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Biomedical subjects

L Hall

Publications and source records attributed to L Hall.

At least 127 records · Page 7Linked to original sources
PubMed1992

Structure and expression of the rat epididymal secretory protein I gene. An androgen-regulated member of the lipocalin superfamily with a rare splice donor site.

The complete rat epididymal secretory protein I (ESP I) gene was isolated from a genomic library constructed in bacteriophage lambda Charon 4A. The complete nucleotide sequence of the gene and its immediate 5' and 3' flanking sequences were determined. Interesting features include the presence of a rare, but functional, splice donor site (...GC) and the presence of a putative androgen-receptor-binding element. A detailed analysis of ESP I regulation was carried out after castration and subsequent testosterone treatment, demonstrating the requirement for androgens. Efferent-duct ligation and cryptorchism, on the other hand, had no effect on the steady-state concentrations of ESP I transcripts. Comparison of the exon/intron organization of the ESP I gene with those of members of the lipocalin superfamily provides strong support for a common ancestral origin.

Amino Acid Sequence↗
PubMed1992

Effect of reciprocal complementation of two defective human immunodeficiency virus type 1 (HIV-1) molecular clones on HIV-1 cell tropism and virulence.

Human immunodeficiency virus type 1 (HIV-1) displays both interstrain and intrastrain genetic variability. Virus populations with extensive microheterogeneity have been defined as swarms or quasispecies. Many of the genomes within HIV-1 swarms appear to be defective in one or more genes required for viral replication. It is unclear to what extent defective viruses play a role in the process of HIV-1 infection or in the pathogenesis of AIDS. We have isolated two biologically active HIV-1 clones: LW 12.3, which contains defects in the vif and vpr genes, and MN ST.1, which has a defect in the vpu gene. LW 12.3 is unable to replicate in peripheral blood mononuclear cells (PBMC). The growth of MN-ST.1 in SupT1 cells is marked by a 3-week lag in extracellular virus production and by the presence of unusually abundant viral buds. We demonstrate here that coinfection of PBMC with these two partially defective HIV-1 clones extends the cellular host range of LW 12.3, significantly increases the replication rate of both viral genomes, and eliminates the delay in production observed with the vpu-defective MN ST.1. When the lesions in vpr and vif of LW 12.3 are repaired, the resultant virus grows normally in PBMC. This is also the case when only vif is repaired, indicating that complementation of LW 12.3 in PBMC by MN ST.1 is mediated by vif in trans. The reciprocal complementation results in a dramatic increase of HIV-1 virulence. This two-component model represents a simplified version of the in vivo situation and illustrates one way in which interaction of defective viruses could increase the spread of infection and progression of disease.

Base Sequence↗
PubMed1992

Use of coculture of colonic mucosal biopsies to investigate the release of eicosanoids by inflamed and uninflamed mucosa from patients with inflammatory bowel disease.

Eicosanoid production was measured in cultured biopsies of colonic mucosa from control patients, with the irritable bowel syndrome, and from patients with proctosigmoiditis and with colonic Crohn's disease. Cultured inflamed colonic mucosa from patients with proctosigmoiditis and Crohn's disease produced more prostaglandin E2 and leukotrienes C4 than control tissues. In addition, eicosanoid production by macroscopically uninflamed or 'quiescent' mucosa from the right colon was examined in patients with proctosigmoiditis and between skip lesions in Crohn's disease patients. In the proctosigmoiditis group quiescent mucosa produced eicosanoids in similar quantities to control tissue. Coculture of quiescent plus inflamed tissue however, generated a marked increase in eicosanoid output in 12 of 20 of the patients and this was similar to the quantity obtained from two pieces of inflamed tissue. In the Crohn's disease group, quiescent mucosa produced more eicosanoids than control mucosa but production was markedly stimulated by coculture with inflamed mucosa in all patients. These findings suggest that in some patients with proctosigmoiditis and in all patients with Crohn's disease quiescent mucosa appears to be sensitised. A small but significant increase in the macrophage population may be partly responsible but it is likely that these and other cells are primed to release eicosanoids, and may be induced to do so by soluble mediators produced by actively inflamed tissue.

