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Biomedical subjects

S Huber

Publications and source records attributed to S Huber.

At least 55 records · Page 3Linked to original sources

Human myelin basic protein specific T cell lines display differential cytotoxicity against astrocytes, but are consistently cytotoxic against monocytes.

In experimental allergic encephalomyelitis (EAE) myelin basic protein (MBP) specific T cells differ in their encephalitogenic potential. To investigate the functional diversity of human MBP specific T cell lines, we analysed their cytotoxic activity against human astrocytes and monocytes. Five out of 14 MBP specific T cell lines killed astrocytes in the presence of MBP. Nevertheless, all lines lysed blood derived monocytes. T cell lines that lysed astrocytes efficiently in the presence of MBP, recognized peptide aa 80-99/86-105 in context with HLA-DRB5 * 0101, peptide aa 50-69/61-83 in context with HLA-DRB1 * 1501 and peptides aa 139-153, and aa 148-162 in context with HLA-DRB1 * 0101. There was no correlation of MBP-mediated lysis of astrocytes with TCR-Vbeta usage, HLA-restriction and the production of tumor-necrosis-factor-alpha (TNF-alpha), lymphotoxin (LT) and interferon-gamma (IFN-gamma). Different lysis of astrocytes, however, revealed a functional heterogeneity of MBP specific T cells, which was not observed by using monocytes as targets.

Astrocytes↗

CFTR mRNA and its truncated splice variant (TRN-CFTR) are differentially expressed during collecting duct ontogeny.

The collecting duct epithelium originates from the embryonic ureter by branching morphogenesis. Ontogeny-dependent changes of CFTR mRNA expression were assessed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in primary monolayer cultures of rat ureteric buds (UB) and cortical collecting ducts, microdissected at different embryonic and postnatal developmental stages. The amount of wild-type CFTR-specific PCR product in UB declined to 20% of the initial value between embryonic gestational day E15 and postnatal day P1. After birth the CFTR product increased transiently between P1 and P7 by a factor of 10 and decreased towards day P14. PCR products specific for TRN-CFTR, a truncated splice variant, however, were low in early embryonic cells, increased markedly between day E17 and P2, and reached a plateau postnatally. Therefore, mRNA encoding TRN-CFTR does not appear to have a specific embryonic-morphogenetic function. By contrast, such function is suggested for wild-type CFTR mRNA as its abundance was high in early embryonic nephrogenesis, as well as during a postnatal period shortly before branching morphogenesis is completed.

Alternative Splicing↗

[A multicenter study of diagnostic criteria in ultrasound mammography. Statistical pitfalls and ways out of the data jungle].

This paper demonstrates the statistical processing of data from a multicentric study. Seventy-seven patients with a suspicious, solid breast mass were included in a two-center study, using clinical breast examination, mammography, and ultrasound. The assessment was formalized using a uniform evaluation sheet. The prospective results of the examinations were compared with the histologic report. The degree of interdependence between an examiner's diagnosis and diagnostic criteria used was assessed using the kappa statistics. We found that despite standardized assessment, the criteria used for differential diagnosis were at least partially different. The criteria valid for diagnosis at both centers were whether a mass fitted well into the surrounding tissue or led to destruction or architectural distortion, whether it was fixed to the surrounding tissues, as assessed by sonopalpation maneuvers, and whether it borders were sharp or unsharp.

Artifacts↗

[Dynamic assessment of contrast medium enhancement in Doppler ultrasound imaging. Current status].

Findings in previous investigations have indicated that contrast-enhanced colour Doppler can be used to improve the demonstration of characteristic features of neovascularization in malignancies. However, the quantification of the increase in colour Doppler signals after Levovist in the cited study relied only on descriptive criteria defined by the investigator, resulting in a subjective scoring system. A computer-assisted method for quantitative analysis of colour pixel density is a novel approach for objective assessment of colour Doppler signal after contrast media administration. After microbubble contrast medium injection in 47 patients, carcinomas and benign lesions behaved differently regarding degree, onset and duration of Doppler enhancement. However, the high interindividual variability and the temporal variations of the Doppler signal still limit the value of these criteria for prospective diagnosis. Rapid image-acquisition techniques are needed in order to apply the necessary mathematical processing before the contrast kinetics can be used for diagnostic purposes.

