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Biomedical subjects

A Gupta

Publications and source records attributed to A Gupta.

At least 703 records · Page 39Linked to original sources
PubMed1992

Binding of oligopeptides to d-AGATCTAGATCT and d-AAGCTTAAGCTT: can tryptophan intercalate in DNA hairpins?

The interactions of three tryptophan-containing peptides, KWK, KGWK tert-butyl ester, and KGWGK, with two self-complementary dodecamers of the same base composition but different sequence were studied by UV, CD, and fluorescence spectroscopy. The oligonucleotides, d-AGATCTAGATCT and d-AAGCTTAAGCTT, contain tandem repeats of the recognition site for the restriction enzyme BglII in the former and HindIII in the latter. Thermal transition data in dilute solutions and in 0.01 M NaCl indicate these dodecamers to be present in hairpin forms. Binding of peptides to these hairpins was followed by tryptophan fluorescence quenching titrations at 10 mM Na+; the data suggest intercalation of the indole ring. The association constants for the peptide-oligonucleotide (PN) complexes are an order of magnitude higher (10(5) M) than those reported with polynucleotides [10(4) M; Rajeswari et al. (1987) Biochemistry 26, 6825]. The pentapeptide, KGWGK, discriminates between BglII and HindIII sequences with higher affinity for the HindIII dodecamer. The CD maximum of KGWGK, at 220 nm, is drastically diminished upon interaction with oligonucleotides. The ellipticity at 220 nm is halved at 10 times less P/N ratio with the HindIII dodecamer than the BglII dodecamer, suggesting stronger binding to the HindIII dodecamer. The results are discussed in terms of two different modes of binding of oligopeptides to the DNA hairpins.

Amino Acid Sequence↗
PubMed1992

Amplification and rearrangement of a prokaryotic metallothionein locus smt in Synechococcus PCC 6301 selected for tolerance to cadmium.

Metal-tolerant cyanobacteria have been isolated from metal-polluted aquatic environments and also selected in culture, but no genes which confer metal tolerance have been described. To investigate the possibility that amplification of a prokaryotic metallothionein gene (smtA), or rearrangement of the smt locus, could be involved in the development of Cd tolerance in Synechococcus PCC 6301, Cd-tolerant lines were selected by stepwise adaptation of a Synechococcus culture. An increase in smtA gene copy number and the appearance of unique additional smtA restriction fragments (both larger and smaller) were detected in these tolerant lines (tolerant to 0.8 microM Cd, 1.3 microM Cd and 1.7 microM Cd). Stepwise adaptation was repeated by using a culture of Synechococcus PCC 6301 inoculated from a single plated colony to obtain four new lines (tolerant to 1.4 microM Cd, 1.8 microM Cd, 2.6 microM Cd and 3.2 microM Cd). Amplification of the smtA gene and development of unique smtA restriction fragments (larger and smaller) were once again detected in these tolerant lines. Amplification and rearrangement of the smt locus were only detected in the seven Cd-tolerant lines, with no evidence of amplification or rearrangement in the non-tolerant lines from which they were derived. As a control, another gene, psaE, was also monitored in these cell lines. There was no evidence of amplification or rearrangement of psaE in the non-tolerant or any of the Cd-tolerant lines.

Base Sequence↗
PubMed1992

Nonischemic intussusception in childhood.

The classical presentation of intussusception consisting of severe abdominal pain, bloody stool, and a palpable abdominal mass leads to the correct diagnosis in majority of the patients. However, an atypical presentation often results in a delayed diagnosis as is commonly seen in nonischemic intussusception. The nonischemic intussusception is a distinct clinical entity that is characterized by a long history of less severe symptoms commonly noticed in older children. The incidence of diarrhea in this group is higher than in the acute variety of intussusception. This variant of intussusception requires a high degree of suspicion for the diagnosis in atypical clinical presentation. The present study summarises our experience treating 31 such cases of nonischemic intussusception during a period of 25 years from 1966 to July 1990.

Child↗
PubMed1992

Spinal or epidural anaesthesia for elective caesarean section? A Swedish experience.

Ninety seven women undergoing elective lower segment caesarean section were randomly divided into two groups, group 1 received spinal anaesthesia with hyperbaric bupivacaine and group 2 received mepivacaine 20 mg/ml with adrenaline 5 microg/ml via an epidural catheter. All patients were given a preload of Ringer acetate and Macrodex prior to onset of anaesthesia. Ephedrine 5 mg was given if the systolic blood pressure fell below 100 mmHg. There was a small (<30%) but significant (P<0.01) fall in blood pressure in both groups of women. Six women in the epidural group required supplemental analgesics during the operation compared to only 1 patient in the spinal group (P<0.01). Muscle relaxation was judged to be inadequate in 3 patients in the spinal group and in 5 patients in the epidural group. One patient in the spinal group had a characteristic post-spinal headache lasting 3 days. The injection-delivery time was shorter (P<0.01) in the spinal group compared to the epidural group. The Apgar scores at 1 and 5 min were similar in both groups. The results from our study suggest that spinal anaesthesia is a good alternative to epidural anaesthesia for elective caesarean section. A fall in blood pressure, which is equally possible in both groups of patients, should be prevented by adequate fluid preload and treated immediately by intravenous ephedrine.

