Association and linkage of alpha-2A adrenergic receptor gene polymorphisms with childhood ADHD

Attention-deficit hyperactivity disorder (ADHD) is a heritable disorder, prevalent from childhood through adulthood. Although the noradrenergic (NA) system is thought to mediate a portion of the pathophysiology of ADHD, genes in this pathway have not been investigated as frequently as those in the dopaminergic system. Previous association studies of one candidate gene in the NA system, ADRA2A, showed inconsistent results with regard to an MspI polymorphism. In the current study, two nearby single-nucleotide polymorphisms, which define HhaI and DraI restriction fragment length polymorphisms, were also genotyped and were in significant linkage disequilibrium with the MspI RFLP. Transmission disequilibrium tests (TDTs) in a sample of 177 nuclear families showed significant association and linkage of the DraI polymorphism with the ADHD combined subtype (P=0.03), and the quantitative TDT showed association of this polymorphism with the inattentive (P=0.003) and hyperactive-impulsive (P=0.015) symptom dimensions. The haplotype that contained the less common allele of the DraI polymorphism likewise showed a strong relationship with the inattentive (P=0.001) and hyperactive-impulsive (P=0.004) symptom dimensions. This study supports the hypothesis that an allele of the ADRA2A gene is associated and linked with the ADHD combined subtype and suggests that the DraI polymorphism of ADRA2A is linked to a causative polymorphism.

Efficacy of subcutaneous insulin lispro versus continuous intravenous regular insulin for the treatment of patients with diabetic ketoacidosis

PURPOSE

To compare the efficacy and safety of subcutaneous insulin lispro with that of a standard low-dose intravenous infusion protocol of regular insulin in patients with uncomplicated diabetic ketoacidosis.

METHODS

In this prospective, randomized open trial, 20 patients treated with subcutaneous insulin lispro were managed in regular medicine wards (n=10) or an intermediate care unit (n=10), while 20 patients treated with the intravenous protocol were managed in the intensive care unit. Patients treated with subcutaneous lispro received an initial injection of 0.3 unit/kg followed by 0.1 unit/kg/h until correction of hyperglycemia (blood glucose levels <250 mg/dL), followed by 0.05 to 0.1 unit/kg/h until resolution of diabetic ketoacidosis (pH > or =7.3, bicarbonate > or =18 mEq/L). Patients treated with intravenous regular insulin received an initial bolus of 0.1 unit/kg, followed by an infusion of 0.1 unit/kg/h until correction of hyperglycemia, then 0.05 to 0.1 unit/kg/h until resolution of diabetic ketoacidosis.

RESULTS

Mean (+/- SD) admission biochemical parameters in patients treated with subcutaneous lispro (glucose: 674 +/- 154 mg/dL; bicarbonate: 9.2 +/- 4 mEq/L; pH: 7.17 +/- 0.10) were similar to values in patients treated with intravenous insulin (glucose: 611 +/- 264 mg/dL; bicarbonate: 10.6 +/- 4 mEq/L; pH: 7.19 +/- 0.08). The duration of treatment until correction of hyperglycemia (7 +/- 3 hours vs. 7 +/- 2 hours) and resolution of ketoacidosis (10 +/- 3 hours vs. 11 +/- 4 hours) in patients treated with subcutaneous lispro was not different than in patients treated with intravenous regular insulin. There were no deaths in either group, and there were no differences in the length of hospital stay, amount of insulin until resolution of diabetic ketoacidosis, or in the rate of hypoglycemia between treatment groups. Treatment of diabetic ketoacidosis in the intensive care unit was associated with 39% higher hospitalization charges than was treatment with subcutaneous lispro in a non-intensive care setting ($14,429 +/- $5243 vs. $8801 +/- $5549, P <0.01).

CONCLUSION

Treatment of adult patients who have uncomplicated diabetic ketoacidosis with subcutaneous lispro every hour in a non-intensive care setting may be safe and more cost-effective than treatment with intravenous regular insulin in the intensive care unit.

