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Background. The hemodynamic effects of aortic arch vessel (AAV) clamping during normothermic regional perfusion (NRP) in donation after circulatory death is unknown. We investigated effects of AAV clamping during NRP compared with no clamping in a porcine model.Methods. In 16 pigs, hemodynamic parameters were recorded including biventricular pressure-volume measurements and invasive blood pressure. Additionally, blood gas parameters and inflammatory cytokines were used to assess the effect of AAV clamping. The animals were centrally cannulated for NRP, and baseline measurements were obtained before hypoxic circulatory arrest was induced by halting mechanical ventilation. During an 8-min asystole period, the animals were randomized to clamp (n = 8) or no-clamp (n = 8) of the AAV before commencement of NRP. During NRP, circulation was supported with norepinephrine (NE) and dobutamine. After 30 min of NRP, animals were weaned and observed for 180 min post-NRP.Results. All hearts were successfully reanimated and weaned from NRP. The nonclamp groups received significantly more NE to maintain a mean arterial pressure >60 mm Hg during and after NRP compared with the clamp group. There were no between group differences in blood pressure or cardiac output. Pressure-volume measurements demonstrated preserved cardiac function‚ including ejection fraction and diastolic and systolic function. No between group differences in inflammatory markers were observed.Conclusions. AAV clamping did not negatively affect donor cardiac function or inflammation after circulatory death and NRP. Significantly less NE was used to support in the clamp group than in the nonclamp group.

BACKGROUND: Thoracoabdominal normothermic regional perfusion (NRP) is a new method for in situ reperfusion and reanimation of potential donor organs in donation after circulatory death by reperfusion of the thoracic and abdominal organs with oxygenated blood. We investigated effects of high oxygenation (HOX) versus low oxygenation (LOX) during NRP on donor heart function in a porcine model.METHODS: Pigs (80 kg) underwent a 15-min anoxic cardiac arrest followed by cardiac reanimation on NRP using a heart-lung bypass machine with subsequent assessment 180 minutes post-NRP. The animals were randomized to HOX (FiO2 1.0) or LOX (FiO2 0.21 increased to 0.40 during NRP). Hemodynamic data were obtained by invasive blood pressure and biventricular pressure-volume measurements. Blood gases, biomarkers of inflammation, and oxidative stress were measured.RESULTS: Eight of 9 animals in the HOX group and 7 of 10 in the LOX group were successfully weaned from NRP. Right ventricular end-systole elastance was significantly improved in the HOX group compared with the LOX group, whereas left ventricular end-systole elastance was preserved at baseline levels. Post-NRP cardiac output, mean arterial, central venous, and pulmonary capillary wedge pressure were all comparable to baseline. Creatinine kinase-MB increased more in the LOX group than the HOX group, whereas proinflammatory cytokines increased more in the HOX group than the LOX group. No difference was found in oxidative stress between groups.CONCLUSIONS: All hearts weaned from NRP showed acceptable hemodynamic function for transplantation. Hearts exposed to LOX showed more myocardial damage and showed poorer contractile performance than hearts reperfused with high oxygen.

BACKGROUND: We aimed to investigate the effect of epinephrine vs placebo on return of spontaneous circulation (ROSC) and brain magnetic resonance spectroscopy and imaging (MRS/MRI) in newborn piglets with hypoxic cardiac arrest (CA).METHODS: Twenty-five piglets underwent hypoxia induced by endotracheal tube clamping until CA. The animals were randomized to CPR + intravenous epinephrine or CPR + placebo (normal saline). The primary outcome was ROSC, and secondary outcomes included time-to-ROSC, brain MRS/MRI, and composite endpoint of death or severe brain MRS/MRI abnormality.RESULTS: ROSC was more frequent in animals treated with epinephrine than placebo; 10/13 vs 4/12, RR = 2.31 (95% CI: 1.09-5.77). We found no difference in time-to-ROSC (120 (113-211) vs 153 (116-503) seconds, p = 0.7) or 6-h survival (7/13 vs 3/12, p = 0.2). Among survivors, there was no difference between groups in brain MRS/MRI. We found no difference in the composite endpoint of death or severe brain MRS/MRI abnormality; RR = 0.7 (95% CI: 0.37-1.19).CONCLUSIONS: Resuscitation with epinephrine compared to placebo improved ROSC frequency after hypoxic CA in newborn piglets. We found no difference in time-to-ROSC or the composite endpoint of death or severe brain MRS/MRI abnormality.IMPACT: In a newborn piglet model of hypoxic cardiac arrest, resuscitation with epinephrine compared to placebo improved the rate of return of spontaneous circulation and more than doubled the 6-h survival. Brain MRS/MRI biomarkers were used to evaluate the effect of epinephrine vs placebo. We found no difference between groups in the composite endpoint of death or severe brain MRS/MRI abnormality. This study adds to the limited evidence regarding the effect and safety of epinephrine; the lack of high-quality evidence from randomized clinical trials was highlighted in the latest ILCOR 2020 guidelines, and newborn animal studies were specifically requested.

The immunomodulatory and regenerative properties of mesenchymal stromal cells (MSCs) make MSC therapy a promising therapeutic strategy in kidney disease. A targeted MSC administration via the renal artery offers an efficient delivery method with limited spillover to other organs. Although local administration alleviates safety issues with MSCs in systemic circulation, it introduces new safety concerns in the kidneys. In a porcine model, we employed intra-renal arterial infusion of ten million allogenic adipose tissue-derived MSCs. In order to trigger any potential adverse events, a higher dose (hundred million MSCs) was also included. The kidney function was studied by magnetic resonance imaging after the MSC infusion and again at two weeks post-treatment. The kidneys were assessed by single kidney glomerular filtration rate (skGFR) measurements, histology and inflammation, and fibrosis-related gene expression. None of the measured parameters were affected immediately after the administration of ten million MSCs, but the administration of one hundred million MSCs induced severe adverse events. Renal perfusion was reduced immediately after MSC administration which coincided with the presence of microthrombi in the glomeruli and signs of an instant blood-mediated inflammatory reaction. At two weeks post-treatment, the kidneys that were treated with one hundred million MSCs showed reduced skGFR, signs of tissue inflammation, and glomerular and tubular damage. In conclusions, the intra-renal administration of ten million MSCs is well-tolerated by the porcine kidney. However, higher concentrations (one hundred million MSCs) caused severe kidney damage, implying that very high doses of intra-renally administered MSCs should be undertaken with caution.

BACKGROUND: Insufficient fluid administration intra- and postoperatively may lead to delayed renal graft function (DGF), while fluid overload increases the risk of heart failure, infection, and obstipation. Several different fluid protocols have been suggested to ensure optimal fluid state. However, there is a lack of evidence of the clinical impact of these regimens. This study aimed to determine whether individualized goal-directed fluid therapy (IGDT) positively affects the initial renal function compared to a high-volume fluid therapy (HVFT) and to examine the effects on renal endothelial glycocalyx, inflammatory and oxidative stress markers, and medullary tissue oxygenation. The hypothesis was that IGDT improves early glomerular filtration rate (GFR) in pigs subjected to renal transplantation.METHODS: This was an experimental randomized study. Using a porcine renal transplantation model, animals were randomly assigned to receive IGDT or HVFT during and until 1 hour after transplantation from brain-dead donors. The kidneys were exposed to 18 hours of cold ischemia. The recipients were observed until 10 hours after reperfusion, which included GFR measured as clearance of chrom-51-ethylendiamintetraacetat (Cr-EDTA), animal weight, and renal tissue oxygenation by fiber optic probes. The renal expression of inflammatory and oxidative stress markers as well as glomerular endothelial glycocalyx were analyzed in the graft using polymerase chain reaction (PCR) technique and immunofluorescence.RESULTS: Twenty-eight recipient pigs were included for analysis. We found no evidence that IGDT improved early GFR compared to HVFT (P = .45), while animal weight increased more in the HVFT group (a mean difference of 3.4 kg [1.96-4.90]; P < .0001). A better, however nonsignificant, preservation of glomerular glycocalyx (P = .098) and significantly lower levels of the inflammatory marker cyclooxygenase 2 (COX-2) was observed in the IGDT group when compared to HVFT. COX-2 was 1.94 (1.50-2.39; P = .012) times greater in the HVFT group when compared to the IGDT group. No differences were observed in outer medullary tissue oxygenation or oxidative stress markers.CONCLUSIONS: IGDT did not improve early GFR; however, it may reduce tissue inflammation and could possibly lead to preservation of the glycocalyx compared to HVFT.

