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Biomedical subjects

R J Demuth

Publications and source records attributed to R J Demuth.

At least 19 recordsLinked to original sources
PubMed1989

Effectiveness of prophylactic mastectomy in the prevention of breast tumors in C3H mice.

The effectiveness of prophylactic mastectomy in the prevention of breast tumors was studied in spontaneous breast-tumor-forming C3H mice. Prolactin levels were assayed to determine if this hormone was related to the incidence of mammary tumors. Two-hundred and fifty-six 1-month-old C3H mice were divided into four groups (control, 1; sham surgery, 2; mammectomy 50 percent, 3; and mammectomy 100 percent, 4). At the time of sacrifice (0 to 1 year postoperatively) estrus cycles were determined, ventral skin (breast) and ovaries were removed for histology, and serum was collected for prolactin assays. Prolactin levels 24 hours postoperatively were significantly elevated (p less than 0.01) in groups 2 to 4 when compared with group 1. Six months postoperatively, prolactin levels were significantly higher (p less than 0.05) in mice with tumors compared with those without tumors in groups 3 and 4. There were no differences in tumor incidence between the four groups. At 12 months postoperatively, no differences in prolactin levels were noted, but group 2 animals had the highest incidence of mammary tumors (89 percent; p less than 0.01) when compared to groups 3 and 4. Mammary tumor incidence was not decreased by 50 percent or 100 percent mammectomy in C3H mice. Prolactin levels rose in response to surgery and/or anesthesia and remained elevated only in tumor-bearing mice who underwent mammectomy, an occurrence similar to that reported in humans.

Adenocarcinoma↗
PubMed1988

Effects of phenylephrine on tissue gas tension, bleeding, infection, and lidocaine absorption.

In an attempt to find a vasoconstrictor with less detrimental local and systemic effects than epinephrine, the effects of phenylephrine, a pure alpha agonist, on tissue gas tension, bleeding, infection rates, and lidocaine absorption were studied. All concentrations of phenylephrine significantly reduced tissue PO2 within 10 minutes of injection, and reduction of PO2 was dose-dependent. Phenylephrine 1:10,000 produced significant bacterial growth when simultaneously injected with 6 X 10(6) Staphylococcus aureus. Bacterial growth was insignificant with 1:20,000 phenylephrine and absent with 1:40,000 phenylephrine. Blood loss from a standard wound was significantly reduced at all concentrations of phenylephrine. Lidocaine absorption was significantly reduced with 1:20,000 and 1:40,000 phenylephrine. In a rat model, 1:40,000 phenylephrine significantly reduced blood loss and lidocaine absorption, produced minimal reduction of tissue PO2, and did not enhance bacterial invasion.

Adsorption↗
PubMed1987

Management of burned long bones.

The management of severely burned and exposed supportive osseous tissues is not fully standardized. We present two patients in whom extensive debridement and decortication of the involved bone may have contributed to subsequent stress fractures. We propose an alternative therapeutic approach for this problem, including: minimal debridement of the bone, early coverage of the exposed bone with vascularized muscle, and adequate prophylactic protection.

Adult↗
PubMed1987

Craniofacial biostereometrics.

We believe that biostereometrics can be useful to the craniofacial surgeon in providing a highly accurate, reproducible diagnostic and presurgical tool that is inexpensive and noninvasive. It can help visualize complex pathologic bony abnormalities, resolve ambiguous CT scans, and predict soft-tissue changes secondary to alterations in bony contours when used in conjunction with CT scans and cephalograms.

Face↗
PubMed1986

Tissue expansion as an adjunctive technique for the management of difficult wounds.

Replacement of lost or injured tissues with similar tissues is a major goal of the reconstructive surgeon. A relatively new modality, tissue expansion, appears to be an helpful adjunct in achieving this goal by providing tissues for reconstruction that are near at hand, possess similar characteristics to the lost tissue, and can even enhance vascularity within an ischemic area. Although the technique is a useful one, its indications and contraindications are incompletely defined. We have used this technique 65 times in 42 patients during a 2 1/2 year period. The overall complication rate has been 22 percent, similar to other reconstructive techniques, but the consequences of these complications have been relatively minor and have not, for the most part, added significantly to patient morbidity.

Adolescent↗
PubMed1986

Juvenile aponeurotic fibroma with disseminated fibrosarcoma.

Juvenile aponeurotic fibromas, although locally recurrent, generally do not metastasize. This observation supports the practice of incomplete excision of the tumor to preserve the function of the involved extremity. We report on a patient with a juvenile aponeurotic fibroma of the palm, who returned 5 years after the second local surgical excision with metastatic fibrosarcoma of the lungs and bones.

Adipose Tissue↗
PubMed1986

Hemodynamic alterations secondary to an electrical burn in the rat: a pilot study.

Rats subjected to a standard electrical burn of 250 volts for 10 seconds receive a severe injury stimulating a pronounced systemic circulatory response. Initial postinjury hyperemia is replaced by a low perfusion state within 24 hours. Our study demonstrates the difficulty in isolating regional microcirculatory alterations under such circumstances. Modification of the burn model or the method of fluid resuscitation may minimize the influence of this dynamic systemic response.

Animals↗
PubMed1986

Attempts to improve tissue survival during ex vivo storage.

Ex vivo hypothermic perfusion has been shown to enhance short-term survival of organs before transplantation. The effects of perfusion, control of media pH, and systemic drug treatment were studied utilizing superficial epigastric free flaps in Sprague-Dawley rats. Viability of the flaps could be reliably maintained (9/10, 90%) for 72 hours using simple storage in phosphate-buffered Ringer's (pH 7.8) at 4 degrees C. Pretreatment with prostaglandin E1 was of slight benefit. Flap perfusion with or without pharmacologic agents was not beneficial.

