Changes in hepatocyte dehydrogenase activity in different zones of liver acini during the revascularization of ischemic extremities

After ischemia (3, 6, 9 and 12 h) of the hind extremities in dogs with a subsequent revascularization for 2 h, enzymatic activity of hepatocytes changes. After ischemia for 3 h the enzymatic activity increases. Restoration of the blood flow at later stages of the experiment results in a progressive decrease of dehydrogenase and diaphorase activities. To a greater extend the changes of the enzymatic activity are observed in perivenular hepatocytes (in the 3d zone of the hepatic acinus).     

Quantitative histophotometric study of liver dehydrogenase activity during temporary ischemia of the extremities

This prospective study depicts quantitative histophotometric characteristics of the changes in the histoenzymologic spectrum of the liver in the course of temporary ischemia of the extremities with subsequent revascularization. The increase in the activities of dehydrogenases under study in the course of a 3-hour ischemia, and the decrease of these parameters in 6- and 12-hour ischemia was discovered, that was determined as a compensatory response followed by the period of compensation exhaustion and the development of the period of complete exhaustion. The data of the study of drug correction of the postischemia syndrome confirmed the rationality of the efforts that were made. A special program developed for computer processing of histological data allows rapid adaptation of the methods for different histophotometric examinations with the use of TV analyzer of the picture, this creating wider possibilities as compared to the known analogs.     

Caloric restriction stimulates revascularization in response to ischemia via adiponectin-mediated activation of endothelial nitric-oxide synthase

Caloric restriction (CR) can extend longevity and modulate the features of obesity-related metabolic and vascular diseases. However, the functional roles of CR in regulation of revascularization in response to ischemia have not been examined. Here we investigated whether CR modulates vascular response by employing a murine hindlimb ischemia model. Wild-type (WT) mice were randomly divided into two groups that were fed either ad libitum (AL) or CR (65% of the diet consumption of AL). Four weeks later, mice were subjected to unilateral hindlimb ischemic surgery. Body weight of WT mice fed CR (CR-WT) was decreased by 26% compared with WT mice fed AL (AL-WT). Revascularization of ischemic hindlimb relative to the contralateral limb was accelerated in CR-WT compared with AL-WT as evaluated by laser Doppler blood flow and capillary density analyses. CR-WT mice had significantly higher plasma levels of the fat-derived hormone adiponectin compared with AL-WT mice. In contrast to WT mice, CR did not affect the revascularization of ischemic limbs of adiponectin-deficient (APN-KO) mice. CR stimulated the phosphorylation of endothelial nitric-oxide synthase (eNOS) in the ischemic limbs of WT mice. CR increased plasma adiponectin levels in eNOS-KO mice but did not stimulate limb perfusion in this strain. CR-WT mice showed enhanced phosphorylation of AMP-activated protein kinase (AMPK) in ischemic muscle, and administration of AMPK inhibitor compound C abolished CR-induced increase in limb perfusion and eNOS phosphorylation in WT mice. Our observations indicate that CR can promote revascularization in response to tissue ischemia via an AMPK-eNOS-dependent mechanism that is mediated by adiponectin.     

The formation of heteroagglutinins in rats "chemically" splenectomized by ethyl palmitate, in comparison to animals surgically splenectomized.

In Wistar rats "chemically splenectomized" by an i.v. injection of ethyl palmitate the formation of heteroagglutinins against human O-erythrocytes has been followed. Ethyl palmitate applied 2 hrs before immunization induced on the 5th day a significant decrease of the antibody level. This temporary inhibition, however, was at a later stage replaced by a significant increase of antibody level with the peak of 8--14 days. Animals surgically splenectomized 24 hrs prior to immunization displayed a weak antibody response throughout the experiment. An injection of the ethyl palmitate on the 6th day after immunization induced a pronounced and persistent decrease of the antibody level. Surgical splenectomy performed within the same interval had a comparable effect. The experiments revealed that the inhibitory effect of ethyl palmitate on antibody production was temporary only, and at a later stage could be compensated by an enhanced antibody activity.     