HyperpolarizedIn the present study, we use this technique to characterize the metabolic fate of hyperpolarized [1-We demonstrate a fivefold elevation of the whole-body lactate-to-pyruvate ratio in digesting snakes, pointing to a large rise in lactate production from pyruvate. Consistent with the well-known metabolic stimulation of digestion, measurements of mitochondrial respiration in hepatocytes in vitro indicate a marked postprandial upregulation of mitochondrial respiration. We observed that a low SNR of the hyperpolarizedWe confirm the large postprandial rise in the wet mass of most visceral organs, except for the heart, and demonstrated that it is possible to image the [1

Systemic Intermittent Hypoxic Therapy (IHT) relies on the adaptive response to hypoxic stress. We investigated allogenic bone-graft resorption in the lumbar spine in 48 mice. The mice were exposed to IHT for 1 week before surgery or 1 week after surgery and compared with controls after 1 and 4 weeks. Complete graft resorption was observed in 33–36% of the animals in the control group, but none in the preoperative IHT group. Increased bone-graft volume was demonstrated by micro-computed tomography in the preoperative IHT group after 1 week (p = 0.03) while a non-significant difference was observed after 4 weeks (p = 0.12). There were no significant differences in the postoperative IHT group. Increased concentration of immune cells was localized in the graft area, and more positive tartrate-resistant acid phosphatase (TRAP) staining was found in controls compared with IHT allogenic bone grafts. Systemic IHT resulted in a significant increase of the major osteoclast inhibitor osteoprotegerin as well as osteogenic and angiogenic regulators Tgfbr3, Fst3l, Wisp1, and Vegfd. Inflammatory cytokines and receptor activator of nuclear factor kappa-B ligand (RANKL) stimulators IL-6, IL-17a, IL-17f, and IL-23r increased after 1 and 4 weeks, and serum RANKL expression remained constant while Ccl3 and Ccl5 decreased. We conclude that the adaptive response to IHT activates numerous pathways leading to inhibition of osteoclastic activity and inhibition of allogenic bone-graft resorption.

Purpose: To evaluate the causality between interventions on spinal cord perfusion pressure and neurological outcome in traumatic spinal cord injury.Methods: A systematic review was conducted in concordance with PRISMA guidelines. The literature was found in the EMBASE, PUBMED, SCOPUS, and WEB OF SCIENCE. Eligible studies included those that reported measurements and interventions on the spinal cord perfusion pressure in either animals or patients suffering from spinal cord injury. Only studies that reported a clinical or relevant clinical outcome measure (i.e., neurophysiology) were included.Results: The search yielded 795 unique records, and six studies were included after careful review. These studies suggested a positive correlation between spinal cord perfusion pressure and neurological outcome, but conclusions on causality could not be made.Conclusion: In spite of growing indications that neurological outcomes are related to the spinal cord perfusion pressure in traumatic spinal cord injuries, a solid conclusion cannot be made due to the limited literature available. Additional well-designed studies are needed to address this issue.Keywords: Critical care; Decompression; Spinal cord injury; Spinal cord perfusion pressure; Spinal surgery; Trauma.

There are a variety of devices that quantify biological properties of cerebral tissue. Installing such device will cause a local insertion trauma, which will affect early measurements. Current literature proposes minimum one hour of observation before acquiring first measurements when using microdialysis. It is unknown whether this applies to other intracerebral devices. We therefore aimed to investigate time needed to reach steady state when using microdialysis and two intracerebral probes in a piglet model. Ten newborn piglets less than 24 hours of age were anaesthetized. Two probes (Codman and OxyLite/OxyFlo) and a microdialysis catheter (CMA Microdialysis) were installed 10 mm into the left hemisphere. Probes measured intracranial pressure, cerebral blood flow, and oxygen tension. The microdialysis catheter measured lactate, glucose, glycerol, and pyruvate. Measurements were acquired hourly for 20 hours. Lactate and glycerol peaked immediately after insertion and reached steady state after approximately four hours. Glucose, pyruvate, cerebral blood flow, and intracranial pressure reached steady state immediately. Oxygen tension reached steady state after 12 hours. With time, interindividual variability decreased for the majority of measurements. Consequently, time to stabilization after insertion depends on the choice of device and is crucial to obtain valid baseline values with high degree of precision.

Bromer, Frederik Duch, Mikkel Bo Brent, Michael Pedersen, Jesper Skovhus Thomsen, Annemarie Brüel, and Casper Bindzus Foldager. The effect of normobaric intermittent hypoxia therapy on bone in normal and disuse osteopenic mice. High Alt Med Biol. 22 225-234, 2021. Background Systemic intermittent hypoxia therapy (IHT) has been shown to elicit beneficial effects on multiple physiological systems. However, only few studies have investigated the effect of long-term normobaric IHT on bone mass and mechanical and microstructural properties. The aim of the present study was to examine the effect of IHT on bone in both healthy and osteopenic mice. Materials and Methods Thirty mice were stratified into four groups Ctrl, Ctrl+IHT, Botox, and Botox+IHT. Osteopenia was induced by injecting Botox into the right hindlimb of the mice causing paralysis and disuse. IHT animals were placed in a normobaric hypoxia-chamber (10% oxygen) for 1 hour twice daily 5 days/week. Animals were sacrificed after 21 days, and DEXA, micro-computed tomography, and mechanical testing were performed on the femora. Results As expected, Botox resulted in a significant reduction of bone mineral content (-23.4%), area bone mineral density (-19.1%), femoral neck strength (Fmax -54.7%), bone volume fraction (bone volume/tissue volume -41.8%), and trabecular thickness (-32.4%). IHT had no measurable effect on the bone properties in either healthy or osteopenic mice. Conclusion The study confirmed that Botox led to loss of bone mass, deterioration of trabecular microstructure, and loss of bone strength. These changes were not influenced by IHT. Notably, IHT had no detrimental effect on bone in either healthy or osteopenic mice. This indicates that IHT of ailments outside of the skeletal system may be administered without causing harm to the bone.

