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Biomedical subjects

J Baranowski

Publications and source records attributed to J Baranowski.

At least 37 records · Page 2Linked to original sources
PubMed1998

Adverse effects of chronic low level lead exposure on kidney function--a risk group study in children.

BACKGROUND: Children have been considered a risk group for lead (Pb) toxicity, mainly because of neurophysiological or neuro-cognitive deficits following Pb exposure. Blood Pb levels (b-Pb) of 100 microg/l currently have been defined as the lowest adverse effect level. The aim of this study was to compare, with the help of urinary markers, the kidney function of children with b-Pb just above this threshold with that of unexposed children, to assess from a nephrological point of view whether the current threshold is justified and whether children really are a particularly vulnerable risk group in terms of Pb-induced kidney damage. METHODS: In a cross-sectional study, 112 children, either from unexposed areas (controls, n=50) or Pb-contaminated areas (n=62), the latter partly with a known history of elevated b-Pb, were examined. Twenty nine urinary or serum markers mostly related to the function or integrity of specific nephron segments were determined (e.g. filtered plasma proteins, tubular enzymes, tubular antigens, eicosanoids). RESULTS: b-Pb were 39+/-13 microg/l in controls and 133+/-62 microg/l in exposed children. The main findings were increased excretion rates of prostaglandins and thromboxane B2, epidermal growth factor, beta2-microglobulin and Clara cell protein in the exposed children. A relationship between b-Pb and the prevalence of values above the upper reference limits was observed. CONCLUSIONS: With the help of urinary markers, nephron segment-specific effects of chronic low-level Pb exposure could be detected in children. The pattern of effects on glomerular, proximal and distal tubular and interstitial markers was similar to that previously observed in adults. The changes, however, occur at lower b-Pb levels than in adults. The current threshold appears to be justified also from a nephrological point of view, and children can indeed be considered a special risk group.

Biomarkers↗
PubMed1998

Results of the TeachWell worksite wellness program.

OBJECTIVE: This study examined whether providing a school-based teacher wellness program enhances the impact of a health curriculum on student outcomes and improves cognitive, behavioral, and physiological outcomes among participating teachers. METHODS: Thirty-two elementary schools were randomly assigned to experimental or comparison conditions. Comparison group schools received the Gimme-5 program, a curriculum designed to increase fourth and fifty graders' consumption of fruits and vegetables. Experimental schools received Gimme-5 and the teacher wellness program, which included 54 workshops over 2 years, along with several schoolwide health activities. Physiological, behavioral, and cognitive outcomes were assessed in teachers and students. RESULTS: There was no evidence that the intervention favorably modified any student or teacher end points; nor did intervention teachers deliver the Gimme-5 program with greater fidelity than comparison teachers. CONCLUSION: Confidence in the null results is bolstered by the randomized design, baseline sample equivalence, appropriate mixed-model analyses, and lack of selective or differential attrition. Insufficient participation in the wellness program appears a likely explanation for the lack of teacher and student effects. Factors specific to the school setting and intervention may have diminished participation and, thus, intervention effects.

Adult↗
PubMed1998

[Comparative study of anatomical changes and function in kidneys after reconstructive surgery of the urinary tract using scintigraphic and other imaging examinations].

We performed a comparative evaluation of anatomical and functional changes in kidneys after urinary tract reconstructive procedures and in patients with history of urinary tract infections using renal scintigraphy and other imaging techniques. Statistically significant differences in the prevalence of pathological findings in imaging between these groups were shown. When children after the RVU are taken into account renal scintigraphy supplies us with objective and precise data about the renal scarring degree. In this group repeated renal scintigraphy should be warranted. After the reconstructive procedures due to hydronephrosis the images from ultrasonography and renal scintigraphy correlate well. Ultrasonography is a golden standard for screening these patients. Statistically significant higher degree of renal scarring in renal scintigraphy in patients after urinary tract infections without urinary tract defect proves the important role of infections in the pathogenesis of these changes. Children with recurrent symptomatic urinary tract infections should be submitted to renal scintigraphy imaging on regularly basis, as a risk group of higher chronic pyelonephritis prevalence.

