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Biomedical subjects

T A Cook

Publications and source records attributed to T A Cook.

At least 55 records · Page 3Linked to original sources
PubMed1995

Autologous free dermal fat graft. Reconstruction of facial contour defects.

OBJECTIVE: To examine the use of autologous free dermal fat grafts (FDFGs) in the reconstruction of soft-tissue facial contour defects, an 8-year, retrospective, computerized medical chart review was conducted for 21 patients who underwent reconstruction with FDFGs. SETTING: Section of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology, Oregon Health Sciences University, Portland, or affiliated hospitals. PATIENTS: Twenty-one patients identified in the chart review were included in the retrospective evaluation. Follow-up periods ranged from 11 to 94 months. Five patients were unavailable for follow-up at the chart review, but all five had satisfactory results at their last evaluation. DESIGN: Soft-tissue augmentation was performed using autologous FDFGs harvested from the abdomen following in situ de-epithelialization with a high-speed dermabrader. Facial contour defects resulted from tumor extirpation, congenital deformity, trauma, or degenerative disease. MAIN OUTCOME MEASURES: Outcome was considered satisfactory when the patient and the surgeon were pleased with the long-term results at the last evaluation. RESULTS: Complications, including graft resorption (five patients) and epithelial cyst formation (two patients), were observed in seven patients and resulted in an unsatisfactory outcome. The remaining 14 patients demonstrated satisfactory results as determined by the patient and the surgeon at the last evaluation. CONCLUSIONS: Successful long-term augmentation of facial contour defects may be achieved with autologous FDFGs in an appropriate patient population. Careful patient selection and proper surgical technique are essential for satisfactory long-term results. Guidelines are provided for the augmentation of facial contour defects with autologous FDFGs.

Adipose Tissue↗
PubMed1995

Ketorolac (Toradol) and acute random-pattern skin flap survival in rat.

OBJECTIVE: To assess the efficacy of sustained postoperative intramuscular ketorolac tromethamine (Toradol) at analgesic levels in the augmentation of acute, random-pattern skin flaps in rat. DESIGN: Prospective, randomized, placebo-controlled, animal trial. SETTING: Animal research laboratory, School of Medicine, Oregon Health Sciences University, Portland. SUBJECTS: Forty-four adult male Sprague-Dawley rats (260 to 280 g). INTERVENTIONS: Twenty-two treatment animals underwent modified McFarlane random-pattern skin flaps followed immediately by intramuscular loading doses of ketorolac. Treatment animals were then maintained on a regimen of intramuscular ketorolac using a three times a day dosing schedule for 14 days postoperatively. Twenty-two control animals underwent identical modified McFarlane random-pattern skin flaps and were given equivalent volumes of intramuscular saline on the same dosing schedule for the 14-day treatment period. MAIN OUTCOME MEASURES: Postmortem measurements of skin flap ischemia (expressed as a percentage of total flap surface area) were performed for both treatment and control animals by three independent, non-blinded observers using the acetate tracing technique. Both pooled and individual data were statistically analyzed using personal computer software. RESULTS: Forty-three of the 44 animals successfully completed the experimental trial. One animal in the treatment group died on postoperative day 3 of unknown causes. During the study period, one postoperative hematoma was detected in both the treatment and control groups. The mean percentage of skin flap ischemic necrosis observed in control animals (35.4%) was consistently less than that measured in the treatment group (36.4%). However, the difference in ischemic flap necrosis between control and treatment groups was not statistically significant (P = .6919). CONCLUSIONS: Comparatively high-dose intramuscular ketorolac failed to augment acute, random-pattern skin flap survival in rat when initiated in the immediate postoperative period. Complications of prolonged, intramuscular ketorolac were not observed in this trial. Further studies using preoperative initiation of drug therapy may help to clarify the true efficacy of ketorolac in flap augmentation.

Analgesics↗
PubMed1995

The epithelial 'turn-in' flap in nasal reconstruction.

OBJECTIVES: To evaluate the epithelial "turn-in" flap for reconstruction of the internal lining in full-thickness nasal defects. Highlighted are its indications, technique, complications, and clinical success, particularly in comparison with the other common modalities for reconstructing this nasal lining. Also, to determine how the random flap withstands vigorous thinning. DESIGN: A retrospective chart review and clinical follow-up of all patients with full-thickness nasal defects of the nose. SETTING: The patient pool comes from a tertiary care center that draws from a large geographic area in the Northwest. Both urban and rural demographics are represented. PATIENTS: Fifty-six patients with large full-thickness nasal defects were reviewed, 18 of which were reconstructed with the epithelial turn-in flap. The causes of the original defect were varied. INTERVENTION: Full-thickness nasal defects were reconstructed in a layered fashion. The turn-in flaps were aggressively thinned to the subdermal plane to minimize flap bulk and airway compromise. MAIN OUTCOME MEASURES: Attention was made to the size and precise location of the defect, the mode of reconstruction, flap viability, and nasal function. RESULTS: Eighteen patients had turn-in flaps for reconstruction of the internal lining. Sixteen patients (89%) had 100% viability of their flaps. Seventeen (94%) reported normal nasal function. CONCLUSIONS: The epithelial turn-in flap is a robust flap that provides dependable and functional results. One of the major advantages of this flap over other methods is that often there is no donor site morbidity. For many select defects, the turn-in flap remains a method of choice for repair of the internal lining.

