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Biomedical subjects

S Mundlos

Publications and source records attributed to S Mundlos.

65 records · Page 4Linked to original sources
PubMed1991

Distribution of cartilage proteoglycan (aggrecan) core protein and link protein gene expression during human skeletal development.

The distribution of cartilage proteoglycan core protein (aggrecan) and cartilage proteoglycan link protein was investigated by in situ hybridization during different stages of human skeletal development. Aggrecan and link protein expression were confined to chondrocytes of the developing skeleton and other cartilaginous structures. Distribution and intensity of the signal was identical with aggrecan as compared to link protein probes. Parallel to the calcification of cartilaginous matrix, chondrocytes of this area lost the expression of aggrecan and link protein specific mRNA and stayed negative throughout the following stages of skeletal development. Highest expression was found in the lower proliferative and upper hypertrophic zone whereas the resting zone showed less expression. Aggrecan gene expression was additionally investigated in iliac crest biopsies of 3 patients with pseudoachondroplasia and compared to age-matched controls. Distribution and intensity of staining revealed no abnormalities. Thus, the phenotypic changes during chondrocyte maturation are accompanied by distinct changes in aggrecan and link protein gene expression. This pattern was maintained in the growth plate of patients with pseudoachondroplasia.

Aggrecans↗
PubMed1991

Genetic disorders of connective tissues.

Due to the growing knowledge of structure and function of extracellular matrix proteins, congenital abnormalities of connective tissues are identified or suspected in an increasing number of clinical disorders. In osteogenesis imperfecta and two subtypes of Ehlers-Danlos syndrome, the affected matrix proteins were identified and mutations in the corresponding genes (procollagen type I and type III, respectively) could be demonstrated. Some forms of chondrodysplasia were shown to be associated with mutations in the gene encoding for the cartilage-specific collagen (type II). In part, the clinical phenotype is determined by the tissue-specific distribution of these collagens. However, the correlation of location and character of the mutation to the phenotype is only just emerging and remains unpredictable in most cases. Recent findings suggest the mutations in matrix genes may be causative not only for rare pediatric diseases but also for more common disorders such as osteoarthritis or aortic aneurysms.

Collagen↗
PubMed1991

[Effect of pellet size of a pancreas enzyme preparation on duodenal lipolytic activity].

Release of lipolytic activity from enteric coated microspheres occurs after emptying from the stomach. Gastric emptying of the spheres is strongly influenced by their size, as several studies indicate. In the present study 10 patients with exocrine pancreatic insufficiency received two types of enzyme substitution (Kreon) and were investigated using the cholesterol-14C-octanoate breath test. Preparation A with microspheres of the size 1.0-1.2 mm and B with the size 1.8-2.0 mm. All patients showed an obvious delay in intraduodenal lipolytic activity using the 1.8-2.0 mm preparation. In 3 out of 10 patients lipolytic activity increased much more early using the 1.0-1.2 mm preparation, in the other patients differences were not as clear. The effectiveness of enzyme substitution was 25% greater for the 1.0-1.2 mm preparation for the time of testing (mean values, p less than 0.10).

Adult↗
PubMed1990

A neonatally tolerant mouse model to assess pathogenicity of human autoantibodies.

Since certain autoimmune diseases, including myasthenia gravis and pemphigus vulgaris can be reproduced in mice by passive transfer of immunoglobulins from affected patients, we assessed whether this procedure could be optimised. Repeated injections of human IgG into mice during pregnancy induced tolerance to human IgG in the litter, and this persisted for at least 9 months. We show that three different human autoantibodies, to mitochondria, centromere and collagen, were retained in the serum of neonatally tolerized mice, but pathogenic effects of these particular autoantibodies were not demonstrable over the four week time scale of our experiments. However, our model should be applicable to studies on human autoantibodies which might damage the appropriate tissue in a heterologous species.

Animals↗
PubMed1990

Distribution of type I and type II collagen gene expression during the development of human long bones.

The temporal and spatial gene expression of collagen type I and type II during the development of the human long bones was studied by the technique of in situ hybridization covering the period from the cartilagenous bone anlage to the formation of a regular growth plate in the newborn. Analysis of the early stages around the seventh week of gestation revealed for type II collagen a strong hybridization signal limited to the chondrogenic tissue. The surrounding connective tissue and the perichondrium showed weak type I collagen expression, while the zones of desmal ossification like the clavicle gave a strong signal. Beginning with the eighth week of gestation, type I collagen mRNA was detectable in newly formed osteoblasts at the diaphysis and appeared along with the formation bone marrow, in the areas of enchondral ossification. Parallel to the development of the different zones of cartilage differentiation, a specific pattern of type II expression could be observed: type II was mainly found in the chondrocytes of the hypertrophic zone and to a lesser degree in the zone of proliferation, while the resting zone and the zone of provisional calcification showed little activity. This segregation of type II expression was most pronounced in the early stages of cartilage calcification and in the growth plate of the newborn.

Bone Development↗
PubMed1990

Monitoring enzyme replacement treatment in exocrine pancreatic insufficiency using the cholesteryl octanoate breath test.

