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A Gurlek

Publications and source records attributed to A Gurlek.

13 recordsLinked to original sources
PubMed2001

Effects of some pharmacological agents on the survival of unipedicled venous flaps: an experimental study.

Clinical and experimental studies have been conducted to improve the survival of venous flaps. As a result of these studies, although various survival mechanisms were raised, none obtained satisfactory information. Venous stasis, and the resultant venous thrombosis, is a factor that decreases the survival of venous flaps. In this study, we evaluated the effects of two antiinflammatory agents, etodolac and etofenamate, on the survival of unipedicled venous flaps. In this study, 35 male New Zealand white rabbits (3,500-4,000 g) (70 ears) were used. Perichondrocutaneous flaps, 3 x 4.5 cm in size, were designed and raised, keeping the central veins intact in the middle of venous flap. Central arteries and nerves were ligated and transected both proximally and distally, to prepare unipedicled venous flaps. A silicone sheet was placed between the cartilage tissue and flap, to prevent blood flow and revascularization beneath. The subjects were divided into seven groups, consisting of five rabbits (10 ears). In the negative control group (group I), the single vascular pedicle of venous flaps, central veins were ligated and flaps sutured into their own place as the composite graft. In the positive control group (group II), after venous flaps were prepared, normal saline, 0.2 mL, was given subcutaneously. In the first of five experimental groups (group III), unfractionated heparin (100 U/day) was given subcutaneously. In the second experimental group (group IV), etodolac (5 mg/kg/day) was given subcutaneously. In the third experimental group (group V), etophenamate (5 mg/kg/day) was given orally through a feeding tube. In the fourth experimental group (group VI), parnaparin (5 anti-Xa U/kg/day) was given subcutaneously. In the fifth experimental group (group VII), nadroparin (5 anti-Xa U/kg/day) was given subcutaneously, about 7 days postoperatively. At the eighth postoperative day, surviving areas of venous flaps were measured, and the results were evaluated by Kruskal-Wallis ANOVA and Mann-Whitney U-test (P < 0.05). Biopsies were also taken from the flaps for histological evaluation of border of necrotic tissue. Surviving areas of unipedicled venous flaps were larger in experimental groups than those in negative and positive control group (P < 0.05). However, comparison of the experimental groups demonstrated no statistically significant difference (P > 0.05). We concluded that all pharmacological agents used in the experimental groups succeeded in increasing the survival of unipedicled venous flaps. Survival of the unipedicled venous flap was higher in venous flaps than that of composite graft, clearly showing the importance of the venous pedicle.

Animals↗
PubMed2001

Indications for immediate tissue transfer for soft tissue reconstruction in visceral pelvic surgery.

BACKGROUND: Perineal wound complications may occur after visceral pelvic surgery. We reviewed our experience to determine indications for immediate tissue transfer (TT) to prevent complications. METHODS: Hospital records and computerized data were reviewed on 175 perineal repairs in 156 patients treated at The University of Texas M.D. Anderson Cancer Center for tumors involving the alimentary tract (135 of 175), genitourinary tract (15 of 175), perineum (19 of 175), or sacrum (6 of 175). Patients had either resection of only the colorectum and anus (APR) (46 of 175) or multivisceral resection (MVR) (129 of 175), and the perineal wound was closed by using TT (108 of 175) or primary closure (PC) (67 of 175) on the basis of the surgeon's judgment. Complications were compared between PC and TT groups. RESULTS: Complications occurred in 57% (100 of 175). There was no significant difference overall in PC and TT procedures or in the APR subgroup. There were significantly fewer complications for TT patients in the MVR subgroup (P =.0001). There were significantly fewer complications for TT patients with prior irradiation in both APR (P =.01) and MVR (P =.007) subgroups. CONCLUSIONS: Immediate TT for perineal wound closure is associated with fewer healing complications than PC in a subset of patients with multivisceral resection or prior radiotherapy. Surgical planning in these cases should consider immediate soft tissue reconstruction.

