Transcatheter Tricuspid Valve Repair in Prohibitive Risk Patients: Impact on Quality of Life and Major Organ Systems.

BACKGROUND: Percutaneous repair for severe tricuspid regurgitation (TR) is emerging as a viable option, but patient selection is challenging and predetermined by comorbidities. This study evaluated mid-term outcomes of transcatheter tricuspid valve repair (TTVR) in very sick inoperable patients and explored the concept of risk-based therapeutic futility. METHODS: TTVR patients treated in our centre were prospectively assigned to prohibitive-risk (PR) and high-risk (HR) subgroups, based on Society of Thoracic Surgeons (STS) Score, frailty indices, and major organ system compromise. Efficacy and safety outcomes were compared at baseline, 30 days, and 6 months. RESULTS: Thirty-three patients (mean age 81.9 ± 5.1 years) completed follow-up from May 2021 to March 2022: 18 PR (mean STS Score 15.5 ± 7%) and 15 HR (mean STS Score 6.4 ± 1.7%). The primary efficacy end point of at least 1 grade of TR reduction by 30 days was recorded in 93.9% of all patients, with no device-related adverse events. Improvement in initial New York Heart Association functional class III/IV occurred in 74% of PR and 93% of HR patients. Six-minute walk test increased by 81 ± 43.6 metres (P < 0.001) and 85.8 ± 47.9 metres (P < 0.001), respectively. Renal function tests improved by 15% (P = 0.048) and 7% (P = 0.050), while liver enzymes decreased by 18% (P = 0.020) and 28% (P = 0.052). Right ventricular systolic function increased in both subgroups by at least 24% (P < 0.001). Six-month mortality was 12.1%, with 6 hospitalisations for acute heart failure. CONCLUSIONS: TR reduction significantly affected quality of life, functional capacity, cardiac remodelling, and multiorgan involvement similarly in PR and HR patients. TTVR is feasible in very sick symptomatic patients, regardless of predicted risk.

Anticholinergic Drug Exposure Increases the Risk of Delirium in Older Patients Undergoing Elective Surgery.

Introduction: Postoperative delirium (POD) is a common and serious adverse event of surgery in older people. Because of its great impact on patients' safety and quality of life, identification of modifiable risk factors could be useful. Although preoperative medication intake is assumed to be an important modifiable risk factor, the impact of anticholinergic drugs on the occurrence of POD seems underestimated in elective surgery. The aim of this study was to investigate the association between preoperative anticholinergic burden and POD. We hypothesized that a high preoperative anticholinergic burden is an independent, potentially modifiable predisposing and precipitating factor of POD in older people. Methods: Between November 2017 and April 2019, 1,470 patients of 70 years and older undergoing elective orthopedic, general, cardiac, or vascular surgery were recruited in the randomized, prospective, multicenter PAWEL trial. Anticholinergic burden of a sub-cohort of 899 patients, who did not receive a multimodal intervention for preventing POD, was assessed by two different tools at hospital admission: The established Anticholinergic Risk Scale (ARS) and the recently developed Anticholinergic Burden Score (ABS). POD was detected by confusion assessment method (CAM) and a validated post discharge medical record review. Logistic regression analyses were performed to evaluate the association between anticholinergic burden and POD. Results: POD was observed in 210 of 899 patients (23.4%). Both ARS and ABS were independently associated with POD. The association persisted after adjustment for relevant confounding factors such as age, sex, comorbidities, preoperative cognitive and physical status, number of prescribed drugs, surgery time, type of surgery and anesthesia, usage of heart-lung-machine, and treatment in intensive care unit. If a patient was taking one of the 56 drugs listed in the ABS, risk for POD was 2.7-fold higher (OR = 2.74, 95% CI = 1.55-4.94) and 1.5-fold higher per additional point on the ARS (OR = 1.54, 95% CI = 1.15-2.02). Conclusion: Preoperative anticholinergic drug exposure measured by ARS or ABS was independently associated with POD in older patients undergoing elective surgery. Therefore, identification, discontinuation or substitution of anticholinergic medication prior to surgery may be a promising approach to reduce the risk of POD in older patients.

Outcomes of a Delirium Prevention Program in Older Persons After Elective Surgery: A Stepped-Wedge Cluster Randomized Clinical Trial.

