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Biomedical subjects

W Lee

Publications and source records attributed to W Lee.

At least 235 records · Page 13Linked to original sources
PubMed1995

Conversion from 2.5 mg to 1.25 mg indapamide in patients with mild to moderate hypertension.

BACKGROUND: Indapamide is an effective antihypertensive drug with diuretic and vasodilating activities. The common starting dose has been 2.5 mg to 5 mg. A lower dose formulation (1.25 mg) is now available. The safety and efficacy of switching patients from indapamide 2.5 mg to indapamide 1.25 mg was evaluated in this randomized, double-blind, multicenter clinical trial. METHODS: Three hundred seventy-eight adult patients with mild to moderate essential hypertension were enrolled in a washout period, during which patients received single-blind placebo for 4 weeks. All 378 patients qualified for the study and received open-label treatment with indapamide 2.5 mg for 8 weeks. Of the 378 patients, 265 responded to indapamide 2.5 mg and were randomized to receive double-blind treatment with either indapamide 1.25 mg (n = 132) or 2.5 mg (n = 133) for 8 weeks. Overall, 245 of the 378 patients who were initially enrolled completed the study. The primary efficacy variable was the number of patients in each treatment group who maintained a supine diastolic blood pressure of < or = 90 mm Hg (treatment success) by the end of the double-blind period (week 16). RESULTS: Treatment with indapamide 1.25 mg once daily was as efficacious as the 2.5-mg once-daily dose. No significant difference was observed for the percentage of patients who achieved treatment success between the patients switched from indapamide 2.5 to 1.25 mg (74%) and the control group maintained on indapamide 2.5 mg (70%). The incidence of drug-related adverse events during the double-blind period was similar between the two treatment groups. The mean change from pretreatment baseline to endpoint in serum potassium was -0.2 mEq/L (-0.2 mmol/L) in the indapamide 1.25 mg treatment group, compared with -0.4 mEq/L (-0.4 mmol/L) in the indapamide 2.5 mg treatment group. CONCLUSIONS: Indapamide 1.25 mg given once daily for 8 weeks was as effective as 2.5 mg once daily in reducing systolic and diastolic blood pressure in patients with mild to moderate hypertension.

Adult↗
PubMed1994

A pulsed field gradient isotope-filtered 3D 13C HMQC-NOESY experiment for extracting intermolecular NOE contacts in molecular complexes.

A pulsed field gradient three-dimensional isotope-filtered 13C HMQC-NOESY experiment has been developed to characterize intermolecular contacts in a 37 kDa macromolecular ternary complex consisting of uniformly 13C labeled trp-repressor, its natural abundance co-repressor, L-tryptophan, and natural abundance operator DNA. The pulse scheme makes use of pulsed field gradients for the removal of artifacts and dephasing of unwanted magnetization during isotope filtering, and employs a strategy to minimize the time that magnetization resides in the transverse plane. The experiment provides solely intermolecular NOE contacts between protons of the labeled protein and protons of the unlabeled species, and has proven to be especially useful in eliminating ambiguities between intra- and intermolecular NOEs in the isotope-edited 3D 13C HMQC-NOESY spectrum of the complex.

Bacterial Proteins↗
PubMed1994

The solution structures of the trp repressor-operator DNA complex.

The solution structures of the complex between Escherichia coli trp holorepressor and a 20 base-pair consensus operator DNA were determined. The majority of proton chemical shifts of the trp holorepressor and operator DNA were assigned from homonuclear 2D NOESY spectra of selectively deuterated analog-operator DNA complexes and the 3D NOESY-HMQC spectrum of a uniformly 15N-labeled repressor-operator DNA complex. The structures were calculated using restrained molecular dynamics and sequential simulated annealing with 4086 NOE and other experimental constraints. The root-mean-squared deviation (RMSD) among the calculated structures and their mean is 0.9(+/- 0.3)A for the repressor backbone, 1.1(+/- 0.5)A for the DNA backbone, and 1.3(+/- 0.3)A for all heavy atoms. The DNA is deformed to a significant extent from the standard B DNA structure to fit the helix-turn-helix (HTH) segment of the repressor (helices D and E) into its major grooves. Little change is found in the ABCF core of the repressor on complexation in comparison to the free repressor, but changes in the cofactor L-tryptophan binding pocket and the HTH segment are observed. The N-terminal residues (2 to 17) are found to be disordered and do not form stable interactions with DNA. Direct H-bonding to the bases of the operator DNA is consistent with all of our observed NOE constraints. Hydrogen bonds from NH eta 1 and NH eta 2 of Arg69 to O-6 and N-7 of G2 are compatible with the solution structure, as they are with the crystal structure. Other direct H-bonds from Lys72, Ala80, Ile79, Thr83 and Arg84 to base-pair functional groups can also be formed in our solution structures.

