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Biomedical subjects

A Johnson

Publications and source records attributed to A Johnson.

At least 451 records · Page 25Linked to original sources
PubMed1989

Septic arthritis in children with hemophilia.

Four of the 139 children with hemophilia followed up at our center have developed septic arthritis during the past 6 years (2.9% incidence). Two infections were caused by Streptococcus pneumoniae and one each by Staphylococcus aureus and Haemophilus influenzae type B. Common features at time of presentation included fever and a 2- to 7-day history of joint pain and swelling unresponsive to factor replacement infusions. Since three of the patients were human immunodeficiency virus seropositive, we propose that human immunodeficiency virus infection may be responsible for the disproportionately high number of cases of septic arthritis observed in our patient population.

Adolescent↗
PubMed1989

Some socioeconomic factors in the selection of blood pressure drugs in New Orleans, Louisiana.

Socioeconomic factors are important in the selection of drug therapy for hypertension in New Orleans. With a preponderance of blacks, and an economic recession in the city, the availability of a large variety of effective and relatively safe hypertensive medications does not in itself solve the problem of providing a lifetime of antihypertensive medication. We must know our patients well and take into consideration income, age, home environment, and family situation. Only then can drug therapy that is appropriate to this complex milieu be prescribed.

Black or African American↗
PubMed1989

Acid-base status at birth and neurodevelopmental outcome at four and one-half years.

Two hundred thirty term infants with measured acid-base status in umbilical arterial blood at birth were selected from 1210 consecutive deliveries for detailed neurodevelopmental follow-up at age 4 1/2 years; 203 were examined. Cutoff points approximately 1 SD from the mean (pH less than or equal to 7.10; base deficit greater than 12 mmol/L) were used to define acidosis. No statistically significant associations between acidosis and developmental outcome were found. The highest proportion of unimpaired children was found among those who were most severely acidotic at birth (pH less than or equal to 7.04; 2 SD below mean), but this finding was not statistically significant. These findings suggest that the ability of the fetus to produce an acidosis in response to the stress of labor may be beneficial to long-term outcome. The 10 nonacidotic babies with 1-minute Apgar scores of less than or equal to 3 showed statistically significant deficits in some areas. Coincident acidosis was not associated with a worse outcome for infants with low Apgar scores.

Acid-Base Equilibrium↗
PubMed1989

A new colorimetric nucleic acid hybridization assay for Listeria in foods.

Non-isotopic colorimetric detection has been applied in a rapid nucleic acid dipstick hybridization assay for detection of Listeria spp. in food and environmental samples. The assay takes approximately 2.5-3 h following a two day broth and plate enrichment. Hybridization occurs between fluorescein labeled detector probes, poly(deoxyadenosine)-tailed capture probes, and Listeria-specific regions of 16 S ribosomal RNA. These target:probe complexes are captured on poly(deoxythymidine) coated plastic dipsticks. Detection is based on binding of horseradish peroxidase conjugated anti-fluorescein antibody to the hybridization complex, and enzyme-mediated color development. The colorimetric endpoint is read on a photometer at 450 nm. In these initial studies, 306 inoculated dairy, meat and seafood samples, and 200 environmental samples were tested. When compared with total culture results the hybridization assay had unconfirmed positive and false-negative rates of approximately 1.4-2.9% and 0.8-4.7%, respectively.

Colorimetry↗
PubMed1989

Studies on calcium absorption from milk using a double-label stable isotope technique.

Calcium absorption was measured in ten male volunteers from skimmed milk, Ca-enriched skimmed milk or watercress (Nasturtium officinale) soup. The foods were labelled extrinsically with 30 mg 44Ca. Shortly after consuming the labelled meal, each subject was given an intravenous injection of 3 mg 42Ca. Fractional absorption from the oral dose was determined from plasma and urine samples collected 24-72 h later, using fast atom bombardment mass spectrometry to measure isotope ratios. The values for urine and plasma were in good agreement. Mean percentage absorption was 45.5 (SEM 1.9)% from the skimmed milk, 35.7 (SEM 4.7)% from the Ca-enriched milk and 27.4 (SEM 1.9)% from the watercress soup. The effect of consuming 568 ml (1 pint) Ca-enriched milk each day for 4 weeks on the efficiency of absorption of Ca was studied. Although there was no statistically significant difference between Ca absorption before and after the supplementation period, the results were considered to be somewhat inconclusive due to the small number of subjects and wide individual variation in Ca absorption.

