Search PubMed⌕ Search

Biomedical subjects

B Toursarkissian

Publications and source records attributed to B Toursarkissian.

30 records · Page 2Linked to original sources
PubMed1994

Characterization of polyamine transport in rat aortic smooth muscle cells.

Increased arterial wall polyamine content has been linked to intimal hyperplasia (IH) formation. Intracellular polyamine content may be regulated by a polyamine transmembrane transport mechanism, but the existence of such a system has not been demonstrated in systemic arterial smooth muscle cells. This study characterizes polyamine transport as found in rat aortic smooth muscle cells. Smooth muscle cells were isolated and cultured from Sprague-Dawley rat aortas. Polyamine transport was determined by adding [14C]-polyamines to the medium, calculating transport kinetic parameters, Vmax and Km. Competition studies with unlabeled polyamines and uptake in the presence of paraquat, a polyamine transport inhibitor, were done to test the specificity of the uptake system. We identified polyamine transporters in aortic smooth muscle cells which were temperature, concentration, and time dependent. Kinetic studies revealed that spermidine and spermine had greater affinity for the transporter(s) than putrescine (Km = 0.3, 0.3, and 3.7 microM respectively; P = 0.0001) while maximum uptake velocity was similar for all polyamines (26.6-31.0 pmole/mg protein/min). Inhibition of de novo polyamine synthesis upregulated polyamine transport 2.8-3.8 times (P = 0.0001) while transporter affinity (as reflected by Km) remained unchanged. Competition studies and paraquat treatment indicated the presence of two polyamine transporters: one shared by all polyamines, the other specific for spermine and spermidine. These data indicate that transmembrane polyamine transport occurs in arterial smooth muscle cells. Upregulation of this system may represent one control mechanism for IH development.

Animals↗
PubMed1994

Percutaneous dilational tracheostomy: report of 141 cases.

Tracheostomy is indicated frequently in the treatment of critically ill patients who require prolonged mechanical ventilation. The purpose of this prospective study was to evaluate our initial experience with 141 cases of percutaneous dilational tracheostomy (PDT) performed over a 2-year period. One hundred twenty PDTs (85%) were placed at the bedside, and 21 (15%) were performed in the operating room in conjunction with other procedures. The procedural complication rate was 11% (16 of 141). Most complications were easily recognized and did not preclude the completion of PDT. One death occurred secondary to severe bronchospasm. The postoperative complication rate was 8% (11 of 141). The most frequent complication was peristomal oozing. The average duration of follow-up after decannulation for patients discharged alive and decannulated was 36 +/- 27 weeks. There were 3 recognized cases of clinically symptomatic tracheal stenosis. We conclude that PDT is comparable with the open method and can be performed rapidly and safely at the patient's bedside.

Adolescent↗
PubMed1994

Percutaneous dilational tracheostomy in children and teenagers.

Percutaneous dilational tracheostomy (PDT) is a new technique that has been successfully performed in adult patients who required long-term mechanical ventilation, but it has not been used in children. The authors report their initial experience with PDT in 11 children and teenagers. The procedure is as follows. Using Seldinger's technique, the trachea is cannulated with a guide-wire. It is then progressively dilated, to an appropriately sized tract, with dilators from a commercially available kit. Then, a tracheostomy tube can be inserted into the trachea, loaded over a dilator. Eleven children, aged 10 to 20 years, underwent PDT in an average of 20 minutes. In eight cases, PDT was performed at the bedside. One intraoperative and one postoperative complication developed in the same patient; both complications were easily recognized and treated. Tracheal stenosis has not developed in eight decannulated patients at an average of 43 +/- 30 weeks after decannulation. PDT appears to be a safe, potentially cost-effective alternative to open tracheostomy in young patients.

Adolescent↗
PubMed1994

Mirizzi's syndrome.

Mirizzi's syndrome is a partial obstruction of the biliary tree caused by a stone impacted in the cystic duct, with or without development of a cholecysto-biliary fistula. We report our experience with five cases and review current methods of diagnosis and management. Preoperative diagnosis greatly facilitates management. Diagnosis may require a combination of ultrasonography, computed tomography, and cholangiography (percutaneous or endoscopic retrograde). At surgery, dissection in the triangle of Calot should be minimized to avoid injury to the common bile duct. Often, a partial cholecystectomy is the only safe option. Defects in the common bile duct can be repaired by a variety of methods. The morbidity and mortality associated with this rare syndrome can be relatively high. A number of patients may have late biliary strictures.

Abdomen↗
PubMed1993

Traumatic ventral abdominal hernia associated with small bowel gangrene: case report.

A rare case is presented of traumatic subcutaneous rupture of the rectus abdominis with ventral herniation and decollement of the jejunum and transverse colon. Irreversible ischemia of the small bowel had occurred following a large mesenteric avulsion. Computed tomographic scanning detected the parietal defect and identified the herniating viscera.

Abdominal Muscles↗
PubMed1993

Coexisting hyperthyroidism and primary hyperparathyroidism.

The simultaneous occurrence of hyperthyroidism and primary hyperparathyroidism is rare in the absence of previous neck irradiation. We report two cases from our institution. Hypercalcemia secondary to hyperthyroidism is common and may obfuscate the diagnosis of concomitant primary hyperparathyroidism. Therefore the continued presence of hypercalcemia in a patient with successfully treated hyperthyroidism should lead the physician to search for primary hyperparathyroidism. Treatment of these concomitant disease processes consists of combined thyroidectomy and parathyroidectomy.

Adult↗
PubMed1990

Mediastinal epithelioid hemangioendothelioma.

