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Biomedical subjects

S Dube

Publications and source records attributed to S Dube.

At least 55 records · Page 3Linked to original sources
PubMed1993

Genetic heterogeneity in human T-cell leukemia/lymphoma virus type II.

DNA from the peripheral blood mononuclear cells of 17 different individuals infected with human T-cell lymphoma/leukemia virus type II (HTLV-II) was successfully amplified by the polymerase chain reaction (PCR) with the primer pair SK110/SK111. This primer pair is conserved among the pol genes of all primate T-cell lymphoma viruses (PTLV) and flanks a 140-bp fragment of DNA which, when used in comparative analyses, reflects the relative degree of diversity among PTLV genomes. Cloning, sequencing, and phylogenetic comparisons of these amplified 140-bp pol fragments indicated that there are at least two distinct genetic substrains of HTLV-II in the Western Hemisphere. These data were confirmed for selected isolates by performing PCR, cloning, and sequencing with to 10 additional primer pair-probe sets specific for different regions throughout the PTLV genome. HTLV-II isolates from Seminole, Guaymi, and Tobas Indians belong in the new substrain of HTLV-II, while the prototype MoT isolate defines the original substrain. There was greater diversity among HTLV-II New World strains than among HTLV-I New World strains. In fact, the heterogeneity among HTLV-II strains from the Western Hemisphere was similar to that observed in HTLV-I and simian T-cell lymphoma/leukemia virus type I isolates from around the world, including Japan, Africa, and Papua New Guinea. Given these geographic and anthropological considerations and assuming similar mutation rates and selective forces among the PTLV, these data suggest either that HTLV-II has existed for a long time in the indigenous Amerindian population or that HTLV-II isolates introduced into the New World were more heterogeneous than the HTLV-I strains introduced into the New World.

Amino Acid Sequence↗
PubMed1992

Adverse effects of oral amiodarone therapy.

Oral amiodarone was administered to 38 patients (25 males, 13 females) with mean age of 43.6 years. Ventricular and supraventricular arrhythmias were present in 30 and 8 patients respectively. Amiodarone was given as 400-1200 mg/day for 1-2 weeks as loading dose and then it was maintained as 100-600 mg/day. The mean duration of therapy was 12.4 months. Adverse effects were noted in 21 (55.3%) cases. The commonest adverse effects observed were asymptomatic corneal microdeposits followed by gastrointestinal, cardiac, neurological and cutaneous disturbances. The drug was withdrawn in 2 (5.3%) patients because of nausea and vomiting. One patient died of pulmonary infiltrations. It is concluded that adverse effects are common with amiodarone but are tolerated well, making this drug an excellent choice for treatment of cardiac arrhythmias.

Administration, Oral↗
PubMed1991

Artificial mutants generated by the insertion of random oligonucleotides into the putative nucleoside binding site of the HSV-1 thymidine kinase gene.

We have obtained 42 active artificial mutants of HSV-1 thymidine kinase (ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21) by replacing codons 166 and 167 with random nucleotide sequences. Codons 166 and 167 are within the putative nucleoside binding site in the HSV-1 tk gene. The spectrum of active mutations indicates that neither Ile166 nor Ala167 is absolutely required for thymidine kinase activity. Each of these amino acids can be replaced by some but not all of the 19 other amino acids. The active mutants can be classified as high activity or low activity on two bases: (1) growth of Escherichia coli KY895 (a strain lacking thymidine kinase activity) in the presence of thymidine and (2) uptake of thymidine by this strain, when harboring plasmids with the random insertions. E. coli KY895 harboring high-activity plasmids or wild-type plasmids can grow in the presence of low amounts of thymidine (less than 1 microgram/mL), but are unable to grow in the presence of high amounts of thymidine. On the other hand, E. coli KY895 harboring low-activity plasmids can grow at a high concentration of thymidine (greater than 50 microgram/mL) in the media. The high-activity plasmids also have an enhanced [3H]dT uptake. The amounts of thymidine kinase activity in vitro in unfractionated extracts do not correlate with either growth at low thymidine concentration or the rate of thymidine uptake. Heat inactivation studies indicate that the mutant enzymes are without exception more temperature-sensitive than the wild-type enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Cloning and primary structure of a human islet isoform of glutamic acid decarboxylase from chromosome 10.

