深低温停循环下幼猪脑皮质HIF-1与NGB的表达及作用

目的:观察深低温停循环(DHCA)下幼猪脑皮质缺氧诱导因子1(HIF-1)与神经珠蛋白(NGB)的表达变化。方法:五指山猪共15头随机分成体外循环组(CPB组)、深低温停循环组(DHCA组)与深低温停循环选择性顺行脑灌注组(SACP组)。建立体外循环后,DHCA组降温至18℃后停循环40 min,SACP组停循环后经无名动脉顺行脑灌注40 min。复灌180 min后取脑皮质组织行HE染色镜检,Western blot及real-time PCR检测HIF-1α、NGB蛋白表达及mRNA水平。结果:HE染色显示与DHCA组相比SACP组脑组织损伤显著减轻。复灌180min后DHCA组及SACP组脑皮质中HIF-1α的蛋白及mRNA水平均显著高于CPB组(P0.05),同时SACP组动物脑组织HIF-1α的蛋白及mRNA水平显著高于DHCA组(P0.05)。复灌180 min后DHCA组及SACP组脑皮质中NGB的蛋白及mRNA水平均显著高于CPB组(P0.05),同时SACP组动物脑组织NGB的蛋白及mRNA水平显著高于DHCA组(P0.05)。结论:HIF-1与NGB的表达上调参与了脑组织对DHCA脑损伤的反应机制,并可能是SACP脑保护作用的机制之一。     

Dietary selenium affects intestinal development of Eimeria papillata in mice

Here, we investigated the effect of the trace element selenium (Se) on course and outcome of Eimeria-paplllata-induced coccidiosis in mice. Male mice were fed on Se-adequate (0.15 ppm), Se-deficient, and Se-high diets (1.0 ppm) for 6 weeks. Mice were orally infected with 1,000 oocysts. The prepatent period lasts for 3 days, but the course of infections varied. At Se-adequate diet, the maximum fecal output of oocysts amounted to 68,300 ooccysts/g feces on day 5 p.i.. However, fecal shedding of oocysts was accelerated in mice on Se-deficient diet and occurred already on day 4 p.i.. By contrast, maximal shedding is impaired in mice on high-Se diet, which takes place on day 5 p.i., but with a decreased output of only 7,300 oocysts/g feces. Light microscopy reveals that all developmental stages are affected: meronts, micro- and macrogamonts, and developing oocysts are increased in comparison with mice fed on selenium-adequate diet. At high Se, the number of parasitic stages in the jejunum is substantially higher than at Se-deficient diet. Se does not affect the number of jejunal Alcian blue-stained goblet cells. Se deficiency increased the number of apoptotic cells in the jejunum. Substantially increased histological injury scores reveal more injuries in jejunum tissue infected by E. papillata. Our data indicate that high dietary Se exerts potential anticoccidial activity. This may be taken advantage of in control measures towards Eimeriosis as a feed additive, potentially alleviating the need for concomitantly utilized anti-coccidial drugs in the feed.     

Changes in arterial blood PO2, PCO2, and pH during deep hypothermic circulatory arrest in adults.

Safe limits of time and temperature during sleep hypothermic circulatory arrest (DHCA) still remain controversial. Furthermore, continuous changes of PaO2, PaCO2, and pH have never been measured during DHCA in humans. Continuous intraarterial blood gas (CIABG) monitoring is a new technology allowing us to study chronological changes occurring due to metabolism during DHCA. When the patients'' temperature reached 18 approximately 20 degrees C following establishment of cardiopulmonary bypass (CPB), circulatory arrest was initiated. After a 20-minute period of DHCA, reperfusion commenced with 18 degree C blood. We continuously monitored PaO2, PaCO2, and pH immediately before, during and following DHCA. Data was analyzed by Student''s t-test. PaO2, PaCO2, and pH of pre- and 5 minutes post DHCA were not significantly different from each other. However, during DHCA, the PaO2 was significantly decreased from 229 +/- 34 to 30 +/- 23 mmHg at 20-minute intervals. But the PaCO2 increased significantly after 20 minutes of circulatory arrest from 34 +/- 5 to 42 +/- 6 mmHg. However, the pH did not change significantly over the 20-minute period. The PaO2 level after 20 minutes is much lower than before DHCA, it would be well tolerated in normothermic adults. The PO2 level in the brain may be even lower given its high metabolic rate. So measuring arterial PO2 continuously during DHCA may provide a surrogate method for determining maximum safe time under DHCA for adults.     

