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Biomedical subjects

B Johnston

Publications and source records attributed to B Johnston.

At least 73 records · Page 4Linked to original sources
PubMed1995

The care plan conundrum.

Explore the source record for details and available documents.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1995

Oral and topical treatment of erectile dysfunction. Present and future.

A great deal of progress has been made in the pharmacological treatment of erectile dysfunction. At present, however, the most effective therapies require intracavernosal injections with a number of associated drawbacks. An increasing number of oral and transdermal agents have been introduced clinically or are at various phases in their development. It is evident that severe end-organ disease probably will not result in successful systemic therapy. Nevertheless, in men with intact or mildly dysfunctional erectile mechanisms, noninvasive treatments can offer some measure of success. Further study of individual and synergistic activity of available compounds is underway.

Administration, Oral↗
PubMed1994

Diurnal penile tumescence recording in the etiological diagnosis of erectile dysfunction.

Rapid eye movement sleep occurs during napping. We investigated the appearance of penile tumescence during periods of day napping in a population of 18 impotent men who, in addition, underwent a comprehensive sleep investigation for impotence, including polysomnographic recording and nocturnal penile tumescence monitoring. Of the subjects 16 (88%) had rapid eye movement sleep during the night. Four patients who did not have erections on 2 separate sessions of nocturnal sleep recording also did not experience penile tumescence during the day. Of the 12 patients with documented erections at night 9 (75%) also exhibited erectile episodes during napping. Diurnal penile tumescence recording is less cumbersome, less expensive and more convenient to perform than its nocturnal counterpart. Diurnal penile tumescence appears to be a summary reflection of nocturnal penile tumescence episodes. The consistency between nocturnal and diurnal penile tumescence suggests that further study of this new technique is worthwhile. Validation of diurnal penile tumescence may offer a viable alternative to the comprehensive assessment of impotent men.

Circadian Rhythm↗
PubMed1994

Oral androgens in the treatment of hypogonadal impotent men.

A study was designed to assess the effect of supplemental oral methyltestosterone in the treatment of impotence associated with low total serum androgen levels. A total of 22 hypogonadal impotent men underwent a comprehensive investigation of erectile dysfunction, including an evaluation of the pituitary-gonadal axis. The patients then received a 1-month course of 2 different commercial preparations of oral methyltestosterone. Hormonal changes induced by the medication were assessed on days 15 and 30 of treatment. The patients kept daily records of sexual activity, and completed visual analogue scales to assess energy levels, mood and sensation of well being on a weekly basis. Supra-physiological levels of total serum testosterone were achieved in every patient but the free fraction of the hormone did not increase proportionally and in many cases a marked decrease was recorded. In all but 1 subject there was a decrease in circulating sex hormone binding globulin. Pituitary gonadotropin levels showed a marked decrease at the end of treatment. The clinical response was disappointing. Only 9% of the patients reported a complete recovery of sexual function. Visual analogue scales did not reveal noticeable changes for any individual in the levels of energy, mood or feeling of well being between pretreatment and posttreatment assessments. Oral methyltestosterone is of limited effectiveness in men with hypogonadal impotence. The positive responses in this study were recorded in men with the most profound deficiency. Exogenous administration of androgens to impotent men should be limited to those with profound hypogonadism as documented by at least 2 abnormal serum free testosterone determinations.

Administration, Oral↗
PubMed1993

Continuous retrograde cerebral perfusion during an aortic arch operation.

An 81-year-old woman presented with acute aortic regurgitation in the setting of an aneurysm of the ascending aorta and arch. The aortic valve, ascending aorta, and arch were replaced with a composite graft during continuous hypothermic total-body perfusion. Continuous cerebral perfusion was carried out by low-pressure retrograde perfusion via the superior vena cava while perfusion of the lower body was maintained via a femoral arterial cannula.

Aged↗
PubMed1993

Smoking may be dangerous to your (sex) life.

