Reference values and physiological characterization of a specific isolated pig kidney perfusion model

Precision arrows: Navigating breast cancer with nanotechnology siRNA

Nanotechnology-based drug delivery systems, including siRNA, present an innovative approach to treating breast cancer, which disproportionately affects women. These systems enable personalized and targeted therapies, adept at managing drug resistance and minimizing off-target effects. This review delves into the current landscape of nanotechnology-derived siRNA transport systems for breast cancer treatment, discussing their mechanisms of action, preclinical and clinical research, therapeutic applications, challenges, and future prospects. Emphasis is placed on the importance of targeted delivery and precise gene silencing in improving therapeutic efficacy and patient outcomes. The review addresses specific hurdles such as specificity, biodistribution, immunological reactions, and regulatory approval, offering potential solutions and avenues for future research. SiRNA drug delivery systems hold promise in revolutionizing cancer care and improving patient outcomes, but realizing their full potential necessitates ongoing research, innovation, and collaboration. Understanding the intricacies of siRNA delivery mechanisms is pivotal for designing effective cancer treatments, overcoming challenges, and advancing siRNA-based therapies for various diseases, including cancer. The article provides a comprehensive review of the methods involved in siRNA transport for therapeutic applications, particularly in cancer treatment, elucidating the complex journey of siRNA molecules from extracellular space to intracellular targets. Key mechanisms such as endocytosis, receptor-mediated uptake, and membrane fusion are explored, alongside innovative delivery vehicles and technologies that enhance siRNA delivery efficiency. Moreover, the article discusses challenges and opportunities in the field, including issues related to specificity, biodistribution, immune response, and clinical translation. By comprehending the mechanisms of siRNA delivery, researchers can design and develop more effective siRNA-based therapies for various diseases, including cancer.

Osmotic response during kidney perfusion with cryoprotectant in isotonic or hypotonic vehicle solution

Organ cryopreservation would revolutionize transplantation by overcoming the shelf-life limitations of conventional organ storage. To prepare an organ for cryopreservation, it is first perfused with cryoprotectants (CPAs). These chemicals can enable vitrification during cooling, preventing ice damage. However, CPAs can also cause toxicity and osmotic damage. It is a major challenge to find the optimal balance between protecting the cells from ice and avoiding CPA-induced damage. In this study, we examined the organ perfusion process to shed light on phenomena relevant to cryopreservation protocol design, including changes in organ size and vascular resistance. In particular, we compared perfusion of kidneys (porcine and human) with CPA in either hypotonic or isotonic vehicle solution. Our results demonstrate that CPA perfusion causes kidney mass changes consistent with the shrink-swell response observed in cells. This response was observed when the kidneys were relatively fresh, but disappeared after prolonged warm and/or cold ischemia. Perfusion with CPA in a hypotonic vehicle solution led to a significant increase in vascular resistance, suggesting reduced capillary diameter due to cell swelling. This could be reversed by switching to perfusion with CPA in isotonic vehicle solution. Hypotonic vehicle solution did not cause notable osmotic damage, as evidenced by low levels of lactate dehydrogenase (LDH) in the effluent, and it did not have a statistically significant effect on the delivery of CPA into the kidney, as assessed by computed tomography (CT). Overall, our results show that CPA vehicle solution tonicity affects organ size and vascular resistance, which may have important implications for cryopreservation protocol design.

Preclinical research performed on reanimated/perfused swine kidneys: The Visible Kidney™ methodologies