Amino Acid Sequence↗
PubMed1994

Proton nuclear magnetic resonance and distance geometry/simulated annealing studies on the variant-1 neurotoxin from the New World scorpion Centruroides sculpturatus Ewing.

The sequence-specific proton resonance assignments for the variant-1 (CsE-v1) neurotoxin from the venom of the New World scorpion Centruroides sculpturatus Ewing (range Southwestern United States) have been performed by 2D 1H NMR spectroscopy at 600 MHz. The stereospecific assignments for the beta-methylene protons of 19 non-proline residues have been determined. A number of short-, medium-, and long-range NOESY contacts as well as the backbone and the side-chain vicinal coupling constants for several residues have been determined. Slowly exchanging amide hydrogens from a number of residues have been identified. On the basis of the NMR data, the solution structure of this protein has been determined by a hybrid procedure consisting of distance geometry and dynamical simulated annealing refinement calculations. Distance constraints from the NOESY data and torsion angle constraints from proton vicinal coupling constant data were used in the simulated annealing calculations. The three-dimensional structure of CsE-v1 is characterized by a three-stranded antiparallel beta-sheet, a short alpha-helix, a cis-proline, and intervening loops. A comparison with the solution NMR data of a homologous protein (CsE-v3) from the Centruroides venom, shows that the structures are essentially similar, except for some minor differences. Some of the NMR spectral perturbations are felt in regions far removed from sites of amino acid substitutions. The hydrophobic surface in CsE-v1 is slightly more extended than in CsE-v3.

Amino Acid Sequence↗
PubMed1994

Determination of a novel sigma receptor antagonist, DuP 734, in rat plasma by reversed-phase high-performance liquid chromatography with ultraviolet detection.

A selective high-performance liquid chromatographic (HPLC) assay for a sigma receptor antagonist, DuP 734 (I), in rat plasma has been developed. Compound I and internal standard, XC031 (I.S.), were first extracted from plasma into an ethyl acetate-toluene mixture (3:7, v/v) and then back-extracted into freshly prepared phosphoric acid (0.03 M). Separation of I and I.S. with no interference from endogenous substances was achieved on a reversed-phase octyl column and detection was by UV at 229 nm. The mobile phase consisted of acetonitrile-glacial acetic acid-triethylamine-0.05 M ammonium acetate (670:4:2:2000, v/v). Using 0.5 ml of rat plasma for extraction, the limit of quantitation was 43 ng/ml and the assay was linear from 43 to 8536 ng/ml. The intra- and inter-day coefficients of variation ranged from 0.7 to 3.0%, and from 1.4 to 14.5%, respectively, over the entire concentration range. The accuracy was within 16.1% of the spiked concentrations. I was stable in frozen plasma at -20 degrees C for at least 68 days.

Animals↗
PubMed1994

Start site selection by Sp1 in the TATA-less human Ha-ras promoter.

The promoter of the human Ha-ras gene is very GC-rich, has four Sp1-binding sites and no TATA element. Transcription initiates at multiple start sites spread over a 90-base pair region, with a major cluster between +1 and +11. We detected the binding of a HeLa nuclear protein to the region from +6 to +20, a region which overlaps the major cluster and includes nine start sites within its boundaries. When part of this region was mutated, the nine start sites were abolished, so the region may be an initiator. The regulatory elements of the promoter have no differential effect on start site usage. But Sp1 bound to GCIV located at -38 acts as a start site selector, increasing the activity of the start sites from +1 downstream but not the upstream sites at -31, -21, and -10. When spacers of increasing length were inserted 3' to GCIV, the major cluster dwindled, and the upstream sites became strong sites, first the one at -10 and then the one at -21. Thus start sites were strongest when put into an Sp1-selected locus 36 to 53 base pairs downstream from GCIV and weak when outside this locus. The start sites with these properties may be due to initiators.

Animals↗
PubMed1994

Solution structure of the variant-3 neurotoxin from Centruroides sculpturatus Ewing.

