Search PubMed⌕ Search

Biomedical subjects

D Andrews

Publications and source records attributed to D Andrews.

90 records · Page 5Linked to original sources
PubMed1985

Partial primary structure of the alpha and beta chains of human tumor T-cell receptors.

The T-cell receptor for antigen (Ti) was purified from the human tumor cell line HPB-ALL. Amino-terminal sequence analysis of an acid-cleaved peptide of the Ti alpha chain showed that it is highly homologous to a putative murine alpha chain recently described. Amino-terminal sequence analysis of the Ti beta chain revealed that it shares 50 percent homology with the Ti beta chain amino acid sequences from two other human T-cell tumors. Nucleotide sequence analysis of a complementary DNA clone encoding the Ti beta chain from the HPB-MLT cell line showed that this chain represents a second human constant region gene segment and suggested that it arises from direct joining of the variable and joining gene segments without any intervening D region sequences.

Amino Acid Sequence↗
PubMed1985

Tryptophanamide formation by Escherichia coli tryptophanyl-tRNA synthetase.

When tryptophanyl-tRNA synthetase from Escherichia coli is allowed to react with L-tryptophan and ATP-Mg in the presence of inorganic pyrophosphatase, the fluorescence change of the reaction mixture reveals three or four sequential processes, depending on the buffer used. Quenched-flow and stopped-flow experiments show that the first two processes, which occur in the 0.001-1.0-s time scale, can be correlated to the formation of two moles of tryptophanyl-adenylate per mole of dimeric enzyme. These two processes are reversible by adding PPi, as seen in the fluorimeter. The third process leads to a reaction product that can no longer reform ATP after addition of PPi and that represents tryptophanyl-ATP ester, as demonstrated by thin-layer chromatography. This compound has been previously shown to be formed by tryptophanyl-tRNA synthetase from E. coli [K. H. Muench (1969) Biochemistry 8, 4872-4879]. Its formation is accompanied by a fluorescence decrease which reaches a minimum in about 30 min. The nature of the fourth process depends on the reaction conditions employed. In sodium bicarbonate or potassium phosphate buffer, the fourth process corresponds to the non-enzymatic hydrolysis of tryptophanyl-ATP ester. This spontaneous hydrolysis competes with formation of the ester and limits its concentration. Eventually, the progressive exhaustion of ATP brings the fluorescence intensity of the reaction mixture back to its initial value. In contrast, in ammonium bicarbonate buffer the previous third process is no longer visible, as evidenced by the absence of a fluorescence decrease beyond the fast initial quenching linked to the formation of tryptophanyl-adenylate. Instead, a fluorescence increase is observed. However, unlike the fourth process seen in sodium bicarbonate buffer, the fluorescence increase in ammonium bicarbonate is much larger than the initial fluorescence decrease linked to adenylate formation, the final fluorescence greatly surpassing the starting fluorescence signal. The reaction product of this process is tryptophanamide, as evidenced by high-performance liquid chromatography. Tryptophanamide formation is faster than that of tryptophanyl-ATP ester and is enzyme-catalyzed with a Km of 1 mM for ammonia and a rate constant of 5.7 min-1 at pH 8.3, 25 degrees C. The affinity of tryptophanamide for the protein is too weak to allow the formation of a significant concentration of enzyme-product complex. Tryptophanamide is therefore released in the reaction medium and its concentration reaches that of the limiting substrate.

Amino Acyl-tRNA Synthetases↗
PubMed1984

A method for screening diuretic agents in the rat.

A reproducible screening method for diuretic agents has been developed based upon the selection of a group of homogenous rats with a similar excretory pattern of water and electrolytes. Normal saline (4% body weight) was used as a hydrating fluid to select appropriate rats and to validate the diuretic activity of standard diuretics. The method required only a small number of rats for screening compounds and produced consistent responses in increasing water and electrolyte excretion.

Animals↗
PubMed1984

Percutaneous transluminal dilatation of peripheral arteries: an analysis of factors predicting early success.

