PubMed Health⌕ Search

Biomedical subjects

J U Lindgren

Publications and source records attributed to J U Lindgren.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effect of immobilization on skeletal muscle nicotinic cholinergic receptors in the rat.

The effect of 4 weeks of hind limb immobilization on nicotinic acetylcholinergic receptors (nAChRs) in the neuromuscular junction of the soleus (SOL) and tibialis anterior (TIB) muscles was studied in rats. Quantitative measurements of the receptors was performed using [3H]alpha-bungarotoxin ([3H]alpha-BTx) receptor autoradiography. Junctional and extrajunctional nAChRs were significantly increased in the SOL and TIB after 4 weeks immobilization. However, a significant decrease in fiber cross-sectional area was observed only in the SOL muscle. Remobilization for 4 weeks reversed the changes in cholinergic receptors and muscle fibers but not in bone. Our findings suggested that lack of nerve impulses are of importance for the events that take place after immobilization leading to muscle atrophy and osteoporosis.

Animals↗
PubMed1996

Remodelling and pain after uncemented total hip replacement.

We studied 70 patients after uncemented hip replacement with the Lord prosthesis which has a relatively long, completely macrotextured stem. The mean follow up was for 9.5 years. We compared radiographs at one year after operation, at 5 years and at the last follow up. Twenty-five patients (36%) had deep or circumferential pain in the thigh. Of the 44 who were most active at 5 years those with thigh pain had less proximal cortical loss than those without (p < 0.05), most cortical bone formation distally and most often had incomplete radiolucent lines at the mid-stem level, perhaps indicating more elastic displacement of the bone relative to the prosthesis. The presence of radiolucent lines correlated with the increase in cortical width at 5 years (p < 0.01). Cortical remodelling continued after 5 years at all levels except at the tip (p < 0.01). The relative elastic displacement at the interface could cause pain and may contribute to the pattern of bone remodelling in the femur after uncemented hip replacement.

Aged↗
PubMed1996

Outcome of total hip arthroplasties with cement. Results after implantation of the Harris Design 2 prosthesis, 1983-1985.

Most reports of excellent long-term results of cemented total hip arthroplasty originate from studies of Charnley prostheses. A radiographic and clinical study was performed on 126 patients who underwent a cemented total hip arthroplasty from 1983 to 1985 with the Harris Design 2 prosthesis (Howmedica, Rutherford, NJ). The femoral component was cobalt-chromium and it had a broad, rounded medial border and a collar. The head diameter was 26 mm. A cemented all-polyethylene socket was used in all cases. At the last follow-up examination, 71% of the patients were completely free of pain and no patient had severe pain or pain at rest. Kaplan-Meier survival analysis estimated the revision rate at 10 years after operation to be 5 +/- 2% (mean +/- SEM) (including planned revisions). The rate of complete acetabular demarcation was 20% at 10 years, and femoral demarcation involving more than 50% of the bone-implant surface or endosteal cavitation was noted in only three cases. These results are as good as the best reported after total hip arthroplasty with the Charnley prosthesis.

Adult↗
PubMed1995

Bone density in medieval skeletons.

We studied the most complete skeletons found in an excavation from the 14th and 15th century in central Stockholm. One hundred eighty-seven were from men and 156 from women: 241 individuals were estimated to be between 20 and 39 and 102 between 40 and 59 years old at death. We examined the bones radiographically and by dual photon absorptiometry. The bone mineral density (BMD) was similar to the finding in North America and Northern Europe today as was the relationship between men and women. However, there appeared to be a higher diaphyseal bone density in the lower extremities, especially in men. The femur score was higher and the BMD of the femoral and tibial shafts was higher than today. In the upper extremities the diaphyseal bone density was lower. Meema's index, as well as the metacarpal score, was smaller than in individuals in this century and the BMD of the humeral shaft was also lower than seen today. Overall, the metaphyseal bone density was similar to what we now consider normal; i.e., the mean BMD of the femoral neck was 0.96 g/cm2 in men and 0.90 g/cm2 in women and of the distal radius 0.43 and 0.32 g/cm2, respectively. The low diaphyseal density and in the upper extremities may be related to the nutritional status, whereas the greater need for walking and standing in the 14th and 15th century might have led to the high diaphyseal density in the lower extremities. There was no evidence of bone loss after 40 years of age in either sex in our study. The average expected lifespan for an adult individual was less than 50 years and we suggest that the relatively high bone density in the older age group may be due to selection of the most physically fit. The activity pattern, therefore, may be considered the most important determinant for the differences.

