PubMed Health⌕ Search

Biomedical subjects

R Stine

Publications and source records attributed to R Stine.

9 recordsLinked to original sources
PubMed2003

Comparison of selection methods for optimizing genetic gain and gene diversity in a red pine ( Pinus resinosa Ait.) seedling seed orchard.

Four selection methods, individual selection (IS), family selection (FS), family plus within-family selection (FWFS) and combined selection (CS), were used to estimate genetic gain [ E( g)] for stem volume and gene diversity ( GD) for ten theoretical selection intensities in a 108-family, 12-year-old red pine seedling seed orchard. Estimated genetic gain for stem volume ranged from 4.6% to 11.8% across all selection methods and intensities with CS consistently having the highest gains and FS the lowest for any given selection intensity. Genetic diversity ranged from 0.9797 to 0.9954 across all selection methods and intensities. Individual selection was the best selection method for retaining GD, especially at the higher selection intensities, while FWFS was more efficient at the lowest selection intensity. An optimization point, which maximized E( g) and GD relative to each other, was calculated for each selection method. In all cases the optimization point indicated that both E( g) and GD would be favorably high when optimized relative to each other. The implications for volume gain, genetic diversity and potential inbreeding in red pine, a species with inherently low levels of genetic variation, are discussed.

Biological Evolution↗
PubMed1999

Shoulder proprioception: latent muscle reaction times.

PURPOSE: The purpose of this study was to identify electromyographic (EMG) differences in the latent muscle reaction timing (LMRT) of the rotator cuff between trained overhead throwers and control subjects in response to sudden internal rotation perturbation (P < or = 0.05). METHODS: Subjects included 15 trained overhead throwers (male intercollegiate baseball players) and 15 untrained subjects (males not active in competitive throwing sports). Subjects were tested while seated, with their dominant glenohumeral joint positioned in 90 degrees abduction/external rotation (scapular plane), their elbow flexed to 90 degrees, and their forearm placed in the perturbation device. Rotator cuff LMRT was assessed as they tried to decelerate a variably timed, sudden internal rotation force. EMG sampling (2000 Hz, 2-s duration) began immediately before perturbation. RESULTS: Trained throwers had slower infraspinatus (P = 0.011) and teres minor (P = 0.024) LMRT and decreased supraspinatus (P = 0.001) and posterior deltoid (P = 0.0001) muscle activation duration compared with control subjects. CONCLUSIONS: These results suggest that the rotator cuff muscles of trained throwers may be downregulated in response to sudden internal rotation perturbation. Although these adaptations would enable greater internal rotation velocities during overhead throwing, they may also contribute to glenohumeral joint pathology. The identification of changes in rotator cuff LMRT in response to sudden internal rotation perturbation suggests an area of acquired neuromuscular imbalance warranting consideration by those involved in the rehabilitation and conditioning of the overhead throwing athlete.

Adolescent↗
PubMed1998

Development and validation of a simple questionnaire to facilitate identification of women likely to have low bone density.

The relationship between low bone mass and risk of fracture is well documented. Although bone densitometry is the method of choice for detecting low bone mass, its use may be limited by the availability of equipment, cost, and reimbursement issues. Improved patient selection for bone densitometry might increase the cost-effectiveness of screening for osteoporosis, a goal we sought to achieve by developing and validating a questionnaire based solely on patient-derived data. Responses to the questionnaire were used to assign postmenopausal women to one of two groups: (1) those unlikely to have low bone mineral density (defined as 2 standard deviations or more below the mean bone mass at the femoral neck in young, healthy white women) and therefore probably not currently candidates for bone densitometry; and (2) those likely to have low bone mineral density and therefore probably candidates for bone densitometry. We asked community-dwelling perimenopausal and postmenopausal women attending one of 106 participating multispecialty centers (both academic and community based) to complete a self-administered questionnaire and undergo bone density measurement using dual x-ray absorptiometry. We used regression modeling to identify factors most predictive of low bone density at the femoral neck in the postmenopausal group. A simple additive scoring system was developed based on the regression model. Results were validated in a separate cohort of postmenopausal women. Data were collected from 1279 postmenopausal women in the development cohort. Using only six questions (age, weight, race, fracture history, rheumatoid arthritis history, and estrogen use), we achieved a target of 89% sensitivity and 50% specificity. The likelihood ratio was 1.78. Validation in a separate group of 207 postmenopausal women yielded 91% sensitivity and 40% specificity. Assuming population characteristics similar to those of our development cohort, use of our questionnaire could decrease the use of bone densitometry by approximately 30%. Sensitivity and specificity can be varied by changing the level for referral for densitometry to provide the most cost-effective use within a particular healthcare setting. Thus use of our questionnaire, an inexpensive prescreening tool, in conjunction with physician assessment can optimize the use of bone densitometry and may lead to substantial savings in many healthcare settings where large numbers of women require evaluation for low bone mass.

