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Biomedical subjects

H Aro

Publications and source records attributed to H Aro.

At least 73 records · Page 4Linked to original sources
PubMed1987

Life stress and psychosomatic symptoms among 14 to 16-year old Finnish adolescents.

School children (N = 2013) completed questionnaires in class on three occasions over a period of 17 months. Life stress data for 12 months were gathered retrospectively in the last questionnaire. Life events and interpersonal problems were associated with psychosomatic symptoms. In terms of change in symptoms, the impact of life events and interpersonal problems was demonstrated in boys but not in girls. Though boys with a history of no events or problems had lower symptom scores than girls, boys with a history of many events or problems caught up with the girls by the end of the follow-up period. On the other hand, symptom differences related to life stress scores were already apparent at the beginning of the study, and these differences were greater in girls than in boys.

Adolescent↗
PubMed1987

The impact of timing of puberty on psychosomatic symptoms among fourteen- to sixteen-year-old Finnish girls.

All eighth-grade pupils of secondary schools in a Finnish town completed questionnaires 3 times during a 17-month follow-up. A total of 935 girls were included in the study. The mean age of the girls at the start of the study was 14.5 years. The results showed that there were differences in psychosomatic symptoms, dating, and alcohol use by age of menarche. However, the results suggested that the differences by age of menarche were largely associated with pubertal development as such. After controlling for time since menarche, the impact of timing on psychosomatic symptoms was demonstrated only at the beginning of the study, not later. Differences in behavior also seemed to be related to pubertal development rather than timing. Differences in symptoms by age of menarche remained after controlling for dating and alcohol use.

Adolescent↗
PubMed1986

Irradiation-induced hypoxia in bones and soft tissues: an experimental study.

Bone marrow and subcutaneous tissue pO2 and pCO2 were measured by means of implanted tissue tonometers in irradiated and nonirradiated rabbit hind limbs. The x-ray dose was 500, 1000, 1500, 2000, and 3000 rads. Tissue gas tensions were measured 1 day and 5 and 11 weeks after radiation. The pCO2 changes in both tissues were slight but not statistically significant. The subcutaneous tissue pO2 decreased during the acute phase of irradiation injury, and the effect of irradiation was dose-dependent. Later on, irradiation had no significant effects on the subcutaneous pO2, although light microscopy of the affected tissues showed fibrosis and blood vessel changes. The response of the subcutaneous pO2 to systemic hyperoxia also increased in the chronic phase of irradiation injury as a sign of improved microcirculation. The bone marrow showed a high radiosensitivity. Irradiation caused a rapid dose-dependent decrease of the marrow pO2, and the marrow pO2 decreased with time during the chronic phase of irradiation injury. The marrow pO2 responded slowly and marginally to an increment of arterial pO2 during breathing 100% oxygen as further evidence of impaired vascular pattern. The results showed that irradiation causes only a transient impairment of tissue perfusion in the skin. However, irradiation-damaged marrow was characterized by progressive tissue hypoxia.

Animals↗
PubMed1986

Conservative management of distraction-type stress fractures of the femoral neck.

Four military recruits with complete distraction-type stress fractures of the femoral neck were treated conservatively. The radiographic diagnosis was made within two weeks of the onset of symptoms and the activities of the patients were matched to the clinical and radiographic progress of fracture healing. None of the fractures displaced and union occurred uneventfully. Our experience suggests that prophylactic internal fixation of these fractures is not necessary.

Adult↗
PubMed1985

Determination of callus quantity in 4-week-old fractures of the rat tibia.

In clinical practice the quantity of fracture callus is usually estimated on the basis of radiographs. In experimental studies on fracture healing, more exact chemical measurements (total protein, DNA, and mineral contents) have been used to quantitate the amount of callus. It is not known, however, how these two parameters correlate with each other. In this study we used different (radiographic, histomorphometric, and chemical) methods to evaluate the quantity of fracture callus in 4-week-old tibial fractures of rats stabilized by intramedullary nailing. The wet and dry weights and the nitrogen, collagen, calcium, phosphorus, and DNA contents of the calluses showed no correlation with the radiographic size of the calluses. There was a strong correlation (p less than 0.001), however, between radiographic and histomorphometric callus sizes. The mass of callus and the chemically defined parameters of callus production thus indicate different properties of the healing bone.

Animals↗
PubMed1985

Changes in intramuscular collagen and fibronectin in denervation atrophy.

The distribution of collagen types I, III, and V and fibronectin was investigated by means of immunofluorescent techniques in denervated and normal rat skeletal muscle. During a period of 28 days, a distinct atrophy developed in the denervated gastrocnemius muscle and was accompanied by an increase in types I and III collagen in the endomysium and perimysium. The amount of type V collagen showed little change, whereas fibronectin increase closely parallelled types I and III collagen. The results indicate that denervation atrophy in muscles is accompanied by striking fibrotic changes due to mesenchymal types I and III collagen.