Importance: Delirium significantly worsens elective surgery outcomes and costs. Delirium risk is highest in elderly populations, whose surgical health care resource consumption (50%) exceeds their demographic proportion (15% to 18%) in high-resource countries. Effective nonpharmacologic delirium prevention could safely improve care in these vulnerable patients, but data from procedure-specific studies are insufficiently compelling to drive changes in practice. Delirium prevention approaches applicable to different surgical settings remain unexplored. Objective: To examine whether a multifaceted prevention intervention is effective in reducing postoperative delirium incidence and prevalence after various major surgical procedures. Design, Setting, and Participants: This stepped-wedge cluster randomized trial recruited 1470 patients 70 years and older undergoing elective orthopedic, general, or cardiac surgery from November 2017 to April 2019 from 5 German tertiary medical centers. Data were analyzed from December 2019 to July 2021. Interventions: First, structured delirium education was provided to clinical caregivers at each site. Then, the study delirium prevention team assessed patient delirium risk factors and symptoms daily. Prevention was tailored to individual patient needs and could include: cognitive, motor, and sensory stimulation; meal companionship; accompaniment during diagnostic procedures; stress relaxation; and sleep promotion. Main Outcomes and Measures: Postoperative delirium incidence and duration. Results: Of 1470 included patients, 763 (51.9%) were male, and the median (IQR) age was 77 (74-81) years. Overall, the intervention reduced postoperative delirium incidence (odds ratio, 0.87; 95% CI, 0.77-0.98; P = .02) and percentage of days with delirium (intervention, 5.3%; control, 6.9%; P = .03). The effect was significant in patients undergoing orthopedic or abdominal surgery (odds ratio, 0.59; 95% CI, 0.35-0.99; P = .047) but not cardiac surgery (odds ratio, 1.18; 95% CI, 0.70-1.99; P = .54). Conclusions and Relevance: This multifaceted multidisciplinary prevention intervention reduced postoperative delirium occurrence and days with delirium in older patients undergoing different elective surgical procedures but not cardiac procedures. These results suggest implementing this delirium prevention program will improve care and outcomes in older patients undergoing elective general and orthopedic procedures.

Patient safety, cost-effectiveness, and quality of life: reduction of delirium risk and postoperative cognitive dysfunction after elective procedures in older adults-study protocol for a stepped-wedge cluster randomized trial (PAWEL Study).

BACKGROUND: Postoperative delirium is a common disorder in older adults that is associated with higher morbidity and mortality, prolonged cognitive impairment, development of dementia, higher institutionalization rates, and rising healthcare costs. The probability of delirium after surgery increases with patients' age, with pre-existing cognitive impairment, and with comorbidities, and its diagnosis and treatment is dependent on the knowledge of diagnostic criteria, risk factors, and treatment options of the medical staff. In this study, we will investigate whether a cross-sectoral and multimodal intervention for preventing delirium can reduce the prevalence of delirium and postoperative cognitive decline (POCD) in patients older than 70 years undergoing elective surgery. Additionally, we will analyze whether the intervention is cost-effective. METHODS: The study will be conducted at five medical centers (with two or three surgical departments each) in the southwest of Germany. The study employs a stepped-wedge design with cluster randomization of the medical centers. Measurements are performed at six consecutive points: preadmission, preoperative, and postoperative with daily delirium screening up to day 7 and POCD evaluations at 2, 6, and 12 months after surgery. Recruitment goals are to enroll 1500 patients older than 70 years undergoing elective operative procedures (cardiac, thoracic, vascular, proximal big joints and spine, genitourinary, gastrointestinal, and general elective surgery procedures). DISCUSSION: Results of the trial should form the basis of future standards for preventing delirium and POCD in surgical wards. Key aims are the improvement of patient safety and quality of life, as well as the reduction of the long-term risk of conversion to dementia. Furthermore, from an economic perspective, we expect benefits and decreased costs for hospitals, patients, and healthcare insurances. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00013311 . Registered on 10 November 2017.

Evolution of transcatheter aortic valve implantation over 7 years: results of a prospective single-centre registry of 2000 patients in a large municipal hospital (TAVIK Registry).

