Early mitral valve repair versus watchful waiting in patients with severe asymptomatic organic mitral regurgitation; rationale and design of the Dutch AMR trial, a multicenter, randomised trial

BACKGROUND

Asymptomatic severe mitral valve (MV) regurgitation with preserved left ventricular function is a challenging clinical entity as data on the recommended treatment strategy for these patients are scarce and conflicting. For asymptomatic patients, no randomised trial has been performed for objectivising the best treatment strategy.

METHODS

The Dutch AMR (Asymptomatic Mitral Regurgitation) trial is a multicenter, prospective, randomised trial comparing early MV repair versus watchful waiting in asymptomatic patients with severe organic MV regurgitation. A total of 250 asymptomatic patients (18-70 years) with preserved left ventricular function will be included. Intervention will be either watchful waiting or MV surgery. Follow-up will be 5 years. Primary outcome measures are all-cause mortality and a composite endpoint of cardiovascular mortality, congestive heart failure, and hospitalisation for non-fatal cardiovascular and cerebrovascular events. Secondary outcome measures are total costs, cost-effectiveness, quality of life, echocardiographic and cardiac magnetic resonance parameters, exercise tests, asymptomatic atrial fibrillation and brain natriuretic peptide levels. Additionally, the complication rate in the surgery group and rate of surgery in the watchful waiting group will be determined.

IMPLICATIONS

The Dutch AMR trial will be the first multicenter randomised trial on this topic. We anticipate that the results of this study are highly needed to elucidate the best treatment strategy and that this may prove to be an international landmark study.

Sacral nerve stimulation for neuromodulation of the lower urinary tract

Sacral neuromodulation (SNM) has become a standard treatment option for patients suffering from urinary urge incontinence, urgency-frequency, and/or nonobstructive urinary retention refractory to conservative and pharmacologic treatment. Since its initial development, the manufacturer of InterStim therapy (Medtronic, Inc., Minneapolis, MN, USA), has introduced technical modifications, while surgeons and researchers have adapted and published various innovations and alterations of the implantation technique. In this article, we feature our SNM technique including patient selection, comprehensive dialogue/evaluation, procedure details, and appropriate follow up. Although there is often great variability in patients with lower urinary tract dysfunction, we maintain that great success can be achieved with a systematic and methodical approach to SNM.

Possible prevention and treatment of prostate cancer by exercise

Exercise and physical activity have been linked to the prevention of certain types of cancer such as colon and breast. As prostate cancer is the most common malignancy diagnosed in the male population, there is obvious interest in determining a possible effect of exercise on disease prevention and improvement of disease-related outcomes. Thus far, data has been conflicting and there has been no clear determination of prostate cancer prevention through exercise. However, as prostate cancer treatment carries many side effects which may be bothersome and health-threatening, researchers have examined the effects of exercise training on reducing treatment-related complications and improving outcomes and quality of life (QOL). In this review, we discuss the impact of exercise on reducing side effects of prostate cancer treatment and improving cancer-specific and overall survival outcomes, as well as improving QOL in prostate cancer patients.

Testicular trauma resulting in spermatic vessel thrombosis and testicular loss: a case report

Testicular ischemia is typically seen with cases of testicular torsion. Twisting of the spermatic cord and compromise of testicular blood supply can induce testicular loss if not promptly discovered and treated. Non-torsion causes of testicular ischemia are uncommon with rare citations in the literature. Herein, we present a case of testicular ischemia induced by traumatic thrombosis of the spermatic vessels.

Unbiased estimation of Langevin dynamics from time series with application to hippocampal field potentials in vitro

