The activity of CobB1 protein deacetylase contributes to nucleoid compaction in Streptomyces venezuelae spores by increasing HupS affinity for DNA.

Streptomyces are soil bacteria with complex life cycle. During sporulation Streptomyces linear chromosomes become highly compacted so that the genetic material fits within limited spore volume. The key players in this process are nucleoid-associated proteins (NAPs). Among them, HU (heat unstable) proteins are the most abundant NAPs in the cell and the most conserved in bacteria. HupS, one of the two HU homologues encoded by the Streptomyces genome, is the best-studied spore-associated NAP. In contrast to other HU homologues, HupS contains a long, C-terminal domain that is extremely rich in lysine repeats (LR domain) similar to eukaryotic histone H2B and mycobacterial HupB protein. Here, we have investigated, whether lysine residues in HupS are posttranslationally modified by reversible lysine acetylation. We have confirmed that Streptomyces venezuelae HupS is acetylated in vivo. We showed that HupS binding to DNA in vitro is controlled by the acetylation. Moreover, we identified that CobB1, one of two Sir2 homologues in Streptomyces, controls HupS acetylation levels in vivo. We demonstrate that the elimination of CobB1 increases HupS mobility, reduces chromosome compaction in spores, and affects spores maturation. Thus, our studies indicate that HupS acetylation affects its function by diminishing DNA binding and disturbing chromosome organization.

Chaperone proteins involved in Rubisco biosynthesis / Bialka chaperonowe zaangazowane w proces biosyntezy Rubisco.

Rubisco is an enzyme found in photosynthetic organisms, which catalyse the first step of biomass accumulation: the carbon dioxide incorporation to ribulose-1,5-bisphosphate. Because of Rubisco's complicated, multimeric structure and a presence of many labile structural elements the enzyme cannot assemble to its native quaternary structure by itself. This is why the folding and assembly process of Rubisco requires the strictly organized operation of a number of auxiliary factors. Chaperone proteins take part in folding of holoenzyme subunits, subsequently they mediate in subunit oligomerisation, and in some cases chaperone proteins direct subunits to their cellular destination such as the carboxysomes or the pyrenoid. In addition to their canonical function of mediating Rubisco assembly, these chaperones are involved in additional processes such as quality control of the biosynthetic process, and regulation of organelle physiology and cellular compartments.

Beyond K48 and K63: non-canonical protein ubiquitination.

Protein ubiquitination has become one of the most extensively studied post-translational modifications. Originally discovered as a critical element in highly regulated proteolysis, ubiquitination is now regarded as essential for many other cellular processes. This results from the unique features of ubiquitin (Ub) and its ability to form various homo- and heterotypic linkage types involving one of the seven different lysine residues or the free amino group located at its N-terminus. While K48- and K63-linked chains are broadly covered in the literature, the other types of chains assembled through K6, K11, K27, K29, and K33 residues deserve equal attention in the light of the latest discoveries. Here, we provide a concise summary of recent advances in the field of these poorly understood Ub linkages and their possible roles in vivo.

E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein.

The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.

Insights into the Structure of Rubisco from Dinoflagellates-In Silico Studies.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is one of the best studied enzymes. It is crucial for photosynthesis, and thus for all of biosphere's productivity. There are four isoforms of this enzyme, differing by amino acid sequence composition and quaternary structure. However, there is still a group of organisms, dinoflagellates, single-cell eukaryotes, that are confirmed to possess Rubisco, but no successful purification of the enzyme of such origin, and hence a generation of a crystal structure was reported to date. Here, we are using in silico tools to generate the possible structure of Rubisco from a dinoflagellate representative, Symbiodinium sp. We selected two templates: Rubisco from Rhodospirillum rubrum and Rhodopseudomonas palustris. Both enzymes are the so-called form II Rubiscos, but the first is exclusively a homodimer, while the second one forms homo-hexamers. Obtained models show no differences in amino acids crucial for Rubisco activity. The variation was found at two closely located inserts in the C-terminal domain, of which one extends a helix and the other forms a loop. These inserts most probably do not play a direct role in the enzyme's activity, but may be responsible for interaction with an unknown protein partner, possibly a regulator or a chaperone. Analysis of the possible oligomerization interface indicated that Symbiodinium sp. Rubisco most likely forms a trimer of homodimers, not just a homodimer. This hypothesis was empowered by calculation of binding energies. Additionally, we found that the protein of study is significantly richer in cysteine residues, which may be the cause for its activity loss shortly after cell lysis. Furthermore, we evaluated the influence of the loop insert, identified exclusively in the Symbiodinium sp. protein, on the functionality of the recombinantly expressed R. rubrum Rubisco. All these findings shed new light onto dinoflagellate Rubisco and may help in future obtainment of a native, active enzyme.

