Glial mechanisms underlying substance use disorders.

Addiction is a devastating disorder that produces persistent maladaptive changes to the central nervous system, including glial cells. Although there is an extensive body of literature examining the neuronal mechanisms of substance use disorders, effective therapies remain elusive. Glia, particularly microglia and astrocytes, have an emerging and meaningful role in a variety of processes beyond inflammation and immune surveillance, and may represent a promising therapeutic target. Indeed, glia actively modulate neurotransmission, synaptic connectivity and neural circuit function, and are critically poised to contribute to addictive-like brain states and behaviors. In this review, we argue that glia influence the cellular, molecular, and synaptic changes that occur in neurons following drug exposure, and that this cellular relationship is critically modified following drug exposure. We discuss direct actions of abused drugs on glial function through immune receptors, such as Toll-like receptor 4, as well as other mechanisms. We highlight how drugs of abuse affect glia-neural communication, and the profound effects that glial-derived factors have on neuronal excitability, structure, and function. Recent research demonstrates that glia have brain region-specific functions, and glia in different brain regions have distinct contributions to drug-associated behaviors. We will also evaluate the evidence demonstrating that glial activation is essential for drug reward and drug-induced dopamine release, and highlight clinical evidence showing that glial mechanisms contribute to drug abuse liability. In this review, we synthesize the extensive evidence that glia have a unique, pivotal, and underappreciated role in the development and maintenance of addiction.

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for CYP2C19 and Voriconazole Therapy.

Voriconazole, a triazole antifungal agent, demonstrates wide interpatient variability in serum concentrations, due in part to variant CYP2C19 alleles. Individuals who are CYP2C19 ultrarapid metabolizers have decreased trough voriconazole concentrations, delaying achievement of target blood concentrations; whereas poor metabolizers have increased trough concentrations and are at increased risk of adverse drug events. We summarize evidence from the literature supporting this association and provide therapeutic recommendations for the use of voriconazole for treatment based on CYP2C19 genotype (updates at https://cpicpgx.org/guidelines/ and www.pharmgkb.org).

Weight assessment in cardiac patients: implications for prescription of low molecular weight heparin.

BACKGROUND: Many drugs such as low molecular weight heparin (LMWH) are administered at "patient weight adjusted" doses. Obtaining an accurate measurement of a patient's weight may not always be possible. The aim of this study was to assess patterns and accuracy of weight estimation and implications for drug dosing. METHODS: The study comprised three parts: (1) inpatient weight documentation was reviewed over a 4 week period (January 2008); (2) a questionnaire was distributed to healthcare staff; (3) healthcare staff were asked to estimate the weight of patients. These estimates took place in three locations: the coronary care unit, cardiac catheterisation laboratory, and the cardiac outpatient department. RESULTS: (1) In 385 patient notes, only 192 (49.9%) had a record of the patient's weight. The dose of LMWH was correct only 51% of the time. (2) Doctors were more likely to estimate a patient's weight than nurses (85 vs 51%, p = 0.003). (3) 50 healthcare staff made 533 weight estimations on 182 patients. There was a tendency to overestimate the weight of lighter patients and underestimate the weight of heavier patients (p<0.001). Patients were more accurate than healthcare staff at estimating their weight (80% vs 39%, p<0.001) and female patients were more likely to be accurate than men (62% vs 44%, p = 0.035). CONCLUSIONS: In our institution weight estimation occurs and may result in inaccurate prescription of LMWH. Estimating a patient's weight should be discouraged but if necessary the patient reported weight is likely to be most accurate. Unless there is significant investment in improved technology to allow obese or acutely unwell patients to be weighed, the dangerous practice of weight estimation is likely to continue.

Abacavir pharmacokinetics during chronic therapy in HIV-1-infected adolescents and young adults.

The pharmacokinetics of abacavir and its metabolites were investigated in 30 human immunodeficiency virus (HIV)-infected adolescents and young adults 13-25 years of age, equally divided into two groups: <18 years of age and >or=18 years of age. All the subjects received the recommended adult dose of 300 mg twice daily. The area under the plasma concentration-time curve (AUC) and half-life of abacavir did not differ significantly between the age groups or by gender or race, and there were only modest associations of age with apparent abacavir clearance and with volume of distribution. There were no significant correlations of carboxylate or glucuronide metabolite levels with age or gender, although glucuronide AUC was higher in Hispanic subjects than in African-American subjects. Zidovudine and lamivudine concentration profiles were also similar in the two age groups. A novel aspect of the study included an assessment of intracellular carbovir, zidovudine, and lamivudine triphosphate levels, and these were found to be similar in the two age-based groups. Overall, these findings suggest that current recommendations relating to adult dosages are appropriate for adolescents and young adults.

