Catherine E. Correia

Impaired Intestinal Iron Absorption in Crohn’s Disease Correlates with Disease Activity and Markers of Inflammation

Background Anemia in patients with Crohns disease (CD) is a common problem of multifactorial origin, including blood loss, malabsorption of iron, and anemia of inflammation. Anemia of inflammation is caused by the effects of inflammatory cytokines [predominantly interleukin‐6 (IL‐6)] on iron transport in enterocytes and macrophages. We sought to elucidate alterations in iron absorption in pediatric patients with active and inactive CD. Methods Nineteen subjects with CD (8 female, 11 male patients) were recruited between April 2003 and June 2004. After an overnight fast, serum iron and hemoglobin levels, serum markers of inflammation [IL‐6, C‐reactive protein (CRP), and erythrocyte sedimentation rate], and a urine sample for hepcidin assay were obtained at 8 am. Ferrous sulfate (1 mg/kg) was administered orally, followed by determination of serum iron concentrations hourly for 4 hours after the ingestion of iron. An area under the curve for iron absorption was calculated for each patient data set. Results There was a strong inverse correlation between the area under the curve and IL‐6 (P = 0.002) and area under the curve and CRP levels (P = 0.04). Similarly, the difference between baseline and 2‐hour serum iron level (&Dgr;[Fe]2hr) correlated with IL‐6 (P = 0.008) and CRP (P = 0.045). When cutoff values for IL‐6 (>5 pg/mL) and CRP (>1.0 mg/dL) were used, urine hepcidin levels also positively correlated with IL‐6 and CRP levels (P = 0.003 and 0.007, respectively). Conclusions Subjects with active CD have impaired oral iron absorption and elevated IL‐6 levels compared with subjects with inactive disease. These findings suggest that oral iron may be of limited benefit to these patients. Future study is needed to define the molecular basis for impaired iron absorption.

Clinical evaluation of a portable lactate meter in type I glycogen storage disease

SummaryHigh lactate concentrations occur in type I glycogen storage disease (GSD) whenever glycogenolysis occurs. Not only does hyperlactataemia cause acute clinical deterioration, but chronic lactate elevations have also been associated with many of the long-term complications in GSD. A portable finger-stick blood lactate meter has recently been marketed as a training tool for high-performance athletes, but it has not been tested as a clinical diagnostic tool. This study was performed to assess the accuracy of the portable lactate meter in subjects with GSD I who are predisposed to high lactate concentrations. A total of 166 intravenous and 39 capillary samples from 13 subjects were tested concomitantly on three different lactate meters. The meter readings were compared with the lactate concentration determined by the laboratory gold-standard enzymatic colorimetric assay. Almost no inter-meter variability was found. The lactate meter values had outstanding correlation with the laboratory lactate determination, although the meters were found to run 0.5 mmol/L higher than the laboratory assay. The meter deviation was independent of lactate concentration. More variability was noted with finger-stick capillary lactate determinations, but monitoring of trends with capillary samples should prove valuable as a method for determining long-term control or acute deterioration. The portable lactate meter is a highly accurate tool for monitoring lactate concentrations, and should prove valuable for monitoring metabolic control in patients with GSD type I and other disorders associated with hyperlactataemia.

Adeno-associated virus-mediated correction of a canine model of glycogen storage disease type Ia.

Glycogen storage disease type Ia (GSDIa; von Gierke disease; MIM 232200) is caused by a deficiency in glucose-6-phosphatase-alpha. Patients with GSDIa are unable to maintain glucose homeostasis and suffer from severe hypoglycemia, hepatomegaly, hyperlipidemia, hyperuricemia, and lactic acidosis. The canine model of GSDIa is naturally occurring and recapitulates almost all aspects of the human form of disease. We investigated the potential of recombinant adeno-associated virus (rAAV) vector-based therapy to treat the canine model of GSDIa. After delivery of a therapeutic rAAV2/8 vector to a 1-day-old GSDIa dog, improvement was noted as early as 2 weeks posttreatment. Correction was transient, however, and by 2 months posttreatment the rAAV2/8-treated dog could no longer sustain normal blood glucose levels after 1 hr of fasting. The same animal was then dosed with a therapeutic rAAV2/1 vector delivered via the portal vein. Two months after rAAV2/1 dosing, both blood glucose and lactate levels were normal at 4 hr postfasting. With more prolonged fasting, the dog still maintained near-normal glucose concentrations, but lactate levels were elevated by 9 hr, indicating that partial correction was achieved. Dietary glucose supplementation was discontinued starting 1 month after rAAV2/1 delivery and the dog continues to thrive with minimal laboratory abnormalities at 23 months of age (18 months after rAAV2/1 treatment). These results demonstrate that delivery of rAAV vectors can mediate significant correction of the GSDIa phenotype and that gene transfer may be a promising alternative therapy for this disease and other genetic diseases of the liver.

