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Biomedical subjects

D G Smith

Publications and source records attributed to D G Smith.

At least 199 records · Page 11Linked to original sources
PubMed1991

Overproduction and characterization of the uracil-DNA glycosylase inhibitor of bacteriophage PBS2.

A plasmid expression vector (pZWtac1) was constructed which allowed inducible overexpression of the uracil-DNA glycosylase (Ung) inhibitor (Ugi)-encoding gene (ugi) in Escherichia coli. In this plasmid, the ugi gene was under the control of both its own promoter and the tac promoter. Constitutive expression of the ugi was observed in the absence of isopropyl-beta-D-thiogalactopyranoside (IPTG). In the presence of 1 mM IPTG, the Ugi protein was overproduced to an approx. 16-fold higher level, and accounted for approx. 19% of the total soluble cellular proteins. Following high-level production in E. coli, the Ugi protein was purified to apparent homogeneity. Using E. coli Ung, we observed that Ugi inactivated the enzyme in a noncompetitive manner. Kinetic studies revealed a Ki value (0.14 microM) of approx. twelve-fold lower than Km value (1.7 microM) of glycosylase. Ugi did not act synergistically with free uracil to inhibit E. coli Ung suggesting that uracil and Ugi could share a similar mode of inhibition.

Bacillus subtilis↗
PubMed1991

Perceptions of community leaders and the merger of rural health services.

The merger of rural primary care and home health services offers the potential of increasing the administrative efficiency of health care, and thereby enhancing quality of care and increasing access to services, particularly health promotion. In a merger of rural health services in Northeastern Vermont, a survey of key community leaders revealed that improved organization of services, improved health status and greater accessibility of services were benefits expected and to some extent realized as a result of the merger process. The desire to preserve community-based services and having a common philosophy were important factors which served to initiate the merger. The actions of a few key individuals and the support of involved organizations were instrumental in continuing the process.

Community Participation↗
PubMed1991

Facial fractures occurring in a medium-sized metropolitan area: recent trends.

A retrospective 3-year survey of 311 patients sustaining 564 facial fractures in a medium-sized metropolitan area is presented. Etiology, distribution and treatment of these facial fractures are reported and compared with earlier studies, where changing patterns of etiology and treatment were noted. Contemporary knowledge of facial injuries is important if diagnosis and treatment are to be accurate and treatment optimal.

Accidents, Traffic↗
PubMed1991

Synthesis and smooth muscle relaxant activity of a new series of potassium channel activators: 3-amido-1,1-dimethylindan-2-ols.

The synthesis of a novel series of smooth muscle relaxants which have been shown to act via the opening or activation of potassium channels is described. Compounds have been evaluated for their ability to inhibit spontaneous tone in guinea pig isolated trachealis and structure-activity relationships are discussed. One compound in particular, 1,1-dimethyl-5-nitro-3-(2-pyridon-1-yl)indan-2-ol, (16) was identified as a potent relaxant of airways smooth muscle in vitro with IC50 = 0.15 microM and was found to significantly inhibit histamine-induced dyspnoea in conscious guinea pigs when given orally 30-45 min prior to challenge.

Amides↗
PubMed1991

Relaxant activity of 6-cyano-2,2-dimethyl-2H-1-benzopyran-4-carboxamides and -thiocarboxamides and their analogues in guinea pig trachealis.

Structural modifications of the potassium channel activator cromakalim (1) are described in which the amide moiety at C-4 has been replaced by carboxamide and thiocarboxamide functions. Analogues in which the hydroxyl group at C-3 has been oxidized or removed are also disclosed. Such analogues display an interesting profile of smooth muscle relaxant activity in the guinea pig isolated trachea, not all of which appears to result from the opening of potassium channels, but few compounds retain useful in vivo activity. However, one compound in particular, 6-cyano-2,2-dimethyl-N-methyl-2H-1-benzopyran-4-thiocarboxamide (13) was shown to be a potent potassium channel activator in vitro and to provide prolonged protection to guinea pigs from the respiratory effects of inhaled histamine.

Animals↗
PubMed1991

Effects of carbon dioxide and sub-lethal levels of antibiotics on adherence of coagulase-negative staphylococci to polystyrene and silicone rubber.

Fifty coagulase-negative staphylococci (CNS) strains were investigated for adherence to both silicone rubber and polystyrene using a microtitre tray system. Culture in an atmosphere containing a physiological level of carbon dioxide (5% CO2) profoundly affected adherent growth to both surfaces. Most strains adhered less well in this atmosphere compared to in air alone, with mean reductions in adherence of 84% and 86% to silicone rubber and polystyrene respectively. Occasional strains adhered better in 5% CO2. The effects of antibiotic concentrations equivalent to 1/4 MIC of cefuroxime, ciprofloxacin, vancomycin and teicoplanin on the adherence of 10 CNS strains were also studied. Vancomycin and teicoplanin frequently increased adherence to silicone rubber and polystyrene compared to controls. The effects of antibiotics on adherence were not only strain dependent but also sometimes atmosphere or surface specific. Antibiotic-induced changes in adherence did not appear to correlate with changes in strain protein profiles or surface hydrophobicities.

