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Biomedical subjects

R E Brownlee

Publications and source records attributed to R E Brownlee.

10 recordsLinked to original sources
PubMed1996

Transforming growth factor beta 1 improves wound healing and random flap survival in normal and irradiated rats.

OBJECTIVES: To evaluate the effect of chronic irradiation on wound healing and random flap survival (FV), and the effect of transforming growth factor beta 1 (TGF-beta 1) in this setting using an animal model. DESIGN: A randomized, controlled study with four groups of rats to study the effect of irradiation 4 months before surgical intervention. The effect of TGF-beta 1 on FV and wound healing also was evaluated in the irradiated and nonirradiated groups. SUBJECTS: Ninety-five rats were available for evaluation. Group 1 (n = 10) was the control; group 2 (n = 28) received TGF-beta 1; group 3 (n = 28) received radiation therapy; and group 4 (n = 29) received radiation therapy and TGF-beta 1. INTERVENTION: The irradiated groups received 15 Gy to their dorsal skin. Four months later all received McFarlane skin flaps. Groups 2 and 4 received topical TGF-beta 1, 4 micrograms, to the bed of the flap; groups 1 and 3 received saline. On postoperative day 7 all rats were evaluated for tensile strength and FV, and histologic staining with hematoxylin-eosin for collagen and TGF-beta 1 was done. The slides were evaluated in a "blinded" fashion. RESULTS: Irradiation decreased tensile strength and FV, but not to a notable degree. Transforming growth factor beta 1 improved tensile strength in the irradiated (P = .04, Student's t test) and nonirradiated groups (P = .05, Student's t test). Transforming growth factor beta 1 also improved FV in all groups, but significantly in the irradiation plus TGF-beta 1 group (P = .001, Student's t test). The TGF-beta 1 group had the most mature collagen present at the wound edge. No qualitative difference was seen in the immunohistochemical staining for the four groups. CONCLUSIONS: Transforming growth factor beta 1 improves wound healing and random FV in radiated and nonirradiated rat skin. Further study is needed to determine the radiation dose necessary to create an "impaired wound-healing model" in rats, and the optimum dose of TGF-beta 1 in this setting.

Administration, Topical↗
PubMed1993

Use of poly-l-aspartic acid to inhibit aminoglycoside cochlear ototoxicity.

Gentamicin is an extremely effective antibiotic against a wide variety of organisms. However, its use is limited by its nephrotoxic and ototoxic effects. Recent studies in rats have shown that poly-l-aspartic acid (PAA) effectively blocks the nephrotoxic effects of the aminoglycosides and does not decrease the antibiotic effectiveness of gentamicin against those organisms tested. A controlled test was undertaken to evaluate the effect of PAA on cochlear ototoxicity. Test solutions were administered to four groups of guinea pigs for 10 days. Group 1, the controls, received distilled water, group 2 received gentamicin, group 3 received PAA, and group 4 received gentamicin plus PAA. Auditory brainstem response thresholds at 20, 16, 8, and 4 kHz were obtained before therapy, after completion of the 10-day course, and 21 days following the completion of therapy. Two-dimensional diffusion assays in human serum were performed to evaluate the effect of PAA on the antimicrobial activity. Histologic evaluation of the cochleae was performed at the conclusion of the experiment. Threshold shifts following 10 days of therapy were not statistically significant in group 4 compared to controls, while the gentamicin group (group 2) was significantly different for all frequencies tested. At 21 days following therapy, group 4 (PAA + gentamicin) maintained significance in the higher frequencies studied. Antimicrobial studies demonstrated that PAA has no effect on the antimicrobial activity of gentamicin and has no antimicrobial effect against Bacillus subtilis when used alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Primary anastomosis of extensive facial nerve defects: an anatomic study.

