Search PubMed⌕ Search

Biomedical subjects

M C Dalsing

Publications and source records attributed to M C Dalsing.

At least 73 records · Page 4Linked to original sources
PubMed1987

Large-artery welding with a milliwatt carbon dioxide laser.

Microvascular laser welding can be effectively used in large-diameter artery techniques. The carotid arteries of 12 anesthetized mongrel dogs were exposed. Following heparinization, the carotid arteries were transected, cleaned along their edges, and repaired on the right side by laser and on the left side by suture. The laser-assisted vascular anastomosis (LAVA) required four stay sutures and laser power for welding. Six-week patency for LAVA vs suture anastomosis was 100% vs 92%, respectively. Anastomotic time requirements were less with LAVA (seven vs 25 minutes). Intimal healing for both techniques immediately demonstrated an intraluminal thrombus, which resolved showing complete endothelial repair by four weeks. The laser seal demonstrated little inflammation compared with the giant cell reaction of suture anastomosis. Immediate wall tensions of 6 to 18 X 10(5) dynes/cm2 were tolerated after both techniques. Laser-assisted vascular anastomosis of large-diameter arteries is feasible, strong, and associated with minimal inflammation.

Animals↗
PubMed1987

Endothelial linings: the effect of serine protease inhibition.

The purpose of this investigation was to determine if the inhibition of the serine proteases, thrombin and plasmin, by heparin and epsilon-aminocaproic acid (EACA) would improve endothelial cell retention on synthetic grafts. Endothelium was harvested from the external jugular veins of mongrel dogs using an enzymatic technique. The cells were grown in tissue culture for 3-4 weeks, labeled with 111In oxine, inoculated (2000 cells/mm2) into fibronectin-coated 4 mm-diameter tubes of polyester elastomer (PE, Hytrel 4056, DuPont), and cultured for 18 hr. Each animal received iv heparin (100 U/kg) prior to implantation, and a 4 X 30-mm segment of the culture-lined PE was interposed in the dog's own carotid artery. After 6 hr of flow the grafts were perfusion fixed; the percentage of endothelial retention was determined by 111In counting, and the surfaces of the grafts were analyzed by scanning electron microscopy. Six experiments were performed in each of three treatment groups. Animals in Group I received no additional drugs. Group II animals received a continuous infusion of heparin at 30 U/kg/hr. Group III animals received a bolus of 200 mg/kg of EACA with the initial heparin dose and a continuous infusion of heparin at 30 U/kg/hr and EACA at 200 mg/kg/hr. Group I grafts retained an average of 36.1 +/- 23.3% of the cells; Group II retained 67.5 +/- 24.9%; and Group III retained 83.4 +/- 9.8%. Although continuous heparin infusion resulted in a trend (P = 0.067) toward better retention, a combined infusion of heparin and EACA resulted in significantly better retention (P = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Aminocaproic Acid↗
PubMed1987

A temporary distal arteriovenous fistula improves venous hemodynamics in a model of venous occlusion.

The formation of a temporary distal arteriovenous fistula (dAVF) has been used clinically to palliate patients with symptomatic venous hypertension. This study tested the efficacy of a temporary dAVF for the treatment of venous hypertension in an experimental model. Twenty-four New Zealand white rabbits were divided into two experimental groups. Group I rabbits (n = 12) underwent standardized ligation of the iliac and femoral venous systems. Group II rabbits (n = 12) underwent standardized ligation of the iliac and femoral venous systems with the formation of a temporary dAVF. Venous obstruction was documented with venography, and venous hypertension was documented with femoral venous pressure measurements. Venous pressure, resistance, blood flow, vein circumference, vein cross-sectional area, vein wall thickness, and venography were compared between four rabbits from each group at 2, 4, and 8 weeks. The effect of differences in baseline venous pressures was eliminated by subtracting the venous pressure in the unobstructed rabbit limb from the pressure in the obstructed rabbit leg. Group II rabbits had a lower standardized venous pressure (4.4 +/- 2.2 versus 9.5 +/- 4.2 mm Hg, p less than 0.01) and venous outflow resistance (0.16 +/- 0.08 versus 0.36 +/- 0.18, p less than 0.05) than did group I rabbits. Group II rabbits also had a larger superficial femoral vein circumference (3.46 +/- 0.67 versus 2.57 +/- 0.08 mm, p less than 0.05) and cross-sectional area (0.66 +/- 0.31 versus 0.31 +/- 0.09 mm2, p less than 0.01) than did group I rabbits. The improvement persisted throughout the 6-week study, which suggested an improved venous outflow.

