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Biomedical subjects

S K Dube

Publications and source records attributed to S K Dube.

At least 37 records · Page 2Linked to original sources
PubMed1990

Restoration of shooty morphology of a nontumorous mutant of Nicotiana glauca x N. langsdorffii by cytokinin and the isopentenyltransferase gene.

The shooty morphology of a nontumorous amphidiploid mutant of Nicotiana glauca Grah. x N. langsdorffii Weinm. was restored by cytokinins, whether exogenously applied or endogenously produced by transformation of the mutant with a transfer DNA (T-DNA) cytokinin-biosynthesis gene (isopentenyltransferase; ipt). Auxins alone did not confer this effect. Similar transformation was not achieved for the parental species. In the case of transformation with the ipt gene, selection of the transformed tissues was based on its hormone-independent growth in the presence of the antibiotic kanamycin. Transformed tissues exhibited a shooty morphology, indistinguishable from that of wildtype genetic tumors N. glauca x N. langsdorffii. This altered phenotype was caused by the presence and constitutive expression of the ipt gene. The insertion and expression of this gene in transformed tissues was confirmed by using the polymerase chain reaction (PCR) technique as well as conventional molecular hybridization analysis. Expression of the ipt gene led to an elevated level of cytokinin in the transformed mutant tissues. This evidence supports the notion that genetic tumors are caused, at least in part, by elevated levels of cytokinin in interspecific hybrids.

Alkyl and Aryl Transferases↗
PubMed1987

Molecular cloning and sequence of the gene for p9Ka. A cultured myoepithelial cell protein with strong homology to S-100, a calcium-binding protein.

The gene for p9Ka, a protein of molecular weight 9000 that is expressed in cultured rat mammary myoepithelial cells, has been isolated from a normal rat genomic library in bacteriophage lambda, by its ability to hybridize to a cloned complementary DNA corresponding to p9Ka mRNA. The cloned rat genomic DNA fragment hybridized to translatable p9Ka mRNA. A nucleotide sequence of 2340 base-pairs of genomic DNA surrounding the p9Ka cDNA sequence has been obtained; the gene contains one intervening sequence of 675 nucleotides. The 3' end of the p9Ka mRNA has been identified on the gene sequence to be 13 nucleotides downstream from a poly(A) addition signal AATAAA. The gene contains an open reading frame of 101 amino acid residues, which is the only open reading frame in the entire gene long enough to encode a protein of molecular weight at least 9000. This hypothetical protein sequence shows greater than 40% homology to rat or bovine S-100 protein and over 30% homology to bovine intestinal calcium-binding protein. The results suggest that p9Ka may be related to a family of low molecular weight calcium-binding proteins.

Amino Acid Sequence↗
PubMed1983

Amplification and organization of dihydrofolate reductase genes in a human leukemic cell line, K-562, resistant to methotrexate.

A subline of human leukemia cells (K-562), highly resistant to methotrexate, was developed by stepwise selection in the presence of increasing concentrations of this drug. The ED50 of these resistant cells was 1 mM compared to 10 nM for the parental line. Comparison of certain folate-requiring enzymes from crude extracts of the parent and resistant cells showed a 240-fold elevation of dihydrofolate reductase activity in the resistant cells with no significant increase in the levels of the other enzymes. Purified dihydrofolate reductase from the resistant cells had the same physical and kinetic properties as the enzyme from the sensitive cells. Southern blot analysis showed a marked increase in the number of dihydrofolate reductase genes in the resistant line. The genomic organization of the human dihydrofolate reductase gene was determined by hybridization with specific cDNA sequences from a human cDNA to DNA fragments from K-562 cells generated by restriction endonucleases. The human dihydrofolate reductase gene contained at least four intervening sequences and was approximately 30 kb in size. Northern blot studies demonstrated an increase of dihydrofolate reductase mRNA species; the predominant message was 3.8 kb. Karyotype analysis revealed three elongated marker chromosomes, derived from chromosomes 5, 6, and 19 which contained homogeneous staining regions, which were not present in the parent cell line.

Cell Line↗
PubMed1983

Gene amplification and altered enzymes as mechanisms for the development of drug resistance.

Two known mechanisms by which neoplastic cells may become resistant to chemotherapeutic agents are reviewed, using methotrexate (MTX) resistance as a model. These mechanisms are an increased level of target enzyme, found in several instances to be a consequence of gene amplification, or an altered target enzyme or receptor, less capable of binding the drug. An example of MTX resistance due to low-level gene amplification in leukemia cells from an MTX-resistant patient is described. Strategies for selectively eradicating these resistant cell populations may be formulated based on the mechanism by which these cells became drug-resistant.

Animals↗
PubMed1981

Urinary catecholamines, plasma renin activity and blood pressure in newborns: effects of narcotic withdrawal.

Blood pressure and plasma renin activity were studied in 13 infants of drug-dependent mothers (heroin and/or methadone) and 20 control newborns for a period of 21 days. Urinary excretion of epinephrine and norepinephrine were also measured at 24 and 48 h of age. The systolic blood pressure was found to be significantly elevated in newborns of drug-dependent mothers compared with controls (p less than 0.01), but diastolic blood pressure levels were similar. Plasma renin activity was significantly elevated (p less than 0.001) at 48-72 h and urinary epinephrine levels were significantly lower (p less than 0.05) at 24-48 h of age in the drug group, and norepinephrine levels were equivalent. Systolic hypertension and elevated plasma renin activity in these newborns of dependent mothers may be due to increased beta-adrenergic receptor sensitivity.

