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Biomedical subjects

J Johnson

Publications and source records attributed to J Johnson.

At least 469 records · Page 26Linked to original sources
PubMed1989

A longitudinal analysis of selected risk factors for childhood psychopathology.

Eight-year and two-year longitudinal analyses of prevalence and risk factors for adult and adolescent psychopathology were carried out for a random sample of 776 children drawn from households in New York State. A 17.7% prevalence rate for one or more DSM-III disorders was estimated. In general, the risk factors studied were more related to externalizing than internalizing diagnoses. Risk factors assessed over 8-year and 2-year intervals were very similar.

Adolescent↗
PubMed1989

Hypoxic Induction of Anoxia Tolerance in Root Tips of Zea mays.

When root tips of fully aerobic, intact maize (Zea mays L.) seedlings are made anaerobic, viability normally is only 24 hours or less at 25 degrees C. We find that viability can be extended to at least 96 hours if seedlings are given a hypoxic pretreatment for 18 hours by sparging the solution with 4% O(2) in nitrogen (v/v) before anoxia. Fully aerobic root tips (sparged with 40% O(2)) had very low alcohol dehydrogenase (ADH) activity (per gram root fresh weight), and the level remained low under anoxia. In hypoxically pretreated roots, however, high levels of ADH activity were induced, and activity rose further during the initial 24 hours of anoxia, and then remained high at about 20 times that of controls in 40% O(2). ADH activity in roots in solution sparged with air (21% O(2)) was about three times that in 40% O(2). Improved viability of hypoxically pretreated root tips was associated with maintenance of a high energy metabolism (ATP concentration, total adenylates, and adenylate energy charge). Roots that were not pretreated lost 94% of the total adenylates and ATP at 24 hours of anoxia. The relation between induced ADH activity, energy metabolism, and improved anoxia-tolerance in acclimated maize root tips is discussed.

Journal Article↗
PubMed1989

Discrepant toxoplasma latex agglutination test results.

The analysis of 4450 toxoplasma serology results showed that 59 (1.3%) latex agglutination reactions were not confirmed in the dye test. These discrepant results were associated with an unspecified IgM antibody but not associated with kit batch variation, inactivation of sera, concurrent cytomegalovirus infection, or the presence of hepatitis B virus "e" antigen. The latex agglutination test is useful as a screen for toxoplasma infection but false positive reactions do occur. Patients at risk of severe toxoplasmosis should be investigated by additional tests.

Animals↗
PubMed1989

Direct agglutination test and other assays for measuring antibodies to Toxoplasma gondii.

The performance of a direct agglutination test for the detection of toxoplasma specific IgG immunoglobulin was compared with that of the latex agglutination test. The direct agglutination test was less sensitive but more specific than the latex agglutination test. Quantitative results were not directly comparable, reflecting the different antibody profiles detected in each assay. The direct agglutination test represents an alternative to the latex agglutination test as a screening test for toxoplasmosis. Patients at risk of life threatening infection require detailed serological examination using additional assays.

Agglutination Tests↗
PubMed1989

Human recombinant tumor necrosis factor alpha infusion mimics endotoxemia in awake sheep.

The macrophage-derived cytokine tumor necrosis factor alpha (TNF alpha) has been proposed as the major mediator of endotoxin-induced injury. To examine whether a single infusion of human recombinant TNF alpha (rTNF alpha) reproduces the pulmonary effects of endotoxemia, we infused rTNF alpha (0.01 mg/kg) over 30 min into six chronically instrumented awake sheep and assessed the ensuing changes in hemodynamics, lung lymph flow and protein concentration, and number of peripheral blood and lung lymph leukocytes. In addition, levels of thromboxane B2, 6-ketoprostaglandin F1 alpha, prostaglandin E2, and leukotriene B4 were measured in lung lymph. Pulmonary arterial pressure (Ppa) peaked within 15 min of the start of rTNF alpha infusion [base-line Ppa = 22.0 +/- 1.5 (SE) cmH2O; after 15 min of rTNF alpha infusion, Ppa = 54.2 +/- 5.4] and then fell toward base line. The pulmonary hypertension was accompanied by hypoxemia and peripheral blood and lung lymph leukopenia, both of which persisted throughout the 4 h of study. These changes were followed by an increase in protein-rich lung lymph flow (base-line lymph protein clearance = 1.8 +/- 0.4 cmH2O; 3 h after rTNF alpha infusion, clearance = 5.6 +/- 1.2), consistent with an increase in pulmonary microvascular permeability. Cardiac output and left atrial pressure did not change significantly throughout the experiment. Light-microscopic examination of lung tissue at autopsy revealed congestion, neutrophil sequestration, and patchy interstitial edema. We conclude that rTNF alpha induces a response in awake sheep remarkable similar to that of endotoxemia. Because endotoxin is a known stimulant of TNF alpha production, TNF alpha may mediate endotoxin-induced lung injury.

