Search PubMed⌕ Search

Biomedical subjects

R G Barr

Publications and source records attributed to R G Barr.

At least 19 recordsLinked to original sources
PubMed1996

Crying patterns in preterm infants.

Healthy infants born at term cry most in the first three months of life, with a peak and increased crying in the evening during the second month. To determine whether the crying of preterm infants manifests similar features, the pattern of crying from 40 weeks gestational age through 24 weeks corrected age was described for 35 relatively healthy preterm infants born between 28 and 34 weeks gestational age. Despite their additional extra-uterine experience, they still cried significantly more after 40 weeks gestational age, with a peak and evening clustering at 6 weeks corrected age. The age of peak crying was not related to gestational age at birth, weight for gestational age, or a variety of perinatal and neurological indices. The results support the argument that the early-peak pattern is a robust maturational feature of early development and may be universal to human infancy.

Age Distribution↗
PubMed1995

Ethidium bromide binding to unstructured and structured 2' GMP.

For disordered 2' GMP and 5' GMP the ethidium cation (Etd) was found to form 1:1 and 2:1 Eth:nucleotide complex. For alkali metal solution self-structured 2'GMP and 5'GMP Etd was found to form 1:1 and 2:1 Etd: order nucleotide complex. The best computer fit was obtained for a structured nucleotide stoichiometry of Na4(2'GMP)8. Binding constants for the Etd:disordered 2'GMP complexes were determined to be (1.6 +/- 0.1) x 10(4)M(-1) and 6.3 +/- 0.5 M(-1) at O degrees C and (1.1 +/- 0.2) x 10(4) M(-1) and 18 +/- 11M(-1) for 5'GMP at 5 degrees C for the 1:1 and 1:2 complex, respectively. For the 1:1 and 1:2 2'GMP:Etd species the enthalpies were determined to be -19.8 +/- 1.0 kcal/mole and 0.1 +/- 0.3 kcal/mole, respectively, and the entropies were -53.3 +/- 6.6 eu and 3.9 +/- 1.6 eu, respectively. Binding constants for the Etd: structured 2'GMP complex, assuming a complex with stoichoimetry (Na+)4 (2'GMP)8 for the structured unit, were determined to be (1.9 +/- 0.1) x 10(4)M(-1) and 5.8 +/- 0.6) x 10(2)M(-1), respectively at 0 degrees C.

Ethidium↗
PubMed1995

Do high doses of stimulants impair flexible thinking in attention-deficit hyperactivity disorder?

OBJECTIVE: To test the hypothesis that high doses of methylphenidate (MPH) impair cognitive flexibility in attention-deficit hyperactivity disorder (ADHD). METHOD: A double-blind crossover design was used in an acute dosage trial to assess effects of three dosages (0.3, 0.6, and 0.9 mg/kg) of MPH on the performance of 17 ADHD children on five tasks designed to assess divergent thinking, perseveration, and ability to shift mental set. The tasks also assessed convergent thinking, problem solving, and speed and accuracy of processing. RESULTS: There was minimal evidence of deleterious effects on flexible thinking or other cognitive processes, either in the ADHD group as a whole or in any subgroup. The most common pattern indicated linear improvement across dosages. CONCLUSIONS: Under the acute dosage conditions used in this study, MPH doses up to 0.9 mg/kg had an increasingly positive effect on measures of mental flexibility and other cognitive processes. Rather than eliciting perseveration, MPH appeared to improve persistence. The generalized nature of the cognitive and motivational changes observed suggests that MPH acts on central, self-regulatory processes. Because effects of two or more daily doses can accumulate when MPH is prescribed in the clinical situation, clinical doses of more than 0.6 mg/kg were not recommended.

Attention Deficit Disorder with Hyperactivity↗
PubMed1995

"Sucrose analgesia" and diphtheria-tetanus-pertussis immunizations at 2 and 4 months.

