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Biomedical subjects

J M Harrelson

Publications and source records attributed to J M Harrelson.

70 records · Page 4Linked to original sources
PubMed1982

Afferent sensory feedback for lower extremity prosthesis.

Electrical stimulation has been applied to sciatic nerves of patients to achieve sensory feedback after lower limb amputation for periods of up to six years. Patients used the sensory feedback device daily. Pain, infection and electrode displacement have not been problems. The immediate postoperative benefits are that pain is minimized after amputation and stump healing is improved. Furthermore, the stimulus affords the patient increased confidence when walking due to renewed awareness of the center of gravity. Improved ability to function in the dark and when walking up and down stairways makes the application of sciatic nerve stimulation after amputation very rewarding.

Amputation, Surgical↗
PubMed1981

CT detection of intraosseous gas: a new sign of osteomyelitis.

In three patients the diagnosis of osteomyelitis was made when computed tomography (CT) demonstrated gas within the medullary cavity of the involved bone. The diagnosis was clinically unsuspected in two of the patients before the CT examination, and none showed bone abnormalities on plain radiographs. Two patients had evidence of infection of the deep soft tissues adjacent to bone, and the third developed the lesion in an allograft. In all three patients CT detection of intraosseous gas resulted in significant alteration of patient management.

Adult↗
PubMed1981

A quantitative histologic study of avian osteopetrotic bone demonstrating normal osteoclast numbers and increased osteoblastic activity.

Hyperostotic diseases caused by increased osteoblastic activity are poorly understood partially because a suitable animal model is not available for their study. In contrast, a hyperostotic disorder caused by defective osteoclasts (mammalian osteopetrosis) is better understood, largely because of advances made with a murine model of the disease. The avian form of osteopetrosis is caused by RNA tumor viruses, but the role of osteoblasts and osteoclasts is not clear. We have performed a morphometric analysis of osteopetrotic avian bone to provide basic information about changes in the cells of bones from animals developing the disease. Chick embryos were injected at 12 days of incubation with a virus (MAV-2(0)) that induces osteopetrosis at a high frequency. Changes in bone volume were detected 14 days after virus injection. By 3 weeks of age, the bone volumes of osteopetrotic chicks were 4.7-fold larger than controls. The mean caliper diameter of an osteoclast was the same in osteopetrotic and normal bone. The number of osteoclasts per tibia increased in osteopetrotic animals, but the density of osteoclasts decreased. The presence of an increased number of osteoclasts of a normal size rules out the possibility that the virus causes osteopetrosis by selectively killing osteoclasts. The total bone-nonbone interface increased in osteopetrosis, and greater than 90 per cent of interface surface was devoted to bone deposition. These results indicate that avian osteopetrosis is an osteoblastic, proliferative disorder of bone and may serve as an excellent animal model for human diseases in which osteoblasts increase in number.

Animals↗
PubMed1980

Evaluation of a role for 1,25-dihydroxyvitamin D3 in the pathogenesis and treatment of X-linked hypophosphatemic rickets and osteomalacia.

Although a defect in renal transport of phosphate seems well established as the primary abnormality underlying the pathogenesis of X-linked hypophosphatemic rickets and osteomalacia, several observations indicate that renal phosphate wasting and hypophosphatemia cannot solely account for the spectrum of abnormalities characteristic of this disease. Thus, in the present study, we investigated the potential role of abnormal vitamin D metabolism in the pathogenesis of this disorder and the effect of 1,25-dihydroxyvitamin D(3) therapy on both the biochemical abnormalities characteristic of this disease and the osteomalacia. Four untreated patients, ages 14-30 yr, had normocalcemia (9.22+/-0.06 mg/dl); hypophosphatemia (2.25+/-0.11 mg/dl); a decreased renal tubular maximum for the reabsorption of phosphate per liter of glomerular filtrate (2.12+/-0.09 mg/dl); normal serum immunoreactive parathyroid hormone concentration; negative phosphate balance; and bone biopsy evidence of osteomalacia. The serum 25-hydroxyvitamin D(3) concentration was 33.9+/-7.2 ng/ml and, despite hypophosphatemia, the serum level of 1,25-dihydroxyvitamin D(3) was not increased, but was normal at 30.3+/-2.8 pg/ml. These data suggested that abnormal homeostasis of vitamin D metabolism might be a second defect central to the phenotypic expression of X-linked hypophosphatemic rickets/osteomalacia. This hypothesis was supported by evaluation of the long-term response to pharmacological amounts of 1,25-dihydroxyvitamin D(3) therapy in three subjects. The treatment regimen resulted in elevation of the serum 1,25-dihydroxyvitamin D levels to values in the supraphysiological range. Moreover, the serum phosphate and renal tubular maximum for the reabsorption of phosphate per liter of glomerular filtrate increased towards normal whereas the phosphate balance became markedly positive. Most importantly, however, repeat bone biopsies revealed that therapy had positively affected the osteomalacic component of the disease, resulting in normalization of the mineralization front activity. Indeed, a central role for 1,25-dihydroxyvitamin D(3) in the mineralization of the osteomalacic bone is suggested by the linear relationship between the serum level of this active vitamin D metabolite and the mineralization front activity. We, therefore, suggest that a relative deficiency of 1,25-dihydroxyvitamin D(3) is a factor in the pathogenesis of X-linked hypophosphatemic rickets and osteomalacia and may modulate the phenotypic expression of this disease.

