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At least 1,639 records · Page 91Linked to original sources
PubMed1999

Traumatic brain injury in high school athletes.

CONTEXT: The potential seriousness of mild traumatic brain injury (MTBI) is increasingly recognized; however, information on the frequency of MTBI among high school athletes is limited. OBJECTIVE: To identify the type, frequency, and severity of MTBI in selected high school sports activities. DESIGN: Observational cohort study. SETTING AND PARTICIPANTS: Two hundred forty-six certified athletic trainers recorded injury and exposure data for high school varsity athletes participating in boys' football, wrestling, baseball and field hockey, girls' volleyball and softball, boys' and girls' basketball, and boys' and girls' soccer at 235 US high schools during 1 or more of the 1995-1997 academic years. MAIN OUTCOME MEASURES: Rates of reported MTBI, defined as a head-injured player who was removed from participation and evaluated by an athletic trainer or physician prior to returning to participation. National incidence figures for MTBI also were estimated. RESULTS: Of 23566 reported injuries in the 10 sports during the 3-year study period, 1219 (5.5%) were MTBIs. Of the MTBIs, football accounted for 773 (63.4%) of cases; wrestling, 128 (10.5%); girls' soccer, 76 (6.2%); boys' soccer, 69 (5.7%); girls' basketball, 63 (5.2%); boys' basketball, 51 (4.2%); softball, 25 (2.1%); baseball, 15 (1.2%); field hockey, 13 (1.1%); and volleyball, 6 (0.5%). The injury rates per 100 player-seasons were 3.66 for football, 1.58 for wrestling, 1.14 for girls' soccer, 1.04 for girls' basketball, 0.92 for boys' soccer, 0.75 for boys' basketball, 0.46 for softball, 0.46 for field hockey, 0.23 for baseball, and 0.14 for volleyball. The median time lost from participation for all MTBIs was 3 days. There were 6 cases of subdural hematoma and intracranial injury reported in football. Based on these data, an estimated 62816 cases of MTBI occur annually among high school varsity athletes participating in these sports, with football accounting for about 63% of cases. CONCLUSIONS: Rates of MTBI vary among sports and none of the 10 popular high school sports we studied is without the occurrence of an MTBI. Continued involvement of high school sports sponsors, researchers, medical professionals, coaches, and sports participants is essential to help minimize the risk of MTBI.

Adolescent↗
PubMed2000

Statistical power comparisons among alternative morphometric methods.

This paper compares the statistical power of various tests that have been proposed to test for equality of shape in two populations. Power surfaces are computed with emphasis on the simplest case of three points in the plane (i.e., landmarks at the vertices of a triangle). Goodall's ([1991] J Roy Stat Soc Serb 53:285-339) F-test was found to have the highest power followed by T(2)-tests using Kendall tangent space coordinates. Power for T(2)-tests using Bookstein shape coordinates was good if the baseline was not the shortest side of the triangle. The Rao and Suryawanshi ([1996] Proc Natl Acad Sci 93:12132-12136 and Rao and Suryawanshi [1998] Proc Natl Acad Sci 95:4121-4125) shape variables had much lower power when triangles were not close to being equilateral. Power surfaces for the EDMA-I T statistic revealed very low power for many shape comparisons including those between very different shapes. Power surface for the EDMA-II Z statistic were also complicated and depended strongly on the choice of baseline used for size scaling. The type I error rate was also often not correct for this method. Results for more than three landmarks are also presented. The implications of the results for practical applications of morphometrics are discussed.

Anthropology, Physical↗
PubMed1996

Urinary infection and albumin excretion in insulin-dependent diabetes mellitus: implications for the measurement of microalbuminuria.