Adolescent↗
PubMed1997

Social-cognitive predictors of fruit and vegetable intake in children.

Social-cognitive theory (SCT) was used to explain the fruit and vegetable intake of 1,398 3rd graders. SCT variables assessed included self-efficacy, outcome expectations, preferences, social norms, asking skills, and knowledge. Fruit and vegetable intake was assessed with 7-day records. Bivariate correlations with fruit and vegetable intake ranged from .17 for asking skills to .29 for fruit and vegetable preferences. In analyses controlling for school-level clustering, only preferences and positive outcome expectations remained significantly associated with fruit and vegetable intake, accounting for approximately 10%-11% of the variance. Limitations in the conceptualization, scope, and measurement of the variables assessed may have contributed to the weak associations observed. Models incorporating factors other than individual-level social-cognitive variables may be required to more fully explain children's dietary behavior.

Child↗
PubMed1997

Patterns in children's fruit and vegetable consumption by meal and day of the week.

OBJECTIVE: To assess differences in children's consumption of fruit and vegetables (F&V) by day of the week and meal of the day. DESIGN: Baseline data from two school based nutrition education studies were combined for analysis. SUBJECTS/SETTING: 2984 third grade students from 48 participating elementary schools in three school districts in the metropolitan Atlanta area. MEASURES OF OUTCOME: The frequency of consumption of F&V abstracted by trained registered dietitians from prompted 7-day food records. STATISTICAL-ANALYSES PERFORMED: Mixed model analysis with meals and days as terms, controlling for the within school correlation, gender and ethnic group. RESULTS: F&V were most frequently consumed at weekday lunch, and second most frequently at dinner. Participation in school lunch accounted for a substantial proportion of F&Vs consumed at lunch. Few F&Vs were consumed at breakfast or snack. CONCLUSIONS: School lunch makes an important contribution to elementary school students' F&V consumption. Dietary change programs should target parents to increase F&V consumption at dinner, and target students for the meals over which they assert the most control: breakfast and snacks.

Adolescent↗
PubMed1996

Synthesis and structure-activity relationships of 2-pyridones: a novel series of potent DNA gyrase inhibitors as antibacterial agents.

Two novel series of 2-pyridones were synthesized by transposition of the nitrogen of 4-quinolones to the bridgehead position. This subtle interchange of the nitrogen atom with a carbon atom yielded two novel heterocyclic nuclei, pyrido[1,2-alpha]pyrimidine and quinolizine, which had not previously been evaluated as antibacterial agents and were found to be potent inhibitors of DNA gyrase. Quinolizines with a methyl group at the 9-position such as (S)-45a (ABT-719) demonstrate exceptional broad spectrum antibacterial activity. Most notably, they are active against resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant strains of enterococci, and ciprofloxacin-resistant organisms. In addition, 2-pyridones also possess favorable physiochemical and pharmacokinetic properties. These 2-pyridones were synthesized from the commercially available starting materials by 10-17 linear transformations. The structure of an adduct yielded by this sequence, (S)-45a (ABT-719), was determined by X-ray crystallographic analysis.

Animals↗
PubMed1996

Separation and identification of metals in human bones, placenta and milk and in air by adsorption and ion-exchange thin-layer chromatography.

A TLC method for the separation of heavy metals and their complexes with dithizone, 4-(2-pyridylazo)resorcinol and ethylenediaminetetraacetic acid was devised and conditions for the solid-phase extraction of heavy metal ions in human bones, placenta and milk after microwave mineralization and in air after alkaline absorption were elaborated.

Adsorption↗
PubMed1996

A measure of stages of change in fruit and vegetable consumption among fourth- and fifth-grade school children: reliability and validity.