The annual death statistics due to vector-borne diseases transmitted by Aedes mosquitoes cause a still growing concern for the public health in the affected regions. An improved understanding of how climatic and population changes impact the spread of Aedes aegypti will help estimate the future populations exposure and vulnerability, and is essential to the improvement of public health preparedness. We apply an empirically well-investigated process-based mathematical model based on the life cycle of the mosquito to assess how climate scenarios (Representative Concentration Pathways (RCP)) and population scenarios (Shared Socioeconomic Pathways (SSP)) will affect the growth and potential distribution of this mosquito in China. Our results show that the risk area is predicted to expand considerably, increasing up to 21.46% and 24.75% of China's land area in 2050 and 2070, respectively, and the new added area lies mainly in the east and center of China. The population in the risk area grows substantially up to 2050 and then drops down steadily. However, these predicted changes vary noticeably among different combinations between RCPs and SSPs with the RCP2.6*SSP4 yielding the most favorable scenario in 2070, representing approximately 14.11% of China's land area and 113 cities at risk, which is slightly lower compared to 2019. Our results further reveal that there is a significant trade-off between climatic and human population impacts on the spreading of Aedes aegypti, possibly leading to an overestimation (underestimation) in sparsely (densely) populated areas if the populations impact on the mosquito's life history is unaccounted for. These results suggest that both climate and population changes are crucial factors in the formation of the populations exposure to Aedes-borne virus transmission in China, however, a reduced population growth rate may slow down the spread of this mosquito by effectively counteracting the climate warming impacts.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can provide a noninvasive way for assessing renal functional information following the administration of a small molecular weight gadolinium-based contrast agent. This method may be useful for investigating renal perfusion and glomerular filtration rates of rodents in vivo under various experimental (patho)physiological conditions. Here we describe a step-by-step protocol for DCE-MRI studies in small animals providing practical notes on acquisition parameters, sequences, T1 mapping approaches and procedures.This chapters is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol chapter is complemented by two separate chapters describing the basic concept and data analysis.

Dynamic contrast-enhanced (DCE) MRI monitors the transit of contrast agents, typically gadolinium chelates, through the intrarenal regions, the renal cortex, the medulla, and the collecting system. In this way, DCE-MRI reveals the renal uptake and excretion of the contrast agent. An optimal DCE-MRI acquisition protocol involves finding a good compromise between whole-kidney coverage (i.e., 3D imaging), spatial and temporal resolution, and contrast resolution. By analyzing the enhancement of the renal tissues as a function of time, one can determine indirect measures of clinically important single-kidney parameters as the renal blood flow, glomerular filtration rate, and intrarenal blood volumes. Gadolinium-containing contrast agents may be nephrotoxic in patients suffering from severe renal dysfunction, but otherwise DCE-MRI is clearly useful for diagnosis of renal functions and for assessing treatment response and posttransplant rejection.Here we introduce the concept of renal DCE-MRI, describe the existing methods, and provide an overview of preclinical DCE-MRI applications to illustrate the utility of this technique to measure renal perfusion and glomerular filtration rate in animal models.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction is complemented by two separate publications describing the experimental procedure and data analysis.

We investigated metabolic changes during brain death (BD) using hyperpolarized magnetic resonance (MR) spectroscopy and ex vivo graft glucose metabolism during normothermic isolated perfused kidney (IPK) machine perfusion. BD was induced in mechanically ventilated rats by inflation of an epidurally placed catheter; sham‐operated rats served as controls. Hyperpolarized [1‐13C]pyruvate MR spectroscopy was performed to quantify pyruvate metabolism in the liver and kidneys at 3 time points during BD, preceded by injecting hyperpolarized[1‐13C]pyruvate. Following BD, glucose oxidation was measured using tritium‐labeled glucose (d‐6‐3H‐glucose) during IPK reperfusion. Quantitative polymerase chain reaction and biochemistry were performed on tissue/plasma. Immediately following BD induction, lactate increased in both organs (liver: eµd0.21, 95% confidence interval [CI] [−0.27, −0.15]; kidney: eµd0.26, 95% CI [−0.40, −0.12]. After 4 hours of BD, alanine production decreased in the kidney (eµd0.14, 95% CI [0.03, 0.25], P, Differences in glucose metabolism in the liver and kidney can be visualized in vivo during brain death using hyperpolarized magnetic resonance spectroscopy and ex vivo following brain death during normothermic kidney machine perfusion using glucose oxidation.

Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65–74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.

Measuring vital signs is central to medical practice, but they are difficult to monitor in awake laboratory animals. We examined the feasibility of a noninvasive device for telemetric assessment of respiration rate, heart rate, temperature and movement in pigs. Awake piglets were monitored continuously for 31 h (interquartile range, 7) before (n = 4) and after (n = 3) surgery. Data quality was sufficient for determination of all parameters. We conclude that continuous, noninvasive monitor- ing of pigs is possible by using the evaluated device.

BACKGROUND: Pigs and minipigs are increasingly used as non-primate large animal models for preclinical research on nervous system disorders resulting in motor dysfunction. Knowledge of the minipig pyramidal tract is therefore essential to support such models.AIM AND METHODS: This study used 5 female Göttingen minipigs aging 11-15 months. The Göttingen minipig corticospinal tract was investigated, in the same animals, with in vivo neuronal tracing and with postmortem diffusion weighted MRI tractography to provide a thorough insight in the encephalic distribution of this primary motor pathway and its decussation at the craniocervical junction.RESULTS: The two methods similarly outlined the course of the pyramidal tract from its origin in the motor cortex down through the internal capsule to the craniocervical junction, where both methods displayed an axonal crossover at the pyramid decussation. The degree of crossover was quantified with unbiased stereology, where 81-93% of the traced corticospinal fibers crossed to the contralateral spinal cord. Accordingly, in the upper cervical spinal cord the corticospinal tract is primarily distributed in the contralateral lateral funiculus and in close relation to the gray matter, wherein some direct terminations on large ventral column gray matter neurons could be identified.DISCUSSION: The combination of neuronal tracing and tractography exploited the strengths of the respective methods to gain a better understanding of the encephalic distribution and craniocervical decussation of the Göttingen minipig corticospinal tract. Moreover, a quantification of the crossing fibers was obtained from the tracing data, which was not possible with tractography. Our data indicate that the porcine corticospinal system is quite lateralized down to the investigated upper cervical levels. However, further elucidation of this point will require a full examination of the corticospinal tracing pattern into the caudal spinal cord combined with an analysis of the direct versus indirect termination pattern on the lower motor neurons.

BackgroundVideographic material of animals can contain inapparent signals, such as color changes or motion that hold information about physiological functions, such as heart and respiration rate, pulse wave velocity, and vocalization. Eulerian video magnification allows the enhancement of such signals to enable their detection. The purpose of this study is to demonstrate how signals relevant to experimental physiology can be extracted from non-contact videographic material of animals.ResultsWe applied Eulerian video magnification to detect physiological signals in a range of experimental models and in captive and free ranging wildlife. Neotenic Mexican axolotls were studied to demonstrate the extraction of heart rate signal of non-embryonic animals from dedicated videographic material. Heart rate could be acquired both in single and multiple animal setups of leucistic and normally colored animals under different physiological conditions (resting, exercised, or anesthetized) using a wide range of video qualities. Pulse wave velocity could also be measured in the low blood pressure system of the axolotl as well as in the high-pressure system of the human being. Heart rate extraction was also possible from videos of conscious, unconstrained zebrafish and from non-dedicated videographic material of sand lizard and giraffe. This technique also allowed for heart rate detection in embryonic chickens in ovo through the eggshell and in embryonic mice in utero and could be used as a gating signal to acquire two-phase volumetric micro-CT data of the beating embryonic chicken heart. Additionally, Eulerian video magnification was used to demonstrate how vocalization-induced vibrations can be detected in infrasound-producing Asian elephants.ConclusionsEulerian video magnification provides a technique to extract inapparent temporal signals from videographic material of animals. This can be applied in experimental and comparative physiology where contact-based recordings (e.g., heart rate) cannot be acquired.

