Biomedical subjects
Publications and source records attributed to H C Schwartz.
Paget's disease is a disorder of bone metabolism that is relatively common in the elderly population. The jaw bones are affected in 17% of cases. A case of maxillary involvement with unusual clinical and radiographic findings is presented.
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A technique is described using a subperiosteal tissue expander and particulate hydroxylapatite for reconstruction of the class IV edentulous mandibular alveolar ridge. The expander is placed under direct visualization via an extraoral approach so that it can be precisely positioned with relation to the inferior alveolar nerve. A fibrous capsule, having ideal ridge structure forms around the expander, and hydroxylapatite can be injected into this capsule from the intraoral route. The rationale for this technique and its advantages are discussed. It has been used in 17 patients with excellent results.
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The ability of acarbose to lower plasma glucose concentration was studied in 12 patients with non-insulin-dependent diabetes mellitus (NIDDM) who were poorly controlled by diet plus sulfonylurea drugs. Patients were studied before and 3 mo after the addition of acarbose to their treatment program, and a significant improvement in glycemic control was noted. Although the decrease in fasting plasma glucose concentration was modest (12.0 +/- 0.8 to 10.8 +/- 0.3 mM), average postprandial plasma glucose concentration decreased by 3.4 mM. When acarbose therapy was discontinued in 5 patients, plasma glucose levels rapidly returned toward pretreatment levels. In addition to the improvement in glycemia, acarbose treatment also led to a significant reduction in HbA1c (7.4 +/- 0.2 to 6.4 +/- 0.2%, P less than 0.01) and triglyceride (2.4 +/- 0.1 to 2.1 +/- 0.1 mM, P less than 0.01) concentrations. Neither the plasma insulin response to meals nor insulin-stimulated glucose uptake improved with acarbose therapy, consistent with the view that acarbose improves glycemic control by delaying glucose absorption. Considerable individual variation was noted in the response to acarbose, and the results in 4 patients were dramatic, with striking reductions in both fasting and postprandial glucose concentrations. The addition of acarbose to patients with NIDDM not well controlled by sulfonylureas appears to have significant clinical benefit.
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We measured the concentration of carboxyhemoglobin (HbCO) in blood samples from 32 neonates by spectrophotometry (IL282 CO-Oximeter) and gas chromatography, finding a strong positive correlation (r = 0.89) between the concentration of fetal hemoglobin (Hb F) and HbCO as measured by spectrophotometry, but not by gas chromatography. Thus, Hb F interferes with the determination of HbCO by spectrophotometric techniques by falsely increasing apparent HbCO in direct proportion to Hb F. We conclude that, when Hb F is known or suspected to be present, blood HbCO cannot be reliably determined by methods based on spectrophotometry.
Reconstruction of 2 cm discontinuity defects using autologous cancellous bone chips and a Dacron-urethane prosthesis was evaluated in four canine mandibles. Histologic studies were performed on specimens taken six and 12 months after bone grafting. All four grafts were completely incorporated, producing a reconstruction that conformed precisely to the desired shape. Remodeling resulted in a trabecular pattern similar to that of the normal mandible. The prosthesis was well tolerated and did not elicit an inflammatory response.
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We describe in physiological terms the increasing glomerular capillary wall (GCW) dysfunction of 20 patients with diabetic glomerulopathy and heavy proteinuria. The clearances of uncharged polysaccharide markers of graded size were used to probe the glomerular filter on three occasions over a 24-mo period. The findings were analyzed with a theoretical model of solute transport that depicts most of the GCW as an isoporous membrane and the minor portion as a nondiscriminatory shunt pathway. Initially, the mean glomerular ultrafiltration coefficient Kf is computed to have been 3-5 times lower and mean pore radius of the major membrane component (r0) 2 A smaller than normal control values. In contrast, the model computes the fraction of filtrate volume permeating the nondiscriminatory shunt pathway (omega 2) to have been sixfold elevated above control values and to have correlated strongly in individual patients with the fractional clearances of albumin (r = .72) and of IgG (r = .73). Sequential studies after 12 and 24 mo revealed an invariable decline in glomerular filtration rate (GFR). Fractional clearances of albumin and IgG increased with time in most patients but declined in a few instances (20-25%). Change in omega 2 tended to occur in parallel with fractional protein clearance, regardless of its direction. We conclude that in progressive diabetic glomerulopathy GFR declines because of a loss by glomerular capillaries of ultrafiltration capacity, proteinuria is largely a consequence of increasingly impaired barrier-size selectivity, and the foregoing injuries reflect damage to different parts of the GCW and may become dissociated from one another with the passage of time.