Journal Article↗
PubMed1992

Natural course of intraocular pressure after cataract extraction and the effect of intracameral carbachol.

Intraocular pressure (IOP) is known to increase after intracapsular cataract extraction, extracapsular cataract extraction (ECCE), and ECCE with intraocular lens (IOL) implantation. Many pharmacological agents have been used to prevent this IOP rise. We conducted a two-phase, randomized, prospective study to evaluate the natural behavior of IOP after cataract surgery and the effect of intraoperative intracameral carbachol on it. In phase 1, 102 cases were randomly assigned to three groups for recording IOP at 24, 48, or 72 hours after ECCE. The IOP at 24 (mean 20.3 mm Hg) and 48 hours (mean 22.3 mm Hg) was significantly higher than the preoperative IOP (mean 16.1 mm Hg); 26.3% of cases in group 1A (24 hours) and 44.1% of cases in group 1B (48 hours) had IOPs greater than or equal to 25 mm Hg. In phase II, intracameral carbachol (0.01%) was used in 30 cases of ECCE and in 30 cases of ECCE with IOL implantation. The IOP at 24 hours (mean 16.3 mm Hg) was not significantly higher than the preoperative IOP and only 11.6% of the cases had IOPs greater than or equal to 25 mm Hg. The mean IOP at 24 hours without carbachol was significantly higher than the mean IOP at 24 hours with it. There was no statistically significant difference between IOP in the two groups one week after surgery.

Adult↗
PubMed1992

The feasibility of studying drug-induced acute hepatitis with use of Medicaid data.

To determine the feasibility of the use of Medicaid data to study drug-induced acute liver disease, we reviewed the medical records of 414 patients receiving Medicaid, age 20 or older, with an ICD-9-CM inpatient billing code consistent with acute hepatitis. Of the patients whose records were reviewed, 15.9% were alcoholics, 31.9% had acute hepatitis A or B, 13.5% were intravenous drug users, 8.2% had acute cholecystitis or choledocholithiasis, and 4.1% had received a blood transfusion within the previous 6 months. No diagnosis of liver disease was found in 10.6% of the patients, and 5.7% had chronic liver disease. Of the 169 patients with idiopathic acute liver disease identified, many had very mild liver disease and were hospitalized for reasons other than liver disease. We conclude that Medicaid billing data has high reliability and validity for the diagnosis of acute liver disease. However, primary medical records are essential for the study of drug-induced hepatitis, to be able to exclude other causes of liver disease, and to obtain information not included in the computer data.

Acute Disease↗
PubMed1992

Drug-induced hypothyroidism: the thyroid as a target organ in hypersensitivity reactions to anticonvulsants and sulfonamides.

Inherited defects in detoxification of reactive metabolites of drugs predispose patients to "hypersensitivity" reactions. Covalent interaction of metabolites with cell macromolecules leads to cytotoxic and immunologic outcomes, manifested clinically by multisystem syndromes with variable organ involvement. Hypothyroidism developed in 5 of 202 patients (age range, 1 to 81 years) we investigated for hypersensitivity reactions to anticonvulsants or sulfonamides shortly after their reaction. None had previous personal or family histories of autoimmune disease. All had low thyroxine levels, elevated levels of thyroid stimulating hormone, and autoantibodies including antimicrosomal antibodies. Patients were 2 to 18 years of age at presentation, and two were male. All returned to a euthyroid state within a year of presentation, and all remain well. The demographics, clinical presentation, and course of the patients is atypical of idiopathic lymphocytic thyroiditis. We investigated the pathogenesis of thyroid toxicity using the hydroxylamine metabolite of sulfamethoxazole as a model. The hydroxyalmine was toxic to thyroid cells in vitro, which did or did not express thyroid peroxidase activity, whereas the parent sulfonamide was toxic only to cells with active thyroid peroxidase. The purified enzyme converted sulfamethoxazole to the hydroxylamine. Formation of reactive drug metabolites by thyroid peroxidase in a host who is genetically unable to detoxify the metabolites may lead directly to cytotoxicity. Covalent binding to macromolecules, including thyroid peroxidase, also may lead to expression of neoantigens and formation of autoantibodies. Patients who have sustained hypersensitivity reactions to drugs should be investigated for possible involvement of the thyroid.

Adolescent↗
PubMed1992

Total nodal radiation in progressive sarcoidosis. Case report.

The subject of this article is a patient with sarcoidosis with neurological involvement, who failed to respond to high dose steroid therapy and cyclophosphamide. Low doses (20 Gy) of total nodal and craniospinal irradiation resulted in an excellent response, the patient being alive and in good health 3 years after irradiation without any further steroid therapy.

Adult↗
PubMed1992

Hand assessment.

Health care personnel caring for a patient with an injured hand must fully understand the functional and structural anatomy as well as assessment methods involved with such an injury. This article will overview the importance of conducting a complete history and thorough examination of the hand as well as proper documentation procedures.

Hand Injuries↗