Fluorescent ligands for the histamine H2 receptor: synthesis and preliminary characterization

3-[3-(Piperidinomethyl)phenoxy]alkyl, N-cyano-N′-[ω-[3-(1-piperidinylmethyl)phenoxy]alkyl]guanidine and 2-(5-methyl-4-imidazolyl)methyl thioethyl derivatives containing fluorescent functionalities were synthesized and the histamine H₂ receptor affinity was evaluated using the H₂ antagonist [¹²⁵I]-aminopotentidine. The compounds exhibited weak to potent H₂ receptor affinity with pK_i values ranging from <4 to 8.85. The highest H₂ receptor affinity was observed for N-cyano-N′-[ω-[3-(1-piperidinylmethyl)phenoxy]alkyl]guanidines substituted with methylanthranilate (13), cyanoindolizine (6) and cyanoisoindole (11) moieties via an ethyl or propyl linker.     

Platelet sparing effect of COX II inhibition used with pegylated interferon alfa-2a for the treatment of chronic hepatitis C: a short term pilot study

The role of a cyclooxygenase (COX) II inhibitor in reducing microvascular inflammation and the platelet count associated with interferon (IFN) plus ribavirin therapy of chronic hepatitis C (HCV) was assessed. Three plasma mediators (biomarkers) associated with platelet activation, inflammation and fibrosis were measured. Eighteen IFN na?ve patients were studied. Nine were treated with pegylated IFN alfa-2a (PEG-IFN alpha-2a) plus ribavirin and rofecoxib; nine were treated with PEG-IFN alpha-2a plus ribavirin. A complete blood count, liver panel and HCV-RNA were assayed weekly. Human soluble P-selectin (hs-P-selectin), human interleukin-8 (IL-8), human interleukin-13 (IL-13) and human thrombopoietin (TPO) were assayed at 4 week intervals. The COX II inhibitor reduced the platelet reduction experienced with PEG-IFN alpha-2a treatment of HCV despite a reduction in the plasma TPO level. Hs-P-selectin was increased in both groups. In contrast, human IL-8 levels declined to undetectable levels in virologic responders. Similarly, human IL-13 levels declined with therapy (P < 0.001). These data suggest that: (1) a COX II inhibition is associated with an increase in the platelet count despite a reduction in the TPO level; (2) human IL-8 and human IL-13 but not hs-P-selectin levels decline in those who experience an early virologic response.     

In vivo measurement of coronary circulation angiotensin-converting enzyme activity in humans

Angiotensin-converting enzyme (ACE) is present on the luminal surface of the coronary vessels, mostly on capillary endothelium. ACE is also expressed on coronary smooth muscle cells and on plaque lipid-laden macrophages. Excessive coronary circulation (CC)-ACE activity might be linked to plaque progression. Here we used the biologically inactive ACE substrate (3)H-labeled benzoyl-Phe-Ala-Pro ([(3)H]BPAP) to quantify CC-ACE activity in 10 patients by means of the indicator-dilution technique. The results were compared with atherosclerotic burden determined by coronary angiography. There was a wide range of CC-ACE activity as revealed by percent [(3)H]BPAP hydrolysis (30-74%). The atherosclerotic extent scores ranged from 0.0 to 66.97, and the plaque area scores ranged from 0 to 80 mm(2). CC-ACE activity per unit extracellular space (V(max)/K(m)V(i)), an index of metabolically active vascular surface area, was correlated with myocardial blood flow (r = 0.738; P = 0.03) but not with measures of the atherosclerotic burden. These results show that CC-ACE activity can be safely measured in humans and that it is a good marker of the vascular area of the perfused myocardium. It does not, however, reflect epicardial atherosclerotic burden, suggesting that local tissue ACE may be more important in plaque development.     

Unique and conserved features of genome and proteome of SARS-coronavirus,an early split-off from the coronavirus group 2 lineage

The genome organization and expression strategy of the newly identified severe acute respiratory syndrome coronavirus (SARS-CoV) were predicted using recently published genome sequences. Fourteen putative open reading frames were identified, 12 of which were predicted to be expressed from a nested set of eight subgenomic mRNAs. The synthesis of these mRNAs in SARS-CoV-infected cells was confirmed experimentally. The 4382- and 7073 amino acid residue SARS-CoV replicase polyproteins are predicted to be cleaved into 16 subunits by two viral proteinases (bringing the total number of SARS-CoV proteins to 28). A phylogenetic analysis of the replicase gene, using a distantly related torovirus as an outgroup, demonstrated that, despite a number of unique features, SARS-CoV is most closely related to group 2 coronaviruses. Distant homologs of cellular RNA processing enzymes were identified in group 2 coronaviruses, with four of them being conserved in SARS-CoV. These newly recognized viral enzymes place the mechanism of coronavirus RNA synthesis in a completely new perspective. Furthermore, together with previously described viral enzymes, they will be important targets for the design of antiviral strategies aimed at controlling the further spread of SARS-CoV.     

Dynamics of macrophage cell populations during murine pulmonary tuberculosis

The influx of macrophages into the lungs is the major component of the granulomatous response to infection with Mycobacterium tuberculosis. In this investigation we used flow cytometric analysis to define macrophage populations entering the airways and lung tissues of infected mice. We demonstrate that by the judicious use of cell surface markers, especially CD11b and CD11c, several cell populations can be distinguished, allowing cell sorting and morphological definition. Primary populations of CD11b(-)/CD11c(+/high) were defined as alveolar macrophages, CD11b(high)/CD11c(+/high) as dendritic cells, and CD11b(+/mid)/CD11c(+/mid) as small macrophages or monocytes, and changes in the activation phenotype of these populations were followed over the early course of the infection. In further studies, these cell populations were compared with cells harvested during the chronic stage of the disease. During the chronic stage of infection, Ag-presenting class II molecules and activation markers were poorly expressed on dendritic, small macrophage, and monocyte cell populations, which may have important implications for the breakdown of the lesions during reactivation disease. This analytical approach may facilitate the further characterization of macrophage populations entering into the lung tissues and their relative contributions to host resistance to tuberculosis infection.     

Comparison of MultiMap and TSP/CONCORDE for constructing radiation hybrid maps

Radiation hybrid (RH) map construction allows investigators to locate both type I and type II markers on a given genome map. The process is composed of two steps. The first consists of determining the pattern distribution of a set of markers within the different cell lines of an RH panel. This is mainly done by polymerase chain reaction (PCR) amplification and gel electrophoresis, and results in a series of numbers indicating the presence or the absence of each marker in each cell line. The second step consists of a comparison of these numbers, using various algorithms, to group and then order markers. Because different algorithms may provide (slightly) different orders, we have compared the merits of the MultiMap and TSP/CONCORDE packages using a data set of information currently under analysis for construction of the canine genome RH map.     

H2AX regulates meiotic telomere clustering

The histone H2A variant H2AX is phosphorylated in response to DNA double-strand breaks originating from diverse origins, including dysfunctional telomeres. Here, we show that normal mitotic telomere maintenance does not require H2AX. Moreover, H2AX is dispensable for the chromosome fusions arising from either critically shortened or deprotected telomeres. However, H2AX has an essential role in controlling the proper topological distribution of telomeres during meiotic prophase I. Our results suggest that H2AX is a downstream effector of the ataxia telangiectasia-mutated kinase in controlling telomere movement during meiosis.