Overexpression of the third H-NS paralogue H-NS2 compensates fitness loss in hns mutants of the enteroaggregative Escherichia coli strain 042

Members of the H-NS protein family play a role both in the chromosome architecture and in the regulation of gene expression in bacteria. The genomes of the enterobacteria encode an H-NS paralogue, the StpA protein. StpA displays specific regulatory properties and provides a molecular backup for H-NS. Some enterobacteria also encode third H-NS paralogues. This is the case of the enteroaggregative E. coli (EAEC) strain 042, which encodes the hns, stpA and hns2 genes. We provide in this paper novel information about the role of the H-NS2 protein in strain 042. A C > T transition in the hns2 promoter leading to increased H-NS2 expression is readily selected in hns mutants. Increased H-NS2 expression partially compensates for H-NS loss. H-NS2 levels are critical for the strain 042 fitness. Under some circumstances, high H-NS2 expression levels dictated by the mutant hns2 promoter can be deleterious. The selection of T > C revertants or of clones harboring insertional inactivations of the hns2 gene can then occur. Temperature also plays a relevant role in the H-NS2 regulatory activity. At 37 °C, H-NS2 targets a subset of the H-NS repressed genes contributing to their silencing. When temperature drops to 25 °C, the repressory ability of H-NS2 is significantly reduced. At low temperature, H-NS plays the main repressory role.

Effects of dietary inclusion of Opuntia ficus-indica on the glycemia and productive performance in lactating sows

Sows with increased blood glucose during late gestation may have decreased feed intake in lactation. Supplying dietary fibre to the sow reportedly modulates blood glucose and improves feed intake. The objective of this study was to evaluate the effects of dietary inclusion of cactus (Opuntia ficus-indica) on the regulation of blood glucose and productive performance in lactating sows. Data from 52 hybrid sows were analysed. The sows were divided into two groups, namely a control group (CG), that is, sows fed conventionally; and an experimental group (EG), that is, sows fed commercial feed plus cacti. Blood glucose in late gestation, and feed intake, milk production and milk quality, development of the piglet, energy balance, post-weaning body weight balance and the interval from weaning to oestrus were recorded. Preprandial blood glucose was 55.9 mg per dL in EG and 71.4 in CG. Sows on EG had greater daily feed intake and lower negative energy balance (5.4 kg/day and -2.8 MJ/day) than those on CG (4.5 kg/day and -9.4 MJ/day). Sows fed EG produced more milk (8.6 L/day) than those on CG (8.1 L/day). The quality of milk produced and the weaning weight of piglets were similar for the two groups. Body weight balance after weaning was greater for sows fed EG, 3.5% versus -1.5% in those fed CG. The weaning to oestrus interval was 0.6 days less for sows fed EG than those fed CG. Feeding cactus to lactating sows regulated blood glucose, which improved most of their productive indicators.Keywords: cactus, dietary fibre, energy balance, hypophagia, piglet

Evolution of Bacterial Global Modulators: Role of a Novel H-NS Paralogue in the Enteroaggregative Escherichia coli Strain 042

Bacterial genomes sometimes contain genes that code for homologues of global regulators, the function of which is unclear. In members of the family Enterobacteriaceae, cells express the global regulator H-NS and its paralogue StpA. In Escherichia coli, out of providing a molecular backup for H-NS, the role of StpA is poorly characterized. The enteroaggregative E. coli strain 042 carries, in addition to the hns and stpA genes, a third gene encoding an hns paralogue (hns2). We present in this paper information about its biological function. Transcriptomic analysis has shown that the H-NS2 protein targets a subset of the genes targeted by H-NS. Genes targeted by H-NS2 correspond mainly with horizontally transferred (HGT) genes and are also targeted by the Hha protein, a fine-tuner of H-NS activity. Compared with H-NS, H-NS2 expression levels are lower. In addition, H-NS2 expression exhibits specific features: it is sensitive to the growth temperature and to the nature of the culture medium. This novel H-NS paralogue is widespread within the Enterobacteriaceae. IMPORTANCE Global regulators such as H-NS play key relevant roles enabling bacterial cells to adapt to a changing environment. H-NS modulates both core and horizontally transferred (HGT) genes, but the mechanism by which H-NS can differentially regulate these genes remains to be elucidated. There are several instances of bacterial cells carrying genes that encode homologues of the global regulators. The question is what the roles of these proteins are. We noticed that the enteroaggregative E. coli strain 042 carries a new hitherto uncharacterized copy of the hns gene. We decided to investigate why this pathogenic E. coli strain requires an extra H-NS paralogue, termed H-NS2. In our work, we show that H-NS2 displays specific expression and regulatory properties. H-NS2 targets a subset of H-NS-specific genes and may help to differentially modulate core and HGT genes by the H-NS cellular pool.