Bone Density↗
PubMed1990

Lachman test revisited.

The Lachman test has become recognized as the most reliable noninvasive clinical method for determining the integrity of the anterior cruciate ligament. The original description provided for the test being reported as either positive or negative. The purpose of this study is to present a clinical grading system for positive examinations. The criteria are as follows: Grade I, proprioceptive appreciation of a positive test; Grade II, visible anterior translation of the tibia; Grade III, passive subluxation of the tibia with the patient supine; Grade IV, ability of the patient with a cruciate-deficient knee to actively sublux the proximal tibia. Seventy-five patients with arthroscopically-documented complete anterior cruciate ligament tears were examined clinically and graded using these criteria. In addition, all patients had arthrometric examinations to measure the amount of anterior subluxation of the tibia in millimeters. A one-way analysis of variance followed by Scheffe multiple comparisons demonstrated the mean measurements of anterior displacement of the tibia in each laxity group to be significantly different.

Adolescent↗
PubMed1989

Natural history of the posterior cruciate ligament-deficient knee.

This paper documents the clinical course of the posterior cruciate ligament-deficient knee. By obtaining an understanding of the natural history of this lesion, the indications for surgical repair, reconstruction, and conservative treatment will be more clearly defined, and the clinician will be able to more critically evaluate the results of both acute repair and reconstruction of this ligament. Forty-three patients with an average interval of 6.3 years (range, one to 37 years) between injury and evaluation were included in this study. Fourteen patients had a straight unidirectional posterior instability and 29 had a combined multidirectional instability. The follow-up evaluation included functional assessment, physical and roentgenographic evaluation, arthrometric laxity measurement, and isokinetic dynametric testing of quadriceps function. Statistical treatment of the data, utilizing both nonparametric methods and logistic modeling, clearly delineated the natural history of the injury to the posterior cruciate ligament (PCL). It was established that the functional outcome can be predicted on the basis of the instability type. Specifically, those knees with PCL disruption without associated ligamentous laxity will probably remain symptom-free. However, when PCL disruption is associated with combined instabilities, a less than desirable functional result will probably occur. Application of logistic modeling to the data demonstrated that the functional result was not due to the type of instability per se, but rather to associated factors, i.e., chondromalacia of the patella, meniscal derangement, quadriceps atrophy, or degenerative changes. A direct correlation has been established between combined multidirectional instability and the occurrence of those associated secondary problems resulting in the patient's complaints and functional disability.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1988

Single photon absorptiometry imaging as a screening method for diminished dual photon density measures.

Scanning of the new 5-mm distal-radius site and the mid-radius (33% site) was performed using single photon absorptiometry (SPA) and of the L2-L4 region of the spine using dual photon absorptiometry (DPA) in a group of healthy women (age range 36-66 yr) in order to develop parameters to enable SPA to be used to screen for low DPA measures. The study data were analyzed as follows: 1. Women were classified as either 'intact' or 'post pelvic surgery' and the data for the two groups were separated. 2. Each SPA measurement was scrutinized and the one which produced the lowest score (% young normal [YN]) was entered for data analysis and graphing. The application of these two analytical discriminators represents a new approach in the biomedical literature. The findings were as follows: 1. When women were separated according to whether they were intact or had undergone pelvic surgery, the threshold value for screening using radius measures among intact women was set at 80% YN. 2. The necessary threshold value for the pelvic-surgery group needed to be set higher, at 93% YN. 3. If either the distal density or the mid-shaft density was below its threshold level, DPA was indicated. 4. At these threshold levels, no women with diminished spinal density (less than 83% YN) were omitted from screening procedure. We conclude that by refining our evaluation of each healthy woman according to her pelvic physiology status (intact or post-surgery) and considering whether either of the two SPA measures is below the threshold value, we will be able to screen for diminished DPA density and thereby eliminate a significant number of expensive but uninformative DPA readings.

Adult↗
PubMed1987

Lachman test evaluated. Quantification of a clinical observation.

The Lachman test has become recognized as the most reliable noninvasive clinical method for determining the integrity of the anterior cruciate ligament. The original description provided for the test is reported as either positive or negative. The purpose of this study is to present a clinical grading system for positive examinations. The criteria are as follows: Grade I, proprioceptive appreciation of a positive test; Grade II, visible anterior translation of the tibia; Grade III, passive subluxation of the tibia with the patient supine; and Grade IV, ability of the patient with a cruciate-deficient knee to actively sublux the proximal tibia. Seventy-five patients with arthroscopically documented complete anterior cruciate ligament tears were examined clinically and graded using the above criteria. In addition, all patients had arthrometric examinations to measure the amount of anterior subluxation of the tibia in millimeters. A one-way analysis of variance followed by Scheffe multiple comparisons demonstrated the mean measurements of anterior displacement of the tibia in each laxity group to be significantly different.

Adolescent↗