It has been recognized for some time that alterations in the affinity of Hb for oxygen could offer a means of improving oxygen delivery to tumors and achieving radiosensitization. Three antilipidemic drugs, clofibrate, bezafibrate, and gemfibrozil, two of which had previously been shown to reduce Hb/O2 affinity in vitro, were tested in mice for their ability to affect Hb/O2 affinity and to alter the radiosensitivity of the RIF-1 sarcoma. Each of the drugs produced a significant increase in the P50 of the blood, from a mean control value of 45 mm Hg to 55, 74, and 51 mm Hg after a dose of 1 g/kg of clofibrate, bezafibrate, and gemfibrozil, respectively. However, they had very different effects on the radiosensitivity of the RIF-1 tumor. When the mice breathed air at the time of irradiation, clofibrate produced a marked sensitization equivalent at the optimum time to a 20-fold reduction in hypoxic fraction; bezafibrate gave a lower sensitization equivalent to a 4-fold reduction, while gemfibrozil caused dramatic radioresistance equivalent to a 10-fold increase in hypoxic fraction. When the mice were given 95% O2/5% CO2 to breathe at the time of irradiation to ensure complete Hb saturation in the lungs, a large increase in the sensitization by bezafibrate was seen, but there was only a small change with clofibrate. We conclude that drugs which reduce Hb/O2 affinity could have a role in sensitizing tumors to radiation.
Synovial chondromatosis is a rare metaplastic disorder of synovium in which cartilaginous nodules are produced within joint spaces. An unusual case involving the temporomandibular joint, with extension of the lesion beyond the joint capsule into the parotid gland, is described. The patient had a history of previous superficial parotidectomy for a "benign mixed tumor." Review of the histologic features revealed both lesions to be identical. The reason for confusion between the two diagnoses is discussed.
Juvenile nasopharyngeal angiofibroma is a rare benign neoplasm occurring almost exclusively in adolescent males. When it is confined to the nasopharynx, surgery is often curative. In 20% of cases, there is intracranial extension, and radiotherapy may be used to avoid the risk of life-threatening haemorrhage. The authors report an unusual case which presented with a swelling of the cheek and an abducens nerve palsy. The lesion extended from the nasopharynx across the pterygomaxillary fissure, as well as intracranially. Radiotherapy was given, and the patient remains disease-free after one year.
Discontinuity defects were created in the mandibles of dogs and then reconstructed immediately with fresh autogenic cancellous bone grafts and Dacron-urethane prostheses. The grafts were irradiated to a total dose of 5000 rads after waiting intervals of between 3 and 12 weeks. Nonirradiated grafts served as controls. The grafts were evaluated clinically, radiographically, and histologically. There was complete incorporation of all grafts, regardless of the interval between surgery and radiotherapy. There were no soft-tissue complications. The controls were distinguishable from the irradiated grafts only by the presence of hematopoietic bone marrow. Fibrofatty marrow was observed in the irradiated grafts. Theoretical support for this technique is found in the biology of cancellous bone grafting and the pathology of radiation injury. In view of the difficulties associated with mandibular bone grafting in preoperatively irradiated patients, a new method of reconstructing selected cancer patients who require both mandibular resection and radiotherapy is suggested.
The purpose of this investigation was to compare immunoreactive erythropoietin levels in umbilical cord plasma and neonatal bilirubin production in infants born of normal women who delivered with or without labor. Two groups of term (38 to 42 weeks) singleton pregnancies were compared: 1) those delivered by repeat elective cesarean section without prior labor (N = 17), and 2) those delivered vaginally or by cesarean section after labor (N = 24). None of the infants was asphyxiated, and there was no difference in Apgar scores between the no-labor and labor groups. The cord plasma erythropoietin levels were lower in the infants of women who had repeat elective cesarean section without labor than in those whose mothers had labor before delivery (Wilcoxon rank sum test, P less than .025). The median erythropoietin for the no-labor group was 22.9 mU/mL compared with 38.8 mU/mL for the labor group. The pulmonary excretion rate of carbon monoxide (VeCO), an index of bilirubin production, for the no-labor group was 14.3 +/- 6.2 SD microL/kg per hour compared with 18.0 +/- 4.9 SD microL/kg per hour for the labor group (P less than .05). The hemoglobin concentration for the no-labor group was 16.0 +/- 1.5 SD g/dL compared with 17.7 +/- 2.2 SD g/dL for the labor group (P less than .05). The VeCO correlated with the hemoglobin concentration (N = 32, r = 0.37, P less than .05). The results of the present study suggest that labor is normally associated with increases in the cord plasma erythropoietin level.(ABSTRACT TRUNCATED AT 250 WORDS)