Pannexin-1 channel "fuels" by releasing ATP from bone marrow cells a state of sterile inflammation required for optimal mobilization and homing of hematopoietic stem cells.

An efficient harvest of hematopoietic stem/progenitor cells (HSPCs) after pharmacological mobilization from the bone marrow (BM) into peripheral blood (PB) and subsequent proper homing and engraftment of these cells are crucial for clinical outcomes from hematopoietic transplants. Since extracellular adenosine triphosphate (eATP) plays an important role in both processes as an activator of sterile inflammation in the bone marrow microenvironment, we focused on the role of Pannexin-1 channel in the secretion of ATP to trigger both egress of HSPCs out of BM into PB as well as in reverse process that is their homing to BM niches after transplantation into myeloablated recipient. We employed a specific blocking peptide against Pannexin-1 channel and noticed decreased mobilization efficiency of HSPCs as well as other types of BM-residing stem cells including mesenchymal stroma cells (MSCs), endothelial progenitors (EPCs), and very small embryonic-like stem cells (VSELs). To explain better a role of Pannexin-1, we report that eATP activated Nlrp3 inflammasome in Gr-1+ and CD11b+ cells enriched for granulocytes and monocytes. This led to release of danger-associated molecular pattern molecules (DAMPs) and mitochondrial DNA (miDNA) that activate complement cascade (ComC) required for optimal egress of HSPCs from BM. On the other hand, Pannexin-1 channel blockage in transplant recipient mice leads to a defect in homing and engraftment of HSPCs. Based on this, Pannexin-1 channel as a source of eATP plays an important role in HSPCs trafficking.

Deficiency of Selected Cathepsins Does Not Affect the Inhibitory Action of ECTV on Immune Properties of Dendritic Cells.

Ectromelia virus (ECTV), an orthopoxvirus, undergoes productive replication in conventional dendritic cells (cDCs), resulting in the inhibition of their innate and adaptive immune functions. ECTV replication rate in cDCs is increased due to downregulation of the expression of cathepsins - cystein proteases that orchestrate several steps during DC maturation. Therefore, this study was aimed to determine if downregulation of cathepsins, such as B, L or S, disrupts cDC capacity to induce activating signals in T cells or whether infection of cDCs with ECTV further weakens their functions as antigen-presenting cells. Our results showed that cDCs treated with siRNA against cathepsin B, L and S synthesize similar amounts of pro-inflammatory cytokines and exhibit comparable ability to mature and stimulate alloreactive CD4+ T cells, as untreated wild type (WT) cells. Moreover, ECTV inhibitory effect on cDC innate and adaptive immune functions, observed especially after LPS treatment, was comparable in both cathepsin-silenced and WT cells. Taken together, the absence of cathepsins B, L and S has minimal, if any, impact on the inhibitory effect of ECTV on cDC immune functions. We assume that the virus-mediated inhibition of cathepsin expression in cDCs represents more a survival mechanism than an immune evasion strategy.

The Influence of Storage Temperature and Packaging Technology on the Durability of Ready-to-Eat Preservative-Free Meat Bars with Dried Plasma.