BACKGROUND: Tracheostomy decannulation is accompanied by several clinical concerns due to air leakage. In this study, we introduced a novel tracheostoma closure device that facilitates the use of noninvasive ventilation, improvement of pulmonary function, and vocalization in the newly decannulated patient. The biosafety and feasibility of the device were evaluated in an animal model.METHODS: Five Danish Landrace pigs were subjected to tracheostomy followed by decannulation and insertion of the tracheostoma closure device. Correct placement of the device was ensured by flexible tracheoscopy. The device consisted of an intratracheal silicone seal disc fixated by a cord through the stoma to an external part. At day 14, computed tomography (CT) was performed before the device was extracted. With the pulling of a cord, the disc unraveled into a thin thread and was extracted through the stoma. At day 21, CT was repeated before euthanasia. The trachea and epidermis were excised en bloc for histopathological evaluation.RESULTS: Insertion and correct placement of the disc was unproblematic in all animals. CT at day 14 confirmed a clear airway, appropriate placement of the disc, and full closure of the tracheostoma. Extraction was successful in one animal but complicated in the remaining animals. There was histological evidence of healing after the foreign body placement.CONCLUSIONS: The study demonstrated that the tracheostoma closure device is feasible and biosafe in a porcine animal model, but the design and quality of the materials need to be improved before clinical trials.

The combination of modern interventional and preventive medicine has led to an epidemic of ageing. While this phenomenon is a positive consequence of an improved lifestyle and achievements in a society, the longer life expectancy is often accompanied by decline in quality of life due to musculoskeletal pain and disability. The Aarhus Regenerative Orthopaedics Symposium (AROS) 2015 was motivated by the need to address regenerative challenges in an ageing population by engaging clinicians, basic scientists, and engineers. In this position paper, we review our contemporary understanding of societal, patient-related, and basic science-related challenges in order to provide a reasoned roadmap for the future to deal with this compelling and urgent healthcare problem. © 2017 The Author(s). Published by Taylor & Francis on behalf of the Nordic Orthopedic Federation.

Magnetic resonance imaging (MRI) is a well-established modality for assessing renal morphology and function, as well as changes that occur during disease. However, the significant metabolic changes associated with renal disease are more challenging to assess with MRI. Hyperpolarized carbon-13 MRI is an emerging technique which provides an opportunity to probe metabolic alterations at high sensitivity by providing an increase in the signal-to-noise ratio of 20,000-fold or more. This review will highlight the current status of hyperpolarised

Intrarenal hypoxia develops within a few days after the onset of insulinopenic diabetes in an experimental animal model (ie, a model of type-1 diabetes). Although diabetes-induced hypoxia results in increased renal lactate formation, mitochondrial function is well maintained, a condition commonly referred to as pseudohypoxia. However, the metabolic effects of significantly elevated lactate levels remain unclear. We therefore investigated in diabetic animals the response to acute intrarenal hypoxia in the presence of high renal lactate formation to delineate mechanistic pathways and compare these findings to healthy control animals. Hyperpolarized 13C-MRI and blood oxygenation level–dependent 1H-MRI was used to investigate the renal metabolism of [1-13C]pyruvate and oxygenation following acutely altered oxygen content in the breathing gas in a streptozotocin rat model of type-1 diabetes with and without insulin treatment and compared with healthy control rats. The lactate signal in the diabetic kidney was reduced by 12%–16% during hypoxia in diabetic rats irrespective of insulin supplementation. In contrast, healthy controls displayed the well-known Pasteur effect manifested as a 10% increased lactate signal following reduction of oxygen in the inspired air. Reduced expression of the monocarboxyl transporter-4 may account for altered response to hypoxia in diabetes with a high intrarenal pyruvate-to-lactate conversion. Reduced intrarenal lactate formation in response to hypoxia in diabetes shows the existence of a different metabolic phenotype, which is independent of insulin, as insulin supplementation was unable to affect the pyruvate-to-lactate conversion in the diabetic kidney.

Background While metformin is the first-line pharmacological treatment of diabetes mellitus type 2, this drug is not considered safe to use in pregnant women because of its unknown consequences for the fetus. In this study, we aimed to investigate the biodistribution of metformin in the pregnant chinchilla, a species exhibiting placental characteristics comparable with the pregnant woman. Furthermore, we aimed to investigate the expression of metformin transporters in humans and chinchillas, respectively, in order to evaluate the pregnant chinchilla as a novel animal model for the use of metformin in pregnancy. Methods Three chinchillas in the last part of gestation were injected with [11C]-metformin and scanned by PET/CT for 70 minutes to visualize the distribution. To investigate the difference in expression of placenta transporters between humans and chinchillas, PCR was performed on samples from five chinchilla placentae and seven human placentae. Results Dynamic PET with [11C]-metformin showed that the metformin distribution in chinchillas was similar to that in nonpregnant humans, with signal from kidneys, liver, bladder, and submandibular glands. Conversely, no radioactive signal was observed from the fetuses, and no metformin was accumulated in the chinchilla fetus when measuring the SUV. PCR of placental mRNA showed that the human placentae expressed OCT3, whereas the chinchilla placentae expressed OCT1. Conclusion Since metformin did not pass the placenta barrier in the pregnant chinchilla, as it is known to do in humans, we do not suggest the chinchilla as a future animal model of metformin in pregnancies.

PURPOSE: Mild hyperthermia can be used as an adjuvant therapy to enhance radiation therapy or chemotherapy of cancer. However, administering mild hyperthermia is technically challenging due to the high accuracy required of the temperature control. MR guided high-intensity focused ultrasound (MR-HIFU) is a technology that can address this challenge. In this work, accurate and spatially uniform mild hyperthermia is demonstrated for deep-seated clinically relevant heating volumes using a HIFU system under MR guidance.METHODS: Mild hyperthermia heating was evaluated for temperature accuracy and spatial uniformity in 11 in vivo porcine leg experiments. Hyperthermia was induced with a commercial Philips Sonalleve MR-HIFU system embedded in a 1.5T Ingenia MR scanner. The operating software was modified to allow extended duration mild hyperthermia. Heating time varied from 10 min up to 60 min and the assigned target temperature was 42.5 °C. Electronic focal point steering, mechanical transducer movement, and dynamic transducer element switch-off were exploited to enlarge the heated volume and obtain uniform heating throughout the acoustic beam path. Multiple temperature mapping images were used to control and monitor the heating. The magnetic field drift and transducer susceptibility artifacts were compensated to enable accurate volumetric MR thermometry.RESULTS: The obtained mean temperature for the target area (the cross sectional area of the heated volume at focal depth primarily used to control the heating) was on average 42.0 ± 0.6 °C. Temperature uniformity in the target area was evaluated using T10 and T90, which were 43.1 ± 0.6 and 40.9 ± 0.6 °C, respectively. For the near field, the corresponding temperatures were 39.3 ± 0.8 °C (average), 40.6 ± 1.0 °C (T10), and 38.0 ± 0.9 °C (T90). The sonications resulted in a concise heating volume, typically in the shape of a truncated cone. The average depth reached from the skin was 86.9 mm. The results show that the heating algorithm was able to induce deep heating while keeping the near-field temperature uniform and at a safe level.CONCLUSIONS: The capability of MR-HIFU to induce accurate, spatially uniform, and robust mild hyperthermia in large deep-seated volumes was successfully demonstrated through a series of in vivo animal experiments.

