosine arabinoside and total body irradiation as conditioning for allogeneic bone marrow transplantation.

Seventy-three patients with hematological cancers undergoing allogeneic bone marrow transplantation (BMT) were evaluated for event-free survival (EFS) and toxicity. All received 36 g/m2 cytosine arabinoside (HDA) and 1200 cGy fractionated total body irradiation (TBI). We assessed the association of EFS and toxicities with the following risk factors; age, gender, diagnosis, initial relapse risk and patient-donor histocompatibility. The EFS probability is 33% at 800 days post-BMT. Twenty-six patients (36%) died of toxicity within 100 days and 14 (19%) have relapsed. EFS was inversely associated with age (P < 0.0001) and initial relapse risk (P = 0.007). The risk of pulmonary (P = 0.023) and hepatic toxicity (P = 0.011) increased with age. Diagnosis other than acute lymphoblastic leukemia (ALL) was a risk factor (P = 0.015) for graft-versus-host disease (GVHD); and fewer ALL patients died from toxicity (P = 0.014). The probability of sepsis within 100 days post-BMT correlated (P = 0.007) with initial relapse risk. We conclude: (1) the lower EFS and greater pulmonary and hepatic toxicity associated with increasing age indicate a need for less toxic regimens that maintain high antileukemic efficacy for older patients; (2) the high GVHD and sepsis rates seen in certain categories of patients indicate a need for careful definition of eligibility criteria for this still highly toxic treatment.

Adolescent↗
PubMed1997

Endoscopic sclerotherapy for esophageal varices in children with extrahepatic portal venous obstruction: a follow-up study.

BACKGROUND: Results of treatment with endoscopic sclerotherapy for esophageal varices in children extrahepatic portal venous obstruction are limited. METHODS: A prospective study was undertaken of fifty children (mean age, 7.4 +/- 3.8 years; range, 4 months to 14 years) with esophageal variceal bleeding caused by extrahepatic portal venous obstruction (EHPVO) treated by repeated intravariceal endoscopic sclerotherapy (EST) at intervals of 2-3 weeks until eradication (no varices on endoscopy). RESULTS: Eradication of varices was achieved in 44 children (88%) with a mean of eight sessions per child. In six other cases, variceal grade decreased by 50% from the initial grades. Bleeding episodes at presentation were controlled in all of the children with first ET >. Over a mean follow-up period of 19 months (range, 12-36 months), a total of 15 episodes of rebleeding occurred in 13 children (26%) before the third session of EST and all were controlled with EST. Risk of rebleeding in children with eradicated varices (n = 44) significantly decreased from 0.2 episodes per month to nil after eradication. None of the children without eradicated varices had rebleeding. Thus, EST was successful in controlling rebleeding in all of the cases. Recurrence of varices was observed in five children (10%). None of our children either required surgery for EST failure or died. CONCLUSIONS: EST is a safe and effective nonsurgical mode of therapy in controlling esophageal variceal bleeding in children with EHPVO. Significant variceal bleeding did not occur during the relatively short follow-up in this series.

Adolescent↗
PubMed1997

Endoscopic management of traumatic posterior urethral stricture: early results and followup.

