Prevention of complications in glycogen storage disease type Ia with optimization of metabolic control.

Prior to 1971, type Ia glycogen storage disease was marked by life-threatening hypoglycemia, lactic acidosis, severe failure to thrive, and developmental delay. With the introduction of continuous feeds in the 1970s and cornstarch in the 1980s, the prognosis improved, but complications almost universally developed. Changes in the management of type Ia glycogen storage disease have resulted in improved metabolic control, and this manuscript reviews the increasing evidence that complications can be delayed or prevented with optimal metabolic control as previously was seen in diabetes.

Identification of imidazo[1,2-b]pyridazine TYK2 pseudokinase ligands as potent and selective allosteric inhibitors of TYK2 signalling.

As a member of the Janus (JAK) family of non-receptor tyrosine kinases, TYK2 mediates the signaling of pro-inflammatory cytokines including IL-12, IL-23 and type 1 interferon (IFN), and therefore represents an attractive potential target for treating the various immuno-inflammatory diseases in which these cytokines have been shown to play a role. Following up on our previous report that ligands to the pseudokinase domain (JH2) of TYK2 suppress cytokine-mediated receptor activation of the catalytic (JH1) domain, the imidazo[1,2-b]pyridazine (IZP) 7 was identified as a promising hit compound. Through iterative modification of each of the substituents of the IZP scaffold, the cellular potency was improved while maintaining selectivity over the JH1 domain. These studies led to the discovery of the JH2-selective TYK2 inhibitor 29, which provided encouraging systemic exposures after oral dosing in mice. Phosphodiesterase 4 (PDE4) was identified as an off-target and potential liability of the IZP ligands, and selectivity for TYK2 JH2 over this enzyme was obtained by elaborating along selectivity vectors determined from analyses of X-ray co-crystal structures of representative ligands of the IZP class bound to both proteins.

A new method for determining gastric acid output using a wireless pH-sensing capsule.

BACKGROUND: Gastro-oesophageal reflux disease (GERD) and gastric acid hypersecretion respond well to suppression of gastric acid secretion. However, clinical management and research in diseases of acid secretion have been hindered by the lack of a non-invasive, accurate and reproducible tool to measure gastric acid output (GAO). Thus, symptoms or, in refractory cases, invasive testing may guide acid suppression therapy. AIM: To present and validate a novel, non-invasive method of GAO analysis in healthy subjects using a wireless pH sensor, SmartPill (SP) (SmartPill Corporation, Buffalo, NY, USA). METHODS: Twenty healthy subjects underwent conventional GAO studies with a nasogastric tube. Variables impacting liquid meal-stimulated GAO analysis were assessed by modelling and in vitro verification. Buffering capacity of Ensure Plus was empirically determined. SP GAO was calculated using the rate of acidification of the Ensure Plus meal. Gastric emptying scintigraphy and GAO studies with radiolabelled Ensure Plus and SP assessed emptying time, acidification rate and mixing. Twelve subjects had a second SP GAO study to assess reproducibility. RESULTS: Meal-stimulated SP GAO analysis was dependent on acid secretion rate and meal-buffering capacity, but not on gastric emptying time. On repeated studies, SP GAO strongly correlated with conventional basal acid output (BAO) (r = 0.51, P = 0.02), maximal acid output (MAO) (r = 0.72, P = 0.0004) and peak acid output (PAO) (r = 0.60, P = 0.006). The SP sampled the stomach well during meal acidification. CONCLUSIONS: SP GAO analysis is a non-invasive, accurate and reproducible method for the quantitative measurement of GAO in healthy subjects. SP GAO analysis could facilitate research and clinical management of GERD and other disorders of gastric acid secretion.

Long-acting insulin analogues elicit atypical signalling events mediated by the insulin receptor and insulin-like growth factor-I receptor.

