Efficacy of home-based peer counselling to promote exclusive breastfeeding: a randomised controlled trial

BACKGROUND

Exclusive breastfeeding is recommended worldwide but not commonly practised. We undertook a randomised controlled study of the efficacy of home-based peer counselling to increase the proportion of exclusive breastfeeding among mothers and infants residing in periurban Mexico City.

METHODS

Two intervention groups with different counselling frequencies, six visits (44) and three visits (52), were compared with a control group (34) that had no intervention. From March, 1995, to September, 1996, 170 pregnant women were identified by census and invited to participate in the study. Home visits were made during pregnancy and early post partum by peer counsellors recruited from the same community and trained by La Leche League. Data were collected by independent interview. Exclusive breastfeeding was defined by WHO criteria.

FINDINGS

130 women participated in the study. Only 12 women refused participation. Study groups did not differ in baseline factors. At 3 months post partum, exclusive breastfeeding was practised by 67% of six-visit, 50% of three-visit, and 12% of control mothers (intervention groups vs controls, p<0.001; six-visit vs three-visit, p=0.02). Duration of breastfeeding was significantly (p=0.02) longer in intervention groups than in controls, and fewer intervention than control infants had an episode of diarrhoea (12% vs 26%, p=0.03).

INTERPRETATION

This is the first reported community-based randomised trial of breastfeeding promotion. Early and repeated contact with peer counsellors was associated with a significant increase in breastfeeding exclusivity and duration. The two-fold decrease in diarrhoea demonstrates the importance of breastfeeding promotion to infant health.

Dengue hemorrhagic fever in Cuba, 1981: a retrospective seroepidemiologic study

In Cuba, 2 epidemics of dengue virus occurred: 1 caused by DEN-1 in 1977 and 1 caused by DEN-2 in 1981. The latter was associated with cases of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). To study viral risk factors for DHF/DSS, a retrospective seroepidemiological survey was conducted in Cerro, a densely populated district in Havana City. The prevalence of plaque reduction neutralizing antibodies to DEN-1 and DEN-2 viruses was measured in 1,295 individuals (children and adults). Of these, 43.7% were immune to DEN-1 virus and 23.6% to DEN-2 virus. Of those individuals who were immune, 26.1% were immune to DEN-1 virus only, 6% to DEN-2 virus only, and 17.6% to both viruses. The DEN-2 virus infection rate in DEN-1 immune individuals was 3.8 times higher than in non-immune individuals. The 5 DHF/DSS cases in the sample had evidence of DEN-1 virus plus DEN-2 virus infections. Three were children and 2 were young adults. No cases were found in individuals infected with DEN-1 virus or DEN-2 virus only. Children infected by DEN-1 virus followed by DEN-2 virus had a high risk of acquiring DHF/DSS. Blacks and whites were equally infected with DEN-1 and DEN-2 viruses.

The crystal structure of the PX domain from p40(phox) bound to phosphatidylinositol 3-phosphate

More than 50 human proteins with a wide range of functions have a 120 residue phosphoinositide binding module known as the PX domain. The 1.7 A X-ray crystal structure of the PX domain from the p40(phox) subunit of NADPH oxidase bound to PtdIns(3)P shows that the PX domain embraces the 3-phosphate on one side of a water-filled, positively charged pocket and reveals how 3-phosphoinositide specificity is achieved. A chronic granulomatous disease (CGD)-associated mutation in the p47(phox) PX domain that abrogates PtdIns(3)P binding maps to a conserved Arg that does not directly interact with the phosphoinositide but instead appears to stabilize a critical lipid binding loop. The SH3 domain present in the full-length protein does not affect soluble PtdIns(3)P binding to the p40(phox) PX domain.

