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Biomedical subjects

M Spira

Publications and source records attributed to M Spira.

At least 55 records · Page 3Linked to original sources
PubMed1991

Study of microcirculation of rat femoral nerve and development of a new vascularized nerve graft model.

This study was designed to investigate the microcirculation of the rat femoral nerve and to develop a vascularized nerve graft (VNG) model which is reliable, consistent, and simple. The rat was chosen for considerations of cost and simplicity of the model. One and 2 cm long femoral nerve segments were transected proximally and distally and left attached to the femoral artery and vein in all animals. Experimental groups included the following procedures: 1) the femoral artery and vein were ligated distally and an arteriovenous (AV) fistula just proximal to the ligature was constructed; 2) distal ligation only of the femoral artery and vein was done; 3) ligation of the femoral artery and vein was done both distally and proximally; 4) control: no ligation or construction of an AV fistula were done. Neurovascular segments in all groups were wrapped with a thin silicone sheath to prevent neurovascularization from the surrounding tissues. At seven days postoperatively, viability of the segments was assessed by fluorescein dye and microangiography studies, followed by histologic evaluation. Results showed that a 1- or 2-cm long femoral nerve segment, when left attached to distally ligated femoral vessels and an intact neurovascular sheath, is a simple design to reproduce and can serve reliably as a VNG model in the rat.

Animals↗
PubMed1991

A new flap model in the rat.

Standardized skin flap models in the rat, such as the McFarlane and Finseth flaps, have suggested placement on the rat of only a single flap. The single flap, because of variations in skin vasculature among rats, may be problematic and require prohibitively large numbers of rats to obtain statistically significant results. In this study of 60 Sprague-Dawley rats, we have developed a flap model designed to be paired in a single rat and standardized to serve as the experimental flap and the control. At the level of the symphysis pubis, symmetrical, three-sided, caudally based, bilateral skin flaps, 2 cm in width, were extended to different bony landmarks. Only the length of the flaps was varied. The inferior epigastric pedicle was then divided. The flap length, which optimally produced predictable and persistent necrosis, was found midway between the xiphoid and the sternal notch. The model was pharmacologically manipulated with the injection of superoxide dismutase through the epigastric vein before division of the inferior epigastric pedicle; this scavenger did not effect the survival of the random pattern flaps.

Animals↗
PubMed1991

The trauma of suction-assisted lipectomy cannula on flap circulation in rats.

The effect of suction-assisted lipectomy on cutaneous blood vessels of inguinal skin flaps was studied and compared in 191 rats. Different types of cannula tips were used; the number of passes was standardized. In one experiment, following suctioning, 3 X 2 cm groin island flaps based on inferior epigastric pedicles were raised and then reattached. Fluorescein dye study and microangiography were performed to evaluate flap viability. Flap survival was determined clinically and by histologic examination on the fifth postoperative day. Three-sided inguinal random-pattern flaps were raised in a second experiment and reattached following suctioning. On the fifth postoperative day, surviving flap areas were measured using standard photographs and an imaging computer and were compared with controls. Results showed that cannula passes accompanied by vacuum are harmful to vessels, while those unaccompanied by vacuum are not. The greater the number of suctioning passes, the more trauma there is to vessels and the greater is the likelihood of flap necrosis. Conical and spatula tips were more harmful to vessels than spherical, cobra, keel cobra, or Fournier tips. These results support the conclusion that suction-assisted lipectomy enhances the possibility of skin necrosis by traumatizing the vascular pedicle of a flap, especially when it is used as an adjunct to flap elevation.

Animals↗
PubMed1990

Reconstructing the breast mound employing a secondary island omental skin flap.

