Chlamydophila abortus infection in the mouse: a useful model of the ovine disease

Chlamydophila (C.) abortus is an obligate intracellular bacterium able to colonize the placenta of several species of mammals, which may induce abortion in the last third of pregnancy. The infection affects mainly small ruminants resulting in major economic losses in farming industries worldwide. Furthermore, its zoonotic risk has been reported in pregnant farmers or abattoir workers. Mouse models have been widely used to study both the pathology of the disease and the role of immune cells in controlling infection. Moreover, this animal experimental model has been considered a useful tool to evaluate new vaccine candidates and adjuvants that could prevent abortion and reduce fetal death. Future studies using these models will provide and reveal information about the precise mechanisms in the immune response against C. abortus and will increase the knowledge about poorly understood issues such as chlamydial persistence.

Surface-adsorbed fibrinogen and fibrin may activate the contact activation system

INTRODUCTION

This study was designed to investigate whether fibrinogen, soluble desAA-fibrin, and insoluble desAABB-fibrin are able to induce clotting by triggering the plasma contact activation system when adsorbed to polystyrene.

MATERIALS AND METHODS

The above-mentioned substances were individually prepared on polystyrene meshwork squares, and then exposed to a purified FXII solution or non-calcium containing plasma (citrated and dialyzed normal pooled plasma) in polystyrene cuvettes coated with surface-immobilized heparin, to completely block contact activation and the coagulation mechanism that might be induced by the cuvette surfaces. Sodium glass beads were used as the reference material.

RESULTS

On exposure to purified FXII solution and plasma, all the tested materials adsorbed and activated FXII to varying degrees. This activation led to the formation of FXIa in the exposed plasma, with the highest activation occurring upon exposure to glass, desAA-fibrin and desAABB-fibrin and the lowest upon exposure to fibrinogen-adsorbed or unmodified polystyrene meshwork squares. Following recalcification, in cuvettes with surface-immobilized heparin, a spectrophotometric assay showed that the surface-exposed plasma aliquots clotted within 5 min after contact with glass, within 10 to 15 min after contact with the two forms of fibrin, and somewhat longer after contact with adsorbed fibrinogen. The longest lag phase, close to 20 min, occurred in plasma exposed to unmodified polystyrene meshwork. Whole blood deposited in surface heparinized cuvettes directly from the cubital vein did not clot during the observation time (2 h).

CONCLUSIONS

These results indicate that domains induced by conformational changes in adsorbed fibrinogen and fibrin are capable of activating adsorbed proenzymes and that various forms of fibrin are considerably stronger activators of the contact activation system than are adsorbed fibrinogen or a polystyrene meshwork. The delayed coagulation in plasma exposed to the unmodified polystyrene meshwork can be explained by a two-step process: first, adsorption of fibrinogen, and second, activation of FXII. Under our experimental conditions, the adsorption and activation of FXII on fibrinogen and fibrin seems to be an important mechanism for triggering coagulation.

Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers

Self-assembled monolayers (SAMs) are widely used in a variety of emerging applications for surface modification of metals and oxides. Here, we demonstrate a new type of molecular self-assembly: the growth of organosilane SAMs at the surface of organic semiconductors. Remarkably, SAM growth results in a pronounced increase of the surface conductivity of organic materials, which can be very large for SAMs with a strong electron-withdrawing ability. For example, the conductivity induced by perfluorinated alkyl silanes in organic molecular crystals approaches 10(-5) S per square, two orders of magnitude greater than the maximum conductivity typically achieved in organic field-effect transistors. The observed large electronic effect opens new opportunities for nanoscale surface functionalization of organic semiconductors with molecular self-assembly. In particular, SAM-induced conductivity shows sensitivity to different molecular species present in the environment, which makes this system very attractive for chemical sensing applications.