Adolescent↗
PubMed1980

Hypophosphatemic osteomalacia: association with prostatic carcinoma.

Hypophosphatemic osteomalacia that remits after resection of a coexisting tumor has been described in 35 patients. Because the associated neoplasms have been of mesenchymal origin, it has been inferred that this tumor-induced osteomalacia syndrome is uniquely related to tumours of this derivation. However, in the present investigation we studied subjects with coincident hypophosphatemia and prostatic carcinoma to ascertain whether this endodermal malignancy causes the tumor-induced osteomalacia syndrome. The hypophosphatemic patients had renal phosphate wasting, gastrointestinal malabsorption of calcium and phosphate, and negative phosphate balance. Moreover, bone biopsies showed histomorphologic changes indicative of osteomalacia. Although widespread metastases precluded establishing the diagnosis of tumor-induced osteomalacia by resection of the tumor, a series of studied excluded alternate causes for the osteomalacia. Further, affected subjects had a normal serum concentration of 25-hydroxyvitamin D, 28.0 +/- 8.3 ng/mL, and serum 1,25-dihydroxyvitamin D levels were low, 15.0 +/- 1.0 pg/mL, characteristic of the tumor-induced osteomalacia syndrome. Thus, prostatic carcinoma, although an endodermal malignancy, may cause the tumor-induced osteomalacia syndrome.

Aged↗
PubMed1980

Bone-grafting in total hip replacement for acetabular protrusion.

Since 1971 we have used homologous and autogenous bone grafts to reinforce the medial acetabular wall when doing a total hip replacement in patients with painful protrusio acetabuli. Thirty-two patients have been followed for a minimum of two years, the longest follow-up being eight years. All grafts appeared to have united roentgeno-graphically within three months, and the protrusion did not progress. In seven patients with a completely absent medial acetabular wall, a protrusio acetabuli ring was used to provide support until the bone graft had healed. Complications included one late dislocation, one pulmonary embolus, two trochanteric non-unins, two fractured trochanters, and one case of loosening of the femoral component. The results of this study suggest that bone-grafting is effective in arresting the progression of acetabular protrusion.

Acetabulum↗
PubMed1978

Skeletal metastases of melanoma.

Sixteen hundred and seventy-seven melanoma patients were treated at Duke University Medical Center from 1956 to 1976. Osseous metastases were more common than previously reported and occurred in 116 patients (6.9 per cent), most often in the axial skeleton. Diagnosis was made by roentgenogram, bone scan, or both in the symptomatic patient. Seventy-five patients sustained pathological fractures, most of which were successfully treated conservatively. Nine of the ten patients with neurological symptoms were improved by laminectomy. The grave prognosis for melanoma patients with osseous metastases (mean survival, 3.6 months) led to conservatism even for an impending pathological fracture. Unstable pathological fractures of long bones were treated by internal fixation and irradiation.

Adult↗
PubMed1978

Hand metastasis from melanoma: a case study.

Metastases to the hand are rare. Most frequently they result from carcinomas of the lung, breast or kidney. This is a case report of a rare peripheral metastatic lesion in a 24-year-old man with melanoma. There are no previously reported hand metastases from melanoma. Because of the extremely poor prognosis for patients with osseous metastases from melanoma, treatment should be palliative.

Adult↗
PubMedDate not supplied

A phase II trial testing the thermal dose parameter CEM43 degrees T90 as a predictor of response in soft tissue sarcomas treated with pre-operative thermoradiotherapy.