Adult↗

[Computer-assisted quantitative evaluation method of color Doppler images in tumor diagnosis].

METHODS: This article reviews methods for objective color Doppler quantification. The principles, limitations and reliability of an objective computer-assisted method of quantitative color Doppler image analysis are described and its role in the assessment of tumor vascularization with regard to differential diagnosis, prognosis and monitoring of therapy effects is evaluated. DISCUSSION: Color Doppler images are quantitatively characterized by the percentage of color pixels in a selected region of interest and the flow velocities corresponding to the encoding colors.

Angiography↗

Colour Doppler sonography in breast tumours: an update.

The aim of our study was to reassess the diagnostic performance of image-based, computer-assisted colour Doppler quantification under routine conditions. We used a computer-assisted protocol that quantitatively characterises a colour Doppler image by the relative amount of colour pixels (colour pixel density, CPD) and the colour hues (numerically expressed by the mean colour value, MCV) in 44 patients with breast carcinoma and 49 patients with benign breast lesions. Studies were carried out over two periods by two examiners, subsequently in charge of breast ultrasound. During the first period, the sensitivity of the MCV was 92 %, the specificity 75 %; the sensitivity of the CPD was 80 %, the specificity 81 %. During the second period, the sensitivity of the MCV was 58 %, the specificity 77 %; the sensitivity of the CPD was 68 %, the specificity 71 %. Despite measures to create uniform examination conditions, the diagnostic performance of this method may decline under routine conditions.

Adult↗

Subplasmalemmal Ca-stores in Paramecium tetraurelia. Identification and characterisation of a sarco(endo)plasmic reticulum-like Ca(2+)-ATPase by phosphoenzyme intermediate formation and its inhibition by caffeine.

Considering increasing interest in calcium stores in protozoa, including parasitic forms, and specifically in subplasmalemmal stores in higher eukaryotes, we have isolated subplasmalemmal calcium stores (alveolar sacs) from the ciliated protozoan, Paramecium tetraurelia. Using antibodies against established sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCAs) we detected in Western blots of subcellular fractions a band of approximately 106 kDa size selectively in alveolar sacs--but not, for example, in plasma membranes--and concomitant restriction of immunofluorecence labelling to the cell cortex of permeabilised cells. These results are the same as with ABs against a peptide derived from a cloned SERCA-like gene from Paramecium [Hauser K., Pavlovic N., Kissmehl R., Plattner H. Molecular characterization of a sarco(endo)plasmic reticulum Ca(2+)-ATPase gene from Paramecium tetraurelia and localisation of its gene product to subplasmalemmal calcium stores. Biochem J 1998; 334: 31-38]. When such isolated alveolar sacs were now tested for phosphoenzyme intermediate (EP) formation, a phosphoprotein of the same apparent molecular mass (approximately 106 kDa) as in blots could be identified in gel autoradiograms. This EP corresponds to that formed in the reaction cycle of different SERCA-types, with dependency on Ca2+ and Mg2+, sensitivity to La3+ or insensitivity towards calmodulin, calmodulin antagonists and vanadate. However, EP formation in alveolar sacs is not inhibited by established SERCA inhibitors (e.g. thapsigargi[ci]n tested up to 100 microM). Surprisingly, caffeine, which is frequently used to mobilise Ca2+ from intracellular stores, strongly inhibits EP formation. In parallel experiments, we did not find any similar effect with sarcoplasmic reticulum isolated from skeletal muscle. We conclude that the approximately 106 kDa protein of alveolar sacs in Paramecium may represent a SERCA-like Ca(2+)-ATPase with some unorthodox features, which might be relevant also for some other protozoan systems. In this case, the established Ca(2+)-mobilizing effect of caffeine may be amplified by inhibiting store refilling.

Animals↗

Analysis of mouse glomerular podocyte mRNA by single-cell reverse transcription-polymerase chain reaction.

Selective investigation of glomerular podocytes is not possible using conventional methods in vivo. Analysis of glomerular epithelium-derived cells in culture yields dubious results because of the rapid dedifferentiation of podocytes. We developed a modification of the polymerase chain reaction (PCR) method previously used to analyze cultured neurons. Podocytes harvested from freshly dissected glomeruli are ideal target cells for this modified, single cell reverse transcription-PCR method to reproducibly identify specific mRNA species from resident intact podocytes in vivo.

