A Coupling Approach for the Generation of α,α-Bis(enolate) Equivalents: Regioselective Synthesis of gem-Difunctionalized Ketones.

Regioselective α,α-difunctionalization adjacent to a ketone is a significant synthetic challenge. Here, we present a solution to this problem through the transition-metal-free coupling of esters with geminal bis(boron) compounds. This forms an α,α-bis(enolate) equivalent which can be trapped with electrophiles including alkyl halides and fluorinating agents. This presents an efficient, convergent synthetic strategy for the synthesis of unsymmetrical blocked ketones.

The relationship between inhibitors of the Wnt signalling pathway (sclerostin and Dickkopf-1) and carotid intima-media thickness in postmenopausal women with type 2 diabetes mellitus.

The aim of the study was to investigate the association of the extracellular inhibitors of Wnt/ß-catenin signalling sclerostin and Dickkopf-1 (Dkk-1) with carotid intima-media thickness (CIMT) in type 2 diabetes mellitus (T2DM). We performed a cross-sectional study including 40 T2DM postmenopausal women and 40 healthy controls. CIMT was measured by B-mode ultrasound. Serum sclerostin and Dkk-1 were measured by solid-phase enzyme-linked immunosorbent assay (ELISA). Serum sclerostin and Dkk-1 concentrations were significantly higher in T2DM group than in controls. There was a significant negative correlation between sclerostin and Dkk-1 and CIMT in T2DM (p = 0.0063 and p = 0.0017, respectively). After adjustment for potential confounders, associations remained significant only for sclerostin. These data suggest that sclerostin, an established modulator of the canonical Wnt signalling, may protect against progression of vascular complications in diabetic patients, possibly by attenuating upregulation of ß-catenin activity in the vascular cells.

Increased sclerostin serum levels associated with bone formation and resorption markers in patients with immobilization-induced bone loss.

CONTEXT: Sclerostin, a Wnt signaling antagonist on the osteoblasts produced by osteocytes, is regulated by mechanical strain and is implicated in the pathogenesis of disuse bone loss. There are no data on sclerostin in humans. OBJECTIVE: The aim of the study was to evaluate sclerostin in patients immobilized after stroke, compared with control subjects, and to analyze its relationship with markers of bone formation and resorption. DESIGN: This was a cross-sectional study. SETTING AND PATIENTS: We studied 40 postmenopausal women immobilized after a single episode of stroke 6 months or longer after onset, and 40 postmenopausal women from the general community. Bone status was assessed by quantitative ultrasound measurements at the calcaneus. Bone alkaline phosphatase (b-AP), carboxy-terminal telopeptide of type I collagen (CrossLaps), and sclerostin were evaluated by ELISA. We also used ELISA to measure serum levels of Dickkopf-1, another soluble inhibitor of Wnt/beta-catenin signaling, highly expressed by osteocytes. RESULTS: Immobilized patients had higher sclerostin serum levels (median 0.975 ng/ml; 25th to 75th percentiles 0.662-1.490) than controls (median 0.300 ng/ml; 25th to 75th percentiles 0.165-0.400: P < 0.0001) and an increased bone turnover with a more significant rise in bone resorption (CrossLaps) than formation (b-AP) markers. Sclerostin correlated negatively with b-AP (r = -0.911; P < 0.0001) and positively with CrossLaps (r = 0.391; P = 0.012). Dickkopf-1 did not significantly differ between the groups. Patients also had quantitative ultrasound measurements index lower than controls (P < 0.001). CONCLUSIONS: This study shows for the first time that long-term immobilized patients present hypersclerostinemia associated with reduced bone formation, and suggests that sclerostin could be a link between mechanical unloading and disuse osteoporosis in humans.

Current management of intermittent claudication: the role of pharmacological and nonpharmacological symptom-directed therapies.

