Perfusion Technique Research Articles

Modulation of α7nAchR for Cardioprotection against Isoprenaline- Induced Myocardial Injury

The α7nAchR gene is expressed in immune cells, including macrophages, and is linked to cardiovascular diseases. The cardioprotective effects of α7nAchR activation against inflammation in isoprenaline-induced myocardial injury are unclear. This study aims to assess the cardioprotective effects of α7nAChR activation on isoprenaline-induced myocardial injury rats. We hypothesized that α7nAChR activation provides cardioprotection against the myocardial injury via the cholinergic anti-inflammatory pathway. Isoprenaline hydrochloride (85 mg/kg) was injected subcutaneously in rats to induce myocardial injury and activated the a7nAchR through daily transcutaneous tragus stimulation for 14 days at 20 Hz, 0.2 ms, and 2 mA. Examination on Langendorff isolated heart perfusion technique showed improvement in cardiac functions. The electrical stimulation affected collagen deposition, circulating troponin T, and circulating inflammatory marker TNFα. The effects were abolished with pharmacological inhibition of α7nAChR. Further, the role of α7nAChR in ischemia-induced inflammation was studied in RAW264.7 macrophages. Inflammation was activated in RAW264.7 macrophages that were treated with glucose-free media, flushed with 95% N2, and 5% CO2 for 1 h, and reoxygenated in a normoxic incubator for 24 h. a7nAchR stimulation in the activated macrophages reduced pro-inflammatory markers (NO, TNFα) but did not affect anti-inflammatory (IL10, TGFb) expression levels. The reduction in pro-inflammatory factors was linked to the modulation of the transcriptional regulator NFκB, but not STAT3. Our findings suggest that activation of the cholinergic anti-inflammatory pathway may protect against isoprenaline-induced cardiac injury by improving cardiac performance and regulating inflammatory macrophage activity potentially via the NFκB/TNFα pathway.

Transcranial Cortex-Wide Imaging of Murine Ischemic Perfusion With Large-Field Multifocal Illumination Microscopy.

Ischemic stroke is a common cause of death worldwide and a main cause of morbidity. Presently, laser speckle contrast imaging, x-ray computed tomography, and magnetic resonance imaging are the mainstay for stroke diagnosis and therapeutic monitoring in preclinical studies. These modalities are often limited in terms of their ability to map brain perfusion with sufficient spatial and temporal resolution, thus calling for development of new brain perfusion techniques featuring rapid imaging speed, cost-effectiveness, and ease of use. We report on a new preclinical high-resolution angiography technique for murine ischemic stroke imaging based on large-field high-speed multifocal illumination fluorescence microscopy. We subsequently showcase the proposed method by monitoring therapeutic effects of thrombolysis in stroke (n=6), further performing cross-strain comparison of perfusion dynamics (n=6) and monitoring the therapeutic effects of sensory stimulation-based treatment (n=11). Quantitative readings of hemodynamic and structural changes in cerebral vascular network and pial vessels were attained with 14.4-µm spatial resolution at 80-Hz frame rate fully transcranially. The in vivo perfusion maps accurately delineated the ischemic core and penumbra, further exhibiting a strong correlation (86.1±4.5%) with ex vivo triphenyl tetrazolium chloride staining, significantly higher than for the conventional laser speckle contrast imaging method. Monitoring of therapeutic effects of thrombolysis confirmed that early recanalization could effectively save the penumbra while reducing the infarct area. Cross-strain comparison of perfusion dynamics affirmed that C57BL/6 mice feature a larger penumbra and smaller infarct core as compared with BALB/c mice, which have few or no collaterals. Sensory stimulation-based treatment could effectively enhance blood flow and abolish perfusion deficits in the ischemic core and penumbra regions. A high-speed fluorescence-based angiography method for transcranial stroke imaging in mice is introduced, which is capable of localizing brain perfusion changes and accurately assessing the ischemic penumbra. Compared with the whole-brain x-ray computed tomography and magnetic resonance imaging methods, which are conventionally used for stroke diagnosis and therapeutic monitoring, the new approach is simple and cost-effective, further offering high resolution and speed for in vivo studies. It thus opens new venues for brain perfusion research under various disease conditions such as stroke, neurodegeneration, or epileptic seizures.

