Corrigendum: A Plant Gene Encoding One-Heme and Two-Heme Hemoglobins With Extreme Reactivities Toward Diatomic Gases and Nitrite

[This corrects the article DOI: 10.3389/fpls.2020.600336.].

Lack of orientation selectivity of the heme insertion in murine neuroglobin revealed by resonance Raman spectroscopy

Different murine neuroglobin variants showing structural and dynamic alterations that are associated with perturbation of ligand binding have been studied: the CD loop mutants characterized by an enhanced flexibility (Gly-loop^40-48 and Gly-loop^44-47 ), the F106A mutant, and the double Gly-loop^44-47 /F106A mutant. Their ferric resonance Raman spectra in solution and in crystals are almost identical. In the high-frequency region, the identification of a double set of core size marker bands indicates the presence of two 6-coordinate low spin species. The resonance Raman data, together with the corresponding crystal structures, indicate the presence of two neuroglobin conformers with a reversed (A conformer) or a canonical (B conformer) heme insertion orientation. With the identification of the marker bands corresponding to each conformer, the data indicate that the B conformer increases at the expense of the A form, predominantly in the Gly-loop^44-47 /F106A double mutant, as confirmed by X-ray crystallography. This is the first time that a reversed heme insertion has been identified by resonance Raman in a native 6-coordinate low-spin heme protein. This diagnostic tool could be extended to other heme proteins in order to detect heme orientational disorder, which are likely to be correlated to functionally relevant heme dynamics. DATABASE: Crystallographic structure: structural data are deposited in the Protein Data Bank under the 6RA6 PDB entry.

A Plant Gene Encoding One-Heme and Two-Heme Hemoglobins With Extreme Reactivities Toward Diatomic Gases and Nitrite

In plants, symbiotic hemoglobins act as carriers and buffers of O₂ in nodules, whereas nonsymbiotic hemoglobins or phytoglobins (Glbs) are ubiquitous in tissues and may perform multiple, but still poorly defined, functions related to O₂ and/or nitric oxide (NO). Here, we have identified a Glb gene of the model legume Medicago truncatula with unique properties. The gene, designated MtGlb1-2, generates four alternative splice forms encoding Glbs with one or two heme domains and 215-351 amino acid residues. This is more than double the size of any hemoglobin from plants or other organisms described so far. A combination of molecular, cellular, biochemical, and biophysical methods was used to characterize these novel proteins. RNA-sequencing showed that the four splice variants are expressed in plant tissues. MtGlb1-2 is transcriptionally activated by hypoxia and its expression is further enhanced by an NO source. The gene is preferentially expressed in the meristems and vascular bundles of roots and nodules. Two of the proteins, bearing one or two hemes, were characterized using mutants in the distal histidines of the hemes. The Glbs are extremely reactive toward the physiological ligands O₂, NO, and nitrite. They show very high O₂ affinities, NO dioxygenase activity (in the presence of O₂), and nitrite reductase (NiR) activity (in the absence of O₂) compared with the hemoglobins from vertebrates and other plants. We propose that these Glbs act as either NO scavengers or NO producers depending on the O₂ tension in the plant tissue, being involved in the fast and fine tuning of NO concentration in the cytosol in response to sudden changes in O₂ availability.

Redox Cofactor Rotates during Its Stepwise Decarboxylation: Molecular Mechanism of Conversion of Coproheme to Heme b

Coproheme decarboxylase (ChdC) catalyzes the last step in the heme biosynthesis pathway of monoderm bacteria with coproheme acting both as redox cofactor and substrate. Hydrogen peroxide mediates the stepwise decarboxylation of propionates 2 and 4 of coproheme. Here we present the crystal structures of coproheme-loaded ChdC from Listeria monocytogenes (LmChdC) and the three-propionate intermediate, for which the propionate at position 2 (p2) has been converted to a vinyl group and is rotated by 90° compared to the coproheme complex structure. Single, double, and triple mutants of LmChdC, in which H-bonding interactions to propionates 2, 4, 6, and 7 were eliminated, allowed us to obtain the assignment of the coproheme propionates by resonance Raman spectroscopy and to follow the H₂O₂-mediated conversion of coproheme to heme b. Substitution of H₂O₂ by chlorite allowed us to monitor compound I formation in the inactive Y147H variant which lacks the catalytically essential Y147. This residue was demonstrated to be oxidized during turnover by using the spin-trap 2-methyl-2-nitrosopropane. Based on these findings and the data derived from molecular dynamics simulations of cofactor structures in distinct poses, we propose a reaction mechanism for the stepwise decarboxylation of coproheme that includes a 90° rotation of the intermediate three-propionate redox cofactor.