Glutamic acid decarboxylase (GAD; glutamate decarboxylase, L-glutamate 1-carboxy-lyase, EC 4.1.1.15), which catalyzes formation of gamma-aminobutyric acid from L-glutamic acid, is detectable in different isoforms with distinct electrophoretic and kinetic characteristics. GAD has also been implicated as an autoantigen in the vastly differing autoimmune disease stiff-man syndrome and insulin-dependent diabetes mellitus. Despite the differing GAD isoforms, only one type of GAD cDNA (GAD-1), localized to a syntenic region of chromosome 2, has been isolated from rat, mouse, and cat. Using sequence information from GAD-1 to screen a human pancreatic islet cDNA library, we describe the isolation of an additional GAD cDNA (GAD-2), which was mapped to the short arm of human chromosome 10. Genomic Southern blotting with GAD-2 demonstrated a hybridization pattern different from that detected by GAD-1. GAD-2 recognizes a 5.6-kilobase transcript in both islets and brain, in contrast to GAD-1, which detects a 3.7-kilobase transcript in brain only. The deduced 585-amino acid sequence coded for by GAD-2 shows less than 65% identity to previously published, highly conserved GAD-1 brain sequences, which show greater than 96% deduced amino acid sequence homology among the three species. The function of this additional islet GAD isoform and its importance as an autoantigen in insulin-dependent diabetes remain to be determined.

Amino Acid Sequence↗
PubMed1991

Effects of sodium butyrate on proliferation-dependent insulin gene expression and insulin release in glucose-sensitive RIN-5AH cells.

A rat islet tumor subclone, RIN-5AH-T2-B, was cultured with 2 mmol/liter of the proliferation-arresting compound sodium butyrate (NaB). Insulin gene expression and glucose-stimulated insulin release were analyzed and compared with logarithmically proliferating and confluent control cells cultured without NaB. Logarithmically proliferating control cells revealed high insulin gene expression. In the presence of amino acids, these cells showed a dose-dependent insulin response to glucose with a half-maximal and maximal 6.5-fold stimulation by 0.8 and 5.6 mmol/liter D-glucose, respectively. However, as the control cells approached growth arrest, insulin gene expression subsided to below detectability, an occurrence that is associated with decreased insulin release and accumulation of cells in the G1 phase of the cell cycle. In contrast, NaB-arrested cells showed continuous insulin gene expression throughout the experiment. Despite this, insulin release in response to glucose was lost. NaB revealed a biphasic effect on the cell-cycle: after an initial leaky G1 arrest during the first 24 h, the 5AH-B cells were arrested in G2 during the following 3 days. These data suggest that insulin gene expression and glucose-stimulated insulin release are affected by the cell cycle. These glucose-sensitive RIN-5AH-T2-B cells may be useful in studies of insulin secretion and gene regulation.

Animals↗
PubMed1991

Autoimmunity of diabetes.

Insulin-dependent diabetes mellitus is associated with a growing number of immune abnormalities. At the time of clinical onset, most patients developing the disease as children or young adults have autoantibodies reactive with islet beta cells. Current autoantibody markers for IDDM are not sufficient to predict the disease in the general population. Studies in first-degree relatives indicate the presence of a subclinical disease characterized by beta cell dysfunction, which may or may not progress to overt IDDM. Although IDDM is genetically linked to certain HLA-DQ class II molecules, it needs to be clarified whether these molecules determine the propensity to react to certain antigens, the failure to maintain tolerance, or the ability to produce disease-associated autoantibodies. Circumstantial evidence suggests that yet another gene outside the HLA complex on chromosome 6 is more important. The interaction with the environment needs to be clarified, and the etiologic role of viruses has not been substantiated. An underlying systemic autoimmune propensity may influence environmental insults and perpetuate islet beta cell destruction. Until these mechanisms are understood, clinicians should periodically check their patients with IDDM for other organ-specific as well as non--organ-specific autoimmune diseases. Our understanding of these phenomena is poor, which may explain why clinical trials with immunosuppressive agents have been of limited success. Further studies on the molecular biology of the immune response against islet beta cell-specific antigens are necessary for the development of both predictive tests and novel measures to prevent IDDM.

