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J Hall

Publications and source records attributed to J Hall.

At least 379 records · Page 21Linked to original sources
PubMed1988

The nucleotide sequence of a carboxymethylcellulase gene from Pseudomonas fluorescens subsp. cellulosa.

The complete nucleotide sequence of the gene coding for one of the carboxymethylcellulases (CMCase), expressed by Pseudomonas fluorescens subsp. cellulosa, has been determined. The structural gene consists of an open reading frame, commencing with an ATG start codon, of 2886 base pairs followed by a TAA stop codon. The gene was shown to code for a signal peptide which closely resembles the signal peptides of other secreted proteins. Unlike most Pseudomonas genes, the CMCase sequence does not have a high G + C (51%) content and there is no marked preference for codons ending in G or C. Upstream of the structural gene there are no sequences which bear a strong resemblance to consensus Escherichia coli promoters. A sequence is present, however, which exhibits homology to the consensus DNA sequence that binds the catabolic activator protein (CAP). Bal31 deletions of the structural gene revealed the extent by which the gene could be modified and still encode a functional CMCase. Subclones of the cellulase gene have been constructed in pUC18 and pUC19. One of the resultant plasmids, pJHS1 directs a 20-fold increase in CMCase synthesis, when compared to the original construct, pJHH2. Analysis of cells harbouring pJHS1 showed the cellulase polypeptide to have a molecular weight of 106000. This is in close agreement with the predicted size of the enzyme deduced from the nucleotide sequence data.

Amino Acid Sequence↗
PubMed1988

Repair of O-alkylpyrimidines in mammalian cells: a present consensus.

Enzymatic repair of the O-alkylpyrimidines (O2- and O4-alkylthymine, O2-alkylcytosine) and alkyl phosphotriesters has been studied in Escherichia coli, and the two proteins involved, a glycosylase (DNA-3-methyladenine glycosylase) and a methyltransferase (DNA-O6-methylguanine:protein-L-cysteine S-methyltransferase, EC 2.1.1.63), have been well characterized. In mammals or mammalian cells treated with carcinogenic alkylating agents, loss of these derivatives has been demonstrated repeatedly. Nevertheless, mammalian repair proteins that are analogous to those from E. coli do not detectably act on these alkyl derivatives. A variety of techniques has been used by many investigators in the United States and Europe, who conclude here that the mode of O-alkylpyrimidine and alkyl phosphotriester repair in mammalian cells differs from that in E. coli. New approaches and methods are needed to characterize these processes at the biochemical and molecular level.

Alkylating Agents↗
PubMed1988

The contribution of O6-methylguanine and methylphosphotriesters to the cytotoxicity of alkylating agents in mammalian cells.

A modified Escherichia coli ada+ gene which encodes methyltransferase active on O6-methylguanine, but not methylphosphotriester residues in DNA has been introduced by transfection into Chinese hamster ovary cells. Expression of the altered Ada protein in these cells conferred resistance to methylating agents. However, in two independently derived cell lines, the relation between enzyme activity and the degree of protection was not quantitative. The molecular nature of the Ada protein fragment produced differed between the two cell lines. In addition, cell lines exhibiting increased resistance to N-methyl-N'-nitro-N-nitrosoguanidine have been derived from a cell line expressing the Ada protein methylphosphotriester repair function. The resistant cell lines expressed elevated levels of methylphosphotriester repair protein. However, this enhanced DNA repair activity was not responsible for the observed resistance.

Alkylating Agents↗
PubMed1988

Molecular cloning of multiple xylanase genes from Pseudomonas fluorescens subsp. cellulosa.

