Longitudinal increase in the detection rate of Mycobacterium chimaera in heater-cooler device-derived water samples

BACKGROUND

Colonization with Mycobacterium chimaera and other non-tuberculous mycobacteria (NTM) has been reported for heater-cooler devices (HCDs) produced by several manufacturers. Up until now, exclusively LivaNova (London, UK) HCDs have been associated with M. chimaera infections after cardiac surgery. The vast majority of studies on HCD colonization were cross-sectional.

AIM

We were interested in longitudinal dynamics of mycobacterial growth in HCD water samples and analysed data of a prospective mycobacterial surveillance of five LivaNova 3T HCDs.

METHODS

Five LivaNova HCDs were subjected to prospective mycobacterial surveillance. For each HCD and the total of HCDs, results of mycobacterial detection were analyzed. Logistic regression was applied to model the association between growth of any NTM or M. chimaera and duration of HCD use.

RESULTS

Non-tuberculous mycobacteria were isolated in 319 (48.0%, 21 water samples grew more than one mycobacterial species) of a total of 665 water samples. The most frequently detected species were M. chimaera (N = 247/319, 77.4%), Mycobacterium gordonae (46/319, 14.4%) and Mycobacterium paragordonae (34/319, 10.7%). Detection rates increased prospectively for any NTM (odds ratio (OR) per year in use: 1.60, 95% confidence interval (CI) 1.17-2.24, P<0.001) and for M. chimaera (OR per year in use: 1.67, 95% CI 1.11-2.57, P<0.01).

CONCLUSION

Longer duration of HCD use was associated with higher detection rates for any NTM and M. chimaera, respectively.

Diversity of nontuberculous mycobacteria in Heater-Cooler Devices - results from prospective surveillance

OBJECTIVE

The international outbreak of cardiac surgery-associated Mycobacterium chimaera infections was traced back to infectious aerosols originating from contaminated water reservoirs of heater-cooler devices (HCD). In general, nontuberculous mycobacteria (NTM) frequently colonize water systems and can contaminate medical devices. Data on detection of NTM other than M. chimaera in samples gathered from HCDs are scarce. The present study summarizes prospective mycobacterial surveillance of five HCDs over more than four years.

METHODS

A cohort of five, in 2014 factory-new acquired, LivaNova 3T (London, UK) HCDs were prospectively followed. Until mid-April 2014 HCDs were maintained according to the manufacturer's recommendations, subsequently according to an intensified in-house protocol including exhaust air evacuation. Mycobacterial surveillance cultures consisted of monthly water samples gathered from patient and cardioplegia circuits, as well as airflow samples.

RESULTS

Out of 441 water samples, 170 (38.6%) revealed NTM growth. The most frequently detected NTM were Mycobacterium chimaera (n=120 (67.4%)), Mycobacterium gordonae (n=35 (19.7 %)), and Mycobacterium paragordonae (n=17 (9.6%)). Growth of NTM, M. chimaera and M. paragordonae was significantly more common in water samples derived from the patient than the cardioplegia circuit of the HCD. Three (2.0%) out of 150 air samples grew NTM.

CONCLUSION

Growth of NTM in HCD water samples was frequent. Diverse NTM species were detected, with M. chimaera being most common. The majority of air samples remained negative. The relevance of NTM other than M. chimaera contaminating HCDs is poorly defined, but a recent report on a HCD-associated outbreak with Mycobacterium abscessus confirms a potential threat.

International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

Chloroquine enhances the antimycobacterial activity of isoniazid and pyrazinamide by reversing inflammation-induced macrophage efflux

Mycobacterium tuberculosis (MTB) is notorious for persisting within host macrophages. Efflux pumps decrease intracellular drug levels, thus fostering persistence of MTB during therapy. Isoniazid (INH) and pyrazinamide (PZA) are substrates of the efflux pump breast cancer resistance protein-1 (BCRP-1), which is inhibited by chloroquine (CQ). In this study, BCRP-1 was found to be expressed on macrophages of human origin and on foamy giant cells at the site of MTB infection. In the current in vitro study, interferon-gamma (IFNγ) increased the expression of BCRP-1 in macrophages derived from the human monocytic leukaemia cell line THP-1. Using a BCRP-1-specific fluorescent dye and radioactively labelled INH, it was demonstrated that efflux from macrophages increased upon activation with IFNγ. CQ was able to inhibit active efflux and augmented the intracellular concentrations both of INH and the dye. In agreement, CQ and specific inhibition of BCRP-1 increased the antimycobacterial activity of INH against intracellular MTB. Although PZA behaved differently, CQ had comparable advantageous effects on the intracellular pharmacokinetics and activity of PZA. The adjunctive effects of CQ on intracellular killing of MTB were measurable at concentrations achievable in humans at approved therapeutic doses. Therefore, CQ, a widely used and worldwide available drug, may potentiate the efficacy of standard MTB therapy against bacteria in the intracellular compartment.

Randomised clinical trial: sustained response to PPI treatment of symptoms resembling functional dyspepsia and irritable bowel syndrome in patients suffering from an overlap with erosive gastro-oesophageal reflux disease

BACKGROUND

Gastro-oesophageal reflux disease (GERD), functional dyspepsia (FD) and irritable bowel syndrome (IBS) are highly prevalent gastrointestinal conditions with accumulating evidence of overlap in patients. Despite availability of a vast body of research related to individual disorders, major pharmacological breakthrough in treatment of the overlap condition is still lacking.

