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Biomedical subjects

J R Morrow

Publications and source records attributed to J R Morrow.

At least 19 recordsLinked to original sources
PubMed1999

Oligonucleotide-europium complex conjugate designed to cleave the 5' cap structure of the ICAM-1 transcript potentiates antisense activity in cells.

The 5' cap structure of mRNA is a N7 methylated guanosine residue that is linked by a 5'-5' triphosphate linkage to the 5'-terminus of cellular and viral RNAs synthesized by RNA polymerase II. This unique structure facilitates several processes of mRNA metabolism, including splicing, nucleocytoplasmic transport,initiation of translation, and degradation. Previous research has demonstrated that the lanthanide macrocycle complex, Eu(THED)3+, effectively cleaves the 5' cap structure of mRNA in solution by nucleophilic attack of the triphosphate linkage via the metal-activated hydroxyethyl group of the THED ligand. This report shows that attachment of a Eu(THED)3+analog to the 3'-terminus of an antisense oligonucleotide, which targets the 5'-terminus of the intercellular adhesion molecule 1 mRNA, potentiates the inhibitory activity of the antisense oligonucleotide in cytokine-treatedendothelial cells.

Cells, Cultured↗
PubMed1999

The energy cost of horizontal walking and running in adolescents.

PURPOSE: This study developed and cross-validated generalized equations for predicting VO2 (mL x kg(-1) x min(-1)) and caloric expenditure (kcal x kg(-1) x min(-1)) during horizontal walking and running in adolescents. METHODS: Subjects were 47 male and 35 female adolescent volunteers, ages 12-18. Each subject underwent a submaximal treadmill exercise test to determine VO2 at randomly selected walking and jogging speeds (67-215 m x min(-1)). Caloric expenditure was estimated from VO2 and RER. Multiple regression was used to develop prediction equations for estimating VO2 and caloric expenditure from a derivation sample of 77 random observations, both walking and running. RESULTS: The group relationship between running speed and energy cost in the derivation sample was linear, whereas the relationship between walking speed and energy cost was quadratic. Gender, age, and height each failed to account for significant additional variation in energy cost after speed and mode were considered. Skinfolds accounted for a small yet significant amount of additional variation in energy cost. The derived equations were cross-validated on a sample of 76 separate random observations. The cross-validation statistics are: for VO2, R = 0.95, error = 3.58 mL x kg(-1) x min(-1), and for caloric expenditure, R = 0.94, error = 0.019 kcal x kg(-1) x min(-1). Most selected adult equations consistently underestimated both VO2 and caloric expenditure in the cross-validation sample. CONCLUSIONS: These results suggest that in adolescents, within the range of speeds tested, the relationship between speed of movement and energy cost for running is linear, but for walking is curvilinear. Also, adult models for estimating VO2 or caloric expenditure do not account for the higher relative energy cost of walking and running in adolescents.

Adolescent↗
PubMed1998

Reliability and concurrent validity of Futrex and bioelectrical impedance.

Thirty Caucasian males (aged 19-32yr) participated in this study designed to investigate the reliability of multiple bioelectrical impedance analysis (BIA) and near-infrared spectroscopy (Futrex, FTX) measurements and the validity of BIA and FTX estimations of hydrostatically (UW) determined percent body fat (%BF). Two BIA and two FTX instruments were used to make 6 measurements each of resistance (R) and optical density (OD) respectively over a 30 min period on two consecutive days. Repeated measures ANOVA indicated that FTX and BIA, using manufacturer's equations, significantly (p<0.01) under predicted UW by 2.4 and 3.8%BF respectively. Standard error of estimate (SEE) and total error (TE) terms provided by regression analysis for FTX (4.6 and 5.31%BF respectively) and BIA (5.65 and 6.95%BF, respectively) were high. Dependent t-tests revealed no significant differences in either FTX or BIA predictions of %BF using two machines. Intraclass reliabilities for BIA and FTX estimates of UW %BF across trials, days, and machines all exceeded 0.97. A significant random error term associated with FTX and a significant subject-by-day interaction associated with BIA was revealed using the generalizability model. Although FTX and BIA estimates of UW %BF were reliable, due to the significant underestimation of UW %BF and high SEE and TE, neither FTX nor BIA were considered valid estimates of hydrostatically determined %BF.

Adult↗
PubMed1998

Relations of sit-up and sit-and-reach tests to low back pain in adults.

