Search PubMed⌕ Search

Biomedical subjects

R A Johnson

Publications and source records attributed to R A Johnson.

At least 199 records · Page 11Linked to original sources
PubMed1986

Suppurative thrombophlebitis: correlation between pathogen and underlying disease.

We identified 29 episodes of suppurative thrombophlebitis in 27 patients admitted to a large general hospital between May 1980 and May 1984. In 25 patients, the intravenous cannulae had been in place for more than 3 days. Streptococcus faecalis, Pseudomonas aeruginosa or one of the Enterobacteriaceae were implicated in 14 patients. All these patients had recently undergone abdominal surgery or had a major intra-abdominal inflammatory process at the time they developed thrombophlebitis. The remaining 13 patients were infected with Staphylococcus aureus, other gram-positive cocci or Candida species. Only two of these had an active abdominal process at the time of their infection (chi 2 = 16.08, P less than 0.001). There is an apparent association between phlebitis caused by enteric organisms and active intra-abdominal pathology. There were two deaths related to delayed or deferred surgery. Suppurative thrombophlebitis is a lethal, preventable nosocomial infection that requires urgent surgical intervention.

Abdomen↗
PubMed1986

Thromboxane A2 synthase inhibitors. 5-(3-Pyridylmethyl)benzofuran-2-carboxylic acids.

The synthesis and screening of a series of 5-(3-pyridylmethyl)benzofuran-2-carboxylic acids as selective thromboxane A2 (TxA2) synthase inhibitors is outlined. The ability of these compounds to inhibit TxA2 biosynthesis was assayed using microsomal enzyme from human platelets. Substitution of the benzofuran ring caused small changes in potency; modification of the carboxylic acid group caused modest reductions in potency, and substitution of the pyridine ring resulted in large reductions of potency. 5-(3-Pyridylmethyl)benzofuran-2-carboxylic acid sodium salt (9b, sodium furegrelate) was chosen for further evaluation as a TxA2 synthase inhibitor.

Animals↗
PubMed1986

Adverse reactions in ten years' general practice, computer analysed.

A total of 167 264 symptoms were recorded in numerical shorthand during a ten years period in a general practice. Computer analysis yielded 1535 adverse reactions with the drug prescribed. Especially prominent were reactions from three antibiotics (13% of all reported reactions), most of which were alimentary symptoms. Ampicillin also induced rashes reported at a rate of 5.2 per thousand prescriptions. Reactions to an oral contraceptive (Minovlar) were the most frequent to a single named drug, being 25.9% of prescriptions for that drug. A worldwide total of around one trillion symptoms seems likely before AD 2000. Computers could be used to detect the unpredictable side effects, as with practolol. Various 'costs' involved are noted, together with wider questions.

Ampicillin↗
PubMed1986

Suppression of humoral and cell-mediated immune responses in vitro by benzo(a)pyrene.

The effect of benzo(a)pyrene (BaP) at different molar (M) concentrations on the in vitro anti-sheep red blood cell (SRBC) plaque (antibody) forming cell (PFC) response and the one-way mixed lymphocyte response (MLR) was tested. Inhibition of the PFC response and the MLR occurred when spleen cells were exposed to a wide range of BaP concentrations from 10(-4) M to 10(-8) M. Maximum depression of the responses occurred at 10(-5) M for PFC production (47% of controls) and for the MLR (19% of controls) as measured by a stimulation index. No significant loss in cell viability was observed at this or lower molar concentrations of BaP. The non-carcinogenic analog of BaP, benzo(e)pyrene, did not suppress PFC responses at comparable concentrations. This in vitro system will facilitate manipulations of T and B lymphocytes and macrophages (adherent cells) in a controlled culture environment for precisely characterizing the sensitivity of these cells and their subpopulations on exposure to BaP.

Animals↗
PubMed1985

Ninhibin: a sperm factor attenuates the atrial natriuretic factor mediated inhibition of adenylate cyclase: possible involvement of inhibitory guanine nucleotide regulatory protein.

