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Biomedical subjects

J R Andrews

Publications and source records attributed to J R Andrews.

At least 19 recordsLinked to original sources
PubMed2000

Effects of throwing overweight and underweight baseballs on throwing velocity and accuracy.

The purpose of this review is to determine how throwing overweight and underweight baseballs affects baseball throwing velocity and accuracy. Two studies examined how a warm-up with overweight baseballs affected throwing velocity and accuracy of 5 oz regulation baseballs. One of these studies showed significant increases in throwing velocity and accuracy, while the other study found no significant differences. Three training studies (6 to 12 weeks in duration) using overweight baseballs were conducted to determine how they affected ball accuracy while throwing regulation baseballs. No significant differences were found in any study. From these data it is concluded that warming up or training with overweight baseballs does not improve ball accuracy. Seven overweight and 4 underweight training studies (6 to 12 weeks in duration) were conducted to determine how throwing velocity of regulation baseballs was affected due to training with these overweight and underweight baseballs. The overweight baseballs ranged in weight from 5.25 to 17 oz, while the underweight baseballs were between 4 and 4.75 oz. Data from these training studies strongly support the practice of training with overweight and underweight baseballs to increase throwing velocity of regulation baseballs. Since no injuries were reported throughout the training studies, throwing overweight and underweight baseballs may not be more stressful to the throwing arm compared to throwing regulation baseballs. However, since currently there are no injury data related to throwing overweight and underweight baseballs, this should be the focus of subsequent studies. In addition, research should be initiated to determine whether throwing kinematics and kinetics are different between throwing regulation baseballs and throwing overweight and underweight baseballs.

Animals↗
PubMed1999

Kinematic and kinetic comparison of baseball pitching among various levels of development.

Proper biomechanics help baseball pitchers minimize their risk of injury and maximize performance. However previous studies involved adult pitchers only. In this study, 23 youth, 33 high school, 115 college, and 60 professional baseball pitchers were analyzed. Sixteen kinematic (11 position and five velocity), eight kinetic, and six temporal parameters were calculated and compared among the four levels of competition. Only one of the 11 kinematic position parameters showed significant differences among the four levels, while all five velocity parameters showed significant differences. All eight kinetic parameters increased significantly with competition level. None of the six temporal parameters showed significant differences. Since 16 of the 17 position and temporal parameters showed no significant differences, this study supports the philosophy that a child should be taught 'proper' pitching mechanics for use throughout a career. Kinetic differences observed suggest greater injury risk at higher competition levels. Since adult pitchers did not demonstrate different position or temporal patterns than younger pitchers, increases in joint forces and torques were most likely due to increased strength and muscle mass in the higher level athlete. The greater shoulder and elbow angular velocities produced by high-level pitchers were most likely due to the greater torques they generated during the arm cocking and acceleration phases. The combination of more arm angular velocity and a longer arm resulted in greater linear ball velocity for the higher level pitcher. Thus, it appears that the natural progression for successful pitching is to learn proper mechanics as early as possible, and build strength as the body matures.

Adolescent↗
PubMed1999

Haycocknema perplexum n. g., n. sp. (Nematoda: Robertdollfusidae): an intramyofibre parasite in man.

Haycocknema perplexum n. g., n. sp. (Nematoda: Robertdollfusidae) is described from a man in Tasmania, Australia. Adult male and female nematodes and larvae were recovered from myofibres following biopsy of the right vastus lateralis muscle and were associated with a polymyositis. H. perplexum is distinguished from all other genera of the Muspiceoidea by the presence of a large amorphous "cell" supporting a granule-filled, flask- or gourd-shaped reservoir in the rectal region of mature and gravid female nematodes, often containing one or more large, refractile, thick-rimmed "globules" on the external surface of the reservoir, by the small number of ova/eggs/larvae developing in each uterus, by the minute, weakly-sclerotised, almost tubular spicule, by the presence of a pair of ampulla-shaped glands posteriorly and by the presence of lateral bacillary bands comprised of a single row of pore cells spaced irregularly and extending posteriorly to the region of the vulva in immature females.

Adult↗
PubMed1998

Polymyositis caused by a new genus of nematode.

We report two patients who presented with increasing malaise and myalgia, and had biopsy-proven polymyositis. Their conditions deteriorated after corticosteroid treatment, and repeat muscle biopsies showed adult and larval nematodes. Anthelminthic treatment was completely successful in both cases. The infecting nematode appears to belong to a new genus and is, to our knowledge, the first known muspiceoid nematode to infect humans. Its life cycle and the route of infection are unknown.

Adult↗
PubMed1998

Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises.