The last decade showed an increased interest in Langevin equations for modeling time series recorded from complex dynamical systems. These equations allow to discriminate between deterministic (drift) and stochastic (diffusion) components of the recorded time series. In practice, the estimation of drift and diffusion is often based on approximations of the models' dynamics that are valid only for high sampling frequencies. Also, model assessment is not or only indirectly performed, potentially leading to false claims. In this study we compare the performance of an asymptotically unbiased estimation method with a generally used approximate method, demonstrating the necessity of using (asymptotically) unbiased estimators. Furthermore, we describe how confidence intervals for the unknown parameters can be constructed and how model assessment can be carried out. We apply the methodology to local field potentials recorded in vitro from mouse hippocampus from eight genetically different strains. The recorded field potentials turn out to be well described by linearly damped Langevin equations with parabolic diffusion. The modeling enables a dynamical interpretation of the spectral power of the field potentials. It reveals that observed spectral power differences in the field potentials across hippocampal regions are associated with differences in the deterministic component of the system, and it reveals transiently active current dipoles, which are not detectable by conventional methods. Also, all estimated parameters have significant heritabilities, which suggests that the Langevin equations capture biological relevant aspects of electrical hippocampal activity.

Ventricular asystole due to inhibition of ventricular backup pacing by a dual chamber pacemaker: possible pitfalls of default settings

A 62-year-old patient presented with dizzy spells after her dual chamber pacemaker (Medtronic Enrhythm P1501DR), implanted for complete AV block, had been reprogrammed to deliver antitachycardia therapy (ATP) for paroxysmal atrial tachycardia. Her symptoms were caused by inhibition of ventricular backup pacing during ATP, leading to ventricular asystoles. Inhibition was the result of premature ventricular beats occurring prior to ATP: when ventricular backup pacing is left in the default setting, this pacemaker withholds backup pacing if any of the four preceding events is a sensed event. This case illustrates the possibly hazardous effects of default pacemaker settings, especially in pacemaker-dependent patients. (Neth Heart J 2010;18:323-6.).

Inbred mouse strains differ in multiple hippocampal activity traits

A major challenge in neuroscience is to identify genes that influence specific behaviors and to understand the intermediary neuronal mechanisms. One approach is to identify so-called endophenotypes at different levels of neuronal organization from synapse to brain activity. An endophenotype is a quantitative trait that is closer to the gene action than behavior, and potentially a marker of neuronal mechanisms underlying behavior. Hippocampal activity and, in particular, hippocampal oscillations have been suggested to underlie various cognitive and motor functions. To identify quantitative traits that are potentially useful for identifying genes influencing hippocampal activity, we measured gamma oscillations and spontaneous activity in acute hippocampal slices from eight inbred mouse strains under three experimental conditions. We estimated the heritability of more than 200 quantitative traits derived from this activity. We observed significant differences between the different mouse strains, particularly in the amplitude of the activity and the correlation between activities in different hippocampal subregions. Interestingly, these traits had a low genetic correlation between the three experimental conditions, which suggests that different genetic components influence the activity in different conditions. Our findings show that several traits of hippocampal gamma oscillations and spontaneous activity are heritable and could thus be potentially useful in gene-finding strategies based on endophenotypes.

Antimicrobial and cytotoxic abietane diterpenoids from the roots of Meriandera benghalensis (Roxb.) Benth

Four abietane diterpenoids were isolated from the methanolic extract of the roots of Meriandera benghalensis and tested for their biological activity. Cryptotanshinone (2) and 17-hydroxycryptotanshinone (4) are known metabolites however the occurrence of tanshinone IIA (1) and przewaquinone A (3) from Meriandera benghalensis is reported for the first time. The four diterpenoids were identified by MS and one- and two dimensional NMR experiments. The isolated compounds were tested for their in vitro antiproliferative activity against three human cancer cell lines (a lung cancer (A-427), a urinary bladder cancer (5637) and a breast cancer (MCF-7) cell line) and for their antibacterial effect against three Gram-positive bacterial strains. All four abietanes showed potent cytotoxic effect against all cancer cell lines (IC50 between 1 and 8 microM) as well as antibacterial effect against the bacteria tested (MIC values between 33 and 70 microM).