Tetracycline alters gene expression in Salmonella strains that harbor the Tn10 transposon

In this report, we show that bacterial plasmids that harbor the Tn10 transposon (i.e., the IncHI1 plasmid R27) modify expression of different Salmonella regulons responding to the presence of tetracycline (Tc) in the medium. By using as a model the Tc-dependent upregulation of the ibpAB operon (which belongs to the heat shock regulon), we have identified Tn10-tetA (coding for a Tc efflux pump) and adjacent tetC sequences as required for ibpAB upregulation. Characterization of transcripts in the tetAC region showed that tetA transcription can continue into tetC sequences, generating a long 3'UTR sequence, which can protect transcripts from RNA processing, thus increasing the expression of TetA protein. In the presence of Tc, the DnaK and IbpA chaperones are overexpressed and translocated to the periplasm and to the membrane fraction respectively. DnaK targeting unfolded proteins is known to induce heat shock by avoiding RpoH proteolysis. We correlate expression levels of Tn10-encoded TetA protein with heat shock induction in Salmonella, likely because TetA activity compromises protein secretion.

Myopodin methylation is a prognostic biomarker and predicts antiangiogenic response in advanced kidney cancer

Myopodin is a cytoskeleton protein that shuttles to the nucleus depending on the cellular differentiation and stress. It has shown tumor suppressor functions. Myopodin methylation status was useful for staging bladder and colon tumors and predicting clinical outcome. To our knowledge, myopodin has not been tested in kidney cancer to date. The purpose of this study was to evaluate whether myopodin methylation status could be clinically useful in renal cancer (1) as a prognostic biomarker and 2) as a predictive factor of response to antiangiogenic therapy in patients with metastatic disease. Methylation-specific polymerase chain reactions (MS-PCR) were used to evaluate myopodin methylation in 88 kidney tumors. These belonged to patients with localized disease and no evidence of disease during follow-up (n = 25) (group 1), and 63 patients under antiangiogenic therapy (sunitinib, sorafenib, pazopanib, and temsirolimus), from which group 2 had non-metastatic disease at diagnosis (n = 32), and group 3 showed metastatic disease at diagnosis (n = 31). Univariate and multivariate Cox analyses were utilized to assess outcome and response to antiangiogenic agents taking progression, disease-specific survival, and overall survival as clinical endpoints. Myopodin was methylated in 50 out of the 88 kidney tumors (56.8 %). Among the 88 cases analyzed, 10 of them recurred (11.4 %), 51 progressed (57.9 %), and 40 died of disease (45.4 %). Myopodin methylation status correlated to MSKCC Risk score (p = 0.050) and the presence of distant metastasis (p = 0.039). Taking all patients, an unmethylated myopodin identified patients with shorter progression-free survival, disease-specific survival, and overall survival. Using also in univariate and multivariate models, an unmethylated myopodin predicted response to antiangiogenic therapy (groups 2 and 3) using progression-free survival, disease-specific, and overall survival as clinical endpoints. Myopodin was revealed hypermethylated in kidney cancer. Myopodin methylation status identified which patients showed a more aggressive clinical behavior and predicted antiangiogenic response. These observations support the clinical utility of an unmethylated myopodin as a prognostic and predictive biomarker in kidney cancer.

[Complete response to tyrosine kinase inhibitors in metastatic renal cancer. Report of four cases]

OBJECTIVSE

To describe the complete responses in our patients with metastatic renal cancer treated with tyrosine kinase inhibitors.

MATERIAL AND METHODS

Between June 2007 and December 2014 we treated in our department 43 patients with metastatic renal cancer with antiangiogenic drugs.

RESULTS

9.3% (4/43) of the patients treated with antiangiogenic drugs obtained complete response according to RECIST 1.1 criteria. In 3 of the 4 patients, complete response was obtained during the first-line treatment with sunitinib at doses of 50 mgr/day in a 4/2 scheme and the remaining patient obtained it with second line axitinib at doses of 10 mgr/day.

CONCLUSIONS

Tyrosine kinase inhibitors can induce complete responses in patients with metastatic renal cancer. Discontinuation of treatment with tyrosine kinase inhibitors after a complete response may be an option.

