Low accumulation of L90M in protease from subtype F HIV-1 with resistance to protease inhibitors is caused by the L89M polymorphism

BACKGROUND: This work evaluates the role of subtype F human immunodeficiency virus type 1 (HIV-1) protease (PR) substitutions L89M and L90M in viral replication and resistance to PR inhibitors (PIs). METHODS: Subtype B and F PR genes were subjected to site-directed mutagenesis, to create and reverse the methionine at positions 89 and 90. Viruses were re-created in cell culture, and their replicative capacity was assessed by fitness assay. Generated viruses were also phenotyped for PI resistance. RESULTS: The subtype F clone (89M90L) showed a replicative capacity comparable to that of the PI-susceptible subtype B clone (89L90L) and was more fit than the L89M mutated subtype B clone (89M90L). Both 89M90M subtype B and F clones presented the lowest fitness s values. The L89M mutation impacted phenotypic resistance to all PIs in half of the subtype F isolates but not in the subtype B isolates. Subtype F isolates presented a phenotypic profile similar to that of subtype B isolates when the M89L mutation was introduced. CONCLUSION: The L89M mutation in subtype F viruses is a high genetic barrier to the accumulation of the L90M resistance mutation and can function as a resistance mutation, depending on the presence of other polymorphisms in the subtype F PR backbone.     

Characterization and clinical impact of antinuclear antibodies in primary biliary cirrhosis

OBJECTIVES: The clinical impact of antinuclear antibodies in primary biliary cirrhosis is uncertain. We analyzed in detail the antinuclear antibodies reactivity of primary biliary cirrhosis patients and correlated the fine specificities observed with clinical, biochemical, and immunologic parameters. METHODS: A total of 96 consecutive primary biliary cirrhosis patients and 283 pathologic controls were studied. To dissect the fine antinuclear antibodies specificities we used different techniques, such as indirect immunofluorescence on cryostat tissue sections and cell culture (HEp-2 cells), counterimmunoelectrophoresis with thymus and spleen extracts, ELISA assays with recombinant Sp100 and purified gp210 and Lamin B receptor, and immunoblot with several recombinant nuclear and cytoplasmic antigens. RESULTS: Antinuclear antibodies were detected in 53% of patients, with the following hierarchy of specificities: 27% anti-Sp100, 16% "multiple nuclear dots," 16% anti-gp210, 16% anti-centromere, 7% XR1, 6% anti-lamin B receptor, 5% anti-SS-A/Ro, 5% anti-ribonucleoprotein, 4% XR2, 2% anti-SS-B/La, 2% perinuclear antineutrophil cytoplasmic antibodies, and 1% anti-double-stranded deoxyribonucleic acid. Several patients showed multiple specificities. The "multiple nuclear dots" pattern was detected more often in antimitochondrial antibodies negative patients. In particular, primary biliary cirrhosis specific antinuclear antibodies (anti-Sp100, anti-gp210, and anti-lamin B receptor) were detected in nine of 13 antimitochondrial negative primary biliary cirrhosis cases. Anti-gp210 was more frequent in patients with more pronounced cholestasis and more impaired liver function. CONCLUSIONS: Antinuclear antibodies reactivities are present in more than half of primary biliary cirrhosis patients and target diverse autoantigens located in distinct subnuclear structures. Anti-gp210 identifies a subgroup of primary biliary cirrhosis patients with more serious liver disease. Positivity for anti-Sp100, anti-gp210, and anti-lamin B receptor, either alone or in combination, may act as a serologic marker of antimitochondrial antibodies negative primary biliary cirrhosis.     

Cardiovascular Disease Prognostic Models in Latin America and the Caribbean: A Systematic Review

Background

Cardiovascular prognostic models guide treatment allocation and support clinical decisions. Whether there are valid models for Latin American and Caribbean (LAC) populations is unknown.

Pathways for the movements of ions during calcium-free perfusion and the induction of the 'calcium paradox'

The intracellular sodium content of cardiac cells in fish and amphibia, measured with either an isotope technique or with sodium-sensitive micro-electrodes, rises steeply from around 15 mmol/l in calcium-containing solution to as much as 70 mmol/l, during exposure to a Ca2+-free solution. This increase is associated with the development of spontaneous and prolonged action potentials so that the membrane may stabilise around -20 mV. On reperfusion with calcium-containing medium the membrane repolarises before a strong contracture develops. Inhibition of the Na-pump increases both the sodium gain and the subsequent calcium re-admission tension. A number of agents e.g. divalent cations, anti-arrhythmic drugs, local anaesthetics and Ca-channel blockers are able to prevent the development of the contracture but only if they are present during the calcium-free perfusion. They also inhibit the development of spontaneous electrical activity and the rise in Nai. The calcium re-admission contracture can be blocked in amphibian preparations voltage clamped around the resting potential during low calcium perfusion. From the known pharmacological action of these agents and the voltage and time dependence of the calcium channel, it is concluded that during calcium depletion, the prolongation of the action potentials is associated with a sustained entry of Na+ via the Ca-channels which leads to the rise in Nai. Once Nai has risen, these agents with the exception of Mn2+, a known inhibitor of the Na/Ca exchange, are unable to prevent the development of the contracture. This suggests that the re-admission contracture follows calcium uptake by way of the Na/Ca exchange.     

Familial gastric cancer

BACKGROUND: Familial aggregation of gastric cancer has pointed out to a possible hereditary and genetic factor involved in the carcinogenesis of this disease. The diffuse type gastric cancer patients are frequently younger and the tumor has locally infiltrative growth pattern early in its development. Observation of families with frequent early onset gastric cancer has led to the identification of a novel gene implicated in gastric cancer susceptibility: CDH1/E-cadherin. Diffuse familiar gastric cancer is defined as any family presenting: two first-degree relatives with diffuse gastric cancer, one of them with age under 50 years or at least 3 first-degree relatives irrespective age of onset. CASE REPORT: The family reported by us does not fit in any of the classification proposed. The precise identification of these families by clinical and molecular tools is of great importance. The case reported is an example of a family that probably is a form of hereditary gastric cancer not yet fully understood. CONCLUSION: Soon there will be new criteria, possibly including genetic and molecular characteristics.