Absorption↗
PubMed1989

Is popliteal angle measurement useful in early identification of cerebral palsy?

The ability of the popliteal angle test to identify infants with cerebral palsy was evaluated in a population considered to be at increased risk for early childhood impairment. The proportion of infants failing the test increased with decreasing gestational age. Over-all, the test had a sensitivity of 51 per cent and a specificity of 92 per cent: it was more sensitive but less specific for infants less than 30 weeks gestation. Only 12 per cent of infants who failed the test were subsequently diagnosed as having cerebral palsy, but the test had a high negative predictive value (99 per cent). Health visitors were asked to identify infants about whom they felt a general concern, regardless of the test results: their increased concern about an infant proved considerably more sensitive than the popliteal angle test.

Cerebral Palsy↗
PubMed1989

Protein kinase inhibitor prevents pulmonary edema in response to H2O2.

We investigated the effect of H2O2 (92 microM) in isolated guinea pig lungs perfused with a buffered Ringer solution. Pulmonary arterial pressure (Ppa), pulmonary capillary pressure (Ppc), and change in lung weight (delta W) were recorded at 0 min and at 15, 30, and 60 min after the H2O2. The capillary filtration coefficient (Kfc) was measured at 0 and 30 min. The perfusion of H2O2 increased the Ppa, Ppc, delta W, and Kfc. The thromboxane synthetase inhibitor Dazoxiben, or the vasodilator papaverine, prevented the increases in Ppa and Ppc. The protein kinase C (PKC) inhibitor H7 [1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride] prevented the increases in Ppa, Ppc, delta W, and Kfc, whereas the inactive isoquinoline HA1004 [N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride] had little effect on the H2O2 response. H2O2 increased the number of stress fibers and disrupted the peripheral band of cultured confluent endothelial cells, changes that were prevented with pretreatment with H7. PKC may mediate the increases in vascular permeability and pulmonary edema that occur in response to H2O2.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Lipoxygenase products induce neutrophil activation and increase endothelial permeability after thrombin-induced pulmonary microembolism.

We examined the mechanism of the neutrophil (PMN)-dependent increase in pulmonary vascular permeability to protein after thrombin-induced pulmonary microembolism. Humoral factors that activate PMNs after thrombin-induced pulmonary microembolism were characterized in pulmonary lymph obtained from unanesthetized sheep challenged with intravenous infusion of alpha-thrombin. Time-dependent increases in PMN migration, aggregation, and superoxide anion (O2-) generation were induced by the pulmonary lymph obtained within 20 minutes after thrombin infusion. The pulmonary lymph neutrophil activating factors present in ether extracts of lymph had retention times of leukotriene B4 (LTB4) and monohydroxyeicosatetraenoic acids (HETEs) by high-performance liquid chromatography. The postthrombin lymph samples containing the LTB4 and HETEs increased PMN O2- generation and endothelial monolayer permeability to 125I-albumin in the presence of PMNs layered on the endothelial monolayers. Control lymph samples replete with LTB4, 5-HETE, and 15-HETE induced increases in PMN O2- generation and endothelial monolayer permeability to 125I-albumin in the presence of PMNs layered on the endothelial monolayers. Maximal increases in PMN O2- production and endothelial permeability occurred when LTB4, 5-HETE, and 15-HETE were coincubated with PMNs, indicating a synergistic action of these mediators in inducing PMN activation. Endothelial monolayer permeability to 125I-albumin did not increase with postthrombin lymph samples obtained after pretreatment with the 5-lipoxygenase inhibitor, L-651,392. The results indicate that lipoxygenase products generated in the lungs after thrombin-induced microembolism contribute to increased endothelial permeability secondary to PMN activation.