Preclinical research remains the essential platform in the development and optimization of medical therapies and advancements in translational medicines. However, specifically to animal research, federal laws, and institutional policies require investigators to apply the principles of the 3R's (replacement, reduction, and refinement). The concept of benchtop models utilizing isolated organs, in which multiple variables can be controlled to recreate human function, has been innovative advancements in preclinical research models that adhere to these principles. More specifically, isolated perfused kidney (IPK) models have been invaluable preclinical tools that have led to numerous advancements over the decades, including understanding renal physiology, pharmacologic therapies, and improvements in renal transplantation. However, pre-existing IPK models are not without their own limitations, leaving areas for improvement. An isolated perfused kidney apparatus was designed to best recreate human use conditions as a preclinical tool. Porcine renal blocks were chosen over the more commonly used rodent models, due to their greater similarities to human anatomies. Sixteen porcine kidney pairs obtained en bloc were extracted and placed onto an apparatus where aortic flows, pressures, and overall systemic temperatures were controlled. Organ viability was assessed in 10 renal blocks (n = 8 fresh and n = 2 previously frozen specimens) via both urinary flows and compositions at timepoints up to 180 min. Multimodality imaging, which included fluoroscopy, ultrasound, optical coherence tomography (OCT), and video scopes, was also employed to capture internal and external images to determine renal artery orientations and dimensions. Anatomical measurements and viability assessments of porcine renal blocks were successfully achieved in our perfusion model. Renal main artery diameters averaged smaller in our sample size than in human anatomy while also having more superior takeoff angles. Yet, the average lengths of each main segment were comparable to human anatomy: 32.09 ± 7.97 mm and 42.23 ± 7.33 mm in the left and right renal main artery, respectively. Urine production and urine composition of the fresh renal blocks, when compared to the frozen blocks and baseline perfusate, showed kidney viabilities of up to 3 h via excretion and retention of various metabolites. In this paper, we described a protocol for an isolated perfused kidney apparatus using large mammalian renal blocks. We believe this protocol to be an improvement from similar pre-existing models in better representing human physiologic function while allowing for multimodal imaging. The resulting Visible Kidney™ preclinical model, which has shown viability after isolation and reperfusion, can be a fast and reliable tool for the development of medical devices while also reducing the unnecessary use of animals for research.

Physiological aspects of pig kidney xenotransplantation and implications for management following transplant

Successful organ transplantation between species is now possible, using genetic modifications. This article aims to provide a comprehensive overview of the differences and similarities in kidney function between humans, primates, and pigs, in preparation for pig-allograft to human xenotransplantation. The kidney, as the principal defender of body homeostasis, acts as a sensor, effector, and regulator of physiologic feedback systems. Considerations are made for anticipated effects on each system when a pig kidney is placed into a human recipient. Discussion topics include anatomy, global kidney function, sodium and water handling, kidney hormone production and response to circulating hormones, acid-base balance, and calcium and phosphorus handling. Based on available data, pig kidneys are anticipated to be compatible with human physiology, despite a few barriers.

Growth Performance, Nutrient Digestibility, Blood Profiles, and Gut Integrity of Growing Pigs Fed Pickled Fish Residue with Decreased Salt Content

This study investigated the growth performance, nutrient digestibility, blood profiles and gut integrity of growing pigs, in response to an increase in pickled freshwater fish residue (PFR) intake following a decrease in salt content. Ninety-six crossbred growing pigs [(Landrace × Large White) × Duroc] with a body weight of 23.65 ± 0.24 kg were randomly assigned to one of four treatments (6 pens/treatment, 4 pigs/pen) in a randomized complete block design. The treatments included: a corn-soybean meal based diet without PFR inclusion (CON) or with PFR addition at 5 (PFR5), 10 (PFR10), and 15% (PFR15), respectively. Desalting via soaking and stirring caused a positive reduction in the salt present on the surface of PFR. Over the 42-day feeding period, an increased level of PFR quadratically increased gain:feed ratio such that gain:feed ratio for PFR10 was greater than that for CON (p < 0.05). Pigs fed PFR10 had greater crude protein digestibility, and lower aspartate aminotransferase and crypt depth than those fed the CON diet (p < 0.05). The linear improvements in crude protein and ether extract digestibility, duodenal villus height, and villus:crypt ratio were observed as the PFR content increased (p < 0.05). However, there were no significant effects on average daily feed intake, dry matter and ash digestibility, blood metabolites (total Ca, P, creatinine, and alkaline phosphatase). Altogether, up to 10% PFR can be included in corn-soybean meal diet without impairing protein digestibility and hepatic enzyme alteration. In fact, administering PFR with lower salt content to growing pigs ultimately promotes their growth performance and gut integrity.

