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Biomedical subjects

W J Stone

Publications and source records attributed to W J Stone.

At least 19 recordsLinked to original sources
PubMed2002

Stages of exercise behavior and caloric expenditure.

BACKGROUND: This study assessed the ability of the stages of exercise behavior to differentiate caloric energy expenditure, by stage, based upon self-report of energy expenditure (EE). METHODS: Volunteer male and female participants (n=890) reported current stage of physical activity; physical activity mode, duration, and frequency; and demographic information (height and weight). Data calculated from reported information included EE, body mass index (BMI), and BMI category. EE profiles were established by average estimated EE (kcal/wk), average total time (min/wk) for physical activity, average activity frequency (times/wk), average session duration (min/session), moderate and vigorous EE levels (kcal/wk), and categorized activity level (sedentary, moderate, vigorous). RESULTS: There were no significant within gender differences across stages of exercise behavior for height. Terminators differed significantly for weight from all other groups, and BMI was significantly less across groups, by gender. All males were identified in the "Mildly Obese" BMI level, while only females in the non-active (precontemplation, contemplation, and preparation) groups were so identified. All other females were at the "Acceptable" BMI level. Regardless of gender, all groups were significantly different from the sedentary precontemplation and contemplation group for EE. Male and female preparation groups reported EE in the moderate level, and were significantly different from the action, maintenance, and termination groups, who reported EE in the vigorous level. Across subsequent stages of exercise behavior, female participants demonstrated increased EE. Male participants were similarly profiled, with the exception of one group (action stage), which was considerably greater than all other groups. CONCLUSIONS: This study confirmed the earlier examined premise, by Cardinal, that self-selected stage of exercise behavior differentiates EE by stage.

Adult↗
PubMed1997

Non-exercise VO2max estimation for physically active college students.

This study sought to develop a maximal oxygen consumption (VO2max) regression model derived strictly from self-reported non-exercise (N-EX) predictor variables. The VO2max (mean +/- SD; 44.05 +/- 6.6 ml.kg-1.min-1) of 100 physically active college students (50 females, 50 males), aged 18 to 29 yr, was measured using a treadmill protocol and open circuit calorimetry. Questionnaire-based predictor variables used in the N-EX regression model included (a) the subject's perceived functional ability (PFA) to walk, jog, or run given distances, (b) habitual physical activity (PA-R) data, (c) body mass index (BMI), and (d) gender. BMI (kg.m-2) was computed from self-reported body weight in pounds and self-reported body height in feet and inches. The questionnaire-based N-EX regression model (R = 0.85, SEE = 3.44 ml.kg-1.min-1) developed in this study exceeded the accuracy of previously developed N-EX regression models and is comparable to many exercise-based regression models in the literature. Cross-validation using PRESS (predicted residual sum of squares) statistics demonstrated minimal shrinkage (R = 0.84, SEE = 3.60 ml.kg-1.min-1) of the present regression model. The PFA data were useful in explaining observed VO2max variance (squared partial r2 = 0.155, P < 0.0001) and enhanced the ability of the N-EX regression model to accurately predict criterion VO2max. These results suggest that a questionnaire-based N-EX regression model provides a valid and convenient method for predicting VO2max in physically active college students.

Adolescent↗
PubMed1997

Cryofiltration apheresis and plasma fractionation causing anaphylactoid reactions in patients receiving angiotensin converting enzyme inhibitors.

Severe anaphylactoid reactions and even death have been reported in hemodialysis patients using certain membrane dialyzers while receiving angiotensin converting enzyme (ACE) inhibitors. We report mild to moderate anaphylactoid reactions in 4 patients receiving plasmapheresis with on-line membrane filters after being placed on ACE inhibitors. Of 21 patients receiving 497 plasma fractionation procedures, only the 2 patients who were receiving ACE inhibitors developed anaphylactoid reactions. Of 28 patients who had 680 cryofiltration procedures, only 2 of 5 patients who were taking ACE inhibitors developed anaphylactoid reactions. All patients developed facial flushing, increased warmth, bradycardia, and hypotension after approximately 1/2 to 1 L of plasma was processed during the procedures. Only a few procedures caused severe hypotension requiring discontinuation of the procedure. We quantified vasodilatory mediators in 1 patient, who developed pronounced symptoms. Results were obtained for 6-keto PGF1alpha, PGD-M, and methyl histamine in plasma. In addition, in the same patient, 2,3 dinor 6-keto PGF1alpha and methyl histamine were quantified in urine samples. Our results showed that plasma and urinary metabolites were not grossly elevated although they did increase slightly. Mild to moderate anaphylactoid reactions were observed in some patients on ACE inhibitors receiving plasma fractionation or cryofiltration apheresis. This was resolved by discontinuing either the ACE inhibitor, plasma fractionation, or cryofiltration apheresis.

Adult↗
PubMed1997

Options for renal replacement therapy: special considerations.

