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Biomedical subjects

R A Johnson

Publications and source records attributed to R A Johnson.

At least 235 records · Page 13Linked to original sources
PubMed1983

Pelvic inflammatory disease.

The rising incidence of pelvic inflammatory disease (PID), coupled with the development of more sophisticated and effective diagnostic techniques, has created a new body of knowledge regarding the microbiology, diagnosis, and natural history of this disease. Acute pelvic inflammatory disease is the major gynecologic health problem in the United States. Distinguishing acute PID from the other causes of acute pelvic pain is often a difficult task. Careful consideration of a patient's risk profile for PID and utilization of the diagnostic techniques available are invaluable in helping the clinician accurately make this differentiation. The microbial spectrum involved in PID is complex and must be taken into consideration when selecting an antibiotic regimen. The recent addition of new, broad-spectrum antibiotics to the physician's therapeutic armamentarium has led to increasingly effective management options. Despite the effectiveness of current medical and surgical therapy, the staggering economic, medical, and social consequences of PID mandates more aggressive efforts at its prevention.

Adolescent↗
PubMed1983

Transient ischemic attacks.

Patients with transient cerebral ischemic attacks (TIAs) are generally felt to be at increased risk for stroke. A comprehensive clinical evaluation consisting of a thorough history and physical examination, as well as adjunctive laboratory and radiologic studies, is required to substantiate the diagnosis and to identify the underlying etiology. For patients with TIAs of atherothrombotic origin, the optimal course of management is still controversial. Although surgical therapy, antiplatelet therapy, and anticoagulant therapy have all shown promise in preventing stroke, their precise roles in the management of TIAs still await further elucidation.

Aged↗
PubMed1982

Treatment of acute abscesses in the casualty department.

In the treatment of acute pyogenic soft-tissue abscess incision, curettage, and primary suture was compared with incision and drainage alone in a randomised prospective trial. Operations were performed under antibiotic cover by casualty officers, and patients were reviewed by an independent observer in a septic dressing clinic. Altogether 114 patients were studied, of whom 54 were treated by curettage and primary suture and 60 by simple drainage. The mean healing time was 8.9 days in those treated by primary suture and 7.8 days in those treated by simple drainage (p less than 0.05). Primary healing failed to occur in 19 (35%) of the sutured wounds, but there were no other complications in either group. It is concluded that incision and drainage alone is adequate treatment for acute soft-tissue abscess.

Abscess↗
PubMed1982

Heart failure in outpatients: a randomized trial of digoxin versus placebo.

The view that digitalis clinically benefits patients with heart failure and sinus rhythm lacks support from a well-controlled study. Using a randomized, double-blind, crossover protocol, we compared the effects of oral digoxin and placebo on the clinical courses of 25 outpatients without atrial fibrillation. According to a clinicoradiographic scoring system, the severity of heart failure was reduced by digoxin in 14 patients; in nine of these 14, improvement was confirmed by repeated trials (five patients) or right-heart catheterization (four patients). The other 11 patients had no detectable improvement from digoxin. Patients who responded to digoxin had more chronic and more severe heart failure, greater left ventricular dilation and ejection-fraction depression, and a third heart sound. Multivariate analysis showed that the third heart sound was the strongest correlate of the response to digoxin (P less than 0.0001). These data suggest that long-term digoxin therapy is clinically beneficial in patients with heart failure unaccompanied by atrial fibrillation whose failure persists despite diuretic treatment and who have a third heart sound.

Adult↗
PubMed1982

Regulation of adrenergic stimulation of hepatic adenylate cyclase by divalent cations.