Synthesis and Evaluation of Carbonic Anhydrase Inhibitors with Carbon Monoxide Releasing Properties for the Management of Rheumatoid Arthritis

Carbon monoxide (CO) is a gas endogenously produced in humans, reported to exhibit anti-inflammatory and cytoprotective effects at low concentration. In this context, CO releasing molecules (CORMs) are attracting enormous interest. Herein, we report a series of small-molecule hybrids consisting of a carbonic anhydrase (CA; EC 4.2.1.1) inhibitor linked to a CORM tail section (CAI-CORMs). All compounds were screened in vitro for their inhibition activity against the human (h) CA I, II, IV, IX, and XII isoforms. On selected CAI-CORM hybrids, the CO releasing properties were evaluated, along with their pain-relieving effect, in a model of rheumatoid arthritis. One CAI-CORM hybrid (5b) induced a higher pain-relieving effect compared to the one exerted by the single administration of CAI (5a) and CORM (15b) fragments, shedding light on the possibility to enhance the pain relief effect of CA inhibitors inserting a CO releasing moiety on the same molecular scaffold.

The hydrogen bonding network of coproheme in coproheme decarboxylase from Listeria monocytogenes: Effect on structure and catalysis

Coproheme decarboxylase (ChdC) catalyzes the oxidative decarboxylation of coproheme to heme b, i.e. the last step in the recently described coproporphyrin-dependent pathway. Coproheme decarboxylation from Listeria monocytogenes is a robust enzymatic reaction of low catalytic efficiency. Coproheme acts as both substrate and redox cofactor activated by H₂O₂. It fully depends on the catalytic Y147 close to the propionyl group at position 2. In the present study we have investigated the effect of disruption of the comprehensive and conserved hydrogen bonding network between the four propionates and heme cavity residues on (i) the conformational stability of the heme cavity, (ii) the electronic configuration of the ferric redox cofactor/substrate, (iii) the binding of carbon monoxide and, (iv) the decarboxylation reaction mediated by addition of H₂O₂. Nine single, double and triple mutants of ChdC from Listeria monocytogenes were produced in E. coli. The respective coproheme- and heme b-complexed proteins were studied by UV–Vis, resonance Raman, circular dichroism spectroscopy, and mass spectrometry. Interactions of propionates 2 and 4 with residues in the hydrophobic cavity are crucial for maintenance of the heme cavity architecture, for the mobile distal glutamine to interact with carbon monoxide, and to keep the heme cavity in a closed conformation during turnover. By contrast, the impact of substitution of residues interacting with solvent exposed propionates 6 and 7 was negligible. Except for Y147A and K151A all mutant ChdCs exhibited a wild-type-like catalytic activity. The findings are discussed with respect to the structure-function relationships of ChdCs.

Unconventional T cells in chronic hepatitis B patients on long-term suppressive therapy with tenofovir followed by a Peg-IFN add-on strategy: A randomized study

HBV eradication in chronic hepatitis B (CHB) subjects is rarely achieved with either nucleos(t)ide analogues (NA) or pegylated interferon (Peg-IFN), which both have a limited effect in restoring immune responses. Thirty CHB subjects on long-term treatment with tenofovir (TDF) and HBV suppression were enrolled and randomized 1:2 to either receive Peg-IFN-α-2a add-on therapy or continue TDF alone. We studied γδ T and iNKT frequency and function (by flow cytometry) at baseline, at 12 weeks and 12 weeks after the end of treatment. A higher reduction in qHBsAg occurred in the add-on group compared with the NA group at W12 (P = .016) and at W24 (P = .012). A decline of qHBsAg ≥0.5 log₁₀ at week 24 occurred in 4 of 10 patients in the add-on arm and 1 of 20 in the NA arm, respectively (P = .03). HBsAg loss was seen in 20% of subjects in the add-on group and in none of the NA group. Compared to HBV negative, CHB on TDF showed lower frequency of iNKT (P = .03) and γδ T cells (P = .03) as well as fewer γδ T cells expressing Vδ2 T-cell receptors (P = .005). No changes in unconventional T-cell frequency and function were shown in both add-on and NA patients nor were differences detected between the two treatment groups. We report persistent impairment of unconventional T cells in CHB. Despite a greater qHBsAg decline of add-on patients, our data failed to detect any effect of Peg-IFN treatment on unconventional T cells.