We have shown in an initial animal study that omentum will adequately vascularize a skin flap and allow transfer of this tissue composite for use in surgical reconstruction of the breast. Based on this experimental procedure, a technique employing a two-stage operation has been developed and used in 21 female patients in reconstruction of the breast after radical mastectomy. In the first stage, the omentum, attached to one gastroepiploic artery and vein, is exteriorized to the subcutaneous tissue of the lower abdominal wall. In the second stage, the distal omentum, now vascularizing the overlying skin and soft tissue, is moved as a secondary island flap to the anterior chest wall to complete the breast reconstruction. In all but 1 of our 21 patients who have been followed for 1 to 8 years, reconstruction of large defects, including the chest wall, breast mound, and infraclavicular axillary fold depression, was performed without use of a prosthesis. In one patient, there was complete necrosis of the flap due to vascular impairment; there were three instances of delayed healing and a significant but partial loss of the flap in one patient. All complications were encountered in the first 10 patients of the series during the time the technique was being refined.

Adolescent↗
PubMed1990

Aesthetic considerations and the pediatric population.

Aesthetic surgery is the natural evolution of reconstructive surgery done to improve a patient's form in addition to function. This becomes especially critical in the pediatric age group in which patients are constantly evolving and their concepts of self-esteem and body image are so fragile.

Adolescent↗
PubMed1989

The growth of human fibroblasts and A431 epidermoid carcinoma cells on gamma-irradiated human amnion collagen substrata.

Human fibroblasts and A431 human epidermoid carcinoma cells were cultured on gamma-irradiated human amnion collagen as well as on plastic dishes and non-irradiated collagen coated dishes. The morphology, attachment, growth and short-term cytotoxicity of these culture conditions have been determined. Both irradiated and non-irradiated amnion collagen enhanced the attachment and proliferation of fibroblasts as compared to the plastic dishes. No differences in these properties were observed for A431 cells cultured on irradiated collagen when compared with culture on non-irradiated collagen substrates. Cytotoxicity assays showed that irradiated and non-irradiated collagens were not cytotoxic for either fibroblasts or A431 cells. The results demonstrated that amnion collagen irradiated at doses of 0.25-2.0 Mrads is optimal for cell growth.

Amnion↗
PubMed1989

The effect of gamma irradiation on injectable human amnion collagen.

The effect of gamma irradiation on the physicochemical properties of injectable human amnion collagen was investigated. Pepsin-extracted human amnion collagen was purified, reconstituted, and irradiated with varying doses of gamma irradiation (0.25 Mrads to 2.5 Mrads). Gamma irradiation had a significant impact on the physical characteristics of the collagen. The neutral solubility of collagen in PBS at 45 degrees C was decreased from 100% for the nonirradiated control sample to 16% for the 2.5 Mrads irradiated sample. SDS polyacrylamide gel electrophoresis also demonstrated the dose-dependent effect of gamma irradiation on collagen cross-links. Electron microscopic observation revealed that even at low irradiation dose (0.25 Mrads), collagen fibril diameter increased. The average diameter was 50 nm for nonirradiated control fibrils, while 4.4 percent of the irradiated collagen fibrils had a diameter greater than 100 nm. Irradiated collagen showed little evidence of damage. Well-preserved cross-striations were found in collagen fibrils at all doses of irradiation. Native amnion collagen irradiated with gamma rays demonstrated a slight increase in resistance to collagenase degradation compared with nonirradiated native collagen samples. Increased resistance to collagenase did not correlate with increasing irradiation dose. After 30 min of incubation at 37 degrees C, both irradiated and nonirradiated collagen was completely digested by collagenase. However, gamma-irradiated collagen did become more sensitive to hydrolysis by trypsin. The higher the irradiation doses used, the greater sensitivity to trypsin was observed. At 0.25 Mrads irradiation only a slight increase was found. No marked differences in amino acid composition were noted among the high dose irradiated, low dose irradiated and control amnion collagen.

Amino Acids↗
PubMed1989

Evaluation of axonal specificity of the regenerating rat sciatic nerve using a fluorescent labeling technique.

