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Biomedical subjects

R Gupta

Publications and source records attributed to R Gupta.

At least 397 records · Page 22Linked to original sources
PubMed1997

RNA splicing ligase activity in the archaeon Haloferax volcanii.

At least two separate enzymes, an endonuclease and a ligase, appear to be involved in tRNA splicing in halophilic archaea. We have identified and partially characterized a splicing ligase activity in cell extracts of Haloferax volcanii that can ligate deproteinized exon products generated in a separate endonuclease reaction. As in vitro transcribed partial intron-deleted derivative of H. volcanii elongator tRNA(Met) is used as substrate for the endonuclease. The ligase can also join the two exons that are independently eluted from the gels. This ligase activity is observed at a range (50 mM to 2.8 M) of monovalent cations in the assays, but is abolished when the enzyme preparations are depleted of the monovalent cations. In contrast, H. volcanii splicing endonuclease has been reported to require divalent cations and is inhibited by monovalent cations. Our endonuclease assays confirm these reports, and also show that the endonuclease is not permanently inactivated even in high monovalent cation containing extracts. The ligase activity in the extracts does not appear to require any divalent cation or exogenously added source of energy or phosphate.

Archaea↗
PubMed1997

Expression of mutated Nck SH2/SH3 adaptor respecifies mesodermal cell fate in Xenopus laevis development.

Nck is a widely expressed SH2/SH3 adaptor protein containing one SH2 and three SH3 domains. Although Nck is assumed to mediate the formation of protein-protein complexes during signaling, little is currently known about its specific function. We have constructed a series of Nck SH3 and SH2 domain mutants, expressed them in Xenopus laevis embryos, and monitored injected embryos for developmental abnormalities. This approach allows correlation of developmental phenotypes with the presence or absence of specific Nck protein-binding domains. We show that microinjection of RNA-encoding Nck with an inactivating mutation in the third SH3 domain (NckK229) into dorsal blastomeres of early embryos caused anterior truncation with high frequency, and membrane localization of both the first and second SH3 domains together was sufficient to induce this anterior-truncation phenotype. Molecular marker analysis of explants revealed that the expression of NckK229 ventralized dorsal mesoderm. Lineage tracing experiments demonstrated that the expression of Nck K229 in dorsal blastomeres affected the migratory properties of mesoderm cells in gastrulation and led to the adoption of a more posterior fate. These data suggest that protein(s) that bind the first and second SH3 domains of Nck can affect the response to signals that establish dorso-ventral patterning, and that protein(s) that bind the third SH3 domain antagonize the ventralizing effect of the first two SH3 domains.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Activation of Pak by membrane localization mediated by an SH3 domain from the adaptor protein Nck.

BACKGROUND: The adaptor protein Nck consists of three Src homology 3 (SH3) domains followed by one SH2 domain. Like the Grb2 adaptor protein, which is known to couple receptor tyrosine kinases to the small GTPase Ras, Nck is presumed to bind to tyrosine-phosphorylated proteins using its SH2 domain and to downstream effector proteins using its SH3 domain. Little is known, however, about the specific biological function of Nck. The Pak family of serine/threonine kinases are known to be activated by binding to the GTP-bound form of Cdc42 or Rac1, which are small GTPases of the Rho family that are involved in regulating the organization of the actin cytoskeleton. RESULTS: We present evidence that Nck can mediate the relocalization and subsequent activation of the Pak1 kinases. We show that Nck associates in vivo with Pak using the second of its three SH3 domains, and that localization of this individual Nck SH3 domain, or of Pak kinase itself, to the membrane results in activation of Pak and stimulation of downstream mitogen activated protein kinase cascades. Activation of downstream signaling by the membrane-localized Nck SH3 domain is blocked by a kinase-inactive mutant form of Pak1. CONCLUSION: These results demonstrate that localization of Pak1 to the membrane in the absence of other signals is sufficient for its activation, and imply that the Nck adaptor protein could function to link changes in tyrosine phosphorylation of cellular proteins to the Cdc42/Pak signaling pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Predictors of arterial thrombosis after diagnostic cardiac catheterization in infants and children randomized to two heparin dosages.