Label-free ITO-based immunosensor for the detection of very low concentrations of pathogenic bacteria

Here we describe the fabrication of a highly sensitive and label-free ITO-based impedimetric immunosensor for the detection of pathogenic bacteria Escherichia coli O157:H7. Anti-E. coli antibodies were immobilized onto ITO electrodes using a simple, robust and direct methodology. First, the covalent attachment of epoxysilane on the ITO surface was demonstrated by Atomic Force Microscopy and cyclic voltammetry. The immobilization of antibody on the epoxysilane layer was quantified by Optical Waveguide Lightmode Spectroscopy, obtaining a mass variation of 12 ng cm(− 2) (0.08 pmol cm(− 2)). Microcontact printing and fluorescence microscopy were used to demonstrate the specific binding of E. coli O157:H7 to the antibody-patterned surface. We achieved a ratio of 1:500 Salmonella typhimurium/E. coli O157:H7, thus confirming the selectivity of the antibodies and efficiency of the functionalization procedure. Finally, the detection capacity of the ITO-based immunosensor was evaluated by Electrochemical Impedance Spectroscopy. A very low limit of detection was obtained (1 CFU mL(− 1)) over a large linear working range (10–10(6) CFU mL(− 1)). The specificity of the impedimetric immunosensor was also examined. Less than 20% of non-specific bacteria (S. typhimurium and E. coli K12) was observed. Our results reveal the applicability of ITO for the development of highly sensitive and selective impedimetric immunosensors.

Nanoscale imaging of the growth and division of bacterial cells on planar substrates with the atomic force microscope

With the use of the atomic force microscope (AFM), the Nanomicrobiology field has advanced drastically. Due to the complexity of imaging living bacterial processes in their natural growing environments, improvements have come to a standstill. Here we show the in situ nanoscale imaging of the growth and division of single bacterial cells on planar substrates with the atomic force microscope. To achieve this, we minimized the lateral shear forces responsible for the detachment of weakly adsorbed bacteria on planar substrates with the use of the so called dynamic jumping mode with very soft cantilever probes. With this approach, gentle imaging conditions can be maintained for long periods of time, enabling the continuous imaging of the bacterial cell growth and division, even on planar substrates. Present results offer the possibility to observe living processes of untrapped bacteria weakly attached to planar substrates.

TrhR, TrhY and HtdA, a novel regulatory circuit that modulates conjugation of the IncHI plasmids

Bacterial conjugation promotes horizontal gene transfer and, consequently, the acquisition of new capabilities such as resistance to antimicrobial compounds and virulence related traits. Conjugative plasmids belonging to the incompatibility group HI are associated with multidrug resistance in Gram-negative pathogens. IncHI plasmid conjugation is thermodependent and all transfer-related genes are encoded in six operons (tra operons). Using R27, the prototype of IncHI1 plasmids, we reported that the plasmid-encoded factor HtdA represses four of the six tra operons. Moreover, our results indicated that other R27 factors were required for appropriate expression of the tra genes. In this report, using R27 libraries and random mutagenesis assays, two genes - trhR and trhY - have been identified as essential for the transcriptional expression of four tra operons and, accordingly, for the R27 conjugation. TrhR and TrhY are required simultaneously and their stimulatory activity is counteracted by HtdA. Functional and physical interactions between TrhR, TrhY and HtdA suggest that they form a three-element regulatory circuit that controls conjugation of IncHI plasmids. Expression studies suggest that H-NS represses conjugation at high temperature by repressing trhR expression. Remarkably, we show that this regulatory circuit is highly conserved among the IncHI plasmids.

Streptococcus sanguinis adhesion on titanium rough surfaces: effect of shot-blasting particles

Dental implant failure is commonly associated to dental plaque formation. This problem starts with bacterial colonization on implant surface upon implantation. Early colonizers (such as Streptococcus sanguinis) play a key role on that process, because they attach directly to the surface and facilitate adhesion of later colonizers. Surface treatments have been focused to improve osseointegration, where shot-blasting is one of the most used. However the effects on bacterial adhesion on that sort of surfaces have not been elucidated at all. A methodological procedure to test bacterial adherence to titanium shot-blasted surfaces (alumina and silicon carbide) by quantifying bacterial detached cells per area unit, was performed. In parallel, the surface properties of samples (i.e., roughness and surface energy), were analyzed in order to assess the relationship between surface treatment and bacterial adhesion. Rather than roughness, surface energy correlated to physicochemical properties of shot-blasted particles appears as critical factors for S. sanguinis adherence to titanium surfaces.

