Biomedical subjects

Michael Johnson

Publications and source records attributed to Michael Johnson.

28 records · Page 2Linked to original sources

PubMed2003

Nutrition and eating in female college athletes: a survey of coaches.

The purpose of the present study was to gather information from coaches regarding their monitoring/management of athlete eating and weight, knowledge of nutritional health issues, availability of prevention/intervention services for athletes at their school, experience with athletes exhibiting symptoms of eating and body image disturbances, and their attitudes toward eating and weight in the sport. A total of 303 coaches (51% response rate) involved in six sports (i.e., gymnastics, swimming, basketball, softball, track, and volleyball) at all levels of collegiate competition (NCAA Divisions I, II, III, and NAIA) completed a 40-item survey. Gender was found to be related to differential responding on only one of the 40 items, while sport and level of competition were related to responses on multiple items. Gymnastics coaches and NCAA Division I coaches differed significantly from coaches of other sports and divisions in that they reported more monitoring/management behaviors, had more experience with athletes exhibiting eating disturbances, and had more resources available for preventing and treating athletes with eating disorders. Gymnastics coaches also differed from other coaches on a number of items related to their attitudes toward eating and weight in the sport. Many coaches have encountered disturbed eating among their athletes, and some of their coaching attitudes and behaviors may inadvertently increase the risk for such disturbances. Implications for clinical and sport psychologists providing prevention or intervention services to intercollegiate athletes are discussed.

Journal Article↗

PubMed2002

Acute effects of aerosolized S-nitrosoglutathione in cystic fibrosis.

S-nitrosoglutathione (GSNO), a naturally occurring constituent of airway lining fluid, enhances ciliary motility, relaxes airway smooth muscle, inhibits airway epithelial amiloride-sensitive sodium transport, and prevents pathogen replication. Remarkably, airway levels of GSNO are low in patients with cystic fibrosis (CF). We hypothesized that replacement of airway GSNO would improve gas exchange in CF. In a double-blind, placebo controlled study, we administered 0.05 ml/kg of 10 mM GSNO or phosphate buffered saline by aerosol to patients with CF and followed oxygen saturation, spirometry, respiratory rate, blood pressure, heart rate, and expired nitric oxide (NO). Nine patients received GSNO and 11 placebo. GSNO inhalation was associated with a modest but sustained increase in oxygen saturation at all time points. Expired NO increased in the low ppb range with GSNO treatment, peaking at 5 minutes but remaining above baseline at 30 minutes. There were no adverse effects. We conclude that GSNO is well tolerated in patients with CF and improves oxygenation through a mechanism that may be independent of free NO. Further, GSNO breakdown increases expired NO. We suggest that therapy aimed at restoring endogenous GSNO levels in the CF airway may merit study.

Administration, Inhalation↗

PubMed2002

Diagnosis of histoplasmosis in urine cytology: reactive urothelial changes, a diagnostic pitfall. Case report and literature review of urinary tract infections.

Histoplasmosis not uncommonly causes systemic infection, particularly in immunocompromised patients. In systemic infection, the urinary tract is often involved, although the diagnosis of histoplasmosis in urine cytologic specimens has never been reported. Urinary tract histoplasmosis may present with gross hematuria, raising clinical suspicion for malignancy. The index case presented with intermittent gross hematuria, suprapubic pain, significant weight loss, hoarse voice, and a painful tongue ulcer. Examination of the patient revealed an ulcerated tongue lesion, an anal ulcer, a polypoid lesion on the vocal cord, and cystoscopic examination of the urinary bladder revealed erythematous patchy areas. Surgical biopsy sections from the vocal cord and tongue lesion were diagnostic of histoplasma infection. Urine cytologic examination showed atypical urothelial cells suspicious for malignancy. However, fungal stains performed on the urine specimen showed histoplasma organisms. We conclude that with a high index of suspicion, and the use of special stains, histoplasma organisms can be identified in urine.

Antifungal Agents↗

PubMed2002

A prospective study of the incidence, prevalence and mortality of multiple sclerosis in Leeds.

OBJECTIVE: To establish the prospective incidence of multiple sclerosis and mortality rates of people with multiple sclerosis in Leeds Health Authority and an updated prevalence of multiple sclerosis on 31 October 1999. METHODS: A population based prevalence register established on 30 April 1996 was maintained by prospectively registering all new cases of multiple sclerosis, flagging all cases with the National Health Service Central Register for notification of deaths and by registering all new clinical events. General practitioners notified patients with multiple sclerosis moving into or out of the area. RESULTS: 136 incident cases were prospectively registered from 30 April 1996 living in Leeds Health Authority (with an estimated resident population of 728,840). 57 deaths were notified. 792 people with multiple sclerosis were identified living in Leeds on 31 October 1999. The mean annual incidence rate for the three-year period 1996-1998 was 6.1/10(5) (95% CI: 5.1-7.2). The sex ratio of incident cases was 2.3 to 1 women to men. On 31 October 1999 the prevalence of multiple sclerosis in the Leeds Health Authority was 108.7/10(5) (95% CI: 101.2-116.5). This compares with a prevalence of 97.3/10(5) (95% CI: 90.3-104.7) on 30 April 1996. The prevalence of definite and probable multiple sclerosis was 93.3/10(5) (95% CI: 86.4-100.6) and of suspected multiple sclerosis was 15.4/10(5) (95% CI 12.7-18.5). Crude annual mortality rates of people with multiple sclerosis for 1997 and 1998 were 1.9/10(5) (95% CI: 1.1 to 3.2) and 3.2/10(5) (95% CI: 2.0 to 4.7). Multiple sclerosis was noted as the underlying cause of death in 8 (14%) cases. CONCLUSION: The incidence of multiple sclerosis in the Leeds Health Authority is similar to that in the south of the United Kingdom. The difference in successive prevalence figures is less than that published in other serial studies. Multiple sclerosis was notified as the underlying cause of death in a minority of deaths in people with multiple sclerosis.