In human newborns, small amounts of sucrose reduce crying with procedural pain by about 50%. To determine whether "sucrose analgesia" could be extended to painful procedures beyond the newborn period, 57 infants were randomly assigned to receive three 250-microliters doses of 50% sucrose solution (g/100 mL) or water before their diphtheria-tetanus-pertussis immunizations at 2 and 4 months of age. Crying during and after injection was measured separately to determine whether sucrose modified crying during the noxious stimulus, recovery from the stimulus, or both. Sucrose was effective in reducing crying only from 83 to 69%, and the reduction was limited to the postinjection period. We conclude that, although sucrose continues to have some effect beyond the newborn period, the effect is limited to recovery from the noxious stimulus, is clinically modest, and is probably smaller than in the newborn period.

Crying↗
PubMed1995

Supplementary carrying compared with advice to increase responsive parenting as interventions to prevent persistent infant crying.

OBJECTIVE: To compare two interventions (supplementary carrying, increased parental responsiveness) introduced from birth for their effectiveness in reducing the amounts of crying in general community infants at 2, 6, and 12 weeks age. DESIGN AND PARTICIPANTS: Mothers and infants in newborn wards of maternity hospitals were assigned to carrying intervention, responsiveness intervention, or control groups. Follow-up measures were used to confirm that the interventions were implemented and to determine their effects on infant crying. SETTING AND MEASUREMENTS: Diary measurements completed in the home were employed to measure the aspects of parental behavior targeted by the interventions. Audio recordings, diaries, and questionnaires assessed the amounts the infants cried and the impact of the crying on their mothers and the health services. Sample sizes at 6 weeks of age were 59 (carrying intervention), 57 (responsiveness intervention), and 94 infants (control group). RESULTS: The carrying intervention successfully increased the amounts the infants were carried, particularly while settled, to the target levels. The responsiveness intervention led to more limited increases in carrying and to a modest increase in feeding frequency, but did not affect measures of parental interactiveness and play. No differences in amounts of crying and fussing were found between the three groups of infants on any of the measures. Subsidiary analyses confirmed that the dependent variable (infant fuss/crying) and main independent variable (carrying while settled) were not significantly correlated. CONCLUSION: It is not, at present, possible to recommend either supplementary carrying or increased parental responsiveness as primary, preventative interventions to reduce infant crying.

Crying↗
PubMed1994

The effect of war on tuberculosis. Results of a tuberculin survey among displaced persons in El Salvador and a review of the literature.

SETTING: During wartime, civilian populations usually experience a drop in caloric intake, disruption of housing, and a diminution in availability of medical services. These disturbances might be expected to result in increased reactivation of tuberculosis, which may result in increased transmission. Such privations occurred in El Salvador during its 1980-92 civil war, particularly among the 20% of the population, or over 1 million people, who were displaced. OBJECTIVE: (1) To estimate the rate of transmission of tuberculosis among displaced Salvadorians prior to and during the war, and (2) to compare this result with experience in the literature. DESIGN: (1) A tuberculin survey was conducted in El Salvador in July 1992 among all residents aged 1-30 years in 12 communities of formerly displaced persons. (2) The English language literature on tuberculosis during wartime was reviewed. RESULTS: (1) Overall, 21.2% of the non-BCG vaccinated had significant tuberculin reactions, equivalent to an annual risk of infection of 2.3%. The trend in the annual risk of infection was upward over the latter 6 years of the war, stable over the first 6 years, and was downward prior to the war years. The estimated incidence of smear positive pulmonary tuberculosis was 125 per 100,000 or 3 times the reported rate for El Salvador. (2) A review of the literature showed consistent evidence for increased morbidity and mortality from tuberculosis during wartime. Increased transmission was suggested by those studies showing a rise in both incidence of tuberculous meningitis during war years and excess morbidity and mortality many years after a war. Two major population-based studies found no evidence of increased transmission based on the calculated annual risk of infection; however other studies examining younger or more severely affected populations, or following more prolonged wars, detected an apparent increase in the transmission of tuberculosis. CONCLUSIONS: Conditions of war are associated with a rapid increase in morbidity and mortality from tuberculosis, which appears to result in increased transmission among populations most severely affected by war. This increased transmission will result in increased morbidity and mortality for many years, underscoring the need for improved tuberculosis control in the post-war period in countries such as El Salvador that have been devastated by war.