AIMS/HYPOTHESIS: Insulin analogues were developed to improve the pharmacological properties of injected insulin and to better mimic endogenous insulin output. However, certain insulin analogues have been suggested to display IGF-I-like biological activities. Furthermore, several recent epidemiological studies have suggested a potential increase in cancer risk for treatment of diabetes patients with long-acting analogue insulin glargine (A21Gly,B31Arg,B32Arg human insulin). Additional studies, however, reported no increased cancer risk. The purpose of the present study was to identify the receptor(s) and signal transduction pathways responsible for the biological actions of insulin glargine and insulin detemir (B29Lys[ε-tetradecanoyl],desB30 human insulin). METHODS: The colon cancer-derived cell line HCT116 was treated with increasing doses of insulin glargine, insulin detemir, regular insulin or IGF-I, and receptor activation was evaluated by immunoprecipitation assays. IGF-I receptor (IGF-IR) internalisation following insulin glargine treatment was assessed by confocal microscopy. Activation of the Akt and extracellular signal-regulated kinase pathways was evaluated by western blots. The anti-apoptotic effect of the analogues was measured by poly-(ADP ribose) polymerase antibody and annexin assays. RESULTS: We found evidence for dual activation of the insulin receptor and IGF-IR by the analogues. Dose-dependency experiments showed that insulin glargine was able to phosphorylate the IGF-IR at fivefold lower doses than those required to activate the insulin receptor. We also showed that insulin glargine can lead to prolonged activation of the receptors and therefore promote abnormal signalling. Confocal imaging experiments showed that insulin glargine, but not regular insulin induced IGF-IR internalisation similarly to IGF-I. Finally, both analogues displayed IGF-I-like anti-apoptotic activities and stimulated cell cycle progression. CONCLUSIONS/INTERPRETATION: Our data indicate that insulin glargine and insulin detemir display atypical signalling activities that differ from those elicited by regular insulin and involve activation of the anti-apoptotic IGF-IR.

Reversal of glycogen storage disease type IIIa-related cardiomyopathy with modification of diet.

Glycogen storage disease type III (GSD III) is caused by a deficiency in debranching enzyme, which leads to an accumulation of abnormal glycogen called limit dextrin in affected tissues. Muscle and liver involvement is present in GSD type IIIa, while the defect is limited to the liver only in GSD type IIIb. Besides skeletal muscle involvement, a cardiomyopathy resembling idiopathic hypertrophic cardiomyopathy is seen. Management consists of maintaining normoglycaemia by supplementation with cornstarch therapy and/or protein. While studies are lacking regarding the best treatment for skeletal muscle disease, a high-protein diet was previously reported to be beneficial. No cases of improvement in cardiomyopathy have been reported. Our patient presented in infancy with hypoglycaemia and hepatomegaly. His prescribed management consisted of cornstarch supplementation and a high-protein diet providing 20% of his total energy needs. At 16 years of age, he developed a severe cardiomyopathy with a left ventricular mass index of 209 g/m(2). The cardiomyopathy remained stable on a protein intake of 20-25% of total energy. At age 22 years, the diet was changed to increase his protein intake to 30% of total energy and minimize his cornstarch therapy to only what was required to maintain normoglycaemia. Dramatic improvement in the cardiomyopathy occurred. Over one year, his left ventricular mass index decreased from 159.7 g/m(2) to 78 g/m(2) (normal 50-86 g/m(2)) and the creatine kinase levels decreased from 455 U/L to 282 U/L. Avoidance of overtreatment with carbohydrate and a high-protein diet can reverse and may prevent cardiomyopathy.

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

While 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.

Adalimumab for the treatment of Crohn-like colitis and enteritis in glycogen storage disease type Ib.