Protective Effects of Acupuncture in Cardiopulmonary Bypass-Induced Lung Injury in Rats

Acute lung injury caused by cardiopulmonary bypass (CPB) increases the mortality after cardiac surgery. Our previous clinical study suggested that electroacupuncture (EAc) has a protective effect during CPB, but the mechanism was unclear. So, we design this study to investigate the effects of EAc on CPB-induced lung injury and the underlying mechanism. Male Sprague Dawley rats were randomly divided into control, CPB, and CPB + EAc groups. A lung injury model was created by CPB surgery to serve as the CPB group, and EAc (2/100 Hz) was used before CPB in the CPB + EAc group. Lung tissue was collected at 0.5, 1, and 2 h after CPB. Pulmonary malondialdehyde (MDA) concentrations as well as superoxide dismutase (SOD), myeloperoxidase (MPO), and caspase-3 activity were determined. c-Jun N-terminal kinase (JNK), ERK, p38 and cleaved caspase 3 in the lung were analyzed by western blotting. A549 cells were treated by rat serum from the CPB and CPB + EAc groups, and cleaved caspase-3 activity was detected by fluorescent immunohistochemistry. CPB significantly increased the MPO activity, MDA content, apoptosis, caspase-3 activity, and phosphorylated p38 but decreased SOD activity compared with the control group. EAc significantly increased SOD activity at 0.5 and 2 h (p < 0.01 vs CPB) and reduced CPB-induced histological changes, MPO activity at 1 and 2 h (p < 0.05 vs CPB), MDA content at 2 h (p < 0.05 vs CPB), caspase-3 activity at 1 h (p < 0.05 vs CPB), and phosphorylated p38 and JNK at 0.5 h after CPB. The serum from the CPB group increased more positive staining cells of cleaved caspase-3 than that from the CPB + EAc group. EAc reversed the CPB-induced lung inflammation, oxidative damage, and apoptosis; the mechanism may involve decreased phosphorylation of p38 along with caspase-3 activity and activation.     

Hyperoxia management during deep hypothermia for cerebral protection in circulatory arrest rabbit model

As a brain protection strategy, antegrade selective cerebral perfusion (ASCP) is widely used in thoracic aorta surgery with deep hypothermic circulatory arrest (DHCA), yet the oxygen management for ASCP has never been standardized. The aim of this study was to investigate the possible neuroprotective effects of hyperoxia management during deep hyperthermia for ASCP combined with DHCA in a rabbit model. Rabbits were assigned into four groups: sham group, without cardiopulmonary bypass (CPB); DHCA group, DHCA for 80 minutes; ASCP group, ASCP combined with DHCA; and SH group, hyperoxia management combined with ASCP and DHCA. Hyperoxia management was performed when the nasopharyngeal temperature was below 22°C. Deep hypothermic circulatory arrest was initiated when nasopharyngeal temperature reached 16-18°C. Blood samples were withdrawn to determine blood gas indexes and neurobiochemical markers of damage, and brain tissues were stored for biochemical analysis. Cerebral oxygen balance was performed better in the SH group compared with the DHCA group and the ASCP group. Hyperoxia management did not increase lipid peroxidation with lower malondialdehyde levels in the SH group compared with the DHCA group and the ASCP group (p < 0.05). S100 calcium binding protein B in the SH group was lower compared with the DHCA group and the ASCP group (p < 0.05). There was no significant difference of neuron-specific enolase in the SH group compared with the sham group. Hyperoxia management during deep hypothermia provided substantial dissolved oxygen and demonstrated better cerebral protection over normoxia management.     

Modulation of Immunologic Response by Preventive Everolimus Application in a Rat CPB Model

