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K S Kumar

Publications and source records attributed to K S Kumar.

At least 19 recordsLinked to original sources
PubMed2006

Parity-violating electron scattering from 4He and the strange electric form factor of the nucleon.

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 4He at an average scattering angle = 5.7 degrees and a four-momentum transfer Q2 = 0.091 GeV2 . From these data, for the first time, the strange electric form factor of the nucleon G(E)s can be isolated. The measured asymmetry of A(PV) = (6.72 +/- 0.84(stat) +/- 0.21(syst) x 10(-6) yields a value of G(E)s = -0.038 +/- 0.042(stat) +/- 0.010(syst), consistent with zero.

Journal Article↗
PubMed2005

Precision measurement of the weak mixing angle in Møller scattering.

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.

Journal Article↗
PubMed2004

Measurement of the generalized polarizabilities of the proton in virtual Compton scattering at Q2=0.92 and 1.76 GeV2.

We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions P(LL)-P(TT)/epsilon and P(LT), and the electric and magnetic generalized polarizabilities (GPs) alpha(E)(Q2) and beta(M)(Q2) at momentum transfer Q(2)=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from piN intermediate states.

Journal Article↗
PubMed2004

Observation of parity nonconservation in møller scattering.

We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV)=[-175+/-30(stat)+/-20(syst)] x 10(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron's weak charge at low energy Q(e)(W)=-0.053+/-0.011. This is consistent with the standard model expectation at the current level of precision: sin((2)theta(W)(M(Z))((-)MS)=0.2293+/-0.0024(stat)+/-0.0016(syst)+/-0.0006(theory).

Journal Article↗
PubMed2004

Correlation of percutaneous liver biopsy fragmentation with the degree of fibrosis.

BACKGROUND: Although fragmentation of a liver biopsy specimen has been considered to be suggestive of cirrhosis, the evidence for this is difficult to find in the published literature. AIM: To determine whether fragmentation of percutaneous liver biopsy specimens correlates with the degree of fibrosis. METHODS: One hundred and eighty-six patients underwent percutaneous liver biopsy prospectively. The specimens were measured for the length and number of fragments. The extent of fibrosis was scored by a pathologist blind to the clinical data. Length and fragmentation data were compared between the different stages. RESULTS: The overall median fragment length was 1.85 cm and the median fragment number was four. Specimens with advanced fibrosis (stages III-IV) had more fragments than those with no or mild fibrosis (stages 0-II) (P < 0.0001). The aggregate fragment length decreased with increasing stage of fibrosis (P < 0.0001). Specimens with greater than 12 fragments were seen only with advanced fibrosis. CONCLUSIONS: Fragmentation of percutaneous liver biopsy specimens is common and increases with progression from early to advanced fibrosis. Fibrotic specimens fragment more often and more extensively.

Adult↗
PubMed2004

N-palmitoylation of the radioprotective domain of interleukin-1 affords inhibition of LPS-induced nitric oxide generation.

Interleukin-1beta (IL-1beta), a cytokine involved in homeostatic processes such as the immune system and inflammatory reactions, is a potent inducer of nitric oxide. The nonapeptide of human IL-1beta (VQGEESNDK, position 163-171, specific radioprotective domain--SRD) has been shown to retain radioprotective, immunostimulatory, and adjuvant activities of the native molecule without any inflammatory and pyrogenic properties. Unlike the parent IL-1, SRD did not induce nitric oxide (NO) in control or irradiated RAW 264.7 cells nor did it affect inducible nitric oxide synthase (iNOS) as shown by ELISA based mRNA assay (Quantikine). A lipophillic derivative of the SRD (a palmitoyl residue at the amino terminus of the SRD) was synthesized (palmitoyl specific radioprotective domain, P-SRD) to find out if this structural derivatization would restore the NO-inducing ability of IL-1. Surprisingly, P-SRD not only did not induce NO, but significantly inhibited lipopolysaccharide (LPS) stimulated nitric oxide (NO) production. Quantikine studies indicated that P-SRD also inhibited iNOS in LPS stimulated macrophage cells, suggesting that decrease in NO production in the presence of P-SRD was the result of iNOS mRNA inhibition. These results indicate that N-palmitoylation of SRD may effectively ameliorate potentially fatal symptoms of LPS-induced endotoxemic hypotensive shock associated with IL-1 without inflammatory and pyrogenic toxic side effects.

Amino Acid Sequence↗
PubMed2004

Aspiration of a tracheostomy tube flange.

Foreign body aspiration is a common pediatric emergency. Aspiration of a metallic tracheostomy tube flange into the left main bronchus and the resultant subacute respiratory distress is presented. Being the only case of its kind in reported pediatric literature, a review of the etiology, clinical presentation and prevention of this accident is appended.

Bronchi↗
PubMed2003

Bloody diarrhea caused by a needle in the pancreatic head.