AIM

To assess sustainability of GERD healing and whether known beneficial effects of proton pump inhibitor treatment on GERD also extend to symptoms suggestive of FD and IBS.

METHODS

A total of 626 patients with reflux oesophagitis were treated with pantoprazole for up to 16 weeks depending on healing of GERD, followed by an observational phase of up to 6 months without treatment. Rates of patients suffering from GERD, FD or IBS were assessed at baseline, and at last visits of treatment and observational phase.

RESULTS

Rates of patients with reflux oesophagitis and concomitantly with reflux symptoms, FD or IBS were each significantly lower after pantoprazole treatment (P < 0.0001). While rates of patients with reflux signs or symptoms increased again during observational phase, rates of FD and IBS were maintained at the low level after cessation of medication (P < 0.0001).

CONCLUSIONS

Pantoprazole is efficacious in the treatment of patients suffering from signs and symptoms suggesting an overlap of GERD, FD and/or IBS, providing a sustained response post-treatment in FD and IBS symptom categories. Mechanisms underlying the beneficial effects of improvement in reflux oesophagitis on symptoms suggestive of FD or IBS still need to be determined.

Improvement of non-steroidal anti-inflammatory drug-induced gastrointestinal symptoms during proton pump inhibitor treatment: are G-protein β3 subunit genotype, Helicobacter pylori status, and environmental factors response modifiers?

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) are associated with significant upper and lower gastrointestinal (GI) morbidity.

AIM

To determine the efficacy and safety of pantoprazole versus placebo in controlling GI symptoms during treatment with NSAIDs and to evaluate the influence of potential response modifiers.

METHODS

800 patients with GI complaints during NSAID treatment were randomized to pantoprazole 20 mg once daily or placebo for 4 weeks in this double-blind, multicenter trial. Assessments included the difference in cumulated overall symptom load of any GI complaint during treatment (primary endpoint), proportion of days without GI symptoms, and influence of risk factors such as gender, age, alcohol consumption, smoking, Helicobacter pylori status, and GNB3 genotype SNP rs5443 (825C>T) on symptom load.

RESULTS

At 4 weeks, cumulated overall symptom load was significantly lower in pantoprazole than placebo recipients [p < 0.0001; intent-to-treat (ITT)]; the effect was statistically significant after 7 days' treatment. Pantoprazole versus placebo recipients had 54 versus 29% of days without GI symptoms (p < 0.0001; ITT). Neither common risk factors nor GNB3 genotype were significantly associated with therapeutic response, while GNB3 825TT versus CT was associated with a significantly higher baseline symptom load (p < 0.05).

CONCLUSION

In the population studied, treatment with the proton pump inhibitor pantoprazole significantly improves GI symptoms during NSAID therapy, irrespective of the risk factors investigated or GNB3 genotype.

Surgical options in the treatment of stress urinary incontinence in women

The aim of this review is to provide an update on the surgical options for treatment of stress incontinence in women. The efficiency of different procedures and the safety associated with each procedure are evaluated, mainly by reviewing the randomised controlled trials. The open retropubic colposuspension and the sling procedures are the most efficacious for treatment stress urinary incontinence especially in the long term. The laparoscopic colposuspension may be as good as the open colposuspension, but the long-term performance remains uncertain. The newer minimal access vaginal sling procedures appear to offer benefits of minimal access surgery with success rate similar to the colposuspension and the traditional slings and minor morbidity in the short and median-term. However long term data is still awaited. The transobturator technique does not seem to provide advantages compared to the classical TVT procedure. Urethral injection therapy does not seem to have the same efficacy as conventional surgery and long term data is still scanty. However, because of low operative morbidity it represents a favourable alternative to standard surgery in patients who prefer less invasive treatment, the frail elderly and other selected women where conventional surgery is problematic.

Pharmacodynamic effects of 3-day intravenous treatment with pantoprazole or ranitidine after 10 days of oral ranitidine

Tachyphylaxis (drug tolerance) is an undesirable condition in drug therapy with histamine-2-receptor antagonists (H2RAs). The concept of overcoming tachyphylaxsis via intravenous (i.v.) administration of proton-pump inhibitors (PPIs) or H2RAs is of significant interest to physicians. In the present study, 32 healthy Helicobacter pylori negative male volunteers were evaluated for the ability of i.v. pantoprazole or i.v. ranitidine to overcome oral ranitidine tachyphylaxis. After 10 days of oral treatment with enteric-coated 300-mg ranitidine tablets once daily in the evening, two groups of 16 volunteers each were randomized to receive either i.v. pantoprazole or i.v. ranitidine for up to 72 h. The primary variable was defined as the increase in 24-h gastric pH median after 1 day of i.v. treatment; the secondary variable was median percentage of time that 24-h gastric pH was <4, as calculated by Hodges-Lehman shift estimators. After 10 days of oral ranitidine treatment, tachyphylaxis was present in all volunteers. Within 1 day of continuous i.v. pantoprazole or i.v. ranitidine administration, 24-h median gastric pH increased from pH 1.45 to pH 3.50 (241%) and from pH 1.50 to pH 2.35 (157%), respectively. I.v. pantoprazole was found to be significantly more effective (p<0.05) than i.v. ranitidine in increasing the 24-h gastric pH after oral ranitidine tachyphylaxis.

