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Biomedical subjects

D G Smith

Publications and source records attributed to D G Smith.

At least 217 records · Page 12Linked to original sources
PubMed1990

Relaxant activity of 4-amido-3,4-dihydro-2H-1-benzopyran-3-ols and 4-amido-2H-1-benzopyrans on guinea pig isolated trachealis.

A series of 4-amido-3,4-dihydro-2H-1-benzopyran-3-ols and 4-amido-2H-1-benzopyrans related to the potassium channel activator cromakalim have been prepared and evaluated for their relaxant activity in guinea pig isolated tracheal spirals. Several analogues show enhanced relaxant activity relative to cromakalim in this preparation and the rank order of potency for those substituents investigated at C-6 was CF3 greater than CN greater than C2H5 greater than aza greater than or equal to CH3. One compound, trans-3,4-dihydro-2,2-dimethyl-4-(2-oxopiperidin-1-yl)-7-(trifluor omethyl)-2H- 1-benzopyran-3-ol (24), was resolved into its two enantiomers and the activity was shown to reside essentially in the (+)-isomer, adding further support to the suggestion that the smooth muscle receptor for these potassium channel activators is stereoselective.

Amides↗
PubMed1990

Identifying hypertensive patients with elevated systolic workplace blood pressures.

The present study was designed to identify patients who had systolic work blood pressures that were substantially higher than their clinic blood pressures. Fifty-two mild and moderate hypertensive patients were assessed using clinic blood pressures and ambulatory blood pressure monitoring in their natural environment. Thirty-eight percent of these patients had systolic work blood pressures that were more than 10 mm Hg above their clinic blood pressures. These patients did not differ from other patients in terms of the demographic or clinical factors which were assessed. Need for control and anger, two core features of the Type A Coronary-prone Behavior Pattern, were shown to discriminate these patients on a statistically reliable basis. Research on cardiovascular reactivity to stress suggests that such patients with elevated systolic work blood pressures may be at greater risk for cardiac morbidity and mortality.

Analysis of Variance↗
PubMed1990

Influence of carbon dioxide on growth and antibiotic susceptibility of coagulase-negative staphylococci cultured in human peritoneal dialysate.

Used peritoneal dialysis fluid was collected from patients undergoing continuous ambulatory peritoneal dialysis, and its pH and composition were assessed after incubation in either air or air with 5% CO2. Precipitation of calcium, magnesium, phosphate, and proteins occurred in the dialysis fluid incubated in air at 37 degrees C and was associated with a mean pH increase of 1.23 U. Incubation of dialysis fluid in air with 5% CO2 prevented precipitation and maintained pCO2 and pH levels at those found physiologically. Coagulase-negative staphylococcal strains isolated from patients with peritonitis tended to grow less well in dialysis fluid incubated in air than in dialysis fluid incubated in the carbon dioxide-enriched atmosphere. MICs of cefuroxime, ciprofloxacin, and vancomycin for seven strains of coagulase-negative staphylococci in dialysis fluid were markedly affected by atmosphere type (16 of 21 MICs). Of these 16 atmosphere-dependent MICs, 14 were at least fourfold higher in air than in air with 5% CO2.

Air↗
PubMed1990

Influence of carbon dioxide on the surface characteristics and adherence potential of coagulase-negative staphylococci.

Coagulase-negative staphylococci obtained from patients with continuous ambulatory peritoneal dialysis-related peritonitis were cultured in nutrient broth in an atmosphere of air containing 5% carbon dioxide (reflecting the CO2 tension found in freshly used dialysate). Significant differences were observed between the surface chemistries of cells grown in the two atmospheres, as determined by X-ray photoelectron spectroscopy and changes in the cell wall protein profile. The growth atmosphere also influenced the adherence potential toward polystyrene and silicone in a proportion of strains examined. Thus, gaseous conditions can profoundly influence the nature of the staphylococcal surface, and this should be considered in any in vitro study of in vivo behavior.

Bacterial Adhesion↗
PubMed1990

Cytochemical localization of mercury in Saccharomyces cerevisiae treated with mercuric chloride.

We describe a cytochemical method for localizing mercury at the electron microscopic level in the yeast Saccharomyces cerevisiae. After addition of a lethal concentration of mercuric chloride to growing yeast cells, mercury was associated with the cell wall and cytoplasmic membrane. Little or no mercury was present in the cytoplasm. Electron probe X-ray microanalysis (EPMA) confirmed that the cytochemical reaction, visualized as mercury-silver complexes, was localized in dense bodies consisting of a core of mercury sulfide polymers surrounded by a shell of silver atoms.