OBJECTIVE: We developed, pilot-tested, and field-applied a stages of change questionnaire regarding fruit and vegetable (F&V) consumption among fourth- and fifth-grade students. METHODS: The design included cross-sectional assessment of internal consistency and construct validity, and 2-week and 7-week longitudinal assessment of test-retest reliability. Subjects included 134 students from one school for pilot-testing and 252 from two schools for field application. Thirty-two questions from McConnaughy et al's stages of change questionnaire were adapted and pilot-tested; minor revisions were made for field application. Statistical analyses included principal components analysis to identify subscales; cluster analysis to identify subgroups within students; Cronbach's alpha coefficient to assess internal consistencies; Pearson product-moment correlations to assess test-retest reliabilities; and oneway ANOVA's by F&V stages of change clusters with actual F&V consumption, F&V self-efficacy subscales, F&V preferences, and F&V outcome expectations subscales to determine construct validity. RESULTS: Principal components analysis from the field application indicated two subscales (precontemplation and beyond precontemplation) accounting for 39.5% of variance. Cluster analysis indicated 6 interpretable clusters; 2 (n = 63) provided responses inconsistent with the stages of change theory and 4 (n = 189) provided responses consistent with the theory. Internal consistencies and test-retest reliabilities were acceptable. Students in the "beyond precontemplation" clusters had higher levels of self-efficacy and outcome expectations regarding eating F&V. CONCLUSIONS: Measuring stages of change other than the precontemplation stage in F&V consumption among elementary school children is problematic. Perhaps the theoretical concept does not apply to children, or elementary school children lack the ability to comprehend the questions measuring the concept, or the approach used was not entirely appropriate.

Attitude to Health↗
PubMed1994

Fruit and vegetable food frequencies by fourth and fifth grade students: validity and reliability.

OBJECTIVE: Due to the increased emphasis on fruit and vegetable (F+V) consumption and a desire to use the simplest dietary assessment method appropriate to determine F+V intake, we assessed the reliability and validity of weekly and monthly fruit and vegetable food frequency questionnaires (F+V FFQ) among fourth and fifth grade students by comparing them to food records previously validated through school lunch observations. METHODS: The multiethnic sample (primarily African-American and Caucasian) included predominantly lower-middle socioeconomic students from 10 classes at one elementary school. F+V FFQ were printed on optical scanning forms and classroom administered on two occasions. Students completed preprinted food record forms at school and received new forms weekly. To allow comparison between the F+V FFQ and food records, a dietitian abstracted information from the records according to a written protocol and transferred it to F+V FFQ forms covering respective time periods. F+V FFQ were converted to estimated daily servings and aggregated to create five F+V indices plus three summary indices. Statistical analyses included Spearman correlations and paired t-tests. RESULTS: Students demonstrated acceptable reliability in completing food records as well as weekly and monthly F+V FFQ; however, validity was unacceptable for both F+V FFQ versions due to significant overreporting. CONCLUSION: Of the two methods studied, the food record procedure is preferred over the FFQ procedure for collecting self-reported F+V consumption data among fourth and fifth grade students.

Child↗
PubMed1994

Accuracy of fourth- and fifth-grade students' food records compared with school-lunch observations.

Fourth- and fifth-grade students' food records completed by using a labor-intensive approach (with daily monitoring) or a less labor-intensive approach (with weekly monitoring) were compared with school-lunch observations. Records were completed at three elementary schools for 14-23 d by students in 26 classes. Record pages were printed forms with areas for recording items consumed, number of servings, and locations of meals. Students were randomly selected for lunch observation. Kappa coefficients and percent of agreement for interobserver reliability for both approaches combined ranged from 0.43 to 0.91 and 72.6% to 95.5%, respectively, on 24 observations. Pearson correlations for 117 record/observation matches were significant for eight and three of nine meal items for the daily and weekly monitoring approaches, respectively. Thus, students were reasonably accurate in keeping records and more accurate with the more labor-intensive approach. Researchers need to select an approach based on the degree of accuracy desired and available finances.

Child↗
PubMed1993

Measuring fruit and vegetable preferences among 4th- and 5th-grade students.