The frequency of urinary infection was determined using quantitative microbiology in 172 insulin-dependent diabetic patients repeatedly being tested for microalbuminuria over 18 months on at least six occasions. The point prevalence of urinary infection at first screening for microalbuminuria was 3%. Over the period of study, 20 of the patients (12%) showed evidence of urinary infection, defined as a pure growth of a recognized pathogen > 10(7)I-1. Infection was more common in women than men (20% vs 5%, p < 0.01) and was significantly associated with the presence of peripheral neuropathy (p < 0.05). Infection was not related to patient age, duration of diabetes, glycaemia, blood pressure, retinopathy or autonomic neuropathy. There were no significant within-patient differences in albumin excretion, glycaemic control or blood pressure in relation to the presence and absence of urinary infection. In only one patient (5%) did urinary infection significantly increase the urinary albumin excretion and this was associated with pyuria. We conclude that the presence of urinary infection does not apparently affect the measurement of urinary albumin excretion unless pyuria is present. Unless diabetic patients are symptomatic, examination of the urine for infection is probably unwarranted when testing for microalbuminuria.

Adult↗
PubMed1996

The negative association between traditional physical activities and the prevalence of glucose intolerance in Alaska Natives.

The once low prevalence of non-insulin-dependent (Type 2) diabetes (NIDDM) in Eskimos and Indians has risen approximately fourfold over the past 30 years, suggesting the presence of a non-genetic factor affecting NIDDM prevalence. At the same time, traditional physical activities required of a subsistence (self-sufficiency) lifestyle have diminished. Since physical activity has been shown to prevent NIDDM in other populations, we performed a case-control study of physical activity and glucose intolerance in 666 Yup'ik Eskimos and Athabaskan Indians > or = 40 years old in 15 villages in the Yukon Kuskokwim Delta in Alaska. Self-administered questionnaires were used to determine whether subjects participated in a number of traditional activities and/or their modern counterpart (for example, dog sledding and riding motorized vehicles). Intensity values and a score were defined for the activities. Cases included known or newly discovered impaired glucose tolerance or NIDDM. Newly discovered cases were defined by oral glucose tolerance testing of those individuals were screening blood glucose values > or = 6.7 mmol l-1 by random capillary blood glucose testing. Cases included 11 newly discovered (1 with a history of IGT) and 26 known cases of NIDDM, and 17 newly discovered and 1 known cases of IGT. The results showed that, compared to a reference group with low-level physical activity, moderate level physical activity (odds ratio, OR, 0.7, 95% confidence interval [CI] 0.4-1.3) and high level activity (OR 0.2, CI 0.1-0.6) were associated with a lower prevalence of glucose intolerance, adjusted for age, ethnicity, body mass index, and sex.

Age Distribution↗
PubMed1996

Testing for individual and population equivalence based on the proportion of similar responses.

This paper focuses on the classical problem of comparison of treatment effects. We show that we can base a simple and intuitive approach to comparison of two treatments on the proportion of similar responses. This approach is equivalent to the standard comparison of the treatment means in the normal case with equal known variances, but is quite different in other cases. Our approach applies under two different settings: testing a null hypothesis of no treatment difference against an alternative hypothesis of a difference, and testing the null hypothesis of at least a specific difference against an alternative hypothesis of equivalence. We develop our approach both for parallel groups (independent samples), and cross-over (paired samples) studies. The two situations give rise to the known concepts of population and individual equivalence. We present a graphical procedure to supplement the method.

Cross-Over Studies↗
PubMed1998

Exploratory thoughts on clinical trials with utilities.

We consider problems of choice of sample size and allocation in the clinical trials context when utilities are explicitly taken into account. In particular, we consider utilities of benefits and side-effects (and their trade-offs), as well as utility functions that trade-off scientific and ethical concerns.

Bayes Theorem↗
PubMed1998

Genotypic relative risks under ordered restriction.

