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Biomedical subjects

J I Peltonen

Publications and source records attributed to J I Peltonen.

9 recordsLinked to original sources
PubMed1995

[Growth plate in primary osteochondritis dissecans of the hip: a prospective study with MRI].

INTRODUCTION: In Perthes' disease, epiphyseal necrosis impairs the function of the growth plate and may result in growth disturbances of the femoral neck. The physeal changes during active disease were prospectively evaluated with magnetic resonance imaging (MRI). MATERIALS AND METHODS: MRI was performed and radiographs were obtained with six-month intervals from the time of diagnosis up to two years in nine hips (eight patients). RESULTS: Normal growth plate was seen in MRI as a stripe of low signal intensity between areas of high signal intensity from the epiphysis and the metaphysis. Distortion, widening and partial disappearance of the growth plate were noted in the hips classified into Catterall groups 3 and 4. The physeal distortion was seen as anterior curling, and, in some hips, as a W-shaped abnormality projecting down into the metaphysis. Delayed growth of the femoral neck, due to premature physeal closure, was noted in hips where the physeal deformation involved more than half of the growth plate. All pathological changes appeared on the MRI scans three to fifteen months after the first symptoms. The extent of the MRI changes did not correlate directly with Catterall's plain film staging. DISCUSSION: The distortion and widening of the growth plate seen in MRI probably reflect histological disarrangement of the physis due to an extensive epiphyseal necrosis. The physeal W-formation in MRI may represent a radiographic "metaphyseal cyst". Disappearance of the growth plate in MRI seems to indicate premature closure of the physis. CONCLUSION: It seems possible to predict premature closure with MRI even within fifteen months after the onset of Perthes' disease.

Child↗
PubMed1994

Early bone matrix formation during distraction. A biochemical study in sheep.

Osteotomy of the distal radius and gradual distraction were performed on 20 sheep. Bone matrix synthesized between the osteotomized bone ends was biochemically characterized at 3, 5, 7, and 14 days after the start of distraction. The deposition of mineral was negligible during the 14-day period. No change was observed in the amount of organic matrix, which comprised 15 +/- 1.4 percent of the wet weight of the tissue. The amount of total protein of the wet weight in the matrix increased from 4.6 to 7.6 percent between 5 and 7 days of distraction. During the first 7 days, the nonprotein component decreased from 11 to 7.3 percent. The proportion of collagen of the total matrix protein increased gradually from 29 to 59 percent. In view of the patterns of the cyanogen bromide peptides of the matrix proteins, the heteropolymer type I[1(I)2(2)(I)1] collagen was consisted to be the principle fibrillar collagen synthesized in the distraction gap. The results suggest that tension-stress markedly affects the synthesis of fibrillar collagen towards the formation of mature bone matrix. In this process, a preliminary lag phase probably exists during which the capacity for protein synthesis is low while the synthesis of Type I collagen has started. In the secondary phase an augmented synthesis of Type I collagen takes place.

Animals↗
PubMed1992

Cementless hip arthroplasty in diastrophic dysplasia.

Diastrophic dysplasia results in severe disproportionate growth failure, generalized joint dysplasia, and early osteoarthrosis of the hips. A total hip arthroplasty is often necessary in patients afflicted with diastrophic dysplasia by time they reach early middle age. During 1983-1988, total hip arthroplasties were performed on six women and four men (15 hips) with diastrophic dysplasia at the Orthopaedic Hospital of the Invalid Foundation. The mean age of the patients at the time of operation was 37 years and the mean height was 133 cm. A Lord endoprosthesis was used in nine hips and a Biomet endoprosthesis in six. Cementless fixation was used in all cases. Autogenous bone grafting to the acetabulum was performed in six hips. Simultaneous corrective osteotomy of the proximal femur and transposition of the greater trochanter was performed in three cases. Soft tissue release and tenotomies were performed in 10 hips. The average follow-up period was 5 years. Overall clinical results were good, with marked relief of pain and improvement of hip joint mobility. Aseptic loosening of the acetabular component was noted in two hips. As for complications, two femoral nerve paresis and two perioperative fractures of the proximal femur occurred, which all healed.

Adult↗
PubMed1992

Bone formation after distraction osteotomy of the radius in sheep.

Gradual distraction by external fixation was performed one week after osteotomy of the radius in 12 sheep. Bone regeneration in the distraction area was studied by light and electron microscopy. One week after starting the distraction the gap was composed of hematopoietic cells and fibroblasts. The collagen production had already started and it continued actively throughout the distraction period. The collagen produced by the fibroblasts in the central interzone of the gap was organized according to the direction of the distraction. The osteoblasts were lined up along the collagen bundles and osteoid formation was most active around the capillaries. Mineralization started two weeks after the beginning of the distraction. After cessation of the distraction, separate groups of cartilaginous cells were found in some specimens among the newly formed bone. Our findings suggest that osteogenesis as a result of gradual distraction occurs through the whole distraction area with preceding formation of organized collagen matrix. The bone structure in the distracted segment represents an organized lamellar structure at an early stage of the osteogenesis.

Animals↗
PubMed1984

Experimental epiphysial distraction producing and correcting angular deformities.

Angular deformities of the distal radius of 15 sheep were induced by asymmetrical epiphysial distraction. Eleven sheep were between 10 and 20 weeks old; four were older than 24 weeks. Gradual distraction on the medial side of the limb caused partial separation of the epiphysis from the metaphysis, resulting in a valgus deformity. The distraction device was removed three to six weeks after insertion. Spontaneous correction of angulation with growth occurred in the younger sheep; but when the induced valgus angle exceeded 20 degrees correction was poor. In two sheep further distraction was applied on the lateral side and this produced complete correction. Premature closure of epiphyses did not occur after distraction and longitudinal growth of the bone remained normal. In the older sheep asymmetrical distraction succeeded in inducing angulation in only one case, and correction was poor.

Age Factors↗
PubMed1974

Effect of maternal intrahepatic cholestasis on fetal steroid metabolism.

Estriol, estriol sulfate, progesterone, and 17 neutral steroid sulfates, including estriol precursors and progesterone metabolites, were determined in 27 cord plasma samples collected after pregnancies complicated by intrahepatic cholestasis of the mother. The levels of these steroids were compared with those in the cord plasma of 42 healthy controls. In the cord plasma, the steroid profile after pregnancies complicated by maternal intrahepatic cholestasis differed greatly from that seen after uncomplicated pregnancy. Two main differences were found. In the disulfate fraction, the concentrations of two pregnanediol isomers, 5alpha-pregnane-3alpha,20alpha-diol and 5beta-pregnane-3alpha,20alpha-diol, were high after cholestasis. Other investigators have shown that, as a result of cholestasis, these pregnanediol sulfates circulate in greatly elevated amounts in the maternal plasma. Our results indicate that in cholestasis these steroids cross the placenta into the fetal compartment, where they circulate in elevated amounts as disulfates. Secondly, the concentrations of several steroid sulfates known to be synthesized by the fetus were significantly lower in the cholestasis group than in the healthy controls. This was especially true of 16alpha-hydroxydehydroepiandrosterone sulfate and 16alpha-hydroxypregnenolone sulfate. These results suggest that, in pregnancies complicated by maternal intrahepatic cholestasis, impairment of fetal steroid synthesis, and especially of 16alpha-hydroxylation, occurs in the fetal compartment.Thus, the changes in maternal steroid metabolism caused by cholestasis are reflected in the steroid profile of the fetoplacental circulation. Furthermore, maternal intrahepatic cholestasis may result in the production of some substance which crosses the placenta and affects fetal steroid metabolism.

17-alpha-Hydroxypregnenolone↗