Pseudomonas fluorescens subsp. cellulosa was shown to express extracellular xylanases. Genes encoding these enzymes were isolated from a gene library of P. fluorescens subsp. cellulosa DNA, constructed in bacteriophage lambda 47.1. One of the phages (PXC) that expressed xylanase also conferred the ability to hydrolyse carboxymethylcellulose. An 11.8 kb HindIII DNA restriction fragment and a 6.2 kb EcoRI DNA fragment were subcloned from two distinct xylanase-expressing phages, into pUC18, to yield recombinant plasmids pGHJ4 and pGHJ5 respectively. Cells of Escherichia coli harbouring either of these two plasmids, or plasmid pJHH1 (comprising the cellulase gene from PXC, previously cloned on a 7.3 kb partial EcoRI DNA fragment in pUC18), expressed xylanase activity. The positions of the xylanase genes in the recombinant plasmids were elucidated by subcloning and transposon mutagenesis. In pJHH1 the xylanase gene was adjacent to the DNA region encoding the endoglucanase. The polysaccharide-degrading genes in pJHH1 were transcribed from different promotors. Hybridization studies revealed that the xylanase genes encoded by pGHJ4 and pGHJ5 showed strong homology. All three cloned enzymes cleaved p-nitrophenyl beta-D-glucopyranoside and 4-methylumbelliferyl beta-D-cellobioside. Xylan and glucose did not affect expression of xylanase in E. coli strains harbouring pJHH1, pGHJ4 or pGHJ5.

Cloning, Molecular↗
PubMed1988

Pulmonary vasoconstrictor response to soluble fibrin in isolated lungs: possible role of thromboxane generation.

The blood coagulation system is activated regularly in severe forms of shock, polytrauma, and sepsis. Arising thrombin cleaves the fibrinopeptides A and B from fibrinogen, and it generates monomers of fibrin, which are initially kept in solution by the remaining excess fibrinogen. The effects of soluble fibrin (fibrin monomer/oligomer-fibrinogen complexes) and fibrinopeptides A and B were investigated in blood-free perfused, isolated rabbit lungs. Urea Tris buffer-dissolved fibrin monomers were injected into the pulmonary artery in the presence of circulating excess fibrinogen. In doses above 5 mg, the monomers consistently provoked a sharp rise in pulmonary artery pressure, which was followed by an elevated pressure plateau. Changing to fresh perfusate devoid of soluble fibrin did not restore the pressure to baseline, and a second administration of the soluble fibrin caused a pressor response larger than the first. Only a modest increase in lung weight (less than 2 g) was observed, and lung inflation pressure was not altered. The pressor responses were accompanied by a rapid release of thromboxane A2 and a more delayed release of prostaglandin I2 into the perfusion fluid. A significant correlation between the height of the fibrin-induced pressure rise and the amount of thromboxane release was noted. Inhibition of cyclooxygenase (indomethacin) suppressed the generation of both prostanoids, whereas inhibition of thromboxane synthetase (OKY-046 and imidazole) selectively blocked the liberation of thromboxane. All three inhibitors caused an immediate decline in pulmonary artery pressure, which had been previously elevated due to administration of soluble fibrin, and markedly reduced the pressor response evoked by a subsequent fibrin application in the same lung.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1988

The different types of alpha-thalassemia: practical and genetic aspects.

From May 1985 to October 1987, 1,564 Southeast Asians living in Hawaii were screened for hereditary anemias. Microcytosis was determined by electronic red cell indices and morphology; iron deficiency was ruled out by normal red cell distribution width and normal protoporphyrin levels; Hb E was determined by electrophoresis; beta-thalassemia (thal) heterozygotes were identified by raised Hb A2 on column chromatography. alpha-Thalassemia heterozygotes were diagnosed by exclusion. Family studies helped identify or confirm diagnoses, especially for the alpha-thal-2 heterozygotes (-alpha/alpha alpha) and homozygotes (-alpha/-alpha). Provisional diagnoses are being checked by DNA analyses. Iron deficiency prevented detection of possibly coexisting alpha-thalassemias in 97 individuals. Technical problems included the obscuring of standard criteria for recognizing the alpha-thal variants by the presence of Hb E or beta-thal. In such cases, alpha-thal could only be detected by family studies or DNA analyses. Problems with hemoglobin (Hb) electrophoresis included Hb H migrating beyond the edge of the strip if incubation was not closely monitored, and difficulty in detecting the small amounts of unstable Hb Constant Spring. DNA analyses also had limitations, since the nondeletion alpha-thalassemias would not be detected by routine Southern blotting. DNA analyses suggested that about 50% of presumed alpha-thalassemias were alpha-thal-2 (-alpha/alpha alpha) variants, and a corresponding number of alpha-thal-2 variants were among the apparent normals. Gene frequencies in the unselected Lao subjects were approximately 0.2 for Hb E, at least 0.1 for (-alpha), usually a rightward (alpha -3.7) type, 0.04 for (-), and 0.01 for a beta-thal. Multistep screening for the alpha- and beta-thalassemias was an effective and efficient strategy.