Food business operators must include the results of shelf life testing in their HACCP plan. Ready-to-eat preservative-free meat products enriched with blood plasma are an unfathomable area of research in food safety. We tested modified atmosphere (80% N2 and 20% CO2) and vacuum packaged RTE preservative-free baked and smoked pork bars with dried blood plasma for Aerobic Plate Count, yeast and mould, lactic acid bacteria, Staphylococcus aureus, Enterobacteriaceae, Escherichia coli, and Campylobacter spp., and the presence of Listeria monocytogenes and Salmonella spp. during storage (temperatures from 4 to 34 °C) up to 35 days after production. The obtained data on the count of individual groups of microorganisms were subjected to analysis of variance (ANOVA) and statistically tested (Student's t-test with the Bonferroni correction); for temperatures at which there were statistically significant differences and high numerical variability, the trend of changes in bacterial counts were visualised using mathematical modelling. The results show that the optimal storage conditions are refrigerated temperatures (up to 8 °C) for two weeks. At higher temperatures, food spoilage occurred due to the growth of aerobic bacteria, lactic acid bacteria, yeast, and mould. The MAP packaging method was more conducive to spoilage of the bars, especially in temperatures over 8 °C.

Biodegradable Fiducial Markers for Bimodal Near-Infrared Fluorescence- and X-ray-Based Imaging.

This study aimed to evaluate, for the first time, implantable, biodegradable fiducial markers (FMs), which were designed for bimodal, near-infrared fluorescence-based (NIRF) and X-ray-based imaging. The developed FMs had poly(l-lactide-co-caprolactone)-based core-shell structures made of radiopaque (core) and fluorescent (shell) composites with a poly(l-lactide-co-caprolactone) matrix. The approved for human use contrast agents were utilized as fillers. Indocyanine green was applied to the shell material, whereas in the core materials, iohexol and barium sulfate were compared. Moreover, the possibility of tailoring the stability of the properties of the core materials by the addition of hydroxyapatite (HAp) was examined. The performed in situ (porcine tissue) and in vivo experiment (rat model) confirmed that the developed FMs possessed pronounced contrasting properties in NIRF and X-ray imaging. The presence of HAp improved the radiopacity of FMs at the initial state. It was also proved that, in iohexol-containing FMs, the presence of HAp slightly decreased the stability of contrasting properties, while in BaSO4-containing ones, changes were less pronounced. A comprehensive material analysis explaining the differences in the stability of the contrasting properties was also presented. The tissue response around the FMs with composite cores was comparable to that of the FMs with a pristine polymeric core. The developed composite FMs did not cause serious adverse effects on the surrounding tissues even when irradiated in vivo. The developed FMs ensured good visibility for NIRF image-supported tumor surgery and the following X-ray image-guided radiotherapy. Moreover, this study replenishes a scanty report regarding similar biodegradable composite materials with a high potential for application.

A Novel Evidence That Mannan Binding Lectin (MBL) Pathway of Complement Cascade Activation is Involved in Homing and Engraftment of Hematopoietic Stem Progenitor Cells (HSPCs).

Delayed homing and engraftment of hematopoietic stem progenitor cells (HSPCs) or even failure to engraft at all is significant clinical problem after hematopoietic transplant. Therefore, in order to develop more efficient homing and engraftment facilitating strategies it is important to learn more about this process. Our team has postulated that myeloablative conditioning for transplantation induces in bone marrow (BM) microenvironment a state of sterile inflammation in which elements of innate immunity activated by radio- or chemotherapy conditioning for transplant play an important role. In frame with this claim we reported that a significant role in this process plays activation of complement cascade (ComC). Accordingly, mice that that lack a fifth component (C5) of ComC turned out to engraft poorly with normal syngeneic BM cells as compared to normal control animals. In extension of our previous studies we provide for first time evidence that mannan binding lectin (MBL) pathway is involved in activation of ComC in myeloablated transplant recipient BM and thus plays an important role in homing and engraftment of HSPCs. To support this MBL-KO mice show significant defect in hematopoietic reconstitution after hematopoietic transplantation. This correlates with a decrease in expression of stromal derived factor-1 (SDF-1) and impaired activation of Nlrp3 inflammasome in irradiated BM of these mice.

