Polymorphism of the ADRB2 gene and response to inhaled beta- agonists in children with asthma: a meta-analysis

BACKGROUND

About 9% of children have asthma, corresponding to almost 6.8 million children in the USA and 1.1 million in the UK. Asthma exacerbations are the leading cause of pediatric emergency room visits and impose a large burden on the individual, family, and society. There is mounting evidence that therapeutic failure of inhaled beta-agonists is associated with polymorphisms of the beta(2)-adrenergic receptor gene (ADRB2); specifically, mutations leading to amino acid changes at positions 16 and 27, which alter down-regulation of the beta(2)-adrenergic receptor (beta(2)AR), induce resistance to the smooth-muscle relaxing effect of beta(2)-adrenergic agonists.

METHODS

We conducted a meta-analysis to examine the association between ADRB2 polymorphisms and the response to inhaled beta(2)-adrenergic agonists in children with asthma. We included all published studies until November 2008, in which asthmatic children underwent testing for acute bronchodilator response, defined as > or = 15% improvement in forced expiratory volume in 1 second (FEV(1)) and single nucleotide polymorphism (SNP) genotyping for positions 16 and/or 27 of the beta(2)AR. Individual and summary odds ratios were calculated using a random effects model.

RESULTS

We identified three case-control or family-based studies involving 960 asthmatic children (692 children with negative beta(2)-bronchodilator response, defined as < 15% improvement in FEV(1) and 268 children with positive bronchodilator response). We found a significant association between favorable therapeutic response to inhaled beta(2)-adrenergic agonists in asthmatic children and the Arg/Arg phenotype at position 16 of the beta(2)AR [OR = 1.77; 95% CI (1.01; 3.1); p = 0.029], compared with the Arg/Gly or Gly/Gly phenotypes. The beneficial effect of Arg at position 16 of the beta(2)AR was most pronounced in African-American asthmatic children [OR = 3.54; 95% CI (1.37, 9.13)]. There was no association between clinical response to beta(2)-agonists and polymorphism at amino acid position 27 of the beta(2)AR (OR = 1.04; 95% CI [0.76,1.42]).

CONCLUSIONS

Failure of bronchodilator response to inhaled beta-agonists in asthmatic children is associated with the Gly allele (Arg/Gly and Gly/Gly genotypes) at position 16 of the beta(2)-adrenergic receptor. Genetic typing for beta(2)AR polymorphism may help identify children with drug-resistant asthma.

Cerebrospinal fluid lactate dehydrogenase isoenzymes in children with bacterial and aseptic meningitis

Differentiation of bacterial from aseptic meningitis may be difficult. Our aim was to determine the pattern of distribution of lactate dehydrogenase (LDH) isoenzymes in the cerebrospinal fluid (CSF) of patients with bacterial and aseptic meningitis. One hundred and fifty-seven patients with suspected meningitis were enrolled in the study. They were divided into 3 groups according to the culture- or bacterial antigen assay-proven diagnosis and CSF findings: bacterial meningitis (n = 31), aseptic meningitis (n = 65), and non-meningitis (n = 61). Total LDH level and percentages of LDH isoenzymes in the CSF were measured in each patient. Each group showed a distinct LDH isoenzyme distribution pattern, with a statistically significant difference among the groups in the percentages of the various isoenzymes. Compared with the non-meningitis group, total LDH activity in the CSF was high in the aseptic meningitis group (49.82+/-35.59 U/L, P < 0.001) and exaggerated in the bacterial meningitis group (944.53+/-112.3 U/L, P < 0.001). Low LDH-2 levels were unique to bacterial meningitis (P < 0.01), whereas high LDH-3 levels were characteristic of aseptic meningitis (P < 0.05). Both groups had low levels of LDH-1 and high levels of LDH-4 and LDH-5. In conclusion, the LDH isoenzyme pattern may be of clinical diagnostic value in meningitis, particularly when culture results are pending.

Pharmacologic treatment of hyperthyroidism during lactation

QUESTION

I have a patient who has hyperthyroidism due to Graves disease. She was taking methimazole but discontinued when she found out she was pregnant. She is currently close to delivery and might require antithyroid therapy in the postpartum period. Can methimazole cross into human milk, and is breastfeeding safe for her infant?

ANSWER

The exposure of infants to methimazole or propylthiouracil through breast milk is minimal and not clinically significant. Women with hyperthyroidism using methimazole or propylthiouracil should not be discouraged from breastfeeding, as the benefits of breastfeeding largely outweigh the theoretical minimal risks.