Contribution of the drug transporter ABCG2 (breast cancer resistance protein) to resistance against anticancer nucleosides

We have studied the potential contribution of ABCG2 (breast cancer resistance protein) to resistance to nucleoside analogues. In cells transfected with DNA constructs resulting in overexpression of human or mouse ABCG2, we found resistance against cladribine, clofarabine, fludarabine, 6-mercaptopurine, and 6-mercaptopurine riboside in both MDCKII and HEK293 cells and against gemcitabine only in HEK293 cells. With Transwell studies in MDCK cells and transport experiments with vesicles from Sf9 and HEK293 cells, we show that ABCG2 is able to transport not only the nucleotide CdAMP, like several other ATP-binding cassette transporters of the ABCC (multidrug resistance protein) family, but also the nucleoside cladribine itself. Expression of ABCG2 in cells results in a substantial decrease of intracellular CdATP, explaining the resistance against cladribine. The high transport rate of cladribine and clofarabine by ABCG2 deduced from Transwell experiments raises the possibility that this transporter could affect the disposition of nucleoside analogues in patients or cause resistance in tumors.

Prevalence, characterisation and clinical profiles of Shiga toxin-producing Escherichia coli in The Netherlands

Detection of Shiga toxin-producing Escherichia coli (STEC) in The Netherlands is traditionally limited to serogroup O157. To assess the relative importance of STEC, including non-O157 serogroups, stool samples submitted nationwide for investigation of enteric pathogens or diarrhoea were screened with real-time PCR for the presence of the Shiga toxin genes. Patients were selected if their stool contained blood upon macroscopic examination, if they had a history of bloody diarrhoea, were diagnosed with haemolytic uraemic syndrome, or were aged <6 years (irrespective of the bloody aspect of the stool). PCR-positive stools were forwarded to a central laboratory for STEC isolation and typing. In total, 4069 stools were examined, with 68 (1.7%) positive PCR results. The highest prevalence was for stools containing macroscopic blood (3.5%), followed by stools from patients with a history of bloody diarrhoea (2.4%). Among young children, the prevalence (1.0%) was not significantly higher than among random, non-bloody, stool samples from diarrhoeal patients (1.4%). STEC strains were isolated from 25 (38%) PCR-positive stools. Eleven O-serogroups were detected, including five STEC O157 strains. As serogroup O157 represented only 20% of the STEC isolates, laboratories should be encouraged to use techniques enabling them to detect non-O157 serogroups, in parallel with culture, for isolation and subsequent characterisation of STEC strains for public health surveillance and detection of outbreaks.

Detection of a spin accumulation in nondegenerate semiconductors

Electrical detection of a spin accumulation in a nondegenerate semiconductor using a tunnel barrier and ferromagnetic contact is shown to be fundamentally affected by the energy barrier associated with the depletion region. This prevents the ferromagnet from probing the spin accumulation directly, strongly suppresses the magnetoresistance in current or potentiometric detection, and introduces nonmonotonic variation of spin signals with voltage and temperature. Having no analogue in metallic systems, we identify energy mismatch as an obstacle for spin detection, necessitating control of the energy landscape of spin-tunnel contacts to semiconductors.

Tunnel spin polarization versus energy for clean and doped Al2O3 barriers

The variation of the tunnel spin-polarization (TSP) with energy is determined using a magnetic tunnel transistor, allowing quantification of the energy dependent TSP separately for both ferromagnet/insulator interfaces and direct correlation with the tunnel magnetoresistance (TMR) measured in the same device. The intrinsic TSP is reduced below the Fermi level, and more strongly so for tunneling into empty states above the Fermi level. For artificially doped barriers, the low bias TMR decreases due to defect-assisted tunneling. Yet, this mechanism becomes ineffective at large bias, where instead inelastic spin scattering causes a strong TMR decay.

EQUAL-qual: a European program for external quality assessment of genomic DNA extraction and PCR amplification

BACKGROUND

Despite the rapid transition into routine clinical practice of molecular techniques based on PCR, external quality assessment (EQA) is still not widely available. The European Union and European Communities Confederation of Clinical Chemistry have supported the EQUAL project as a series of 3 different EQA programs for the assessment of molecular methods independently from analytes. We present the results from the EQUAL-qual program designed to evaluate the analytical aspects of DNA analysis by means of a conventional qualitative PCR experiment.

METHODS

The EQUAL-qual program provided DNA, blood samples, and primer sets to participant laboratories to assess DNA extraction and PCR amplification. We have developed statistical procedures to identify laboratories performing poorly in DNA extraction (quality and quantity), PCR efficiency, and data interpretation after electrophoresis.