Actins↗

Expression of glucose transporters in human peritoneal mesothelial cells.

Glucose containing solutions, the basis of peritoneal dialysis fluids, affect the proliferation and regeneration of peritoneal mesothelial cells (MsC). The aim of this study was to examine mechanisms of glucose transport into MsC, that is, the expression of facilitative glucose transporters (GLUT) and the Na(+)-dependent glucose transporter (SGLT1) in human primary MsC and a transfected MsC line. Since expression of both transporters is differentiation dependent, we investigated the effects of cell differentiation induced by culturing MsC on membranes or by addition of hexamethylene bisacetamide (HMBA; 6 mM), which enhances SGLT1 expression in LLC-PK1 cells. Levels of mRNA for GLUT1 through GLUT4 and SGLT1 were evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR). The presence of the corresponding proteins was examined by Western blotting and localized by immunofluorescence. Active, Na(+)-dependent glucose transport was assessed by alpha-methyl-D-[14C]glucopyranoside (AMG) with and without the SGLT1-specific inhibitor phlorizin and by patch clamp experiments in NaCl or choline-chloride, For Na(+) dependent glucose uptake choline chloride instead of NaCl served as negative control. Facilitative transport was assessed using 2-fluoro-2-deoxy-[14C]-D-glucose (FDG) with and without the inhibitors cytochalasin B or phloretin. Primary and transfected MsC express GLUT1 and GLUT3 mRNA while no transcripts were found for GLUT2 and GLUT4. No SGLT1 transcript was detectable in subconfluent cells. Semiquantitative RT-PCR analysis documented that the addition of the differentiation inducer HMBA to confluent cultures or growth of MsC on membranes for seven days produced a down-regulation of mRNA for GLUT1, no change for GLUT3, and a substantial increase for SGLT1 mRNA. Under these conditions MsC express SGLT1 protein and possess a Na(+)-dependent glucose uptake as assessed by AMG. Phlorizin (1 mM) inhibits AMG uptake by 30 to 40%. In patch clamp experiments the addition of extracellular glucose depolarized the membrane potential only in the presence of sodium. These results indicate that differentiated MsC express GLUT1, GLUT3, and SGLT1. Further characterization of these transport mechanisms and their regulation may help to understand the cellular effects of glucose on MsC in peritoneal dialysis.

Base Sequence↗

Chloride channels ClC-2 and ICln mRNA expression differs in renal epithelial ontogeny.

Development-dependent mRNA expression of the chloride channels ClC-2 and ICln was studied by quantitative reverse transcriptase-polymerase chain reaction in rat ureteric bud and cortical collecting duct primary monolayer cultures. Abundance of ClC-2 mRNA increased in ureteric bud cells between embryonic day 15 (E15) and E17, peaked at postnatal day 3 (P3), and was down-regulated at P7 when morphogenesis is complete, suggesting a specific embryonic function. Expression of ICln mRNA, in contrast, up-regulated continuously with development.

Animals↗

Detection of multiple vascular endothelial growth factor splice isoforms in single glomerular podocytes.

Glomerular podocytes are major determinants of filtration permselectivity in the glomerulus. Although the molecular mechanisms determining the characteristics of the glomerular filtration unit are incompletely understood, vascular endothelial growth factor (VEGF) has been implicated. To analyze this process in situ, we established a method that allows exploration of in vivo mRNA expression of podocytes using single-cell reverse transcriptase-polymerase chain reaction (RT-PCR). Microdissected mouse glomeruli were held in a patch-clamp apparatus, and single podocytes were harvested by aspiration. After lysis, the cells were reverse transcribed, and PCR was performed (45 cycles). The podocyte nature of the material was confirmed by detection of podocyte-specific mRNA (glomerular epithelial protein 1 and Wilms' tumor protein 1). Using specific oligonucleotide primers, VEGF was detected in mRNA obtained from renal cortex, single microdissected glomeruli, cultured murine podocytes, and single podocytes in situ. All cells examined expressed three VEGF isoforms (121, 165, and 189). These differ in their capacity for binding to extracellular matrix and could have different potencies regulating glomerular endothelial permeability. Our approach should allow a semiquantitative, isoform-specific evaluation of VEGF mRNA expression in podocytes during nephrogenesis and in glomerular disease.