Variability in post-transplant outcomes reported by studies examining perfusion techniques in liver transplantation: a qualitative systematic review

Variability in post-transplant outcomes reported by studies examining perfusion techniques in liver transplantation: a qualitative systematic review

A Closed Circulation Langendorff Heart Perfusion Method for Cardiac Drug Screening

Cardiovascular diseases represent an economic burden for health systems accounting for substantial morbidity and mortality worldwide. Despite timely and costly efforts in drug development, the cardiovascular safety and efficacy of the drugs are not always fully achieved. These lead to the drugs’ withdrawal with adverse cardiac effects from the market or in the late stages of drug development. There is a growing need for a cost-effective drug screening assay to rapidly detect potential acute drug cardiotoxicity. The Langendorff isolated heart perfusion technique, which provides cardiac hemodynamic parameters (e.g., contractile function and heart rate), has become a powerful approach in the early drug discovery phase to overcome drawbacks in the drug candidate's identification. However, traditional ex vivo retrograde heart perfusion methods consume a large volume of perfusate, which increases the cost and limits compound screening. An elegant and cost-effective alternative mode for ex vivo retrograde heart perfusion is the constant-flow with a recirculating circuit (CFCC), which allows assessment of cardiac function using a reduced perfusion volume while limiting adverse effects on the heart. Here, we provide evidence for cardiac parameters stability over time in this mode. Next, we demonstrate that our recycled ex vivo perfusion system and the traditional open one yield similar outputs on cardiac function under basal conditions and upon β-adrenergic stimulation with isoproterenol. Subsequently, we validate the proof of concept of therapeutic agent screening using this efficient method. β-blocker (i.e., propranolol) infusion in closed circulation countered the positive effects induced by isoproterenol stimulation on cardiac function.

Beyond the icebox: modern strategies in organ preservation for transplantation.

Organ transplantation, a critical treatment for end-stage organ failure, has witnessed significant advancements due to the integration of improved surgical techniques, immunosuppressive therapies, and donor-recipient matching. This review explores the progress of organ preservation, focusing on the shift from static cold storage (SCS) to advanced machine perfusion techniques such as hypothermic (HMP) and normothermic machine perfusion (NMP). Although SCS has been the standard approach, its limitations in preserving marginal organs and preventing ischemia-reperfusion injury (IRI) have led to the adoption of HMP and NMP. HMP, which is now the gold standard for high-risk donor kidneys, reduces metabolic activity and improves posttransplant outcomes. NMP allows real-time organ viability assessment and reconditioning, especially for liver transplants. Controlled oxygenated rewarming further minimizes IRI by addressing mitochondrial dysfunction. The review also highlights the potential of cryopreservation for long-term organ storage, despite challenges with ice formation. These advances are crucial for expanding the donor pool, improving transplant success rates, and addressing organ shortages. Continued innovation is necessary to meet the growing demands of transplantation and save more lives.

Brain endothelial permeability, transport, and flow assessed over 10 orders of magnitude using the in situ brain perfusion technique

