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Biomedical subjects

M Schmidt

Publications and source records attributed to M Schmidt.

At least 379 records · Page 21Linked to original sources
PubMed1998

Genomic organization and fine mapping of the keratin 2e gene (KRT2E): K2e V1 domain polymorphism and novel mutations in ichthyosis bullosa of Siemens.

We and others have previously shown that ichthyosis bullosa of Siemens, an autosomal dominant disorder characterized by epidermal thickening and blistering, is caused by mutations in the late-differentiation keratin K2e. Here, we have determined the genomic organization and complete sequence of the KRT2E gene, which consists of nine exons, spanning 7634 bp of DNA. The gene was mapped by high-resolution radiation-hybrid mapping to the interval between microsatellite markers D12S368 and CHLC.GATA11B02.1112. Several intragenic polymorphisms were detected, including an 18 bp duplication in exon 1, corresponding to the V1 domain of the K2e polypeptide. Genomic polymerase chain reaction conditions were optimized for all exons, and two novel mutations, N192Y in the 1A domain and E482K in the 2B domain of K2e, were found in ichthyosis bullosa of Siemens families. Mutations were excluded from 50 normal unrelated individuals by restriction analysis. These results emphasize that mutations in K2e underlie ichthyosis bullosa of Siemens and provide a comprehensive mutation detection strategy for ongoing studies of keratinizing disorders.

Chromosome Mapping↗
PubMed1998

Contrast-enhanced three-dimensional magnetic resonance angiography of the splanchnic vasculature before and after caloric stimulation. Original investigation.

RATIONALE AND OBJECTIVES: To develop a comprehensive noninvasive magnetic resonance angiography (MRA) strategy for the morphologic and functional assessment of the splanchnic arteries, based on a combination of breath-held contrast-enhanced 3D MRA and segmented k-space 2D phase-contrast acquisitions acquired before and after caloric stimulation. METHODS: Ten healthy volunteers were examined twice: once in the fasting state (6 hours with no food intake) and a second time following caloric stimulation with a standard 475-kcal meal. Flow in the superior mesenteric artery (SMA) and vein (SMV) was quantitated using a 2D breath-held, segmented k-space phase-contrast (PC) acquisition in a plane perpendicular to the axis of the vessels, while vascular morphology was displayed with a contrast-enhanced 3D MRA acquisition consisting of 44 contiguous 2-mm sections, acquired in apnea (28 seconds). For comparative analysis, the splanchnic vasculature was divided into 11 segments and evaluated on a 2-point scale (cannot exclude pathology, can exclude pathology). RESULTS: Flow volume in the SMA increased from 2.3 ml/min/kg (+/- 0.9 ml/min kg) to 7.3 ml/min kg (+/- 4.7 ml/min kg) following caloric stimulation (P < 0.05). Flow in the SMV exceeded flow in the SMA and increased from 3.4 ml/min/kg (+/- 0.3 ml/min kg) to 9.1 ml/min/kg (+/- 4.8 ml/min/kg) following stimulation. Flow volume of SMV correlated better with SMA flow after stimulation. Caloric stimulation significantly improved visualization of the splanchnic arterial vasculature (P < 0.05). Only 5 of 110 evaluated arterial segments (4.5%) remained inadequately seen to exclude vascular pathology. CONCLUSION: Magnetic resonance imaging offers a comprehensive assessment of the splanchnic arterial vasculature based on 3D display of vessel morphology and analysis of flow function. While the most relevant proximal vessel segments are visible even under fasting conditions, caloric stimulation enhances visualization of small vessels.

Adult↗
PubMed1998

Perforin and granzyme B lytic protein expression during chronic viral and autoimmune hepatitis.

