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Biomedical subjects

R A Johnson

Publications and source records attributed to R A Johnson.

359 records · Page 20Linked to original sources
PubMedDate not supplied

Application of quadFERM+ for the identification of fastidious gram-positive and gram-negative bacilli.

The 2-hr quadFERM+ kit (qF) (Analytab Products, Plainview, NY) was compared with conventional tube tests for the identification of the HACEK bacteria (Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae), other Haemophilus and Kingella spp., Capnocytophaga, Corynbacterium, and Moraxella spp. Test results were identical for 296 comparisons with 74 isolates (74%). In the remaining 104 comparisons for 26 isolates, 50 reactions were identical, and qF produced a positive result in 46 of 54 discrepancies.

Actinobacillus↗
PubMedDate not supplied

Aid-in-dying: issues and implications for nursing.

A debate format describes questions arising from the Model Aid-in-Dying Act, drafted at the University of Iowa's College of Law, and the implications for nurses. The Act allows patients or their named surrogates to demand or request active aid-in-dying. The Act requires nurses and other health care providers to comply with the qualified patient's demand unless the health care provider is a registered conscientious objector.

Ethics, Nursing↗
PubMedDate not supplied

Enzymatic preparation of 32P-labeled beta-L-2',3',-dd-5'ATP and its use as a high-affinity, conformation-specific ligand for labeling adenylyl cyclases.

An enzymatic method was developed for the preparation of unlabeled and [beta-32P]-labeled beta-L-2',3'-dd-5'ATP from the monophosphate with near quantitative yields. beta-L-2',3'-dd-5'ATP was a competitive and potent inhibitor of adenylyl cyclases (IC5 approximately 30 nM). Upon uv-irradiation beta-L-2',3'-dd-[beta-32P]-5'ATP directly crosslinked to a chimeric construct of this enzyme. Data suggest that this is a pre-transition state inhibitor and contrasts with the equipotent 2',5'-dd-3'ATP, a post-transition state, noncompetitive inhibitor.

Adenosine Triphosphate↗
PubMedDate not supplied

Synthesis of nucleoside 3'-thiophosphates in one step procedure.

A mild and efficient one-step method of thiophosphorylation was devised for acid-sensitive nucleosides. The procedure is based on thiophosphorylation of nucleoside magnesium alkoxide by 2-chloro-2-thio-1,3,2-dioxaphospholane. The utility and efficiency of this method combined with deprotection of the resulting cyclic triester were demonstrated by its application to the synthesis of both adenosine 3'- and 5'-thiophosphates. The procedure does not require protection of the exocyclic amino group and can be successfully used for the thiophosphorylation of nucleosides that are unusually sensitive to depurination.

Animals↗
PubMedDate not supplied

Gallium scintigraphy for diagnosis of septic arthritis and osteomyelitis in children.

Thirty-four children with presumptive acute osteomyelitis or septic arthritis underwent early gallium-67 citrate scintigraphy and have been retrospectively reviewed. Diagnostic accuracy using this technique was 91%. Gallium-67 citrate is a more reliable radiopharmaceutical agent for the detection of selected acute musculoskeletal infections than either technetium methylene diphosphonate or indium-111. However, the radiation dosage from gallium is higher than from other radiopharmaceutical agents, and the authors would recommend its use only in cases where the diagnosis cannot be made on the basis of clinical, laboratory, or plain roentgenographic criteria.

Acute Disease↗
PubMedDate not supplied

Cephalad distribution of three differing volumes of new methylene blue injected into the epidural space in adult goats.

Epidural anesthesia and analgesia are popular regional anesthetic techniques in many animal species. However, we have not found any reports of studies in animals that have investigated the extent of cephalad migration and level of sensory blockade achieved based only on the volume of drug injected into the epidural space. The purpose of this study was to determine if there is a relationship between the volume (mL/kg) of an injectate injected epidurally and the extent of its cephalad migration within the epidural space. Twelve adult goats were randomly assigned to three treatment groups based on the volume of 0.12% New Methylene Blue (NMB), 0.1, 0.2, or 0.3 mL/kg, injected into the epidural space. The site and speed of injection, animal position, and direction of needle bevel were held constant. All injections were performed at the lumbo-sacral space immediately following euthanasia. At necropsy, the vertebral columns were transected longitudinally. The extent of cephalad migration of dye within the epidural space was easily determined by staining of the dura. Measurements were rounded to the nearest intervertebral space to which the dye had migrated. The individual making assessments was blinded to all treatments. In goats treated with 0.1, 0.2, or 0.3 mL/kg NMB, the number of stained spinal segments was 3.5 +/- 0.6, 6.5 +/- 0.9, and 8.8 +/- 0.6, (mean +/- SEM), respectively. Linear regression performed on the data was significant (P < .05) with R2 = 0.86. There was a strong linear relationship between volume (mL/kg) of epidurally injected NMB and cranial migration, with the larger volumes producing more cephalad spread within the epidural space. These results provide evidence for the volume of epidural injectate needed to produce a desired level of sensory blockade in adult goats.

