Linear epitope mapping of humoral responses induced by vaccination with recombinant HIV-1 envelope protein gp160

Ischemic preconditioning of the myocardium with repeated brief periods of ischemia and reperfusion prior to prolonged ischemia significantly reduces subsequent myocardial infarction. Following ischemic preconditioning, two "windows of opportunity" (early and late) exist, during which time prolonged ischemia can occur with reduced infarction size. The early window occurs at approximately 4 hours and the late window at 24 hours following ischemic preconditioning of the myocardium. We investigated if ischemic preconditioning of skeletal muscle prior to flap creation improved subsequent flap survival and perfusion immediately or 24 hours following ischemic preconditioning. Currently, no data exist on the utilization of ischemic preconditioning in this fashion. The animal model used was the latissimus dorsi muscle of adult male Sprague-Dawley rats. Animals were assigned to three groups, and the right or left latissimus dorsi muscle was chosen randomly in each animal. Group 1 (n = 12) was the control group, in which the entire latissimus dorsi muscle was elevated acutely without ischemic preconditioning. Group 2 (n = 8) investigated the effects of ischemic preconditioning in the early window. In this group, the latissimus dorsi muscle was elevated immediately following preconditioning. Group 3 (n = 8) investigated the effects of ischemic preconditioning in the late window, with elevation of the latissimus dorsi muscle 24 hours following ischemic preconditioning. The preconditioning regimen used in groups 2 and 3 was two 30-minute episodes of normothermic global ischemia with intervening 10-minute episodes of reperfusion. Latissimus dorsi muscle ischemia was created by occlusion of the thoracodorsal artery and vein and the intercostal perforators, after isolation of the muscle on these vessels. Muscle perfusion was assessed by a laser-Doppler perfusion imager. One week after flap elevation, muscle necrosis was quantified in all groups by means of computer-assisted digital planimetry. Our results show that ischemic preconditioning resulted in a significant reduction (p < 0.05) in muscle-flap necrosis immediately and 24 hours following ischemic preconditioning. Perfusion changes after flap elevation were similar among the three groups. Ischemic preconditioning of skeletal muscle prior to flap creation significantly reduces subsequent muscle-flap necrosis caused by the ischemia of flap creation immediately and 24 hours following ischemic preconditioning. Further elaboration of the mechanisms of ischemic preconditioning may allow pharmacologic preconditioning to be used in the augmentation of skeletal muscle-flap survival in the clinical setting.     

Use of ultrasonography to evaluate muscle thickness and blood flow in free flaps

The purpose of this study was to investigate the common belief that a microvascular transfer of a non-innervated free muscle flap loses muscle bulk over time. Sixteen patients (latissimus dorsi = 8, rectus abdominis = 7, and gracilis muscle = 1) were evaluated an average of 41 months after free flap transfer. Latissimus dorsi and lower extremity flaps displayed significantly more swelling than the other flaps. Flap bulk was measured by ultrasound. The mean thickness of upper extremity flaps was 10.3 +/- 1.8 mm (control muscles 11.8 +/- 2.8), lower-extremity 14.5 +/- 3.7 mm (control muscles 10.9 +/- 0.7), latissimus dorsi 14.3 +/- 2.2 mm (control muscles 10.3 +/- 0.8, P = 0.018), and rectus abdominis 11.2 +/- 1.2 mm (control muscles 12.4 +/- 1.9). Color Doppler ultrasonography was used to detect the pedicles of the free flaps and also to measure the peak velocity of blood flow intramuscularly and in the pedicles. In the upper extremities (n = 5) the pedicles could be found in only 20% of cases whereas in the lower extremities (n = 11) 91% of pedicles were located. (P = 0.013). Peak flow within the free flaps was significantly higher in the lower extremity (50% of the peak flow of the common femoral artery) than in the upper extremity (5% of the peak flow of the common femoral artery, P = 0.013). This study demonstrated that non-innervated free muscle flaps in the extremities maintain the original muscle thickness, although lower extremity and latissimus dorsi flaps have a trend to be thicker. Most pedicles of free muscle flaps in the upper extremities could not be located by ultrasound. However, flaps in the lower extremities most often have patent pedicles and also more vigorous intramuscular blood flow.     