Epidemiologic studies on Dengue in Santiago de Cuba, 1997

A small, isolated outbreak of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) due to dengue virus type 2 (DEN-2) was documented in Santiago de Cuba on the island of Cuba beginning in January 1997. There were 205 DHF/DSS cases, all in persons older than age 15 years. All but three had evidence of a prior dengue infection, with the only known opportunity being the islandwide dengue virus type 1 (DEN-1) epidemic of 1977-1979. Virtually complete clinical and laboratory surveillance of overt disease was achieved. From December 1997 to January 1998, a random, age-stratified serum sample was obtained from 1,151 persons in 40 residential clusters in Santiago. Sera were tested for DEN-1 and DEN-2 neutralizing antibodies. The prevalence of DEN-2 antibodies in children age 15 years and under, born after the 1981 DEN-2 epidemic, was taken as the 1997 DEN-2 infection rate. This was adjusted slightly to accommodate observed cases, resulting in an estimated infection rate of 4.3%. Dengue fever and DHF/DSS attack rates were calculated from estimated total primary and secondary DEN-2 infections. Only 3% of 13,116 primary infections were overt. The DHF/DSS attack rate for adults of all ages was 420 per 10,000 secondary DEN-2 infections.

Receptor recognition by gp130 cytokines

Cytokines of the gp130 family exert their diverse biological effects by formation of stable high affinity transmembrane receptor complexes that are characterized by the presence of the shared transmembrane signalling receptor gp130. Different gp130 ligands form signalling complexes that vary in both composition and stoichiometry. Analysis of the three-dimensional structure of selected ligands and receptor elements indicates that ligands display three topologically conserved receptor recognition epitopes that interact with complementary ligand recognition elements. The composition of the signalling complex and downstream biological responses is defined by the relative affinity of different receptor components for these epitopes. The detailed structure of receptor recognition epitopes indicates that the generation of small molecule cytokine mimetics may be a feasible objective.

The leukemia-associated AML1 (Runx1)--CBF beta complex functions as a DNA-induced molecular clamp

We have determined the structure, at 2.6 A resolution, of the AML1 (Runx1) Runt domain--CBF beta--DNA ternary complex, the most common target for mutations in human leukemia. The structure reveals that the Runt domain DNA binding mechanism is unique within the p53 family of transcription factors. The extended C-terminal 'tail' and 'wing' elements adopt a specific DNA-bound conformation that clamps the phosphate backbone between the major and minor grooves of the distorted B-form DNA recognition site. Furthermore, the extended 'tail' mediates most of the NF-kappa B/Rel-like base-specific contacts in the major groove. The structure clearly explains the molecular basis for the loss of DNA binding function of the Runt domain--CBF beta complex as a consequence of the human disease-associated mutations in leukemogenesis and cleidocranial dysplasia.

Crystal structure of a cytokine-binding region of gp130

The structure of the cytokine-binding homology region of the cell surface receptor gp130 has been determined by X-ray crystallography at 2.0 A resolution. The beta sandwich structure of the two domains conforms to the topology of the cytokine receptor superfamily. This first structure of an uncomplexed receptor exhibits a similar L-shaped quaternary structure to that of ligand-bound family members and suggests a limited flexibility in relative domain orientation of some 3 degrees. The putative ligand-binding loops are relatively rigid, with a phenylalanine side chain similarly positioned to exposed aromatic residues implicated in ligand binding for other such receptors. The positioning and structure of the N-terminal portion of the polypeptide chain have implications for the structure and function of cytokine receptors, such as gp130, which contain an additional N-terminal immunoglobulin-like domain.

Effect of Glass Fiber Surface Treatments on Mechanical Strength of Epoxy Based Composite Materials

Sizing glass fibers with silane coupling agents enhances the adhesion and the durability of the fiber/polymer matrix interface in composite materials. There are several tests to determine the interfacial strength between a fiber and resin, but all of them present difficulties in interpreting the results and/or sample preparation. In this study, we observed the influence of different aminosilanes fiber coatings on the resistance of epoxy-based composite materials using a very easy fractographic test. In addition, we tried a new fluorescence method to get information on a molecular level precisely at the interface. Strength was taken into account from two standpoints: (i) mechanical strength and (ii) the resistance to hydrolysis of the interface in oriented glass-reinforced epoxy-based composites. Three silanes: gamma-aminopropyltriethoxysilane, gamma-Aminopropylmethyldiethoxysilane, and gamma-Aminopropyldimethylethoxysilane were used to obtain different molecular structures at the interface. It was concluded that: (i) the more accessible amine groups are, the higher the interface rigidity is; (ii) an interpenetrating network mechanism seems to be the most important for adhesion and therefore to the interfacial strength; and (iii) the higher the degree of crosslinking in the silane coupling layer is, the higher the hydrolytic damage rate is.