OBJECTIVES: Use of transcatheter aortic valve implantation (TAVI) to treat severe aortic stenosis (AS) has gained popularity, accompanied by an evolution of patient and clinical factors. We aimed to characterise changes and evaluate their impact on outcomes. SETTING: In this single-centre, German TAVIK registry patients undergoing TAVI between 2008 and 2015 were documented prospectively. PARTICIPANTS/INTERVENTIONS: 2000 consecutive patients with AS undergoing TAVI were divided in four cohorts. 500 patients underwent TAVI in each of the following time bins: April 2008 to July 2010 (cohort I), July 2010 to April 2013 (cohort II), April 2012 to October 2013 (cohort III) and October 2013 to March 2015 (cohort IV). RESULTS: The mean age was 81.8 years, without significant variation across cohorts. Compared with cohort I, prior MI (5.4%vs11.0%; p<0.001) and New York Heart Association class IV (10.0%vs3.6%; p<0.001) were less common in cohort IV. Across cohorts, there was a fall in EuroSCORE (24.3%-18.7%), frailty (48.4%-17.0%) and use of transapical access (43.6%-29.0%), while transfemoral access increased (56.4%-71.0%; p<0.001 for each). Periprocedurally, there was a fall in moderate/severe aortic regurgitation (3.2%-0.0%) and rate of unplanned cardiopulmonary bypass (4.0%-1.0%; both p<0.001). A similar trend applied to 30-day rate of major vascular complications (5.2%-1.8%; p=0.006), life-threatening bleeding (7.0%-3.0%; p<0.001) and cardiovascular mortality (4.4%-1.8%; p=0.020). One-year post-TAVI, mortality and stroke rates did not differ. CONCLUSIONS: Evolution of TAVI between 2008 and 2015 saw a trend towards its usage in lower risk patients and rapid progression towards improved safety. Evaluation and refinement should now continue to further lessen stroke and pacemaker rates.

Feasibility of transcatheter aortic valve implantation in patients with coronary heights ≤7 mm: insights from the transcatheter aortic valve implantation Karlsruhe (TAVIK) registry.

OBJECTIVES: Transcatheter aortic valve implantation (TAVI) in patients with low coronary heights is generally denied but is not impossible. Information about these high-risk procedures is sparse. METHODS: Since May 2008, data of more than 3000 patients who had TAVI were prospectively collected in the institutional TAVI Karlsruhe registry. Characteristics, peri- and postoperative outcome of patients with low coronary heights of ≤7 mm were analysed according to the Valve Academic Research Consortium-2. RESULTS: Eighty-six patients with an average coronary height of 6.4 ± 1.1 mm (mean age 81.0 ± 5.3 years, logistic EuroSCORE I 19.6 ± 13.3%) were treated. TAVI was performed in 72 transfemoral (83.7%) and 14 transapical (16.3%) cases using 44 CoreValve/Evolut R (51.2%), 21 Sapien XT/S3 (24.4%), 14 ACURATE (16.3%), 5 Lotus (5.8%) and 2 Portico (2.3%) prostheses. Ten procedures were valve-in-valve (VinV) TAVI (VinV, 11.6%). The 72-h, 30-day, 1-year and follow-up (3.0 ± 1.6 years) mortality rates were 2.3%, 8.0%, 10.5% and 26.7%, respectively. Within 30 days, 4 cardiac deaths and 3 non-cardiac deaths occurred (4.7% and 3.5%). Three coronary obstructions (3.5%) occurred-2 during VinV TAVI. One patient was connected to extracorporeal circulation that could not be weaned later due to an unsuccessful percutaneous coronary intervention. Another patient, the only conversion (1.2%), required delayed surgical valve replacement. The third patient died of right heart failure after aortic dissection. The procedural success rate was 95.3%. VinV procedures were associated with increased follow-up deaths (P < 0.001; hazard ratio 7.96). CONCLUSIONS: Coronary-related complications in TAVI procedures in patients with coronary heights ≤7 mm occurred less frequently, but once they occurred, they were serious. These TAVI procedures are feasible, with a high procedural success rate, but meticulous preoperative planning should be mandatory. In VinV procedures, the follow-up mortality rate is increased; therefore, we do not recommend these procedures.

Percutaneous Mechanical Circulation Support Combined with Extracorporeal Membrane Oxygenation (oxyRVAD) in Secondary Right Heart Failure.