Dichloroacetate exerts therapeutic effects in transgenic mouse models of Huntington's disease

Dichloroacetate (DCA) stimulates pyruvate dehydrogenase complex (PDHC) activity and lowers cerebral lactate concentrations. In the R6/2 and N171-82Q transgenic mouse models of Huntington's disease (HD), DCA significantly increased survival, improved motor function, delayed loss of body weight, attenuated the development of striatal neuron atrophy, and prevented diabetes. The percentage of PDHC in the active form was significantly reduced in R6/2 mice at 12 weeks of age, and DCA ameliorated the deficit. These results provide further evidence for a role of energy dysfunction in HD pathogenesis and suggest that DCA may exert therapeutic benefits in HD.

Autosomal dominant craniometaphyseal dysplasia is caused by mutations in the transmembrane protein ANK

Craniometaphyseal dysplasia (CMD) is a rare skeletal disorder characterized by progressive thickening and increased mineral density of craniofacial bones and abnormally developed metaphyses in long bones. Linkage studies mapped the locus for the autosomal dominant form of CMD to an approximately 5-cM interval on chromosome 5p, which is defined by recombinations between loci D5S810 and D5S1954. Mutational analysis of positional candidate genes was performed, and we describe herein three different mutations, in five different families and in isolated cases, in ANK, a multipass transmembrane protein involved in the transport of intracellular pyrophosphate into extracellular matrix. The mutations are two in-frame deletions and one in-frame insertion caused by a splicing defect. All mutations cluster within seven amino acids in one of the six possible cytosolic domains of ANK. These results suggest that the mutated protein has a dominant negative effect on the function of ANK, since reduced levels of pyrophosphate in bone matrix are known to increase mineralization.

Phosphoramidon-sensitive endothelin-converting enzymes modulate cerebral blood flow and neural damage of hypoxic rats

The enzymatic activity of endothelin-converting enzymes (ECE) was altered to determine the potential effect of endothelins (ET) on cerebral blood flow measured by laser Doppler flowmetry (CBF(LDF)) and the resultant neural damage of rats, made hypoxic via breathing 12% O(2) for 35 min. Intrastriatal administration of phosphoramidon (PRN, 5 microM), a dual inhibitor of ECE and neutral endopeptidase (NEP), significantly increased infarct volume to hypoxia with a significant attenuation of CBF(LDF). However, intrastriatal thiorphan (TRN, 5 microM), an inhibitor of NEP, had no effect on the CBF(LDF) responses or infarct volume induced by the hypoxic challenge. These findings showed that inhibition of ECE by PRN interfered with the vasodilator activity of ET to the hypoxic response that increased neural damage, thus suggesting that PRN-sensitive ECE is functionally active in the modulation of cerebral blood flow in rats undergoing hypoxia.

Hypoxic modulation of striatal lesions induced by administration of endothelin-1

Levels of endothelin-1 (ET-1), a potent endogenous vasoconstrictor, are elevated in plasma and cerebrospinal fluid (CSF) following cerebral ischemia and reperfusion injury. The present study sought insight into the potential differential vasoactive effects on the cerebral vasculature and resultant neural damage of ET-1 during normoxic vs. ischemic conditions and upon reperfusion. Under normoxic conditions, intrastriatal stereotaxic injection of exogenous ET-1 (40 pmol) induced a significant (P<0.05) reduction (</=29+/-12%) in the regional (striatal) cerebral blood flow measured by Laser Doppler flowmetry (CBF(LDF)) for up to 40 min in halothane-anesthetized male Long-Evans rats. Intrastriatal injection of ET-1 10 min after the onset of hypoxia (12% O(2), balance N(2)) tended to blunt, but not significantly, the striatal CBF(LDF) responses to the 35 min period of hypoxia. ET-1 given during reoxygenation significantly (P<0.05) reduced striatal CBF(LDF), which was similar to the effect of ET-1 during normoxia. ET-1-induced infarction when administered prior to hypoxia, but not during or post-hypoxia, was significantly (P<0.05) exacerbated compared to infarction of ET-1 without hypoxia. These results suggest that exogenous ET-1 administered into the brain parenchyma can induce an infarction associated with modulation of CBF(LDF) during the normoxic or reoxygenation period, but not during the hypoxic period and that the increased release of ET-1 in any pathological phase of cerebral ischemia contributes to irreversible neural damage with associated hemodynamic disturbances.