Lipoprotein processing is required for virulence of Mycobacterium tuberculosis

Lipoproteins are a subgroup of secreted bacterial proteins characterized by a lipidated N-terminus, processing of which is mediated by the consecutive activity of prolipoprotein diacylglyceryl transferase (Lgt) and lipoprotein signal peptidase (LspA). The study of LspA function has been limited mainly to non-pathogenic microorganisms. To study a potential role for LspA in the pathogenesis of bacterial infections, we have disrupted lspA by allelic replacement in Mycobacterium tuberculosis, one of the world's most devastating pathogens. Despite the presence of an impermeable lipid outer layer, it was found that LspA was dispensable for growth under in vitro culture conditions. In contrast, the mutant was markedly attenuated in virulence models of tuberculosis. Our findings establish lipoprotein metabolism as a major virulence determinant of tuberculosis and define a role for lipoprotein processing in bacterial pathogenesis. In addition, these results hint at a promising new target for therapeutic intervention, as a highly specific inhibitor of bacterial lipoprotein signal peptidases is available.

Impact of amphotericin B on the cytochrome P450 system in HIV-infected patients

OBJECTIVE

To investigate whether cytochrome P450-dependent enzymes are influenced by amphotericin B (Am-B) during the treatment of Candida oesophagitis in HIV-infected patients.

METHODS

Twelve HIV-infected, antiretroviral-naive patients (CDC/WHO stage C3) with Candida oesophagitits were enrolled into a prospective clinical trial. The patients were treated with Am-B (0.4 mg/kg body weight) for two weeks. At baseline and after Am-B therapy the clearance of antipyrine and its metabolites were investigated by high-performance liquid chromatography. In addition, the urinary excretion of 6-beta-hydroxycortisol and 17-hydroxycorticosteroids was assessed by means of a radioimmunoassay.

RESULTS

The following significant changes were observed after Am-B treatment (P < 0.01): increase of antipyrine half-life (12.4 h vs 16.8 h) and the area under the plasma concentration-time curve (27.9 mg min/ml vs 38.1 mg min/ml); decrease of the total body clearance (61.2 ml/min vs 43.7 ml/min); decrease of the renal clearance of antipyrine metabolites - norantipyrine (7.45 ml/min vs 5.31 ml/min), 4-hydroxyantipyrine (15.4 ml/min vs 10.3 ml/min), hydroxymethylantipyrine (4.31 ml/min vs 3.65 ml/min); decrease of urinary 6-beta-hydroxycortisol excretion (453 microg/24h vs 298 microg/24h) and the ratio of 6-beta-hydroycortisol to 17-hydroxycorticosteroids (8.8% vs 6.4%).

CONCLUSIONS

Our data indicate that Am-B therapy has an inhibitory effect on cytochrome P450-dependent enzymes in HIV-infected patients. These results are of particular significance for HIV-infected patients who are concomitantly treated with drugs that are predominantly metabolised in the liver. A careful drug monitoring system seems advisable, especially for proteinase inhibitor experienced HIV-1-infected subjects.

Beckenvenenthrombose im 16. Lebensjahr bei angeborener Vena-cava-inferior-Atresie und Ecstasy-Abusus

Kasuistik: Eine kaukasische Patientin, die sich wegen kosmetisch störender Varizen an der Bauchdecke und den Leisten vorstellte, erlitt mit 16 Jahren während einer exzessiven Tanzveranstaltung unter dem Einfluss von Ecstasy (3,4-Methylendioxymethamphetamin) aus kompletter Gesundheit bei damals asymptomatischer Vena-cava-inferior-Atresie eine akute Beckenvenenthrombose. Diagnostik: Bidirektionale Dopplersonographie, farbkodierte Duplexsonographie, Kernspintomographie mit Magnevist-Kontrastmittel der Venen beider Beine bzw. im Bereich des kleinen Beckens, Bestimmung der Serumkonzentration von Protein C und Protein S, Ausschluss von APC-Resistenz und Faktor-V-Leiden-Mutation. Ergebnisse: In der farbkodierten Duplexsonographie thrombosierte Vena iliaca externa sowie septierte, jedoch suffiziente Vena femoralis communis beidseits, keine Insuffizienzen oder Thromben in den übrigen extraund intrafaszialen Beinvenen nachweisbar. In der Kernspintomographie der Beckenvenen stellte sich eine Hypoplasie der Vena cava inferior oberhalb der Nierenetage und eine Atresie der Vena cava inferior unterhalb der Nierenetage dar sowie ein ausgeprägter venöser Kollateralkreislauf im Bereich des Beckens über die Vv. iliacae internae beidseits und die Vv. lumbales ascendentes beidseits bei varikös entarteten Kollateralvenen im Bereich der Bauchdecke beidseits mit Anschluss an die V. femoralis communis beidseits. Die untersuchten Gerinnungsparameter blieben unauffällig. Schlussfolgerung: Ecstasy-Abusus kann in Kombination mit starker körperlicher Anstrengung zu Exsikkose und Hämokonzetration führen. Dies sehen wir als letzte Ursache der Thrombose bei bestehender Vena-cava-Aplasie.