[Adverse cutaneous reactions to erlotinib]

INTRODUCTION

Erlotinib is an inhibitor of human epidermal growth factor approved for treating non-small cell lung cancer. The aim of this prospective observational study was to determine the prevalence of adverse cutaneous reactions caused by erlotinib and assess the management of such effects.

METHODS

Eleven patients with lung cancer and 1 with ovarian cancer received erlotinib at a dose of 150 mg/d. The prevalence, severity, and time course of the adverse cutaneous reactions were assessed.

RESULTS

The most frequent cutaneous reaction was acneiform eruption (10 cases). The patients were treated with topical erythromycin and clindamycin, or with doxycycline. Also reported were seborrheic dermatitis (5), paronychia (4), xerosis (3), mouth blisters (3), blepharitis (2), cheilitis (1), and fissures on the hands and feet (1). The first reactions to appear were seborrheic dermatitis (9.8 days until onset) and acneiform eruption (11.8 days), whereas the paronychia presented latest (65.3 days). One patient with acneiform eruption and another with paronychia suspended treatment until the lesions improved.

CONCLUSIONS

Erlotinib induces adverse effects in most patients treated. Acneiform eruption, seborrheic dermatitis, and paronychia are the most frequently reported reactions and can lead to temporary suspension of erlotinib administration.

Venous thromboembolic disease in cancer. Optimisation of the use of antithrombotic agents

Venous thromoboembolism is one of the most common complications in cancer patients and may have serious consequences. At present, most clinical oncologists report using thromboprophylaxis in less than 5% of patients. One of the possible reasons for this limited use is the lack of oncology specific guidelines. In effect, while there are excellent guidelines for optimising the use of antithrombotic agents to prevent and treat thromboembolism, they must be adapted to the concrete context of cancer patients. The present review explores how different situations affect cancer patients and their risk of developing venous thromboembolism (VTE), and evaluates the situations in which antithrombotic agents should be administered to treat and prevent VTE.

Dielectrophoresis as a tool to characterize and differentiate isogenic mutants of Escherichia coli

In this study we report on an experimental method based on dielectrophoretic analysis to identify changes in four Escherichia coli isogenic strains that differed exclusively in one mutant allele. The dielectrophoretic properties of wild-type cells were compared to those of hns, hha, and hha hns mutant derivatives. The hns and hha genes code respectively for the global regulators Hha and H-NS. The Hha and H-NS proteins modulate gene expression in Escherichia coli and other Gram negative bacteria. Mutations in either hha or hns genes result in a pleiotropic phenotype. A two-shell prolate ellipsoidal model has been used to fit the experimental data, obtained from dielectrophoresis measurements, and to study the differences in the dielectric properties of the bacterial strains. The experimental results show that the mutant genotype can be predicted from the dielectrophoretic analysis of the corresponding cultures, opening the way to the development of microdevices for specific identification. Therefore, this study shows that dielectrophoresis can be a valuable tool to study bacterial populations which, although apparently homogeneous, may present phenotypic variability.

Early detection of nonresponse to interferon plus ribavirin combination treatment of chronic hepatitis C

We have investigated the value of early hepatitis C virus (HCV) RNA decline (DeltaHCV RNA) to predict response to combination therapy in 66 chronic hepatitis C patients treated with IFN-alpha2b (3 MU thrice weekly) and ribavirin (800 mg daily) for 12 months [25 sustained responders (SR) and 41 nonresponders or relapsers (NR)]. Serum HCV RNA was retrospectively measured in samples obtained at baseline and 4, 8 and 12 weeks after treatment onset, using a commercially available quantitative RT-PCR assay. At 4 weeks, serum HCV RNA had decreased a mean of 2.6 +/- 0.8 logs among SR as compared with only 0.5 +/- 0.8 logs in NR (P < 0.001), and was already undetectable (< 600 IU/mL) in 12 (48%) of the SR but in none of the NR. At 8 weeks, HCV RNA was undetectable in 21 SR and in 2 NR and mean DeltaHCV RNA were 4.2 +/- 1.3 and 0.8 +/- 1.0 logs, respectively (P < 0.001). At week 12 all SR had undetectable HCV RNA as compared with only five NR (P < 0.001). Stepwise logistic regression analysis identified DeltaHCV RNA at 12 weeks as the strongest predictor of sustained response. Receiver operating characteristic (ROC) curves of DeltaHCV RNA for sustained response prediction identified sensitivity peaks with 100% negative predictive value corresponding to DeltaHCV RNA > 1 log at 4 weeks, > 2 logs at 8 weeks and > 3 logs at 12 weeks. Our results show that early changes in the HCV RNA level may reliably identify patients having no chance of a sustained virological response during the first 3 months of combination therapy, thus providing an excellent tool for optimizing antiviral treatment of chronic hepatitis C.