Adult↗
PubMed1992

Venous stenoses in patients who undergo hemodialysis: treatment with self-expandable endovascular stents.

During a 32-month period, 25 modified self-expandable endovascular stents were placed in 20 hemodialysis access sites to treat 21 stenoses and four occlusions in 19 patients. All stenoses were initially dilated with a high-pressure balloon. The initial success rate was 90% (18 of 20 access sites). The stents were patent from 0 to 960 days (mean duration of follow-up, 309 days). At 2 years follow-up, the patency rates were as follows: primary, 25%; secondary, 34%; and tertiary, 42%. The morbidity rate associated with this procedure was 15% (three of 20 sites); the mortality rate, 5% (one of 19 patients). All five complications (graft or native-vein thrombosis [n = 2], nerve deficits [n = 2], and death secondary to sepsis [n = 1]) occurred in three patients early in the study, before the use of prophylactic antibiotics and refinements in technique. The best results occurred in patients in whom the stenosis or occlusion affected a large vein that had no acute angle and was away from venous confluences such as the femoral and iliac regions.

Constriction, Pathologic↗
PubMed1992

Clinical reasoning process for service provision in the public school.

This paper outlines the clinical reasoning process used to guide decisions on the provision of occupational therapy services in the Wake County Public School System in North Carolina. The process is based on a theoretical framework derived from occupational therapy theory and public law. Benefits of using the clinical reasoning process include (a) increased consistency of decision making among therapists; (b) increased appropriateness of decisions regarding whether a student needs educationally based occupational therapy services, what type of occupational therapy service would meet the student's need, and how often this service should be provided; and (c) improved ability of therapists to articulate to all those involved with a student the reasoning behind decisions to provide educationally based occupational therapy services. The schematic diagrams that depict this process provide a useful tool for therapists with varied work experiences entering school-based practice.

Child↗
PubMed1991

Sequence and expression of the gene encoding 3-phosphoglycerate kinase from Bacillus stearothermophilus.

The structural gene (pgk) encoding 3-phosphoglycerate (PGK) from Bacillus stearothermophilus NCA1503, has been cloned in Escherichia coli and its complete nucleotide sequence determined. The gene consists of an open reading frame corresponding to a protein of 394 amino acids (aa) (calculated Mr 42,703) and, in common with other prokaryotic pgk genes, is preceded by the structural gene encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Constructs containing the B. stearothermophilus pgk gene and its flanking sequences in the high-copy plasmid, pUC9, co-express both PGK and GAPDH at high levels in transformed E. coli cells, typically producing PGK at levels of up to 30% of the soluble cell protein. The deduced aa sequence of B. stearothermophilus PGK is compared with those of the mesophilic (yeast) and extreme thermophilic (Thermus thermophilus) enzymes since the crystal structure of these PGKs are known or are in the process of being determined. Changes in the sequences of the three enzymes, as they appear to relate to the enhancement of thermal stability, are discussed.

Amino Acid Sequence↗
PubMed1991

A 23 kDa protein from rat sperm plasma membranes shows sequence similarity and phospholipid binding properties to a bovine brain cytosolic protein.

A 23 kDa protein that is a major component of rat epididymal secretions and sperm plasma membranes has been purified and partially sequenced. A data-base search revealed approximately 85% sequence similarity with a phosphatidyl-ethanolamine-binding protein from bovine brain cytosol. The rat 23 kDa protein also showed selective affinity for phosphatidylethanolamine (Kd = 1.6 x 10(-5) M) with lower activity towards phosphatidylinositol and phosphatidylcholine. It is suggested that differential affinity of protein antigens towards asymmetrically aligned phospholipids in sperm plasma membranes could account for their organisation into specific regional domains.