Animals↗
PubMed1986

Chronic contained rupture of abdominal aortic aneurysms.

Anecdotal reports of chronic contained rupture of abdominal aortic aneurysms exist. Their existence and implications have been largely ignored. From March 1984 to March 1985, 24 patients required repair of an infrarenal abdominal aortic aneurysm. Four patients underwent emergent repair. The remaining 20 patients were evaluated with computed tomography electively. Seven patients (35%) were demonstrated to have a rupture of the aneurysm and a retroperitoneal hematoma on the computed tomographic scan. All of the patients had histories of back or flank pain; five patients continued to complain of mild pain on admission. In no case was shock, impending shock, or a decrease in the hemoglobin level present on admission. All patients were operated on within 24 hours of evaluation. At operation, rupture was noted with organized hematoma outside the aorta contained in a pseudoaneurysmal wall of retroperitoneal connective tissue. There was no intraperitoneal blood. There was no operative mortality and survival was 100% at six months. The CT scan evaluation had identified a subgroup of patients with aneurysms associated with chronic contained rupture.

Aged↗
PubMed1985

Restenosis following carotid endarterectomy. Evaluation by duplex ultrasonography.

This study evaluated the efficacy of duplex ultrasonographic scanning in assessing the status of carotid arteries after 155 endarterectomies in 131 patients. Duplex studies were done as early as one month and as late as 96 months postoperatively; 33 patients had serial studies. Only 59 (42%) of 142 arteries had no evidence of irregularity or reduction in diameter at the operative site. An additional 41 (29%) had a reduction in diameter between 10% and 29%; 19 (13%) had reductions of 30% to 49%; nine (6%) from 50% to 69%; six (4%) from 70% to 99%; and eight (6%) were occluded. In 51 vessels, angiographic studies confirmed the duplex findings. Symptoms suggestive of recurrent cerebrovascular disease occurred postoperatively in 25 instances; in only three were the anatomic findings suggestive of lesions appropriate to the symptoms. We conclude that duplex ultrasonographic scanning is a useful technique for assessing carotid arteries after endarterectomy and that postoperative narrowing of vessels occurs more commonly than suspected.

Aged↗
PubMed1985

Infrapopliteal bypass for established gangrene of the forefoot or toes.

This study was undertaken to assess factors affecting limb salvage after femorodistal bypass in patients with established gangrene. From January 1977 through June 1983, 361 patients underwent infrapopliteal bypasses; 58 patients (59 limbs) had forefoot and/or toe gangrene. There were 33 men and 25 women (mean age 67.6 years), and 40 patients (69%) were diabetic. A total of 71 femorodistal bypass procedures were performed in these patients: a single bypass in 49, repeat procedure in eight, and multiple bypasses in two patients. Graft material was autogenous saphenous vein in 22 cases, polytetrafluoroethylene (PTFE) in 39 cases, and a composite graft in 10 procedures. After bypass 50 patients underwent limited toe or forefoot amputation with uncomplicated healing. Limb salvage by life-table analysis was 70% at 1 year, 60% at 3 years, and 28% at 5 years. The graft patency at 3 years was 65% for vein grafts and 30% for PTFE grafts. In the entire series the operative mortality rate was 1.7%. Age, sex, hypertension, or diabetes mellitus did not influence the result of surgery. Similarly, failure of a previous femoropopliteal or tibial graft did not reduce the likelihood of limb salvage. Graft patency, however, is prerequisite for limb salvage, and graft patency can be maintained by thrombectomy or repetitive bypass. The present study suggests that limb salvage is possible in as many as two thirds of limbs with established gangrene. Although saphenous vein remains the graft material of choice, its absence should not preclude attempts at limb salvage. Repetitive grafting did not jeopardize patient safety but contributed significantly to extended limb survival.

