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Biomedical subjects

R G Barr

Publications and source records attributed to R G Barr.

At least 73 records · Page 4Linked to original sources

Feeding and temperament as determinants of early infant crying/fussing behavior.

In the first 3 months of life, crying and fussing in normal infants tend to increase until 6 weeks of age and decrease progressively thereafter. To determine whether feeding choice and early infant temperament are predictors of early crying, 374 healthy, full-term infants were observed prospectively from birth to 6 weeks of age. Feeding choice and sociodemographic characteristics were ascertained in the first few days postpartum. Parents completed a 17-item early infant temperament questionnaire at 2 weeks of age and a 24-hour behavior diary for 8 days at 6 weeks of age. Initially breast-fed infants cried and fussed more frequently throughout 24 hours compared with those who were formula fed, and increased frequency and duration of crying and fussing were predicted by "more difficult" temperament. Furthermore, a different pattern of crying and fussing within the day was found for infants who were changed from breast- to formula feeding. However, according to stepwise multiple regression models, daily duration of crying/fussing was significantly predicted only by the temperament score (but not initial feeding choice), which accounted for 7% of the variance. Frequency of crying/fussing were predicted only by socioeconomic status, temperament, and feeding frequency, which accounted for 12% of the variance. Breast- or formula feeding at 6 weeks of age was independently associated with crying/fussing only during the evening. It was concluded that early infant temperament predisposes to early crying and fussing but is of limited use as a clinical predictor. Later crying/fussing behavior is not predicted by initial feeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Bottle Feeding↗

Improved sensitivity of proton MR to oxygen-17 as a contrast agent using fast imaging: detection in brain.

The potential utility of H2(17)O as a contrast agent has been demonstrated in biological solutions and isolated tissues but its use has been impaired by the need to run heavily T2-weighted spin-echo images. By choosing an appropriate steady-state free precession experiment sensitive to T1/T2, we have improved the available contrast-to-noise per unit time by more than a factor of 5. This allows easy measurement of the proton effects for concentrations as low as 0.4% H2(17)O in less than 1 min. Injection into small animals produces a marked reduction in the overall image intensity. Consecutive imaging at the rate of one every 52 s has been used to follow the rate of change in brain image intensity immediately after injection.

Animals↗

Oxygen-17 contrast agents. Fast imaging techniques.

Under physiologic conditions the stable isotope oxygen-17, in the form of O-17 water, lowers the proton T2 of blood, CSF, tissues, and whole organisms. With MRI the resulting changes in intensity can be detected using spin-echo pulse sequences, but much greater sensitivity is achieved in a fraction of the time with a steady-state free precession sequence such as FISP. With this sequence it is possible to detect levels as low as 0.4% Oxygen-17 water in 53 seconds or less.

Contrast Media↗

Dosage effects and individual responsivity to methylphenidate in attention deficit disorder.

Effects of three dosages of methylphenidate (0.15, 0.30 and 0.60 mg/kg) were assessed in 19 ADD-H children on a variety of cognitive, academic and behavioral measures in the laboratory and the classroom. A predominant linear pattern of improvement was found across almost all measures. A slight decrease between 0.3 and 0.6 mg/kg on one cognitive task leaves open the possibility that higher dosages reduce stimulant effectiveness or cause decrements on some kinds of "high-level/high load" tasks. Response patterns of individual children varied considerably across measures. All children improved on at least several measures. Results were interpreted as evidence for stimulant activation of self-regulatory processes.

Attention↗

Parental diary of infant cry and fuss behaviour.

Despite their common use parental diaries of infants' cry and fuss behaviour have not been compared with objective methods of recording. To understand what is meant by the descriptions of crying and fussing in the diaries, the diaries of 10 mothers of 6 week old infants were compared with tape recordings of vocalisations made by the babies over a 24 hour period. There were moderately strong correlations between the frequency of episodes (clusters of 'negative vocalisations') on the audiotape and episodes of 'crying and fussing' in the diaries, and between the duration of episodes on the audiotape and episodes of 'crying' in the diaries. To assess the acceptability of the diaries for recording information for clinical and epidemiological research, they were then used in a population study of a wide socioeconomic group. Usable data were obtained from 91% of the sample. The results suggest that despite pronounced differences between recording methods, these diaries may provide valid and useful reports of crying and fussing in the short term.

Child Behavior↗

Nursing interval and maternal responsivity: effect on early infant crying.