Ribosomal and non-ribosomal resistance to oxazolidinones: species-specific idiosyncrasy of ribosomal alterations

A derivative of Mycobacterium smegmatis, which carries only one functional rRNA (rrn) operon, was used to isolate mutants resistant to the ribosome-targeted antibiotic linezolid. Isolation and characterization of linezolid-resistant clones revealed two classes of mutants. Ribosomes from class I mutants are resistant to oxazolidinones in an in vitro peptidyl transferase assay, indicating that resistance maps to the ribosome component. In contrast, ribosomes from class II mutants show wild-type susceptibility to a linezolid derivative in vitro, pointing to a non-ribosomal mechanism of resistance. Introduction of a wild-type ribosomal RNA operon into linezolid-resistant strains restored linezolid sensitivity in class I mutants, indicating that resistance (i) maps to the rRNA and (ii) is recessive. Sequencing of the entire rrn operon identified a single nucleotide alteration in 23S rRNA of class I mutant strains, 2447G --> T (Escherichia coli numbering). Introduction of mutant rrl2447T into M. smegmatis rrn- resulted in a linezolid-resistant phenotype, demonstrating a cause-effect relationship of the 2447G --> T alteration. The 2447G --> T mutation, which renders M. smegmatis linezolid resistant, confers lethality in E. coli. This finding is strong evidence of structural and pos-sibly functional differences between the ribosomes of Gram-positive and Gram-negative bacteria. In agreement with the results of the in vitro assay, class II mutants show a wild-type sequence of the complete rRNA operon. The lack of cross-resistance of the class II mutants to other antibiotics suggests a resistance mechanism other than activation of a broad-spectrum multidrug transporter.

Oxidative stress response genes in Mycobacterium tuberculosis: role of ahpC in resistance to peroxynitrite and stage-specific survival in macrophages

The Mycobacterium tuberculosis ahpC gene, encoding the mycobacterial orthologue of alkylhydroperoxide reductase, undergoes an unusual regulatory cycle. The levels of AhpC alternate between stages of expression silencing in virulent strains grown as aerated cultures, secondary to a natural loss of the regulatory oxyR function in all strains of the tubercle bacillus, and expression activation in static bacilli by a yet undefined mechanism. The reasons for this unorthodox regulatory cycle controlling expression of an antioxidant factor are currently not known. In this work, M. tuberculosis H37Rv and Mycobacterium smegmatis mc(2)155 ahpC knockout mutants were tested for sensitivity to reactive nitrogen intermediates, in particular peroxynitrite, a highly reactive combinatorial product of reactive nitrogen and oxygen species, and sensitivity to bactericidal mechanisms in resting and activated macrophages. Both M. tuberculosis ahpC::Km(r) and M. smegmatis ahpC::Km(r) showed increased susceptibility to peroxynitrite. In contrast, inactivation of ahpC in M. tuberculosis did not cause increased sensitivity to donors of NO alone. M. tuberculosis ahpC::Km(r) also showed decreased survival in unstimulated macrophages, but the effect was no longer detectable upon IFNgamma activation. These studies establish a specific role for ahpC in antioxidant defences involving peroxynitrite and most likely additional cidal mechanisms in macrophages, with the regulatory cycle likely contributing to survival upon coming out of the stationary phase during dormancy (latent infection) or upon transmission to a new host.

The role of cortisol suppression on craving for and satisfaction from nicotine in high and low impulsive subjects

The rewarding properties of drug self-administration have been shown to depend on mesolimbic dopamine release but also on the availability of corticosterone, as shown in rats. Since this became particularly evident when tested in rat strains bred for high (HR) and low (LR) reactivity to novel stimuli, the role of cortisol and personality in drug craving was investigated in 60 male nicotine-deprived smokers divided according to questionnaire scores into high and low impulsives, a dimension considered to represent HR/LR rats. They either received the peripheral cortisol blocker metyrapone (MET) or the centrally blocking substance dexamethasone (DEX) or placebo (n=20 each) and were then allowed to smoke. MET more than DEX reduced craving for cigarettes during deprivation. This was only observed in low impulsives while high impulsives developed low craving unmodified by blockade of cortisol. Satisfaction from smoking was less achieved with DEX than with MET and not modified by impulsivity. Differences between MET and DEX in influencing craving during deprivation and satisfaction from smoking were discussed on the basis of different glucocorticoid receptors. The mineralocorticoid receptor (MR) seems to be the 'turn on switch' and the glucocorticoid receptor (GR) the 'turn off switch' in mediating the rewarding properties of dopamine in drug self-administration.

Silencing of oxidative stress response in Mycobacterium tuberculosis: expression patterns of ahpC in virulent and avirulent strains and effect of ahpC inactivation

Intracellular pathogens such as Mycobacterium tuberculosis are able to survive in the face of antimicrobial products generated by the host cell in response to infection. The product of the alkyl hydroperoxide reductase gene (ahpC) of M. tuberculosis is thought to be involved in protecting the organism against both oxidative and nitrosative stress encountered within the infected macrophage. Here we report that, contrary to expectations, ahpC expression in virulent strains of M. tuberculosis and Mycobacterium bovis grown in vitro is repressed, often below the level of detection, whereas expression in the avirulent vaccine strain M. bovis BCG is constitutively high. The repression of the ahpC gene of the virulent strains is independent of the naturally occurring lesions of central regulator oxyR. Using a green fluorescence protein vector (gfp)-ahpC reporter construct we present data showing that repression of ahpC of virulent M. tuberculosis also occurred during growth inside macrophages, whereas derepression in BCG was again seen under identical conditions. Inactivation of ahpC on the chromosome of M. tuberculosis by homologous recombination had no effect on its growth during acute infection in mice and did not affect in vitro sensitivity to H2O2. However, consistent with AhpC function in detoxifying organic peroxides, sensitivity to cumene hydroperoxide exposure was increased in the ahpC::Km(r) mutant strain. The preservation of a functional ahpC gene in M. tuberculosis in spite of its repression under normal growth conditions suggests that, while AhpC does not play a significant role in establishing infection, it is likely to be important under certain, as yet undefined conditions. This is supported by the observation that repression of ahpC expression in vitro was lifted under conditions of static growth.

