Effects Of Vascular Occlusion Research Articles

Cutaneous microvascular occlusion syndrome as the first manifestation of catastrophic lupus-associated antiphospholipid antibody syndrome: a case report

BackgroundAntiphospholipid syndrome (APS), defined by thrombotic events or obstetric complications in the presence of persistently high antiphospholipid antibodies, is characterized by a wide variety of clinical presentations and the effects of vascular occlusion can impact almost any organ system or tissue. Since adult-onset APS classification criteria are not well verified in pediatrics (where pregnancy-related problems are rare), estimating childhood prevalence is challenging. Stroke and pulmonary embolism are thromboembolic events occurring in children that can cause considerable long-term morbidity. Children with APS are more prone to recurrent thromboembolism than adults. Cutaneous symptoms are prominent and typically represent the first clue of APS. Although dermatologic findings are exceedingly heterogeneous, it is essential to consider which dermatological symptoms justify the investigation of antiphospholipid syndrome and the required further management.Case presentationWe describe a seven-year-old Iranian boy with retiform purpura and acral cutaneous ischemic lesions as the first clinical presentation of antiphospholipid syndrome in the setting of systemic lupus erythematous.ConclusionAPS in pediatrics, is associated with a variety of neurologic, dermatologic, and hematologic symptoms. Therefore, it is essential for pediatricians to be aware of the rare appearance of Catastrophic APS as an initial indication of APS.

Effects of selective hepatic vascular occlusion on the prognosis of patients undergoing hepatic resection for huge liver cancer

Objective To evaluate the effects of selective hepatic vascular occlusion SHVO) on the prognosis of patients undergoing hepatic resection for huge liver cancer.Methods The clinical data of 49 patients who received huge liver cancer resection at the Zhejiang People's Hospital from January 2005 to January 2010 were retrospectively analyzed.Based on the type of hepatic vascular occlusion,all patients were divided into Pringle's maneuver group (24 patients) and SHVO group (25 patients).The intraoperative condition,postoperative recovery of hepatic and renal function,incidence of complications,survival rate and recurrence rate of liver cancer of the 2 groups were compared.All data were analyzed by using the t test or Fisher exact probability.The survival curve was drawn by using the Kaplan-Meier method and the survival of the 2 groups was compared by using the Log-rank test.Results Hepatectomy was successfully performed on all the patients.Time for blood occlusion were (32 ±19) minutes in the Pringle's maneuver group and (34 ± 22)minutes in the SHVO group,with no significant difference between the 2 groups (t =2.45,P ＞ 0.05).The volume of blood loss of the Pringle's maneuver group was (736 ± 543) ml,which was significantly greater than (273 ± 298) ml of the SHVO group (t =6.87,P ＜0.05).The incidences of hepatic vein rupture were 21％ (5/24) in the Pringle's maneuver group and 24％ (6/25)in the SHVO group,with no significant difference (x2=1.45,P＞0.05).The course of 3 patients was complicated by hepatic vein rupture and hemorrhage and 1 by air embolism in the Pringle's maneuver group,while no hemorrhage or air embolism happened in the SHVO group.Four patients in the Pringle's maneuver group and 3 in the SHVO group were found with vascular invasion,while the resection margins were negative.There was no significant difference in the hepatic function in the 2 groups before operation.The levels of alanine aminotransferase in the SHVO group at postoperative day 1 and 3 were significantly lower than those in the Pringle's maneuver group (t=7.12,6.35,P ＜ 0.05).There was no significant difference in the levels of blood urea nitrogen and creatinine between the 2 groups (P ＞ 0.05).Acute hepatic dysfunction was found in 4 patients in the Pringle's maneuver group,but no patients with acute hepatic dysfunction was found in the SHVO group.The 1-and 3-year tumor-free survival rates were 58％ and 21％ in the Pringle's maneuver group,which were significantly lower than 72％ and 30％ in the SHVO group (x2 =5.32,6.07,P ＜ 0.05).The 5-year tumor-free survival rates were 21％ in the Pringle's maneuver group and 20％ in the SHVO group,with no significant difference between the 2 groups (x2 =1.78,P ＞ 0.05).Conclusion SHVO is safe,feasible and effective to prevent hemorrhage and postoperative acute hepatic dysfunction,and it is also helpful in reducing early-stage tumor recurrence and improving the tumor-free survival rate in patients with huge liver cancer. Key words: Liver neoplasms; Hepatectomy ; Hepatic vascular occlusion ; Recurrence

Effect of vascular occlusion on radiofrequency ablation of the liver in a rabbit VX2 tumor model