RESULTS

An application to participate was obtained from 213 laboratories (from 25 countries), and 175 (82%) of laboratories submitted results for assessment. Questionable results in terms of quality and/or quantity of DNA derived from blood extractions were returned by 27% of laboratories (46 of 166). PCR efficiency showed high variability, with 3% of laboratories (5 of 163) showing a consistently low rate of amplification and 10% (18 of 175) not reporting the expected number of bands of the amplified targets.

CONCLUSIONS

The results showed considerable variability in all phases of the experiment. The approach confirms the validity of EQA as a method for evaluating analytical aspects of PCR-based tests.

Multicenter comparison of molecular methods for detection of Legionella spp. in sputum samples

Legionellosis can be diagnosed by PCR using sputum samples. In this report, the methods of nine laboratories for 12 sputum samples with Legionella pneumophila and Legionella longbeachae are compared. We conclude that (i) liquefaction prevents PCR inhibition, (ii) the employed mip gene PCRs detected L. pneumophila only, and (iii) the 16S rRNA gene PCR detected both Legionella species and is preferred for the diagnosis of legionellosis.

[Cardiopulmonary responses during high intensity weight training in male handball players]

OBJECTIVE

Strength training has become popular and accepted as part of a well-rounded fitness program. Moreover, resistance training is currently prescribed by many health organizations for improving health and fitness. The purpose of this study was to evaluate the possible influence of high intensity heavy weight training on endurance related parameters. Hence the characteristics of oxygen uptake (VO2) kinetics and the heart rate (HR) kinetics have been assessed during a typical session of strength training in twelve healthy male handball players, aged 20-30 years.

METHODS

The oxygen uptake and the heart rate were measured continuously using a portable breath-by-breath exercise system. The training consisted of 4 exercises (squat, bench press, lat pull, and neck press), each performed for ten repetitions at an intensity of 80% of one repetition maximum over a 30-seconds period with a 1:4 work/test ratio.

RESULTS

During weight training, the VO2 ranged from 0.8 +/- 0.2 l x min(-1) to 2.4 +/- 0.4 l x min(-1). The lowest values were measured during load, while peak values were reached 40 to 70 seconds after load. Mean (+/- SE) VO2 was 1.22 +/- 0.05 l x min(-1), or 26.5% of the treadmill-determined VO2(max). Mean (+/- SE) HR was 117 +/- 4 beats x min(-1), or 61% of the treadmill-determined HR(max).

CONCLUSION

The findings in the present study indicate that high intensity weight training is not able to produce adaptive improvement in cardiovascular function. The physiological responses measured during this experiment provide support to previous studies, that the lack of cardiovascular adaptation may be due to the low percentage of VO2(max)elicited by this form of training.

Outbreak detection and secondary prevention of Legionnaires’ disease: A national approach

BACKGROUND

To stop a possible outbreak of Legionnaires' disease (LD) at an early stage an outbreak detection programme was installed in The Netherlands.

METHODS

The programme consisted of sampling and controlling of potential sources to which LD patients had been exposed during their incubation period. Potential sources were considered to be true sources of infection if two or more LD patients (cluster) had visited them, or if available patients' isolates and environmental Legionella spp. were indistinguishable by amplified fragment length polymorphism genotyping.

RESULTS

Rapid sampling and genotyping as well as cluster recognition helped to target control measures. Despite these measures, two small outbreaks were only stopped after renewal of the water system. The combination of genotyping and cluster recognition lead to 29 of 190 (15%) patient-source associations.

CONCLUSION

Systematic sampling and cluster recognition can contribute to outbreak detection and lead to cost-effective secondary prevention of Legionnaires' disease.

Legionnaires’ disease and gardening

Legionella longbeachae was cultured from the sputum of a patient suffering from Legionnaires' disease. Source identification efforts included analysis of samples of potting soil from the patient's garden, and a genotypically indistinguishable strain of L. longbeachae was cultured from this material. Following examination of a national collection of Legionella isolates, two more patients with indistinguishable genotypes were identified. One of these patients had visited a garden centre in the same municipality in which the index patient had acquired his potting soil. The study demonstrated the value of systematic collection of identification data and patient isolates over a prolonged period.