Insights into the Active Site of Coproheme Decarboxylase from Listeria monocytogenes

Coproheme decarboxylases (ChdC) catalyze the hydrogen peroxide-mediated conversion of coproheme to heme b. This work compares the structure and function of wild-type (WT) coproheme decarboxylase from Listeria monocytogenes and its M149A, Q187A, and M149A/Q187A mutants. The UV-vis, resonance Raman, and electron paramagnetic resonance spectroscopies clearly show that the ferric form of the WT protein is a pentacoordinate quantum mechanically mixed-spin state, which is very unusual in biological systems. Exchange of the Met149 residue to Ala dramatically alters the heme coordination, which becomes a 6-coordinate low spin species with the amide nitrogen atom of the Q187 residue bound to the heme iron. The interaction between M149 and propionyl 2 is found to play an important role in keeping the Q187 residue correctly positioned for closure of the distal cavity. This is confirmed by the observation that in the M149A variant two CO conformers are present corresponding to open (A₀) and closed (A₁) conformations. The CO of the latter species, the only conformer observed in the WT protein, is H-bonded to Q187. In the absence of the Q187 residue or in the adducts of all the heme b forms of ChdC investigated herein (containing vinyls in positions 2 and 4), only the A₀ conformer has been found. Moreover, M149 is shown to be involved in the formation of a covalent bond with a vinyl substituent of heme b at excess of hydrogen peroxide.

The Greenland shark Somniosus microcephalus-Hemoglobins and ligand-binding properties

A large amount of data is currently available on the adaptive mechanisms of polar bony fish hemoglobins, but structural information on those of cartilaginous species is scarce. This study presents the first characterisation of the hemoglobin system of one of the longest-living vertebrate species (392 ± 120 years), the Arctic shark Somniosus microcephalus. Three major hemoglobins are found in its red blood cells and are made of two copies of the same α globin combined with two copies of three very similar β subunits. The three hemoglobins show very similar oxygenation and carbonylation properties, which are unaffected by urea, a very important compound in marine elasmobranch physiology. They display identical electronic absorption and resonance Raman spectra, indicating that their heme-pocket structures are identical or highly similar. The quaternary transition equilibrium between the relaxed (R) and the tense (T) states is more dependent on physiological allosteric effectors than in human hemoglobin, as also demonstrated in polar teleost hemoglobins. Similar to other cartilaginous fishes, we found no evidence for functional differentiation among the three isoforms. The very similar ligand-binding properties suggest that regulatory control of O₂ transport may be at the cellular level and that it may involve changes in the cellular concentrations of allosteric effectors and/or variations of other systemic factors. The hemoglobins of this polar shark have evolved adaptive decreases in O₂ affinity in comparison to temperate sharks.

Hydrogen peroxide-mediated conversion of coproheme to heme b by HemQ-lessons from the first crystal structure and kinetic studies

Heme biosynthesis in Gram-positive bacteria follows a recently described coproporphyrin-dependent pathway with HemQ catalyzing the decarboxylation of coproheme to heme b. Here we present the first crystal structure of a HemQ (homopentameric coproheme-HemQ from Listeria monocytogenes) at 1.69 Å resolution and the conversion of coproheme to heme b followed by UV-vis and resonance Raman spectroscopy as well as mass spectrometry. The ferric five-coordinated coproheme iron of HemQ is weakly bound by a neutral proximal histidine H174. In the crystal structure of the resting state, the distal Q187 (conserved in Firmicutes HemQ) is H-bonded with propionate p2 and the hydrophobic distal cavity lacks solvent water molecules. Two H₂ O₂ molecules are shown to be necessary for decarboxylation of the propionates p2 and p4, thereby forming the corresponding vinyl groups of heme b. The overall reaction is relatively slow (k_cat /K_M = 1.8 × 10² m^-1 ·s^-1 at pH 7.0) and occurs in a stepwise manner with a three-propionate intermediate. We present the noncovalent interactions between coproheme and the protein and propose a two-step reaction mechanism. Furthermore, the structure of coproheme-HemQ is compared to that of the phylogenetically related heme b-containing chlorite dismutases.

DATABASE

Structural data are available in the PDB under the accession number 5LOQ.