Adult↗
PubMed1995

Total hip replacement and cancer. A cohort study.

The incidence of cancer after hip replacement was studied in the 1.6 million inhabitants of Stockholm County, Sweden. A cohort of 10,785 individuals who had had hip replacement between 1974 and 1988 was followed from the date of operation to the first malignant tumour, to death, or to the end of 1989. The follow-up was based on 58,437 person-years at risk as calculated from information obtained by record-linkage with the National Cancer Registry and the National Cause-of-Death Register. The Standardised Morbidity Ratio (SMR) for all cancer sites, disregarding the length of follow-up, was 0.96 (95% CI 0.90 to 1.03). For lymphoma and leukaemia the corresponding SMR was 0.89 (0.68 to 1.14). Our results do not support previous suggestions of an increased incidence of leukaemia and lymphoma after total hip replacement.

Adult↗
PubMed1994

Treatment of chronic tibial osteomyelitis, segmental bone loss, and soft tissue defect by bone transplant.

New methods of treatment have greatly improved the success of limb salvage in severe lower extremity trauma. We report the use of a microvascular free tissue transfer and distraction osteogenesis in the reconstruction of soft tissue and bone defects complicated by infection. Soft tissue coverage and bony stabilization by external fixation resulted in eradication of the infection. The external fixator also allowed bone transport and regeneration to overcome a bone defect of approximately 6 cm. Bone transportation can be accomplished in a distal to proximal direction if the situation necessitates it. These techniques are extremely versatile and useful in the treatment of bone and soft tissue defect.

Adult↗
PubMed1993

Combined treatment with calcitonin and 1,25-dihydroxyvitamin D3 for osteoporosis in women.

Twenty-two middle-aged women with severe osteoporosis were treated for 2 years with either 0.5 mg of synthetic human calcitonin subcutaneously three times per week combined with 0.5 micrograms of calcitriol and 0.5 g of calcium per day orally or calcium only. The treatment with calcitonin plus calcitriol (12 patients) resulted in a significantly increased calcium absorption rate. The mean values for serum phosphate did not change during the treatment period and the mean values did not differ between the treatment groups, but the serum calcium and urinary Ca/Cr ratio increased somewhat in the group given the combined treatment. There was no evidence that the combined treatment improved the bone density in this study. It is possible that calcitriol, instead of increasing the effect of calcitonin by suppression of the parathyroid, might have counteracted its effect by increasing the bone resorption.

Absorptiometry, Photon↗
PubMed1992

Restoration of femoral offset during hip replacement. A radiographic cadaver study.

Restoration of femoral offset is an important part of total hip arthroplasty. Since radiographs showing the femur at a sufficient degree of internal rotation to allow direct measurement of femoral offset are not usually available, templates of the prosthesis at 25 and 45 degrees of rotation were created. Radiographs of 20 cadaver femurs with a mean offset of 44 +/- 5 mm (r 36-56) were then obtained at different degrees of rotation. Simple guidelines to indicate the correct template for each projection of the femur were found. The system could be used to select a prosthesis with correct offset using radiographs obtained at angles of rotation between 20 degrees internally and 40 degrees externally.

Cadaver↗
PubMed1991

Corrosion of modular hip prostheses.

Nine uncemented hip prostheses of modular design were revised because of late infection (2 cases), femoral stem loosening or fracture (2), loosening of threaded cups (3) and protrusion of bipolar cups (2). At surgery we found tissue discoloration and macroscopic corrosion in four of the nine prostheses, located at the head-neck junction. Histological examination in most cases showed extensive necrosis associated with metal particles, indicating metal toxicity. Metallographic examination of the prosthetic heads revealed structural imperfections and inhomogeneity of the metal. We suggest that the crevice between the head and neck is a potential site of corrosion in modular designs.