Effect of vascular occlusion on radiofrequency ablation of the liver in a rabbit VX2 tumor model

Structure and Function of Myelinated Nerve Fibers in the Rabbit Eye Following Ischemia/Reperfusion Injury

The rabbit eye presents a valuable model to study the effects of vascular occlusion on the function and structure of myelinated nerve fibers. The rabbit eye has a band of myelinated nerve fibers within the intraocular compartment that are supplied by a narrow band of retinal vasculature. These vessels were transiently occluded ( approximately 8 hours) using laser photocoagulation and the transmission of electrical signals along the nerve fibers was assessed by recording the visual evoked response (VER). Morphological damage was assessed by histological techniques. The ischemic insult produced no permanent change in retinal function as assessed by electroretinography, but the VER was suppressed, indicating failure of nerve fiber transmission. Histologically, the visible damage to the region supported by the retinal vasculature worsened following reperfusion, showing evidence of demyelination and necrosis followed by macrophage responses and gliosis. This rabbit model of ischemia/reperfusion of the retinal vasculature offers a rare opportunity to reliably study the response of myelinated nerve fibers to ischemia/reperfusion insults and has demonstrated the susceptibility of myelinated nerve fibers to such insults.

Effects of Vascular Occlusion on Muscular Endurance in Dynamic Knee Extension Exercise at Different Submaximal Loads

Strength training with low load under conditions of vascular occlusion has been proposed as an alternative to heavy-resistance exercise in the rehabilitation setting, when large forces acting upon the musculoskeletal system are unwanted. Little is known, however, about the relative intensity at which occlusion of blood flow significantly reduces dynamic muscular endurance and, hence, when it may increase the training effect. The purpose of this study was to investigate endurance during dynamic knee extension at different loads with and without cuff occlusion. Sixteen subjects (20-45 years of age) with strength-training experience were recruited. At 4 test sessions, the subjects performed unilateral knee extensions to failure with and without a pressure cuff around the thigh at 20, 30, 40, and 50% of their 1 repetition maximum (1RM). The pressure cuff was inflated to 200 mm Hg during exercise with occlusion. Significant differences in the number of repetitions performed were found between occluded and nonoccluded conditions for loads of 20, 30, and 40% of 1RM (p < 0.01) but not for the 50% load (p = 0.465). Thus, the application of a pressure cuff around the thigh appears to reduce dynamic knee extension endurance more at a low load than at a moderate load. These results may have implications regarding when it could be useful to apply a tourniquet in order to increase the rate of fatigue and perhaps also the resulting training effect. However, the short- and long-term safety of training under ischemic conditions needs to be addressed in both healthy and less healthy populations. Furthermore, the high acute pain ratings and the delayed-onset muscle soreness associated with this type of training may limit its potential use to highly motivated individuals.

Effects of Vascular Occlusion on Surface Electromyography and Muscle Oxygenation during Isometric Contraction

Objective:To investigate changes in motor-unit activity and muscle oxygenation (MO) during isometric contraction with and without vascular occlusion using surface electromyography (EMG) and near-infrared spectroscopy.Design and Setting:MO and EMG of the right vastus medialis muscle were measured during isometric contraction at 30%, 50%, and 70% maximal voluntary contraction (MVC), with and without vascular occlusion.Participants:6 healthy men.Results:Integrated EMG (IEMG) and mean power frequency were significantly higher with vascular occlusion at 30% and 50% MVC. MO reduction at each load was significantly lower with vascular occlusion. A significant positive correlation was found between IEMG and changes in MO level under both conditions.Conclusions:These results suggest that oxygen supply to active muscles was impaired by occlusion and that type II fibers were then preferentially recruited, which suggests that hypertrophy occurs in low-intensity exercise in patients with limitations resulting from advanced age, pain, or postsurgery limitation.

Lesion progression with time and the effect of vascular occlusion following radiofrequency ablation of the liver.

The effectiveness of radiofrequency ablation (RFA) under selective vascular occlusion and its effects on architecture and viability of normal liver parenchyma was studied in a porcine model. RFA was applied in the liver under general anaesthesia in 18 pigs. Six animals were killed immediately after the procedure and 12 at 24 h. RFA was performed sequentially under four conditions: (1) without vascular occlusion, (2) during occlusion of the hepatic artery, (3) during occlusion of the portal vein and (4) during occlusion of the hepatic artery and portal vein. Liver biopsies from the treated area were stained for conventional histological examination, reduced nicotinamide adenine dinucleotide diaphorase and 5'-nucleotidase activity. Vascular occlusion significantly increased the size of the coagulation centre after RFA. Combined portal venous and arterial occlusion had no additional effect on lesion size compared with venous or arterial occlusion alone. After 24 h, deterioration of viability was observed in the parenchyma up to 3 cm from the coagulated area. The efficacy of RFA in liver increases with occlusion of the portal vein or hepatic artery. The extent of secondary heat-induced necrosis in liver parenchyma should be considered for determination of the final size of the ablated area.