The sit-up and sit-and-reach tests are found on nearly all youth and adult fitness tests because of the perceived relation between performance on these tests and low back pain. However, this relationship has not been well validated. Therefore, the purpose of the study was to examine the relationship between performance on these two common field tests of muscular strength and flexibility (the sit-up and the sit-and-reach tests) and self-reported low back pain (LBP). The sample included 2,747 adults with a mean age of 44.6 +/- 9.8 years. The 1-minute sit-up (mean = 30.9 +/- 10.6) and sit-and-reach tests (mean = 39.88 +/- 10.49 cm) were administered to participants as part of a voluntary clinical health and fitness evaluation between 1980 and 1990. Participants completed a mail-back survey in 1990 on musculoskeletal health problems. Low back pain was quantified by developing on ordinal variable from questionnaire responses which represented a range of severity of LBP from none (0) to LBP which required medical care (3). With an average of 6.1 (+/- 2.0) years of follow-up, LBP was reported by 54% of the study participants (men = 45%, women = 54%). Pearson correlations between sit-up (r = .002; p = .94), sit-and-reach (r = -.043; p = .03), and LBP indicated poor LBP criterion-related validity from the sit-up and sit-and-reach tests. Partial correlations, where age, gender, percent of body fat, and time between testing and survey response were controlled, displayed no increase in the relationship. This study does not support the validity of sit-up and sit-and-reach test items for health-related fitness batteries because they were unrelated to LBP.

Adult↗
PubMed1997

Resistance training in children and youth: a meta-analysis.

This research used meta-analysis to examine the effect of resistance training on children and youth. Studies investigating the effects of various forms of resistance training in participants of ages less than 18 years were analyzed. Effects sizes (ES) were calculated by gender, age group (boys ages > or = 16 years and girls ages > or = 14 years were defined as older), training (isokinetic, isometric, isotonic), and design type (pretest-posttest or experimental-control). Similar ESs were obtained for older and younger children; isotonic methods demonstrated larger ESs than isometric or isokinetic. Larger ESs were obtained in studies with cross-sectional (experimental-control) than pre-post designs. Resistance training appears to enhance muscular endurance and strength in children and youth. The magnitude of the effect appears to be a function of gender, training method, and experimental design.

Adolescent↗
PubMed1994

Artificial ribonucleases.

Many inorganic and organic compounds promote the reactions catalyzed by RNase A. Both the transesterification step, where a 2',3'-cyclic phosphate is formed with concomitant cleavage of RNA, and the hydrolysis step, where the 2',3'-cyclic phosphate is converted to a phosphate monoester, may be mimicked with compounds that are readily synthesized in the laboratory. Electrophilic activation of the phosphate ester and charge neutralization are generally important means by which artificial RNases promote phosphate diester displacement reactions. Several artificial RNases operate by a bifunctional general acid/general base mechanism, as does RNase A. Provision of an intramolecular nucleophile appears to be an important pathway for metal complex promoted phosphate diester hydrolysis. In contrast to the successful design of compounds that promote the reactions catalyzed by RNase A, there are no artificial nucleases to date that will cleave the 3' P-O bond of RNA or hydrolyze an oligonucleotide of DNA. Artificial RNases based on both metal complexes and organic compounds have been described. Metal complexes may be particularly effective catalysts for both transesterification and hydrolysis reactions of phosphate diesters. Under physiological conditions (37 degrees C and neutral pH), several metal complexes catalyze the transesterification of RNA. Future work should involve the development of metal complexes which are inert to metal ion release but which maintain open coordination sites for catalytic activity. The design of compounds containing multiple amine or imidazole groups that may demonstrate bifunctional catalysis is a promising route to new artificial RNases. Further design of these compounds and careful placement of catalytic groups may yield new RNase mimics that operate under physiological conditions. The attachment of artificial RNases to recognition agents such as oligodeoxynucleotides to create new sequence-specific endoribonucleases is an exciting field of endeavor. Applications for such sequence-specific endoribonucleases include in vitro manipulations of RNA and the destruction of gene transcripts in vivo. Further work will require the development of new synthetic methodologies for attachment of catalytic cleaving groups to oligodeoxynucleotides.

Base Sequence↗
PubMed1994

Caltrac versus calorimeter determination of 24-h energy expenditure in female children and adolescents.

The purpose of this study was to determine the validity of the Caltrac accelerometer for estimating 24-h energy expenditure (EE) in children and adolescents. EE for 40 girls (13.0 +/- 1.8 yr) was assessed for 24 h via indirect calorimetry in whole-room calorimeters. EE and activity level were estimated concurrently by two Caltrac accelerometers placed on the subjects at each hip. Significant correlations (P < 0.001) resulted between Caltrac estimates and calorimeter values for 24-h total EE (TEE, r = 0.80), sedentary daily EE (SDEE, r = 0.84), and waking EE (WEE, r = 0.85). Nonetheless, the Caltrac significantly (P < 0.001) underestimated EE in all experimental conditions (TEE: -13.3 +/- 8.6%; SDEE: -6.8 +/- 7.3%; WEE: -30.4 +/- 8.5%). A significant multiple correlation between calorimeter values and a combination of Caltrac activity counts and body weight (R = 0.86, P < 0.001) suggested these variables could be useful for daily EE estimation. Additional analyses indicated that as EE increased, the absolute difference between Caltrac and calorimeter values also increased. The significant correlations between Caltrac and calorimeter values suggest the Caltrac may be useful for assessing daily caloric expenditure for groups of children.

