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Biomedical subjects

T Krieg

Publications and source records attributed to T Krieg.

At least 289 records · Page 16Linked to original sources
PubMed1980

[Ehlers-Danlos-Syndrome. Heterogeneity and molecular causes of the disease picture].

Progress in the experimental field and a deepened understanding of biological functional entities gave considerable impetus to connective tissue research. This was particularly true for the heritable connective tissue disorders, of which the Ehlers-Danlos-Syndrome is the best example. Its clinical and biochemical heterogeneity have allowed a classification of the disease into sub-groups, and the conditions for differential diagnosis and therapeutic trials were thus improved.

Collagen↗
PubMed1979

Inhibiting effect of procollagen peptides on collagen biosynthesis in fibroblast cultures.

NH2-terminal extension peptides of type I and type III procollagens were isolated from dermatosparactic and normal fetal calfskin, respectively. Cell culture experiments showed that the globular domains of the tested procollagen peptides were biologically active but that peptides from the helical region of collagen had no effect. The peptides were added to the incubation medium of calf fibroblasts along with radioactive precursor amino acids, and the amount of newly synthesized collagen was determined. The experiments indicated that procollagen peptides exerted a feedback-like inhibitory effect specific for the synthesis of collagen. Neither degradation of collagen, hydroxylation of collagen alpha chains, nor synthesis of noncollagenous proteins were affected. Synthesis of type II collagen by calf chondrocytes was not reduced. In addition, it was shown that procollagen peptides from calf were equally effective when added to human fibroblast cultures, an observation that could be of considerable medical interest.

Animals↗
PubMed1979

Biochemical characteristics of Ehlers-Danlos syndrome type VI in a family with one affected infant.

The parents of a child with the clinical symptoms of Ehlers-Danlos syndrome type VI were identified as third-degree cousins. Biochemical analysis of the dermis of the patient revealed a complete lack of hydroxylysine in the dermal collagen. The dermis of both parents contained only half the amount of hydroxylysine found in healthy individuals. Hydroxylation of prolyl residues was normal in the skin of the patient and his parents. Investigation of the collagen synthesized by fibroblasts derived from the skin of the patient showed a normal proportion of type I and type III collagen. However, while hydroxylation of prolyl residues was normal in type I and type III collagen, hydroxylation of lysyl residues was markedly lower than normal in both type I and type III collagen.

Collagen↗
PubMed1978

Aminoterminal extension peptides from type I procollagen normalize excessive collagen synthesis of scleroderma fibroblasts.

Fibroblasts derived from a skin biopsy of a patient with scleroderma in the sclerotic stage were shown to have a higher rate of DNA synthesis, and to synthesize more collagen than fibroblasts from a healthy control. The addition of procollagen peptides to the culture medium of scleroderma fibroblasts almost normalized the collagen synthesis. This observation indicates that the mechanism for the regulation of collagen synthesis by feed back inhibition of prollagen peptides is functioning in this disease. It is suggested that the level of biologically active procollagen peptides is lowered.

Collagen↗
PubMed1978

[Hexachlorbenzene (HCB) induced porphyria in rats. Influence of HCB-metabolites on the biosynthesis of heme (author's transl)].

Female adult Wistar rats were fed with a diet containing 0.05% hexachlorobenzene (HCB) or its metabolites, pentachlorobenzene (PCB) and pentachlorphenole (PCP). These chlorinated aromatic hydrocarbons produced an increase in the liver cytochrome P-450 content in about the same degree, however, only the application of HCB showed an extremely high rise in the P-450 enzymatic activity expressed in terms of the O-dealkylation of 7-Ethoxycoumarine. No alteration was observed in the urinary porphyrin excretion in the PCB and PCP treated animals, whereas 60 days after the beginning of the HCB application a high level of porphyrins could be detected in the urine of the animals. It seems unlikely therefore that the HCB metabolites (PCB and PCP) are porphyrogenic agents. In addition, although induction of the liver cytochrome P-450 system was observed after PCP pretreatment of the rats over a period of 40 days, the consequent application of HCB did not influence the establishment of the experimental porphyria.

Animals↗
PubMed1978

[Porphyria cutanea tarda: possible treatment and its results (author's transl)].

In 4 of 12 patients with porphyria cutanea tarda (PCT) treatment with p-aminobenzoic acid (PABA) achieved normal porphyrin excretion and disappearance of the skin changes. But this result is far worse than that obtained with the venesection method of Ippen. PABA treatment should, therefore, be discontinued.--Among 56 patients (37 males, 19 females) given chloroquine treatment (twice 125 mg per week), normal porphyrin excretion and disappearance of the skin changes occurred in 32 after an average duration of treatment of 8 months, while in 21 (15 males and 6 females) an improvement set in after an average treatment duration of only 5 months so far. The treatment failed in three patients, but one of them lapsed his treatment and one died of an intercurrent disease, so that only one can be reckoned a true failure of chloroquine treatment.