Adolescent↗
PubMed1994

Structure sensitivity of amino proton exchange in 2'- and 5' - guanosine monophosphate dianions.

Proton NMR line broadening methods were used to determine the rates of amino proton exchange for disordered 2'- and 5' - GMP dianions in aqueous solutions containing tetramethylammonium (TMA+) cations. Replacing TMA+ with Na+ does not substantially alter the exchange rates, provided that H-bonded, Na(+)-directed tetramer structures are absent. Activation enthalpies (kcal/mol) and entropies (eu) for 2'-GMP are: delta H not equal to = 18.5 +/- 1.3, delta S not equal to = 9.6 +/- 4.2 for TMA+ salt at pH 8.10, and delta H not equal to = 14.7 +/- 2.6, delta S not equal to = -3.7 +/- 8.0 for the Na+ salt at pH 8.11. Extrapolated values of pseudo first-order rate constants at 25 degrees C are in the range of k = 1-10 sec-1. At suitable concentrations and temperatures, the Na+ salts of both 2'- and 5' - GMP formed stacked and unstacked tetramer units. Relative to the exchange kinetics observed for the disordered nucleotide, the exchange process in the tetramer units was catalyzed in half the amino protons and inhibited in the other half. The catalytic process (k > 10(3) sec-1) has been attributed to amino protons not involved in interbase H-bonding, where as the inhibited process (k < 10(-1) sec-1) was assigned to those protons which do form such bonds. The structure-catalyzed process in both the stacked and unstacked tetramers was manifested by a loss of NMR amino proton intensity due to weighted time-averaging with the resonance for bulk water. A bridging water molecule between an amino proton and a phosphate on an adjacent nucleotide in the tetramer unit may provide a mechanistic pathway for the structure-catalyzed process.

Guanosine Monophosphate↗
PubMed1994

Effects of intra-oral sucrose on crying, mouthing and hand-mouth contact in newborn and six-week-old infants.

To determine whether a single intra-oral administration of sucrose would calm infants and elicit mouthing and hand-mouth contact, crying newborn and six-week-old infants were given sucrose solution before one feed and sterile water before another in a cross-over trial. Six-week-old infants were also given sucrose and water after feeding. For the newborn infants, the calming effect was rapid, substantial and lasted for at least four minutes. Mouthing and hand-mouth contact increased, but for shorter durations. For the six-week-old infants, sucrose calmed for one minute only before feeding, but had no effects on mouthing or hand-mouth contact. The results imply that intra-oral sucrose has acute age-related effects on crying and suckling-feeding behaviour mediated by a pre-absorptive mechanism. Sucrose may tap a functional system for reducing distress related to feeding and/or regulation of infant state.

Administration, Oral↗
PubMed1993

Rhythmic organization of the sound of infant crying.

The purpose of the present study was to examine the temporal morphology and rhythmic structure underlying the repeated bursts of expiratory sounds in a sustained bout of crying of twenty-three 1-month-old infants. Durations of expiratory sounds and bursts were determined from a 90-s bout of naturally occurring cries recorded in the home before feeding. Results indicated wide individual differences in temporal morphology between infants and within infant cry sounds. Binary spectrum analysis of the presence of expiratory sounds in the cry sound detected rhythms in temporal organization at a wide range of dominant frequencies. Spectral complexity (higher numbers of peaks in the power spectrum) was related to a longer time since infants were last fed and shorter expiratory sounds. Results emphasize the importance of viewing cries of young infants as dynamic signals. An ontogenetic history of the rhythms of infant cry sounds may contribute to understanding organismic and environmental experiences which contribute to development.

Child Behavior↗
PubMed1993

Normality: a clinically useless concept. The case of infant crying and colic.

