Experimental perturbation of the development of sexual size dimorphism in the mouse skeleton.

BALB/c mice were raised for 30 days under nine treatment regimens to determine their effects on sexual dimorphism for size of the femur and of the body. Treatment groups were divided into three experiments: 1) burrowing in a high litter cage; eight times normal gravity for a total of one hour per day; a voluntary exercise control. 2) Unilateral femoral and sciatic nerve ablation; the opposite unoperated leg. 3) Swimming exercise; anabolic steroid; swimming and anabolic steroid; normal exercise control. Traits measured were body weight gain and thirteen femoral characters: moment at failure, length, cross-sectional area, anteroposterior and lateromedial diameters of the cross section, wall thickness for all four quadrants of the shaft, moments of inertia of the cross section in the anteroposterior and lateromedial directions, deflection of the shaft before failure, and total mineral content. Sexual dimorphism of the traits studied varied significantly with treatment. The greatest dimorphism was seen in the controls and the burrowing group. The least dimorphism was seen in the eight times gravity, the steroid, and the exercise and anabolic steroid groups. Reduction in the extent of sexual dimorphism was not correlated with a reduction in the loading regimen but rather seemed mediated by systemic changes in physiology brought on by several factors. Change in the amount of sexual dimorphism for size from the control reflects change in growth rates for males and females in response to different treatments. Change in growth rates of juvenile males and females will likely result in changes in the size of femoral characters and body weight in the adult. Change in the size of femoral characters affects the strength of the femur. In natural populations, a change in the body size of adult males and females could adversely affect reproductive success in groups that normally exhibit strong dimorphism, and hence, select against any conditions that reduce sexual dimorphism. Ordinarily, a significant change in sexual dimorphism--of the magnitude seen here--through natural selection, would take several generations.

Adaptive modeling in a mammalian skeletal model system.

Juvenile BALB/c mice were used as a model system to test the effects of various loading and exercise regimens on the growth and development of femora. Six treatments and three controls were used to document changes in geometric, mechanical, and material properties of the femora associated with strength. In each age-matched experiment, body weight and the strength, length, anterior and posterior diameters, cross-sectional area, moments of inertia in the anteroposterior and lateromedial directions, cortical wall thickness, and mineral content of the femora were assessed and found to vary significantly among treatment groups. An adaptive interpretation of these data was provided by calculating Pearson correlation coefficients between moment at failure (one measure of strength) and each geometric, mechanical and material property of the femora that contributes to strength. We make the assumption that at the termination of the experiment the greater the coordination between changes in strength and changes in the parameters that contribute to strength (the greater the number of correlations), the more adaptively modeled the femora are. Adaptive modeling here refers to the manner in which the femora grow and develop (adapt) under a given treatment regimen. Absolute strength of whole femora was reflected by our measure of adaptive modeling in all groups with one exception. In each experiment, the voluntary exercise controls were the most adaptively modeled. The least adaptively modeled groups also showed a general retardation of growth. It appears that juvenile mouse femora demonstrate a wide range of responses to different conditions of loading and exercise and that some of these changes are likely permanent. Moreover, at least two major variables--1) mechanical loading and 2) glucocorticoid mediated psychological stress--appear to contribute to the differences seen between the treatment groups.

Experimental changes in mineral content of juvenile mouse femora.

Juvenile laboratory mice were exposed to hypergravity (8 g), burrowing exercise, swimming to exhaustion, an anabolic steroid, and swimming and an anabolic steroid for 30 days to determine the variability of skeletal mineralization during growth. Changes in mineralization were correlated with changes in bending strength. Experimental mouse femora were loaded to failure in a cantilever beam configuration to determine bending strength, and ashed to determine total mineral content. Between experimental groups, mineral content ranged from 66.0 to 71.2% with the greatest change from the control being a 4.7% decrease in mineralization in the male swimming exercise group (P less than 0.001). Within two age-matched experiments, the first showed that the group with the greatest decrease in mineralization also had the greatest reduction in bending strength (P less than 0.001). The second age-matched experiment showed that the group with the greatest reduction in mineralization had bending strength greatly reduced (P less than 0.001). However, in this experiment, the weakest femora were in the anabolic steroid group that did not have the mineral content reduced. We conclude that (1) mineralization of juvenile mouse femora is extremely variable given varied conditions of exercise or loading; (2) mineralization of normal bone is decreased more often and to a greater extent than increased from normal exercise controls; (3) the decrease in mineralization seen here can decrease bending strength; and (4) the decrease in mineralization seen was not caused by a decrease in a mechanical loading but was probably due to a corticosterone-mediated psychological stress response.(ABSTRACT TRUNCATED AT 250 WORDS)