pKa of adenine 2451 in the ribosomal peptidyl transferase center remains elusive

The universally conserved A2451 of 23S rRNA has been proposed to participate directly in the catalysis of peptide bond formation in the ribosomal peptidyl transferase center. An unusually high, near neutral, pKa of A2451 is a prerequisite for its action as a general acid-base catalyst. Increased reactivity of A2451 to dimethylsulfate (DMS) at pH 8.5 compared to pH 6.5 was taken as evidence that the pKa of this nucleotide falls within this pH range. Structural data suggested that the interaction between A2451 and G2447 in the ribosome is responsible for A2451 pKa perturbation. In contrast to expectation, our studies did not show pH dependence of A2451 dimethylsulfate modification in ribosomes of Thermus aquaticus and Mycobacterium smegmatis. Other rRNA regions, however, showed major alterations in DMS reactivity at pH 8.5 compared to pH 6.5, suggesting that conformational rearrangements in the structure of the large ribosomal subunit may occur upon the pH shift. The G2447U mutant of M. smegmatis was viable, indicating that the G2447-A2451 interaction is not critical for the ribosome function. We concluded that the proposed unusual pKa of A2451, if existing, may not be crucial for the ribosome activity and that the previously reported pH-dependent alterations in the DMS modification of A2451 do not necessarily reveal an unusual pKa of this nucleotide.

Mechanisms of streptomycin resistance: selection of mutations in the 16S rRNA gene conferring resistance

Chromosomally acquired streptomycin resistance is frequently due to mutations in the gene encoding the ribosomal protein S12, rpsL. The presence of several rRNA operons (rrn) and a single rpsL gene in most bacterial genomes prohibits the isolation of streptomycin-resistant mutants in which resistance is mediated by mutations in the 16S rRNA gene (rrs). Three strains were constructed in this investigation: Mycobacterium smegmatis rrnB, M. smegmatis rpsL(3+), and M. smegmatis rrnB rpsL(3+). M. smegmatis rrnB carries a single functional rrn operon, i.e., rrnA (comprised of 16S, 23S, and 5S rRNA genes) and a single rpsL+ gene; M. smegmatis rpsL(3+) is characterized by the presence of two rrn operons (rrnA and rrnB) and three rpsL+ genes; and M. smegmatis rrnB rpsL(3+) carries a single functional rrn operon (rrnA) and three rpsL+ genes. By genetically altering the number of rpsL and rrs alleles in the bacterial genome, mutations in rrs conferring streptomycin resistance could be selected, as revealed by analysis of streptomycin-resistant derivatives of M. smegmatis rrnB rpsL(3+). Besides mutations well known to confer streptomycin resistance, novel streptomycin resistance conferring mutations were isolated. Most of the mutations were found to map to a functional pseudoknot structure within the 530 loop region of the 16S rRNA. One of the mutations observed, i.e., 524G-->C, severely distorts the interaction between nucleotides 524G and 507C, a Watson-Crick interaction which has been thought to be essential for ribosome function. The use of the single rRNA allelic M. smegmatis strain should help to elucidate the principles of ribosome-drug interactions.

Mycobacterium bovis BCG recA deletion mutant shows increased susceptibility to DNA-damaging agents but wild-type survival in a mouse infection model

Pathogenic microorganisms possess antioxidant defense mechanisms for protection from reactive oxygen metabolites which are generated during the respiratory burst of phagocytic cells. These defense mechanisms include enzymes such as catalase, which detoxifies reactive oxygen species, and DNA repair systems, which repair damage resulting from oxidative stress. To (i) determine the relative importance of the DNA repair system when oxidative stress is encountered by the Mycobacterium tuberculosis complex during infection of the host and to (ii) provide improved mycobacterial hosts as live carriers to express foreign antigens, the recA locus was inactivated by allelic exchange in Mycobacterium bovis BCG. The recA mutants are sensitive to DNA-damaging agents and show increased susceptibility to metronidazole, the first lead compound active against the dormant M. tuberculosis complex. Surprisingly, the recA genotype does not affect the in vitro dormancy response, nor does the defect in the DNA repair system lead to attenuation as determined in a mouse infection model. The recA mutants will be a valuable tool for further development of BCG as an antigen delivery system to express foreign antigens and as a source of a genetically stable vaccine against tuberculosis.

Structural basis for selectivity and toxicity of ribosomal antibiotics

Ribosomal antibiotics must discriminate between bacterial and eukaryotic ribosomes to various extents. Despite major differences in bacterial and eukaryotic ribosome structure, a single nucleotide or amino acid determines the selectivity of drugs affecting protein synthesis. Analysis of resistance mutations in bacteria allows the prediction of whether cytoplasmic or mitochondrial ribosomes in eukaryotic cells will be sensitive to the drug. This has important implications for drug specificity and toxicity. Together with recent data on the structure of ribosomal subunits these data provide the basis for development of new ribosomal antibiotics by rationale drug design.