Electron Probe Microanalysis↗
PubMed1990

Longitudinal study of adverse reactions following diphtheria-tetanus-pertussis vaccine in infancy.

A prospective study of immunogenicity and adverse effects of 1553 doses of diphtheria and tetanus toxoids and whole cell pertussis vaccine (DTP) was performed in 538 children observed longitudinally from 2 months to 20 months of age. Subjects were randomized to the standard four-dose immunization schedule or to a three-dose schedule (with a saline injection substituted for DTP at 6 months of age). The three-dose schedule could not be recommended on the basis of serologic data. Compliance for completing a clinical observation form in the 48 hours following injections was greater than 99%. Fever, local reactions, or adverse behavioral effects were described in association with 96% of DTP doses and 36% of placebo injections. Contraindications to DTP immunization developed in 3% of study children. No convulsion, hypotonic hyporesponsive episode, encephalopathy, or temperature greater than 40.5 degrees C occurred. Behavioral and local inflammatory effects occurred maximally in the first 6 hours following vaccine but fever peaked later. There was no interrelationship between occurrence of local reaction and fever. Data suggest that age has more effect on the type and rate of adverse clinical events than does vaccine dose number. Existing antibody levels to vaccine components, lot of vaccine, breast-feeding, or gestational age did not affect rate or type of clinical reactions. Neither occurrence of reactions nor the use of acetaminophen affected antibody response to vaccine.

Acetaminophen↗
PubMed1989

Response of cultured human cell lines from rhabdomyosarcoma xenografts to treatment with chloroethylnitrosoureas.

DNA interstrand cross-links are thought to be the cytotoxic lesion resulting from treatment of cells with the chlorethylnitrosoureas (CENUs). We showed in an earlier study that the resistance of xenografts of pediatric rhabdomyosarcoma to therapy with CENUs correlates with levels of O6-alkylguanine-DNA alkyltransferase. We now demonstrate a relationship between levels of the alkyltransferase and CENU-induced cytotoxicity and DNA-interstrand cross-link formation in two cell lines recently established from such rhabdomyosarcoma xenografts. Rh18 cells were derived from the HxRh18 xenograft line, which contains the alkyl-transferase and is relatively resistant to CENUs, and Rh28 cells were derived from the HxRh28 xenograft line, which lacks detectable alkyltransferase activity and is sensitive to treatment with the CENUs. In vitro, Rh28 cells were 5- to 6-fold more sensitive to growth inhibition by 1,3-bis(2-chloroethyl)nitrosourea than Rh18 cells. Extracts of Rh18 cells contained 3.8 units of the alkyltransferase per mg of protein, whereas such activity was undetectable in Rh28 cells, a unit of the alkyltransferase being defined as 1 pmol of [3H] methyl transferred from [3H]methyl-labeled DNA to protein. DNA interstrand cross-links, measured by alkaline elution 6 h after a 1-h pulse treatment with CENU, could not be detected in Rh18 cells but were found in the Rh28 line. The phenotypes of the parental xenograft lines defined by their alkyltransferase levels and by responses to CENU therapy of the mice have clearly been retained in the cultured cell lines, and as predicted, cross-link formation was inhibited in the alkyltransferase-containing Rh18 cells. These two new cell lines thus provide a useful model for studying the role of DNA repair in rhabdomyosarcoma resistance to these alkylating agents.

Animals↗
PubMed1989

The charges for ESRD treatment of diabetics.

To evaluate the differential charges for treating end-stage renal disease (ESRD) associated with diabetes mellitus, Medicare billing data are analyzed. The charges of 244 patients in the Michigan Kidney Registry identified as having (ESRD) from diabetes are compared with charges of 902 nondiabetic patients. Average annual charges for ESRD treatment for diabetics are +29,671 (+/- 27,662) which are +4695 (+/- 1344) higher than charges for nondiabetics. The majority of the difference (84.3%) is attributable to higher inpatient hospital charges. Most of the remainder (14.5%) is attributable to higher physician and medical supply charges. Charges for treatment of diabetics are higher on all modalities of treatment, but differences are not significant among modalities.

Adult↗
PubMed1989

Outbreak of pertussis in a residential facility for handicapped people.

