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E Engel

Publications and source records attributed to E Engel.

At least 55 records · Page 3Linked to original sources
PubMed1997

In vivo color stability of resin-veneered telescopic dentures: a double blind pilot study.

STATEMENT OF PROBLEM: Discoloration is a major disadvantage of resin veneers on telescopic dentures. In vitro color measurements with large and flat samples of resin veneer composites have been published, but no in vivo data are available. PURPOSE: This study describes the discoloration of resin veneers in vivo by use of spectrophotometry and the L*a*b* system of the Commission Internationale de L'Eclairage (CIE). METHODS: In a clinical evaluation of this technique, two composite veneer materials were compared in 18 patients. RESULTS: Both brands discolored significantly after 1 year. While L* and a* were not changed significantly, b* and the total color difference delta E increased by approximately 2 units each year. No statistically significant differences were found between the materials.

Color↗
PubMed1997

Biochemical characterization and histochemical localization of nitric oxide synthase in the nervous system of the snail, Helix pomatia.

Nitric oxide synthase (NOS) in the snail Helix pomatia was characterized by biochemical and molecular biological techniques and localized by histochemical methods. Central ganglia contained particulate paraformaldehyde-sensitive and cytosolic paraformaldehyde-insensitive NADPH-diaphorase. The cytosolic NADPH-diaphorase activity coeluted with NOS activity. The activity of NOS was dependent on Ca2+ and NADPH and was inhibited by N(G)-nitro-L-arginine (L-NNA). Proteins purified by 2',5'-ADP affinity chromatography were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and migrated at 150, 60, 40, and 30 kDa. An antibody to mammalian NOS exclusively labeled the 60-kDa protein. Characterization of the cDNA of the corresponding 60-kDa NOS-immunoreactive protein revealed no sequence homology with any known NOS isoform. The recombinant protein exhibited Ca2+- and NADPH-dependent NOS activity, which was partially inhibited by EGTA and L-NNA. Histochemistry showed NADPH-diaphorase activity in discrete regions of the central and peripheral nervous system. About 60% of the NADPH-diaphorase-positive neurons colocalize with immunoreactive material detected by antibodies to mammalian NOS. Comparison of organs showed the highest NADPH-diaphorase activity in the nervous system, whereas moderate activity was present in muscle tissue, digestive tract, and gonads. Our study suggests the presence of NOS and a putative NOS-associated/regulating protein in mollusk nervous tissue.

Animals↗
PubMed1997

Human spasmolytic polypeptide decreases proton permeation through gastric mucus in vivo and in vitro.

Exogenously administered trefoil peptides are gastroprotective in rat injury models. We hypothesized that trefoil-associated gastroprotection occurred by decreasing the rate of proton permeation through mucus. Gastric surface cell intracellular pH and mucus gel thickness were measured by in vivo microscopy. Gastric mucosal blood flow was measured by laser-Doppler flowmetry. The effect of human spasmolytic peptide (hSP) on H+ diffusion through 5% purified porcine mucin was measured using an Ussing chamber. Buffering action of mucin was measured by titration. In vivo, gastric mucosal blood flow and mucus gel thickness were not affected by any of the treatments. Topical hSP, but not intravenous hSP, decreased initial acidification rate and elevated the intracellular pH of gastric surface cells during luminal acid challenge. In in vitro studies, hSP dose dependently decreased the diffusion coefficient of H+ through 5% porcine mucin solution. hSP had no significant effect on the buffering action of mucin solutions. These data support our hypothesis that hSP interacts with gastric mucin in a manner that inhibits proton permeation through the mucus gel layer.

Animals↗
PubMed1997

Uniparental disomy (UPD). Genomic imprinting and a case for new genetics (prenatal and clinical implications: the "Likon" concept).