Right heart failure (RHF) because of pulmonary hypertension (PH) is a frequently encountered clinical problem with high mortality. The last resort, if pharmacological therapy fails, is mechanical circulatory support. There is a lack of percutaneous systems to support the right ventricle (RV). Venoarterial extracorporeal membrane oxygenation is widely used as a bailout in acute RHF in non-left ventricular assist device patients. Venoarterial extracorporeal membrane oxygenation does not unload the left ventricle and may cause failure of the left ventricle if used for a longer period of time. We report the long-term use of an ECMO-based percutaneous right ventricular assist system (oxyRVAD) capable to deliver up to 6 L/min of blood flow with a returning cannula placed in the main pulmonary artery used in RHF originating from PH with poor oxygenation. We present a series of four patients on oxyRVAD (mean treatment duration 15 ± 7.6 days). Patients benefited from the system clinically; however, two patients eventually died while on oxyRVAD. Nevertheless, we provide a proof-of-concept of this system in PH patients, which is feasible and might provide a useful "bridge-to-recovery" or "bridge-to-transplant" option in the management of patients with severe RHF because of PH.

Cross-clamping a porcelain aorta: an alternative technique for high-risk patients.

BACKGROUND: Aortic cross-clamping in patients with porcelain aorta is associated with high mortality and morbidity rates. The aim is to establish a new approach to improve the outcome in this high-risk population. METHODS: Between September 2007 and November 2012, 42 patients with an aortic (N.=33; 81.3±6.4 years) or mitral valve disease (N.=9; 80.3±5.7) combined with a porcelain aorta underwent aortic (AVR) or mitral valve replacement (MVR). After arterial cannulation via distal aortic arch or femoral artery, longitudinal aortotomy under total cardiopulmonary bypass (CPB) was performed. The aorta was slowly clamped, thus mobilized atherosclerotic material could leave the aorta through the open incision. Subsequent to the actual operation, the aorta was gradually unclamped. Again, plaques were flushed out via the still open aortotomy ("open proximal ascending aorta"). RESULTS: Intraoperatively, no technical no problems occurred. Mean CPB time was 92.2±27.9 min (AVR) and 92.3±36.3 min (MVR); cardiac ischemia time was 74.3±26.7 min (AVR) and 77.1±31.6 min (MVR). Surgical revision was necessary in three patients (7.1%) due to major bleedings. Two AVR-patients suffered from minor stroke and one MVR-patient from major stroke (neurological deficit rate =7.1%). Transient ischemic attacks occurred in three patients (7.1%), another three patients (7.1%) required temporary hemofiltration. Neither gastrointestinal disorders nor respiratory failure or valve-related problems were noted. 30-day mortality was 6.9%. CONCLUSIONS: Cross-clamping with "open proximal ascending aorta" is effective and the incidence of stroke and systemic embolization in patients with porcelain aorta is low compared to literature.

Glycine reduces platelet aggregation.

It has been demonstrated that a wide variety of white blood cells and macrophages (i.e. Kupffer cells, alveolar and peritoneal macrophages and neutrophils) contain glycine-gated chloride channels. Binding of glycine on the receptor stimulates Cl(-) influx causing membrane hyperpolarization that prevents agonist-induced influx of calcium. Since platelet-aggregation is calcium-dependent, this study was designed to test the hypothesis that glycine would inhibit platelet aggregation. Rats were fed diets rich of glycine for 5 days, while controls received isonitrogenous valine. The bleeding time and ADP- and collagen-induced platelet aggregation were measured. Dietary glycine significantly increased bleeding time about twofold compared to valine-treated controls. Furthermore, the amplitude of platelet aggregation stimulated with ADP or collagen was significantly decreased in whole blood drawn from rats fed 2.5 or 5 % dietary glycine by over 50 %. Addition of glycine in vitro (1-10 mM) also blunted rat platelet aggregation in a dose-dependent manner. Strychnine, a glycine receptor antagonist, abrogated the inhibitory effect of glycine on platelet-aggregation in vitro suggesting the glycine works via a glycine receptor. Glycine also blunted aggregation of human platelets. Further, the glycine receptor was detected in both rat and human platelets by western blotting. Based on these data, it is concluded that glycine prevents aggregation of platelets in a dose-dependent manner via mechanisms involving a glycine receptor.

How to do it: direct true lumen cannulation technique of the ascending aorta in acute aortic dissection type A.