BackgroundCerebral blood flow normally places a limit on the magnitude of brain vascular permeability (P) that can be measured in vivo. At normal cerebral blood flow, this limit falls at the lower end of lipophilicity for most FDA-approved CNS drugs. In this study, we report on two methods that can be used to overcome this limitation and measure brain vascular permeability values that are up to ~1000 times higher using the in situ brain perfusion technique.MethodsRat brain was perfused with physiological saline at increased flow rate and in the presence of various concentrations of plasma protein, serum albumin or alpha-acid glycoprotein. Plasma protein was added to the saline perfusion fluid to lower extraction into the measurable range using the Crone Renkin “diffusion-flow” equation to calculate brain PoS.ResultsCerebrovascular Po was determined for 125 solutes, of which 78 showed little or no evidence of active efflux transport. Fifty of the solutes were in the lipophilicity zone (Log Poct 1–5) of most FDA-approved CNS drugs. Care was taken to ensure the integrity of the brain vasculature during perfusion and to measure flow accurately using markers that had been verified for the flow rates. The results showed a linear relationship between Log Po and Log Poct over ~10 orders of magnitude with values for diazepam, estradiol, testosterone, and other agents that exceed prior published values by fivefold to 200-fold.ConclusionsThe results show that brain vascular permeability can be measured directly in vivo for highly lipophilic solutes and the PS values obtained match reasonably with that predicted by the Crone-Renkin flow diffusion equation with care taken to validate the accuracy for the component measurements and with no need to invoke “enhanced” or “induced” dissociation.

Application of Bilateral Cerebral Perfusion + Balloon Occlusion of Descending Aorta + Antegrade Perfusion of Lower Body in Debakey Type I Aortic Dissection.

To evaluate the efficacy of a new perfusion method in DeBakey Type I aortic dissection surgery, with the goal of enhancing thorough organ protection and optimising patient outcomes. Descriptive study. Place and Duration of the Study: Department of Thoracic and Cardiovascular Surgery, The First Affiliated Hospital of the University of South China, from January 2020 to December 2021. Thirty-two patients undergoing total aortic arch replacement with descending aortic stenting were included in the study. The new perfusion method involved a combination of bilateral selective cerebral perfusion, descending aortic balloon occlusion, and antegrade lower body perfusion. Lower limb ischaemic complications and mortality rate were the main outcome measures. Surgical procedures and patient data were collected and analysed. No cases of paraplegia, intestinal necrosis, or lower-limb ischaemia were observed. The new perfusion method effectively protected lower-body organs, with a short duration of lower-body ischaemia during surgery. The overall mortality rate was 3.13%, and postoperative complications were minimal, resulting in satisfactory survival rates. The combination of perfusion techniques, including bilateral selective cerebral perfusion, descending aortic balloon occlusion, and anterograde lower body perfusion, proved effective in improving the outcomes for DeBakey Type I aortic dissection surgery. Further research is needed to confirm the long-term benefits of this approach. DeBakey type I aortic dissection, Descending aortic balloon blockade, Lower body anterograde perfusion, Bilateral selective cerebral perfusion.

Investigation of the Permeability of Antiretroviral Drugs Lamivudine and Valganciclovir via Single-Pass Intestinal Perfusion (SPIP) Method

Introduction: Antiretroviral medications are widely used to treat HIV infections. Lamivudine (3TC) is prescribed for HIV-1 infection management in adults and pediatrics, while valganciclovir (VGC) is a prodrug of ganciclovir derived from valine. Methods: The Biopharmaceutics Classification System (BCS) estimates the contributions of intestinal permeability, dissolution, and solubility in oral drug absorption. Intestinal permeability refers to a substance's capacity to pass through the protective layer of cells in the intestine. The intestinal permeability of 3TC and VGC was analyzed and categorized using the singlepass intestinal perfusion technique according to the BCS in male Sprague Dawley rats, and a reversed-phase HPLC method was validated for precise and accurate measurement. Results: According to the BCS, 3TC and VGC have been classified as having low permeability when compared to metoprolol tartrate, which is classified as Class I with good permeability and resolution. Conclusion: The permeability values derived from this work can be valuable in exposure assessment models.

Machine Perfusion as a Strategy to Decrease Ischemia-Reperfusion Injury and Lower Cancer Recurrence Following Liver Transplantation.

