Arterial concentration of 99mTc-sestamibi at rest, during peak exercise and after dipyridamole infusion

Tracers for myocardial perfusion imaging during stress should not only have high cardiac uptake but they should also have a fast blood clearance to prevent myocardial tracer uptake after the ischaemic stimulus. The present study characterize the early phase of the arterial (99m)Tc-sestamibi (MIBI) time-activity curve after venous bolus injection at rest, during peak exercise and after dipyridamole infusion. We included 11 patients undergoing angioplasty for one-vessel disease (rest study) and 20 patients evaluated for the detection of haemodynamic significant coronary stenoses by (99m)Tc-sestamibi single photon emission computed tomography (SPECT) using either bicycle exercise testing (10 patients) or standard dipyridamole testing (10 patients). Arterial blood samples of 1 ml were taken from the left femoral artery (rest study) or the right radial artery (exercise and dipyridamole studies) every 5 s during the first 5 min postinjection. In the exercise and the dipyridamole studies blood sampling were extended to include blood samples every 5 min 5-30 min postinjection. Peak MIBI concentration was lower and decrease in concentration slower after tracer injection during exercise than during dipyridamole stress testing. This may cause an underestimation of perfusion defects during exercise because of MIBI uptake after the ischaemic stimulus. The implications of the study not only refer to the choice of stress modality when using MIBI. This study also underlines the importance of considering early blood clearance in addition to regional myocardial tracerkinetic aspects such as myocardial extraction fraction when new tracers are introduced.     

Hay fever and predictive value of prick test and specific IgE antibodies: A prospective study in children

Little is known from population-based studies in children about the diagnostic values of allergen-specific IgE antibodies (RAST) and skin prick test (SPT) with respect to hay fever. We aimed to determine and compare the diagnostic values of SPT and RAST to aeroallergens with respect to the incidence of hay fever cases in schoolchildren at different cut-off points. A prospective cohort study was performed on 1100 school children (5–7 and 8–10 years). Information on a doctor's diagnosis of hay fever was obtained by questionnaire and allergic sensitization to grass and birch pollen, cat, and Dermatophagoides pteronyssinus were measured using SPT and RAST between September 1992 and July 1993. Thirty-eight children give a history of hay fever (3.5%) in 1992/93 and additionally 37 cases occurred until 1996. Allergic sensitization was present in 17.9% (SPT), 30.2% (RAST) and more frequent in children with a history of hay fever (SPT: OR 11.7, 5.5–24.7; RAST: OR 10.6, 4.3–26.4). This difference was most pronounced for sensitization to pollen allergens. The sensitivity, specificity, positive and negative predictive values (PPV, NPV) for SPT and RAST were 65.6, 83.7, 11.9, 98.6 and 79.3, 71.6, 9.3, 99.0, respectively, with differences for specificity being significant (p < 0.001). Whereas NPV were equally high for SPT (99.2) and RAST (99.3), the incidence of hay fever cases were predicted rather poorly though somewhat better by SPT than by RAST (PPV 16.7 vs. 9.8; p < 0.001) initially. With increasing cut-off point for RAST reactivity, the PPV increased and reached 25.0 at 17.5 kU/l, whereas the NPV decreased to 97.9, which was lower than that of SPT reactivity (p < 0.01). At the cut-off point of 1.5 kU/l almost identical predictive values for SPT and RAST were obtained. SPT and RAST perform better in the negative than positive prediction of hay fever cases in epidemiological studies. Differences in the predictive capabilities depend on the chosen cut-off point for RAST reactivity.     

Inter-laboratory validation of PCR-based detection of Mycobacterium tuberculosis in formalin-fixed, paraffin-embedded tissues

The present study is based on the initiative for quality assurance in pathology of the German Society of Pathology and the Professional Association of German Pathologists. Four panel laboratories with experience and expertise in polymerase chain reaction (PCR) detection of Mycobacterium tuberculosis were selected to establish the prerequisites for continuous external laboratory trials, in particular, by providing pre-tested specimens and evaluation criteria for participating institutes. In the first step, the four panel laboratories performed an internal trial to test their own reliability and reproducibility. Paraffin sections and DNA preparations from 34 tissues (25 clinical specimens and 9 controls) totalling to 66 samples were evaluated by each panel institute according to their own protocols. The methodologies differed and are described in detail. Despite these differences, a high degree of inter-laboratory reliability was achieved. In this report, we summarise our results including the correlation with the histology and provide recommendations for applying PCR-based methodology for the detection of mycobacterial DNA in surgical specimens. Supplementary data are available online at (rubric Forschung). Pre-tested specimens are now available for the external trial and can be ordered from the steering institute via Oligene (). All molecular pathology laboratories are invited to participate in this quality assurance initiative.     

Aminoglycoside-mediated rescue of a disease-causing nonsense mutation in the V2 vasopressin receptor gene in vitro and in vivo

Many human diseases are caused by inactivating mutations in specific G-protein-coupled receptors (GPCRs). In about 10% of these cases, a premature stop codon leads to the generation of a truncated, functionally inactive receptor protein. In this study, we tested the hypothesis that such GPCR mutations can be functionally rescued in vitro and in vivo by treatment with aminoglycoside antibiotics, which are known for their ability to suppress premature termination codons. As a model system, we studied a mutant V2 vasopressin receptor (AVPR2) containing the inactivating E242X nonsense mutation which mimics human X-linked nephrogenic diabetes insipidus (XNDI) when introduced into mice via gene targeting techniques. Studies with cultured mammalian cells expressing the E242X mutant receptor showed that G418 (geneticin) was by far the most potent aminoglycoside antibiotic capable of suppressing the E242X nonsense codon. Strikingly, G418 treatment increased AVP-mediated cAMP responses in cultured kidney collecting duct cells prepared from E242X mutant mice in vitro, and significantly improved the urine-concentrating ability of E242X mutant mice in vivo. This is the first study demonstrating that G418 (aminoglycosides) can ameliorate the clinical symptoms of a disease-causing premature stop codon in a member of the GPCR superfamily.     