In acute aortic dissection type A (AADA), direct true lumen cannulation (DTLC) of the ascending aorta is a fast and safe cannulation site providing antegrade perfusion of the supraaortic and visceral vessels. An Overholt clamp is passed around the ascending aorta to place a Mersilene tape for later securing of the arterial cannula. After draining venous blood into the cardiopulmonary bypass system (CPB), the ascending aorta is transected and the aortic lumen inspected. The true lumen is identified and an arterial cannula inserted directly. Finally, the cannula is secured with the previously placed tape and CPB is initiated. DTLC can be used as arterial cannulation standard technique in operations for AADA.

Successful management of fulminant pulmonary embolism using a novel portable extracorporeal life support system.

A 46-year-old man presented to the emergency room with pain in his left leg, dyspnea, and general cyanosis. During examination he collapsed and required resuscitation. Under suspicion of pulmonary embolism, a new portable "click 'n run" extracorporeal life support system (LIFEBRIDGE-B(2)T [Medizintechnik AG, Ampfing, Germany]) was implanted by the femoral vessels under resuscitation within 15 minutes of presentation. The patient was stabilized, despite severe decompensation (pH, 6.8), and could be transferred for a computed tomographic scan, which confirmed massive pulmonary embolism. Still connected to the life support system, the patient was transferred to the operating room. After a pulmonary thrombectomy was performed, the patient recovered without any organ dysfunction. A portable emergency extracorporeal life support may change clinical practice in the treatment of patients with severe hemodynamic deterioration at emergency care hospitals.

Reevaluation of direct true lumen cannulation in surgery for acute type A aortic dissection.

BACKGROUND: The optimal mode of arterial cannulation in acute type A aortic dissection is controversial. We retrospectively investigated our experience with direct true lumen cannulation as an alternative to standard cannulation procedures. METHODS: From April 2004 to August 2007, 29 patients (20 men, 9 women; mean age of 63.2 +/- 12.6 years) underwent emergency operation for acute type A aortic dissection with direct true lumen cannulation. After venous drainage into the venous reservoir, the ascending aorta was completely transected in the region between the sinotubular junction and innominate artery. After visual and digital identification of the true lumen, the arterial cannula was directly inserted into the true lumen and secured with a ligature. RESULTS: Mean aortic cross-clamp time was 77.4 +/- 28.3 minutes, and hypothermic circulatory arrest for the distal anastomosis was 10.4 +/- 11.0 minutes. All patients survived the surgical procedure. No surgical problems were observed by applying this strategy. Mean intensive care unit stay was 4.0 +/- 3.5 days. Postoperative mean ventilation time was 43.3 +/- 41.3 hours. One patient had a prolonged postoperative course and required permanent ventilation. Two patients required temporary hemofiltration. Neurologic disorders occurred in 6 patients: 2 had severe cerebral hypoxia, and 4 had temporary hemiplegia under good regression. All patients were alive at discharge. CONCLUSIONS: Direct true lumen cannulation is a promising surgical strategy for emergency operations in type A aortic dissection. It is a simple, quick, and safe method to provide antegrade flow through the true aortic lumen.

Extrahepatic cells contribute to the progenitor/stem cell response following reduced-size liver transplantation in mice.

The extent to which extrahepatic cells participate in liver regeneration following transplantation is not known. Either full-size or reduced-size livers from wild-type mice were implanted into green fluorescent protein-positive (GFP(+)) transgenic recipient mice to determine whether regenerated liver contained host-derived GFP(+) hepatic cells. After reduced-size liver transplantation, GFP(+) cells were localized to the portal zone of the liver lobule. Interestingly, GFP(+) cells stained for CD117, a marker for progenitor cells, beginning 2 days after transplantation. A significant number of GFP(+) CD117(+) cells were identified in donor livers after 28 days. GFP(+) cells comprised nearly 9% of the donor liver 28 days after reduced-size liver transplant. Moreover, GFP(+) cells also expressed the hepatic progenitor cell marker A6 and novel marker hepatic-specific antigen (HSA), as well as stem cell antigen-1 (Sca-1). Interestingly, some GFP(-) cells also were stained for CD117 and A6, suggesting that both extrahepatic and intrahepatic stem cells were present and may have contributed to the regenerative response under these conditions. Reduced-size liver transplantation using GFP(+) transgenic mice supports the hypothesis that recipient-derived progenitor cells are present and may contribute to liver regeneration following transplantation.

Graft tumor necrosis factor receptor-1 protects after mouse liver transplantation whereas host tumor necrosis factor receptor-1 promotes injury.