Uniparental disomy (UPD) is often the result of an aneuploid event masquerading under the features of diploidy. As such, it may never be recognized, being at 2 opposite phenotypic poles, harmless to the bearer, or, if harmful, eventually responsible for uncharacteristic although perhaps serious conditions. UPD can also be associated with problems such as recessiveness or mosaicism. This article considers the chances of unmasking UPD, in the course of CVS or AC prenatal diagnosis, by reviewing the main cytogenetic signals and major familial or personal antecedents raising its suspicion. Once suspected, the lead toward UPD may or may not be followed through appropriate molecular studies. UPD for either maternal or paternal chromosomes 13, 21 and 22 may not have consistent, common deleterious effects, while other identified UPD's are too rare to call. Unconditionally, main, consistent or near consistent damages to the phenotype have been traced to specific chromosome pairs such as 15 mat (Prader-Willi syndrome), 15 pat (Angelman syndrome), 11 pat (Wiedemann-Beck with syndrome), 14 mat and pat (multiple cogenital and developmental anomalies [MCDA]-several rather constant) and 7 mat (Russel-Silver [RS] and Growth-failure [GF]). The above problems all stem from an alteration of the normal, developmentally important genomic imprinting processes and most of them may recognize several etiopathogenic paths, other than UPD, none of which abides by straight Mendelian rules. In this very area, therefore, a new, non-traditional type of inheritance is confronting genetic counselling. In this paper, for want of appropriate semantic language, the neologism "likon" (or "laïkon") is coined to make reference to the hemizygously expressed sequences of the genomic parts imprinted in the somatic tissues. Broadening the definition, the word is then applied to the 4 possible epigenotypes of imprinted domains, which depend on the parental sex-of-origin: germinally "resting" (R), or "acting" (A), to be made somatically silent, that is to say "unexpressed" (U), or transcribed and "expressed" (E), thus abbreviated as EA, ER, UA and UR. Entire pedigrees may then be analyzed accordingly in health and in disease. Examples are presented herewith.

Aneuploidy↗
PubMed1996

Chronic recurrent multifocal osteomyelitis: an evolving clinical and radiological spectrum.

OBJECTIVE: To describe unusual clinical and radiological features in patients with chronic recurrent multifocal osteomyelitis (CRMO). DESIGN AND SUBJECTS: Based on radiographic and microscopic findings, three patients were prospectively diagnosed as having chronic recurrent multifocal osteomyelitis (CRMO). They form the basis of this report because of either the unusualness of the clinical presentation, hitherto undescribed associated diseases or the unusual age of presentation and sites of lesions. RESULTS: One patient developed pyoderma gangrenosum at the site of one of the skeletal lesions and then went on to develop ulcerative proctitis. A second patient presented with a soft tissue mass, which on MRI mimicked a sarcoma. The final patient presented with lesions in the wrist and phalanges of the toes at the unusual age of 38. None of the patients was treated with steroids or antibiotics for the skeletal lesions. Steroids were administered to one patient for treatment of pyoderma gangrenosum. CONCLUSIONS: The pattern and distribution of skeletal lesions in CRMO are well recognized in the pediatric age group. The unusual clinical and/or radiological features discussed herein suggests that this is a disease that continues to evolve with a broader spectrum of features than recognized.

Adult↗
PubMed1995

Isoforms of Bet v 1, the major birch pollen allergen, analyzed by liquid chromatography, mass spectrometry, and cDNA cloning.

Bet v 1, the major allergen of birch pollen, displays a considerable degree of heterogeneity. Several charge variants have been detected by two-dimensional IgE immunoblots and isoelectric focusing techniques. This heterogeneity has been attributed to glycosylation (or other post-translational modifications) or to isogenes coding for Bet v 1 isoforms and/or allelic variants. However, until now, only limited structural data for Bet v 1 have been published. Recently, we described the expression, purification, and immunological properties of recombinant Bet v 1 (rBet v 1) produced in Escherichia coli as a non-fusion protein (Ferreira, F. D., Hoffmann-Sommergruber, K., Breiteneder, H., Pettenburger, K., Ebner, C., Sommergruber, W., Steiner, R., Bohle, B., Sperr, W. R., Valent, P., Kungl, A. J., Breitenbach, M., Kraft, D., and Scheiner, O. (1993) J. Biol. Chem. 268, 19574-19580). Here, we present a more detailed structural characterization of Bet v 1 by both cDNA cloning and mass spectrometry. Thirteen different cDNA clones coding for Bet v 1 isoforms were obtained by polymerase chain reaction amplification of birch pollen cDNA with a sequence-specific 5'-terminal primer and a nonspecific 3'-terminal primer or by immunological screening of a birch pollen cDNA library. These isoforms are referred to as Bet v 1b to Bet v 1n, whereas the previously isolated Bet v 1 cDNA (Breiteneder, H., Pettenburger, K., Bito, A., Valenta, R., Kraft, D., Rumpold, H., Scheiner, O., and Breitenbach, M. (1989) EMBO J. 8, 1935-1938) is now referred to as Bet v 1a. High performance liquid chromatography and plasma desorption mass spectrometry of proteolytic fragments of purified natural Bet v 1 (nBet v 1) and rBet v 1a were used to (i) confirm the primary structure of all Bet v 1 isoforms and (ii) to investigate any possible postsynthetic modifications on rBet v 1a or on the natural mixture of isoallergens obtained from birch pollen. Except for the cleavage of initiating methionine, no postsynthetic modifications were found in either nBet v 1 or rBet v 1a.