Novel Evidence that Purinergic Signaling - Nlrp3 Inflammasome Axis Regulates Circadian Rhythm of Hematopoietic Stem/Progenitor Cells Circulation in Peripheral Blood.

We found that circadian changes in ATP level in peripheral blood (PB) activate the Nlrp3 inflammasome, which triggers diurnal release of hematopoietic stem/progenitor cells (HSPCs) from murine bone marrow (BM) into PB. Consistent with this finding, we observed circadian changes in expression of mRNA for Nlrp3 inflammasome-related genes, including Nlrp3, caspase 1, IL-1ß, IL-18, gasdermin (GSDMD), HMGB1, and S100A9. Circadian release of HSPCs from BM into PB as well as expression of Nlrp3-associated genes was decreased in mice in which pannexin 1-mediated secretion of ATP was inhibited by the blocking peptide 10Panx and in animals exposed to the specific small-molecule inhibitor of the Nlrp3 inflammasome MCC950. In addition to HSPCs, a similar decrease in diurnal cell counts was observed for mesenchymal stromal cells (MSCs), endothelial progenitor cells (EPCs), and very small embryonic-like stem cells (VSELs). These results shed more light on the complexity of circadian regulation of HSPC release into PB, which is coordinated in a purinergic signaling-, innate immunity-dependent manner. Moreover, in addition to circadian changes in expression of the Nlrp3 inflammasome we also observed diurnal changes in expression of other inflammasomes, including Aim2, Nrp1a, and Nlrp1b.

Nlrp3 Inflammasome Signaling Regulates the Homing and Engraftment of Hematopoietic Stem Cells (HSPCs) by Enhancing Incorporation of CXCR4 Receptor into Membrane Lipid Rafts.

Fast and efficient homing and engraftment of hematopoietic stem progenitor cells (HSPCs) is crucial for positive clinical outcomes from transplantation. We found that this process depends on activation of the Nlrp3 inflammasome, both in the HSPCs to be transplanted and in the cells in the recipient bone marrow (BM) microenvironment. For the first time we provide evidence that functional deficiency in the Nlrp3 inflammasome in transplanted cells or in the host microenvironment leads to defective homing and engraftment. At the molecular level, functional deficiency of the Nlrp3 inflammasome in HSPCs leads to their defective migration in response to the major BM homing chemoattractant stromal-derived factor 1 (SDF-1) and to other supportive chemoattractants, including sphingosine-1-phosphate (S1P) and extracellular adenosine triphosphate (eATP). We report that activation of the Nlrp3 inflammasome increases autocrine release of eATP, which promotes incorporation of the CXCR4 receptor into membrane lipid rafts at the leading surface of migrating cells. On the other hand, a lack of Nlrp3 inflammasome expression in BM conditioned for transplantation leads to a decrease in expression of SDF-1 and danger-associated molecular pattern molecules (DAMPs), which are responsible for activation of the complement cascade (ComC), which in turn facilitates the homing and engraftment of HSPCs.

Induction of heme oxygenase-1 is a beneficial response in a murine model of venous thrombosis.

The induction of heme oxygenase-1 (HO-1) may protect against tissue injury. The present study examines the induction of HO-1 in a murine model of venous thrombosis and explores the downstream consequences of this induction. In a model of stasis-induced thrombosis created by ligation of the inferior vena cava, HO-1 expression is markedly induced. Such expression occurs primarily in smooth muscle cells in the venous wall and in leukocytes infiltrating the venous wall and clot. To determine the significance of HO-1 induction in venous thrombosis, this model was imposed in HO-1(+/+) and HO-1(-/-) mice. The initial clot size did not differ in either group by day 2, but was significantly larger in HO-1(-/-) mice by day 10, where an exaggerated inflammatory response in the venous wall was also observed. Following ligation of the inferior vena cava, HO-1(-/-) mice exhibited increased nuclear factor kappaB activation and markedly increased up-regulation of tissue factor, selectins, inflammatory cytokines, and matrix metalloproteinase-9, the latter incriminated in both clot lysis and vascular injury. We conclude that HO-1 deficiency impairs thrombus resolution and exaggerates the inflammatory response to thrombus formation. These findings offer insight into recent observations that polymorphisms in the HO-1 gene may increase the risk for recurrent venous thrombosis and dysfunction of hemodialysis arteriovenous fistulas, the latter caused, in part, by thrombosis.

