Rabbit Brain Research Articles

Maternal surgery during pregnancy has a transient adverse effect on the developing fetal rabbit brain

Recently, the US Food and Drug Administration called for cautious use of anesthetic drugs during pregnancy. In 0.2-2% of pregnancies, nonobstetric surgery is being performed. The consequences of anesthesia during pregnancy on fetal development remain unclear, and preclinical studies in relevant animal models may help to elucidate them. To assess the effect of maternal anesthesia and surgery during pregnancy on the developing fetal brain, using a rabbit model. This is a randomized, sham-controlled study in time-mated pregnant does at 28 days of gestation (term= 31 days), which corresponds to the end of the second trimester in humans. Anesthesia was induced in 14 does (155 pups) with propofol and maintained with 4 vol% (equivalent to 1 minimum alveolar concentration) sevoflurane for 2 hours, and a laparotomy with minimal organ manipulation was performed (surgery group). Maternal vital signs (blood pressure, heart rate, peripheral and cerebral oxygen saturation, temperature, end-tidal CO2, pH, lactate) were continuously monitored. Sham controls consisted of 7 does (74 pups) undergoing invasive hemodynamic monitoring for 2 hours without sedation. At term, does underwent cesarean delivery under ketamine-medetomidine sedation and local anesthesia. Pups either underwent motor and sensory neurologic testing followed by euthanasia at day 1 or daily neurodevelopment testing for 2 weeks and extensive neurologic assessment at 5 and 7 weeks (open field and object recognition test, T-maze, and radial-arm maze). Brains were harvested for histologic assessment of neuron density and synaptophysin expression. Blood gases and vital parameters were stable in both groups. On postnatal day 1, surgery pups had significant lower motor (25 ± 1 vs 23 ± 3; P= .004) and sensory (16 ± 2 vs 15 ± 2; P= .005) neurobehavioral scores and lower brain-to-body weight ratios (3.7% ± 0.6% vs 3.4% ± 0.6%; P= .001). This was accompanied by lower neuron density in multiple brain regions (eg, hippocampus 2617 ± 410 vs 2053 ± 492 neurons/mm2; P= .004) with lower proliferation rates and less synaptophysin expression. Furthermore, surgery pups had delayed motor development during the first week of life, for example with hopping appearing later (6 ± 5 vs 12 ± 3 days; P= .011). Yet, by 7 weeks of age, neurobehavioral impairment was limited to a reduced digging behavior, and no differences in neuron density or synaptophysin expression were seen. In rabbits, 2 hours of maternal general anesthesia and laparotomy, with minimal organ and no fetal manipulation, had a measurable impact on neonatal neurologic function and brain morphology. Pups had a slower motoric neurodevelopment, but by 7 weeks the effect became almost undetectable.

Effect of hyaluronidase on expression of neuron-glial antigen 2 and myelin basic protein after germinal matrix-intraventricular hemorrhage in premature rabbits

Objective To investigate the neuroprotective effect of hyaluronidase(HAase) on rabbit brain tissue in germinal matrix-intraventricular hemorrhage(GM-IVH) premature rabbits. Methods Eighty premature rabbits of gestation age 29 days were randomly divided into normal group, GM-IVH control group and HAase treatment group.The rabbits in GM-IVH control group and HAase treatment group were given intraperitoneal injection of 50 g/L glycerol to establish GM-IVH animal model, while the premature rabbits in normal group were given the same dose of 9 g/L saline.The GM-IVH was screened by using cranial ultrasound.The premature rabbits in HAase treatment group were given HAase into the lateral forebrain while the rabbits in the GM-IVH control group were given the same dose of 9 g/L saline.In 3 days, 7 days and 14 days after birth, the premature rabbits were killed and brain tissue were separated.The expression of neuron-glial antigen 2(NG2) were detected by adopting immunohistochemical method.The expression of myelin basic protein(MBP) were detected by Western blot method. Results The expression of NG2 in 3 groups of premature rabbits decreased gradually with the increase of age[the values of NG2 in the normal group were(62.65±33.58)×104, (15.61±4.22)×104, and (13.54±4.51)×104 on the 3rd, 7th, and 14th day; those in the GM-IVH control group were (54.58±25.48)×104, (48.91±22.49)×104, (7.18±2.28)×104 on the 3rd, 7th, and 14th day; those in the HAase treatment group were (148.13±27.30)×104, (88.38±14.55)×104, (77.98±18.96)×104 on the 3rd, 7th, and 14th day]. At the same time, the expression of NG2 in the HAase treatment group was higher than that of the GM-IVH control group, and the differences were statistically significant among the 3 groups at any time(all P<0.05). The expression of MBP protein in the 3 groups increased with the increase of day age[MBP protein in the normal group were (0.30±0.22)×103, (1.91±0.43)×103, and (5.67±2.14) ×103 on the 3rd, 7th, and 14th day; those in the GM-IVH control group were (0.87±0.12)×103, (1.15±0.22)×103 and (2.54±0.69) ×103 on the 3rd, 7th, and 14th day; those in the HAase treatment group were (0.91±1.01)×103, (2.25±0.66)×103, (3.40±1.10)×103 on the 3rd, 7th, and 14th day]. The difference was statistically significant between the normal group and the HAase treatment group(P<0.05). Conclusions After HAase treatment, the expression of NG2 and MBP can be improved to a certain extent, promoting the development of oligodendrocytes and regeneration of myelin sheath. Key words: Germinal matrix-intraventricular hemorrhage; Hyaluronidase; Neuron-glial antigen 2; Myelin basic protein