Psychosocial Functioning in Youth with Glycogen Storage Disease Type I

OBJECTIVE To assess the quality of life and psychosocial functioning among pediatric patients with Glycogen Storage Disease (GSD) types Ia and Ib. METHODS Thirty-one youth with GSD types Ia and Ib and 42 healthy controls participated. Quality of life ratings from the GSD types Ia and Ib sample were compared with a previously reported clinical comparison sample. Children completed measures of quality of life, loneliness, family functioning, and sibling relationship quality (e.g., warmth, conflict). Parents completed measures of parental distress, parenting stress, child adaptive behavior, and child emotional and behavioral functioning. RESULTS Quality of life was generally lower in youth with GSD relative to healthy controls but similar to those with a chronic illness. Children with GSD were rated as having more internalizing symptoms, social problems, and lower independent functioning relative to healthy controls. Parents reported greater distress and parenting stress relative to healthy controls. CONCLUSIONS The presence of GSD types Ia and Ib are associated with reduced quality of life and independent functioning, and elevated levels of internalizing distress and parental stress relative to healthy peers. Relative to their children, parents generally reported that their child was more impaired, which suggests the need for multiple informants during assessment and active parental involvement during psychological treatment. These points should be kept in mind when assessing and treating youth with this disease and their families as psychological interventions that target areas of concern (e.g., adherence, coping with having a chronic disease) may be helpful for improving child and family outcomes.

Hyperlipidemia in glycogen storage disease type III: Effect of age and metabolic control

SummaryWhile the presence of hyperlipidaemia in glycogen storage disease (GSD) type Ia and Ib is generally accepted, few investigators have adequately assessed lipid profiles of GSD III in children, in whom the presence of hyperlipidaemia may be most prominent. We analysed the lipid profiles in 44 GSD III patients from 6 months to 30 years of age. Hypertriglyceridaemia and hypercholesterolaemia were common in children younger than 3 years of age. Hypertriglyceridaemia correlated negatively with age, and may reflect increased severity of hypoglycaemia in this younger population. The presence of hyperlipidaemia during childhood in these patients identifies another GSD population that could be at risk for early cardiovascular disease (CVD). Consequently, the outcome of clinical trials investigating the vascular effect of hyperlipidaemia in GSD applies to types other than GSD I.

Reference values of nocturnal oxygenation for use in outpatient oxygen weaning protocols in premature infants

To define reference ranges for oxygen saturation (SpO2) values in healthy full‐term infants in the first days of life and in preterm infants off supplemental oxygen as they approach neonatal intensive care unit (NICU) discharge.

Glycogen storage disease type Ia in canines: a model for human metabolic and genetic liver disease.

A canine model of Glycogen storage disease type Ia (GSDIa) is described. Affected dogs are homozygous for a previously described M121I mutation resulting in a deficiency of glucose-6-phosphatase-α. Metabolic, clinicopathologic, pathologic, and clinical manifestations of GSDIa observed in this model are described and compared to those observed in humans. The canine model shows more complete recapitulation of the clinical manifestations seen in humans including “lactic acidosis”, larger size, and longer lifespan compared to other animal models. Use of this model in preclinical trials of gene therapy is described and briefly compared to the murine model. Although the canine model offers a number of advantages for evaluating potential therapies for GSDIa, there are also some significant challenges involved in its use. Despite these challenges, the canine model of GSDIa should continue to provide valuable information about the potential for generating curative therapies for GSDIa as well as other genetic hepatic diseases.