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Biomedical subjects

L Risteli

Publications and source records attributed to L Risteli.

208 records · Page 12Linked to original sources
PubMed1975

Glucosylation of galactosylhydroxylysyl residues in collagen in vitro by collagen glucosyltransferase. Inhibition by triple-helical conformation of the substrate.

Glucosylation of galactosylhydroxylysyl residues in various collagen polypeptide chains and in small peptides prepared from collagen was studied in vitro using collagen glucosyltransferase purified about 200 to 500-fold from extract prepared from chick embryos. When various denatured polypeptide or peptide chains were compared as substrates for the enzyme, no significant differences were found between citrate-soluble collagens from normal or lathyritic rats and isolated alpha1 and alpha2 chains. In contrast, gelatinized insoluble calf skin collagen, and peptides prepared from collagen and having an average molecular weight of about 500 were clearly less effective substrates as judged from their Km and V values. A marked difference was found between native and heat-denatured citrate-soluble collagen in that no synthesis of glucosylgalactosylhydroxylysine was observed with the native collagen when the reaction was studied at 30 degrees C with different times, enzyme concentrations, and substrate concentrations. When the reaction was studied as a function of temperature, little glucosylation of native collagen was observed below 37 degrees C, but there was a sharp transition in the rate of glucosylation of native collagen at temperatures above 37 degrees C, similar to that observable in the melting curve of collagen. The data suggest that triple-helical conformation of collagen prevents that glucosylation of galactosylhydroxylysyl residues.

Animals↗
PubMedDate not supplied

Serum type III procollagen and basement membrane proteins as noninvasive markers of hepatic pathology in Indian childhood cirrhosis.

While serum concentrations of antigens of the aminopropeptide of type III procollagen have been considered as indicators of hepatic pathology in adults, the high concentrations normally found in children during growth may preclude their use in pediatric liver disease. To clarify this and to determine the role of other circulating connective tissue-related substances in children, we have measured serum concentrations of antigens related to aminopropeptide of type III procollagen, the 7S domain of type IV collagen and the P1 fragment of laminin in healthy subjects aged 1 month to 4 years and in children with Indian childhood cirrhosis, a particularly aggressive form of liver disease. In healthy subjects, there was a considerable age variation in serum aminopropeptide of type III procollagen but not in 7S collagen or laminin P1. In Indian childhood cirrhosis, all three serum antigens were increased (p less than 0.001) above the upper limit of normal for age. Both the serum 7S collagen and laminin P1 concentrations showed a significant correlation with the degree of intralobular fibrosis and also with the severity of necrosis and cellular infiltration, suggesting that these serum antigens may be a noninvasive means of assessing and monitoring events associated with hepatic fibrosis in Indian childhood cirrhosis. The raised serum aminopropeptide of type III procollagen in Indian childhood cirrhosis did not correlate with any histological parameter assessed. Gel filtration of serum showed that, in healthy subjects, the predominant antigenic form of aminopropeptide of type III procollagen was a degradation peptide smaller than authentic aminopropeptide of type III procollagen; while in Indian childhood cirrhosis the authentic peptide and a larger degradation peptide predominated.(ABSTRACT TRUNCATED AT 250 WORDS)

Basement Membrane↗
PubMedDate not supplied

The basement membrane proteins laminin and type IV collagen in isolated villi in pre-eclampsia.

The distribution and concentrations of the basement membrane proteins laminin and type IV collagen were studied in isolated placental villi in normal pregnancy and in pre-eclampsia. In both cases these proteins could be localized by immunofluorescence in the trophoblast and capillary basement membranes, and occasionally also in the matrix surrounding the capillaries. The basement membrane proteins were quantified by solubilizing the villi with proteolytic enzymes and by subsequently measuring the concentrations of two resistant domains of these proteins (7-S collagen and the fragment PI, representing type IV collagen and laminin, respectively) with specific radioimmunoassays. The ratio type IV collagen:laminin was significantly higher in pre-eclamptic samples than in the controls, most probably reflecting a decrease in laminin concentration in the villi in pre-eclampsia. Such a change in the chemical composition of placental basement membranes could weaken the attachment of trophoblast cells to the underlying basement membrane and also modify the permeability and exchange properties of the villi.