Animals↗
PubMed1986

Repeated skin expansion to resurface a massive thigh wound.

We report here a patient who sustained posttraumatic skin and soft-tissue loss of the right thigh. Replacement of approximately 750 cm2 of split-thickness skin graft with adjacent skin serially expanded and advanced demonstrates the applicability of this technique to cover large tissue defects. Despite infection and exposure, we believe that expansion can proceed safely on an outpatient basis, providing that systemic toxicity does not develop and the exposure does not mechanically preclude expansion.

Child↗
PubMed1986

Use of ultrasound to locate a "lost" tissue expander injection port.

We have presented a rapid and reliable method of finding lost injection valves. (A frustrating footnote, however, is that 1 week later the port had again migrated and could not be located. Since the further anticipated gain was marginal, the bladder was already nearly expanded, and the expense for repeated ultrasound was a consideration, no further attempts were made to locate this port by ultrasound for further filling).

Aged↗
PubMed1985

Biostereometrics and computergraphics for patients with craniofacial malformations: diagnosis and treatment planning.

Utilizing the techniques of biostereometric photography and current state-of-the-art computergraphics, topographic contourgrams have been generated in a series of patients with complex craniofacial malformations. These contourgrams are considered useful in diagnosis and treatment planning and as an aid in postoperative follow-up. We hope that the technique will provide a means to study longitudinal growth in unoperated and operated patients with craniofacial malformations. Comparisons between these groups and normal patients are currently being investigated.

Adult↗
PubMed1985

Potentiation of infection by epinephrine.

A subinfective dose of Staphylococcus aureus (6 X 10(6)) does not produce wound infection in the rat model. Reducing the dosage (concentration) of epinephrine results in decreased numbers of viable bacteria in tissue and a lower incidence of wound infection in this model.

Animals↗
PubMed1984

Inadvertent intraradial arterial injection of cocaine.

Injection of a chemical irritant into the radial artery at the wrist causes acute discoloration of the skin, edema, and pain in the hand. Subsequent damage due to vasospasm, endarteritis, particulate embolization, and vascular thrombosis may result in ischemic contractures, amputations, and other functional hand deficits. Injection of a street cocaine preparation into the radial artery of a 22-year-old man produced a constellation of signs and symptoms similar to that described for other irritants. Current thoughts with regard to the pathophysiology and treatment of these injuries are reviewed.

Adult↗
PubMed1984

Complications of embolization treatment for problem cavernous hemangiomas.

Radiologists trained in selective angiography can now deliver sclerosing or occluding materials to the arterial supply of vascular tumors. Such skills require special training and there are limitations to the use of these materials. Specific obliteration can be carried out if this technique is quality controlled. Materials being used for embolization are continually being studied and are changing as new materials are developed. Radiologists can assist surgeons in managing some of these very difficult problems. A large series of patients with various vascular lesions treated at the Oregon Health Sciences University was reviewed. The complications of embolization used for cavernous hemangiomas have tempered our enthusiasm for it as an adjunct form of therapy. We do feel that this method of treatment remains useful in selected cases. The occlusion achieved caused a decrease in both symptoms and size of lesions treated. The decrease in size excluded the need for surgery in 3 cases, aided resection in 1, but caused significant complicating slough in 1. Five cases are presented to demonstrate problems of tissue necrosis encountered.

Adolescent↗
PubMed1984

Management of mandibular fractures in unreliable patient populations.

There is a high incidence of complications following treatment of fractures of the dentulous mandible at our institution, which has led us to scrutinize the criteria for maintaining teeth in the line of fracture and to evaluate other factors that may compromise healing of the fractured mandible, especially in an unreliable patient population. We have reviewed the opinions of various authors and agree that management decisions must be individualized. We recommend prompt and stable immobilization, adequate observation, use of a "tickle file" to keep track of missed appointments, and long-acting intramuscular prophylactic antibiotic coverage, all of which will help minimize morbidity associated with teeth in the line of mandibular fractures, especially in high-risk patients. We also recommend extraction of fully or partially erupted third molars in the line of fracture as well as deeply carious teeth, severely mobile teeth, or teeth with half or more of their root surface exposed to the fracture line. Finally, we recommend that intraoral rather than extraoral open reduction be considered when teeth are to be extracted in order to avoid contamination with the extraoral environment, to enhance surgical access, and to lower postsurgical morbidity.

Adult↗
PubMed1984

The effectiveness of prophylactic subcutaneous mastectomy in Sprague-Dawley rats induced with 7,12-dimethylbenzanthracene.

Fifty-day-old female, albino Sprague-Dawley rats were induced with DMBA, a potent carcinogen that reliably causes multiple breast tumors. Prophylactic subcutaneous mastectomy was performed 2 weeks after injection. Control animals had no breast tissue removed and developed 5.14 tumors per animal, or 1.3 tumors per quadrant. Animals subjected to 50 percent (unilateral) mastectomy developed 5.4 tumors per animal, with 0.72 tumors per surgical quadrant. Animals that underwent 75 percent (three quadrant) mastectomy developed 4.33 tumors per animal, or 0.48 tumors per surgical quadrant. The incidence of tumors was significantly reduced in the surgical areas. However, the risk of any animal developing a breast neoplasm was not reduced in direct proportion to the percentage of breast tissue removed. We believe that this model may prove valuable in evaluating prophylactic subcutaneous mastectomy.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Alterations in local blood flow and tissue-gas tension caused by epinephrine.

Subcutaneous injection of epinephrine markedly reduced local tissue pO2 levels and blood flow while increasing tissue pCO2 in a rat model. The duration and magnitude of these effects were correlated with prolonged elevation of tissue levels of epinephrine and were proportional to the amount of epinephrine injected.

Animals↗