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Biomedical subjects

K Ullrich

Publications and source records attributed to K Ullrich.

141 records · Page 8Linked to original sources
PubMed1979

Endocytosis of beta-N-acetylglucosaminidase from sections of mucolipidosis-II and-III fibroblasts by non-parenchymal rat liver cells.

beta-N-Acetylglucosaminidase isolated from the secretions of fibroblasts of mucolipidosis-II and -III patients is internalized by cultured non-parenchymal rat liver cells. The rate of endocytosis compared with that of beta-N-acetylglucosaminidase from control fibroblasts was 11 and 19% for the enzyme from mucolipidosis-II and -III patients respectively. The inhibition of endocytosis by mannan indicates that the beta-N-acetylglucosaminidase from mucolipidosis-II and -III patients is recognized by cell-surface receptors specific for mannose.

Acetylglucosaminidase↗
PubMed1979

Recognition of human urine alpha-N-acetylglucosaminidase by rat hepatocytes. Involvement of receptors specific for galactose, mannose 6-phosphate and mannose.

Adsorptive endocytosis of alpha-N-acetylglucosaminidase from human urine by isolated rat hepatocytes is inhibited by glycoproteins, polysaccharides and sugars that are known to bind to cell-surface receptors specific for either terminal galactose/N-acetylgalactosamine residues, terminal mannose residues or mannose 6-phosphate residues. Recognition of alpha-N-acetylglucosaminidase by a cell-surface receptor specific for terminal galactose/N-acetylgalactosamine residues is supported by the observations (a) that neuraminidase pretreatment of the enzyme enhances endocytosis, (b) that beta-galactosidase treatment decreases endocytosis and (c) that neuraminidase pretreatment of hepatocytes decreases alpha-N-acetylglucosaminidase endocytosis. Recognition of alpha-N-acetylglucosaminidase via receptors recognizing mannose 6-phosphate residues is lost after treatment of the enzyme with alkaline phosphatase and endoglucosaminidase H. The effect of endoglucosaminidase H supports the view that the mannose 6-phosphate residues reside in N-glycosidically linked oligosaccharide side chains of the high-mannose type. The weak inhibition of endocytosis produced by compounds known to interact with cell-surface receptors specific for mannose residues suggests that this recognition system plays only a minor role in the endocytosis of lysosomal alpha-N-acetylglucosaminidase by hepatocytes.

Acetylglucosaminidase↗
PubMed1979

Effect of lectins on endocytosis and secretion of lysosomal enzymes by cultured fibroblasts.

1. Pretreatment of cultured human skin fibroblasts with convanavalin A and wheat germ agglutinin inhibited endocytosis of alpha-N-acetylglucosaminidase and increased extracellular accumulation of beta-N-acetylglucosaminidase. 2. These effects were dose-dependent, reversible and could be prevented by haptenic carbohydrates, such as methyl alpha-D-mannoside or N-acetylglucosamine. 3. Pretreatment of fibroblasts with di- and monovalent succinylated concanavalin A inhibited alpha-N-acetylglucosaminidase endocytosis, but had no effect on extracellular beta-N-acetylglucosaminidase accumulation. 4. Concanavalin A-alpha-N-acetylglucosaminidase complexes become internalized via the recognition of the lectin. Complex formation prevents recognition of the phosphorylated carbohydrate on lysosomal enzymes that interacts with cell surface receptors specific for lysosomal enzymes. The inhibitory effect of all lectins tested on lysosomal enzyme endocytosis suggests that the cell surface receptors for lysosomal enzymes interact either directly with lectins or are closely linked to lectin receptors. The effect of polyvalent lectins on extracellular lysosomal enzyme accumulation is ascribed to their alteration of membrane fluidity.

Acetylglucosaminidase↗
PubMed1978

Evidence for lysosomal enzyme recognition by human fibroblasts via a phosphorylated carbohydrate moiety.

Adsorptive endocytosis of five different lysosomal enzymes from various human and non-human sources was susceptible to inhibition by mannose and l-fucose, methyl alpha-d-mannoside, alpha-anomeric p-nitrophenyl glycosides of mannose and l-fucose, mannose 6-phosphate and fructose 1-phosphate. A few exceptions from this general scheme were observed for particular enzymes, particularly for beta-glucuronidase from human urine. The inhibition of alpha-N-acetylglucosaminidase endocytosis by mannose, p-nitrophenyl alpha-d-mannoside and mannose 6-phosphate was shown to be competitive. The loss of endocytosis after alkaline phosphatase treatment of lysosomal enzymes supports the hypothesis that the phosphorylated sugars compete with a phosphorylated carbohydrate on the enzymes for binding to the cell-surface receptors [Kaplan, Achord & Sly (1977) Proc. Natl. Acad. Sci. U.S.A.74, 2026-2030]. Endocytosis of ;low-uptake' forms of alpha-N-acetylglucosaminidase and alpha-mannosidase was likewise susceptible to inhibition by sugar phosphates and by alkaline phosphatase treatment, suggesting that ;low-uptake' forms are either contaminated with ;high-uptake' forms or are internalized via the same route as ;high-uptake' forms. The existence of an alternative route for adsorptive endocytosis of lysosomal enzymes is indicated by the unaffected adsorptive endocytosis of rat liver beta-glucuronidase in the presence of phosphorylated sugars and after treatment with alkaline phosphatase.

Acetylglucosaminidase↗
PubMed1978

Epithelial rat liver cells have cell surface receptors recognizing a phosphorylated carbohydrate on lysosomal enzymes.