PURPOSE: We assessed the outcome of core through internal urethrotomy for traumatic posterior urethral stricture, and reviewed the followup results of these patients. MATERIALS AND METHODS: During the last 4 years 13 patients with a stricture up to 2 cm. long underwent core through internal urethrotomy with C-arm fluoroscopy guidance and an orientation in 2 planes. Retrograde urethrotomy was performed and an 18F Foley catheter was left indwelling for 4 weeks, after which urethrotomy was repeated. All patients were advised to perform clean intermittent self-catheterization for urethral calibration and dilation. Outcome was defined as class 1-3 patients who required 2 or fewer urethrotomies with clean intermittent self-catheterization discontinued after the primary procedure, class 2-5 who required 2 or fewer urethrotomies with clean intermittent self-catheterization and class 3-5 who required 3 or more urethrotomies. RESULTS: Of the 13 patients 8 (61%) did well after a mean followup of 17.7 months. The 3 patients with a class 1 outcome did well, while 2 of 5 with a class 2 outcome required repeat urethrotomy during followup. Of the 5 patients (39%) with a class 3 outcome in whom core through internal urethrotomy failed 3 required open surgery and 2 were lost to followup. Recurrence rate was 69% at 3 months and 25% at 12 months after the initial procedure. No patient was incontinent at last followup. Two patients had significant hematuria postoperatively, which resolved with conservative treatment. CONCLUSIONS: Endoscopic treatment should be considered the first line procedure for all post-traumatic posterior urethral strictures. The morbidity of open surgery can be avoided in 61% of patients. Hospital stay, loss of work, morbidity and related complications are also markedly decreased with endoscopic therapy.

Adult↗
PubMed1997

Chronic renal failure and nephrolithiasis in a solitary kidney: role of intervention.

PURPOSE: We determined the role of intervention and its outcome in patients with a solitary kidney, nephrolithiasis and chronic renal insufficiency, as well as the role of clearance in these patients compared to those with a solitary kidney, nephrolithiasis and normal renal function. MATERIALS AND METHODS: A total of 36 records was evaluable, including 16 from patients with normal (group 1) and 20 from those with abnormal (group 2) renal function. Group 2 was further subdivided into those with mild to moderate (group 2A) and advanced (group 2B) renal failure. Patients with acute renal failure were excluded from the study. Glomerular filtration rate was calculated by the Cockcroft and Gault formula. The reciprocal of serum creatinine was used to determine outcome. RESULTS: Groups 1 and 2 were comparable demographically except for serum creatinine, stone bulk and hospital stay. Of 36 patients 8 with normal renal function and 15 with chronic renal failure underwent percutaneous nephrolitholapaxy, 6 underwent extracorporeal shock wave lithotripsy and 7 underwent open surgery. Total clearance was achieved in 25 of 36 patients (72%). Glomerular filtration rate improved in 24 patients, remained stable in 8 and deteriorated in 4. However, 3 patients had less than 20% deterioration and 1 had significant deterioration in function after intervention. Improvement in glomerular filtration rate after intervention was significantly greater in cases of advanced renal failure. Patients with residual stones did worse than those without residual calculi. Mean hospital stay, deterioration in glomerular filtration rate and major morbidity rate were significantly greater in patients with residual calculi than in those with total clearance. CONCLUSIONS: Intervention should be contemplated in patients with a solitary kidney, stone disease and renal failure as in any other patient with stone disease, with the aim being total clearance. Stone eradication delays deterioration, and decreases the requirement for dialysis and renal replacement.

Adult↗
PubMed1996

Selective expression of c-mas proto-oncogene in rat cerebral endothelial cells.

Northern blot analysis of cultured endothelial cells derived from rat cerebral resistance vessels demonstrated the presence of c-mas mRNA. This is the first description of mas expression in non-neuronal cells. c-mas message was not detectable in cultured endothelial cells derived from other vascular beds, including rat aorta and mesenteric resistance vessels. Since c-mas has been purported to regulate the proliferation response to angiotensin, the growth properties of all three endothelial cell cultures were examined. The data indicated no differences in either basal or angiotensin-stimulated cell growth among brain, mesenteric or aortic-derived endothelial cells. These data suggest that c-mas is selectively expressed in brain endothelial cells and that this proto-oncogene does not regulate cell proliferation in this cell type.

Angiotensin II↗
PubMed1996

Local control in synchronous bilateral Wilms tumor.