In industrialized societies, the unique pattern of crying in the first three months is "unexplained" but thought to be due to different biobehavioral factors from later crying behavior. To increase the range of the feeding and caretaking behaviors hypothesized to be relevant determinants of early crying, home observations and diary records were analyzed from samples of two subcultures of American middle-class women (La Leche League and "standard care" mothers; each n = 16) differing primarily in such practices. Both during and after the early crying stage, frequently fed infants cried or fretted less often (8.1 v 15.8 episodes per hour at 2 months of age; 10.7 v 16.6 episodes per hour at 4 months of age), and fewer of them exhibited rhythmic crying behavior (four v 11 at 2 months; eight v 13 at 4 months) during observations. However, only during the early crying period at 2 months were interval between feedings and maternal response latency shown to be independent determinants of cry/fret frequency (overall r2 = .35, P = .01), each factor accounting for approximately half of the explained individual variance. Furthermore, feeding interval was the only variable associated with rhythmic crying behavior at 2 months of age (r2 = .20;P = .01). In similar analyses at 4 months, there were no significant relationships with later crying or fretting. The results suggest that, in the presence of variation in feeding practice greater than that which is typical for our society, feeding interval may be a significant factor in early (but not later) crying behavior; furthermore, this effect is independent of and additive to the soothing effect of short response latency.

Breast Feeding↗

Oxygen-17 compounds as potential NMR T2 contrast agents: enrichment effects of H2(17)O on protein solutions and living tissues.

The isotopic enrichment of solutions, living tissues, and organisms with oxygen-17 in the form of H2(17)O shortens their proton NMR transverse relaxation times (T2) and produces changes in NMR image intensity. The transverse relaxation rate (1/T2) was found to be linearly dependent on the H2(17)O concentration in biological solutions up to 5% enrichment. The longitudinal relaxation time (T1) is not affected by enrichment. Equal concentrations of H2(17)O do not produce the same magnitude of T2 change in all physiological environments. The reasons for these differences are discussed. The results suggest that certain oxygen-17 compounds should be explored as "contrast agents" in magnetic resonance imaging.

Animals↗

Short term effects of methylphenidate on the cognitive, learning and academic performance of children with attention deficit disorder in the laboratory and the classroom.

Sixteen children meeting diagnostic criteria for Attention Deficit Disorder with Hyperactivity (ADD-H) were tested on methylphenidate (0.3 mg/kg) and placebo on cognitive, learning, academic and behavioral measures in a double-blind study. Assessments were carried out in the laboratory and in the children's regular classrooms. Results indicate methylphenidate-induced improvements on a majority of the measures. Drug-induced changes reflected increased output, accuracy and efficiency and improved learning acquisition. There was also evidence of increased effort and self-correcting behaviours. It is argued that reviewers have underestimated the potential of stimulants to improve the performance of ADD-H children on academic, learning and cognitive tasks.

Achievement↗

Increased carrying reduces infant crying: a randomized controlled trial.

The crying pattern of normal infants in industrialized societies is characterized by an overall increase until 6 weeks of age followed by a decline until 4 months of age with a preponderance of evening crying. We hypothesized that this "normal" crying could be reduced by supplemental carrying, that is, increased carrying throughout the day in addition to that which occurs during feeding and in response to crying. In a randomized controlled trial, 99 mother-infant pairs were assigned to an increased carrying or control group. At the time of peak crying (6 weeks of age), infants who received supplemental carrying cried and fussed 43% less (1.23 v 2.16 h/d) overall, and 51% less (0.63 v 1.28 hours) during the evening hours (4 PM to midnight). Similar but smaller decreases occurred at 4, 8, and 12 weeks of age. Decreased crying and fussing were associated with increased contentment and feeding frequency but no change in feeding duration or sleep. We conclude that supplemental carrying modifies "normal" crying by reducing the duration and altering the typical pattern of crying and fussing in the first 3 months of life. The relative lack of carrying in our society may predispose to crying and colic in normal infants.

Adult↗

Roentgenographic observation of gas-fluid levels in the colon of children with abdominal pain and malabsorption of lactose.

Gas-fluid levels in the colon observed in radiographs are abnormal and usually indicate serious gastrointestinal disease. Colonic gas-fluid levels associated with concurrent abdominal pain and malabsorption of lactose, documented by lactose breath hydrogen testing, were observed in five children. Incomplete lactose absorption is a relatively benign condition that can be added to the differential diagnosis of gas-fluid levels in the colon and may account for some cases of spontaneous resolution of clinical and radiologic signs in children presenting with acute recurrent abdominal pain.

