Vendor differences in alcohol consumption and the contribution of dopamine receptors to Pavlovian-conditioned alcohol-seeking in Long-Evans rats

RATIONALE

Drug-associated environmental stimuli elicit craving in humans and drug-seeking in animals.

OBJECTIVES

We tested the hypothesis that Pavlovian-conditioned alcohol-seeking is mediated by dopamine, using rats from two vendors.

METHODS

Male, Long-Evans rats (220-240 g) from Charles River (St-Constant, QC, Canada) and Harlan Laboratories (Indianapolis, IN, USA) received 21 sessions of intermittent, 24-h access to ethanol (15 %, v/v) and water in the home-cage. Subsequently, rats were trained to discriminate between one conditioned stimulus (CS+) that was paired with ethanol (0.2 ml per CS+) and a second stimulus (CS-) that was not. Entries into a fluid port where ethanol was delivered were recorded. Next, rats were exposed to a different context where cues and ethanol were withheld. At test, responding to the CS+ and CS- without ethanol was assessed in the second, non-alcohol context. Injections (1 ml/kg; s.c.) of the dopamine D1-receptor antagonist SCH 23390 (0, 3.33, and 10 μg/kg) or dopamine D2-receptor antagonist eticlopride (0, 5, and 10 μg/kg) were administered before test.

RESULTS

Home-cage alcohol consumption was higher in Harlan rats than Charles River rats. At test, saline-treated rats responded more to the alcohol-predictive CS+ than the CS-. While SCH 23390 attenuated CS+ responding in rats from both vendors, eticlopride reduced CS+ responding in Harlan rats only. Subsequently, SCH 23390 but not eticlopride attenuated CS+ responding when the CS+ was again paired with ethanol.

CONCLUSIONS

These results indicate important differences in alcohol consumption in Long-Evans rats from different suppliers, and highlight a novel role for dopamine in Pavlovian-conditioned alcohol-seeking.

Subtyping obesity with microarrays: implications for the diagnosis and treatment of obesity

OBJECTIVE

Obese patients respond differently to weight loss interventions. No efficient diagnostic tool exists to separate obese patients into subtypes as a means to improve prediction of response to interventions. We aimed to separate obese subjects into distinct subgroups using microarray technology to identify gene expression-based subgroups to predict weight loss.

DESIGN

A total of 72 obese men and women without family history of diabetes were enrolled in the study; 52 were treated with ephedra and caffeine (E+C) and 20 with placebo for 8 weeks. Adipose and skeletal muscle tissue biopsies were performed at baseline. RNA sample pairs were labeled and hybridized to oligonucleotide microarrays. Quantile normalization and gene shaving were performed, and a clustering algorithm was then applied to cluster subjects based on their gene expression profile. Clusters were visualized using heat maps and related to weight changes.

RESULTS

Cluster analysis of gene expression data revealed two distinct subgroups of obesity and predicted weight loss in response to the treatment with E+C. One cluster ('red') decreased to 96.87+/-2.35% body weight, and the second cluster ('green') decreased to 95.59+/-2.75% body weight (P<0.05). 'Red' cluster had less visceral adipose tissue mass (2.77+/-1.08 vs 3.43+/-1.49 kg; P<0.05) and decreased size of the very large fat cells (1.45+/-0.61 vs 2.16+/-1.74 microl; P<0.05) compared to 'green' cluster. Gene expression for both skeletal muscle and adipose tissue was also different between clusters.

CONCLUSIONS

Our study provides the first evidence that the combined approach of gene expression profiling and cluster analysis can identify discrete subtypes of obesity, these subtypes have different physiological characteristics and respond differently to an adrenergic weight loss therapy. This brings us that into an era of personalized treatment in the obesity clinic.

Strong association between mitochondrial DNA copy number and lipogenesis in human white adipose tissue

AIMS/HYPOTHESIS

Recent studies suggest a link between insulin resistance and mitochondrial function in white fat cells. The aim of this study was to evaluate adipocyte mitochondrial DNA (mtDNA) copy number in relation to adipocyte and clinical variables that are related to insulin sensitivity.

METHODS

We studied a group of 148 healthy volunteers with a large inter-individual variation in BMI. Relative amounts of mtDNA and nuclear DNA were determined by quantitative RT-PCR. The mtDNA:nuclear DNA ratio reflects the tissue concentration of mtDNA per cell.

RESULTS

The mtDNA copy number was enriched in adipocytes of adipose tissue and decreased slightly by ageing (p = 0.015) and increasing BMI (p = 0.004); however, it was not influenced by sex, energy-restricted diets or marked long-term weight reduction. Adipose mtDNA copy number was not independently related to resting energy expenditure, overall insulin sensitivity or adipocyte lipolysis. However, it showed a strong positive correlation with basal (p = 0.0012) and insulin-stimulated lipogenesis (p < 0.0001) in fat cells, independently of age and BMI, and a weak positive correlation with levels of mRNA from several genes involved in mitochondrial oxidative capacity (r = 0.2-0.3).