Structural basis for the heterodimeric interaction between the acute leukaemia-associated transcription factors AML1 and CBFbeta

Mutations in the genes encoding the interacting proteins AML1 and CBFbeta are the most common genetic abnormalities in acute leukaemia, and congenital mutations in the related AML3 gene are associated with disorders of osteogenesis. Furthermore, the interaction of AML1 with CBFbeta is essential for haematopoiesis. We report the 2.6 A resolution crystal structure of the complex between the AML1 Runt domain and CBFbeta, which represents a paradigm for the mode of interaction of this highly conserved family of transcription factors. The structure demonstrates that point mutations associated with cleidocranial dysplasia map to the conserved heterodimer interface, suggesting a role for CBFbeta in osteogenesis, and reveals a potential protein interaction platform composed of conserved negatively charged residues on the surface of CBFbeta.

Crystal structure of catalase HPII from Escherichia coli

BACKGROUND

Catalase is a ubiquitous enzyme present in both the prokaryotic and eukaryotic cells of aerobic organisms. It serves, in part, to protect the cell from the toxic effects of small peroxides. Escherichia coli produces two catalases, HPI and HPII, that are quite distinct from other catalases in physical structure and catalytic properties. HPII, studied in this work, is encoded by the katE gene, and has been characterized as an oligomeric, monofunctional catalase containing one cis-heme d prosthetic group per subunit of 753 residues.

RESULTS

The crystal structure of catalase HPII from E. coli has been determined to 2.8 A resolution. The asymmetric unit of the crystal contains a whole molecule, which is a tetramer with accurate 222 point group symmetry. In the model built, that includes residues 27-753 and one heme group per monomer, strict non-crystallographic symmetry has been maintained. The crystallographic agreement R-factor is 20.1% for 58,477 reflections in the resolution shell 8.0-2.8 A.

CONCLUSIONS

Despite differences in size and chemical properties, which were suggestive of a unique catalase, the deduced structure of HPII is related to the structure of catalase from Penicillium vitale, whose sequence is not yet known. In particular, both molecules have an additional C-terminal domain that is absent in the bovine catalase. This extra domain contains a Rossmann fold but no bound nucleotides have been detected, and its physiological role is unknown. In HPII, the heme group is modified to a heme d and inverted with respect to the orientation determined in all previously reported heme catalases. HPII is the largest catalase for which the structure has been determined to almost atomic resolution.

Tyrosine residues in phospholipase Cgamma 2 essential for the enzyme function in B-cell signaling

Phospholipase Cgamma (PLCgamma) isoforms are regulated through activation of tyrosine kinase-linked receptors. The importance of growth factor-stimulated phosphorylation of specific tyrosine residues has been documented for PLCgamma1; however, despite the critical importance of PLCgamma2 in B-cell signal transduction, neither the tyrosine kinase(s) that directly phosphorylate PLCgamma2 nor the sites in PLCgamma2 that become phosphorylated after stimulation are known. By measuring the ability of human PLCgamma2 to restore calcium responses to the B-cell receptor stimulation or oxidative stress in a B-cell line (DT40) deficient in PLCgamma2, we have demonstrated that two tyrosine residues, Tyr(753) and Tyr(759), were important for the PLCgamma2 signaling function. Furthermore, the double mutation Y753F/Y759F in PLCgamma2 resulted in a loss of tyrosine phosphorylation in stimulated DT40 cells. Of the two kinases that previously have been proposed to phosphorylate PLCgamma2, Btk, and Syk, purified Btk had much greater ability to phosphorylate recombinant PLCgamma2 in vitro, whereas Syk efficiently phosphorylated adapter protein BLNK. Using purified proteins to analyze the formation of complexes, we suggest that function of Syk is to phosphorylate BLNK, providing binding sites for PLCgamma2. Further analysis of PLCgamma2 tyrosine residues phosphorylated by Btk and several kinases from the Src family has suggested multiple sites of phosphorylation and, in the context of a peptide incorporating residues Tyr(753) and Tyr(759), shown preferential phosphorylation of Tyr(753).

