PubMed Health⌕ Search

Biomedical subjects

B S Lee

Publications and source records attributed to B S Lee.

At least 19 recordsLinked to original sources
PubMed1992

Psychological factors, immunologic activation, and disease activity in rheumatoid arthritis.

The purpose of this study was to use structural equation modeling techniques to examine potential interrelationships among psychological factors, immunologic activation, and disease activity in rheumatoid arthritis (RA). The subjects were 80 male patients with a diagnosis of classic or definite RA. Measures included the Beck Depression Inventory, the Arthritis Helplessness Index, and the Arthritis Impact Measurement Scales (AIMS) pain score. Joint counts and immunophenotypic analyses of peripheral blood lymphocytes also were collected. Path analysis showed that percentage of HLA-DR+ cells in the peripheral blood and helplessness were related to join count. In addition, joint count had an effect upon depression. Depression had an effect upon pain, but there was no reciprocal effect of pain upon depression. This study describes a preliminary path model of interrelationships among psychological factors, immunologic activation, and disease activity in RA.

Aged↗
PubMed1992

Gene products that promote mRNA turnover in Saccharomyces cerevisiae.

We showed previously that the increased rate of mRNA turnover associated with premature translational termination in the yeast Saccharomyces cerevisiae requires a functional UPF1 gene product. In this study, we show that the UPF1 gene codes for a 109-kDa primary translation product whose function is not essential for growth. The protein contains a potential zinc-dependent nucleic acid-binding domain and a nucleoside triphosphate-binding domain. A 300-amino-acid segment of the UPF1 protein is 36% identical to a segment of the yeast SEN1 protein, which is required for endonucleolytic processing of intron-containing pre-tRNAs. The same region is 32% identical to a segment of Mov-10, a mouse protein of unknown function. Dominant-negative upf1 mutations were isolated following in vitro mutagenesis of a plasmid containing the UPF1 gene. They mapped exclusively at conserved positions within the sequence element common to all three proteins, whereas the recessive upf1-2 mutation maps outside this region. The clustering of dominant-negative mutations suggests the presence of a functional domain in UPF1 that may be shared by all three proteins. We also identified upf mutations in three other genes designated UPF2, UPF3, and UPF4. When alleles of each gene were screened for effects on mRNA accumulation, we found that the recessive mutation upf3-1 causes increased accumulation of mRNA containing a premature stop codon. When mRNA half-lives were measured, we found that excess mRNA accumulation was due to mRNA stabilization. On the basis of these results, we suggest that the products of at least two genes, UPF1 and UPF3, are responsible for the accelerated rate of mRNA decay associated with premature translational termination.

Amino Acid Sequence↗
PubMed1992

cDNA sequence and tissue expression of bovine vacuolar H(+)-ATPase M(r) 70,000 subunit.

cDNA clones encoding the 70,000 relative molecular weight (M(r)) subunit of the bovine vacuolar proton-adenosine triphosphatase (H(+)-ATPase) were isolated, and a total length of 3.1 kb in overlapping clones from bovine kidney and brain libraries was sequenced. The cDNA contains a 1.9-kb coding region and yields a deduced protein sequence of 618 amino acids. The subunit sequence has 50% amino acid identity with the corresponding subunit from yeast, carrot, and Neurospora vacuolar H(+)-ATPases. The internal regions of the protein are most highly conserved, whereas the NH2- and COOH-terminals exhibit variability. mRNA levels of the M(r) 70,000 subunit were examined in multiple bovine tissues and were found to be expressed at highest levels in kidney medulla and cortex, at moderate levels in brain and adrenal gland, and at low levels in liver, muscle, and heart.

Adenosine Triphosphatases↗
PubMed1992

Biochemistry of the renal V-ATPase.

