The Comparative Analysis between Surgical Thrombectomy and Hybrid Treatment in Salvage Operation / 대한혈관외과학회지

PURPOSE: Salvage operation is performed to improve the functional deficit of vascular access. This study is planned to evaluate the utility of the hybrid surgery through a comparative analysis between the results of surgical thrombectomy and those of hybrid surgery, combining surgical methods and endovascular treatments. METHODS: From January 2007 to December 2008, surgical thrombectomy had been done to 55 patients, whereas hybrid surgery had been done to 111 patients from January 2009 to December 2011. We have done a comparative analysis on the patency rate after the salvage operation for each group, retrospectively. Medical records were reviewed for patient information and radiographic data was used for checking the stenosis site in the hybrid surgery group. RESULTS: There were no statistically significant differences between the two groups, including age, gender, diabetes status, hypertension, and vascular access site or type. The primary patency rate was significantly higher in arteriovenous fistulas (65%) compared with arteriovenous grafts group (55%), at 12 months (P<0.01). At one year after the salvage operation, the secondary patency rate was higher in the hybrid surgery group compared to the surgical thrombectomy group (43.8% vs. 23.7%, P<0.01). CONCLUSION: This study shows that hybrid surgery combining surgical methods and endovascular treatments can be more useful for the salvaging of thrombosed vascular access than performing only surgical thrombectomy.

Periventricular leukomalacia induced by in utero clamping of pregnant rat aorta in fetal rats / 소아과

PURPOSE: This study was undertaken to develop an animal model of periventricular leukomalacia (PVL) induced by in utero clamping of pregnant rat aorta in fetal rats. METHODS: A timed pregnanct Sprague-Dawley rat on embryonic day 21 just prior to delivery was sedated and anesthetized, and a Harvard ventilator for small animals was applied. Following laparotomy, the maternal aorta was clamped reversibly for 40 minutes using a surgical clip. The fetal rats were then delivered by Cesarean section, resuscitated if necessary, and reared by a surrogate mother rat until postnatal day 21 to obtain the brain specimen. After systemic perfusion and fixation, 10 microm thick serial brain sections were obtained and stained for pathologic examination and assessment of ventriculomegaly. Ventriculomegaly was assessed by the measured ventricle to total brain volume ratio. RESULTS: Eight out of eleven fetal rats (73%) survived in the ischemia group after induction of in utero ischemia by clamping maternal rat aorta, and all ten survived in the control group. Body and brain weights measured at postnatal day 21 were significantly lower in the ischemia group compared to the control group. In pathologic findings, significant ventriculomagaly (3.67+/-1.21% vs. 0.23+/-0.06%) was observed in the ischemia group compared to the control group; although cystic lesion was not observed, mild (n=6) and moderate (n=2) rerefaction of the brain tissue was observed. CONCLUSION: A fetal rat model of PVL induced by in utero clamping of pregnant rat aorta was developed.

Bioluminescence Imaging of Chondrocytes in Rabbits by Intraarticular Injection of D-Luciferin / 핵의학분자영상

PURPOSE: Luciferase is one of the most commonly used reporter enzymes in the field of in vivo optical imaging. D-luciferin, the substrate for firefly luciferase has very high cost that allows this kind of experiment limited to small animals such as mice and rats. In this current study, we validated local injection of D-luciferin in the articular capsule for bioluminescence imaging in rabbits. MATERIALS AND METHODS: Chondrocytes were cultured and infected by replication-defective adenoviral vector encoding firefly luciferase (Fluc). Chondrocytes expressing Fluc were injected or implanted in the left knee joint. The rabbits underwent optical imaging studies after local injection of D-luciferin at 1, 5, 7, 9 days after cellular administration. We sought whether optimal imaging signals was could be by a cooled CCD camera after local injection of D-luciferin. RESULTS: Imaging signal was not observed from the left knee joint after intraperitoneal injection of D-luciferin (15 mg/kg), whereas it was observed after intraarticular injection. Photon intensity from the left knee joint of rabbits was compared between cell injected and implanted groups after intraarticular injection of D-luciferin. During the period of imaging studies, photon intensity of the cell implanted group was 5-10 times higher than that of the cell injected group. CONCLUSION: We successfully imaged chondrocytes expressing Fluc after intraarticular injection of D-luciferin. This technique may be further applied to develop new drugs for knee joint disease.