Use of a nitric oxide precursor to protect pig myocutaneous flaps from ischemia-reperfusion injury

Nitric oxide is a radical with vasodilating properties that protects tissues from neutrophil-mediated ischemia-reperfusion injury in the heart and intestine. Previous studies in our laboratory suggested that L-arginine, a nitric oxide precursor, can protect skin flaps from ischemia-reperfusion injury. In this study, we examined the effects of L-arginine on the survival of myocutaneous flaps in a large animal model and established whether this effect was mediated by nitric oxide and neutrophils. Two superiorly based 15 x 7.5 cm epigastric myocutaneous island flaps were dissected in 15 Yorkshire pigs weighing 45 to 50 kg. One of the flaps was subjected to 6 hours of arterial ischemia and then reperfused for 4 hours (ischemia-reperfusion flaps), whereas the other flap was used as a non-ischemic control (non-ischemia-reperfusion flaps). The flaps were divided into four groups: control non-ischemia-reperfusion flaps that received only saline (group I); ischemia-reperfusion flaps that were treated with saline (group II); and flaps treated with either L-arginine (group III) or Nomega-nitro-L-arginine methylester (L-NAME), a nitric oxide synthase competitive inhibitor, plus L-arginine in equimolar amounts (group IV). These drugs were administered as an intravenous bolus 10 minutes before the onset of reperfusion, followed by a 1-hour continuous intravenous infusion. Full-thickness muscle biopsies were taken at baseline, 3 and 6 hours of ischemia, and 1 and 4 hours of reperfusion. The biopsies were evaluated by counting neutrophils and measuring myelo-peroxidase activity. At the end of the experiment, skeletal muscle necrosis was quantified using the nitroblue tetrazolium staining technique, and a full-thickness biopsy of each flap was used for determination of water content. Statistical analysis was performed using analysis of variance and the Newman-Keuls test. Non-ischemia-reperfusion flaps showed no muscle necrosis. Ischemia-reperfusion flaps treated with saline had 68.7 +/- 9.1 percent necrosis, which was reduced to 21.9 +/- 13.6 percent with L-arginine (p < 0.05). L-NAME administered concomitantly with L-arginine demonstrated a necrosis rate similar to that of saline-treated ischemia-reperfusion flaps (61.0 +/- 17.6 percent). Neutrophil counts and myeloperoxidase activity after 4 hours of reperfusion were significantly higher in ischemia-reperfusion flaps treated with L-NAME and L-arginine as compared with the other three groups (p < 0.05). Flap water content increased significantly in ischemia-reperfusion flaps treated with saline and L-NAME plus L-arginine versus non-ischemia-reperfusion flaps (p < 0.02) and L-arginine-treated ischemia-reperfusion flaps (p < 0.05). There was no difference in flap water content between ischemia-reperfusion flaps treated with L-arginine and non-ischemia-reperfusion flaps. Administration of L-arginine before and during the initial hour of reperfusion significantly reduced the extent of flap necrosis, neutrophil accumulation, and edema due to ischemia-reperfusion injury in a large animal model. This protective effect is completely negated by the use of the nitric oxide synthase blocker L-NAME. The mechanism of action seems to be related to nitric oxide-mediated suppression of ischemia-reperfusion injury through neutrophil activity inhibition.     

Effects of ischemia on cerebral arteriolar dilation to arterial hypoxia in piglets

BACKGROUND AND PURPOSE: Arterial hypoxia mediates cerebral arteriolar dilation primarily via mechanisms involving activation of ATP-sensitive K+ channels (K[ATP]), which we have shown to be sensitive to ischemic stress. In this study, we determined whether ischemia/reperfusion alters cerebral arteriolar responses to arterial hypoxia in anesthetized piglets. Since adenosine plays an important role in cerebrovascular responses to hypoxia, we also determined whether adenosine-induced arteriolar dilation is affected by ischemic stress. We tested the hypothesis that reductions in cerebral arteriolar dilator responses after ischemia would be proportional to the contribution of K(ATP) to hypoxia and adenosine. METHODS: Pial arteriolar diameters were measured using a cranial window and intravital microscopy. We examined arteriolar responses to arterial hypoxia (inhalation of 8.5% and 7.5% O2), to topical adenosine (10[-5] and 10[-4] mol/L) and to arterial hypercapnia (inhalation of 5% and 10% CO2 in air) before and after 10 minutes of global ischemia. Ischemia was achieved by increasing intracranial pressure. Arterial hypercapnia was used as a positive control for the effectiveness of the ischemic insult. In addition, we evaluated cerebral arteriolar responses to 10(-5) and 10(-4) mol/L adenosine applied topically with or without glibenclamide, a selective inhibitor of K(ATP) (10[-5] and 10[-6] mol/L). Finally, we administered theophylline (20 mg/kg, i.v.) to assess the contribution of adenosine to cerebral arteriolar dilation to arterial hypoxia. RESULTS: Before ischemia, cerebral arterioles dilated by 19+/-3% to moderate and 29+/-4% to severe hypoxia (n=7; P<.05); 13+/-2% to 10(-5) and 20+/-1% to 10(-4) mol/L adenosine (n=9; P<.05); and by 17+/-2% to moderate and 28+/-3% to severe hypercapnia (n=6; P<.05). After ischemia, cerebral arteriolar responses to hypoxia and adenosine were unchanged. In contrast, cerebral arteriolar dilation to hypercapnia was impaired by ischemia (1+/-1% and 2+/-1% at 1 hour; n=6). Glibenclamide reduced cerebral arteriolar dilation to adenosine by approximately one half (n= 7). In addition, blockade of adenosine receptors by theophylline (20 mg/kg, i.v.) almost totally suppressed cerebral arteriolar dilation to arterial hypoxia (n = 6). CONCLUSIONS: Cerebrovascular responsiveness is selectively affected by anoxic stress. In addition, cerebral arteriolar dilation to hypoxia and adenosine is maintained after ischemia despite the expected impairment in K(ATP) function.     

