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Biomedical subjects

J Potts

Publications and source records attributed to J Potts.

At least 19 recordsLinked to original sources
PubMed1995

A modified internal rotation stretching technique for overhand and throwing athletes.

Strength, stretching, and rehabilitation methods for the shoulder have been previously described and have been universally applied; nevertheless, many throwing athletes continue to develop overuse injuries. The pitching process tends to increase external rotation and limit internal rotation of the shoulder joint. Our technique involves a modified stretching method of the posterior shoulder musculature. The athlete lies prone with the elbow flexed 90 degrees. With the shoulder abducted 90 degrees, in neutral flexion/extension, and 90 degrees or more of internal rotation, the scapula protrudes posteriorly. By depressing the inferior angle of the scapula toward the thoracic wall, the infraspinatus muscle and posterior joint capsule are effectively isolated and stretched. Manual stabilization of the scapula onto the chest wall transfers the internal rotation movements to the glenohumeral joint, as opposed to sharing the movement with the scapulothoracic articulation. This method improves the efficacy of the internal rotation stretching exercise for the glenohumeral joint. Such an addition to traditional stretching methods may increase the efficiency of the least effective component. We conclude that this modification to traditional programs should be an integral part of the training and rehabilitation program of any athlete requiring near maximal performance of the shoulder.

Athletic Injuries↗
PubMed1995

Subintimal hematoma of the aorta after deceleration injury.

Deceleration injuries of the aorta may occur without aortic disruption. We describe the case of a patient with a subintimal hematoma of the aorta that resolved within 48 hours. Serial arteriography confirmed the diagnosis and excluded aortic rupture. Thoracic exploration was not performed.

Adult↗
PubMed1994

Sex and ethnic group differences in fat distribution in young United Kingdom South Asians and Europids.

South Asians (Asians) have a high prevalence of non-insulin-dependent diabetes (NIDDM) and a high incidence of ischaemic heart disease (IHD). To investigate whether this predisposition can be detected in young adult life, metabolic risk factors for these diseases were compared in U.K. Europid and Asian students. Among the 80 Europid and 80 Asian students aged between 20 and 23 years and well matched for body mass index (BMI), Asians were found to be relatively hyperglycaemic [5.1 (5.0-5.2) vs 4.6 (95% CI: 4.5-4.7) mmol/l] and hypercholesterolaemic [5.3(5.2-5.4) vs 4.9 (4.8-5.0) mmol/l] and to have a higher waist/hip and subscapular/triceps ratio. The waist/hip ratio was found to be a better predictor of glucose and cholesterol than calliper measurements in both ethnic groups although the subscapular/triceps ratio was independently related to both glucose and cholesterol. Predictors of both IHD and NIDDM are present at an early age in U.K. Asians.

Adipose Tissue↗
PubMed1991

Full-length chicken parathyroid hormone. Biosynthesis in Escherichia coli and analysis of biologic activity.

Chicken parathyroid hormone (cPTH) has been reported to stimulate adrenal steroidogenesis and to have unusual potency on traditional PTH target tissues. To evaluate these properties, chicken PTH-(1-88) has been expressed in Escherichia coli using a plasmid encoding a fusion protein which links together growth hormone, a factor Xa recognition site, and chicken PTH-(1-88). The growth hormone-cPTH fusion protein required the presence of 0.02% sodium dodecyl sulfate to remain in solution and be cleaved by factor Xa. The high performance liquid chromatography-purified recombinant cPTH-(1-88) and chemically synthesized cPTH-(1-34) had similar potency in rat osteosarcoma (ROS 17/2.8) cells, opossum kidney (OK) cells, and dispersed primary chicken kidney cells. The biologic potencies of cPTH-(1-34) and cPTH-(1-88) in radioreceptor binding and cAMP generation in both bone- and kidney-derived cell lines were less than those of human (h)PTH-(1-34). In dispersed chicken kidney cells, cAMP production by cPTH-(1-34) and cPTH-(1-88) was similar to that stimulated by human PTH-(1-34). No stimulation of steroidogenesis could be detected when recombinant chicken PTH-(1-88) was added to dispersed chicken adrenal cells. The biologic activity of recombinant chicken PTH-(1-88) purified from E. coli was comparable with that of chicken PTH-(1-88) expressed by mammalian COS cells. Thus, the full-length chicken PTH did not exhibit enhanced potency, when compared with human PTH in ROS 17/2.8, OK cell lines, and dispersed chicken kidney cells and did not demonstrate the novel steroidogenic action previously reported in adrenal cells. The successful production of chicken PTH-(1-88) will enhance our understanding of the structure-activity relationships for PTH, particularly the sequence-dependent metabolism of the hormone.

Animals↗
PubMed1991

Beta-endorphin time course response to intensity of exercise: effect of training status.