Recent evidence suggests that end-to-end repair of the facial nerve with or without rerouting is functionally and cosmetically superior to grafting. Most surgical experts feel that facial nerve defects of greater than 10 mm cannot be successfully managed without grafting. Our clinical experience with mastoid-extratemporal rerouting has shown that neural defects greater than 10 mm are amenable to tension-free primary anastomosis with favorable outcome. To verify this observation, we performed the first human cadaveric study to quantify the maximal length of facial nerve defect that is amenable to a tensionless primary anastomosis. Concentrating on the region of the nerve between the second genu and the pes anserinus, four different hearing preserving rerouting procedures were performed. Our investigation demonstrated that decompression and mobilization of the facial nerve allows tension-free closure of 8.2 +/- 0.7 mm defects. Dissection of the tympanic portion of the temporal bone in addition to decompression and mobilization increases the repairable defect size to 14.0 +/- 1.7 mm. Retroposition of the parotid gland adds roughly 3.5 mm to the length of facial nerve gained with either of the above procedures. The most extensive mastoid-extratemporal rerouting procedure with retroposition of the parotid gland, which we refer to as radical temporofacial rerouting of the facial nerve, allows closure of neural defects of 17.6 +/- 1.7 mm. Our results should encourage surgeons to repair facial nerve defects of between 10 and 17 mm by rerouting with primary anastomosis, rather than by grafting.

Adenoma↗
PubMed1992

Ciprofloxacin. Use as a topical otic preparation.

Most common topical otic preparations have been shown to cause sensorineural hearing loss and hair-cell damage in experimental animals. Ciprofloxacin is a relatively new fluoroquinolone with excellent activity against Pseudomonas and methicillin-resistant Staphylococcus aureus. Recent studies have shown oral ciprofloxacin to be effective in the treatment of chronic serous otitis media and malignant external otitis. However, this drug has never been used as a topical otic preparation. Thirty-five albino female guinea pigs were used to investigate the ototoxicity of topical ciprofloxacin hydrochloride. Bilateral transbullae drug delivery tubes were placed and auditory brain-stem response thresholds were recorded at 20, 16, 8, and 4 kHz before treatment and 21 days after the completion of treatment. Two groups of guinea pigs were used. In group 1 (positive controls), five guinea pigs had 0.1 mL of neomycin sulfate administered in one ear while the opposite (control) ear received 0.1 mL of 0.9% sodium chloride solution; in group 2, 30 guinea pigs received 0.75% ciprofloxacin ophthalmic solution and 0.9% sodium chloride solution in the control ear. All drugs were given twice a day for 7 consecutive days. All results were evaluated with paired, two-tailed t test and Hotelling's T2 test, and calculation of power was performed on all nonsignificant results. No significant ototoxic reaction was observed; small increases in hearing thresholds occurred at 4 (5.65 +/- 8.25 dB [mean +/- SD]) and 8 kHz (3.70 +/- 6.63 dB [mean +/- SD]) in the ciprofloxacin-treated ears; however, no significant hair-cell loss was seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1992

Thyroid paraganglioma.

Paraganglioma of the thyroid gland is a rare neoplasm. Only eight cases have previously been reported. The neoplasm was confined to the thyroid in all but two patients; laryngeal involvement was seen in one and tracheal involvement in another. A review of these previously reported cases is presented along with the details of an additional case with laryngeal involvement. Laryngeal and thyroid paragangliomas are compared and contrasted. The anatomic and embryologic basis of these tumors and the diagnosis and treatment are discussed. We suggest changing the nomenclature and reporting of these lesions on the basis of their apparent common origin. Surgery remains the treatment of choice in most paragangliomas, including those involving the larynx and thyroid. Although the number of reported cases is small, there have been no cases of distant metastases or local recurrence after adequate surgical removal.

Adult↗
PubMed1991

Acquired von Willebrand's syndrome. Therapeutic and diagnostic implications.

Acquired von Willebrand's syndrome is a newly recognized bleeding diathesis thought to be caused by autoantibodies to the von Willebrand factor. Acquired von Willebrand's syndrome has been reported in association with lymphoproliferative disorders and benign monoclonal gammopathies. Clinical features and laboratory abnormalities of this disease are similar to congenital von Willebrand's disease, but the optimal treatment may differ. We describe a 75-year-old man with chronic lymphocytic leukemia and recurrent epistaxis and also discuss the pathogenesis, diagnosis, and treatment of both the congenital and acquired disorders.

Aged↗
PubMed1990

Orbital complications of sickle cell disease.

Swelling and pain of the peri-orbital tissues in patients with sickle cell disease has been described. This has most often been ascribed to orbital apex syndrome, but there are recent reports in the literature of frontal bone infarctions compounding this syndrome. We will present a case report of a child with sickle cell disease with bilateral orbital abscesses and frontal bone infarctions. The literature pertaining to the diagnosis and treatment of the orbital complications of sickle cell disease is reviewed. We stress that intravenous antibiotics are not adequate therapy for orbital abscesses and that these must be drained surgically.

Abscess↗