An outbreak of pertussis was recognized and investigated in a home for neurologically impaired people. Of 66 residents, 44 (67%) had evidence of recent pertussis infection, although only 12 (27%) had respiratory symptoms. Pertussis was diagnosed by culture, direct fluorescent antibody testing of nasal secretions, agglutinating antibody titer, pertussis antitoxin titer, IgG antibody to pertussis toxin, IgA antibody to pertussis toxin, IgA antibody to filamentous hemagglutinin, or IgG antibody to filamentous hemagglutinin. No single test identified more than 66% of people with pertussis. Of those with positive serologic findings, 95% had a positive test result for IgA antibody to filamentous hemagglutinin or for IgG antibody to pertussis toxin or for both. Pertussis occurred in both immunized and unimmunized residents. Seven carriers were identified; these residents had positive cultures or positive direct fluorescent antigen test results but negative serologic findings. Treatment of residents and caretakers with erythromycin halted the outbreak.

Adolescent↗
PubMed1989

Active Epstein-Barr virus infection in post-viral fatigue syndrome.

Serological evidence of active infection with Epstein-Barr virus (EBV) was found in 25 of 124 patients (20%) with the post-viral fatigue syndrome (PVFS). In another study on the same group of patients around 50% were found to have evidence of chronic enterovirus infection. No overlap was found between those patients with enterovirus infection and those with active EBV infection. We suggest that there are multiple causes of PVFS and that, in the absence of coexisting immunosuppressive disease which may itself reactivate the virus, EBV may be the aetiological agent in a predominantly female subgroup of patients with PVFS. Furthermore, the disease process in this subgroup may be immunopathological in nature.

Adolescent↗
PubMed1989

Radiocarpal articular contact characteristics with scaphoid instability.

The relative importance of the three major periscaphoid ligament complexes in maintaining the normal radiocarpal articulation was assessed. Pressure-sensitive film recorded the changes in radioscaphoid and radiolunate articular contact that occurred with sequential ligament sectioning in 12 cadaver wrists. Alterations in the radiocarpal articular contact as a result of ligament disruption are evident in the absence of the recognizable static x-ray changes of carpal instability. The scapholunate interosseous ligament is essential in preventing scapholunate diastasis and dorsoradial subluxation of the proximal scaphoid. Rotatory subluxation of the scaphoid occurs when disruption of the scapholunate interosseous ligament is coupled with disruption of either the palmar intracapsular radiocarpal ligaments or the scaphotrapezial ligament complex. These data help explain the development of degenerative arthritis caused by carpal ligamentous instability.

Biomechanical Phenomena↗
PubMed1989

The relationship between patients' satisfaction with their physicians and perceptions about interventions they desired and received.

This study was designed to determine the relationship between patients' satisfaction with their physician, the types of interventions that patients reported they received, and the congruence between those interventions and the types of interventions they desired. One hundred eighteen symptomatic adult primary-care patients completed questionnaires before and after their respective medical visits. Patients who indicated they received any one of the three nontechnical interventions: education (P less than 0.001), stress counseling (P less than 0.05), and negotiation (P less than 0.01), were significantly more satisfied than those who had not received these interventions. Patient perceptions about receiving technical interventions, i.e., examination, tests, medications, and nondrug therapy, were not related to patient satisfaction. The congruence between patient-intervention desires and perceptions about interventions received generally were not significantly related to satisfaction except for the interaction between receiving a medication and postvisit-medication desires (P less than 0.001). A series of multiple regression analyses revealed that, in general, perceptions about nontechnical interventions were better predictors of patient satisfaction than perceptions about technical interventions.

Adult↗
PubMed1989

Accounting based risk measures for not-for-profit hospitals.

This paper discusses the issues involved with determining an appropriate discount rate for not-for-profit hospitals and develops a method for computing measures of systematic risk based on a hospital's own accounting data. Data on four hospital management companies are used to demonstrate the method. Results indicate the need for sensitivity analysis in the selection of estimation methods and in the final determination of a discount rate.

Accounting↗
PubMed1989

Changes in anti-endotoxin-IgG antibody and endotoxaemia in three cases of gram-negative septic shock.

Circulating endotoxin levels and IgG antibodies to a range of Gram-negative bacterial lipopolysaccharides (LPS) (endotoxins) of different sizes and structures were measured daily in three cases of septic shock. There was an inverse relationship between endotoxin levels and cross-reactive antibodies to the core glycolipid (CGL) region of lipopolysaccharide. This suggests that antibody to LPS-CGL was initially consumed by a superabundance of endotoxin, and that a resurgence of intrinsic anti-LPS-CGL antibody levels may be associated with a reduction of circulating endotoxin. The implications of these findings for passive antibody therapy of septic shock are discussed.

Adult↗