Morphological characteristics of the changes in the skeletal muscle tissue in acute experimental ischemia of the extremities

A comprehensive morphological study of the ischemic skeletal muscles of the limbs was performed in experiments on dogs. Ischemia of the muscle tissue was induced by artificial embolic occlusion of the terminal part of the aorta. A quantitative functional and morphological study revealed serious disturbances in metabolism of the skeletal muscle that was subjected to a 6-hour ischemia. Depression of aerobic metabolism, ineffectiveness of anaerobic glycolysis (a spare pathway of the synthesis of macroergic substances), a dramatic lowering of ATPase activity, and activation of acid phosphatase in experiments of such a duration are important signs of a probably compromised adaptation process and irreversibility of the lesions in the tissue. The data should be taken into consideration in determining the optimal periods of the blood flow recovery in the limbs. Morphological changes in muscle fibers under ischemia progress with an increase in the experiment duration (up to 9 and 12 h). An important morphological sign of ischemia is a disturbed typification of muscle fibers.     

Time-dependent changes in lipid metabolism in mice with methionine choline deficiency-induced fatty liver disease

Methionine and choline-deficient diet (MCD)-induced fatty liver is one of the best-studied animal models of fatty liver disease. The present study was performed to clarify the relative contributions of individual lipid metabolic pathways to the pathogenesis of MCD-induced fatty liver. Hepatic lipogenesis mediated by the sterol regulatory element-binding protein (SREBP-1c) was increased at 1 week, but not at 6 weeks, of MCD feeding. On the other hand, ¹⁴C-palmitate oxidation did not change at 1 week, but significantly decreased at 6 weeks. This decrease was associated with increased expression of fatty acid translocase, a key enzyme involved in fatty acid uptake. Expression of endoplasmic reticulum stress markers was increased in mice given MCD for both 1 and 6 weeks. These findings suggest the presence of time-dependent differences in lipid metabolism in MCD-induced fatty liver disease: SREBP-1c-mediated lipogenesis is important in the early stages of fatty liver disease, whereas increased fatty acid uptake and decreased fatty acid oxidation become more important in the later stages.     

Experimental studies on continuous hypothermic liver perfusion with a synthetic solution containing gelatin polypeptides (Haemaccel)

A rat liver model has been developed for studying preservation by continuous hypothermic perfusion. Perfusion for 5 and 24 hr with a defined solution containing Haemaccel as colloid at a temperature of 5–7 °C was found to result in good preservation of the metabolic activity of the livers as assessed by the ability of the tissue to synthesize urea and take up galactose. In common with other continuous perfusion methods, there was increasing evidence of cell damage as perfusion progressed, and there was an associated depletion of cellular K⁺ and an increase in tissue water content. There was a considerable increase in vascular resistance, as indicated by a fall in flow rate at a constant pressure in the later stages of perfusion, similar to that which has been reported in other liver preservation experiments using plasma derivatives or Dextran. Further studies are envisaged to attempt to analyze, in a controlled fashion, the nature of the damage incurred by the liver during storage and the requirements for maintenance of a viable graft at hypothermia.     

Effects of a cardiac peptide preparation on the myocardium in ischemia

Based on experimental studies the possibility of cordialin use in acute ischemia is being substantiated. On the first day of the animals' mortality and increased life duration of cells in ischemia zone, delaying the injury region expansion. But later in rats, that were given cordialin, slowing down of injury zone recovery and scar tissue formation was demonstrated. Cordialin use in early stages of myocardial infarction is suggested. In experiments on isolated heart cordialin is reported to decrease the intensity of processes of lipids' peroxide oxidation in intact and ischemic myocardium. But in reperfusion cordialin activates LPO, that is associated with heart contracting activity inhibition. The results of the study may serve as an experimental basis for cordialin use on the first day of MI development. Its further use needs the correction of its ability to slow down the processes of necrotic tissue recovery.     

Changes in Sphingomyelinase Activity,Tumor Necrosis Factor α Level,and Lipid Peroxidation Intensity in the Course of Development of Cholestatic Liver Injury

Changes in sphingomyelinase activity, tumor necrosis factor α expression, and level of lipid peroxidation products in the course of development of cholestatic liver injury have been studied. The same type phase shifts in the analyzed parameters were observed, which included a marked decrease at the early stages of cholestasis (days 3–6) and a pronounced increase at the later stages (days 12–16), i.e., under the conditions of developed pathology. There was a significant positive linear correlation between tumor necrosis factor α expression, sphingomyelinase activity, and lipid peroxidation intensity in cholestatic injury. We propose that detected changes may reflect the balance between the effects of the two major bile components—bilirubin, which is accumulated in the liver at the early stages of cholestasis, and bile acids, whose influence dominates at the later stages of pathologic process. Our results indicate that tumor necrosis factor α overexpression, sphingomyelin cycle activation, and lipid peroxidation intensification may cause apoptosis of hepatocytes at the late stages of cholestasis.     