Quantification of early damage in latissimus dorsi muscle grafts

Acute damage in the latissimus dorsi muscle may account for variable clinical results following dynamic cardiomyoplasty and an ischemic cause has been suggested. Using established techniques, we set out to demonstrate and to quantify the acute muscle damage in a rodent model. The left latissimus dorsi muscle of 5 Sprague-Dawley rats was mobilized on its thoracodorsal vascular pedicle, thus interrupting the regional blood supply to its distal part. The undisturbed contralateral muscle served as a matched control. After 24 hours, the muscle was excised and divided into proximal, middle, and distal thirds. Damage was graded histologically and quantified by nitroblue tetrazolium macrohistochemistry. Both methods of assessment correlated well (r=-0.936; P < 0.001) and demonstrated significant damage, principally in the middle and the distal regions of the ischemic muscles. Therefore, the rodent model appears to be useful for investigating the pathogenesis and prevention of acute ischemic damage in the latissimus dorsi graft under conditions resembling the clinical scenario.     

Postoperative sensitivity of vascular pedicles latissimus dorso transplant without neural anastomosis

It is still a matter of controversy whether anastomosis of the sensory nerves is necessary in free transplants of microvascular reanastomosed myocutaneous latissimus dorsi flaps in the oral cavity and oropharynx. Some surgeons perform this routinely because they expect fewer complications in skin with a sensory nerve supply. We clinically examined 30 patients in order to assess the sensory innervation of the transplant tissue. All patients received free transplants of microvascular reanastomosed latissimus dorsi flaps during a tumor operation in the oral cavity. Sensation was determined clinically according to pain, temperature, pressure, two point discrimination and vibration. In most patients sensation in the Latissimus dorsi flap does not return. These findings suggest that reinnervation in the myocutaneous latissimus dorsi flap mostly does not occur, indicating that there is a need for anastomosis of a sensory nerve during transplant surgery with a myocutaneous latissimus dorsi flap to reinnervate it.     

Autologous latissimus breast reconstruction: a 3-year clinical experience with 100 patients

This article presents our technique of autologous breast reconstruction using the latissimus dorsi flap and studies the advantages, disadvantages, and results that can be expected. A consecutive sample of 100 patients was studied. The average length of follow-up was 20 months (range 8 to 44 months), and all of the subjects were reviewed in consultation without loss to follow-up. The supplementary volume of the latissimus dorsi was obtained from five fatty zones: fat on the cutaneous paddle, fat taken from the surface of the muscle, the scapular fat pad, the anterior fatty zone, and the supra-iliac fat pad. This technique must be measured against the transverse rectus abdominis muscle (TRAM) flap, free or pedicled, when the patient needs an autologous breast reconstruction. It can be used when the TRAM flap is contraindicated (this corresponds to 45 percent of patients of our sample) or when the dorsal donor site is preferred (55 percent of cases of our sample). The major complications are rare (1 percent partial necrosis and 1 percent total necrosis of the flap). The minor complications are represented mainly by the dorsal seroma. This is the main drawback of the technique, as it occurs in 79 percent of cases and regularly in obese patients. In view of this frequency, patients should be warned of its likely occurrence. The dorsal donor-site morbidity is relatively low; 4 percent of dorsal sequelae were classed as moderate, and 96 percent were considered low. The scapular sequelae have been classed as low in 97 percent of cases, and temporary scapular sequelae aggravation has been noted in 3 percent. Results of breast reconstruction using this technique are most encouraging. The level of patient satisfaction is high; 87 percent of them were deeply satisfied, 10 percent were satisfied, and only 3 percent were poorly satisfied. This group of poorly satisfied subjects (3 percent) consists of patients who suffered a serious postoperative complication. The aesthetic results have been judged excellent by surgeons in 85 percent of the cases, good in 12 percent of the cases, and poor in 3 percent of the cases; no result has been judged bad. This technique of breast reconstruction by autologous latissimus dorsi brings a major advance in breast reconstruction. The best indications of this technique are when one can bury the cutaneous paddle: cases of skin-sparing mastectomy, cases where the latissimus dorsi flap can be combined with an abdominal advancement flap, and cases of conversion of implant reconstruction to an autologous reconstruction.     

