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Biomedical subjects

D J Smith

Publications and source records attributed to D J Smith.

At least 289 records · Page 16Linked to original sources
PubMed1991

Hepatitis C update. New answers, new questions.

Currently available tests for infection with the hepatitis C virus detect the presence of antibodies against the virus. The value of these tests is limited, however, because the appearance of antibodies may be delayed and because there is a significant rate of false-positive results. Supplementary tests now being developed should greatly facilitate diagnosis of hepatitis C. Patients with chronic liver disease due to the hepatitis C virus can be treated with interferon alfa-2b (Intron A). This treatment should also be considered for patients with markedly elevated transaminase levels, evidence of significant histologic injury, or symptoms referable to the liver.

Chronic Disease↗
PubMed1991

The effect of autogenous bone graft application on wound contamination.

A rat model was created in which contaminated wounds were closed in either the presence or absence of autogenous bone graft. The recipients of bone graft were divided into two groups--one receiving autogenous cancellous bone, the other receiving nonviable autogenous autoclaved cortical bone. Quantitative bacterial cultures were collected both at the time of wound closure and 2 weeks after closure. A significantly increased level of soft-tissue contamination was associated with wound closure in the presence of either type of bone graft, indicating an overall adverse effect on soft tissues. A critical level existed such that at initial bacterial contamination levels greater than 10(4) organisms/g tissue, final contamination levels were significantly elevated. With initial contamination levels less than 10(4) organisms/g tissue, however, final bacterial contamination levels were not significantly different. These results may help explain the different rates of infection that have been reported when delayed primary closure of open fractures is done in conjunction with autogenous bone graft.

Animals↗
PubMed1991

Acute lung injury following reperfusion after ischemia in the hind limbs of rats.

In this study, we proposed that oxygen free radicals participate in the acute pulmonary injury that follows limb ischemia/reperfusion. Using an established model of hind limb ischemia, reproducible lung injury occurred after reperfusion. Lung microvascular permeability was measured with 125I-BSA and increased two-fold after 30 minutes of reperfusion. Pulmonary injury was blocked with DMSO, DMTU, allopurinol, indomethacin, and SOD plus catalase. The degree of pulmonary neutrophil sequestration as assessed by tissue myeloperoxidase activity was significantly diminished in animals pretreated with antioxidants. Pretreatment with indomethacin did not attenuate the neutrophil sequestration within the pulmonary parenchyma. These data suggest that increased lung microvascular permeability and neutrophil accumulation occur following hind limb ischemia/reperfusion. Therapeutic interventions with oxygen radical inhibitors blocked this process, while the prostaglandin inhibitor, indomethacin, only reduced lung permeability.

Allopurinol↗
PubMed1991

Custom-made free vascularized compound toe transfer for traumatic dorsal loss of the thumb.

Dorsal compound traumatic thumb loss can be reconstructed in selected young and well-motivated patients with a custom-made partial great toe transfer. The transfer, including the nail complex and vascularized piece of bone, can be fashioned by longitudinally cutting the distal phalanx to approach the appearance of the opposite thumb and to allow for more normal nail appearance. Ten patients illustrate this technique and emphasize its reconstructive potential as well as cosmetic acceptance.

Adolescent↗
PubMed1991

An assessment of the Kemble Star 700 sample processor for the automation of complement fixation and ELISA tests in a microbiology laboratory.

A Kemble Robotic sample processor was programmed to perform routine serological tests for microbiology. Accuracy of dispensed volumes was assessed and precision of dilutions was compared with manual methods. An appraisal of time taken to perform complement-fixation and enzyme-linked immunosorbent assays by manual and automated methods was undertaken. Labour requirements were reduced when processing large numbers of samples and the reproducibility of more demanding tests was improved by the greater accuracy of the robotic manipulations.

Automation↗
PubMed1991

Effect of adoptive transfer of cloned Actinobacillus actinomycetemcomitans-specific T helper cells on periodontal disease.

Previously we isolated several Actinobacillus actinomycetemcomitans-specific T-cell clones from the spleens and lymph nodes of immunized Rowett rats. These clones were characterized as W3/13+, W3/25+, OX8-, and OX22-, suggesting a T helper (Th) phenotype. In the current experiments, 10(6) cells from a single A. actinomycetemcomitans-specific clone (A3) were adoptively transferred to a group (AaTh; n = 13) of normal heterozygous rats (rnu/+) at 28 days of age. A second group received no T cells (AaNT; n = 15), and a third group also received no T cells (NAaNT, n = 11). Beginning 1 day after transfer, the first and second groups were infected orally with A. actinomycetemcomitans for 5 consecutive days. The presence of infection was confirmed immediately after challenge and after 5 months, when the experiments were ended. Significantly higher numbers of lymphocytes were recovered from the gingival tissues of the first group than from those of either of the other groups. Also, this group showed significantly elevated (P less than 0.01) serum immunoglobulin G and immunoglobulin M antibody to A. actinomycetemcomitans in an enzyme-linked immunosorbent assay when compared with both other groups. Bone loss was significantly lower (P less than 0.01) in recipients of A. actinomycetemcomitans-specific cloned cells when compared with the other infected group and was approximately equal to the bone loss of the uninfected group. These results are consistent with the hypothesis that T-cell regulation can affect periodontal disease. In this regulation, T helper cells appear to interfere with periodontal bone loss.