Bloody diarrhea in adolescents is not uncommon polyposis, inflammatory bowel disease, and infections are the usual causes. A 13-year-old boy with a metallic foreign body in the head of the pancreas presented with bloody diarrhea. The clinical problems and surgical approach are discussed.

Adolescent↗
PubMed2003

Tri(propylene glycol) glycerolate diacrylate cross-linked polystyrene: a new resin support for solid-phase peptide synthesis.

A highly flexible, mechanically and chemically stable copolymer, tri(propylene glycol) glycerolate diacrylate cross-linked polystyrene (PS-TRPGGDA), was synthesized by the suspension polymerization and employed as a solid support for peptide synthesis. The beaded polymer support containing secondary hydroxyl functional groups in the cross-linker was used as the growth site for peptide synthesis. The procedure is unique and cost-effective in that it avoids the initial functionalization steps required for most of the styrene-based polymer supports. The resin was characterized by 13C-CP-MAS NMR spectroscopy and the morphologic features of the resin were investigated using scanning electron microscopy. Swelling studies conducted on the new support revealed that the PS-TRPGGDA resin undergoes more effective swelling and solvation than PS-DVB resin in all solvents used in peptide synthesis. The efficiency of the new support was demonstrated by synthesizing a 'difficult' sequence Ala-Arg-(Ala)6-Lys and comparing it with commercially available Merrifield and Sheppard resins. The synthetic efficiency was further demonstrated by the synthesis of a 24-residue NR 2A peptide substrate of calcium/calmodulin-binding peptide. The high yield and purity of the peptide synthesized on the novel support indicates the positive role of the flexible and hydrophilic cross-linking agent in the solid support.

Acrylates↗
PubMed2003

Synthesis of retro acyl carrier protein (74-65) fragment on a new glycerol based polystyrene support.

Retro-ACP (74-65) fragment was synthesized on a novel 4% tri-(propylene glycol) glycerolate diacrylate cross-linked polystyrene (PS-TRPGGDA) support. The peptide is grown from the functional site present in the cross-linker, which makes it unique and cost-effective among other styrene based polymer supports. A comparative study with Merrifield resin indicates high yield and purity of the peptide synthesized on the novel support.

Acrylates↗
PubMed2003

Rhinosporidiosis presenting as recurrent nasal polyps.

Rhinosporidiosis is a chronic granulomatous disease of the mucous membrane, predominantly of the nose and nasopharynx. It is uncommon in Malaysia but has been seen in immigrant workers from endemic areas like India and Sri Lanka. A case seen in Johor is reported here to highlight the need of awareness among clinicians at a time where there is increasing numbers of immigrant workers in our country. The causative organism of this disease is Rhinosporidium seeberi, which is found in stagnant waters. Sporangia and endospores of R. seeberi are seen in the granulomatous polypoidal lesions. The patients commonly present with epistaxis and nasal blockage. Complete excision is the treatment of choice for this disease. Recurrences are common despite anti-microbial treatment.

Adult↗
PubMed2002

Q2 evolution of the generalized Gerasimov-Drell-Hearn integral for the neutron using a 3He target.

We present data on the inclusive scattering of polarized electrons from a polarized 3He target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5 degrees. Our data include measurements from the quasielastic peak, through the nucleon resonance region, and beyond, and were used to determine the virtual photon cross-section difference sigma(1/2)-sigma(3/2). We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of four-momentum transfer squared Q2 of 0.1-0.9 GeV2.

Journal Article↗
PubMed2002

Sequence determinants on the NR2A and NR2B subunits of NMDA receptor responsible for specificity of phosphorylation by CaMKII.

Calcium/calmodulin-dependent protein kinase type II (CaMKII) and NMDA-type glutamate receptor (NMDAR) are neuronal proteins involved in learning and memory. CaMKII binds to the NR2B subunit of NMDAR in more than one mode, a stable association involving a noncatalytic site on CaMKII and an enzyme-substrate mode of interaction by its catalytic site. The latter binding results in phosphorylation of serine-1303 on NR2B. We have investigated this binding by studying the kinetics of phosphorylation of synthetic peptides harboring nested sequences of the phosphorylation site motif. We find that residues 1292-1297 of NR2B enhance the affinity of the catalytic site-mediated binding of CaMKII to the minimal phosphorylation site motif, 1298-1308 of NR2B, as evident from measurements of K(m) values for phosphorylation. However, CaMKII shows decreased affinity towards the closely related NR2A subunit due to an -Ile-Asn- motif present as a natural insertion in the analogous sequence on NR2A.

Amino Acid Sequence↗
PubMed2002

A randomized trial of high-dose interferon alpha-2b, with or without ribavirin, in chronic hepatitis C patients who have not responded to standard dose interferon.