Adult↗

PubMed2002

Lateral diffusion coefficients in membranes measured by resonance energy transfer and a new algorithm for diffusion in two dimensions.

We describe measurements of lateral diffusion in membranes using resonance energy transfer. The donor was a rhenium (Re) metal-ligand complex lipid, which displays a donor decay time near 3 micros. The long donor lifetime resulted in an ability to measure lateral diffusion coefficient below 10(-8) cm(2)/s. The donor decay data were analyzed using a new numerical algorithm for calculation of resonance energy transfer for donors and acceptors randomly distributed in two dimensions. An analytical solution to the diffusion equation in two dimensions is not known, so the equation was solved by the relaxation method in Laplace space. This algorithm allows the donor decay in the absence of energy transfer to be multiexponential. The simulations show that mutual lateral diffusion coefficients of the donor and acceptor on the order of 10(-8) cm(2)/s are readily recovered from the frequency-domain data with donor decay times on the microsecond timescale. Importantly, the lateral diffusion coefficients and acceptor concentrations can be recovered independently despite correlation between these parameters. This algorithm was tested and verified using the donor decays of a long lifetime rhenium lipid donor and a Texas red-lipid acceptor. Lateral diffusion coefficients ranged from 4.4 x 10(-9) cm(2)/s in 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) at 10 degrees C to 1.7 x 10(-7) cm(2)/s in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) at 35 degrees C. These results demonstrated the possibility of direct measurements of lateral diffusion coefficients using microsecond decay time luminophores.

Algorithms↗

PubMed2002

Lower extremity nontraumatic amputation among veterans with peripheral arterial disease: is race an independent factor?

OBJECTIVES: To determine if race/ethnicity is independently associated with an increased risk for nontraumatic lower extremity amputation versus lower extremity bypass revascularization among patients with peripheral arterial disease (PAD). METHODS: Data were analyzed from the National VA Surgical Quality Improvement Program (NSQIP) and from the Veterans Affairs Patient Treatment File (PTF). Race/ethnicity was defined as non-Hispanic white, black, or Hispanic. Variables that were univariately associated (P < or = 0.05) with the outcome of amputation were placed into a multiple logistic regression model to determine independent predictors for the dependent variable, lower extremity amputation versus lower extremity bypass revascularization. RESULTS: Three thousand eighty-five lower extremity amputations and 8409 lower extremity bypass operations were identified. Among all cases included, there were 416 Hispanic patients (3.6%), 2337 black patients (20.3%), and 8741 non-Hispanic white patients (76.1%). Among all variables within the model, Hispanic and black race were each associated with a greater risk for amputation than a history of rest pain/gangrene (Hispanic race 1.4, 95% CI 1.1, 1.9; black race 1.5, 95% CI 1.4, 1.7; rest pain/gangrene 1.1, 95% CI 1.0, 1.3). The final model had a c statistic of 0.83. CONCLUSION: Hispanic race and black race were independent risk factors for lower extremity amputation in patients with PAD. Although the burden of certain atherosclerotic risk factors (eg, diabetes and hypertension) is higher in minority patients, the impact of this burden does not account for the increased risk for the outcome of lower extremity amputation in these two populations. Further research is needed to better understand the reason(s) why race/ethnicity is independently associated with poor outcomes in PAD.

Activities of Daily Living↗

PubMed2002

Replication of avian sarcoma virus in vivo requires an interaction between the viral RNA and the TpsiC loop of the tRNA(Trp) primer.