The number of patients coming to end-stage renal disease (ESRD) continues to increase annually, challenging the existing system of renal replacement therapy. Moreover, these patients, on average, are older at the onset of ESRD and are living longer after the initiation of renal replacement therapy. The choice of modality of renal replacement therapy (hemodialysis, peritoneal dialysis, or transplantation) that is best suited for a particular patient is thus increasingly important. Important factors to consider include not only mortality and morbidity, but also quality of life, patient age and social circumstances, and the etiology of ESRD. Three ESRD patient populations in particular, diabetic patients, the elderly and the patients with HIV infection or acquired immunodeficiency syndrome (AIDS), present renal care providers with complex issues as to renal replacement therapy and outcomes. Motivated patients with available resources, no matter what their cause of ESRD, should be considered as excellent candidates for home hemodialysis. This modality of renal replacement therapy is associated with improved survival and quality of life when compared with other modes of dialysis.

Humans↗
PubMed1994

Loss of neurofibromin in adrenal gland tumors from patients with neurofibromatosis type I.

The neurofibromatosis type I gene encodes a protein, neurofibromin, which may function as a tumor suppressor gene product. Recent studies have demonstrated loss of neurofibromin in tumors from NF1 and non-NF1 patients, including neurofibrosarcomas, neuroblastomas and malignant melanomas. Since neurofibromin is expressed in the adrenal gland, six pheochromocytomas and one adrenal cortical tumor were examined for neurofibromin expression. In all seven tumors, no neurofibromin could be detected. Furthermore, loss of heterozygosity (LOH) analysis demonstrated that in one of the pheochromocytomas, reduction to homozygosity was observed for both 17p and 17q markers while the adrenal cortical tumor demonstrated LOH for only 17q markers. The frequent LOH surrounding the NF1 locus and lack of neurofibromin expression in these tumors suggest that NF1 gene mutations may contribute to the development of adrenal gland neoplasms in patients with NF1.

Adrenal Gland Neoplasms↗
PubMed1993

Occurrence of pyuria and bacteriuria in asymptomatic hemodialysis patients.

Patients with end-stage renal disease on hemodialysis have documented defects in their immune responses, and infections contribute significantly to their morbidity and mortality. This study prospectively detected and quantitated leukocyturia and bacteriuria in asymptomatic hemodialysis patients. Thirty-one percent of asymptomatic hemodialysis patients had significant pyuria (> 10 white blood cells per high-power field) and 25% had bacteriuria of pathologic dimensions, (> 1 x 10(5)/mL of a single microorganism). Pyuria was a good marker for significant bacteriuria in these patients. These results demonstrate that the urinary tract, even in ESRD patients on hemodialysis, may represent a significant reservoir for infection.

Bacteriuria↗
PubMed1993

Year-round conditioning for basketball.

Year-round conditioning specifically designed for basketball has reached a high level of sophistication over the past several decades. There is growing evidence that it can contribute to improved performance and reduced injury. The major components of conditioning for basketball have been identified as anaerobic power (stages I and II), aerobic power, muscular strength/power/endurance, and flexibility. The concept of year-round conditioning uses the principles of periodization in work and rest to achieve peak performance and avoid injury. There are unique problems associated with the various levels of competition that require diligent monitoring on the part of the coach to maximize physical condition and avoid overtraining.

Basketball↗
PubMed1992

Employee physical activity: how does it compare to the nation?

1. Working adults exercise as much as the rest of society. 2. The amount of physical activity declines with age until 55, at which point increases were observed. 3. Marriage appears to have the largest effect on reducing the amount of physical activity a person gets. 4. Males are 1 1/2 times more likely than females to be vigorously active.

Adult↗
PubMed1991

Page kidney: case report and review of the literature.

Page kidney is caused by the accumulation of blood in the perinephric or subcapsular space, resulting in compression of the involved kidney, renal ischemia, and high renin hypertension. Most patients are young hypertensives with a remote history of blunt trauma to the abdomen or back. We describe a case of acute Page kidney following a renal biopsy in a patient with underlying IgA nephropathy. In addition to the new-onset hypertension, this patient developed a significant decline in renal function due to the inability of the contralateral diseased kidney to compensate. Magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound were valuable in making this diagnosis. Medical and surgical therapeutic options were considered. This report also reviews all previously described cases of Page kidney.

Adult↗
PubMed1990

Effects of dialysis membranes on beta 2-microglobulin production and cellular expression.