The solution structure of the CsE-v3 neurotoxin from the venom of the North American scorpion Centruroides sculpturatus Ewing (CsE) has been determined by a hybrid refinement procedure that employed distance geometry and dynamical simulated annealing. Distance constraints deduced from the nuclear Overhauser effect spectroscopy data and torsion angle constraints deduced from the vicinal coupling constant data were used in the refinement procedure. A family of simulated annealing structures that showed no constraint violations was generated. The energy-minimized average structure exhibited root-mean-square deviations of 0.121 nm for the backbone and 0.182 nm for all atoms, with respect to this family. These studies confirm the previously qualitative NMR findings about the secondary structural features, viz. the presence of a short alpha-helix composed of residues 23-31 and an antiparallel beta-sheet composed of the strands of residues 1-5, 45-50 and 36-42. A cluster of aromatic ring systems is located on one side of the protein. The solution and crystal structures have similar overall features, but show some minor differences.

Amino Acid Sequence↗
PubMed1994

Sequential transplants using mobilized peripheral blood progenitor cells.

Modest success has been achieved with the use of high-dose cytotoxic therapy and bone marrow transplantation in solid tumors. Patient outcome can potentially be improved with further intensification of the therapy. The rapid hematologic recovery achieved with mobilized peripheral blood progenitor cells (PBPC) may reduce the toxicity of transplantation enabling the use of sequential courses of myeloablative therapy. We report on 42 patients with solid tumors enrolled in a tandem transplant protocol involving the use of PBPC mobilized with cyclophosphamide (4 g/m2), etoposide (1 g/m2), and granulocyte-colony-stimulating factor (G-CSF: 10 micrograms/kg/day). This regimen significantly increased the number of circulating progenitor cells; only 1-2 aphereses were sufficient to collect 2.5 x 10(8)/kg mononuclear cells, our goal for each transplant course. The median number of circulating colony-forming units (CFU) and CD34+ cells obtained for each transplant course were 70.3 x 10(4)/kg, and 11.7 x 10(6)/kg, respectively. There was a significant correlation between the numbers of CD34+ cells and CFU measured in the apheresis product (r = 0.49, P = .003). The first transplant regimen given to 38 patients consisted of thiotepa, carboplatin, and cyclophosphamide. The second transplant regimen given to 29 patients consisted of busulfan and etoposide. Hematologic recovery was comparable after each of the two transplant courses. The median time to neutrophil recovery over 0.5 x 10(9)/L and to platelet transfusion independence was 9 and 8 days, respectively. There was no difference in engraftment rates after transplant with PBPC only (n = 28 courses) compared to transplant with PBPC plus bone marrow (n = 39 courses).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, CD↗
PubMed1994

Phenotypic analysis and characterization of CD34+ cells from normal human bone marrow, cord blood, peripheral blood, and mobilized peripheral blood from patients undergoing autologous stem cell transplantation.

Single- and multicolor flow cytometry were used to define progenitor subsets in normal human bone marrow and peripheral blood, cord blood, and blood following mobilization of CD34+ progenitor cells by cyclophosphamide or cyclophosphamide/etoposide/G-CSF treatment. CD34 cells were quantitated and subsets of CD34+ cells were defined by coexpression of CD33, CD13, CD10, CD19, CD45RA, and CD71. Myeloid and erythroid progenitors were quantitated by sorting single CD34+ cells into individual wells of 96-well plates containing methylcellulose, IL-3, GM-CSF, G-CSF, IL-6, and erythropoietin. Comparative studies of CD34 cells showed that the percentage of CD34+ mononuclear cells was greatest in blood samples from patients following mobilization treatment with cyclophosphamide/etoposide/G-CSF averaging 2%. By comparison, the remaining sample groups ranged from 1.68 to 0.15% CD34 cells in this order, bone marrow > cord blood > cyclophosphamide mobilized blood > peripheral blood. Comparison of CD34 cells per milliliter of bone marrow or blood showed a range of 22.4 x 10(4) to 0.65 x 10(4)/ml in the following order, bone marrow > chemotherapy/etoposide/G-CSF > cord blood > cyclophosphamide-mobilized blood. Comparative analysis of CD34 subsets from different sources showed significant differences, particularly bone marrow and blood samples. A distinct population of CD34+ CD19+ (Leu 12) CD10+ (CALLA) pre-B lymphocyte cells was defined in bone marrow with lower side and forward light scatter characteristics and was variable between donors (29.8 +/- 16.9%, mean +/- 1 SD; range, 3-54%; n = 8). This population was not found to a significant degree in blood and also expressed CD45RA (Leu 18). Coexpression studies of CD45RA and CD71 (transferrin receptor) expression on CD34+ cells defined a CD45RA- CD71+ population containing 89 +/- 6.3% (n = 4) BFU-E and a CD45RA+ CD71+ population that contained all CFU-GM (n = 4). LeuM7 (CD13) stained a larger percentage to a greater intensity than MY7 (CD13). Coexpression of CD45RA (Leu 18) and CD13 (LeuM7) defined a subset of CD13+ CD45RA+ cells enriched for CFU-GM and CFU-M with a cloning efficiency of 31%. Coexpression of CD33 (MY9) and CD13 (MY7) defined a population that was predominantly CFU-GM with a cloning efficiency of 38%. These studies define CD34+ phenotypes containing pure populations of B lymphocyte, granulocyte-macrophage, or erythroid progenitors and demonstrate the utility of multiparameter flow cytometry to define lineage-committed CD34+ cells.