Liver transplantation (LT) is a key treatment for primary and secondary liver cancers, reducing tumor burden with concurrent improvement of liver function. While significant improvement in survival is noted with LT, cancer recurrence rates remain high. Mitochondrial dysfunction caused by ischemia-reperfusion injury (IRI) is known to drive tumor recurrence by creating a favorable microenvironment rich in pro-inflammatory and angiogenic factors. Therefore, strategies that decrease reperfusion injury and mitochondrial dysfunction may also decrease cancer recurrence following LT. Machine perfusion techniques are increasingly used in routine clinical practice of LT with improved post-transplant outcomes and increased use of marginal grafts. Normothermic (NMP) and hypothermic oxygenated machine perfusion (HOPE) provide oxygen to ischemic tissues, and impact IRI and potential cancer recurrence through different mechanisms. This article discussed the link between IRI-associated inflammation and tumor recurrence after LT. The current literature was screened for the role of machine perfusion as a strategy to mitigate the risk of cancer recurrence. Upfront NMP ("ischemia free organ transplantation") and end-ischemic HOPE were shown to reduce hepatocellular carcinoma recurrence in retrospective studies. Three prospective randomized controlled trials are ongoing in Europe to provide robust evidence on the impact of HOPE on cancer recurrence in LT.

Biliary Complications after Liver Transplant: Timeline, Spectrum, Management Algorithm, and Prevention

AbstractBiliary complications are the most common complications seen after liver transplantation (LT) with an incidence ranging between 10 and 15% and increasing in the setting of increased access to living donor liver transplant and utilization of marginal grafts. Among the biliary complications, the most common are anastomotic strictures, nonanastomotic strictures, and biliary leaks, which have a variable time of presentation posttransplant. The risk factors for the development of biliary complications include surgical techniques, type of grafts, prolonged ischemia, primary disease etiology, and associated post-LT complications. The approach to a diagnosis in an appropriate clinical setting involves a stepwise approach involving clinical history, assessment of risk factors, biochemical abnormalities, and appropriate imaging. Therapeutic options revolve around endoscopic retrograde cholangiopancreatography and percutaneous transhepatic biliary drainage, with surgical intervention being reserved in case of failure of these modalities. Preventive strategies with machine perfusion techniques are promising, while use of T-tubes for prevention of complications remains controversial.

Circulating cell‐free DNA in liver transplantation: A pre‐ and post‐transplant biomarker of graft dysfunction

AbstractBackgroundLiver transplantation (LT) is still limited by organ shortage and post‐transplant monitoring issues. While machine perfusion techniques allow for improving organ preservation, biomarkers like donor‐derived cell‐free DNA (dd‐cfDNA) and mitochondrial cfDNA (mt‐cfDNA) may provide insights into graft injury and viability pre‐ and post‐LT.MethodsA prospective observational cohort study was conducted on LT recipients (n = 45) to evaluate dd‐cfDNA as a biomarker of graft dysfunction during the first 6 months after LT. Dd‐cfDNA was quantified on blood samples collected pre‐LT and post‐LT using droplet digital PCR. In livers undergoing dual hypothermic oxygenated machine perfusion (D‐HOPE), total cfDNA and mt‐cfDNA levels were measured on perfusate samples collected at 30‐min intervals. Correlations with graft function and clinical outcomes were assessed.ResultsDd‐cfDNA levels peaked post‐LT and correlated with transaminase levels and histological injury severity. The longitudinal assessment showed that postoperative complications and rejection were associated with an increase in dd‐cfDNA levels. Mt‐cfDNA levels in D‐HOPE perfusate correlated with graft function parameters post‐LT and were higher in patients with early allograft dysfunction and severe complications.ConclusionsThis study confirms dd‐cfDNA as a marker of graft injury after LT and suggests that perfusate mt‐cfDNA levels during D‐HOPE correlate with graft function and post‐transplant clinical outcome. Integration of these tests into clinical practice may improve transplant management and viability assessment during hypothermic perfusion.

Development of a protocol for whole-lung in vivo lung perfusion-assisted photodynamic therapy using a porcine model.