Characterization of the TBX5 binding site and analysis of mutations that cause Holt-Oram syndrome.

Holt-Oram syndrome is caused by mutations in TBX5, a member of the T-box gene family. In order to identify DNA sequences to which the TBX5 protein binds, we have performed an in vitro binding site selection assay. We have identified an 8 bp core sequence that is part of the Brachyury consensus-binding site. We show that TBX5 binds to the full palindromic Brachyury binding site and to the half-palindrome, whereas Brachyury does not bind to the TBX5 site. Amino acids 1-237 of TBX5 are required for DNA binding. Analysis of the effects of specific substitution mutations that arise in Holt-Oram patients indicates that G80R and R237Q eliminate binding to the target site. DNA database analysis reveals that target sites are present in the upstream regions of several cardiac-expressed genes including cardiac alpha actin, atrial natriuretic factor, cardiac myosin heavy chain alpha, cardiac myosin heavy chain beta, myosin light chain 1A, myosin light chain 1V and Nkx2.5. Cell transfection studies demonstrate that TBX5 activates the transcription of an atrial natriuretic factor reporter construct and this effect is significantly reduced by deletion of the TBX5 binding site.

Genetic determinants of sensitivity to diazepam in inbred mice.

Mice from 15 standard inbred strains were tested for sensitivity to several effects of acute diazepam (DZ). Strains differed in sensitivity to DZ-induced: low-dose stimulation and high-dose depression of locomotor activity, hypothermia, and ataxia assessed on a rotarod. Correlations among strain means indicated that sensitivity to a particular effect of DZ generalized well across doses. Sensitivities to some of the different behavioral responses also were significantly correlated. For example, strains sensitive to DZ-induced increases in activity were significantly less sensitive to the drug's hypothermic effects. These results suggest that there are multiple genetic determinants of behavioral sensitivity to DZ effects. That is, genetically influenced sensitivity to DZ is not monolithic but is somewhat specific to the particular response variable studied, a result that also characterizes genetic control of responses to other drugs.

Rapid myoglobin analysis to assess coronary artery reperfusion after acute myocardial infarction.

BACKGROUND: Coronary artery reperfusion significantly improves outcome in patients with acute myocardial infarction. A noninvasive method for assessing reperfusion in the early stage of infarction should be helpful in patient management. HYPOTHESIS: We sought to assess whether release pattern of myoglobin is helpful in identifying patients with and without reperfusion following thrombolytic therapy for myocardial infarction. METHODS: Myoglobin was measured before thrombolysis, half hourly for 4 h, then every 2 h for 10 h. Myoglobin was analyzed using a ward-based "rapid" and automated analyzer that yielded quantitative results within 10 min of blood collection. RESULTS: In the 15 patients with coronary reperfusion, the time from thrombolysis to peak myoglobin levels (mean +/- SD, 2.4 +/- 1.5 h) was significantly lower than in nonreperfused patients (5.1 +/- 2.9, p < 0.01). As an indicator for reperfusion, a doubling of myoglobin 1 h after streptokinase achieved a sensitivity of 80%, a specificity of 80%, and a predictive accuracy of 80%. CONCLUSIONS: The difference in myoglobin release kinetics is useful in identifying patients without coronary reperfusion and should aid in their management.

Mapping of 10 novel microsatellites in the MHC class III region: application to the study of autoimmune disease.

The MHC class III region contains many genes that are good candidates for involvement in autoimmune disease. We report the mapping and characterization of 10 novel (CA)n microsatellites spanning the region, which are highly informative and suitable for linkage and association studies. We used these markers to identify haplotypes of MHC class III microsatellite alleles in DNA from cell lines homozygous for MHC class II and class I alleles.

Hypothermia in the north east of Scotland.

The aim of the study was to establish the incidence of hypothermia in the Grampian region, and to examine the accuracy of routine reporting of hypothermia on hospital discharge records. From 1990-1994, 167 patients were admitted with an SMRI diagnosis of hypothermia. An admission temperature of under 35 degrees C was recorded in 47 (28%); rectal in 37 (confirmed hypothermia) and not specified on non-rectal in 10 (possible hypothermia). Most admissions were during the winter months in only 18 cases of the 47 patients with confirmed or possible hypothermia was a secondary cause not apparent. Isolated hypothermia is rare in Grampian. In most cases other disease is the underlying cause.