Asia, Southeastern↗
PubMed1988

Thalassemia heterozygotes in Hawaii: ethnic attitudes toward screening and prenatal diagnosis.

The attitudes toward screening and prenatal diagnosis for the hemoglobinopathies Hb E and alpha-thalassemia, prevalent in Southeast Asia, it were studied in Southeast Asians living in Hawaii. Since May 1985, one Laotian and two Filipino Outreach Workers were trained to make home visits to educate and recruit prospective subjects for a federally-funded thalassemia screening project. Volunteers over age 18 were interviewed to assess their comprehension about thalassemia and their attitudes toward screening, family planning, and prenatal diagnosis using structured questionnaires to measure subjective responses. Prenatal diagnosis was explained to all subjects using simple brochures in Laotian and in three Filipino dialects. Culturally oriented genetic counceling was offered to all heterozygotes, emphasizing that their status was common and benign. By July 1987, 597 adult participants had been interviewed; 262 were male, 335 female (65 pregnant); 250 were Laotian, 221 Filipino, 90 Chinese, and 36 of other races. Among female interviewees, 268 said they would want prenatal diagnosis and 196 said they would abort an affected fetus. Most interviewees, especially those who were pregnant, were in favor of: 1) public education about screening, 2) having relatives tested, and 3) prenatal diagnosis when indicated. These attitudes seemed to be influenced by Western culture and religious constraints. Comprehension of genetic concepts correlated closely with education. Ten pregnancies occurred in 16 couples where both partners were heterozygous for a thalassemia (thal) (at least two non-referred couples had homozygous alpha-thal-1 fetuses during this time). Five had amniocentesis for risk of alpha-thal homozygosity, two for risk of beta-thal homozygosity, two miscarried, and one was referred too late for fetal testing. After amniocentesis, one couple declined termination for a fetus with Hb E/beta-thal, and was sceptical of the results when their infant seemed normal at birth; one couple kept a homozygous beta-thal fetus, possibly modified by alpha-gene deletions.

Abortion, Eugenic↗
PubMed1988

Partial characterization of a soluble mitogenic factor from medulloblastoma.

To determine how medulloblastoma cells might influence the proliferation and phenotype of normal stromal cells, normal human leptomeningeal cells were treated in culture with medulloblastoma-conditioned medium; their ability to incorporate tritiated thymidine and synthesize collagen was measured. The treated leptomeningeal cells had a significantly greater uptake of tritiated thymidine and grew faster than control leptomeningeal cells. Immunofluorescence studies demonstrated a greater intensity of staining for procollagen type III in the cell layer of the treated cultures than in control cultures; diethylaminoethyl (DEAE)-cellulose chromatography of the medium showed that the treated cells synthesized predominantly type III collagen, whereas control cells synthesized type I collagen. Analysis of the medulloblastoma-conditioned medium revealed that the soluble factor responsible for these effects in an acid- and heat-stable protein. The increased proliferation and altered collagen synthesis induced in leptomeningeal cell cultures by a soluble factor from a medulloblastoma are examples of how tumor and stromal elements interact, and may be related to the process of desmoplasia often observed in medulloblastomas in vivo.

Cell Division↗
PubMed1988

Staff satisfaction in short stay wards.

Two Short Stay Wards (SSWs) have been opened in a large teaching hospital in Sydney's outer Western suburbs, as a means of overcoming budget constraints and a shortage of nurses prepared to work conventional rosters. This paper reports a survey of the attitudes of medical and nursing staff using these two SSWs. Overall, medical personnel were found to hold positive attitudes to the SSWs and reported higher patient turnover as a result of their opening. Identified barriers to usage of the wards included scheduling of operating suite time, and lack of flexibility in the booking, admission and movement of SSW patients. Nurses who work in the SSWs have chosen to work under these special nursing conditions. They were found to be particularly satisfied with their work hours, rapport with patients and other staff, the high patient turnover and varied case mix. Sources of dissatisfaction included Friday night duty and deployment, and the administrative procedures practised by medical staff, including difficulties in contacting them.