Animals↗

Matrix metalloproteinase-9 (gelatinase B) is selectively elevated in CSF during relapses and stable phases of multiple sclerosis.

Matrix metalloproteinases (MMPs) are a family of endopeptidases capable of enzymatic digestion of subendothelial basement membrane and other components of the extracellular matrix. Expression of MMP-2, -3, -7 and -9 is increased around multiple sclerosis plaques and in brain tissue in experimental allergic encephalomyelitis. To measure quantitatively the expression of these MMPs and their endogenous inhibitors (TIMP-1 and -2), we analysed samples from 52 patients with relapsing-remitting and primary progressive multiple sclerosis by ELISA (enzyme-linked immunosorbent assay) and substrate-gel electrophoresis (zymography). MMP-9 was increased over controls in 100% of relapsing-remitting multiple sclerosis cases, with similar levels detected in relapses and clinically stable phases of disease. In primary progressive multiple sclerosis, MMP-9 was increased in 57% of CSF samples, but concentrations were below those encountered in the relapsing-remitting form. The selective upregulation of MMP-9 suggests that T-cells and macrophages invading the brain parenchyma and the CSF space are the predominant source of MMP-9 in multiple sclerosis. TIMPs and other MMPs (MMP-2 and -3) were not upregulated or not detectable (MMP-7) in CSF of patients with relapsing-remitting and primary progressive multiple sclerosis. The sustained increase of MMP-9 in clinically stable multiple sclerosis supports the concept that multiple sclerosis is associated with ongoing proteolysis that may result in progressive tissue damage. The selective inhibition of MMP-9 could be a useful approach for the prevention of disease progression in multiple sclerosis.

Cerebrospinal Fluid↗

Computer assisted retraining of attentional impairments in patients with multiple sclerosis.

OBJECTIVE: To evaluate the efficacy of a computer based retraining of specific impairments of four different attentional domains in patients with multiple sclerosis. METHODS: Twenty two outpatients with multiple sclerosis received consecutively a specific training comprising 12 sessions in each of the two most impaired attention functions. The baseline of attentional deficits, the performance after each training period, and the course of performance in the next nine weeks was assessed by a computerised attention test battery. Additionally, the impact of the training on daily functioning was evaluated with a self rating inventory. RESULTS: Subgroups of patients with multiple sclerosis showing different patterns of attentional impairment could be separated. Significant improvements of performance could almost exclusively be achieved by the specific training programmes. The increase of performance remained stable for at least nine weeks. For quality of life patients reported less attention related problems in everyday situations. CONCLUSIONS: In patients with multiple sclerosis it seems worthwhile to assess attentional functions in detail and to train specific attention impairments selectively.

Activities of Daily Living↗

Effects of a microbubble contrast agent on breast tumors: computer-assisted quantitative assessment with color Doppler US--early experience.

PURPOSE: To evaluate objectively the effects of a microbubble contrast agent on the color Doppler ultrasound (US) examination of breast lesions. MATERIALS AND METHODS: Forty-seven patients aged 23-71 years underwent color Doppler US before and after intravenous injection of a microbubble contrast agent. A 3-minute computer-assisted assessment of the color pixel density (CPD) was used to evaluate objectively the increase in the number of color Doppler US signals, the transit time of the microbubble bolus, and the potential additional differential diagnostic information. RESULTS: Peak CPD at contrast agent-enhanced color Doppler US was 14.3% +/- 8.1 (mean +/- 1 standard deviation) for carcinomas and 9.3% +/- 4.9 for benign lesions (P = .04). The time to peak enhancement was shorter in carcinomas (38 seconds +/- 20) than in benign tumors (71 seconds +/- 48, P = .02). Final CPD was close or equal to baseline values. With the median of 13% for peak CPD as a threshold, the sensitivity for this parameter was 55%, the specificity was 79%, and the accuracy was 62% (P = .04). For a median time to peak of 50 seconds, the sensitivity was 84%, the specificity was 57%, and the accuracy was 76%. CONCLUSION: After microbubble contrast agent injection, carcinomas and benign lesions behave differently in degree, onset, and duration of Doppler US enhancement. High interindividual variability and temporal variations in the Doppler US signal still limit the value of these criteria for prospective diagnosis.