Arterial thrombosis is the most frequent major complication of percutaneous arterial catheterization in children. We prospectively studied the effect of randomized dosage of heparin, 50 IU/kg-group I and 100 IU/kg-group II, on the incidence of arterial thrombosis in 366 children and analysed the various factors which may influence the occurrence of this complication. The age of patients ranged from 17 d to 11 yr (mean age 39.5 +/- 40.9 mo) and mean weight was 11.2 +/- 7.8 kg (range 3 to 39 kg). The incidence of arterial thrombosis was 9.8% in group I and 9.3% in group II (P = NS). There was no statistical difference in precatheterization and procedure variables in the two groups and also in the group with absent pulse (n = 35) to the group with pulse present post cath (n = 331). There were 24.9% infants in our study and 14.3% of these had arterial thrombosis. The loss of pulse was more often seen with more number of attempts at arterial puncture (P < 0.001), absence of back bleed at the end of the procedure (P < 0.001), and increased duration of catheterization (P < 0.01). Use of larger sheath size in a given weight and body surface area of children increased incidence of arterial thrombosis. The administration of heparin 50 IU/kg was equally efficacious to heparin 100 IU/kg. Of the patients with arterial thrombosis, 23 responded with intravenous heparin and 12 needed streptokinase. There was no bleeding or haematoma. Thus our study shows that less attempt for arterial puncture, use of smaller sheath size, maintaining shortest procedure time and ensuring back bleed minimises incidence of arterial thrombosis post catheterization.

Anticoagulants↗
PubMed1997

Leishmania major: molecular cloning, sequencing, and expression of the heat shock protein 60 gene reveals unique carboxy terminal peptide sequences.

Heat shock proteins (HSP) in the size range of M(r) 60,000 are major targets of the immune response in vivo. The leishmania heat-inducible proteins of M(r) 65-67,000 are expressed at relatively high levels in infected macrophages (Infection and Immunity 1993, 61, 3265-3272) and may be important targets of the host response. To facilitate further studies concerned with these proteins, the HSP60 gene of Leishmania major was cloned, sequenced, and expressed. A lambdaEMBL-3 L. major genomic library was screened with a PCR-generated DNA probe derived from a highly conserved region of the leishmania HSP60 gene. A single clone that hybridized strongly was characterized. Sequence analysis revealed an open reading frame of 1770 bp encoding a putative polypeptide of 589 amino acids with a predicted size of M(r) 64,790 and with the highest degree of amino acid sequence similarity (56%) to HSP60 from Trypanosoma cruzi. Less extensive amino acid sequence similarity (48%) was observed between that leishmania HSP60 and the corresponding human protein. Notably, significant regions of sequence dissimilarity between the leishmania and human proteins were identified principally within the carboxy-terminal regions of the proteins. The entire coding region of the leishmania HSP60 gene was subcloned into the pET-3a vector and expressed in Escherichia coli. Purified recombinant protein was used to examine sera from patients with tegumentary leishmaniasis from Colombia for the presence of antibodies to HSP60. Unlike sera from healthy, uninfected controls, sera from patients reacted strongly with recombinant leishmania HSP60. This recognition had specificity in that these same sera showed little or no reactivity with either recombinant mycobacterial HSP65 or recombinant human HSP60. These findings indicate that patients with tegumentary forms of leishmaniasis have humoral responses to leishmania HSP60. Further studies of this protein will clarify its importance as a target of the immune response and as a potential antigen for serodiagnosis.

Amino Acid Sequence↗
PubMed1997

Oscillatoria anguistissima: a promising Cu2+ biosorbent.