Actinobacillus↗
PubMed1991

Impaired alanine uptake by basolateral liver plasma membrane vesicles from rats consuming ethanol.

Chronic ethanol consumption reduces alanine transport by rat basolateral liver plasma membrane (blLPM) vesicles; however, the mechanism for this effect remains uncertain. It may be related to the ethanol-induced changes in blLPM fluidity and lipid composition; alternatively ethanol might reduce the number of transporters in the blLPM. To investigate the effect of blLPM fluidity and lipid composition on Na(+)-dependent alanine uptake these parameters were altered in vitro. Increasing the blLPM fluidity had no effect on Na(+)-dependent alanine uptake by blLPM vesicles or the activity of amino acid transport systems, A and ASC. Because ethanol is known to reduce the blLPM cholesterol content, the influence of altering blLPM cholesterol on alanine transport by these membranes was investigated next. Neither an increase nor a decrease of the cholesterol content of the blLPM altered Na(+)-dependent alanine uptake or the activity of system A or ASC. Finally, the influence of chronic ethanol consumption on the specific binding of [3H]alanine to blLPM was studied. The dissociation constant for alanine binding to blLPM from ethanol-fed rats and their pair-fed controls was similar (1.9 +/- 0.2 vs. 2.0 +/- 0.3 mM); however, the maximal binding capacity for alanine was significantly (P less than 0.05) lower in the blLPM from ethanol-fed rats (316 +/- 53 pmol/mg protein) compared with their pair-fed controls (527 +/- 79 pmol/mg protein). These studies do not support the hypothesis that ethanol-induced changes in blLPM fluidity are responsible for the impaired alanine transport; they do suggest that ethanol may reduce the

Alanine↗
PubMed1991

Immunoglobulin isotypes in human minor gland saliva.

Lower labial, upper labial, palatine (minor), and parotid (major) gland saliva samples from 18 young adult males were quantitatively assayed for the presence of IgA1, IgA2, IgM, and IgG. The mean (+/- standard deviation) concentrations of IgA (sum of IgA1 + IgA2) were 79 +/- 42 micrograms/mL (parotid), 111 +/- 42 micrograms/mL (lower labial), 69 +/- 72 micrograms/mL (upper labial), and 88 +/- 68 micrograms/mL (palatine). Total IgA concentrations were positively correlated among different minor-gland samples from the same subject, although these correlations did not reach significance. Upper-labial-gland saliva samples contained significantly (at least p less than 0.05) lower concentrations of IgA1 than those found in parotid or lower-labial minor-gland secretions. All three minor-gland sources of saliva contained significantly (p less than 0.002) higher levels of IgG than did parotid saliva. Upper-labial fluids had significantly (p less than 0.02) higher IgG concentrations than lower-labial saliva. IgM could be detected in 89% of parotid saliva samples and 75% of the palatine saliva samples. Palatine IgM concentrations (8.2 +/- 17.8 micrograms/mL) were significantly (p less than 0.05) higher than parotid IgM concentrations (0.6 +/- 0.4 micrograms/mL). IgM was detected much less frequently and at lower concentrations in lower- and upper-labial-gland saliva. These data reveal that minor-gland saliva from different oral sites may contain distinctive immunoglobulin isotype patterns, and expressions of host defense may vary within each micro-environment.

Adolescent↗
PubMed1991

Comparative time estimation skills of Hispanic children.

76 Hispanic and 47 Caucasian children from an urban school district located in a racially mixed neighborhood were compared on their ability to make functional time estimates. The findings indicate that initial differences in ability to make time estimations dissipate across Grades 1 to 5.

Child↗
PubMed1991

Disseminated histoplasmosis with bilateral adrenal enlargement: diagnosis by computed tomography-directed needle biopsy.

Disseminated histoplasmosis is a rare and potentially fatal disease caused by the dimorphic soil fungus Histoplasma capsulatum. We describe a 67-year-old man with diabetes who presented with a 6-month history of fever, weight loss, and mental deterioration; using computed tomography (CT), we found hepatosplenomegaly and bilateral adrenal masses. CT-directed adrenal biopsy showed yeast forms consistent with H capsulatum. Therapy with ketoconazole was accompanied by adrenal insufficiency (treated successfully with prednisone and fludrocortisone) and produced an excellent therapeutic response. We address the differential diagnosis of bilateral adrenal enlargement, and we discuss the clinical features, diagnosis, and treatment of disseminated histoplasmosis, a disease that includes parts of the Southwestern United States in its endemic region.

