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Biomedical subjects

M F Johnson

Publications and source records attributed to M F Johnson.

53 records · Page 3Linked to original sources
PubMed1986

Some issues in the design and interpretation of 'negative' clinical studies.

The objective of most comparative trials is to show a "positive" result whereby one treatment is significantly better than another. However, the motivation behind some trials is to demonstrate a "negative" result that two treatments are equally effective. Such "equivalence" trials usually arise in comparing a new conservative treatment with an effective but more intensive standard therapy that has potential adverse side effects. Retrospective sample-size tables were provided to determine whether a completed study showing no significant difference between treatment effects is large enough to justify a true-negative conclusion. In this article, the sample sizes given in the decision-making tables are compared with those derived using a confidence-interval approach, the method we recommend for interpreting completed trials in order to judge the range of true treatment differences that is reasonably consistent with the observed data. Some implications of this comparison are discussed in respect to the interpretation of negative studies. Selected biostatistical principles involving the proper use of the tables are also presented. Finally, we distinguish between a completed negative study and an equivalence study, which is designed from the onset to demonstrate the comparability of different treatments. Important design considerations and sample-size tables are given for planning equivalence trials. We show that very large numbers of patients are usually needed to establish with a high degree of confidence that two treatments have comparable efficacy.

Clinical Trials as Topic↗
PubMed1985

Oxytocin antiserum delays onset of ovarian steroid-induced maternal behavior.

We have previously reported that intracerebroventricular (ICV) administration of oxytocin (OXY) produces a significant increase in maternal behavior in ovariectomized (OVXed) rats given a single priming dose of estrogen. Arginine vasopressin (AVP) has a weaker and more delayed but significant facilitating effect on the onset of maternal behavior. Other investigators have demonstrated that prolonged treatment of OVXed nulliparous rats with estrogen and progesterone followed by withdrawal of progesterone shortens the latency of onset of maternal behavior. We hypothesized that ovarian steroids increase the onset of maternal behavior by a central mechanism involving OXY and possibly AVP. To test this nulliparous Sprague Dawley rats were given SC one Silastic capsule containing 4.4 mg of 17 beta-estradiol eight days after OVX and three capsules each containing 40 mg of progesterone ten days after OVX. Progesterone capsules were removed on the 20th day after OVX, 24 hrs before the introduction of three rat pups (1-5 days old). One hr prior to introduction of pups animals received ICV 10 microliters of anti-oxytocin antiserum (AOA), anti-arginine vasopressin antiserum (AVA), anti-neurotensin antiserum (ANA), normal rabbit serum (NRS), AOA + 250 ng OXY or no ICV infusion. Animals receiving AOA displayed significantly less maternal behavior compared to animals receiving NRS, ANA or no ICV infusion over the first two, six and 25 hrs of pup contact. OXY significantly reversed the inhibitory effect of AOA in the first two hrs of pup contact. AVA significantly decreased the onset of maternal behavior compared to ANA or no ICV infusion over the first six hrs of pup contact.

Animals↗
PubMed1983

Technology at Washington University School of Medicine Library: BACS, PHILSOM, and OCTANET.

A brief overview of the Bibliographic Access and Control System developed by the Washington University School of Medicine Library is presented. Because the system has been described in two previous reports, this paper focuses on its relationship to other automated programs (i.e., PHILSOM and OCTANET), education of users, evaluation of the system, and outreach to the medical center. In operation for more than two years, BACS represents the computerization of much of the managerial and operational functions of the library, and marks the completion of stage 1 of the three stages of library evolution described in the AAMC report Academic Information in the Academic Health Sciences Center: Roles for the Library in Information Management.

Computers↗
PubMed1983

OCTANET--an electronic library network: I. Design and development.

The design and development of the OCTANET system for networking among medical libraries in the midcontinental region is described. This system's features and configuration may be attributed, at least in part, to normal evolution of technology in library networking, remote access to computers, and development of machine-readable data bases. Current functions and services of the system are outlined and implications for future developments in computer-based networking are discussed.

Interlibrary Loans↗
PubMed1978

The long-term effects of iridectomy for primary acute angle-closure glaucoma.