Everolimus (EVL) is widely used in solid organ transplantation. It is known to have antiproliferative and immunosuppressive abilities via inhibition of the mTOR pathway. Preventive EVL administration may lower inflammation induced by cardiopulmonary bypass (CPB) and reduce systemic inflammatory response syndrome (SIRS). After oral loading with EVL 2.5 mg/kg/day (n?=?11) or placebo (n?=?11) for seven consecutive days, male Wistar rats (400–500 g) were connected to a miniaturised heart-lung-machine performing a deep hypothermic circulatory arrest protocol. White blood cells (WBC) were significantly reduced in EVL-pretreated animals before start of CPB with a preserved reduction by trend at all other time points. Ischemia/reperfusion led to decreased glucose levels. Application of EVL significantly increased glucose levels after reperfusion. In addition, potassium levels were significantly lower in EVL-treated animals at the end of reperfusion. Immunoblotting revealed increased S6 levels after CPB. EVL decreased phosphorylation of S6 in the heart and kidney, which indicates an inhibition of mTOR pathway. Moreover, EVL significantly modified phosphorylation of AKT, while decreasing IL2, IL6, RANTES, and TNFα (n?=?6). Preventive application of EVL may modulate inflammation by inhibition of mammalian target of rapamycin (mTOR) pathway and reduction of proinflammatory cytokines. This may be beneficial to evade SIRS-related morbidities after CPB.     

Proton magnetic resonance spectroscopy assessment of neonatal brain metabolism during cardiopulmonary bypass surgery

Here, we report on the development and performance of a robust 3-T single-voxel proton magnetic resonance spectroscopy (¹H MRS) experimental protocol and data analysis pipeline for quantifying brain metabolism during cardiopulmonary bypass (CPB) surgery in a neonatal porcine model, with the overall goal of elucidating primary mechanisms of brain injury associated with these procedures. The specific aims were to assess which metabolic processes can be reliably interrogated by ¹H MRS on a 3-T clinical scanner and to provide an initial assessment of brain metabolism during deep hypothermia cardiac arrest (DHCA) surgery and recovery. Fourteen neonatal pigs underwent CPB surgery while placed in a 3-T MRI scanner for 18, 28, and 37°C DHCA studies under hyperglycemic, euglycemic, and hypoglycemic conditions. Total imaging times, including baseline measurements, circulatory arrest (CA), and recovery averaged 3 h/animal, during which 30–40 single-voxel ¹H MRS spectra (sLASER pulse sequence, TR/TE = 2000/30 ms, 64 or 128 averages) were acquired from a 2.2-cc right midbrain voxel. ¹H MRS at 3 T was able to reliably quantify (1) anaerobic metabolism via depletion of brain glucose and the associated build-up of lactate during CA, (2) phosphocreatine (PCr) to creatine (Cr) conversion during CA and subsequent recovery upon reperfusion, (3) a robust increase in the glutamine-to-glutamate (Gln/Glu) ratio during the post-CA recovery period, and (4) a broadening of the water peak during CA. In vivo ¹H MRS at 3 T can reliably quantify subtle metabolic brain changes previously deemed challenging to interrogate, including brain glucose concentrations even under hypoglycemic conditions, ATP usage via the conversion of PCr to Cr, and differential changes in Glu and Gln. Observed metabolic changes during CPB surgery of a neonatal porcine model provide new insights into possible mechanisms for prevention of neuronal injury.     

Precise quantification of pulsatility is a necessity for direct comparisons of six different pediatric heart-lung machines in a neonatal CPB model

Generation of pulsatile flow depends on an energy gradient. Surplus hemodynamic energy (SHE) is the extra hemodynamic energy generated by a pulsatile device when the adequate pulsatility is achieved. The objective of this study was to precisely quantify and compare pressure-flow waveforms in terms of surplus hemodynamic energy levels of six different pediatric heart-lung machines in a neonatal piglet model during cardiopulmonary bypass (CPB) procedures with deep hypothermic circulatory arrest (DHCA). Thirty-nine piglets (average weight, 3 kg) were subjected to CPB with a hydraulically driven physiologic pulsatile pump (PPP; n=7), Jostra-HL 20 pulsatile roller pump (Jostra-PR; n=6), Stockert Sill pulsatile roller pump (SIII-PR; n=6), Stockert Sill mast-mounted pulsatile roller pump with a miniature roller head (Mast-PR; n=7), Stockert Sill mast-mounted nonpulsatile roller pump (Mast-NP; n=7), or Stockert CAPS nonpulsatile roller pump (CAPS-NP, n=7). Once CPB was begun, each animal underwent 20 minutes of hypothermia, 60 minutes of DHCA, 10 minutes of cold reperfusion, and 40 minutes of rewarming. The pump flow rate was maintained at 150 ml x kg(-1) x min(-1) and the mean arterial pressure (MAP) at 45 mm Hg. In the pulsatile experiments, the pump rate was kept at 150 bpm and the stroke volume at 1 ml/kg. The SHE (ergs/cm3) = 1,332 ([(integral fpdt) / (integral fdt)] - MAP) was calculated at each experimental stage. During normothermic CPB (15 minutes on pump), the physiologic pulsatile pump generated the highest surplus hemodynamic energy (8563 +/- 1918 ergs/cm3, p < 0.001) compared with all other pumps. The Jostra HL-20 and Stockert Sill pulsatile roller pumps also produced adequate surplus hemodynamic energy. Nonpulsatile roller pumps and the Stockert Sill mast-mounted pulsatile roller pump did not generate any extra hemodynamic energy. During hypothermic CPB and after DHCA and rewarming, the results were extremely similar to those seen during normothermic CPB. The surplus hemodynamic energy formula is a novel method to precisely quantify different levels of pulsatility and nonpulsatility for direct and meaningful comparisons. The PPP produced the greatest surplus hemodynamic energy. Most of the pediatric pulsatile pumps (except Mast-PR) generated significant surplus hemodynamic energy. None of the nonpulsatile roller pumps generated adequate surplus hemodynamic energy.     