Preconditioning of human myocardium with adenosine during coronary angioplasty

BACKGROUND: It is unknown whether adenosine can precondition human myocardium against ischemia in vivo. METHODS AND RESULTS: Thirty patients were randomized to receive a 10-minute intracoronary infusion of adenosine (2 mg/min) or normal saline; 10 minutes later, they underwent percutaneous transluminal coronary angioplasty (PTCA; three 2-minute balloon inflations 5 minutes apart). In control patients, the ST-segment shift on the intracoronary ECG was significantly greater during the first inflation than during the second and third inflations, consistent with ischemic preconditioning. In contrast, in adenosine-treated patients, there were no differences in ST-segment shift during the three inflations. The ST-segment shift was significantly smaller in the adenosine-treated group compared with the control group during all three inflations. The reduction in ST-segment shift afforded by adenosine during the first inflation (-72% versus first inflation in control subjects) was greater than that afforded by ischemic preconditioning in control subjects (-52% during the third versus first inflation). Measurements of chest pain score paralleled those of ST-segment shift. Adenosine had no effect on baseline regional wall motion as determined by quantitative two-dimensional echocardiography. Thus, intracoronary infusion of adenosine before PTCA rendered the myocardium remarkably resistant to subsequent ischemia. Judging from the intracoronary ECG, the protection provided by adenosine was even superior to that provided in control subjects by the ischemia associated with the first two balloon inflations. Infusion of adenosine had no major adverse effects in patients undergoing PTCA of the left anterior descending or circumflex arteries. CONCLUSIONS: Adenosine preconditions human myocardium against ischemia in vivo. Pretreatment with adenosine is remarkably effective (even more effective than ischemic preconditioning) and could be used prophylactically to attenuate ischemia in selected patients undergoing PTCA of the left anterior descending coronary artery. Whether adenosine can be safely infused into the right or the circumflex coronary artery in the presence of a temporary pacemaker remains to be established.     

The inflammatory reaction in elective flap surgery

The inflammatory response in three different flap procedures was investigated by measuring the preoperative and postoperative levels of C-reactive protein, leukocyte count, and body temperature. Patients scheduled for delayed breast reconstruction were operated on with the lateral thoracodorsal flap, the latissimus dorsi flap, or the pedicled TRAM flap. All patients received 2 gm of intravenous cloxacillin for antibiotic prophylaxis and 1 gm of paracetamol four times a day as basic treatment for postoperative pain. Within each treatment group, significant postoperative changes in C-reactive protein levels, leukocyte count, and body temperature were noted when compared with preoperative values. The highest C-reactive protein level (130 mg/ml) was found in the TRAM group on the third postoperative day. The kinetic pattern of C-reactive protein was similar for the latissimus dorsi flap and lateral thoracodorsal flap procedures, but the maximum C-reactive protein levels were significantly lower, 74 and 44 mg/ml respectively. Small (0.5 to 0.9 degrees C) but significant differences in body temperature were also noted on the second and third postoperative day. The TRAM flap group had the highest, the latissimus dorsi flap group intermediate, and the lateral thoracodorsal flap group the lowest value. The postoperative C-reactive protein levels seem to reflect the extent of the surgical trauma.     