Instability and site-specific excision of integration-proficient mycobacteriophage L5 plasmids: development of stably maintained integrative vectors

Integrative vectors expressing foreign genes are used as tools for the development of recombinant vaccines in mycobacteria since it is assumed that these vectors are stably maintained even without antibiotic selection. We here demonstrate that integration-proficient vectors are lost from the mycobacterial genome in high frequency. Loss of integrated vectors occurred in recA+ and in recA-strains, indicating a RecA-independent mechanism. Loss of the integrated vector was prevented when integrase gene function was carried on a separate plasmid that is unable to replicate in mycobacteria, indicating that excision is a function of integrase. By providing attP in cis and integrase function in trans, vectors integrating at the attB site are stably maintained, even when carrying genes that deleteriously affect the host.

Gene Replacement in Mycobacterium tuberculosis and Mycobacterium bovis BCG Using rpsL as a Dominant Negative Selectable Marker

Much progress has been made in mycobacterial research in general and in mycobacterial genetics in particular during the past 10 yr. The complete genome sequences of two isolates of Mycobacterium tuberculosis, the widely distributed laboratory strain M. tuberculosis H37Rv (1) and a clinical isolate CDC 1551 ( http://www.tigr.org ), have recently been determined, thus providing a complete blueprint of the genetic make-up of this pathogen.

Bioavailability of a crushed pantoprazole tablet after buffering with sodium hydrogencarbonate or magaldrate relative to the intact enteric coated pantoprazole tablet

The aim of this study was to determine the bioavailability of orally administered, crushed pantoprazole tablets after buffering with either 1.4% sodium hydrogencarbonate or 1600 mg magaldrate relative to the intact enteric coated pantoprazole tablet. A single dose, three-period crossover study was performed with 18 healthy male volunteers. The crushed pantoprazole suspension, together with either sodium hydrogencarbonate or magaldrate, was administered via a nasogastral tube. Tmax of crushed pantoprazole was earlier as compared to the intact tablet (0.5 h vs. 3 h) and Cmax was approximately 10% higher due to faster absorption. The bioavailability of the crushed pantoprazole tablet relative to the intact pantoprazole tablet was 93% when using sodium hydrogencarbonate as the buffering agent, and 88% when using magaldrate. Based on the internationally approved confidence intervals for AUC (0.80-1.20) and Cmax (0.70-1.43), the crushed tablet buffered with sodium hydrogencarbonate was shown to be bioequivalent with the intact tablet (point estimates for AUC or Cmax: 0.93 or 1.10). For the crushed tablet buffered with magaldrate (point estimates for AUC or Cmax: 0.88 or 1.12) bioequivalence with the intact tablet could not be formally demonstrated, although the lower confidence limit for AUC of 0.78 was only slightly below the lower limit of the equivalence range of 0.80.

Contribution of the multidrug efflux pump LfrA to innate mycobacterial drug resistance

Multidrug resistance (MDR) in bacteria has been associated with efflux pumps that export structurally unrelated compounds and decrease cytoplasmic drug accumulation. To investigate MDR in mycobacteria, we studied the Mycobacterium smegmatis mutant mc(2)11, which is resistant to doxorubicin, tetracycline, rhodamine, ethidium bromide and the hydrophilic fluoroquinolones. A genomic library constructed from this mutant was used to select clones conferring resistance to doxorubicin. Surprisingly, the clone selected encodes the efflux pump LfrA, which has been reported to confer resistance to hydrophilic fluoroquinolones, ethidium bromide, rhodamine, and acriflavine. To define the contribution of LfrA to the innate mycobacterial drug resistance and to the MDR phenotype in mc(2)11, the lfrA gene was disrupted in both the mc(2)11 mutant and the mc(2)155 wild-type parent. LfrA disruption of the wild-type strain decreased resistance to ethidium bromide and acriflavine, and increased accumulation of ethidium bromide. However, disruption of lfrA gene results only in a 2-fold decrease in minimal inhibitory concentrations (MICs) for ciprofloxacin, doxorubicin, rhodamine, and accumulation of [(14)C]ciprofloxacin was unchanged. LfrA disruption of the MDR strain mc(2)11 produced a similar phenotype. Thus, LfrA contributes significantly to the intrinsic MICs of M. smegmatis for ethidium bromide and acriflavine, but not for ciprofloxacin, doxorubicin or rhodamine.

Age-related differences in twitch contractile properties of plantarflexor muscles in women

This study compared maximal voluntary isometric strength and electrically evoked twitch characteristics of the plantarflexor muscles among the groups of women of the 3rd (n=14), 4th (n=13), 5th (n=11), 6th (n=12) and 8th (n=13) decade. A significant decrease (P < 0.05-0.001) has been found in isometric maximal voluntary contraction (MVC) force from the 5th decade and in twitch maximal force from the 6th decade. The 3rd decade group produced 72% greater MVC force and 43% greater twitch maximal force than the 8th decade group (P < 0.001). A prolongation (P < 0.01) in twitch contraction time was observed from the 5th decade. Twitch contraction time in the 3rd decade group was 16% shorter (P < 0.001) compared with the 8th decade group (P < 0.01). Twitch half-relaxation time did not differ significantly (P > 0.05) among the groups. A decrease (P < 0. 05-0.001) has been found in twitch maximal rate of force development from the 5th decade and in twitch maximal rate of relaxation from the 6th decade. The 3rd decade group produced 63% greater (P < 0. 001) twitch maximal rate of force development than the 8th decade group. It was concluded that in women a marked age-related reduction in maximal voluntary force-generating capacity of the plantarflexor muscles and speed of contraction of the electrically evoked twitch takes place after 40 years of age, while reduction in maximal force-generating capacity and speed of relaxation of the twitch occurs after 50 years of age.