Allergens↗
PubMed1995

Uniparental disomy in humans: development of an imprinting map and its implications for prenatal diagnosis.

Uniparental disomy (UPD) in humans is caused primarily by meiotic nondisjunction events, followed by trisomy or monosomy 'rescue'. The majority of cases appear to be associated with advanced maternal age, and may be initially detected as mosaic trisomies during routine prenatal diagnosis by chorionic villus sampling or amniocentesis. In addition, structural abnormalities including Robertsonian translocations, reciprocal translocations and supernumerary marker chromosomes appear to be associated with an increased risk of UPD. Predicting the phenotypic effects of UPD is complex, as three independent factors are involved: (i) effects of trisomy on the placenta or the fetus; (ii) autosomal recessive disease due to reduction to homozygosity; and (iii) imprinted gene effects for some chromosomes. To date, UPD in humans has been reported for 25 of the 47 possible uniparental types. Imprinting effects have been established with certainty for four human chromosomes that have homology to mouse chromosomes which have been shown to have significant phenotypic effects in uniparental animals. A normal phenotype has been reported for 14 other UPD types. Thus, collection of data on UPD cases in humans is providing an imprinting map analogous to the experimentally derived imprinting map in mouse. This human imprinting map has important clinical implications, particularly in the area of prenatal diagnosis.

Animals↗
PubMed1995

Palliative therapy of melanoma patients with fotemustine. Inverse relationship between tumour load and treatment effectiveness. A multicentre phase II trial of the EORTC-Melanoma Cooperative Group (MCG).

Fotemustine (FM) is a new chloronitrosurea (CNU), chemically characterized by the graft of an aminophosphonic acid on the CNU radical, which makes it highly lipophilic. Following single-institution phase I and II studies with remarkably high response rates of some 40%, including brain metastases of 25% and more, the EORTC-MCG started a multicentre phase II trial to confirm these results according to EORTC guidelines. Treatment consisted of an induction cycle of FM (100 mg/m2 on days 1 + 8 + 15), followed by maintenance courses (q3w). Fifty-four patients were entered by 11 institutions. General interest in this promising new agent, however, led clinicians of six additional institutions to join the EORTC trial and 90 more patients were included in only 4 months. This rapidly rising accrual rate became inversely related to the physicians' adherence to the eligibility criteria: palliation of symptoms rather than clinical research was the dominant reason to start treatment. Clinical characteristics and results in the eligible vs non-eligible patient group (in parentheses) were as follows: male/female 29/26 (68/65), mean age 54 years (53), ECOG-PS 0-1 (0-4), CR 2 (0), PR 10 (2), NC 17 (5) and for brain metastases: PR 4 (1), NC 2 (1), for an ORR of 12% (5%). Median duration of response was 6 months (range 4-16). The clinically relevant toxicity was limited to the haematopoiesis with delayed platelet nadirs (30% grade III+IV), granulocyte (25% grade III + IV) and the gastrointestinal tract: nausea and vomiting (26% grade II, 18% III, 1% IV). This study confirms that FM is active in melanoma including brain metastases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Bicarbonate diffusion through mucus.

