Quantitative determination of sulfanilamide in sodium sulfacetamide raw material and ophthalmic solutions by high-performance liquid chromatography.
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Chromatography, High Pressure Liquid↗
Biomedical subjects
L Hall
Publications and source records attributed to L Hall.
Site-directed mutagenesis of yeast phosphoglycerate kinase. The 'basic-patch' residue arginine 168.
There is evidence, some of it of questionable authenticity, which suggests that phosphoglycerate kinase takes up a more compact form following the binding of substrates. Using this evidence it has been assumed that a conformational rearrangement is required for phosphoryl transfer to occur and that this is brought about by moving the enzyme's two domains towards each other. In order to test this hypothesis we have modified, by site-directed mutagenesis, an arginine residue thought to be involved in stabilising the transition-state intermediate. Although some 1.3 nm away from the site of phosphoryl transfer, as seen in the crystallographically determined structure, the substitution of arginine 168 by lysine (R168K) more than halves the specific activity of the enzyme. Substituting the arginine with a methionine (R168M) reduces activity further, but not completely, thus proving that the charge associated with this residue is not essential for catalytic activity. Both mutations raise the Michaelis constants (Km) for ATP and glycerate 3-phosphate. The largest change is observed with the triose substrate and the methionine mutant, suggesting that the primary function of arginine 168 is to influence the environment of this substrate. The effect on activity of adding sulphate to R168K and R168M mutant enzyme has also been investigated. The sulphate activation effect at low substrate concentrations is reduced for the methionine substitution but almost abolished for the lysine substitution. The most reasonable explanation of all these findings is that, in the wild-type enzyme, the guanidinium group of arginine 168 forms a hydrogen bond with one of the triose substrate's C1 oxygens. This steric arrangement would not be possible in the 'open form' of this enzyme as observed in the crystal structure.
Arginine↗
An evaluation of the extraction efficiencies of some common extractants for Fe, Cr, Mn, Ni, Pb and Cu on five grain-size fractionated, tropical marine sediments.
A number of extractants and extraction procedures were evaluated using a variety of tropical marine sediments fractionated on the basis of grain size. Total metal levels obtained by X-ray fluorescence analysis were used in the normalization of levels obtained by these extractants/extraction procedures. A change in extraction efficiency with change in the pH of the extractant used was observed for Fe and Mn irrespective of particle size of the fraction. Iron was extracted uniformly at each leaching level for the <53micro fractions. Manganese had comparable extraction efficiencies with both weak and strong extractants. The extraction efficiencies for Cr were generally low possibly due to an association with the residual phase. The ease with which both Pb and Ni were extracted indicated that they were only loosely bound in the sediments. The extraction efficiencies for Cu varied widely for the fractions of larger particle sizes but fell within narrow ranges for the <53micro fractions.
Journal Article↗
Isolation of a novel mildly repetitive DNA sequence that is predominantly located at the terminus of the short arm of chromosome 4 near the Huntington disease gene.
A novel mildly repetitive DNA sequence that is reiterated approximately 20 times in the human genome has been isolated and characterized. Most of the repeat units are localized very near the terminus of the short arm of chromosome 4 (4p) in the region known to contain the Huntington disease (HD) gene. A cloned probe that detects the repeated sequence reveals a restriction fragment length polymorphism that is close to and/or distal to the most distal genetic locus on 4p. This probe, therefore, provides a new genetic marker very close to and possibly flanking the HD gene. In addition, this probe should prove very useful for detailed physical mapping of the most distal region of 4p around the HD gene. The few (two or three) copies of this repeat not located near the terminus of 4p are located near the ends of two other chromosomes, 14 and 21.
Animals↗
Nuclear magnetic resonance studies of isolated structural domains of yeast phosphoglycerate kinase.
The structural integrity and substrate binding properties of the two genetically engineered domains of yeast phosphoglycerate kinase were investigated using one- and two-dimensional nuclear magnetic resonance techniques. Both domains were found to fold with regions of native-like structure, with the N-domain showing greater conformational flexibility than the C-domain. The 'basic patch' region of the N-domain is, however, clearly perturbed by removal of the C-domain. This is most likely due to the absence of stabilizing interactions between the C-terminal peptide (including alpha-helices XIII and XIV) and the N-domain. The C-domain is able to bind nucleotide with an affinity only three times less than that of the native protein.
Hydrogen-Ion Concentration↗
Efficient expression and characterization of isolated structural domains of yeast phosphoglycerate kinase generated by site-directed mutagenesis.
The two domains of yeast phosphoglycerate kinase were produced by recombinant techniques. The N-domain was obtained by the introduction of a termination codon at the position coding for Phe185, and the C-domain by a deletion in the gene of the coding sequence between Ser1 and Leu186. Both domains were efficiently expressed in yeast, the level for the C-domain being greater than that for the N-domain. Both domains were found to have a quasi-native structure; the C-domain retained its ability to bind nucleotides. Small local differences were detected in domain structure compared to that in the whole enzyme, probably due to the lack of interdomain stabilizing interactions. Nevertheless, such an approach provides direct evidence for independent folding of domains in a two-domain protein.
