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Biomedical subjects

J W Schweiger

Publications and source records attributed to J W Schweiger.

At least 19 recordsLinked to original sources
PubMed1997

Intravenous vitamin K1 prior to orthotopic heart transplantation: effects in vivo and in vitro.

BACKGROUND: Vitamin K1 is used to reverse warfarin's anticoagulant action. It is unclear whether intravenous vitamin K1 is safe or efficacious prior to urgent cardiac surgery. METHODS: We retrospectively and prospectively examined the effects of preoperative intravenous vitamin K1 in vivo (administered for warfarin reversal immediately before heart transplantation) on intraoperative blood product utilization, hemodynamics and coagulation parameters. We also determined the direct effects of vitamin K1 in vitro on rings of human saphenous vein and internal mammary artery. RESULTS: In the retrospective limb, 29 of 67 patients were administered vitamin K1 preoperatively via slow intravenous infusion. Vitamin K1 administration produced no adverse outcome but did not affect subsequent perioperative use of blood products. In the prospective limb (n = 10), vitamin K1 significantly (P < or = 0.01, Student t-test) altered mean arterial pressure (from 85 +/- 15 to 76 +/- 16 mmHg), systemic vascular resistance (from 1364 +/- 308 to 1078 +/- 252 dyn.s.cm-5), and cardiac index (from 2.3 +/- 0.3 to 2.7 +/- 0.3 L/min/m2) (mean +/- SD). Significant decreases in prothrombin time (19.8 +/- 2.7 to 17.7 +/- 1.8 s) and activated clotting time (164 +/- 26 to 137 +/- 24 s) were observed at 60 min. In vitro vitamin K1 (10(-7) to 10(-4) M) had no effect on the tone of noradrenaline-constricted rings. CONCLUSIONS: Vitamin K1, administered by intravenous infusion prior to heart transplantation, did not alter subsequent perioperative blood product administration. Vitamin K1 rapidly reversed the anticoagulant effect of warfarin and produced modest hemodynamic changes. The decrease in systemic vascular resistance is probably not due to a direct effect of vitamin K1 on vascular smooth muscle.

Anticoagulants↗
PubMed1996

Craniofacial osseointegration of a large midfacial bone-anchored combination maxillofacial prosthesis: a clinical report.

The combination of retentive clips and magnets has been used with favorable results for smaller facial prostheses. This patient's large midfacial defect created the need for an attachment design that would retain an intraoral obturator prosthesis and a large silicone facial prosthesis. The advantages of this design include having an obturator that is separately attached by clips to the framework. This allows the patient more ease in insertion and removal of the prosthesis. It also allows for better oral hygiene. The magnets aid the patient in the proper alignment of the facial prosthesis. The O-ring attachment was not a complicated technique in this patient's treatment. The patient can, without the use of a mirror, snap the rubber matrix O-ring attachment over the patrix attachment on the framework. This resulted in a retentive facial prosthesis, which helped the patient feel more secure. The silicone margins were well adapted to the patient's skin, which allows the use of thin translucent margins and the elimination of the inherent problems associated with the use of adhesives.

Frontal Bone↗
PubMed1996

A conservative fixed partial denture: a clinical report.

The restoration of a patient's edentulous area with a three-unit fixed partial denture is described. The denture consisted of an etched-metal bonded retainer and metal ceramic pontic with a nonrigid connector in combination with a conventional inlay retainer. The incorporation of a nonrigid connector permitted the use of dissimilar metals and cements with retainers of different retention potentials. This technique provides minimal reduction of tooth structure with supragingival margins for improved periodontal health.

Adult↗
PubMed1995

A two-stage impression technique for custom facial prostheses.

A two-stage impression technique that uses polyvinyl siloxane and irreversible hydrocolloid in a custom impression tray is described. The technique records the tissues to be contacted by the facial prosthesis with minimal distortion with the patient in an upright position and facial musculature at rest. The procedure is simple, accurate, and it eliminates some of the shortcomings of other techniques.

Acrylic Resins↗
PubMed1989

Titanium implants in irradiated dog mandibles.

The use of osseointegrated titanium implants has been a great benefit to selected cancer patients who otherwise would not be able to wear conventional and/or maxillofacial prostheses. Cognizant of the risk of osteoradionecrosis, we used an animal model to seek experimental evidence for successful osseointegration in bone irradiated to tumoricidal levels. Five healthy male beagle dogs received 60 gray to a previously edentulated and healed area of the right hemimandible. The left hemimandible was kept as a nonirradiated control. After 9 months, titanium implants were placed and allowed an additional 5 1/2 months to osseointegrate. At that time, block specimens were obtained, radiographed, photographed, and analyzed histologically. Although statistical significance cannot be attached to the results, osseointegration was achieved in half of the irradiated specimens.

Animals↗
PubMed1988

The pulmonary microcirculation of the rat: differential ultrastructural responses of the endothelia to protamine sulfate.

Protamine sulfate is used clinically to reverse the anti-coagulant effects of heparin and in certain cases high protein, non-cardiogenic pulmonary edema develops. In the present study an initial stage of edema formation, namely, interstitial fluid accumulation around partially muscular extra-alveolar microvessels was observed in rats in situ after right ventricular injections of protamine. In addition, the endothelium of these microvessels displayed marked increases in plasmalemmal vesicles; however, disruption of the endothelium was not observed. Further, endothelial vesicle densities were unchanged and perivascular cuffs were not observed in either the nonmuscular extra-alveolar microvessels or the alveolar capillaries. Left ventricular injections of protamine failed to elicit the ultrastructural responses to protamine. Predosing the pulmonary microcirculation with heparin also served to prevent protamine-induced changes in the partially muscular microvessels. If it is assumed that heparin lowers the threshold for protamine-mediated responses in patients who develop edema, inhibition of protamine-induced changes by heparin predosing cannot be explained by the present data. Although evidence of increased endothelial vesiculation in the partially muscular microvessels was obtained, relative contributions of vesicles or of the junctional clefts to efflux from the pulmonary microvessels is not known. Thus, the mechanisms associated with a reduction of endothelial selectivity to macromolecular efflux after protamine administration remain to be defined.

Animals↗
PubMed1987

Aneurysmal bone cysts of the jaws: a case study and review of the literature.

Although first documented in 1958, the definitive explanation of the etiology and pathogenesis of the aneurysmal bone cyst has yet to be elucidated. This may be attributable to the relatively small number of cases contained within the literature. The following report and review of the pertinent literature is presented to add to the current body of knowledge on the subject.

Adolescent↗
PubMed1987

Oral complications following radiation therapy: a five-year retrospective report.

Oral complications following radiation therapy for head and neck cancer are common. A retrospective review of histories of 324 patients seen over a 5-year period by both the Radiation Oncology Department and the Dental Service at Memorial Sloan-Kettering Cancer Center is presented. ORN developed in only six patients during the interval.

Female↗
PubMed1977

Mandibular replacement after resection for tumor.

The ideal natural or prosthetic mandibular replacement should be adjustable at the time of surgery, completely stable, free from tissue reaction or rejection, rapidly incorporated into surrounding tissue, and unlimited in lifespan. A brief review of clinically utilized mandibular replacements is discussed in relation to the ideals. At this time the replacement most adequately satisfying these principles is autogenous cancellous bone and marrow supported by a titanium mesh trough. This article describes the details of external mandibular fixation and the reconstructive procedure including preoperative preparation and common postoperative complications. Modifications of the prosthesis and surgical technique are suggested in order to decrease the chances of postoperative exposure, a complication in any type of mandibular reconstruction.

Bone Transplantation↗