Blood cocaine and metabolite concentrations, clinical findings, and outcome of patients presenting to an ED

The purpose was to determine if blood cocaine or metabolite concentrations would accurately reflect the severity of clinical findings in patients presenting to the emergency department, identifying those requiring therapeutic intervention or those at risk for poor outcome. Blood for determination of cocaine and metabolite concentrations was drawn from patients and were determined by an extractive alkylation/mass spectrometry procedure. The mean blood concentrations (mg/L) in 111 patients were as follows: cocaine, 0.26 +/- 0.5; ecgonine 0.42 +/- 0.47; ecgonine methyl ester 0.21 +/- 0.37, norcocaine 0.03 +/- 0.17; benzoylecgonine 1.28 +/- 1.29, cocaethylene 0.02 +/- 0.06. Two patients died, 23 required hospital admission, and 88 were discharged from the ED. There was no statistical correlation between cocaine or any metabolite concentration and the severity of clinical symptoms, disposition, need for treatment or outcome. Blood cocaine and metabolite concentrations should be interpreted with caution because they vary widely and do not predict the severity of clinical findings, the incidence of adverse effects, outcome, or need for interventional therapy.

Cocaine metabolism in hyperthermic patients with excited delirium

The half-life of cocaine in clinical experiments has been reported to range from 60 to 90 min. It has been previously suggested that elevated temperature may accelerate the metabolism of cocaine. However, there is no clinical data to indicate the presence of hyperthermia like that seen in excited delirium alters the half-life of cocaine. We report the results of half-life determinations from serial cocaine concentrations in two patients with excited delirium. Both patients presented to the emergency department with classic findings of excited delirium that included hyperthermia, agitation, and cardiovascular aberrations. One patient died despite aggressive therapeutic intervention. Cocaine and metabolite concentrations were determined by an extractive alkylation mass spectrometry procedure. Presenting cocaine concentrations in patient 1 and patient 2 were 0.387 and 0.266 mg/L respectively. Results from pharmacokinetic modeling of the serial concentrations show that the half-life of cocaine was not significantly accelerated, despite the presence of hyperthermia. Data from these two cases provide further evidence that catastrophic reactions to cocaine are independent of amount or route of administration, and that the metabolism of cocaine, at least in these patients, was not altered by hyperthermia.

Suppression of accelerated diabetic atherosclerosis by the soluble receptor for advanced glycation endproducts

Accelerated atherosclerosis in patients with diabetes is a major cause of their morbidity and mortality, and it is unresponsive to therapy aimed at restoring relative euglycemia. In hyperglycemia, nonenzymatic glycation and oxidation of proteins and lipids results in the accumulation of irreversibly formed advanced glycation endproducts. These advanced glycation endproducts engage their receptor in cells of the blood vessel wall, thereby activating mechanisms linked to the development of vascular lesions. We report here a model of accelerated and advanced atherosclerosis in diabetic mice deficient for apolipoprotein E. Treatment of these mice with the soluble extracellular domain of the receptor for advanced glycation endproducts completely suppressed diabetic atherosclerosis in a glycemia- and lipid-independent manner. These findings indicate interaction between the advanced glycation endproducts and their receptor is involved in the development of accelerated atherosclerosis in diabetes, and identify this receptor as a new therapeutic target in diabetic macrovascular disease.