Four hundred ninety-five patients undergoing peripheral arterial percutaneous transluminal dilatation (TLD) with the Gruntzig balloon catheter were studied prospectively to determine which factors could be used to predict a successful result from the procedure. Ten variables were recorded before the TLD. The procedure was considered a success at follow-up if both the clinical grade and the objective vascular laboratory results improved. The results of a logistic discriminant function analysis showed that three variables were associated with success of a TLD at 3 months: the site of the TLD, the severity of the lesion (i.e., stenosis or occlusion), and the runoff. With these results, logistic regression analysis was used to estimate the chances of a successful result for all combinations of these significant variables. It is concluded that the early result of a TLD is determined by the site of the TLD, the severity of the lesion, and the runoff. A table of the estimated chances of success for any combination of these variables has been constructed and accurately describes our patient population.

Aged↗
PubMed1984

Mycobacterium thermoresistibile infection in an immunocompromised host.

This is the second report of Mycobacterium thermoresistibile as the etiological agent of a pulmonary granuloma and the first occurrence of this organism in a patient who has not been outside the continental United States. The organism is susceptible to rifampin, ethambutol, and streptomycin but resistant to isoniazid and p-aminosalicylic acid.

Granuloma↗
PubMed1984

Disinfection of the flexible fibreoptic bronchoscope against Mycobacterium tuberculosis and M gordonae.

In view of recent reports of contamination of the fibreoptic bronchoscope by tuberculous and non-tuberculous mycobacteria, we evaluated the disinfecting properties of aqueous glutaraldehyde (Cidex) and an iodophor (Prepodyne) against Mycobacterium tuberculosis and M gordonae. We found that a 15 minute disinfection procedure with either agent, coupled with initial vigorous mechanical cleaning of the bronchoscope and its accessories, is a quick and reliable method for preventing the contamination of the bronchoscope with mycobacteria.

Bronchoscopy↗
PubMed1983

Biochemical studies of the excitable membrane of Paramecium tetraurelia. VII. Sterols and other neutral lipids of cells and cilia.

The neutral lipid content of cells and cilia of Paramecium tetraurelia was determined as a function of growth stage and of growth medium composition. The major sterol(s) of deciliated cells and of cilia were the sterol provided in the growth medium (e.g., stigmasterol) and its 7-dehydro derivative. Body sterol esters and triglycerides accumulated during exponential cell growth and became depleted during stationary phase. Isolated cilia contained neither sterol esters nor triglycerides. The ratio of phospholipid to free sterol in cilia was constant (approximately 5:1) throughout exponential growth in axenic or bacterized medium, but the relative proportions of free sterol and 7-dehydrosterol varied with growth phase and with growth medium composition. Cholesterol did not support the growth of Paramecium, but was taken up rapidly into cells and cilia as the free sterol and its 7-dehydro derivative. The fatty acids of sterol esters and of triglycerides were similar to those of membrane phospholipids.

Animals↗
PubMed1979

Biochemical studies of the excitable membrane of Paramecium tetraurelia. II. Phospholipids of ciliary and other membranes.

The phospholipids of cilia and deciliated bodies of Paramecium tetraurelia were isolated and characterized. 1-alkyl-2-acyl-sn-glycero-3-(2'-aminoethyl) phosphonate (GAEPL), phosphatidylethanolamine, and 1-alkyl-2-acyl-sn-glycero-3-phosphorylcholine (GPC) were the major lipids of Paramecium, and the minor lipids included phosphatidylinositol, cardiolipin, ceramide-(2-aminoethyl) phosphonate (CAEP), ceramide phosphorylethanolamine (COPE) and four sphingolipids whose identity was not established. The deciliated bodies contained 4% cardiolipin, 15% GAEPL, 41% phosphatidylethanolamine, 30% GPC and 3% each of CAEP and phosphatidylinositol; the cilia contained no cardiolipin, 24% GAEPL, 37% phosphatidylethanolamine, 15% GPC, 15% CAEP, 3% phosphatidylinositol, 2% COPE and small amounts (approx. 1%) of the four uncharacterized sphingolipids. No alteration in phospholipid composition was found among cells harvested in the various stages of growth. The phospholipids of six Paramecium mutants of three distinct phenotypes (pawn, paranoiac and fast) were also examined. Only one significant difference was found on comparison of the whole cell, deciliated body and cilia fraction of the mutants with the analogous fractions from wild type cells: the fast mutant, fA 97, had two extra, minor phospholipids (approx. 2%) in the deciliated body fraction that were tentatively identified as 1,2-diacyl-sn-glycero-3-(2'-aminoethyl) phosphonate (AEPL) and 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamine (GPE).