Time window for the contribution of the delta-opioid receptor to cardioprotection by ischemic preconditioning in the rat heart

The present study aimed to examine (1) whether the role of the opioid receptor in ischemic preconditioning (PC) is consistent regardless of the duration of ischemic insult and (2) which opioid receptor subtype contributes to PC. In the first series of experiments, the effects of PC, a nonselective opioid receptor antagonist (naloxone), and their combination on the infarct size after various durations of ischemia were assessed. In anesthetized, open-chest rats, the coronary artery was occluded for 20, 30, or 40 minutes to induce infarction and was reperfused for 3 hours, PC was performed with two cycles of 5-minute ischemia followed by 5-minute reperfusion before the sustained ischemia. At 25 minutes before the ischemia, naloxone was injected alone or in combination with subsequent PC. Infarct size was determined by tetrazolium staining and was expressed as a percentage of the risk area size (%IS/RA). In the second series of experiments, the effects of a delta-receptor-selective antagonist, naltrindole (NTI), and a kappa-receptor selective antagonist, nor-binaltrophimine (nor-BNI), on PC before 30-minute coronary occlusion were assessed. In untreated controls, %IS/RA was 53.1 +/- 3.2 after 20 minutes, 67.9 +/- 3.9 after 30 minutes, and 87.8 +/- 2.0 after 40 minutes of ischemia, respectively. PC significantly reduced %IS/RA after 20, 30, and 40 minutes of ischemia to 3.1 +/- 0.8, 12.8 +/- 1.1, and 42.1 +/- 4.3, respectively (P < 0.05 vs. each control). Naloxone (6 mg/kg) partially attenuated the protection afforded by PC when the sustained ischemia was 30 minutes (%IS/RA = 27.4 +/- 4.5; P < 0.05 vs. PC), but this inhibitory effect of naloxone was not detected when the duration of the ischemia was 20 or 40 minutes. NTI (10 mg/kg) also attenuated infarct size limitation by PC after 30 minutes of ischemia (%IS/RA = 25.6 +/- 3.7), but nor-BNI (10 mg/kg) failed to modify infarct size limitation by PC (%IS/RA = 13.3 +/- 3.2). The present results suggest that activation of the opioid delta-receptor partly contributes to preconditioning against infarction in the rat and that there may be a time window (at around 30 minutes after the onset of ischemia) for this opioid receptor-mediated protective mechanism.     

Modifications of the paraspinous muscle flap: anatomy and clinical application

Soft-tissue defects of the back, particularly involving the paravertebral tissues, are generally covered with myocutaneous, muscle, or fasciocutaneous flaps. The case of a 64-year-old man with a paravertebral malignant fibrous histiocytoma is reported. To ensure adequately radical margins, the ipsilateral trapezius and latissimus dorsi muscles as well as the costal periosteum and the spinous processes were resected between T9 and T12. The resulting defect was covered with a pedicled latissimus dorsi flap and an island flap of the paravertebral muscles. Prompted by this case, we studied the blood supply of the paravertebral muscles in 10 cadavers. The vasculature was visualized after flushing with colored latex and microsurgical dissection. Another 4 specimens were subjected to angiography and tomography. In the majority of cases (8 of 10), three perforators emerging from the intercostal arteries were identified. These were found to communicate in a longitudinal and vertical direction. Before piercing the fascia, they ramified in three layers matching the layers of the paravertebral muscles. Since the intercostal arteries were shown to communicate through anastomoses of adequate caliber, the paravertebral muscles appear to be useful candidates for proximally or distally pedicled transposition or island flaps.     

Port-site metastases. Impact of local tissue trauma and gas leakage

OBJECTIVE: To determine whether selective 5-lipoxygenase (5-LO) inhibition decreases expression of adhesion molecules (beta2 integrins) on systemic neutrophils, decreases neutrophil infiltration in ischemic flap tissue, and improves flap survival. DESIGN: A randomized, controlled study of 91 adult female Hartley guinea pigs divided into 3 survival groups, 4 neutrophil assay groups, 1 sham group, and 1 control group. Ischemia of varying duration and reperfusion was induced in island flank skin flaps. The treated groups received zileuton, a 5-LO inhibitor, orally during flap ischemia. After reperfusion, systemic neutrophil receptor expression, neutrophil infiltration, and flap survival were measured. Surface receptor molecules on neutrophils from whole blood samples obtained via transcardiac puncture were analyzed using monoclonal antibodies and cell-associated fluorescence. Neutrophil infiltration into a distal 1 cm2 of flap tissue was assessed using myeloperoxidase antibodies. Flap survival was determined within 7 days of surgery. RESULTS: Untreated flaps with 10 hours of ischemia underwent total necrosis. Treated 2- and 10-hour ischemic flaps survived intact. A significant main effect of the drug treatment was detected using analysis of variance (P<.001). Neutrophil receptor detection in the untreated groups undergoing 2 and 10 hours of ischemia was significantly increased compared with that in the treated groups with the same ischemia times. Skin neutrophil infiltration was significantly decreased in the treated groups. CONCLUSIONS: Systemic administration of a 5-LO inhibitor is effective in reducing ischemia-reperfusion injury in flap tissue. Our data indicate that there is a significant reduction in neutrophil receptor expression with administration of 5-LO, reducing the priming of systemic neutrophils from circulating cytokines.     