The key role played by charge in the interaction of cytochrome c with cardiolipin

Cytochrome c undergoes structural variations upon binding of cardiolipin, one of the phospholipids constituting the mitochondrial membrane. Although several mechanisms governing cytochrome c/cardiolipin (cyt c/CL) recognition have been proposed, the interpretation of the process remains, at least in part, unknown. To better define the steps characterizing the cyt c-CL interaction, the role of Lys72 and Lys73, two residues thought to be important in the protein/lipid binding interaction, were recently investigated by mutagenesis. The substitution of the two (positively charged) Lys residues with Asn revealed that such mutations cancel the CL-dependent peroxidase activity of cyt c; furthermore, CL does not interact with the Lys72Asn mutant. In the present paper, we extend our study to the Lys → Arg mutants to investigate the influence exerted by the charge possessed by the residues located at positions 72 and 73 on the cyt c/CL interaction. On the basis of the present work a number of overall conclusions can be drawn: (i) position 72 must be occupied by a positively charged residue to assure cyt c/CL recognition; (ii) the Arg residues located at positions 72 and 73 permit cyt c to react with CL; (iii) the replacement of Lys72 with Arg weakens the second (low-affinity) binding transition; (iv) the Lys73Arg mutation strongly increases the peroxidase activity of the CL-bound protein.

Modelling of healthcare-associated infections: a study on the dynamics of pathogen transmission by using an individual-based approach

Prevention and control of Healthcare Associated Infections (HAIs) has become a high priority for most healthcare organizations. Mathematical models can provide insights into the dynamics of nosocomial infections and help to evaluate the effect of infection control measures. The model presented in this paper adopts an individual-based and stochastic approach to investigate MRSA outbreaks in a hospital ward. A computer simulation was implemented to analyze the dynamics of the system associated with the spread of the infection and to carry out studies on space and personnel management. This study suggests that a strict spatial cohorting might be ineffective, if it is not combined with personnel cohorting.

Late onset of hepatitis B virus reactivation following hematopoietic stem cell transplantation: successful treatment with combined entecavir plus tenofovir therapy

Prophylaxis with lamivudine (LAM) is recommended for hepatitis B core antibody-positive allogenic hematopoietic stem cell transplant (HSCT) recipients, but the optimal timing for the institution and duration of the prophylaxis is still unknown. Furthermore, considering the high rate of mortality associated with hepatitis B virus reactivation (HBV-R), the most potent and long-term effective antiviral regimen should be considered. We report here a case of late onset of HBV-R after a long-term prophylaxis with LAM in a patient who underwent HSCT for non-Hodgkin lymphoma and who was successfully treated with a combination antiviral regimen including entecavir and tenofovir disoproxil fumarate.

Impact of hyperglycaemia and cholesterol levels on the outcome of hepatitis C virus (HCV) treatment in HIV/HCV-coinfected patients

OBJECTIVES

High serum total cholesterol and low-density lipoprotein (LDL) levels have been demonstrated to increase the probability of a sustained viral response (SVR) in chronic hepatitis C. Conversely, insulin resistance reduces SVR rates. We investigated the influence of baseline glucose and lipid values on the outcome of hepatitis C virus (HCV) treatment in HIV-1 infected subjects.

METHODS

We retrospectively reviewed the charts of HIV/HCV-coinfected patients treated with an interferon-based regimen from 2002 to 2008. Fasting glucose levels and total cholesterol, LDL and triglyceride levels were recorded prior to the initiation of treatment.

RESULTS

Of the 96 patients enrolled in the study, 36 (37.5%) had genotype 1, 48 (50%) genotype 2 or 3 and 12 (12.5%) genotype 4. SVR was obtained in 25% (nine of 36) and 70% (42 of 60) of patients with genotype 1 and other genotypes, respectively. In the multivariate analysis, the independent predictors of SVR were: genotype other than genotype 1 [adjusted odds ratio 9.64, confidence interval (CI) 2.7-34.3; P<0.0001], HCV viraemia [adjusted odds ratio 0.36, CI 0.15-0.9; P=0.028], fasting glucose > or =100 mg/dL [adjusted odds ratio 0.13, CI 0.034-0.51; P=0.003], and cholesterol level > or =190 mg/dL [adjusted odds ratio 5.96, CI 1.6-22.3; P=0.008].

CONCLUSIONS

Higher baseline serum glucose and cholesterol levels may be significant prognostic indicators for anti-HCV treatment outcome in HIV/HCV-coinfected patients.