Pretreatment with N-nitro-L-arginine Methyl Ester Improved Oxygenation After Inhalation of Nitric Oxide in Newborn Piglets with Escherichia coli Pneumonia and Sepsis

We evaluated the effects of a combined therapy of pre-blockade endogenous nitric oxide synthase (NOS) with N-nitro-L-arginine methyl ester (L-NAME) and continuous inhaled NO (iNO) on the gas exchange and hemodynamics of Escherichia coli pneumonia and sepsis in newborn piglets. Seven to ten day old ventilated newborn piglets were randomized into 5 groups: control, E. coli pneumonia control, pneumonia with iNO 10 ppm, pneumonia pre-treated with L-NAME 10 mg/kg, and pneumonia with the combined therapy of L-NAME pretreatment and iNO. E. coli pneumonia was induced via intratracheal instillation of Escherichia coli, which resulted in progressively decreased cardiac index and oxygen tension; increased pulmonary vascular resistance index (PVRI), intrapulmonary shunting, and developed septicemia at the end of 6 hr experiment. iNO ameliorated the progressive hypoxemia and intrapulmonary shunting without affecting the PVRI. Only two of 8 animals with L-NAMEpretreated pneumonia survived. Whereas when iNO was added to infected animals with L-NAME pretreatment, the progressive hypoxemia was abolished as a result of a decrease in intrapulmonary shunting without reverse of the high PVRI and systemic vascular resistance index induced by the L-NAME injection. This result suggests that a NOS blockade may be a possible supportive option for oxygenation by iNO treatment in neonatal Gram-negative bacterial pneumonia and sepsis.

Pretreatment with N-nitro-L-arginine Methyl Ester Improved Oxygenation After Inhalation of Nitric Oxide in Newborn Piglets with Escherichia coli Pneumonia and Sepsis

We evaluated the effects of a combined therapy of pre-blockade endogenous nitric oxide synthase (NOS) with N-nitro-L-arginine methyl ester (L-NAME) and continuous inhaled NO (iNO) on the gas exchange and hemodynamics of Escherichia coli pneumonia and sepsis in newborn piglets. Seven to ten day old ventilated newborn piglets were randomized into 5 groups: control, E. coli pneumonia control, pneumonia with iNO 10 ppm, pneumonia pre-treated with L-NAME 10 mg/kg, and pneumonia with the combined therapy of L-NAME pretreatment and iNO. E. coli pneumonia was induced via intratracheal instillation of Escherichia coli, which resulted in progressively decreased cardiac index and oxygen tension; increased pulmonary vascular resistance index (PVRI), intrapulmonary shunting, and developed septicemia at the end of 6 hr experiment. iNO ameliorated the progressive hypoxemia and intrapulmonary shunting without affecting the PVRI. Only two of 8 animals with L-NAMEpretreated pneumonia survived. Whereas when iNO was added to infected animals with L-NAME pretreatment, the progressive hypoxemia was abolished as a result of a decrease in intrapulmonary shunting without reverse of the high PVRI and systemic vascular resistance index induced by the L-NAME injection. This result suggests that a NOS blockade may be a possible supportive option for oxygenation by iNO treatment in neonatal Gram-negative bacterial pneumonia and sepsis.

