Biomedical subjects
Publications and source records attributed to S Wetzel.
We present a case of traumatic vertical atlantoaxial dislocation of 16 millimetres with a fatal outcome. We hypothesize that this extremely rare traumatic vertical atlantoaxial dislocation results from insufficiency of the C1/C2 facet capsules after rupture of the tectorial membrane and the alar ligaments.
Normal aging, leukoaraiosis (LA) and vascular disease particularly involve the human frontal lobes. We decided to investigate a population of elderly patients referred for neuroimaging because of progressive minor cognitive deficits but no dementia. They underwent conventional Magnetic resonance imaging (MRI) using axial T1 and T2-weighted imaging as well as coronal FLAIR sequences in addition to the axial diffusion-weighted MRI. MRI allowed us to differentiate patients with leukoaraïosis (LA+) from those without it (LA-) and mapping of the apparent diffusion coefficient (ADC) to investigate local tissular water motion. We observed an increase in the ADC in all investigated patients with increasing age (r=0.326, p=0.002). This increase was observed in both patients groups (LA+ and LA-). In addition, the LA+ group had significant higher ADC values than the LA- group after controlling for age (p<0.0001).
Patients affected by atopic dermatitis tend to develop viral infections. Probably the most feared complication of atopic dermatitis is eczema herpeticum, a disseminated infection with herpes simplex virus. A monomorphic eruption of dome-shaped blisters, pustules and erosions in the eczematous skin lesions along with severe systemic illness leads to the diagnosis. The clinical diagnosis may be confirmed by polymerase chain reaction, viral culture, electron microscopy with negative staining, Tzanck test, immunofluorescence tests or serology. While intravenous acyclovir is still regarded as standard treatment of eczema herpeticum, several recently-developed antiviral drugs provide therapeutic options.
The principal aphid-borne viruses infecting Strawberry (Fragaria spp.) Strawberry crinkle virus (SCV), Strawberry mild yellow edge virus (SMYEV), Strawberry mottle virus (SMoV) and Strawberry vein banding virus (SVBV) can cause serious crop losses. In this paper, a multiplex reverse transcriptase polymerase chain reaction (RT-PCR) method is described for the simultaneous detection of all four viruses in combination with a plant mRNA specific internal control which can be used as an indicator of the effectiveness of the extraction and RT-PCR. In total, 18 strawberry isolates infected naturally were analysed by this method. Every combination of RNA virus was able to be detected and a full complement of all four viruses were found together in three isolates, all taken from wild strawberry (Fragaria chiloensis (L.) Duch.) in Chile. The upper detection limit for the four viruses was at an extract dilution of 1/200. The broad applicability of the RNA specific internal control primers-which produced a PCR fragment of the expected size in 25 of 27 plant species tested-combined with improvements, made in extraction methods described provides potentially a standard method for comparable RT-PCR analyses in a wide variety of plant species.
Diffusion-weighted MR imaging (DWI) is particularly sensitive for the detection of acute stoke. Until recently, DWI was performed with EPI technology. We compared 18 patients with clinical suspicion of acute stroke on a standard 1.5T unit and an open low-field MR scanner. Eighteen patients with 20 lesions of acute stroke were studied retrospectively with DWI and ADC mapping on both systems. The technique used was a rotating fast-spin echo T2 at low-field and an EPI sequence at 1.5T. Both examinations were performed within 24 hours and analyzed by two neuroradiologists. We obtained the same results on DWI sequences on both systems, regarding high intensity lesions on DWI. Interpretation of the ADC maps proved to be difficult on low-field MR near the lateral ventricles (3/18). We experienced the same difficulty of interpretation at low and high field in the cerebellum, in the temporal fossa and in cortex situated near bone, due to susceptibility artifacts. Chronic lesions were better visualized at low than at high field. In our opinion, DWI on a low-field open MR scanner is a good technique to evaluate subacute stroke and was as reliable as when performed on a 1.5T MR system.
BACKGROUND: The effect of rainfall patterns on soil surface CO2 efflux, soil moisture, soil temperature and plant growth was investigated in a grassland ecosystem of northern Ontario, Canada, where climatic change is predicted to introduce new precipitation regimes. Rain shelters were established in a fallow field consisting mainly of Trifolium hybridum L., Trifolium pratense L., and Phleum pratense L. Daytime ambient air temperatures within the shelters increased by an average of 1.9 degrees C similar to predicted future increases in air temperatures for this region. To simulate six precipitation regimes which cover the maximum range to be expected under climate change, a portable irrigation system was designed to modify the frequency of monthly rainfall events with a constant delivery rate of water, while maintaining contemporary average precipitation volumes. Controls consisted of blocks irrigated with frequencies and total monthly precipitation consistent with the 25 year average rainfall for this location. RESULTS: Seasonal soil moisture correlated with soil surface CO2 efflux (R = 0.756, P < 0.001) and above ground plant biomass (R = 0.447, P = 0.029). By reducing irrigation frequency, soil surface CO2 efflux decreased by 80%, P < 0.001, while soil moisture content decreased by 42%, P < 0.001. CONCLUSIONS: Manipulating the number of precipitation events and inter-rainfall intervals, while maintaining monthly rainfall averages impacted CO2 efflux and plant growth. Even with monthly rainfall averages that are similar to contemporary monthly precipitation averages, decreasing the number of monthly rainfall events reduced soil surface CO2 efflux and plant growth through soil moisture deficits. Although many have speculated that climate change will increase ecosystem productivity, our results show that a reduction in the number of monthly rainfall events while maintaining monthly averages will limit carbon dynamics.