Standard treatments for isolated lung metastases remain a clinical challenge. In vivo lung perfusion technique provides flexibility to overcome the limitations of photodynamic therapy (PDT) by replacing the blood with acellular perfusate, allowing greater light penetration. Using Monte Carlo-based simulations, we will evaluate the abilities of a light delivery system to irradiate the lung homogenously. Afterward, we aim to demonstrate the feasibility and safety profile of a whole-lung perfusion-assisted PDT protocol using 5-ALA and Chlorin e6. A porcine model of a simplified lung perfusion procedure was used. PDT was performed at 630 or 660nm with 5-ALA or Chlorin e6, respectively. Light fluence rate measurements and computed tomography (CT) scan segmentations were used to create in silico models of light propagation. Physiologic, gross, CT, and histological assessment of lung toxicity was performed 72h post-PDT. Dose-volume histograms showed homogeneity of light intensity throughout the lung. Predicted and measured fluence rates showed strong reliability. The photodynamic threshold of 5-ALA was , whereas Chlorin e6 showed negligible uptake in lung tissue. We lay the groundwork for personalized preoperative in silico dosimetry planning to achieve desired treatment volumes within the therapeutic range. Chlorin e6 demonstrated the greatest therapeutic potential, with a minimal uptake in healthy lung tissues.

An Arteriovenous Bioreactor Perfusion System for Physiological In Vitro Culture of Complex Vascularized Tissue Constructs.

The generation and perfusion of complex vascularized tissues in vitro requires sophisticated perfusion techniques. For multiscale arteriovenous networks, not only the arterial, but also the venous, biomechanical and biochemical conditions that physiologically exist in the human body must be accurately emulated. For this, we here present a modular arteriovenous perfusion system for the in vitro culture of a multi-scale bioartificial vascular network. The custom-built perfusion system consisted of two circuits: in the arterial circuit, physiological arterial biomechanical and biochemical conditions were simulated using a modular set-up with a pulsatile peristaltic pump, compliance chambers, and resistors. In the venous circuit, venous conditions were emulated accordingly. In the center of the system, a bioartificial multi-scale vascularized fibrin-based tissue was perfused by both circuits simultaneously under biomimetic arteriovenous conditions. Culture conditions were monitored continuously using a multi-sensor monitoring system. The physiological arterial and venous pressure- and flow-curves, as well as the microvascular arteriovenous oxygen partial pressure gradient, were accurately emulated in the perfusion system. The multi-sensor monitoring system facilitated live monitoring of the respective parameters and data-logging. In a proof-of-concept experiment, vascularized three-dimensional fibrin tissues showed sustained cell viability and homogenous microvessel formation after culture in the perfusion system. The arteriovenous perfusion system facilitated the in vitro culture of a multiscale vascularized tissue under physiological pressure-, flow-, and oxygen-gradient conditions. With that, it presents a promising technique for the in vitro generation and culture of complex large-scale vascularized tissues.

HPB O04 - Human Splenic Ex-Vivo Perfusion Model: A Platform for Translational Basic Science Research