Regenerative capability in the hindlimb of Xenopus laevis during ontogenetic development

The regenerative capacity of hindlimb of Xenopus laevis was investigated by amputating the limbs at four levels in various developmental stages including younger postmetamorphosed froglets. Amputations of limbs were performed at the base of limb in stages 50, 51, 52, 53, 54, 55, 58, and 60 (Nieuwkoop and Faber's table), at the middle of limb bud in stages 50, 51, 52 and 54, and at mid-thigh and mid-shank in stages 58 and 60, and the froglets in 2 and 3 cm in snout-vent length. In the present experiments the regenerative capacity of limbs was expressed by the rate of regeneration and morphogenesis. Tadpoles in the stages after 55 failed to regenerate when the limbs were amputated at base level, but individuals in all the other experimental series exhibited regeneration in various rates irrespective of the level of amputation and the stage. The regenerative capacity increased distally along the proximo-distal axis of the limb when amputated at the same stage, while regeneration was better in younger stages than that in older stages when amputations were made at the same levels. The regenerates obtained by amputation of limbs in stages between 50 and 54, were mainly digitated in that they had 5 toes with 3 claws which is the same pattern with the normal limb, 4 toes with 2 claws, 3 toes with 2 claws or one, and 2 toes with one claw etc. Tadpoles at stage 50 could regenerate toes and claws without defect, but in the later the regenerative capacity gradually declined by reducing the number of toes and claws and accompanied by malformation of skeleton as the stage proceeded. The tadpoles in stages after 58, and the froglets of 2 and 3 cm, produced various types of heteromorphic regenerates of shapes such as cone, spike or rod of which the centra were occupied with cartilage rods. However these regenerates showed no morphological differences according to the developmental stages. These heteromorphic regenerates continued their growth even after one year without any sign of development of digitated feet.     

Prolyl hydroxylase activity during newt forelimb regeneration

Prolyl hydroxylase activity was measured to obtain insight into changes in collagen metabolism during forelimb regeneration in the adult newt, Notophthalmus viridescens. Activity increased markedly during the redifferentiative stages, remained elevated during digit formation, and decreased as regeneration neared completion. The greatest activity, seen during early digit formation, represents a 20-fold increase in activity over the level seen in nonregenerating limbs. The profile of enzyme activity correlates with the rate of collagen synthesis and the soluble collagen content of the regenerating tissue. Enzyme extracted from limbs in the early stages of regeneration can be activated in vitro upon preincubation with cofactors; however, preincubation has little, if any, effect on enzyme extracted from limbs at the later digit-forming stages.     

Acute occlusion of an abdominal aortic aneurysm complicated by bilateral lower extremity venous thrombosis: A case report

Acute occlusion of an abdominal aortic aneurysm is a rare phenomenon. Its possible complications include distal spasm followed by arterial thrombosis, ischemia of the distal limbs, distal embolization, acidosis, hyperkalemia, and the development of venous thrombosis of the lower limbs. Surgical correction is often complicated by cardiac decompensation, renal failure, fatal pulmonary embolism, and metabolic derangements related to toxins released from the revascularized limb. Unless contraindicated, immediate systemic heparinization must be undertaken when the diagnosis is first suspected. We present a case of sudden occlusion of an abdominal aortic aneurysm complicated by venous thrombosis involving both lower extremities. After undergoing surgical revascularization, the patient sustained massive fatal pulmonary emboli. Prophylactic interruption of the inferior vena cava may be indicated in patients who present with this complication of abdominal aortic aneurysm.     

Nucleoside mono- and nucleoside diphosphate kinase activities in rat liver and brain in radiation sickness

Activity of nucleoside di- and nucleoside triphosphates metabolism enzymes in tissues of rats gamma-irradiated by a dose of 30 Gy was studied 0.5, 1, 3, 6 and 24 hours after the radiation effect. It is shown that the nucleoside monophosphate kinase activity of the liver and brain is enhanced almost at all stages of the studies and the nucleoside diphosphate kinase activity is inhibited. A significant but reversible decrease of the nucleoside monophosphate kinase activity is observed in the liver 3 h later. By an end of the first day after irradiation the nucleoside mono- and nucleoside diphosphate kinase activities increase significantly both in the liver and brain.     