We investigated the effects of different dialysis membranes on the production of beta 2-microglobulin (beta 2m) in peripheral blood mononuclear cell cultures (PBMNC) obtained from hemodialysis patients in a prospective cross-over design study. Chronic dialysis with cuprophane membrane leads to an increase in beta 2m production from 129 +/- 11 ng/ml to 192 +/- 23 ng/ml (P less than 0.002). This increase is reversed by the use of a non-complement activating membrane polymethylmethacrylate. In addition, during chronic dialysis with cuprophane membrane, an increasing proportion of these cells display low beta 2m expression on their surface (from 6.1 +/- 0.8% of PBMNC to 16.9 +/- 3.4%, P less than 0.001), concomitant with the emergence of cells with low density of HLA on their surface (from 4.9 +/- 1.2% of cells to 32.9 +/- 7.8% of cells, P less than 0.001). The total content of cell-associated beta 2m is also decreased in dialysis patients in general, and in particular in patients chronically dialyzed with new cuprophane membrane. These effects can be reproduced by incubation of PBMNC with cuprophane membranes, and with the addition of C5a, IL-1 and TNF in vitro. Thus, chronic dialysis with cuprophane membrane may be a factor in the genesis of high beta 2m levels and causes changes in beta 2m and HLA expression on cell surfaces.

Aged↗
PubMed1990

Re-evaluation of the plasma renin-angiotensin system in anephric patients.

In view of recent observations that a number of extrarenal tissues have the potential to produce angiotensin II and release it in a regulated fashion, we made measurements of immunoreactive angiotensin I (irAng I) and angiotensin II (irAng II), along with active and inactive renin, and angiotensinogen in plasma of seven anephric patients and of 16 normal healthy volunteers to gain insight into possible sources of plasma Ang II. High performance liquid chromatography clearly demonstrated that the predominant component of irAng II in anephric plasma is the biologically active octapeptide Ang II. Plasma renin activity (PRA), and active and inactive renin all were detected in all of the anephrics but their levels were decreased to 33% for PRA, 12% for active renin, and 18% for inactive renin when compared with those in healthy subjects. While plasma angiotensinogen was significantly but only slightly increased in anephric patients (+28% over the mean value for normal subjects), irAng I and irAng II both were present in quantities almost comparable with those in normals. These results suggest that local angiotensin production contributes, in part at least, to the circulating plasma Ang II. Vascular tissue seems to be the best candidate responsible for such a mechanism, on the basis of recent demonstrations of unequivocal, regulated release of Ang II from diverse vascular beds.

Adult↗
PubMed1990

Strongyloides infections in transplant recipients.

Solid organ transplant recipients can experience serious disease and death from infection due to the parasitic roundworm Strongyloides stercoralis. This parasite lives in soil contaminated with human feces. Domestic dogs and cats may be another reservoir. Larvae can penetrate the skin, are carried hematogenously to the lungs, migrate up the bronchial tree, and then can be passed to the upper small intestine. Autoinfection occurs in the setting of immunosuppression when invasive larvae penetrate the gut wall and cause disseminated infection. Polymicrobial sepsis is sometimes seen due to enteric organisms adhering to the parasite. Transplant recipients are at highest risk during the first 3 months posttransplant. Many organ systems may be affected. Pulmonary symptoms include cough, wheezing, sputum production, dyspnea, hemoptysis, tachypneas, and pleuritic pain. Hyperinfection, an augmentation of the normal skin-lung-intestine life cycle, occurs in roughly two-thirds of infected transplant recipients, with dissemination in the remainder. Diagnosis is made primarily by examination of the stool or intestinal secretions for ova and parasites. Occasionally, parasites are noted in the sputum. New serologic tests show promise. The parasite may remain in the host for over 25 years before immunosuppression causes either dissemination or hyperinfection. Thiabendazole given for 3 to 7 days is the treatment of choice for organ transplant recipients. Repeat courses may be needed to eradicate infection.

Adult↗
PubMed1989

Treatment of the anemia of rheumatoid arthritis with recombinant human erythropoietin: clinical and in vitro studies.

Two anemic patients with rheumatoid arthritis were treated with recombinant human erythropoietin (EPO) for 5 months. Both patients showed significant increases in hematocrit, red cell volumes, and marrow erythroid and megakaryocyte progenitor cells. No significant toxic effects from EPO were observed. These data indicate that EPO may be effective in overcoming the pathogenetic factors that limit erythropoiesis in rheumatoid arthritis.

Adult↗
PubMed1989

Serendipitous diagnosis of appendicovesical fistula by bone scan: a case report.

A 71-year-old patient had recurrent urinary tract infections for 7 years after sigmoid colectomy via a Hartmann procedure. Extensive radiological and endoscopic tests were inconclusive as to the cause of bacteriuria. Chronic back pain led to performance of a radionuclide bone scan with the incidental demonstration of a vesicoenteric fistula, confirmed at exploration. Appendectomy with resection of the involved bladder resulted in cessation of bacteriuria.

Aged↗
PubMed1989

Cocaine-associated rhabdomyolysis and acute renal failure.

We have described four male patients, aged 21 to 39 years, who had rhabdomyolysis and acute renal failure during parenteral cocaine use. This complication has only recently been attributed to cocaine. Their illnesses behaved clinically like nonoliguric acute tubular necrosis, though renal biopsies were not done. No permanent nerve, muscle, or kidney damage resulted.

Acute Kidney Injury↗