Secondary ischemic tolerance improved by administration of L-NAME in rat flaps

Nitric oxide (NO) under basal conditions is an important regulator of vascular tone. Under ischemic conditions, however, NO can combine with superoxide anion to produce the damaging hydroxyl free radical. The current project observes the effect of inhibiting NO production (L-Nitro-amino-methyl-arginine, L-NAME) on flaps rendered ischemic by secondary (2 degrees) venous obstruction. Eighty rats had 3 x 6 cm skin flaps based on the epigastric vessels. Primary (1 degree) ischemia was produced by arteriovenous occlusion for 2 hours; (2 degrees) venous ischemia was induced by clamping the vein, alone for either 3 or 5 hours. Thirty minutes prior to 2 degrees ischemia, rats received either L-NAME (30 mg/kg) or saline buffer. Flap survival was assessed 7 days later and Chi-square analysis was used. At 3 hours of ischemia, treatment improved survival from 55% to 85% (P < 0.05). Treatment also improved survival at 5 hours of ischemia from 5% to 35% (P < 0.04). Although under resting conditions, NO is a potent vasodilator, during 2 degrees venous obstruction it may contribute to flap necrosis.     

Vertical double flap design for repair of wide defects of the lower limb, using combined ascending scapular and latissimus dorsi flaps

Two cases are presented in which a scapular osteocutaneous flap and a latissimus dorsi musculocutaneous flap were applied as combined flaps with a single pedicle, to repair massive soft-tissue defects resulting from tibial hemisection in the lower limb. In each case, the oval-shaped donor site was divided into two parts (an ascending scapular flap and a latissimus dorsi flap, respectively) to repair the resected area, using a vertically designed, combined flap from the dorsolateral region. Consequently, after flap elevation, the donor site could be closed primarily and functions of the affected limb could be completely reconstructed. For reconstruction of defects too large to be covered with a single flap, the vertical double flap design of a combined ascending scapular and latissimus dorsi flap is a good alternative. It has the merits of easy dissection, broad area skin coverage and it also provides a composite flap that contains a scapular bone graft. Moreover, it allows a simple microsurgical anastomosis, as well as direct closure of the donor site. In addition, when the recipient site is on the lower leg, flap elevation can be carried out simultaneously with surgery at the recipient site. This means that the operative time can be shortened.     

Importance of endogenous adenosine during ischemia and reperfusion in neonatal porcine hearts

BACKGROUND: Adenosine has several potentially cardioprotective effects. We hypothesized that the effects of endogenous adenosine vary with degree of ischemia and that elevating endogenous levels is protective. METHODS AND RESULTS: Isolated blood-perfused piglet hearts underwent 120 minutes of low-flow ischemia (10% flow) or 90 minutes of zero-flow ischemia, all with 60 minutes of reperfusion. Hearts were treated with either saline, the adenosine receptor blocker 8-sulfophenyltheophylline (8SPT, 300 micromol x L(-1)), or the nucleoside transport inhibitor draflazine (1 micromol x L(-1)). In separate groups, biopsies were obtained before and at the end of ischemia. Compared with saline, 8SPT did not significantly alter functional recovery in either protocol. Draflazine significantly improved percent recovery of left ventricular systolic pressure both in the low-flow protocol (92+/-3% versus 75+/-2% [saline] and 73+/-3% [8SPT], P<.001 for both) and in the zero-flow protocol (76+/-3% versus 59+/-4% [saline] and 46+/-9% [8SPT], P<.05 for both). In the zero-flow protocol, draflazine also significantly reduced ischemic contracture and release of creatine kinase. Tissue adenosine at the end of ischemia was elevated by draflazine compared with saline-treated hearts: after low-flow ischemia to 0.10+/-0.05 versus 0.00+/-0.00 micromol x g(-1) dry wt (P<.05) and after zero-flow ischemia to 1.73+/-0.82 versus 0.15+/-0.03 micromol x g(-1) dry wt (P<.05). CONCLUSIONS: In neonatal porcine hearts, endogenous adenosine produced during ischemia does not influence ischemic injury or functional recovery. Elevating endogenous adenosine by draflazine elicits cardioprotection in both low-flow and zero-flow conditions.     