The cholesteryl-14C-octanoate breath test was used to monitor the intraluminal enzymatic activity of pancreatin preparations in six patients with severe pancreatic insufficiency. Conventional enzyme replacement, with cimetidine as an adjunct, was compared to supplementation with enteric coated microspheres. In healthy control subjects, 14CO2 excretion rose rapidly and peaked at 90-120 minutes; mean (SD) cumulative recovery at four hours was 51 (8)%. In patients with pancreatic insufficiency on no treatment mean (SD) cumulative recovery was only 6 (4)%. After pancreatin, with previous administration of cimetidine, it increased to 27 (11)% with a time course resembling that in controls. With 2 mm enteric coated microspheres, 14CO2 excretion did not rise significantly before 120 minutes and cumulative recovery after four hours was 15 (11)%. In a control study, 2 mm radio-opaque microspheres did not empty from the stomach until two hours after ingestion. The results suggest that the cholesteryl octanoate breath test can be successfully used to monitor the intraluminal enzymatic activity after treatment with different forms of enzyme replacement in pancreatic insufficiency. In contrast to treatment with conventional pancreatin and cimetidine as an adjunct, 2 mm enteric coated microspheres did not show in vivo enzymatic activity until two hours after administration.

Breath Tests↗
PubMed1987

Comparison of principal components computed with principal factor analysis on the basis of averaged and single-trial ERPs using the Fischer-Roppert procedure.

Averaged and single-trial event-related potentials (ERPs) were analysed using the Principal Factor Analysis (PFA) with following varimax rotation, and the results were compared. The correspondence between the matrices of factor loadings was tested by means of the Fischer-Roppert-procedure. For the application of PFA, a preceding averaging to improve the signal to noise ratio is not necessary. If the group of subjects is homogeneous enough, the analysis of the single-trial ERPs provides results sufficient to investigate the component structure of the ERP. The ERPs from all subjects can be described with one common component structure.

Arousal↗
PubMed1987

The cholesteryl octanoate breath test: a new procedure for detection of pancreatic insufficiency in the rat.

A breath test for the detection of pancreatic insufficiency was developed and tested in rats. The test features the hydrophobic molecule cholesteryl-1-14C-octanoate, which liberates 14C-octanoic acid when hydrolyzed by carboxyl ester lipase (cholesterol esterase). The 14C-octanoate is absorbed passively and rapidly metabolized to 14CO2, which is excreted in expired air. The compound was administered as an emulsion of cholesteryl octanoate, triglyceride, and lecithin to rats with mild pancreatic insufficiency induced by injecting the pancreatic duct with zein. The animals had exocrine pancreatic hypofunction based on the enzyme content of pancreas at autopsy. Amylase was reduced by 97.1 +/- 1.4%, whereas chymotrypsin was reduced by 73 +/- 14%. The p-aminobenzoic acid test was abnormal at 1 wk (21.68 +/- 8.4%), but become normal at 3 months (72.08 +/- 5.8%) after zein injection. Despite this, the animals gained weight and absorbed fat normally. The 14CO2 excretion rate in the 110-min interval after feeding was significantly reduced to 60% of sham-operated animals. Peak 14CO2 collections 20 min after feeding were reduced by 75 +/- 11%. 14CO2 output was completely normalized by administration of pancreatin prior to the test meal. The results suggest that a sensitive, noninvasive method for detecting deficiency of pancreatic carboxyl ester lipase (cholesterol esterase) secretion in the rat has been developed.

4-Aminobenzoic Acid↗
PubMed1986

Exocrine pancreatic function in oleic acid-induced pancreatic insufficiency in rats.

Pancreatic insufficiency was induced in rats by a single injection of 50 microliter oleic acid into the pancreatic duct over a period of 3 min. Exocrine tissue was destroyed within 3-6 days, and after 6 weeks the remaining pancreas equaled 2.7% of the original organ. The rats showed retardation of body weight in spite of normal food intake. After 7 weeks the fecal weight increased by 23%, and the fecal chymotrypsin activity decreased by 90% compared to controls. At this time plasma cholecystokinin (CCK) concentrations were significantly elevated. The amylase content in the remaining pancreas was reduced by 99%, and trypsin content was reduced by 93%. Unstimulated protein discharge from the remnant pancreas in vitro was threefold higher compared to secretion from control tissue. Thus a simple, reproducible model for inducing persistent pancreatic insufficiency was developed. To compensate for the loss of exocrine tissue, the remaining acinar cells adapt by a CCK-mediated increase in protein secretion.

Adaptation, Physiological↗
PubMedDate not supplied

Genetics of congenital hand anomalies.

Congenital limb malformations exhibit a wide spectrum of phenotypic manifestations and may occur as an isolated malformation and as part of a syndrome. They are individually rare, but due to their overall frequency and severity they are of clinical relevance. In recent years, increasing knowledge of the molecular basis of embryonic development has significantly enhanced our understanding of congenital limb malformations. In addition, genetic studies have revealed the molecular basis of an increasing number of conditions with primary or secondary limb involvement. The molecular findings have led to a regrouping of malformations in genetic terms. However, the establishment of precise genotype-phenotype correlations for limb malformations is difficult due to the high degree of phenotypic variability. We present an overview of congenital limb malformations based on an anatomic and genetic concept reflecting recent molecular and developmental insights.

Chromosome Aberrations↗