BACKGROUND: Cytotoxic T lymphocytes and Kupffer cells are essential components of the immune response during liver diseases. Recent studies have highlighted the role of cytotoxic T lymphocytes using Fas and its ligand in induced hepatocyte death during acute and chronic hepatitis. METHODS: In the present work, the main purpose was to investigate perforin and granzyme B expression in liver biopsies of patients with chronic hepatitis (10 HBV, 14 HCV and 10 autoimmune hepatitis) using immunohistochemistry. The liver biopsies of two normal individuals were also studied in the same conditions. RESULTS: Few intrahepatic T lymphocytes expressed perforin and granzyme B, while a large number of Kupffer cells were positive for both proteins in all the patients tested. The co-localization of perforin and granzyme B, and CD3 or CD68 antigens was visualized, respectively, in T cells and Kupffer cells, using confocal microscopy. In situ hybridization assays confirmed that perforin and granzyme B mRNAs were present in the liver during chronic hepatitis. The results were similar among the three groups of patients and whatever the activity of the disease. Perforin and granzyme B expression was lacking in liver samples from normal individuals. CONCLUSIONS: These data suggest a minor role for the T cell-mediated perforin/granzyme B death pathway, and a putative role for Kuppfer cells via lytic protein release, during chronic hepatitis.

Adolescent↗
PubMed1998

Characterization of a cis-acting sequence in the Pol region required to transfer human foamy virus vectors.

To identify cis-acting elements in the foamy virus (FV) RNA pregenome, we developed a transient-vector-production system based on cotransfection of indicator gene-bearing vector and gag-pol and env expression plasmids. Two elements which were critical for vector transfer were found and mapped approximately. The first element was located in the RU5 leader and the 5' gag region (approximately up to position 650 of the viral RNA). The second element was located in an approximately 2-kb sequence in the 3' pol region. Although small 5' and 3' deletions, as well as internal deletions of the latter element, were tolerated, both elements were found to be absolutely required for vector transfer. The functional characterization of the pol region-located cis-acting element revealed that it is essential for efficient incorporation or the stability of particle-associated virion RNA. Furthermore, virions derived from a vector lacking this sequence were found to be deficient in the cleavage of the Gag protein by the Pol precursor protease. Our results suggest that during the formation of infectious virions, complex interactions between FV Gag and Pol and the viral RNA take place.

Animals↗
PubMed1998

Intestinal and peritoneal bleeding: detection with an intravascular contrast agent and fast three-dimensional MR imaging--preliminary experience from an experimental study.

PURPOSE: To assess the ability to detect and localize intestinal and peritoneal bleeding with an intravascular contrast agent and fast three-dimensional (3D) magnetic resonance (MR) imaging. MATERIALS AND METHODS: An intravascular contrast agent (NC100150 Injection) was administered into small-bowel specimens at five flow rates; the specimens were imaged with a 3D gradient-echo (GRE) sequence at 1-minute intervals. Radionuclide studies with technetium-99m pertechnetate were performed in the same manner. Subsequently, the MR imaging technique was assessed in vivo. Two intraluminal intestinal and one hepatic bleeding sites were created in an anesthetized pig. Three-dimensional GRE imaging data sets were acquired after intravenous injection of the contrast agent. Imaging findings were confirmed with macroscopic inspection. RESULTS: Contrast material injected at 0.5-2.0 mL/min was detected with both radionuclide and MR imaging after 1 minute. An accumulated volume of 0.2 mL was necessary to demonstrate the bleeding site. In vivo, all bleeding sites were readily detected on MR images. Contrast material accumulated in the intestines and peritoneal space. CONCLUSION: In conjunction with an intravascular contrast agent, 3D MR imaging allows detection and localization of gastrointestinal bleeding. The extent of the bleeding can be determined with repeat data acquisitions.

Animals↗
PubMed1998

Leak measurements in spontaneously breathing premature newborns by using the flow-through technique.

