Biomedical subjects
Publications and source records attributed to A J Olah.
The aim of this study was to test whether healing of extensive transosseous defects in the calvaria can successfully be achieved using guided bone regeneration. The results demonstrated complete osseous bridging of the skull defect in the test specimen. In the control specimen, fibrous connective tissue occupied the area of the skull defect.
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An 82-year-old woman, with clinically and histologically documented osteomalacia associated with a history of several gastrointestinal operations and malabsorption, was successfully treated with low dose calcitriol. Osteomalacia, with particular reference to the gastrointestinal type, and the role of vitamin D and its metabolites are discussed. Therapy with calcitriol is compared with conventional vitamin D treatment. Calcitriol should be considered in the treatment of osteomalacia induced by gastrointestinal disorders.
Renal osteodystrophy is one of the major complications in patients on long-term hemodialysis. A group of 42 patients on hemodialysis (mean age 42 yr) were investigated in order to assess the prevalence of renal osteodystrophy in Israeli patients. The patients were examined by X-ray, and 66.7% were found to have signs of osteodystrophy. Of 14 patients without signs of bone involvement, 10 had been on treatment less than 1 yr. A bone biopsy, performed in 28 patients (mean age 43 yr), showed signs of renal osteodystrophy in all. Two of these patients were diagnosed as having mainly osteitis fibrosa, four as having osteomalacia and the rest as having the symptoms of both.
Twenty patients with chronic renal failure being treated with hemodialysis were investigated in an attempt to ascertain whether hyperparathyroidism is an important etiologic factor in these patients' anemia. The patients were divided into two groups, one with hemoglobin of greater than 8 g/dl and the other with hemoglobin of less than 8 g/dl. These groups differed in blood transfusion requirements and in serum iron saturation. There was no difference between their levels of serum calcium, serum phosphate, serum alkaline phosphatase or serum parathyroid hormone. On bone biopsy endosteal fibrosis with bone marrow involvement was found in 2 of the 11 patients with high hemoglobin and in 5 of the 9 patients with low hemoglobin. Endosteal fibrosis with bone marrow involvement may thus be an important factor in the pathogenesis of anemia, and its presence or absence in association with hyperparathyroidism may explain the controversial observations reported by other investigators.
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9 patients with advanced renal failure and renal osteodystrophy documented by iliac crest biopsy were treated with 1,25-dihydroxycholecalciferol (average dose 0.53 micrograms per day) for 6 months. Under 1,25-DHCC there was a statistically significant increase in serum calcium and decrease in serum alkaline phosphatase and immune parathyroid hormone. Histomorphometric evaluation of posttreatment bone biopsies showed reduction of osteoclastic resorption and endosteal fibrosis. Osteoid volume decreased in most cases. In 3 patients with predominant fibroosteoclasia, bone turnover practically normalized. Bone mineral content of the radius (photoabsorptiometry) did not change with treatment. Transient hypercalcemia occurred in 5 patients and was easily corrected by adjustment of 1,25-DHCC dosage.
The effect of prolonged metiamide administration on serum gastrin, gastrin content of the antrum and gastric corpus, and G-cell population was studied in the rat. A single subcutaneous injection of metiamide (200 mg/kg) at the onset of 16 days of continous treatment with three daily injections was followed by a fivefold increase in serum gastrin level at 4 hr in fasted and at 4 and 6 hr in fed rats. After 16 days of metiamide, the fed rats showed a peak in serum gastrin level of the same magnitude as on day 1, but only at 4 hr. Two hours later, the levels decreased rapidly to basal values. In the fasted animals, the response to metiamide was reduced to a threefold increase at 2 hr. There was no difference in gastrin content of the antrum and gastric corpus nor in volume density of the G-cells after the prolonged treatment compared with the controls. It is concluded that in spite of rises in serum gastrin, prolonged metiamide medication has no effect on the gastrin content of the antrum and gastric corpus nor on the G-cell population in the rat. Furthermore, after prolonged treatment, metiamide-induced gastrin release is diminished.
The extent to which histomorphometric analysis of bone biopsies correlates with Ca kinetic and biochemical parameters to reflect true bone formation and resorption in adult man remains an unsolved issue. Two groups of patients with either low (osteoporosis), (n = 15) or high (Paget's disease, n = 6) bone turnover were studied before and after sodium fluoride (NaF) and diphosphonate (EHDP) treatment, respectively. Histomorphometry of iliac crest biopsies permitted precise quantitation of the osteoblast layers (SVab), osteoid seams (SVos), the number of osteoclasts (NAocl) and the Howship's lacunae (SVhl). These determinations were correlated with serum alkaline phosphatase (aPh), urinary hydroxyproline (HyPro), Ca accretion rate (Vo+), and Ca mobilization rate (Vo-). In both patient groups bone formation indices were significantly correlated: SVob/Vo+, r = 0.85; SVos/Vo+, r = 0.83; and aPh/Vo+, r = 0.97. Provided that bone matrix formation and mineralization progess at the same rate, bone formation may be assessed by measuring either aPh, Vo+, SVob, or SVos. From these correlations it is not possible to draw any conclusions regarding the absolute "true" value of bone formation, be it in terms of Ca kinetics, alkaline phosphatase, or histomorphometry. However, since Vo+ retains its proportionality to all the other bone formation parameters tested, the so-called "slow exchange," which refers to pure physicochemical Ca exchange processes in the bone mineral, does not perturb Vo+ in an unsystematic way. Vo+ as well as aPh and histomorphometric indices are thus reliable, though not absolute indices of bone formation. Bone resorption indices correlated less well than bone formation indices: NAocl/Vo-, r = 0.68 and SVhl/Vo-, r = 0.63 with both groups. In the osteoporotic group, a negative correlation existed between the empty Howship's lacunae SVhe and Vo+, r = -0.62. Consequently, the overall extent of Howship's lacunae SVhl is influenced both by bone resorption and bone formation. On the other hand, the best correlation of HyPro was with the sum of Vo+ and Vo-, r = 0.97, confirming that HyPro is a sensitive index for the change of bone turnover.
Movat's pentachrome I stain has been adapted and modified as a stain for undecalcified bone sections. After embedding in methyl methacrylate, this procedure yields consistently good results, with an excellent and colorful contrast between mineralized and unmineralized compartments of both cartilage and bone. In addition, osteoblasts, osteoclasts, and other cells and tissue components can easily be differentiated. The staining properties of the lacunar wall surrounding the osteocytes are considered to reflect various states of osteocytic activity. The method is especially useful for the study of bone growth and bone repair, and as a stain for conventional histomorphometry and computer-assisted image analysis in bone biopsies.
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