Thermostable chaperonin from Clostridium thermocellum.

Homologues of the chaperonins Cpn60 and Cpn10 have been purified from the Gram-positive cellulolytic thermophile Clostridium thermocellum. The Cpn60 protein was purified by ATP-affinity chromatography and the Cpn10 protein was purified by gel-filtration, ion-exchange and hydrophobic interaction chromatographies. The identities of the proteins were confirmed by N-terminal sequence analysis and antigenic cross-reactivity. The Cpn60 homologue is a weak, thermostable ATPase (t1/2 at 70 decrees C more than 90 min) with optimum activity (Kcat 0.07 S-1) between 60 degrees C and 70 degrees C. The ATPase activity of the authentic Cpn60 was inhibited by Escherichia coli GroES. The catalytic properties of a recombinant C. thermocellum Cpn60 purified from a GST-Cpn60 fusion protein expressed in E. coli [Ciruela (1995) Ph.D. Thesis, University of Kent] were identical with those of the authentic C. thermocellum Cpn60. Gel-filtration studies show that at room temperature the Cpn60 migrates mainly as a heptamer. Electron microscopy confirms the presence of complexes showing 7-fold rotational symmetry and also reveals a small number of particles that seem to be tetradecamers with a similar structure to E. coli GroEL complexes.

Defining the immunogenetic susceptibility to primary biliary cirrhosis.

Primary biliary cirrhosis is a chronic cholestatic disease, thought to be immune-mediated with genetic susceptibility encoded in the major histocompatibility complex. In northern Europeans, the best established associations are with HLA-DR8 and the complement allele, C4B2. These associations could be due to a single susceptibility locus on an extended haplotype linking HLA-DR8 and C4B2 or to both HLA-DR8 and C4B2 independently conferring disease susceptibility. C4B2 genotyping was performed on 64 patients with primary biliary cirrhosis and 61 controls matched for ethnic background and frequency of HLA-DR8. C4B2 was associated with HLA-DR8 (p < 0.05) in PBC. No difference in the frequency of C4B2 was detected between control and disease populations, suggesting that HLA-DR8 and C4B2 are in linkage disequilibrium and that C4B2 is not a susceptibility locus for PBC. Taq I polymorphisms were screened in the disease and control populations with the cosmid probe G91, located midway between the HLA-DR and complement loci. One G91 restriction fragment (G91A) was found to be associated with both HLA-DR8 and C4B2, at equal frequency in health and disease, providing evidence of an HLA-DR8-G91A-C4B2 extended haplotype. The frequency of G91A was the same in the disease and control populations, suggesting that G91A does not confer disease susceptibility. These findings establish G91 as the telomeric boundary for disease susceptibility associated with HLA-DR8, encoded on chromosome six. These studies help define the immunogenetic susceptibility locus for primary biliary cirrhosis.

Assessment of left ventricular regional wall motion with blood pool tomography: comparison of 11CO PET with 99Tcm SPECT.

Left ventricular contraction is routinely assessed by radionuclide ventriculography. Although a planar image is conventionally used, tomography has been to improve the detection of wall motion abnormalities. A blood pool image is often used in positron emission tomography on which to superimpose metabolic tracers. Can this image also be used to assess left ventricular contraction? Nine healthy controls, mean (S.D.) age 55 (5) years, and 12 patients, mean (S.D.) age 61 (8) years, with normal, proven or suspected left ventricular damage underwent blood pool tomography with 11CO positron emission tomography (PET) and 99Tcm single photon emission computed tomography (SPECT). A normal value of ejection fraction and range of phase were defined. The normal left ventricular ejection fraction was > or = 37% for PET and > or = 40% for SPECT. The ejection fractions obtained by the two methods in the patient group were positively correlated (r = 0.89, P < 0.001). Abnormalities of left ventricular contraction were detected in nine patients by PET and 10 patients by SPECT imaging. The discrepancy was in a patient with a previous inferior myocardial infarction. Blood pool imaging with 11CO PET can be used to assess left ventricular ejection fraction and regional wall motion.

Comparison of the value of novel rapid measurement of myoglobin, creatine kinase, and creatine kinase-MB with the electrocardiogram for the diagnosis of acute myocardial infarction.