The creation of an endovascular exit through the vessel wall using a minimally invasive working channel in order to reach all human organs.

Since the establishment of the Seldinger technique for secure entry to the vascular system, there has been a rapid evolution in imaging and catheters that has made the arteries and veins internal routes to any place in the body for interventions. It is curious that a general exit from the vasculature in a similar manner has not been proposed earlier. Possibly, the simplest reason is that accidental perforation of the vasculature by guide wire or catheter is a feared adverse event in endovascular intervention. Most places in the body can be reached by ultrasonography or computed tomography-guided intervention. Some organs such as the central nervous system, the heart and pancreas are harder to access and, in some organs, like the kidney, repeated percutaneous punctions to cover large areas is not suitable. We present a new general purpose micro-endovascular device creating a working channel to these 'hard to reach' organs by an inverted Seldinger technique. This review details this trans-vessel wall technique, which has been studied in pancreas for transplantation of insulin-producing cells, for injection of contrast agent to the heart and to the brain, bowels and kidney in rat, rabbit, swine and macaque monkeys with up to one year of follow-up without adverse events. Furthermore, the payloads that can be given through such a system are briefly discussed. Drugs, cells, gene vectors and other therapeutic substances may be injected directly to the tissue to increase efficacy and decrease risk of off-site adverse effects.

On the existence of mechanoreceptors within the neurovascular unit of the mammalian brain.

We describe a set of perivascular interneurons (PINs) with series of fibro-vesicular complexes (FVCs) throughout the gray matter of the adult rabbit and rat brains. PIN-FVCs are ubiquitous throughout the brain vasculature as detected in Golgi-impregnated specimens. Most PINs are small, aspiny cells with short or long (> 1mm) axons that split and travel along arterial blood vessels. Upon ramification, axons form FVCs around the arising vascular branches; then, paired axons run parallel to the vessel wall until another ramification ensues, and a new FVC is formed. Cytologically, FVCs consist of clusters of perivascular bulbs (PVBs) encircling the precapillary and capillary wall surrounded by end-feet and the extracellular matrix of endothelial cells and pericytes. A PVB contains mitochondria, multivesicular bodies, and granules with a membranous core, similar to Meissner corpuscles and other mechanoreceptors. Some PVBs form asymmetrical, axo-spinous synapses with presumptive adjacent neurons. PINs appear to correspond to the type 1 nNOS-positive neurons whose FVCs co-label with markers of sensory fiber-terminals surrounded by astrocytic end-feet. The PIN is conserved in adult cats and rhesus monkey specimens. The location, ubiquity throughout the vasculature of the mammalian brain, and cytological organization of the PIN-FVCs suggests that it is a sensory receptor intrinsic to the mammalian neurovascular unit that corresponds to an afferent limb of the sensorimotor feed-back mechanism controlling local blood flow.

Brain Infection by Hepatitis E Virus Probably via Damage of the Blood-Brain Barrier Due to Alterations of Tight Junction Proteins.

Extrahepatic injury, particularly neurologic dysfunctions such as Guillain-Barré syndrome, neurologic amyotrophy, and encephalitis/meningoencephalitis/myositis were associated with HEV infection, which was supported by both clinical and laboratory studies. Thus, it is crucial to figure out how the virus invades into the central nervous system (CNS). In this study, CNS lesions were determined in rabbits and Mongolian gerbils inoculated with genotype 4 HEV. Junctional proteins were detected in HEV infected primary human brain microvascular cells (HBMVCs). Viral encephalitis associated perivascular cuffs of lymphocytes and microglial nodules were observed in HEV infected rabbits. Both positive- and negative-strand of HEV RNA was detected in brain and spinal cord in rabbits intraperitoneally infected with HEV at 28 dpi (days postinoculation), but not in rabbits gavaged with HEV. HEV ORF2 protein was further examined in both brain and spinal cord sections of infected rabbits, with positive signals located mainly in neural cells and perivascular areas. Ultrastructural study showed thickened and reduplicated basement membranes of capillary endothelium in HEV RNA positive brain tissues. In vitro study showed loss of tight junction proteins including Claudin5, Occludin, and ZO-1 (zonula occludens-1) in HBMVCs inoculated with HEV for 48 h. These findings indicated that disruption of the blood-brain barrier (BBB) might be potential mechanisms of HEV invasion into the CNS. It provides new insights to further study HEV associated neurologic disorders and will be helpful for seeking potential therapeutics for HEV infection in the future.