Does fluvastatin favour HCV replication in vivo? A pilot study on HIV-HCV coinfected patients

Fluvastatin showed anti-hepatitis C virus (HCV) activity in vitro, through the inhibition of geranylgeranylation of cellular proteins, and a synergistic effect with interferon (IFN)-alpha. Nevertheless statins up-regulate low-density lipoprotein (LDL) receptor, required for HCV cell entry, and the closely related scavenger receptors SRBI and CD36; moreover they reduce class II major histocompatibility complex expression on antigen presenting cell, modulating T-cell activation. In vivo LDL levels have been identified as prognostic indicator of sustained viral response to IFN in patients with HCV infection, suggesting that lipid-lowering agents might conversely favour HCV entry into the hepatocytes and translate into higher viral replication. We evaluated the effect of fluvastatin on HCV-RNA levels, CD36 expression and T-cell homeostasis in HCV-RNA positive patients. HCV-RNA was measured at baseline and after 4 weeks in 42 HCV/HIV-1 co-infected patients, randomized to receive either fluvastatin 80 mg qd or no treatment. CD36 expression and markers of T-cell activation were evaluated by means of flow cytometry. Plasma interleukin (IL)-10, IFN-gamma and IL-7 were measured by ELISA. Serum cholesterol and LDL decreased significantly in the treatment group (P = 0.0001 and 0.01, respectively). Surprisingly a significant increase of HCV-RNA levels was seen after 4 weeks of fluvastatin (P = 0.03). The percentages of naive/activated/apoptotic cells and CD36 expression remained unchanged. Fluvastatin did not inhibit HCV-RNA replication in vivo; conversely we observed a significant increase of HCV-RNA levels. CD36 expression on monocytes were not up-regulated by statins as previously reported in vitro. The correlation between HCV infectivity, oxidized-LDL receptor and statins in HCV infection need further evaluation.

Does fluvastatin favour HCV replication in vivo? A pilot study on HIV-HCV coinfected patients

Fluvastatin showed anti-hepatitis C virus (HCV) activity in vitro, through the inhibition of geranylgeranylation of cellular proteins, and a synergistic effect with interferon (IFN)-alpha. Nevertheless statins up-regulate low-density lipoprotein (LDL) receptor, required for HCV cell entry, and the closely related scavenger receptors SRBI and CD36; moreover they reduce class II major histocompatibility complex expression on antigen presenting cell, modulating T-cell activation. In vivo LDL levels have been identified as prognostic indicator of sustained viral response to IFN in patients with HCV infection, suggesting that lipid-lowering agents might conversely favour HCV entry into the hepatocytes and translate into higher viral replication. We evaluated the effect of fluvastatin on HCV-RNA levels, CD36 expression and T-cell homeostasis in HCV-RNA positive patients. HCV-RNA was measured at baseline and after 4 weeks in 42 HCV/HIV-1 co-infected patients, randomized to receive either fluvastatin 80 mg qd or no treatment. CD36 expression and markers of T-cell activation were evaluated by means of flow cytometry. Plasma interleukin (IL)-10, IFN-gamma and IL-7 were measured by ELISA. Serum cholesterol and LDL decreased significantly in the treatment group (P = 0.0001 and 0.01, respectively). Surprisingly a significant increase of HCV-RNA levels was seen after 4 weeks of fluvastatin (P = 0.03). The percentages of naive/activated/apoptotic cells and CD36 expression remained unchanged. Fluvastatin did not inhibit HCV-RNA replication in vivo; conversely we observed a significant increase of HCV-RNA levels. CD36 expression on monocytes were not up-regulated by statins as previously reported in vitro. The correlation between HCV infectivity, oxidized-LDL receptor and statins in HCV infection need further evaluation.

Altered expression of the tetraspanin CD81 on B and T lymphocytes during HIV-1 infection

CD81 is a member of the tetraspan superfamily and plays a role in immune responses and in hepatitis C virus (HCV) pathogenesis. We analysed CD81 cell surface and mRNA expression in different lymphocytic subpopulations in human immunodeficiency virus (HIV)-1, HCV and dually infected subjects. CD81 cell surface expression was evaluated with fluorescence activated cell sorter (FACS) analysis; mRNA quantification was performed with semiquantitative polymerase chain reaction (PCR). CD81 cell surface expression on CD4(+) T lymphocytes was significantly different by analysis of variance (anova) test (P < 0.001), with reduced expression in HIV-1(+) patients. In B lymphocytes, higher cell surface expression was present in HIV-1, in HCV and in dually infected subjects compared to healthy controls. CD81 expression on B lymphocytes showed a positive correlation with plasma HIV-RNA. CD81 mRNA levels in B lymphocytes were significantly higher in HIV-1(+) patients compared to healthy controls. The potential consequence of the down-regulation of CD81 in CD4(+) cells during HIV-1 infection in conjunction with diverted CD28, CD4 and CD3 expression is the disruption of T cell function. Increased CD81 expression on B lymphocytes might explain the higher prevalence of lymphoproliferative disorders in HIV-1 and HCV infection. Up-regulation of CD81 mRNA on CD4(+) T cells indicates that down-regulation of CD81 occurs at the post-transcriptional/translational level.