Adolescent↗
PubMed1989

Prediction of vertebral strength by dual photon absorptiometry and quantitative computed tomography.

We measured the lumbar bone mineral of 19 cadavers (10 women, 9 men) by dual photon absorptiometry (DPA) and quantitative computed tomography (QCT). In addition, we determined the ultimate load and stress of each vertebra, and finally ash content and volumetric ash density of the vertebral body. We found that single energy QCT was inferior to DPA and dual energy QCT in the prediction of the ultimate load or stress of vertebrae (P less than 0.001). The ultimate stress was best predicted by using the dual energy QCT results (r = 0.71; SEE = 36.3 N/cm2) whereas the ultimate vertebral load was best predicted by using the DPA (BMC) results (r = 0.80; SEE = 740 N). If the QCT finding was multiplied with the surface area of the vertebral body it could be used to predict the ultimate load with good accuracy (r = 0.74; SEE = 841 N). All the above correlations were higher in women than in men. The frequency of vertebral compression fractures in the material was well correlated with the bone mineral findings. A nonlinear (third degree) relationship between mineral content and mechanical characteristics is proposed but within the area of measurement used in clinical practice a linear (first degree) equation is preferred.

Aged↗
PubMed1989

Outcome of falls in women: endogenous factors associated with fracture.

Thirty-six women who had sustained soft-tissue injury after a simple fall were compared with age-matched controls who had suffered a fracture in a similar fall. Subjects aged 45-70 years who had suffered a fracture had significantly lower bone density in the proximal femur and lower grip strength than their controls. No differences in femoral bone density or grip strength were found between the two groups at ages over 70, but the women with fractures were on average of greater body weight than the no-fracture group. Bone mineral density declined more rapidly with age and was less closely correlated with body weight and time since menopause in the no-fracture group than among the women with a fracture. We conclude that the determinants of fracture vary with age; low bone density and low muscle strength are associated with fracture below the age of 70 but not at higher ages.

Accidental Falls↗
PubMed1987

Tissue reactions to wear products from polyacetal (Delrin) and UHMW polyethylene in total hip replacement.

The tissue reaction to implanted materials and their wear products is important for the long-term fixation of a total hip replacement (THR). Recent reports indicate a relatively high incidence of aseptic loosening with Christiansen total hip prostheses. We examined tissue reactions to wear products in two groups of prostheses: 16 Christiansen prostheses with polyacetal (Delrin) sockets, and 18 Charnley-Müller total hip prostheses with ultrahigh-molecular-weight polyethylene (UHMWP) sockets. Specimens from these 34 patients were compared in a combined qualitative and semiquantitative morphological study. We saw similar histological changes in specimens of both groups, but specimens from the bone-cement interfaces of the acetabulum and femur shaft in the polyacetal group showed more inflammation and necrosis.

Acetals↗
PubMed1987

Apparent absence of local response to bone screws in guinea pigs with contact sensitivity.

Guinea pigs sensitized to nickel, cobalt, or chromium were used to study if impaired fixation occurred as a result of allergy against metal implants in bone. Screws made from stainless-steel (ASTM F55, F138-139) or cobalt chromium (ASTM F75-76) were inserted in the right and left proximal tibiae, and the mechanical strength of the fixation to the bone was evaluated after 4 months. In addition, we studied the histology on decalcified sections of the implant bone interface from the distal femur where the same type of screws had been inserted. To see if changes in bone density occurred in the proximal tibia as a result of allergy, the amount of ash was determined. Although the animals maintained their contact sensitivity throughout the experimental period, there were no differences between allergic and control animals for any of the parameters studied. All screws were well fixed in the tibia at the end of the experiment, and histologically we did not find any significant differences between allergic and control animals by qualitative examination. The experiment supports our earlier results from a 6-week experiment and indicates that contact allergy may be unimportant for the fate of orthopedic implants.

Animals↗
PubMed1987

Effects of anti-estrogens on bone in castrated and intact female rats.

