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Biomedical subjects

S Roy

Publications and source records attributed to S Roy.

At least 739 records · Page 41Linked to original sources
PubMed1983

A continuous spectrophotometric assay for Escherichia coli alanyl-transfer RNA synthetase.

A new continuous spectrophotometric assay is demonstrated for Escherichia coli alanyl-tRNA synthetase. It involves beta-gamma adenylyl imidophosphate as a substitute for ATP in the pyrophosphate exchange reaction. The net conversion of beta-gamma adenylyl imidophosphate to ATP can be linked to NADP reduction by hexokinase and glucose-6-P dehydrogenase catalyzed reactions, which can be monitored at 340 nm. This assay can be extended to other aminoacyl-tRNA synthetases which can use beta-gamma nonhydrolyzable analogs of ATP as an ATP substitute.

Adenylyl Imidodiphosphate↗
PubMed1983

Methods to determine success of attempts to terminate early gestation pregnancies with prostaglandin vaginal suppositories.

One-hundred subjects received vaginal suppositories containing prostaglandin analogues in order to terminate their pregnancies of 49 days gestation or less. This non-surgical method was successful in 61 subjects, failed in 35 subjects and four subjects were lost to follow-up. Success of prostaglandin therapy cannot be predicted using pretreatment clinical parameters, pretreatment serum beta-hCG levels, or the passage of tissue from the vagina based upon history obtained from the subject. The passage of tissue histologically identified as of fetal origin is a definitive way to determine the success of pregnancy termination but the passage of tissue obtained by history is not. Of the 61 subjects in whom the prostaglandin suppositories were a success, 56 (92%) had a beta-hCG level day 7 +/- 2 following treatment which was 15% or less than the pretreatment value and 5 had beta-hCG levels which were more than 15% of the pretreatment value. All subjects with beta-hCG levels 5 to 9 days after the abortion that were less than 15% of the pretreatment concentrations had a successful termination. Of 35 subjects in whom the prostaglandin suppositories were unsuccessful, 26 had a beta-hCC level 7 +/- 2 days following treatment which was greater than the pretreatment level and 9 had beta-hCG levels less than the pretreatment value. The results of this study indicate that when prostaglandin vaginal suppositories are used to terminate early gestations, if there is no decline in beta-hCG levels 7 +/- 2 days following treatment, the pregnancy should be terminated by another method.

Abortion, Induced↗
PubMed1983

Specificity of receptors for leukotrienes A4, B4, C4, D4, E4 and histamine on the guinea-pig lung parenchyma. Effect of FPL-55712 and desensitization of the myotropic activity.

The novel metabolites of arachidonic acid, leukotriene (LT) A4, B4, C4, D4 and E4 have potent myotropic activity on guinea-pig lung parenchymal strip in vitro. The receptors responsible for their action were characterized using desensitization experiments and the selective SRS-A antagonist, FPL-55712. During the continuous infusion of LTB4, the tissues became desensitized to LTB4 but were still responsive to histamine, LTA4, LTC4, LTD4 and LTE4. When LTD4 was infused continuously, the lung strips contracted to LTB4 and histamine but were no longer responsive to LTA4, LTC4, LTD4 and LTE4. Furthermore, FPL-55712 (10 ng ml-1 - 10 ug ml-1) produced dose-dependent inhibitions of LTA4, LTC4, LTD4 and LTE4 without inhibiting the contraction to LTB4 and histamine. On the basis of these results, it appears that the guinea-pig lung parenchyma may have one type of receptor for LTB4 and another for LTD4; LTA4, LTC4 and LTE4 probably act on the LTD4 receptor.

Animals↗
PubMed1983

Ethanol effects on synaptic glutamate receptor function and on membrane lipid organization.

The enhancement of L-glutamic acid binding activity of brain synaptic membranes by low concentrations of ethanol (less than 50 mM) and the decrease in binding at high concentrations (greater than 100 mM) was not due to a direct action by ethanol on the glutamate binding protein. Biphasic effects of ethanol on membrane protein complexes such as the glutamate binding sites might be the result of biphasic changes in membrane lipid organization. Low ethanol concentrations (0.1-4.0 mM) were shown to decrease fatty acid chain motion detected by the EPR probe 5-doxyl stearic acid, whereas high concentrations (greater than 400 mM) increased lipid motion in egg phosphatidylcholine liposomes. The function of the L-glutamate receptor-ion channel complex in the presence of ethanol was also determined by measuring the changes in thiocyanate (SCN-) influx brought about by L-glutamate or ethanol. A low concentration of ethanol (9.4 mM) diminished the L-glutamate-induced depolarization of synaptic membranes, while a high concentration (93.7 mM) increased the passive SCN-influx and produced a transient overshoot in glutamate-stimulated SCN-flux.

