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Biomedical subjects

I Paronen

Publications and source records attributed to I Paronen.

14 recordsLinked to original sources
PubMed1998

Bone remodelling in the pores and around load bearing transchondral isoelastic porous-coated glassy carbon implants: experimental study in rabbits.

Cylinders of porous-coated glassy carbon were implanted into drill holes made through the articular surface of the medial condyle of both tibiae of ten rabbits for six and 12 weeks. Bone ingrowth and remodelling was examined by radiographic, histologic, oxytetracycline-fluorescence and microradiographic methods. Bone ingrowth into pores and load bearing implants was seen by all examination methods. Bone ingrowth occurred earlier when the pores were facing cancellous bone than cortical bone. Appositional bone formation occurred on the trabeculae a few millimetres from the interface during the early phase of remodelling at six weeks. At 12 weeks resorptive remodelling had occurred both in the surroundings and in those pores that face cancellous bone, whereas the amount of bone still increased in the pores facing cortical bone. In its porous-coated form glassy carbon functions well as a frame for ingrowing bone and it shows good osteoconductivity. Its mechanical properties are suitable for functioning as a structural bone substitute in places where the loads are mainly compressive. The difference between findings at six and 12 weeks indicated physiologic stress distribution and the adverse effects of stiff materials on bone remodelling were avoided by using this isoelastic material.

Journal Article↗
PubMed1996

Enterochromaffin cell density in the gastric mucosa of patients with chronic renal failure.

Thirty patients with chronic renal failure (CRF) and 30 age- and sex-matched controls were assessed for gastrointestinal diseases by gastroscopy, serum gastrin determination, and routine clinical and laboratory evaluation. Biopsy specimens from their gastric oxyntic mucosa were immunohistochemically stained with monoclonal antibodies against serotonin (5-hydroxytryptamine) and chromogranin A, the latter staining all gastric endocrine cells, the former disclosing serotonin-containing enterochromaffin (EC) cells only. The average EC cell density (cells/mm2) in the CRF patients was significantly lower than in the controls: 2.6 vs 12.9 (p = 0.0005). The EC cell counts also correlated negatively with serum gastrin values (p = 0.0031). The densities of the chromogranin-positive cells did not differ between CRF patients (74 cells/mm2) and controls (76 cells/mm2) (p = 0.7559). We conclude that, in addition to the previously known findings of hypoacidity, persistent hypergastrinaemia, and G and parietal cell hyperplasia, CRF also reduces the number of oxyntic EC cells. The negative correlation between EC cell density and serum gastrin levels reflects the complex interplay between different endocrinological activities in the gastrointestinal tract.

Adult↗
PubMed1994

Glassy carbon implant as a bone graft substitute: an experimental study on rabbits.

The purpose of this experimental investigation was to study the incorporation of porous glassy carbon in bone. Cylinders of porous glassy carbon were implanted in drill holes in diaphyses and metaphyses of rabbits tibia for 1, 3, 6, 12 and 24 weeks. Bone ingrowth into the glassy carbon implants was examined by radiographic, histologic, fluorocrome and microradiographic methods. The material caused no pathological reaction. Tissue ingrowth into pores was seen by all examination methods. The amount of bone in the pores increases with time. The ingrowth was most distinctive in those areas where the implant was in close contact with cortical bone or trabeculae of the cancellous bone. Porous glassy carbon can be used as bone substitute, although the small size of implant available is at the present a limitation for its clinical use.

Animals↗
PubMed1993

Osteoporosis in lysinuric protein intolerance.

Lysinuric protein intolerance (LPI) is an autosomal recessive disease characterized by defective transport of cationic amino acids. Patients have an increased incidence of fractures and their skeletal radiographs show osteoporosis. The aim of the study was to characterize the osteopenia in LPI. Twenty-nine Finnish LPI patients (age range 3.7-44.4 years) were screened for parameters of bone metabolism. Morphometric analysis of bone was carried out in specimens of 9 patients. Collagen synthesis was studied with cultured skin fibroblasts (4 patients) and collagen fibril sizes (3 patients) were measured using electron microscopy. Most histological bone specimens (8/9) showed osteoporosis. Osteomalacia was excluded. Routine clinical laboratory tests were unrevealing. The concentrations of free hydroxyproline and type III procollagen N-propeptide in serum and the urinary excretion of hydroxyproline were increased in almost all patients during their growth and in about half of adult patients. Collagen synthesis in LPI fibroblast cultures was significantly decreased compared with that in age-matched controls at 5 (p < 0.01), 14 (p < 0.01) and still at 30 years (p < 0.01), whereas no difference was observed at the age of 44 years (p = N.S.). Osteoporosis in LPI might reflect defective matrix protein synthesis caused by protein deprivation and deficiency of cationic amino acids. Increased collagen turnover can also contribute to the osteoporosis.