Oscillatoria anguistissima rapidly adsorbs Cu2+ from aqueous solution. The adsorption of Cu2+ followed Freundlich Isotherm, and the amount of Cu2+ removed from solution increased with increasing Cu2+ concentration. The adsorption is pH dependent, and maximum Cu2+ removal occurs at pH 5. Of the various pretreatments, HCl treatment of the biomass increased the capacity for Cu2+ removal. Presence of Mg2+ and Ca2+ resulted in decline in the Cu2+ adsorption capacity of Oscillatoria cells. This species could also effectively remove Cu2+ from mine water containing 68.4 microg/ml of Cu2+ at pH 3.45.

Adsorption↗
PubMed1997

Outcome of polyarteritis nodosa in northern India.

Over the last 10 years, 17 patients (13 males and 4 females) diagnosed as having classical polyarteritis nodosa (PAN) were treated and followed up in the rheumatology clinic of our institute. The median age and duration of symptoms at presentation were 29 years (range 13-59) and 9.5 months, respectively. Patients presented with the typical clinical picture of classical PAN. The diagnosis was established with the help of an aortogram (7/10), sural nerve biopsy (7/8), muscle biopsy (5/7) and renal biopsy (3/4). For reasons not known, none of the 17 patients was HBsAg positive. Patients were treated with a combination of oral prednisolone (1 mg/kg per day) for 6 weeks, which was slowly tapered off over 6 months, and monthly intravenous cyclophosphamide pulses (15 mg/kg) for the first 6 months, followed by 3-monthly pulses for a total of 2 years. Remission was achieved in 14 patients after a median of 5 months of treatment. Remission was stable for a median of 5 years of follow-up. Three patients did not respond well and died within 6 months of diagnosis. The causes of death in these were intracerebral haemorrhage in one patient and gastrointestinal bleeding in two patients. This experience is in accord with the reported literature that classical PAN is mostly a monophasic disease with either an excellent response to the appropriate immunosuppressive therapy and a long remission or a downhill course culminating in death. A chronic course is rare.

Administration, Oral↗
PubMed1997

Results of surgical repair of full-thickness tears of the rotator cuff.

Shoulder pain is often caused by pathologic conditions of the rotator cuff. Many investigators have studied the factors that influence the outcome after rotator cuff repair. This article reviews the different factors and the various methods of reporting outcome after shoulder surgery.

Adult↗
PubMed1997

Growth inhibition of B-cell precursor acute lymphoblastic leukemia cell lines by monocytes: a role for prostaglandin E2.

Leukemic cell lines have proven invaluable in the molecular analysis of recurring chromosomal translocations but the optimal methods for leukemia cell line establishment are unknown. During in vitro culture, most B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells die within 1 week at least partially mediated by inhibitors elaborated by peripheral blood mononuclear cells (PB MNCs) present within the leukemia sample. In experiments reported here, cyclooxygenase inhibitors (indomethacin and meclofenamic acid) blocked the PB MNC-mediated inhibition of BCP-ALL proliferation. Also, prostaglandin E2 (PGE2) was detected in supernatants from PB MNC cultures. When PGE2 was mixed directly with BCP-ALL cells, proliferation decreased significantly. Under the culture conditions used, PB MNCs secreted PGE2 which appears to be one of the major inhibitors of BCP-ALL growth in vitro.

Adult↗
PubMed1997

Role of iron and iron chelation therapy in oxygen free radical mediated tissue injury in an ascending mouse model of chronic pyelonephritis.

The contribution of iron towards the free radical generation leading to renal tissue damage was assessed using a non-obstructive ascending mouse model for chronic pyelonephritis. The parameters studied include luminol dependent chemiluminescence (LDCL), histopathology and some biochemical investigations. We found that iron enhanced the renal tissue damage and led to renal scarring, and end point in chronic renal inflammation, irrespective of the bacterial strain studied. In addition a role of iron chelation therapy as a treatment for chronic renal inflammation is also suggested.

Animals↗
PubMed1997

Focal segmental glomerulosclerosis in one of two "en bloc" pediatric transplanted kidneys.