Autoantibodies↗
PubMed1989

Amplification of a polymorphic dihydrofolate reductase gene expressing an enzyme with decreased binding to methotrexate in a human colon carcinoma cell line, HCT-8R4, resistant to this drug.

A methotrexate (MTX)-resistant human colon carcinoma cell line was obtained by growing HCT-8 cells in stepwise increasing concentrations of the drug. The resistant subline (HCT-8R4) was able to grow in the presence of 1 x 10(-4) M MTX and was found to have a 25-fold increase in the level of the target enzyme dihydrofolate reductase (DHFR), with a corresponding increase in DHFR gene copies as well as DHFR transcripts. Southern blot analysis of DNA from HCT-8R4 cells revealed the amplification of an altered gene. The amplified DHFR gene lacks an EcoRI restriction enzyme site in the coding region, normally present in other human cell lines. Sequence analysis of cDNA synthesized from transcripts in the MTX-resistant cell line revealed a base transition T----C at nucleotide position 91 resulting in a substitution of serine for phenylalanine. The dissociation constant for MTX binding to the HCT-8R4 enzyme was 1.25 nM, an 8-fold increase from the Kd 150 pM of purified wild type human DHFR. This decrease in binding of MTX to the HCT-8R4 DHFR is consistent with the predicted involvement of phenylalanine in the DHFR active site in hydrophobic interactions with MTX. This mutation plus the 25-fold increase in DHFR activity explains the high level of resistance of this subline to MTX.

Base Sequence↗
PubMed1988

The effect of 5'-amino-5'-deoxythymidine on the pattern of polyadenylation of herpes simplex virus type 1 ribonucleic acid.

Treatment of herpes simplex virus type 1 (HSV-1) infected Vero cells with 5'-amino-5'-deoxythymidine (AdThd) causes a 65% reduction in the amount of total viral RNA present at late times of infection. This decrease is apparent as early as 6 hours post infection, affecting the levels of viral cytoplasmic polyadenylated (poly(A+] species to a greater extent than non-polyadenylated (poly(A-] RNA. Cytoplasmic viral poly(A+) RNA is present in AdThd-treated cultures at only 10% control poly(A+) levels, yet there is no evidence of a direct inhibition of RNA polyadenylation. Underrepresentation of RNA species in the cytoplasm is not sequence-specific. The results suggest that the antiviral activity of AdThd may involve not only incorporation into viral DNA, with a resultant decrease in viral transcription, but also perturbation of the relative amounts of viral poly(A+) RNA and poly(A-) RNA.

Animals↗
PubMed1987

The association of supersensitive cholinergic REM-induction and affective illness within pedigrees.

Based on the Rieder and Gershon (1978) biological genetic study paradigm we compared the prevalence of a putative vulnerability factor (rapid cholinergic REM sleep induction) between 35 affectively ill and 31 well first-degree relatives of 34 probands chosen on the basis of presence of primary affective illness and positive marker status. A significantly higher percentage of ill relatives (63%, 22 out of 35 subjects) had a supersensitive REM-induction response as compared to well relatives (22%, 7 out of 31 subjects). Since the current study does not rule out the effects of prior depressive episodes or treatment on cholinergic sensitivity, caution must be exercised in the interpretation of our findings.

Acetylcholine↗
PubMed1987

[Painful pronation--a diagnostic pitfall in septic arthritis and osteomyelitis of the elbow in infancy].

