Sreedhar Kallakuri

Glycine prevents the induction of apoptosis attributed to mesenteric ischemia/reperfusion injury in a rat model.

PURPOSE We have previously demonstrated that glycine has a protective effect in mesenteric ischemia/reperfusion (I/R) injury. The purpose of this study was to elucidate the molecular mechanisms of the cytoprotective action of glycine. Because oxidative stress in I/R injury can lead to apoptosis, we examined the role of glycine in modulating the apoptotic signals in a rat mesenteric I/R injury model. METHODS Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals (n=6) received normal saline intravenously at the rate of 0.01 mL/g/h during the ischemia and reperfusion period. Treated animals divided in 3 groups (n=6 in each) received glycine at a dose of either 0.5, 0.75, or 1.0 mg/g, infused at the rate of 0.01 mL/g/h during the reperfusion period. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were harvested for histopathology, TUNEL assay, and immunohistochemistry. Expression of apoptosis-related molecules, bcl-2, bax, caspase-3, death receptor, Fas, and death substrate, poly (ADP-ribose) polymerase (PARP) were studied. RESULTS In glycine-treated animals, the middle and distal segments of the small intestine were well- preserved and showed better histologic grade and morphometric parameters as compared with saline controls (P<.05) in a dose-independent manner. There was increased apoptosis in saline controls as compared to the treated group (P<.01). Pro-apoptotic bax and caspase-3 were downregulated, whereas bcl-2 was upregulated in the glycine-treated animals (P<.02). Increased expression of death receptors and cleavage of PARP was observed in saline controls as compared to treated groups (P<.05). No significant differences were noted between the proximal bowel segments of treated and control animals. CONCLUSIONS These data support the concept that I/R causes formation of death- inducing signal complexes, which may activate the sequential cleavage of caspases and death substrates. We have demonstrated that one of the mechanisms of the protective effect of glycine is the downregulation of the death-inducing signals and abrogation of the apoptotic cascade in this I/R injury model.

Combined coronary artery bypass grafting and abdominal aortic aneurysm repair

BACKGROUND We report here the results of combined coronary artery bypass grafting (CABG) and abdominal aortic aneurysm (AAA) repair and the factors associated with higher mortality following this procedure. METHODS The authors performed a retrospective chart review of 26 patients who underwent combined CABG and AAA repair between March 1990 and October 1996. RESULTS No postoperative myocardial infarction or major cardiac complications were noted. A morbidity rate of 38% (n = 10) and mortality rate of 11% (n = 3) were noted. Comparative analysis of nonsurvivors (n = 3) versus survivors (n = 23) revealed the following: ejection fraction (EF) was significantly lower (33% +/- 3% versus 44% +/- 14%, P < 0.05), duration of cardiopulmonary bypass (CPB) was significantly longer (239 +/- 122 minutes versus 141 +/- 54 minutes, P < 0.05), and incidence of postoperative respiratory failure (67% versus 17%, P = 0.001) were significantly higher in nonsurvivors. No differences in mean age, gender distribution, incidence of hypertension or diabetes were noted between the groups. CONCLUSIONS Combined CABG and AAA repair protected patients from postoperative aneurysm rupture and myocardial infarction. Poor EF, prolonged CPB, and postoperative respiratory failure were associated with higher mortality.

P53 gene transfer to the injured rat carotid artery promotes apoptosis

BACKGROUND In a previous study we have demonstrated significant reduction of intimal hyperplasia after adenovirus-mediated gene transfer of p53 protein to the injured rat carotid artery. The purpose of this study was to elucidate whether apoptosis is one of the mechanisms responsible for this reduction. Apoptosis, a physiologic cell death process that stabilizes cell numbers in tissues, can be independently induced by p53. METHODS In vivo gene transfer was used in isolated segments of balloon-injured rat carotid arteries. Genetically modified adenovirus encoding for wild-type p53 protein (AdWTp53) was applied at 8 x 10(10) plaque-forming units/mL. Control rats received either adenovirus null at the same concentration or balloon injury alone. Arteries were harvested at 24 and 48 hours after the procedure. Apoptosis was detected in tissue sections by in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Specimens were graded either negative or positive less than 10%, 10% to 20%, 20% to 30%, or greater than 30% according to the number of apoptotic cells in the medial or intimal layer per high power field. Specimens were also subjected to DNA agarose gel electrophoresis and transmission electron microscopy. RESULTS With the TUNEL assay no apoptosis was visualized at 24 and 48 hours in the controls (n = 5 in each group), whereas in the AdWTp53 groups (n = 5 in each) all specimens presented apoptosis (P < .05, AdWTp53 vs controls). The average grade of apoptotic cells detected in the medial layer in the AdWTp53 groups was less than 10% to 20% at 24 hours and 20% to 30% at 48 hours. The DNA agarose gel electrophoresis failed to detect a DNA laddering pattern, characteristic of apoptosis. Electron microscopy revealed morphologic changes typical of apoptosis in the treated group, whereas specimens from control group did not reveal any apoptotic features. CONCLUSIONS At 48 hours after balloon injury alone, no apoptosis was observed in the vessel wall. However, when p53 gene was transferred, apoptosis was visualized in all specimens with greater intensity at 48 hours after injury. Promotion of apoptosis may play a key role in the mechanism by which p53 gene decreases intimal hyperplasia.