Adult↗
PubMed2001

Double auricle?

Explore the source record for details and available documents.

Ear, External↗
PubMed2001

Effect of losartan on circulating TNFalpha levels and left ventricular systolic performance in patients with heart failure.

BACKGROUND: Tumor necrosis factor alpha (TNFalpha) plays an important role in the pathophysiology of heart failure. Recent studies have shown a beneficial effect of losartan in these patients. However, the effect of losartan on TNFalpha levels in heart failure has not yet been studied. We evaluated the effect of losartan on circulating TNFalpha levels and ejection fraction (EF) in patients with congestive heart failure. METHODS: Forty patients with heart failure and EF < or = 40% were enrolled into the study. All of the patients have been given diuretic and digitalis therapy. Twenty patients were given losartan (50 mg/d) (Group I, 10 women, 10 men, 12 dilated cardiomyopathy, 8 ischemic heart disease, mean age 64.9 + 8.9), and another 20 patients were not given losartan because of hypotension or renal dysfunction (Group II, 13 men, 7 women, 10 dilated cardiomyopathy, 10 ischemic heart disease, mean age 61.2 +/- 10.5). EF was measured at the initial evaluation and on the fifteenth day of the therapy by echocardiographic examination using an acoustic quantification method. Circulating TNFalpha levels were also measured at the initial evaluation and on the fifteenth day of therapy by the ELISA method. RESULTS: Losartan significantly increased EF and decreased TNFalpha (EF increased from 29.4 +/- 7.3% to 36.0 +/- 8.5%, P < 0.001, and TNFalpha decreased from 39.2 +/- 37.4 pg/ml to 27.0 +/- 30.0 pg/ml, P < 0.05). Changes in TNFalpha levels and EF were not found to be correlated (r=-0.28, P=0.24). However, in the control group, EF and TNFalpha levels were similar at baseline and at the fifteenth day (EF 31.4 + 8.1% vs 31.7 +/- 7.8%, P=0.1, and TNFalpha 91.5 + 86.0 pg/ml vs 110.0 +/- 80.7 pg/ml, P=0.1, respectively). CONCLUSIONS: Losartan improves left ventricular systolic function and decreases TNFalpha level. The decreased TNFalpha level seems to be independent of EF.

Aged↗
PubMed2001

Regulation of osteoblast growth by interactions between transforming growth factor-beta and 1alpha,25-dihydroxyvitamin D3.

Osteoblast growth and differentiation encompass a series of events including proliferation, changes in cell shape, and expression of the markers specific for osteoblast phenotype. Both transforming growth factor-beta (TGF-beta) and 1alpha,25-dihydroxyvitamin D3 (1alpha,25[OH]2D3) are effective in regulating osteoblast proliferation, differentiation, bone matrix maturation and cell-specific gene expression. Although there is some degree of controversy regarding the influences on osteoblasts in vitro, it is generally agreed that TGF-beta stimulates osteoblast proliferation and growth, and inhibits the expression of the markers characteristic of the osteoblast phenotype such as osteocalcin. In contrast, 1alpha,25(OH)2D3 causes inhibition of the proliferation of osteoblasts, arrests their growth, and stimulates expression of specific markers. In many studies, complex interactions have been demonstrated between TGF-beta and 1alpha,25(OH)2D3 modulating their receptor expression, synthesis, and effects on osteoblast-specific gene expression. The cooperative actions of TGF-beta and 1alpha,25(OH)2D3 can be synergistic or antagonistic. It has recently been established that Smad proteins that transduce signals downstream the TGF-beta stimulation may mediate the crosstalk between TGF-beta and 1alpha,25(OH)2D3 signaling. Future studies should focus on the explanation of the molecular basis of these interactions and the in vivo consequences of the regulation of osteoblast growth and differentiation by TGF-beta and 1alpha,25(OH)2D3.

Animals↗
PubMed1998

Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration.

We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve, long bone, intestine, or blood vessel.