Structure of the heme d of Penicillium vitale and Escherichia coli catalases

A heme d prosthetic group with the configuration of a cis-hydroxychlorin gamma-spirolactone has been found in the crystal structures of Penicillium vitale catalase and Escherichia coli catalase hydroperoxidase II (HPII). The absolute stereochemistry of the two heme d chiral carbon atoms has been shown to be identical. For both catalases the heme d is rotated 180 degrees about the axis defined by the alpha-gamma-meso carbon atoms, with respect to the orientation found for heme b in beef liver catalase. Only six residues in the heme pocket, preserved in P. vitale and HPII, differ from those found in the bovine catalase. In the crystal structure of the inactive N201H variant of HPII catalase the prosthetic group remains as heme b, although its orientation is the same as in the wild type enzyme. These structural results confirm the observation that heme d is formed from protoheme in the interior of the catalase molecule through a self-catalyzed reaction.

Lamotrigine serum concentration-to-dose ratio: influence of age and concomitant antiepileptic drugs and dosage implications

Using bivariate and multivariate methods, we retrospectively analyzed the influence of patient age and the use of concomitant antiepileptic drugs (AEDs) on the lamotrigine (LTG) concentration-to-dose (C/D) ratio in samples from 164 patients (68 children, 96 adults) with epilepsy receiving LTG alone (n = 28) or in combination with various antiepileptic drugs (n = 136). The LTG C/D ratio increased with age in children receiving LTG alone (r = 0.60, p < 0.01), but decreased with age in adults receiving LTG and inducers (r = -0.42, p < 0.001). In patients receiving LTG and inducers, the ratio was statistically lower in those younger than 9 years of age (0.23 +/- 0.08) and older than 30 years of age (0.32 +/- 0.15) than it was in those between 9 and 30 years of age (0.44 +/- 0.15). The mean LTG C/D ratio was 0.37 +/- 0.15 in patients receiving LTG and inducers (n = 92), 0.84 +/- 0.41 in patients receiving LTG alone (n = 28), 1.09 +/- 0.44 in those receiving LTG with VPA plus inducers (n = 17), and 3.41 +/- 1.18 in those receiving LTG and VPA (n = 27). Differences in the LTG C/D ratio between treatment groups were similar in children and in adults. We reached the following conclusions: The LTG C/D ratio increased with age in children but may decrease with age in adults receiving concomitant enzyme-inducing AEDs; the LTG C/D ratio was 10 times lower in patients receiving LTG and inducers than in those receiving LTG and VPA (in both children and adults), and this difference was higher than the four-fold difference described for LTG half-life and the two-fold differences currently used in LTG dosage.

Energetic and functional contribution of residues in the core binding factor beta (CBFbeta ) subunit to heterodimerization with CBFalpha

Core-binding factors (CBFs) are a small family of heterodimeric transcription factors that play critical roles in several developmental pathways, including hematopoiesis and bone development. Mutations in CBF genes are found in leukemias and bone disorders. CBFs consist of a DNA-binding CBFalpha subunit (Runx1, Runx2, or Runx3) and a non-DNA-binding CBFbeta subunit. CBFalpha binds DNA in a sequence-specific manner, whereas CBFbeta enhances DNA binding by CBFalpha. Recent structural analyses of the DNA-binding Runt domain of CBFalpha and the CBFbeta subunit identified the heterodimerization surfaces on each subunit. Here we identify amino acids in CBFbeta that mediate binding to CBFalpha. We determine the energy contributed by each of these amino acids to heterodimerization and the importance of these residues for in vivo function. These data refine the structural analyses and further support the hypothesis that CBFbeta enhances DNA binding by inducing a conformational change in the Runt domain.