We prospectively evaluated whether delivering a thermal dose of > 10 cumulative equivalent minutes at 43 degrees C to >90% of the tumour sites monitored (CEM43 degrees T90) would produce a pathologic complete response (pCR) in > 75% of high-grade soft tissue sarcomas treated pre-operatively with thermoradiotherapy. The impact of thermal dose on local failure (LF), distant metastasis (DM), and toxicity was also assessed. Thirty-five patients > or = 18 years old with grade 2 or 3 soft tissue sarcomas accessible for invasive thermometry were enrolled on the protocol. All patients received megavoltage external beam radiotherapy (RT) in daily fractions of 1.8-2.0 Gy, five times a week, to a median total dose of 50 Gy and an initial hyperthermia treatment (HT) of I h duration utilizing the BSD 2000 with Sigma 60 or MAPA applicators at frequencies of 60-140 MHz. Further HT was given for patients with CEM43 degrees T90 > 0.5 after initial HT ('heatable' patients), twice a week to a maximum of 10 HT or CEM43 degrees T90 > 100. Of the 35 patients entered, 30 had heatable tumours, one of which was inevaluable for pCR or LF as the patient died of DM prior to surgery, leaving 29 evaluable patients. Of these 29 patients, 15 (52%) had a pCR (95% CI: 37-73%), significantly less than the projected rate of > or = 75% (p = 0.02). Of the 25 heatable tumours that achieved CEM43 degrees T90 > or = 10, 14 (56%) had a pCR (95% CI: 39-78%) significantly less than the projected rate (p = 0.06). Three of the 29 patients (10%) with heatable tumours had a LF, versus 1/5 unheatable tumours (p = 0.48). Fourteen of the 30 patients (47%) with heatable tumours developed DM, versus 2/5 unheatable tumours (p = 1.00). Ten of the 30 patients (33%) with heatable tumours developed treatment-induced toxicity. Thus, no correlation of thermal dose with histologic response was observed. Prospective control of CEM43 degrees T90 failed to achieve the projected pCR rate following pre-operative thermoradiotherapy for high-grade soft tissue sarcomas, despite excellent local control. Possible explanations for this outcome are discussed.

Adult↗
PubMedDate not supplied

Primary actinomycosis of an extremity: a case report and review.

Primary infection of an extremity is an uncommon feature of actinomycosis and can readily be confused with actinomycetoma caused by aerobic actinomycetes such as Nocardia and Streptomyces. A case of primary actinomycosis of the leg is reported, and 35 cases published in the English-language literature are reviewed. There were 14 cases of upper extremity infections and 22 cases of lower extremity infections. Antecedent trauma had occurred in 21 cases. Lesions began in the skin, subcutaneous tissue, muscle, bone, and joint space. Spread to contiguous structures was characteristic, and most lesions eventually involved all of the aforementioned structures. The lesions were typical of actinomycosis with sinus formation and granules in the pus. Cultures were positive in 17 cases. Surgical therapy was necessary in most instances; penicillin remains the drug of choice. Pending results of culturing, a lesion with granules of branching gram-positive bacteria would best be treated empirically with penicillin and a sulfonamide. Prognosis is excellent.

Actinomyces↗
PubMedDate not supplied

Newer knowledge of vitamin D and its metabolites in health and disease.

Renewed interest in vitamin D, over the past several years, has resulted in increased knowledge of (1) the metabolic pathways which result in production of an active metabolite, (2) the role of its various metabolities at target tissues, and (3) its interaction with other control systems in the maintenance of calcium/phosphorus homeostasis. Presently, a role for 1, 25-(OH)2 D3 can be identified in the regulation of (1) calcium and phosphorus absorption from the intestine, (2) PTH production, and (3) calcium mobilization from bone (in conjunction with PTH). Several other actions at the kidney, muscle and other organs have been suggested but not proven. In contrast, the actual process of bone mineralization may be dependent, in part, on 25-(OH) D3. Despite these major advances in our knowledge, many gaps remain and controversial data continues unresolved. However, application of this new information to analysis of a wide variety of disease states has resulted in remarkable progress in appreciation of the pathogenesis and appropriate treatment for these diseases. Nonetheless, continued research promises further advances and more precise definition of disease states as well as delineation of the therapeutic role of Vitamin D metabolites in their treatment.

Bone and Bones↗