Adolescent↗
PubMed1995

Auricular reconstruction.

1. Treat the underlying etiology: In cases of cancer, assure complete excision by using Mohs surgery. In cases of trauma, assure complete debridement of necrotic tissue and bring in healthy viable, well-vascularized tissue. 2. Assess the defect in detail: Analyze the defect in regard to composition (skin, cartilage, or both), effect of cartilaginous loss on overall structure, and need for cartilaginous replacement. 3. Skin only (FTSG or flap) is often enough: Wait 3 months after flap transposition before placing any subcutaneous graft material. 4. Treat the three "levels" as separate units. When advancing chondrocutaneous flaps in primary closure or rotating the entire ear in wedge resection closure, care should be taken to preserve the individual three level tiers (conchal bowl, scapha, helical rim/ lobule). 5. Use flap edema creatively. 6. Rarely consider total reconstruction in the adult.

Adult↗
PubMed1995

The leather ankle lacer.

The purpose of this study was to evaluate the efficacy of a leather ankle lacer for treating painful problems of the ankle and hindfoot. The evaluation involved patient self assessment, clinical examination and radiographic determination of the effectiveness of the ankle lacer. Overall, patients had moderate pain relief with significant but not complete restriction of motion. Based on this study and our clinical experience, we find the leather ankle lacer to be a compliant and comfortable treatment strategy for patients with painful ankle and hindfoot problems who desire some retained motion.

Aged↗
PubMed1994

Amino acid residues lining the chloride channel of the cystic fibrosis transmembrane conductance regulator.

The cystic fibrosis transmembrane conductance regulator forms a chloride channel that is regulated by phosphorylation and intracellular ATP levels. The structure of the channel-forming domains is undetermined. To identify the residues lining this channel we substituted cysteine, one at a time, for 9 consecutive residues (91-99) in the M1 membrane-spanning segment. The cysteine substitution mutants were expressed in Xenopus oocytes. We determined the accessibility of the engineered cysteine to charged, sulfhydryl-specific methanethiosulfonate reagents added extracellularly. We assume that, among residues in membrane-spanning segments, only those lining the channel will be accessible to react with these hydrophilic reagents and that such a reaction would irreversibly alter conduction through the channel. Only the cysteines substituted for Gly-91, Lys-95, and Gln-98 were accessible to the reagents. We conclude that these residues are in the channel lining. The periodicity of these residues is consistent with an alpha-helical secondary structure.

Amino Acid Sequence↗
PubMed1994

Identification of dynamin 2, an isoform ubiquitously expressed in rat tissues.

Dynamin is a 100-kDa microtubule-activated GTPase originally isolated from mammalian brain that has been proposed to be crucial in the early steps of endocytosis. Previous studies on the primary structure, biochemical properties, and functional role of dynamin indicated that it was neuron-specific. However, using an antibody against a synthetic peptide representing an enzymatic region of rat brain dynamin (D100), we identified a 100-kDa protein doublet in rat liver, suggesting that dynamin exists as different isoforms that are distinct from the brain counterpart. We then initiated a search for distinctive dynamin isoforms with antibodies and cDNA probes. A 500-bp PCR-generated cDNA probe corresponding to the enzymatic region of the rat brain dynamin-encoding gene was used to isolate six overlapping clones from a rat liver cDNA library that together span the complete coding sequence of another dynamin gene, "Dyn2." Sequence analyses reveal that dynamin 2 (Dyn2) is 75% identical to brain dynamin at the DNA level and is 79% identical at the protein level. By Northern blot analysis and isoform-specific PCR, Dyn2 was found ubiquitously in adult rat tissues as two transcripts of 3.5 kb and 4 kb; the highest levels were found in testis. These results indicate that dynamin proteins are encoded by at least two genes expressed differentially in mammalian tissues and that the expression of Dyn2, and not of brain dynamin, accounts for the ubiquitous distribution of dynamin in rat tissues.

Amino Acid Sequence↗
PubMed1993

Laboratory and animal model evaluation of the Cryotech LCS 2000 in hepatic cryotherapy.