Xanthones from Gentianella amarella ssp. acuta with acetylcholinesterase and monoamine oxidase inhibitory activities

Two new xanthone glycosides, corymbiferin 3-O-beta-D-glucopyranoside (1) and swertiabisxanthone-I 8'-O-beta- d-glucopyranoside (2), were isolated from Gentianella amarella ssp. acuta, along with eight known xanthones: triptexanthoside C, veratriloside, corymbiferin 1-O-glucoside, swertianolin, norswertianolin, swertiabisxanthone-I, bellidin, and bellidifolin, four of them identified for the first time in G. amarella ssp. acuta. The isolation was conducted mainly by centrifugal partition chromatography, and the structures of the isolated compounds were established on the basis of spectrometric data including 2D NMR and mass spectrometry. Xanthones were weakly active against acetylcholinesterase (AChE), except triptexanthoside C, which inhibited AChE with an IC(50) of 13.8 +/- 1.6 microM. Some compounds were active against monoamine oxidases (MAO): bellidin and bellidifolin showed interesting inhibitory activity of MAO A, while swertianolin, the 8-O-glucopyranoside form of bellidifolin, gave 93.6% inhibition of MAO B activity at 10(-5) M.

Structure of catalase HPII from Escherichia coli at 1.9 A resolution

Catalase HPII from Escherichia coli, a homotetramer of subunits with 753 residues, is the largest known catalase. The structure of native HPII has been refined at 1.9 A resolution using X-ray synchrotron data collected from crystals flash-cooled with liquid nitrogen. The crystallographic agreement factors R and R(free) are respectively 16.6% and 21.0%. The asymmetric unit of the crystal contains a whole molecule that shows accurate 222-point group symmetry. The structure of the central part of the HPII subunit gives a root mean square deviation of 1.5 A for 477 equivalencies with beef liver catalase. Most of the additional 276 residues of HPII are located in either an extended N-terminal arm or in a C-terminal domain organized with a flavodoxin-like topology. A small number of mostly hydrophilic interactions stabilize the relative orientation between the C-terminal domain and the core of the enzyme. The heme component of HPII is a cis-hydroxychlorin gamma-spirolactone in an orientation that is flipped 180 degrees with respect to the orientation of the heme found in beef liver catalase. The proximal ligand of the heme is Tyr415 which is joined by a covalent bond between its Cbeta atom and the Ndelta atom of His392. Over 2,700 well-defined solvent molecules have been identified filling a complex network of cavities and channels formed inside the molecule. Two channels lead close to the distal side heme pocket of each subunit suggesting separate inlet and exhaust functions. The longest channel, that begins in an adjacent subunit, is over 50 A in length, and the second channel is about 30 A in length. A third channel reaching the heme proximal side may provide access for the substrate needed to catalyze the heme modification and His-Tyr bond formation. HPII does not bind NADPH and the equivalent region to the NADPH binding pocket of bovine catalase, partially occluded in HPII by residues 585-590, corresponds to the entrance to the second channel. The heme distal pocket contains two solvent molecules, and the one closer to the iron atom appears to exhibit high mobility or low occupancy compatible with weak coordination.

MC1R: three novel variants identified in a malignant melanoma association study in the Spanish population

The human melanocortin-1 receptor (MC1R) gene, which plays a crucial role in pigmentation, also appears to be important in malignant melanoma (MM). This case-control study in the Spanish population included 116 consecutive MM patients and 188 controls frequency matched for sex and age. Sequence analysis of the entire coding region of MC1R was performed, identifying 21 variants, all of them previously reported except for three novel non-synonymous changes: Ser41Phe, Met128Thr and Asn281Ser. Simulated structural analyses suggested disruption of the local structure around Phenylalanine 41, possible destabilization of the hydrophobic interior of the molecule in Threonine 128 and that Asparagine 281 could be in a region of functional importance. The fact that these three novel variants were not present in 1,000 healthy individuals tested adds further weight to them having putative adverse effects on the functional protein. Six variants, all non-synonymous changes, were individually associated with MM risk (Arg160Trp, Asp294His, Val60Leu, Val92Met, Ile155Thr and Arg163Gln). Carrying two non-synonymous variants was associated with much higher risk of MM (odds ratio: 10.44, 95% confidence interval = 4.48-24.33, P = 5 x 10(-8)) and haplotype analysis, verified by cloning, confirmed that this is predominantly due to carrying each on a different chromosome. Our results suggest that both red hair colour (RHC) and non-red hair colour variants, and possibly other rare non-synonymous variants, in MC1R are implicated in the development of MM. In addition to carrying MC1R variant alleles, having blond/red hair and childhood sunburns were independent risk factors for MM.