Timing of referral for vascular access placement: a systematic review.

OBJECTIVE: This review was conducted to determine the optimal timing for referring patients with end-stage renal disease to vascular surgery for access placement. METHODS: A systematic review of the electronic databases (MEDLINE, EMBASE, Current Contents, Cochrane CENTRAL and Web of Science) was conducted through March 2007. Randomized and observational studies were eligible if they compared an early referral cohort with a late referral cohort in terms of patient-important outcomes such as death, access-related sepsis, and hospitalization related to access complications. RESULTS: We found no studies that fulfilled eligibility criteria. CONCLUSION: At the present time, the optimal timing for referral to vascular surgery for vascular access placement is based on expert opinion and choices made by patients and physicians.

Autogenous versus prosthetic vascular access for hemodialysis: a systematic review and meta-analysis.

OBJECTIVES: The autogenous arteriovenous access for chronic hemodialysis is recommended over the prosthetic access because of its longer lifespan. However, more than half of the United States dialysis patients receive a prosthetic access. We conducted a systematic review to summarize the best available evidence comparing the two accesses types in terms of patient-important outcomes. METHODS: We searched electronic databases (MEDLINE, EMBASE, Cochrane CENTRAL, Web of Science and SCOPUS) and included randomized controlled trials and controlled cohort studies. We pooled data for each outcome using a random effects model to estimate the relative risk (RR) and its associated 95% confidence interval (CI). We estimated inconsistency caused by true differences between studies using the I(2) statistic. RESULTS: Eighty-three studies, of which 80 were nonrandomized, met eligibility criteria. Compared with the prosthetic access, the autogenous access was associated with a significant reduction in the risk of death (RR, 0.76; 95% CI, 0.67-0.86; I(2) = 48%, 27 studies) and access infection (RR, 0.18; 95% CI, 0.11-0.31; I(2) = 93%, 43 studies), and a nonsignificant reduction in the risk of postoperative complications (hematoma, bleeding, pseudoaneurysm and steal syndrome, RR 0.73; 95% CI, 0.48-1.16; I(2) = 65%, 31 studies) and length of hospitalization (pooled weighted mean difference -3.8 days; 95% CI, -7.8 to 0.2; P = .06). The autogenous access also had better primary and secondary patency at 12 and 36 months. CONCLUSION: Low-quality evidence from inconsistent studies with limited protection against bias shows that autogenous access for chronic hemodialysis is superior to prosthetic access.

Surveillance of arteriovenous hemodialysis access: a systematic review and meta-analysis.

OBJECTIVES: Hemodialysis centers regularly survey arteriovenous (AV) accesses for signs of dysfunction. In this review, we synthesize the available evidence to determine to what extent proactive vascular access monitoring affects the incidence of AV access thrombosis and abandonment compared with clinical monitoring. METHODS: We searched electronic databases (MEDLINE, EMBASE, Cochrane CENTRAL, Web of Science, and SCOPUS) and sought references from experts, bibliographies of included trials, and articles that cited included studies. Two reviewers independently assessed trial quality and extracted data. We used random effects meta-analysis to estimate the pooled relative risk (RR) and 95% confidence interval (CI) across studies and conducted subgroup analyses to explain heterogeneity. The I(2) statistic was used to assess heterogeneity of treatment effect among trials. RESULTS: Nine studies (1363 patients) compared a strategy of surveillance vs clinical monitoring. A vascular intervention to maintain or restore patency was provided to both groups if needed. Surveillance followed by intervention led to a nonsignificant reduction of the risk of access thrombosis (RR, 0.82; 95% CI, 0.58-1.16; I(2) = 37%) and access abandonment (RR, 0.80; 95% CI, 0.51-1.25; I(2) = 60%). Three studies (207 patients) compared the effect of vascular interventions vs observation in patients with abnormal surveillance result. Vascular interventions after an abnormal AV access surveillance led to a significant reduction of the risk of access thrombosis (RR, 0.53; 95% CI, 0.36-0.76) and a nonsignificant reduction of the risk of access abandonment (RR, 0.76; 95% CI, 0.43-1.37). CONCLUSION: Very low quality evidence yielding imprecise results suggests a potentially beneficial effect of AV access surveillance followed by interventions to restore patency. This inference, however, is weak and will require randomized trials of AV access surveillance vs clinical monitoring for rejection or confirmation.