The concentration of beta-endorphin (B-EP) was measured in 6 trained and 6 untrained cyclists during three intensities of exercise to determine the time course changes of B-EP. B-EP was determined by radioimmunoassay with less than 5% cross reactivity with beta-lipotrophin. A counter-balanced design was used to avoid an order effect from exercise intensity. Resting B-EP values were similar across visits. There were no differences in resting B-EP values comparing the trained (4.61 +/- 0.25 pmol.l-1) to the untrained (4.03 +/- 0.23 pmol.l-1) group. Cycling at 60% VO2max did not increase B-EP in either group at any time measured. Cycling at 70% VO2max increased B-EP by 10 min in both groups p less than 0.05. The rate and magnitude of increase of B-EP were similar for both groups. B-EP changes at 80% VO2max were significantly greater that at 70% VO2max and were identical for the two groups. Both groups demonstrated increases by 5 min and further increases at 30 min of exercise p less than 0.01. These changes occurred despite the fact that lactate levels were lower in the trained group at both 70 and 80% VO2max intensities. It is concluded that the time course change for B-EP is similar for trained and untrained individuals working at the same relative intensity of exercise and does not seem to be related to plasma lactate concentrations.

Adult↗
PubMed1991

Effects of strength training on lactate threshold and endurance performance.

To determine the effects of 12 wk of strength training on lactate threshold (LT) and endurance performance, 18 healthy untrained males between 25 and 34 yr of age were randomly assigned to either strength training (N = 10) or control (N = 8) groups. Despite no changes in treadmill VO2max or cycle peak VO2, a 33 +/- 5% increase (P less than 0.001) in cycling time to exhaustion at 75% of peak VO2 was observed following training. No significant changes in cycling time were observed in the control group. There were significant reductions in plasma lactate concentration at all relative exercise intensities ranging between 55 and 75% of peak VO2 training. The improved endurance performance was associated with a 12% increase in LT (r = 0.78, P less than 0.001). The strength training program resulted in significant improvements (P less than 0.001) of 31 +/- 5% and 35 +/- 7% in isokinetic peak torque values for leg extension and flexion, respectively, at a velocity of 30 degrees.s-1. There were also significant increases in 1-RM values of 30 +/- 4% (P less than 0.001) for leg extension, 52 +/- 6% (P less than 0.001) for leg flexion, and 20 +/- 4% (P less than 0.001) for the bench press. These findings indicate that strength training improves cycle endurance performance independently of changes in VO2max. This improved performance appears to be related to increases in LT and leg strength.

Adult↗
PubMed1990

Plasma beta-endorphin concentration: response to intensity and duration of exercise.

Twelve college-age men exercised on a bicycle ergometer to VO2max and at 60, 70, and 80% VO2max for 30 min to determine the effects of exercise intensity on plasma beta-endorphin (B-EP). The time course for alterations in B-EP and the relationship to lactate were also examined. Following the VO2max test, the three submaximal intensities were completed on separate days using a counter-balanced design. Blood was sampled from an indwelling venous catheter at rest during exercise and recovery to assess the time course response. B-EP content was determined by radioimmunoassay (Immunonuclear) with less than 5% cross-reactivity to B-LPH. At rest, B-EP content was similar across visits, 4.34 +/- 0.36 pmol.l-1. The 60% intensity did not elevate B-EP at any time measured. B-EP content increased by 15 min at 70% VO2max with a further increase at 30 min. B-EP remained elevated during the 20 min recovery. At 80% VO2max B-EP content increased by 5 min. B-EP continued to increase during the exercise and peaked at 21.91 +/- 2.03 pmol.l-1 5 min into the recovery. Lactate showed a mild correlation with B-EP (r = 0.43) at 80% VO2max. A significant correlation (r = 0.78) between lactate and B-EP did occur with the VO2max test. It is concluded that an exercise intensity of at least 70% VO2max for 15 min is needed to increase plasma B-EP. Furthermore, the higher the exercise intensity the more rapid the onset for increases in plasma B-EP.

Adult↗
PubMed1989

Gastrointestinal tuberculosis: resurgence of an old pathogen.

Thirteen patients with gastrointestinal tuberculosis (GITB) were treated at our hospitals from 1977-1987. Ten of these patients were seen during the last four years. Three patients required operative intervention for management of complications of their disease. This review discusses the presentation, diagnosis, and operative management of GITB. The authors feel that the increasing prevalence of GITB noted in their institution is primarily the result of the growing prevalence of mycobacterium tuberculosis pneumonia across the nation. With the recent influx of patients from areas of endemic tuberculosis and the increasing number of immunosuppressed patients, a surge in the number of patients presenting with GITB is likely to occur in the United States. Surgeons must be conversant with the diverse clinical features and operative management of this disease.

Cecal Diseases↗
PubMed1989

Effects of nearpoint visual stress on psycholinguistic processing in reading.

To date, there have been few studies to evaluate directly the relationship between binocular visual stress and reading performance. This study employed the cloze procedure to demonstrate the effects of nearpoint stress on performance and efficiency in reading comprehension. Using 19 third year optometry students as subjects, binocular stress was simulated by -2.00 D lenses. Performance, as determined by the time to complete the task, was significantly reduced (p less than .03), but no significant differences in accuracy scores were measured.

Adult↗
PubMed1988

Widespread occurrence of calicin, a basic cytoskeletal protein of sperm cells, in diverse mammalian species.

