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Biomedical subjects

H C Schwartz

Publications and source records attributed to H C Schwartz.

At least 19 recordsLinked to original sources
PubMed1990

Extraoral placement of a subperiosteal tissue expander for reconstruction with hydroxylapatite of the severely atrophic mandibular alveolar ridge.

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.

Adult↗
PubMed1990

Effect of acarbose on carbohydrate and lipid metabolism in NIDDM patients poorly controlled by sulfonylureas.

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.

Acarbose↗
PubMed1988

Interference of fetal hemoglobin with the spectrophotometric measurement of carboxyhemoglobin.

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.

Carboxyhemoglobin↗
PubMed1987

Evaluation of autologous cancellous bone grafting of mandibular discontinuity defects in dogs using a Dacron-urethane prosthesis.

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.

Animals↗
PubMed1987

Functional nature of glomerular injury in progressive diabetic glomerulopathy.

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.

Adult↗
PubMed1986

Synovial chondromatosis of the temporomandibular joint presenting as a parotid mass: possibility of confusion with benign mixed tumor.

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.

Adenoma, Pleomorphic↗
PubMed1986

Juvenile nasopharyngeal angiofibroma presenting as a facial swelling. A case report.

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.

Adolescent↗
PubMed1986

Postoperative irradiation of fresh autogenic cancellous bone grafts.

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.

Animals↗
PubMed1979

Interface radiation dosimetry in mandibular reconstruction.

When a beam of radiation crosses the interface between two substances, secondary electrons are generated. This results in enhancement of the absorbed dose of radiation roughly proportional to the difference in atomic numbers. Interfaces are created in reconstruction of the mandible with implantable trays containing hematopoietic bone marrow and cancellous bone chips. Radiation was measured in tissue-equivalent material surrounding mandibular tray implants of titanium, vitallium, stainless steel, and Dacron/polyetherurethane. The absorbed dose was enhanced by 29% to 36% adjacent to the metallic trays; 1% dose enhancement was noted adjacent to the Dacron/polyetherurethane tray. We conclude that, when radiation therapy is necessary following mandibular reconstruction, homogeneity of dose is maintained and local soft-tissue reactions to excessive irradiation may be avoided by using a nonmetallic tray.

Biocompatible Materials↗
PubMed1979

Zygomatico-coronoid ankylosis secondary to heterotopic bone formation: combined treatment by surgery and radiation therapy--a case report.

Zygomatico-coronoid ankylosis is a rare, extra-articular form of ankylosis of the jaws. An unusual case is presented in which true bony zygomatico-coronoid ankylosis was produced by a mass of heterotopic bone. Surgical treatment consisted of an oblique ostectomy across the mandibular ascending ramus, with interposition of Silastic sheeting to form a pseudarthrosis. Since surgery is often the stimulus for this condition, 2000 rads were delivered to the surgical site postoperatively in order to inhibit recurrent heterotopic bone formation. The rationale and indications for this form of treatment are discussed.

Ankylosis↗
PubMed1979

Use of a craniotome for obtaining cancellous bone and marrow from the ilium.

The ilium is a rich source of cancellous bone and marrow for grafting. Grafts can be harvested very rapidly with a standard craniotome. The clutch mechanism prevents inadvertent soft tissue injury if both cortical plates are perforated. The surgical approach is similar to that used in other techniques. No complications have been encountered.

Bone Marrow Transplantation↗
PubMed1979

Rhinolithiasis: a disorder not to be approached transorally.

Rhinolithiasis is a disorder that results from the calcification of intranasal foreign bodies. An unusual case is presented in which a rhinolith was discovered on a maxillary occlusal radiograph. The rhinolith was initially confused with a lesion of the palate. Precise localization of lesions is mandatory before transoral exploration is attempted.

Adolescent↗
PubMed1978

Spontaneous resolution of severe aplastic anemia associated with viral hepatitis A in a 6-year-old child.

Recovery from acquired aplastic anemia associated with hepatitis is rare. This case of a 6-year-old boy with severe aplastic anemia is the first reported association of this disease with a hepatitis A infection. Antibody to hepatitis A (anti-HA) was not detected on admission, but was detected three weeks later. Infection with hepatitis B virus, cytomegalovirus (CMV), and Epstein-Barr virus (EBV) were excluded. The peak titer of anti-HA was higher than would be expected for passive transfer of antibody resulting from transfusions. The persistence of antibody for more than 20 months after the last transfusion was not consistent with passive antibody, which would be expected to disappear over that time. This child had indications for allogeneic marrow transplant and a sibling donor who was histocompatible. However, the transplant was postponed because the prognosis was considered to be poor in the presence of active hepatitis. There was a spontaneous remission without the necessity of the transplantation procedure.

Anemia, Aplastic↗