BACKGROUND: Tumor necrosis factor (TNF)-alpha is a cytokine with pleiotropic effects on the liver. The predominant hepatic receptor for TNFalpha is TNF receptor-1 (TNFR1). TNFR1 mediates liver injury after ischemia/reperfusion but is also mitogenic during hepatic regeneration. This study investigated the role of graft and host TNFR1 in early graft injury after liver transplantation in mice. METHODS: Livers from TNFR1 deficient (TNFR1-/-) and wild type (WT) mice were transplanted into either TNFR1-/- or WT recipients in all four possible combinations after 12 hours of cold storage. After eight hours, alanine transferase (ALT), necrosis, TdT-mediated dUTP-digoxigenin nick-end labeling (TUNEL) staining, caspase-3 activation, and myeloperoxidase were determined. RESULTS: When TNFR1-/- livers were transplanted into either WT or TNFR1-/- recipients, ALT was twofold greater than when WT donor livers were used. Necrosis and TUNEL staining also increased twofold and sevenfold, respectively, after transplantation of TNFR1-/- donor livers compared to WT. By contrast, ALT and necrosis decreased when WT or TNFR1-/- livers were transplanted into TNFR1-/- hosts compared to WT, which was associated with decreased neutrophil infiltration. CONCLUSION: In conclusion, graft and recipient TNFR1 has opposing effects. Graft TNFR1 decreases graft injury, whereas recipient TNFR1 mediates an increase of injury associated with enhanced neutrophil infiltration. Cross-transplanting of knockout and wild-type livers provides a new means to investigate graft-host interactions during hepatic injury.

TNF alpha-induced Ras activation due to ethanol promotes hepatocyte proliferation independently of liver injury in the mouse.

Tumor necrosis factor alpha (TNFalpha) has been shown to be both proapoptotic and mitogenic for hepatocytes and necessary for alcohol-induced liver injury. Ras, a known proto-oncogene, is very important in the regulation of cellular responses to TNFalpha. Therefore, the purpose of this study was to investigate the role of Ras in alcohol-induced pathogenesis. Male C57Bl/6 mice were fed ethanol or high-fat control diet via intragastric cannulation for 4 weeks. Ras activity was increased significantly after 4 weeks of ethanol and correlated with an increase in pathologic features. However, in mice deficient in the receptor-type 1 for TNFalpha (TNFR1(-/-)), ethanol-induced liver injury and the increase in Ras activity were significantly blunted compared with wild-type mice. Furthermore, it was demonstrated that H-, K-, and R-Ras isoforms were increased after ethanol exposure in wild-type mice. In TNFR1(-/-) mice, R-Ras activity remained elevated by ethanol, whereas H-Ras and K-Ras activity was blunted significantly under these conditions. Interestingly, hepatocellular proliferation, which was elevated approximately fivefold after 4 weeks of chronic ethanol in wild-type mice, was also blunted in TNFR1(-/-) mice given ethanol. Inhibition of Ras with adenovirus containing a dominant-negative Ras had no effect on ethanol-induced liver injury, but significantly blunted ethanol-induced hepatocyte proliferation by more than 50%. Overexpression of mitochondrial superoxide dismutase using recombinant adenovirus blunted lipid peroxidation and attenuated hepatic injury resulting from ethanol, but had no effect on Ras activation and hepatocyte proliferation caused by ethanol. In conclusion, these data support the hypotheses that hepatocellular oxidative stress leads to cell death and that TNFalpha-induced Ras activation is important in hepatic proliferation in response to ethanol-induced liver injury.

Reduced-size liver transplantation in the mouse.