Cloning, Molecular↗
Hemodynamic effects following ingestion of an imidazoline-containing product.
Toxic ingestions constitute a major health problem for infants and young children, with an estimated 500,000 poisonings in 1980, 90% of them in children less than five years old. Mortality and associated expense are considerable. Sympathetic amines, while less commonly involved in pediatric poisonings, deserve special attention because of their potent cardiovascular side effects, eg, tachycardia and hypertension. Tetrahydrozoline, the active ingredient in several nasal and ophthalmologic over-the-counter medications, has previously been implicated in childhood ingestions. We report a case of tetrahydrozoline ingestion in which, paradoxically, lethargy, bradycardia, and hypotension were noted.
Bradycardia↗
Serum beta 2-microglobulin levels in haemophiliacs.
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Biomarkers↗
A retrospective death certificate study of AIDS and AIDS-related conditions in Ohio: 1984-1986.
AIDS surveillance data are used routinely to define the magnitude of the epidemic, project future case numbers, delineate risk behaviors, and to assist in health planning and resource allocation. The purposes of this study are: (1) to evaluate the effectiveness of the Ohio Department of Health (ODH) AIDS Surveillance System in Ohio from 1984 through 1986 and (2) to identify additional cases which may have been overlooked through normal case identification procedures. A review of all deaths occurring in Ohio among males between the ages 20 and 50 was conducted for several diseases and conditions commonly associated with AIDS.
Acquired Immunodeficiency Syndrome↗
Length of hospital stay in surgical service patients with nosocomial Hemophilus influenzae infections.
The length of hospitalization was characterized for 24 surgical service patients with nosocomial respiratory tract infections associated with Hemophilus influenzae. The mean number of days were: admission to surgery 8.22; surgery to culture of the nosocomial pathogen 7.00; admission to culture 16.71; admission to discharge 38.75; surgery to discharge 25.48; and culture to discharge 21.42. The length of hospital stay was prolonged for those patients with nosocomial respiratory tract infections related to H influenzae.
Cross Infection↗
Nucleotide sequence of the phosphoglycerate kinase gene from the extreme thermophile Thermus thermophilus. Comparison of the deduced amino acid sequence with that of the mesophilic yeast phosphoglycerate kinase.
Using oligonucleotide probes derived from amino acid sequencing information, the structural gene for phosphoglycerate kinase from the extreme thermophile, Thermus thermophilus, was cloned in Escherichia coli and its complete nucleotide sequence determined. The gene consists of an open reading frame corresponding to a protein of 390 amino acid residues (calculated Mr 41,791) with an extreme bias for G or C (93.1%) in the codon third base position. Comparison of the deduced amino acid sequence with that of the corresponding mesophilic yeast enzyme indicated a number of significant differences. These are discussed in terms of the unusual codon bias and their possible role in enhanced protein thermal stability.
Amino Acid Sequence↗
Structure and expression of the guinea-pig alpha-lactalbumin gene.
The entire guinea-pig alpha-lactalbumin gene was isolated from a genomic DNA library constructed in the bacteriophage lambda L47. The complete nucleotide sequence of the gene and its immediate 5' and 3' flanking sequences were determined and compared with those of the human and rat alpha-lactalbumin genes. This demonstrates that the size, organization and sequence of the exons is highly conserved between species, and reveals the presence of the highly conserved potential regulatory 'milk box' consensus sequence [RGAAGRAAA(N)TGGACAGAAATCAA(CG)TTTCTA] between positions -140 and -110 relative to the transcriptional start point. A guinea-pig LINE repeat sequence was also present in the 5' flanking region between positions -520 and -1195. Transfection of the alpha-lactalbumin gene cloned in a bovine papilloma virus vector into the mouse C127 and human MCF-7 mammary tumour cell-lines gave rise to stable but seemingly constitutive expression of alpha-lactalbumin. Expression was from the correct transcriptional start point, resulting in the accumulation of correctly processed mRNA and the secretion of alpha-lactalbumin into the culture medium.
Animals↗
Quantitative determination of disodium edetate in ophthalmic and contact lens care solutions by reversed-phase high-performance liquid chromatography.
A specific and sensitive HPLC method has been developed for the quantitative determination of disodium edetate (1) in a variety of ophthalmic and contact lens care solutions. Using this method, a common contaminant, nitrilotriacetic acid (2), is easily separated from 1. Sample preparation involves a single dilution step prior to mixing with an aqueous cupric nitrate solution to form a copper:EDTA complex for analysis. An aliquot of the resulting mixture is analyzed by HPLC using either a 10-microns styrene divinyl benzene column or, for separations requiring greater selectivity and resolution because of interfering components in the sample matrix, a 5-microns octadecyl column with a mobile phase of acetonitrile:0.006 M aqueous tetrabutylammonium phosphate, pH 6.5 (20:80). The column effluent is monitored by UV detection at 254 nm. The method is linear, quantitative, and reproducible for a wide variety of formulations. Using this method, the average recovery of 1 from spiked samples was 100%, with a relative standard deviation of less than 2%. The minimal quantifiable level of 1 was approximately 2.8 ng (equivalent to an analytical concentration of 1.5 microgram/mL).
