Nonoptimal DNA topoisomerases allow maintenance of supercoiling levels and improve fitness of Streptococcus pneumoniae

Fluoroquinolones, which target gyrase and topoisomerase IV, are used for treating Streptococcus pneumoniae infections. Fluoroquinolone resistance in this bacterium can arise via point mutation or interspecific recombination with genetically related streptococci. Our previous study on the fitness cost of resistance mutations and recombinant topoisomerases identified GyrAE85K as a high-cost change. However, this cost was compensated for by the presence of a recombinant topoisomerase IV (parC and parE recombinant genes) in strain T14. In this study, we purified wild-type and mutant topoisomerases and compared their enzymatic activities. In strain T14, both gyrase carrying GyrAE85K and recombinant topoisomerase IV showed lower activities (from 2.0- to 3.7-fold) than the wild-type enzymes. These variations of in vitro activity corresponded to changes of in vivo supercoiling levels that were analyzed by two-dimensional electrophoresis of an internal plasmid. Strains carrying GyrAE85K and nonrecombinant topoisomerases had lower (11.1% to 14.3%) supercoiling density (σ) values than the wild type. Those carrying GyrAE85K and recombinant topoisomerases showed either partial or total supercoiling level restoration, with σ values being 7.9% (recombinant ParC) and 1.6% (recombinant ParC and recombinant ParE) lower than those for the wild type. These data suggested that changes acquired by interspecific recombination might be selected because they reduce the fitness cost associated with fluoroquinolone resistance mutations. An increase in the incidence of fluoroquinolone resistance, even in the absence of further antibiotic exposure, is envisaged.     

Prolonged lymphocyte depletion by single-dose rabbit anti-thymocyte globulin and alemtuzumab in kidney transplantation

Although antibody induction has gained in popularity, two agents are rarely combined. We retrospectively analyzed peripheral lymphocyte phenotypes of renal transplant recipients who received induction therapy with a different antibody/combination: alemtuzumab(C1H), Thymoglobulin(rATG), daclizumab(Dac), rATG+C1H, and rATG+Dac. CD4+ T-cells were suppressed by C1H and rATG+C1H, as well as by rATG and rATG+Dac but to a lesser extent. The effect lasted for 3 years at around 40% of baseline values. CD8+ T-cells showed a similar trend but had a more rapid recovery to baseline. CD19+ B-cells were effectively suppressed for 2 months by C1H and rATG+C1H, and abruptly returned to baseline afterwards; suppression by rATG(7 doses) was modest but lasted longer. A higher proportion of CD56+CD16+ Natural Killer cells in C1H treated patients suggested a relatively spared effect of C1H on this cell type. Low CD25+ T-cells by 5-dose Dac returned to baseline around 6 months, whereas rATG+C1H and rATG+Dac showed persistent effect. CD4+CD25hi T-cells were suppressed by both rATG+C1H and rATG+Dac, but the initial proportion of CD4+CD25hi T-cells among CD4+ T-cells and CD4+CD25hi/CD4+CD25lo ratio were significantly higher in rATG+C1H. Overall, with extensive and persistent lymphocyte suppression by a simple administration of agents, single-dose rATG+C1H induction can be an alternative in renal transplantation.     

Human papilloma virus and esophageal carcinoma in a Latin-American region

AIM： To investigate the presence of high-risk human papilloma virus （HPV） in esophageal squamous cell carcinomas （ESCCs） in a non-selected Mexican population. METHODS： Cases with a pathological diagnosis of squamous cell carcinoma of the esophagus were obtained from Department of Pathology files, at the National Cancer Institute in Mexico City during the period between 2000 and 2008. Slides from each case were reviewed and cases with sufficient neoplastic tissue were selected for molecular analysis. DNA was extracted from paraffin-embedded tissue samples for polymerase chain reaction analysis to detect HPV DNA sequences. Demographic and clinical data of each patient were retrieved from corresponding clinical records. RESULTS： HPV was detected in 15 （25%） of ESCCs. HPV-16 was the most frequently observed genotype, followed by HPV-18; HPV-59 was also detected in one case. Unfortunately, HPV genotype could not be established in three cases due to lack of material for direct sequencing, although universal primers detected the presence of HPV generic sequences. No low-risk HPV genotypes were found nor was HPV-16/18 co- infection. HPV presence in ESCC was not significantly associated with gender, age, alcohol consumption, smoking, anatomic location, or histologic grade. All patients belonged to low and very low socioeconomic strata, and were diagnosed at advanced disease stage. Male patients were most commonly affected and the male：female ratio in HPV-positive ESCC increased two- fold in comparison with HPV-negative cases （6.5：1 vs 3/1：1）. CONCLUSION： High prevalence of high-risk HPV in ESCC in Mexico does not support the hypothesis that HPV-associated ESCC is more common in areas with higher ESCC incidence rates.     