Daclizumab therapy for children with corticosteroid-resistant acute graft-vs.-host disease

MAbs such as daclizumab have shown promising results in the treatment of corticosteroid-resistant aGVHD. Data describing the efficacy of MAbs in children are limited. We describe the efficacy of daclizumab in children with corticosteroid-resistant aGVHD. Seventeen children (0.4-16.2 yr) received daclizumab for aGVHD. Safety was evaluated in all 17. Response was evaluated in the 15 children who received a full course of daclizumab. A PR was defined as improvement of aGVHD symptoms in at least one organ without worsening in other organs. We observed an overall response rate (CR plus PR) of 40% (6/15). Four children had a CR and two had a PR. aGVHD involving the gut had the highest response rate (five of 10; 50%). Adverse effects attributed to daclizumab were limited to an episode of reactive arthritis. Mortality was high (47%; eight of 17) though five of the six responders to daclizumab survived. The mean length of follow-up in the surviving nine patients was 32 months (range seven to 48). We conclude that daclizumab is effective in the treatment of children with corticosteroid-resistant aGVHD, especially in patients with gut involvement.

Use of hypoglycemic drugs during lactation

QUESTION

My patient was taking glipizide (an oral sulfonylurea) for type 2 diabetes. Now she is pregnant and taking insulin instead. She is very anxious to return to her previous treatment immediately after delivery because of the pain and hurdles associated with the administration of insulin. Can sulfonylureas cross into human milk and, if so, is it safe for her to breastfeed her infant?

ANSWER

The exposure of infants to second-generation sulfonylureas (eg, glipizide, glyburide) through breast milk is expected to be minimal, based on the limited data available. Women with type 2 diabetes treated with sulfonylureas should not be discouraged from breastfeeding. The benefits of breastfeeding greatly outweigh the risks of these medications, if any. The baby should, however, be monitored for signs of hypoglycemia.

Methadone exposure during lactation

QUESTION

One of my patients is currently using methadone for maintenance of opioid dependence. She wants to breastfeed. Is breastfeeding safe for her infant?

ANSWER

The exposure of infants to methadone through their mothers' breast milk is minimal. Women using methadone for treatment of opioid dependence should not be discouraged from breastfeeding. The benefits of breastfeeding largely outweigh any theoretical minimal risks.

Invasive Kingella kingae infections in children: clinical and laboratory characteristics

OBJECTIVE

Kingella kingae, a Gram-negative coccobacillus, is being increasingly recognized as an invasive pathogen in children, causing mainly bacteremia and arthritis; however, there have been only a few studies on K kingae infections to date, mostly small-scale series. The aim of this study was to report our experience with invasive K kingae infections in children who were hospitalized at a major tertiary medical center in Israel.

METHODS

The medical charts of 62 children with proven invasive K kingae infections were reviewed: 42 with positive blood culture results and 20 with positive synovial fluid culture results.

RESULTS

Most infections occurred among previously healthy children aged 5 to 22 months. Eighty percent had a mild concurrent illness of the respiratory or gastrointestinal tract. A chronic underlying disease was documented in 19% of the 1- to 15-year-old children with bacteremia. Three patients had persistent bacteremia, identified by 2 positive blood cultures drawn 1 to 4 days apart. Four (10%) patients from the bacteremia group had endocarditis, and 2 required emergency cardiac surgery. Only a mild-to-moderate elevation of serum inflammatory markers was noted except for patients with endocarditis or a prolonged course of arthritis. Patients with bacteremia received a diagnosis significantly later than those with arthritis, with no other between-group differences in age, month of disease onset, and inflammatory marker levels. All K kingae isolates were resistant to vancomycin and clindamycin.

CONCLUSIONS

Our large series indicates that invasive K kingae infections occur in previously healthy children, mostly during the first 2 years of life; affected older children usually have an underlying medical condition. The infection generally elicits only a mild inflammatory response unless accompanied by endocarditis. Despite its low virulence, K kingae might cause a life-threatening heart disease that requires emergent, aggressive treatment.

Polymorphism of the MDR1/ABCB1 C3435T drug-transporter and resistance to anticonvulsant drugs: a meta-analysis

BACKGROUND

Approximately one-third of patients with epilepsy patients have recurrent seizures despite therapy. It has been suggested that therapeutic failure is associated with high expression of the multidrug efflux ABCB1 (MDR1) drug-transporter; specifically, that patients with the 3435CC genotype have higher efflux of anticonvulsants out of brain tissue, with correspondingly lower concentrations in the central nervous system.