Receptor-mediated endocytosis of alpha-N-acetylglucosaminidase by cultured epithelial rat liver cells is inhibited by mannose, L-fucose and most effectively by mannose 6-phosphate. Endocytosis of alpha-N-acetylglucosaminidase is lost after treatment of the enzyme with alkaline phosphatase. These findings indicate that epithelial rat liver cells possess cell surface receptors that recognize a phosphorylated carbohydrate on alpha-N-acetylglucosaminidase, as was previously reported for cell surface receptors of human skin fibroblasts. Inhibition of alpha-mannosidase endocytosis by epithelial rat liver cells in the presence of mannose 6-phosphate and loss of enzyme endocytosis after treatment with alkaline phosphatase suggest that this enzyme is recognized by the same receptor.

Acetylglucosaminidase↗
PubMed1977

[Early embryonal maldevelopment of the umbilical cord with defect of the abdominal wall and severe body malformations (dysplasia umbilico-fetalis) (author's transl)].

A case of dysplasia umbilico-fetalis is demonstrated. The malformation comprises a rare and strange reduction anomaly of the feto-umbilical unit, which is caused during early embryonic life (around the 7 mm stage, corresponding to the end of the third week of gestation). The cause of the damage is not known. The folding off of the embryo from the yolk sac and the development of the abdominal stalk are impaired. No abdominal wall is formed, and the umbilicus and umbilical cord are not developed. The abdominal organs are enclosed in a short amnion-mesoderm tube, which is bordered by the retroperitoneum at the fetal side and by the chorionic plate at the placenta side. The umbilical vessels are only a few centimeters long and traverse in the mesodermal layer of the amnion-mesoderm tube. The thin wall of the tube usually ruptures before birth, thus causing an abacterial fibrinoid peritonitis by the chemical irritation of the peritoneum through the constituents of the amniotic fluid. The lower extremities of the fetus reveal varying degrees of reduction deformities. One leg and large parts of the pelvis may be entirely missing, if the side of origin of the extremity is included in the amnion-mesoderm tube. Severe kyphoscoliosis is probably a secondary phenomenon. In addition, malformations of the inner organs occur such as caudal displacement and hernia of the diaphragma, hypoplasia of the lungs, dysplasia of the genito-urinary tract and non-rotation of the gut. The pathophysiology of the rare developmental defect and its secondary implications are discussed with special reference to related malformations such as omphalocele and infraumbilical defect of the abdominal wall.

Abdominal Muscles↗
PubMed1976

[Cystinosis (author's transl)].

Cystinosis (syn. crystine storage disease) is inherited as an autosomal recessive trait. The severety of clinical symptoms may vary considerably. The most severe form of nephropathic cystinosis causes death of the affected patients at the age of 2 to 4 years (subacute course) or before puberty (primary chronical course). Three autopsy cases are demonstrated. Each of these children died from complications of chronic renal failure, caused by kidney contraction as a sequela of chronic interstitial nephritis. Cristalline cystine deposits were found in the renal interstium as well as in the RES cells of spleen and liver. Because of water solubility of L-cystine aqueous fixation and staining solutions must be avoided. Diagnostic doubly refractive brick- or needle-shaped cystine cristals can be demonstrated in frozen sections or tissue smears from spleen, liver, lymphnode and bone marrow.

Child↗
PubMedDate not supplied

[Tuberculous meningitis in a 13-month-old boy: a case report].

We present the case of a 13-month old Turkish boy of Kurdish origin with tuberculous meningitis. Fever of unknown origin and neurologic symptoms (loss of ability of walking and free sitting, cerebral seizures, central paresis of the VII. cranial nerve, coma) led to the diagnosis. Cranial CT demonstrated hydrocephalus and enhancement of the basal meninges after contrast injection; the chest x-ray showed an infiltrate in the right upper lobe of the lung and the cerebrospinal fluid (CSF) mild pleocytosis with elevated protein and reduced glucose concentrations. Diagnosis was confirmed by detection of Mycobacterium tuberculosis in the CSF by polymerase chain reaction (PCR). Immediately, surgical and level-controlled tuberculostatic treatment was initiated. The patient recovered completely.

Antitubercular Agents↗
PubMedDate not supplied

School performance and intellectual outcome in adolescents with phenylketonuria.

In a retrospective study, 34 treated adolescents with phenylketonuria and their relatives were tested with scale 2 of the Culture Fair Intelligence Test (CFT20) and self-developed questionnaire concerning their development in school. The patients also filled in the Anxiety Questionnaire for Children. With an IQ of 93.6, the patients reached a normal mean intellectual performance but this was significantly below the mean IQ of the general population (100, p < 0.01), the IQ of their mothers (98.2, p < 0.05), their fathers (105.4, p < 0.05) and their siblings (110.3, p < 0.05). The patients' IQs correlated significantly with the IQs of their mothers, the socio-economic status of their families, the quality of dietary control since birth and the serum phenylalanine concentration at the moment of testing. With respect to age at which the patients started school, type of school attended and number of school years which had to be repeated, there were no significant differences between the patients and their siblings. The patients did not display a markedly higher degree of general anxiety, nervousness at examination time or a greater reluctance to attend school.

Adolescent↗
PubMedDate not supplied

Most comfortable listening level presentation versus maximum discrimination for word discrimination material.

The purpose of the present study was to determine if most comfortable listening level (MCL) presentation of word discrimination material would yield maximum discrimination for normal and sensorineural hearing loss subjects. The results of the study indicated that normally hearing listeners do obtain maximum discrimination at MCL, while presentation of word discrimination material at MCL to sensorineural hearing loss listeners does not yield maximum discrimination. Further examination of the results would also contraindicate the use of any other method which incorporates single or dual presentation levels as a means of determining maximum discrimination for the sensorineural hearing loss listener.

Adolescent↗