Evidence for direct protein-protein interaction between members of the enterobacterial Hha/YmoA and H-NS families of proteins

Escherichia coli nucleoid-associated H-NS protein interacts with the Hha protein, a member of a new family of global modulators that also includes the YmoA protein from Yersinia enterocolitica. This interaction has been found to be involved in the regulation of the expression of the toxin alpha-hemolysin. In this study, we further characterize the interaction between H-NS and Hha. We show that the presence of DNA in preparations of copurified His-Hha and H-NS is not directly implicated in the interaction between the proteins. The precise molecular mass of the H-NS protein retained by Hha, obtained by mass spectrometry analysis, does not show any posttranslational modification other than removal of the N-terminal Met residue. We constructed an H-NS-His recombinant protein and found that, as expected, it interacts with Hha. We used a Ni(2+)-nitrilotriacetic acid agarose method for affinity chromatography copurification of proteins to identify the H-NS protein of Y. enterocolitica. We constructed a six-His-YmoA recombinant protein derived from YmoA, the homologue of Hha in Y. enterocolitica, and found that it interacts with Y. enterocolitica H-NS. We also cloned and sequenced the hns gene of this microorganism. In the course of these experiments we found that His-YmoA can also retain H-NS from E. coli. We also found that the hns gene of Y. enterocolitica can complement an hns mutation of E. coli. Finally, we describe for the first time systematic characterization of missense mutant alleles of hha and truncated Hha' proteins, and we report a striking and previously unnoticed similarity of the Hha family of proteins to the oligomerization domain of the H-NS proteins.

Interferon and ribavirin combination therapy for chronic hepatitis C in human immunodeficiency virus-infected patients with congenital coagulation disorders

We have conducted an open, prospective trial to assess the safety and efficacy of interferon alfa-2b and ribavirin in combination for the treatment of chronic hepatitis C in human immunodeficiency virus (HIV)-infected hemophiliacs. Twenty hemophiliacs coinfected with HIV and hepatitis C virus (HCV), 18 of them under highly active antiretroviral therapy (HAART), with a mean CD4(+) cell count of 490 +/- 176 cells/mm(3) and undetectable (n = 9) or low-level HIV RNA (<10,000 copies/mL; n = 11), were treated with interferon-alfa2b (3 MU thrice weekly) and ribavirin (800 mg/d) for 6 or 12 months according to virologic response. Patients were monitored for tolerance and response at 4, 8, 12, 24, 36, and 48 weeks during treatment and every other month thereafter. All 20 patients enrolled completed at least 6 months of treatment with no major side effect requiring treatment withdrawal, dose reduction, or modification of HAART. Overall, 8 patients (40%) achieved a sustained virologic response at the end of the 6-month post-treatment follow-up. Sustained responders had lower baseline HCV-RNA levels (5.7 +/- 0.8 vs. 6.3 +/- 0.4 log10 IU/mL, P =.041) but were otherwise similar to nonresponders. All sustained responders had a decrease in HCV-RNA level of at least 1 log per month during the first 2 months and undetectable levels at 6 months. In conclusion, our results provide evidence that combination therapy with interferon and ribavirin is safe in HIV-infected hemophiliacs with stable CD4 cell count and undetectable or low-level HIV replication, and leads to eradication of HCV in 40% of these patients.

Major histocompatibility complex and tumor necrosis factor-alpha polymorphisms in pigeon breeder's disease