Effect of an intravenous iron dextran regimen on iron stores, hemoglobin, and erythropoietin requirements in hemodialysis patients

Iron deficiency is a common cause of delayed or diminished response to erythropoietin (EPO) in hemodialysis patients. Although oral iron is often prescribed to replete iron stores, this approach to iron supplementation may not be adequate with chronic EPO therapy. Intravenous (IV) iron dextran may be an effective alternative approach to replete iron stores and may facilitate more cost-effective use of EPO. The purpose of this study was to evaluate an IV iron dextran regimen that consisted of a loading dose phase followed by monthly maintenance doses of iron dextran. The effect of this regimen on iron stores, hemoglobin, and EPO doses was evaluated. This was an open prospective study in adult hemodialysis patients who were iron deficient as defined by a serum ferritin less than 100 ng/mL or transferrin saturation (TSAT) of less than 20%. Patients were loaded with 1 g iron dextran in five divided doses and then received monthly maintenance doses of 100 mg for the 4-month study period. Values of serum ferritin, TSAT, hemoglobin, and EPO dose were followed for the 4-month study period. Thirty hemodialysis patients receiving EPO were identified as being iron deficient and were enrolled in the study. The mean serum ferritin increased significantly from 49 ng/mL at baseline to 225 ng/mL at the end of the study period (P < 0.0001). Mean TSAT also increased significantly from 27% to 33% (P = 0.002). Values for hemoglobin did not change significantly during the study period; however, there was a significant reduction in EPO dose from a mean baseline dose of 112 U/kg/wk to 88 U/kg/wk at the end of the study period (P = 0.009). Seventeen patients experienced an increase in hemoglobin or a decrease in EPO dose. Economic analysis showed that approximately $580 (Cdn) per patient per year could be saved by use of IV iron dextran. The administration of the IV iron dextran regimen in the iron-deficient hemodialysis population was effective at repleting and maintaining iron stores and reducing EPO use.

A poxvirus-encoded semaphorin induces cytokine production from monocytes and binds to a novel cellular semaphorin receptor, VESPR

The vaccinia virus A39R protein is a member of the semaphorin family. A39R.Fc protein was used to affinity purify an A39R receptor from a human B cell line. Tandem mass spectrometry of receptor peptides yielded partial amino acid sequences that allowed the identification of corresponding cDNA clones. Sequence analysis of this receptor indicated that it is a novel member of the plexin family and identified a semaphorin-like domain within this family, thus suggesting an evolutionary relationship between receptor and ligand. A39R up-regulated ICAM-1 on, and induced cytokine production from, human monocytes. These data, then, describe a receptor for an immunologically active semaphorin and suggest that it may serve as a prototype for other plexin-semaphorin binding pairs.

A standardized procedure for locating and documenting ECG chest electrode positions: consideration of the effect of breast tissue on ECG amplitudes in women

Continuing uncertainty exists about standardized procedures for the placement of electrocardiographic (ECG) chest electrodes, technical variability being the largest error source for short-term variations in amplitudes and waveforms of the chest lead ECGs. To avoid presumed attenuation of ECG amplitudes by abundant breast tissue, anterolateral chest electrodes in women are often placed under the breasts and too low. There is also considerable uncertainty about locating the midclavicular line and the V4 electrode, particularly in obese persons and in women. We examined the effect of breast tissue protuberance on ECG amplitudes using ECG and anthropometric data on 6,814 women included in the Atherosclerosis Research in Communities Study (ARIC). The R wave amplitudes in anterolateral chest leads and the Sokolow-Lyon voltage decreased (P < .001 for all), and RaVL and the Cornell voltage increased significantly with increasing breast protuberance (P < .001 for all). However, these effects were small (15 microV or less for each 1-cm increment in breast protuberance), and R2 values were less than .01, indicating that breast protuberance alone explained less than 1% of ECG amplitude variations. When chest size and breast protuberance estimates were entered simultaneously into a multivariate regression model, chest size appeared to dominate, and model R2 values increased for positive associations with RaVL (R2 = .12) and the Cornell voltage (R2 = .04). Combined model R2 values remained < or =.01 for all other ECG amplitudes. A detailed step-by-step standardized electrode placement procedure was formulated. Because of the difficulties encountered in locating the left midclavicular line by visual inspection, we introduced well-defined procedures for identification and documentation of lateral chest electrode placement locations as a quality control method for clinical trials. Population data from the Third National Health and Nutrition Survey on the distributions by sex and race of chest electrode V4 and V6 locations and anthropometric data on chest size and shape are presented in order to facilitate evaluation of the comparability of electrode placement procedures in various studies and for quality control in clinical trials. It is concluded that standardized procedures to document chest electrode placement locations are feasible. Breast tissue appears to have a practically negligible effect on ECG amplitudes, and in women, the placement of chest electrodes on the breast rather than under the breast is recommended in order to facilitate the precision of electrode placement at the correct horizontal level and at the correct lateral positions.

