Improved safety for molecular diagnosis of classical rabies viruses by use of a TaqMan real-time reverse transcription-PCR "double check" strategy

To improve the diagnosis of classical rabies virus with molecular methods, a validated, ready-to-use, real-time reverse transcription-PCR (RT-PCR) assay was developed. In a first step, primers and 6-carboxyfluorescien-labeled TaqMan probes specific for rabies virus were selected from the consensus sequence of the nucleoprotein gene of 203 different rabies virus sequences derived from GenBank. The selected primer-probe combination was highly specific and sensitive. During validation using a sample set of rabies virus strains from the virus archives of the Friedrich-Loeffler-Institut (FLI; Germany), the Veterinary Laboratories Agency (VLA; United Kingdom), and the DTU National Veterinary Institute (Lindholm, Denmark), covering the global diversity of rabies virus lineages, it was shown that both the newly developed assay and a previously described one had some detection failures. This was overcome by a combined assay that detected all samples as positive. In addition, the introduction of labeled positive controls (LPC) increased the diagnostic safety of the single as well as the combined assay. Based on the newly developed, alternative assay for the detection of rabies virus and the application of LPCs, an improved diagnostic sensitivity and reliability can be ascertained for postmortem and intra vitam real-time RT-PCR analyses in rabies reference laboratories.

Neurotropism in blackcaps (Sylvia atricapilla) and red-billed queleas (Quelea quelea) after highly pathogenic avian influenza virus H5N1 infection

The epidemiologic role of passerine birds in the spread of highly pathogenic avian influenza virus (HPAIV) remains controversial. However, confirmed natural infections with HPAIV in Passeriformes, their close contact to poultry and humans, and their role as a human food source indicate a need for increased research on passerines. To date, there are only a few studies on viral shedding and pathomorphologic changes in songbirds infected with HPAIV. To investigate susceptibility, clinical outcome, virus spread, and pathomorphology, the authors inoculated oculo-oronasally 22 red-billed queleas (Quelea quelea) and 11 blackcaps (Sylvia atricapilla) with A/Cygnus cygnus/Germany/R65/2006 (H5N1) using 2 different doses of either 10(4) EID50 (50% egg infective dose) or 10(6) EID50 per animal. They monitored all birds for clinical signs and oropharyngeal and cloacal virus shedding. They also performed immunohistochemistry and obtained molecular virologic data by real-time reverse transcription polymerase chain reaction in tissue samples. In contrast to blackcaps, where 100% of the infected individuals died, queleas were much less susceptible, with a mortality of 82% and 18%, depending on the doses applied. In both species, the virus was shed within 3 to 6 days postinfection, mainly via the respiratory tract. Viral antigen was detected in 100% of the succumbed birds, particularly in the central nervous system. In blackcaps, the heart, lungs, and pancreas were mainly infected. In contrast, the pancreas was predominantly affected in queleas, whereas the heart and the lower respiratory tract were of minor relevance. The authors hypothesize that neurotropism should be considered a main factor for the fatal course of disease in Passeriformes after infection with HPAIV.

[Functional cardiac MRI for assessment of aortic valve disease]

Aortic valve disease shows a rising incidence with the increasing mean age of Western populations. The detection of hemodynamic parameters, which transcends the mere assessment of valve morphology, has an important future potential concerning classification of the severity of disease. MRI allows a non-invasive and a spatially flexible view of the aortic valve and the adjacent anatomic region, left ventricular outflow tract (LVOT) and ascending aorta. Moreover, the technique allows the determination of functional hemodynamic parameters, such as flow velocities and effective orifice areas. The new approach of a serial systolic planimetry velocity-encoded MRI sequence (VENC-MRI) facilitates the sizing of blood-filled cardiac structures with the registration of changes in magnitude during systole. Additionally, the subvalvular VENC-MRI measurements improve the clinically important exact determination of the LVOT area with respect to its specific eccentric configuration and its systolic deformity.