Ischemic preconditioning in the intact rat heart is mediated by delta1- but not mu- or kappa-opioid receptors

BACKGROUND: Our laboratory has previously shown that delta-opioid receptors are involved in the cardioprotective effect of ischemic preconditioning in the rat heart. However, this class of receptors consists of two subtypes, delta1, and delta2, and mu- or kappa-opioid receptors may also exist in the heart. Therefore, the purpose of the present study was to test the hypothesis that ischemic preconditioning is mediated through stimulation of one or both delta-opioid receptor subtypes. METHODS AND RESULTS: Anesthetized, open chest, male Wistar rats were assigned to 1 of 14 groups. All animals were subjected to 30 minutes of occlusion and 2 hours of reperfusion. Ischemic preconditioning was elicited by three 5-minute occlusion periods interspersed with 5 minutes of reperfusion. Two doses of 7-benzylidenenaltrexone (BNTX; 1 and 3 mg/kg i.v.), a selective delta1-opioid receptor antagonist, or naltriben (NTB; 1 and 3 mg/kg i.v.), a selective delta2-opioid receptor antagonist, were given before ischemic preconditioning. To test for a role of mu-opioid receptors, rats were pretreated with beta-funaltrexamine (beta-FNA; 15 mg/kg s.c), an irreversible mu-opioid receptor antagonist, 24 hours before ischemic preconditioning or given the mu-opioid receptor agonist D-Ala,2N-Me-Phe,4glycerol5-enkephalin (DAMGO) as three 5-minute infusions (1, 10, and 100 microg/kg per infusion i.v., respectively) interspersed with 5-minute drug-free periods before the prolonged ischemic and reperfusion periods (lowDAMGO, medDAMGO, and hiDAMGO, respectively). The involvement of kappa-opioid receptors was tested by administering one of two doses of nor-binaltorphimine (nor-BNI; 1 and 5 mg/kg i.v.) before ischemic preconditioning. Infarct size (IS) as a percent of the area at risk (AAR) was measured by triphenyltetrazolium stain. Ischemic preconditioning markedly reduced IS/AAR (14+/-4%, P<.05) compared with control (55+/-4%). NTB, beta-FNA, and nor-BNI were unable to block the cardioprotective effect of ischemic preconditioning. In addition, DAMGO had no effect on IS/AAR. However, the high dose of BNTX (3 mg/kg i.v.) significantly attenuated the cardioprotective effect of ischemic preconditioning (39+/-5%; P<.05 versus control and ischemic preconditioning). CONCLUSIONS: These results indicate that delta1-opioid receptors play an important role in the cardioprotective effect of ischemic preconditioning in the rat heart.     

Surgical cover of dorsolumbar radionecrosis. Apropos of 6 cases

Thoracolumbar radionecrosis may be difficult to cover. We often use muscular or myocutaneus flaps available in this location, mainly the latissimus dorsi flap. It can be used as a pedicle, free, or especially a "reversed" flap with lumbar pedicles. However in our experience and in the literature this reversed flap is difficult to use because of the morbidity of the flap, transposed without its main pedicle. The authors consider the current methods of cover by flaps in six cases and in the literature. Surgical possibilities are now more numerous. First, a latissimus dorsi muscular flap autonomized by vascular delay, half-free flap, or a flap with the lengthening of its pedicle is possible. Second, we can also use an intercostal island flap for the back and a gluteal thigh flap in the lumbar region.     

Configuration of linear dynamic cardiomyoplasty for hypoplastic right ventricle

BACKGROUND: The purpose of this study is to determine feasibility of linear dynamic cardiomyoplasty with a briefly preconditioned latissimus dorsi in the experimental model simulating patch enlargement of the hypoplastic right ventricle. METHODS: In 8 mongrel dogs, a diminished right ventricular chamber was reconstructed with an extended pericardial patch. A left latissimus dorsi, preconditioned for 2 weeks (2 Hz) after a previous 2-week vascular delay period, was placed on the patch, with the muscle fiber oriented in parallel to the right ventricular long axis. RESULTS: Graft pacing with trained-pulses of 25 Hz at a 1:1 ratio showed significant augmentation of pulmonary flow and pressure (158% +/- 21%, 156% +/- 14%, respectively), contributing to restoring right ventricular function comparable with preoperative control, which was also confirmed by the right ventricular function curve and pressure-volume relationship analyzes. Continuous pacing was performed in 4 animals for 7 hours without evidence of muscle fatigue, implying feasibility of "working conditioning" after minimum preconditioning for this type of right heart assist. CONCLUSIONS: Linear latissimus dorsi myoplasty can restore normal right ventricular performance at a physiologic preload, and may provide a surgical option for the hypoplastic right ventricle.     