Amino Acid Sequence↗
PubMed1991

cDNA cloning of porcine interleukin 2 by polymerase chain reaction.

Porcine interleukin 2 (IL-2) cDNA was cloned by polymerase chain reaction (PCR), using primers derived from the corresponding bovine sequence. The resulting porcine DNA sequence encodes a 154 residue IL-2 primary translation product. Comparison of the mature, secreted form of porcine IL-2 with those of other species was carried out in an attempt to identify differences that might contribute to the observed differing species specificities.

Amino Acid Sequence↗
PubMed1991

Conformational changes in yeast phosphoglycerate kinase upon ligand binding: fluorescence of a linked probe and chemical reactivity of genetically introduced cysteinyl residues.

The effects of ligands on the conformation of yeast phosphoglycerate kinase were explored by introducing cysteinyl residues at different positions in the molecule by site-directed mutagenesis. Thus several mutants were constructed, each containing a unique cysteinyl residue. Neither the conformation nor the enzyme activity was affected by the substitutions. The reactivity of the thiol groups and the fluorescence of N-acetyl-N'-(5-sulfo-1-naphthyl)ethylene-diamine covalently linked to these thiols were used to monitor the conformational changes induced upon ligand binding. It was found that the observed changes mainly involve the part of the protein located in the cleft, particularly the environment of residues 35 and 183. No alteration was observed on the external side of the protein. Only 3-Phosphoglycerate induced these conformational changes. However, when the fluorescent probe was attached to residue 377, the binding of the two substrates was required to induce a modification in the fluorescence of the probe. These results indicate that the substrates separately or together induce discrete molecular motions in phosphoglycerate kinase.

Adenosine Triphosphate↗
PubMed1991

Do children with severe head injury benefit from intensive care?

Intensive management of severe closed head injury is pursued in most neurosurgical units, as it no doubt reduces mortality. However, the fate of those salvaged from death is less clearly defined. The impact of aggressive management on the psychological recovery is even less clear. This retrospective study of children admitted to a regional paediatric neurosurgical service attempts to address these issues. Eighty-four children between the ages of 3 to 16 years with severe head injuries were studied and categorized according to conservative or intensive treatment groups. The availability of intensive management led to a greater number of such children referred. The mortality in those children sustaining more severe injury, i.e. Glasgow Coma Score (GCS) 3 or 4, was halved (44%) with intensive management from 80% in the conservative group. For those with less severe injury (GCS 5-8), it was unchanged at about 23%. The reduced mortality is at the expense of increased morbidity. Psychological testing showed that the cognitive recovery was comparable.

Adolescent↗
PubMed1991

A genetic linkage map of human chromosome 5 with 60 RFLP loci.

A genetic map of human chromosome 5 that contains 60 restriction fragment length polymorphism (RFLP) loci in one linkage group has been constructed. Segregation data using these markers and 40 large multigenerational families supplied by the Centre d'Etude du Polymorphisme Humain have been collected. Linkage analyses were performed with the program package CRI-MAP; using odds greater than 1000:1, 30 RFLP loci could be placed on the map. This genetic map spans 289 cM sex-equal, 353 cM in females, and 244 cM in males. While the relative rate of recombination for female meioses is nearly twice that of males over much of the chromosome, several instances of statistically significant excess male recombination were observed. The order of probes on the genetic map has been confirmed by their physical order as determined by somatic cell hybrid lines containing deletions of normal chromosome 5. There is concordance between the physical positions of markers and their genetic positions. Our most distal probes on the genetic map are cytologically localized to the most distal portions of the chromosome. This suggests that our genetic map spans most of chromosome 5.

Blotting, Southern↗
PubMed1991

Evaluation of a brief psychological treatment for emotional disorders in primary care.