Differentiation of two distinct clusters among currently circulating influenza A(H1N1)v viruses, March-September 2009

Analysis of all complete genome sequences of the pandemic influenza A(H1N1)v virus available as of 10 September 2009 revealed that two closely related but distinct clusters were circulating in most of the affected countries at the same time. The characteristic differences are located in genes encoding the two surface proteins - haemagglutinin and neuraminidase - and four internal proteins - the polymerase PB2 subunit, nucleoprotein, matrix protein M1 and the non-structural protein NS1. Phylogenetic inference was demonstrated by neighbour joining, maximum likelihood and Bayesian trees analyses of the involved genes and by tree construction of concatenated sequences.

Differentiation of two distinct clusters among currently circulating influenza A(H1N1)v viruses, March-September 2009

Analysis of all complete genome sequences of the pandemic influenza A(H1N1)v virus available as of 10 September 2009 revealed that two closely related but distinct clusters were circulating in most of the affected countries at the same time. The characteristic differences are located in genes encoding the two surface proteins - haemagglutinin and neuraminidase - and four internal proteins – the polymerase PB2 subunit, nucleoprotein, matrix protein M1 and the non-structural protein NS1. Phylogenetic inference was demonstrated by neighbour joining, maximum likelihood and Bayesian trees analyses of the involved genes and by tree construction of concatenated sequences.

[Oxygen-enhanced functional MR lung imaging]

Current diagnostic tools for the assessment of lung function are limited by global measurements or the need for radioactive tracers. Ideally, these tools should allow quantitative, regional distinct analyses without exposure to radiation. The current paper presents oxygen-enhanced functional MRI for assessment of lung ventilation. First applied in humans in 1996, a considerable amount of experience is now available on 1.5T scanners. The generation of quantitative T1-maps shows a high clinical potential. Low-field MR scanners, which are mostly open-designed, are especially interesting for functional lung imaging. The open design has advantages in respect to patient comfort by lower noise production and easy access to the patients and the costs are lower (no need for helium cooling). Lower signal-to-noise ratios can be overcome by changing the relaxation times. New navigator techniques allow further compensations. This article focuses on the presentation of low-field scanners and the application of T1 and T2(*) maps is described for healthy volunteers and first patients.

Efficacy of a commercial inactivated H5 influenza vaccine against highly pathogenic avian influenza H5N1 in waterfowl evaluated under field conditions

Highly pathogenic avian influenza virus (HPAIV) can cause devastating losses in the poultry industry. In addition, several HPAIV exhibit a zooanthroponotic potential and can cause fatal infections in humans. These attributes particularly apply to HPAIV H5N1 of Asian origin. Due to the absence of overt clinical symptoms, introduction and subsequent spread of HPAIV H5N1 in domestic waterfowl (especially ducks) may occur undetected, which increases the risk of transspecies transmissions to highly vulnerable gallinaceous poultry and mammals, including humans. Humans may also become infected with HPAIV H5N1 by food products from slaughtered, silently infected ducks. Vaccination against HPAIV can raise a protective barrier against an incursion of HPAIV since, at least under experimental conditions, the reproduction factor R0 lowered to <1, which ensures eradication of the virus. The objective of this study was to analyse whether these results can also be obtained under free-ranging field conditions in commercially reared flocks of goose parents and fattening ducks injected with a licensed, adjuvanted inactivated H5N2 vaccine. The time and labour required for the vaccination of these geese and duck flocks exceeded expected values, mainly due to animal sorting according to foot ring labels. No adverse effects directly associated with vaccination were observed. Serologically, a homogenous H5-specific antibody response was induced. Titres varied with temporal distance from the last application of vaccine. Geese parents were clinically protected against challenge with HPAIV A/Cygnus cygnus/Germany/R65/06 (H5N1), but still could be infected and spread HPAIV H5N1, albeit at lower levels and for shorter periods compared to unvaccinated controls. Fattening Pekin ducks proved to be clinically resistant against challenge virus infection and shed very little virus.

