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Biomedical subjects

P Dieker

Publications and source records attributed to P Dieker.

15 recordsLinked to original sources
PubMed1981

Lecithin-cholesterol-acyltransferase deficiency: autosomal recessive transmission in a large kindred.

Thirty-four members of a single Sardinian kindred with lecithin-cholesterol-acyltransferase deficiency have been studied. The kindred spans four generations and the parents of the two affected siblings are blood relatives. Segregation of the acyltransferase deficiency gene in the family clearly demonstrated an autosomal recessive mode of inheritance. Thirteen family members, including all obligate heterozygotes, had roughly half-normal acyltransferase activities (mean +/- S.D. = 0.39 +/- 0.06 mU/ml) when compared to 17 intrafamilial controls and spouses (mean +/- S.D. = 0.72 +/- 0.09 mU/ml) and 40 blood donors from Marburg/Lahn (mean +/- S.D. =0.76 +/- 0.1 mU/ml). Characterization of the heterozygotes did not reveal abnormalities in their plasma lipoproteins. LCAT deficiency and the beta-thalassaemia trait coexisting in this kindred segregated independently.

Consanguinity↗
PubMed1980

Substitution in vitro of lecithin-cholesterol acyltransferase. Analysis of changes in plasma lipoproteins.

Lecithin-cholesterol acyltransferase (EC 2.3.1.43) was purified 15 000-fold from human plasma. The active material was homogeneous in different gel electrophoretic systems but separated into three major bands with apparent pI values of 4.28, 4.33 and 4.37 in isoelectrofocusing. The apparent Mr of the enzyme is 67 000 +/- 2000. An antiserum prepared against the purified enzyme specifically inhibited the activity of lecithin-cholesterol acyltransferase in whole serum. Serum from a patient with familial deficiency of lecithin-cholesterol acyltransferase was substituted in vitro with the highly purified enzyme. The serum from this patient did not contain immunochemically detectable enzyme protein. Substitution of enzyme resulted in the following major changes. 1. Cholesteryl ester content in serum increased by 36-89 mg/100 ml depending on the experimental conditions. The enzyme-mediated formation of cholesteryl ester led to an increase of cholesteryl ester content in high-density and very-low-density lipoproteins and in low-density lipoproteins containing apoprotein-B. No increase occurred in fractions containing very large flattened structures and the abnormal lipoprotein-X and in lipoprotein-E. Incubation of isolated fractions with lecithin-cholesterol acyltransferase led to significant cholesterol esterification only in high-density lipoproteins. 2. The characteristic disc-shaped rouleaux-forming high-density lipoproteins of enzyme-deficient serum disappeared. Instead a single homogeneous population of high-density lipoproteins formed. The particles generated were spherical and had the electrophoretic properties, density (1.080 g/ml), diameter (12.5 nm) and apoprotein composition of normal high-density lipoproteins-2. 3. The concentration of spherical particles containing apolipoprotein E (density 1.040-1.080 g/ml) and the lamellar lipoprotein-X-like structures in the low-density lipoprotein fraction were not affected by the enzyme substitution. 4. A single homogeneous population of spherical lipoprotein-B particles of 26.5-nm diameter occurred at density 1.029 g/ml. The data suggest that the discoidal high-density lipoproteins are the major site of cholesteryl ester formation that apolipoprotein-E is not involved in an undirectional transport of newly formed cholesteryl ester from high-density lipoproteins to other lipoproteins and that lipoprotein-X and lipoprotein-E are not preferential substrates for the acyltransferase.

Apolipoproteins↗
PubMed1977

Intra- and extrarenal vascular changes in the acute renal failure of the rat caused by mercury chloride.