Therapeutic Window for Cycloheximide Treatment after Hypoxic-Ischemic Brain Injury in Neonatal Rats

We have previously shown that cycloheximide significantly inhibited apoptosis, and reduced ensuing cerebral infarction in a newborn rat model of cerebral hypoxiaischemia. This study was performed to determine the therapeutic window for cycloheximide therapy. Seven day-old newborn rat pups were subjected to 100 min of 8% oxygen following a unilateral carotid artery ligation, and cycloheximide was given at 0, 6, 12 and 24 hr after hypoxia-ischemia (HI). Apoptosis or necrosis was identified by performing flow cytometry with a combination of fluorescinated annexin V and propidium iodide, and the extent of cerebral infarction was evaluated with triphenyl tetrazolium chloride (TTC) at 48 hr and 72 hr after HI, respectively. With cycloheximide treatment at 0 hr after HI, both apoptotic and necrotic cells by flow cytometry were significantly reduced, only necrotic cells were significantly reduced at 6 and 12 hr, and no protective effect was seen if administration was delayed until 24 hr after HI compared to the HI control group. Infarct volume, measured by TTC, was significantly reduced by 92% and 61% when cycloheximide was given at 0 or 6 hr after HI respectively; however, there was an insignificant trend in infarct reduction if cycloheximide was administered 12 hr after HI, and no protective effect was observed when administration was delayed until 24 hr after HI. In summary, cycloheximide was neuroprotective when given within 6 hr after HI in the developing newborn rat brain.

Effects of NG-monomethyl-L-arginine and L-arginine on cerebral hemodynamics and energy metabolism during reoxygenation-reperfusion after cerebral hypoxia-ischemia in newborn piglets / 소아과

PURPOSE: This study was carried out to elucidate the effects of nitric oxide synthase(NOS) inhibitor, NG-monomethyl-L-arginine(L-NMMA) and nitric oxide precursor, L-arginine(L-Arg) on cerebral hemodynamics and energy metabolism during reoxygenation-reperfusion(RR) after hypoxia-ischemia(HI) in newborn piglets. METHODS: Twenty-eight newborn piglets were divided into 4 groups; Sham normal control(NC), experimental control(EC), L-NMMA(HI & RR with L-NMMA), and L-Arg(HI & RR with L-Arg) groups. HI was induced by occlusion of bilateral common carotid arteries and simultaneously breathing with 8 percent oxygen for 30 mins, and followed RR by release of carotid occlusion and normoxic ventilation for one hour. All groups were monitored with cerebral hemodynamics and cytochrome aa3 (Cyt aa3) using near infrared spectroscopy(NIRS). Na+, K(+)-ATPase activity, lipid peroxidation products, and tissue high energy phosphate levels were determined biochemically in the cerebral cortex. RESULTS: In experimental groups, mean arterial blood pressure, PaO2, and pH decreased, and base excess and blood lactate level increased after HI compared to NC group(P<0.05). These variables subsequently returned to baseline after RR except pH. There were no differences among the experimental groups. In NIRS, oxidized hemoglobin(HbO2) decreased and hemoglobin(Hb) increased during HI(P<0.05) but returned to base line immediately after RR; 40 min after RR, the HbO2 had decreased significantly compared to NC group(P<0.05). Changes of Cyt aa3 decreased significantly compared to NC after HI and recovered at the end of the experiment. Significantly reduced cerebral cortical cell membrane Na+, K(+)-ATPase activity and increased lipid peroxidation products(P<0.05) were not improved with L-NMMA or L-Arg. CONCLUSION: These findings suggest that NO is not involved in the mechanism of HI and RR brain damage during the early acute phase of RR.