Catecholamines↗
PubMed1981

Relationship of thyroid hormone levels to the severity of the narcotic withdrawal syndrome.

Serum T3, T4 and thyroid stimulating hormone (TSH) were evaluated in 24 neonates of mothers taking methadone and compared with 16 normal controls using cord serum and serum taken on days 1, 2, 3, 4, 7, and 14. Patients were divided into treated (Rx; n = 14) and not treated (No Rx; n = 10) groups based on withdrawal scores and correlated to thyroid hormone levels. T4 levels were greater in the Rx group when compared to controls on days 2, 4 and 7 (p less than 0.01) and when compared to the No Rx group on days 3 and 7 (p less than 0.005). No Rx patients had higher T4 levels when compared to controls on day 4 (p less than 0.05). In general T3 levels paralleled T4 results. TSH levels were decreased in the Rx group compared to No Rx and controls on day 2 (p less than 0.01). Lipsitz scores correlated with T4 levels on days 3, 4, and 7 in methadone patients (p less than 0.05) but did not correlate with T3 or TSH. These findings suggest a correlation between the severity of withdrawal symptoms and T4 and T3 levels.

Female↗
PubMed1980

Effects of methadone on thyroid function in mother, fetus, and newborn.

The effects of maternal use of methadone during pregnancy on tests of thyroid function were studied in 14 women and their offspring. Twelve normal nonaddicted women and their infants served as a control group. Concentrations of thyrotropin (TSH), thyroxine (T4), and triiodothyronine (T3) were not significantly different in maternal and cord serum, and in infant serum at age 24 hours. There was no significant difference in infants' TSH concentrations at 2, 3, and 7 days of age. At 2 and 7 days, T3 levels were significantly higher in the methadone than in the control group (P = .01 and less than .01, respectively). At 3 days, differences were of borderline significance (P = .08). Increased T4 levels in the methadone group of infants were statistically significant at 2 days (P less than .01) and at 3 and 7 days (P = .05). The mechanisms responsible for the biochemical evidence of hyperthyroidism were not determined, but may have been related to altered autonomic function and/or increased metabolic activity which occurs during neonatal narcotic withdrawal.

Adolescent↗
PubMed1977

Localization of the globin gene in the template active fraction of chromatin of Friend leukemia cells.

Friend leukemia cell chromatin has been fractionated into template active and inactive components. The globin gene sequence is associated with the template active component both prior to and after the cells are induced with dimethyl sulfoxide to synthesize hemoglobin and therefore appears to be in an active configuration in uninduced as well as in induced Friend leukemia cells. In cells which have lost the ability to produce hemoglobin, the globin gene sequence is not associated with the template active fraction of chromatin. These results demonstrate the success of the fractionation procedure.

Animals↗
PubMed1976

Dimethylsulfoxide-induced differentiation and hemoglobin synthesis in tissue cultures of rat erythroleukemia cells transformed by 7,12-dimethylbenz(a)anthracene.

Permanent cell lines from transplantable tumors from 7, 12-dimethylbenz(a)anthracene-induced erythroleukemia of the rat were established. These cell lines maintain their erythroid nature. Erythroid differentiation can be induced by dimethylsulfoxide. This is shown by decrease in cell size, appearance of red and benzidine positive cells, and induced synthesis of four out of six adult globin chains.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

Gonococcal ophthalmia neonatorum. Relationship of maternal factors and delivery room practices to effective control measures.

Gonococcal opthalmia (proved by cultures) occurred in 11 infants delivered at the Jewish Hospital and Medical Center of Brookly (JHMCB) during a three and one-half-year period. Two more infant had conjunctivitis with presumptive evidence of gonococci (Gram stain of eye discharge). Silver nitrate was instilled in the eyes of the neonates by registered nurses. Maternal histories of these infants showed lack of prenatal care in ten, history of gonorrhea in pregnancy in three, and positive serology (STS) in two; ten of the mothers were unmarried. The over-all incidence of gonorrhea at the JHMCB prenatal clinic screening program is very low (0.02 per cent). Prevention of neonatal gonorrheal ophthalmia depends on: vigorous screening of mothers at delivery as well as during prenatal visits, careful attention to instillation of silver nitrate in the neonates' eyes, development of serologic tests for gonorrhea, and improved bacteriologic methods for culturing the organism.

Conjunctivitis↗
PubMed1975

Blood pressure studies in black children.

Blood pressure measurements were obtained under office conditions by auscultatory method, using appropriate cuff sizes, in 1,668 healthy black children (827 boys and 841 girls) ranging in age from 4 to 17 years. We found no significant difference between the mean systolic blood pressure of black children in our study and that of whites as reported in the literature. However, mean diastolic blood pressure was lower in black children. Some black children (3.6%) were found to have blood pressure more than 2 standard deviations above the mean for their age and should be closely observed for developing hypertensive cardiovascular changes.

Adolescent↗