Lower extremity peripheral arterial disease (PAD) is a manifestation of atherosclerosis, with a prevalence ranging from 4% to 12% in the adult population and increasing up to 20% in older individuals. Intermittent claudication (IC) may markedly impair walking ability, overall functional status and quality of life. PAD is a marker of systemic atherosclerosis and is associated with increased cardiovascular morbidity and mortality. However, leg disease usually runs a rather benign course in claudicant patients, with only about 1% to 3% of them ever requiring a major amputation over a 5-year period. The goals of treatment for claudication are to relieve exertional symptoms, and improve walking capacity and quality of life. Therapeutic strategies aimed at reducing systemic cardiovascular risk burden and prolonging survival, including intensive risk factor modification and antiplatelet therapy, should be implemented in all patients with PAD. Supervised exercise training has proven the most effective conservative treatment for symptomatic relief of IC. Current evidence for drug therapy of IC supports the use of cilostazol as a first-line drug. Other drugs with more limited evidence of benefit for claudication include pentoxifylline and naftidrofuryl. Endovascular or surgical revascularization is indicated for selected patients with vocation- or lifestyle-limiting claudication who are unresponsive to exercise and pharmacotherapy. New drug candidates for managing claudication symptoms include propionyl-L-carnitine and statins. Preliminary studies suggest that therapeutic angiogenesis holds promise for future treatment of IC.

Therapeutic perspectives.

Osteoporosis and atherosclerosis are linked by biological association. This encourages the search for therapeutic strategies having both cardiovascular and skeletal beneficial effects. Among drugs that may concordantly enhance bone density and reduce the progression of atherosclerosis we can include bisphosphonates (BP), statins, ß -blockers, and possibly anti-RANKL antibodies. Available data come from experimental animals and human studies. All these treatments however lack controlled clinical studies designed to demonstrate dual-action effects.

Pamidronate and osteoporosis prevention in liver transplant recipients.

Osteoporosis is a common complication in patients with end-stage liver disease and after orthotopic liver transplantation (LT), with resulting increasing fracture rate. In this study, we investigated the role of treatment with pamidronate in preventing further bone loss after LT. Eighty-five patients with end-stage liver disease were included in the study. Pamidronate 30 mg was given intravenously every 3 months after LT for the duration of 1 year to 43 patients with osteopenia or osteoporosis prior LT. The remainders served as controls. All patients received a supplementation of calcium and vitamin D. Bone mineral density (BMD) at the lumbar spine and the femoral neck, and markers of bone metabolism were measured before and 12 months after LT. Sixty-two BMD were available at 12 months; only paired BMD were evaluated. A significant increase in lumbar spine BMD was observed in pamidronate treated patients. No change was evident in controls. Femoral neck BMD decreased in both treated and untreated patients. Osteocalcin serum levels and deoxypyridinoline urinary excretion were significantly reduced by treatment. Our study suggests that pamidronate decreases bone turnover and is effective in preventing the course of bone loss after LT, however the efficacy, at the dosage regimen employed and in a follow-up of 12 months, appears to be limited to trabecular bone, with no effect on the cortical structure of the femur.

Association of high alpha2-Heremans-Schmid glycoprotein/fetuin concentration in serum and intima-media thickness in patients with atherosclerotic vascular disease and low bone mass.

OBJECTIVE: Alpha2-Heremans-Schmid glycoprotein (AHSG; fetuin), a member of the cystatin superfamily of cysteine protease inhibitors involved in vascular pathology and bone metabolism, has been reported to be reduced in patients with atherosclerosis and medial calcification related to end stage renal disease or dialysis. No data on fetuin in patients with peripheral artery disease associated with low bone mass and normal renal function are available in the literature. In the present study we evaluated serum fetuin concentrations, bone mass, and markers of bone turnover in patients with atherosclerosis of peripheral vessels and normal kidney function. PATIENTS AND METHODS: Ninety consecutive patients with evidence of atherosclerotic plaques at the common carotid or femoral artery were studied. Severity grade of disease was documented by ultrasound measurement of intima-media thickness (IMT). Fasting serum levels of fetuin were measured by sandwich enzyme immunoassay. MAIN RESULTS: The mean patient serum concentration of fetuin was 57.68+/-13.6 ng/ml, significantly higher than that of control subjects (41.6+/-7.6 ng/ml; p<0.001). The mean serum concentration of bone-specific alkaline phosphatase (BAP) were 8.4+/-2.3 microg/l, significantly lower than controls (13.6+/-1.6 microg/l; p<0.001). Fetuin was correlated with IMT (r=0.8530; p<0.0001) and inversely correlated with BAP (r=-0.5503; p<0.0001). Patients had a vertebral and femoral bone mass significantly lower than controls. CONCLUSION: This study documented for the first time that, in patients with atherosclerosis of peripheral vessels, serum fetuin levels were higher than in healthy subjects, and correlated with the severity of disease; further studies are required to analyse the role of AHSG as an independent predictor of atherosclerotic disease and low bone mass in patients with normal renal function.

