N-aryl piperazine metabotropic glutamate receptor 5 positive allosteric modulators possess efficacy in preclinical models of NMDA hypofunction and cognitive enhancement.

Impaired transmission through glutamatergic circuits has been postulated to play a role in the underlying pathophysiology of schizophrenia. Furthermore, inhibition of the N-methyl-d-aspartate (NMDA) subtype of ionotropic glutamate receptors (NMDAR) induces a syndrome that recapitulates many of the symptoms observed in patients with schizophrenia. Selective activation of metabotropic glutamate receptor subtype 5 (mGlu5) may provide a novel therapeutic approach for treatment of symptoms associated with schizophrenia through facilitation of transmission through central glutamatergic circuits. Here, we describe the characterization of two novel N-aryl piperazine mGlu5 positive allosteric modulators (PAMs): 2-(4-(2-(benzyloxy)acetyl)piperazin-1-yl)benzonitrile (VU0364289) and 1-(4-(2,4-difluorophenyl)piperazin-1-yl)-2-((4-fluorobenzyl)oxy)ethanone (DPFE). VU0364289 and DPFE induced robust leftward shifts in the glutamate concentration-response curves for Ca(2+) mobilization and extracellular signal-regulated kinases 1 and 2 phosphorylation. Both PAMs displayed micromolar affinity for the common mGlu5 allosteric binding site and high selectivity for mGlu5. VU0364289 and DPFE possessed suitable pharmacokinetic properties for dosing in vivo and produced robust dose-related effects in reversing amphetamine-induced hyperlocomotion, a preclinical model predictive of antipsychotic-like activity. In addition, DPFE enhanced acquisition of contextual fear conditioning in rats and reversed behavioral deficits in a mouse model of NMDAR hypofunction. In contrast, DPFE had no effect on reversing apomorphine-induced disruptions of prepulse inhibition of the acoustic startle reflex. These mGlu5 PAMs also increased monoamine levels in the prefrontal cortex, enhanced performance in a hippocampal-mediated memory task, and elicited changes in electroencephalogram dynamics commensurate with procognitive effects. Collectively, these data support and extend the role for the development of novel mGlu5 PAMs for the treatment of psychosis and cognitive deficits observed in individuals with schizophrenia.

Molecular strain typing of Mycobacterium tuberculosis complex in Bamako, Mali.

OBJECTIVE: To identify strains of Mycobacterium tuberculosis complex (MTC) circulating in Bamako and to examine the relationship between the strains and their drug susceptibility profiles. METHODS: Between 2006 and 2010, we conducted a cross-sectional study using spoligotyping to identify strains of MTC recovered from 126 tuberculosis (TB) patients under treatment in Bamako, Mali. RESULT: Three members of the MTC were isolated: M. tuberculosis (71.4%), M. africanum (27.8%) and M. bovis (0.8%). Of these, three strains were found to be the most prevalent: M. tuberculosis T1 (MTB T1; 38.9%), M. africanum F2 (MAF2; 26.2%) and M. tuberculosis Latin American and Mediterranean 10 (MTB LAM 10; 10.3%). MAF2 and MTB LAM 10 strains have a lower risk of multidrug resistance (MDR) than MTB T1 (respectively OR 0.1, 95%CI 0.03-0.4 and OR 0.1, 95%CI 0.01-0.8). Age ≥ 32 years (OR 1.4, 95%CI 0.4-3.9), negative human immunodeficiency virus status (OR 0.4, 95%CI 0.1-2.5) and male sex (OR 4, 95%CI 0.9-16.5) were not associated with MDR. The prevalence of MDR among treatment and retreatment failure patients was respectively 25% and 81.8% compared to new patients (2.9%). CONCLUSION: This study indicates a low level of primary drug resistance in Bamako, affirms the importance of using correct drug regimens, and suggests that the MTB T1 strain may be associated with the development of resistance.

Mycobacterium tuberculosis genome-wide screen exposes multiple CD8 T cell epitopes.

Mounting evidence suggests human leucocyte antigen (HLA) class I-restricted CD8(+) T cells play a role in protective immunity against tuberculosis yet relatively few epitopes specific for the causative organism, Mycobacterium tuberculosis, are reported. Here a total genome-wide screen of M. tuberculosis was used to identify putative HLA-B*3501 T cell epitopes. Of 479 predicted epitopes, 13 with the highest score were synthesized and used to restimulate lymphocytes from naturally exposed HLA-B*3501 healthy individuals in cultured and ex vivo enzyme-linked immunospot (ELISPOT) assays for interferon (IFN)-gamma. All 13 peptides elicited a response that varied considerably between individuals. For three peptides CD8(+) T cell lines were expanded and four of the 13 were recognized permissively through the HLA-B7 supertype family. Although further testing is required we show the genome-wide screen to be feasible for the identification of unknown mycobacterial antigens involved in immunity against natural infection. While the mechanisms of protective immunity against M. tuberculosis infection remain unclear, conventional class I-restricted CD8(+) T cell responses appear to be widespread throughout the genome.