Child↗

Determinants of weight and adiposity in the first year of life.

To overcome methodologic defects (failure to control for confounding factors, univariate statistical analyses) in previous studies of etiologic determinants of childhood adiposity, we carried out a prospective cohort study of 462 healthy, full-term infants observed from birth to 12 months. Postpartum, we obtained sociodemographic data and administered two recently validated scales of maternal attitudes toward feeding and infant body habitus. Parental heights and weights and infant feeding variables were determined by interview, and at 6 and 12 months we measured height and weight and triceps, subscapular, and suprailiac skinfolds. Multiple regression analysis was used to determine independently predictive factors for weight, body mass index (BMI = weight/height), and the sum of the three skinfold measurements. Birth weight, sex, age at introduction of solid, and duration of breast-feeding were all significant predictors of weight at 12 months (r2 = 0.296, P less than 0.0001). Significant determinants for BMI included birth weight, duration of breast-feeding, sex, and IBH (r2 = 0.125, P less than 0.0001); those for total skinfold were age at introduction of solid foods and birth weight (r2 = 0.038, P = 0.002). Similar results were obtained at 6 months, although slightly less of the variance was explained. We conclude that the ability to predict which babies will be heavy or obese during the first year is limited. Breast-feeding and delayed introduction of solid foods do offer some protective effect, however, and thus efforts to encourage these practices may be reaping some benefit.

Adult↗

Breath hydrogen excretion in normal newborn infants in response to usual feeding patterns: evidence for "functional lactase insufficiency" beyond the first month of life.

Sequential studies of morning breath hydrogen excretion were carried out in the homes of 16 normal breast-fed or formula-fed infants during the first 5 months of life. Except for two infants whose stools did not produce H2, all infants had elevated breath H2 excretion (greater than 10 parts per million) during and after the first month of life. There was a significant relationship to age (P less than 0.005) for all three measures of H2 excretion (4-hour average, peak, and preprandial), with mean values being highest in month 2, elevated but lower in month 1, and dropping significantly in months 3 and after. Additional 24-hour studies with six 7-week-old infants demonstrated that H2 excretion was inversely related to state of arousal, more likely to be detected in the afternoon, and not clearly related to time of feeding. These findings suggest that incomplete lactose absorption in response to usual feeding patterns persists beyond the first months of life in all infants. The pattern of breath H2 excretion indicates a probable developmental change in quantity and consistency of carbohydrate substrate delivered to colonic flora. Although elevated breath H2 excretion in response to normal feeding demonstrates incomplete absorption, it should not be used to determine an infant's status as a "lactose malabsorber."

Breast Feeding↗

Fasting breath hydrogen concentration: normal values and clinical application.

Excretion of hydrogen in breath commonly persists despite an overnight fast. Although elevation of hydrogen concentration above the fasting value after administration of a test sugar is evidence of malabsorption, the significance of the fasting value itself is unknown. We determined the normal limits of fasting breath hydrogen in healthy children and adults, and in patients with chronic diarrhea or recurrent abdominal pain. Fasting breath hydrogen in 221 healthy children and 9 healthy adults averaged 7.1 +/- 5.0 parts per million (mean +/- SD), exceeding 30 parts per million in less than 1%. No value exceed 42 parts per million. In 73 patients with recurrent abdominal pain and 76 patients with chronic diarrhea, fasting breath hydrogen was less than 42 parts per million in 97% and 83%, respectively. History and laboratory data were reviewed in the 15 patients where fasting breath hydrogen exceeded 42 parts per million. Seven had documented small bowel bacterial overgrowth and an additional 3 patients had radiographic evidence of intestinal stasis. Using test dinner meals, we prospectively evaluated the effect of previously ingested foods containing complex carbohydrates on fasting breath hydrogen. Dinner meals consisting of rice, wheat, or beans influenced fasting breath hydrogen values, but did not result in elevated fasting breath hydrogen in healthy individuals. Rice bread resulted in uniformly low fasting breath hydrogen values in healthy subjects (2.0 +/- 2.5 parts per million), but fasting breath hydrogen remained elevated in patients with bacterial overgrowth. Our studies indicate that conditions for measurement of the fasting breath hydrogen value may be standardized to improve discrimination between normal and abnormal values.