The sera from individuals suffering from cutaneous leishmaniasis due to Leishmania brazilensis present antibodies against parasitic conserved proteins, but not their human counterparts.

Sera from individuals suffering from leishmaniasis have been shown to strongly react against conserved proteins from the parasite, such as ribosomal, histones and heat-shock proteins. Some of these proteins have also been described as immunogenic in several auto-immune syndromes, and the detection of antibodies against them is considered to be indicative of disorder of the immune system. In this paper, we investigate whether there is any relationship between the recognition of some conserved proteins from leishmania braziliensis by individuals suffering from cutaneous (CL) and mucocutaneous (MCL) leishmaniasis, and the recognition of the human homologues of these antigens found in sufferers from autoimmune diseases. Our findings reveal that the immune response generated during CL and MCL is elicited specifically by the parasitic histone H1 and Hsp70, since the CL and MCL sera do not react against their human counterparts. In addition, evidence is presented showing the specific recognition of human proteins by the autoimmune sera, showing only a weak cross-reaction with the most divergent regions of the parasitic proteins.

Molecular characterization of the Leishmania braziliensis L6 ribosomal protein.

By screening a Leishmania braziliensis complementary DNA library with a pool of sera from leishmaniasis patients, the gene coding for L6 ribosomal protein was isolated. The sequence, genomic organization, and transcription of this gene are described in this article. The sequence analysis of the L. braziliensis L6 gene shows a single open reading frame, which codes for a protein of 192 amino acids (aa) with a hypothetical molecular mass of 20.9 kDa. The protein exhibits significant sequence similarity to L6 ribosomal proteins from higher eukaryotes and yeast. Thus, the L. braziliensis L6 protein contains 4 functional motifs, which are located at equivalent positions in other L6 ribosomal proteins described previously. Interestingly, the L6 ribosomal protein from L. braziliensis contains a specific region of 14 aa and a tyrosine kinase motif, which is absent in human and C. elegans L6 protein. The locus coding the L. braziliensis L6 ribosomal protein is formed by 2 gene copies arranged in tandem and located in a chromosome of approximately 0.9. Mb. The genes are actively transcribed as 2 polyadenylated transcripts of approximately 1.15 and 0.85 kb, which differ in their steady-state level and stability.

Molecular and immunological characterization of L14 ribosomal protein from Leishmania braziliensis.

The isolation and molecular characterization of the gene coding for L14 ribosomal protein from L. braziliensis is described. There are 2 copies of the gene per haploid genome, repeated in a head-to-tail tandem orientation and located in a single chromosome of approximately 950 kb. Northern blot analyses indicate the presence of a single transcript of 0.95 kb which is up-regulated when parasites reach the stationary growth phase. L. braziliensis L14 gene codes for a 175 amino acid long polypeptide showing 75-83% sequence identity with L14 proteins from trypanosomatids and approximately 25% with its counterparts from higher eukaryotic organisms. L14 ribosomal proteins from trypanosomatids and higher eukaryotes share along their molecules a similar distribution pattern of theoretically functional domains. L. braziliensis L14 recombinant protein is not recognized by sera from cutaneous leishmaniasis patients. Immunization of mice with one dose of L14 recombinant protein and a second dose of L14 protein covalently linked to the HSP70 from Trypanosoma cruzi induces a high antibody level against this L14 protein, which is mostly of the IgG2a subtype, as well as a strong increase in splenocyte proliferation index.

Development of a rapid polymerase chain reaction-ELISA assay using polystyrene beads for the detection of Toxoplasma gondii DNA.