There are still several problems surrounding the diagnosis of cerebrospinal fluid leak. Currently the method of choice for cerebrospinal fluid detection is qualitative determination of beta-2-transferrin. Faster and more efficient methods (beta-trace) are under clinical investigation. The major problem is localisation of the site of leakage. Combination of several radiological methods increases the rate of correct diagnosis. In surgery the use of intrathecal sodium-fluorescein improves visualisation of the site of leakage and thus increases the chances of secure and stable closure of the cerebrospinal fluid fistula.
The effects of ethanol on acoustically stimulated blood oxygenation level-dependent (BOLD) signal response in healthy humans was examined with echo planar functional magnetic resonance imaging (fMRI). An acquisition mode minimizing neuronal activation by scanner noise in combination with acoustic excitation by a pulsed 1000-Hz sine tone was used. Paradigms were repeated three times before and after the ingestion of 0.7 g of ethanol/kg(body weight). Linear correlation analyses (r>/=0.40) revealed bilateral BOLD responses in the auditory cortex. Significant voxels covered a cortical volume of approximately 3 ml that was reduced by approximately 40% after ethanol. The BOLD signal change initially reaching approximately 3% was reduced by 12-27%, depending on the definition of the region of interest for signal quantitation. Because ethanol produces vasodilation, the hemodynamic contribution to the BOLD signal change was estimated by modeling the relationship between regional cerebral blood flow (rCBF) and BOLD signal changes. Assuming a baseline flow increase by 10% after ethanol intake, the resulting 'Flow-BOLD-Dependence' (FBD) curve suggested that the ethanol-related BOLD signal reduction was approximately 7-12% greater than the reduction contributed purely by vasodilation. However, simultaneous determination of rCBF and regional cerebral blood volume would be required for an exact quantitation of the neuronally induced BOLD response. Although the FBD model needs empirical validation, its cautious implementation appears to be helpful if fMRI is used in combination with vasoactive drugs.
Unilateral acoustic stimulation produces a functional MRI (fMRI)-blood-oxygenation-level-dependent (BOLD) response mainly in the contralateral auditory cortex. In unilateral deaf patients, the BOLD response is bilateral. We studied a subject with sudden hearing loss after cochlear nerve resection before and repeatedly after surgery. During normal bilateral hearing, contralateral cortical BOLD responses were found. Progressing compensatory reorganization with bilateral representation of unilateral stimulation was detected over a period of approximately 1 year.
Magnetic resonance angiography (MRA) has become an imaging modality which comprises various techniques based on two concepts: methods relying on the natural flow effects, the time-of-flight and phase-contrast technique, either in two- or three-dimensional acquisition mode, and the more recently developed contrast-enhanced (CE) MRA methods. The main indications for evaluation of the supra-aortic vessels are, firstly, the grading of carotid artery stenoses caused by an atherosclerotic process, and secondly, the evaluation of dissections of the cervical arteries because this disease plays an important role as a cause for stroke especially in younger patients. The various MRA techniques in their application to the main pathologies encountered at the supra-aortic vessels are presented, and recent developments in the promising field of CE MRA are discussed.
Explore the source record for details and available documents.
It has been shown in clinical trials that patients with high grade symptomatic carotid stenosis benefit from carotid thromboendarterectomy. Because of the invasiveness and the costs of intra-arterial digital subtraction angiography, the current standard of reference for the grading of carotid stenosis, magnetic resonance angiography, has become a technique of utmost interest for evaluation of the carotid arteries. The time-of-flight and the newly developed contrast-enhanced magnetic resonance angiography techniques are discussed. At present, we recommend computer enhanced magnetic resonance angiography for screening procedures and for the post-operative follow-up. For pre-operative evaluation we still recommend intra-arterial digital subtraction angiography.
Explore the source record for details and available documents.