PURPOSE: To evaluate the role of radiation therapy (RT), chemotherapy (CT), and surgery in the local control of synchronous bilateral Wilms Tumor (WT). METHODS AND MATERIALS: Between 1962 to 1993, 45 children were treated for bilateral WT; 38 patients with synchronous tumors were reviewed. Initial surgery depended on the era of treatment and included unilateral nephrectomy (N)/partial nephrectomy (PN) and contralateral PN in 6, unilateral N/PN alone in 7, and biopsy only in 25. Chemotherapy (CT) consisted of vincristine, actinomycin-D, and adriamycin in 32 and vincristine/ actinomycin-D in 6. Radiation therapy (RT) was given to 32 patients. Treatment included both kidneys in 20, unilateral kidney plus contralateral renal bed in 9, unilateral kidney in 2, and unilateral renal bed in 1. Follow-up was 16 months to 25 years (median: 6.3 years). RESULTS: Local control (LC) has been maintained in 66 out of 76 sites (87%). For Stage I-II disease with initial N/PN, LC was 10 out of 12 with RT and 11 out of 11 without RT; for Stage III with initial N/PN, LC was 8 out of 9 with RT and 1 out of 1 without RT. Initial CT and RT was followed by delayed N/PN for 20 sites; LC was 15 out of 17 in post induction Stage I-II and 1 out of 3 in postinduction Stage III. In 23 sites undergoing biopsy and chemotherapy, LC was 19 out of 20 with RT and 1 out of 3 without RT. Seven of 23 sites had a complete response (CR) after induction CT, and LC was maintained in four out of four with RT and one out of three without RT. Univariate Cox Regression analysis demonstrated that sites receiving two drugs had a statistically significant increase in loco-regional relapse when compared to sites receiving three drugs (p = 0.004). Major morbidities related to multimodality therapy have included renal failure in one patient and small bowel obstruction requiring lysis of adhesions in two patients. CONCLUSIONS: Local control does not seem to be compromised by renal conservation therapy. Local control is excellent in sites treated with radiation therapy in combination with three drug chemotherapy.

Adolescent↗
PubMed1996

F protein induced fusion of Sendai viral envelopes with mouse teratocarcinoma cells through Le(x)-Le(x) interaction.

The efficiency of membrane fusion between reconstituted Sendai viral envelopes containing only the fusion protein (F-virosomes) and the plasma membrane of mouse teratocarcinoma cells (F9) in culture was assessed using an assay based on the relief of self-quenching of a lipid probe incorporated in the F-virosomes. The potential of F-virosomes was also evaluated for a targeted cytosolic delivery of lysozyme to F9 cells. [125I]Lysozyme entrapped into F-virosomes was taken to examine its fusion-mediated transfer to the F9 cells. Target specificity of the F-virosomes was confirmed by the interaction between the terminal Le(x) moiety (Gal beta 1-->4(Fuc alpha 1-->3)GlcNAc) of F protein and the Le(x) determinant on the membrane of F9 cells. Incubation of the loaded F-virosomes with cells led to fusion-mediated delivery, as inferred from the ability of cells to internalize lysozyme in the presence of azide (a potent inhibitor of endocytosis). These results suggest that carbohydrate-carbohydrate interaction is strong enough for target cell recognition followed by phospholipid bilayer melding induced by fusion glycoprotein of Sendai virus.

Animals↗
PubMed1996

Anoxic injury of endothelial cells increases production of nitric oxide and hydroxyl radicals.

Reactive oxygen radicals have been implicated as mediators of anoxic injury in brain, but the cellular source of these radicals is unknown. In the periphery, there is evidence that endothelial cells play a fundamental role in anoxic tissue injury. The objective of the present study was to examine the response of rat brain endothelial cells to anoxia/reoxygenation injury in vitro. The results demonstrate that brain endothelial cells produce hydroxyl radicals and have increased nitric oxide synthase activity after anoxic injury. The increased production of nitric oxide in the cerebral endothelial cells does not appear to be mediated by an increase in either inducible or constitutive nitric oxide synthase. The radical trap alpha-phenyl-tert-butyl nitrone blocked hydroxyl free radical production, but not nitric oxide. These data suggest that the cerebral microcirculation may be an important site of oxygen free radical production in the brain in ischemic stroke.