Poxvirus genomes encode a secreted, soluble protein that preferentially inhibits beta chemokine activity yet lacks sequence homology to known chemokine receptors

Poxvirus genomes encode several proteins which inhibit specific elements of the host immune response. We show the "35K" virulence gene in variola and cowpox viruses, whose vaccinia and Shope fibroma virus equivalents are strongly conserved in sequence, actually encodes a secreted soluble protein with high-affinity binding to virtually all known beta chemokines, but only weak or no affinity to the alpha and gamma classes. The viral protein completely inhibits the biological activity of monocyte chemotactic protein-1 (MCP-1) by competitive inhibition of chemokine binding to cellular receptors. As all beta chemokines are also shown to cross-compete with MCP1 binding to the viral protein, we conclude that this viral chemokine inhibitor (vCCI) not only interacts through a common binding site, but is likely a potent general inhibitor of beta chemokine activity. Unlike many poxvirus virulence genes to date, which are clearly altered forms of acquired cellular genes of the vertebrate immune system, this viral chemokine inhibitor (vCCI) shares no sequence homology with known proteins, including known cellular chemokine receptors, all of which are multiple membrane-spanning proteins. Thus, vCCI presumably has no cellular analogue and instead may be the product of unrelenting sequence variations which gave rise to a completely new protein with similar binding properties to native chemokine receptors. The proposed function of vCCI is inhibition of the proinflammatory (antiviral) activities of beta chemokines.

LERK-7: a ligand of the Eph-related kinases is developmentally regulated in the brain

The eph family is the largest subfamily of receptor tyrosine kinases (RTKs). Members of this subfamily display specific expression in the developing and adult brain. Recently, cDNAs encoding membrane bound ligands for these receptors have been identified which we have termed LERKs (ligand for eph-related kinases). We report here the isolation of LERK-7 from a human fetal brain cDNA library. LERK-7 encodes a protein of 228 amino acids and is anchored to the membrane by glycosyl-phosphatidylinositol (GPI) linkage. When transfected into CV1/EBNA cells, LERK-7 binds soluble forms of both hek and elk. In addition, a soluble form of LERK-7 will induce phosphorylation of eck expressed in a human duodenum adenocarcinoma cell line. LERK-7 expressed multiple transcripts (7.5-kb, 6.0-kb, and 3.5-kb) with the highest levels in human adult brain, heart, spleen, and ovary and human fetal brain, lung, and kidney. Similar to the other ligands in this family, LERK-7 is developmentally regulated in the brain. LERK-7 is identical to the recently described AL-1.

The salmon SmaI family of short interspersed repetitive elements (SINEs): interspecific and intraspecific variation of the insertion of SINEs in the genomes of chum and pink salmon

The genomes of chum salmon and pink salmon contain a family of short interspersed repetitive elements (SINEs), designated the salmon SmaI family. It is restricted to these two species, a distribution that suggests that this SINE family might have been generated in their common ancestor. When insertions of the SmaI SINEs at 10 orthologous loci of these species were analyzed, however, it was found that there were no shared insertion sites between chum and pink salmon. Furthermore, at six loci where SmaI SINEs have been species-specifically inserted in chum salmon, insertions of SINEs were polymorphic among populations of chum salmon. By contrast, at four loci where SmaI SINEs had been species-specifically inserted in pink salmon, the SINEs were fixed among all populations of pink salmon. The interspecific and intraspecific variation of the SmaI SINEs cannot be explained by the assumption that the SmaI family was amplified in a common ancestor of these two species. To interpret these observations, we propose several possible models, including introgression and the horizontal transfer of SINEs from pink salmon to chum salmon during evolution.