Acceleration↗
PubMed1993

Body composition of sedentary and physically active spinal cord injured individuals estimated from total body electrical conductivity.

Reliability and evidence of construct validity of Total Body Electrical Conductivity (TOBEC) for estimating body composition in spinal cord injured subjects was evaluated using 17 males with C6-L2 spinal cord transections. Subjects reporting regular exercise were categorized as active (n = 12); nonexercisers were considered sedentary (n = 5). Measures included body weight, length, circumferences, skinfolds, and three TOBEC readings. Reliability for percent fat of both single and multiple TOBEC trials (t = 3) ranged from .994 to .999. Average percent fat values were significantly (p < .009) higher in sedentary subjects. Sum of seven skinfolds was significantly correlated (r[15] = 0.73, p < .01) with percent fat measured by TOBEC. Results suggest TOBEC is reliable (rtt > 0.99) in estimating body composition in spinal cord injured individuals. High reliability estimates for single and multiple trials indicate use of a single trial will provide reliable body fat estimates. Construct validity evidence infers that TOBEC measured body composition discriminates between active and sedentary paraplegics.

Adult↗
PubMed1993

Validation of a 20-minute steady-state jog as an estimate of peak oxygen uptake in adolescents.

Distance run tests are often used to estimate peak oxygen uptake (peak VO2) in children. This study examined the concurrent validity of a 20-min steady-state jog (20MSSJ). The sample consisted of 43 boys and 32 girls who performed a 20MSSJ and completed a maximal treadmill test 1 week later. Peak VO2 was measured by indirect calorimetry. Subject characteristics were as follows: boys, mean age = 15.1 +/- 1.0 years, mean peak VO2 = 46.4 +/- 7.7 ml.kg-1 x min-1, mean 20MSSJ = 2.3 +/- 0.5 miles; girls, mean age = 15.3 +/- 1.1 years, mean peak VO2 = 40.4 +/- 5.1 ml.kg-1 x min-1, mean 20MSSJ = 2.1 +/- 0.5 miles. The correlation between 20MSSJ and peak VO2 was .68 across boys and girls. The regression slopes of the boys and girls were common, but the intercepts differed, F (1, 72) = 10.9, p < .05. The influence of weight and skinfold fat was examined. Separate models were developed, and the R for each was increased to .79 (SEE = 4.45 ml.kg-1 x min-1) for the model using weight and .80 (SEE = 4.36 ml.kg-1 x min-1) for the model using sum of skinfolds. The regression equations are as follows: peak VO2 = 35.10 + 6.19 (Run) + 2.96 (Gender) -0.26 (Skinfold fat) peak VO2 = 33.94 + 7.64 (Run) + 5.84 (Gender) -0.18 (Weight) (Run = 20MSSJ performance in miles; Gender; females = 0, males = 1; Skinfold fat = sum of two-site skinfolds in mm; Weight = body weight in kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Exercise and VO2 max in children: a meta-analysis.

Despite widespread belief that children are aerobically trainable, studies examining the ability of a child to improve maximal oxygen uptake (VO2max) have yielded inconsistent findings. The present investigation, using meta-analysis, examined the effects of physical activity, gender, experimental design, and sufficiency of exercise on the VO2 max of child subjects. Sixty-nine studies examining the effects of training on children were originally located; 28 met criteria for inclusion. From these studies, 70 effect sizes (ESs) were calculated. Some studies employed cross-sectional (XS) designs involving comparisons of intact groups of subjects; the others used a pretest-posttest (PP) design, which followed subjects throughout a specified training program. Average ES indicated a considerable difference between trained and untrained subjects though several possible sources of confounding (e.g., subject self-selection) in XS studies were identified. Effect sizes of .94 (+/- 1.00) and .35 (+/- 0.82) were achieved for XS and PP designs, respectively. Further analyses were conducted with the PP design studies. In these studies, subjects improved approximately 2 ml.kg 1 x min-1. In the PP studies, effect sizes were not significantly affected by (a) gender, (b) "sufficient" and "insufficient" training protocol, or (c) test mode. Results indicated that reported changes in VO2max in children are small to moderate and are a function of the experimental design used.

Adolescent↗
PubMed1992

Quality of life of hospitalized persons with AIDS.

This study explores quality of life from the viewpoint of Persons with AIDS (PWAs) who were interviewed during periods of hospitalization. Quality of life was viewed as the patients' perception of the relative effectiveness of a chosen or ascribed management style in solving the practical problems associated with being ill. Six management styles used by the respondents to improve their quality of life were identified. Results of this study suggest that nurses can improve PWAs' quality of life by supporting their respective management styles.

Acquired Immunodeficiency Syndrome↗