Caffeine is the most widely consumed behaviorally active substance in the world. Almost all caffeine comes from dietary sources (beverages and food), most of it from coffee and tea. Acute and, especially, chronic caffeine intake appear to have only minor negative consequences on health. For this

Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use

Growth and development can be investigated using readily observable demographic factors such as weight and age. Size is the primary covariate and can be referenced to a 70-kg person with allometry using a coefficient of 0.75 for clearance and 1 for volume. The use of these coefficients is supported by fractal geometric concepts and observations from diverse areas in biology. Fat free mass (FFM) might be expected to do better than total body weight when there are wide variations in fat affecting body composition. Clearance pathways develop in the fetus before birth. The use of postnatal age as a descriptor of maturation is unsatisfactory because birth may occur prematurely; therefore postmenstrual age is a superior predictor of elimination function. A sigmoid E(max) model (Hill equation) describes gradual maturation of clearance in early life leading to a mature adult clearance achieved at a later age.

Mechanism-Based Concepts of Size and Maturity in Pharmacokinetics

Objective:The diagnosis of infection in critically ill patients is challenging because traditional markers of infection are often misleading. For example, serum concentrations of calcitonin pre-cursors are increased in patients with infections. However, their predictive accuracy for the diagnosis of

Calcitonin precursors are reliable markers of sepsis in a medical intensive care unit.

Gastroesophageal reflux (GER), defined as passage of gastric contents into the esophagus, and GER disease (GERD), defined as symptoms or complications of GER, are common pediatric problems encountered by both primary and specialty medical providers. Clinical manifestations of GERD in children include vomiting, poor weight gain, dysphagia, abdominal or substernal pain, esophagitis and respiratory disorders. The GER Guideline Committee of the North American Society for Pediatric Gastroenterology and Nutrition has formulated a clinical practice guideline for the management of pediatric GER. The GER Guideline Committee, consisting of a primary care pediatrician, two clinical epidemiologists (who also practice primary care pediatrics) and five pediatric gastroenterologists, based its recommendations on an integration of a comprehensive and systematic review of the medical literature combined with expert opinion. Consensus was achieved through Nominal Group Technique, a structured quantitative method. The Committee examined the value of diagnostic tests and treatment modalities commonly used for the management of GERD, and how those interventions can be applied to clinical situations in the infant and older child. The guideline provides recommendations for management by the primary care provider, including evaluation, initial treatment, follow-up management and indications for consultation by a specialist. The guideline also provides recommendations for management by the pediatric gastroenterologist. This document represents the official recommendations of the North American Society for Pediatric Gastroenterology and Nutrition on the evaluation and treatment of gastroesophageal reflux in infants and children. The American Academy of Pediatrics has also endorsed these recommendations. The recommendations are summarized in a synopsis within the article. This review and recommendations are a general guideline and are not intended as a substitute for clinical judgment or as a protocol for the management of all patients with this problem.

Guidelines for evaluation and treatment of gastroesophageal reflux in infants and children: recommendations of the North American Society for Pediatric Gastroenterology and Nutrition.

Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus

Procalcitonin as a marker for the early diagnosis of neonatal infection

The maturation of the different pathways of caffeine metabolism was studied during infancy. The group of children (n = 14) consisted of four premature newborn infants and 10 older infants who received caffeine citrate solution. Caffeine and 11 of its metabolites were measured by HPLC. Total demethylation and N3- and N7-demethylation increase exponentially with postnatal age; the plateau is reached by 120 days and accounts for 58.6%, 90.5%, and 79.3%, respectively. N1-demethylation shows no variation with postnatal age. It is suggested that N3-demethylation is more important in young infants than in adults and that maturation of N1-demethylation occurs later than 19 months of age. 8-Hydroxylation is mature as early as 1 month of age and may be higher in infants than in adults. Acetylation is not mature before at least 1 year of age. Differences in maturation rate of acetylation may be related in part to genetic acetylator status.

Maturation of caffeine metabolic pathways in infancy.

Small-bowel bacterial overgrowth in children with chronic diarrhea, abdominal pain, or both

Caffeine acetylator phenotype was studied during maturation in 54 8− to 447-d-old children hospitalized for minor disease (group A) and in five 3− to 630-d-old children with Pierre Robin syndrome (group B). In group A, the children received 2.5 mg/kg caffeine orally once between birth and 15 mo. Group B patients were chronically treated with caffeine (2.3 to 15.8 mg/kg/d) for prevention of apneas, and the acetylator phenotype was serially determined. Phenotyping was performed on a spot urine sample collected 2–6 h after drug administration. Caffeine metabolites [5-acetylamino-6-formylamino-3-methyl uracil (AFMU), 1-methylxanthine, 1-methyluric acid, 1,7-methyluric acid, and 1,7-methylxanthine) were measured using HPLC. Acetylator phenotype was determined on the basis of AFMU/1-methylxanthine (ratio 1) and AFMU/AFMU + 1-methyluric acid + 1-methylxanthine + 1,7-methylxanthine + 1,7-methyluric acid (ratio 2) molar ratios. In group A, all children were slow acetylators before 83 d of age (ratio 1 < 0.4; ratio 2 < 0.08), whereas older children included slow and fast acetylators. The acetylation molar ratios differed significantly between age groups and increased with age. The cumulative percentage of fast acetylators increased with age but the plateau was not yet reached at 15 mo. In three children, the phenotyping was repeated after 15 mo: the second determination was consistent with the first one. In group B, all children appeared as slow acetylators on the first phenotyping. Four of them appeared subsequently as fast acetylators; one remained a slow acetylator until 11 mo. These results suggest that maturation of caffeine acetylation occurs during at least the first 15 mo of life for fast acetylators but is not detectable in slow acetylators. Acetylator status cannot reliably be determined before at least 15 mo.

/pdf/caffeine-acetylator-phenotyping-during-maturation-in-infants-4ewjarktvy.pdf

Caffeine Acetylator Phenotyping during Maturation in Infants

Four premature neonates and eight infants 1–19 months old received caffeine for apnea The usual morning oral dose was substituted by 1,3,7 13C-trimethylxanthine (13C-tri CAF) as the citrate salt Five breath samples were collected the day before (day 1) and the day of 13C-tri CAF administration (day 2) Plasma (after each breath collection) and urine were collected on day 213C-CO2 exhalation was determined by isotope ratio mass spectrometry Caffeine and its metabolites were measured using high-pressure liquid chromatography Assessment of the labeled CO2 in the breath revealed no detectable 13C-tri CAF N-demethylation activity in infants before 45 wk postconceptional age However, demethylation (as urinary metabolites) has been detected before that age Two-, 4-, and 6-h cumulative excretion of 13C-tri CAF as 13C-CO2 increased with postnatal age and correlated with caffeine plasma clearance (r = 0840, p < 001) These results were consistent with those obtained for urinary metabolites In one infant (19 months old) the cumulative excretion of 13C-CO2 while crying was 65% of the value observed during quiet breathing The measurement of caffeine demethylation using the caffeine CO2 breath test is feasible in infants and is a safe and noninvasive method to determine age related changes in P4501-dependent N-demethylase activity

/pdf/maturation-of-caffeine-n-demethylation-in-infancy-a-study-2ud9st81kk.pdf

J. Badoual

Papers

Procalcitonin as a marker for the early diagnosis of neonatal infection

Maturation of caffeine metabolic pathways in infancy.

Small-bowel bacterial overgrowth in children with chronic diarrhea, abdominal pain, or both

Caffeine Acetylator Phenotyping during Maturation in Infants

Maturation of caffeine N-demethylation in infancy: a study using the 13CO2 breath test.