BACKGROUND: Conventional interferon monotherapy fails to achieve virological clearance in most hepatitis C-infected patients. The use of high-dose induction regimens may improve the initial clearance of virus, while the addition of ribavirin appears to improve the rates of sustained response once clearance is achieved. AIM: To compare the efficacy and safety of re-treatment with an induction regimen of high-dose interferon alpha-2b, with or without ribavirin, in chronic hepatitis C patients who have not responded to standard dose interferon monotherapy. METHODS: Previous virological non-responders to standard dose interferon (3-5 MU three times weekly for > or = 12 weeks) were randomized to receive, unblind, either 10 MU interferon alpha-2b daily for 10 days, then 5 MU daily for 74 days, then 5 MU three times weekly for 24 weeks (total 36 weeks) (group A), or the above regimen with the addition of ribavirin, 1000-1200 mg/day, at day 11 (group B). All patients were followed up for 24 weeks after completion of therapy. RESULTS: End of treatment virological response was noted in one of 10 (10%) patients in group A and in eight of 15 (54%) patients in group B (P=0.04). The sole end treatment responder in group A and three in group B relapsed on follow-up. The apparent improvement in response in group B compared to group A nearly reached statistical significance (group B 5/15 vs. group A 0/10; P=0.06). CONCLUSIONS: In this small pilot study, a 36-week high-dose induction interferon monotherapy protocol did not yield sustained responses in previous non-responders to standard dose interferon. However, the same regimen with ribavirin yielded a 33% sustained response rate, nearly reaching statistical significance. The therapy was well tolerated, despite the higher doses of interferon used and the addition of ribavirin. High-dose interferon with ribavirin appears to be a therapeutic option for non-responders to conventional interferon monotherapy.

Adult↗
PubMed2002

Radioprotection, pharmacokinetic and behavioural studies in mouse implanted with biodegradable drug (amifostine) pellets.

PURPOSE: We evaluated the use of a subcutaneously (s.c.) implantable, biodegradable pellet as a drug delivery system for the radioprotector amifostine. MATERIALS AND METHODS: Mice were implanted s.c. with either the custom-made biodegradable amifostine drug pellet or the placebo pellet without amifostine, exposed to cobalt-60 gamma-radiation (bilateral, 1 Gy min(-1), 7-16 Gy), and the 30-day survival rate was monitored. The non-irradiated mouse was used for pharmacokinetic and behavioural tests. RESULTS: Significant radioprotection (85-95% survival) at 10 Gy was observed in the three-amifostine pellet implanted group 3-5 h after implantation. LD50/30 was 7.97, 8.74 and 16.64 Gy for the control, three-placebo pellet (dose reduction factor, DRF=1.10, p<0.01), and three-amifostine pellet (DRF=1.79, p<0.01) groups respectively in mouse exposed to radiation 2h after implantation. Radioprotection at 12 Gy was observed up to 4h after s.c. amifostine administration and up to 3h after implantation. Pharmacokinetic data revealed that the three-amifostine pellet group had sustained blood WR-1065 levels at 2 h after implantation, in contrast to the reported sharp peak at 30 min for s.c. administration. Although locomotor activity was significantly reduced (p<0.01) in the amifostine pellet group, the onset of the locomotor decrement was delayed as compared with groups that received 400 and 750 mg kg(-1) s.c. amifostine. CONCLUSIONS: Amifostine in biodegradable implant was effective. The radioprotection observed was comparable between conventional s.c. administration of the drug and implantation. Pharmacokinetic data and locomotor activity suggest that the implantation was beneficial though radioprotection data warrants formulation improvements in implants.

Amifostine↗
PubMed2001

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls in human tissues, meat, fish, and wildlife samples from India.

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and non- and mono-ortho-substituted polychlorinated biphenyls (dioxin-like PCBs) were measured in tissues of humans, fishes, chicken, lamb, goat, predatory birds, and Ganges River dolphins collected from various locations in India. PCDDs/DFs were found in most of the samples analyzed with the liver of spotted owlet containing the highest concentration of 3,300 pg/g, fat wt. 2,3,7,8-Substituted PCDDs and PCDFs were found in human fattissues at concentrations ranging from 170 to 1,300 pg/g, fat wt. Concentrations of PCDDs were generally greaterthan those of PCDFs in human tissues, fishes, animal fat, and dolphin. Among fishes, meat, and wildlife samples analyzed, concentrations of PCDDs/DFs were found in the following order: country chicken < goat/lamb fat < fishes < river dolphins < predatory birds. Hepta-CDDs and OCDD were the major PCDD homologues found in humans, fishes, meat products, and dolphins. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents of PCDDs/DFs were greater than those of PCBs in selected fish, dolphin, and human samples. To our knowledge, this is the first report of PCDDs and PCDFs in human tissues, fishes, meat, and wildlife collected from India.

Adult↗