Basement Membrane↗
PubMedDate not supplied

Preoperative high type I collagen degradation marker ICTP reflects advanced breast cancer.

Type I collagen synthesis (PINP, PICP) and degradation (ICTP) markers were analysed from preoperative serum samples of 138 women with breast cancer (BC), 94 women with benign breast disease (BBD) and 100 healthy controls to evaluate the levels of these markers and the stage of BC at the time of diagnosis. We also compared the clinical utility of these markers in detecting BC with CA15-3 and CEA. The mean value of ICTP was statistically significantly elevated in the BC group (p < 0.001), as compared with the control group, but the elevated values in BC group were due to stage IV disease. The sensitivity of ICTP in detecting BC was 0.23, which was equal with CA15-3(0.24) or CEA(0.23). The sensitivity of both PICP and PINP for diagnosing BC was poor, but a tendency to higher serum levels of PINP and low PICP/PINP ratio was detected in patients with advanced stage IV disease. These results indicate that high preoperative serum levels of ICTP are associated with advanced BC, but like CA15-3 and CEA, its clinical value in diagnosing purpose is poor.

Biomarkers, Tumor↗
PubMedDate not supplied

Serial determinations of aminoterminal propeptide of type III procollagen (PIIINP) and prognosis in ovarian cancer; comparison to CA125.

During malignant growth many changes take place in the metabolism of fibrillar type III collagens in the connective tissues. The aminoterminal propeptide of type III procollagen (PIIINP) has been found to be often elevated in ovarian cancer. In the present study the prognostic value of serum PIIINP concentration in epithelial ovarian cancer is evaluated in relation to serum CA125. Fifty-six women were enrolled in the study. Serial venous blood samples were taken preoperatively and 6, 9 and 12 months after operation for PIIINP and CA125 determinations. The results were correlated to the three-year survival. In Kaplan-Meier survival analysis the preoperative (P = 0.0422), 9-month (P = 0.0062) and 12-month (P = 0.0062) serum PIIINP concentration distinguished between the patients with good and poor prognosis while CA125 did so only at 9- (P = 0.0005) and 12-month (P < 0.0001) follow-up. In the multivariate analysis the independent predictors of prognosis were the preoperative PIIINP and 12-month CA125 concentrations. The percentage changes in serum PIIINP concentration did not differentiate the patients with good or poor prognosis at any time point, whereas the changes in CA125 concentration significantly divided the patients into two prognostic groups during the second half of the postoperative year. We found that PIIINP and CA125 are complementary to each other as predictors of prognosis in epithelial ovarian cancer as preoperative PIIINP was better than CA125 and 1-year CA125 better than PIIINP in this function.

Adult↗
PubMedDate not supplied

Aminoterminal propeptide of the alpha1-homotrimer variant of human type I procollagen (hotPINP) in malignant pleural effusion.

The aminoterminal propeptide (hotPINP) of type I homotrimer, a putative malignancy-associated type I collagen variant, was purified for the first time and a method was established for its detection in pleural fluid. Samples of 58 patients, with malignant or benign disease, were studied with specific immunoassays for the two propeptides of type-I procollagen (PICP and PINP) and with HPLC-DEAE chromatography to separate the two PINP variants. HotPINP was present in 64% of both benign and malignant pleural effusion fluids, with the exception of malignant mesotheliomas, none of which showed the presence of hotPINP. Also the PICP to PINP ratios were lower than normal in both benign and malignant samples (altogether in 69% of samples), although this deviation was greater in malignancy. These two phenomena were independent of each other. As synthesis of the alpha1-homotrimer-variant of type-I collagen seems to be relatively common during the formation of pleural effusion, it may be generally related to a fibroproliferative reaction in the pleural wall.

Amino Acid Sequence↗
PubMedDate not supplied

Effect of intravenous feeding on wound healing in starvation: an experimental study on the rabbit.