A new method for measuring and correcting air leaks during lung-function testing in infants has been validated in vitro and in vivo by using a flow-through system that measured the inflow and outflow of a face mask. An adjustable leak was quantified by using suction flow to validate the accuracy of leak measurements. To validate the leak correction, the volume of a pump was measured with different air leaks (0-30%). The method developed was tested in 67 infants breathing spontaneously. There was good agreement between measured and simulated leaks (r = 0.998, P < 0.001; 95% limits of agreement were -0.3 and 0.1%, respectively). The volume was generally underestimated because of leaks, and the volume error was up to 94% compared with the maximum error of 5% after leak correction. With continuous leak measurements in vivo, there were <4% actual leaks (median 2.6%), and we did not observe any leaks in >7% of cases. The leak correction improved the accuracy of ventilatory measurements. The monitoring of leaks is helpful for airtight placement of the face mask and for prevention of serious measurement errors caused by leaks.

Algorithms↗
PubMed1998

IgE binding capacity of synthetic and recombinant peptides of the major storage mite (Lepidoglyphus destructor) allergen, Lep d 2.

BACKGROUND: Lepidoglyphus destructor is an important non-pyroglyphid mite species in Europe and a dominant allergen in farming environments. The major allergen of L. destructor, Lep d 2, is a protein of 13.2 kD that is recognised by about 90% of sera RAST positive to this mite species. METHODS: The cDNA of two isoallergens of the Lep d 2 has previously been sequenced and the protein expressed in different protein expression systems. In order to map the B-cell epitopes, the full length protein and the truncated forms of the protein have been expressed in Escherichia coli as glutathione-S-transferase (GST) fusion proteins. Recombinant Lep d 2 fragments and synthetic overlapping 15 mer peptides spanning Lep d 2 were probed with sera from patients allergic to storage mite. RESULTS: The full-length (125 amino acids) GST fusion protein reacted strongly with patient IgE in Western blots and dot blots. Synthetic peptides failed to react with IgE antibodies from mite-allergic patients and the truncated fusion proteins displayed weak IgE-binding capacity. CONCLUSION: We conclude that there are no dominant linear IgE-binding epitopes in Lep d 2. Recombinant or synthetic Lep d 2 fragments may, however, be further evaluated as hypoallergenic candidate molecules for specific immunotherapy.

Allergens↗
PubMed1998

Cyclophosphamide pulse therapy in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive disorder with poor prognosis. Response to treatment is infrequent and the use of immunosuppressive agents other than corticosteroids is the subject of ongoing discussion because of uncertain efficacy and side-effects. To determine the efficacy and safety of cyclophosphamide pulse therapy in IPF, this study retrospectively analysed 18 patients with progressive IPF who were treated with intermittent i.v. cyclophosphamide (1-13 g x month(-1)) and additional oral prednisolone for 1 yr. Static lung volumes, arterial oxygen tension (Pa,O2) at rest, clinical symptoms and potential treatment-related side-effects were recorded. Cyclophosphamide had to be stopped in one patient, owing to repeated pulmonary infection; 11 patients were responders (five improving, six stabilizing) and six patients deteriorated. The change in vital capacity (VC) of responders was +6.7+/-18.0% (mean +/-SD), compared with -20.6+/-18.2% in nonresponders (p=0.008). Pa,O2 remained constant in responders (+0.13+/-0.88 kPa (+1.0+/-6.6 mmHg)), while it decreased in nonresponders (-2.08+/-1.92 kPa (-15.6+/-14.4 mmHg, p=0.008)). Additional prednisolone was reduced by 19.1+/-13.4 mg in responders, compared with 6.7+/-16.3 mg in nonresponders (p=0.02). VC at initiation of therapy was higher in responders (60.2+/-10.2 versus 40.3+/-12.9% predicted; p=0.004). No side-effects occurred, other than respiratory tract infection. These data demonstrate that intravenous cyclophosphamide pulse therapy may be a favourable regimen for certain patients with progressive idiopathic pulmonary fibrosis. Patients with a vital capacity of more than 50% predicted and a shorter duration of disease may benefit most.

Administration, Oral↗
PubMed1998

Ongoing somatic mutations and clonal expansions after cure of Helicobacter pylori infection in gastric mucosa-associated lymphoid tissue B-cell lymphoma.

