Mouse hypothalamic GT1-7 cells demonstrate AMPK-dependent intrinsic glucose-sensing behaviour.

AIMS/HYPOTHESIS: Hypothalamic glucose-excited (GE) neurons contribute to whole-body glucose homeostasis and participate in the detection of hypoglycaemia. This system appears defective in type 1 diabetes, in which hypoglycaemia commonly occurs. Unfortunately, it is at present unclear which molecular components required for glucose sensing are produced in individual neurons and how these are functionally linked. We used the GT1-7 mouse hypothalamic cell line to address these issues. METHODS: Electrophysiological recordings, coupled with measurements of gene expression and protein levels and activity, were made from unmodified GT1-7 cells and cells in which AMP-activated protein kinase (AMPK) catalytic subunit gene expression and activity were reduced. RESULTS: Hypothalamic GT1-7 neurons express the genes encoding glucokinase and ATP-sensitive K(+) channel (K(ATP)) subunits K ( ir ) 6.2 and Sur1 and exhibit GE-type glucose-sensing behaviour. Lowered extracellular glucose concentration hyperpolarised the cells in a concentration-dependent manner, an outcome that was reversed by tolbutamide. Inhibition of glucose uptake or metabolism hyperpolarised cells, showing that energy metabolism is required to maintain their resting membrane potential. Short hairpin (sh)RNA directed to Ampkα2 (also known as Prkaa2) reduced GT1-7 cell AMPKα2, but not AMPKα1, activity and lowered the threshold for hypoglycaemia-induced hyperpolarisation. shAmpkα1 (also known as Prkaa1) had no effect on glucose-sensing or AMPKα2 activity. Decreased uncoupling protein 2 (Ucp2) mRNA was detected in AMPKα2-reduced cells, suggesting that AMPKα2 regulates UCP2 levels. CONCLUSIONS/INTERPRETATION: We have demonstrated that GT1-7 cells closely mimic GE neuron glucose-sensing behaviour, and reducing AMPKα2 blunts their responsiveness to hypoglycaemic challenge, possibly by altering UCP2 activity. These results show that suppression of AMPKα2 activity inhibits normal glucose-sensing behaviour and may contribute to defective detection of hypoglycaemia.

To see or not to see?...that is the question. An analysis of out-patient follow-up arrangements and non-attendance in a community paediatric population.

OBJECTIVE: To investigate the relationship between the number of outpatient appointments made; the distance traveled to attend these and the proportion of these appointments missed. DESIGN: Retrospective Cohort Study. SETTING: Community Paediatrics. PARTICIPANTS: Eighteen pre-school children on the Special Needs Register. RESULTS: With an increase in the number of appointments made and the distances involved in attending these, the number of missed appointments tends to increase. CONCLUSIONS: We need to educate parents as to the importance of follow-up, include families in decision making about appointments and rationalize the number of appointments made.

Calpain inhibition and insulin action in cultured human muscle cells.

Variation in the calpain 10 gene has been reported to increase susceptibility to type 2 diabetes. Part of this susceptibility appears to be mediated by a decrease in whole body insulin sensitivity. As skeletal muscle is the primary tissue site of the peripheral insulin resistance in type 2 diabetes, the aim of this study was to use a human skeletal muscle cell culture system to explore the effects of calpain inhibition on insulin action. Calpain 10 mRNA and protein expression was examined in cultured myoblasts, myotubes, and whole skeletal muscle from non-diabetic subjects using RT-PCR and Western blotting. Changes in insulin-stimulated glucose uptake and glycogen synthesis in response to the calpain inhibitors ALLN and ALLM were measured. Calpain 10 expression was confirmed in cultured human myoblasts, myotubes, and native skeletal muscle. Insulin-stimulated glucose uptake was significantly decreased following preincubation with ALLN [404+/-40 vs 505+/-55 (mean+/-SEM)pmol/mg/min; with vs without ALLN: p = 0.04] and ALLM [455+/-38 vs 550+/-50 pmol/mg/min; with vs without ALLM: p = 0.025] in day 7 fused myotubes, but not in myoblasts. Neither ALLN nor ALLM affected insulin-stimulated glycogen synthesis in myoblasts or myotubes. These studies confirm calpain 10 expression in cultured human muscle cells and support a role for calpains in insulin-stimulated glucose uptake in human skeletal muscle cells that may be relevant to the pathogenesis of the peripheral insulin resistance in type 2 diabetes.