Adolescent↗
PubMed1991

Gastric parietal, chief, and G-cell densities in chronic renal failure.

We calculated morphometrically the amount of antral gastrin-producing (G) cells and body parietal and chief cells in gastric biopsy specimens from 30 undialysed patients with chronic renal failure (CRF) and from sex- and age-matched controls. The CRF patients had raised fasting serum gastrin levels, whereas these were normal in the controls (mean, 290 +/- 283 (+/- SD) ng/l (n = 27) versus 33 +/- 36 (n = 30)). Serum gastrin values of the patients and controls correlated positively with G-cell density (r = 0.501, n = 36, p = 0.002), as did the maximal acid output of the CRF patients with parietal cell density (r = 0.617, n = 14, p = 0.019). In CRF patients the densities of G, parietal, and chief cells were higher than those in the controls (G cells, 351 +/- 151 (+/- SD) cells/mm2, n = 21 versus 211 +/- 90, n = 16, p = 0.002; parietal cells, 299 +/- 94, n = 15 versus 224 +/- 72, n = 14, p = 0.025; chief cells, 886 +/- 346, n = 15 versus 743 +/- 182, n = 14, p = 0.181). The results agree with previous findings indicating that hyposecretion of gastric acid in CRF does not derive from decreased capacity for acid secretion but rather from the inhibition of acid output. Increased parietal cell density in CRF patients gives cause to suspect that the maximum acid output might even in raised, possibly depending on the permanent hypergastrinaemic state with its trophic influence on the gastric body mucosa.

Adult↗
PubMed1989

Serum gastrin in chronic renal failure: its relation to acid secretion, G-cell density, and upper gastrointestinal findings.

The interrelations among fasting serum gastrin, serum creatinine, gastric acid secretion variables, and G-cell densities were analyzed in 47 patients with chronic renal failure (CRF). The patients also underwent gastroscopy and radiologic upper gastrointestinal barium examination. It is suggested that the hypergastrinemia seen in CRF is related to several factors: gastric acidity, grade of renal failure, G-cell density, and basal gastrin secretion rate. With regard to serum gastrin two different populations can be found, the cutting-off point being 300 ng/l. Although the group with high gastrin levels included significantly more patients with gastric body atrophy than the other group (4 of 11 versus of 1 of 36), most of them had no atrophy, which indicates that (an)other mechanism(s) is responsible for the hypergastrinemia. In the relation between serum gastrin and gastric acidity also, two differently behaving subgroups emerged. In the first, strong acidity change corresponded to minor gastrin change, whereas in the other, minor acidity change corresponded to marked gastrin change. The correlation coefficients between gastrin and acidity were high within both subgroups. During regular dialysis patients preserve the characteristics delineated from non-dialyzed values. Patients with signs of duodenal ulcer disease had high maximal acid output and low serum gastrin. Otherwise no associations were found between GI findings and the variables studied.

Cell Division↗
PubMed1988

Adrenal pheochromocytoma-ganglioneuroma producing catecholamines and various neuropeptides.

A 65-year-old woman presenting with back pain, difficulties in walking and watery diarrhea. A right adrenal tumor and high excretion of catecholamines were found. Laboratory examinations showed raised levels of vasoactive intestinal polypeptide, pancreatic polypeptide, gastrin and calcitonin. Histology showed a combined pheochromocytoma-ganglioneuroma. The neoplastic cell population was immunohistochemically shown to contain tyrosine hydroxylase, neuropeptide Y, met-enkephalin, substance P, vasoactive intestinal polypeptide, calcitonin and calcitonin gene-related peptide. Postoperatively, the patient recovered fully and the hormone levels returned to normal.

Adrenal Gland Neoplasms↗
PubMed1988

Reduced thickness of gastric mucosa and retarded progression of chronic gastritis in patients with renal failure.