In most eukaryotic cells, vacuolar H(+)-ATPases (V-ATPases) are present primarily or exclusively in intracellular membrane compartments, functioning in the acidification of the endocytic and secretory vacuolar apparatus necessary for constitutive cell function. V-ATPases also participate in renal hydrogen ion secretion in both the proximal and distal nephron, residing at high concentrations on the plasma membrane, where they are regulated physiologically to maintain the acid-base balance of the organism. Recent experiments have begun to reveal how the kidney controls transcellular proton transport while still maintaining acidification of intracellular compartments. Control may occur by recruitment of proton pumps to or away from the plasma membrane. The proton-transporting plasma membrane of intercalated cells is a specialized apparatus that translocates the enzyme between an intracellular membrane pool and the plasma membrane in response to physiological stimuli. Regulation may also occur by changes in the kinetics of the V-ATPase. V-ATPases are a family of structurally similar enzymes which differ in the composition of specific subunits. Cytosolic regulatory enzymes present in renal cells may preferentially affect V-ATPases in selective membrane compartments.

Adenosine Triphosphatases↗
PubMed1992

A case of prenatal diagnosis of hemophilia A.

Classic hemophilia, (hemophilia A), is an X-linked hereditary bleeding disorder affecting half of the male offspring of female carriers. Prenatal diagnosis offers an option, namely to restrict abortions to hemophilic fetuses only, and thus retain the chance of bearing normal sons. Recently, the authors have made a prenatal diagnosis of hemophilia A in an obligate carrier with a male fetus at 24 weeks of gestation by pure fetal sampling and accurate factor VIII coagulant assay, which was repeatedly less than 1% at 28 weeks of gestation.

Adult↗
PubMed1992

[Synthesis and antitumor activities of 4-acylthiol-4-deoxy-4'-demethylepipodophyllotoxin analogues].

This paper describes the synthesis and antitumor activity of 4-acylthiol-4-deoxy-4'-demethylepipodophyllotoxin analogues. 4-Mercapto-4-deoxy-4'-demethylepipodophyllotoxin prepared from 4'-demethylepipodophyllo-toxin with H2S in the presence of BF3.Et2O, was acylated with different acids using diethyl cyanophosphonate and thus, corresponding 4-acylthiol-4-deoxy-4'-demethyl epipodophyllotoxin analogues were synthesized. These compounds were screened in L1210 leukemia and KB cells, and one compound has activity similar to etoposide, and others were generally weaker than etoposide and corresponding 4-acylamido-4-deoxy-4'-demethylepipodophyllotoxin analogues.

Animals↗
PubMed1992

Structural analysis and comparison of cobrotoxin and cardiotoxins by near-IR Fourier transform Raman spectroscopy.

Venom toxins were isolated from Formosan cobra (Naja naja atra) by cation-exchange chromatography. The near-IR FT-Raman analytical method has been applied to the characterization and classification of the toxin components in their lyophilized forms. Structural analysis and comparison of various purified toxin fractions were made with respect to their amino acid compositions and near-IR Fourier-transform Raman spectra. The results indicate that the major secondary structure of cobra toxins including cobrotoxin and various cardiotoxins is mainly anti-parallel beta-pleated sheet as judged by the Raman signals at 1238 cm-1 (amide III) and 1671 cm-1 (amide I). It is also found that the relative Raman signal intensities of Tyr, Phe, Trp and Met residues in purified toxins correlate very well with the structural data obtained from amino acid analysis. The advantage and improvement of applying the near-IR FT-Raman spectroscopy to the unambiguous classification and comparison of venom toxins are evident and the discrepancies with previous Raman studies on these venom toxins are also revealed and discussed.

Animals↗
PubMed1991

Braccio da gamba.

Explore the source record for details and available documents.

Cumulative Trauma Disorders↗
PubMed1991

Functional differences among nonerythroid anion exchangers expressed in a transfected human cell line.