Benign human enterovirus becomes virulent in selenium-deficient mice

Coxsackieviruses have been implicated as possible co-factors in the etiology of the selenium (Se)-responsive cardiomyopathy known as Keshan disease. Here we report that a cloned and sequenced amyocarditic coxsackievirus B3 (CVB3/0), which causes no pathology in the hearts of Se-adequate mice, induces extensive cardiac pathology in Se-deficient mice. CVB3/0 recovered from the hearts of Se-deficient mice inoculated into Se-adequate mice induced significant heart damage, suggesting mutation of the virus to a virulent genotype. We demonstrate the important role of host nutritional status in determining the severity of a viral infection. © 1994 Wiley-Liss, Inc.     

Serum UCH-L1 as a Novel Biomarker to Predict Neuronal Apoptosis Following Deep Hypothermic Circulatory Arrest

Background: Deep hypothermic circulatory arrest (DHCA) has been used in cardiac surgery involving infant complex congenital heart disease and aortic dissection. DHCA carries a risk of neuronal apoptotic death in brain. Serum ubiquitin C-terminal hydrolase L1 (UCH-L1) level is elevated in a number of neurological diseases involving neuron injury and death. We studied the hypothesis that UCH-L1 may be a potential biomarker for DHCA-induced ischemic neuronal apoptosis.Methods: Anesthetized piglets were used to perform cardiopulmonary bypass (CPB). DHCA was induced for 1 hour followed by CPB rewarming. Blood samples were collected and serum UCH-L1 levels were measured. Neuron apoptosis and Bax and Bcl-2 proteins in hippocampus were examined. The relationship between neuron apoptosis and UCH-L1 level was determined by receiver operating characteristics (ROC) curves and correlation analysis.Results: DHCA resulted in marked neuronal apoptosis, significant increase in Bax:Bcl-2 ratio in hippocampus and UCH-L1 level elevations in serum (all P<0.05). Positive correlation was obtained between serum UCH-L1 level and the severity of neuron apoptosis (r= 0.78, P<0.01). By ROC, the area under the curve were 0.88 (95% CI: 0.74-0.99; P<0.01), 0.81 (95% CI: 0.81-0.96; P<0.05), 0.71 (95% CI: 0.47-0.92; P=0.11) for UCH-L1, Bax/Bcl-2 ratio and Bax, respectively. Using a cut-off point of 0.25, the UCH-L1 predicted neuronal apoptosis with a sensitivity of 85% and specificity of 57%.Conclusion: Serum UCH-L1, as an easy and quick measurable biomarker, can predict neural apoptosis induced by DHCA. The elevation in UCH-L1 concentration is consistent with the severity of neural apoptosis following DHCA.     

Effects of methionine on selenium embryotoxicity in cultured rat embryos

Effects of methionine, an essential amino acid, on the embryotoxicity of selenium (Se) were examined using the rat embryo culture. Rat embryos at day 9.5 of gestation were cultured for 48 h in the presence of sodium selenite at 10 and 20 microM or sodium selenate at 30 and 100 microM with or without the addition of 1 mM DL-methionine. Selenite at 20 microM or selenate at 100 microM alone increased the incidence of embryonic malformation and inhibited the embryonic growth. The addition of methionine increased the incidence of embryonic malformation at 10 microM of selenite but decreased the incidence of embryonic malformation at 100 microM of selenate. On the other hand, the addition of methionine partially restored the inhibited embryonic growth at 20 microM of selenite or at 100 microM of selenate. It was considered from these results that the methionine availability in the embryonic environment and the oxidation state of Se are critical in Se embryotoxicity.     

