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S T Lee

Publications and source records attributed to S T Lee.

At least 19 recordsLinked to original sources
PubMed1995

Organization and sequence of the human P gene and identification of a new family of transport proteins.

We have determined the structure, nucleotide sequence, and polymorphisms of the human P gene. Mutations of the P gene result in type II oculocutaneous albinism (OCA2) in humans and pink-eyed dilution (p) in mice. We find that the human P gene is quite large, consisting of 25 exons spanning 250 to 600 kb in chromosome segment 15q11-q13. The P polypeptide appears to define a novel family of small molecule transporters and may be involved in transport of tyrosine, the precursor to melanin synthesis, within the melanocyte. These results provide the basis for analyses of patients with OCA2 and may point toward eventual pharmacologic treatment of this and related disorders of pigmentation.

Albinism, Oculocutaneous↗
PubMed1995

In vitro metabolism of testosterone by gonads of the grouper (Epinephelus tauvina) before and after sex inversion with 17 alpha-methyltestosterone.

The steroidogenic potential of gonadal tissues of the protogynous grouper (Epinephelus tauvina) was examined before and after sex inversion with 17 alpha-methyltestosterone. Incubations of gonadal tissues of the fish with [3H]testosterone resulted in the biosynthesis of 5 beta-androstane-3 beta, 17 beta-diol and 5 beta-dihydrotestosterone as the only metabolites in the female phase. Although the production of these 5 beta-reduced androgens persisted in the male phase, there was a shift toward the production of 11 beta-hydroxytestosterone and 11-ketotestosterone as major metabolites.

Androstane-3,17-diol↗
PubMed1995

Using Fyrite to monitor incubator carbon dioxide levels.

PURPOSE: The Fyrite analyzer (Bacharach, Incorporated) was evaluated to ascertain whether it would perform within the range specified by the manufacturer (+/- 0.5%). Fyrite analyzer samples were compared to control samples obtained using an infrared CO2 monitor (Ohmeda, Model Number 5200). METHODS: Ten Fyrite analyzer measurements from each of three incubators were obtained using two different analyzers by three investigators for a total of 60 measurements per investigator. Twenty control measurements for each of the three incubators were obtained using an infrared monitor calibrated at the 5.0% CO2 level. RESULTS: Fyrite analyzer values fell outside of an acceptable range (Control mean CO2 +/- 0.5%) for 7 of 60 (11.7%) observations for Incubator 1 and 4 of 60 (6.7%) observations for Incubator 2. (Incubator 3 had no values outside the range.) The Fyrite analyzers were significantly different from each other (P = 0.002). The three investigators (I) differed significantly from the control (I1 and I3, P < 0.001; I2, P = 0.02) as well as from each other (I1 vs I2, P < 0.001; I1 vs I3, P < 0.001; I2 vs I3, P < 0.016). CONCLUSIONS: Use of an infrared monitor for incubator calibration and monthly CO2 checks in concert with daily use of the Fyrite as a monitoring tool only is the better method.

Calibration↗
PubMed1995

Acute intracranial subdural haematoma resulting from lumbar myelography.

We report a case of acute intracranial subdural haematoma after lumbar myelography with Iopamidol. The haematoma was successfully treated by emergency craniotomy. The bleeding came from cortical bridging veins as confirmed by surgery. This rare complication should be suspected in patients who complain of prolonged headache or develop a neurological deficit after myelography.

Acute Disease↗
PubMed1995

Identification of Leishmania species by a specific DNA probe that is conserved only in the maxicircle DNA of human-infective Leishmania parasites.

An A + T-rich repeated DNA sequence cloned from maxicircle DNA of Leishmania mexicana amazonensis was found to be conserved in the maxicircles of human-infective Leishmania species but totally absent from non-human-infective ones. Differences in the pattern of distribution of this repeated sequence in the maxicircles of each human-infective Leishmania species potentially allow the development of a sensitive probe to differentiate among these species.

Animals↗
PubMed1995

A phylogenetic analysis of the genus Saccharomonospora conducted with 16S rRNA gene sequences.

Nearly complete sequences of 16S rRNA genes of representative strains of the genus Saccharomonospora were determined following the isolation and cloning of the amplified genes. The sequences were aligned with those of representatives of the family Pseudonocardiaceae, and a phylogenetic tree was inferred by the neighbor-joining method. The genus Saccharomonospora formed a distinct clade within the evolutionary radiation encompassed by the family Pseudonocardiaceae. The average nucleotide similarity value found between the type strains of the four validly described Saccharomonospora species was 97.5% +/- 1.0%. The most distant relationship was found between Saccharomonospora azurea and Saccharomonospora viridis K73 (96.3% similarity). In contrast, Saccharomonospora azurea K161 and "Saccharomonospora caesia" K163 had identical 16S rRNA gene sequences. The nucleotide sequence data suggest that the genus Saccharomonospora contains several new centers of variation.