Measurement of the D(s)+ lifetime

A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, D(s)+ --> phi(1020)pi+ and D(s)+ -->K*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5(stat) +/- 5.1(syst) fs using 8961 +/- 105 D(s)+ --> phi(1020)pi+ and 4680 +/- 90 D(s)+ --> K*(892)0K+ decays. This is a significant improvement over the present world average.

Open, Randomized, Multicentre Italian Trial on Peg-Ifn plus Ribavirin versus Peg-Ifn Monotherapy for Chronic Hepatitis C in HIV-Coinfected Patients on Haart

Background

Chronic hepatitis C is common and aggressive in HIV-positive patients, so the development of a well-tolerated HCV therapy is a priority. We evaluated the efficacy and safety of pegylated interferon α2b (PEG-IFN) plus ribavirin (RBV) versus PEG-IFN monotherapy in HIV/HCV-coinfected patients undergoing highly active antiretroviral therapy (HAART), and analysed the predictive factors of response.

Methods

An Italian, multicentre, open-label trial including 135 coinfected patients, randomized to PEG-IFN 1.5 μg/kg/week plus RBV 400 mg twice daily ( n=69, arm A) or PEG-IFN 1.5 μg/kg/week ( n=66, arm B) for 48 weeks. We assessed the predictive values of early virological response (EVR) at week 8 (HCV-RNA drop >2 log10 compared with baseline or undetectable levels) on sustained virological response (SVR).

Results

Fifty-five patients (28 from arm A and 27 from arm B) completed 48 weeks of therapy. At the end of treatment, 20/28 patients in arm A and 11/27 in arm B had HCV-RNA <50 IU/ml. In a per-protocol analysis, SVR was reached by 54% of patients in arm A (genotype 2–3, 11/16; genotype 1–4, 4/12) and 22% in arm B (genotype 2–3, 3/15; genotype 1–4, 3/12). In an intention-to-treat analysis, the SVR was 22% in arm A (genotype 2–3, 11/32; genotype 1–4, 4/37) versus 9% in arm B (genotype 2–3, 3/32; genotype 1–4, 3/34). The best predictors of SVR were the use of combination therapy, infection with HCV genotype 3 versus genotype 1, and EVR at week 8. Thirty patients (15 from arm A and 15 from arm B) dropped out of the trial prematurely due to side effects. The positive predictive value of EVR at week 8 was 65%, the negative predictive value was 86%.

Conclusions

PEG-IFN plus RBV can be considered a solid option for the treatment of HIV/HCV-coinfected patients. The key to successfully improving efficacy is strong compliance through strict overall patient monitoring, in order to best manage drug toxicity. EVR assessment at week 8 may become a useful stategy in the management of therapy.

Response to Haart and Gb Virus Type C Coinfection in a Cohort of Antiretroviral-Naive HIV-Infected Individuals

The prognostic role of GB virus type C (GBV-C) viraemia in HIV-infected subjects treated with highly active antiretroviral therapy (HAART) is still undefined, The aim of this analysis is to assess the relationship between GBV-C infection and response to antiretroviral therapy among HIV-infected subjects initiating HAART when antiretroviral-naive.

A prospective, observational study of 400 HIV-infected patients with measurements of GBV-C RNA, hepatitis C virus (HCV) antibodies and HCV RNA determined from plasma stored prior to HAART initiation, Time to virological (achieving HIV RNA ≤500 copies/ml) and immunological success (a CD4+ count increase of ≥200cells/μl), and the time to virological relapse (confirmed HIV RNA >500 copies/ml) were assessed by Kaplan-Meier methods and Cox proportional hazard regression model.

Of the subjects, 117 (29.3%) were GBV-C positive and, overall, 351 (87.8%) patients achieved virological success, After controlling for a number of confounders including HCV RNA, GBV-C viraemic patients experienced a significantly lower risk of HIV rebound than those who were GBV-C negative [relative hazard (RH)=0.56, 95% CI: 0.34–0.93, P=0.03], Conversely, the probability of achieving initial virological success or CD4+ count response after HAART did not differ between GBV-C-negative and -positive subjects, These results suggest that GBV-C coinfection may play a role in determining the rate of HIV rebound possibly by competing with HIV replication after HIV load has been successfully suppressed by HAART.

The Management of Hepatitis B Virus/HIV-1 Co-Infected Patients Starting Their First Haart Regimen. Treating Two Infections for the Price of One Drug?