Technology update: computer-assisted video instruction in hospitals.

Interactive videodisks are state-of-the-art technology, and their potential is rapidly beginning to be recognized in the health care industry. A recent survey of 169 health institutions found that 79% planned the purchase of videodisks within the next year, and 72% planned to develop a videodisk program. As the role of the medical records practitioner increasingly includes acting as a hospitalwide information manager, CAVI provides the medical records professional a unique opportunity to both provide effective training within the department and hospital and be the leader in bringing the advantages of CAVI to the institution.

Evaluating software for the clinical laboratory.

A set of guidelines to assist in structuring the software-evaluation process is presented. In recent years, laboratory professionals have increasingly assumed responsibility for the evaluation of software to be used in the laboratory for patient testing or administrative functions. This is a positive trend that brings user expertise to the selection of computer software but one that mandates the development of appropriate software evaluation procedures on the part of laboratory personnel. Software should be chosen that best conforms to the needs of the laboratory. Proper evaluation of available software is critical. Documentation should be reviewed, the software should be tested, capabilities must be compared with accrediting or licensing bodies' standards, and vendor support should be assessed. Development of a well-defined procedure for software evaluation will ensure selection of software that solves, not creates, problems.

Structural alterations and breaking strength of mouse femora exposed to three activity regimens.

Mice were used as a model system to correlate loading, changes in cortical and trabecular bone growth and remodeling, and differences in breaking strength of the whole femur. BALB/c mice were raised for 30 days, starting at day 14, under three conditions of loading or exercise: (a) normal exercise control (NE), (b) 4 x normal gravity for a total of one h/day in addition to normal exercises (HG), and (c) chronic digging and burrowing (high-litter cage) (HL). Results indicate that both HG and HL groups significantly increased the cortical cross-sectional area of the mid-shaft of the femur, the moment of inertia in the antero-posterior direction at the mid-shaft, anterior wall thickness of the midshaft cross section, and changed the architecture of trabecular bone in the proximal one-third of the femur. The extent of these structural changes, however, was unique in each group. The HG group (high-intensity, short duration loading) demonstrated the greatest structural changes in the moment of inertia in the antero-posterior direction, which increased by 44% over the control (p less than .001), and in the architecture of trabecular bone. The HL group (lower-intensity, chronic exercise), demonstrated the greatest structural change in cortical bone cross-sectional area, which increased by 27% (p less than .0001). Despite the differences in loading and structural changes in the HG and HL groups, the breaking strength of the whole femur for both groups was approximately 64% greater than the controls (p less than .0001). A mechanical analysis of our data revealed that for our tests the contribution of bending to the total stress on the shaft may be over 50 times greater than that of either compression or tension. Further, the change in the geometry of the cortical bone may account for only approximately 50% of the increase in breaking strength; the remaining increase must be accounted for by changes in material properties and/or placement of trabeculae within the lumen of the shaft.

Guidelines for evaluating medical record software.

In recent years, many medical record professionals have assumed responsibility for the evaluation of microcomputer and mainframe medical record software. This article presents guidelines to help the medical record practitioner develop appropriate procedures for structuring the software evaluation process.

The microcomputer as a management tool.

Computer technology must be applied to the use of administrative time with the same fervor that has been attached to the computerization of the medical record functions. This article explains database management systems and spreadsheet software, exploring their application to several administrative functions appropriate for medical record managers and supervisors. The benefits of integrated software are also discussed.

Activity patterns within the genioglossus during suckling in domestic dogs and pigs: interspecific and intraspecific plasticity.