A double-labeling technique using fluorescent compounds, i.e., diamidino yellow and true blue, is described, with the divided rat sciatic nerve model. Tibial and peroneal fascicles were transected, and each freshly cut nerve end was placed in a vial containing either the true blue or the diamidino yellow label. After a 10-15 day survival period, animals were systemically perfused with fixative, and the lumbar enlargement and dorsal root ganglia corresponding to sciatic nerve roots were removed. Serial sectioning and examination with ultraviolet fluorescence microscopy and counts of the labeled cells were performed. Diamidino yellow in labeled cells was found localized to the nucleus, whereas true blue was found localized to the cytoplasm and nucleolus (control group n = 5). Intermixing of these pools was noted, with yellow cells seen among blue labeled cells following nerve autograft repair of a 1 cm segment of the rat sciatic nerve (experimental group n = 5). Double-labeled cells displaying a yellow nucleus and a blue cytoplasmic label were also seen. We believe that the double-labeling technique described, using the fluorescent retrograde tracers diamidino yellow and true blue, is a useful monitoring method for assessing the specificity of regenerating axons in the rat sciatic nerve.

Amidines↗
PubMed1989

Reliability of sciatic function index in assessing nerve regeneration across a 1 cm gap.

To evaluate the validity of sciatic function index as a reliable functional parameter in assessing regeneration of rat sciatic nerve through a 1 cm gap, we undertook the following investigation. Sixty-three adult male Sprague-Dawley rats were assigned to four groups for repair of a 1 cm gap created in the right rat sciatic nerve; 19 rats were repaired with amniotic collagen conduits, 20 with nerve autograft, and 17 with silicone tubes. In seven rats, the gap was not repaired and served as a control. Functional recovery was assessed by de-Medinaceli SFI and by clinical observations, compared with quantitative and qualitative histological results at 4, 10, and 17 weeks postoperatively. The SFI results did not correlate with the histological findings and clinical observations over the observation period in all groups.

Animals↗
PubMed1989

Nasal alar reconstruction with an ear helix free flap.

Reconstruction of full-thickness defects of the nasal alae has always been a challenge. Local flaps are commonly used but often result in facial scars and bulky alae that require secondary revisions. The structural similarities between the nasal alae and auricular helices have allowed the use of free helical composite grafts to repair small nasal defects of less than 2.0 cm. Recent delineation of vascular territories of the ear has allowed the use of vascularized helical free flaps in the repair of large alar defects. Successful reconstruction of a 3.2 cm x 3.0 cm full-thickness alar defect, with a chondrocutaneous microsurgical free flap from the root of the auricular helix, is presented. The reconstruction was satisfactory as to contour, symmetry, and color match over a one year follow-up.

Adult↗
PubMed1989

Adjunctive agents to facilitate rapid tissue expansion.

A rodent model was used to study tissue expansion. Three chemical agents--hyaluronidase, prostaglandin E2, and colchicine--were administered and their effects on tissue expansion studied. Hyaluronidase and colchicine both enhanced the rate of expansion when compared with results in control animals (p less than 0.05). Although prostaglandin E2 had less effect on expansion rate, it did significantly enhance tissue oxygen tension of expanded skin when compared with controls (p less than 0.05). Clinical implications include the possibility of pretreating patients with these agents to increase the rate of expansion and to improve the safety of current methods of expansion.

Animals↗
PubMed1989

Immune response to gamma-irradiated injectable human amnion and human skin collagens in the rat.

The immune response in rats to gamma-irradiated human amnion and human skin collagen was characterized through histologic and immunologic methods. Pepsin-extracted human amnion collagen and skin collagen were purified and reconstituted. Implants of amnion collagen demonstrated greater persistence than skin collagen. For amnion collagen implants, no significant inflammatory response was found. Fibroblast and adipocyte ingrowth and neovascularization were present. Conversely, obvious inflammatory infiltration was evident in the skin collagen implants. Enzyme-linked immunosorbent assay results showed that anti-amnion collagen antibody levels were significantly lower than anti-skin collagen antibody levels against their respective implant materials. The ratios of type I to type III collagen are 56:44 and 95:5 for amnion collagen and skin collagen, respectively. These findings suggest that in this heterologous type system, type III collagen-rich amnion collagen preparations appear superior to skin collagen for soft-tissue augmentation.

Amnion↗
PubMed1988

Bacterial challenge study of a porous carbon percutaneous implant.

