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Biomedical subjects

W W Shaw

Publications and source records attributed to W W Shaw.

106 records · Page 6Linked to original sources
PubMed1981

The effects of preservation on microvascular vein grafts in rats.

Segments 15 mm in length were excised from the femoral veins of rats and preserved by refrigeration at 4 C in lactated Ringer's solution for periods up to 21 days. The findings show that veins can be preserved for up to seven days and successfully grafted to recipients. Although there was some success in preserving vein segments for more than seven days, a high rate of thrombosis occurred after implantation in the recipients. It is generally accepted that damaged endothelium causes thrombosis. The light and electron microscopic observations in this study, however, suggest that the condition of the endothelium may not be the only important factor in the patency of small vessels. A thickened and prominent elastic lamina may also play a role in keeping the lumen open.

Animals↗
PubMed1981

Immediate reconstruction of full-thickness chest wall defects.

Twenty-one patients had full-thickness chest wall defects reconstructed at the New York University Medical Center in the last ten years. Marlex mesh provided chest wall stability in 5 patients. In 9 patients with radiation ulcers Marlex mesh was not required; a severe fibrotic reaction had obliterated the pleural space and prevented paradoxical motion. Partial sternal resections did not require Marlex stabilization, while a total sternectomy resulted in marked ventilatory insufficiency in a patient who would have benefited from the use of a stabilizing material. Random pattern flaps were used initially; more recently, axial pattern, myocutaneous, and myocutaneous free flaps were employed. Necrosis developed in 4 (36%) of the 11 patients with random pattern flaps, but was not seen with the newer flap techniques. Myocutaneous free flaps provided uncomplicated coverage of and stability to three large, potentially contaminated defects. It seems that with the currently available flap techniques and the methods of chest wall stabilization, immediate repair of all full-thickness chest wall defects is possible.

Adult↗
PubMed1980

Microvascular free dermis-fat flaps for reconstruction after ablative head and neck surgery.

Reconstruction of the head and neck region following radical parotidectomy with or without mandibulectomy may be a difficult procedure. Facial skin is usually preserved, but the underlying soft-tissue structures and bone are deficient. The challenge is to augment the facial defect while the overlying skin is preserved with a high success rate, minimal time, one operative stage, and reduced secondary deformity to the patient. In certain instances, a microvascular free flap is ideal. We have used a de-epithelialized microvascular free groin flap successfully to reconstruct large parotid-mandibular defects in nine patients. A small bridge of epithelium is left to relieve tension from edema and to monitor the flap postoperatively. The high success rate, minimal complications, and acceptable donor site defect make the microvascular free dermis-fat flap an ideal choice for this type of reconstruction.

Adolescent↗
PubMed1980

The effects of short-term preservation on microvascular free groin flaps in rats.

Free groin flaps taken from rats were preserved by refrigeration at 4 degrees C in either lactated Ringers solution or tissue culture medium for various periods of time. The results indicate that a high survival rate can be expected at periods up to 72 hours, but there was no success in preserving flaps longer than 72 hours. These preliminary experimental findings suggest that, clinically, a high survival rate can be achieved in free flaps following excision from donor sites even if the microvascular transfer must be postponed for a period up to but not exceeding 48 hours.

Animals↗
PubMed1980

The microvascular technique of vein grafting in rats as a training and experimental model.

Techniques for obtaining and implanting vein grafts in the femoral arteries of rats are described. Grafts 5 mm in length can be removed from the femoral vein without ligating any side branches; a 15-mm segment is the maximum graft that can be obtained from the femoral vein in a rat. This requires ligation and division of all the branches between the inguinal ligament and the great saphenous vein. The superficial epigastric vein also can be used as a source of grafts to be used in the femoral artery. In this study, neither the femoral nor the superficial epigastric vein appeared to have functioning valves. Therefore, reversing the vein graft before implantation was not necessary.

Animals↗
PubMed1979

Conservation of major leg arteries when used as recipient supply for a free flap.

The potential hazards of using proximal segments of leg arteries for end-to-end anastomosis to vessels in free flaps are examined, and alternatives are proposed. The convservation of the major tibial arteries seems highly desirable, to minimize any subsequent development of ischemic complications. Turning a free flap upside down moves the anastomosis to the distal part of the extremity, thus conserving most of the muscular branches of the recipient artery. Cutting the recipient artery distally and bending it back in recurrent fashion also allows for easy end-to-end anastomosis, with many technical advantages.