A novel cytoskeletal element consisting of dense webs of thin (3-14 nm) filaments surrounding the nucleus of the sperm head has recently been isolated and shown to be associated with certain major basic proteins. Using antibodies specific for calicin, a prominent Mr-60,000 cytoskeletal protein of the posterior calyx of bull sperm heads detected in immunoblotting on gel electrophoretically separated polypeptides as well as in immunofluorescence and immunoelectron microscopy, we show that the same--or an immunologically related--polypeptide occurs in sperm heads of other species with greatly different morphology, including human, boar, guinea pig, hamster, rat and mouse. The calicin localization in the various species is described and discussed in relation to the specific sperm morphology.

Animals↗
PubMed1984

Portal vein perfusion of the isolated rat liver: some markers of hyperthermic liver damage.

The cytotoxic effects of hyperthermia on tumours are readily measured. Parameters of injury to normal tissues are needed to evaluate therapeutic potential. Fifty-five isolated rat livers were perfused in vitro for 180 min in order to determine parameters of hyperthermic injury. During this period they were heated for 1 h at temperatures ranging from 37 degrees to 45 degrees and then assessed for evidence of hyperthermic injury. The most critical indicator of hyperthermic injury was sustained depression of bile production. Bile secretion decreased by 80% after heating at temperatures above 42 degrees. Aspartate amino transferase (AST) release increased significantly at temperatures of 42 degrees and above. Potassium and variable amounts of glucose were released into the medium during heating, reflecting temporary changes in metabolism at high temperatures.

Animals↗
PubMed1978

Elevated ejection fractions in patients with the anginal syndrome and normal coronary arteriograms.

The etiology of chest pain in patients with the anginal syndrome and normal coronary arteriograms has not been established. There has been no explanation for the association of electrocardiographic, hemodynamic, and myocardial metabolic abnormalities consistent with myocardial ischemia observed in some patients with this disorder. Historical, clinical, laboratory, and hemodynamic data of 45 patients (24 females, 21 males), mean age 47.5 years, with chest pain and normal coronary arteriograms are reviewed. Left ventriculograms were analyzed utilizing the single-plane cineangiographic measurement of left ventricular volume. Systolic ejection fractions for the 45 patients ranged from 0.66 to 0.91 (mean 0.80 +/- 0.01 SEM). Ventricular volumes determined angiographically revealed mean end-diastolic and end-systolic volumes of 83 +/- 5 ml and 18 +/- 2 ml, respectively. The mean changes in longitudinal and transverse segmental axis shortening that occurred during ventricular systole were 28.8% and 50.7%, respectively. These elevated values for ejection fraction, and reduced measurements of ventricular volumes, indicate that some patients with chest pain and normal coronary arteriograms may have small hearts with hyperdynamic ventricular contraction. These findings suggest that hyperdynamic ventricular contraction may play a causative role in the development of transient, angina-like chest pain in these patients. The etiology of the proposed hyperdynamic ventricle is unknown, but it may be attributable to increased beta-sympathetic stimulation of the myocardium.

Adult↗
PubMed1977

Phonocardiographic and echocardiographic features of Lillehei-Kaster mitral prosthesis.

Fifteen patients were studied with phonocardiography (phono) and echocardiography (echo) three to 13 months after mitral valve replacement with Lillehei-Kaster mitral valve prostheses. Echo measurements in all patients included prosthesis excursion (DE), opening velocity (OV), closing velocity (CV), and Q-to-mitral prosthesis closure (Q-MPC). In five patients, further, echo measurements included isometric contraction period (ICP), left ventricular ejection time (LVET), and time to completion of aortic valve opening (TCAO). Phono measurements in all patients included pre-ejection period (PEP), LVET, and PEP/LVET. Further phono measurements in the same five patients in whom further echo measurements were performed included Q to first heart sound (Q-S1), ICP, and isometric relaxation period (IRP). Phono and echo measurements were done sequentially. The echo results showed widespread values for DE, OV and CV with no correlation between clinical state, size of prosthesis, or postoperation duration. There was a positive correlation between CV and OV, r + 0.65. Q-MPC by echo averaged 72 msec, which is longer than reported values for Q-to-mitral valve closure in normal people. Similarly, ICP by echo was shorter than ICP by phono in every patient. Of the phono measurements IRP was shortest (45 msec) in one patient in congestive heart failure with a possible prosthesis malfunction. We conclude that echo- and phonocardiography are useful tools in evaluating mitral prosthesis function, but because normal values are widespread, individual measurements may be useful for followup in the same individual. Precise measurement of subdivisions of systolic intervals are now possible with these techniques.

Adult↗
PubMed1975

Fluid therapy in severe systemic reaction to radiopaque dye.

Two patients developed severe vascular collapse after left ventriculography with organic iodides. Hemodynamic monitoring showed marked reduction in systemic pressures. In one patient there was no response to the standard therapeutic measures in anaphylactic reactions, and prompt response to fluid administration was obtained. In the second patient response was prompt to fluids, adrenalin, and hydrocortisone.

Anaphylaxis↗