HLA-B*35-restricted CD8 T cell epitopes in the antigen 85 complex of Mycobacterium tuberculosis.

Few target epitopes have been described for human CD8 T lymphocytes in antigens of Mycobacterium tuberculosis. By use of a reverse immunogenetics approach, 23 motif-bearing peptides of the Ag85 complex were tested for binding to HLA-B*35, one of the common B-types in West Africa. Three 9-mer peptides bound with high affinity to HLA-B*3501 and displayed low dissociation rates of peptide-major histocompatibility complexes (MHCs). IC(50) and half-life values of peptide-MHC class I complexes were in the same range as reported earlier for other immunogenic peptides. Immune responses against peptide Ag85C (aa 204-212) WPTLIGLAM were characterized in detail. Peptide-stimulated effector cells were able to kill macrophages infected with M. tuberculosis or bacille Calmette-Guérin. Peptide-specific CD8 T cells could be visualized by using HLA-B*3501 tetramers and were shown to produce interferon-gamma and tumor necrosis factor-alpha. Together with other published epitopes, these peptides can be used to study more closely the role of CD8 T cells in mycobacterial infection and tuberculosis.

Contact areas and pressures between native patellas and prosthetic femoral components.

Contact areas and pressures between native patellas and a prosthetic condylar design femoral component were measured at flexion angles of 30 degrees, 60 degrees, and 90 degrees. These were compared to measurements obtained with a domed all-polyethylene patellar component. Mean native patellar contact areas were found to be fourfold greater than seen with the prosthetic patellar component. Contact stresses in the native patellas were below the yield strength of articular cartilage in 80% of the contact area. By contrast, stresses measured in the prosthetic patella exceeded the yield strength of ultrahigh molecular weight polyethylene in 64% of the measured contact area. Contact areas and stresses were not significantly effected by flexion angle. Although contact areas and stresses reflect only a part of the dynamics of the patellofemoral articulation this information would support the selective retention of the native patella in total knee arthroplasty.

The prevalence and clinical characteristics of short segments of specialized intestinal metaplasia in the distal esophagus on routine endoscopy.

OBJECTIVE: To prospectively determine the prevalence and clinical characteristics of short segments of specialized intestinal metaplasia in the distal esophagus. Short segment is defined as extending less than 2 cm proximal to the esophagogastric junction. This has been referred to by some investigators as "short segment Barrett's esophagus." METHODS: One hundred and seventy two patients undergoing elective esophagogastroduodenoscopy were consecutively enrolled. Patients with known Barrett's esophagus were excluded. All study patients completed a symptom questionnaire. At endoscopy, the presence of esophagitis and locations of the diaphragmatic hiatus, esophagogastric junction, and the squamocolumnar junction were recorded. Biopsy specimens were obtained at the squamocolumnar junction to identify specialized intestinal metaplasia and 2 cm above the squamocolumnar junction to evaluate for histological esophagitis. RESULTS: Two patients (1.2%) had at least 2 cm of columnar-lined esophagus. Of the 170 patients without 2 cm of columnar-lined esophagus, 16 (9.4%) patients had short segments of specialized intestinal metaplasia. Twelve (7.0%) of these patients had specialized intestinal metaplasia limited to the esophagogastric junction. All patients with specialized intestinal metaplasia were Caucasian, and there was a slight male predominance. Patients without specialized intestinal metaplasia (n = 154, 90.6%) did not differ statistically with respect to age, gender, use of acid-suppressing drugs, alcohol, or smoking history. Pyrosis and regurgitation were significantly more common in patients with specialized intestinal metaplasia involving the distal 2 cm of the esophagus or the esophagogastric junction. Cough was more common in the group with specialized intestinal metaplasia limited to the esophagogastric junction. The groups were similar in frequency of dysphagia, globus sensation, nocturnal pyrosis, eructation, early satiety, nausea, and abdominal pain. CONCLUSIONS: Specialized intestinal metaplasia less than 2 cm proximal to the esophagogastric junction is common in Caucasian patients undergoing routine esophagogastroduodenoscopy. Pyrosis and regurgitation are significantly more common in patients with short segments of specialized intestinal metaplasia, whether involving the distal 2 cm of the esophagus or the esophagogastric junction alone. Alcohol and tobacco use are no more common in patients with specialized intestinal metaplasia than in those without metaplasia. The presence of specialized intestinal metaplasia did not correlate with either endoscopic or histological esophagitis.