CONCLUSIONS/INTERPRETATION

The mtDNA copy number in human white fat cells is fairly stable within healthy individuals. It is not influenced by sex or weight loss and is not important for overall insulin sensitivity or energy expenditure at rest. However, it is strongly related to adipocyte lipogenesis and weakly to mitochondrial oxidative capacity, suggesting that adipocyte mitochondria are, above all, local regulators.

LICOS, a primordial costimulatory ligand?

In mammals, the classical B7 molecules expressed on antigen-presenting cells, B7-1 (CD80) and B7-2 (CD86), bind the structurally related glycoproteins CD28 and CTLA-4 (CD152), generating costimulatory signals that regulate the activation state of T cells. A recently identified human CD28-like protein, ICOS, also induces costimulatory signals in T cells when crosslinked with antibodies, but it is unclear whether ICOS is part of a B7-mediated regulatory pathway of previously unsuspected complexity, or whether it functions independently and in parallel. Here, we report that, rather than binding B7-1 or B7-2, ICOS binds a new B7-related molecule of previously unknown function that we call LICOS (for ligand of ICOS). At 37 degrees C, LICOS binds only to ICOS but, at lower, non-physiological temperatures, it also binds weakly to CD28 and CTLA-4. Sequence comparisons suggest that LICOS is the homologue of a molecule expressed by avian macrophages and of a murine protein whose expression is induced in non-lymphoid organs by tumour necrosis factor alpha (TNFalpha). Our results define the components of a distinct and novel costimulatory pathway and raise the possibility that LICOS, rather than B7-1 or B7-2, is the contemporary homologue of a primordial vertebrate costimulatory ligand.

Effects of N-butyldeoxynojirimycin and the Lec3.2.8.1 mutant phenotype on N-glycan processing in Chinese hamster ovary cells: application to glycoprotein crystallization

Heterologous gene expression in either (1) the glycosylation-defective, mutant Chinese hamster ovary cell line, Lec3.2.8.1, or (2) the presence of the alpha-glucosidase inhibitor, N-butyldeoxynojirimycin facilitates the trimming of N-linked glycans of glycoproteins to single N-acetylglucosamine (GlcNAc) residues with endoglycosidase H (endo H). Both approaches are somewhat inefficient, however, with as little as 12% of the total protein being rendered fully endo H-sensitive under these conditions. It is shown here that the combined effects of these approaches on the restriction of oligosaccharide processing are essentially additive, thereby allowing the production of glycoproteins that are essentially completely endo H-sensitive. The preparation of a soluble chimeric form of CD58, the ligand of the human T-cell surface recognition molecule CD2, illustrates the usefulness of the combined approach when expression levels are low or the deglycosylated protein is unstable at low pH. The endo H-treated chimera produced crystals of space group P3(1)21 or P3(2)21, and unit cell dimensions a = b = 116.4 A, c = 51.4 A alpha = beta = 90 degrees , gamma = 120 degrees , that diffract to a maximum resolution of 1.8 A.

Crystal structure of the CD2-binding domain of CD58 (lymphocyte function-associated antigen 3) at 1.8-A resolution

The binding of the cell surface molecule CD58 (formerly lymphocyte function-associated antigen 3) to its ligand, CD2, significantly increases the sensitivity of antigen recognition by T cells. This was the first heterophilic cell adhesion interaction to be discovered and is now an important paradigm for analyzing the structural basis of cell-cell recognition. The crystal structure of a CD2-binding chimeric form of CD58, solved to 1.8-A resolution, reveals that the ligand binding domain of CD58 has the expected Ig superfamily V-set topology and shares several of the hitherto unique structural features of CD2, consistent with previous speculation that the genes encoding these molecules arose via duplication of a common precursor. Nevertheless, evidence for considerable divergence of CD2 and CD58 is also implicit in the structures. Mutations that disrupt CD2 binding map to the highly acidic surface of the AGFCC'C" beta-sheet of CD58, which, unexpectedly, lacks marked shape complementarity to the equivalent, rather more basic CD58-binding face of human CD2. The specificity of the very weak interactions of proteins mediating cell-cell recognition may often derive largely from electrostatic complementarity, with shape matching at the protein-protein interface being less exact than for interactions that combine specificity with high affinity, such as those involving antibodies.