Abstract Background The function of the spleen has always been shrouded in mystery and since the Renaissance leading figures have attempted to understand its function. Vesalius questioned Galen and Marcello Malpighi (1628-1694) gave the first accurate description of the histology and the physiology. The spleen still poses unique challenges as invasive approaches may produce intraperitoneal bleeding, differences between human and animal spleens complicates comparative studies, and post-mortem examinations reveal only late-stage disease manifestations and functional studies are impossible. This study describes a human splenic ex-vivo perfusion model for translational research, using microbiological studies as markers of splenic physiological function. Method Patients with left-sided pancreatic cancers scheduled for distal pancreatic and splenic resection were identified from the Hepato-Pancreatic and Biliary MDT at the University Hospitals of Leicester NHS Trust. Patients were informed, consented, and the surgical approach remained standard, with splenic artery ligation deferred until specimen extraction. The artery was cannulated, and residual blood clots were cleared with Custodiol® HTK solution. The perfusion technique employs an extracorporeal circuit incorporateing anoxygenator and a heated water chamber maintaining a 37°C perfusate. The perfused spleen was infected with Streptococcus Pneumoniae strains, with regular biopsies and perfusate gas analysis performed. Results Since February 2023, nine spleens have been successfully perfused, with an average weight of 169.5 grams, cold ischemic time of 116 minutes, and warm ischemic time of 12.2 minutes. Pressure was maintained at 80 mmHg and hourly perfusate gas analysis demonstrated a mean pH of 7.1 and a gradual increase in lactate. Histopathological examination revealed clear distinctions between the lymphoid tissue and splenic red pulp, with intact central arterioles and healthy cell morphology at time 0 and after 6 hours of perfusion. Additionally, the perfused spleens cleared S. pneumoniae strains to below-detection levels. Conclusion Our work demonstrates that a stable human splenic ex-vivoperfusion model which maintains structural and physiological integrity can be achieved from tissue that would otherwise be discarded. The continued physiological function is confirmed by the clearance of S. pneumoniae. While currently employed for microbiological studies, this model has the potential to facilitate a wide range of different translational science studieswhile reducing the need for animal experimentation. The perfusion times employed for the present study were sufficient to demonstrate bacterial clearance which was the aim but there is capacity in the system to significantly prolong the duration.

Psidium guajava leaves extract alters colonic microbiome composition and reduces intestinal sodium absorption in rats exposed to a high-sodium diet.

High sodium intake is a major risk factor for hypertension and renal diseases. Previous studies have shown that a suspension of ethanolic extract of Psidium guajava (guava) leaves (PsE) has antihypertensive effects in rats on a high-sodium diet (HSD), but some mechanisms to that remain unexplored. This study explored whether oral PsE treatment affects sodium handling by the intestine and alters the gut microbiome in HSD-fed rats. Male Wistar rats were divided into two groups: standard salt diet (SSD) and HSD (0.9% Na+), from weaning. After 12 weeks, both groups received PsE (200mg/kg) or a vehicle for an additional 4 weeks. Sodium excretion was measured using flame photometry, and sodium absorption was assessed by intestinal perfusion technique. The gut microbiome was analysed through 16S ribosomal gene sequencing. HSD increased faecal sodium, further elevated by PsE, which inhibited intestinal sodium absorption in HSD rats. HSD altered the abundance of specific bacterial families, which PsE partially reversed. No changes in alpha diversity were noted among groups. These findings suggest that PsE inhibited intestinal sodium handling and that PsE, combined with increased faecal sodium, may reshape the gut microbiome of HSD rats to resemble that of SSD rats.

Quantifying lower extremity blood flow using low-dose CT perfusion: validation in a swine model

Abstract Background Quantitative assessment of blood flow in peripheral extremities in conjunction with simultaneous CT angiography measurements can improve risk assessment and provide a critical decision-making tool for patients across a wide spectrum of vascular disease severity. Purpose This study assessed the reproducibility and accuracy of lower extremity blood flow measurements with a low-dose first-pass analysis CT perfusion technique. Materials and Methods This prospective study utilized 16 Yorkshire Swine to obtain lower extremity blood flow CT measurements at baseline and under induced femoral stenosis using a vascular occluder. Thirty-three pairs of CT measurements evaluated reproducibility, and 43 CT measurements assessed accuracy against ultrasound flow probe references. Contrast agent and saline chaser were both injected peripherally at a rate of 5 mL/s. Bolus tracking was used, and a pre-contrast and post-contrast helical scan were acquired at the base and approximately the peak of the femoral enhancement (CT angiogram), respectively. The acquired data were then used as analytical inputs into a first-pass analysis model to derive perfusion in mL/min/g. The reproducibility and accuracy of lower extremity perfusion measurements were assessed via Mixed model regression and Bland-Altman analysis. Results Calculated CT perfusion measurements derived from first-pass analysis technique (PCT), and the reference standard ultrasound perfusion measurements (Pref) were related by PCT = 1.06 Pref + 0.00 (r2 = 0.90, Root-Mean-Square Error [RMSE] = 0.01 mL/min/g). The first (P1) and second (P2) CT perfusion measurements were related by P2 = 0.98 P1 + 0.02 (r = 0.97, RMSE = 0.11 mL/min/g). The average effective dose of perfusion measurement using first-pass analysis technique was calculated to be only 2.13 mSv. Conclusion The low-dose quantitative CT perfusion technique can accurately measure lower extremity perfusion (mL/min/g) using only 2 helical scans. The CT angiogram and perfusion measurements can be used as a comprehensive technique for morphological and physiological assessment of limb ischemia.