Role of ERCC1, XRCC3, Aurora A and TGFBR1 single-nucleotide polymorphisms (SNP) and CHFR and 14–3-3σ methylation in a customized cisplatin (cis) trial based on ERCC1 mRNA levels in stage IV non-small cell lung cancer (NSCLC) patients (pts)

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Background: The primary aim of this trial was response. In both the control arm and in the genotypic arm with low tumor ERCC1 mRNA levels, pts received docetaxel (doc)/cis; in the genotypic arm with high tumor ERCC1 mRNA levels, pts received doc/gemcitabine. Response was significantly higher in the genotypic arms. We examined 324 pts for genetic markers that could influence response, including ERCC1 118 C/T, ERCC1 C8092A, XRCC3 241 (Thr to Met), Aurora A 91 T>A, Aurora A 169G>A, a SNP within intron 7 of the TGFBR1 gene (Int7G24A), and an in-frame germline deletion (TGFBR1*6A). Methylation of 14–3-3s and CHFR were also analyzed. Methods: DNA from peripheral lymphocytes was used for genotyping (Taqman assay) and methylation-specific PCR was used for 14–3- 3s and CHFR in pretreatment serum DNA. Results: There were no differences in clinical characteristics among the different SNP types, except that pts with Aurora A 91 AA had higher tumor ERCC1 mRNA levels (P=0.005). No relationship was found between ERCC1 SNPs and tumor ERCC1 mRNA levels. A strong correlation was found between the Int7G24A and XRCC3 241 SNPs (P=0.03). The Int7G24A GA type had a higher odds ratio (OR) of response (OR 2.32) than the AA type (OR 3.15) (P=0.02). XRCC3 241 MetMet had a lower probability of response (OR 0.23) (P=0.04). No other differences in response were observed according to any of the other SNPs or methylation. In the multivariate model, the best response was observed in pts with performance status (PS) 0, low ERCC1 levels, and XRCC3 241 SNP ( Table ). Conclusions: Further research is warranted to define the role of theTGFBR1 Int7G24A gene in customized treatments.

No significant financial relationships to disclose.

[Table: see text]

Elevated levels of thioredoxin (Trx) in serum correlate with poor outcome in docetaxel (doc)/cisplatin (cis)-treated stage IV non-small cell lung cancer (NSCLC) patients (p)

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Background: Chemotherapy causes the production of reactive oxygen species (ROS), which facilitates cancer cell death. Trx protein functions as a ROS scavenger and a negative regulator of apoptosis signal regulating kinase-1 (ASK-1). High levels of Trx are associated with chemoresistance. 14–3-3s proteins are involved in cell cycle control and protein trafficking. Methods: Trx ELISA and 14- 3–3s methylation-specific PCR were performed in baseline serum from 107 stage IV NSCLC p treated with doc/cis. Results: Median age, 60 (range, 32–79); male, 87 (81.3%). PS: 0, 27 (25.2%); 1, 80 (74.8%). Adenocarcinoma, 46 (43.8%); squamous cell carcinoma, 40 (38.1%); 21 p had large cell or unspecified histology. Complete response, 1 p; partial response, 20 p; overall response rate, 20%. Median Trx level, 97.4 (range, 18.8–763.1). Serum was available for 14–3-3s methylation analysis in only 88 p. 14–3-3s was methylated in 43 p (48.9%). A significant correlation was observed between 14–3-3s methylation status and Trx levels ( Table ). 4 p with methylated and 17 with unmethylated 14–3-3s had Trx levels >182.8 (P=0.003). Median Trx levels were 103.5 in responders and 94.3 in non-responders (P=0.96). Time to progression (TTP) was 5.6 months (m) for 27 p with Trx <49.6, 4.4 m for 53 p with Trx 49.6–182.8, and 3.8 m for 27 p with Trx >182.8 (P=0.02). In a Cox multivariate analysis, Trx levels emerged as an independent variable for TTP when 14–3-3s was included in the model. Hazard ratios: 1.3 for PS1 (P=0.84); 1.05 for 14–3-3s unmethylated (P=0.22); 1.4 for Trx 49.6–182.8 and 1.95 for Trx >182.8 (P=0.04). Conclusions: Serum Trx levels can predict TTP in doc/cis-treated p. The additional role of 14–3-3s methylation may be more clearly demonstrated in cis/gemcitabine regimens.

No significant financial relationships to disclose.