One of the effects of smoking on penile arteries and veins is impotence. The nurse has a responsibility to educate patients about this effect and to help them quit smoking if this is their goal. The authors apply a teaching model used with other patient populations to facilitate this teaching-learning process.

Adult↗
PubMed1993

Splenectomy does not enhance engraftment of DLA-nonidentical marrow transplants.

Previous studies in mice and monkeys suggested that either splenic irradiation of splenectomy led to enhanced allogeneic marrow engraftment. These findings suggested that a population of radiation-resistant host cells involved in mediating marrow graft rejection are sequestered in the spleen. In this current study, the effect of splenectomy in dogs receiving 9.2 Gy total body irradiation (TBI) and unrelated dog leukocyte antigen (DLA)-nonidentical donor marrow grafts was studied. We found that splenectomy did not significantly change the incidence of graft failure as compared to that observed in previously and concurrently transplanted nonsplenectomized recipients.

Animals↗
PubMed1993

Population-based study of fall injuries in children and adolescents resulting in hospitalization or death.

OBJECTIVE: To determine the incidence and characteristics of fall-related injuries to children and adolescents. DESIGN: Population-based study. SETTING: All hospital discharges in Washington State for fall-related injuries in 1989 and 1990. POPULATION: Children and adolescents 19 years and younger. RESULTS: Falls accounted for nearly one third of all trauma admissions, and fall patients tended to be younger than those with other injuries. Falls from one level to another accounted for 40% of the total. One fourth of all patients and 42% of preschoolers sustained head injury. The annual cost of these injuries in Washington State was $4.5 million.

Accidental Falls↗
PubMed1992

Discriminant analysis when all variables are ordered.

Determination of the equation that relates an ordered dependent variable to ordered independent variables is sought. One solution, non-parametric discriminant analysis (NPD), involves obtaining the best monotonic step function by means of a computer search procedure. Although one can use alternative selection criteria in obtaining the equation, the illustrative examples use absolute distance. This paper compares the prediction procedures obtained from NPD with those from linear discriminant analysis, linear regression (with and without transformed variables), and logistic regression. We show that NPD is analogous to regression tree analysis with incorporation of ordered variables and monotonicity. We use various prediction functions to predict the example data, the data using the leave-one-out technique, and a verification set. Consistently, non-parametric discriminant analysis performs as good as or better than the tested alternatives.

Craniocerebral Trauma↗
PubMed1992

Rate-corrected mean velocity of fiber shortening-stress at peak systole as a load-independent measure of contractility.

The relation of mean velocity of fiber shortening-stress at end-systole is a good load-independent index of left ventricular contractility, but involves simultaneous M-mode echocardiography, carotid tracing and blood pressure determination, which may be impractical in children. As stress at peak systole and end-systole are closely related, this study examined whether the relation of mean velocity of fiber shortening-stress at peak systole could be used as a simpler method of assessing left ventricular contractility in a normal population of children. In addition, the cross-sectional normal range for a pediatric population was obtained. In 25 normal children aged 4 to 17 years (mean age 11), rate-corrected mean velocity of fiber shortening (MVCFc), stress at peak systole (sigma PS), and end-systolic stress (sigma ES) were determined using echocardiography, carotid pulse tracing and blood pressure measurement. Six patients with cardiomyopathy (mean age 8 years) were also studied. The relation of stress at peak systole and end-systolic stress was sigma PS = 1.004 sigma ES + 12.0 (r = 0.91, SEE = 4.98; p less than 0.001) for the normal group, and sigma PS = 1.083 sigma ES + 7.7 (r = 0.99, SEE = 4.07; p less than .001) for the cardiomyopathic group. This slope of the regression line was slightly higher and the difference was statistically significant. The slope of MVCFc = 0.0066 sigma PS + 1.55 (SEE = 0.131, r = -0.52) was nearly identical to that of MVCFc = 0.0065 sigma ES + 1.46, (SEE = 0.135, r = -0.46), with no difference in the regression coefficients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Inhaled steroids in patients with bronchiectasis.