Aerobiosis↗
PubMed1996

Regulation of FGF receptors in the oligodendrocyte lineage.

Fibroblast growth factors (FGFs) affect a broad spectrum of developmentally regulated cellular responses involved in the control of growth and differentiation. To identify specific FGF receptor forms involved in these responses, we have characterized FGF receptor transcript expression, and its modulation by FGF-2, as enriched populations of oligodendrocyte progenitors differentiate into mature oligodendrocytes. The data demonstrate that the levels of mRNA expression for FGF high-affinity receptors-1, -2, and -3 are differentially regulated during lineage progression: FGF receptor-1 expression increases with lineage progression, FGF receptor-2 is predominantly expressed by terminally differentiated oligodendrocytes, and FGF receptor-3 reaches a peak level of expression in late progenitors and then declines upon further differentiation; FGF receptor-4 expression was not detected in oligodendrocytes. Distinct patterns of alternatively spliced variants of FGF receptor-1 and -2 transcripts are expressed: the predominant FGF receptor-1 transcripts contain three Ig-like domains (FGF receptor-1 alpha), whereas the FGF receptor-2 transcripts contain two Ig-like domains (FGF receptor-2 beta 2) and this form is up-regulated as oligodendrocytes differentiate. In addition, the expression of these receptors is differentially regulated by the ligand, FGF-2: FGF receptor-1 mRNA expression is up-regulated in early progenitors, and FGF receptor-2 mRNA expression is down-regulated in mature oligodendrocytes. Finally, astrocytes express FGF receptor-1, -2, and -3 transcripts, but at different levels and with different exon utilization (FGF receptor-1 beta, FGF receptor-2 beta 1/beta 2) compared to oligodendrocytes. To our knowledge this is the first report that demonstrates that the mRNA expression of these three FGF receptor types is differentially regulated in primary cells as they differentiate along a lineage from progenitors to terminally differentiated cells. We propose that this pattern of expression provides a molecular basis for the developmentally varying response of cells to a common ligand. For example, according to this hypothesis, in response to FGF-2, FGF receptor-1 transduces signals that stimulate the prolonged proliferation and migration of early progenitors, FGF receptor-3 promotes the proliferation and arrest of differentiation of late progenitors, and FGF receptor-2 transduces signals for terminal differentiation, but not proliferation, in mature oligodendrocytes.

Alternative Splicing↗
PubMed1996

Developmental and FGF-2-mediated regulation of syndecans (1-4) and glypican in oligodendrocytes.

Differentiating cells undergo developmentally regulated changes in cell-cell and cell-matrix adhesion that control migration through microenvironments, proliferation, and differentiation. The diversity of the patterns of expression of heparan sulfate proteoglycans (HSPGs), coupled with their interactions with extracellular matrix, cell adhesion molecules, and growth factors, has emphasized their critical importance in the regulation of these events. Syndecans (1-4), glypican, and cerebroglycan are membrane-associated HSPGs that have been implicated in these events in various tissues and several tumor cell lines. We have examined the developmental expression and FGF-2-mediated regulation of these HSPGs during differentiation within a specific lineage of primary cells, oligodendrocytes (OL). Northern analyses of highly purified, developmentally synchronized populations of OL-lineage cells at three stages of differentiation (early and late progenitors and mature OLs) showed that the expression of individual forms of these syndecans and glypican are developmentally regulated. Specifically, the level of expression of syndecan-2 and -4 and glypican mRNAs increased as the cells differentiated from proliferative late progenitors to postmitotic mature cells. The expression of syndecan-1 and -3 had the inverse developmental pattern. Therefore, these two sets of molecules may have different roles in regulating the onset of terminal differentiation in OLs. The levels of mRNA expression were regulated by FGF-2: in late progenitors, FGF-2 induced a doubling of the mRNA levels of syndecan-2, -3, and -4, while those for syndecan-1 and glypican remained unaffected; in mature OLs, the levels of syndecan-1 mRNA were up-regulated, the levels of syndecan-2 and -4 and glypican were down-regulated. These results suggest that the individual syndecan molecules have distinct functions during the differentiation process and that multiple levels of regulation must exist, leading to a changing repertoire of these molecules during OL lineage progression and myelinogenesis.