Adrenal Glands↗
PubMed1990

Isolation and characterization of ciliary neurotrophic factor from rabbit sciatic nerves.

Ciliary neurotrophic factor (CNTF) has been purified 35,000-fold to homogeneity from rabbit sciatic nerves using its ability to promote the survival of chick embryo ciliary ganglion neurons as the bioassay. The purification involved a combination of acid treatment, ammonium sulfate fractionation, hydrophobic interaction chromatography, chromatofocusing, preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and reversed-phase high performance liquid chromatography. Overlapping peptide sequences were obtained which accounted for 49% of the primary structure of the molecule. This information was used to prepare synthetic peptides in order to elicit antibodies. Purified CNTF exhibited two major and several minor bands between 24 and 22 kDa on silver-stained sodium dodecyl sulfate-polyacrylamide electrophoresis gels. All of the molecular forms were immunostained in Western blots by antiserum to synthetic peptides. The peptide sequences also provided a basis for cloning and expression of the rabbit CNTF gene (Lin, L-F. H., Mismer, D., Lile, J. D., Armes, L. G., Butler, E. T., III, Vannic, J. L., and Collins, F. (1989) Science 246, 1023-1025) confirming that the protein purified as reported here is CNTF.

Amino Acid Sequence↗
PubMed1990

Nitrate analysis by capillary gas chromatography.

A microanalytical gas chromatographic (GC) method for the analysis of nitrate in rat urine is described. The method involves the conversion of nitrate to nitromesitylene and quantitation using 3,4-dimethylnitrobenzene as an internal standard. The nitroaromatics were separated on a wide-bore capillary column and detected with a nitrogen-phosphorus thermionic detector. The method exhibited linearity over the range of 1.0 to 1000 microM nitrate, and the detection limit was 0.5 microM nitrate (200-microliters sample). The coefficient of variation (CV) range for intra-day precision was 2.2 to 5.8% (20 microM level) and 3.1 to 6.5% (200 microM level). Inter-day CVs ranged from 2.0 to 6.1% for the samples tested. The average recovery was 77% (20 microM level) and 80% (20 microM level). The accuracy of the GC method compared favorably with results obtained from a standard colorimetric nitrate assay. Interference by urinary chloride was eliminated by pretreatment of samples with saturated silver acetate. Both processed and unprocessed samples were stable for at least 60 days at -15 degrees C. The procedure was used to measure urinary nitrate in rats fed a custom low-nitrate diet.

Animals↗
PubMed1990

The multifunctional peptide synthetase performing the first step of penicillin biosynthesis in Penicillium chrysogenum is a 421,073 dalton protein similar to Bacillus brevis peptide antibiotic synthetases.

The nucleotide sequence of the Penicillium chrysogenum Oli13 acvA gene encoding delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase, which performs the first step in penicillin biosynthesis, has been determined. The acvA gene contains an open reading frame of 11,238 bp encoding a protein of 3746 amino acids with a predicted mol. wt of 421,073 dalton. Three domains within the protein of approximately 570 amino acids have between 38% and 43% identity with each other and share similarity with two antibiotic peptide synthetases from Bacillus brevis as well as two other enzymes capable of performing ATP-pyrophosphate exchange reactions. The acvA gene is located close to the pcbC gene encoding isopenicillin N synthetase, the enzyme for the second step of beta-lactam biosynthesis, and is transcribed in the opposite orientation to it. The intergenic region of 1107 bp from which the acvA and pcbC genes are divergently transcribed has also been sequenced.

Amino Acid Sequence↗
PubMed1990

Beta-lactam antibiotic biosynthetic genes have been conserved in clusters in prokaryotes and eukaryotes.

A cosmid clone containing closely linked beta-lactam antibiotic biosynthetic genes was isolated from a gene library of Flavobacterium sp. SC 12,154. The location within the cluster of the DNA thought to contain the gene for delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS), the first step in the beta-lactam antibiotic biosynthetic pathway, was identified by a novel method. This DNA facilitated the isolation, by cross-hybridization, of the corresponding DNA from Streptomyces clavuligerus ATCC 27064, Penicillium chrysogenum Oli13 and Aspergillus nidulans R153. Evidence was obtained which confirmed that the cross-hybridizing sequences contained the ACVS gene. In each case the ACVS gene was found to be closely linked to other beta-lactam biosynthetic genes and constituted part of a gene cluster.

Anti-Bacterial Agents↗