Pigeon breeders disease (PBD) is caused by the exposure of a susceptible host to avian antigens. However, genetic factors determining individual predisposition are unknown. In this work, polymorphisms of the major histocompatibility complex (MHC) class II alleles and tumor necrosis factor alpha (TNF-alpha) promoter were evaluated in 44 patients with PBD, 99 healthy unrelated controls (HC), and 50 exposed but asymptomatic subjects (EAS). MHC typing was performed by PCR-specific sequence oligonucleotide analysis, and TNF-alpha polymorphism at -238 and -308 positions by amplification refractory mutation system-PCR. PBD patients showed a significant increase of the alleles HLA-DRB1*1305 (p < 0.001, OR = 15.4, 95% CI = 3.18-102.6 [HC], and OR = 17.05, 95% CI = 2.25-357.8 [EAS]) and HLA-DQB1*0501 (p < 0.05, OR = 2.93, 95% CI = 1.21-7.15 [HC], and OR = 2.96, 95% CI = 1.0-9.14 [EAS]). A decrease of HLA-DRB1*0802 was also noticed in patients when compared with both control groups (p < 0.05). Haplotype analysis revealed an increase of DRB1*1305-DQB1*0301 and a decrease of DRB1*0802-DQB1*0402. PBD patients had an increased frequency of TNF-2(-)(308) compared with both control groups (p < 0.05). Patients exhibiting the TNF-2(-)(308) allele were younger (33.9 +/- 14.6 versus 44.2 +/- 10.4 yr; p < 0.05), and displayed more lymphocytes in their bronchoalveolar lavages (88.0 +/- 12.1 versus 68.9 +/- 17.2; p < 0.05). These results suggest that genetic factors located within the MHC region contribute to the development of PBD.

Expression of the hemolysin operon in Escherichia coli is modulated by a nucleoid-protein complex that includes the proteins Hha and H-NS

The Escherichia coli protein Hha is a temperature- and osmolarity-dependent modulator of the expression of the hemolysin operon. The Hha protein was purified and its DNA-binding properties analyzed. Hha binds in a non-specific manner throughout the upstream regulatory region of the hemolysin operon in the recombinant hemolytic plasmid pANN202-312. A search for interacting proteins revealed that Hha interacts with H-NS. DNA-binding studies showed that, in vitro, Hha and H-NS together form a complex with DNA that differs from those formed with either protein alone. These data, together with the effects of hha and hns mutations on the expression of the hemolysin genes, suggest that in vivo H-NS and Hha form a nucleoid-protein complex that accounts for the thermo-osmotic regulation of the hemolysin operon in E. coli.

Alterations in protein expression caused by the hha mutation in Escherichia coli: influence of growth medium osmolarity

The Hha protein belongs to a new family of regulators involved in the environmental regulation of virulence factors. The aim of this work was to study the effect of the hha mutation on the overall protein pattern of Escherichia coli cells by two-dimensional polyacrylamide gel electrophoresis. The growth medium osmolarity clearly influenced the effect of the hha mutation. The number of proteins whose expression was altered in hha cells, compared with wild-type cells, was three times larger at a high osmolarity than at a low osmolarity. Among the proteins whose expression was modified by the hha allele, both OmpA and protein IIAGlc of the phosphotransferase system could be identified. As this latter enzyme participates in the regulation of the synthesis of cyclic AMP and hence influences the catabolite repression system, we tested whether the expression of the lacZ gene was also modified in hha mutants. This was the case, suggesting that at least some of the pleiotropic effects of the hha mutation could be caused by its effect on the catabolite repression system.

The putative Orf4 of broad-host-range conjugative plasmid R446 could Be related to the H-NS family of bacterial nucleoid-associated proteins

The iml determinant of IncM plasmid R446 was described initially as a short fragment of DNA causing (when cloned in multicopy plasmids) insensitivity to pilus-dependent bacteriophage lysis in bacteria harboring coresident IncM plasmids. We have performed a computational analysis of the iml determinant of IncM plasmid R446 and found that a potential polypeptide (Orf4) shows similarity to the H-NS family of nucleoid-associated modulators of gene expression. The predicted protein has a molecular weight of 16.3 kDa and an isoelectric point of 5.50. Orf4 is adjacent and upstream of Orf5, a potential polypeptide related to the Hha/YmoA/RmoA family of proteins which modulate bacterial virulence expression (Hha and YmoA) and R100 transfer (RmoA) in response to environmental conditions.

Sequence, identification and effect on conjugation of the rmoA gene of plasmid R100-1

The rmoA gene was recently identified from two partially overlapping sequences corresponding to a region close to the end of the tra operon of plasmid R100. Its putative amino acid sequence showed strong homology to the Hha protein of Escherichia coli and YmoA protein of Yersinia enterocolitica, which are modulators of gene expression in response to environmental stimuli. We have cloned the rmoA gene from plasmid R100-1 in pUC19 and obtained the complete nucleotide sequence, which was previously published only partially and may have contained some mistakes. The rmoA gene product has been identified in radiolabelled minicells as a protein of the predicted molecular mass. The wild-type rmoA gene of plasmid R100-1 has been mutated by gene replacement and its effect on the efficiency of conjugation has been analysed. When grown in LB medium, cells harbouring R100-1 plasmid with a disrupted copy of rmoA showed a five-fold increase in conjugation frequency compared to cells harbouring R100-1 plasmid with the wild-type rmoA gene, grown in the same conditions. When cells were grown in NaCl-free LB medium they showed a 50-fold increase in conjugation frequency.