Focal segmental glomerulosclerosis (FSGS) is thought to have several causes, including hypertension, reduction of nephron mass, or immunologic processes. Experimental studies have underlined the role of glomerular adaptation to capillary pressure in the growing kidney after partial nephrectomy. We report here the occurrence of FSGS in one of two "en bloc" pediatric kidneys transplanted in an adult recipient. One of the kidneys sustained early ureteral obstruction requiring reoperation and subsequently developed pathological changes on biopsy consistent with FSGS, whereas the mate kidney did not, although both kidneys grew at equal rates and to equivalent sizes.

Adult↗
PubMed1997

Hypocholesterolaemic effects of Terminalia arjuna tree bark.

Diet-induced hyperlipidaemic rabbits were given 50% ethanolic extract of Terminalia arjuna tree bark in doses of 100 mg/kg (Group B, n = 6) and 500 mg/kg (Group C, n = 6) and compared with controls (Group A). At 60 days of intervention in Groups A, B and C mean +/- S.E.M. total cholesterol was 574 +/- 61, 320 +/- 29 and 217 +/- 44 mg/dl, respectively (P < 0.01); LDL cholesterol was 493 +/- 57, 271 +/- 30 and 162 +/- 44 mg/dl (P < 0.01); HDL cholesterol was 59 +/- 7, 36 +/- 3 and 35 +/- 4 mg/dl (P = n.s.); triglyceride was 108 +/- 13, 67 +/- 6 and 101 +/- 26 mg/dl (P = n.s.); cholesterol/HDL ratio was 10.1 +/- 1.3, 9.2 +/- 1.1 and 6.1 +/- 1.0 (P = n.s.); and LDL/HDL ratio was 8.7 +/- 1.3, 7.8 +/- 1.1 and 4.5 +/- 1.0 (P < 0.01). The extract did not adversely affect biochemical tests of liver and renal function and haematological parameters.

Animals↗
PubMed1997

Focal corneal decompensation caused by an anterior capsulotomy remnant.

Capsule contraction syndrome, an infrequent but sight-compromising condition, can usually be managed by a neodymium:YAG (Nd:YAG) anterior capsulotomy. The anterior capsule can be split from the visual axis to the periphery with multiple spokes. In this patient, however, these spokes closed, leaving the small anterior capsulotomy indistinguishable from its pre-capsulotomy appearance. A subsequent Nd:YAG laser circumcision of the thickened capsulotomy margin restored the patient's sight. The excised capsular doughnut fell into the anterior chamber angle and resulted 34 months later in localized corneal decompensation. Removal of the capsular remnant markedly improved the corneal changes. The experience from this case suggests that multiple Nd:YAG relaxing incisions may be a safer way to manage capsule contraction syndrome than complete circumcision of the anterior capsule. If the latter approach is taken, the capsular remnant should not be cut completely free of the anterior capsule.

Anterior Chamber↗
PubMed1997

Prevalence and determinants of coronary heart disease in a rural population of India.