Animals↗
PubMed1979

Leaching of lead from ceramics.

The amount of lead leached from various glazed ceramic was determined by extraction with 5% acetic acid for one hour at 85 degrees C. All commercial ceramic items, both domestic and imported, were below the FDA standard of 7 mg/liter lead in the extractant. On the other hand, almost 60% of the domestic homemade ceramic items exceeded FDA standards. Comparison with previous studies show significant reduction in lead leaching from commercial ceramic containers. However, homemade ceramic items continue to pose a potential hazard of excessive lead release.

Ceramics↗
PubMed1975

Lead extraction from aluminum.

The lead content of various aluminum samples was determined. The amount of lead was found to be in the range from 28-45 ppm. The leaching of lead from aluminum products by 5% acetic acid was negligible at room temperature, but up to 2 mg/liter was leached at 85 degrees C. Although no significant health hazard exists in the usage of aluminum in contact with food items, it is recommended that aluminum containers be conditioned by several extractions with dilute acetic acid at higher temperatures.

Acetates↗
PubMedDate not supplied

In vivo validation of tissue segmentation based on a 3D feature map using both a hamster brain tumor model and stereotactically guided biopsy of brain tumors in man.

The purpose of this study was to validate our MR tissue segmentation technique using a hamster brain tumor model and malignant brain tumors in man. We used a multispectral tissue segmentation analysis. Three sets of MRI data were included: proton density, T2-weighted fast spin echo, and T1-weighted spin echo, as inputs. Three image preprocessing steps included correcting image nonuniformity, application of an anisotropic diffusion type filter, and data point selection by a qualified observer. We used the k-Nearest Neighbor segmentation algorithm, which does not require prior knowledge of the sample distribution. This choice allowed us to optimize the different tissue clusters present in three-dimensional (3D) feature space. In vivo validation of the technique was performed in hamsters harboring tumors induced with JC virus-transformed HJC-15 cells, as compared to three control animals. Human brain tumors obtained by stereotactically guided biopsy in six patients were also included in the study. Finally, brain tumors were removed from two patients who underwent conventional craniotomy using segmentation-derived images as a guide. In the hamsters, 10 tissues were correctly identified by segmentation and were confirmed histologically (P < .02). In the patients, there was also a strong correlation between our segmentation results and the tissue obtained by stereotactic biopsy (P < .01). In one of the two patients who underwent open craniotomy, segmentation images were useful in revealing tumor spread into vital areas of the brain (motor area). In conclusion, the results of segmentation correlate well with the tissues in vivo and thus warrant further clinical utilization and evaluation.

Adult↗
PubMedDate not supplied

Improving diabetic patients' outcomes in family medicine in the United Arab Emirates.

We evaluated a diabetic mini-clinic by assessing adherence to American Diabetes Association guidelines and changes in glycosylated haemoglobin levels. Of 1063 patients, 721 were multiple attenders. Single and multiple attenders showed no significant differences in age, sex, time since diagnosis or body mass index. Female and male multiple attenders showed significant declines in glycosylated haemoglobin levels over the first 12 and 18 months respectively. After 2 years, these levels were similar to those at entry to the clinic. The clinic's compliance with standard measurement guidelines was high. The diabetic mini-clinic model, which is effective in industrialized countries, was equally effective in this setting.

Ambulatory Care Facilities↗