[Rectal injury during radical surgery of bladder and/or prostate]

Contribution of 42 patients, aged 57 to 69 (mean age 58) with infiltrant vesical neoplasia who underwent radical cystoprostatectomy according to the technique described by P.C. Walsh (38/42) or radical cystectomy with hysterectomy (4/42). Neoplasia stages were as follows: 7 T2G-III; 13 T3aGII: 15 T3aG-III and 7 T3bG-III. Ten (10) patients, aged between 48 and 70 (mean age 57), with prostate neoplasia who were performed radical prostatectomy using the technique described by the above author, were also ascribed to the last group. Prostate neoplasias were at the following stages: 4 T2c; 5 T3a and 1T3b. T3 stages had been given hormonal therapy prior to the procedure. No patient received radiotherapy. Rectal injury occurred in 2 of the 52 (2/52) patients described. One was a female patient who was being performed cystectomy and hysterectomy plus double adnexectomy. Urinary by-pass in this case was C.F.C. detubulized ureterosigmoidostomy. The second case was a male patient undergoing radical prostatectomy. In both cases pre- and post-operative discharge colostomy was performed. Suture of rectal injury was also done in the patient where colostomy was performed during the procedure. The authors emphasise that no rectal injury that may take place during radical prostatectomy or cystoprostatectomy should be disregarded. They raise and answer questions of great practical interest such as: Is simple suture of the rectum enough? Should the omentum be used in rectal repair? Is it indispensable to perform discharge colostomy? and, is prognosis more serious when the gut is not prepared?

Osmolarity modulates the expression of the Hha protein from Escherichia coli

The effect of the osmolarity of the culture medium on the expression of the hha gene of Escherichia coli was investigated. When cells were grown in LB medium, expression reached a maximum in the exponential phase of growth and decreased in the stationary phase. Increasing the osmolarity of the LB medium had no significant effect on the expression of the hha gene, but depletion of NaCl led to a significant decrease in expression. Expression of the hha gene is thus sensitive to the osmolarity of the growth medium. High levels of expression of the hha gene when cells are grown at medium to high osmolarity are consistent with the finding that the Hha protein appears to play its main modulatory role when cells grow under these conditions.

Detection of pap, sfa and afa adhesin-encoding operons in uropathogenic Escherichia coli strains: relationship with expression of adhesins and production of toxins

A total of 243 Escherichia coli strains isolated from patients with urinary tract infections (UTI) were investigated for the presence of pap, sfa and afa adhesin-encoding operons by using the polymerase chain reaction. It was found that 54%, 53% and 2% of the strains exhibited the pap, sfa and afa genotypes, respectively. Pap+ and/or sfa+ strains were more frequent in cases of acute pyelonephritis (94%) than in cases of cystitis (67%) (P < 0.001) and asymptomatic bacteriuria (57%) (P < 0.001). The pap and/or sfa operons were found in 90% of strains expressing mannose-resistant haemagglutination (MRHA) versus 37% of MRHA-negative strains (P < 0.001). The presence of pap and sfa operons was especially significant in strains belonging to MRHA types III (100%) (without P adhesins) and IVa (97%) (expressing the specific Gal-Gal binding typical of P adhesins). Both pap and sfa operons were closely associated with toxigenic E. coli producing alpha-haemolysin (Hly+) and/or the cytotoxic necrotizing factor type 1. There was an apparent correlation between the pap and sfa operons and the O serogroups of the strains. Thus, 93% of strains belonging to O1, O2, O4, O6, O7, O14, O15, O18, O22, O75 and O83 possessed pap and/or sfa operons, versus only 32% of strains belonging to other serogroups (P < 0.001). The results obtained in this study confirm the usefulness of our MRHA typing system for presumptive identification of pathogenic E. coli exhibiting different virulence factors. Thus, 85% of strains that possessed both pap and sfa adhesin-encoding operons showed MRHA types III or IVa previously associated with virulence of E. coli strains that cause UTI and bacteraemia.