Actuarial Analysis↗
PubMed1983

The effect of protein deficiency on growth and response of primary and metastatic hepatoma.

Although protein-energy malnutrition is common in the cancer patient, the efficacy of aggressive nutritional therapy is unclear. This study evaluates the effects of protein deficiency on tumor growth, response, and chemotherapy complications in primary and metastatic rat hepatoma. Seventy-two ACI rats (200-250 g) with implanted Morris hepatoma were divided into four groups (N = 18 for each group): 1, regular diet; 2, regular diet plus cyclophosphamide (CPM) (100 mg/kg/ip); 3, protein-free diet; and 4, protein-free diet + CPM. Forty additional rats in similar groups (5-8, ten in each group) underwent intravenous injection of 6 X 10(3) tumor cells to produce pulmonary metastases. Animals were assessed for survival, tumor size, serum albumin, number of pulmonary metastases, and hemorrhagic cystitis at 2 weeks. Survival was 50% in groups 4 and 8, and 100% in the others. Serum albumin was significantly lower in rats on protein free diets (2.59 +/- 0.37 vs 3.35 +/- 0.40 g%, P less than 0.01). Tumor volume was significantly reduced by CPM (26.0 +/- 4.2 cm3 vs 1.2 +/- 0.4 cm3, P less than 0.01). Protein-free diets resulted in lower total body weight, and reduced tumor volume without, but not with CPM (14 +/- 1.6 cm3 P less than 0.05, 1.1 +/- 0.3 cm3, P less than 0.05 vs above controls). CPM reduced the number of pulmonary metastases in regular diet groups (307.2 +/- 108.3 vs 36 +/- 11, P less than 0.01), while protein free diets did not significantly affect metastases, without or with CPM (251.7 +/- 71.4 and 22.3 +/- 12.4, P greater than 0.05 vs controls). Hemorrhagic cystitis was much more common in protein free groups compared to rats on regular diets (55 vs 11%, P less than 0.01). These data indicate that protein deficiency did not affect response to chemotherapy in a primary or metastatic rat hepatoma model. However, protein deficiency results in a significantly increased rate of mortality, weight loss, and hemorrhagic cystitis which may lead to delay or cessation of cancer therapy.

Animals↗
PubMed1983

Superoxide dismutase: a cellular protective enzyme in bowel ischemia.

Recent data suggest that the free-radical anion superoxide (O-2), an unstable, cytotoxic form of oxygen, is implicated in the pathogenesis of ischemic bowel injury. This study evaluates the role of superoxide dismutase (SOD), an enzyme specific for enzymatic conversion of O-2 in protecting the bowel from an ischemic insult. At laparotomy, the superior mesenteric artery was occluded for 1 min in 90-g weanling rats (n = 144). Animals were divided into four groups: I, untreated controls (n = 41); II, received aminophylline (AMN) 40 mg/kg ip, a substrate for (O-2) generation (n = 21); III, received superoxide dismutase (SOD) 2.5 mg/kg iv (n = 20); IV, received both AMN and SOD (n = 22). Rats were evaluated for bowel infarction, perforation, and mortality over a 7-day observation period. In 40 additional rats (10 per group) bowel ultrastructure was evaluated by scanning electron microscopy (EM) during occlusive ischemia and at various time intervals following reperfusion. Mortality was 63.4% in controls (26/41) with necrosis noted in 19 and perforation in 7. AMN resulted in a 90% mortality (19/21) (chi 2, P less than 0.05 vs control), with necrosis in 15 and perforation in 4. SOD reduced mortality to 25% (5/20) with necrosis in 4 and perforation in 1 (chi 2, P less than 0.02 vs controls) and, when added to AMN, 45.5% (10/22) (chi 2, P less than 0.01 vs AMN alone). On EM, tissue damage was minimal during occlusive ischemia, worsened by duration of reperfusion, enhanced by AMN, and reduced by SOD. These data suggest that following hypoxia, the injured bowel may be unable to appropriately handle reoxygenation. Tissue damage was related to duration of reperfusion and was worse following AMN, a xanthine derivative that might generate (O-2), a cytotoxic free radical. SOD detoxifies O2-, increases survival, and protects the bowel during reperfusion.