[Recommendations for utilizing computerized tomography and magnetic resonance tomography in heart diagnosis. 2--Magnetic resonance tomography ]

MRI and CT have become important tools in the diagnosis of cardiac diseases. The permanent technical development and the continuously growing clinical and scientific experience required an update of the previous recommendations regarding the spectrum of clinical applications and the technical aspects of MRI and CT of the heart. The Working group Herzdiagnostik of the German Roentgen Society has revised its recommendations based on the current literature and has updated technical requirements and clinical indications. Part I of the recommendations deals with cardiac computed tomography while part II focuses on MRI in cardiac applications. These recommendations shall serve as a guideline when deciding on appropriate technique for non-invasive cardiac imaging and shall help to perform high quality imaging based on a standardised approach.

Exacerbation of Whipple's disease associated with infliximab treatment

A 34-year-old man with chronic inflammatory joint disease and recurrent fever over 6 years was diagnosed as having Still's disease. Treatment with corticosteroids and azathioprine was ineffective. Therefore, infliximab/ methotrexate was started. The patient subsequently developed a wasting disease with rapid weight loss, erythema nodosum, diarrhoea, progressive lymph node enlargement, and a sigmoido-vesical fistula. Histological analysis of several enlarged lymph nodes, the margins of the fistula, and the small bowel established the diagnosis of Whipple's disease (WD). The presence of Tropheryma whipplei (Tw) DNA in the tissues was confirmed by polymerase chain reaction (PCR). Careful re-evaluation of biopsies taken from the ileum and the liver 2 years earlier, which at that time was not judged to be diagnostic for WD, retrospectively showed subtle histological signs of WD and were positive for Tw DNA. In summary, infliximab treatment seems to increase the risk of exacerbation of WD. WD should be carefully ruled out prior to application of tumour necrosis factor-alpha (TNF-alpha) blockade.

[Training program for radiologic technologists for performing chest X-rays at inspiration in uncooperative children]

PURPOSE

A computer program was created to train technologists to perform chest X-rays in crying infants at maximum inspiration.

MATERIALS AND METHODS

Videos of 4 children were used. Using a computer program, the moment of deepest inspiration was determined in the video in the single frame view. During the normal running video, 14 technologists (3 with significant experience, 3 with little experience and 8 with very little experience in pediatric radiography) simulated a chest radiograph by pushing a button. The computer program stopped the video and the period of time to the optimal moment for a chest x-ray was calculated. Every technologist simulated 10 chest X-rays in each of the 4 video clips. The technologists then trained themselves to perform chest X-rays at optimal inspiration like playing a computer game. After training, the test was repeated. Changes were evaluated by t-test for unpaired samples (level of significance p < 0.05).

RESULTS

Although the differences improved in all children, minimal deviation from the optimal moment for taking an X-ray at inspiration occurred in the periodically crying child (0.21 sec before and 0.13 sec after training). In a non-periodically crying infant, the largest differences were shown. The values improved significantly from 0.29 sec to 0.22 sec. The group with substantial experience in pediatric radiology improved significantly from 0.22 sec to 0.15 sec. The group with very little experience in pediatric radiology showed worse results (improvement from 0.29 sec to 0.21 sec).

CONCLUSION

The ability of a technologist to take a chest X-ray at optimal inspiration in a crying child is improved by the tested computer program.

[Spectroscopic imaging of the human liver using 3D CSI: optimization and application in patients with metastatic uvea melanoma]

PURPOSE

(31)P MR spectroscopy (MRS) allows the noninvasive assessment of metabolic alterations in tumors. Due to physical as well as technical limitations, mostly large and single voxels are used. We used a spatially resolved (31)P MRS technique to characterize metabolic abnormalities inside and adjacent to liver metastases of patients with uvea melanoma.

