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J R Thomas

Publications and source records attributed to J R Thomas.

At least 37 records · Page 2Linked to original sources
PubMed1999

A generalized rank-order method for nonparametric analysis of data from exercise science: a tutorial.

Frequent violations of the assumption that data are normally distributed occur in exercise science and other life and behavioral sciences. When this assumption is violated, parametric statistical analyses may be inappropriate for data analysis. We provide a rationale for using a generalized form of nonparametric analyses based on the Puri and Sen (1985) L treated as a chi 2 approximation. If data do not meet the assumption of normality, this nonparametric approach has substantial power and is easy to use. An advantage of this generalized technique is that ranked data may be used in standard parametric statistical programs widely available on desktop and mainframe computers, for example, regression, analysis of variance (ANOVA), multivariate analysis of variance (MANOVA) within BioMed, SAS, SPSS. Once the data are ranked and analyzed with these programs, the only adjustment required is to use a standard formula to calculate the nonparametric test statistic, L, instead of the parametric test statistic (e.g., F). Thus, rank-order nonparametric models become parallel with their parametric counterparts allowing the researcher to select between them based on characteristics of the data distribution. Examples of this approach are provided using data from exercise science for regression, ANOVA (including repeated measures) and MANOVA techniques from SPSSPC. Using these procedures, researchers can easily examine data distributions and make an appropriate decision about parametric or nonparametric analyses while continuing to use their regular statistical packages.

Analysis of Variance↗
PubMed1999

Regulation of intestinal tyrosine phosphorylation and programmed cell death by peroxovanadate.

Cell suspensions of ileal mucosa undergo a rapid and synchronized form of programmed cell death when cultured in a simple medium at 37 degrees C. Because tyrosine phosphorylation of proteins plays a crucial role in the signal transduction of many cellular processes, we examined its role in intestinal programmed cell death by use of immunoblot and immunohistochemical methods. We observed a 50-70% reduction in tyrosine phosphorylation during the initial 10 min of intestinal epithelial cell culture. We hypothesized that the inhibition of protein tyrosine phosphatases would increase protein tyrosine phosphorylation in these suspensions and decrease programmed cell death. A strong inhibitor of these phosphatases (peroxovanadate) but not a weaker one (sodium orthovanadate) abolished the DNA fragmentation/laddering normally seen in dying enterocytes. Peroxovanadate enhanced protein tyrosine phosphorylation of many intestinal proteins, dramatically increasing the dually phosphorylated and active form of mitogen-activated protein kinase. Immunohistochemistry revealed a particularly high level of increased tyrosine phosphorylation in the intestinal crypts in peroxovanadate-treated mucosa. Kinetic studies indicated that the pivotal time for protein tyrosine phosphatase inhibition occurred within 5 min of ex vivo culture, precisely when protein tyrosine phosphorylation declined. Our data suggest that tyrosine kinase inactivation or tyrosine phosphatase activation may initiate intestinal epithelial cell death.

Animals↗
PubMed1999

Placebo surgery.

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Ethics, Medical↗
PubMed1998

Evidence of an association between 6q13-21 chromosome aberrations and locally aggressive behavior in patients with cartilage tumors.

BACKGROUND: The finding of a cytogenetic-pathologic correlation between complex karyotypes and high grade cartilaginous tumors has been reported. However, few cytogenetic reports exist regarding benign or low grade lesions. A subset of low grade malignant cartilaginous tumors is characterized by locally aggressive behavior but no metastatic potential. Because the histopathologic distinction between benign, borderline, or low grade malignant cartilaginous lesions can be difficult, the finding of additional tumor markers associated with the clinical behavior of borderline cartilaginous lesions could be clinically significant. METHODS: Four cartilaginous tumors, including an osteochondroma (OC), a chondromyxoid fibroma (CF), an enchondroma (EC), and a dedifferentiated chondrosarcoma (DCS), were cultured and harvested using short term, in situ culture techniques. Chromosome analysis was performed by conventional G-banding and fluorescence in situ hybridization was used to confirm G-banding. RESULTS: The stemlines of all four tumors showed multiple chromosome anomalies that included aberrations of 6q13-21. The OC showed a t(6;16)(q21;p13.3). The CF showed a complex rearrangement between the chromosome 6 homologues, resulting in an inv(6)(p25q23)t(6;6)(q23;q13). This tumor also showed the clonal evolution of telomeric associations resulting in duplications, deletions, and the formation of a ring 15. The EC showed a der(6)t(6;15)(q13;q11)t(15;22)(q22;q13) stemline and subclones with an unstable iso 17q that subsequently fused to both ends of chromosome 16. The DCS showed a del(6)(q13), r(9), +12 stemline. CONCLUSIONS: The cytogenetic findings of this study suggest the cytogenetic-pathologic correlation of complex karyotypes found in high grade cartilage tumors may extend to lower grade tumors with complex karyotypes. These findings further suggest that chromosome aberrations in the region of 6q13-21 may be associated with locally aggressive behavior in patients with cartilage tumors.

Adolescent↗
PubMed1998

Comparison of subperiosteal vs subgaleal elevation techniques used in forehead lifts.