In mapping diseases of complex aetiology, conventional linkage approaches narrow the location of the disease susceptibility locus to quite a large region so that candidate gene association studies are then necessary to further isolate these genes. However, even in the simplest scenario where the candidate locus is bi-allelic, two statistical tests with various correcting factors have been proposed: a chi-square 1 df test (counting chromosomes) which may be slightly conservative and a 2 df chi-square test (counting genotypes) which may lack power because of the extra degree of freedom. This paper introduces a better and more powerful alternative which turns out to be a compromise between the two existing statistical tests. The asymptotic distribution of this test statistic is determined and the efficacy of the 3 tests are compared under different genetic models by simulation.

Breast Neoplasms↗
PubMed2000

Synthesis of bivalent inhibitors of eucaryotic proteasomes.

Based on the peculiar spatial array of the active sites in the internal chamber of the multicatalytic proteasome, as derived from the X-ray structure of yeast proteasome, homo- and heterobivalent inhibitors were designed and synthesized to exploit the principle of multivalency for enhancing inhibition potency. Peptidic bis-aldehyde compounds of the octapeptide size were synthesized to address adjacent active sites, whilst a PEG spacer with a statistical length distribution of 19-25 monomers was used to link two identical or different tripeptide aldehydes as binding heads. These bis-aldehyde compounds were synthesized applying both methods in solution and solid phase peptide synthesis. Bivalent binding was observed only for the PEG-spaced inhibitors suggesting that binding from the primed side prevents hemiacetal formation with the active site threonine residue.

Chymases↗
PubMed2000

Familial tendency to foetal loss analysed with Bayesian graphical models by Gibbs sampling.

This paper presents several models for investigating whether the HLA allogenotypes DR1/Br, DR3 and DR10 are genetic markers for a predisposition of experiencing unexplained recurrent foetal losses. A total of 199 women from 113 families answered questionnaires concerning their pregnancies and 145 of these women were HLA typed. The analysis of the data is complicated as dependencies between pregnancy outcomes are expected. The main purpose of the paper is to illustrate how such analyses can be performed using Bayesian graphical models and Gibbs sampling. The analyses are made using the programs BUGS and CODA. Markov chain Monte Carlo analyses within a Bayesian framework have become easier with the introduction of these programs. However, experience shows that some caution is required so we recommend making some initial analyses using very simple models and perhaps approximative methods, followed by a model development introducing increasing complexity.

Abortion, Habitual↗
PubMed2000

National cancer database report on chondrosarcoma of the head and neck.

BACKGROUND: Management of chondrosarcoma of the head and neck is largely based on single-institution reports with small numbers accrued over several decades. METHODS: The American College of Surgeons' National Cancer Data Base included 400 cases of chondrosarcoma of the head and neck diagnosed between 1985 and 1995. Chi square analyses of selected contingency tables and Wilcoxon regression analyses of selected survival stratifications were performed. RESULTS: Histologic types included conventional (80.8%), myxoid (10.5%), and mesenchymal (8.8%). The mesenchymal and myxoid subtypes were rare among white patients (17.1%) and more common among African-American (31.8%) and Hispanic patients (44.9%). Treatment was most commonly surgery alone (59.5%) and surgery with irradiation (21.0%). Disease-specific survival was 87.2% at 5 years and 70.6% at 10 years. Worse 5-year survival was associated with higher grade (67.3%), regional or distant spread (71.0%), and the myxoid (45.0%) or mesenchymal (53.2%) subtypes. CONCLUSIONS: Chondrosarcoma of the head and neck encompasses a variety of lesions that differ substantially by demographic and tumor characteristics. Individual tumors can be classified further according to site of origin, histologic subtype, and tumor grade, which can be used to predict biologic behavior and prognosis.

Adult↗
PubMedDate not supplied

Growth status and obesity of Hopi children.