Selenium Status Alters the Immune Response and Expulsion of Adult Heligmosomoides bakeri Worms in Mice

Heligmosomoides bakeri is a nematode with parasitic development exclusively in the small intestine of infected mice that induces a potent STAT6-dependent Th2 immune response. We previously demonstrated that host protective expulsion of adult H. bakeri worms from a challenge infection was delayed in selenium (Se)-deficient mice. In order to explore mechanisms associated with the delayed expulsion, 3-week-old female BALB/c mice were placed on a torula yeast-based diet with or without 0.2 ppm Se, and after 5 weeks, they were inoculated with H. bakeri infective third-stage larvae (L3s). Two weeks after inoculation, the mice were treated with an anthelmintic and then rested, reinoculated with L3s, and evaluated at various times after reinoculation. Analysis of gene expression in parasite-induced cysts and surrounding tissue isolated from the intestine of infected mice showed that the local-tissue Th2 response was decreased in Se-deficient mice compared to that in Se-adequate mice. In addition, adult worms recovered from Se-deficient mice had higher ATP levels than worms from Se-adequate mice, indicating greater metabolic activity in the face of a suboptimal Se-dependent local immune response. Notably, the process of worm expulsion was restored within 2 to 4 days after feeding a Se-adequate diet to Se-deficient mice. Expulsion was associated with an increased local expression of Th2-associated genes in the small intestine, intestinal glutathione peroxidase activity, secreted Relm-β protein, anti-H. bakeri IgG1 production, and reduced worm fecundity and ATP-dependent metabolic activity.     

Application of modified perfusion technique on one stage repair of interrupted aortic arch in infants: a case series and literature review

One stage repair of interrupted aortic arch (IAA) associated with cardiac anomalies in neonates and infants is challenging for the entire surgical team. Deep hypothermic circulatory arrest (DHCA) prolongs myocardial and cerebral ischemia and may induce heart, brain, and major organ dysfunction. From May 2004 to May 2006, 13 infants with IAA underwent one stage repair by median sternotomy under DHCA with continuous regional cerebral perfusion (RCP) in Fuwai Children's Heart Center. Median age at operation was 10.4 +/- 6.7 months, and mean body weight was 6.58 +/- 2.15 kg. Temperature of nasopharynx was decreased to 18 degrees C-20 degrees C; rectal temperature was controlled at 19 degrees C-22 degrees C. Flow rate of RCP was maintained with 20-25 ml x kg x min under DHCA combined with RCP. Mean artery pressure (MAP) measuring from right radial artery was 32.5 +/- 5.8 mm Hg, and MAP from femoral artery was 11.2 +/- 3.5 mm Hg. Mean cardiopulmonary bypass (CPB) time was 141.6 +/- 21.7 min, and mean aortic clamp time was 52.3 +/- 10.9 min. Mean duration of RCP was 31.5 +/- 12.4 min. Mean intubation time in intensive care unit (ICU) was 54.7 +/- 12.6 hours, and mean ICU stay was 67.9 +/- 28.4 hours. This report describes our CPB protocol under DHCA using continuous RCP in low weight pediatric patients to minimize neurological complications during one stage IAA repair and summarizes the various CPB managements in recent literature as well.     

Effects of glutathione depletion on selenite- and selenate-induced embryotoxicity in cultured rat embryos.

Effects of depletion of reduced glutathione (GSH) on selenium (Se) embryotoxicity in cultured rat embryos were examined. Rat embryos at day 9.5 of gestation were cultured for 48 h in the presence of Se as either sodium selenite at 10 and 20 microM or sodium selenate at 30 and 100 microM. Embryonic GSH was depleted by the addition of 0.1 mM of L-buthionine-[S,R]-sulfoximine (BSO) without embryotoxicity, i.e., significant growth retardation and malformation of the embryos. Selenite at 10 microM or selenate at 100 microM significantly increased the incidence of malformation of the embryos. The incidence of selenite-induced malformation of the embryos at 20 microM was significantly decreased with BSO. On the contrary, the incidence of selenate-induced malformation at 30 microM was significantly increased with BSO. It was noted that the major malformed regions of the embryos by the embryotoxic concentration of BSO alone were the same to those affected by selenite or selenate. It was considered from these results that embryonic GSH was involved in the embryotoxicity of selenite and selenate. The embryotoxicity of selenate may not be mediated through the reduction to selenite. It was suggested that the formation of selenodiglutathione and the oxidative stress were involved in the embryotoxicity of selenite and selenate, respectively.     