Animals↗
PubMed1983

Clinical experience with pediatric urolithiasis.

Our clinical experience with 47 pediatric patients with stones is reviewed. Surgical therapy was standard with successful stone manipulation in 12 of 13 patients. In 91 per cent of our patients factors causing or predisposing to stone disease were discovered. A thorough metabolic evaluation, including an oral calcium loading test in 20 children, proved to be helpful. A new patient subgroup relating unexplained hematuria to eventual stone formation is described. Our protocol for metabolic evaluation and recommendations for treatment based on the results of such an evaluation are given. We have found the metabolic evaluation of the child with stones meaningful and particularly helpful in planning subsequent therapy for these patients.

Adolescent↗
PubMed1983

NMR study of slowly exchanging imino protons in yeast tRNAasp.

We have monitored the exchange of imino and amino protons by NMR after quick transfer of yeast tRNAAsp in 2H2O solvent. When the concentration of exchange-catalyzing buffer is not too high, one imino proton exchanges considerably more slowly than any other (e.g., 100 hr versus 4 hr for the second-slowest imino proton at 18 degrees C in 15 mM Mg). This provides excellent conditions for identification, by the nuclear Overhauser effect, of the slowest exchanging proton, which we show to be the imino proton of the U-8 . A-14 reverse Hoogsteen tertiary-structure base pair; other slowly exchanging protons are identified as imino protons from A . U-11 and G . psi-13. In preliminary experiments, we find that the exchange of these protons is catalyzed by cacodylate or Tris buffer. The lifetimes of two other imino protons, ca. 10 min at 28 degrees C, are buffer independent. Slowly exchanging amino protons have also been observed. Correlation with the exchange of the uracil-8 imino proton suggests that they may be from adenine-14.

Base Sequence↗
PubMed1983

Perspectives on adverse effects of milks and infant formulas used in infant feeding.

Potential adverse effects of infant formulas and breast milk upon growth are discussed. The author's description of failure to thrive in infants receiving a chloride-deficient formula emphasizes that growth can be affected by the deficiency of nutrients such as chloride. Quality control of the manufacture of infant formulas must be monitored to ensure their safety, since they are used as the sole source of infant nutrition. As the incidence of breast feeding increases, its potential hazards must also be recognized by those who monitor the growth of infants.

Avitaminosis↗
PubMed1983

Evaluation of T lymphocyte subpopulations in children with nephrotic syndrome.

We have evaluated lymphocyte subsets both quantitatively and functionally in children with nephrotic syndrome. Ten children had minimal change nephrotic syndrome (MCNS), seven had focal segmental glomerular sclerosis (FSGS) and four had recovered from MCNS. Two patients with FSGS had decreased OKT4+ cells and a decreased T4/T8 ratio. Patients with active MCNS synthesized significantly less IgM in vitro than did normal subjects (P less than 0.005). In vitro IgG synthesis was significantly decreased in patients with active nephrotic syndrome whether it was due to MCNS or FSGS. Co-culture studies involving lymphocyte subsets suggested that both patients with decreased percentages of T4+ cells had decreased T helper cell activity as well. The results of this study support previous speculation about abnormal immune function in some patients with nephrotic syndrome.

Antibodies, Monoclonal↗
PubMed1983

Reflux nephropathy complicated by acute post-streptococcal glomerulonephritis.

A 7 years old male with severe bilateral vesicoureteral reflux developed acute renal failure without evidence of either infection or obstruction. The diagnosis of acute post-streptococcal glomerulonephritis was confirmed by clinical, serological and histological evaluation. The patient's creatinine clearance decreased from 25 ml/min/1.73 m2 to 10-13 ml/min/1.73 m2 following the acute nephritic episode and chronic dialysis therapy was required thereafter. This patient illustrates that a glomerular etiology should be suspected when acute renal failure occurs in a patient with reflux nephropathy and suggests that the prognosis of acute post-streptococcal glomerulonephritis may be worse in children with pre-existing renal disease.