The purpose of this study was to examine the growth status and prevalence of underweight, overweight, and obesity in Hopi children. Subjects were 263 (117 males, 146 females) Hopi children 6-12 years of age. Stature and mass were measured and the body mass index (BMI) was calculated. Body size variables were plotted relative to age- and sex-specific reference data and the prevalence rates for underweight, overweight, and obesity were estimated using the BMI as the criterion. Age-specific sex differences were compared using independent samples t-tests. In both sexes, mean age-specific stature appeared to be relatively stable around the 50th percentile of reference values. Mean age-specific mass appeared to be relatively stable between the 50th and 90th percentiles of the reference values, while the mean BMI tended to fluctuate about the 85th percentile. Approximately 23% of Hopi children were classified as overweight and an additional 24% were classified as obese. Only two subjects were categorized as underweight. The results are consistent with other reports that childhood obesity is a serious public health concern among Native Americans. Further study is warranted to examine the causes of the high prevalence rates of pediatric obesity among Native Americans and the effectiveness of prevention and intervention programs.

Age Factors↗
PubMedDate not supplied

Oxygen saturation and heart rate in healthy school children and adolescents living at high altitude.

This study was conducted to establish reference values for percent oxygen saturation of hemoglobin (SaO2, %) and heart rate (HR, bpm) in children living at high altitude (4,100 m) and to relate possible differences in the variables with ethnic origin. Healthy children from a mine-located school (Tintaya, n = 417), a nearby school (Marquiri, n = 474), and a rural Andean community (Nuñoa, n = 373) were investigated. The samples included different ethnic combinations, with the Nuñoa children having a predominant Quechua ancestry. Mean SaO2 for all ages was substantially lower in all high altitude children compared to values considered normal for sea level. Among the three samples, SaO2 was higher (91.3 +/- 2.7) and HR was lower (84.8 +/- 13.6) in Nuñoa than in Tintaya (SaO2, 89.8 +/- 2.5; HR, 91.7 +/- 14.9) and Marquiri (SaO2, 89.6 +/- 3.1; HR, 88.5 +/- 12.9) (P < 0.05). There was no sex difference and only a weak age-dependent trend for SaO2. Values considered abnormal at sea level were observed in all healthy high-altitude children. Higher SaO2 and lower HR in Nuñoa children may suggest a better degree of acclimatization to altitude.

Acclimatization↗
PubMed2006

Methods of selecting informative variables.

We propose a new method for selection of the most informative variables from the set of variables which can be measured directly. The information is measured by metrics similar to those used in experimental design theory, such as determinant of the dispersion matrix of prediction or various functions of its eigenvalues. The basic model admits both population variability and observational errors, which allows us to introduce algorithms based on ideas of optimal experimental design. Moreover, we can take into account cost of measuring various variables which makes the approach more practical. It is shown that the selection of optimal subsets of variables is invariant to scale transformations unlike other methods of dimension reduction, such as principal components analysis or methods based on direct selection of variables, for instance principal variables and battery reduction. The performance of different approaches is compared using the clinical data.

Algorithms↗
PubMed2006

Confidence intervals for the mean of lognormal data with excess zeros.

In this paper, we consider an approach based on the adjusted signed log-likelihood ratio statistic for constructing a confidence interval for the mean of lognormal data with excess zeros. An extensive simulation study suggests that the proposed approach outperforms all the existing methods in terms of coverage probabilities and symmetry of upper and lower tail error probabilities. Finally, we analyzed two real-life datasets using the proposed approach.

Algorithms↗
PubMed1994

Redox-active bis-cysteinyl peptides. II. Comparative study on the sequence-dependent tendency for disulfide loop formation.