Glycogen storage disease (GSD) type Ib is a congenital disorder of glycogen metabolism that is associated with neutropenia, neutrophil dysfunction, and an inflammatory bowel disease that mimics a Crohn phenotype. Gastrointestinal inflammation in GSD Ib has been successfully treated with 5-aminosalicylic acid and granulocyte colony-stimulating factor (G-CSF). However, therapeutic options for patients not responding to traditional therapies have been limited owing to untoward effects of glucocorticoids and immunomodulators in this metabolic disorder. Adalimumab is a monoclonal antibody targeting tumour necrosis factor-α that has shown promise for the treatment of patients with Crohn disease. Due to the limited options for treating GSD-associated inflammatory bowel disease, use of adalimumab was attempted in a case unresponsive to aminosalicylate, G-CSF, and antibiotic therapy. Significant clinical and histological improvement was observed in our patient, and the medication was well tolerated.

Quantitative comparison of functional MRI and direct electrocortical stimulation for functional mapping.

BACKGROUND: Mapping functional areas of the brain is important for planning tumour resections. With the increased use of functional magnetic resonance imaging (fMRI) for presurgical planning, there is a need to validate that fMRI activation mapping is consistent with the mapping obtained during surgery using direct electrocortical stimulation (DECS). METHODS: A quantitative comparison of DECS and fMRI mapping techniques was performed, using a patient-specific conductivity model to find the current distribution resulting from each stimulation site. The resulting DECS stimulation map was compared to the fMRI activation map, using the maximal Dice similarity coefficient (MDSC). RESULTS: Our results show some agreement between these two mapping techniques--the stimulation site with the largest MOSC was the only site that demonstrated intra-operative effect. CONCLUSIONS: There is a substantial effort to improve the techniques used to map functional areas, particularly using fMRI. It seems likely that fMRI will eventually provide a valid non-invasive means for functional mapping.

Assessing glomerular filtration rate by estimation equations in kidney transplant recipients.

Surveillance of glomerular filtration rate (GFR) is crucial in the management of kidney transplant recipients. With special emphasis on serum creatinine (SCr) calibration assay, we assessed the performance of estimation equations as compared to iothalamate GFR (iGFR) in 209 patients using the modification of diet in renal disease (MDRD), Nankivell and Cockcroft-Gault methods. Fifty-five percent of patients were treated with a calcineurin inhibitor (CNI) and all were taken trimethroprim-sulfametoxazole at the time of SCr measurement. The mean iGFR was 44 +/- 26 mL/min/1.73 m2. The MDRD equation showed a median difference of 0.9 mL/min/1.73 m2 with 53% of estimated GFR within 20% of iGFR. Median differences were 7.5 and 7.0 mL/min/1.73 m2 for Nankivell and Cockcroft-Gault formulas, respectively. The accuracy of the Nankivell and Cockcroft-Gault formulas was such that only 38% and 37% of estimations, respectively, fell within 20% of iGFR. The performance of all equations was not uniform throughout the whole range of GFR, with some deterioration at the extremes of GFR levels. In addition, good performance of the MDRD equation was seen in subjects taking CNI. In conclusion, the overall performance of the MDRD equation was superior to the Nankivell and Cockcroft-Gault formulas in renal transplant recipients including subjects treated with CNI.

Influence of tissue conductivity anisotropy on EEG/MEG field and return current computation in a realistic head model: a simulation and visualization study using high-resolution finite element modeling.

