Influence of muscle length and force on endurance and pressor responses to isometric exercise.

Experiments were performed to determine whether endurance time, mean arterial pressure, or heart rate was related to either muscle length or external torque production in humans during isometric knee extension. Eight men and nine women performed isometric knee extension to the endurance limit at each of three muscle lengths, determined by knee angles of 40 degrees (0.698 rad, shortest), 60 degrees (1.047 rad, intermediate), and 90 degrees (1.571 rad, longest), and at intensities of 30 and 50% maximal voluntary contraction (MVC). Knee extension forms an ascending-descending length-torque curve, and lengths were chosen to result in different external torques. MVC was greatest at a knee angle of 60 degrees (P < 0.05 vs. 40 degrees, 90 degrees), with no significant difference between 90 degrees and 40 degrees. Endurance time was inversely related to muscle length, independent of torque production, at 30% MVC [40 degrees, 395 +/- 139 (SE); 60 degrees, 237 +/- 60; 90 degrees, 165 +/- 51 s; P < 0.05 vs. each other] and 50% MVC (40 degrees, 176 +/- 64; 60 degrees, 137 +/- 40; 90 degrees, 85 +/- 23 s; P < 0.05 vs. each other). Evidence is presented that endurance is a function of internal muscle force and not resultant external torque. The experimental design allowed the relationship of external torque and cardiovascular responses to be examined independent of exercise intensity. Muscle mass was also controlled in that the same muscle group was involved in all contractions. There were no differences in mean arterial pressure, heart rate, or rating of perceived exertion at any percentage of endurance time under any condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone receptor messenger ribonucleic acid and protein are overexpressed in human uterine leiomyomas.

OBJECTIVE: Our purpose was to identify molecular mechanisms underlying abnormal growth of uterine leiomyomas. STUDY DESIGN: Biopsy samples of tumor and adjacent "normal" myometrium from nine patients were analyzed for progesterone receptor gene expression and for proliferation-associated antigen Ki-67. RESULTS: Northern analysis indicated that progesterone receptor messenger ribonucleic acid levels were increased twofold to 15-fold in leiomyoma compared with adjacent myometrial biopsy tissue from all patients (n = 9), whereas beta-actin messenger ribonucleic acid was at similar levels in these samples. Quantitative immunoassay, immunohistochemistry studies, and Western blot analyses revealed increased amounts of progesterone receptor protein in the tumor tissue. Both the progesterone receptor A and B forms were expressed in the leiomyoma and adjacent myometrium. Corresponding to increased progesterone receptor gene expression, the proliferation-associated antigen Ki-67 was also significantly elevated in the leiomyoma tissue. CONCLUSION: These data provide the first evidence that progesterone receptor messenger ribonucleic acid is overexpressed in uterine leiomyomas, suggesting that amplified progesterone-mediated signaling is instrumental in the abnormal growth of these tumors.

Oral trauma in children: a hospital survey.

The purpose of this investigation was to determine the type and prevalence of dental injuries seen in a hospital emergency room. Of the 10,436 patients who were treated at the hospital emergency room as a result of a traumatic episode, 765 (7.3%) had sustained injuries to structures of the oral cavity. The leading cause of dental injury was falls, accounting for 55.8% of the injuries. The male-to-female ratio of dental injuries was 1.6:1. The peak age group of children with dental injuries was the 1-to-2-year-old age group. Laceration of the lip was the most predominant injury to structures of the oral cavity, accounting for 62.8% of the dental injuries. The peak month for dental injuries was June, and 61.2% of the dental injuries occurred in the home.

Dentofacial trauma in children.

Most of the literature on dental injury pertains to the classification, incidence, prevalence, and treatment of fractured teeth. A major finding here is that the five leading causes of dentofacial injuries, regardless of severity, were falls, being struck by an object, bicycle accidents, assaults, and motor vehicle accidents.

Organizational characteristics of dental schools associated with research productivity.

The purpose of this study was to identify organizational characteristics of dental schools that relate to research productivity. Published data on 53 U.S. dental schools comprised the seven predictor variables. The criterion variable of school research productivity (SRP) was defined as the aggregate number of faculty publications generated by each dental school. Using stepwise multiple regression, it was found that three of the variables predicted 34 percent of the variance in SRP: (1) level of NIDR funding, R2 = .28; (2) student/faculty ratio, R2 = .31, and (3) number of library books, R2 = .337. An ANOVA was conducted between source of basic science instruction and SRP and revealed that the use of medical school faculty to teach basic science courses for dental students had the strongest positive relationship to SRP. The "ideal" combination of dental school characteristics associated with research productivity was $420,000 or more in NIDR funds, a student/faculty ratio of 4.75 or less, a dental library with at least 10,000 dental-related books, and the use of medical school faculty to teach basic science courses.

Relationship between faculty characteristics and research productivity.

The purpose of this research was to identify the characteristics of the active research producer within dental schools. A survey was mailed to 4,901 full-time faculty members in 53 U.S. dental schools, of which 1,481 (31 percent) were returned. Faculty Research Productivity (FRP) was defined as the number of publications generated by a faculty member during his or her academic career, as reported in response to a survey question. Seventeen characteristics of faculty members also were obtained from responses to survey items. Using stepwise multiple regression, five variables predicted 38 percent of the variance in FRP: Interest in Research, Earned Ph.D., Number of Journal Subscriptions, Consulting Time Per Week, and Research Time Per Week. While the relationship between FRP and student contact time was linear (the more articles produced the less student contact time), time spent in teaching per week did not enter the prediction equation.

The inquiry approach in dental hygiene education.

A study was done to assess the impact of an inquiry-oriented curriculum in a dental hygiene program. Two instruments, designed to measure student perception of personal and faculty inquiry and disinquiry behavior, were administered to four consecutive classes twice a year between 1978 and 1981. Junior and senior students perceived a significant increase in faculty inquiry behavior and, initially, a decrease in disinquiry behavior. Time in the program affected student disinquiry behavior at a significant level, though no significant change was seen in inquiry behavior. National Board mean scores improved, and several categories of clinical productivity increased significantly during this period. The implications of these findings are discussed.