PURPOSE: Although closed (CKCE) and open (OKCE) kinetic chain exercises are used in athletic training and clinical environments, few studies have compared knee joint biomechanics while these exercises are performed dynamically. The purpose of this study was to quantify knee forces and muscle activity in CKCE (squat and leg press) and OKCE (knee extension). METHODS: Ten male subjects performed three repetitions of each exercise at their 12-repetition maximum. Kinematic, kinetic, and electromyographic data were calculated using video cameras (60 Hz), force transducers (960 Hz), and EMG (960 Hz). Mathematical muscle modeling and optimization techniques were employed to estimate internal muscle forces. RESULTS: Overall, the squat generated approximately twice as much hamstring activity as the leg press and knee extensions. Quadriceps muscle activity was greatest in CKCE when the knee was near full flexion and in OKCE when the knee was near full extension. OKCE produced more rectus femoris activity while CKCE produced more vasti muscle activity. Tibiofemoral compressive force was greatest in CKCE near full flexion and in OKCE near full extension. Peak tension in the posterior cruciate ligament was approximately twice as great in CKCE, and increased with knee flexion. Tension in the anterior cruciate ligament was present only in OKCE, and occurred near full extension. Patellofemoral compressive force was greatest in CKCE near full flexion and in the mid-range of the knee extending phase in OKCE. CONCLUSION: An understanding of these results can help in choosing appropriate exercises for rehabilitation and training.

Adult↗
PubMed1998

Avulsion fracture of the sublime tubercle of the ulna: a newly recognized injury in the throwing athlete.

OBJECTIVE: The purpose of this report is to describe the imaging features in three cases of avulsion injury of the sublime tubercle of the ulna that occurred in throwing athletes. CONCLUSION: Avulsion fracture of the sublime tubercle of the ulna is a potential cause of chronic medial elbow pain in the throwing athlete. This entity is best evaluated with a combination of plain radiographs and coronal MR images, particularly gradient-echo images that show the continuity of the avulsed fragment with the ulnar collateral ligament.

Adult↗
PubMed1998

Biomechanics of windmill softball pitching with implications about injury mechanisms at the shoulder and elbow.

Underhand pitching has received minimal attention in the sports medicine literature. This may be due to the perception that, compared with overhead pitching, the underhand motion creates less stress on the arm, which results in fewer injuries. The purpose of this study was to calculate kinematic and kinetic parameters for the pitching motion used in fast pitch softball. Eight female fast pitch softball pitchers were recorded with a four-camera system (200 Hz). The results indicated that high forces and torques were experienced at the shoulder and elbow during the delivery phase. Peak compressive forces at the elbow and shoulder equal to 70-98% of body weight were produced. Shoulder extension and abduction torques equal to 9-10% of body weight x height were calculated. Elbow flexion torque was exerted to control elbow extension and initiate elbow flexion. The demand on the biceps labrum complex to simultaneously resist glenohumeral distraction and produce elbow flexion makes this structure susceptible to overuse injury.

Adult↗
PubMed1997

Current concepts: the stabilizing structures of the glenohumeral joint.

Significant contemporary advances have permitted a more comprehensive understanding and development of some interesting concepts about the glenohumeral joint. The purpose of this review paper was to discuss current concepts related to the anatomic stabilizing structures of the shoulder joint complex and their clinical relevance to shoulder instability. The clinical syndrome of shoulder instability represents a wide spectrum of symptoms and signs which may produce various levels of dysfunction, from subtle subluxations to gross joint instability. The glenohumeral joint attains functional stability through a delicate and intricate interaction between the passive and active stabilizing structures. The passive constraints include the bony geometry, glenoid labrum, and the glenohumeral joint capsuloligamentous structures. Conversely, the active constraints, also referred to as the active mechanisms, include the shoulder complex musculature, the proprioceptive system, and the musculoligamentous relationship. The interaction of the active and passive mechanisms which provide passive and active glenohumeral joint stability will be thoroughly discussed in this paper.

Biomechanical Phenomena↗
PubMed1997

The physical examination of the glenohumeral joint: emphasis on the stabilizing structures.

Thorough descriptions of specific physical examination tests used to determine glenohumeral instability are lacking in the scientific literature. The purpose of this paper was to discuss the importance of the subjective history and illustrate the physical examination of the glenohumeral joint. Additionally, the authors will illustrate specific stability assessment for the glenohumeral joint based on current basic science and clinical research. The physical examination of a patient whose history suggests subtle glenohumeral joint instability may be extremely difficult for the clinician due to the normal amount of capsular laxity commonly present in most individuals. An essential component of the physical examination is a through and meticulous subjective history which includes the mechanisms of injury and/or dysfunction, chief complaint, level of disability, and aggravating movements. The physical examination must include an assessment of motion, static stability testing, muscle testing, and a neurologic assessment. A comprehensive understanding of various stability testing maneuvers is important for the clinician to appreciate. The evaluation techniques discussed in this paper should assist the clinician in determining the passive stability of the glenohumeral joint.

Humans↗
PubMed1996

Theory and practice in speech-language pathology: a review of systemic principles.

Linear, cause-effect reasoning has dominated the training and clinical practice of speech-language pathology for many years. Recently, however, the roles of many speech-language clinicians and the contexts in which they provide their clinical services have been changing, and traditional ways of viewing clinical work no longer seem to apply. This article applies principles of systems theory to such changes and advocates an integration of these principles with those of traditional, linear views to achieve a better understanding of this evolution in the clinical practice of speech-language pathology.