To achieve a deeper understanding of the brain, scientists, and clinicians use electroencephalography (EEG) and magnetoencephalography (MEG) inverse methods to reconstruct sources in the cortical sheet of the human brain. The influence of structural and electrical anisotropy in both the skull and the white matter on the EEG and MEG source reconstruction is not well understood. In this paper, we report on a study of the sensitivity to tissue anisotropy of the EEG/MEG forward problem for deep and superficial neocortical sources with differing orientation components in an anatomically accurate model of the human head. The goal of the study was to gain insight into the effect of anisotropy of skull and white matter conductivity through the visualization of field distributions, isopotential surfaces, and return current flow and through statistical error measures. One implicit premise of the study is that factors that affect the accuracy of the forward solution will have at least as strong an influence over solutions to the associated inverse problem. Major findings of the study include (1) anisotropic white matter conductivity causes return currents to flow in directions parallel to the white matter fiber tracts; (2) skull anisotropy has a smearing effect on the forward potential computation; and (3) the deeper a source lies and the more it is surrounded by anisotropic tissue, the larger the influence of this anisotropy on the resulting electric and magnetic fields. Therefore, for the EEG, the presence of tissue anisotropy both for the skull and white matter compartment substantially compromises the forward potential computation and as a consequence, the inverse source reconstruction. In contrast, for the MEG, only the anisotropy of the white matter compartment has a significant effect. Finally, return currents with high amplitudes were found in the highly conducting cerebrospinal fluid compartment, underscoring the need for accurate modeling of this space.

Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb.

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.

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

High 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.

Extracorporeal ultrafiltration for acute exacerbations of chronic heart failure: report from the Acute Dialysis Quality Initiative.

This report from a work group affiliated with the Acute Dialysis Quality Initiative is a critical assessment of the use of extracorporeal ultrafiltration (UF) in the management of acutely decompensated heart failure (HF). In addition to assessing UF in this setting, the report also provides background information on HF, including classification, pathophysiology, and the importance of concomitant renal failure. A summary of important results from clinical trials in this area is provided, along with a discussion of technical considerations. Finally, specific recommendations for future clinical evaluations are given.

Hepatocellular carcinoma in glycogen storage disease type Ia: a case series.

We present a series of 8 patients (6 males, 2 females) with hepatocellular carcinoma (HCC) and glycogen storage disease type Ia (GSD Ia). In this group, the age at which treatment was initiated ranged from birth to 39 years (mean 9.9 years). All patients but one were noncompliant with treatment. Hepatic masses were first detected at an age range of 13-45 years (mean 28.1 years). Age at diagnosis of HCC ranged from 19 to 49 years (mean 36.9 years). Duration between the diagnosis of liver adenomas and the diagnosis of HCC ranged from 0 to 28 years (mean 8.8 years, SD = 11.5). Two patients had positive hepatitis serologies (one hepatitis B, one hepatitis C). Alpha-fetoprotein (AFP) was normal in 6 of the 8 patients. Carcinoembryonic antigen (CEA) was normal in the 5 patients in which it was measured. Current guidelines recommend abdominal ultrasonography with AFP and CEA levels every 3 months once patients develop hepatic lesions. Abdominal CT or MRI is advised when the lesions are large or poorly defined or are growing larger. We question the reliability of AFP and CEA as markers for HCC in GSD Ia. Aggressive interventional management of masses with rapid growth or poorly defined margins may be necessary to prevent the development of HCC in this patient population.

Clocking femtosecond X rays.

Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

Atomic-scale visualization of inertial dynamics.

The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

A role for schwann cells in the neuroregenerative effects of a non-immunosuppressive fk506 derivative, jnj460.