The effects of modified protein sparing therapy (PSP) and total parenteral nutrition (TPN) on total and wound metabolism were studied for 96 hours after laparotomy and a small gastric excision in 40 rabbits starved for seven days. A further eight starved and eight non-starved animals served as controls for the blood variables. Normal healing up to day 14 was studied in 20 non-starved animals. The difference in deaths and animals in poor condition, 42.1 per cent in PSP and 18.6 per cent in TPN, respectively, was clear but statistically non-significant. PSP led to a lower mean serum albumin concentration than TPN, 25.7 +/- 3.7 (SD) and 28.7 +/- 3.0 (p = 0.02), respectively. The animals receiving PSP excreted significantly more 3-methylhistidine. TPN maintained a positive nitrogen balance, but PSP produced a negative one. The collagen content of the skin scar was lower after PSP (3.1 +/- 0.7 mg) than after TPN (4.5 +/- 1.3 mg) (p less than 0.05), the latter coming close to the level for normal 4-day healing, 4.5 +/- 1.2 mg. Prolyl 4-hydroxylase (PPH) activity showed no difference. No inter-group differences in collagen were found in the stomach. Both regimens totally reversed the starvation-induced decrease in PPH activity in the stomach, but only partially in skin. Thus TPN produced better total and skin wound metabolism after laparotomy and starvation than did PSP. No differences in visceral wound healing were observed.

Animals↗
PubMedDate not supplied

Connective tissue metabolites in serum as markers of disease activity in patients with rheumatoid arthritis.

The serum levels of aminoterminal type III procollagen peptide (S-PIIINP), immunoreactive prolyl 4-hydroxylase protein (S-IRPH), 7S domain of collagen type IV (S-Col IV, 7S), and fragment P1 of laminin (S-Lam), which are associated with the metabolism of extracellular interstitial collagens and basement membranes, were measured sequentially for two years in 14 rheumatoid arthritis (RA) patients undergoing disease modifying antirheumatic drug treatment. Elevated S-PIIINP, S-IRPH, and S-Col IV, 7S levels were demonstrated in active RA. In active disease the metabolites showed some correlation with clinical and serological signs of disease activity. A high average synovial fluid/serum concentration ratio of PIIINP and of Col IV, 7S supports the concept that the increased serum levels of PIIINP and Col IV, 7S originated from the diseased joints. After 2 years of treatment a decline was observed in S-PIIINP and S-Col IV, 7S in treatment responders. However, the median levels of S-PIIINP and S-IRPH were still above the upper limit of normal, suggesting smouldering, subclinical inflammatory processes. S-Lam remained within the normal range in active and inactive disease.

Adult↗
PubMedDate not supplied

A novel type of developmental dentin defect.

We describe a developmental dentin disorder distinct from dentin defects characterized thus far. The proband was a 9-year-old boy who was the only family member known to be affected in five generations. The dental defect was not associated with any general disease or developmental disorder. The teeth appeared normal with the exception of the pink hue seen in some primary teeth. Radiographs showed pathological resorption of primary teeth and abnormally shaped pulp chambers and denticles in permanent teeth. Root canals were wide in developing teeth, but appeared thin in erupted teeth. Histological examination of two primary molars revealed canal-like defects in dentin. In the crown, the canals appeared as clusters, which alternated with columns of normal tubular dentin, and in the virtually atubular root dentin they were haphazardly distributed. Scanning electron microscopic examination confirmed the distribution pattern of the canals. In transmission electron microscopy, the defects were found to contain symmetrically banded, segmental collagenous structures. The canal contents immunostained with antibodies to the N-terminal propeptide of type I procollagen, suggesting retention of the propeptide extension in type I collagen. Whereas type III collagen reactivity was barely detectable in the canal region, staining for type V collagen and the non-fibril-forming type VI collagen was strong. The findings imply that the pathogenesis of the defect could be related to a local failure of odontoblasts to produce normal dentin matrix.

Child↗