Animals↗
PubMed1989

A comprehensive community approach to adolescent drug abuse prevention: effects on cardiovascular disease risk behaviors.

This paper reports the effects of a multi-community drug prevention trial on the use of cigarettes, alcohol, and marijuana in early adolescents and their parents, effects on parent prevention practices, and the relationship of family health behaviors to adolescent cigarette and alcohol use. Annual self-report surveys were administered to a population-based sample of 6/7th grade students from all schools in a 15 community area (n = 5008). Students were also administered an expired air (CO) measure of cigarette smoking to increase the accuracy of self-reported smoking and drug use. A sub-sample of parents were also surveyed at one year follow-up (n = 620). Logistic regression analyses of student data indicated that program groups were increasing in monthly drug use prevalence rates at an average of half the rates of control groups at one year follow-up (3.4 vs 14.5% for cigarette use, 4.2 vs 9.6% for alcohol use (greater than 1 drink), 3.5 vs 7.6% for marijuana use); effects were similar for weekly use rates, and have been maintained at two year follow-up. Analyses of parent data at one year follow-up indicated that the odds of program group parents rating drug prevention practices and personal involvement in prevention programs as extremely important, discussing prevention with their children, and exercising regularly were higher compared to control group parents; and perceived child use of cigarettes and marijuana, and self-use of alcohol in the last week was lower (odds ratios averaged across prevention ratings for each substance = 1.85, 1.72, 1.37, 1.53; for use items .34, .73, .59; P less than .10-- .002).

Adolescent↗
PubMed1989

Inflammatory conditions of the major salivary glands.

The clinical features, diagnosis, management, and complications of inflammatory conditions affecting the major salivary glands are described. Acute and chronic infections arising primarily and secondary to predisposing causes are discussed, and cause and epidemiological factors are included as relevant. Noninfective inflammatory conditions are outlined.

Acute Disease↗
PubMed1989

Differential non-responsiveness in humans of candidate Plasmodium falciparum vaccine antigens.

Synthetic subunit vaccines to sporozoites, merozoites, and gametes are being developed for malaria. The vaccine strategy assumes that the population to be immunized will respond favorably to these vaccine antigens. Using sera of 35 adults and 50 children from the The Gambia, West Africa, where Plasmodium falciparum is highly endemic, we examined the humoral immune response to candidate malaria vaccine antigens from sporozoites, merozoites, and gametes. We observed widespread restricted immunogenicity to defined parasite antigens in children and adults. HLA typing of adult lymphocytes demonstrated a marked diversity in HLA haplotypes in this population. Our results and those from our studies in mice suggest that genetic factors may partly explain the immunological non-responsiveness. This may necessitate re-evaluation of the malaria vaccine strategy.

Adult↗
PubMed1989

A regional register of early childhood impairments: a discussion paper. The Steering Committee of the Oxford Region Child Development Project.

A regional register of preschool children with cerebral palsy, severe vision loss and sensorineural deafness has been complied. Case definition, the threshold for including or excluding a case and a standard method for describing a case have been predefined. In order to achieve complete ascertainment, multiple sources of information were used and account was taken of population movement, and loss of cases through death. The optimal age of case ascertainment poses a particular problem and counting of definite cases was delayed until age three years with a further review at age five years. The register can be used to estimate prevalence of impairment, as a basis for aetiological and interventive studies and for service planning. It fills an important gap in the information currently available on childhood morbidity.

Cerebral Palsy↗
PubMed1989

The unstable lower full denture--a practical and simple solution.

Advanced resorption of the mandibular residual ridge produces a flat or even concave base, which is characteristic of the "difficult lower jaw". The provision of dentures for such patients using conventional techniques often leads to an unstable and unsatisfactory result regardless of the accuracy of the fit of the denture base.

Bone Resorption↗