Inulin Clearance During Ex vivo Normothermic Machine Perfusion as a Marker of Renal Function

Normothermic machine perfusion (NMP) offers a unique opportunity to objectively assess donor organ quality. This study describes the evaluation of inulin clearance as a potential marker for the ex vivo function of porcine kidneys during NMP. The function assessment was performed in both kidneys from slaughterhouse pigs (n = 20) and kidneys from pigs in a laboratory setting (n = 28). The kidneys were exposed to different warm ischemia times (WIT). After a period of static cold storage, the kidneys underwent a 4-hour NMP with autologous whole blood. Inulin clearance, hemodynamic parameters, and urine output were measured. Based on the inulin excretion behavior laboratory pig kidneys were assigned to three classes (functional, limited functional, and nonfunctional), slaughterhouse pig kidneys to two classes (limited functional and nonfunctional), respectively. Contrary to the marginal kidneys of the slaughterhouse pigs, the functional variation of kidneys of the laboratory pigs was associated with the WIT. A correlation between functional kidneys and a WIT less than 25 min was shown. Because none of the slaughterhouse pig kidneys could be assigned to the functional class, only the laboratory pig kidneys were used for examinations with functional markers. Renal blood flow and urine output during NMP correlated significantly (p < 0.01) with ex vivo kidney function. This study demonstrated that inulin is a marker of high quality for the evaluation of suggested kidney function after NMP with whole blood. Furthermore, surrogate markers measured during NMP can be used to describe and predict the physiologic behavior of kidneys before transplantation.

Microbial inhibition and biosensing with multifunctional carbon dots: Progress and perspectives

Carbon dots (CDs) and their doped counterparts including nitrogen-doped CDs (N@CDs) have been synthesized by bottom-up or top-down approaches from different precursors. The attractiveness of such emerging 2D‑carbon-based nanosized materials is attributed to their excellent biocompatibility, preparation, aqueous dispersibility, and functionality. The antimicrobial, optical, and electrochemical properties of CDs have been advocated for two important biotechnological applications: bacterial eradication and sensing/biosensing. CDs as well as N@CDs act as antimicrobial agents as their surfaces encompass functional hydroxyl, carboxyl, and amino groups that generate free radicals. As a new class of photoluminescent nanomaterials, CDs can be employed in diversified analytics. CDs with surface carboxyl or amino groups form nanocomposites with nanomaterials or be conjugated with biorecognition molecules toward the development of sensors/biosensors. The deployment of conductive CDs in electrochemical sensing has also increased significantly because of their quantum size, excellent biocompatibility, enzyme-mimicking activity, and high surface area. The review also addresses the ongoing challenges and promises of CDs in pathogenesis and analytics. Perspectives on the future possibilities include the use of CDs in microbial viability assay, wound healing, antiviral therapy, and medical devices.

Normothermic machine perfusion of ischaemically damaged porcine kidneys with autologous, allogeneic porcine and human red blood cells

In porcine kidney auto-transplant models, red blood cells (RBCs) are required for ex-vivo normothermic machine perfusion (NMP). As large quantities of RBCs are needed for NMP, utilising autologous RBCs would imply lethal exsanguination of the pig that is donor and recipient-to-be in the same experiment. The purpose of this study was to determine if an isolated porcine kidney can also be perfused with allogeneic porcine or human RBCs instead. Porcine kidneys, autologous and allogeneic blood were obtained from a local slaughterhouse. Human RBCs (O-pos), were provided by our transfusion laboratory. Warm ischaemia time was standardised at 20 minutes and subsequent hypothermic machine perfusion lasted 1.5–2.5 hours. Next, kidneys underwent NMP at 37°C during 7 hours with Williams' Medium E and washed, leukocyte depleted RBCs of either autologous, allogeneic, or human origin (n = 5 per group). During perfusion all kidneys were functional and produced urine. No macroscopic adverse reactions were observed. Creatinine clearance during NMP was significantly higher in the human RBC group in comparison with the allogeneic group (P = 0.049) but not compared to the autologous group. The concentration of albumin in the urine was significantly higher in the human RBC group (P <0.001) compared to the autologous and allogeneic RBC group. Injury marker aspartate aminotransferase was significantly higher in the human RBC group in comparison with the allogeneic group (P = 0.040) but not in comparison with the autologous group. Renal histology revealed glomerular and tubular damage in all groups. Signs of pathological hyperfiltration and microvascular injury were only observed in the human RBC group. In conclusion, perfusion of porcine kidneys with RBCs of different origin proved technically feasible. However, laboratory analysis and histology revealed more damage in the human RBC group compared to the other two groups. These results indicate that the use of allogeneic RBCs is preferable to human RBCs in a situation where autologous RBCs cannot be used for NMP.