Rationale for the treatment of cancer with sodium selenite

Epidemiological studies conducted during several decades of the last century have demonstrated the importance of sufficient nutritional supply of selenium (Se) for human health. More importantly, low blood Se levels were found to be associated with an increased incidence and mortality from various types of cancers. Recently, attention of researchers was drawn to the relationship between free radical generation, known otherwise as oxidative stress, and carcinogenesis. It was therefore thought that antioxidants should be beneficial for prevention and inhibition of different malignancies. However, there appeared to be a paradox, because tumor growth is associated with tissue hypoxia that is accompanied by the formation of reductive rather than oxidative free radicals. Various organic and inorganic Se compounds, generally considered to be antioxidants, produced mixed results when tested in animal models and human subjects. Amongst them, sodium selenite has been shown to be the most effective in an in vitro and in vivo carcinogenesis studies. As recently demonstrated, selenite is not an antioxidant, but possesses oxidizing properties in the presence of specific substrates. Thus selenite is capable of oxidizing polythiols to corresponding disulfides, but does not react with monothiols. Such polythiols associated with cancer membrane-bound proteins appear under the reducing conditions of hypoxic tumor tissue. These thiol groups can, in turn, initiate a disulfide exchange reaction with plasma proteins, predominantly with fibrinogen, to form an insoluble and protease-resistant fibrin-like polymer. As the result, tumor cells become surrounded by a coat which masks specific tumor antigens thus allowing cancer cells to escape immune recognition and elimination by natural killer (NK) cells. Selenite by virtue of oxidizing cell membrane thiols, can prevent the formation of the coat and consequently makes cancer cells vulnerable to the immune surveillance and destruction. In addition, selenite may directly activate NK cells, as well as inhibit angiogenesis without undesirable decrease in the oxidative potential of cellular environment. It is, therefore, postulated that sodium selenite, in view of its relative low toxicity, might become a drug of choice for many types of cancer including leukemia.     

Platelet-rich plasma stimulates human dermal fibroblast proliferation via a Ras-dependent extracellular signal-regulated kinase 1/2 pathway

Platelet-rich plasma (PRP) contains a high concentration of several growth factors and contributes to soft-tissue engineering and wound healing. However, the effect of PRP on human dermal fibroblast proliferation and responses is unknown. This was investigated in the present study using PRP prepared from the whole human blood using the double-spin method. Human dermal fibroblast cultures were established from skin samples collected during plastic surgery. Platelet concentration and growth factor levels in PRP were estimated, and a cell proliferation assay was carried out after PRP treatment. The role of Ras-dependent extracellular signal-regulated kinase (ERK)1/2 in the effects of PRP was investigated in human dermal fibroblasts by suppressing ERK1/2 expression with an inhibitor or by short interfering (si)RNA-mediated knockdown, and assessing ERK1/2 phosphorylation by western blotting as well as proliferation in PRP-treated cells. We found that PRP stimulated human dermal fibroblast proliferation, which was suppressed by ERK1/2 inhibitor treatment (P < 0.01). ERK1/2 phosphorylation was increased in the presence of PRP, while siRNA-mediated knockdown of ERK1/2 blocked cell proliferation normally induced by PRP treatment (P < 0.01). These results demonstrate that PRP induces human dermal fibroblast proliferation via activation of ERK1/2 signaling. Our findings provide a basis for the development of agents that can promote wound healing and can be applied to soft-tissue engineering.     

