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Biomedical subjects

J Stratton

Publications and source records attributed to J Stratton.

17 recordsLinked to original sources
PubMed1999

Transthoracic contrast echocardiographic detection of ascending aortic dissection.

BACKGROUND: Ascending aortic dissection is highly lethal if left untreated. Therefore rapid accurate diagnosis is necessary. Diagnosis can be made with imaging modalities that use contrast agents to delineate anatomy reliably. Transthoracic echocardiography has not routinely been diagnostically useful because of the inability in clearly visualizing the ascending aorta. METHOD AND RESULTS: We describe a case in which transthoracic echocardiography with an echocardiographic contrast agent provided diagnostic information regarding an acute ascending aortic dissection, delineating both the true and false lumens. CONCLUSIONS: Transthoracic echocardiography combined with an echocardiographic contrast agent can be useful in detecting an ascending aortic dissection.

Aged↗
PubMed1998

High cell-density fermentation.

The purpose of this chapter is to educate the reader about the basic equipment and strategies used in fermentations of P. pastoris in both bench-top and pilot-scale operations. A key element in expression of foreign proteins in this yeast is the need for sufficient aeration, which is achieved by proper mixing of the media and by blending gases to control dissolved oxygen content. Automatic pH control is essential for growth and expression in P. pastoris. Finally, fed-batch fermentations require the use of peristaltic pumps and tubing capable of low rates of delivery for the feeding of nutrients and base. Teflon tubing and peristaltic pump adapters are recommended for fed-batch operations. The information in this chapter should enable a reader with little or no experience to perform a high-cell density fermentation of a P. pastoris expression strain. Although most procedures described here are specifically for the BioFlo III (NBS), it should be possible to achieve high expression levels with almost any good-quality fermentor, modified to accommodate this organism.

Alcohol Oxidoreductases↗
PubMed1997

Rectal prolapse associated with bulimia nervosa: report of seven cases.

PURPOSE: Rectal prolapse is a condition in which, when complete, the full thickness of the rectal wall protrudes through the anus. Bulimia nervosa is an eating disorder characterized by periodic food binges, which are followed by purging. Purging usually takes the form of self-induced vomiting, laxative abuse, and/or diuretic abuse. We report seven cases of rectal prolapse associated with bulimia nervosa. METHODS: The case histories of seven women with rectal prolapse and bulimia nervosa, average age 29 (range 21-42) years, seen over a period of 11 years (1987-1997) were reviewed. An analysis of the clinical data, including history, presenting physical examination, surgical treatment, and outcome was performed. RESULTS: All seven patients had a diagnosis of bulimia nervosa, made either before or with a diagnosis of rectal prolapse. Rectal prolapse was confirmed in each patient at anorectal examination. Five patients underwent sigmoid resection with proctopexy, one died before operative therapy, and one awaits further treatment. One of the five surgical patients had a recurrence that was managed by a perineal rectosigmoidectomy. CONCLUSION: To our knowledge, despite extensive review of both bulimia nervosa and rectal prolapse as seen in the medical literature, an association between the two has not been described previously. Several aspects of bulimia nervosa, including constipation, laxative use, overzealous exercise, and increased intra-abdominal pressure from forced vomiting are likely causes for the probable relationship with rectal prolapse. The possibility that an atypically young female presenting with rectal prolapse may also have bulimia nervosa should be taken into account by clinicians. This may assist the diagnosis of bulimia nervosa, a disease with multiple morbidities. Conversely, a patient being treated for bulimia nervosa who develops anorectal symptoms may come to earlier diagnosis and treatment for rectal prolapse.

Adolescent↗
PubMed1996

The influence of age on the assessment of motor unit activation in a human hand muscle.

Two indices of motor unit recruitment, the ramp-force and repetitive-discharge thresholds, were compared in the first dorsal interosseus muscle of ten young and twelve elderly subjects. The purpose was to determine the effect of age on the relationship between the two recruitment thresholds and the spike-triggered average force of motor units. Each subject performed three tasks requiring isometric abduction of the left index finger: a maximum voluntary contraction (MVC), a ramp-and-hold contraction, and a repetitive-discharge task. The elderly subjects used coactivation of the antagonist muscle (second palmar interosseus) more frequently than the young subjects during the ramp-and-hold contraction. Many elderly subjects expressed difficulty with the controlled ramp-down phase of the ramp-and-hold contraction and preferred a coactivation strategy to a derecruitment strategy for this task. There were no differences due to age or gender in the ramp-force thresholds between the various groups. However, the normalized repetitive-discharge threshold was significantly less for the younger subjects and for the male subjects. Nonetheless, the two recruitment thresholds were able to predict the spike-triggered average force with similar success for both the young and the elderly subjects. These data suggest that the recruitment threshold of a motor unit in first dorsal interosseus was characterized equally well by either the ramp-force or repetitive-discharge measurement for both young and elderly subjects but that coactivation was used more frequently by the elderly subjects during the ramp-and-hold task.