Combined protective effect of zinc oxide nanoparticles and melatonin on cyclophosphamide-induced toxicity in testicular histology and sperm parameters in adult Wistar rats

BACKGROUND

Cyclophosphamide (CP) has been known as an anticancer drug with several side effects on various organs such as a male reproductive system that can cause infertility.

OBJECTIVE

To evaluate the possible combined effects of zinc oxide nanoparticles (nZno) and melatonin (Mel) on sperm parameters and histopathological changes of the testis in CP-treated rats.

MATERIALS AND METHODS

42 adult male Wistar rats were divided into six groups. GI: control, GII: 60 mg/kg/wk CP, GIII and GIV, 10 mg/kg/wk Mel and 5mg/kg/wk nZno and GV: 5 mg/kg/wk nZno and 10 mg/kg/wk Mel were given 2 hr prior to CP injection, respectively,GVI: 5mg/kg/wk nZno and 10 mg/kg/wk Mel simultaneously. After 8 wk of treatment, rats were sacrificed and testis and epididymis were harvested for further evaluation.

RESULTS

The CP-treated group showed significant decreases in the body, testes and epididymis weights and sperm parameters (sperm count, viability, motility) with an increase abnormal sperms when compared with the control (p<0.001), as well as many histological alterations included decreased diameters of seminiferous tubules and Johnsen's Testicular Score (with degeneration, desquamation, multi-nucleated giant cell formation), whereas combined treatment (GV), showed more protective effects on CP-induced reproductive system damage compared with groups III or IV (p<0.001).

CONCLUSION

These results suggest simultaneous administration of Mel and nZno have more effectively protections against CP-induced reproductive damage than Mel or nZno alone.

Comparison of normothermic and hypothermic perfusion in porcine kidneys donated after cardiac death

BACKGROUND

Normothermic machine perfusion (NMP) is an alternative strategy for preserving kidneys donated after cardiac death (DCD). The relative efficacy of prolonged NMP compared to hypothermic machine perfusion (HMP) in DCD kidneys with moderate ischemic injury is undetermined. This study compares NMP and HMP kidney preservation in a porcine DCD model.

METHODS

Ten porcine kidneys underwent NMP or HMP preservation following 45 minutes of warm ischemia and 5 hours of cold ischemia. After 8 hours of machine preservation, hemodynamic stability, renal function, perfusate biomarkers, and histologic integrity were assessed in a simulated reperfusion model.

RESULTS

During simulated reperfusion, no differences were observed in oxygen consumption, urine production, creatinine clearance, fractional excretion of sodium, proteinuria, and perfusate levels of lactate dehydrogenase and aspartate aminotransferase. Resistance was no different after 30 minutes of simulated reperfusion. Histologically, NMP kidneys demonstrated increased vacuolization after preservation and greater loss of tubular integrity after simulated reperfusion. Perfusate levels of alkaline phosphatase (AP) and gamma glutamyltransferase (GGT) were higher in NMP kidneys during preservation, but upon simulated reperfusion, AP and GGT levels were higher in HMP-preserved kidneys. Peak AP and GGT during simulated reperfusion of HMP kidneys were over 14 times higher than peak AP and GGT during preservation of NMP kidneys.

CONCLUSIONS

NMP provided comparable preservation of renal function as HMP and minimized AP and GGT release upon reperfusion.