BACKGROUND: Achievement of the nation's Year 2000 fruit and vegetable goal of five or more daily servings may relate to children's preferences for fruits and vegetables. There are, however, no easily administered instruments for measuring preferences for fruits and vegetables among children. METHODS: An initial questionnaire systematically varied preparation methods after focus group discussions had indicated that this had an impact on fruit and vegetable preferences. The three-part questionnaire (fruits, vegetables, fruit and/or vegetable snacks) was classroom administered. Internal consistencies and test-retest reliabilities were acceptable. Principal components analyses, however, revealed food-specific rather than preparation factors; thus, preparation was eliminated from a revised questionnaire. RESULTS: Repeat classroom administration of the revised questionnaire yielded acceptable internal consistencies and test-retest reliabilities. Preferences were higher for fruits than vegetables. Principal components analyses indicated single fruit and vegetable factors and a two-factor solution for snacks (vegetables, fruits). Pearson correlations between preferences and consumption were significant, but accounted for only a small fraction of the variance. Correlations between fruit exposure and preferences, and between vegetable exposure and preferences were 0.55 and 0.51, respectively. CONCLUSION: The revised questionnaire provides a reliable, valid, and simple tool for assessing fruit and vegetable preferences of 4th- and 5th-grade students. The relationship between these preferences and actual consumption is weak; however, making fruits and vegetables more available may enhance preferences.

Child↗
PubMed1993

Observations on physical activity in physical locations: age, gender, ethnicity, and month effects.

The level of physical activity of 3- and 4-year-old children was assessed in alternative physical locations by month and time of day and by age, gender, and ethnicity. Physical activity was assessed by observation with the Children's Activity Rating Scale (CARS) for up to 12 hours from 7:00 am to 7:00 pm. A sample of 191 three- and four-year-old children was observed for up to four times in the course of a year. The sample was tri-ethnic. Boys were significantly more active than girls. Activity was consistently higher outside than inside. There were significant differences in the amount of time children in this age group spent inside versus outside by time of year; the activity levels of boys and girls differed by time of year, particularly when outside. A model including gender, month, and location terms accounted for 75% of the variance in physical activity. These data further documented gender differences in physical activity among very young children using measures not subject to self-report biases but did not explain or clarify the gender differences. The substantial differences by physical location and time of year deserve future attention, but more refined methods will be needed to balance data by location and important seasonal times. An inference from these results is that activity levels among young children may be increased by encouraging them to spend more time outdoors.

Activity Cycles↗
PubMed1993

Defining the year 2000 fruit and vegetable goal.

Various nutrition guidelines recommend increased consumption of fruits and vegetables (F+V); a Year 2000 goal targets five or more daily servings of F+V. Decisions are needed regarding how to define F+V to facilitate measurement of goal achievement. Four alternative definitions (narrow and broad, each with and without legumes) were developed and applied to food frequencies from 133 children and 211 parents. Results varied by definition. Mean intake met the goal of five or more daily servings regardless of definition and exceeded it for both broad definitions by children and both broad definitions and the narrow definition with legumes for adults. Median intakes met the goal for all definitions except for children with the narrow definition without legumes, and exceeded it for children with both broad definitions and for adults with the broad definition with legumes. These differences by definition indicate that a clear definition of F+V is needed.

Adult↗
PubMed1992

DNA topoisomerases from pathogenic fungi: targets for the discovery of antifungal drugs.

DNA topoisomerases, a class of enzymes that change the topological structure of DNA, have been shown to be the target of many therapeutic agents, including antibacterial agents (quinolones) and anticancer agents. These drugs inhibit the enzyme in a unique way so that the enzyme is converted into a cellular poison. Candida albicans and Aspergillus niger are two major opportunistic fungal pathogens. Our results show that these fungi have high levels of both type I and type II topoisomerases (with a minimum of 5 x 10(5) ATP-independent relaxation units and 2 x 10(5) P-4 unknotting units per liter of wild-type C. albicans). The ATP-dependent type II topoisomerase (termed C. albicans topoisomerase II) was purified by approximately 2,000-fold from C. albicans cells by using a simple isolation scheme that consists of three column procedures: hydroxylapatite, phosphocellulose, and heparin-agarose chromatographies. The responses of the Candida and the calf thymus topoisomerase II to some known topoisomerase II inhibitors were measured. Etoposide and 4'-(9-acridinylamino)methanesulfon-m-anisidide, compounds known to inhibit catalysis and to enhance DNA breakage by mammalian topoisomerase II, and A-80198, an etoposide derivative, enhanced cleavage by both enzymes at similar concentrations of these compounds, with the response of the calf thymus topoisomerase II from slightly to fourfold higher in magnitude than the response of the Candida enzyme in the same concentration range. In contrast, A-75272 (a cytotoxic tricyclic quinolone) shows a slightly stronger DNA cleavage enhancement effect with the Candida enzyme than with the mammalian counterpart. The abundance of the enzyme in cells and the different drug responses of the host enzyme and the fungal enzyme suggest that the fungal topoisomerase may serve as a target for the discovery of effective and safe antifungal agents.