A randomized trial in general practice compared: (i) a brief psychological treatment (problem-solving) given by a psychiatrist; (ii) any treatment of the GP's choice, whether psychological or pharmacological. The patients had recent onset emotional disorders of poor prognosis. Patients in the problem-solving group showed significantly greater reductions in symptoms. Problem-solving as given by a psychiatrist was feasible in primary care and acceptable to patients. Problem-solving is now being evaluated as given by general practitioners trained in the method.

Adolescent↗
PubMed1991

Relative activities of HIV-1-IIIB and HIV-1BaL LTR and tat in primary monocytes and lymphocytes.

The mechanisms determining the ability of some but not other strains of human immunodeficiency virus type 1 (HIV-1) to grow in peripheral blood monocyte-macrophages are presently unclear. The tat gene of HIV-1-IIIB which replicates poorly in human macrophages, and the tat gene of HIV-1-BaL, which replicates to high titers in the same cells in transient expression systems with their respective long terminal repeats (LTR) driving a reporter chloramphenicol acetyl transferase (CAT) gene were compared. The authors hypothesized that the tat gene and LTR of BaL might help account for its efficient growth in primary monocyte-macrophages by virtue of a high activity in these cells relative to that of the IIIB tat and LTR. Primary peripheral blood lymphocytes and monocytes were cotransfected with either the HIV-1BaL or HIV-1-IIIB LTR fused to the CAT gene and their respective tat genes. The IIIB tat and LTR were at least as active in primary lymphocytes as the BaL combination, and both tat-LTR pairs were more active in primary lymphocytes than monocytes. The same relative activities were also observed in primary monocytes after in vitro maturation to macrophages prior to transfection. These data strongly suggest that neither the tat gene nor the LTR of HIV-1-IIIB and HIV-1BaL can account for the great ability of the latter or the inability of the former to grow in monocyte-macrophages.

Amino Acid Sequence↗
PubMed1991

Very high affinity interaction of DPI 201-106 and BDF 8784 enantiomers with the phenylalkylamine-sensitive Ca2(+)-channel in Drosophila head membranes.

1. Piperazinylindoles (DPI 201-106, BDF 8784), drugs known to act on voltage-dependent Na(+)-channels, bind with very high affinity to a Ca2(+)-channel-associated phenylalkylamine receptor in Drosophila melanogaster head membranes. These compounds and (+)-tetrandrine, a naturally occurring Ca2(+)-antagonist, were the most selective inhibitors for phenylalkylamine-labelled Drosophila Ca2(+)-channels compared to mammalian L-type Ca2(+)-channels. 2. Replacement of the cyano group by a methyl group in (+)-DPI 201-106 ((+)-BDF 8784) increases the IC50 value for inhibition of phenylalkylamine labelling of Drosophila Ca2(+)-channels from 0.29 to 2.1 nM but decreases the IC50 value for inhibition of phenylalkylamine labelling of mammalian skeletal muscle Ca2(+)-channels from 3480 to 49 nM. 3. DPI 201-106 enantiomers completely block (at 0.1 microM) phenylalkylamine photolabelling of a 136 K polypeptide in Drosophila head membranes whereas 10 microM aconitine or lidocaine are without effect. 4. Assessment of the Ca2(+)-antagonist effects of the substituted DPI 201-106 enantiomers in K(+)-depolarized taenia strips from guinea-pig caecum yielded pA2 values of 6.33 +/- 0.07 for (-)-BDF 8784 and 6.99 +/- 0.17 for (+)-BDF 8784, respectively. 5. Piperazinylindoles, previously believed to act nonspecifically on voltage-dependent mammalian L-type Ca2(+)-channels, therefore have stereoselectivity for a novel binding site and chemical selectivity unrelated to local anaesthetic activity. 6. It is proposed that a very high affinity piperazinylindole-selective site is coupled to the phenylalkylamine receptor of Drosophila Ca2(+)-channels. These sites are still present on mammalian L-type Ca2(+)-channels but have lower affinity and/or are less tightly coupled to phenylalkylamine receptors on the alpha 1-subunit.

Affinity Labels↗