BACKGROUND: Reduced-size liver transplantation (RSLT) is increasingly used but is still associated with an increased susceptibility to graft damage, failure, and retransplantation. To investigate mechanisms underlying graft injury after RSLT, this study developed a model of RSLT in mice. METHODS: Livers from male C57Bl/6 mice were explanted and stored in cold University of Wisconsin solution. The livers were reduced to 50% by resecting the left lobes. After cold storage for 1 hr, the grafts were implanted. As controls, full-size liver transplantations and sham operations were performed. In some mice, after 41 hr of surgery, 5-bromo-2'-deoxyuridine (BrdU) was administered for BrdU cytochemistry and histology 1 hr later. Alanine transaminase, bilirubin, and survival were determined. RESULTS: Survival after RSLT was 100% and 86% after 42 hr and 8 days, respectively, compared with 100% after full-size transplantation. After 42 hr, alanine transaminase increased eightfold after RSLT and twofold after full-size versus sham operation. Bilirubin in RLST increased approximately twofold compared with full-size and sham. Histology after RSLT was consistent with regeneration but otherwise virtually normal. BrdU incorporation after RSLT and full-size transplantation increased 54-fold and twofold, respectively, compared with sham. Regeneration of the reduced-size graft was also indicated by a 67% increase of graft weight after 42 hr. CONCLUSION: RSLT can be performed in mice with good graft survival, minimal graft injury, and a robust hepatic regenerative response. This model of 50% RSLT provides a new tool to study mechanisms of graft injury and regeneration in genetically modified mice.

Dependence of liver injury after hemorrhage/resuscitation in mice on NADPH oxidase-derived superoxide.

Hemorrhagic shock and resuscitation cause hepatocellular damage by mechanisms involving oxidative stress. However, the sources of free radicals mediating hepatocellular injury remain controversial. Thus, this study tested the hypothesis that NADPH oxidase plays a role in producing hepatocellular injury after hemorrhagic shock and resuscitation. Both wild-type and NADPH oxidase-deficient mice (p47(phox) knockout mice) were subjected to hemorrhagic shock (3 h at 30 mmHg). The mice were resuscitated over 30 min with the shed blood and additional lactated Ringer's solution (50% of the shed blood volume). Serum alanine aminotransferase (ALT) levels increased at 1 and 6 h postresuscitation in wild-type animals to 4735 +/- 1017 IU/L and 1450 +/- 275 IU/L (mean +/- SE), respectively, whereas in knockout mice, this ALT increase was blunted at both time points (732 +/- 241 IU/L and 328 +/- 69 IU/L, P < 0.05). Liver necrosis assessed histologically 6 h after the end of reperfusion was also attenuated in the knockout mice (3.5% +/- 0.95% of area vs. 0.9% +/- 0.26%, P < 0.05). In hemorrhaged wild-type mice, infiltrating neutrophils were twice as numerous compared with hemorrhaged NADPH oxidase-deficient animals 6 h after reperfusion. In knockout animals, hepatic 4-hydroxynonenal content, indicative of lipid peroxidation from reactive oxygen species, was blunted (6.7% +/- 0.6% vs. 26.4% +/- 2.3% of stained area, P < 0.05), as shown by immunohistochemistry. Immunohistochemical staining for 3-nitrotyrosine, indicative of reactive nitrogen species formation, was also blunted in the livers of knockout mice (11.6% +/- 2.8% vs. 37.4% +/- 3.4, P < 0.05). In conclusion, hemorrhagic shock and resuscitation cause hepatocellular damage via NADPH oxidase-mediated oxidative stress. The absence of NADPH oxidase substantially attenuates hepatocellular injury after hemorrhagic shock and resuscitation, blunts neutrophil infiltration, and decreases formation of reactive oxygen and reactive nitrogen species.

Prevention of hepatic ischemia-reperfusion injury by green tea extract.

These experiments were designed to determine whether green tea extract (GTE), which contains polyphenolic free radical scavengers, prevents ischemia-reperfusion injury to the liver. Rats were fed a powdered diet containing 0-0.3% GTE starting 5 days before hepatic warm ischemia and reperfusion. Free radicals in bile were trapped with the spin-trapping reagent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) and measured using electron spin resonance spectroscopy. Hepatic ischemia-reperfusion increased transaminase release and caused pathological changes including focal necrosis and hepatic leukocyte infiltration in the liver. Transaminase release was diminished by over 85% and pathological changes were almost totally blocked by 0.1% dietary GTE. Ischemia-reperfusion increased 4-POBN/radical adducts in bile nearly twofold, an effect largely blocked by GTE. Epicatechin, one of the major green tea polyphenols, gave similar protection as GTE. In addition, hepatic ischemia-reperfusion activated NF-kappa B and increased TNF-alpha mRNA and protein expression. These effects were all blocked by GTE. Taken together, these results demonstrate that GTE scavenges free radicals in the liver after ischemiareoxygenation, thus preventing formation of toxic cytokines. Therefore, GTE could prove to be effective in decreasing hepatic injury in disease states where ischemia-reperfusion occurs.