[Table: see text]

Excision repair cross complementing 6 (ERCC6) single nucleotide polymorphism (SNP) and outcome to gemcitabine (gem)/cisplatin (cis) or docetaxel (doc)/cis in stage IV non-small cell lung cancer (NSCLC) patients (pts)

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Background: ERCC6 (alternate name CSB) is involved in both transcription coupled and base excision DNA repair, and the ERCC6 C-6530>G SNP is involved in gene regulation. Different levels of ERCC6 mRNA expression have been observed in cells according to ERCC6–6530 genotype. Methods: We investigated the ERCC6 C-6530>G SNP in 309 stage IV NSCLC pts treated with doc/cis (196 pts) and gem/cis (113 pts). DNA was extracted from peripheral lymphocytes and Taqman assay was used for SNP typing. Results: Distribution of ERCC6 genotypes was: CC 113 pts (36.6%); CG 157 pts (50.8%); GG 39 pts (12.6%). No differences in genotype were observed according to age, gender, performance status (PS), histology, chemotherapy regimen or second-line treatment. Overall time to progression (TTP) was 5.4 months (m) and median survival (MS) 9.9 m. No differences in TTP or MS were observed according to ERCC6 SNP types. However, when pts were broken down by chemotherapy regimen, TTP was 7 m for 31 CC pts treated with gem/cis and 5.4 m for 71 CC pts treated with doc/cis (P=0.04) ( Table ). MS was longer for CC pts treated with gem/cis (11 m) than for CC pts treated with doc/cis (8.9 m) (P=0.46). Differences were also observed in pts with PS 0 and in younger pts. Conclusions: ERCC6 C-6530>G SNP may confer differential sensitivity to gem or doc in combination with cis. We hypothesize that ERCC6 6350 CC is a surrogate of ERCC6 transcript, where lower ERCC6 expression levels may increase the activity of gem/cis in comparison to doc/cis.

No significant financial relationships to disclose.

[Table: see text]

Reactive perivascular T-cell infiltrate predicts survival in primary central nervous system B-cell lymphomas

Well-established histopathological prognostic factors are lacking in primary central nervous system (CNS) lymphomas (PCNSL). The present study investigated the presence and prognostic role of tumour necrosis (TN) and reactive perivascular T-cell infiltrate (RPVI), defined as a rim of small reactive T-lymphocytes occurring alone or located between the vascular wall and large neoplastic cells, in tumour samples from 100 immunocompetent patients with PCNSL. World Health Organization histotypes of the patients were: 96 diffuse large B-cell lymphomas, two Burkitt-like lymphomas, one anaplastic large T-cell lymphoma and one unclassified B-cell lymphoma. TN was observed in 24 (24%) cases and RPVI in 26 (36%) of 73 assessable cases. Patients with RPVI-positive lesions exhibited a significantly better overall survival (OS) than patients with RPVI-negative lymphoma, particularly among patients treated with high-dose methotrexate-based chemotherapy (3-year OS: 59 +/- 14% vs. 42 +/- 9%, P = 0.02). By contrast, the presence of TN did not demonstrate prognostic significance. Multivariate analysis confirmed an independent association between RPVI and survival. In conclusion, the presence of RPVI is independently associated with survival in PCNSL. This parameter can be easily and routinely assessed at diagnosis on histopathological specimens.

Factors influencing the prevalence of Salmonella spp. in swine farms: a meta-analysis approach

A systematic review and meta-analysis was conducted to identify study-level variables that could explain the variation in apparent Salmonella spp. prevalence estimates. Electronic and non-electronic literature searches from 1990 until 2005 were carried out to identify all studies related to the prevalence of subclinical Salmonella infection in swine. The searches were restricted to studies published in English, Spanish, and French. Clinical trials or any other study where an intervention was evaluated were excluded from this analysis. A template was designed to retrieve the most relevant variables and data abstraction was performed in duplicate. A total of 98 papers containing 82 animal-level and 156 farm-level studies were used in the analyses. The median farm-level and animal-level prevalences were 59% and 17%, respectively. Meta-regression analyses were carried out on both farm and animal-level data. Diagnostic procedure, sample size, and country where study was conducted were the three most important predictors in explaining the differences in Salmonella prevalences between studies. When compared to a farm with a apparent prevalence of 50% determined by the blood ELISA, prevalences based on culture of fecal samples were 39% lower and prevalences based on cecum and tissue cultures were 16% and 19% lower, respectively. Similar to farm-level models, animal-level models did not show any difference among serological tests and prevalence values based culture procedures were, on average, 9% lower than those from serological tests. Sample size was negatively associated with prevalence estimates. In conclusion, the methodology was useful for identifying and quantifying sources of variation in Salmonella apparent prevalence among studies and for establishing prevalence distributions that could be used as input parameters in risk assessment and decision models. The analysis provides some guidelines when interpreting and comparing apparent Salmonella prevalence results from studies using different study designs.