Adult↗
PubMed1993

Physical training improves skeletal muscle metabolism in patients with chronic heart failure.

OBJECTIVES: This study investigated the effects of physical training on skeletal muscle metabolism in patients with chronic heart failure. BACKGROUND: Skeletal muscle metabolic abnormalities in patients with chronic heart failure have been associated with exercise intolerance. Muscle deconditioning is a possible mechanism for the intrinsic skeletal muscle metabolic changes seen in chronic heart failure. METHODS: We used phosphorus-31 nuclear magnetic resonance spectroscopy to study muscle metabolism during exercise in 12 patients with stable ischemic chronic heart failure undergoing 8 weeks of home-based bicycle exercise training in a randomized crossover controlled trial. Changes in muscle pH and concentrations of phosphocreatine and adenosine diphosphate (ADP) were measured in phosphorus-31 spectra of calf muscle obtained at rest, throughout incremental work load plantar flexion until exhaustion and during recovery from exercise. Results were compared with those in 15 age-matched control subjects who performed a single study only. RESULTS: Before training, phosphocreatine depletion, muscle acidification and the increase in ADP during the 1st 4 min of plantar flexion exercise were all increased (p < 0.04) compared with values in control subjects. Training produced an increase (p < 0.002) in incremental plantar flexion exercise tolerance. After training, phosphocreatine depletion and the increase in ADP during exercise were reduced significantly (p < 0.003) at all matched submaximal work loads and at peak exercise, although there was no significant change in the response of muscle pH to exercise. After training, changes in ADP were not significantly different from those in control subjects, although phosphocreatine depletion was still greater (p < 0.05) in trained patients than in control subjects. The phosphocreatine recovery half-time was significantly (p < 0.05) shorter after training, although there was no significant change in the half-time of adenosine diphosphate recovery. In untrained subjects, the initial rate of phosphocreatine resynthesis after exercise (a measure of the rate of oxidative adenosine triphosphate [ATP] synthesis) and the inferred maximal rate of mitochondrial ATP synthesis were reduced compared with rates in control subjects (p < 0.003) and both were significantly increased (p < 0.05) by training, so that they were not significantly different from values in control subjects. CONCLUSIONS: The reduction in phosphocreatine depletion and in the increase in ADP during exercise, and the enhanced rate of phosphocreatine resynthesis in recovery (which is independent of muscle mass) indicate that a substantial correction of the impaired oxidative capacity of skeletal muscle in chronic heart failure can be achieved by exercise training.

Adenosine Diphosphate↗
PubMed1992

Bioquest Limited.

Explore the source record for details and available documents.

Antibodies, Monoclonal↗
PubMed1989

Mechanisms of response to treatment in autoimmune thrombocytopenic purpura.

To determine the mechanisms of an increase in the platelet count after therapy for autoimmune thrombocytopenic purpura, we determined the survival time and localization of radiolabeled autologous platelets and measured platelet-associated immunoglobulin levels before and after prednisone therapy or splenectomy in 19 patients with the disease. Eleven of 12 patients (92 percent) responded to prednisone with a mean threefold increase in the platelet count, resulting from increased platelet production (P less than 0.005); platelet survival was unchanged. Treatment with steroids failed in only one patient, whose pretreatment platelet production was already above normal. After splenectomy, 6 of 10 patients had a mean fourfold rise in the platelet count that correlated with increased platelet survival (P less than 0.005), together with improved platelet recovery (the percentage of platelets circulating in the blood immediately after the injection). Platelet production was unchanged. Base-line 111In-labeled platelet localization in the liver was normal in five patients in whom splenectomy was effective and increased to above normal in two of three in whom it was ineffective. Total platelet localization in the liver and spleen decreased by more than half after successful splenectomy (P less than 0.001), whereas it decreased by less than 25 percent after unsuccessful splenectomy. Platelet-associated immunoglobulin levels neither predicted nor correlated with treatment responses to prednisone or splenectomy. We conclude that prednisone improves platelet counts primarily by increasing platelet production, whereas the effect of splenectomy is to prolong platelet survival. Baseline measurements of platelet turnover and of platelet localization in the liver may be helpful in predicting the response to prednisone or splenectomy, respectively.

Adolescent↗
PubMed1984

Variations in circulating catecholamines fail to alter human platelet alpha-2-adrenergic receptor number or affinity for [3H]yohimbine or [3H]dihydroergocryptine.