Numerous percutaneous devices for power transmission and control to electrically powered, intracorporeal blood pumps have been used for periods ranging from 12 months to 4 yrs; however, consistent and reliable performance has not been achieved, due most frequently to the development of infection and sinus tracts at the percutaneous lead exit site. The present study showed that percutaneous devices fabricated from porous vitreous carbon can function satisfactorily in vivo over extended periods. The implant sites successfully resisted infection by normal flora bacteria for as long as 48 months, although superficial surface colonization and infection did occur after deliberate application of pathogens.

Animals↗
PubMed1987

Treatment of bilateral axillary hyperhidrosis by suction-assisted lipolysis technique.

Axillary hyperhidrosis, although not life-threatening, is a troublesome condition which produces a personal and social handicap of great significance to patients for many years before they seek a cure. Treatment has consisted of application of topical antiperspirants, systemic anticholinergic medications, excision and primary closure of the involved axillary skin, subdermal shaving of the subcutaneous fat pad containing the hypersecreting sweat glands, and combinations of all of the above. Medical treatment is frequently inadequate and surgical techniques so far described may carry significant morbidity. We have used the technique of suction-assisted lipolysis as an alternative method of treatment for this condition. The procedure has been employed successfully in one patient with no recurrence after one year of follow-up. The operation is done as an outpatient procedure under general or local anesthesia. Suction is carried out through a 1-cm incision in the anterior axillary fold and the entire surface of the dermis is fully "vacuumed" in all directions with 15 to 20 strokes, using a 5- or 7-mm diameter cannula. The area treated includes the area of maximal axillary hair growth and 5 to 6 cm beyond. Routine dressings are removed five days posteroperatively, with the patient generally resuming all activities within one week.

Adipose Tissue↗
PubMed1987

Use of human amnion for microvascular interpositional grafts.

A major problem associated with vascular grafting employing an artificial graft is the inflammatory response provoked by the graft and subsequent complications of classical acute rejection phenomena when the graft is implanted subcutaneously into human volunteers. The favorable results obtained by a preliminary study of subcutaneous implantation of amnion in our laboratory have led us to a prospective study to determine its value as a vascular graft. Tubed conduits of glutaraldehyde-treated amnion were hand constructed of varying diameters and lengths. They were employed as segmental interpositional grafts in experimentally created femoral and aortic arterial defects in Sprague-Dawley rats. Patency rates varied from 60 to 90 percent, with all grafts showing remarkable reendothelialization within 3 to 4 weeks postoperatively. Morphology, antigenic reaction, blood flow, and patency of the different experimental amnion grafts were evaluated and compared to appropriate controls.

Amnion↗
PubMed1987

Salvage of amputation stumps by secondary reconstruction utilizing microsurgical free-tissue transfer.

During a 2-year period, 15 lower and upper extremity amputees were treated by microsurgical free-tissue transfer in an effort to salvage their amputation stumps. Salvage of length and restoration of contour to aid in prosthetic rehabilitation were the two main indications for reconstruction. Included in the 15 transfers were 3 scapular free flaps, 11 latissimus dorsi musculocutaneous flaps, and 1 groin flap. Thirteen of the patients in this group were refitted with prostheses following reconstruction and did well with no pain or skin breakdown of the resurfaced stumps. The follow-up period on these patients averaged 16 months. One patient, in whom the flap succeeded, underwent stump soft-tissue revision and myodesis. One patient, in whom the flap failed, continued to develop recurrent ulceration in his stump. This clinical experience followed an extensive laboratory study of 12 above-knee amputation patients using noninvasive Doppler ultrasound measurements to determine weight-loading and interface-pressure distribution between the stump and the socket of the prostheses and their relation to stump length and circumference.

Adolescent↗
PubMed1987

Surgical treatment of acne scars.

Dermatologists and their plastic surgical colleagues treating acne vulgaris and its sequelae have an effective arsenal of anti-acne preparations to inhibit and avoid many of the long-term, cosmetically deforming effects of severe inflammatory acne. It is incumbent upon the physician participating in the care of the early and late sequelae of acne vulgaris to provide timely surgical therapy for those lesions requiring surgical drainage, extraction, or scar revision, while maintaining appropriate medical therapy for those areas of the skin still at risk to develop active disease.

Acne Vulgaris↗