Attitude of Health Personnel↗
PubMed1988

Efficacy of water vapor-saturated air in the treatment of exercise-induced pulmonary hemorrhage in Thoroughbred racehorses.

The efficacy of water vapor-saturated air as a treatment for horses with exercise-induced pulmonary hemorrhage (EIPH) was studied. Horses selected for study (n = 14) had grade 1 or greater hemorrhage in the trachea after a minimum of 4 breezes between 0.8 and 1 km, as determined by endoscopy. Nine horses were treated with water vapor-saturated air; 5 horses were not treated. When the mean and maximal EIPH scores from the pretreatment period were compared with the mean and maximal EIPH scores from the treatment period in both treated and nontreated groups, there was no significant difference between groups. There was a suggestion of a linear relationship between exercise speed and the mean EIPH score of the first 4 breezes in all 14 horses.

Animals↗
PubMed1988

Whole body lymphangioscintigraphy in ferrets chronically infected with Brugia malayi.

Whole body lymphangioscintigraphy was performed after intradermal injection of 99mtechnetium human serum albumin or antimony colloid in the distal hindlimbs and forelimbs of ferrets chronically infected with Brugia malayi. The findings were compared with control ferrets and those with surgical interruption of the iliac lymphatics. While only one infected ferret manifested chronic hindlimb lymphedema, all exhibited delayed transport of radioisotope from the hindpaw with obstruction in the groin, poor or absent visualization of central lymphatic channels and regional lymph nodes, a picture similar to that following surgically induced lymphatic obstruction. In control ferrets, there was prompt visualization of peripheral lymphatic channels and regional lymph nodes with sharper and more extensive channel visualization after radiolabeled albumin and more intense sustained nodal visualization after radiolabeled antimony colloid. This noninvasive technique provides a readily repeatable investigative tool adaptable to small animals to study the evolution of lymphatic filariasis and other conditions associated with lymphatic obstruction.

Animals↗
PubMed1987

The reaction domain on Rhodospirillum rubrum cytochrome c2 and horse cytochrome c for the Rhodospirillum rubrum cytochrome bc1 complex.

The interaction of the Rhodospirillum rubrum cytochrome bc1 complex with R. rubrum cytochrome c2 and horse cytochrome c was studied using specific lysine modification and ionic strength dependence methods. In order to define the reaction domain on cytochrome c2, several fractions consisting of mixtures of singly labeled carboxydintrophenyl-cytochrome c2 derivatives were employed. Fraction A consisted of a mixture of derivatives modified at lysines 58, 81, and 109 on the back of cytochrome c2, while fractions C1, C2, C3, and C4 were mixtures of singly labeled derivatives modified at lysines 9, 13, 75, 86, and 88 on the front of cytochrome c2 surrounding the heme crevice. The rate of the reaction of fraction A was found to be nearly the same as that of native cytochrome c2. However, the rate constants of fractions C1-C4 were found to be more than 20-fold smaller than that of native cytochrome c2. These results indicate that lysine residues surrounding the heme crevice of cytochrome c2 are involved in electrostatic interactions with carboxylate groups at the binding site on the cytochrome bc1 complex. Since the same domain is involved in the reaction with the photosynthetic reaction center, cytochrome c2 must undergo some type of rotational or translational diffusion during electron transport in R. rubrum. The reaction rates of horse heart cytochrome c derivatives modified at single lysine amino groups with trifluoroacetyl or trifluoromethylphenylcarbamoyl were also measured. Modification of lysines 8, 13, 25, 27, 72, 79, and 87 surrounding the heme crevice was found to significantly lower the rate of the reaction, while modification of lysines in other regions had no effect. This indicates that the reaction of horse cytochrome c also involves the heme crevice domain.

Animals↗