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Biomedical subjects

I Alitalo

Publications and source records attributed to I Alitalo.

At least 19 recordsLinked to original sources
PubMed1990

Collagen synthesis and mineralization in the early phase of distraction bone healing.

Corticotomy of the distal radius followed by gradual distraction by external fixation was performed on three sheep. Collagen synthesis and mineral deposition were analysed from sequential biopsies obtained from the center of the distraction area during the first 4 weeks of distraction. The whole distraction area was rapidly filled with organic matrix the amount of which, due to fluctuation in its nonprotein component, initially decreased from 88 to 66% of the level in control bone but gained its initial level in 4 weeks. Total protein in the matrix represented 70% of that in the control bone during the 4-week follow up period while the proportion of collagen of the total protein increased from 53 to 88%, a level comparable with the unoperated bone. Determination of the type of fibrillar collagen by characterization of their cyanogen bromide peptides showed that in the distraction area production of type II collagen does not occur but the heteropolymer type I (alpha 1(I)2 alpha 2(I)1) collagen represents almost totally the collagen synthesized. Deposition of mineral into the distraction gap was detectable already after 2 weeks and increased rapidly after 3 weeks of distraction. The results suggest that unlike in other processes, e.g., direct osteonal and callus-type bone repair, in distraction bone healing gradual distraction of osteotomized bone leads directly to synthesis of mature fibrous organic matrix of bone followed by its rapid mineralization.

Animals↗
PubMed1988

Regeneration after physeal distraction of the radius in sheep.

In 18 sheep, gradual physeal distraction of the distal radius was performed by external fixation. Separation of the physis from the metaphysis occurred in all the sheep. Prior to bone formation, collagen fibers were organized according to the direction of the distraction, and lamellar bone was formed if the collagen bundles were lineally organized. In the area where the collagen was disorganized, and also near the periosteum, woven bone was first formed, which was then remodeled into lamellar bone. In some sheep separate groups of chondrocytes were isolated in the metaphyseal area after the distraction. In 2 animals a double physis was formed in the metaphyseal area. This was obviously due to the separation of proliferative chondrocytes in the metaphysis as a result of distraction. After consolidation of the distraction area, this zone of chondrocytes, located in the metaphysis, was still producing new bone 20 weeks postoperatively.

Animals↗
PubMed1988

Bovine bone morphogenetic protein (bBMP) induced repair of skull trephine defects in sheep.

An aggregate of partially purified bovine bone morphogenetic protein (bBMP) and bone matrix insoluble noncollagenous proteins (iNCP), weighing a total of 100 mg of lyophilized BMP/iNCP, was implanted using ultra thin gelatin capsules in skull trephine defects in adult sheep. One hundred milligram samples of freeze-dried bovine serum albumin (BSA) were similarly implanted for controls. In five sheep, the capsules were implanted in 18-20 mm trephine skull defects and also in posterior cervical muscle pouches for heterotopic controls. In two out of five sheep, the trephines were repaired with bone as early as four weeks after the operation. Eight to 12 weeks after surgery repair was complete in the other three sheep. In the control contralateral trephines, one-third to one-half of the defect was incompletely repaired. Neither the BMP nor the BSA control implants induced bone formation in the muscle. While the BMP/iNCP prepared from bovine bone consistently induced regeneration in skull trephine defects, only fibrous tissue and no extraskeletal bone was induced to form in cervical muscle pouches in sheep.

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↗
PubMed1984

Distraction of the growth plate. Experiments in pigs and sheep.

Distraction of the growth plate of the distal radius was performed on 15 pigs and 10 sheep of growing age. The separation of the plate from the metaphysis occurred within 4-6 days after the operation. The distraction rate was 1-1.5 mm/day and was continued for 1-3 weeks. Consolidation of the separation area occurred within 6 weeks. Oxytetracycline bone labelling showed that the ossification developed toward the centre of the separation line from the metaphysis and from the inner layer of the periosteum as well as from the physeal side. The growth of the bone continued after the distraction procedure and in most cases the growth plate was open when examined radiologically after the distraction.