Crystal structure and functional dissection of the cytostatic cytokine oncostatin M

BACKGROUND

The cytokine oncostatin M (OSM) inhibits growth of certain tumour-derived cells, induces proliferation in other cell types (e.g. haemangioblasts) and is a mediator of inflammatory responses. Its mechanism of action is via specific binding to gp130 and either the leukaemia inhibitory factor receptor (LIFR) or oncostatin M receptor (OSMR) systems at the cell surface to form an active signalling complex.

RESULTS

We report here the crystal structure of human oncostatin M (hOSM) along with mutagenesis data which map the receptor-binding epitopes of the molecule. The structure was determined to a resolution of 2.2 A and conforms to the haematopoietin cytokine up-up-down-down four-helix bundle topology. The site 2 epitope, responsible for gp130 binding, is centred around Gly120 which forms a 'dimple' on the surface of the molecule located on helices A and C. The site 3 motif, responsible for LIFR and OSMR binding, consists of a protruding Phe160/Lys163 pair located at the start of helix D.

CONCLUSIONS

The data presented allow functional dissection of the receptor-binding interfaces to atomic resolution. Modelling suggests that the gp130 residue Phe169 packs into the site 2 dimple in an analogous fashion to structurally equivalent residues at the growth hormone-growth hormone receptor interface, implying that certain key features may underlie recognition across the whole cytokine/receptor superfamily. Conversely, detailed comparison of the available structures suggests that variations on a common theme dictate the specificity of receptor-ligand interactions within the gp130 family of cytokines.

Dengue haemorrhagic fever in Cuba. II. Clinical investigations

Clinical and serological studies were carried out on 114 patients admitted to hospital in Havana, Cuba with Dengue Haemorrhagic Fever and Dengue Shock Syndrome (DHF/DSS). Serological confirmation of dengue was obtained in 90% of cases, with 5% of cases primary and 95% secondary. Fever, haemorrhagic manifestations, vomiting and headache were the most frequent signs and symptoms. Among haemorrhagic manifestations, petechiae and vaginal bleeding were reported in a larger number of patients. 21 patients presented shock and, of these, 20 were secondary infections. The disease appeared more frequently in white persons and in women. The aetiopathogenicity of the syndromes is discussed. 95% of the cases could be explained on the basis of the secondary infection hypothesis.

Efficacy and safety of losartan in the treatment of hypertension in renal transplant recipients

Arterial hypertension, which represents a common problem in patients with renal transplant, contributes to the cardiovascular morbidity and mortality of these patients. The most usual immunosuppressive drugs (cyclosporine and FK-506) collaborate on the development of hypertension. Calcium channel blockers are the most habitually used antihypertensive drugs in this population, although its long-term hemodimamycs effects could be deleterious especially in transplanted patients with chronic graft nephropathy. Losartan, a specific blocker of angiotensin II (AT1) receptors, has demonstrated a potent antihypertensive effect with a good safety and tolerance profile. The glomerular effects of losartan could be useful in transplanted patients. The present open, prospective and multicenter study evaluated the efficacy and safety of losartan in the treatment of hypertension in a group of patients with a renal transplant. Seventy-six patients with systolic blood pressure > or = 140 and/or diastolic blood pressure > or = 90 mm Hg, and/or patients on therapy with one antihypertensive drug and related side effects were included. After inclusion, therapy with losartan 50 mg/24 hr was started, discontinuing the previous antihypertensive therapy and/or therapy which caused the side effects. At four weeks, if blood pressure (BP) was not controlled, hydrochlorothiazide 25 mg or furosemide 40 mg/24 hr was added. At baseline and at weeks 2, 4, 8 and 12, the following parameters were monitored: BP, creatinine, hematocrit, hemoglobin, glucose, ions, uric acid, cholesterol, triglycerides, bilirubin, SGOT, SGPT, GGT, LDH, calcium, phosphate, alkaline phosphatase, proteinuria, and both cyclosporine and FK-506 levels in whole blood. Sixty-seven patients completed the 12-week study period. Mean blood pressure decreased from 113 +/- 10 to 102 +/- 9 mm Hg at the end of the study (P < 0.0001); 38 of the 67 patients (56.7%) who completed the study had a SBP lower than 140 mm Hg and a DBP lower than 90. These blood pressures were obtained in 30 patients on monotherapy with losartan (78.9%). Proteinuria decreased significantly at week 4 and was confirmed at week 12, especially in patients with proteinuria > or = 300 mg/24 hr. Nine patients were withdrawn during the study period for different reasons. Serum creatinine showed a slight, non-clinically significant increase at week 4, remaining stable until the end of the study. Two patients developed a mild normocytic anemia, and three others presented a mild impairment of pre-existent anemia. No interactions with cyclosporine or FK-506 were described. These results indicate that losartan is effective in reducing BP in hypertensive patients with a renal transplant. It has a good tolerance profile and does not interfere with immunosuppressive therapy.