We examined the impact of a lamivudine-containing highly active antiretroviral therapy (HAART) regimen on 164 hepatitis B virus/HIV co-infected individuals starting their first HAART. Lamivudine-treated patients (accounting for 73% of the study population) showed a significantly lower level of alanine aminotransferase over follow-up [–81.1 mU/ml mean difference; 95% confidence intervals (95% CI): –30.3; –131.7, P=0.003] and a significantly reduced risk of liver-related morbidity/mortality [Relative hazard (RH)=0.07; 95% CI: 0.01–0.38, P=0.002] than those starting a lamivudine sparing-regimen.

A high statistics measurement of the Lambda(+)(c) lifetime

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.

Search for CP violation in the decays D+--> K(S)pi+ and D+-->K(S)K+

A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D+-->K(S)pi+ and D+-->K(S)K+. We have measured the following asymmetry parameters relative to D+-->K-pi+pi+: A(CP)(K(S)pi+) = (-1.6+/-1.5+/-0.9)%, A(CP)(K(S)K+) = (+6.9+/-6.0+/-1.5)%, and A(CP)(K(S)K+) = (+7.1+/-6.1+/-1.2)% relative to D+-->K(S)pi+. We have also measured the relative branching ratios and found Gamma(D+-->K(0)pi+)/Gamma(D+-->K-pi+pi+) = (30.60+/-0.46+/-0.32)%, Gamma(D+-->K(0)K+)/Gamma(D+-->K-pi+pi+) = (6.04+/-0.35+/-0.30)%, and Gamma(D+-->K(0)K+)/Gamma(D+-->K(0)pi+) = (19.96+/-1.19+/-0.96)%.

Measurement of the branching ratios of D(+) and D(+)(s) hadronic decays to four-body final states containing a K(S)

We have studied hadronic four-body decays of D(+) and D(+)(s) mesons with a K(S) in the final state using data recorded during the 1996-1997 fixed-target run of the Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of gamma(D(+)-->K(S)K-pi(+)pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0768+/-0.0041+/-0.0032. We make the first observation of three new decay modes with branching ratios gamma(D(+)-->K(S)K+pi(+)pi(-))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0562+/-0.0039+/-0.0040, gamma(D(+)-->K(S)K+K-pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0077+/-0.0015+/-0.0009, and gamma(D(+)(s)-->K(S)K+pi(+)pi(-))/gamma(D(+)(s)-->K(S)K-pi(+)pi(+)) = 0.586+/-0.052+/-0.043, where in each case the first error is statistical and the second error is systematic.

Study of the decay D0 --> K+pi-

Using a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831), we observe the decay D0-->K+pi- with a signal yield of 149+/-31 events compared to a similarly cut sample consisting of 36 760+/-195 D0-->K-pi+ events. We use the observed ratio of D0-->K+pi- to D0-->K-pi+ (0.404+/-0.085+/-0.025)% to obtain a relationship between the D0 mixing and doubly Cabibbo suppressed decay parameters.

Antagonists of P2 receptor prevent NGF-dependent neuritogenesis in PC12 cells

The pheochromocytoma PC12 cell line that develops neuronal characteristics of sympathetic cells after treatment with nerve growth factor (NGF) represents a well-established cellular model system for studying NGF signalling. Interesting information on the different mechanistic pathways of NGF can be obtained by adopting the pharmacological approach of inhibiting P2 receptors, expressed in naive PC12 cells and recognised as important biological mediators of neurotransmitters and growth factors. We show here that Basilen Blue, an antagonist of P2 receptor, reversibly prevents NGF-dependent neurite outgrowth with an IC(50) in the 5-10 microM range. Suramin, oxidised-ATP and diisothiocyanatostilbene-disulfonic acid, differently from other purinoceptor ligands, are also effective in this regard. NGF-dependent regeneration and stability of neurites, selected NGF-dependent extracellular and intracellular protein phosphorylations, binding of [(3)H] ATP to PC12 cell membranes are also modulated by Basilen Blue. On the contrary, cell adhesion, cellular duplication, 5'-nucleotidase activity, NGF-induced tyrosine autophosphorylation of TrkA receptors are not affected. NGF furthermore directly modulates the extracellular release of ATP and especially the levels of P2X(2) receptor protein in PC12 cells. In addition, extracellular ATP improves the neuritogenic effect of sub-optimal concentrations of NGF. Our study identifies P2 receptor ligands, particularly Basilen Blue, as useful tools to dissect different NGF-evoked functions, suggesting a mechanistic role for P2 receptors in the signalling pathways of NGF.