Screening a peptidyl database for potential ligands to proteins with side-chain flexibility

OBJECTIVE: Microdialysis and 31P-NMR spectroscopy were used to test opposing hypotheses that ischemic preconditioning inhibits adenine nucleotide degradation and purine efflux, or that preconditioning activates cardiovascular adenosine formation to provide enhanced cardioprotection. METHODS: 31P-NMR spectra and matching interstitial fluid (ISF) or venous effluent samples were obtained from Langendorff perfused rat hearts. Control hearts (n = 9) underwent 30 min of global normothermic ischemia and 30 min reperfusion. Preconditioned hearts (n = 6) were subjected to a 5 min ischemic episode and 10 min reflow prior to 30 min ischemia and 30 min reperfusion. Effects of repetitive ischemia-reperfusion (3 x 5 min ischemic episodes) on adenosine levels and energy metabolism were also assessed (n = 8). RESULTS: Preconditioning improved post-ischemic recovery of heart rate x left ventricular developed pressure (71 +/- 5 vs 43 +/- 8%, P < 0.05) and end-diastolic pressure (14 +/- 3 vs 29 +/- 4 mmHg, P < 0.05) compared with control hearts, respectively. Preconditioning did not alter intracellular ATP, phosphocreatine (PCr), inorganic phosphate (Pi), H+ or free Mg2+ during global ischemia, but improved recoveries of PCr, Pi, and delta GATP on reperfusion. ISF adenosine increased more than 20-fold during 30 min ischemia. The 5 min preconditioning episode increased ISF adenosine 3-fold, and reduced ISF adenosine and inosine during subsequent prolonged ischemia by up to 75%. Venous purine levels during reperfusion were also reduced by preconditioning. Accumulation of adenosine in ISF and venous effluent during repetitive ischemia was progressively reduced despite comparable changes in substrate for adenosine formation via 5'-nucleotidase, (5'-AMP), and in allosteric modulators of this enzyme (Mg2+, H+, Pi, ADP, ATP). CONCLUSIONS: (i) Ischemic preconditioning reduces interstitial and vascular adenosine levels during ischemia-reperfusion, (ii) reduced ISF adenosine during ischemia is not due to reduced ischemic depletion of adenine nucleotides in preconditioned rat hearts, (iii) preconditioning may inhibit adenosine formation via 5'-nucleotidase in ischemic rat hearts, and (iv) improved functional recovery with preconditioning is unrelated to metabolic/bioenergetic changes during the ischemic insult, but may be related to improved post-ischemic recovery of [Pi] and delta GATP in this model.     

Effects of sodium nitroprusside and phenylephrine on blood flow in free musculocutaneous flaps during general anesthesia

BACKGROUND: Hypoperfusion and necrosis in free flaps used to correct tissue defects remain important clinical problems. The authors studied the effects of two vasoactive drugs, sodium nitroprusside and phenylephrine, which are used frequently in anesthetic practice, on total blood flow and microcirculatory flow in free musculocutaneous flaps during general anesthesia. METHODS: In a porcine model (n = 9) in which clinical conditions for anesthesia and microvascular surgery were simulated, latissimus dorsi free flaps were transferred to the lower extremity. Total blood flow in the flaps was measured using ultrasound flowmetry and microcirculatory flow was measured using laser Doppler flowmetry. The effects of sodium nitroprusside and phenylephrine were studied during local infusion through the feeding artery of the flap and during systemic administration. RESULTS: Systemic sodium nitroprusside caused a 30% decrease in mean arterial pressure, but cardiac output did not change. The total flow in the flap decreased by 40% (P < 0.01), and microcirculatory flow decreased by 23% in the skin (P < 0.01) and by 30% in the muscle (P < 0.01) of the flap. Sodium nitroprusside infused locally into the flap artery increased the total flap flow by 20% (P < 0.01). Systemic phenylephrine caused a 30% increase in mean arterial pressure, whereas heart rate, cardiac output, and flap blood flow did not change. Local phenylephrine caused a 30% decrease (P < 0.01) in the total flap flow. CONCLUSIONS: Systemic phenylephrine in a dose increasing the systemic vascular resistance and arterial pressure by 30% appears to have no adverse effects on blood flow in free musculocutaneous flaps. Sodium nitroprusside, however, in a dose causing a 30% decrease in systemic vascular resistance and arterial pressure, causes a severe reduction in free flap blood flow despite maintaining cardiac output.