Structural Organization of Astrocytes in the Subgranular Zone of the Rabbit Hippocampal Dentate Fascia

Neurogenesis in the subgranular zone (SGZ) of the mammalian hippocampus is well known to occur throughout the life span. Astrocytes in this specialized proliferative zone are supposed to have properties of progenitor cells. Structural features of these cells and their interspecies differences remain understudied, while data on the structural organization of the SGZ in the rabbit (order Lagomorpha, superorder Glires), which is widely used in medical and biological studies, are lacking at all. The present work was focused on the structural and cytochemical organization of astrocytes in the SGZ of the rabbit hippocampal dentate fascia as studied by laser confocal microscopy. The study was carried out on the brain of adult Chinchilla rabbits compared to that of adult Wistar rats. Two morphological astrocyte types were identified in the rabbit SGZ: radial gliocyte-like (type I) and atypical fibrous astrocyte-like (type II) cells. By contrast, the rat SGZ exhibited a predominance of type II astrocytes which lacked long unramified processes penetrating through the granular layer and reaching the molecular layer. SGZ astrocytes, both in the rabbit and rat, were characterized by intense immunoreactivity for glutamine synthetase, most pronounced in the processes that formed the perivascular glia limitans. Importantly, the peculiarities of the astrocyte organization in the dentate fascia of the rabbit hippocampus allowed SGZ delimitation, whereas astrocytes in the rat SGZ exhibited no local morphological distinctions. The latter finding indicates a more complex organization of the neurogenic zone in the hippocampus of lagomorphs in contrast to the same zone in rodents.

Dynamic magnetic resonance imaging of carbogen challenge on awake rabbit brain at 1.5T.

Anesthesia may alter the cellular components contributing to the magnetic resonance imaging (MRI) signal intensities. Developing awake animal models to evaluate cerebral function has grown in importance. To investigate a noninvasive strategy for dynamic MRI (dMRI) of awake rabbits during carbogen challenge. A nonmetallic assistive device with a self-adhering wrap secure procedure was developed for the head fixation of awake rabbits. Multi-shot gradient echo echo-planar imaging sequence was applied for the dMRI on a 1.5 T clinical MRI scanner with a quadrature head coil. The carbogen challenge pattern was applied in a sequence of air - carbogen - air - carbogen - air. Twelve scans were performed for each block of carbogen challenge. T2-weighted fast-spin echo and T1-weighted gradient echo sequences were performed before and after dMRI to evaluate the head position shifts. The whole dMRI scan time was about 30 minutes. The position shift of 8 rabbits in the x-and y-direction was less than 3%. The average MRI signal intensities (SI) from the 8 rabbits during carbogen challenge was fitted well using exponential growth and decay functions. The average MRI SI increase due to carbogen inhaling was 1.51%. The proposed strategy for head dMRI on an awake rabbit during carbogen challenge is feasible.

Traumatic Injury Leads to Inflammation and Altered Tryptophan Metabolism in the Juvenile Rabbit Brain.

Neuroinflammation after traumatic brain injury (TBI) contributes to widespread cell death and tissue loss. Here, we evaluated sequential inflammatory response in the brain, as well as inflammation-induced changes in brain tryptophan metabolism over time, in a rabbit pediatric TBI model. On post-natal days 5-7 (P5-P7), New Zealand white rabbit littermates were randomized into three groups: naïve (no injury), sham (craniotomy alone), and TBI (controlled cortical impact). Animals were sacrificed at 6 h and 1, 3, 7, and 21 days post-injury for evaluating levels of pro- and anti-inflammatory cytokines, as well as the major components in the tryptophan-kynurenine pathway. We found that 1) pro- and anti-inflammatory cytokine levels in the brain injury area were differentially regulated in a time-dependent manner post-injury; 2) indoleamine 2,3 dioxygeenase 1 (IDO1) was upregulated around the injury area in TBI kits that persisted at 21 days post-injury; 3) mean length of serotonin-staining fibers was significantly reduced in the injured brain region in TBI kits for at least 21 days post-injury; and 4) kynurenine level significantly increased at 7 days post-injury. A significant decrease in serotonin/tryptophan ratio and melatonin/tryptophan ratio at 21 days post-injury was noted, suggesting that tryptophan metabolism is altered after TBI. A better understanding of the temporal evolution of immune responses and tryptophan metabolism during injury and repair after TBI is crucial for the development of novel therapeutic strategies targeting these pathways.