Aminophylline↗
PubMed1983

Ischemic bowel: the protective effect of free-radical anion scavengers.

Recent data indicates that the free-radical anion superoxide (O2-), an unstable cytotoxic form of oxygen, is implicated in the pathogenesis of ischemic bowel following reperfusion after low flow states. This report evaluates the effect of free radical scavengers on survival in an animal model with bowel ischemia. At laparotomy, the superior mesenteric artery (SMA) of 79 weanling rats (90 g) was occluded for one minute and released. Animals were divided into three experimental groups: group I acted as controls (n = 41), group II, received thiopental 5 mg/kg IV (n = 19), group III, received methohexital 2.5 mg/kg IV (n = 19). At one week animals were evaluated for mortality, mean survival time, evidence of bowel necrosis or perforation, and bowel appearance on scanning electron microscopy (EM). Mortality was 63.5% (26/41) in group I, 19 had necrotic bowel and 7 had gross perforation; 31.6% in group II (6/19) (p less than .05 versus control), with one necrotic bowel and 5 perforations; and 57.9% in group III (11/19) where 7 had necrotic bowel and 4 had perforations (p NS v control). Survival time (mean +/- SD in days) post SMA occlusion was 3.2 +/- 1.9 for group I; 4.0 +/- 1.7 for group II; and 2.5 +/- 2.0 for group III. EM showed mucosal destruction worsened by the duration of reperfusion, decreased by thiopental but not by methohexital. Thiopental, a free radical anion scavenger was cytoprotective in this animal model, as it decreased mortality and the incidence of bowel necrosis and perforation. These data support the thesis that following low flow states bowel ischemia may be related to a reperfusion injury due to the release of toxic free radical anions.

Animals↗
PubMed1983

Neonatal apnea, xanthines, and necrotizing enterocolitis.

This study evaluates the relationship of xanthine treatment of premature apnea and NEC in a bowel ischemia model. The superior mesenteric artery was occluded for 1.0 minute in 82 wheanling rats. Group I (n = 41) were untreated controls. Group II (n = 21) received aminophylline (AMPH) 40 mg/kg I.P., 4 hr and immediately prior to clamping. Animals were evaluated for bowel infarction, perforation, and mortality at 7 days. In 20 additional rats (10 per group) bowel was evaluated by scanning electron microscopy (EM) at timed intervals (5 and 30 min). Ischemic bowel occurred in 25 of 41 (60%) controls (18 (43%) with necrosis; 7 (17%) with perforations) and 19 of 21 (90%) rats with AMPH (15 (70%) had necrosis; 4 (19%) perforations). Mortality was 60% (controls) and 90% (AMPH) respectively (p less than .05). On EM, AMPH enhanced bacterial overgrowth however actual mucosal damage appeared similar. Following ischemia, AMPH has an adverse effect on the bowel. Use of AMPH in prematures at risk for NEC is questioned.

Aminophylline↗
PubMedDate not supplied

Median arcuate ligament syndrome with multivessel involvement: diagnosis with spiral CT angiography.