Testosterone use in men with sexual dysfunction: a systematic review and meta-analysis of randomized placebo-controlled trials.

OBJECTIVE: To conduct a systematic review and meta-analysis of randomized placebo-controlled trials to measure the effect of testosterone use on sexual function in men with sexual dysfunction and varying testosterone levels. METHODS: Librarian-designed search strategies were used to search the MEDLINE (1966 to October 2004), EMBASE (1988 to October 2004), and Cochrane CENTRAL (inception to October 2004) databases. The MEDLINE search was rerun in March 2005. We also reviewed reference lists from included studies and content expert files. We selected randomized placebo-controlled trials of testosterone vs placebo that enrolled men with sexual dysfunction and measured satisfaction with erectile function and libido and overall sexual satisfaction. RESULTS: We included 17 trials (N = 862 participants) in this review. Trials that enrolled participants with low testosterone levels showed (1) a moderate nonsignificant and inconsistent effect of testosterone use on satisfaction with erectile function (random-effects pooled effect size, 0.80; 95% confidence interval [CI], -0.10 to 1.60), (2) a large effect on libido (pooled effect size, 1.31; 95% CI, 0.40 to 2.25), and (3) no significant effect on overall sexual satisfaction. Trials that enrolled patients with low-normal and normal testosterone levels at baseline showed testosterone that caused (1) a small effect on satisfaction with erectile function (pooled effect size, 0.34; 95% CI, 0.03 to 0.65), (2) moderate nonsignificant effect on libido (pooled effect size, 0.41; 95% CI, -0.01 to 0.83), and (3) no significant effect on overall sexual satisfaction. CONCLUSION: Testosterone use in men is associated with small improvements in satisfaction with erectile function and moderate improvements in libido. Unexplained inconsistent results across trials, wide CIs, and possible reporting bias weaken these inferences.

Testosterone and cardiovascular risk in men: a systematic review and meta-analysis of randomized placebo-controlled trials.

OBJECTIVE: To conduct a systematic review and meta-analysis of randomized trials that assessed the effect of testosterone use on cardiovascular events and risk factors in men with different degrees of androgen deficiency. METHODS: Librarian-designed search strategies were used to search the MEDLINE (1966 to October 2004), EMBASE (1988 to October 2004), and Cochrane CENTRAL (inception to October 2004) databases. The database search was performed again in March 2005. We also reviewed reference lists from included studies and content expert files. Eligible studies were randomized trials that compared any formulation of commercially available testosterone with placebo and that assessed cardiovascular risk factors (lipid fractions, blood pressure, blood glucose), cardiovascular events (cardiovascular death, nonfatal myocardial infarction, angina or claudication, revascularization, stroke), and cardiovascular surrogate end points (ie, laboratory tests indicative of cardiac or vascular disease). Using a standardized data extraction form, we collected data on participants, testosterone administration, and outcome measures. We assessed study quality with attention to allocation concealment, blinding, and loss to follow-up. RESULTS: The 30 trials included 1642 men, 808 of whom were treated with testosterone. Overall, the trials had limited reporting of methodological features that prevent biased results (only 6 trials reported allocation concealment), enrolled few patients, and were of brief duration (only 4 trials followed up patients for > 1 year). The median loss to follow-up across all 30 trials was 9%. Testosterone use in men with low testosterone levels led to inconsequential changes in blood pressure and glycemia and in all lipid fractions (total cholesterol: odds ratio [OR], -0.22; 95% confidence interval [CI], -0.71 to 0.27; high-density lipoprotein cholesterol: OR, -0.04; 95% CI, -0.39 to 0.30; low-density lipoprotein cholesterol: OR, 0.06; 95% CI, -0.30 to 0.42; and triglycerides: OR, -0.27; 95% CI, -0.61 to 0.08); results were similar in patients with low-normal to normal testosterone levels. The OR between testosterone use and any cardiovascular event pooled across trials that reported these events (n = 6) was 1.82 (95% CI, 0.78 to 4.23). Several trials failed to report data on measured outcomes. For reasons we could not explain statistically, the results were inconsistent across trials. CONCLUSION: Currently available evidence weakly supports the inference that testosterone use in men is not associated with important cardiovascular effects. Patients and clinicians need large randomized trials of men at risk for cardiovascular disease to better inform the safety of long-term testosterone use.