UNLABELLED: FK506 and its non-immunosuppressive derivatives represent a class of pharmacological agents referred to as immunophilin ligands that have been reported to promote neuroregeneration and survival in several experimental models; however their cellular and molecular mechanisms of action have not been well established. Here we characterize a new immunophilin ligand that interacts with both FK506 binding protein 12 (FKBP12) and FKBP52, and demonstrate that JNJ460 induces neurite outgrowth from freshly explanted dorsal root ganglia (DRG) in a Schwann cell-dependent manner. Purified cultures of neurons fail to respond to these drugs, but cultures containing Schwann cells and neurons respond with neurite outgrowth, as do neurons grown in conditioned medium from JNJ460-treated Schwann cells. Using microarray analysis and a transcription reporter assay, we show that JNJ460 induces a series of transcriptional changes that occur in a temporal cascade. Among the Schwann cell-expressed genes upregulated following JNJ460 treatment is the POU transcription factor SCIP, which has been shown to regulate Schwann cell gene transcription and differentiation. JNJ460 potentiated transforming growth factor beta (TGF-beta)-induced transcriptional activation and SCIP induction in Schwann cells, by altering the interaction between FKBP12 and the TGF-beta type I receptor, TbetaR1. Finally, to test whether JNJ460 enhances neurite regeneration in vivo, we treated animals with JNJ460 for 30 days following mechanical transection of the sciatic nerve and demonstrated myelin and axonal hypertrophy at the ultrastructural level. Collectively, these data suggest that Schwann cells play an important role in the biological effects of immunophilin ligands by affecting neuron-glial signaling during regeneration. SUMMARY: The cellular and molecular mechanisms responsible for the regenerative effects of immunophilin ligands are not well understood. Here we show that the neuritogenic effects of JNJ460 in a DRG model depend on interactions between neurons and Schwann cells. Treatment of purified Schwann cells with JNJ460 alters Schwann cell gene expression, and promotes the generation of factors that act on neurons. These data indicate that Schwann cells play an important role in the actions of immunophilin ligands.

A software framework for solving problems of bioelectricity applying high-order finite elements.

Electrical activity in biological media can be described in a mathematical way, which is applicable to computer-based simulation. Biophysically mathematical descriptions provide important insights into the electrical and electrophysiological properties of cells, tissues, and organs. Examples of these descriptions are Maxwell's and Poisson's equations for electromagnetic and electric fields. Commonly, numerical techniques are applied to calculate electrical fields, e.g. the finite element method. Finite elements can be classified on the order of the underlying Interpolation. High-order finite elements provide enhanced geometric flexibility and can increase the accuracy of a solution. The aim of this work is the design of a framework for describing and solving high-order finite elements in the SCIRun/BioPSE software system, which allows geometric modeling, simulation, and visualization for solving bioelectric field problems. Currently, only low-order elements are supported. Our design for high-order elements concerns interpolation of geometry and physical fields. The design is illustrated by an implementation of one-dimensional elements with cubic interpolation of geometry and field variables.

Acute and chronic effects of methamphetamine on tele-methylhistamine levels in mouse brain: selective involvement of the D(2) and not D(3) receptor.

We have explored the role of endogenous dopamine in the control of histaminergic neuron activity in mouse brain regions evaluated by changes in tele-methylhistamine (t-MeHA) levels. In vitro, methamphetamine released [(3)H]noradrenaline but failed to release [(3)H]histamine from synaptosomes. In vivo, methamphetamine enhanced t-MeHA levels by about 2-fold with ED(50) values of approximately 1 mg/kg in caudate putamen, nucleus accumbens, cerebral cortex, and hypothalamus. This response selectively involved the D(2) and not the D(3) receptor as indicated by its blockade by haloperidol and by its persistence after administration of nafadotride, a D(3) receptor preferential ligand, or in (-/-) D(3) receptor-deficient mice. The t-MeHA response to methamphetamine was delayed compared with the locomotor-activating effect of this drug, suggesting that it is of compensatory nature. In agreement, ciproxifan, an inverse agonist known to enhance histamine neuron activity, decreased the hyperlocomotion induced by methamphetamine. Repeated methamphetamine administration resulted in the expected sensitization to the hyperlocomotor effect of the drug but did not modify either the ED(50) or the E(max) regarding t-MeHA levels. However, it resulted in an enhanced basal t-MeHA level (+30-40%), which was sustained for at least 11 days after withdrawal in hypothalamus, striatum, and cerebral cortex and suppressed by haloperidol. Hence, both the acute and chronic administration of methamphetamine enhance histamine neuron activity, presumably in a compensatory manner. Repeated methamphetamine administration also resulted in a modified balance in the opposite influences of dopamine and serotonin on histaminergic neurons as revealed by the enhanced response to haloperidol and abolished response to ketanserin, respectively.