Cerebral oxygen saturation and electrical brain activity before,during, and up to 36 hours after arterial switch procedure in neonates without pre-existing brain damage: its relationship to neurodevelopmental outcome

Objective: To monitor the pattern of cerebral oxygen saturation (rSat), by use of NIRS, in term infants before, during and after the arterial switch operation and to evaluate its relation to neurodevelopmental outcome. Methods: In 20 neonates without pre-existing brain damage hemodynamics and arterial oxygen saturation (AO₂-Sat) were monitored simultaneously with rSat and amplitude-integrated EEG (aEEG) from 4 h to 12 h before up to 36 h after cardiopulmonary bypass (CPB) and short duration of cardiac arrest during deep hypothermia (DHCA). The Bayleys developmental scale was performed at 30 months. Results: Before surgery rSat was <50% in 16 patients. During CPB rSat increased to normal values, with a sharp decrease during brief CA (median 6.5 min). Post-CPB rSat showed a transient decrease (30–45%) despite normal PaO₂ with sustained normalization after 6–26 h. Recovery time of the rSat seemed longer when pre-operative rSat was below 35%, and for lower minimum nasopharyngeal temperature and longer duration of CPB and of DHCA. Recovery time of the aEEG varied and did not correlate with normalization of rSat. Neurodevelopmental outcome was normal in all but two patients. Patients with lower pre-operative rSat (<35%) tended to have lower DQ (developmental quotient) scores at 30–36 months. (median: mental 102 and motor 101 (range 58–125) compared with mental 100 and motor 110 (range 83–125)) Conclusion: Despite prompt normalization of circulation and oxygenation after surgery, recovery of rSat of the brain took 6–26 h, probably because of higher energy demand after CPB. Pre-operative cerebral oxygenation may be underestimated as a possible cause of adverse post-operative outcome.     

Combined enzyme histochemical and ultrastructural study on cryostat sections of pig heart to detect early reperfusion damage after ischaemia

In cardiac surgery, recognition of peroperative myocardial infarction may improve patient selection for prolonged circulatory support. The value of enzyme histochemistry to discriminate between reversible and irreversible myocardial damage at short periods of reperfusion was studied in an in vivo model of regional ischaemia in pig hearts. The left anterior descending coronary artery (LADCA) was clamped for 45 min followed by 2 h reperfusion (group 1, n=3). Post-mortem heart tissue showed markedly decreased activities of lactate dehydrogenase (LDH) and beta-hydroxybutyrate dehydrogenase (BDH) as demonstrated in cryostat sections, accompanied by massive leakage of LDH in the venous effluent. The depleted areas showed irreversible cell damage based on the presence of flocculent densities in mitochondria. In group 2 (n=6), LADCA flow was reduced to 40 per cent of the base-line value followed by 2 h reperfusion. Heart tissue showed normal LDH and BDH activities, except for some cells surrounding blood vessels, which activity was minimally decreased. Flocculent densities in mitochondria were never observed. We conclude that enzyme histochemistry of LDH and BDH activity on cryostat sections is a useful tool for detecting irreversible myocardial cell damage as early as 2 h reperfusion after ischaemia of the pig heart. The technique has potential applications in the detection of peroperative infarction in human biopsies.     

Inhibitory effect of ketamine on phosphorylation of the extracellular signal-regulated kinase1/2 following brain ischemia and reperfusion in rats with hyperglycemia

To determine if the inhibitory effects of ketamine on the extracellular signal-regulated kinase (ERK) 1/2 are involved in reduction of the hyperglycemia-exaggerated cerebral ischemic lesion, rats with normoglycemia, hyperglycemia, or hyperglycemia supplemented with ketamine were subjected to 15 min of forebrain ischemia, and then, reperfusion for 0.5, 1, and 3h. Phosphorylation of ERK1/2 in the brain tissues was assessed by immunohistochemistry and Western blot analysis. In rats with normoglycemia, we demonstrated a moderate increase of the ERK1/2 phosphorylation in the cingulum cortex and hippocampus CA3 following an ischemic intervention. It quickly dropped to control levels after reperfusion for 0.5h. In rats with hyperglycemia, however, the increase of the ERK1/2 phosphorylation in these areas was significantly higher in all animals reperfused. The neuronal death, detected by the TdT-mediated-dUTP nick end labeling assays, was found in the cingulum cortex (5.23+/-2.34, per high power feild) and hippocampus CA3 areas (6.29+/-3.68, per 1mm(2)) in hyperglycemic group after reperfusion for 3h. With ketamine treatment, the ERK1/2 phosphorylation in cingulum cortex and hippocampus CA1 and CA3 areas was found to be the same as that in normoglycemia rats. Our results suggest that hyperglycemia may increase the ischemic insult through modulation of the signal transduction pathways involving ERK1/2. The inhibitory effects of ketamine on the hyperglycemia-activated ERK1/2 phosphorylation are probably through inhibition of the N-methyl d-aspartate-mediated calcium influx, which subsequently reduce the hyperglycemia-exaggerated cerebral damage.