Assessment of fundamental movement patterns and risk of injury in male soccer players

Introduction. The aim of the study was to assess the functional status of male soccer players in different age groups who played on different surfaces. Methods. The study included 45 soccer players aged 13-35 years. Among them, 15 were junior players, 15 were players of the senior Silesia-Opole 3rd league (SL), and 15 were senior players in the futsal Extra Class league (SF). The functional status and basic motor skills were assessed according to the results obtained in seven motor tasks included in the Functional Movement Screen™ (FMS) test. Results. The mean total scores in the FMS test were statistically significantly higher among both senior futsal and senior 3

Impact of high doses of 6% hydroxyethyl starch 130/0.42 and 4% gelatin on renal function in a pediatric animal model

OBJECTIVES

Despite serious renal side effects in critically ill adult patients, artificial colloids are still fundamental components of perioperative fluid therapy in infants and children, although the impact of 6% hydroxyethyl starch (HES) and 4% gelatin (GEL) on renal function during pediatric surgery has not been identified yet.

AIM

To determine the impact of high doses of artificial colloids on renal function, we conducted an experimental animal study and hypothesized that neither the infusion of HES nor of GEL would have a serious impact on renal function.

METHODS

Fifteen sedated piglets were randomly assigned to receive an infusion of either 50 ml · kg(-1) HES or GEL, or a balanced electrolyte solution (crystalloid group). Before and 1 week after infusion, serum and urine renal function tests were recorded and renal biopsies were taken.

RESULTS

Serum and urine renal function tests revealed no increase after administration of HES and GEL, and only a discrete increase in serum creatinine (median 9.8 μmol · l(-1), 95% CI 4.0-19.1) in the crystalloid group. Histopathological examination indicated a sparsely, multifocal infiltration of mononuclear cells in all groups and an unspecific pyelectasia of one animal in the GEL group.

CONCLUSIONS

After high doses of HES or GEL in piglets, no relevant impact on renal function could be found. These results confirm that AKI after HES or GEL is very unlikely in hemodynamically stable perioperative patients with normal renal function.

Determination of the Preferred Conditions for the Isolated Perfusion of Porcine Kidneys

Background: The isolated perfused porcine kidney (IPPK) model has been the method of choice for the early preclinical evaluation of kidney graft preservation techniques. The preferred reperfusion conditions have not yet been determined. Here, we examined the effects of pressure- or flow-controlled perfusion and oxygenation by pure oxygen or carbogen (95% O2/5% CO2) on normothermic reperfusion in the IPPK model. Methods: Porcine kidneys were cold-stored for 24 h in histidine-tryptophan-ketoglutarate solution and reperfused for 1 h with normothermic whole blood/Krebs-Henseleit buffer medium (20/80%). Kidneys (n = 5/group) were flow-controlled reperfused with pure oxygen (1 ml/min/g; Flow-O2) or pressure-controlled reperfused (85 mm Hg mean arterial pressure) and oxygenated with either pure oxygen (Pressure-O2) or carbogen (Pressure-O2/CO2). Renal function and damage were assessed during reperfusion and NGAL and HIF-1α levels were analyzed using an ELISA. Results: Pressure-O2 and Pressure-O2/CO2 were associated with significantly better renal hemodynamics and acid-base homeostasis compared to Flow-O2. Urine protein concentrations and the fractional excretion of sodium were lower with both Pressure-O2 and Pressure-O2/CO2 than with Flow-O2. NGAL and HIF-1α levels were also lower with Pressure-O2 and Pressure-O2/CO2 than with Flow-O2. Only Pressure-O2/CO2 could demonstrate a significantly increased urine production compared to Flow-O2. The structural integrity was well preserved in the Pressure-O2 and Pressure-O2/CO2 groups, whereas diffuse and global glomerular destruction was observed in the Flow-O2 group. Conclusion: In the IPPK model, the application of pressure-controlled reperfusion with carbogen oxygenation, and to a lesser extent with pure oxygen, maintained physiological renal function for 1 h, thus providing a reliable and reproducible ex vivo evaluation of kidney preservation quality.