Recommended technique for brain removal to retain anatomic integrity of the pineal gland in order to determine its size in sudden infant death syndrome

A standardized removal and dissection procedure is presented for human infant brain. A previously unreported cistern of the pineal gland must be severed at autopsy in order to preserve the gland's anatomic integrity during brain removal. Utilization of these methods to investigate Sudden Infant Death Syndrome brain tissue should facilitate interdisciplinary studies and comparisons of inter agency findings. We use these dissection procedures to extend our findings on reduced pineal gland size as an anatomic marker assisting the forensic pathologist in making the diagnosis of Sudden Infant Death Syndrome.

Prothrombin Frankfurt: a dysfunctional prothrombin characterized by substitution of Glu-466 by Ala

We have identified a patient with a dysfunctional prothrombin that we have designated Prothrombin Frankfurt. The proband was characterized by a prothrombin activity level of 13% and 20% compared to normal controls using two different assays with a normal prothrombin antigen level of 91% of normal controls. The genetic defect responsible for the abnormal prothrombin activity was determined by the polymerase chain reaction followed by single-strand conformation polymorphism (PCR-SSCP) analysis and by DNA sequence analysis of the human prothrombin gene. Substitution of a C for an A at nucleotide 10177 in the human prothrombin gene of the proband was identified, which results in the replacement of Glu-466 by Ala. The proband and one sister were homozygous for this mutation. Both parents, as well as one brother, were found to be heterozygous for this mutation. The same amino acid substitution was previously identified to be responsible for the dysfunctional protein Prothrombin Salakta and was hypothesized to result in altered substrate specificity. Four polymorphisms were also identified in the prothrombin gene from the proband when compared to the published sequence at nucleotides 554, 4048, 4272 and 10253.

Diagnosis of tracheal injury in mechanically ventilated premature infants by flexible bronchoscopy. A pilot study

Flexible bronchoscopy (FB) is uniquely suited for the study of large airway lesions in the ventilated premature infant. However, no standardized clinical scoring system of distal tracheal injury exists and the adverse consequences of FB in ventilated premature infants are not well described. Using a prototype Olympus fiberoptic ultrathin bronchoscope with a directable tip and an outer diameter of 2.2 mm, we serially scored distal tracheal injury in conventionally ventilated premature infants on the basis of mucosal and obstructive changes observed at bronchoscopy. In addition, we prospectively evaluated the incidence of adverse cardiovascular and pulmonary effects during, immediately after, and within 1 h of FB. We performed 21 FBs in eight conventionally ventilated premature infants with birth weight of 1,239 +/- 438 g and gestational age of 30 +/- 3 weeks. The carina and mainstem bronchi were easily visualized in all infants using the prototype bronchoscope. During the first several days of life, moderate-to-severe distal tracheal mucosal injury occurred frequently, while moderate-to-severe obstructive injury occurred infrequently. Distal mucosal injury appeared to improve during the fourth week of life. Mild distal obstructive injury began to appear during the second week of life. Adverse consequences of FB observed in our patient population included transient hypoxemia and bradycardia during FB, changes in systolic blood pressure immediately and within 1 h after FB, and emesis immediately after FB. Serious adverse cardiovascular or pulmonary effects were not observed. We conclude that FB can be performed safely with appropriate monitoring and is a useful tool in the clinical assessment and serial evaluation of distal tracheal injury in ventilated premature infants. We speculate that moderate-to-severe distal tracheal mucosal injury may be associated with the development of later obstructive injury. On the basis of this preliminary study, further prospective investigations of tracheal injury in ventilated premature infants appear to be warranted.

Flexible fiberoptic endoscopy for airway problems in a pediatric intensive care unit

We used flexible fiberoptic endoscopy to evaluate 87 patients with potential problems of the airway in a pediatric intensive care unit. Four different-sized bronchoscopes were used to perform 61 diagnostic laryngoscopic procedures, 35 diagnostic bronchoscopic procedures, and eight therapeutic bronchoscopic procedures. Diagnostic information was obtained in 91 of 96 procedures. Of the eight therapeutic procedures, seven were considered successful. Morbidity was minimal, and there was no death. Flexible fiberoptic endoscopy proved useful as a bedside technique for critically ill pediatric patients in whom evaluation of the airway in the operating room under general anesthesia would have been difficult.

Applications of an ultrathin flexible bronchoscope for neonatal and pediatric airway problems

A new 2.7 mm flexible fiberoptic bronchoscope with a directable tip was used to evaluate potential airway problems in 73 pediatric patients. Forty-eight laryngoscopies and 47 bronchoscopies were performed over an 18-month period. Persistent stridor was the most common indication for laryngoscopy; persistent wheezing, the most common indication for bronchoscopy. We obtained diagnostic information in 83 procedures, incidental findings in four, and normal results in eight. There were four complications and no deaths. This instrument enabled patients to be examined who were previously considered too small or who previously required rigid bronchoscopy under general anesthesia.