Characterization of a murine model of intranasal infection suitable for testing vaccines against C. abortus

Mouse models have been widely used to test candidate vaccines against Chlamydophila abortus infection in mice. Although the induction of a systemic infection by endogenous or intraperitoneal inoculation is a useful tool for understanding the immune mechanism involved in the protection conferred by the vaccination, a different approach is necessary to understand other factors of the infection, such as mucosal immunity or the colonization of target organs. To test whether C. abortus intranasal model of infection in mice is a useful tool for testing vaccines in a first group of experiments mice, were infected intranasally with C. abortus to characterize the model of infection. When this model was used to test vaccines, two inactivated experimental vaccines, one of them adjuvated with QS-21 and another with aluminium hydroxide, and a live attenuated vaccine (strain 1B) were used. Non-vaccinated control mice died within the first 8 days, after displaying substantial loss of weight. Histologically, the mice showed lobar fibrinopurulent bronchointerstitial pneumonia. Prior immunization with QS-21 adjuvated vaccine or 1B vaccine presented mortality and the recipients showed a greater number of T cells in the lesions, especially CD8(+) T cells, than the control mice and mice immunized with vaccine adjuvated with aluminium hydroxide. The results confirm that the C. abortus intranasal model of infection in mice is a useful tool for testing vaccines.

Test characteristics from latent-class models of the California Mastitis Test

We evaluated (using latent-class models) the ability of the California Mastitis Test (CMT) to identify cows with intramammary infections on the day of dry-off. The positive and negative predictive values of this test to identify cows requiring dry-cow antibiotics (i.e. infected) was also assessed. We used 752 Holstein-Friesian cows from 11 herds for this investigation. Milk samples were collected for bacteriology, and the CMT was performed cow-side, prior to milking on the day of dry-off. At the cow-level, the sensitivity and specificity of the CMT (using the four quarter results interpreted in parallel) for identifying all pathogens were estimated at 70 and 48%, respectively. If only major pathogens were considered the sensitivity of the CMT increased to 86%. The negative predictive value of the CMT was >95% for herds with major-pathogen intramammary-infection prevalence <15%, so that selective dry-cow therapy might be reasonable for such herds if cows were screened with the CMT.

Seroprevalence of and risk factors for HIV-1 infection among female commercial sex workers in South America

OBJECTIVE

Assessment of HIV prevalence and associated risk behaviours among female commercial sex workers (FCSW) across major cities in South America.

METHODS

Seroepidemiological, cross sectional studies of 13 600 FCSW were conducted in nine countries of South America during the years 1999-2002. Participants were recruited in brothels, massage parlours, hotels, and streets where anonymous questionnaires and blood samples were collected. HIV infection was determined by enzyme linked immunosorbent assay (ELISA) screening and western blot confirmatory tests.

RESULTS

The overall HIV seroprevalence was 1.2% (range 0.0%-4.5%). The highest HIV seroprevalences were reported in Argentina (4.5%) and Paraguay (2.6%); no HIV infected FCSW were detected in Venezuela and Chile. Consistent predictors of HIV seropositivity were: (1) a previous history of sexually transmitted infections (STI, AORs = 3.8-8.3), and (2) 10 years or more in commercial sex work (AORs = 2.2-24.8). In addition, multiple (> or =3) sexual contacts (AOR = 5.0), sex with foreigners (AOR = 6.9), use of illegal drugs (AOR = 3.2), and marijuana use (AOR = 8.2) were associated with HIV seropositivity in Southern Cone countries.

CONCLUSIONS

Consistently low HIV seroprevalences were detected among FCSW in South America, particularly in the Andean region. Predictors of HIV infection across the continent were STI and length of commercial sex work; however, use of illegal drugs, especially marijuana, and sexual contacts with foreigners were also found to be associated risk factors in the Southern Cone region. Interventions for the control of HIV and other STI need to be region and country specific; drug use appears to have an ever increasing role in the spread of HIV among heterosexually active populations.