Animals↗
PubMed1985

Endoneurial fibrosis following nerve transection. An immunohistological study of collagen types and fibronectin in the rat.

Indirect immunofluorescent techniques with antibodies to type I, III, and V collagens and fibronectin were used to study rat sciatic nerve tributaries after transection with intact contralateral nerves as controls. Codistribution of type I and III collagens characterized the epineurium of normal nerve. In the perineurium, however, type I collagen was absent, but type III and V collagens and fibronectin were detected. Type I and III collagens were codistributed in the endoneurial stroma where a homogeneous staining by antibodies to fibronectin was also observed. During the 4-week observation period after transection the perineurium reacted by slight thickening which was most clearly demonstrated by staining with antibodies to fibronectin and to type V collagen. A widening of the type I-negative cleft also occurred. Endoneurial, type V collagen-positive cuffs around the nerve fibers became disorganized, and a concomitant increase of the stroma containing type I and III collagens and fibronectin was observed. The codistribution of the fibrous collagen types appeared similar in normal epineurium and endoneurium. Type V collagen was located in the perineurium and in endoneurial cuffs surrounding the nerve fibers. The present data indicate that collagen accumulation takes place in the perineurium and endoneurium of transected nerve. The cell type responsible for the synthesis of the connective tissue material is discussed.

Animals↗
PubMed1985

Fracture healing in paraplegic rats.

In paraplegic rats, histomorphometric and chemical methods were used to evaluate callus production in tibial fractures stabilized by intramedullary nails. There were no differences in the mean sizes of fracture callus between paraplegic rats and their non-weight-bearing and weight-bearing controls. However, the variance of callus size was large in paraplegic rats. The concentration of nitrogen was high in calluses of paraplegic rats during the cartilaginous stage of healing. The hydroxyproline concentration did not differ between the groups. The rate of callus ossification was more rapid in paraplegic rats than in controls, but fracture calluses of paraplegic rats showed delayed accumulation of calcium and incomplete maturation of woven new bone. The results suggest that there are both mechanical and non-mechanical factors affecting callus formation in fractures below a spinal lesion.

Animals↗
PubMed1985

Effect of nerve injury on fracture healing. Callus formation studied in the rat.

In an attempt to determine the effects of peripheral nerve lesions on fracture healing, radiographic, histomorphometric and chemical methods were used to evaluate callus formation in tibial fractures of rats with sciatic denervation. Fracture union by bridging external callus was more rapid in denervated limbs than in controls. By contrast, external calluses of denervated fractures were smaller and less dense and contained less collagenous matrix (hydroxyproline) and minerals (calcium, phosphorus) than controls. The RNA/DNA ratio decreased more rapidly in denervated calluses than in controls. Mineralization of collagenous matrix (estimated from the calcium/hydroxyproline ratio) was not affected by denervation.

Animals↗
PubMed1985

Development of nonunions in the rat fibula after removal of periosteal neural mechanoreceptors.

Periosteal proprioceptive nerve receptors may act as mechanoreceptors of long bones during adaptive remodeling after fracture. They may also contribute to the mechanisms of coordinated functional activity of fractured limbs and thus inhibit harmful overloading of fracture callus. The area of proprioceptive nerve receptors around the distal part of the rat fibula was stripped surgically, and a standard fracture of the fibular shaft was produced. Animals failed to unite their fractures and developed mainly atrophic nonunions. Atrophy of ununited fragments was due to osteoclastic bone resorption. Atrophy of the bone fragments was aggravated if the legs were also subjected to sciatic denervation. Sciatic denervation alone, without removal of receptors, did not interfere with the union of fractures. The results indicate that the area of proprioceptive receptors in the rat tibiofibular bone is critical for the healing of fibular fractures. Because the effect on bone healing of receptor removal was not inhibited by sciatic denervation, the effect was not transmitted through spinal pathways of the sciatic nerve. The development of nonunions could not be explained by the surgical trauma alone. Aggravation of fibular atrophy by sectioning of the sciatic nerve suggests that some neural elements are associated with the phenomenon, either directly or indirectly through neuromuscular function.

Animals↗
PubMed1984

Electrostimulation of rat callus cells and human lymphocytes in vitro.

Asymmetrical pulsing low voltage current was supplied via electrodes to cultured rat fracture callus cells and human peripheral blood lymphocytes. The [3H]thymidine incorporation of the callus cells and 5-[125I]iodo-2'-deoxyuridine incorporation of the lymphocytes were determined. The growth pattern of callus cells (estimated by cellular density) did not respond to electrical stimulation. However, the uptake of [3H]thymidine was increased at the early phase of cell proliferation and inhibited at later phases of proliferation. The [3H]thymidine uptake of confluent callus cell cultures did not respond to electrical stimulation. Lymphocytes reacted in a similar way; stimulated cells took up more DNA precursor than control cells at the early phase of stimulation. During cell division, induced by the mitogens phytohemagglutinin and Concanavalin-A, the uptake of DNA precursor by stimulated cells was constantly inhibited. The results suggest that electrical stimuli affect the uptake mechanisms of cell membranes. The duality of the effect seems to be dependent on the cell cycle.