Pulled elbow is a common injury in infancy and childhood. The history and clinical findings are usually classical, but one should never forget that the classical history can always be easily reconstructed by the examining physician. It can be estimated that in 93% of all cases a dramatic response to therapy can be observed. In the remaining 7% the most common cause for failure to treatment is an incomplete or recurrent subluxation of the radial head and distortions or fractures of the elbow. But in approx. 1% the examining physician must suspect a hidden osteomyelitis or osteoarthritis of the elbow. With adequate antibiotic therapy the prognosis is generally good. To avoid this diagnostic pitfall, it is essential to re-examine carefully all cases which do not respond to therapy in order to exclude an osteomyelitis.

Arthritis, Infectious↗
PubMed1987

[Genetic transformation of somatic cells. XII. Mutations in human satellite DNA introduced into Chinese hamster cells].

Data are presented about detailed restriction mapping, hybridization and sequence analysis of plasmid pRT301 rescued into E. coli 25-30 cell divisions after transfection of Chinese hamster cells. This plasmid contains an insert of human satellite III fragment (HS3), which was replicated many times in mammalian cells, and we found multiple point mutations in this non-selectable fragment, mainly single inserts of GC base pair. Specificity of mutagenesis of HS3 induced by transfection and replication in Chinese hamster cells differs from mutagenesis specificity found by other authors for selectable genes.

Animals↗
PubMed1985

Methotrexate resistant cells as targets for selective chemotherapy.

Strategies that are selective for eradicating methotrexate resistant cells are described. These strategies have been developed based on knowledge of the mechanism of drug resistance encountered in experimental systems and in the clinic. Drug resistance to methotrexate in experimental tumors is commonly due to either gene amplification (dihydrofolate reductase) or to impaired transport of methotrexate. While no effective drugs or methods to prevent gene amplification have been described, the concept of developing "pro drugs", i.e. a drug that is selectively reduced by dihydrofolate reductase to an inhibitor of another critical folate enzyme (thymidylate synthase, methionine synthetase, folylpolyglutamate synthetase) remains worthwhile. Second generation antifolates such as trimetrexate which are effective vs methotrexate transport resistant cells have already been developed and are in clinical trial.

Animals↗
PubMed1985

Cholinergic REM sleep induction response correlation with endogenous major depressive subtype.

We compared central cholinergic responsiveness (using the latency to induction of rapid eye movement sleep after arecoline challenge as a response marker) in 90 subjects: patients with major depressive disorder (MDD) (n = 53), nonaffective psychiatric controls (n = 17), and normal controls (n = 20). MDD patients as a whole showed a supersensitive cholinergic response compared to nonaffective patients and normal subjects. Further analysis indicated a strong association between cholinergic supersensitivity and endogenous subtype of MDD, including a significant correlation with specific endogenous features such as distinct quality of mood, anhedonia, lack of reactivity, and agitation. Unlike rapid eye movement (REM) latency (a more conventional physiological marker), cholinergic sensitivity did not correlate with age or severity of illness but only with the presence of endogenous features. Previously described sleep physiological correlates such as REM latency and REM density of the first REM period also distinguished between endogenous and nonendogenous MDD. There was a statistically significant correlation between REM latency and arecoline REM induction response.

Adult↗
PubMed1985

Psychiatric training and therapies in Ayurved.

This paper describes the selection and training procedures, ethical codes, metaphysical theories and principles of psychiatric treatments as practiced in Ayurved. Three treatment approaches for psychological disorders are: Ministered therapies (psychotherapies), Performance therapies (rituals), Auto therapies. Other forms of therapies mentioned are herbal, physical and natural. Treatments were administered with benediction. Man was treated as a whole with a psychosomatic approach. Ayurved is still a living science, though much of its knowledge has passed into oblivion. Resurrection of the lost treasure is advocated if the objective of 'Health for All by 2000 A.D.' is to be achieved for countries like India.

Ethics, Medical↗