Intestinal angina may be caused by compression of the celiac artery by the median arcuate ligament of the diaphragm. Aortography can suggest the diagnosis, but the diaphragm cannot be visualized by this examination. We report a symptomatic woman in whom spiral computed tomography-guided angiography demonstrated stenosis of the celiac artery, superior mesenteric artery, and both renal arteries due to diaphragmatic compression. Surgery was beneficial.

Celiac Artery↗
PubMedDate not supplied

Stent grafting of abdominal aortic aneurysms: pre-and postoperative evaluation with multislice helical CT.

Endovascular stent grafting of abdominal aortic aneurysms is a new technique that may replace open surgery in selected cases. Pre-and postoperative angiography can be replaced by helical CT. This pictorial essay describes and illustrates the use of multislice helical CT where maximum intensity projection and multiplanar reformats play a central role in the evaluation.

Aged↗
PubMedDate not supplied

Wall remodeling after wall shear rate normalization in rat mesenteric arterial collaterals.

Previous studies have demonstrated endothelial and smooth muscle hyperplasia occur during arterial luminal expansion associated with elevation of arterial wall shear rates. The current study investigated whether remodeling induced by elevated wall shear would ultimately result in a vessel with intimal and medial cell densities and other wall characteristics similar to control arteries. A rat mesenteric model was used in which collateral wall shear is restored to normal 4 weeks after arterial occlusion. Twelve weeks after shear elevation, paired in vivo measurements indicated that the maximum collateral inner diameter was increased 27-75%. Morphometric evaluation of collateral cross sections indicated that, relative to control arteries, luminal and medial areas were increased 79 +/- 22 and 56 +/- 15%. Collateral medial cell density was decreased (1.12 +/- 0.044 vs. 1.35 +/- 0.005 nuclei/1,000 micrometer(2) but intimal cell density was similar (2.86 +/- 0.166 vs. 2.49 +/- 0.102 nuclei/100 micrometer luminal perimeter). Medial thickness to radius ratio was also similar between control and collateral arteries. Thus, for the wall characteristics evaluated, there are many similarities between enlarged collaterals and control arteries. Comparison of nuclear numbers in arterial cross sections of the current and previous studies suggest that intimal and medial cellular regression is correlated with a decrease in wall shear force toward normal levels.

Animals↗
PubMedDate not supplied

Nitric oxide maintains dilation of immature and mature collaterals in rat hindlimb.

The role of nitric oxide (NO) in maintaining collateral dilation was investigated in rats with acute and chronic superficial femoral artery occlusion. Collateral function was evaluated from arterial pressure measurements proximal (mean arterial pressure, MAP) and distal (PD) to the occlusion under resting and hyperemic conditions. For resting and hyperemic conditions, respectively, PD increased with the duration of occlusion from 34 +/- 2.1 and 14 +/- 0.8 mm Hg acutely postocclusion to 37 +/- 2.8 and 19 +/- 3.6, 42 +/- 4.9 and 25 +/- 1.5, and 49 +/- 5.6 and 25 +/- 2.1 mm Hg at 1, 4, and 12 weeks. After NO synthase inhibition with N omega-nitro-L-arginine methyl ester (L-NAME), PD in control limbs increased but in occluded limbs decreased by 20 +/- 2.0 mm Hg (acute) and 18 +/- 2.1, 15 +/- 4.4, and 20 +/- 8.1 mm Hg at 1, 4, and 12 weeks postligation, respectively. The percent of MAP (%MAP) dissipated by large arteries and collateral vessels decreased during collateral development (from 71 +/- 1.7% acutely to 57 +/- 2.2% at 12 weeks postligation) and was increased approximately 20% by L-NAME at each time point. The rise in PD and decrease in %MAP dissipated by collaterals following chronic occlusion indicates that significant collateral development occurred. The fall in PD and increase in %MAP dissipation after L-NAME administration suggest that NO-mediated vasodilatory tone is maintained throughout the period of collateral development.

Animals↗