Animals↗
PubMed1984

Experimental epiphyseal separation by torsional force.

Separation of the proximal tibial epiphysis from the metaphysis by torsional force was experimentally studied using cadaver bone preparations from 19 adolescent sheep. The energy needed to displace the epiphysis increased in correlation with an increase in the age of the animal. The separated epiphyseal and metaphyseal surfaces were examined using scanning electron microscopy. In the younger animals the separation line passed through the area of hypertrophied chondrocytes. In the animals more near skeletal maturity the separation occurred in a more sinuous fashion and also through spongious bone.

Age Factors↗
PubMed1984

The immediate effects of retrograde pancreatography on the pancreas.

Endoscopic retrograde pancreatography (ERP) may be followed by elevated serum amylase or occasionally by pancreatitis. This is said to be due to the irritating effect of contrast media (CM) or to the cation content of CM. We investigated the effect of intraductally injected CM (ionic CM with and without sodium, non-ionic CM) on the porcine pancreas. All types of CM as well as control media (saline, 7% sodium bicarbonate solution) produced small foci of histological pancreatitis, although without any clinical signs of pancreatitis.

Animals↗
PubMed1983

Flow-volume relations in coronary circulation and distribution of coronary flow into nutritional and non-nutritional compartments.

Simultaneous assessment of coronary flow and flow-volume relation makes it possible to evaluate the dilatatory responses of coronary vasculature. A new set up of methods for investigation of the coronary circulation was employed to study the nature of the coronary flow and volume responses to dipyridamole in dogs. The turnover rate of coronary blood, the reciprocal value of the mean transit time, can be accurately determined by computer simulation analysis of coronary dye dilution curves. After intravenous dipyridamole (0.5 mg/kg) both coronary turnover rate and electromagnetically assessed blood flow were observed to increase in parallel and to the same degree (+55%). This indicates that no increase in the coronary vascular volume and, accordingly, no significant overall coronary dilatation takes place. The effective coronary blood flow in relation to the myocardial oxygen consumption, i.e. the nutritional flow, and the myocardial oxygen consumption decreased by 25% concomitant to a corresponding fall in myocardial oxygen requirements. Thus, the increase in total coronary flow after dipyridamole is useless for myocardial metabolism, and may properly be denoted as luxury perfusion or throughput flow.

Animals↗
PubMed1983

Osteochondrotic changes in the vertebrae of four ataxic horses suffering from cervical vertebral malformation.

Ataxia caused by a focal compression of the cervical spinal cord was diagnosed in four young standardbred trotting horses. Diagnosis was verified by myelography. Changes in the cervical vertebral column were studied using microradiographic and histologic methods. In the vertebrae involved, there was irregularity of the cartilaginous growth zone, cracks with a loose fragment and disturbance in the enchondral ossification. These changes resemble osteochondrosis. Porous appearance in lateral and ventral funiculi as well as mural calcified plaques in the small vessels of the white matter were found in the spinal cord.

Animals↗
PubMed1977

Effects of atropine, isoprenaline, neostigmine and practocol on cardiac arrhythmias induced by potassium in anesthetized dogs.

Either atropine, isoprenaline, neostigmine or practolol was given intravenously in therapeutic doses to dogs anesthetized with pentobarbitone sodium. Cardiac arrhythmias were induced by potassium chloride intravenously as a bolus injection in a dose of 0.3 mmol/kg. The standard electrocardiographic lead II was recorded continuously. pH, Po2 and Pco2 were checked from arterial blood samples before and after the injection. The isoprenaline treated dogs showed the smallest amount of arrhythmias and all the dogs survived. More severe arrhythmias were seen in the neostigmine and practolol treated dogs and the most severe occurrences were encountered in the atropine treated dogs.

Animals↗