Animals↗
PubMed1989

Outpatient myelography: an acceptable and cost-effective technique.

Sixty-five patients with stable low back pain had their lumbar myelography performed as outpatients, staying in the department for 1 h after the examination. The incidence of post-myelogram headache was similar to that reported for inpatients. No serious after-effects occurred in the study group. The vast majority of patients preferred to be at home following the study. It is concluded that outpatient myelography is safe, less expensive and preferred by the patients.

Adult↗
PubMed1989

Characterization and partial purification of the cockroach antigen in relation to housedust and housedust mite (D.f.) antigens.

Allergens in crude cockroach antigens (CRa) have not been well defined. In order to characterize the CRa, the authors partially purified CRa by gel filtration (G-75) and analyzed it by polyacrylamide electrophoresis (PAGE) and allergy skin testing (AST). Hyperimmune serum was produced against CRa in rabbit (R anti-CRa) and used for immunoelectrophoresis (IEP), double immunodiffusion (DID), crossed immunoelectrophoresis (CIE), and crossed radio immunoelectrophoresis (CRIE) to further characterize the CRa. The crude CRa contained 9 and 15 precipitating arcs by IEP and CIE, respectively. Indirect CRIE revealed that CRa contained nine to 15 different allergens. There were no lines of identity between the CRa and housedust mite (D.f.) or between the CRa and commercial housedust by DID or IEP. Autologous housedust of cockroach asthmatic subjects showed lines of identity with the CRa. Fractionation of CRa on a Sephadex G-75 column chromatography showed two distinct peaks (B1 and B2) separated by a broad valley. The high molecular fraction B1 was most allergenic (100%) and contained three antigens of high molecular weight. These three antigens were identifiable by the techniques of IE, CIE, and DID. B2, the low molecular fraction (molecular weight less than 13,000 dalton) contained minor allergen(s). B2 elicited positive AST in 55% of cockroach-sensitive individuals, but it was not detected by IEP, CIE, nor by DID.

Allergens↗
PubMed1989

Prevention of deep vein thrombosis in potential neurosurgical patients. A randomized trial comparing graduated compression stockings alone or graduated compression stockings plus intermittent pneumatic compression with control.

In a randomized trial of neurosurgical patients, groups wearing graduated compression stockings alone (group 1) or graduated compression stockings plus intermittent pneumatic compression (IPC) (group 2) were compared with an untreated control group in the prevention of deep vein thrombosis (DVT). In both active treatment groups, the graduated compression stockings were continued for 14 days or until hospital discharge, if earlier. In group 2, IPC was continued for seven days. All patients underwent DVT surveillance with iodine 125-labeled fibrinogen leg scanning and impedance plethysmography. Venography was carried out if either test became abnormal. Deep vein thrombosis occurred in seven (8.8%) of 80 patients in group 1, in seven (9.0%) of 78 patients in group 2, and in 16 (19.8%) of 81 patients in the control group. The observed differences among these rates are statistically significant. The results of this study indicate that graduated compression stockings alone or in combination with IPC are effective methods of preventing DVT in neurosurgical patients.

Clinical Trials as Topic↗
PubMed1989

Gastrinoma: the predictive value of preoperative localization.

In the management of gastrinoma, a variety of preoperative tests for tumor localization are recommended. Their value in predicting surgical outcome is not well defined. We reviewed the preoperative investigation and operative outcome in 23 patients to assess the predictive value of localization before surgery. With results of laparotomy used as reference, the efficacy of computed tomography, angiography, ultrasonography, and magnetic resonance imaging, individually and combined for primary and metastatic disease, was determined. All investigative modalities were poor for the detection of primary gastrinomas, with individual sensitivities in the range of 20% to 29%. Their combined sensitivity was 53%, with a negative predictive value of only 38%. The detection of metastatic disease was better, with a combined accuracy of 83%. At laparotomy, tumor was identified in 19 of 23 (83%) patients. In 14 patients with negative preoperative workup, primary gastrinoma was found in 10 of 14 (71%) and resected for long-term cure in three of 14 (21%) patients. In all nine patients with positive preoperative test results, tumor was found and was resected for cure in four (44%) patients. In conclusion, preoperative localization of primary gastrinoma is unreliable, and a negative workup does not preclude cure. Therefore, despite the availability of effective palliative antiulcer therapy, all patients exclusive of those with multiple endocrine neoplasia, type I, or metastasis should undergo laparatomy with curative resection in mind.