Animals↗
PubMed1989

Mechanism of inhibition of DNA gyrase by quinolone antibacterials: specificity and cooperativity of drug binding to DNA.

Although the functional target of quinolone antibacterials such as nalidixic acid and norfloxacin has been identified as the enzyme DNA gyrase, the direct binding site of the drug is the DNA molecule [Shen, L. L., & Pernet, A. G. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 307-311]. As described in this paper, binding specificity and cooperativity of quinolones to DNA were further investigated with the use of a variety of DNA species of different structures and different base compositions. Results show that the drug binding specificity is controlled and determined largely by the DNA structure. The drug binds weakly and demonstrates no base preference when DNA strands are paired. The drug binds with much greater affinity when the strands are separated, and consequently, binding preference emerges: it binds better to poly(G) and poly(dG) over their counterparts including poly(dI). The results suggest that the drug binds to unpaired bases via hydrogen bonding and not via ring stacking with DNA bases. The weak binding to relaxed double-stranded DNA and the stronger binding to single-stranded DNA are both nonspecific as they do not demonstrate binding saturation and cooperativity. The specific type of binding, initially demonstrated in our previous publication with the supercoiled DNA and more recently with complex formed between linear DNA and DNA gyrase [Shen, L. L., Kohlbrenner, W. E., Weigl, D., & Baranowski, J. (1989) J. Biol. Chem. (in press)], occurs near the drug's supercoiling inhibition concentration. As shown in this paper, binding saturation curves of this type are highly cooperative (with Hill constant greater than 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1989

Mechanism of quinolone inhibition of DNA gyrase. Appearance of unique norfloxacin binding sites in enzyme-DNA complexes.

As a means of gaining additional information on the topoisomerase-mediated cytotoxicity induced by a variety of antibacterial and antitumor compounds we have examined the interaction of the quinolone anti-bacterial agent, norfloxacin, with the bacterial topoisomerase, DNA gyrase. Membrane filtration and spin-column techniques were used to study the binding of [3H]norfloxacin to purified plasmid DNA, DNA gyrase, and complexes formed by adding gyrase to different forms of plasmid DNA. Consistent with previous results (Shen, L. L., and Pernet, A. G. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 301-311) little [3H]norfloxacin binds to reconstituted gyrase, but significant levels of drug bind nonspecifically to relaxed DNA. However, when DNA and gyrase are incubated together additional norfloxacin binding sites are detectable. These complex-dependent sites are distinguishable from those sites involved in nonspecific DNA binding in that the complex-dependent sites are saturable and they retain bound norfloxacin after centrifuging the complex through a spin column. In addition, extent of binding is influenced by the topological state of DNA used to form the complex. The complex-dependent norfloxacin binding sites are likely involved in the inhibition of the enzyme since saturation of these sites occurs in the same norfloxacin concentration range as the inhibition of DNA supercoiling activity. Moreover, there is a close correlation of norfloxacin-induced DNA breakage with levels of norfloxacin bound to complexes of gyrase and relaxed DNA. These findings provide the first direct correlation of quinolone binding with inhibition of enzyme activity and induction of DNA breakage, and they suggest that the inhibition of DNA gyrase by norfloxacin occurs as a result of binding to a site which appears after the formation of a gyrase-DNA complex.

Binding Sites↗