A new transient expression system has been developed to investigate the function of anion exchangers in vivo. Human 293 cells were cotransfected with AE2 or AE3 cDNA together with a plasmid encoding a cell surface marker protein. Staining of the cells with antibody directed against a cell surface epitope present in the marker protein permitted the detection of cells expressing functional anion exchangers. Intracellular pH (pHi) recording in individual transfectants loaded with the fluorescent pHi indicator, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein, was used to determine the flux of HCO3- as a measure of Cl-/HCO3- exchange activity. Cells expressing either anion exchanger displayed significantly enhanced Cl-/HCO3- exchange activity compared with controls expressing only the marker. Transfection with either anion exchanger or with control plasmid resulted in altered intrinsic buffering capacity profiles compared with untransfected controls. Expression of either AE2 or AE3 did not result in changes in resting pHi. The activities of both AE2 and AE3 were stimulated at alkaline pHi, suggesting that an internal protonation site in AE2 and AE3 may regulate their activities. Both exchangers were inhibited reversibly and irreversibly by the anion 4,4'-diisothiocyanostilbene-2,2'-disulfonate with IC50 values of 142 and 0.43 microM for AE2 and AE3, respectively. These data indicate that structural differences in these highly conserved anion exchangers give rise to differences in affinities at the external anion binding site.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1991

Resonance Raman detection of a carotenoid in the lens of the deep-sea hatchetfish.

A laser scanning micro-probe has been used to elicit resonance Raman signals from frozen sections of the lens of the deep-sea hatchetfish, Argyropelecus affinis. The signals demonstrate with certainty the presence of a carotenoid and its distribution in the lens. The carotenoid exhibits characteristic resonance Raman vibrational modes at 1551 cm-1 (C = C stretch, v1), 1147 cm-1 (C-C stretch with C-H bend, v2), 2285 cm-1 (2v2) and 2681 cm-1 (v1 + v2), upon excitation at 441.6 nm. Unlike glycogen in the nucleus of dove lens, the carotenoid in the lens of A. affinis occurs at a higher concentration in the cortex, although its presence in the nucleus is established. A study of lenses of varying age showed that carotenoid incorporation is accelerated as the fish grows older and hence its concentration is highest in the cortex. Because of the extremely low concentration of the carotenoid in the nucleus, it was detectable only by the very sensitive resonance Raman technique.

Aging↗
PubMed1991

Radioiodine speciation in the hot cell effluent gases of a radiopharmaceutical production facility.

In order to characterize the various chemical forms of airborne radioiodine species, grab-sampling measurements were conducted at the hot cell laboratory of a radiopharmaceutical production facility, using a selective-adsorbent-iodine filter system. Volatile radioiodine species were produced in the hot cell process which extracted the fission product 99Mo from the irradiated uranium target. The effluent gases were then released through the hot cell filter bank and the main filter bank. Two samplings were made, one at the inlet and one at the outlet of the hot cell filter bank. In comparison with other radioiodine isotopes detected, higher than expected concentrations of 132I were found, primarily in the form of organic iodide--an observation that could be explained by the beta decay of 132Te, the precursor of 132I, in the hot cell waste solution. The relative distribution of airborne 132I was considerably different from that of other iodine radioisotopes. An unexpected component of these distributions was radioiodine penetrating the silver zeolite filter and adsorbed on a triethylenediamine (TEDA) impregnated charcoal filter.

Air Pollutants, Radioactive↗
PubMed1991

Structural analysis of phospholipase A2 by near-IR Fourier transform Raman spectroscopy.

Venom toxins were isolated from Formosan cobra (Naja naja atra) by cation-exchange chromatography. Most toxin components could be obtained in relatively pure forms by single-step ion-exchange chromatography whereas an extra step of gel permeation was needed for the separation of phospholipase A2 (PLA2) from the major neurotoxic component, i.e. cobrotoxin. The newer near-IR FT-Raman analytical method has been applied to the characterization of PLA2 in their lyophilized forms. Structural analysis of PLA2 and correlation of Raman spectroscopic data with amino acid compositions were made. The results indicate that phospholipase A2 showed the Raman peak at 1659 cm-1 which is characteristic of the alpha-helical structure in this enzyme. It is also found that the relative Raman signal intensities of Tyr, Phe, Trp and Met residues in purified toxins correlate very well with the structural data obtained from amino acid analysis. The application of near-IR FT-Raman techniques in the detection of the microenvironments of the aromatic amino acids such as Tyr and Trp in the native toxins may prove useful in the investigation of the functional properties of various venom toxins.