Protective effect of glycine in mesenteric ischemia and reperfusion injury in a rat model

PURPOSE Glycine has a protective effect in renal and skeletal muscle ischemia. The purpose of this study was to evaluate the effect of glycine in mesenteric ischemia and reperfusion injury in a rat model. METHODS Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals received normal saline solution intravenously at 0.01 mL/g of body weight/h during ischemia and reperfusion. Treated animals received glycine at 0.5, 0.75, or 1.0 mg/g of body weight, dissolved in saline solution and infused at 0.01 mL/g/h for 2 hours. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were isolated. Sections of the segments stained with hematoxylin-eosin were subjected to histologic examination (as per modified Chiu grading system) and morphometric analysis consisting of measurement of bowel wall, muscularis and mucosal thickness, epithelial coverage, and villar circumference. Isometric tension responses to electrical stimulation (10, 30, 50, 100 Hz), high doses of potassium (120 mmol/L), and carbachol (0.1, 0.5, 1.0, 5.0 micromol/L) were recorded in a multimuscle chamber. Statistical analysis was performed with unpaired t test and one-way analysis of variance. RESULTS The middle and distal segments of the small bowel in glycine-treated animals showed better histologic grade compared with saline solution-treated control rats (P <.05). At morphometric analysis, total thickness, mucosal thickness, and villar circumference ratio were well preserved in the middle and distal segments of the small bowel in the glycine-treated group (P <.05). No significant differences were observed in the proximal bowel segments between glycine-treated and control animals, because the proximal segment was not subjected to much ischemia. No differences were noted in percentage of epithelial coverage. Isometric tension responses evoked by electrical stimulation were greater (P <.05) in the middle and distal segments treated with glycine as compared with control segments. Carbachol-evoked contractions were stronger (P <.05) in the small bowel segments of animals treated with glycine. The responses evoked by 120 mmol/L of potassium were stronger in the distal segments of the small bowel in the glycine-treated group (P <.05). This cytoprotective effect of glycine was not dose-dependent. CONCLUSIONS Glycine improved mucosal viability in the ischemia and reperfusion injury rat model. Mucosal thickness and villous circumference ratio were reliable objective parameters for evaluation of intestinal ischemia injury. Glycine improved the contractile responses of the bowel segments also, probably by altering the physiologic mechanisms underlying force generation. Further studies are required to elucidate the mechanism of the cytoprotective action of glycine.

Early transposition of the sartorius muscle for exposed patent infrainguinal bypass grafts.

The traditional approach for patent and exposed and infected infrainguinal bypass grafts in the groin has included wide operative debridement and secondary or delayed primary closure. However, this has been associated with significant risk of further contamination and length of stay. The authors reviewed their experience using the wide debridement, sartorius muscle flap transposition, and primary wound closure as an alternative. During the past 5 years, they have had 50 patients with major wound necrosis or infection in the groin or thigh with the graft or native artery being exposed after debridement. This group included 28 men; 74% of the patients had hypertension, 58% had diabetes, and 20% had renal failure. The grafts were split evenly between native vein and prosthetic material. After wide debridement, closure was performed by the vascular surgeon using the sartorius muscle flap. Postoperatively, there was an 8% major amputation rate and a 12% mortality rate in the first 30 days. One patient developed a pseudoaneurysm 5 weeks after placement of the flap. This patient underwent removal of the infected polytetrafluoroethylene graft with ligation of the common femoral artery. None of the procedures have resulted in further systemic or graft sepsis. None have resulted in arterial or graft blowout. Follow-up was for an average of 18 months. Closure of groin and thigh wounds with exposed bypass graft or native artery can be safely performed with the sartorius muscle flap with excellent results. The length of stay of these patients compared to historical controls is acceptable. Furthermore, the chance of infection of the native artery or bypass may be reduced. Familiarity with this simple technique can be a valuable tool for the vascular surgeon.

Carotid Endarterectomy in Octogenarians and Nonagenarians : Is it Worth the Effort ?