MATERIALS AND METHODS

Optimization of 3D chemical shift imaging (3D CSI) was performed in healthy volunteers (n = 19; voxel size 25 ml). Patients (n = 8) with liver metastases were then examined. Cross sectional imaging was available for all patients.

RESULTS

Compared to healthy volunteers, the PME/PDE ratios of patients with liver metastasis were significantly higher (0.56 +/- 0.30 vs. 0.39 +/- 0.21; p < 0.05). A trend towards increased PME/beta ATP ratios (2.07 +/- 1.83 vs. 1.02 +/- 0.45; p = 0.12) and decreased Pi/PME ratios (0.57 +/- 0.29 vs. 1.06 +/- 0.58; p = 0.06) was also observed. Patients with metastases > or = 5 cm showed significantly higher PME/PDE ratios (0.68 +/- 0.17 vs. 0.45 +/- 0.03; p < 0.05). Liver parenchyma adjacent to metastases did not show any significant changes compared to non-diseased tissue.

CONCLUSION

3D CSI allows the simultaneous analysis of metabolic alterations in diseased as well as in healthy human liver. Metastases show significant metabolic alterations. Thus, (31)P MRS opens new possibilities for therapeutic monitoring.

Oligosaccharide-mediated inhibition of the adhesion of pathogenic Escherichia coli strains to human gut epithelial cells in vitro

The aim of the study was to investigate the ability of pectic oligosaccharides (POS) to inhibit adhesion of three strains of verotoxigenic Escherichia coli, three strains of enteropathogenic E. coli, and one nonclinical strain of Desulfovibrio desulfuricans to human intestinal epithelial cell cultures. Lactobacillus acidophilus and Lactobacillus gasseri were included for comparison. Attachment was determined in the human HT29 cell line by viable count of adherent bacteria. POS in buffer at pH 7.2 were antiadhesive at a dose of 2.5 mg ml(-1), reducing adhesion of enteropathogenic E. coil and verotoxigenic E. coli strains to less than 30% of control values. Concentrations resulting in 50% inhibition ranged from 0.15 to 0.46 mg ml(-1). L. acidophilus was not significantly affected, but adhesion of L. gasseri was reduced to 29% of the control value. POS reduced the adhesion of D. desulfuricans to 0.33% of the control value. POS also had a protective effect against E. coli verocytotoxins VT1 and VT2 at concentrations of 0.01 and 1 microg ml(-1), respectively.

Rapid molecular subtyping by reverse transcription polymerase chain reaction of the neuraminidase gene of avian influenza A viruses

Accurate identification of hemagglutinin (HA) and neuraminidase (NA) subtypes of influenza A viruses is an integral part of monitoring programs targeting avian influenza viruses (AIV). Use of highly sensitive molecular screening methods such as pan influenza-specific real-time RT-PCR (rRT-PCR) yields an increasing number of samples which are positive for AIV RNA but negative by virus isolation and, therefore, require molecular, instead of serological, subtyping. We developed specific RT-PCR assays for all known nine AIV NA subtypes. Validation using 43 reference isolates from different animal species revealed good performance characteristics regarding sensitivity and specificity. On basis of serial tenfold dilution series of reference isolates a benchmark value of C(t) 32 in an M gene-specific rRT-PCR became evident below which all nine NA subtypes were readily detectable by the subtype-specific RT-PCRs. For subtypes N1, N2, N4 and N6 detection was extended to dilutions with C(t) values of up to 35. Diagnostic applicability of the whole set of conventional NA-specific RT-PCRs was evaluated by analysis of 119 different diagnostic samples from wild birds which proved to be positive for AIV by M gene-specific rRT-PCR. Diagnostic sensitivity and specificity was confirmed by sequencing NA amplicons from 41 field isolates generated from this set and by NA inhibition assays. A universal molecular HA/NA subtyping algorithm for rRT-PCR positive avian influenza virus monitoring samples is proposed which may complement classical serological subtyping of influenza A virus isolates.