Reverse transcription in avian sarcoma virus (ASV) initiates from the 3' end of a tRNA(Trp) primer, which anneals near the 5' end of the RNA genome. The region around the primer-binding site (PBS) forms an elaborate stem structure composed of the U5-inverted repeat (U5-IR) stem, the U5-leader stem, and the association of the tRNA primer with the PBS. There is evidence for an additional interaction between the viral U5 RNA and the T psi C loop of the tRNA(Trp) (U5-T psi C). We now demonstrate that this U5-T psi C interaction is necessary for efficient replication of ASV in culture. By randomizing specific biologically relevant regions of the viral RNA, thereby producing a library of mutant viruses, we are able to select, through multiple rounds of infection, those sequences imparting survival fitness to the virus. Randomizing the U5-T psi C interaction region of the viral RNA results in selection of largely wild-type sequences after five rounds of infection. Also recovered are mutant viruses that maintain their ability to base pair with the T psi C loop of the tRNA(Trp). To prove this interaction is specific to the tRNA primer, we constructed a second library, in which we altered the PBS to anneal to tRNA(Pro), while simultaneously randomizing the viral RNA U5-T psi C region. After five rounds of infection, the consensus sequence 5'-GPuPuCPy-3' emerged, which is complementary to the 5'-GGTTC-3' sequence found in the T psi C loop of tRNA(Pro). These observations confirm the importance of the U5-T psi C interaction in vivo.

Animals↗

PubMedDate not supplied

Application of real-time particle sensors to help mitigate exposures of wildland firefighters.

High particulate exposures have been demonstrated to decrease lung function among firefighters. In this article, the authors demonstrated the feasibility of using small real-time particle sensors to inform wildland firefighters so they may make informed decisions on the use of personal respiratory protection. Using 1 mg/m3 as an indicator point for use of appropriately designed respiratory protection, such sensors could help prevent 16% to 74% of particulate exposure during prescribed burns when firefighters assess exposure as low or medium. Adherence to such a guideline for the use of respiratory protection would involve its deployment during 3% to 22% of individual 8-hour shifts. In addition, data-logging sensors would provide a valuable tool for tracking exposure to particulates among wildland firefighters for occupational health monitoring.

Adult↗

PubMedDate not supplied

Phase I study of prolonged infusion Bryostatin-1 in patients with advanced malignancies.

PURPOSE: Bryostatin-1 is a compound known to inhibit protein kinase C expression. Clinical trials have focused on administration schedules ranging from 1 hour to 72 hour infusions. Preclinical data suggest that the down regulation of the target PKC occurs only as long as the drug is being infused. Therefore we performed a phase 1 clinical trial to determine the safety and recommended dose of prolonged infusion Bryostatin-1. EXPERIMENTAL DESIGN: Patients with advanced metastatic cancer were enrolled in this traditional phase 1 clinical trial utilizing prolonged infusion Bryostatin-1. The administration of Bryostatin-1 was initially begun at 96 hours and extended to 14 days. Doses were escalated using the 96 hour infusion time and then duration of infusion was increased. All patients underwent extensive sampling for determination of PKC levels as well as other key biologic end points. The determination of maximum tolerated dose and recommended phase two dose were based on toxicity. RESULTS: 38 patients were enrolled in the study. The recommended phase two doses were 24 mcg/m2 over five days, 16 mcg/m2 over six days and 8 mcg/m2 over 14 days. At the higher dose levels we demonstrated consistent down regulation of PKC-alpha. This was not observed at the low dose level. Toxicities were limited to myalgias and fatigue and were dose-related. The results of downstream signaling effects were less clear. MMP expression was not altered by treatment with Bryostatin-1. Only limited evidence for alterations in PKC activity as measured by expression of phosphorylated MAPK was observed. No objective responses were observed with five patients having prolonged stabilization of disease. CONCLUSIONS: Bryostatin-1 is safely administered over prolonged infusion schedules. There appears to be a dose response for PKC inhibition. Bryostatin-1 is a complicated compound as is the target PKC and its related signaling pathways. There is only limited clinical activity with this compound as a single agent; future studies should focus on combinations with other cytotoxics or targeted therapies.

Adult↗

PubMedDate not supplied

Temporal lobe, autism, and macrocephaly.

BACKGROUND AND PURPOSE: Because of increased prevalence of macrocephaly in autism, head size must be controlled for in studies that examine volumetric findings of the temporal lobe in autistic subjects. We prospectively examined temporal lobe structures in individuals with autism who were normocephalic or macrocephalic (head circumference > 97th percentile) and in control subjects who were normocephalic or macrocephalic or who had a reading disorder (unselected for head size). The rationale for the reading disorder group was to have control subjects with potential temporal lobe anomalies, but who were not autistic. METHODS: In individuals aged 7-31 years, autism was diagnosed on the basis of standardized interview and diagnostic criteria. Control subjects ranged in age from 7 to 22 years. All subjects were male. MR morphometrics of the major temporal lobe structures were based on ANALYZE segmentation routines, in which total brain volume and total intracranial volume (TICV) were calculated. Both group comparisons and developmental analyses were performed. RESULTS: No distinct temporal lobe abnormalities of volume were observed once head size (TICV) was controlled for. In autistic and control subjects, robust growth patterns were observed in white and gray matter that differed little between the groups. Although subtle differences were observed in some structures (ie, less white matter volume in the region of the temporal stem and overall temporal lobe), none was statistically significant. CONCLUSION: No major volumetric anomalies of the temporal lobe were found in cases of autism when IQ, TICV, and age were controlled. Temporal lobe abnormalities that may be associated with autism are likely to be more related to functional organization within the temporal lobe than to any gross volumetric difference.

Adolescent↗