Acute Disease↗
PubMed1983

A double-blind comparison of a propionic acid derivative (ibuprofen) and a fenamate (mefenamic acid) in the treatment of dysmenorrhea.

A double-blind three-way crossover design in the treatment of dysmenorrhea comparing a propionic acid derivative (ibuprofen) and a fenamate (mefenamic acid) with a placebo showed that both ibuprofen and mefenamic acid are generally superior to placebo. Statistically significant results were obtained in favor of the study drugs over placebo for the pain relief afforded by the treatments (as graded by patients) and the visual analog pain relief score, which not only ranks but also indicates the degree of pain relief as a percentage of total relief (100%). Pairwise comparisons for the ranks found mefenamic acid significantly superior to placebo (P less than .001) and ibuprofen marginally superior to placebo (P less than .06), while the visual analog pain relief scale demonstrated mefenamic acid and ibuprofen superior to placebo (P less than .001 and P less than .01, respectively). For both the patient ranking of pain relief by treatment and the visual analog pain relief scale, the results showed no significant differences between ibuprofen and mefenamic acid. Side effects occurred in 11 ibuprofen cycles, five mefenamic acid cycles, and ten placebo cycles of the 48 cycles with each agent. These were generally of minor severity or importance and were not statistically different. The need for additional analgesics and the ability to pursue normal daily activity were not different for any treatment group. The findings of this study indicate no clinical difference between a propionic acid derivative such as ibuprofen and a fenamate such as mefenamic acid in the treatment of dysmenorrhea.

Adult↗
PubMed1982

Nuclear Overhauser effect study of yeast tRNAVal 1: evidence for uridine-pseudouridine base pairing.

The proton NMR spectrum of yeast tRNAVal 1 has been studied using nuclear Overhauser effect (NOE), including comparison of NOE patterns between purine C8 deuterated and nondeuterated samples. Studies of the downfield region enable us to reliably assign many resonances in the acceptor and D stems. Prominent among these reliable assignments is that of the unusual base pair U psi, which is made here for the first time. Other identifications include GU2, U8-A14, the three AU base pairs of the acceptor stem, and N1 and N3 protons of psi 55.

Base Composition↗
PubMed1982

Procedure for C2 deuteration of nucleic acids and determination of A psi 31 pseudouridine conformation by nuclear Overhauser effect in yeast tRNAPhe.

Nuclear Overhauser effect (NOE) combined with semispecific deuteration provides a general strategy for identification of exchangeable protons in nucleic base pairs, and has been extended to NOEs involving purine C2 protons in tRNA. Deuterated tri-ethyl orthoformate was condensed with 5(4)-amino imidazole 4(5)-carboxamide to yield C2 deuterated hypoxanthine. C2 deuterated hypoxanthine was fed to a purine requiring mutant of yeast and C2 deuterated yeast tRNAPhe was isolated. This C2 deuterated tRNAPhe was used to identify A psi 31 and U8-A14. A psi 31 was found to be bonded through N1H. The utility of C2 deuteration in nucleic acid NMR is thus demonstrated.

Base Sequence↗
PubMed1982

Nuclear overhauser effect study of yeast aspartate transfer ribonucleic acid.

Nuclear Overhauser effect studies are described for yeast tRNAAsp in 0.1 M NaCl, pH 7.0. A primary aim is to develop a general method for attacking the problem of assignment in transfer ribonucleic acids (tRNAs). Previously, we have demonstrated the utility of the nuclear Overhauser effect (NOE) between protons on adjacent base pairs combined with C8 deuterium substitution, by assigning the imino protons of the dihydrouridine stem and the two reverse-Hoogsteen base pairs T54-A58 and U8-A14. Here, we extend that approach to other parts of the molecule. We also describe several NOE-connected patterns for, e:g., m5CG and psi 55 N3H imino protons which may be of general utility. For the first time, a purine-15-pyrimidine-48 base pair (in this case A15-U48) has been assigned. A total of 13 of 25 base pairs from all parts of the molecule and several noninternally bonded imino protons have now been assigned unambiguously. This is a general method for assigning resonances in tRNA and perhaps in all double-stranded nucleic acids. This, and the distance information inherent in NOE measurements, should make NMR more generally applicable to nucleic acids.

Base Sequence↗