To summarize, it has been argued that: 1. The assessment of complaints about crying and colic present particular diagnostic problems. 2. The crying brought as a complaint seldom indicates disease. 3. Once clinical disease has been ruled out, the clinical meanings of normality and abnormality no longer apply. 4. At that point, one should not try to determine a "cut-off" point for abnormal crying, because (a) it is unhelpful clinically, (b) it is wrong in principle, and (c) it is not likely that any specific amount of crying is normal or abnormal, independent of context. 5. As a possible alternative, it is proposed that we should think of the behavior not a symptom of something the infant "has," but as something the infant "does." This behavior may have consequences that are functional or dysfunctional for the infant, the caregiver, or the infant-caregiver interaction. If this argument has merit, it may have some interesting and important implications for the way we think about, treat, and investigate developmental and behavioral problems including (but not limited to) infant crying and colic. First, what holds true for crying and colic may also hold for bedwetting and enuresis, overactivity and attention-deficit hyperactivity disorder, and abdominal pain and recurrent abdominal pain syndrome, to name just a few. As a brief test of their applicability, one might ask how often organic disease is found in these entities, or how often patients are investigated and treated because an arbitrary amount of these behaviors is taken to be "excessive" or abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)

Colic↗
PubMed1993

Crying and motor behavior of six-week-old infants and postpartum maternal mood.

OBJECTIVE: To determine whether prepartum and postpartum emotional distress in first-time mothers is associated with crying and fussing behavior and activity level in 6-week-old infants, after eliminating potential biases. DESIGN: Observational study examining predictive and concurrent associations between maternal emotions and infant behaviors. SETTING: General community. PARTICIPANTS: Expectant primiparas attending obstetricians' offices for routine prenatal care were recruited in the third trimester. Mothers and babies were required to be free of medical complications to complete the study. Of 113 mothers who enrolled, complete crying/fussing data were obtained in 88 dyads. Activity data were obtained in a designated subgroup of 50 infants. MEASUREMENTS: Mothers completed a self-report scale of emotional distress, the 28-item General Health Questionnaire, at 34 weeks of gestation and at 6 weeks postpartum. Crying/fussing data were obtained using a previously validated parent diary of infant behavior during the sixth week of life. Motor activity was measured objectively in the home setting with actometers. RESULTS: Third-trimester distress was not related to either infant crying/fussing or activity. Postpartum distress was significantly related to crying/fussing duration and bout frequency (r[88] = .45 and .28, respectively; both P < .01). These relations were not diminished after controlling statistically for background and/or potential mediating variables, nor could they be accounted for by different diary-recording styles in the mothers. Postpartum distress was not, however, related to activity level (r[50] = -.09; not significant). Furthermore, the pattern of maternal distress was associated differentially with crying levels. Distress levels increased from prepartum to postpartum among mothers of infants who met predefined clinical criteria for "colic," while decreasing in the others ("colic" status x period interaction: F(1,86) = 8.2; P < .01). Also, infant crying varied among four groups of mothers who differed according to presence and timing of clinically significant emotional disturbance (one-way analysis of variance, F (3,86) = 9.4; P < .001). Infants of mothers who became significantly distressed postpartum ("reactive") cried more than those in the other groups, even mothers who had been distressed both prepartum and postpartum ("depressed") (3.7 vs 2.7 h/d; P = .05, post hoc Tukey). CONCLUSIONS: Maternal emotional distress and infant crying behavior are associated in the postpartum period independent of reporting or referral biases. Clinically significant levels of crying (or "colic") are differentially associated with different patterns of clinically significant maternal distress. Reported concern about either maternal mood or infant crying behavior should be taken seriously as a possible indicator of a stressed mother-infant relationship.

Adult↗
PubMed1992

Short-term effects of feed composition on sleeping and crying in newborns.