Neuroprotective Effect of Cycloheximide on Hypoxic-Ischemic Brain Injury in Neonatal Rats

This study was done to determine the neuroprotective effect of cycloheximide on neonatal hypoxic-ischemic brain injury. Seven day-old newborn rat pups were subjected to 90 min of 8% oxygen following a unilateral carotid artery ligation. The extent of cerebral infarction was evaluated at 1 and 4 week of recovery. Apoptosis was identified by performing terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining and flow cytometry with a combination of fluoresceinated annexin V and propidium iodide. Brain infarction area was significantly increased at 4 week compared to 1 week after hypoxia-ischemia in the control group. With cycloheximide treatment, the number of TUNEL positive cells in the ipsilateral cerebral cortex at 48 hr and peri-infarct area at 1 and 4 week of recovery was significantly reduced, both apoptotic and necrotic cells by flow cytometry 48 hr after the injury were significantly reduced, and the extent of cerebral infarction at 1 and 4 week of recovery was also significantly attenuated compared to the hypoxia-ischemia control group. In summary, our data suggest that apoptosis plays an important role in the development of delayed infarction, and inhibition of apoptosis with cycloheximide significantly reduces the ensuing cerebral infarction in a newborn rat pup model of cerebral hypoxia-ischemia.

Single Cell Dissociation Methods for Flow Cytometric Cell Death Analysis of Hypoxia-Ischemia Injured Newborn Rat Pup Brain / 소아과

PURPOSE: Newborn brain tissue has to be dissociated into a single cell suspension for flow cytometric analysis of cell death during hypoxia-ischemia. Thus the development of a method to dissociate cells from the brain tissue with least damage and maintenance of membrane and antigen integrity remains the challenge for the in vivo application of this technique. We evaluated the efficacy of mechanical or enzymatic (collagenase or tryspin) methods of brain tissue disaggregation. METHODS: The extent of the damage to the plasma membrane and loss of the characteristics of the membrane induced with each dissociation method was determined by comparing the flow cytometric results labeled with both fluorescent annexin V and propidium iodide of the newborn rat pup brain tissue in the control group (n=10) and in the 48-hour after hypoxia-ischemia group (n=10). RESULTS: In the control group, the cell percentage of damaged, apoptotic and necrotic cells of both hemispheres with the mechanical dissociation method was significantly increased compared to the trypsin or collagenase method. In the 48-hour after hypoxia-ischemia group, the cell percentage of apoptotic and necrotic cells of the right hemisphere with the collagenase method significantly increased, and live cells significantly decreased compared to the left hemisphere, control group. Although the same trend was observed, the extent of alterations made with the trypsin method was significantly less compared to the collagenase method. CONCLUSION: The dissociation of neonatal brain tissue for flow cytometric analysis with collagenase was most efficacious with the least cell damage and preservation of the plasma membrane characteristics.

Effect of Hyperbilirubinemia on the Brainstem Auditory Evoked Response in Newborn Piglets

PURPOSE: We sought to know the effect of hyperbilirubinemia on brainstem auditory evoked response in newborn piglets. METHODS: To achieve the concentration of bilirubin above 20 mg/dL, we injected a bolus of 50 mg/kg of bilirubin intravenously over 30 minutes, followed by 30-40 mg/kg/ hr of bilirubin continuous intravenous infusion to 10 newborn piglets. Brainstem auditory evoked responses were obtained from these piglets at baseline, 1 hour, 2 hours, 3 hours and 4 hours after the exposure to hyperbilirubinemia. RESULTS: The mean amplitude of wave V was 0.33+/-0.03 microV at baseline, 0.32+/-0.04 microV at 1 hour, 0.33+/-0.05 microV at 2 hours, 0.23+/-0.04 microV at 3 hours and 0.26+/-0.05 microV at 4 hours of experiment and began to decrease after 3 hours of the exposure to hyperbilirubinemia. The latency of wave III was 4.06+/-0.08 ms at baseline, 3.95+/-0.09 ms at 1 hour, 4.05+/-0.10 ms at 2 hours, 4.05+/-0.09 ms at 3 hours, 4.12+/-0.11 ms at 4 hours of experiment and began to increase after 1 hour of the exposure to hyperbilirubinemia. CONCLUSION: Hyperbilirubinemia decreased the amplitude of wave V and increased the latency of wave III of brainstem auditory evoked responses in newborn piglets.