Adult↗
PubMed1994

Design and construction of rhinovirus chimeras incorporating immunogens from polio, influenza, and human immunodeficiency viruses.

This paper describes the design and construction of chimeric human rhinoviruses that contain immunogenic regions from other pathogens as part of their surface coat proteins. Segments encoding the poliovirus 3 Sabin VP1 and VP2 proteins, the influenza hemagglutinin (HA) glycoprotein, and the human immunodeficiency virus gp120 surface and gp41 transmembrane glycoproteins were inserted into a full-length clone of human rhinovirus 14 (HRV14) at regions corresponding to neutralizing immunogenic sites IA (NIm-IA) and II (NIm-II). Of 12 chimeric constructs described, 3 produced viable virus. An HRV14 chimeric virus containing five amino acids of influenza HA (corresponding to 300 A2 of solvent-accessible surface area) had wild-type HRV14 growth characteristics and was neutralized by four of four anti-influenza HA antisera with reciprocal neutralizing titers ranging from 180 to 330. However, antisera raised in two guinea pigs against the HRV14:influenza HA chimera did not show significant neutralization of relevant strains of influenza. These results are the first to demonstrate the feasibility of making viable chimeras of human rhinoviruses displaying heterologous immunogens.

Amino Acid Sequence↗
PubMed1994

Comparison of chromosome aberrations in leiomyoma and leiomyosarcoma using FISH on archival tissues.

Fluorescence in situ hybridization (FISH) with chromosome-specific probes was used to study cytogenetic changes in five cases of leiomyosarcoma (LMS) and nine cases of uterine leiomyoma (LM). Biotinylated DNA probes for the centromeric regions of chromosomes 1, 6, 8, 9, 17, and 18, painting probes for chromosomes 1 and 22, and the cosmid probe for chromosome region 21q22.3 were used on nuclei isolated from paraffin blocks. Four of five LMS cases revealed major chromosomal aberrations, while the only case with minor clonal aberrations was subsequently found not to be a typical LMS. The most common numerical aberrations found in the LMS cases were extra copies of chromosome 8 (three of five cases), loss of chromosome 1 (three of five cases), and loss of chromosome 6 (two of five cases). One of two LMS cases studied with a chromosome 1 painting probe demonstrated translocations of chromosome 1. In contrast to LMS, only five of nine uterine LM cases had abnormal clones, and these were smaller than those in LMS. Two LM cases showed 9% tetrasomy 8 with 17 or 20% monosomy 6, and three other cases had monosomy 6 clones in 18-34% of cells. These results indicate that typical LMS is characterized by multiple chromosomal aberrations affecting most of the cells, whereas borderline LMS and LM have fewer affected chromosomes and less clonal involvement.

Adult↗
PubMed1994

Quantitation of hepatitis C viral RNA in sera of hemodialysis patients: gender-related differences in viral load.