Animals↗
PubMedDate not supplied

Fatty acid transport: the diffusion mechanism in model and biological membranes.

The transport of fatty acids (FA) across membranes can be described by three fundamental steps: adsorption, transmembrane movement, and desorption. In model membranes, these steps are all rapid and spontaneous for most fatty acids, suggesting that FA can enter cells by free diffusion rather than by protein-mediated mechanisms. Here we present new fluorescence approaches that measure adsorption and transmembrane movement of FA independently. We show that FA adsorb to the plasma membrane of adipocytes and diffuse through the membrane by the flip-flop mechanism within the time resolution of our measurements (approximately 5 s). Thus we show that passive diffusion is a viable mechanism, although we did not evaluate its exclusivity. Important implications of the diffusion mechanism for neural cells are that all types of FA could be available and that selectivity is controlled by metabolism. Studies of FA uptake into brain endothelial cells and other brain cell types need to be performed to determine mechanisms of uptake, and metabolism of FA must be separated in order to understand the role of membrane transport in the overall uptake process.

Adipocytes↗
PubMedDate not supplied

Age, period, and cohort effects in marijuana and alcohol incidence: United States females and males, 1961-1990.

Using multiple classification models applied to self-report data on initiation of drug use from nine National Household Surveys on Drug Abuse conducted between 1982 and 1995, this paper shows that the directions of change in period and cohort effects were similar for marijuana and alcohol and for males and females. Period effects--indicative and societal tolerance or support for drug use during 5-year periods between 1961 and 1990--declined between the early 1970s and late 1980s, while cohort effects--indicative of early experiences of birth cohorts favoring drug use--increased. One interpretation is that trends in incidence were determined by two opposing vectors of social forces: Beginning in the 1970s, changes in social policies, values, and drug markets--as reflected in period effects--increasingly acted to reduce incidence, while changes in conditions of childhood socialization--as reflected in cohort effects--increasingly facilitated or encouraged incidence. Especially for marijuana, the increase in cohort effects is larger among females, which gives rise to gender convergence--approximately equal male and female incidence rates for both drugs--by the late 1980s. An innovative method of the paper is the adjustment of incidence rates for reporting bias.

Age Distribution↗
PubMedDate not supplied

Nonresponse and selection bias in treatment follow-up studies.

Large-scale studies of addiction treatment employ two stages: select providers, then select patients to follow-up. Nonresponse due to noncooperation of providers and problems of locating and recruiting patients may bias the results. We review selection and attrition biases in previous work and in four major United States treatment studies in the 1990s: DATOS (N = 10,100 clients, 96 units), NTIES (N = 6,593/71), SROS (N = 3,047/99), and CALDATA (N = 3,045/86). We develop a standard approach, break down sampling and attrition rates, and discuss differences in client, program, and methodology factors. We conclude with some methodological recommendations for future follow-up studies of addiction treatment.

Follow-Up Studies↗
PubMedDate not supplied

Trends in rates for mortality from all causes among Indians in Minnesota, 1960-79.

Trends in age- and sex-specific mortality rates for all causes of death for Indians in Minnesota during the years 1960-79 were examined using the Mantel-Haenszel chi-square extension test. Indians younger than 15 years of age were not included in the analysis because of the changes in classification for Indian race in census reports for Indian children and adolescents, known decreases in Indian infant mortality, and the small number of deaths among Indian children and adolescents during the years 1960-79. Declines in mortality rates were observed for Indian men and women 75 years of age and older, men 65 through 74 years of age, and women 25 through 54 years of age. Overall, only 8 percent of men and 53 percent of women were in age groups that showed declining mortality rates for all causes of death during the years 1960-79. The greatest decline in mortality rates for men and women occurred among those 75 years of age and older. Mortality rates for Indians in Minnesota declined during the study period for fewer than half of the age groups. Such strategies as risk factor surveillance, public health programs, and medical interventions need to be directed toward these groups that have not experienced the same declines in mortality rates as nearly all age groups of whites, both nationwide and in Minnesota, during the same period.

Adolescent↗