Chromatography, High Pressure Liquid↗
Genetic variability between isolates of human immunodeficiency virus (HIV) type 2 is comparable to the variability among HIV type 1.
The isolation from macaques of retroviruses related to human immunodeficiency virus (HIV) led to the identification of a second group of human retroviruses (termed HIV-2), which are prevalent in West Africa and closely related to the simian immunodeficiency virus (SIV). We have cloned and determined the complete nucleotide sequence of the human West African retrovirus HIV-2NIH-Z and compared it to that of a previously described strain of HIV-2 (HIV-2ROD) as well as to SIV and HIV-1. We have reached the following conclusions: (i) The HIV-2 isolates are (slightly) more closely related to each other than to SIV, compatible with their isolation from different species. (ii) The variability between HIV-2 isolates is similar in degree and kind to that found among HIV-1 isolates. The equivalent degrees of intragroup divergence suggest that HIV-1 and HIV-2 have existed in their present ranges in Africa for approximately equal lengths of time. The fact that acquired immunodeficiency syndrome is widespread in regions where HIV-1 is prevalent but not in regions where HIV-2 is prevalent suggests a substantial difference in the morbidity rates associated with HIV-1 vs. HIV-2 infection. (iii) HIV-2 and SIV are related to each other more closely than they are to HIV-1.
Amino Acid Sequence↗
Surgical service nosocomial infections at a Veterans Administration medical center.
Nosocomial surgical infections at a Veterans Administration medical center were monitored from February 1986 to June 1987 (17 months). Three hundred twenty-four patients had 508 nosocomial infections, including 66 patients in whom cultures were not performed. The remaining 258 patients had 584 microorganisms, including gram-negative bacilli (56.8 percent), gram-positive cocci (33.6 percent), and yeasts (8.4 percent). The most common isolates were Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, group D enterococci, and Staphylococcus epidermidis. Antimicrobial susceptibilities were similar for nosocomial and all hospital isolates combined 84.5 percent of the time; all hospital isolates combined were more resistant in 5.5 percent and nosocomial isolates in 10.0 percent. The infection rate for surgical wounds was only 2.5 percent. When all nosocomial infection sites were compared, however, the rate for lower respiratory tract and some other infections appeared high and disproportionate. The significance of this finding is questionable because of a lack of comparable published reports from other Veterans Administration medical centers. The importance of patient population at risk of obtaining some nosocomial infections (especially lower respiratory) may be greater in adult men than in other patient populations.
Adult↗
Surgeon and family physician opinions of the general surgical needs of family practice residents: a pilot study.
There is a lack of data assessing needs and evaluating educational objectives in general surgery for family practice residents. Studies suggest that family practice residency graduates feel underprepared in some surgical areas. This study provides results of a survey of 28 surgeons, practicing family physicians and family practice residents in the Northeast regarding the importance of 166 surgical objectives. The groups are compared to each other to detect differences in perceptions about what family practice residents should be taught in general surgery. Surgeons attached significantly less importance to nine of 21 general categories of learning objectives (e.g. emergency skills) than did practicing family physicians or family practice residents. No differences in ratings of surgical objectives were observed for 12 of 21 general categories.
Clinical Competence↗
Organization and sequence of the human alpha-lactalbumin gene.
A recombinant bacteriophage containing the entire alpha-lactalbumin gene was isolated from a human genomic library constructed in bacteriophage lambda L47. Within this recombinant the 2.5 kb alpha-lactalbumin gene is flanked by about 5 kb of sequence on either side. The complete nucleotide sequence of the gene and its immediate flanking sequences were determined and compared with those of the rat alpha-lactalbumin gene. These studies showed that the size, organization and sequence of the exons have been highly conserved, whereas the introns have diverged considerably. In particular, the first intron of the human gene was found to contain an Alu repetitive sequence not present in the rat. A high degree of homology (67%) was also observed in the 5' flanking regions, extending as far as 655 nucleotide residues upstream of the transcriptional initiation site. Comparison of the 5' flanking sequences of these two alpha-lactalbumin genes with those of five casein genes has revealed the presence of a highly conserved region [consensus sequence: RGAAGRAAA(N)TGGACAGAAATCAA(CG)TTTCTA], extending from position -140 to -110 in all seven sequences examined, suggesting a possible regulatory role in the hormonal control or tissue-specific expression of milk protein genes in the mammary gland.
Animals↗
Illustrations from the Wellcome Institute Library. The archive of the Lister Institute of Preventive Medicine.
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Academies and Institutes↗