Bis(cysteinyl)octapeptides related to the active sites of the oxidoreductases protein disulfide isomerase (PDI), thioredoxin reductase (trr), glutaredoxin (grx), and thioredoxin (trx) were analyzed for their propensity to form the intramolecular 14-membered disulfide ring in oxidation experiments. The rank order of percentage of cyclic monomer formed in aqueous buffer (pH 7.0) at 10(-3) M concentration was found to be very similar, but opposite to that of the Kox and, correspondingly, of the redox potentials of the native enzymes. Attempts to induce intrinsic conformational preferences of the peptides by addition of trifluoroethanol led to enhancements of beta-turn structures as reflected by the CD and Fourier transform ir spectra. The induced secondary structure, instead of aligning the tendencies of the excised fragments for loop formation with those of the intact proteins, was found to suppress the differences by significantly increasing the preference for cyclic monomers (approximately 90%). Similarly, operating under denaturing conditions, i.e., in 6 M guanidinium hydrochloride, only for the trx peptide was the statistical product distribution obtained. For the remaining peptides, again a strong increase of cyclic monomer contents was observed that could not be correlated with dissolution of beta-sheet type aggregates. The CD spectra are more consistent with the presence of ordered structure to some extent, possibly resulting from an hydrophobic collapse of the sparingly soluble peptides. The results of the oxidation experiments further support previous findings from thiol disulfide interchange equilibria, which clearly revealed a decisive role of the characteristic thioredoxin structural motif in dictating the redox properties of the enzymes. Point mutations in the active sites of the oxidoreductases allowed us to affect their redox potentials strongly, but apparently only in the constraint form of the three-dimensional structure as similar exchanges in the excised fragments did not produce the expected effect. This observation contrasts with numerous reports that the conformation of short disulfide loops is mainly dictated by the amino acid sequence.

Amino Acid Sequence↗
PubMed2004

Brain metastases of malignant germ cell tumors in children and adolescents.

BACKGROUND: Brain metastases of pediatric germ cell tumors are uncommon, and there is limited information regarding their incidence, clinical presentation, response to treatment, and influence on survival. METHODS: The authors reviewed the experience with brain metastases from pediatric germ cell tumors at St. Jude Children's Research Hospital (Memphis, TN) over a 40-year period. RESULTS: Between March 1962 and February 2002, 16 of 206 patients with germ cell tumors (7.8%) had brain metastases at the time of initial presentation (n = 2), later in the course of the illness (n = 12), or at autopsy (n = 2). Twelve of 16 patients (75%) had symptoms referable to the brain (nausea/emesis, headaches, or seizures), and 14 (88%) had pulmonary metastases at the time brain metastases were identified. Patients with brain metastases were more likely to have an extragonadal primary tumor (P = 0.013), advanced-stage disease at initial presentation (P = 0.016), and choriocarcinoma within the primary tumor (P < 0.001). The incidence of brain metastases was significantly lower in the second 2 decades of the study period (5 of 135 patients [3.7%]) than in the first 2 decades (11 of 71 patients [15.5%]; P = 0.005). Two of the 16 patients in the current study are long-term survivors. CONCLUSIONS: Brain metastases are uncommon in childhood germ cell tumors, and their incidence appears to be decreasing. In the current study, most patients with such metastases were symptomatic and had pulmonary metastases at the time brain metastases were identified. Patients with the highest risk of developing brain metastases include those with extragonadal tumors, those with high disease stage at initial presentation, and those with choriocarcinoma as a component of the primary tumor. The probability of survival is poor, although a small proportion of patients may become long-term survivors.

Adolescent↗
PubMed2005

The correlation between fatigue, physical function, the systemic inflammatory response, and psychological distress in patients with advanced lung cancer.