Abdomen↗

Maternal psychological determinants of infant obesity. Development and testing of two new instruments.

We have developed and tested two instruments to measure psychological factors that may affect infant feeding and thus "confound" the relationship between feeding and subsequent obesity. The Maternal Preconceptions of Ideal Infant Body Habitus (IBH) consists of 4 drawings of 9-month-olds exhibiting a range of body habiti from quite lean to very chubby; new mothers are asked to rank the 4 in order of preference for their new baby. The Maternal Feeding Attitudes (MFA) ia a 10-item questionnaire addressing the new mother's food "pushiness". Both the IBH and the MFA produced high test-retest intraclass correlation coefficients (RI's): 0.92 and 0.95, respectively. Significant inverse correlations were found between the IBH and both maternal age (r = -0.38; p = 0.004) and the Green SES index (r = -0.28; p = 0.025), indicating that older, higher-SES mothers prefer leaner infants. Breast-feeding mothers had significantly lower mean IBH scores than did formula-feeding mothers (p = 0.029). The MFA, by contrast, was not associated with any of these variables. We conclude that maternal adiposity preference and feeding attitudes can be reliably measured. Owing to their possible associations with infant obesity and its determinants, we suggest that these factors be included in future studies in this domain.

Adult↗

31P NMR studies of energy metabolism in perfused rat kidney.

Conventional biochemical analyses have demonstrated significant alterations in high-energy phosphate metabolism during shock, but the time course of these changes cannot be followed in individual animals because these analyses are invasive and destructive. This study sought to evaluate the utility of 31P NMR as a means of following phosphorus metabolites under various conditions, including those designed to model the shocked state. Twenty adult albino rats were subject to a modified Wiggers' model of hemorrhagic shock lasting from 5 to 140 min. ATP was determined on extracts of the kidneys of each animal both by a biochemical assay and by integration of 31P NMR resonance signals. The equation for renal ATP content plotted versus time for enzymatically determined ATP was 1.79 - 0.0097x (r = 0.83, P less than 0.01) as compared to 1.76 - 0.0093x (r = 0.69, P less than 0.01) for NMR-determined ATP. Isolated, normal rat kidneys perfused with oxygenated, modified Krebs' solution while in the NMR spectrometer maintained normal ATP levels for several hours. ATP/ADP ratios were greater than those observed by conventional enzymatic analysis. Temporary anoxia, induced by substituting 100% N2 for 95% O2:5% CO2, resulted in decreases in ATP content, which reverted to normal with reinstitution of oxygenation. Intracellular pH changed in accordance with perfusate pH during anoxia. It is concluded that 31P NMR studies of the perfused rat kidney have immediate application for the nondestructive study of energy metabolism in shock and ischemia.

Adenosine Diphosphate↗

Mucosal function and breath hydrogen excretion: comparative studies in the clinical evaluation of children with nonspecific abdominal complaints.

To evaluate the role of the lactose breath hydrogen test for the detection of lactose malabsorption in children with chronic nonspecific abdominal complaints, breath hydrogen excretion was measured in 131 children with recurrent abdominal pain (n = 75) or chronic nonspecific diarrhea (n = 56) following a lactose load (2 gm/kg; maximum 50 gm). The data were compared to those obtained from lactose tolerance tests (n = 113) and symptom response following a lactose load (n = 109) performed simultaneously with the lactose breath hydrogen test, and with results from small bowel biopsies obtained in 31 children to determine dissacharidase activity and mucosal histology. The results indicate that an increase in breath hydrogen of greater than 10 ppm above base line values (delta ppm) by 120 minutes ("early increase" response) completely discriminates between biopsy-proven isolated lactase-insufficient and lactase-sufficient children. A similar increase after 120 minutes ("late increase" response) is consistent both with normal mucosal function and partial lactase insufficiency due to mucosal injury. Breath hydrogen responses predicted assayed lactase activity in all patients with isolated lactase insufficiency, but were "falsely negative" in four of ten children whose lactase insufficiency was secondary to mucosal injury. In both clinical groups, lactose malabsorbers report significantly more symptoms than absorbers (P less than .001), but neither symptom reports nor tolerance tests are accurate methods for distinguishing lactose malabsorbers from absorbers. Although the lactose breath hydrogen test provides objective documentation of lactose malabsorption, it is equally predictive of assayed lactase activity in all clinical groups.

Abdomen↗