To determine whether the composition of feedings would affect newborn behavior independently of the act of feeding itself, 53 two- to three-day-old normal newborns were randomly assigned to receive an extra feeding of water, carbohydrate (lactose), or balanced formula 3 hours after their usual early morning feeding. Previous studies in adult humans and animals, and a single study in human newborns, have indicated that more sleep might be expected following the carbohydrate feed compared with the water and balanced-formula feeds because of recruitment of centrally mediated serotonergic systems. Behavioral effects were assessed for 40 minutes postfeeding by direct observation of the newborn's states (quiet, active, and indeterminate sleep; drowsiness; non-cry wakefulness; and fret/cry). Feed composition did affect behavior, and the effects were fairly specific to particular newborn states. Non-cry wakefulness and drowsiness were unrelated to the presence or type of nutrients, but they tended to occur soon after the meal in all groups. Crying was increased in water-fed newborns relative to both carbohydrate- and formula-fed newborns. Sleeping showed specific patterns of change in all three groups. Sleep duration was increased in the balanced-formula group compared with the water group throughout the observation period. Contrary to the prediction, sleeping duration in carbohydrate-fed newborns never exceeded that of formula-fed newborns; rather, it resembled that of water-fed newborns early in the postprandial period, but formula-fed newborns later. These effects could not easily be explained by potential confounding factors such as handling, volume ingested, caloric intake, or plasma glucose concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Crying↗
PubMed1992

Pediatric pain: interacting behavioral and physical factors.

Pain in infants, children, and adolescents warrants study from a developmental, behavioral, and physiological perspective because maturation of physical, emotional, and cognitive systems influences the way in which pain is experienced and expressed. Pediatric pain is an underdeveloped area ripe for study within the realm of developmental and behavioral pediatrics, as noted by documentation of its undertreatment in children. The focus of this paper is to present issues relevant to the study of pain in children, using the example of the recurrent abdominal pain syndrome to illustrate points regarding epidemiology, assessment, and intervention. It is the opinion of these authors that pediatric pain must be understood from a developmental perspective in both clinical and nonclinical populations of children. Multidisciplinary approaches to research in pain aids in understanding the development of nociceptive transmission and inhibitory systems, the development of pain expression, and the influence of context on pain experience and behavior. The goal of research in pediatric pain is to understand these systems within a developmental context so that preventive and therapeutic intervention strategies can be developed to reduce children's distress and pain-related disability.

Abdominal Pain↗
PubMed1992

Temperament and the psychobiology of childhood stress.

This paper provides a conceptual overview of recent research on the developmental psychobiology of childhood stress. We propose that the construct of temperament can be regarded as an organizing principle in children's responses to environmental adversity, and we review three physiologic "windows" through which such responses can be usefully examined. It is concluded that individual differences between children in their psychobiologic reactivity to stressors may constitute an important and novel point of departure for future studies of stress and childhood morbidity.

Cardiovascular Physiological Phenomena↗
PubMed1992

The crying of infants with colic: a controlled empirical description.

To obtain a controlled empirical description of some of the measurable clinical features of colic in a naturalistic context, 38 infants whose mothers considered crying a problem ("colic") and 38 pair-matched control infants were observed and videotaped at home 10 minutes before and after an evening feed. The parents kept a diary of infant behaviors (including crying and fussing) for 7 days following the visit. Following Wessel et al (Pediatrics. 1954;14:421-434), each "colic" infant was classified according to the number of days per week that crying and fussing duration was greater than 3 h/d. The distribution of infants with colic suggested that there were two subgroups: Wessel's colic infants, with 3 days or more per week of more than 3 hours of crying and fussing per day; and non-Wessel's colic infants, with fewer such days. Maternal measures of total daily crying/fussing duration, crying/fussing bout length, and infant temperament and objective analyses of facial activity showed a consistent pattern of differences in which Wessel's colic infants differed from both non-Wessel's colic and control infants, who in turn did not differ from each other. Both colic groups differed from control infants only in the perception of postfeed cries as being more "sick sounding." The results imply that the complaint of colic represents two (or more) groups and that there may be meaningfully distinct colic syndromes. They also provide the first independent empirical support for Wessel and colleagues' clinical distinction between "fussy" and "contented" babies.

Colic↗