Hepatic and renal energy status prior to transplantation correlates with graft survival. However, effects of brain death (BD) on organ-specific energy status are largely unknown. We studied metabolism, perfusion, oxygen consumption, and mitochondrial function in the liver and kidneys following BD. BD was induced in mechanically-ventilated rats, inflating an epidurally-placed Fogarty-catheter, with sham-operated rats as controls. A 9.4T-preclinical MRI system measured hourly oxygen availability (BOLD-related R2*) and perfusion (T1-weighted). After 4 hrs, tissue was collected, mitochondria isolated and assessed with high-resolution respirometry. Quantitative proteomics, qPCR, and biochemistry was performed on stored tissue/plasma. Following BD, the liver increased glycolytic gene expression (Pfk-1) with decreased glycogen stores, while the kidneys increased anaerobic- (Ldha) and decreased gluconeogenic-related gene expression (Pck-1). Hepatic oxygen consumption increased, while renal perfusion decreased. ATP levels dropped in both organs while mitochondrial respiration and complex I/ATP synthase activity were unaffected. In conclusion, the liver responds to increased metabolic demands during BD, enhancing aerobic metabolism with functional mitochondria. The kidneys shift towards anaerobic energy production while renal perfusion decreases. Our findings highlight the need for an organ-specific approach to assess and optimise graft quality prior to transplantation, to optimise hepatic metabolic conditions and improve renal perfusion while supporting cellular detoxification.

BACKGROUND: Chronic pulmonary regurgitation often leads to myocardial dysfunction and heart failure. It is not fully known why secondary hypertrophy cannot fully protect against the increase in wall stress brought about by the increased end-diastolic volume in ventricular dilation. It has been assumed that mural architecture is not deranged in this situation, but we hypothesised that there might be a change in the pattern of orientation of the aggregations of cardiomyocytes, which would contribute to contractile impairment.METHODS: We created pulmonary valvular regurgitation by open chest, surgical suturing of its leaflets in seven piglets, performing sham operations in seven control animals. Using cardiovascular magnetic resonance imaging after 12 weeks of recovery, we demonstrated significantly increased right ventricular volumes in the test group. After sacrifice, diffusion tensor imaging of their hearts permitted measurement of the orientation of the cardiomyocytes.RESULTS: The helical angles in the right ventricle approached a more circumferential orientation in the setting of right ventricular RV dilation (p = 0.007), with an increased proportion of surface-parallel cardiomyocytes. In contrast, this proportion decreased in the left ventricle. Also in the left ventricle a higher proportion of E3 angles with a value around zero was found, and conversely a lower proportion of angles was found with a numerical higher value. In the dilated right ventricle the proportion of E3 angles around -90° is increased, while the proportion around 90° is decreased.CONCLUSION: Contrary to traditional views, there is a change in the orientation of both the left ventricular and right ventricular cardiomyocytes subsequent to right ventricular dilation. This will change their direction of contraction and hinder the achievement of normalisation of cardiomyocytic strain, affecting overall contractility. We suggest that the aetiology of the cardiac failure induced by right vetricular dilation may be partly explained by morphological changes in the myocardium itself.

11C-acetate is a positron emission tomography (PET) tracer of oxidative metabolism, whereas hyperpolarized 13C-acetate can be used in magnetic resonance imaging (MRI) for investigating specific metabolic processes. The aims of this study were to examine if the kinetic formalism of 11C-acetate PET in the kidneys is comparable to that of 13C-acetate MRI, and to compare the dynamic metabolic information of hyperpolarized 13C-acetate MRI with that obtained with 11C-acetate PET. Rats were examined with dynamic hyperpolarized 13C-acetate MRI or 11C-acetate PET before and after intravenous injection of furosemide, a loop diuretic known to alter both the hemodynamics and oxygen consumption in the kidney. The metabolic clearance rates (MCR) were estimated and compared between the two modalities experimentally in vivo and in simulations. There was a clear dependency on the mean transit time and MCR for both 13C-acetate and 11C-acetate following furosemide administration, while no dependencies on the apparent renal perfusion were observed. This study demonstrated that hyperpolarized 13C-acetate MRI is feasible for measurements of the intrarenal energetic demand via the MCR, and that the quantitative measures are correlated with those measured by 11C-acetate PET, even though the temporal window is more than 30 times longer with 11C-acetate.

Intrarenal hypoxia is an acknowledged factor contributing to the development of diabetic nephropathy. Hyperbaric oxygen (HBO) therapy is a well‐known adjuvant treatment for several medical conditions, such as decompression sickness, infections, and wound healing. The underlying metabolic response of HBO is largely unknown. In this study, we investigated the effect of HBO on the intrarenal metabolic alteration in diabetes. Hyperpolarized [1‐ 13 C]pyruvate MRI was performed to assess intrarenal energy metabolism in normoglycemic controls and short‐term (2 weeks) streptozotocin‐induced diabetic rats with and without HBO for five consecutive days. HBO therapy blunted intrarenal lactate production, 3 days after the therapy, in both normoglycemic controls and diabetic rats without affecting either lactate dehydrogenase mRNA expression or activity. HBO therapy reduced lactate formation in both normoglycemic and hyperglycemic rats. These findings support hyperpolarized [1‐ 13 C]pyruvate MRI as a novel method for monitoring HBO therapy via the pyruvate to lactate conversion.

While unilateral nephrectomy (UNx) is suggested to protect against ischemia-reperfusion injury (IRI) in the remaining kidney, the mechanisms underlying this protection remain to be elucidated. In this study, functional MRI was employed in a renal IRI rat model to reveal global and regional changes in renal filtration, perfusion, oxygenation and sodium handling, and microarray and pathway analyses were conducted to identify protective molecular mechanisms. Wistar rats were randomized to either UNx or sham UNx immediately prior to 37 minutes of unilateral renal artery clamping or sham operation under sevoflurane anesthesia. MRI was performed 24 hours after reperfusion. Blood and renal tissue were harvested. RNA was isolated for microarray analysis and QPCR validation of gene expression results. The perfusion (T1 value) was significantly enhanced in the medulla of the post-ischemic kidney following UNx. UNx decreased the expression of fibrogenic genes, i.a. Col1a1, Fn1 and Tgfb1 in the post-ischemic kidney. This was associated with a marked decrease in markers of activated myofibroblasts (Acta2/α-Sma and Cdh11) and macrophages (Ccr2). This was most likely facilitated by down-regulation of Pdgfra, thus inhibiting pericyte-myofibroblast differentiation, chemokine production (Ccl2/Mcp1) and macrophage infiltration. UNx reduced ischemic histopathologic injury. UNx may exert renoprotective effects against IRI through increased perfusion in the renal medulla and alleviation of the acute pro-inflammatory and pro-fibrotic responses possibly through decreased myofibroblast activation. The identified pathways involved may serve as potential therapeutic targets and should be taken into account in experimental models of IRI.

Objective To provide morphological descriptions of microphthalmia or anophthalmia in eight pythons using microcomputerized tomography (μCT), magnetic resonance imaging (MRI), and histopathology. Animals studied Seven Burmese pythons (Python bivittatus) and one ball python (P. regius) with clinically normal right eyes and an abnormal or missing left eye. Procedure At the time of euthanasia, four of the eight snakes underwent necropsy. Hereafter, the heads of two Burmese pythons and one ball python were examined using μCT, and another Burmese python was subjected to MRI. Following these procedures, the heads of these four pythons along with the heads of an additional three Burmese pythons were prepared for histology. Results All eight snakes had left ocular openings seen as dermal invaginations between 0.2 and 2.0 mm in diameter. They also had varying degrees of malformations of the orbital bones and a limited presence of nervous, glandular, and muscle tissue in the posterior orbit. Two individuals had small but identifiable eyes. Furthermore, remnants of the pigmented embryonic framework of the hyaloid vessels were found in the anophthalmic snakes. Necropsies revealed no other macroscopic anomalies. Conclusions Eight pythons with unilateral left-sided microphthalmia or anophthalmia had one normal eye and a left orbit with malformed or incompletely developed ocular structures along with remnants of fetal structures. These cases lend further information to a condition that is often seen in snakes, but infrequently described.