Loss of lamivudine resistance in a zidovudine and lamivudine dual-resistant HIV-1 isolate after discontinuation of in vitro lamivudine drug pressure

We examined the in vitro phenotypic and genotypic profiles of an extensively passaged human immunodeficiency virus type 1 clinical isolate which has been selected for lamivudine resistance, with an M184V mutation in a zidovudine-resistant genetic background, and then cultured with zidovudine alone. Our passaging strategy led to a decrease in lamivudine IC50 values, which were comparable to those prior to lamivudine exposure, and the genotypic restoration of the wild-type sequence at codon 184 of reverse transcriptase.

A case of Austrian's syndrome with ocular involvement

A man with a history of alcohol abuse was admitted to hospital with pneumonia and meningitis due to Streptococcus pneumoniae. Because of the worsening of respiratory function and the persistence of fever, an echocardiographic examination was made, which showed endocarditis with destruction of the aortic valve. The patient underwent surgical valve replacement. In addition, he showed a choroiditis in the left eye which improved after antibiotic therapy. The interest of this case lies in the rarity of the triad described as Austrian's syndrome and in the coexistent fourth septic localization, namely in the left eye.

High sensitivity quantitative analysis of cobalt uptake in rat cerebellar granule cells with and without excitatory amino acids

We quantified the effect of the excitatory amino acids kainate and glutamate on the uptake of cobalt in primary rat cerebellar granule neurons, by using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). We quantitatively demonstrated that Co2+ uptake, although enhanced by glutamate and kainate also takes place in the absence of excitatory amino acids. We also found that cobalt uptake is not significantly altered by the presence of glutamate receptor competitive or noncompetitive antagonists, indicating that cobalt uptake in granule neurons does not require glutamate receptor stimulation. Our results suggest, therefore, that Co2+ may enter the cell by passive diffusion through the plasma membrane.

Loss of antiviral effect owing to zidovudine and lamivudine double resistance in HIV-1-infected patients in an ongoing open-label trial

In order to compare the resistance pattern to zidovudine plus lamivudine in zidovudine-experienced patients, we studied three HIV-1-infected patients enrolled in NUCB3004, an open-label trial. Over a 24-week follow-up, the patients were studied for drug sensitivity, reverse transcriptase genotype, viral load (HIV-1 RNA level) and viral phenotype (syncytium inducing (SI) or non-syncytium inducing). Virus isolates derived from peripheral blood mononuclear cells (PBMCs) were tested for changes in drug susceptibility. Proviral DNA in the patients' PBMCs and RNA from plasma and culture supernatant were subjected to amplification and sequencing. All three HIV-1 strains showed a decreased susceptibility to either zidovudine or lamivudine after 24 weeks of therapy. The pattern of DNA genotypic resistance to lamivudine in patient A showed a mutation at codon 184 of the reverse transcriptase-encoding gene (methionine to valine). No HIV-1 strains with lamivudine-related mutations in proviral DNA were found among the isolates obtained from patients B and C. In these two patients, the mutation at codon 184 of the reverse transcriptase-encoding gene appeared in RNA, both in plasma and in culture supernatant. Viral phenotyping revealed the maintenance of the SI phenotype at week 24. Two out of the three patients experienced a reduction in HIV-1 RNA levels after 24 weeks of therapy, and in two out of three there was a rebound in viral load at week 28 together with the onset of the codon 184 mutation in RNA. The degree of phenotypic resistance to both zidovudine and lamivudine correlated with the amino acid changes in RNA and the rapid increase in viral load.

Danazol in the treatment of menorrhagia: the effect of a 1 month induction dose (200 mg) and 2 month's maintenance therapy (200 mg, 100 mg, 50 mg or placebo)

This paper highlights the difficulties of recruiting subjects to objective menstrual blood loss (MBL) studies. Such difficulties may explain the relative paucity of such studies in the literature. Eleven women with objectively assessed evidence of menorrhagia were treated for 1 month with an induction dose of 200 mg of danazol (Danocrine). Subsequently the women were randomly assigned to receive 50, 100 or 200 mg of danazol or placebo for 2 months of maintenance dosing. Follow-up with objective assessment of MBL was continued for 3 months after cessation of maintenance dosing. Danazol 200 mg as an induction dose significantly reduced MBL. The maintenance dose of 200 mg during the following 2 months produced a further decrease in MBL and in some cases amenorrhoea. The lower maintenance dosages of 50 mg and 100 mg were associated with a variable response. The study was unable to determine whether any beneficial effect of the maintenance dosages of danazol could be maintained following cessation of therapy since the study numbers had become too small. It appears, however, that there is unlikely to be any persisting benefit once therapy has ceased.