PCR detection of human papillomavirus of the mucosa: comparison between MY09/11 and GP5+/6+ primer sets

BACKGROUND AND OBJECTIVES: Human papillomaviruses (HPV) are the causal agent for the development of carcinomas in the cervix uteri and further pathological changes of the skin including mucosa, particularly warts, condylomas and dysplasias. Therefore, we investigated the efficacy of different consensus primers pairs for HPV detection by PCR using brushed samples from the oral cavity in comparison with samples from the cervix uteri. STUDY DESIGN: In the present study, we used two well-established sets of PCR primers in different combinations for the detection of HPV DNA in 106 non-invasive brush biopsy samples of the oral mucosa and 56 samples from the cervix uteri. Direct sequencing of PCR products in all cases determined HPV genotype and specificity. RESULTS: Overall, HPV was detected in 69 of 106 oral mucosa samples. HPV specific amplicons were obtained in 35.8% (N = 38) when using GP5+/6+ primers. The positivity rate was increased to 65.1% in a GP5+/6+ auto-nested PCR approach. In contrast, MY9/11 PCR and nested PCR with MY9/11 outer followed by GP5+/6+ inner primers yielded 2.2% and 16.1%, respectively. In gynaecological samples, PCR results were similar independent of the primer combination used. Thus, DNA quality and DNA content could be additional factors influencing the rate of positivity. CONCLUSION: For oral mucosa samples, auto-nested GP5+/6+ PCR is in our hands the most suitable approach for epidemiological studies because of its high sensitivity, high reliability and reproducibility as well as its relatively simple laboratory procedure.     

Quantitative fiber tracking of lateral and interhemispheric white matter systems in normal aging: relations to timed performance

The integrity of white matter, as measured in vivo with diffusion tensor imaging (DTI), is disrupted in normal aging. A current consensus is that in adults advancing age affects anterior brain regions disproportionately more than posterior regions; however, the mainstay of studies supporting this anterior-posterior gradient is based primarily on measures of the corpus callosum. Using our quantitative fiber tracking approach, we assessed fiber tract integrity of samples of major white matter cortical, subcortical, interhemispheric, and cerebellar systems (11 bilateral and 2 callosal) on DTI data collected at 1.5T magnet strength. Participants were 55 men (age 20-78 years) and 65 women (age 28-81 years), deemed healthy and cognitively intact following interview and behavioral testing. Fiber integrity was measured as orientational diffusion coherence (fractional anisotropy, FA) and magnitude of diffusion, which was quantified separately for longitudinal diffusivity (lambdaL), an index of axonal length or number, and transverse diffusivity (lambdaT), an index of myelin integrity. Aging effects were more evident in diffusivity than FA measures. Men and women, examined separately, showed similar age-related increases in longitudinal and transverse diffusivity in fibers of the internal and external capsules bilaterally and the fornix. FA was lower and diffusivity higher in anterior than posterior fibers of regional paired comparisons (genu versus splenium and frontal versus occipital forceps). Diffusivity with older age was generally greater or FA lower in the superior than inferior fiber systems (longitudinal fasciculi, cingulate bundles), with little to no evidence for age-related degradation in pontine or cerebellar systems. The most striking sex difference emerged for the corpus callosum, for which men showed significant decline in FA and increase in longitudinal and transverse diffusivity in the genu but not splenium. By contrast, in women the age effect was present in both callosal regions, albeit modestly more so in the genu than splenium. Functional meaningfulness of these age-related differences was supported by significant correlations between DTI signs of white matter degradation and poorer performance on cognitive or motor tests. This survey of multiple fiber systems throughout the brain revealed a differential pattern of age's effect on regional FA and diffusivity and suggests mechanisms of functional degradation, attributed at least in part to compromised fiber microstructure affecting myelin and axonal morphology.     

Nonstructural proteins NS2-3 and NS4A of classical swine fever virus: essential features for infectious particle formation

The nonstructural protein NS2-3 of pestiviruses undergoes tightly regulated processing. For bovine viral diarrhea virus it was shown that uncleaved NS2-3 is required for infectious particle formation while cleaved NS3 is essential for genome replication. To further investigate the functions of NS2-3 and NS4A in the pestivirus life cycle, we established T7 RNA polymerase-dependent trans-complementation for p7-NS2-3-4A of classical swine fever virus (CSFV). Expression of NS2-3 and NS4A in trans restored the production of infectious particles from genomes lacking NS2-3 expression. Co-expression of cleaved NS4A was essential. None of the enzymatic activities harbored by NS2-3 were required for infectious particle formation. Importantly, expression of uncleavable NS2-3 together with NS4A rescued infectious particles from a genome lacking NS2, demonstrating that cleaved NS2 per se has no additional essential function. These data indicate that NS2-3 and NS3, each in association with NS4A, have independent functions in the CSFV life cycle.