Suckling is universal among terrestrial mammals, but it is not clear whether mechanisms of suckling are the same in mammals of differing morphology or feeding ecology. An evaluation of the literature on tongue movements during suckling suggests that pigs and dogs may use the tongue differently, with humans being intermediate. Electromyographic (EMG) recordings of the middle and posterior portions of genioglossus of pigs and dogs were compared in order to (1) see whether neuromotor patterns for tongue movement during suckling can be recognized and (2) identify interspecific differences in neuromotor patterns if present. A single pattern of coordination was found in dogs, but results from pigs indicated plasticity, both within and between individuals. The literature on humans indicates that, as in pigs, suckling patterns may vary. In addition to the difference in variability, pigs and dogs differed in EMG burst duration and cycle length. The performance of suckling in pigs, dogs and humans, respectively, resembled the tongue movements used in drinking in each species. The greater plasticity of suckling behavior in pigs (and possibly humans) may be related to an ability to acquire milk under a variety of environmental conditions or to a generally variable feeding process characteristic of omnivorous mammals.

Computerization of a nosocomial infection system.

This paper describes the implementation of a computerized nosocomial infection control system for a 500-bed tertiary-care teaching hospital. It is implemented on a minicomputer that uses the relational data base management system INGRES, which is marketed by Relational Technology, Inc. This system, which replaces a manual one that depended on "needle sort" data cards, is designed to provide for entry of infection data that have been collected onto abstracting forms; decision support in the prospective analysis of suspicious infection rates or trends; generation of monthly, on-demand, and annual infection rate reports; retrospective interrogation and analysis of infection data for rates and trends that may explain or clearly indicate the sources of in-hospital (nosocomial) infections; updating of infection records as additional infection-related data become available and known to the hospital's infection control team; and ad hoc analysis and comparisons between data on control and infected patients, both prospectively and retrospectively.

Microfracture patterns of abrasive wear striations on teeth indicate directionality.

A method is described that will indicate the direction that an abrasive particle was traveling as it scored the surface of a brittle material. Light and scanning electron micrographs of glass, dentine, and enamel abraded by loose and, steel carbide, and diamond indicate that partial Hertzian fracture cones are formed at the margins of wear striations during abrasion. The bases of these fracture cones face in the direction of travel of the abrasive particle and, therefore, indicate directionality. Because this method is based only on the consistent geometry of fracturing of brittle materials, it is independent of the loading of the abrasive particle. The only other method available to determine directionality of striations is unreliable since it uses the width of striations, and, hence, is dependent upon a consistent loading regime of the abrasive particle. This new method has direct application for determining the direction of movement of the jaws during mastication in living or fossil animals.

Spirometric evaluation of acute bronchial asthma.

Spirograms were obtained before and after emergency therapy in 85 episodes of acute bronchial asthma in 82 patients. The clinical status of all patients after emergency treatment was reevaluated 48 hours later. Patients could be divided into three groups: I) admissions; II) patients discharged but with later respiratory problems; and III) patients who were discharged and did well. The mean pre- and posttreatment one second forced expiratory volume (FEV1.0) was significantly different among all three groups. FEV1.0 less than or equal to 0.6 liter before treatment, or an FEV1.0 less than or equal to 1.6 liter after emergency treatment, was associated with an unfavorable course. Eighty-eight percent of Group I patients (admissions) had either an initial FEV1.0 less than or equal to 0.6 liter, or a posttreatment FEV1.0 less than or equal to 1.6 liter. Among all patients whose initail FEV1.0 was less than or equal to 0.6 liter, 80% were either admitted or had subsequent respiratory problems; 75% of all patients whose posttreatment FEV1.0 was less than or equal to 1.6 liter were either admitted or developed subsequent respiratory problems. Moreover, 90% of patients who had both a pretreatment FEV1.0 less than or equal to 0.6 liter and a posttreatment FEV1.0 less than or equal to 1.6 liter were admitted or had subsequent significant airway obstruction. We conclude that spirometry can identify asthmatic patients who require admission or who will have significant airway obstruction within 48 hours after discharge from the emergency department.