4-Aminobenzoic Acid↗
PubMed1977

[Long time HCB exposition of rats: influence on the porphyrin excretion in the urine and on the cytochrome P-450 in the liver (author's transl)].

Adult female Wistar rats were fed with a diet containing 0.05% HCB. About the 55th day of the experiments an increase of porphyrin and its precursors (ALA and PBG) in the urine of the rats can be measured. In contrast the induction of the O-dealcylation reaction of 7-ethoxycoumarin could be already measured 2 days after starting with the HCB feeding. The inhibition of the enzymatic reaction by metyrapone, naphthoflavone, tetrahydrofurane or CO/O2 presents neither the typical pattern of the phenobarbital type nor the typical pattern of the benzpyrene type of cytochrome P-450. When the animals became porphyric (about the 55th day of the HCB exposure) no qualitative changes in the cytochrome P-450 pattern could be demonstrated. The relationship between the enzyme induction in the liver and the porphyria following the HCB application is still remaining unclear.

Animals↗
PubMed1977

The marfan's syndrome. In vitro study of collagen metabolism in tissue specimens of the aorta.

Tissue specimen of the aorta was obtained from a patient with Marfan's syndrome after heart surgery. Media and adventitia were carefully separated and subsequently used for biochemical characterization. Aortas from an embryonic calf and from a human adult were used as internal controls. The data clearly indicated that an insufficient synthesis of type I collagen rather than a defect in the formation of cross-links may be the prime cause in this inherited connective tissue disorder. Such a disturbance in the regulation of the genes coding for the different collagen chains may explain the weakness and enhanced extensibility of the blood vessels finally resulting in an aneurysm.

Aminopropionitrile↗
PubMed1976

[Erythropoietic protoporphyria: porphyrin content of a gall-stone (author's transl)].

In the case of a 48 year old woman with characteristic signs of erythropoetic protoporphyria, a solitary gall-stone which had persisted over a period of 10 years was removed. Porphyrin-concentration of this gall-stone was found to be 22.6 mcg/g, which is almost twenty times the concentration of other cholestrol-stones. Besides protoporphyrin, porphyrins with a higher degree of carboxylation were discovered in four different samples by thin layer chromatography. It is postulated that the increased bile-concentration of protoporphyrin in the liver causes the cristallisation of cholestrol and the formation and growth of gall-stones. The biochemical finding of porphyrins with a higher degree of carboxylation indicates that the porphyrins of the gall-stone may not only come from hemolysed erythrocytes but possibly also from metabolites of disturbed hepatic porphyrin biosynthesis.

Cholelithiasis↗
PubMed1976

[Release of 14c-chloramphenicol in the rabbit femur implanted with polymethylmetacrylate (author's transl)].

In vitro studies and animal experiments were started for the purpose of following the migration of chloramphenicol marked with 14C from polymerised polymethylmetacrylate cylinders. Test-cylinders were submerged in a physiological saline solution and the 14C concentration followed over a period of 34 days. Two series were started with the cylinders being submerged at intervals of 5 and 40 min after the start of polymerisation. These in vitro studies showed that initially the migration of active substances marked with 14C from the plastic cylinders was extremely high but remained then constant over the whole test period. Over a period of at least 20 days a higher 14C migration was evident in those cylinders submerged in the elution 5 min after the start of polymerisation. In our in vivo studies we implanted test-cylinders into the femur of rabbits. The migration of active substances marked with 14C resulted in 14C-concentrations being present in the surrounding tissues. During the phase of exudation, depending on the operative process, the concentration increased and reached values that remained constant during the phase of recanalisation of the surrounding tissues over a period of up to 6 weeks. Thereafter the concentration of active substances fell. The max. concentration rates of active substances within the boundary layer were between 15 and 20 mug/g humidity weight. After 8 weeks we found concentration rates of approx. 1 mug/g humidity weight. On examining the 14C distribution within the implanted plastic cylinders we observed that in the course of time the boundary layer increased in thickness and a concentration gradient towards the centre had developed. The spread of diffusion gradually seized the deeper layers so that a long-lasting presence of active substances may be expected.

Acrylic Resins↗
PubMed1976

[Letter: Porphyria cutanea tarda: normalization of porphyrin-excretion following treatment with p-amino-benzoic acid (Potaba) (author's transl)].

Two patients with porphyria cutanea tarda were treated with p-amino-benzoic acid (Potaba) (3x4g/day). Normalization of porphyrin-excretion was observed after three respectively 45 days of treatment. Furthermore no influence of the excretion of porphyrin precursors (porphobilinogen or delta-amino-levulinic acid) were noticed. Also, no side effects of this treatment were found.

Adult↗