Histologic evidence of intrarenal vasomotor changes were observed in the rat in the course of acute renal failure caused by the injection of HgCl2. Male Wistar rats injected s.c. with 2.5 or 4.7 mg HgCl2 per kg b. wt. developed fibrinoid damage in the media segments of preglomerular renal vessels, mostly in the arcuate and interlobular arteries. The lesions were patchy and irregularly scattered throughout the kidneys. 24 h post-injection the lesions were very rare and of only mild degree, whereas they were fully developed and regularly seen 48 h post-injection. A high percentage of similar changes was found in certain extrarenal vascular areas especially in the mesentery and pancreas. The damaged vascular segments were usually dilated. The results of various thichrome stains and histochemical reactions suggested edema of vascular smooth muscle cells and imbibition of the media by blood plasma substances, sometimes reaching the degree of fibrinoid necrosis. These findings were confirmed by electron microscopy. The imbibition of the smooth muscle cells by blood plasma material was clearly evidenced by the demonstration of intracellular fibrin precipitations. In connection with the degeneration of smooth muscle cells, accumulations of crystal-like fibrin formations could often be shown. Subendothelial fibrin formations were not observed. 96 h after the 2.5 mg injection the changes were already regressing, but edema of the vascular wall and signs of disturbed vasotonia persisted for several days. The maximum of the vascular changes usually coincided with the maximum of azotemia and the formation of debris cylinders in the renal tubules. However, no clear relationship was recognizable in individual cases between vascular damage, extent of tubular necrosis and renal function. The pathogenesis of the vascular changes is obscure, but neurogenic factors, increased release of catecholamines and/or vasoactive agents of renal origin in connection with other factors might play a decisive role. Arterial hypertension was absent. It is assumed that the structural damage of the vascular media is mainly brought about by prolonged or recurring vasospasms, or by alternating spasm and vasodilatation with local ischemia and increased tension of the vascular wall in the dilated segments. The altered function and structure of the vascular wall might, to a certain extent, contribute to renal insufficiency.

Acute Kidney Injury↗
PubMed1976

[Total parathyroidectomy and autologous parathyroid transplantation in secondary hyperparathyroidism (author's transl)].

In a 17-year-old female patient with marked secondary hyperparathyroidism and progressive bone changes all four parathyroid glands were removed. Part of the endocrine tissue was reimplanted into the muscles of the forearm. The transplant took successfully and showed a satisfactory function. Total parathyroidectomy and autologous parathyroid transplantation has a number of advantages as compared with subtotal parathyroidectomy: The function of the transplant can be directly observed and tissue can be easily removed in the further course of the disease. It is thus possible to regulate parathormone secretion over long periods in patients with chronic renal failure.

Adolescent↗
PubMed1975

Lipoproteins in lecithin-cholesterol-acyltransferase(LCAT)-deficiency. II. Further studies on the abnormal high-density-lipoproteins.

The lipoproteins from two sibs with familial lecithin-cholesterol-acyltransferase(LCAT)-deficiency were further characterized. Comparatively lipoproteins from patients with secondary LCAT-deficiency were studied. Both groups of patients had particles of unusual size and shape in the alpha1-(HD-2)-lipoprotein subfraction. The abnormal HDL-2 particles were disk-like in appearance with a major axis of about 180 A and a minor axis of about 40 A and tended to aggregate into long coinlike stacks. The abnormal HDL-2 particles contained the normal protein constituents of HDL Apo A-I, Apo A-II and Apo C but in addition a major polypeptide with a M.W. of 39000 not seen in significant amounts in normal high-density-lipoproteins. This polypeptide was found identical in size, isoelectric focusing and immunochemically with an arginine-rich normal polypeptide constituent of very-low-density-lipoproteins designated apoprotein E. Presence of this protein marker in the HDL allowed the specific immunological detection of the abnormal HDL-2 (LP-E) in plasma. Further minor biochemical abnormalities were observed in the lipoproteins of the patients with familial LCAT-deficiency. However, the main protein constituents of their HDL, the Apo A, Apo C and Apo E polypeptides, were found to be identical electrophoretically and by analytical isoelectric focusing with their normal counterparts. The data suggest that the basic genetic defect in the hereditary disease leads to a deficient activity of the LCAT-enzyme and that all abnormalities in the lipoprotein spectrum are secondary.

Acetyltransferases↗