In vivo splicing and functional characterization of Mycobacterium leprae RecA

The RecA proteins from Mycobacterium tuberculosis and Mycobacterium leprae contain inteins. In contrast to the M. tuberculosis RecA, the M. leprae RecA is not spliced in Escherichia coli. We demonstrate here that M. leprae RecA is functionally spliced in Mycobacterium smegmatis and produces resistance toward DNA-damaging agents and homologous recombination.

[The effect of a vaginal device on urinary leakage and quality of life of women with stress urinary incontinence]

The aim of this study was to assess the effect of a vaginal device (Continence Guard) on urine leakage and its impact on quality of life (QoL). Fifty-five women participated in a three month study using the Continence Guard. QoL was assessed by an incontinence specific questionnaire (IIQ), two incontinence specific questions and the generic SF-36 health questionnaire. A total of 41 (74.5%) women completed the study. Use of the vaginal device was associated with subjective cure in 11 women (27%) and improvement in 27 (66%). The mean 24-hour pad test leakage decreased significantly. QoL measured by the IIQ and the two incontinence specific questions showed highly significant improvements. The SF-36 questionnaire showed no significant changes. In conclusion treatment with the Continence Guard significantly decreases leakage and improves QoL in women with the symptom of urinary stress incontinence. The SF-36 questionnaire was not sensitive enough to detect alterations in QoL in patients with stress urinary incontinence.

The visual G protein of fly photoreceptors interacts with the PDZ domain assembled INAD signaling complex via direct binding of activated Galpha(q) to phospholipase cbeta

Visual transduction in the compound eye of flies is a well-established model system for the study of G protein-coupled transduction pathways. Pivotal components of this signaling pathway, including the principal light-activated Ca(2+) channel transient receptor potential, an eye-specific protein kinase C, and the norpA-encoded phospholipase Cbeta, are assembled into a supramolecular signaling complex by the modular PDZ domain protein INAD. We have used immunoprecipitation assays to study the interaction of the heterotrimeric visual G protein with this INAD signaling complex. Light-activated Galpha(q)- guanosine 5'-O-(thiotriphosphate) and AlF(4)(-)-activated Galpha(q), but not Gbetagamma, form a stable complex with the INAD signaling complex. This interaction requires the presence of norpA-encoded phospholipase Cbeta, indicating that phospholipase Cbeta is the target of activated Galpha(q). Our data establish that the INAD signaling complex is a light-activated target of the phototransduction pathway, with Galpha(q) forming a molecular on-off switch that shuttles the visual signal from activated rhodopsin to INAD-linked phospholipase Cbeta.

Objektivierung kutaner Mikrozirkulationsstörungen bei akralen vaskulären Erkrankungen mittels Laser-Doppler- Perfusion-Imaging

Periphere arterielle Verschlüsse lassen sich mittels der arteriellen digitalen Subtraktionsangiographie (DSA) darstellen. Methode: In der vorliegenden Fallstudie verglichen wir die invasive Technik der arteriellen DSA mit dem nichtinvasiven zweidimensionalen Laser-Doppler- Perfusion-Imaging. Ergebnis: Bei 2 Patienten mit Thrombangitis obliterans entsprachen den Arterienabbrüchen Areale mit verminderten Fluxwerten im LDPIBild. Eine Patientin mit Livedo-Vaskulitis zeigte hingegen eine vermehrte Gefäßkontrastierung und vermehrten Kontrastmittelfluß in der DSA, aber Areale mit verminderten Fluxwerten im LDPI-Bild. Histologisch entsprachen den offenen Lumina der subkutanen Arterien hingegen hyaline Thromben der korialen Arteriolen. Schlußfolgerung: Insgesamt erfaßt das LDPI offenbar selektiv die kutane Perfusion. Da das Verfahren nicht invasiv ist, ermöglicht es wiederholte Verlaufskontrollen.

Evaluation of a simple, non-surgical concept for management of urinary incontinence (minimal care) in an open-access, interdisciplinary incontinence clinic

Our objective was to evaluate a new concept for assessment and treatment of urinary incontinence in an open-access, interdisciplinary incontinence clinic. A standardized program for investigation and treatment of incontinence was based on minimal relevant investigations, primarily non-surgical treatment with a limited consumption of resources ("minimal care"). This was a prospective observational study of 408 consecutive women examined and treated in the clinic. The main characteristics of the women were a high median age and a high prevalence of severe concomitant diseases with possible influence on lower urinary tract function. More than half of the patients had urge or mixed incontinence. Most of the patients were managed with conservative treatment. Fifteen percent were referred to in-hospital treatment, with 5% to incontinence surgery. In total 44% felt cured or very much improved. Before and after treatment one third of the women completed quality-of-life questions and voiding charts, while 43% completed the pad tests. Quality of life improved significantly. Objectively leakage on pad test and voiding charts was significantly improved. The patients were in general very satisfied with clinic's program. Almost one fourth of the women were followed up for 6 months after discharge. No significant deterioration in the subjective results were found compared to status at discharge. In conclusion, the results highlight the need for advice and treatment of patients with incontinence. The minimal care program and interdisciplinary structure in the incontinence clinic offer effective and low cost treatment for urinary incontinence. The open-access, interdisciplinary incontinence clinic model is recommended. Neurourol. Urodynam. 18:9-17, 2000.