A comprehensive organ protection strategy in total arch replacement: a propensity-weighted analysis.

To report the outcomes and determine the effectiveness of a comprehensive organ protection strategy in total arch replacement. A total of 350 patients who underwent total arch replacement were enrolled. 54 patients underwent the comprehensive organ protection strategy with bilateral antegrade cerebral perfusion (bACP) and aortic balloon occlusion (ABO) technique (comprehensive strategy group) and 296 patients underwent the standard strategy with unilateral antegrade cerebral perfusion (standard strategy group). Inverse probability of treatment weighting (IPTW) was used to balance the baseline characteristics. After IPTW, the comprehensive strategy group had lower incidences of 30-day mortality (0.9% vs 4.9%, P = 0.002), continuous renal replacement therapy (CRRT) (0.6% vs 10.3%, P < 0.001), renal failure (4.6% vs 13.7%, P < 0.001), hepatic dysfunction (11.6% vs 21.1%, P = 0.001), and shorter duration of mechanical ventilation [16 (13, 31) vs 20 (14, 48) hours, P = 0.011]. Multivariable logistic analysis showed the comprehensive strategy was an independent protective factor of 30-day mortality (odds ratio (OR): 0.242, 95% confidence interval (CI): 0.068-0.867, P = 0.029), CRRT (OR: 0.045, 95% CI: 0.008-0.264, P = 0.001), renal failure (OR: 0.351, 95% CI: 0.156-0.788, P = 0.011), and mechanical ventilation >20 hours (OR: 0.531, 95% CI: 0.319-0.883, P = 0.015). Kaplan-Meier analysis showed mid-term survival was comparable. The comprehensive organ protection strategy might improve early survival, reduce the use of CRRT, have protective effects on the kidney, and shorten mechanical ventilation time in total arch replacement. This strategy might be considered a viable alternative in total arch replacement.

L-Arginine and asymmetric dimethylarginine (ADMA) transport across the mouse blood-brain and blood-CSF barriers: Evidence of saturable transport at both interfaces and CNS to blood efflux

L-Arginine is the physiological substrate for the nitric oxide synthase (NOS) family, which synthesises nitric oxide (NO) in endothelial and neuronal cells. NO synthesis can be inhibited by endogenous asymmetric dimethylarginine (ADMA). NO has explicit roles in cellular signalling and vasodilation. Impaired NO bioavailability represents the central feature of endothelial dysfunction associated with vascular diseases. Interestingly, dietary supplementation with L-arginine has been shown to alleviate endothelial dysfunctions caused by impaired NO synthesis. In this study the transport kinetics of [3H]-arginine and [3H]-ADMA into the central nervous system (CNS) were investigated using physicochemical assessment and the in situ brain/choroid plexus perfusion technique in anesthetized mice. Results indicated that L-arginine and ADMA are tripolar cationic amino acids and have a gross charge at pH 7.4 of 0.981. L-Arginine (0.00149±0.00016) has a lower lipophilicity than ADMA (0.00226±0.00006) as measured using octanol-saline partition coefficients. The in situ perfusion studies revealed that [3H]-arginine and [3H]-ADMA can cross the blood-brain barrier (BBB) and the blood-CSF barrier. [3H]-Arginine (11.6nM) and [3H]-ADMA (62.5nM) having unidirectional transfer constants (Kin) into the frontal cortex of 5.84±0.86 and 2.49±0.35 μl.min-1.g-1, respectively, and into the CSF of 1.08±0.24 and 2.70±0.90 μl.min-1.g-1, respectively. In addition, multiple-time uptake studies revealed the presence of CNS-to-blood efflux of ADMA. Self- and cross-inhibition studies indicated the presence of transporters at the BBB and the blood-CSF barriers for both amino acids, which were shared to some degree. Importantly, these results are the first to demonstrate: (i) saturable transport of [3H]-ADMA at the blood-CSF barrier (choroid plexus) and (ii) a significant CNS to blood efflux of [3H]-ADMA. Our results suggest that the arginine paradox, in other words the clinical observation that NO-deficient patients respond well to oral supplementation with L-arginine even though the plasma concentration is sufficient to saturate endothelial NOS, could be related to altered ADMA transport (efflux).