Adult↗
PubMed1979

Assessment of the healing potentials of ulcers of the skin by photoplethysmography.

An objective method of assessing the healing potentials of skin ulcers would eliminate the long waiting period necessary for visual evidence of healing or nonhealing to appear. This would permit the continued conservative treatment for healing ulcers and prompt surgical interventions for those ulcers which are nonhealing. In this preliminary study, the cutaneous blood flow immediately around the ulcer site was studied using the photoplethysmograph. Vigorous cutaneous blood flow shown by good pulsatile wave forms on the photoplethysmograph is shown to be indicative of an ongoing healing process in which spontaneous healing of the ulcer can be predicted. Ulcers with nonpulsatile wave forms fail to heal with conservative management. One patient with nonpulsatile wave forms at the ulcer site showed improvement and eventual healing of the ulcer after undergoing a lumbar sympathectomy. Thus, nonpulsatile blood flow shown by poor wave forms on the photoplethysmograph would suggest early surgical intervention. This method may also aid in determining the extent of surgical excision of the ischemic scar tissue surrounding the chronic skin ulcer.

Humans↗
PubMedDate not supplied

Residual silicone detection using MRI following previous breast implant removal: case reports.

The current controversy surrounding the safety of silicone gel breast implants has resulted in an increasing number being removed. Although previous reports have suggested that remnants of the implant capsule are reabsorbed after explantation surgery, the persistence of the capsule in fact may be associated with implant fragments and silicone gel leakage. In this study we have used magnetic resonance imaging (MRI) to identify residual silicone gel and silicone granulomas following the removal of silicone gel breast implants. Four representative clinical case reports are presented. These patients, who had residual silicone present in their bodies, presented to us with breast pain, palpable masses, or abnormal calcific mass densities apparent on a mammogram. High-resolution MRI images were found to be helpful in identifying local and remote collections of silicone gel, silicone granulomas, and residual capsules that were incompletely removed from previous explantation surgery. MRI breast images demonstrated high resolution and provided the accurate anatomical locations of residual silicone gel and silicone granulomas in all the regions of breast parenchyma, chest wall muscles, and axillae. Patients with persistent local symptoms following explantation surgery may benefit from an evaluation of the breast using MRI.

Adult↗
PubMedDate not supplied

The effect of basic fibroblast growth factor on the neovascularisation process: skin flap survival and staged flap transfers.

Forty-two male Sprague-Dawley rats were utilised to determine whether the angiogenic property of basic fibroblast growth factor (bFGF) could be applied to improve the survival of the ischaemic portion of a random skin flap and to accelerate the process of staged flap transfer. In the ischaemic flap model, bFGF enhanced the development of vascular connections between the bed and the flap and prevented marginally perfused areas from undergoing necrosis. No effect was observed in the staged reconstruction model using the same dosage of bFGF. A speculative explanation is given for the differential effect of BFGF in these two models. The application of angiogenic factors may improve the survival of the random portion of skin flaps. Further investigations are needed to determine whether exogenously applied angiogenic factors can have a beneficial effect in staged flap reconstructions.

Angiogenesis Inducing Agents↗
PubMedDate not supplied

The fasciovascular flap: a new vehicle for islet transplantation.

In order to determine whether pancreatic islets could be neovascularized by a fasciovascular flap (FVP), islet transplant studies were conducted in Lewis rats. Islets from two donors were isolated by collagenase digestion and discontinuous gradient centrifugation on Ficoll. These islets were injected in syngeneic recipients either into random groin SC fat as a control, or into a flap composed of fascia and fat elevated from the groin based on the superficial inferior epigastric vessels. After two wk, islet viability was assessed by histological analysis. The degree of neovascularization of the islet tissue was evaluated with India ink injection through the vascular pedicle. Whereas control islets degenerated and did not show clear signs of neovascularization, FVP-islets showed rich neovascularization and viability as a large sheet of islet clusters. These results have demonstrated that the FVP-flap is a novel recipient site which can support a large quantity of islet tissue. This model constitutes a unique neo-endocrine pancreas flap, which can be subsequently transplanted at will to transfer the established neo-endocrine pancreas to a desired site using microvascular surgical technique.

Adipose Tissue↗