METHODS

We conducted a meta-analysis to examine the association between MDR1 polymorphisms and the response to anticonvulsants. We included all published studies until September 2007, in which patients with responsive and unresponsive seizure disorders underwent genotyping for ABCB1 C3435T. Individual and summary odds ratios were calculated using a random effects model. A secondary analysis was also performed, stratifying the studies by their ethnic distribution to account for genetic heterogeneity. We also performed a cumulative analysis by date of publication for the included studies using a random effects model.

RESULTS

We identified 11 case-control studies involving 3,371 patients (1,646 patients with drug-resistant epilepsy and 1,725 controls). We identified no significant association between anticonvulsant drug resistance and MDR1 polymorphism [odds ratio 1.15; 95% confidence interval (CI) 0.78-1.70; p = 0.48). Subanalysis of studies according to ethnicity yielded similar findings [European cohort: OR = 1.31; 95% CI 0.89-1.94, p = 0.18; Asian cohort: OR = 0.99; 95% CI 0.51-1.89, p = 0.96).

CONCLUSIONS

We found no association between ABCB1 genotype and response to anticonvulsant drugs. At the present time, genetic typing for MDR1 polymorphism is not warranted for patients with drug-resistant epilepsy.

Antenatal use of selective serotonin-reuptake inhibitors and QT interval prolongation in newborns

OBJECTIVES

Prolongation of the QT interval is a risk factor for sudden death. Selective serotonin-reuptake inhibitor antidepressants can prolong the QT interval and are widely used by pregnant women. Whether antenatal exposure to selective serotonin-reuptake inhibitor causes QT prolongation in offspring is unknown. The aim of this study was to determine the effect of maternal use of selective serotonin-reuptake inhibitor antidepressants during pregnancy on the QTc interval of the offspring.

METHODS

Between January 2000 and December 2005, we collected data on all of the newborns born at a single tertiary care hospital. Electrocardiograms of infants exposed to selective serotonin-reuptake inhibitor antidepressants in utero were compared with those of healthy control newborns matched on gestational age. The tracings were interpreted by a pediatric cardiologist who was unaware of the drug exposure.

RESULTS

We identified 52 newborns exposed to selective serotonin-reuptake inhibitor antidepressants in the immediate antepartum period and 52 matched control subjects. The mean QTc was significantly longer in the group of newborns exposed to antidepressants as compared with control subjects (409 +/- 42 vs 392 +/- 29 milliseconds). Five (10%) newborns exposed to selective serotonin-reuptake inhibitor antidepressants had a markedly prolonged QTc interval (>460 milliseconds) compared with none of the unexposed newborns. The longest QTc interval observed among exposed newborns was 543 milliseconds. All of the drug-associated repolarization abnormalities normalized in subsequent electrocardiographic tracings.

CONCLUSIONS

Antepartum use of selective serotonin-reuptake inhibitor antidepressants is associated with QTc interval prolongation in exposed neonates. Additional research using a standardized protocol is needed to determine whether exposure to selective serotonin-reuptake inhibitor antidepressants in late pregnancy is also associated with arrhythmias.

Establishing causality in pediatric adverse drug reactions: use of the Naranjo probability scale

Carbamazepine hypersensitivity syndrome is a rare, life-threatening condition. Its diagnosis is critical to avoid future exposure to aromatic anticonvulsants. Pediatricians rarely use a systematic approach to establish the cause of drug reactions in the clinical setting. We describe the use of the Naranjo adverse drug reaction probability scale to establish causality in three cases of suspected anticonvulsant hypersensitivity syndrome with the aim of introducing clinicians to this effective tool. Our analysis reveals that this method is useful, but also highlights potential areas for its improvement.

Generalized seizures following topical lidocaine administration during circumcision: establishing causation

We report a case of neonatal seizures after lidocaine administration for circumcision. A 3-month-old male infant received an overdose as evidenced by toxic lidocaine levels and developed generalized seizures shortly after. Back extrapolation of the serum lidocaine concentration to time zero was used to determine the administered dose. The Naranjo scale was used to determine causation; probable causation was defined. Particular care must be taken to administer an appropriate dose of local anesthetics in infants to avoid life-threatening seizures.