Biocompatible Materials↗
PubMed1997

Ectopic bone formation by marrow stromal osteoblast transplantation using poly(DL-lactic-co-glycolic acid) foams implanted into the rat mesentery.

Porous biodegradable poly(DL-lactic-co-glycolic acid) foams were seeded with rat marrow stromal cells and implanted into the rat mesentery to investigate in vivo bone formation at an ectopic site. Cells were seeded at a density of 6.83 x 10(5) cells/cm2 onto polymer foams having pore sizes ranging from either 150 to 300 to 710 microns and cultured for 7 days in vitro prior to implantation. The polymer/cell constructs were harvested after 1, 7, 28, or 49 days in vivo and processed for histology and gel permeation chromatography. Visual observation of hematoxylin and eosin-stained sections and von Kossa-stained sections revealed the formation of mineralized bonelike tissue in the constructs within 7 days postimplantation. Ingrowth of vascular tissue was also found adjacent to the islands of bone, supplying the necessary metabolic requirements to the newly formed tissue. Mineralization and bone tissue formation were investigated by histomorphometry. The average penetration depth of mineralized tissue in the construct ranged from 190 +/- 50 microns for foams with 500-710-microns pores to 370 +/- 160 microns for foams with 150-300-microns pores after 49 days in vivo. The mineralized bone volume per surface area and total bone volume per surface area had maximal values of 0.28 +/- 0.21 mm (500-710-microns pore size, day 28) and 0.038 +/- 0.024 mm (150-300-microns, day 28), respectively. As much as 11% of the foam volume penetrated by bone tissue was filled with mineralized tissue. No significant trends over time were observed for any of the measured values (penetration depth, bone volume/surface area, or percent mineralized bone volume). These results suggest the feasibility of bone formation by osteoblast transplantation in an orthotopic site where not only bone formation from transplanted cells but also ingrowth from adjacent bone may occur.

Animals↗
PubMed1997

Cell adhesion and short-term patency in human endothelium preseeded 1.5-mm polytetrafluoroethylene vascular grafts: an experimental study.

It has been shown that endothelialization improves short-term patency of 1.5-mm expanded polytetrafluoroethylene vascular grafts. A model for endothelialization of 1.5-mm expanded polytetrafluoroethylene vascular grafts with human endothelial cells is described. In this model, the adherence of endothelial cells was increased significantly in grafts coated with serum proteins and collagen. By means of this protocol, graft patency was tested after implantation in two animal models: the rat aorta and the rabbit common carotid artery. Anastomosis was performed with a 3M Precise Microvascular Anastomotic System. In both animal models, no significant loss of endothelial cells in the precoated grafts (rat, n = 8) were noted 1 hour after blood flow restoration. All uncoated grafts showed significant endothelial cell loss. In the rabbit model, all nonendothelialized grafts (n = 8) clotted 5 to 25 minutes after flow restoration. Seven (n = 8) endothelialized grafts showed no clotting during 1 hour's observation: one clotted immediately for a patency rate of 87.5 percent. These results indicate that endothelialization of 1.5-mm grafts is practical. Furthermore, adhesion of endothelial cells to the graft walls is not affected by short-term, pulsatile, high-pressure blood flow.

Animals↗
PubMed1997

Peripheral nerve regeneration: the effects of postoperative irradiation.