Anti-Bacterial Agents↗
PubMed1991

Variation in the expression of cell envelope proteins of coagulase-negative staphylococci cultured under iron-restricted conditions in human peritoneal dialysate.

Strains of coagulase-negative staphylococci (CNS), including Staphylococcus epidermidis, S. hominis, S. warnerii, S. simulans, S. capitis, S. haemolyticus and S. saprophyticus, were isolated from patients with continuous-ambulatory-peritoneal-dialysis-related peritonitis. The cell wall and cytoplasmic membrane protein profiles of CNS strains cultured in either nutrient broth (NB) or pooled human peritoneal dialysate (HPD) were compared. Some interspecies variation in both the wall and membrane protein profiles was noted. However, the cell wall protein profiles of HPD-grown CNS strains differed markedly from those cultured in NB. Growth in HPD resulted in a marked reduction in the total number of cell-wall-associated proteins but up to three antigenically related proteins in the 40-56 kDa range, depending on the species, predominated. Growth in HPD also resulted in the induction of two iron-repressible cytoplasmic membrane proteins (IRMPs) of 32 and 36 kDa in S. epidermidis. Other CNS strains only appeared to express a single IRMP, which varied in molecular mass from 32 to 36 kDa. Whilst the IRMP in these CNS strains showed considerable antigenic homology with the 32 kDa IRMP, the S. warneri IRMP showed cross-reactivity with both the 32 and 36 kDa IRMPs of S. epidermidis. Immunoblotting experiments revealed that whilst the CNS cell wall proteins were poorly immunogenic, the IRMPs were the immunodominant CNS protein antigens, reacting strongly with antibodies present in HPD. This finding provides evidence to suggest that the IRMPs are expressed in vivo during infection.

Antibodies, Bacterial↗
PubMed1991

Decreased DNA damage by acid and increased repair of acid-damaged DNA in acid-habituated Escherichia coli.

A study of the conjugal transfer of ColV,I-K94 tn 10 from acid-treated donors suggested that acid-habituated recipients repair acid-damaged plasmid DNA better than those that are not habituated. The presence of an increased repair activity for acid-damaged DNA in habituated cells was confirmed by isolating pBR322 from acid-treated organisms; habituated cells produced more transformants when transformed by it than did non-habituated ones. Additionally, agarose gel electrophoretic studies of pBR322 DNA isolated from acid-damaged cells and tests of its transforming activity both indicated that plasmid DNA in habituated cells is less damaged by extreme acidity than is that in non-habituated organisms.

Conjugation, Genetic↗
PubMed1991

Habituation to acid in Escherichia coli: conditions for habituation and its effects on plasmid transfer.

Induction of acid resistance (habituation) in Escherichia coli at pH 5.0 took ca 5 min in broth at 37 degrees C and 30-60 min in minimal medium. Induction occurred at a range of pH values from 4.0 to 6.0; it was dependent on continuing protein and RNA synthesis but substantial acid resistance appeared in the presence of nalidixic acid. Acid resistance was long-lasting; organisms grown at pH 5.0 retained most of their resistance after 2 h growth at pH 7.0. Organisms grown at pH 5.0 showed increased synthesis of a number of cytoplasmic proteins compared with the level in cells grown at pH 7.0. DNA repair-deficient strains carrying recA, uvrA or polA1 mutations were more acid-sensitive than the repair-proficient parents but were able to habituate at pH 5.0. Organisms grown at pH 5.0 transferred the ColV plasmid much more effectively at acid pH than did those grown at pH 7.0 and habituated recipients appeared better able to repair incoming acid-damaged plasmid DNA than did those that were non-habituated. Induction of acid resistance at pH 5.0 may be significant for the survival of organisms exposed to periodic discharges of acid effluent in the aquatic environment and habituation may also allow plasmid transfer and repair of acid-damaged plasmid DNA during or after such exposure.

Adaptation, Physiological↗
PubMed1991

The effect of a plaque control programme on the incidence and severity of cyclosporin-induced gingival changes.