PURPOSE: Although most patients with primary gastric low-grade mucosa-associated lymphoid tissue (MALT) B-cell lymphoma experience complete endoscopic and histologic remission after the cure of Helicobacter pylori infection, in many patients, the polymerase chain reaction (PCR) still detects monoclonal B cells in the gastric mucosa. The present study asked whether the lymphoma immunoglobulin VH (IgVH) sequences remained stable in patients with gastric MALT lymphoma after H pylori eradication. PATIENTS AND METHODS: Eight patients with stage EI disease treated with H pylori eradication were analyzed before and at different time points after the cure of the infection. After the amplification of IgVH genes from DNA extracted from gastric biopsy specimens, monoclonal PCR products were cloned and multiple clones (43 to 105) were sequenced per patient. RESULTS: Mutations were detected in all lymphoma VH sequences, which suggested germinal center or postgerminal center origin of the lymphoma B cells. In five of the eight patients, clonal heterogeneity was observed at diagnosis or during follow-up. Genealogical analysis of shared and unshared mutations showed that the process of somatic mutations was ongoing after H pylori eradication in four of the five patients who showed clonal instability. Ongoing mutations were observed in three of the four patients who completely responded to H pylori eradication, but in only one of the four patients who did not respond or who partially responded. CONCLUSION: In low-grade gastric MALT lymphomas, an ongoing process of somatic hypermutation and antigen selection can be detected after the therapeutic removal of the underlying stimulus H pylori. These data point to the relevance of yet unknown antigens that drive this disease. In addition, they challenge the view that these lymphomas may be cured solely by the eradication of H pylori.

Adult↗
PubMed1998

Progesterone inhibits glucocorticoid-dependent aromatase induction in human adipose fibroblasts.

In fibroblasts derived from human adipose tissue, aromatase induction is observed after exposure to 1 microM cortisol in the presence of serum or platelet-derived growth factor (PDGF). Progesterone suppresses this induction in a dose-dependent manner, 10 microM resulting in complete inhibition. A reduced cortisol concentration (0.1 microM) concomitantly reduces the progesterone concentration required for effective inhibition (10-100 nM). This effect of progesterone is specific, as neither the release of cellular enzymes nor aromatase induction by dibutyryl-cAMP, which acts independently from cortisol, are affected. However, the inhibitory effect of progesterone requires its presence throughout the induction period. Kinetic studies in intact cells reveal a reduced number of aromatase active sites upon progesterone treatment, whereas progesterone at near-physiological concentration (100 nM) does not inhibit aromatase activity in isolated microsomes. Semi-quantitative reverse transcriptase PCR analysis shows reduced amounts of aromatase mRNA in progesterone-treated cells, indicating specific inhibition of the glucocorticoid-dependent pathway of aromatase induction. The inhibitory effect of progesterone is not blocked by the anti-progestin ZK114043, excluding action via progesterone receptors and indicating competition for the glucocorticoid receptor. Progesterone must be considered a potential physiological inhibitor of glucocorticoid-dependent aromatase induction in adipose tissue. It is proposed that it is a suppressor of aromatase induction in adipose tissue in premenopausal women.

Adipocytes↗
PubMed1998

Radiographic and clinical responses to periodontal therapy.