Hepatic cryotherapy is increasingly used in the treatment of patients with multiple hepatic metastases, particularly from colorectal cancer. The Cryotech LCS 2000 system, with insulated shaft-circulated liquid nitrogen probes, was designed for this purpose and was evaluated on the bench and in an animal model. The 9-mm probe was considerably more effective than the 5-mm probe when judged on time to create an iceball of a given diameter. The use of thawing gas reduced the time until the probe could be removed from 25 to 5 min but heated gas only produced a further reduction of 2 min. In the animal model, significant reduction in treatment times occurred with vascular inflow occlusion. The zone of necrosis as a percentage of the original iceball diameter was significantly higher following a twin freeze/thaw cycle. The relationship of the edge of the iceball to the eventual zone of hepatic necrosis was studied using different unabsorbable markers. India ink and sutures proved unreliable but a Teflon cannula was more successful and the margin was only of the order of 2 mm. The discrepancy between this observation and the percentage of the original iceball diameter which apparently becomes necrotic (64 and 82%) for single- and double-freeze lesions, respectively, suggests that the cryolesion undergoes shrinkage within 1 month and that the diameter of necrosis underestimates the true zone of destruction.

Animals↗
PubMed1993

Assessment of survival and microscopic changes in porcine skin flaps undergoing immediate intraoperative tissue expansion.

The technique of rapid intraoperative tissue expansion has been used with increasing frequency in the clinical setting over the last several years. This technique takes advantage of the skin's ability to immediately stretch and increase in surface area when expanded under a constant load. Sixteen random-pattern, rapidly expanded skin flaps on 10 domestic male pigs were studied to assess the predictive value of the fluorescein test for flap viability after rapid intraoperative tissue expansion. Partial fluorescence was found to be a more accurate predictor of flap survival in the experimental rapidly expanded flaps when compared to full fluorescence. Partial fluorescence was found to under-predict flap survival by 0.3 to 0.5 cm, whereas full fluorescence was found to under-predict flap survival by 2.5 cm. Additionally, histologic and ultrastructural changes were examined in rapidly expanded skin from the hip region in three pigs. The only microscopic change noted between control and experimental flaps was dilated capillaries in the dermis of expanded skin, which was noted by electron microscopy. Collagen and elastic tissue changes were not demonstrated in rapidly expanded pig skin by electron microscopy, direct immunofluorescence, collagen, and elastic tissue stains.

Animals↗
PubMed1993

The growth of carcinogen-induced colon cancer in rats is inhibited by cimetidine.

Colon cancer was induced in 40 Sprague Dawley rats using a 10-week course of 1,2 dimethylhydrazine (DMH). Twenty animals received cimetidine in their drinking water, commencing 5 weeks after concluding the course of DMH. After five weeks treatment of the animals were sacrificed and the colon and rectum excised. Tumours were assessed histologically for depth of invasion, inflammatory cell response and stained for Proliferating Cell Nuclear Antigen (PCNA), as a measure of tumour proliferative index. PCNA staining was measured using a computerized image analysis system. There were 25 tumours in the cimetidine treated group and 20 in controls. In the control group, 10% of the tumours were benign, 35% malignant polyps, 40% invading through submucosa and 15% invading through the bowel wall, as opposed to 40%, 44%, 8% and 8%, respectively in the cimetidine group (Chi squared test: P = 0.002). The mean proliferative index for control tumours was 27.9% and for the cimetidine tumours 23.1% t test: P = 0.002). It is concluded that cimetidine inhibits colon cancer cellular proliferation and slows early tumour invasion in this animal model.

1,2-Dimethylhydrazine↗
PubMed1992

Rhinoplasty surgery.

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Adrenal Cortex Hormones↗
PubMed1992

Amputation level is not adversely affected by previous femorodistal bypass surgery.

Data was reviewed on patients presenting with lower limb-threatening ischaemia to a single vascular unit between September 1984 and December 1990. Three hundred and thirty patients underwent either femoro-popliteal or femoro-infrapopliteal reconstructive surgery and 316 primary amputations were performed on 281 patients. Sixty-three secondary amputations were performed following a femoro-distal bypass failure. The below-knee amputation to above-knee amputation ratio (BKA/AKA) was 1.0 in the primary amputation group to 0.91 in the secondary amputation group. A direct comparison cannot be made as the patients represent two separate clinical groups. The ratio of reconstructive operations to primary amputations more than doubled between the first and second halves of the study. The BKA:AKA ratio in the secondary amputation group and the total number of secondary amputations remained relatively constant. This study supports the view that previous femoro-distal surgery does not adversely affect the overall outcome of amputation.

Aged↗