The aim of this randomized porcine study was to compare surface targeted temperature management (TTM) to endovascular TTM evaluated by cerebral diffusion-weighted magnetic resonance imaging (MRI): apparent diffusion coefficient (ADC), and by intracerebral/intramuscular microdialysis. It is well known that alteration in the temperature affects ADC, but the relationship between cerebral ADC values and the cooling method per se has not been established. Eighteen anesthetized 60-kg female swine were hemodynamically and intracerebrally monitored and subsequently subjected to a baseline MRI. The animals were then randomized into three groups: (1) surface cooling (n = 6) at 33.5°C using EMCOOLSpad(®), (2) endovascular cooling (n = 6) at 33.5°C using an Icy(®) cooling catheter with the CoolGard 3000(®), or (3) control (n = 6) at 38.5°C using a Bair Hugger™. The swine were treated with TTM for 6 hours followed by a second MRI examination, including ADC. Blood and microdialysate were sampled regularly throughout the experiment, and glucose, lactate, pyruvate, glycerol, and the lactate/pyruvate ratio did not differ among groups, neither intracerebrally nor intramuscularly. Surface cooling yielded a significantly lower median ADC than endovascular cooling: 714 (634; 804) × 10(-6) mm(2)/s versus 866 (828; 927) × 10(-6) mm(2)/s, (p

Monopterus albus, a swamp eel inhabiting the freshwaters of South East Asia, relies on an extensive vascularisation of the buccal cavity, pharynx and anterior oesophagus for gas exchange, while the gills are much reduced. In the present study we describe the macro-circulation in the cephalic region and the vascularisation of the buccal cavity of M. albus using vascular fillings and micro-computed tomography (μCT). We also show that M. albus has the capacity to use the buccal cavity for aquatic gas exchange, being able to maintain normal arterial blood gas composition, blood pressure, heart rate and cardiac output throughout 10h of forced submergence. M. albus therefore can be characterised as a facultative air-breather. Because M. albus aestivates for many months in moist mud during the dry season we characterised in vivo cardiovascular function during exposure to anoxia as well as the effects of anoxia on in vitro contractility of strip preparations from atria and ventricle. Both studies revealed a low anoxia tolerance, rendering it unlikely that M. albus can survive prolonged exposure to anoxia.

Pythons are renowned for the profound phenotypical flexibility of their visceral organs in response to ingestion of large meals following prolonged fasting. Traditionally, the phenotypic changes are studied by determining organ mass of snakes killed at different times during digestion. Here we evaluate the use of magnetic resonance imaging (MRI) for in vivo measurements of the visceral organs in fasting and digesting snakes. Twelve snakes were MRI scanned immediately before the organs were removed and weighed to provide direct comparison of the two methods. Both methods provided similar estimates for the mass of liver, gallbladder, and pancreas, whereas MRI overestimated the size of the heart and small intestine, probably because blood and digesta contributed to the volume determined by MRI. The correlations were used to derive wet organ mass from MRI-based volumes to evaluate the mass development through repeated MRI scans of five digesting snakes. MRI was performed at fasting and 24, 48, 72, 132, and 500 h after eating a meal corresponding to 25% of body mass. This observation period revealed a reversible volume upregulation of the visceral organs, supporting the view that successive MRI facilitates in vivo investigations of structural changes accompanied by digestion.

INTRODUCTION: Ischemia/reperfusion injury (I/R-I) is a leading cause of acute kidney injury (AKI) and is associated with increased mortality. Danegaptide is a selective modifier of the gap junction protein connexion 43. It has cytoprotective as well as anti-arrhythmic properties and has been shown to reduce the size of myocardial infarct in pigs. The aim of this study was to investigate the ischemia-protective effect of Danegaptide in a porcine renal I/R-I model with two weeks follow up.METHODS: Unilateral renal I/R-I was induced in pigs by clamping the left renal artery over a two hour period. The model allowed examination of renal blood flow by magnetic resonance imaging (MRI) and the measurement of single kidney GFR two weeks after injury. Eleven animals were randomized to Danegaptide-infusion while nine animals received placebo. Kidney histology and urinary neutrophil gelatinase-associated lipocalin (NGAL) excretion were included as markers of AKI.RESULTS: Unilateral kidney I/R-I resulted in an immediate ~50% GFR reduction, associated with a four-fold increase in urinary NGAL-excretion. Fourteen days after I/R-I, the total GFR was ~75% of baseline with a significantly lower GFR in the injured left kidney compared to the right kidney. No differences in GFR were observed between the treated and non-treated animals immediately after I/R-I or at Day 14. Furthermore, no differences were observed in the urinary excretion of NGAL, renal blood flow or other markers of renal function.CONCLUSIONS: As expected this porcine renal I/R-I model was associated with reduced GFR two weeks after injury. Danegaptide did not improve renal function after I/R-I.

We thank Anderson et al. [[1][1]] for engaging in our paper on hearing in salamanders [[2][2]]. We have written our paper primarily as experimental physiologists basing hypotheses on recent animals and with no research expertise in palaeontology. Therefore, discussions with palaeontologists are

ATM and ATR display distinct activities in meiotic DSB repair, such that ATM functions in DNA damage repair and negative feedback control over programmed double strand breaks, whereas ATR is required for checkpoint activity., Ataxia telangiectasia–mutated (ATM) and ataxia telangiectasia–related (ATR) kinases are conserved regulators of cellular responses to double strand breaks (DSBs). During meiosis, however, the functions of these kinases in DSB repair and the deoxyribonucleic acid (DNA) damage checkpoint are unclear. In this paper, we show that ATM and ATR have unique roles in the repair of meiotic DSBs in Drosophila melanogaster. ATR mutant analysis indicated that it is required for checkpoint activity, whereas ATM may not be. Both kinases phosphorylate H2AV (γ-H2AV), and, using this as a reporter for ATM/ATR activity, we found that the DSB repair response is surprisingly dynamic at the site of DNA damage. γ-H2AV is continuously exchanged, requiring new phosphorylation at the break site until repair is completed. However, most surprising is that the number of γ-H2AV foci is dramatically increased in the absence of ATM, but not ATR, suggesting that the number of DSBs is increased. Thus, we conclude that ATM is primarily required for the meiotic DSB repair response, which includes functions in DNA damage repair and negative feedback control over the level of programmed DSBs during meiosis.

