Kinin- and angiotensin-converting enzyme (ACE) inhibitor-mediated nitric oxide production in endothelial cells

Carboxypeptidase cleavage of the C-terminal Arg of kinins generates specific agonists of the B1 receptor. Activation of B1 receptors produces nitric oxide via eNOS in bovine endothelial cells and iNOS in cytokine-stimulated human endothelial cells. Angiotensin-converting enzyme (ACE) inhibitors are direct agonists of B1 receptors in endothelial cells, although they release NO via a different signaling pathway than peptide ligands in bovine cells. This brief review discusses carboxypeptidase M as a required processing enzyme for generating B1 agonists, how ACE inhibitors and peptide ligands stimulate NO production and the evidence for, as well as some consequences of, the direct activation of B1 receptors by ACE inhibitors.     

Synthesis and characterization of a novel Pd(II) complex with the condensation product of 2-(diphenylphosphino)benzaldehyde and ethyl hydrazinoacetate. Cytotoxic activity of the synthesized complex and related Pd(II) and Pt(II) complexes

A new palladium(II) complex 1 of the condensation product of 2-(diphenylphosphino)benzaldehyde (dpba) and ethyl hydrazinoacetate (etha) was synthesized and characterized by elemental analyses, IR, and (1)H NMR spectroscopy. The bound ligand is a bidentate (PN chromophore), the remaining two coordination places being occupied by chloride ions in overall square planar geometry. The cytotoxic activity of the complex 1 and two related Pd(II) and Pt(II) complexes 2 and 3 was tested against a panel of four tumor cell lines. The activity of the complexes was similar to that of cisplatin, the most widely used metal-based antitumor drug. It is important to notice that complexes 2 and 3 were active to cisplatin-resistant U2-OS/Pt cells. Cell cycle alteration investigation, apoptotic assay and gelatin zymography in relation to invasion and metastasis of tumor cells, were performed with all the investigated complexes on Human cervix carcinoma (HeLa) cells. The results suggest that 1 has a similar effect to cisplatin, inducing apoptosis followed by arrest of cells in S phase of cell cycle, while 2 and 3 induce apoptosis without significant perturbations of cell cycle distribution.     

Evaluation of residue variability in a conformation‐specific context and during evolutionary sequence reconstruction narrows drug resistance selection in Abl1 tyrosine kinase

Diseases with readily available therapies may eventually prevail against the specific treatment by the acquisition of resistance. The constitutively active Abl1 tyrosine kinase known to cause chronic myeloid leukemia is an example, where patients may experience relapse after small inhibitor drug treatment. Mutations in the Abl1 tyrosine kinase domain (Abl1‐KD) are a critical source of resistance and their emergence depends on the conformational states that have been observed experimentally: the inactive state, the active state, and the intermediate inactive state that resembles Src kinase. Understanding how resistant positions and amino acid identities are determined by selection pressure during drug treatment is necessary to improve future drug development or treatment decisions. We carry out in silico site‐saturation mutagenesis over the Abl1‐KD structure in a conformational context to evaluate the in situ and conformational stability energy upon mutation. Out of the 11 studied resistant positions, we determined that 7 of the resistant mutations favored the active conformation of Abl1‐KD with respect to the inactive state. When, instead, the sequence optimization was modeled simultaneously at resistant positions, we recovered five known resistant mutations in the active conformation. These results suggested that the Abl1 resistance mechanism targeted substitutions that favored the active conformation. Further sequence variability, explored by ancestral reconstruction in Abl1‐KD, showed that neutral genetic drift, with respect to amino acid variability, was specifically diminished in the resistant positions. Since resistant mutations are susceptible to chance with a certain probability of fixation, combining methodologies outlined here may narrow and limit the available sequence space for resistance to emerge, resulting in more robust therapeutic treatments over time.     

In vivo analysis reveals substrate-gating mutants of a rhomboid intramembrane protease display increased activity in living cells

Intramembrane proteases hydrolyze peptide bonds within cell membranes. Recent crystal structures revealed that rhomboid intramembrane proteases contain a hydrated active site that opens to the outside of the cell, but is protected laterally from membrane lipids by protein segments. Using Escherichia coli rhomboid (GlpG) structures as a guide, we previously took a mutational approach to identify the GlpG gating mechanism that allows substrates to enter the active site laterally from the membrane. Mutations that weaken contacts keeping the gate closed increase enzyme activity and implicate transmembrane segment 5 as the substrate gate. Since these analyses were performed in vitro with pure proteins in detergent micelles, we have now examined GlpG in its natural environment, within the membrane of live E. coli cells. In striking congruity with in vitro analysis, gate-opening mutants in transmembrane segment 5 display up to a 10-fold increase in protease activity in living cells. Conversely, mutations in other parts of the protease, including the membrane-inserted L1 loop previously thought to be the gate, decrease enzyme activity. These observations provide evidence for the existence of both closed and open forms of GlpG in cells, and show that inter-conversion between them via substrate gating is rate limiting physiologically.     

The ultrastructure of pinealocytes in the pig

Summary Pinealocytes of female pigs were studied electron-microscopically and compared with those of other mammals. A prominent Golgi apparatus forming dense-cored vesicles was widely dispersed in the cytoplasm of the cell body. A very characteristic feature of the pig pinealocytes was the presence of membrane-bounded bodies showing wide variations in internal structure. Possible roles of the dense-cored vesicles and membrane-bounded bodies in secretory processes of pinealocytes are discussed.     

Factor Structure and Longitudinal Measurement Invariance of the Demand Control Support Model: An Evidence from the Swedish Longitudinal Occupational Survey of Health (SLOSH)

Objectives

To examine the factor structure and to evaluate the longitudinal measurement invariance of the demand-control-support questionnaire (DCSQ), using the Swedish Longitudinal Occupational Survey of Health (SLOSH).

Methods

A confirmatory factor analysis (CFA) and multi-group confirmatory factor analysis (MGCFA) models within the framework of structural equation modeling (SEM) have been used to examine the factor structure and invariance across time.

Results

Four factors: psychological demand, skill discretion, decision authority and social support, were confirmed by CFA at baseline, with the best fit obtained by removing the item repetitive work of skill discretion. A measurement error correlation (0.42) between work fast and work intensively for psychological demands was also detected. Acceptable composite reliability measures were obtained except for skill discretion (0.68). The invariance of the same factor structure was established, but caution in comparing mean levels of factors over time is warranted as lack of intercept invariance was evident. However, partial intercept invariance was established for work intensively.

Conclusion

Our findings indicate that skill discretion and decision authority represent two distinct constructs in the retained model. However removing the item repetitive work along with either work fast or work intensively would improve model fit. Care should also be taken while making comparisons in the constructs across time. Further research should investigate invariance across occupations or socio-economic classes.     

Comparison between carotid stenting and carotid endarterectomy in early outcome

Carotid artery stenting (CAS) is a widely used method in prevention of stroke for carotid artery stenosis as an alternative to surgical treatment. Initial studies reveal higher morbidity and mortality rates for CAS than acceptable standards for carotid endarterectomy (CEA). The aim of this study was to compare results in a series of CAS with concurrent risk-matched group of CEA patients. The study included two groups of 50 patients with internal carotid artery stenosis. We compared early outcome (30 days after procedure) in risk-matched groups of patients that underwent these procedures. Post procedural complications were equally frequent in both groups. There was no significant difference in perioperative complication rates (P = 0.871). Comparison of these two methods shows that CAS and CEA are competitive methods for treatment of carotid artery stenosis. Particularly in symptomatic patients with high risk for surgery CAS is alternative treatment.