AIMS: To develop a rapid colourimetric assay for the detection of Toxoplasma gondii DNA using polystyrene beads as solid support. METHODS AND RESULTS: A nested-polymerase chain reaction (PCR)-ELISA assay for the detection of T. gondii DNA was standardized by optimizing the hybridization time and probe concentration. Its detection threshold was then determined and compared with Southern blotting hybridization. These were found to be equivalent, but the PCR-ELISA-beads test is easier to perform and the turnaround time is much shorter than with Southern blot. CONCLUSIONS: The PCR-ELISA-beads assay is a valuable tool for the detection of T. gondii DNA. SIGNIFICANCE AND THE IMPACT OF THE STUDY: Our results demonstrate that this PCR-ELISA assay, using polystyrene beads, can be used as a routine diagnostic test for the detection of T. gondii in clinical laboratories.

Analysis of NLS and rRNA binding motifs in the L25 ribosomal protein from Leishmania (viannia) braziliensis: investigation of its diagnostic capabilities.

A cDNA clone codifying ribosomal protein L25 was isolated from a Leishmania braziliensis cDNA gene library. The alignment of the amino acid sequence deduced from this gene with other proteins revealed that this protein is related to the L23/25 rihosomal protein family. This is so because this protein shows, in its C-terminal end, the rRNA binding domains characteristic of these proteins and at the N-terminal end the NLS sequence necessary for its entry into the nucleus. Southern blot analysis showed 2 copies of gene L25 per genome arranged in tandem position and pointing in the same direction. Northern blot analysis showed that this gene is transcribed in 2 mRNAs when parasite promastigotes are in the logarithmic phase. In order to analyse the antigenic properties of L. braziliensis RPL25, it was purified as a recombinant protein and ELISA-tested against cutaneous, mucocutaneous and Chagasic sera. The results indicate that the recombinant RPL25 from L. braziliensis presents a non-specific reaction that disqualifies it for the diagnosis of cutaneous leishmaniasis. In contrast, some of the synthetic peptides derived from its sequence may serve as promising tools for the diagnosis of this disease.

Cloning and molecular characterization of the cDNA encoding histone H1 from Leishmania braziliensis.

The isolation and molecular characterization of the histone H1-encoding gene from Leishmania braziliensis was carried out. The gene is present in the genome as a single copy and transcribed as a polyadenylated transcript of 830 nucleotides. The deduced amino acid sequence has in its central region the DNA binding K-[K/R]-A-A-[A/P] motif, which is repeated in tandem 9 times.

Mapping of the antigenic determinants of the T. cruzi kinetoplastid membrane protein-11. Identification of a linear epitope specifically recognized by human Chagasic sera.

The high variability among strains and isolates of Trypanosoma cruzi and the existence of shared antigenic determinants with other pathogens, particularly with members of the Leishmania genus make difficult the specific diagnosis of Chagas' disease. The data reported in this paper show that the T. cruzi KMP11 protein is an immunodominant antigen highly recognized by the sera from chagasic and leishmaniasis patients. By the use of amino- and carboxyl-terminal truncated KMP11 recombinant proteins and synthetic peptides, evidence is provided that while the sera from chagasic patients recognize linear peptides the sera from patients with visceral leishmaniasis must be predominantly directed against conformational epitopes. We found that a particular linear determinant, located in the carboxyl-terminal region of the protein, is recognized with high specificity and sensitivity only by sera from Chagas' disease patients, suggesting it could be a good candidate for differential serodiagnosis of Chagas' disease.

Small-scale isolation of high molecular weight DNA from Leishmania braziliensis.

In this paper, we report a method for isolation of high molecular weight DNA from Leishmania promastigotes. This technique is especially indicated for small-scale purification of DNA suitable for the construction of highly representative genomic libraries. In our protocol, lysis buffer is compatible with RNase treatment, avoiding an additional precipitation step and consequent shearing of DNA. In order to prove the quality of the DNA isolated by this method, a Leishmania braziliensis genomic library was constructed, and an L. braziliensis KMP-11 gene was cloned after screening the library with a heterologous probe.