A series of studies were performed to determine the relationship between physiologic levels of circulating plasma norepinephrine and epinephrine and human platelet alpha-2 binding site number and the affinity (KD) of these sites for antagonist radioligands. In one study, alpha-2-adrenergic binding site number and affinity were compared using both [3H]yohimbine and [3H]dihydroergocryptine as radioligands. There was good absolute and relative comparison for binding site number, but only a relative relationship for KD. In 46 normal subjects, there was no significant relationship between site number or KD and age, plasma epinephrine, or plasma norepinephrine concentration. Even after plasma epinephrine was raised nearly 20-fold by means of an intravenous infusion for 4 h in seven normal subjects, neither sites (608 +/- 68 vs. 567 +/- 120 sites/platelet) nor KD (2.01 +/- 0.94 vs. 2.14 +/- 1.15 nM) were significantly changed. Similarly, neither sites (445 +/- 55 vs. 421 +/- 53 sites/platelet) nor KD (1.44 +/- 0.29 vs. 2.10 +/- 0.75 nM) were significantly changed in six normal subjects when plasma norepinephrine levels increased during oral administration of prazosin for 1 wk. Thus, in a cross-sectional analysis and after a change in plasma catecholamine concentrations, there was no relationship in normal subjects between platelet alpha-2 binding site number or affinity of these sites for antagonist radioligands and the circulating catecholamine levels to which the platelets were exposed. In a group (n = 7) of patients who lack epinephrine-induced platelet aggregation due to abnormal thrombopoiesis, binding site number was decreased (304 +/- 36 vs. 572 +/- 29 sites/platelet, P less than 0.001) and KD tended to be greater (8.69 +/- 2.44 vs. 5.40 +/- 0.31 nM, P = NS) than in normal subjects (n = 46), despite having similar plasma catecholamine levels. There was no difference in binding site number (491 +/- 116 sites/platelet) and KD (5.61 +/- 0.84 nM) in patients (n = 5) with autonomic insufficiency and low levels of upright plasma norepinephrine when compared with the normal subjects. Two patients were examined before and after the removal of a pheochromocytoma. Their binding site number and KD were normal before the operation and essentially unchanged after the tumor removal and fall of plasma catecholamines. Thus, this study demonstrates that within the physiologic and pathophysiologic range of plasma catecholamines (in men), there is no relationship between the circulating catecholamine concentration and either platelet alpha-2 adrenergic binding site number or the affinity of these sites for antagonist radioligands.

Adult↗
PubMedDate not supplied

A new approach to substance abuse treatment. Adolescents and adults with ADHD.

Adolescents and young adults with Attention Deficit Hyperactivity Disorder (ADHD) are not only at risk for drug and alcohol dependence, but are also difficult to maintain in a chemical dependency facility due to disruptive behaviors. Such patients may be "hyperaroused," a term coined by the field of occupational therapy, but oppositional behaviors hide their physical and emotional overreactivity. Thirty years ago, occupational therapist Dr. Jean Ayres developed Sensory Integration (SI) techniques that are traditionally used with children under 12 years of age who are diagnosed with learning disabilities, autism, and ADHD. Many of the chemically dependent adolescent and young adult patients with ADHD who are in treatment display characteristics similar to those of children traditionally targeted for this therapy. Techniques used by occupational therapists trained in SI were adapted to treat hyperarousal and overreactivity to the environment in chemically dependent adolescents and young adults, in order to maintain them in the treatment environment until they were ready to graduate. The techniques were successful in maintaining and educating patients about ADHD and chemical dependency.

Adolescent↗
PubMedDate not supplied

Pesticide food poisoning from contaminated watermelons in California, 1985.

Aldicarb, a carbamate pesticide, is the most potent pesticide in the market and has a LD50 of 1 mg/kg. In the United States it is illegal to use aldicarb on certain crops, e.g., watermelons, because it is incorporated into the flesh of the fruit. Once an accidental or illegal use of such a potent pesticide occurs, there is no easy way for the agricultural or public health system to protect the populace. This paper describes the impact of one such event upon the health of individuals and the institutions of California. On July 4, 1985, California and other western states experienced the largest known outbreak of food-borne pesticide illness ever to occur in North America. This was attributed to watermelons contaminated through the illegal or accidental use of aldicarb by a few farmers in one part of the state. Within California, a total of 1,376 illnesses resulting from consumption of watermelons was reported to the California Department of Health Services (CDHS). Of the 1,376 illnesses, 77% were classified as being probable or possible carbamate illnesses. Many of the case reports involved multiple illnesses associated with the same melon among unrelated individuals. Seventeen individuals required hospitalization. There were 47 reports of illness involving pregnant women, two of whom reported having subsequent stillbirths. Thirty-five of the remaining pregnant women were followed-up 9 mo after the epidemic; no additional stillbirths were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Which formula should be used in Ireland to estimate fetal weight?

In order to determine which formula most accurately predicts weight in Irish infants we performed a prospective study on 162 mothers within one week of delivery. Actual weights were compared with estimated weights derived from the formulae of Shepard; Hadlock; Birnholtz; Deter and Campbell. Overall the Deter formula gave the closest approximation of birth weight. All the formulae became increasingly inaccurate in the larger infants i.e. > 4 kg. However in infants of average weight the Campbell formula, which is based on a single measurement (A.C), is as good as any.

Birth Weight↗