Latino child health: need for inclusion in the US national discourse.

The "rediscovery" of poverty, as echoed in concepts of social inequality, has contributed to the goal of eliminating racial/ethnic and social class disparities in the United States. This commentary focuses on what we know about the pressing health care needs and issues relevant to Latino children and families and how extant knowledge can be linked to priority policy recommendations to ensure the inclusion of Latino health issues in the national discourse. A systematic review of the literature on Latino children and of expert opinion revealed 4 evidence-based themes focused on poverty: economic factors, family and community resources, health system factors, and pitfalls in Latino subgroup data collection. Consensus was found on 4 priority policy recommendations: (1) reduce poverty and increase access to health care coverage, (2) increase funding in targeted primary and preventive health care services, (3) provide funds needed to fully implement relevant health legislation, and (4) improve measurement and quality of data collection. If these recommendations are not instituted, the goals of Healthy People 2010 will not be achieved for the Latino population.

Keratosis follicularis spinulosa decalvans: confirmation of linkage to Xp22.13-p22.2.

Keratosis follicularis spinulosa decalvans (KFSD) is a rare, X linked disorder with skin and eye involvement (MIM 308800). We have studied a large British family with KFSD using polymorphic markers from Xp21-p23 and obtained a lod score of 2.056 at theta=0 with markers proximal and distal to the KFSD candidate region Xp22.13-p22.2 identified by Oosterwijk et al. Our data confirm the linkage to Xp22.13-p22.2 observed in the previously reported Dutch family, but fail to narrow the candidate interval for the KFSD locus.

Intelligence and development in Aarskog syndrome.

AIM: To test the hypothesis that overall intelligence quotient (IQ) is decreased in patients with Aarskog syndrome. METHODS: 21 boys under 17 years of age with a confirmed clinical diagnosis of Aarskog syndrome were assessed using the Griffiths mental development scales and the British ability scales. RESULTS: IQ ranged from 68 to 128 and followed a normal distribution. CONCLUSION: This study does not support the hypothesis that Aarskog syndrome is associated with a lowering of mean IQ.

Isolation and characterization of the faciogenital dysplasia (Aarskog-Scott syndrome) gene: a putative Rho/Rac guanine nucleotide exchange factor.

Faciogenital dysplasia (FGDY), also known as Aarskog-Scott syndrome, is an X-linked developmental disorder characterized by disproportionately short stature and by facial, skeletal, and urogenital anomalies. Molecular genetic analyses mapped FGDY to chromosome Xp11.21. To clone this gene, YAC clones spanning an FGDY-specific translocation breakpoint were isolated. An isolated cDNA, FGD1, is disrupted by the breakpoint, and FGD1 mutations cosegregate with the disease. FGD1 codes for a 961 amino acid protein that has strong homology to Rho/Rac guanine nucleotide exchange factors (GEFs), contains a cysteine-rich zinc finger-like region, and, like the RasGEF mSos, contains two potential SH3-binding sites. These results provide compelling evidence that FGD1 is responsible for FGDY and suggest that FGD1 is a Rho/RacGEF involved in mammalian development.

Alpha thalassaemia mental retardation (ATR-X): an atypical family.

A novel form of severe, X linked mental retardation associated with alpha thalassaemia (ATR-X syndrome) has recently been described. Two affected cousins are described, one of whom has an unusually mild haematological phenotype. HbH inclusions, which are the hallmark of this disease, were only detected in the peripheral red blood cells after repeated observations.