The mucus layer overlying duodenal epithelium maintains a pH gradient against high luminal acid concentrations. Despite these adverse conditions, epithelial surface pH remains close to neutrality. The exact nature of the gradient-forming barrier remains unknown. The barrier consists of mucus into which HCO3- is secreted. Quantification of the ability of HCO3- to establish and maintain the gradient depends on accurate measurement of this ion's diffusion coefficient through mucus. We describe new experimental and mathematical methods for diffusion measurement and report diffusion coefficients for HCO3- diffusion through saline, 5% mucin solutions, and rat duodenal mucus. The diffusion coefficients were 20.2 +/- 0.10, 3.02 +/- 0.31, and 1.81 +/- 0.12 x 10(-6) cm2/s, respectively. Modeling of the mucobicarbonate layer with this latter value suggests that for conditions of high luminal acid strength the neutralization of acid by HCO3- occurs just above the epithelial surface. Under these conditions the model predicts that fluid convection toward the lumen could be important in maintaining the pH gradient. In support of this hypothesis we were able to demonstrate a net luminal fluid flux of 5 microliters.min-1.cm-2 after perfusion of 0.15 N HCl in the rat duodenum.

Animals↗
PubMed1995

Barrier function of the gastric mucus gel.

The gastric epithelium is covered by a continuous layer of secreted mucus and bicarbonate. The function of this mucobicarbonate layer in terms of protecting the epithelial cells from luminal acid is controversial. Several studies conducted in vitro have shown that gastric mucus can slow proton diffusion and can enable the formation of a pH gradient across the mucobicarbonate layer. In our laboratory, simultaneous measurements of intracellular pH and the thickness of the mucus gel overlying gastric surface cells in vivo indicated that surface cell acidification rates and mucus gel thickness were inversely related. This suggests that the gastric mucobicarbonate layer delays proton permeation into gastric surface cells, enabling secreted bicarbonate to neutralize luminal acid. Several theoretical models, including the effects of mucus and bicarbonate secretion, convection, stirring, and lipids are offered as a possible explanation for the experimental observations. Lipid content and additional unstirred layers outside of the mucus gel are offered as possible explanations for the experimental observations. On the basis of the available data and theoretical considerations, we can conclude that all of these factors probably interact in an integrated manner to protect the gastric epithelial cells from damage due to luminal acid.

Animals↗
PubMed1995

[Uniparental disomy: a review of causes and clinical sequelae].

1) Uniparental disomy (UPD) results from the exceptional derivation of a pair of the offspring chromosome from one parent only and has been documented thus far for chromosomes 2, 4, 5, 6, 7, 11, 13, 14, 15, 20, 21, 22 both X's and the XY pair. Its consequences on the phenotype may result from three potentially harmful effects, namely isodisomy, interference with genomic imprinting and, occasionally the vestigial aneuploidy from which UPD may have originated. 2) In isodisomy, the uniparental pair is partially or entirely homozygous, through the duplication of a same chromosomal DNA template, thus bringing about an increased risk of recessive disorders. As a result, conditions such as cystic fibrosis, a type of osteogenesis imperfecta, thalassemia alpha or beta, retinoblastoma, rod monochromacy, etc., have now been reported. 3) Duplication of both homologues of a parental pair in a diploid genome is called heterodisomy. Both iso- and heterodisomy may also cause disruption of the genomic imprints normally modifying the differential expression of some maternal and paternal genes or gene sequences needed for eugenic growth and development, in the course of normal biparental inheritance. Such a disturbance can be one of the causes of congenital clinical entities as well defined as Angelman, Prader-Willi or Beckwith-Wiedemann syndromes and some new syndromes, for instance for UPD 7 mat, UPD 14 mat and, probably also 14 pat. 4) All in all, UPD can cause morbidity or lethality by altering imprinting processes, mimicking certain deletions or duplications, generating recessive disorders or prompting malignant tumor development. 5) In the clinical field, UPD occasionally upsets some mendelian tenets of traditional inheritance, and raises, the question of the evolutional role plaid by genomic imprinting (GI). An hypothetical opinion is that one of GI potential side effects is a biased intergenerational preferential display or skip of parental features. This could be so because some of the inherited genes or gene domains only gain maternal or paternal expression in the offspring, as a function of their parental imprint.

Chromosome Aberrations↗