Analysis of an equivalent electric circuit of the hepatocyte during stopping and restoration of the blood flow

An analysis of an electric scheme of hepatocyte under conditions of stopping and restoring the blood flow taking into account the morphological and biochemical characteristics of the normal and injured liver was carried out. It is shown that the fast phase of restoring the membrane potential (MP) when restoring the blood flow following ischemia is stipulated by restoring extracellular concentrations of potential-generating ions; and slow restoring of the normal liver MP is connected with the phase of potassium efflux hyperpolarization. The injured liver MP stability to ischemia is higher because of the transmembrane ion gradient decrease before ischemia and next effect of depolarisation of passive currents weakening under conditions of closed extracellular space, and total ATPase activity decrease, i.e. a more economical ATP expenditure by the cell at ischemia.     

Changes in muscle sympathetic nerve activity and calf blood flow during static handgrip exercise

To test the function of sympathetic vasco-constrictor nerves on blood flow in resting limbs during static muscle contraction, muscle sympathetic nerve activity (MSNA) to the leg muscle was recorded from the tibial nerve microneurographically before, during and after 2 min of static handgrip (SHG). Simultaneously, calf blood flow (CBF) was measured by strain gauge plethysmography. An increase in MSNA, a decrease in CBF and an increase in calf vascular resistance (CVR) in the same resting limb occurred concomitantly during SHG. However, the increase in CVR was blunted in the second minute of handgrip when MSNA was still increasing. The results indicated that the decrease of CBF during SHG reflects the increase in MSNA, while the dissociation between MSNA and CVR at the later period of SHG may be related to metabolic change produced by the vasoconstriction.     

膝部骨折合并腘动脉损伤23例临床分析

目的：回顾性分析膝部骨折合并腘动脉损伤的治疗方法和效果。方法：23例膝部骨折合并腘动脉损伤的患者,其中肢体严重缺血患者（远端动脉搏动消失,皮温下降,皮肤花斑或者苍白）13例,部分缺血患者（远端动脉搏动减弱,或者消失但有毛细血管充盈征）10例。腘动脉修复方法：端端吻合术4例,修补术5例,切开取栓术3例,对侧大隐静脉移植修复术10例。修复顺序：先修复血管再固定骨折8例,先固定骨折再修复血管14例,处理骨折前先建立临时性动脉内分流10例。结果：肢体存活19例,截肢4例。截肢者均为严重缺血患者,其中1例患者因严重骨折和广泛软组织损伤合并急性肾功能衰竭行I期截肢,3例患者因术后反复感染（1例合并肾功能不全）行Ⅱ期截肢。严重缺血的患者只有3/13例完全恢复,而部分缺血的患者有6/10例完全恢复。血管再通时间≥8h的患者只有4/13例完全恢复,而血管再通时间〈8h的患者有5/9完全恢复。结论：膝部骨折合并腘动脉损伤时,肢体缺血程度和缺血时间是影响患者康复的重要因素,术后感染仍是造成截肢的主要原因。     

Skeletal muscle vascular responses in human limbs to isometric handgrip

Studies of whole limb blood flow have shown that static handgrip elicits a vasodilatation in the resting forearm and vasoconstriction in the resting leg. We asked if these responses occur in the skeletal muscle vascular bed, and if so, what is the relative contribution of local metabolic versus other mechanisms to these vascular responses. Blood flow recordings were made simultaneously in the skeletal muscle of the resting arm and leg using the Xenon-washout method in ten subjects during 3 min of isometric handgrip at 30% of maximal voluntary contraction. In the arm, skeletal muscle vascular resistance (SMVR) decreased transiently at the onset of exercise followed by a return to baseline levels at the end of exercise. In the leg SMVR remained unchanged during the 1st min of handgrip, but had increased to exceed baseline levels by the end of exercise. During exercise electromyography (EMG) recordings from nonexercising limbs demonstrated a progressive 20-fold increase in activity in the arm, but remained at baseline in the leg. During EMG-signal modelled exercise performed to mimic the inadvertent muscle activity, decreases in forearm SMVR amounted to 57% of the decrease seen with controlateral handgrip. The present study would seem to indicate that vascular tone in nonexercising skeletal muscle in the arm and leg are controlled differently during the early stages of static handgrip. Metabolic vasodilatation due to involuntary contraction could significantly modulate forearm skeletal muscle vascular responses, but other factors, most likely neural vasodilator mechanisms, must make major contributions. During the later stages of contralateral sustained handgrip, vascular adjustments in resting forearm skeletal muscle would seem to be the final result of reflex sympathetic vasoconstrictor drive, local metabolic vasodilator forces and possibly neurogenic vasodilator mechanisms.     