Identification of a novel bond between a histidine and the essential tyrosine in catalase HPII of Escherichia coli

A bond between the N delta of the imidazole ring of His 392 and the C beta of the essential Tyr 415 has been found in the refined crystal structure at 1.9 A resolution of catalase HPII of Escherichia coli. This novel type of covalent linkage is clearly defined in the electron density map of HPII and is confirmed by matrix-assisted laser desorption/ionization mass spectrometry analysis of tryptic digest mixtures. The geometry of the bond is compatible with both the sp3 hybridization of the C beta atom and the planarity of the imidazole ring. Two mutated variants of HPII active site residues, H128N and N201H, do not contain the His 392-Tyr 415 bond, and their crystal structures show that the imidazole ring of His 392 was rotated, in both cases, by 80 degrees relative to its position in HPII. These mutant forms of HPII are catalytically inactive and do not convert heme b to heme d, suggesting a relationship between the self-catalyzed heme conversion reaction and the formation of the His-Tyr linkage. A model coupling the two processes and involving the reaction of one molecule of H2O2 on the proximal side of the heme with compound 1 is proposed.

A versatile negative-staining ribonuclease zymogram

A versatile negative-staining ribonuclease zymogram is described. The method has several advantages as it combines, by means of different staining procedures, high resolving power, sensitivity, and specificity with a rapid, reproducible, and simultaneous analysis of purity of ribonuclease samples on the same polyacrylamide gel. Activity bands can be visualized at any time during the incubation process without staining of the gel. This allows the choice of different staining procedures after incubation. Using poly(C) as substrate less than 1 pg of bovine pancreatic ribonuclease A was detected in less than 2 h after the electrophoretic run. An additional advantage with respect to other methods is that no refrigeration is needed during electrophoresis.

Astrocyte-derived TNF and glutamate critically modulate microglia activation by methamphetamine

Methamphetamine (Meth) is a powerful illicit psychostimulant, widely used for recreational purposes. Besides disrupting the monoaminergic system and promoting oxidative brain damage, Meth also causes neuroinflammation, contributing to synaptic dysfunction and behavioral deficits. Aberrant activation of microglia, the largest myeloid cell population in the brain, is a common feature in neurological disorders triggered by neuroinflammation. In this study, we investigated the mechanisms underlying the aberrant activation of microglia elicited by Meth in the adult mouse brain. We found that binge Meth exposure caused microgliosis and disrupted risk assessment behavior (a feature that usually occurs in individuals who abuse Meth), both of which required astrocyte-to-microglia crosstalk. Mechanistically, Meth triggered a detrimental increase of glutamate exocytosis from astrocytes (in a process dependent on TNF production and calcium mobilization), promoting microglial expansion and reactivity. Ablating TNF production, or suppressing astrocytic calcium mobilization, prevented Meth-elicited microglia reactivity and re-established risk assessment behavior as tested by elevated plus maze (EPM). Overall, our data indicate that glial crosstalk is critical to relay alterations caused by acute Meth exposure.