OBJECTIVE: To determine whether serum myoglobin, creatine kinase, and creatine kinase-MB measured at admission by rapid, compact, and easy to use automated quantitative analysers (results within 10 min) helped the early identification of acute myocardial infarction. The results were compared with the data obtained from the electrocardiograms recorded at admission. DESIGN: A prospective study. SETTING: Coronary care unit. PATIENTS: 94 consecutive patients with suspected myocardial infarction. Myocardial infarction was subsequently confirmed in 44 patients and excluded in 50. METHODS: All admission serum myoglobin, creatine kinase, and creatine kinase-MB were measured by clinical staff using analysers in the coronary care unit. An admission electrocardiogram was obtained from all patients. RESULTS: The sensitivity, specificity, and predictive accuracy for diagnosing myocardial infarction were: electrocardiogram 68%, 100%, and 85%; myoglobin 57%, 100%, and 80%; creatine kinase (threshold of 190 U/l) 34%, 98%, and 68%; creatine kinase-MB (threshold of 25 U/l) 43%, 100%, and 73%. When the electrocardiographic and myoglobin data were combined the sensitivity improved to 91%, diagnostic accuracy to 96%, with specificity of 100%. The results for the electrocardiogram and creatine kinase-MB were 80%, 90%, 100% respectively and those for the electrocardiogram with creatine kinase were 80%, 89%, 98% respectively. CONCLUSIONS: Admission myoglobin, creatine kinase, and creatine kinase-MB measurements were not as useful as the electrocardiogram for the diagnosis of acute myocardial infarction. Combining the electrocardiogram and myoglobin data substantially improved the sensitivity and predictive accuracy for the diagnosis of acute myocardial infarction.

Patients with suspected myocardial infarction who present with ST depression.

Patients with suspected myocardial infarction who present with ST depression have a high mortality which is not reduced by thrombolytic therapy. Despite this, there are few data on these patients. We studied the electrocardiographic and clinical characteristics of these patients, the diagnostic and prognostic value of the presenting electrocardiogram (ECG), and the reasons for the high mortality and apparent lack of thrombolytic efficacy. We studied all patients with suspected infarction admitted during 1990 with ST depression. Of the 136 patients (84 men, mean [SD] age 68 [11] years), 74 (54%) had confirmed infarction and 73 (54%) had previous infarction. 1-year mortality was 26% for all patients, 31% for those with confirmed infarcts, and 19% for those in whom infarction was subsequently excluded. Patients with infarction had more severe ST depression (mean 2.5 mm [SD 1.5]) and more ECG leads with ST depression (mean 4.7 leads [1.8]) compared with patients without infarction (1.4 mm [0.8], p < 0.001; 3.6 leads [1.7], p < 0.001). Sensitivity and specificity for the subsequent diagnosis of infarction with ST depression were 20% and 97%, respectively, for at least 4 mm; and 21% and 95%, respectively, for at least 7 leads. 1-year mortality was low in patients with 1 mm ST depression (14%) or no more than 2 leads (11%), but high in patients with at least 2 mm ST depression (39%, p < 0.001) and at least 3 leads (30%, p = 0.08). Patients with suspected infarction and ST depression had a high mean age, high incidence of previous infarction, and poor prognosis. The presenting ECG is helpful in predicting prognosis, and ST depression of at least 4 mm or involving at least 7 leads is highly specific for diagnosis of infarction.

First myocardial infarction in patients under 60 years old: the role of exercise tests and symptoms in deciding whom to catheterise.

OBJECTIVE: To determine the role of exercise tests and assessment of angina in the detection of potentially threatening disease in young patients with infarcts. DESIGN: Elective readmission of patients at a mean (SD) of 60 (30) days after acute myocardial infarction for assessment of angina, treadmill exercise tests, and cardiac catheterisation. SETTING: Cardiology department of a teaching hospital. PATIENTS: 186 consecutive survivors, aged under 60 years and discharged from the coronary care unit after a first myocardial infarction. MAIN OUTCOME MEASURES: Coronary arteriography, presence of angina, result of exercise tests, and referral for revascularisation. RESULTS: 31% of patients had either two vessel disease (with proximal left anterior descending involvement), three vessel disease, or left main stem disease. 49% of all patients had angina. Of the 173 patients who had an exercise test 34% had 1 mm and 24% had 2 mm of exercise induced ST depression. Thirty percent had no angina and a negative exercise test: after a mean (SD) follow up of 16 (4) months none of this symptom free sub-group had died, had experienced a further myocardial infarction, or had been referred for revascularisation. 79% of patients with either two vessel disease (with proximal left anterior descending involvement), three vessel disease, or left main stem disease had either angina or a 1 mm ST depression during the exercise test. CONCLUSION: Patients without cardiac pain after myocardial infarction and without ST changes during an exercise do not need arteriography.