Hepatitis C virus (HCV) infection is common in hemodialysis patients, as determined by antibody assays and qualitative polymerase chain reaction (PCR) analysis of serum HCV RNA. To further characterize HCV infection in this population, we measured the viral load in infected hemodialysis patients by a quantitative, competitive PCR assay (QC-PCR) for HCV RNA. Hepatitis C virus RNA levels were correlated with serologic, biochemical, and demographic features of a cohort of hemodialysis patients. Sera from 208 hemodialysis patients were screened for HCV RNA (5' conserved region) by reverse transcriptase PCR (RT-PCR) and HCV-specific antibody. Forty-four patients were antibody positive (21%); among these patients, 34 (77%) were HCV RNA positive. No viremic, seronegative patients were identified. Hepatitis C virus RNA levels quantitated by QC-PCR ranged from 3 x 10(5) to 10(8) molecules of HCV RNA/mL. Male patients had significantly higher mean and median HCV RNA levels (10(7) molecules/mL) compared with female patients (3.6 x 10(6) molecules/mL and 3 x 10(6) molecules/mL, respectfully; P = 0.02). No other demographic or clinical feature of this cohort correlated with HCV RNA levels. Intravenous drug abuse was the most frequently identified risk factor (29% of seropositive patients) for infection with HCV in this population. No association between HCV RNA levels and hepatic enzyme levels (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase) was apparent. Hepatitis C virus infection is highly prevalent in our hemodialysis population, and hemodialysis patients, particularly males, have high levels of HCV in serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Solution structure of the tetrameric minimum transforming domain of p53.

We report the solution structure of the minimum transforming domain (residues 303-366) of human p53 (p53tet) determined by multidimensional NMR spectroscopy. This domain contains a number of important functions associated with p53 activity including transformation, oligomerization, nuclear localization and a phosphorylation site for p34/cdc2 kinase. p53tet forms a symmetric dimer of dimers that is significantly different from a recent structure reported for a shorter construct of this domain. Phosphorylation of Ser 315 has only minor structural consequences, as this region of the protein is unstructured. Modelling based on the p53tet structure suggests possible modes of interaction between adjacent domains in full-length p53 as well as modes of interaction with DNA.

Amino Acid Sequence↗
PubMed1994

Anti-arrhythmic efficacy of beta-adrenergic blockade during acute ischemia in myocardium with scar.

Ventricular arrhythmia production in the ischemic heart is considered to be influenced by prior infarction. Although beta-adrenergic blockade is known to have beneficial effects during acute ischemia, its anti-arrhythmic efficacy during post-infarction ischemia is not known. To explore this question, we have used a model with a relatively high incidence of ischemic arrhythmias. Mongrel dogs 2 to 3 years of age were studied intact under anesthesia. An irreversible injury of the infero-posterior myocardium was produced with an electrode catheter 1 week earlier. The arrhythmic response to acute ischemia was assessed using serial, transient 15-minute occlusions of the left-anterior descending coronary artery with a balloon catheter. During ischemia alone, the incidence of ventricular fibrillation in animals who underwent all phases of the study was 6 of 9; with atenolol (0.2 mg/kg intravenously) and ischemia, 1 of 9 (p < 0.05). To assess the role of the bradycardic response, the latter was repeated 1 week subsequently during atrial pacing at the heart rate that existed before ischemia. Fibrillation occurred in 8 of 9, a significant reversal of the therapeutic effect. To exclude the potential artifact of a fixed intervention protocol, a study was undertaken with the short-acting esmolol, in which three ischemic periods were alternated at 1-hour intervals: (A) ischemia without treatment, (B) ischemia with continuous infusion of 150 micrograms/kg/min esmolol, and (C) same as B except that heart rate was maintained by atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1994

Evaluation of a combined two- and three-dimensional compression method using human visual characteristics to yield high-quality 10:1 compression of cranial computed tomography scans.

RATIONALE AND OBJECTIVES: The compression of cranial computed tomography scans was improved by using independent intra- and interframe compression techniques. METHODS: For intraframe compression, an image was decomposed into four subimages, one subimage was chosen as a reference subimage, and three of the subimages were predicted from the reference subimage. The prediction error was encoded with a classified vector quantizer (CVQ) based on human visual perception characteristics. Interframe redundancy is exploited by a displacement estimated interslice (DEI) algorithm that encodes the differences between reference subimages from adjacent slices. This combined DEI/CVQ method was subjectively evaluated by 13 radiologists under a blinded protocol, and was compared to the CVQ method alone, the DEI method alone, the original images, and to a standard intraframe discrete cosine transform (DCT) compression method. RESULTS: Only the combined DEI/CVQ method at 10:1 compression was not scored significantly different from the original images. At 15:1 compression, the DEI/CVQ method was scored significantly better than the 10:1 DCT and any other 15:1 compression methods. CONCLUSIONS: Compressed image quality is enhanced by exploiting inter- and intraframe redundancy, and by modeling some characteristics of human visual perception. The DEI/CVQ method is well-suited for progressive transmission, and thus, holds potential in teleradiology as well as picture archiving and communications systems.

Analysis of Variance↗