Adult↗

Single cell RT-PCR analysis of ClC-2 mRNA expression in ureteric bud tip.

Embryonic epithelia at the tip of the ureteric bud (UB) face the interspace between epithelial and mesenchymal cells and are fundamentally involved in reciprocal signaling during early nephrogenesis. To characterize their membrane conductive proteins, patch-clamp and single cell RT-PCR techniques were applied to embryonic rat UBs [embryonic day 17 (day E17)] microdissected from the outer cortex. Cells at the UB tip had a high whole cell conductance (14 +/- 2 nS/10 pF, n = 8). The main fractional conductance resembled that of Ca-activated Cl channels in nonepithelial cells, with its time-dependent activation at depolarizing and inactivation at hyperpolarizing voltages. A second Cl-selective current fraction, by contrast, activated slowly during strong hyperpolarization, suggestive of a ClC-2-mediated conductance. To determine the origin of this current, cytoplasm was harvested into the patch pipette, RNA was reverse transcribed, and cDNA encoding the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) housekeeper gene or the ClC-2 Cl channel was amplified by polymerase chain reaction (PCR). GAPDH and ClC-2 PCR products were identified in 23 and 8 (out of a total of 57) single cell cDNA samples, respectively. ClC-2 PCR products with two different lengths were obtained, which might be due to two alternatively spliced ClC-2 mRNA isoforms. This first and combined approach by patch-clamp and single cell RT-PCR techniques to embryonic epithelia indicates that 1) cells at the UB tip express a phenotype remarkably different from that of postembryonic collecting duct principal cells and that 2) ClC-2 is likely to have a key role in early nephrogenesis.

Animals↗

Activated protein C resistance assay performance: improvement by sample dilution with factor V-deficient plasma.

OBJECTIVE: To evaluate a modification of a commercially available reagent kit (COATEST APC Resistance Kit) for functional activated protein C (APC) resistance testing, and to determine the ability of the modified assay to demonstrate APC resistance in patients receiving warfarin. DESIGN: Functional APC resistance testing was performed using both the first-generation COATEST APC Resistance Kit and a modified, or second-generation, version of the COATEST assay that uses predilution of the patient sample with factor V-deficient plasma. Factor V genotyping for APC resistance (FV R506Q) was performed using a well-characterized polymerase chain reaction-restriction fragment length polymorphism method. SETTING: University medical center. PATIENTS: Seventy-three individuals referred for hypercoagulability testing who were not receiving warfarin therapy and 29 patients with a history of venous thrombosis who were receiving warfarin therapy. MAIN OUTCOME MEASURE: Sensitivity and specificity as determined by comparing functional APC resistance to the FV R506Q genotype. RESULTS: In 73 patients referred for hypercoagulability testing, but not receiving warfarin therapy, a sensitivity of 0.86 and a specificity of 0.75 were obtained with the first-generation COATEST assay. In contrast, a sensitivity and specificity of 1.0 were obtained when the second-generation COATEST assay was employed. In 29 patients receiving warfarin, the first-generation assay exhibited a sensitivity and specificity of 0.88 and 0.95, respectively, whereas the sensitivity and specificity for the second-generation assay was 1.0. CONCLUSIONS: Predilution of patient plasma with factor V-deficient plasma results in improved sensitivity and specificity of the COATEST APC Resistance Kit, thus offering a simple modification to enhance APC resistance determination in the routine clinical laboratory setting.

Blood Coagulation Disorders↗

Reciprocal expression of myelin-associated glycoprotein splice variants in the adult human peripheral and central nervous systems.

The L- and S-MAG isoforms differ only at their C-terminus and are believed to be functionally distinct. To obtain information on the relative expression of these alternatively spliced isoforms in humans, we cloned an S-MAG cDNA fragment. The deduced amino-acid sequence of the human S-MAG C-terminus shows fairly conservative substitutions of 4 out of the 10 residues compared to the rodent peptide. Using reverse transcription and a competitive polymerase chain reaction, we show that, in contrast to rodents, the L-MAG splice variant predominates in adult human brain while, like in rodents, S-MAG transcripts are most abundant in peripheral nerve. The results obtained by Western blot analysis and immunohistochemistry are in good agreement with the findings at the mRNA level. Animal experiments may thus be more representative for the role of MAG in human nerve than in brain.

Adult↗