An epithelioid hemangioendothelioma arising from the innominate vein in the anterior superior mediastinum of a 62-year-old man was treated by wide local excision followed by radiotherapy. This clinicopathologic entity is a rare cause of mediastinal mass and is characterized by an intermediate malignant potential. To our knowledge, very few cases have been reported in the mediastinum; those cases are listed in this report. Gross and microscopic distinguishing features of epithelioid hemangioendothelioma, as well as differential diagnosis, are reviewed from the literature. Finally, clinical behavior is discussed and treatment options are suggested.

Brachiocephalic Veins↗
PubMedDate not supplied

Efficacy of infrainguinal bypass for limb salvage in young diabetic patients.

The efficacy of infrainguinal bypass for limb salvage in young diabetic patients has not been well established. The purpose of this study is to determine the intermediate-term results (patency and limb salvage) of infrainguinal revascularization carried out for limb salvage (rest pain or ulceration) in young (<50 years old) diabetic atherosclerotic patients. Thirty-nine bypasses in 31 patients with a mean age of 44 years were retrospectively reviewed. There were no perioperative deaths. Minor or major complications occurred in 23% of cases. By life table analysis, the 18-month primary patency rate was 60+/-11%, assisted primary patency rate was 78+/-9%, and limb salvage rate was 71+/-9%. Most major amputations (five of nine) were required in patients with functional bypasses, either because of persistent infection or failure of wound healing. The presence of severe stenoses (>70%) in all three major named foot vessels (dorsalis pedis, medial and lateral plantar arteries) was associated with a high likelihood of limb loss despite a patent bypass (p<0.05). We could not identify any other factors statistically predictive of thrombosis, amputation, or the need for graft revision. Infrainguinal revascularization in this patient population can be carried out with acceptable limb salvage rates. However, patients should be made aware of the high incidence of amputation regardless of the success of the revascularization procedure, particularly in the presence of severe occlusive disease within the foot.

Adult↗
PubMedDate not supplied

Autologous superficial femoral vein for the repair of suprarenal mycotic aneurysms: a preferred conduit?--a case report.

The authors report a patient who presented with a ruptured mycotic aneurysm that destroyed the posterior segment of the suprarenal perimesenteric aorta. Initial in-line repair with a rifampin-soaked Dacron prosthetic patch failed 14 days postoperatively with recurrent hemorrhage. At reoperation, the aorta was repaired with a superficial femoral/popliteal vein interposition graft; a segment of superficial femoral/popliteal vein was also used in-line to revascularize the superior mesenteric and celiac arteries. The patient survived with no evidence of recurrence at 8 months postoperatively.

Adult↗
PubMedDate not supplied

Changing patterns of access site complications with the use of percutaneous closure devices.

The authors report their experience with 15 cases of groin complications associated with the use of percutaneous closure devices following femoral arterial catheterization over a 2-year period. The complication rate was 1.7% for catheterizations in which a closure device was used. The 15 cases included 7 uncomplicated pseudoaneurysms (PSA), 3 infected pseudoaneurysms, 4 nonarterial groin infections (infected hematomas and/or abscesses), and 1 case of femoral artery occlusion. These complications presented at an average of 5 +/- 4 days postcatheterization. One patient with an infected PSA required a below-the-knee amputation. During the same time interval, there were no infectious complications in patients not receiving closure devices. We conclude that groin complications associated with such devices tend to present late and include a higher percentage of infections as opposed to complications occurring in patients not receiving closure devices. An aggressive surgical approach to these problems appears warranted.

Aneurysm, False↗
PubMedDate not supplied

Lower extremity bypass graft revision in diabetics.

Revision of lower extremity bypass graft stenoses identified by surveillance duplex scanning is frequently required in diabetic patients. The authors evaluated (1) the value of routine angiography before graft revision in diabetics, (2) factors that predict patients in whom angiography alters management, and (3) the incidence of recurrent stenosis and factors that might predict it. Forty-two infrainguinal primary vein bypasses undergoing primary revision were retrospectively studied. The initial graft stenosis was detected at a mean of 11.5 +/-3.6 months after the original bypass. Angiograms were obtained in 38 cases, revealing additional findings in 29 of 38 cases (76%), with a resultant alteration of the operative plan in 27 cases (71%). The most frequent additional angiographic finding was the identification or localization of a lesion in the inflow or outflow tracts (18 of 27 cases). Cases where the angiogram altered the management plan had a mean systolic velocity ratio across the stenosis (Vr) of 7.3 +/-6.1, versus a Vr of 4.8 +/-1.3 for cases where the angiogram did not alter the management plan (p<0.04). Duplex scanning identified 4 lesions that were not seen on angiography; 3 of 4 were confirmed as webs at surgery. Twenty of 42 grafts (48%) developed recurrent stenoses at a mean of 4.9 +/-3.8 months from initial revision. Restenosis occurred in 69% of female limbs as compared to 38% of male limbs (p=0.06). Recurrent stenosis was not a predictor of ultimate graft failure, unless left untreated. Four of 10 untreated grafts ultimately failed. A total of 9 of the 42 grafts eventually failed (21%), leading to 3 amputations (7%). The authors conclude that failing infrainguinal bypass grafts identified by duplex in diabetics should undergo a detailed angiographic evaluation. This frequently leads to an alteration in the management plan, especially in the presence of a high Vr across stenoses. High rates of limb salvage (93%) and assisted primary graft patency (79%) despite a high recurrent stenoses rate (48%) justify routine duplex surveillance, preoperative angiography, and aggressive graft revision in diabetic patients with infrainguinal grafts.

Aged↗