Pharmacokinetic disposition and clinical outcomes in infants and children receiving intravenous busulfan for allogeneic hematopoietic stem cell transplantation

We conducted a retrospective pharmacokinetic analysis of i.v. busulfan in children undergoing hematopoietic stem cell transplantation (HSCT) and describe its relation to transplantation outcomes. Forty-five children (median age, 3 yr) underwent HSCT at The Hospital for Sick Children from April 2003 through January 2006 and received i.v. busulfan every 6 h as part of their conditioning regimen. Initial busulfan doses were based on actual patient weight: <9 kg, 0.95 mg/kg per dose; 9-16 kg, 1.2 mg/kg per dose; 16-23 kg, 1.1 mg/kg per dose; 24-34 kg, 0.95 mg/kg per dose; >34 kg, 0.8 mg/kg per dose. Plasma busulfan concentrations were obtained after the first dose. The fourth and subsequent busulfan doses were adjusted to achieve an area under the concentration versus time curve (AUC) of 900-1500 microM.min. Development of hepatic venous occlusive disease (HVOD; modified Baltimore criteria) and engraftment (absolute neutrophil count >or=0.5 x 10(9)/L) were evaluated. Busulfan pharmacokinetic parameters were calculated using 1-compartment methods. Mean busulfan pharmacokinetic parameters were maximum concentration (C(max); 4.7 +/- 0.75 microM), volume of distribution at steady state (0.68 +/- 0.17 L/kg), elimination rate constant (0.0051 +/- 0.0010 min(-1)), total body clearance (3.5 +/- 1.23 mL/[min.kg]), and AUC (1271 +/- 280 microM.min). Mean volume of distribution at steady state was larger in children <1 yr of age (0.77 +/- 0.24 vs 0.64 +/- 0.11 L/kg; P = .040) and children <4 yr of age (0.73 +/- 0.18 vs 0.60 +/- 0.11 L/kg; P = .001) than in older children. Compared with older children, mean weight-adjusted total body clearance was higher in children <4 yr of age (3.8 +/- 1.40 versus 3.0 +/- 0.76 mL/[min.kg]). HVOD was diagnosed in 8 children (18%), including 4 children <1 yr of age. Children who developed HVOD achieved a lower C(max) than did those without HVOD (4.2 +/- 0.68 versus 4.8 +/- 0.73 microM; P = .035). Other than C(max), no association was observed between busulfan disposition and development of HVOD in children for whom i.v. busulfan doses were adjusted to achieve a target AUC. The influence of factors other than busulfan disposition on transplantation outcomes, such as genetic polymorphisms, should be evaluated.

Omega-3 fatty acid supplementation during pregnancy: for mother, baby, or neither?

QUESTION

Several pregnant patients have asked recently whether media reports of children's intelligence quotients' increasing with increased intake of essential fatty acids are meaningful enough to be worth the effort of supplementation. What advice should they be given?

ANSWER

Existing evidence from interventional studies is sparse and conflicting and should not lead to supplementation with polyunsaturated fatty acids.

Increased rate of major birth malformations in infants with neonatal “asymmetric crying face”: A hospital-based cohort study

Asymmetric crying face (ACF) is a minor anomaly found in 3-8 per 1,000 births, which may be associated with other anomalies. Previous studies on this topic included small groups of selected subjects, resulting in large variations in findings. The aim of this study was to examine the characteristics and associated anomalies of newborn infants with ACF compared with the general population of newborn infants. The study included newborn infants delivered between 1993 and 2003 at the Department of Neonatology of Rabin Medical Center, Israel. Charts of all newborns diagnosed with ACF were reviewed for obstetric and neonatal details, then compared with non-ACF newborns. ACF was diagnosed in 258 of 67,289 newborns (0.38%), with left-side predominance (77%). Major malformations were found in 7% of ACF infants, 3.5-fold higher than in the total Israeli population. Mild anomalies were present in 15% of the ACF group, and deformations in 4.6%. There was a higher rate of forceps deliveries in the ACF group (RR = 2.73, 95% CI = 1.37-5.42). ACF was more prevalent among females, and the male:female ratio was lower in the ACF group (0.86 vs. 1.06, P = 0.05). The rate of low-birth-weight infants was 3.9% among ACF infants and 9.6% in the control group (RR = 0.41, 95% CI = 0.23-0.76). No significant between-group difference was found for rates of primiparity, macrosomia, prematurity, postmaturity, or size-for-gestational-age. Thus, ACF is associated with a high rate of major malformations. This should prompt clinicians to seek for additional birth defects in ACF infants.

Exposure to alcohol-containing medications during pregnancy

QUESTION

A pregnant patient consulted her physician after discovering that a diphenhydramine preparation (Benadryl elixir) she used for allergy symptoms during the first trimester of her pregnancy contained 15% alcohol. Should she be concerned about fetal alcohol spectrum disorder in her baby?

ANSWER

Most ethanol-containing medical preparations are safe during pregnancy. Adult doses of some elixirs with high ethanol concentrations might produce blood levels similar to those achieved by drinking 1 alcoholic beverage. Caution is advisable when prescribing ethanol-containing elixirs to pregnant women, as is informing them about the alcohol content.