The effect of ninhibin, a sperm factor extracted from bovine sperm, was studied on adenylate cyclase from rat aorta. Ninhibin treatment of the membranes activated adenylate cyclase in a concentration dependent manner. The maximal activation (approximately equal to 4-fold) was obtained at 2micrograms ninhibin and at 10 min of treatment at 37 degrees C. On the other hand, in untreated control membranes, ninhibin at 2 micrograms could stimulate adenylate cyclase by about 50-60% only. In addition, ninhibin potentiated the guanine nucleotide-, isoproterenol- and forskolin (FSK)-stimulated adenylate cyclase activities and also attenuated the GTP gamma s and atrial natriuretic factor (ANF)-mediated inhibition of enzyme activities. Furthermore the inhibition of isoproterenol- and FSK-stimulated adenylate cyclase activities by ANF was also abolished by ninhibin. These data indicate that ninhibin which has been suggested to inactivate or inhibit Ni-guanine nucleotide regulatory protein can also attenuate the ANF-receptor mediated inhibition of adenylate cyclase in rat aorta suggesting an involvement of Ni-guanine nucleotide regulatory protein in the coupling of ANF receptors to adenylate cyclase.

Acrosin↗
PubMed1985

Active myocarditis in the spectrum of acute dilated cardiomyopathies. Clinical features, histologic correlates, and clinical outcome.

We studied the clinical features and course (average follow-up time, 18 months) of 27 patients with acute dilated cardiomyopathy (symptoms for less than 6 months) who were referred for endomyocardial biopsy. Almost 40 per cent of the patients subsequently had a rise in left ventricular ejection fraction (on average, from 0.21 to 0.41) and substantial improvement in heart failure; the remainder died or had chronic dilated cardiomyopathy. Biopsy revealed myocarditis in 18 patients, and this finding was especially common (89 per cent) in patients who had been ill for less than four weeks. But the biopsy specimen was negative in four patients whose clinical features and later course were diagnostic of myocarditis. Nine patients received immunosuppressive drugs, and four improved--a rate that did not differ from the rate of spontaneous improvement. Neither the histologic features of the biopsy specimen nor the clinical features at presentation were clearly correlated with subsequent improvement, whether or not immunosuppressive drugs were given. We conclude that many cases of unexplained dilated cardiomyopathy result from myocarditis. Definitive histologic confirmation depends on the duration of illness. The efficacy of immunosuppressive treatment must still be established.

Acute Disease↗
PubMed1985

Extraction of the adenylate cyclase-activating factor of bovine sperm and its identification as a trypsin-like protease.

We previously reported the activation of adenylate cyclases from rat brain (Johnson, R. A., Awad, J. A., Jakobs, K. H., and Schultz, G., (1983) FEBS Lett. 152, 11-16) and from human platelets (Jakobs, K. H., Johnson, R. A., and Schultz, G. (1983) Biochim. Biophys. Acta 756, 369-375) by a factor derived from bovine sperm. In this report we describe the conditions for the extraction of the factor from bovine sperm and characteristics of its effects on adenylate cyclase which are consistent with its being a protease. The activating capacity of sperm particles was extracted from previously washed and frozen sperm into a 30,000 X g supernatant fraction by various salts, but not by the nonionic detergent Lubrol-PX. The amount of extracted factor: (a) was greatest with NH4HCO3 greater than NaCl greater than Na acetate; (b) was optimal with 0.5 M salt; (c) was not appreciably affected by the pH of the extraction buffer between pH 5.0 and 8.5; and (d) exhibited the greatest specific activity at the lower pH. The extracted sperm factor could be concentrated without loss by ultrafiltration on Amicon PM-10 membranes. The effect on adenylate cyclase of concentrated and desalted sperm extracted was inhibited 50% by various salts at 10 to 30 mM. The effects of the sperm factor to activate platelet adenylate cyclase, to block its inhibition via the alpha-adrenoceptor, and to block inhibition of stimulated forms of the enzyme by stable guanine nucleotides were prevented by protease inhibitors. A 50% reduction in the sperm factor's activation of platelet adenylate cyclase was caused by 30 nM soybean trypsin inhibitor, 30 nM alpha 2-macroglobulin, 300 nM leupeptin, 1 microM antipain, 15 microM aprotinin, and 100 microM benzamidine. Up to 3 mM phenylmethanesulfonyl fluoride was without effect on activation of the platelet cyclase by the sperm factor. The effects of the sperm factor persisted after its removal by the washing of pretreated platelet membranes and after its inactivation by the subsequent addition of leupeptin. The data strongly support the conclusion that the bovine sperm factor is a trypsin-like protease. alpha-Chymotrypsin, trypsin, and sperm acrosin were comparably effective in stimulating the platelet adenylate cyclase 5- to 8-fold, with concentrations eliciting maximal stimulation being: 200 ng trypsin/ml; 2 micrograms alpha-chymotrypsin/ml; and 2 micrograms acrosin/ml.(ABSTRACT TRUNCATED AT 400 WORDS)

Acrosin↗
PubMed1985

An analysis of physicians' reasons for prescribing long-term digitalis therapy in outpatients.