Aggravation of brain injury after transient focal ischemia in p53-deficient mice

The transcriptional factor p53 is a regulatory protein which contributes to the preservation of tissue integrity by promoting either DNA repair or apoptosis. To establish the pathophysiological role of this protein in ischemia, we produced 1 h transient middle cerebral artery (MCA) occlusion in normal and in p53-deficient mice and investigated the resulting tissue damage by multiparametric imaging. Possible genetic influences on the angioarchitecture of the MCA territory and blood flow were examined by intravascular latex infusion and laser-Doppler flowmetry. Wild-type (p53 +/+), heterozygous (p53 +/−) and homozygous (p53 −/−) mice deficient for the p53 gene did not differ in respect to angioarchitecture or the effect of vascular occlusion on blood flow and general physiological parameters. Twenty-four hours after 1 h MCA occlusion, mice revealed a gene dose-dependent decline in the size of metabolic disturbances (ATP depletion and inhibition of protein synthesis) and histological injury (Cresyl Violet staining). DNA fragmentations detected by terminal deoxynucleotidyl transferase-mediated UTP nick end labeling (TUNEL) did not differ in the three groups and were only present in ATP-depleted tissue. Our findings suggest that after transient focal brain ischemia p53 prevents rather than aggravates brain injury, and that this effect is brought about by mechanisms that are unrelated to the pro-apoptotic properties of this gene.

Temporal variation and factors affecting measurement of canine von Willebrand factor

Abstract Objective To determine whether canine plasma von Willebrand factor (vWf) varies between and within individuals over time and with different blood sample collection and processing procedures. Animals 26 adult dogs and 6 pups. Procedure Blood was obtained from the jugular or cephalic vein daily for 8 to 19 days and weekly for 9 to 23 weeks in adult dogs and periodically up to 180 days of age in pups. Temporal variation in vWf concentration and the effect of vascular occlusion, venipuncture site, lipemia, hemolysis, anticoagulant, storage time, freeze-thawing, and centrifugation speed on plasma vWf concentration, measured by ELISA, were determined. Results Plasma vWf concentration varied over time. In dogs with mean vWf concentration ≥ 79 U/dl, the largest intraindividual range in vWf spanned 64 U/dl with daily and 53 U/dl with weekly sample collection. In dogs with mean vWf concentration ≤ 24 U/dl, the largest individual variation was 12 U/dl with daily and weekly sample collection. In dogs with mean vWf concentration ≥ 53 and ≤ 74 U/dl, the largest intraindividual range spanned 35 U/dl. Mean vWf concentration of pups from 3 to 180 days of age did not change. Sample hemolysis decreased mean vWf by 37%. Mean vWf concentration was 9% higher in cephalic than jugular vein samples (P = 0.056). Other sample collection/preparation procedures did not affect vWf concentration. Conclusion There was substantial temporal variation in vWf concentration within individual dogs. Clinical Relevance Multiple tests may be necessary to obtain a reliable estimate of vWf concentration in dogs. (Am J Vet Res 1996;57:1288-1293)

Modification of human tumour and normal tissue pH during hyperthermic and normothermic antiblastic regional isolation perfusion for malignant melanoma: a pilot study.