CT measurement of blood perfusion in hepatocellular carcinoma: from basic principle, measurement methods to clinical application

Hepatocellular carcinoma (HCC) is one of the common and fatal malignant tumors worldwide, and the burden of HCC is particularly severe in China. Physiologically, the blood supply to healthy liver is mainly from the portal vein, supplemented by the hepatic artery. While in the development of HCC, the main source of blood supply to HCC is changed from the portal vein to the hepatic artery. The characteristics of HCC vascularization are important for imaging, surgery, interventional therapy, targeted therapy, etc. Even in the future, with the development of radiation therapy technology, such as proton and heavy ion therapy and artificial intelligence technology, the dynamic changes in HCC blood perfusion can be used as a new biomarker of tumor activity to provide accurate information on the intensity modulation of radiotherapy, so that accurate measurements of HCC blood perfusion is of great significance in guiding the diagnosis and treatment of HCC. The technologies for measurement of HCC blood perfusion have developed from invasive techniques, such as inert gas scavenging, electromagnetic flowmeter, and radionuclide-labeled erythrocyte elution in the middle of the last century to the present non-invasive techniques of CT. With the development of CT imaging technology in the last 30 years, the CT-based imaging technology can assess the status of organ and tissue perfusion relatively easily and accurately. In this paper, the various CT measurement techniques of blood perfusion in HCC were categorized into three types: semi-quantitative technique, relative quantitative technique, and absolute quantitative technique. Their basic principle, scanning methods, and clinical applications were discussed to provide a reference for the diagnosis and treatment of HCC.

Comparison of inferior vena cava puncture under continuous cardiac perfusion with cardiac puncture in blood acquisition of the laboratory mouse.

Obtaining sufficient blood volume from mice significantly facilitates experimental research. This study explored the inferior vena cava puncture under continuous cardiac perfusion (IVCP-UCCP) technique and evaluated its efficiency in comparison with conventional cardiac puncture (CP). In an initial dose-finding study, 50 mice were randomly assigned to one of 10 groups with escalating perfusion volume from 0.5 to 4.5 ml in 0.5-ml increments. The minimum perfusion volume was determined to be 2 ml in collecting whole circulating blood. In the next comparison using the conventional method, 40 mice were randomly assigned to one of two groups denoting different blood collection methods: Group 1: CP, Group 2: IVCP-UCCP. The results showed 1) that the cells and undiluted blood volume collected via IVCP-UCCP was over twofold higher than that by CP (p < 0.001), confirmed by the cell counts and hematoxylin-eosin staining of different tissues slides (p < 0.001); 2) the new technique did not alter the cellular composition or viability, which was verified by routine blood tests and flow cytometry (p > 0.05); 3) the blood collected via the novel technique was diluted 2.1 times: the hemato-biochemical indicator results multiplied by 2.1 were identical with the test results of blood from CP (p > 0.05). Together, the refined blood collection method of IVCP-UCCP completely extracted the limited blood resources in mice, significantly enhanced the utilization of each mouse, and thus offered scientific and ethical benefits. This technique may be also applicable for other small animal models.