牛磺酸对肢体缺血／再灌注后肝损伤大鼠TNF-α、NF-κB表达的影响

目的：探讨给予牛磺酸预处理对肢体缺血／再灌注（limb ischemia-reperfusion,H／R）后大鼠肝脏损伤及,INn、NF—KB表达的影响及意义。方法：采用Wistar大鼠建立LI/R损伤模型,随机分为4组（n=10）：对照（C）组,缺血／再灌注（I／R）组,牛磺酸（T）组和牛磺酸＋缺血／再灌注（TR）组。比色法测定动物血浆ALT、AST、MDA,肝组织MDA、MPO、DNA裂解率和钙含量,放免法检测血浆及肝组织TNF-α水平;HE染色观察肝脏组织形态改变;免疫组化法观察NF-κB蛋白表达。结果：与C组比较,I／R和TR组各损伤性指标、TNF-α水平均升高,NF-κB蛋白表达增高（P〈0．01）;但TR组上述各项指标较I／R组显著降低。结论：牛磺酸预处理可减轻大鼠LI／R所致肝脏损伤,降低TNF-α、NF-κB表达。     

The relationship between thalamocortical connections and stimulus-evoked metabolic activity in the ventroposterior nucleus of the monkey.

Although a highly organized system of reciprocal projections exists between the cerebral cortex and the thalamus, the relationship of the thalamocortical projections to functional activity remains unclear. This study attempts to identify the correlation between thalamic relay cells and functional activity evoked in the ventroposterior nucleus (VP) of cynomolgus and squirrel monkeys. Wheatgerm agglutinin conjugated to horseradish peroxidase (WGA:HRP) was iontophoretically injected into physiologically determined sites in the somatosensory cortex, resulting in retrogradely labeled cells and anterogradely labeled terminals in corresponding somatosensory thalamic regions. In the same animals, 2-deoxyglucose (2DG) experiments were carried out 2 days later, using the somatic stimuli identified as best exciting the cortical neurons. Stimulation to the limbs produced crescent-shaped clusters of metabolic label arranged in a somatotopically organized fashion in the ventral posterior lateral nucleus (VPL). Following WGA:HRP injections into area 3b, the stimulus-evoked 2DG label was colocalized with the retrograde and anterograde tracer. This finding suggests that the location of stimulus-evoked metabolic activity can be predicted by the presence of transported WGA:HRP clusters.     

吸入一氧化碳防治肢体缺血／再灌注所致肝脏损伤的实验研究

目的：观察吸入外源性一氧化碳（CO）对肢体缺血／再灌注（I／R）所致肝脏损伤的防治作用。方法：健康SD大鼠100只,随机分为假手术（S）、假手术吸入CO（SC）、I／R、I／R吸入CO（RC）组。通过夹闭股动脉4h、再开放6—72h、10d复制肢体L／R致肝脏损伤模型。S、I／R组吸入普通医用空气,SC、RC组吸入含CO（体积分数为0．05％）的医用空气。光镜观察肝组织病理学变化,全自动生化分析仪检测血谷丙转氨酶（GPT）,流式细胞仪检测肝细胞凋亡百分比及bax、bcl-2的表达水平。结果：S组与SC组比较,各项观察指标无显著差别;与SC组比较,I/R及RC组肝组织呈病理改变,血清GPT及肝细胞凋亡百分比明显升高;I／R组肝细胞bax蛋白的表达水平明显升高。和L／R组相比。RC组肝组织损伤程度减轻,血清GPT、肝细胞凋亡百分比及bax蛋白的表达水平明显降低,而肝细胞bcl-2蛋白的表达水平显著升高。结论：吸入适量外源性CO对肢体I／R所致肝脏损伤有防治效应。