We examined by medical-record review why long-term digitalis therapy was prescribed in 150 outpatients, the reasons were: supraventricular tachyarrhythmias (35): supraventricular tachyarrhythmias and heart failure (33); and heart failure with sinus rhythm (82). In the patients without supraventricular tachyarrhythmias we scrutinized the diagnosis of heart failure using a clinicoradiographic scoring system and found the diagnosis unlikely in 32 patients. When these 32 patients are combined with the 31 patients who had only one occurrence of supraventricular tachyarrhythmias or heart failure, 42% of the patients were on long-term digitalis therapy for a questionable reason. We conclude that a substantial fraction of general medical outpatients might benefit from digitalis withdrawal, if evidence for heart failure is lacking or if the reason prompting digitalis therapy is isolated to the distant past.

Aged↗
PubMed1985

Addition of a topically applied corticosteroid to a modified Goeckerman regimen for treatment of psoriasis: effect on duration of remission.

A double-blind parallel group study was undertaken to assess the effect of adding a topically applied corticosteroid cream to a modified Goeckerman regimen to treat patients with psoriasis. Nineteen patients with psoriasis were treated with either this regimen and hydrocortisone valerate cream or the regimen and vehicle cream. Patients were given daily treatments until their skin cleared or until twenty-eight treatments were received. They were then followed up until rebound or relapse occurred or 6 months had passed. The addition of hydrocortisone valerate cream to the modified Goeckerman regimen led to relapse after 5.9 weeks in comparison with 17.9 weeks for the control group.

Administration, Topical↗
PubMed1985

Prognostic value of a coronary artery jeopardy score.

The prognostic value of a coronary artery jeopardy score was evaluated in 462 consecutive nonsurgically treated patients with significant coronary artery disease, but without significant left main coronary stenosis. The jeopardy score is a simple method for estimating the amount of myocardium at risk on the basis of the particular location of coronary artery stenoses. In patients with a previous myocardial infarction, higher jeopardy scores were associated with a lower left ventricular ejection fraction. When the jeopardy score and the number of diseased vessels were considered individually, each descriptor effectively stratified prognosis. Five year survival was 97% in patients with a jeopardy score of 2 and 95, 85, 78, 75 and 56%, respectively, for patients with a jeopardy score of 4, 6, 8, 10 and 12. In multivariable analysis when only jeopardy score and number of diseased vessels were considered, the jeopardy score contained all of the prognostic information. Thus, the number of diseased vessels added no prognostic information to the jeopardy score. The left ventricular ejection fraction was more closely related to prognosis than was the jeopardy score. When other anatomic factors were examined, the degree of stenosis of each vessel, particularly the left anterior descending coronary artery, was found to add prognostic information to the jeopardy score. Thus, the jeopardy score is a simple method for describing the coronary anatomy. It provides more prognostic information than the number of diseased coronary arteries, but it can be improved by including the degree of stenosis of each vessel and giving additional weight to disease of the left anterior descending coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1985

Clinical anaesthetic knowledge amongst surgical house staff.

Knowledge of common anaesthetic drugs, techniques and complications amongst junior surgical staff at a typical district general hospital is assessed. The implications for patient care are discussed and suggestions made for improved education.

Anesthesiology↗
PubMed1985

The diagnosis of ectopic pregnancy.

Recent developments in pregnancy testing, pelvic ultrasound, and diagnostic laparoscopy have enabled the physician to make an early and accurate diagnosis. Familiarity with these diagnostic aids is critical since prompt diagnosis will reduce the likelihood of life-threatening intraperitoneal hemorrhage and may allow more conservative surgery to be performed.

Blood Cell Count↗
PubMed1985

Mechanical ventilation of critically ill newborns on scheduled flights of commercial passenger aircraft.

Transport of critically sick neonates of any gestation on scheduled commercial passenger aircraft is practical, safe, and cost effective. There is no disruption to boarding or egress of passengers and no seats need be removed or rearranged. Civil Aviation and Federal Aviation Authority regulations are obeyed. Power supply modifications and strengthening of the transport incubator are necessary. Other standard neonatal intensive care equipment can be used in battery mode. Replacement of an endotracheal tube in-flight is not difficult.

Aircraft↗