Impact of 6% hydroxyethyl starch 130/0.42 and 4% gelatin on renal function in a pediatric animal model

OBJECTIVES

Artificial colloids, frequently used to prevent hemorrhagic shock in children, may induce serious renal side effects in critically ill adult patients. The impact of perioperative colloid infusion on the renal function in adults and children remains unclear.

AIM

To determine the impact of single doses of artificial colloids on renal function tests, we conducted an experimental animal study. We hypothesized that neither the infusion of moderate doses of 6% hydroxyethyl starch (HES) nor of 4% gelatin (GEL) would have a serious impact on the renal function of healthy piglets.

METHODS

Fifteen sedated piglets were randomly assigned to receive an infusion of either 20 ml·kg(-1) HES or GEL or a balanced electrolyte solution (BS, control group) over 30 min. Before and 7 days after infusion, serum and urine renal function tests were recorded and renal biopsies were taken.

RESULTS

Serum and urine renal function tests (e.g., creatinine, urea, cystatin C, and neutrophil gelatinase-associated lipocalin) were within normal ranges, and a microscopic examination of the renal tissue in all groups revealed no major alterations such as tubular necrosis, interstitial bleeding, interstitial inflammation, or vacuoles.

CONCLUSIONS

In this pediatric animal model, the infusion of moderate doses of artificial colloids was not found to have any relevant impact on renal function. Further clinical investigations are necessary to provide a conclusive assessment of the risk for renal impairment after HES and GEL administration during major pediatric surgery.

The autologous normothermic ex vivo perfused porcine liver-kidney model: improving the circuit's biochemical and acid-base environment

BACKGROUND

The ex vivo porcine liver perfused model isolates the organ from extrinsic regulatory mechanisms, facilitating an improved understanding of the organ physiology and reaction to various conditions. We have assessed the influence of the addition of a porcine kidney to the circuit.

METHODS

Eight livers were harvested and perfused for 6 hours. In 5 additional experiments a kidney also was connected in parallel. Hourly arterial blood gases were collected to analyze glucose, acid base, and renal parameters. The primary end point was an evaluation of the influence of the kidney on glucose, pH, and electrolyte levels.

RESULTS

In the combined porcine liver-kidney circuit all the parameters significantly improved compared with the liver circuit alone. This was particularly evident for glucose values because normoglycemia was reached by the end of the perfusion, and for pH and electrolyte values that were maintained at initial levels.

CONCLUSIONS

The addition of a porcine kidney to the perfusion circuit improves the biochemical milieu. This might produce more consistent and reliable results, particularly during studies requiring a steady-state environment.

Nanosized multifunctional liposomes for tumor diagnosis and molecular imaging by SPECT/CT

Among currently used cancer imaging methods, nuclear medicine modalities provide metabolic information, whereas modalities in radiology provide anatomical information. However, different modalities, having different acquisition times in separate machines, decrease the specificity and accuracy of images. To solve this problem, hybrid imaging modalities were developed as a new era, especially in the cancer imaging field. With widespread usage of hybrid imaging modalities, specific contrast agents are essentially needed to use in both modalities, such as single-photon emission computed tomography/computed tomography (SPECT/CT). Liposomes are one of the most desirable drug delivery systems, depending on their suitable properties. The aim of this study was to develop a liposomal contrast agent for the diagnosis and molecular imaging of tumor by SPECT/CT. Liposomes were prepared nanosized, coated with polyethylene glycol to obtain long blood circulation, and modified with monoclonal antibody 2C5 for specific tumor targeting. Although DTPA-PE and DTPA-PLL-NGPE (polychelating amphilic polymers; PAPs) were loaded onto liposomes for stable radiolabeling for SPECT imaging, iopromide was encapsulated into liposomes for CT imaging. Liposomes [(DPPC:PEG(2000)-PE:Chol:DTPA-PE), (PL 90G:PEG(2000)-PE:Chol:DTPA-PE), (DPPC:PEG(2000)-PE:Chol:PAPs), (PL 90G:PEG(2000)-PE:Chol:PAPs), (60:0.9:39:0.1% mol ratio)] were characterized in terms of entrapment efficiency, particle size, physical stability, and release kinetics. Additionally, in vitro cell-binding studies were carried out on two tumor cell lines (MCF-7 and EL 4) by counting radioactivity. Tumor-specific antibody-modified liposomes were found to be effective multimodal contrast agents by designating almost 3-8 fold more uptake than nonmodified ones in different tumor cell lines. These results could be considered as an important step in the development of tumor-targeted SPECT/CT contrast agents for cancer imaging.