We investigated the synthesis and accumulation of vegetative storage proteins (VSPs) in poplar plantlets and the homology between poplar seed storage proteins (SSPs) and VSPs. One-dimensional SDS polyacrylamide gel electrophoresis confirmed that both seed and vegetative storage proteins contained two predominant polypeptides of MW 32 and 36 kDa, but the subunit composition of the polypeptides differed. The 32- and 36-kDa polypeptides were highly abundant in basal leaves, stems, and roots of poplar plantlets. The 36-kDa subunit was synthesized in all plantlet tissues examined, but the 32-kDa subunit was not, suggesting that the 36-kDa polypeptide is a precursor of the 32-kDa polypeptide. The 36- and 32-kDa polypeptides of both SSPs and VSPs were glycosylated and both were found to be albumins. In addition, both polypeptides cross-reacted with a VSP antibody. Protein fingerprint patterns generated with two different proteolytic enzymes were identical for the 36-kDa polypeptide isolated from seeds or from stem tissue. Our study provides evidence that poplar SSPs and VSPs exhibit homology, and that expression is neither tissue-specific nor regulated solely by photoperiod.
PURPOSE: To evaluate the reliability of source images and maximum intensity projection images of MR angiography in showing the arterial segments of the circle of Willis. METHODS: In 62 patients, 526 arterial segments of the circle of Willis were determined to be present, partially present, or absent by blinded observers evaluating MR angiographic source images and maximum intensity projection images. Vessel diameter was measured on source images. These results were then compared with the results from intraarterial digital subtraction angiography. RESULTS: MR angiographic maximum intensity projection images had a sensitivity of 87% and a specificity of 88% and MR angiographic source images had a sensitivity of 89% and a specificity of 63% in depicting the presence of a vessel segment. The positive predictive value of an arterial segment with a diameter of at least 1 mm was 99%. CONCLUSION: MR angiography is a sensitive technique for detecting the anatomy of the circle of Willis. Maximum intensity projection images are more specific than source images. An arterial segment with a diameter of at least 1 mm on the source image is almost always present and patent.
Tumoral Calcinosis is a rare clinical entity characterized by the presence of calcified, periarticular masses, as seen on radiographs. A severe case in a patient with chronic renal failure is presented and the complex etiology of this disease is discussed.
The incidence in the literature of dystopic goiter depends on classification of the false endothoracic goiter ("substernal goiter") as dystopic and varies from 2 to 20%. From November 1989 through April 1993 we operated on 530 patients with benign nodular goiters. In 84 patients (15.8%) the operation proved a dystopic goiter. We showed that difficulties in comparing our data with published series were due to misnomers of the dystopic goiter. The dystopic goiter comprises the true endothoracic goiters (alliata vera and isolata vera) as well as the false endothoracic goiters (substernal goiter). The precise classification of the dystopic goiter is crucial to an optimal operative strategy reducing postoperative morbidity.
The use of different viral promoters for the expression of the EBNA1 gene product appears to be a critical step in the regulation of Epstein-Barr virus latent gene expression and may reflect the extent of differentiation of B-cell hosts. Low-passage Burkitt lymphoma cell lines resemble immature B cells in that they express CD10 (CALLA) and do not express B-cell activation antigens. In these cells, transcription from a promoter located in the BamHI F fragment of the viral genome results in the exclusive expression of EBNA1, referred to as the latency I pattern of viral gene expression. In contrast, high-passage Burkitt lymphoma cells and lymphoblastoid cell lines resemble activated B cells in that they do not express CD10 but do express activation antigens such as CD23. In these cells, the use of two promoters located in the BamHI W and C fragments of the viral genome leads to the expression of all six EBNA gene products (latency III). We have found that four human B-cell lines, DB, LBW2, LBW14, and Josh 7, stably express a pattern of B-cell differentiation antigens intermediate between those found in latency I and latency III cell lines and characterized by the coexpression of CD10 and CD23. The pattern of EBNA1 promoter usage in these cell lines was examined to determine whether their intermediate cellular phenotype was reflected in their patterns of viral gene expression. DB, LBW2, and LBW14 utilize both the BamHI F promoter region and BamHI W promoter region to transcribe the EBNA1 gene. This stable pattern of mixed promoter usage for the expression of the EBNA gene products in B cells has not previously been described. In addition, these three B-cell lines expressed lower levels of the viral latent gene product EBNA2 than those typically observed in latency III cells. The lower levels of activation of viral and cellular promoters known to be regulated by EBNA2 also correlated with the reduced levels of EBNA2 expression in these cells. These included the viral LMP1 and LMP2A promoters and the cellular CD23B promoter. The fourth B-cell line, Josh 7, expressed EBNA1 mRNAs derived from both the BamHI W promoter and BamHI C promoter, similar to latency III cells. The intermediate cellular phenotype in Josh 7 cells appeared to be due, in part, to a deficiency in the expression of viral LMP1.(ABSTRACT TRUNCATED AT 400 WORDS)