Liver plasma membrane adenylate cyclase was stimulated paradoxically by an alpha 2-adrenergic mechanism under conditions of low metal ion and low GTP concentrations. In untreated membranes, epinephrine stimulation was GTP-dependent and was mediated by beta-adrenergic receptors since it was completely blocked by propranolol, but unaffected by dihydroergocryptine. Pre-treatment of membranes to remove or reduce divalent cations and guanine nucleotides changed epinephrine stimulation to a form that was mediated by alpha 2-receptors since it was completely blocked by dihydroergocryptine, phenoxybenzamine and yohimbine, but not by propranolol or prazosin. The pre-treatment did not alter enzyme activation by isoproterenol or glucagon, alpha 2-Adrenergic stimulation of adenylate cyclase in depleted membranes required the presence in the assay of 1-2 mM Mg2+ and small amounts of exogenous GTP (less than or equal to 50 nM). Increasing the Mg2+ or GTP concentration in the assay produced a progressive reversal of epinephrine-stimulated activity from an alpha 2-adrenergic form to a predominantly beta-adrenergic form. Readdition of Ca2+ or Mg2+, but not Mn2+, into depleted membranes by incubation in the presence of metal reestablished the pattern of enzyme sensitivity to epinephrine to that seen with untreated membranes i.e., it changed from alpha 2- to beta-receptor mediation. Alterations in membrane and assay content of metal ions and GTP did not result in the activation of the enzyme by vasopressin or angiotensin II. These findings demonstrate the ability of Ca2+, Mg2+ and GTP to control the coupling of beta- and alpha 2-adrenergic receptors with liver adenylate cyclase. It is hypothesized that the cations act by regulating the interaction of the receptors with adrenergic agonists and/or the guanine nucleotide binding protein(s) which is postulated to be involved in control of the enzyme.

Adenylyl Cyclases↗
PubMed1982

Regulation of hepatocyte cAMP and pyruvate kinase by site-specific analogs of adenosine.

The effects of site-specific analogs of adenosine on cAMP content and pyruvate kinase activity of isolated rat hepatocytes were studied. N6-(phenylisopropyl) adenosine (PIA), a metabolically stable analog of adenosine which acts specifically at 'R' sites, increased cAMP content and decreased pyruvate kinase activity to about the same extent as did epinephrine, By contrast, adenosine itself was without effect. Consistent with 'R'-site mediated effects, the effects of PIA were blocked by 3-isobutyl-l-methylxanthine. 2'5'-Dideoxyadenosine, which acts specifically at 'p' sites to inhibit adenylate cyclase, counteracted the effects of epinephrine on pyruvate kinase, but paradoxically not the effects of PIA. The adenylate cyclase in membranes from these parenchymal cells was determined and was found to exhibit comparable sensitivity to 'R' site-specific analogs and other activators as did the enzyme prepared from whole liver. Thus, the data suggest that the effects on liver metabolism of 'R' site-specific analogs of adenosine are initiated by an adenosine-receptor coupled activation of adenylate cyclase and that these effects are characteristics of the parenchymal cells.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Isolation of enteroviruses from oxidation pond waters.

Enteroviruses were isolated from influent and effluent wastewaters of two types of oxidation lagoons during an 18-month study. Isolations, performed by sewage concentration and direct assay, were low in number and did not follow a seasonal trend. The younger treatment system, using aeration and effluent chlorination, was more efficient at removing viruses than the aging, static complex.

Enterovirus↗
PubMed1982

Respiratory syncytial virus infection in cyclophosphamide-treated cotton rats.

Cotton rats infected intranasally with respiratory syncytial virus and immunosuppressed with cyclophosphamide shed virus for at least 7 weeks. Dissemination of virus beyond the respiratory tract was observed. In contrast, virus was recovered from infected, non-immunosuppressed rats for only 1 week, and only from the respiratory tract.

Animals↗
PubMed1982

Asymptomatic carotid bruit.

The asymptomatic carotid bruit is not an uncommon finding in patients aged 45 years and older. The presence of such a finding has been associated with an increased incidence of stroke and cardiovascular death. The optimal evaluation and management of such patients are still unresolved. Noninvasive carotid evaluation appears to be useful for defining the degree of carotid artery stenosis and possibly in identifying a particular subset of patients at high risk for stroke. Whether patients with asymptomatic carotid bruits are best managed medically or surgically remains controversial and will require further investigation.

Carotid Artery Diseases↗