A meta-analytic study of predictors for loneliness during adolescence

BACKGROUND: Extensive research has been completed to investigate loneliness in adolescents over the past several decades; identification of key predictors for loneliness was needed using meta-analytic techniques. OBJECTIVES: To identify predictors for loneliness in adolescents through a comprehensive review of the literature and to use quantitative meta-analysis to determine the magnitude of the relationships between each predictor and loneliness. METHODS: The literature reviewed included 242 studies published or unpublished between 1980 and 2004, of which 95 met the inclusion criteria. Eleven key predictors for loneliness were identified in the 95 studies. A meta-analysis was conducted on each of the 11 predictors in relation to loneliness. RESULTS: Four predictors (gender, depression, shyness, and self-esteem) had large effect sizes, four predictors (social support, social anxiety, maternal expressiveness, and paternal expressiveness) had large medium to medium effect sizes, two predictors (stress and self-disclosure) had low effect sizes, and one predictor (age) had a very low effect size. DISCUSSION: Theories of loneliness served as a framework for interpreting the findings of the meta-analysis. The most powerful predictors can be used in intervention studies aimed at reducing loneliness in adolescents.     

Plant-borne human contamination by fascioliasis

Contamination by fasciolids takes place through ingestion of metacercariae attached to vegetables. Experimental studies were performed with plant-made foods suggesting a role in human contamination in Iran and on the usefulness of potassium permanganate as a preventive tool for killing metacercariae attached to vegetables used in salads in Egypt. In the foods assayed, although viability decreases with time, a high percentage of the metacercariae were still alive 2 and 4 weeks after preparation. Infection of laboratory animals proved that metacercariae kept their infectivity. The 5-minute tests of potassium permanganate effects showed that metacercarial viability was not affected even at the very high doses of 300, 600, and 1,200 mg/L. Careful, subsequent washing of leaves and vegetables with water is therefore needed after its application. A review on similar studies performed with metacercariae belonging to fasciolid and other trematode species affecting humans is included.     

Targeting the CYP2B 1/cyclophosphamide suicide system to fibroblast growth factor receptors results in a potent antitumoral response in pancreatic cancer models

The CYP2B1/cyclophosphamide (CPA) suicide gene therapy approach has been shown to be highly promising in clinical trials for the treatment of pancreatic cancer. However, delivering the therapeutic gene to a sufficient number of tumor cells able to trigger a complete response remains a challenge. Target-specific delivery of adenovirus to fibroblast growth factor receptors (FGFRs) has been obtained in a variety of tumor models and has been shown to highly increase transduction efficiency. In the present paper we have tested the therapeutic outcome of retargeting the adenoviral vector, Ad-CYP2B1, to FGFRs, using an FGF2-Fab' conjugate, in pancreatic cancer models. First, we show a heterogeneous subcellular distribution of overexpressed FGFR-1 in pancreatic cancer cells. Higher transduction efficiency was observed in five of the six cell lines studied after FGF2-AdGFPLuc infection. Interestingly, an association between FGFR-1 membrane cell expression and viral entry was found. Moreover, tumors injected with FGF2-AdGFPLuc showed enhanced and persistent transgene expression. Importantly, we demonstrate the relevant enhanced cytotoxic effect of the FGF2-Ad-CYP2B]/CPA system in four of the six cell lines studied. Moreover, retargeting Ad-CYP2B1/CPA to FGFRs resulted in a potent antitumoral effect and in an increased survival rate, in two human pancreatic xenograft models. Thus, our results indicate that redirecting adenoviruses to FGFRs highly increases the potency of the suicide system CYP2B1/CPA. Consequently, it may constitute a promising approach to the treatment of patients with pancreatic tumors, in which a high proportion of FGF receptors precisely localize to the plasma membrane.     