The purpose of this study was to evaluate the effects of postoperative external cobalt-60 beam irradiation on nerve regeneration. Sixty-five 250-gm male Sprague-Dawley rats were studied. Peripheral nerve regeneration was measured by walking track analysis and histomorphology of the proximal, graft, and distal nerve segments. These 65 animals underwent a 1.5-cm interpositional nerve graft into the right posterior tibial nerve. The left leg served as a control. Each animal was then randomly allocated into one of four groups. Group 1 served as control. Groups 2 through 4 were subjected to external cobalt-60 gamma-ray irradiation through a 2.5-cm circular portal for a total fractionated dose of 30, 50, and 70 Gy beginning on postoperative day 3. Radiation was administered in 2-Gy fractions, 5 fractions per week, with a top-up dose of 16 Gy given at the end of the fractionated irradiation. Walking track analysis was performed at 30, 60, 90, and 120 days after nerve grafting. At the conclusion of 120 days, sections of the proximal, grafted, and distal nerve were harvested, stained, and examined histomorphologically. Hematoxylin and eosin stains also were obtained. Evaluation of the print-length index demonstrated no statistical difference between the unirradiated controls and the irradiated groups. The total number of axons per square millimeter and nerve fiber density per square millimeter were significantly decreased in the distal segment of all the irradiated groups when compared with controls. Despite the reduction in myelinated regenerating fibers, no reduction in function was observed, as measured by walking track analysis. We would therefore recommend immediate reconstruction of peripheral nerve defects in the face of postoperative irradiation.

Animals↗
PubMed1996

Comparison of vascular effects of calcitonin gene-related peptide and lidocaine on human veins.

Arterial and venous constriction during microsurgery are among the leading causes of flap failure. So far, pharmacologic tools have been proposed only for arterial constriction, and local anesthetics are commonly used to counteract the vascular spasm. The purpose of this study was to investigate the vascular effects of two known arterial vasodilators on human veins, in order to evaluate the possibility of their potential use during microsurgery. In vitro experiments were performed on 31 greater saphenous vein (SV) rings obtained from 20 patients and on 12 cephalic vein (CV) rings from 7 patients. The rings were mounted in organ baths and their isometric contractile activity was measured. Experiments were conducted by cumulatively adding calcitonin gene-related peptide (CGRP) or lidocaine to the organ baths. The endothelium was mechanically removed in 18 SV rings and in 6 CV rings. Results demonstrated that in vitro CGRP produced vasodilation only; no constrictive effects were seen. Lidocaine produced a biphasic response with contraction at low concentrations (1.5 x 10(-5) M, 1.5 x 10(-3) M) and release of the maximal contraction at higher concentrations, similar to that observed in arteries. Removal of the endothelium did not significantly affect contractile activity in either CGRP- or lidocaine-treated vessels. The data supported the conclusion that CGRP could be used to relieve venous constriction, and it is suggested that further studies on the clinical use of CGRP in microsurgery is warranted.

Calcitonin Gene-Related Peptide↗
PubMed1996

Calcitonin gene-related peptide in experimental ischemia. Implication of an endogenous anti-ischemic effect.

Ischemia resulting from flap harvesting and vascular manipulation during microsurgery may be responsible for flap ischemic sufferance and, ultimately, necrosis. Recently, the regulatory role of the sensory nervous system in ischemia has attracted much interest. Calcitonin gene-related peptide (CGRP), a neuropeptide, is a naturally occurring vasodilator with no constrictive effects. In the present study, we developed a model of partial, chronic ischemia in the rat epigastric flap and investigated the effects of ischemia on concentrations of CGRP-like immunoreactivity (-LI) in ischemic skin and in different regions of the rat brain (striatum, hippocampus, pituitary, hypothalamus, and frontal and occipital cortex). A neurovascular island flap based on the superficial epigastric vessels was raised in 10 animals. Ischemia of the flap was obtained by ligating the feeding artery so that the blood flow was reduced to 25% of the normal circulation. An electromagnetic Doppler positioned on the artery was used to monitor the blood flow reduction. Ten nonoperated animals were used as controls. Ten days after the operation, CGRP-LI was significantly increased in five of six brain regions analyzed (striatum excepted). Significantly decreased concentrations of CGRP-LI were found in seven ischemic flaps, as opposed to the control group. In the remaining three flaps, no significant changes in CGRP concentration were observed. The highest blood flux values (detected using a laser Doppler) in the flaps correlated positively with the highest concentrations of CGRP-LI in the flap tissue. The results of the present study suggest that endogenous CGRP may be involved in the adaptive response to ischemia.

Animals↗