Forty-nine eyes were treated with iridectomy for primary acute angle-closure glaucoma. Forty asymptomatic, normotensive fellow eyes were similarly treated. The duration of follow-up after surgery was 52.3 +/- 3.6 months. Thirty-seven (76%) of the eyes with acute attacks were cured by iridectomy alone and required no medical therapy. Twelve eyes (24%) developed increased intraocular pressure following iridectomy, but only one eye (2%) required filtering surgery. Eighty-eight percent of the asymptomatic, normotensive fellow eyes required no subsequent therapy, and none developed visual field defects. Visual acuity was unchanged in 22 of 49 (45%) of the acutely involved eyes and decreased more than six lines in 11 (22%) eyes. In the 40 fellow eyes, visual acuity was unchanged in 63% and decreased more than six lines in only one (2%) eye.

Aged↗
PubMed1978

Plasma cortisol and elective cataract surgery.

Plasma cortisol was measured before and after elective cataract surgery in 19 patients given local anesthesia and in 11 patients given general anesthesia. In eight patients control plasma cortisols were measured at times corresponding to the surgical determinations. These eight patients demonstrated the circadian pattern of a fall in plasma cortisol. Only seven (37%) of 19 patients given local anesthesia failed to demonstrate the four-hour decrease in plasma cortisol (4-hr. p.o./8 A.M.0 greater than or equal to 0.80) following surgery, but this occurred in ten (91%) of 11 patients under general anesthesia (P less than .005). The 8:00 A.M. value was increased on the first postoperative day (8 A.M.1/8 A.M.0 greater than or equal to 1.37) in five (26%) of 19 patients given local anesthesia, but this occurred in 8 (73%) of 11 patients undergoing general anesthesia (P less than .025). The cortisol response to cataract surgery was significantly both more frequent and of greater magnitude in those patients undergoing general anesthesia.

Anesthesia, General↗
PubMed1977

Anterior segment ischemia after cyclocryotherapy.

The syndrome of anterior segment ischemia occurred in three patients as a complication of cyclocryotherapy for hemorrhagic glaucoma. Cryotherapy was applied with a retinal probe (2.5 mm in diameter) for 12 one-minute applications (-60 degrees or -80 degrees C) over the entire 360-degree circumference at the globe. The pathogenesis for this complication may be related, and unique, to chronic ocular ischemia associated with rubeosis iridis.

Adult↗
PubMed1976

Medical serials control systems by computer--a state of the art review.

A review of the problems encountered in serials control systems is followed by a description of some of the present-day attempts to solve these problems. Specific networks are described, notably PHILSOM (developed at Washington University School of Medicine Library), the UCLA Biomedical Library's system, and OCLC in Columbus, Ohio. Finally, the role of minicomputers in present and future developments is discussed, and some cautious guesses are made on future directions in the field.

Computers↗
PubMed1975

Pregnancy and the syndrome of herniated lumbar intervertebral disc; an epidemiological study.

In a study of the epidemiology of acute herniated lumbar intervertebral discs in the New Haven, Connecticut, area, it was found that the female cases had had more pregnancies resulting in live births than women of similar age without known herniated discs. However, cases had not had more pregnancies resulting in miscarriages than other women of their age. Among women who underwent surgery for their herniated discs, the association between number of live births and herniated discs was found for women with herniations at the L5 level but not for women with herniations at the L3 level.

Abortion, Spontaneous↗
PubMedDate not supplied

Interrelationships between physical activity and other health behaviors among university women and men.

BACKGROUND: The interrelationships among health behaviors are not well understood. The present study examines health behaviors and their relations to various types of physical activity among university seniors. METHODS: The study sample was an ethnically diverse group of 576 men and women (mean age 24.5 +/- 2 years) recruited from a large urban university. Physical activity was assessed with a modification of the Blair Seven-Day Recall by telephone interview, and health behaviors were assessed with the CDC's Youth Risk Behavior Survey, College Version. Hierarchical multiple regressions were conducted to determine whether health behaviors of men and women were associated with physical activity after adjusting for potential demographic confounders. RESULTS: Nineteen health behavior items were factor analyzed, yielding 5 factors: tobacco use, drinking and driving, unsafe sex, eating fatty foods, and eating healthy foods. Physical activity measures included leisure-time moderate and vigorous activities, flexibility, and strengthening activities. For men, a significant relation was found between three of four indices of physical activity and eating healthy foods (P < 0.05), but no association was noted with other health behaviors. For women, vigorous physical activity was related to eating healthy foods, and strengthening activities were related to eating fewer fatty foods (P < 0.05). CONCLUSIONS: Consistent with previous studies, physical activity was found to have modest associations with eating behaviors but not with other health-related behaviors.

Adolescent↗