Comparison of Sexual and Drug Use Behaviors Between Female Sex Workers in Tijuana and Ciudad Juarez,Mexico

Female sex workers (FSWs) have been documented to have high rates of sexually transmitted diseases and HIV in many parts of the world. However, little work has been done to characterize the prevalence of these infections along the U.S.–Mexican border, where sexual tourism and culturally sanctioned sex work among nationals is widespread. The objective of this study was to compare differences in background characteristics, HIV risk behaviors, drug use, and sexually transmitted infection/HIV prevalence between FSWs who participated in a behavioral risk intervention in two U.S.–Mexican border cities. Baseline data were collected from March 2004 through September 2005. Data from 295 FSWs were compared between Tijuana and Ciudad (Cd.) Juarez. Among 155 FSWs in Tijuana and 140 in Cd. Juarez, HIV seroprevalence was 4.8% and 4.9%, respectively. FSWs in Cd. Juarez were more likely to test positive for active syphilis (31.3%) compared with Tijuana (11.8%) but did not differ in terms of the prevalence of gonorrhea and chlamydia. FSWs in both sites reported high levels of unprotected sex and use of drugs; however, FSWs in Cd. Juarez were more likely than those in Tijuana to ever have injected drugs (75% vs. 25%, p <.001). Heroin and cocaine use and injection drug use were significantly more common in Cd. Juarez, whereas methamphetamine use was more common in Tijuana. Injection of vitamins was common in both cities. Logistic regression analyses suggested that being younger, working in Cd. Juarez, and using heroin or cocaine were independently associated with active syphilis infection. In Tijuana, methamphetamine use was strongly associated with active syphilis infection. These preliminary results suggest that risk profiles for HIV/sexually transmitted infection among FSWs in these two Mexico–U.S. border cities differ, suggesting a need to tailor interventions to the specific needs in each city.     

<Emphasis Type="Italic">Hysterothylacium aduncum</Emphasis>, the only anisakid parasite of sardines (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) from the southern and eastern coasts of Spain

An epidemiological study was carried out on the anisakids in sardines (Sardina pilchardus) from the southern (Atlantic and Mediterranean) and eastern coasts of Spain. Length of fish was from 12.2–21.0 cm. The anisakids found were identified as the third larval stage (L3) of Hysterothylacium aduncum, with a total prevalence of 11.85%. Prevalence within the host was 9.64% in viscera and 4.69 % in muscle. The highest infection parameters were found in fish from the east coast (western Balearic Sea) with prevalence of 25.21%, mean intensity of 2.10, and mean abundance of 0.52. No worms of the genus Anisakis were found in the 359 sardines analyzed.     

Suppression of MMP-9 expression in brain microvascular endothelial cells (BMVEC) using a gold nanorod (GNR)-siRNA nanoplex

Inhibition of Matrix metalloproteinase-9 (MMP-9) activity using delivery of short interfering RNA (siRNA) molecules to brain microvascular endothelial cells (BMVECs) that constitute the BBB may have a significant impact on reducing the BBB permeability. Gold nano rods (GNRs) can electrostatically bind with MMP-9 siRNA to form a nanoplex and the uptake of this nanoplex by BMVEC cells can result in suppression of MMP-9 expression. The current study explores if this GNR-MMP-9 siRNA nanoplex gene silencing modulates the expression of tight junction (TJ) proteins in the BMVEC. The endothelial TJ's of the BBB play a critical role in controlling cellular traffic into the central nervous system. We hypothesize that silencing of the MMP-9 gene expression in BMVEC will increase the expression of TJ proteins thereby decrease endothelial permeability. Our results showed a significant increase in the gene and protein expression of TJ proteins: ZO-1, Occludin and Claudin-5 in BMVEC cells that were transfected with the GNRs-siRNA-MMP-9 nanoplex suggesting that BBB disruption, which results from loss of TJ function due to MMP-9 activation during neuroinflammation can be prevented by silencing MMP-9 expression.