Abstract Purpose: The safety, effectiveness and cost issues of carotid endarterectomy (CEA) in the elderly patient have been debated due to the limited life expectancy and presumably increased rate of complications. This is despite multiple reports in the literature of excellent results in this population. To further examine this issue, we compared characteristics of three populations who underwent CEA at our institution: 53–79 year old patients (youngest group), 80–89 years old patients (middle group), and 90–98 year old patients (oldest group). Methods: Medical and financial data were obtained by retrospective review of hospital charts and billing records. We analyzed 266 random CEAs performed in 251 patients in the youngest group, 280 CEAs performed in 247 patients in the middle group and 19 CEA in 16 patients in the oldest group performed between 2/1/90 and 2/5/01. Results: Comparing each CEA group, there were no differences in gender (males: 56% vs. 51% vs. 53%), incidence of preoperative symptoms (43% vs. 43% vs. 42%), hypertension (68% vs. 60% vs. 42%), combined perioperative death and stroke rate (1.8% vs. 2.1% vs. 10%) or other complications (11% vs. 10% vs. 10%). Significant differences (p<0.05) were noted between the groups in incidence of diabetes (33% vs. 51% vs. 5% in each group), and heart disease (28% vs. 38% vs. 21%). Length of stay for admissions for CEA only were also similar in all three groups (2.37 days vs. 2.67 days vs. 2.36 days). A cost analysis of the earliest 230 patients in the entire series examining hospital cost per case revealed similar data for the <80 years old and > 80 year old patients (

Endovascular management of axillofemoral bypass graft stump syndrome

7,842 vs.

Prospective evaluation of combined upper and lower extremity DVT.

9,400). Conclusions: Carotid endarterectomy can be performed in the elderly as safely and cost effectively as in the younger population.

Impact of duplex arteriography in the evaluation of acute lower limb ischemia from thrombosed popliteal aneurysms

OBJECTIVE Upper extremity embolic complications of occluded axillofemoral bypass grafts are infrequent. However, traditional management of dissection of axillary anastomosis for removal of the stump can be challenging. We report two patients with critical upper extremity ischemia secondary to stump syndrome and its successful management with endovascular techniques. METHODS One hundred fifty-two patients underwent axillofemoral bypass grafting over 10 years from 1991-2001. Two patients from this series had acute ischemia involving the ipsilateral upper extremity of occluded axillofemoral bypass graft. Duplex ultrasound scans revealed occlusion of the axillofemoral bypass graft and acute occlusion of ipsilateral upper extremity arteries. Both patients underwent brachial artery exploration and embolectomy. Completion angiograms revealed persistent axillofemoral bypass graft stump as the source of embolus. The stump was obliterated with a 10-mm/40-mm Wallgraft introduced through the same arteriotomy made for brachial embolectomy. Transesophageal echocardiography and magnetic resonance angiography of the arch and great vessels were performed to exclude other sources of origin for the embolus. RESULTS Both patients remained symptom-free and with patent stent grafts, as seen on duplex scans at 3, 6, and 9 months of follow-up. CONCLUSIONS Upper extremity embolism is a rare complication after occlusion of axillofemoral bypass grafts. The endovascular approach to obliterate the stump of occluded axillofemoral bypass grafts is minimally invasive and an effective alternative treatment of this rare condition.

Hemodynamics of infrapopliteal PTFE bypasses and adjunctive arteriovenous fistulas

The clinical importance of upper extremity deep venous thrombosis (UEDVT) has been increasingly demonstrated in recent literature. Not only has the risk of pulmonary embolism from isolated upper extremity DVT been demonstrated, but a significant associated mortality has been encountered. Examination of this group of patients has demonstrated the existence of combined upper and lower extremity deep venous thrombosis (DVT) in some patients who exhibit an even higher associated mortality. As a result of this information, it has become the standard practice at this institution to search for lower extremity DVTs in patients found to have acute thrombosis of upper extremity veins. Since January 1999, there have been a total of 227 patients diagnosed with acute UEDVT. Within this group, 211 (93%) patients had lower extremity studies; 45 of these 211 (21%) had acute lower extremity DVTs by duplex examination in addition to the upper extremity DVTs. Overall, there were 145 women, 66 men, and the average age was 70 ±1.2 (SEM); 22 of these patients had bilateral lower extremity thrombosis (LEDVT), and 8 patients were found to have chronic thrombosis of lower extremity veins. Of the patients with bilateral upper extremity DVTs, there were 3 with bilateral LE acute DVTs. Finally, 8 of the remaining 166 patients (5%) with originally negative lower extremity studies were found to develop a thrombosis at a later date. These data serve to confirm previous studies, on a larger scale, that there should be a high index of suspicion in patients with UEDVT of a coexistent LEDVT.