BACKGROUND: The prevalence and determinants of coronary heart disease (CHD) have been inadequately studied in rural areas of developing countries. METHODS: Entire communities were surveyed in randomly selected villages in Rajasthan, India. A physician-administered questionnaire, physical examination, and electrocardiogram (ECG) were performed on 3148 adults > or = 20 years of age (1982 males, 1166 females). Fasting blood samples for determination of lipids were obtained from 202 males and 98 females. Prevalence of coronary risk factors--smoking, hypertension, sedentary life-style, obesity, and hypercholesterolemia--was determined. CHD was diagnosed on basis of past documentation, response to WHO-Rose questionnaire, or changes in ECG. Three methods were used: (a) documentation, history, and ECG criteria, (b) ECG-Q, ST, or T changes, and (c) presence of Q waves. RESULTS: Coronary risk factors: smoking was present in 51% males and 5% females, hypertension (> or = 140/90 mmHg) in 24% males and 17% females, hypercholesterolemia (> 200 mg/dl) in 22%, diabetes history in 0.2%, and irregular physical activity or sedentary habits in 85%. Other risk factors were lack of formal education in 44%, obesity (body-mass index > or = 27 kg/m2) in 6% and truncal obesity (waist-hip ratio > or = 0.95) in 5%. The prevalence of CHD (clinical + ECG criteria) was 3.4% in males and 3.7% in females. According to ECG criteria only, it was 2.8% in males and 3.3% in females and according to Q-waves only, it was 1.6% in males and 0.9% in females. Multivariate logistic regression analysis showed that age and smoking in males and age and systolic blood pressure in females were associated with higher prevalence of Q-wave CHD. In males, higher educational level and prayer habit were associated with lower prevalence. CONCLUSIONS: Prevalence of CHD in this rural community is higher than in previously reported Indian studies. Smoking, hypertension, and sedentary lifestyle have high prevalence. Significant determinants of CHD are increasing age and smoking while education and prayer-habit are protective.

Adult↗
PubMed1997

Chromosomal location and expression of the single-copy gene encoding high-mobility-group protein HMG-I/Y in Arabidopsis thaliana.

A cDNA encoding the HMG-I/Y protein from Arabidopsis thaliana has been isolated and characterised by nucleotide sequencing. The 903 bp cDNA contains a 612 bp open reading frame encoding a protein of 204 amino acid residues showing homology to HMG-I/Y proteins from other plant species. The protein contains four copies of the 'AT-hook' motif which is involved in binding A/T-rich DNA. Southern blotting showed that the HMG-I/Y gene was present in a single copy in the Arabidopsis genome. The gene was localised to the top of chromosome 1 by RFLP analysis of F8 recombinant inbred lines. Northern blotting showed that the gene was expressed in all organs examined, with the highest expression in flowers and developing siliques.

Amino Acid Sequence↗
PubMed1997

The single-copy gene encoding high-mobility-group protein HMG-I/Y from pea contains a single intron and is expressed in all organs.

The coding and 3'-downstream regions of the gene encoding the high mobility group protein HMG-I/Y from pea have been isolated, sequenced and characterised. A 795 bp pea genomic fragment containing the coding region of the pea HMG-I/Y gene with a single intron of 201 bp was isolated by PCR. The gene encodes a protein of 197 amino acid residues with four copies of the AT-hook DNA-binding motif encoded by exon 2. Southern blot analysis on genomic DNA revealed the presence of a single copy of the HMG-I/Y gene in the haploid genome. The pea HMG-I/Y gene is expressed in all organs of pea including roots, stems, leaves, flowers, tendrils and developing seeds, as determined by northern blot analysis.

Amino Acid Sequence↗
PubMed1997

Familial and social influences on juvenile gambling behavior.

Social learning theory maintains that individuals model, learn and maintain behaviors that are observed, appealing and reinforcing. As such, parents and family members can often serve as significant models for gambling. Four hundred and seventy seven children between the ages of 9 and 14 completed a questionnaire inquiring about their gambling activities, including where and with whom gambling occurs, as well as information concerning their perceptions of their own gambling behavior. Results indicate that 86% of children who gamble regularly reported gambling with family members. Fifty-three percent of students who gambled within the previous 12 months reported gambling with their siblings, 40% gambled with their parents, 46% gambled with other relatives, and 75% gambled in their own homes. Students' responses also indicated gambling with their friends (75%), gambling alone (18%), and with strangers (8%). As children's age increases they tend to gamble more at friend's homes and at school. Prevalence rates indicated that 81% of the total sample had gambled at one point in their lives and 52% of those children reported gambling once a week or more. Eleven percent reported that gambling makes them feel important, 27% feel they gamble more than they desire to do so, and only 10% of the grade 8 students fear being caught gambling, suggesting gambling activities to be a socially acceptable behavior. Several clinical and research questions are addressed.

Journal Article↗