Actinomycetales↗
PubMed1995

Distribution of cryV-type insecticidal protein genes in Bacillus thuringiensis and cloning of cryV-type genes from Bacillus thuringiensis subsp. kurstaki and Bacillus thuringiensis subsp. entomocidus.

DNA dot blot hybridizations with a cryV-specific probe and a cryI-specific probe were performed to screen 24 Bacillus thuringiensis strains for their cryV-type (lepidopteran- and coleopteran-specific) and cryI-type (lepidopteran-specific) insecticidal crystal protein gene contents, respectively. The cryV-specific probe hybridized to 12 of the B. thuringiensis strains examined. Most of the cryV-positive strains also hybridized to the cryI-specific probe, indicating that the cryV genes are closely related to cryI genes. Two cryV-type genes, cryV1 and cryV465, were cloned from B. thuringiensis subsp. kurstaki HD-1 and B. thuringiensis subsp. entomocidus BP465, respectively, and their nucleotide sequences were determined. The CryV1 protein was toxic to Plutella xylostella and Bombyx mori, whereas the CryV465 protein was toxic only to Plutella xylostella.

Amino Acid Sequence↗
PubMed1995

CD34 immunohistochemical staining of bone marrow biopsies in myelodysplastic syndromes.

Although it has been shown that the percentage of bone marrow blasts in myelodysplastic syndrome (MDS) constitute the only independent determinant of survival and progression to acute leukemia, the great variability in survival among patients with MDS of similar percentage of blasts has prompted us to investigate new objective, independent prognostic parameters for the selection of high-risk patients. It was suggested that CD34 antigen expression adversely affected the prognosis of acute myelogenous leukemia. However, no study has been published so far on clinical and prognostic significance of CD34 antigen expression in MDS. Bone marrow biopsies from 58 patients diagnosed as primary MDS were studied using QBEND/10, a monoclonal antibody which recognized the human progenitor CD34 antigen on routine aldehyde-fixed, paraffin-embedded samples. The high percentage of CD34-positive cells (above 3% of total bone marrow nucleated cells) was predominantly observed in cases with RAEB-T, CMML, and to a lesser degree in RAEB. But neither age, hemograms, bone marrow findings including percentage of blasts, ALIP, nor leukemic transformation correlated with the percentage of CD34-positive cells. The median actuarial survival time in the high positive group was significantly shorter (12.0 months) than that of the low group (30.0 months; p = 0.028). The high CD34 aggregate (> or = 3) was selectively found in cases with RAEB, RAEB-T, and CMML. The percentage of bone marrow blasts (p = 0.007) and ALIP (p = 0.030) significantly correlated with number of CD34 aggregates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Differential responses of CD34-positive acute myelogenous leukemic blasts to the costimulating effects of stem cell factor with GM-CSF and/or IL-3.

Stem cell factor (SCF), a c-kit ligand, has a preferential effect on the proliferation of several classes of immature hematopoietic progenitor cells in combination with GM-CSF or IL-3. To analyze the costimulatory role of SCF in leukemic growth, we investigated the effect of SCF in the presence of GM-CSF and/or IL-3 on isolated CD34-positive (CD34+) leukemic blasts from 15 patients with acute myelogenous leukemia (AML). Cultures of CD34+ cells from normal bone marrow were used as controls. When the proliferation of CD34+ AML blasts in the presence of GM-CSF and/or IL-3 were evaluated in vitro for the effects of SCF, two patterns emerged. In one pattern, CD34+ AML blasts responded with a significant increase in DNA synthesis and/or colony formation when SCF was used with GM-CSF and/or IL-3 relative to the growth with SCF alone; This result is consistent with those CD34+ bone marrow cells from normal donors. Six patients (40%) were included in this category. The addition of SCF as a single factor resulted in colony formation in all six of these cases. In the other pattern, nine of the patients (60%) had CD34+ leukemic cells whose growth with SCF plus either GM-CSF, IL-3, or GM-CSF+IL-3, was not significantly different from the growth noted in the presence of SCF alone. Among them seven cases that did not form colonies in response to SCF alone, and one case showing autocrine, background growth were included. In the six cases in which the costimulating effects of SCF were documented, CD34+ c-kit+ blasts comprised 50.5 +/- 18.7% of the CD34+ leukemic blasts-higher than 21.8 +/- 19.4% of cases in which the costimulating effect of SCF was not documented. In the cases showing high c-kit antigen expression (> or = 40%), SCF had a costimulatory effect in 71% (5/7) of the patients. In conclusion, our data indicate that CD34+ leukemic blasts from a good proportion of patients with AML did not respond to the costimulating effects of SCF in the presence of GM-CSF adn/or IL-3, in contrast to those CD34+ bone marrow cells from normal donors. The possible use of SCF for acute leukemia must await further cytogenetic and molecular studies, which should clarify the preferential costimulating role of SCF in normal hematopoiesis.