Angiography↗
PubMed1989

Mechanisms of splenic control of murine malaria: tissue culture studies of the erythropoietic interplay of spleen, bone marrow, and blood in lethal (strain 17XL) Plasmodium yoelii malaria in BALB/c mice.

This work characterizes the erythropoietic interplay of the spleen, blood, and bone marrow in a lethal murine malaria, strain 17XL P. yoelii. This malaria runs a fulminant 7 day course in BALB/c/ByJ mice, marked by high levels of parasitized reticulocytes with death likely due to anemia. We have quantitated the levels of burst forming units-erythroid (BFU-E), the early, niche-seeking, largely erythropoietin-unresponsive erythropoietic precursors, and of colony forming units-erythroid (CFU-E), the more differentiated sessile erythropoietin-responsive precursors, in bone marrow, blood, and spleen, through the course of this malaria. A decline in marrow BFU-E began on day 2, but recovered, relatively, after day 3. Marrow cellularity declined, being but 75% normal on day 6. Spleen weight increased about 5-fold within 6 days with enlargement of erythroid, lymphoid, macrophage, and stromal compartments. Splenic BFU-E increased in the first 24 hr and 5-fold by day 6. Splenic CFU-E increased in the first 24 hr and into day 4. They then declined and showed a secondary, large-scale, sustained rise interrupted by death. Because the spleen was enlarging, a greater than 60-fold increase in the absolute number of splenic CFU-E occurred at the time of death. Marrow CFU-E followed the same pattern as splenic CFU-E, but the terminal increase represented but a 4-fold absolute increase because of declining marrow cellularity. High levels of erythropoietin occurred only late in the course of disease, likely in response to profound anemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Optic disc cupping: prevalence findings from the WESDR.

Increased cupping of the optic disc is considered to be an indication of pressure-related damage of the optic nerve. This paper explores the relationship of intraocular pressure and cupping in persons with diabetes mellitus, a group of people whose optic nerves may be more susceptible to the effects of intraocular pressure. Stereoscopic fundus photographs of the seven standard fields were obtained in all persons participating in the Wisconsin Epidemiologic Study of Diabetic Retinopathy at the time of the initial prevalence survey. Measurements of disc and cup diameters in the vertical and horizontal meridia were made by two trained graders. Cup-to-disc ratios were computed for both diameters of each eye and the mean of the two gradings was used. A history of glaucoma was significantly associated with larger cup-to-disc ratios at the prevalence examination. Cup-to-disc ratios were not larger in those with high IOP, nor in those who had panretinal photocoagulation.

Adult↗
PubMed1989

Optic disc cupping: four year follow-up from the WESDR.

Change in optic disc cupping was evaluated in a 4-year follow-up of a well defined cohort of people with diabetes mellitus. Cup-to-disc ratios were computed for both vertical and horizontal diameters of each eye at the baseline and 4-year follow-up examinations. Graders were masked as to the identity of participants and to the dates of the photographs. Increases of at least 0.1 between baseline and follow-up were used as clinically significant change in the ratios. None of the following factors at baseline were consistent predictors of such a change: intraocular pressure, age, duration of diabetes, hypertension or severity of diabetic retinopathy. People who developed proliferative retinopathy by the follow-up examination were not more likely to have such an increase in ratio at the follow-up. We conclude that clinically significant increases in cup-to-disc ratio cannot be consistently predicted in people with diabetes from the risk factors evaluated with the grading system used in this study.

Diabetes Complications↗
PubMed1988

Construction, expression, and function of a new yeast amber suppressor, tRNATrpA.

The number of different tRNA species in Saccharomyces cerevisiae known to be capable of suppressing termination of translation at UAG, UAA, and UGA codons is limited to those which insert tyrosine, leucine, and serine. Suppressor tRNAs that insert other amino acids, even those whose anticodons differ from the expected recognition sequences for nonsense codons by a single nucleotide, have never been identified via classical genetic analysis. We have used site-directed mutagenesis to convert the anticodon of a cloned tRNATrp gene from CCA to CTA with the expectation that this gene would produce tRNA molecules capable of interacting with the UAG terminator codon. We show that this form of the gene can be transcribed and spliced in vitro to produce mature tRNA with the expected base sequence. The putative suppressor gene has been introduced into several S. cerevisiae host strains using the centromere vector YCp19. Efficient suppression of amber mutations met8-1, tyr7-1, and lys2-801 results from the presence of the CTA form of tDNATrp. Two UAA mutants, leu2-1 and ade2-101, and the UGA marker his4-260 are not suppressed.

Bacterial Proteins↗