Humoral immune response in Yersinia enterocolitica O:5 induced arthritis in hamsters

Yersinia enterocolitica can cause extraintestinal sequelae such as reactive arthritis. The immunopathogenic mechanisms of this disease have not been completely clarified. Autoimmunity and persistent immune responses against bacterial antigens have been related to Yersinia-induced arthritis. The arthritogenic capacity of Y. enterocolitica O:5 and the kinetics of the development of autoantibodies and Yersinia antigen-specific antibodies were studied in hamsters. The results indicated that Y. enterocolitica O:5 was arthritogenic in the animal model studied. The animals developed septic arthritis on day 2 post-infection (p.i.) and reactive arthritis on day 65 p.i. An important IgG response to types I and II collagen and the persistence of antibodies against lipopolysaccharide and bacterial cellular extract were observed. By immunoblotting, it was obtained that IgG reacted against a large number of bacterial antigens, the strongest being the responses against 88, 76, 63 and 36-33 kDa peptides. From the results obtained, it can be concluded that serovar O:5 was experimentally arthritogenic, and that both autoimmune mechanisms and Yersinia-specific antibodies participated in the development of Yersinia-induced reactive arthritis in the animal model studied.

Construction of a double hha hns mutant of Escherichia coli: effect on DNA supercoiling and alpha-haemolysin production

A double hha hns Escherichia coli mutant was constructed. The effect of the single hns mutation and of the double hha hns mutation on the expression of the alpha-haemolysin determinant of plasmid pANN202-312 was assessed. Whereas the hns mutant moderately increased expression of the toxin, the double hha hns mutant strongly enhanced transcription of the hly operon and hence expression of the toxin. This suggests that both Hha and H-NS proteins participate in the modulation of the expression of the toxin. The enhancement of haemolysin expression in the double mutant could not be correlated to a global alteration of DNA topology: DNA preparations of a reporter plasmid isolated from this mutant gave a topoisomer distribution similar to that of the parental strain.

Distribution and characterization of faecal verotoxin-producing Escherichia coli (VTEC) isolated from healthy cattle

Faecal swabs obtained from a random sample of 268 cows and 90 calves on 19 Lugo farms were examined for verotoxin-producing Escherichia coli (VTEC). We found VTEC on 95% of the farms. The prevalence rates of VTEC infection in asymptomatic cows and calves were estimated to be 35 and 37%, respectively. The proportion of animals infected on each farm ranged from 0 to 100%. VTEC strains isolated from healthy cattle belonged to 27 O serogroups; however, 57% (85 of 149) were of one of 8 serogroups (O2, O8, O22, O77, O82, O105, O113 and O171). Nearly 60% of the bovine VTEC strains belonged to serogroups that cause haemorrhagic colitis and haemolytic uraemic syndrome in humans. The VTEC were all non-O157:H7; 91% were eae-negative and 86% produced VT2 or VT1 and VT2. These characteristics are different from those of VTEC isolated from calves with diarrhoea.

[Reconstructive surgery of rheumatic mitral valvulopathy in patients under 18 years of age]

OBJECTIVE

To present our experience in 58 children (37 female, 21 male) aged 4 to 18 years (mean +/- SD = 14.9 +/- 2.7) with rheumatic mitral valve disease who underwent surgical reconstruction.

METHODS

They were divided in four groups according to the abnormalities of the mitral apparatus: Group I had mitral regurgitation due to lesions located in the valvar structures with normal valvar movement (n = 1, 2%), group II mitral regurgitation with lesions located mainly in subvalvular structures with valve prolapse (n = 11, 19%), group III with mitral regurgitation due to lesion located both in valvular and subvalvular structures and restricted valvar motion (n = 38, 65%), and group IV included patients with stenosis (n = 8, 14%).

RESULTS

Surgical mortality was 5% (3/58) and three patients (5%) were reoperated immediately. The 52 remaining patients were followed from 6 to 108 months (mean 45.8 +/- 30.1 months, 199 patient-years). Six cases were reoperated in the follow-up (3.0% per patient-year). The functional class using the criteria of the New York Heart Association was evaluated before and after the procedure: class I raised from two to 42 patients whereas it decreased in the others (class II from 13 to 7, class III from 38 to 3, class IV from 5 to none; p < 0.001). The cardiothoracic index decreased from 0.61 +/- 0.064 before surgery to 0.55 +/- 0.069 after surgery (p < 0.001). Thirty patients (57%) were evaluated with echo-Doppler in the follow-up period. There were no deaths in the follow-up period.

CONCLUSIONS

Our data shows that reconstructive surgery of the mitral valve with rheumatic involvement offers good immediate and late results, with a low reoperation rate, avoiding the use of prosthetic valves as a first option.