Animals↗
PubMed1996

Comparison of the effect of left ventricular volume and pressure overload on beta-adrenoceptor density in left heart valvular disease.

The sympathetic responses in left heart valvular disease may depend on the ventricular load conditions. We proposed to evaluate this possibility by comparing the effects of left ventricular pressure (LVP) and volume (LVV) overload on beta-adrenoceptor density and ligand binding affinity in lymphocytes and in the four myocardial chambers in rheumatic heart valvular patients. Receptor activity was determined by radioligand binding using [125I]iodocyanopindolol. In the lymphocytes (n = 45), the beta-adrenoceptor density was reduced by 88% (P < 0.001) in LVP patients (n = 15) and 79% (P < 0.001) in LVV patients (n = 30) compared with 23 controls. In the myocardium, the receptor density of the LVP (n = 12) was attenuated by 55% (P < 0.05) in the left ventricle, 42% in the right ventricle, 13% in the left atrium, and 37% in the right atrium, while in LVV patients (n = 22) it decreased by 73% (P < 0.01) in the left ventricle, 62% (P < 0.05) in the right ventricle, 30% in the left atrium, and 34% in the right atrium compared with 15 controls. Thus, the reduction in density was greatest in lymphocytes and least in the atria in both groups. The decrease in ventricular density of the LVV group was similar to the reduction in the lymphocytes and two-fold higher than in the atrial density. These alterations were significantly greater for the LVV than for the LVP group. The Kd for the myocardial receptor binding to [125I]iodocyanopindolol was not significantly influenced in either group, but was lower in the lymphocytes. These findings suggest that in patients with left heart valvular disease, there is a significant attenuation in both peripheral and myocardial beta-adrenoceptor density. The decrease in receptor density is significantly greater in the left ventricular volume overload than in the left ventricular pressure overload patients.

Adolescent↗
PubMed1996

Effect of left ventricular pressure and volume overload on alpha-adrenoceptor activity in patients with rheumatic heart valvular disease.

We have investigated the possibility that the various left ventricular load conditions may exert different effects on the sympathetic function by comparing the influence of volume (VOL) and pressure (POL) overload on platelet alpha-adrenoceptor activity, plasma catecholamines and cAMP in 44 patients with rheumatic heart valvular disease. Receptor activity was determined by radioligand binding methods, catecholamines by HPLC using an electrochemical detector, and cAMP by radioimmunoassay. The mean alpha-adrenoceptor density (Bmax) of the control group (n = 29) was 4.71 +/- 0.41 fmol per 10(7) platelets and the corresponding dissociation constant (Kd) was 2.47 +/- 0.15 nM. In VOL patients, the density was elevated by 70% (P < 0.0001), but it remained unchanged in the POL patients. In contrast to the Bmax, the Kd of the VOL group was not changed, and it increased by 34% (P < 0.01) in the POL group. Norepinephrine was elevated by 91% (P < 0.05) in POL, and epinephrine increased by 65% (P < 0.05) in POL and 71% (P < 0.05) in VOL. These results suggest that the sympathetic nervous system responds to left ventricular volume overload by increasing alpha-adrenoceptor density with no apparent change in receptor affinity toward [3H]-yohimbine binding, and to left ventricular pressure overload by decreasing their binding affinity without a parallel decrease in receptor density. The increase in receptor density in VOL is accompanied by an increase in plasma epinephrine, and the decrease in binding affinity in POL is associated with increased plasma norepinephrine and epinephrine levels.

Adolescent↗