Mechanical periodontal therapy is widely used for a variety of periodontal conditions. While the clinical efficacy of this treatment has been validated, the radiographic response has not been studied in depth. The purpose of the present study was to examine the clinical and radiographic response to mechanical periodontal therapy, and assess the factors associated with these changes. One hundred and eight patients, with established periodontitis, received oral hygiene instruction and mechanical periodontal therapy for a period of 4 to 5 weeks. Scheduled maintenance visits were performed at 3, 6, 9, and 15 months. Probing depth (PD) and attachment level (AL) measurements were performed at baseline, and at 3 and 15 months. Intraoral radiographs were taken at baseline and 12 to 15 months postsurgery using a Rinn alignment system. Alveolar crestal height (ACH) measurements were performed on a pair of digitized images of the previously taken radiographs. An overall mean of patients' changes for PD, AL, and ACH was initially computed. Active sites (gainers and losers) were determined using a threshold method, and expressed as patient's percentage of active sites (number of active sites of the total sites measured in each patient). Mean overall probing reduction and AL gain was 0.5 mm and 0.44 mm, respectively. Of all sites measured, 16.6% exhibited AL gain, while only 6.2% of all sites exhibited AL loss. Mean overall change in ACH was -0.07 mm, of which 11.8% of all sites exhibited ACH gain, while 15.1% exhibited loss beyond the threshold. Non-smokers presented no change in bone loss, while smokers continued to lose bone at an annual rate of 0.17 mm, despite treatment (P <0.005). Likewise, the average percent of sites per patients showing attachment gain beyond the threshold were much greater in non-smokers (13.9%) compared to 9.0% in smokers (P <0.01). Mean probing reduction was 50% greater among non-smokers (0.6 mm) when compared to smokers (0.4 mm), which was also statistically significant (P <0.05). A positive and significant correlation was established between the percentage of sites with AL gain and sites with ACH gain (Rho =0.40; P=0.0001). It is suggested that monitoring sites for AL and ACH gain expressed as changes beyond a selective threshold is an important outcome variable in treatment studies.

Adult↗
PubMed1998

Diagnostic impact of four postprocessing techniques in evaluating contrast-enhanced three-dimensional MR angiography.

OBJECTIVE: The purpose of this study was to determine the added diagnostic value of various three-dimensional (3D) data viewing techniques when analyzing contrast-enhanced 3D MR angiography. MATERIALS AND METHODS: Twenty patients (mean age, 62 years) with symptomatic peripheral vascular disease were assessed with breath-hold, contrast-enhanced 3D MR angiography and catheter angiography, which served as the standard of reference. After an initial interpretation of the 3D MR angiographic data sets based only on standardized maximum intensity projections (MIP), the diagnostic gain of the stepwise addition of interactive multiplanar reformations, shaded-surface displays (SSD), and virtual intraarterial endoscopy (VIE) images was calculated. Time required for each step of postprocessing was measured. RESULTS: Pathologic changes were revealed by catheter angiography in 60 vascular segments (50 severe stenoses, seven aneurysms, and three occlusions). The average postprocessing times were MIP, 8 min (range, 5-12 min); multiplanar reformations, 9 min (range, 3-11 min); SSD, 15 min (range, 8-25 min); and VIE, 40 min (range, 18-63 min). Addition of multiplanar reformations to MIPs resulted in the greatest gain of diagnostic accuracy, from 92% to 96%, and diagnostic confidence. When analysis was based on all four techniques, receiver operating characteristic curve analysis revealed only minimal improvements in diagnostic confidence, whereas diagnostic accuracy remained unchanged at 96%. CONCLUSION: Accurate and time-effective analysis of contrast-enhanced 3D MR angiography should be based on MIP algorithms and multiplanar reformations. Additional evaluation with VIE or SSD techniques is time-consuming and provides little diagnostic gain.

Adult↗
PubMed1998

The in vivo activity of vascular endothelial growth factor isoforms in the avian embryo.

The activity of the different isoforms of quail vascular endothelial growth factor (VEGF; 122, 146, 166 and 190 amino acids) were quantitatively examined in vivo by overexpression in the chicken embryo using the retroviral expression vector RCAS. All isoforms were potent inducers of vascularization and permeability. A linear relationship between expression of their mRNA and induction of vascularization and permeability was observed for all isoforms. Pattern formation and morphogenesis was otherwise not altered. Overexpression of qVEGF122 and 146 in the eye of chicken embryos did not induce vascularization of either the cornea or retina-which are avascular tissues in birds. We conclude that all isoforms of VEGF are potent inducers of angiogenesis dependent on a permissive environment.

Amino Acid Sequence↗