Human tumour and normal tissue pH were investigated during hyperthermic and normothermic antiblastic regional isolation perfusion and the effects of vascular occlusion, artificially induced hypoxia, hyperglycaemia, haemoglobin level of the perfusate and hyperthermia on tumour and normal tissue pH were evaluated. A pilot study was performed on 10 patients, with locally inoperable recurrent and primary malignant melanoma of the leg. The treatment consisted of a regional isolation perfusion with hyperthermia (120 min at 42-43 degrees C), at femoral level, followed by a normothermic regional isolation perfusion with Melphalan (60 min at 37-38 degrees C), at iliacal level, 7-10 can be distinguished: (1) first ischaemic anoxia period; (2) extracorporeal circulation, during which the leg is heated to the desired temperature, after which either hyperthermia or Melphalan is applied; (3) second ischaemic anoxia period. During the anoxia periods the large vessels that supply the leg are temporarily clamped and the effects on tissue pH can be investigated. During extracorporeal circulation, high-dose glucose can be administered to the isolated leg, to acutely decrease tumour tissue pH. Such a decrease is expected to sensitize tumours to hyperthermia, when applied immediately prior to or during heating. At the beginning of the treatment the mean tumour pH was significantly lower than normal tissue pH (7.14, with a mean tumour volume of 39.2 cm3, and 7.38, respectively; p < 0.01). During the perfusions with hyperthermia and Melphalan, tissue pH decreased by -0.41 units and -0.20 for tumour, and -0.11 units for normal tissue, respectively (all statistically significant). The two anoxia periods accounted for approximately half of the net decrease. During these periods tumour pH appeared to decrease more selectively, although there was great variation. The other investigated modalities, such as hyperglycaemia and hyperthermia, also decreased tissue pH, but to a lesser extent. However, a combination of more than one modality caused a larger decrease than a single one, but no preference for tumour could be detected. Before the second perfusion mean tumour pH was significantly increased by 0.14 units, and was no longer significantly different from normal tissue pH in the course of the regional isolation perfusion. This could be the reflection of the reduced tumour volume (by 30%, n.s.). Similar pH changes occurred during this Melphalan perfusion, but they were less pronounced since the total treatment time was shorter. Summarizing, tumour pH can be decreased more than normal tissue pH in the course of the regional isolation perfusion. In particular, vascular occlusion appeared to be tumour pH selective.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of Pulmonary Embolism on the Lung

Summary The pathophysiologic consequences of pulmonary thromboemboli on pulmonary function result both from the direct effects of vascular occlusion and from released vasoactive and bronchoactive mediators. All of these alterations in function are further modified by the effect of embolization on cardiac function, predominantly through modification of the ####. This complex interaction of events makes it difficult to clearly assign mechanisms to all of the observed changes in patients as well as to utilize changes in clinical values as a way of following the natural history of the vascular occlusion.

Effects of vascular occlusion on the femoral head in growing rabbits.

Temporary vascular occlusion of the femoral head in 6-week-old rabbits was produced by a closed means in a hip spica; the hips were maintained for 24 h in the position of flexion, abduction and internal rotation. All animals developed necrosis of the capital femoral epiphysis, best seen histologically at 2 weeks, and this subsequently recovered. Despite marked histological changes only one hip developed radiographic changes.

The effects of vascular occlusion on the human inner ear.

Occlusion of the anterior vestibular artery has resulted in severe degeneration and new bone formation limited to the utricle, saccule, and superior and lateral semicircular canals. Depriving the inner ear of its main blood supply, i.e. the internal auditory artery, has resulted in severe degeneration and ossification of the entire membranous labyrinth, except the endolymphatic duct and sac. A more severe cochlear sclerosis was seen when both arterial and venous blood supplies to the cochlea were occluded. The implications of these findings on the etiology and management of inner ear disorders are emphasized.

The effect of vascular occlusion on the thermal sensitization of a mouse tumour.

The effect of occluding the blood supply to a mouse tumour (with a metal clamp) has been studied for both irradiation and heating. Local heat was applied by immersion in a water bath for one hour at 42.8 degrees C or for 15 minutes at 44.8 degrees C. Occlusion of the blood supply during heating has a profound cytotoxic effect on the tumour, even in the absence of irradiation. Most tumours treated with 42.8 degrees C for one hour under clamped conditions were locally controlled whether they were irradiated or not. Tumours heated with their blood supply unobstructed showed a lesser sensitivity to heat, seen as an increased sensitivity to X rays with a thermal enhancement ratio of 1.8--2.6. With the shorter period of more intense heat (44.8 degrees C for 15 min), the effect of increasing the clamping time before heating was studied. The proportion of tumours locally controlled increased from 33% if the clamp was applied immediately before heating to 83% if the clamp was present for 60 minutes before heating commenced. No cures were observed for heat applied immediately before clamping, or immediately after release of the clamp. Accumulation of metabolic products or pH changes are implicated as the factors which alter the thermal sensitivity of these tumour cells.

The reactivity of the pial circulation of the rabbit to hypercapnia and the effect of vascular occlusion.

The reactivity of the pial circulation of the rabbit to hypercapnia and the effect of vascular occlusion.

Effect of vascular occlusion on small-bowel intraluminal pressures in dogs.

1. Intraluminal pressure recordings were obtained in 14 mongrel dogs after either superior mesenteric arterial occlusion (in 7 animals) or superior mesenteric venous occlusion (in 7 other animals).

The Effect of Vascular Occlusion on Transplanted Tumors

The Effect of Vascular Occlusion on Transplanted Tumors