Antigens, CD↗
PubMed1994

A YAC contig spanning a cluster of human type III receptor protein tyrosine kinase genes (PDGFRA-KIT-KDR) in chromosome segment 4q12.

We have mapped five genes encoding protein tyrosine kinases (PTKs) to the pericentromeric region of human chromosome 4. PTK4 and TYRO4, which encode nonreceptor intracellular PTKs, are located at 4p12 and 4q13, respectively. The other three genes, PDGFRA, KIT, and KDR, encode type III transmembrane receptor PTKs for known ligands. We have developed a contig of 29 yeast artificial chromosomes (YACs) spanning approximately 2 Mb of DNA at 4q12 that includes PDGFRA, KIT, and KDR, and we have used this YAC contig to map 12 different sequence-tagged sites in this region. PDGFRA, KIT, and KDR thus constitute a cluster of genes at 4q12 encoding closely related type III receptor PTKs. Mutations of the human KIT gene result in piebaldism, an autosomal dominant disorder of melanocyte development.

Base Sequence↗
PubMed1994

Efficacy and safety of loratadine compared with astemizole in Malaysian patients with allergic rhinitis.

Nonsedating selective peripheral H1 receptor antagonists are an important advance in antihistaminic therapy in allergic patients. This is a randomised, double-blind parallel group study comparing the use of two such agents viz loratadine 10mg daily and astemizole 10mg daily for two weeks in 39 Malaysian allergic rhinitis patients. At these dosages, both drugs were demonstrated to be efficacious (p < 0.05) for controlling nasal symptoms and safe in terms of short term biochemical and haematological changes and adverse effects noted. Evaluating efficacy criteria utilised in this study loratadine and astemizole were comparable but loratadine was significantly more effective in three areas viz: (i) in diminishing nasal symptoms after 2 weeks of treatment (p = 0.03); (ii) physician's efficacy evaluation after 2 weeks' treatment (p = 0.009); (iii) patient's efficacy evaluation after 2 weeks' treatment (p = 0.019).

Astemizole↗
PubMed1992

Deletion of the pro-alpha 1(I) N-propeptide affects secretion of type I collagen in Chinese hamster lung cells but not in Mov-13 mouse cells.

We have introduced two mutations into a full-length human pro-alpha 1(I) cDNA that delete 114 amino acids or the entire 139 amino acids of the N-propeptide domain. Wild-type and mutated versions of the cDNA were introduced into cultured Chinese hamster lung (CHL) cells, which do not produce endogenous type I collagen, and into Mov-13 mouse cells, which produce endogenous pro-alpha 2(I) chains but not pro-alpha 1(I) chains. As judged by resistance to proteases, neither mutation impaired intracellular triple helical assembly of human alpha 1(I) homotrimers in CHL cells, or of chimeric type I collagen comprised of human alpha 1(I) and mouse alpha 2(I) chains in Mov-13 cells. Thus, the N-propeptide is not necessary for intracellular assembly of the main helical collagen domain of type I collagen. In CHL cells the rate of secretion of the mutant homotrimers was greatly reduced as compared to wild type homotrimers, and by immunofluorescence and immunoelectron microscopy, the mutant chains were shown to be accumulated in large vesicular expansions of the rough endoplasmic reticulum. When such cells were retransfected with cDNA encoding wild-type human alpha 2(I) chains, mutant alpha 1(I) chains were not rescued and heterotrimers containing the mutant chains were also retained in the intracellular vesicles. By contrast, deletion of the N-propeptide did not affect secretion of heterotrimers containing mutant chains from Mov-13 cells. Thus, an intact N-propeptide appears necessary for efficient secretion of type I collagen from some but not all cell types.

Amino Acid Sequence↗
PubMed1992

Retention of C60 and C70 fullerenes on reversed-phase high-performance liquid chromatographic stationary phases.