The efficacy of plaque control as a means of preventing cyclosporin-induced gingival overgrowth was assessed in 27 adult renal transplant patients. After baseline examination, patients were randomly allocated to receive intensive oral hygiene instructions, scaling and root planing (OH group) or no treatment (no treatment group). Gingival condition was assessed 6 months after baseline and changes in gingival form were related to various periodontal and pharmacokinetic measures. In both treatment groups, there was a significant increase (P less than 0.05) in gingival hyperplasia scores at 6 months. In the OH group, plaque scores were significantly lower (P less than 0.05) at 6 months, whereas in the no treatment group, a significant increase in plaque scores, gingival inflammation and probing depths was observed at 6 months. Dosages of cyclosporin, whole blood concentrations of cyclosporin, baseline gingival index, hyperplasia scores, and 6-month plaque index were not important determinants for the increase in gingival over-growth in both treatment groups. It is concluded that attention to plaque control and the removal of local irritants is of some benefit for the gingival health of cyclosporin-treated adult renal transplant patients, but these measures alone did not prevent gingival overgrowth. Pharmacokinetic variables of cyclosporin and various periodontal measures were not good predictors of cyclosporin-induced gingival changes.

Adult↗
PubMed1991

The merger of rural primary care and home health services.

The merger of rural primary care and home health services offers the potential for increasing the administrative efficiency of health care, and thereby enhancing the quality of care and increasing access to services, particularly health promotion. However, the proposed benefits of any merger can only be realized if the merger process is successfully completed. An analysis of the factors that were important in a case study of successful and unsuccessful mergers of rural health centers and home health care agencies in northeastern Vermont is presented. Three components were found to be necessary to start the merger process: complementary needs, opportunity, and common philosophy. The involvement and support of key individuals was crucial to sustaining merger interest. Good communication throughout the process contributed substantially to the maintenance of both community and staff support. Others considering similar mergers should recognize that the process of consolidating organizations and satisfying regulations takes some time to complete.

Community Health Centers↗
PubMed1991

Characterization of cell envelope proteins of Staphylococcus epidermidis cultured in human peritoneal dialysate.

The cell envelope protein profiles of Staphylococcus epidermidis cultured in used human peritoneal dialysate (HPD) differed markedly from those of cells cultured in nutrient broth. Compared with broth-grown cells, many cell wall proteins were repressed in HPD, although three proteins of 42, 48, and 54 kDa predominated and an iron-repressible 130-kDa protein was induced. Growth in HPD also resulted in expression of two cell membrane proteins of 32 and 36 kDa which were iron repressible. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis using monospecific polyclonal antisera raised against the 32- and 36-kDa proteins revealed considerable antigenic and molecular mass homology among 12 S. epidermidis isolates from patients with continuous ambulatory peritoneal dialysis-related peritonitis. The 32-kDa antiserum also cross-reacted with a 32-kDa S. aureus cell membrane protein. Immunoblots of S. epidermidis cell walls and membranes were also probed with normal human serum and serum and HPD from continuous ambulatory peritoneal dialysis patients. While the cell wall proteins of S. epidermidis appeared to be relatively poorly immunogenic, the 32- and 36-kDa membrane proteins reacted strongly with antibodies present in each of the body fluids evaluated. These results suggest that the highly conserved 32- and 36-kDa iron-repressible proteins are expressed during growth in vivo and may be involved in iron transport, since all 12 S. epidermidis strains examined also produced iron chelators.

Bacterial Proteins↗
PubMed1991

Health insurance in the health administration curriculum.

Managers and policymakers knowledgeable in the delivery and financing of health care are needed in the health care industry, and health administration programs can meet this need by expanding course offerings which consider the role and operations of insurers. This paper surveys the major topics in the field of health insurance and presents a course overview for an introduction to the field of health insurance for health administration students.

Actuarial Analysis↗
PubMed1991

Clinical support groups that work.

A support group for nurses who care for patients with AIDS has been meeting at a major teaching hospital in New York City for the past year. The authors believe its success has been determined by three components: the group's ability to first, express feelings; second, do a needs assessment and plan programs to meet those needs; and third, participate in the organizational development system of the hospital. Management recognizes the importance of the group, endorses it, and supports it verbally and behaviorally.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Postponement of death until symbolically meaningful occasions.

This study shows that mortality dips before a symbolically meaningful occasion and peaks just afterward. Mortality among Chinese (n = 1288) dips by 35.1% in the week before the Harvest Moon Festival and peaks by the same amount (34.6%) in the week after. We chose to study mortality among Chinese and a Chinese holiday for two reasons. First, the holiday moves around the calendar, thus allowing separation of the effects of the holiday from fixed, monthly mortality effects. Second, the holiday appeals strongly to one (experimental) group and not to others (which can be used as control groups). In terms of percentage, cerebrovascular diseases displayed the largest dip/peak pattern, followed by diseases of the heart, and then malignant neoplasms. The dip/peak mortality pattern does not appear in various non-Chinese control groups. The statistical significance of the findings was demonstrated with linear and curvilinear regression analysis and with two nonparametric tests. After testing alternative explanations for the findings, we concluded that the dip/peak pattern occurs because death can be briefly postponed until after the occurrence of a significant occasion.

Aged↗