The effects of the antiestrogens tamoxifen and keoxifene on the bone density of intact and ovariectomized female rats were determined after 4 months of therapy. The antiestrogens did not cause a decrease in bone density in intact animals, although uterine wet weight did decrease. Ovariectomy caused an increase in body weight (25%) and a significant decrease in femur density (P less than 0.01). Antiestrogens did not further decrease the bone density of ovariectomized rats but rather helped to maintain bone density. Antiestrogens as well as estrogen (oral estradiol benzoate 25 micrograms daily) helped to maintain bone density in the range observed for the intact rats, but inhibited estrogen stimulation of uterine weight. These contrasting pharmacological actions of antiestrogens suggest that patients receiving long-term adjuvant tamoxifen therapy for breast cancer should be evaluated to determine whether tamoxifen can retard the development of osteoporosis.

Animals↗
PubMed1985

The effect of 1 alpha-hydroxyvitamin D2 on calcium metabolism in glucocorticoid-treated rats.

Intestinal calcium transport and renal calcium and phosphate excretion have been measured in normal and prednisolone-treated rats. Prednisolone treatment reduced intestinal calcium transport and increased phosphate excretion, causing a reduction in serum phosphate. Both 1 alpha-hydroxyvitamin D2 and 1 alpha-hydroxyvitamin D3 normalized phosphate excretion, whereas 1 alpha-hydroxyvitamin D3 was not fully effective in serum phosphate. Prednisolone treatment also caused a decreased bone density that was prevented both with 1 alpha-hydroxyvitamin D2 and 1 alpha-hydroxyvitamin D3. 1 alpha-hydroxyvitamin D2 appeared at least as effective as 1 alpha-hydroxyvitamin D3 in correcting the bone disturbance.

Animals↗
PubMed1984

Effects of 1,25(OH)2D3 on bone tissue in the rabbit: studies on fracture healing, disuse osteoporosis, and prednisone osteoporosis.

A closed tibial fracture, which was controlled by an intramedullary stainless steel pin, was created in 16 rabbits. Eight rabbits were treated with 75 ng of 1,25(OH)2D3 daily as subcutaneous (s.c.) injections. After three weeks, the fractured tibia resisted a force of 101.7 +/- 21.0 Newtons in the control group and 57.3 +/- 8.0 Newtons in animals given 1,25(OH)2D3 (m +/- SE, P less than 0.05). In another group of eight rabbits, the left hindleg was immobilized in a plastic splint. Four rabbits were given 75 ng of 1,25(OH)2D3/day s.c. and the effect of immobilization was studied on the calcaneus. Bone ash/cm3 of the calcaneus on the immobilized side was decreased by 11 +/- 2% in control rabbits and by 20 +/- 2% in the group treated with 1,25(OH)2D3 indicating a more advanced immobilization osteoporosis (m +/- SE, P less than 0.05), which was also demonstrated by studies of bone density. Eighteen rabbits were used in a study of the effects of 1,25(OH)2D3 on the development of prednisolone osteoporosis. The dose of prednisolone was 2.5 mg per day, given by the oral route. After four months, the density of the femur was 1.53 +/- 0.02 g/cm2 in control rabbits and 1.42 +/- 0.01 in prednisolone-treated animals (P less than 0.01). In rabbits additionally given 1,25(OH)2D3, the mean value for bone density was further lowered (n.s.). It appears that 1,25(OH)2D3 exaggerates disuse osteoporosis and prednisolone osteoporosis and impairs fracture healing in rabbits. These results differ from what has been shown earlier with 1,25(OH)2D3 treatment in the rat.

Animals↗
PubMed1984

Antirachitic activity of 1 alpha-hydroxyergocalciferol and 1 alpha-hydroxycholecalciferol in rats.

Weanling vitamin D-deficient rats fed a high calcium, low phosphate diet were injected daily with 1 alpha-hydroxyergocalciferol or 1 alpha-hydroxycholecalciferol at doses of 2.5, 25 or 250 ng. Intestinal calcium and phosphate transport, serum phosphorus level, epiphyseal plate calcification, and percent femur ash increased as a function of the dose. Both compounds were equally effective in eliciting these responses demonstrating their equivalency as antirachitic compounds.

Animals↗