Amino Acids↗
PubMed1991

Homology between alpha 2(V) and alpha 1(III) collagen promoters and evidence for negatively acting elements in the alpha 2(V) first intron and 5' flanking sequences.

We have isolated a 17 kilobase pair (kb) genomic clone containing the 5' portion of the human alpha 2(V) collagen gene. Nucleotide sequence was determined for 1671 base pairs (bp) comprising the promoter region, first exon and 334 bp of the first intron, and the major transcriptional start site determined by primer extension and S1 nuclease analysis. Sequence comparison revealed the alpha 2(V) promoter to be similar in structure to the promoter of the alpha 1(III) collagen gene. This is the first instance of such similarities between promoter regions of genes encoding different fibrillar collagen chains. Homology, in 5' flanking sequences, extends upstream to about nucleotide -120 in each gene and is particularly striking near the TATTTA sequence (TATA box) present in each promoter. Some homology also surrounds the two transcription start sites. The 5' untranslated regions of the two genes also show strong homology. Chimeric chloramphenicol acetyltransferase (CAT) constructs were prepared with various fragments from the 5' portion of the alpha 2(V) gene. Transient expression assays, in human fibroblasts, localized the functional alpha 2(V) promoter to the region of 5' flanking sequence conserved between the alpha 2(V) and alpha 1(III) genes. Expression assays also identified negatively acting elements, in intron and 5' flanking sequences, which inhibit transcription from the alpha 2(V) promoter.

Amino Acid Sequence↗
PubMed1990

Functional expression and subcellular localization of an anion exchanger cloned from choroid plexus.

We have isolated rat brain cDNA clones encoding AE2, a homologue of the erythrocyte anion exchanger, band 3 (AE1). Immunocytochemistry and in situ hybridization reveal that, in brain, AE2 expression is restricted to the basolateral membrane of the choroid plexus epithelium. Expression of a full-length mouse AE2 cDNA in COS-7 cells resulted in chloride- and bicarbonate-dependent alterations in intracellular pH, demonstrating that AE2 is a Cl/HCO3 exchanger. Cation replacement studies indicate that AE2-mediated exchange is independent of extracellular sodium. COS-7 cells expressing a mutant rat AE2 cDNA clone that lacks the cytoplasmic NH2-terminal 660 amino acids exhibit identical responses to cation and anion substitution. These results indicate that this domain does not play a significant role in either correct insertion of the transporter into the plasma membrane or anion exchange.

Amino Acid Sequence↗
PubMed1989

High levels of expression of full length human pro-alpha 2(V) collagen cDNA in pro-alpha 2(V)-deficient hamster cells.

A full length cDNA encoding human pro-alpha 2(V) collagen was constructed. Partial sequencing of the cDNA and primer extension analysis of mRNA from fibroblasts found that pro-alpha 2(V) mRNA differs from the mRNAs of other fibrillar collagens in the increased length of its 5'-untranslated region. The pro-alpha 2(V) cDNA was placed downstream of the human cytomegalovirus immediate early promoter/regulatory sequences for expression studies in cultured Chinese hamster lung cells. These cells have been shown previously to synthesize large quantities of pro-alpha 1(V) homotrimers as their only collagenous product. Transfection resulted in a number of clonal cell lines that express human alpha 2(V) RNA at levels comparable to, and in some cases greater than, levels found in normal human skin fibroblasts. Pro-alpha 2(V) chains produced in the majority of clonal lines were of sufficient quantity to complex all available endogenous pro-alpha 1(V) chains. Chimeric heterotrimers, composed of hamster alpha 1(V) and human alpha 2(V) chains in a 2:1 ratio, were stable to pepsin digestion and were found predominantly associated with the cell layer. Surprisingly, pro-alpha 2(V) chains, in excess to pro-alpha 1(V) chains, were found in the extracellular matrix and, in much greater abundance, in media. These chains were pepsin sensitive, indicating that pro-alpha 2(V) chains can be secreted as nonstable homotrimers or as free chains.

Animals↗