Material and Methods: The 2-compartment filtration model for Gd-DTPA (2) was generalized to allow for protein binding. Eight healthy Danish-Landrace-pigs were examined in general anaesthesia at 1.5T with a saturation-recovery TurboFLASH sequence (1 axial and 2 coronal slices; temporal resolution 1s; TR 194ms; TE 0.96ms; IR 9ms; slice thickness 8mm). A double-bolus protocol with Gd-DTPA as first bolus followed by Gd-BOPTA as second bolus or vice versa (group I; Gd-DTPA/Gd-BOPTA n = 4 vs. group II GdBOPTA/Gd-DTPA n = 4) was performed. An arterial input function (AIF) was defined manually in the aorta and cortical regions-ofinterest were defined semi-automatically in left- and right kidneys using thresholds on plasma volume. Data were fitted to the generalized 2-compartment filtration model, producing split renal plasma-flow (FP) and -volume (VP), tubular flow (FT) or glomerular-filtration-rate (GFR) and tubular transit time (TT). Urine protein levels were obtained. Gd-DTPA and Gd-BOPTA values were compared with the Wilcoxon-signed-rank-test. Differences between both groups were assessed with the Wilcoxon-rank-sumtest. Results: The pigs demonstrated a weak proteinuria of 0.27 ± 0.08g/l. There were no significant differences between group I (GdDTPA then Gd-BOPTA) and group II (Gd-BOPTA) for any of the parameters. The AIF measured with Gd-BOPTA showed a significantly higher maximal enhancement (162.8 ± 36.9 AU), compared to the AIF derived from Gd-DTPA (145±29.8 AU) (p

ATM-related kinases promote repair of DNA double-strand breaks and maintenance of chromosome telomeres, functions that are essential for chromosome structural integrity in all eukaryotic organisms. In humans, loss of ATM function is associated with ataxia telangiectasia, a neurodegenerative disease characterized by extreme sensitivity to DNA damage. Drosophila melanogaster has recently emerged as a useful animal model for analyzing the molecular functions of specific domains of this large, multifunctional kinase. The gene encoding Drosophila ATM kinase (dATM) was originally designated tefu because of the telomere fusion defects observed in atm mutants. In this report, molecular characterization of eight atm (tefu) alleles identified nonsense mutations predicted to truncate conserved C-terminal domains of the dATM protein, as well as two interesting missense mutations. One of these missense mutations localized within a putative HEAT repeat in the poorly characterized N-terminal domain of dATM (atm4), whereas another associated with a temperature-sensitive allele (atm8) changed the last amino acid of the conserved FATC domain. Leveraging this molecular information with the powerful genetic tools available in Drosophila should facilitate future analysis of conserved ATM-mediated molecular mechanisms that are important for telomere maintenance, DNA repair, and neurodegeneration.

Udgivelsesdato: 2009-Dec-16 Advanced and exclusive software solutions are offered to reduce susceptibility artefacts on MRI echo-planar sequences. We present a straightforward surgical technique to reduce the cortical distortion and signal loss that normally occur using diffusion tensor imaging (DTI) of the Göttingen minipig brain. Pronounced pneumatisation of the minipig cranium causes considerable susceptibility artefacts at the air/tissue interface around the frontal sinuses. Five Göttingen minipigs had burr holes drilled through the outer lamina of the skull bilaterally at the level of bregma. The underlying frontal sinuses were filled with a suspension of an MRI-compatible alginate. DTI was obtained before and after placing the medium in the sinus, quantifying the change using mutual information and Wilcoxon's rank-sum test. Fibertracking algorithms were applied to visualize the effect of treatment. We showed that the susceptibility artefacts were reduced at the air, bone and brain interfaces and that major cortical fiberbundles could be reliably visualized. This study demonstrated that DTI fibertracking of cortical bundles in experimental animals with extensive skull pneumatisation is feasible even when advanced software is unavailable.

Udgivelsesdato: 2009-Apr-6 BACKGROUND: The Göttingen minipig is increasingly used as an animal model in experimental neuroscience as a much needed alternative to non-human primates. Accurate spatial targeting in this species in vivo is challenging, and most clinically available magnetic resonance imaging (MRI) protocols do not provide sufficient spatial resolution for this purpose. Thus, the aim of this study was to develop an in vivo pre-operative MRI protocol allowing direct visualization of individual nuclei of major interest in the minipig brain. MATERIALS AND METHODS: Three Göttingen minipigs underwent MRI using an inversion-recovery fast spin-echo sequence that was optimized with regards to the following parameters: inversion time, relaxation time, echo time and spatial and temporal resolution, giving a scan duration acceptable for the tight schedule usually employed in a neurosurgical procedure. The most optimal pulse sequence was applied in 8 Göttingen minipigs and the anatomical structures were identified. RESULTS AND CONCLUSION: High-resolution images with excellent contrast were acquired, presenting negligible geometric distortions. Minor flow artifacts from the large neck vessels generated the most prominent artifact. Determination of coordinates necessary in experimental neurosurgery in the Göttingen minipig was considerably improved with this MRI protocol.

Udgivelsesdato: 2009-Jan Although myocardial architecture has been investigated extensively, as yet no evidence exists for the anatomic segregation of discrete myocardial pathways. We performed post-mortem diffusion tensor imaging on 14 pig hearts. Pathway tracking was done from 22 standardized voxel groups from within the left ventricle, the left ventricular papillary muscles, and the right ventricular outflow tract. We generated pathways with comparable patterns in the different hearts when tracking from all chosen voxels. We were unable to demonstrate discrete circular or longitudinal pathways, nor to trace any solitary tract of myocardial cells extending throughout the ventricular mass. Instead, each pathway possessed endocardial, midwall, and epicardial components, merging one into another in consistent fashion. Endocardial tracks, when followed towards the basal or apical parts of the left ventricle, changed smoothly their helical and transmural angulations, becoming continuous with circular pathways in the midwall, these circular tracks further transforming into epicardial tracks, again by smooth change of the helical and transmural angles. Tracks originating from voxels in the papillary muscles behaved similarly to endocardial tracks. This is the first study to show myocardial pathways that run through the mammalian left and right ventricles in a highly reproducible manner according to varying local helical and transmural intrusion angles. The patterns generated are an inherent feature of the three-dimensional arrangement of the individual myocytes aggregated within the walls, differing according to the regional orientation and branching of individual myocytes. We found no evidence to support the existence of individual muscles or bands. Anat Rec, 2009. (c) 2008 Wiley-Liss, Inc.

PURPOSE: Aim of this study was to evaluate the dynamic changes in renal relative signal intensity (RSI) following the administration of Gd-DTPA in adolescent pigs with complete and partial unilateral ureteric obstruction. METHODS: Pigs were divided into 3 groups: partial and complete unilateral ureteric obstruction and controls. Complete unilateral ureteric obstruction (CUUO) was created by ligating the left ureter, whereas partial unilateral ureteric obstruction (PUUO) was created in pigs of 2 weeks of age by embedding the left ureter into the psoas muscle. Dynamic MRI was performed before and at 0 - 60 min after an intravenous bolus injection of Gd-DTPA. Mean RSI of the renal cortex, medulla and pelvis was measured and interpreted as an indirect measure of the renal function. In addition, renography was performed, and renal morphology was examined IN VITRO. RESULTS: Three phases of RSI were identified. The dynamic RSI patterns differed markedly between obstructed and control kidneys. In PUUO kidneys, Phase 1 of the mean RSI of the cortex and medulla demonstrated a decreased amplitude and prolonged duration, whereas in Phase 2 the mean RSI of the pelvis was increased. In acute CUUO kidneys, the mean RSI patterns were similar to those of controls, except for a significant increase of the pelvic mean RSI. CONCLUSIONS: Gd-DTPA enhanced dynamic MRI allowed a characterization and differentiation of renal function and morphology of normal and obstructed kidneys, and secondly, provided potentially important information on renal concentrative and filtration availability.

Udgivelsesdato: 2008-Jun Anti-inflammatory therapy has provided hope for a new effective treatment of brain ischemic stroke. In this study, adult male Wistar rats subjected to right middle cerebral artery occlusion (MCAO) for 60 min were allocated to treatment of the anti-inflammatory compound alpha melanocyte stimulating hormone (alpha-MSH) or saline. Magnetic resonance imaging (MRI) and histology were used to evaluate the effects of alpha-MSH. MRI volumetry was performed to measure infarct size, and MRI measurements of the apparent diffusion coefficient (ADC) were performed to evaluate changes in the extra/intracellular volume ratio. Triphenyltetrazolium chloride (TTC) staining was used as a reference method to measure infarct sizes. The ADC value of the infarct area decreased significantly two days after MCAO in both groups. Simultaneously the infarct volume determined from the ADC map decreased in the alpha-MSH treated group compared to the control group. Five days after MCAO, ADC returned to baseline levels in both groups. The infarct volume in the alpha-MSH group was smaller compared to the saline treated group as demonstrated both by MRI and TTC staining. This study showed that the extra/intracellular ratio (reflected by ADC) following focal brain ischemic stroke could be affected by alpha-MSH. Secondly, we showed that the infarct volume was reduced by alpha-MSH. The volumetric dimensions of the infarct areas measured by MRI were comparable to those measured by histology.