OBJECTIVES: To compare eyebrow and forehead elevation and tension among the following 3 surgical techniques: subperiosteal dissection to the supraorbital rim, subperiosteal dissection with release (elevation, incision, and spread) of periosteum at the supraorbital rim, and subgaleal dissection to the supraorbital rim, and to determine the optimal method of elevation in an aesthetically accepted range for the endoscopic forehead lift. DESIGN: A randomized, self-controlled study using an open approach to the forehead in cadaver heads. Each half of head was compared with the other in the following 2 study groups: subperiosteal dissection without release vs subperiosteal dissection with release of periosteum (group 1) and subperiosteal dissection with release of periosteum vs subgaleal dissection. SETTING: Anatomy laboratory at a university medical center. SUBJECTS: Eight cadaver heads fixed with ethylene glycol in each group. INTERVENTION: Predissection distances in millimeters from fixed anatomic landmarks were measured. The forehead flaps were elevated using a coronal incision and divided with a midline incision for side-to-side comparison. Cadaver heads and side of surgical intervention were selected randomly. The flap tensions associated with incremental flap advancement of 0.5 and 1.0 cm were measured. Traction of 2.2 kg was then applied to each flap, and distances between the fixed landmarks were measured. MAIN OUTCOME MEASURES: Mean predissection and postdissection distance of brow and forehead elevation for each dissection type and mean distance and median tension of brow and forehead elevation within each group. RESULTS: The mean postdissection brow measurements at rest were significantly greater than the mean predissection measurements at most landmarks in all dissections for both groups (P<.05). The mean postdissection brow and forehead measurements with 2.2 kg of traction were significantly greater than the mean predissection measurements at all landmarks in all dissections for both groups (P<.05). The mean increase in distance from predissection to postdissection (at rest and with 2.2 kg of traction) did not significantly differ between the different dissection types (P>.05). For group 1, the median flap tension for subperiosteal dissection without release was greater than that for subperiosteal dissection with release (P>.05). For group 2, subperiosteal dissection with release had greater median flap tension than subgaleal dissection (P>.05). CONCLUSIONS: All 3 methods of dissection significantly elevated the brow at rest for most landmarks. All 3 methods of dissection significantly elevated the brow and forehead when traction was applied to the flap. Brow and forehead elevation at rest and with 2.2 kg of traction did not significantly differ between the dissections. Subgaleal dissection was associated with less flap tension compared with the subperiosteal dissection with or without release. The data support the use of all 3 methods of forehead dissection for brow elevation and subgaleal forehead dissection as the optimal approach for the forehead lift, whether performed endoscopically or open.

Aged↗
PubMed1998

Structures of enzymically derived oligosaccharides from sorghum glucuronoarabinoxylan.

Oligosaccharides derived from alkali-extracted sorghum glucuronoarabinoxylan by digestion with a combination of (1-->4)-beta-D-arabinoxylan arabinofuranohydrolase (AXH) and endo-(1-->4)-beta-D-xylanase (Xyl I), both from Aspergillus awamori, were purified by size-exclusion chromatography followed by preparative high-performance anion-exchange chromatography. Structural studies including monosaccharide analysis, methylation analysis, 1H NMR spectroscopy, and mass spectrometry were carried out, resulting in the characterisation of four novel oligosaccharides, namely, alpha-D-GlcpA-(1-->2)-beta-D-Xyl p-(1-->4)-beta-D-Xyl p-(1-->4) -beta-D-Xyl p, alpha-D-GlcpA-(1-->2)-beta-D-Xyl p-(1-->4) [alpha-L-Araf-(1-->3)]-beta-D-Xyl p-(1-->4)-beta-D-Xyl p, alpha-D-GlcpA-(1-->2)-beta-D- Xyl p-(1-->4)-beta-D-Xyl p-(1-->4)[alpha-L-Araf-(1-->2)-alpha)-alpha- L-Araf-(1-->3)]-beta-D-Xyl p-(1-->4)-beta-D-Xyl p, and alpha-D-GlcpA-(1-->2) -beta-D-Xyl p-(1-->4)[alpha-L-Araf-(1-->3] beta-D-Xyl p-(1-->4)[alpha-L-Araf-(1-->2)-alpha-L-Araf-(1-->3)] -beta-D-Xyl p-(1-->4)-beta-D-Xyl p. The various oligosaccharides identified provide additional insight into the structure of sorghum glucuronoarabinoxylan. Furthermore, novel data were generated with respect to the substrate specificity of AXH and Xyl I towards glucuronoarabinoxylans in general.

Aspergillus↗
PubMed1998

Locomotion improves children's spatial search: a meta-analytic review.

This meta-analysis quantitatively summarized the developmental influence and the effects of locomotor experience as well as the benefits of locomotor practice, locomotor assistance, and active searching patterns on children's search performance. Based on specific criteria, a search of a database and reference lists identified 19 studies, including 1,029 children (510 boys and 519 girls) from 4 to 144 months of age. Outcome measures of spatial performance were converted to 83 effect sizes that reflected the effects of specific experimental characteristics. Analyses of variance indicated that with older children, locomotor activities are more important to their spatial searching. Locomotor status, searching patterns, locomotor assistance, test conditions, and test reliability were identified as moderator variables. In addition, locomotor training significantly improved children's spatial search. The results supported the hypothesis that children's development of spatial search skills is influenced by locomotor experience.

Age Factors↗