Child, Preschool↗
PubMed1996

Biomechanics of overhand throwing with implications for injuries.

Proper throwing mechanics may enable an athlete to achieve maximum performance with minimum chance of injury. While quantifiable differences do exist in proper mechanics for various sports, certain similarities are found in all overhand throws. One essential property is the utilisation of a kinetic chain to generate and transfer energy from the larger body parts to the smaller, more injury-prone upper extremity. This kinetic chain in throwing includes the following sequence of motions: stride, pelvis rotation, upper torso rotation, elbow extension, shoulder internal rotation and wrist flexion. As each joint rotates forward, the subsequent joint completes its rotation back into a cocked position, allowing the connecting segments and musculature to be stretched and eccentrically loaded. Most notable is the external rotation of the shoulder, which reaches a maximum value of approximately 180 degrees. This biomechanical measurement is a combination of true glenohumeral rotation, trunk hyperextension and scapulothoracic motion. Near the time of maximum shoulder external rotation (ERmax), shoulder and elbow musculature eccentrically contract to produce shoulder internal rotation torque and elbow varus torque. Both the shoulder and the elbow are susceptible to injury at this position. At ball release, significant energy and momentum have been transferred to the ball and throwing arm. After ball release, a kinetic chain is used to decelerate the rapidly moving arm with the entire body. Shoulder and elbow muscles produce large compressive forces to resist joint distraction. Both joints are susceptible to injury during arm deceleration.

Arm↗
PubMed1996

Genetic analysis of the lozenge gene complex in Drosophila melanogaster: adult visual system phenotypes.

Mutations at the lozenge (lz) locus are pleiotropic, primarily affecting the sense organs for sight, smell and taste. To better understand the role that lz plays in the visual system, we investigated its complex genetics and the effect mutations have on the structure of the compound eye. Complementation analysis within the lz locus reveals two functional units necessary for a normal eye, cistrons A and B. Previous recombination studies identified four subloci spanning 0.14 m.u. Cistron A mutations map to the distal-most spectacle sub-locus, which has been identified as an insertion point for P-elements. Southern blotting and chromosomal in situ hybridization show that P-allele lzmu2 contains a single P-element; a cosmid clone derived from lzmu2 confirms that the P-element is defective. Mutants of both cistrons perturb lens structure and eye pigmentation. However, the extent of the defects differs between the most severe mutations of the two cistrons. Within the eye, failure to form the fenestrated membrane permits photoreceptor neurons to "fall" into the brain disrupting neural structure. Our analysis shows that lz exerts control over the identity of cone cells, pigment cells and photoreceptor neurons.

Alleles↗
PubMed1995

Ulnar collateral ligament injury in the throwing athlete: evaluation with saline-enhanced MR arthrography.

PURPOSE: To determine whether magnetic resonance (MR) arthrography of the elbow can demonstrate precisely an ulnar collateral ligament (UCL) abnormality in the throwing athlete. MATERIALS AND METHODS: Forty college-level and professional throwing athletes (age range, 18-40 years) underwent saline-enhanced MR arthrography of their injured elbows. MR findings were compared with the surgical findings. RESULTS: Saline-enhanced MR arthrography was positive in 24 of 26 individuals with UCL tear confirmed at the time of surgery. Eighteen (95%) of 19 complete UCL tears and six (86%) of seven partial UCL tears were diagnosed with MR arthrography. Two false-negative findings and no false-positive findings were obtained. CONCLUSION: Saline-enhanced MR arthrography of the elbow is a new application of a previously described technique used in the shoulder. It is useful for demonstration of subtle and gross UCL abnormalities in the throwing athlete.

Adolescent↗
PubMed1995

Identification of Trichinella pseudospiralis from a human case using random amplified polymorphic DNA.

A human case of infection by Trichinella pseudospiralis has recently been described. Some morphologic anomalies of the muscle larvae, however, raise the possibility of an incorrect taxonomic attribution. A molecular taxonomic approach has therefore been applied for the identification of the parasite. Random amplified polymorphic DNAs were obtained from a single larva extracted from a muscle biopsy of the suspected case of T. pseudospiralis infection, and compared with those derived from 27 reference strains of Trichinella spp. Nearly identical amplification patterns were obtained from the suspected larva and from reference strains of T. pseudospiralis, thus supporting the original morphology-based identification. An enzyme-linked immunosorbent assay and Western blots carried out on pretreatment and post-treatment sera provided further confirmation.

Adult↗
PubMed1995

Arthroscopic anatomy of the elbow.

Elbow arthroscopy is becoming a mainstream orthopedic procedure. Through multiple portals, a thorough evaluation of the entire elbow joint is possible. However, an understanding of normal arthroscopic anatomy is essential for orientation and alienation of pathologic processes.

Arthroscopy↗