The effect of inhaled beclomethasone diproprionate (1500 micrograms day-1) on symptoms, pulmonary function and sputum production was examined in a double-blind, placebo-controlled, cross-over study in 20 patients with bronchiectasis. An 18% reduction in daily sputum production (P less than 0.003) was observed on treatment with inhaled steroid compared to placebo. A small, significant, improvement in morning peak expiratory flow rate (P less than 0.03) and forced expiratory volume in 1 s (P less than 0.03) was seen but the absolute changes are unlikely to be of clinical importance. Symptom scores for cough improved significantly (P less than 0.02). Inhaled steroids may have a role in the management of bronchiectasis by reducing cough and sputum production.

Administration, Inhalation↗
PubMed1992

Pharmacologic, toxicologic, and marrow transplantation studies in dogs given succinyl acetone.

A novel immunosuppressant, succinyl acetone (4,6-dioxoheptanoic acid), was studied in dogs. Results with bolus intravenous injections at doses ranging from 50 to 1600 mg/kg showed dose-dependent alpha and beta half-lives, ranging from 30 to 80 min and 7 to 27 hr, respectively. Results suggested that continuous i.v. infusion was necessary to maintain constant plasma levels. Four dogs were given 9.2 Gy total-body irradiation and autologous marrow transplants along with continuous i.v. infusion of succinyl acetone at 50, 100, 200, or 400 mg/kg/day for 21 days, and all four had rapid, sustained hematopoietic engraftment. However, two of the four dogs receiving 200 and 400 mg succinyl acetone/kg/day, respectively, developed bilateral hind-limb ataxia, with histologically confirmed cerebellar lesions in the dog given the higher dose, thus establishing a potential dose-limiting neurotoxicity. Prevention of graft-versus-host disease was studied in recipients of allogeneic marrow. Dogs were given 9.2 Gy TBI, followed by hematopoietic grafts from unrelated DLA-nonidentical or DLA-haploidentical littermate dogs. Succinyl acetone was given as continuous infusion for 21 days after transplant at doses of 100-300 mg/kg/day. Starting succinyl acetone on the day of marrow infusion in four dogs failed to prevent rapid onset of acute GVHD, and dogs survived no longer than controls. Starting succinyl acetone 3 days before transplant delayed the onset of acute GVHD and prolonged survival significantly compared with that of dogs not given postgrafting immunosuppression (P = 0.008); survival was comparable to that in previously reported dogs given either methotrexate or cyclosporine as postgrafting immunosuppression (P = 0.88 and 0.99, respectively). Seven of the sixteen allogeneic recipients developed evidence of neurotoxicity during succinyl-acetone infusion. Neurological dysfunctions were manifested by hind-limb ataxia and posterior paresis. In conclusion, succinyl acetone significantly delayed the onset of GVHD and prolonged survival of DLA-nonidentical marrow graft recipients but did not induce graft-host tolerance and was associated with dose-limiting neurotoxicity.

Animals↗
PubMed1991

Relevance of pH dependency on in vitro release of bromocriptine from a modified-release formulation.

Since pH profiles of the dissolution rate are thought to be predictive for the in vivo performance of oral modified-release formulations with respect to bioavailability and dose dumping with food, these pH profiles were established for a new modified-release (MR) formulation for bromocriptine (Parlodel SRO). The results show a marked decrease of bromocriptine dissolution with increasing pH of the dissolution medium. However, when measured in native human duodenal juice (pH 8.1), dissolution was significantly higher than when measured in buffer of comparable pH. In a human pharmacokinetic study, this MR formulation showed good bioavailability and no food effect on the pharmacokinetic profile. Therefore, pH profiles alone seem to have only a limited predictive power for the in vivo performance of this MR formulation for bromocriptine.

Bromocriptine↗