The separation of C60 and C70 fullerenes on four different polysiloxane stationary phases was examined. It was determined that polar solvents can be used as mobile phases effectively for the separation of fullerene molecules. Unlike previously published work, a polymeric octadecyl siloxane (ODS) stationary phase provided higher separation factors for C70/C60 than did monomeric ODS stationary phases or phenyl substituted stationary phases. For example, for a methanol-diethyl ether (50:50, v/v) mobile phase and C60, k' approximately 5.0 separation factors, alpha = 3.3, were achieved with polymeric ODS compared to alpha = 2.2, with a monomeric ODS stationary phase. A linear solvation energy relationship (LSER) was used to model the importance of solvent interactions and stationary phase interaction to solute retention.

Carbon↗
PubMed1992

Characterization of sequence changes in kinetoplast DNA maxicircles of drug-resistant Leishmania.

We have compared kinetoplast DNA maxicircles of tunicamycin- and arsenite-resistant variants of repeatedly cloned Leishmania mexicana amazonensis showing DNA amplification with wild-type and arsenite-resistant variants of the same lineage that do not show DNA amplification. DNA restriction patterns and the degree of cross-hybridization between maxicircle DNA fragments of parasites displaying DNA amplification and those of parasites without amplification were examined. In addition, the nucleotide sequence of the cytochrome b (Cyb) gene from the coding region was compared between these two groups of parasites. Extensive changes were found in the nucleotide sequences and the amino acid sequences of the cytochrome gene of the maxicircles of variants with DNA amplification. The Cyb genes from both groups had much shorter open reading frames than the same gene from Leishmania tarentolae and Trypanosoma brucei. The simultaneous changes in maxicircles and minicircles of these variants suggest that they may confer the advantage of maintaining viable mitochondrial function under selective pressure.

Amino Acid Sequence↗
PubMed1992

Effects of exposure to carbon disulphide on low density lipoprotein cholesterol concentration and diastolic blood pressure.

The relation of carbon disulphide (CS2) exposure to risk factors for ischaemic heart disease was recently examined using data from a 1979 cross sectional study of 410 male textile workers, of whom 165 were exposed and 245 were unexposed to CS2. Average eight hour CS2 exposure concentrations ranged from 0.6 to 11.8 ppm by job title category among the exposed workers. A significant and positive linear trend in low density lipoprotein cholesterol concentration (LDLc) and diastolic blood pressure with increasing CS2 exposure was found after adjustment for potential confounders. When exposure was examined as a categorical variable (none, low, moderate, and high), the high exposure group had an adjusted mean LDLc that was 0.32 mmol/l greater than the non-exposed group (p = 0.02), and an adjusted mean diastolic blood pressure that was 3.16 mm Hg greater than the non-exposed group (p = 0.09). The effect of CS2 on diastolic blood pressure was strengthened in analyses limited to exposed workers: the high exposure group had an adjusted mean diastolic blood pressure that was 5 mm Hg greater than that of the low exposed group (p = 0.03). Triglyceride, high density lipoprotein cholesterol, and fasting glucose concentration, and systolic blood pressure were not affected by exposure. Blood lead concentration was positively associated with systolic and diastolic blood pressure. The results indicate that relatively modest exposure to CS2 may raise LDLc concentration and diastolic blood pressure and suggest mechanisms by which exposure to CS2 may influence risk of ischaemic heart disease. Also the results provide further support for the hypothesis of a possible association between blood lead concentration and blood pressure.

Adult↗
PubMed1992

Esophageal strictures: treatment with a new design of modified Gianturco stent. Work in progress.

To overcome the drawbacks of the modified Gianturco stent tube with barbs, a new barbless stent tube was constructed. Twenty-two barbless stent tubes 4.5-14.0 cm long were placed with a new introducing tube in 21 patients: 10 stent tubes in 10 patients with recurrent dysphagia after radiation therapy or chemotherapy, 10 in 10 patients with esophageal cancer in whom surgical management was contraindicated, and two in one patient with postoperative benign stricture. No technical failure or procedural complications occurred. After the procedure, all but two patients could ingest most or all foods. In two patients with an esophagorespiratory fistula and one patient with esophageal rupture, the barbless stent tube successfully occluded the fistula and rupture site. The stent tube migrated in one patient. Fifteen patients are surviving, with the stent tubes patent for 3-35 weeks (mean patency, 13 weeks); the six other patients died 7-24 weeks (mean, 16 weeks) after stent placement. It is concluded that barbless stent tubes show promise in the management of dysphagia caused by esophageal strictures.

Aged↗