Animals↗
PubMed1984

Experimental osteosynthesis with liquid ethyl cyanacrylate polymerized with ultrasound.

Ethyl cyanacrylate (Cyacrine) was used as bone cement in osteosynthesis of experimental osteotomies. The osteotomies were produced in the scapulas of rabbits by detaching a rectangular fragment with an ultrasonic bone saw. The control osteotomies were immobilized by steel wire fixation. The control fragments united uneventfully. The experimental osteotomies were fixed with a mixture of bone chips and liquid Cyacrine, polymerized in situ with ultrasound. No adjunctive fixation was used. Stable fixation was difficult to obtain. Further, healing of the osteotomies consistently failed because of inhibited new bone formation on surfaces in contact with Cyacrine. Cyacrine also provoked a prolonged inflammatory reaction with round cell and macrophage infiltration in the region of the osteosynthesis.

Animals↗
PubMed1984

Tissue oxygen tension in externally stabilized tibial fractures in rabbits during normal healing and infection.

Permanently implanted Silastic tonometers were used to measure average extracellular oxygen tension in the medullary cavity of osteotomized rabbit tibias stabilized with external pin fixation. During uncomplicated healing the baseline bone pO2 rose slowly with time from 10 to 20 mm Hg while during staphylococcal infection pO2 varied between 8 and 15 mm Hg and showed no correlation with the healing time. The maximal response of the bone pO2 to oxygen breathing correlated linearly with the healing time whether the osteotomy was infected or not. On the 42nd day the maximal pO2 during systemic hyperoxia was 85 mm Hg for the control bones, 42 mm Hg for the osteotomized bones, and 30 mm Hg for the infected osteotomized bones. The results indicate moderate bone tissue hypoxia during uncomplicated healing and more profound hypoxia during healing affected by infection.

Animals↗
PubMed1984

Cystic osteolysis induced by silicone rubber prosthesis.

Synovitic symptoms and radiologically documented cystic lesions in several carpal bones and distal radius developed two years after the implantation of silicone rubber scaphoid prosthesis for pseudoarthrosis. Open biopsy revealed granulomatous synovitis and osteitis and foreign material in carpal tissues. Ultrastructurally dense material was found in the cytoplasm of histiocytic, often multinucleated cells. Electron-probe analysis of the material showed a definite peak for silicon, proving the causal relationship of symptoms and signs to the silicone rubber prosthesis.

Adult↗
PubMed1982

Osteolysis after rigid fixation. The possible role of periosteal neural mechanoreceptors in bone remodeling.

Rigid intramedullary fixation in the rat tibiofibular bone of a tibial fracture caused the development of nonunion in the associated fibular fracture, with marked osteolytic resorption of the fibular fragments. In contrast, with flexible fixation, the associated fibular fracture healed normally. The tibial fractures healed uneventfully in both cases. Histologic examinations showed that there exists a plexus of encapsulated nerve endings (Pacinian corpuscles) in the periosteum of the fibula, at the distal tibiofibular junction. The rat fibula forms a bony contact with the lower midshaft of the anteriorly curved tibia, acting as a supporting shaft. The periosteal neural mechanoreceptors probably sense the fibular loading when the tibia is bent during weight-bearing. Fibular resorption in rigid fixation could be attributed to the rigid intramedullary nail preventing tibial bending and loading of the receptor area. In other words the neural elements could detect the stress protection due to rigid fixation and coordinate the adverse remodeling process.

Animals↗
PubMed1981

Ultrasonic device in bone cutting. A histological and scanning electron microscopical study.

The immediate and the long-term effects on bone produced by an ultrasonic cutting device and an oscillating saw were compared histologically and by scanning electron microscopy. The long bones and scapulas of rabbits were used as experimental material. By scanning electron microscopy the osteotomy surface produced by the ultrasonic saw was observed to be rougher than that produced by oscillating saw, but there were no microfractures. Histologically the early regeneration of the bone tissue was delayed to some degree after ultrasonic cutting, but the regeneration process as a whole was found to be the same after cutting with either of the saws.

Animals↗
PubMed1980

Asymmetric biphasic voltage stimulation of the osteotomized rabbit bone.

An experimental study was performed to determine the effect of electric current on the healing of osteotomies in the antebrachium of the rabbit. Starting with the assumption that the waveform of biphasic asymmetric voltage simulates the asymmetric pattern of stress-induced physiological electrical potentials in normal bone, biphasic asymmetric voltage was applied to the osteotomized radius or ulna. The effects of the electrical stimulation were evaluated by means of X-rays and histological studies. The voltage supplied induced periosteal proliferation whether implanted, insulated electrodes were employed or uninsulated external transfixation pins were used as electrodes. The stimulation had not only osteogenic but also chondrogenic effect. The external callus formation at the osteotomy sites and around the transfixation pins proved to be greater in the stimulated animals than in the controls.

Animals↗