BACKGROUND: Functional disability is reported frequently in fatigued cancer patients, but little is known about the correlation between fatigue and objective physical function. In addition, from previous work, the systemic inflammatory response and psychological distress appear to be related to fatigue. METHODS: Thirty-eight patients with metastatic or locally advanced lung carcinoma and 15 age-matched and gender-matched, healthy controls completed the Functional Assessment of Chronic Illness Therapy-Fatigue scale, a visual analogue weakness score, and the Hospital Anxiety and Depression (HAD) scale. Hemoglobin concentrations, C-reactive protein (CRP) concentrations, creatine kinase concentrations, white blood cell count, body composition, Karnofsky performance status (KPS), grip strength, and chair-rise time also were measured in both groups. The cancer patients were then grouped into tertiles on the basis of fatigue scores. RESULTS: The cancer patients had greater fatigue compared with the control group (P < 0.001). They also weighed less, had lower hemoglobin and creatine kinase levels and higher CRP levels, and had lower KPS, poorer grip strength, longer chair-rise times, and increased HAD scale scores (all P < 0.01). KPS and chair-rise time were correlated strongly (r(2) = 0.565; P < 0.001). With increasing fatigue, KPS was lower, and chair-rise time and HAD scale scores were greater (P < 0.01). On multiple regression analysis, only KPS, weakness, and HAD scale scores were correlated independently with fatigue (r(2) = 0.570; P < 0.001). CONCLUSIONS: Objective physical function (as measured by chair-rise time) in patients with advanced lung cancer was poorer with increasing fatigue. Results of the current study suggest that fatigue is not a result primarily of weight loss or anemia but is related to KPS and psychological distress.

Adult↗
PubMed2005

Extrapulmonary tuberculosis active infection misdiagnosed as cancer: Mycobacterium tuberculosis disease in patients at a Comprehensive Cancer Center (2001-2005).

BACKGROUND: Extrapulmonary tuberculosis is an uncommon disease in the U.S., even in immunosuppressed cancer patients. This study evaluated characteristics and frequency of extrapulmonary tuberculosis in patients at a tertiary care referral cancer center. METHODS: The records of all consecutive patients with Mycobacterium tuberculosis diagnosed during January 2001 through April 2005 at the M. D. Anderson Cancer Center were reviewed after obtaining institutional review board approval. RESULTS: There were 26 patients with active tuberculosis during the period studied; 18 of them were cancer patients and the others had been referred for a presumed cancer but did not have cancer. The overall rate of active tuberculosis during this period was 0.2 in 1000 new cancer diagnoses. There were 18 men (69%), the median age was 54 years (range, 3-84 yrs), and 16 patients (62%) were born in the U.S. Thirteen (72%) of the 18 cancer patients had solid-organ tumors; 3 of the 5 patients with a hematologic malignancy had non-Hodgkin lymphoma. Three patients (12%) had diabetes mellitus, and 2 patients (8%) had received high-dose (>1 mg/kg of prednisone daily) corticosteroids in the previous week. No patient had a recent history (within the past 4 wks) of chemotherapy; 4 patients had neutropenia. Cough was a prominent symptom (31%), followed by bone pain (19%), dyspnea (15%), and fever (12%). Fifteen patients (58%) had extrapulmonary infection, including 5 patients with concurrent pulmonary involvement; 7 noncancer patients (88%) and 8 cancer patients (44%, P = 0.22) had extrapulmonary disease. In 11 patients (42%), the lungs were the only site of active tuberculosis. Cavitary pneumonia was seen radiographically in 3 of 16 patients (19%) with pulmonary tuberculosis. All M. tuberculosis isolates were susceptible to isoniazid, rifampin, ethambutol, and pyrazinamide; streptomycin resistance was noted in 1 of 22 (5%) isolates tested. Twenty-two patients (85%) received appropriate antituberculosis treatment; all had a clinical and radiographic response. In 3 patients (12%) the cause of death was attributed to M. tuberculosis disease; 2 of 18 cancer patients (11%) died of progressive M. tuberculosis, and they had advanced solid-organ cancer, whereas 1 of 8 patients (13%) without cancer died and the tuberculosis diagnosis was made only on postmortem examination. Univariate analysis showed no significant differences in patients or disease characteristics between non-U.S.-born and U.S.-born patients, whereas noncancer patients (age 52 yrs) and those with extrapulmonary tuberculosis (age 53 yrs) were younger compared with cancer patients (63 yrs; P < 0.007) and those with pulmonary disease (age 60 yrs; P = 0.09). CONCLUSIONS: Extrapulmonary tuberculosis was relatively common in younger patients with active M. tuberculosis infection, and was often initially misdiagnosed as cancer.

Adolescent↗