[Tazarotene increases the antipsoriatic effect of dithranol in chronic psoriasis]

We examined whether it is possible to increase the antipsoriatic action by combining dithranol with a retinoid (tazarotene). In a randomized, open, prospective study with 50 psoriatic patients (22 females, 28 males, PASI>10) the antipsoriatic effectiveness of dithranol monotherapy to was compared combined therapy with dithranol and retinoid. The combination dithranol/retinoid (collective 2, reduction of the PASI from 17,2 to 2,8) revealed a significantly faster healing than the dithranol monotherapy (collective 1, reduction of the PASI from 18,5 to 4,8). The irritation of the combination therapy as evaluated with clinical score and laser doppler imaging was increased. Anti-psoriatic effectiveness of dithranol can be increased by combining it with tazarotene.

A vaginal device (continence guard) in the management of urge incontinence in women

The aim of the study was to assess the efficacy of a disposable vaginal device in the management of urge incontinence. A total of 38 women with urge incontinence and uninhibited bladder contractions during cystometry were included. They wore the device from morning to night. Before, and again after, using the device for 1 month the women were assessed by pelvic examination, uroflowmetry, postvoid residual urine, two 24-hour pad-tests, a 3-day voiding diary and vaginal and urine cultures. A questionnaire about the subjective effect and adverse events was completed. Thirty women (79%) completed the study. Two (6.7%) were subjectively cured when using the device, 15 (50%) were improved, and 13 (43.3%) experienced unchanged incontinence. The 24-hour pad-test leakage showed a statistically significant decrease (P=0.001) - in 11 women (36.7%) the decrease was more than 50%. The other urodynamic results were unchanged. A significant decrease in the number of daily micturitions was found in the group of responders (P=0.02). No vaginal infections were found; 4 women (13%) had uncomplicated urinary tract infection during the test-period. Subjective complaints were few, and 21 women (70%) wanted to continue the treatment with the device. The vaginal device constitutes a new option in the management of urge incontinence, with a subjective and objective cure/improvement rate of 56.7%. The device is easy to use and well accepted.

Anal incontinence after obstetric third- /fourth-degree laceration. One-year follow-up after pelvic floor exercises

The study was a 1-year follow-up of 48 women with obstetric third- /fourth-degree perineal laceration. After primary surgical repair the symptomatic patients were treated with pelvic floor exercises with or without transanal electrical stimulation. Various methods for assessing anal sphincter function were also evaluated. One month postpartum 10 women (21%) complained of anal incontinence, 8 for flatus only; 1 patient was reoperated on. After 1 year none complained of fecal incontinence, and 3 (7%) complained of flatus incontinence. We found relatively few women with anal incontinence after third- /fourth-degree laceration. The pelvic floor training program was effective, but electrical stimulation was abandoned because of anal pain. Grade IIIb lesion, dilution of the sphincter at anal ultrasonography, and sphincter weakness at palpation were significantly related to symptoms of anal incontinence. For routine follow-up after third- /fourth-degree laceration, palpation of the anal sphincter and pelvic floor seems sufficient as first-line assessment.

RecA-Mediated gene conversion and aminoglycoside resistance in strains heterozygous for rRNA

Clinical resistance to aminoglycosides in general is due to enzymatic drug modification. Mutational alterations of the small ribosomal subunit rRNA have recently been found to mediate acquired resistance in bacterial pathogens in vivo. In this study we investigated the effect of 16S rRNA heterozygosity (wild-type [wt] and mutant [mut] operons at position 1408 [1408wt/1408mut]) on aminoglycoside resistance. Using an integrative vector, we introduced a single copy of a mutated rRNA operon (1408 A-->G) into Mycobacterium smegmatis, which carries two chromosomal wild-type rRNA operons; the resultant transformants exhibited an aminoglycoside-sensitive phenotype. In contrast, introduction of the mutated rRNA operon into an M. smegmatis rrnB knockout strain carrying a single functional chromosomal wild-type rRNA operon resulted in aminoglycoside-resistant transformants. Subsequent analysis by DNA sequencing and RNase protection assays unexpectedly demonstrated a homozygous mutant genotype, rRNAmut/rRNAmut, in the resistant transformants. To investigate whether RecA-mediated gene conversion was responsible for the aminoglycoside-resistant phenotype in the rRNAwt/rRNAmut strains, recA mutant strains were generated by allelic exchange techniques. Transformation of the recA rrnB M. smegmatis mutant strains with an integrative vector expressing a mutated rRNA operon (Escherichia coli position 1408 A-->G) resulted in transformants with an aminoglycoside-sensitive phenotype. Subsequent analysis showed stable heterozygosity at 16S rRNA position 1408 with a single wild-type allele and a single resistant allele. These results demonstrate that rRNA-mediated mutational resistance to aminoglycosides is recessive.