Udgivelsesdato: 2008-May-29 PURPOSE: We investigated the functional consequences of relieving ureteric obstruction in young pigs with experimental hydronephrosis (HN) induced by partial unilateral ureteropelvic obstruction. MATERIALS AND METHODS: Three groups of animals were followed from the age of 2 weeks to the age of 14 weeks: Eight animals had severe or grades 3-4 HN throughout the study. Six animals had relief of the obstruction after 4 weeks. Six animals received sham operations at both ages. Morphological and functional examinations were performed at age 6 weeks and again at age 14 weeks and consisted of magnetic resonance imaging (MRI), technetium-diethylenetriaminepentaaceticacid ((99m)Tc-DTPA) renography, renal technetium-dimercaptosuccinicacid ((99m)Tc-DMSA) scintigraphy, and glomerular filtration rate (GFR) measurement. RESULTS: After relief of the partial obstruction, there was reduction of the pelvic diameter and improvement of urinary drainage. Global and relative kidney function was not significantly affected by either obstruction or its relief. Renal (99m)Tc-DMSA scintigraphy showed a change in both the appearance of the kidney and a change in the distribution within kidneys even after relief of obstruction. CONCLUSION: This study shows that partial ureteric obstruction in young pigs may be associated with little effect on global and differential kidney function. However, even after relief of HN, the distribution of (99m)Tc-DMSA in the kidney remains abnormal suggesting that a normal differential renal function may not represent a normal kidney.

In the present study, we studied the effect of bacteremia on cerebral blood flow (CBF) autoregulation in a rat model of pneumococcal bacteremia and meningitis. Anesthetized rats were divided into five groups (A to E) and inoculated with pneumococci intravenously and normal saline intracisternally (group A, N = 10); saline intravenously and pneumococci intracisternally (group B, N = 10); pneumococci intravenously and pneumococci intracisternally (group C, N = 5); saline intravenously, antipneumococcal antibody intravenously (to prevent bacteremia), and pneumococci intracisternally (group D, N = 10); or saline intravenously and saline intracisternally (group E, N = 10), respectively. Positive cultures occurred in the blood for all rats in groups A, B, and C, and in the cerebrospinal fluid for all rats in groups D and E. Twenty-four hours after inoculation, CBF was measured with laser-Doppler ultrasound during incremental reductions in cerebral perfusion pressure (CPP) by controlled hemorrhage. Autoregulation was preserved in all rats without meningitis (groups A and E) and was lost in 24 of 25 meningitis rats (groups B, C, and D) ( P

Ventricular hypertrabeculation (noncompaction) is a poorly characterized condition associated with heart failure. The condition is widely assumed to be the retention of the trabeculated ventricular design of the embryo and ectothermic (cold-blooded) vertebrates. This assumption appears simplistic and counterfactual. Here, we measured a set of anatomical parameters in hypertrabeculation in man and in the ventricles of embryos and animals. We compared humans with left ventricular hypertrabeculation (N=21) with humans with structurally normal left ventricles (N=54). We measured ejection fraction and ventricular trabeculation using cardiovascular MRI. Ventricular trabeculation was further measured in series of embryonic human and 9 animal species, and in hearts of 15 adult animal species using MRI, CT, or histology. In human, hypertrabeculated left ventricles were significantly different from structurally normal left ventricles by all structural measures and ejection fraction. They were far less trabeculated than human embryonic hearts (15-40% trabeculated volume versus 55-80%). Early in development all vertebrate embryos acquired a ventricle with approximately 80% trabeculations, but only ectotherms retained the 80% trabeculation throughout development. Endothermic (warm-blooded) animals including human slowly matured in fetal and postnatal stages towards ventricles with little trabeculations, generally less than 30%. Further, the trabeculations of all embryos and adult ectotherms were very thin, less than 50μm wide, whereas the trabeculations in adult endotherms and in the setting of hypertrabeculation were wider by orders of magnitude. It is concluded in contrast to a prevailing assumption, the hypertrabeculated left ventricle is not like the ventricle of the embryo or of adult ectotherms. This article is part of a Special Issue entitled:Cardiomyocyte Biology: Integration of Develomental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

The effects of ex vivo preservation techniques on the quality of diffusion tensor magnetic resonance imaging in hearts are poorly understood, and the optimal handling procedure prior to investigation remains to be determined. Therefore, 24 porcine hearts were examined in six groups treated with different preservation techniques, including chemical fixation and freezing. Diffusion properties of each heart were assessed with diffusion tensor imaging in terms of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da) and radial diffusivity (Dr). Tractography was performed to visualize the course of the cardiomyocytes, assuming greater diffusivity in the longitudinal than the transverse axis of individual cardiomyocytes. Significant differences in MD, Da and Dr were found, as well as in FA between groups (P

Rule-based languages such as Kappa excel in their support for handling the combinatorial complexities prevalent in many biological systems, including signalling pathways. But Kappa provides little structure for organising rules, and large models can therefore be hard to read and maintain. This paper introduces a high-level, modular extension of Kappa called LBS-κ. We demonstrate the constructs of the language through examples and three case studies: a chemotaxis switch ring, a MAPK cascade, and an insulin signalling pathway. We then provide a formal definition of LBS-κ through an abstract syntax and a translation to plain Kappa. The translation is implemented in a compiler tool which is available as a web application. We finally demonstrate how to increase the expressivity of LBS-κ through embedded scripts in a general-purpose programming language, a technique which we view as generally applicable to other domain specific languages.

BACKGROUND: The tallest animal on Earth, the giraffe (Giraffa camelopardalis) is endowed with a mean arterial blood pressure (MAP) twice that of other mammals. The kidneys reside at heart level and show no sign of hypertension related damage. We hypothesized that a species-specific evolutionary adaption in the giraffe kidney allows normal for size renal hemodynamics and glomerular filtration rate (GFR) despite a MAP double that of other mammals.METHODS: Fourteen anaesthetized giraffes were instrumented with vascular and bladder catheters to measure glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). Renal interstitial hydrostatic pressure (RIHP) was assessed by inserting a needle into the medullary parenchyma. Doppler ultrasound measurements provided renal artery resistive index (RI). Hormone concentrations as well as biomechanical, structural, and histological characteristics of vascular and renal tissues were determined.RESULTS: GFR averaged 342±99 ml min(-1) and ERPF 1252±305 ml min(-1) . RIHP varied between 45 and 140 mmHg. Renal pelvic pressure was 39±2 mmHg and renal venous pressure 32±4 mmHg. A valve-like structure at the junction of the renal and vena cava generated a pressure drop of 12±2 mmHg. RI was 0.27. The renal capsule was durable with a calculated burst pressure of 600 mmHg. Plasma renin and AngII were 2.6±0.5 mIU/l and 9.1±1.5 pg/ml, respectively.CONCLUSION: In giraffes, GFR, ERPF and RI appear much lower than expected based on body mass. A strong renal capsule supports a RIHP which is >10-fold that of other mammals effectively reducing the net filtration pressure and protecting against the high MAP. This article is protected by copyright. All rights reserved.