Modelling the Growth Rate of Listeria Monocytogenes in Cooked Ham Stored at Different Temperatures.

INTRODUCTION: The purpose of the study was to determine and model the growth rates of L. monocytogenes in cooked cured ham stored at various temperatures. MATERIAL AND METHODS: Samples of cured ham were artificially contaminated with a mixture of three L. monocytogenes strains and stored at 3, 6, 9, 12, or 15ºC for 16 days. The number of listeriae was determined after 0, 1, 2, 3, 5, 7, 9, 12, 14, and 16 days. A series of decimal dilutions were prepared from each sample and plated onto ALOA agar, after which the plates were incubated at 37ºC for 48 h under aerobic conditions. The bacterial counts were logarithmised and analysed statistically. Five repetitions of the experiment were performed. RESULTS: Both storage temperature and time were found to significantly influence the growth rate of listeriae (P > 0.01). The test bacteria growth curves were fitted to three primary models: the Gompertz, Baranyi, and logistic. The mean square error (MSE) and Akaike's information criterion (AIC) were calculated to evaluate the goodness of fit. It transpired that the logistic model fit the experimental data best. The natural logarithms of L. monocytogenes' mean growth rates from this model were fitted to two secondary models: the square root and polynomial. CONCLUSION: Modelling in both secondary types can predict the growth rates of L. monocytogenes in cooked cured ham stored at each studied temperature, but mathematical validation showed the polynomial model to be more accurate.

Testosterone use in men and its effects on bone health. A systematic review and meta-analysis of randomized placebo-controlled trials.

CONTEXT: Androgen-deficient men are at increased risk of osteoporosis. The extent to which testosterone can prevent and treat osteoporosis in men remains unclear. OBJECTIVE AND DESIGN: We performed a systematic review and meta-analysis of randomized placebo-controlled trials in men to estimate the effect of testosterone use on bone health outcomes. DATA SOURCES: The review encompassed librarian-designed search strategies using MEDLINE (1966 to March 2005), EMBASE (1988 to March 2005), and Cochrane CENTRAL (inception to March 2005); a review of reference lists from included studies; and content expert files. DATA COLLECTION: Independently and in duplicate, we assessed the methodological quality of the eligible trials and collected data on bone mineral density and bone fractures at the longest point of complete follow-up. DATA SYNTHESIS: We included eight trials enrolling 365 patients. Two trials followed patients for more than 1 yr. Meta-analysis of these trials showed that, compared with placebo, im testosterone was associated with an 8% (95% confidence interval, 4%, 13%) gain in lumbar bone mineral density and transdermal testosterone had no significant impact. Testosterone use was associated with a nonsignificant 4% (95% confidence interval, -2%, 9%) gain in femoral neck bone mineral density with unexplained differences in results across trials (26% of these differences were not explained by chance alone). No trials measured or reported the effect of testosterone on fractures. CONCLUSIONS: Intramuscular testosterone moderately increased lumbar bone density in men; the results on femoral neck bone density are inconclusive. Without bone fracture data, the available trials offer weak and indirect inferences about the clinical efficacy of testosterone on osteoporosis prevention and treatment in men.