Biological alterations and self-reported symptoms among insecticides-exposed workers in Burkina Faso

Occupationally exposed workers, farm workers and plant protection agents in the Sahel region of Burkina Faso were interviewed to assess adverse health effects of insecticides. The subjects were also examined for changes in both hematological and biochemical parameters. The prevalence of liver and kidney dysfunction was found to be quite high among insecticide applicators, especially among plant protection agents. The prevalence of biochemical alterations seems to be correlated to the frequency of insecticide use. However, no significant differences were found between the hematological parameters among farm workers and plant protection agents. The hematological parameters of all the insecticide applicators were normal. The great majority of insecticide applicators (85%) reported symptoms related to insecticide exposure. The use of insecticides in the agriculture of Burkina Faso is threatening to human health.

Resuscitation of warm ischaemia predamaged porcine kidneys by fibrinolytic preflush with streptokinase: reduction of animal experiments

In order to reduce the number of animal experiments, the use of non-heart-beating donors (NHBDs) from a commercial abattoir has been proposed. Since the use of slaughterhouse organs is legally not defined as animal experiment, this would fulfil international standards as an alternative to animal experiments. The development of intravascular thrombosis after cardiac arrest negatively impacts organ preservation and thus viability during ischaemic storage and reperfusion. A fibrinolytic preflush with streptokinase might overcome these limitations. Therefore, the functional and histomorphological integrity of kidneys preserved immediately with intact circulation (control group A) and kidneys preserved after cardiac arrest with a 30 min period of warm ischaemia (WI) (group B) was compared with kidneys preflushed with 12.5 kU/L (group C) or 50 kU/L streptokinase (group D) after 30 min WI prior to preservation. We could demonstrate that kidneys preflushed with 12.5 kU/L streptokinase (group C) performed better than those without streptokinase pretreatment after WI (group B). Parameters like oxygen consumption, perfusion pressure, laboratory values, lactate dehydrogenase level and lipidperoxidation were closer to that of the control (group A) than in groups B and D. The higher streptokinase concentration of 50 kU/L (group D) resulted histologically in a more pronounced tissue damage and an attenuated renal function, indicating toxic effects. On the basis of our results we believe streptokinase preflushed slaughterhouse kidneys to be an adequate alternative to organs from laboratory animals with the potential to further reduce the number of animal experiments.

Anatomical particularities of the porcine immune system--a physician's view

In this article the anatomical structure of the porcine immune organs is described. The focus is on their particularities that are related to the use of pigs as an animal model. Key issues of the intrauterine development of the lymphoid organs are presented, such as the specific epithelio-chorial placenta, the appearance of the thymic tissue and the initial development of B cells. The role of the thymus for the development of alpha/beta and gamma/delta T cells and the location of tonsillar tissue in the naso-pharynx, in the oral cavity and at the basis of the tongue are described. The porcine spleen is of interest for surgical techniques to treat splenic trauma adequately. The observation of the inverted lymph node structure of pigs is puzzling and it remains unclear why only few species have this distinct morphological organisation. Based on the functional differences in lymphocyte recirculation observed in pigs, specific lymph cannulation experiments are possible in the porcine immune system. The porcine intestinal lymphoid tissue and the lymphocytes in the mucosal epithelium and lamina propria are of interest for studying the gut immune responses. For use as a model the fact that the pig is a monogastric omnivorous animal represents an advantage, although the porcine ileal Peyer's patch has no obvious anatomical equivalent in man. Based on the detailed knowledge of porcine immune morphology the pig is suitable as model animal for immunology--in addition to the various experimental approaches in physiology, pharmacology, surgery, etc. that are applicable to human medicine.