Conflicting results are reported in the literature on the structure and function of gastric mucosa in patients with chronic renal failure (CRF). In the present endoscopic study of 68 CRF patients on conservative treatment (regular dialyses or transplantations had not yet been undertaken), we sought to clarify whether CRF leads to hypertrophic or hypotrophic phenomena in gastric mucosa, as interpreted by the presence and grade of gastritis and by the thickness of the gastric mucosa. We found that the mean progression of gastritis in both antrum and body was significantly slower than expected in CFR patients, and that the thickness of both antral and body mucosa was significantly lower in CFR patients than in non-CRF controls. Furthermore, although the thickness of the oxyntic body mucosa in CRF showed a positive correlation to serum gastrin (SeGa) levels and even though 12 of the patients showed high SeGa levels corresponding to those seen in the Zollinger-Ellison synbdrome (300-1500 ng/l), the thickness of the oxyntic body mucosa in CRF patients did not exceed that seen in control subjects with normal SeGa. We conclude that CRF exerts inhibitory effects on the gastric mucosa resulting in retardation in the progression of chronic gastritis and hypotrophy of the gastric mucous membrane.

Adult↗
PubMed1988

Increased incidence of duodenitis in chronic renal failure.

Forty-six consecutive patients with chronic renal failure (CRF) were assessed radiographically, endoscopically and histologically for duodenal inflammation. Their gastric secretion was also examined. Thirty-eight patients with non-ulcer dyspepsia served as controls. Histologically established duodenitis was more common in CRF patients than in controls. Among the non-dialyzed patients its prevalence reached 28% (9/32), while in the controls it was 5% (2/38) (p less than 0.05). The CRF patients with duodenitis had upper GI symptoms, hypersecretion of acid (p less than 0.05) and duodenal ulcer disease (p less than 0.05) more frequently compared with the CRF subjects with normal duodenal mucosa. The correlation of radiographically and endoscopically detected duodenitis with that found microscopically was poor.

Adult↗
PubMed1985

Bone growth into glassy carbon implants. A rabbit experiment.

This study was designed to evaluate the growth of bone into porous glassy carbon cylinders. Porous carbon cylinders were implanted in 30 rabbits intra-articularly in the metaphysis of the femur opposite from the patella. The rabbits were sacrificed up to 24 weeks after the operation. The bone samples were examined by histologic, fluorochrome and microradiographic methods. The amount of bone ingrowth was measured histomorphometrically. Fluorochrome uptake was seen in the implant pores, which indicated new bone growth originating from surrounding bone. After 3 weeks, microradiographs revealed new bone formation in the pores and with time the bone spicules became more dense. The amount of bone tissue in the pores grew and reached a maximum at 12 weeks, when 45 per cent of the total pore volume was incorporated with bone tissue. No adverse tissue responses were observed.

Animals↗
PubMed1985

Immunohistochemical localization of human liver specific protein using rabbit antisera and the avidin-biotin complex technique.

A sensitive enzymatic avidin-biotin complex technique was utilized to locate the antigenic sites in human liver which react with rabbit antibodies to human liver specific protein (LSP). Depending on the rabbit antiserum used, anti-LSP reactive material was seen in different locations. (1) diffusely distributed in liver parenchymal cells, (2) in both hepatocyte cytoplasm and plasma membrane and (3) in hepatocyte plasma membrane only. The cytoplasmic staining was partially or totally abolished by preabsorption with human kidney homogenate whilst the plasma membrane staining remained uninfluenced. The latter was apparently confined to bile canalicular walls and may be liver specific in contrast to the cytoplasmic reaction which seems to be due to antigen determinants cross-reacting with tissue components in kidney.

Animals↗
PubMedDate not supplied

Vitamin D and calcitonin treatment in patients with femoral neck fracture: a prospective controlled clinical study.

The effects on general and bone metabolism of femoral neck fracture patients of 0.25 micrograms alpha-calcoid given orally twice daily (n = 9) and 25 micrograms calcitonin given subcutaneously 30 times (n = 10) in 10 weeks were studied against a control (n = 11). Bone histology and histomorphometry showed non-age related osteoporosis in 30% and osteomalacia in 22% of the patients studied. Impaired serum vitamin D status was found in 47-88% of patients, secondary hyperparathyroidism and increased serum parathyroid hormone in 59% and decreased serum calcitonin levels in 69%. On histology, normal findings and non-age related osteoporosis on histology were associated with low serum levels of 25-hydroxyvitamin D3, 1,25- and 24,25-dihydroxyvitamin D3. Very high serum levels of 1,25-dihydroxyvitamin D3 and low levels of 25-hydroxyvitamin D3 occurred in fracture patients with osteomalacia. Calcitonin improved calcium balance, reduced osteoporosis and increased the serum 1,25- and 24,25-dihydroxyvitamin D3 levels but had no effect on osteomalacia. Vitamin D reduced osteomalacia, slightly increased the serum 1,25-dihydroxyvitamin D3 concentration and decreased serum levels of parathyroid hormone. Both treatments gave a similar slight decrease in serum calcitonin concentrations. A mechanism of action for the treatments is suggested.

Aged↗