The fibrinogen prothrombin time‐derived method is not useful in patients anticoagulated with low molecular weight heparins or rivaroxaban

Background The fibrinogen prothrombin time-derived (FIBPT-d) method with photo-optical coagulometers is easy and economical. However, there are few reports on the behavior of this test on samples from patients anticoagulated with direct oral anticoagulants or low molecular weight heparin (LMWH). Objective To compare fibrinogen results obtained with the Clauss (FIB C) method and the FIBPT-d method with two thromboplastins in anticoagulated patients. Population The study population comprised 295 consecutive anticoagulated patients: 99 treated with vitamin K antagonists (VKAs), 49 treated with unfractionated heparin (UFH), 47 treated with LMWH, 50 treated with rivaroxaban, 50 treated with dabigatran, and 100 normal controls (NCs). Methods Dabigatran samples were analyzed by the use of FIB C with HemosIL Fibrinogen C or 100 NHI thrombin units mL-1 reagents; rabbit brain and human recombinant thromboplastins with HemosIL PTFibrinogen HS plus (HS) and Recombiplastin 2G (RP) were used for FIBPT-d method. Heparin and rivaroxaban levels were assessed with HemosIL Liq antiXa with specific calibrators; dabigatran levels were determined with the HemosIL Direct Thrombin Inhibitor Assay. All assays were performed on the ACL TOP platform in two laboratories. Percentage biases for the FIBPT-d method versus the FIB C method were calculated by the use of Bland-Altman plots. Results Positive biases of the FIBPT-d method versus the FIB C method with both thromboplastins were seen in NC samples (13.7% and 18.9% for HS and RP, respectively), but biases with HS in rivaroxaban and VKA patient samples were higher than that in NC samples, at 31.9% and 34.0%, respectively. LMWH patient samples showed higher bias than NC samples: 26.5% and 29.3.0% with HS and RP, respectively. UFH and dabigatran patient samples showed similar bias as NC samples. Conclusion The FIBPT-d method should not be used in anticoagulated patients, because the FIBPT-d mathematical algorithm has been validated only in normal subjects, so overestimation could occur in these patients.

Can the Impact of Topiramate on Memory Processes be Related to Its ‘Antialcoholic Activity’?—A Preclinical Study

Topiramate causes the inhibition of alcohol consumption in addicts but the mechanism of this action has not been fully understood yet. Nowadays, it seems that memory may have a role in the development of dependence. In this study, the impact of topiramate and ethanol on the bioelectric activity of the brain in rabbits and on spatial memory in rats was evaluated. The aim of the study was to assess the effect of co-administration of topiramate and ethanol on bioelectric activity of the rabbits' brain and on spatial memory in rats. Topiramate decreased ethanol-induced changes in all studied brain structures and improved memory and learning processes. A pharmaco-electroencephalography study was used to examine the effect of topiramate (25 mg/kg/day) co-administered for 6 weeks with ethanol on the bioelectric activity of the rabbits' brain. The influence of the drug was also assessed in first and second weeks of the abstinence period. Spatial memory was evaluated in rats using Morris water maze task. Topiramate (60 mg/kg/day) was administered with the ethanol for 3 weeks and for 2 weeks in the abstinence. After 6 weeks of topiramate and ethanol administration, the drug decreased ethanol-induced changes in the midbrain reticular formation, hippocampus and frontal cortex. In the abstinence, the drug also inhibited the features of neuronal hyperactivity, especially in the hippocampus. Moreover, topiramate co-administered with ethanol for 3 weeks decreased ethanol-induced memory disturbance in rats. This beneficial effect was also observed in the second week of abstinence. These findings reveal that 'antialcoholic' activity of topiramate may be associated with its advantageous effect on memory and learning processes.

Top stories: Chocolate money, the rise of multicellularity, and pet rabbit brains

Top stories: Chocolate money, the rise of multicellularity, and pet rabbit brains

Brain Targeted Intranasal Zaleplon Nano-emulsion: In-Vitro Characterization and Assessment of Gamma Aminobutyric Acid Levels in Rabbits' Brain and Plasma at Low and High Doses.

Zaleplon is a pyrazolopyrimidin derivative hypnotic drug indicated for the short-term management of insomnia. Zaleplon belongs to Class II drugs, according to the biopharmaceutical classification system (BCS), showing poor solubility and high permeability. It undergoes extensive first-pass hepatic metabolism after oral absorption, with only 30% of Zaleplon being systemically available. It is available in tablet form which is unable to overcome the previous problems. The aim of this study is to enhance solubility and bioavailability via utilizing nanotechnology in the formulation of intranasal Zaleplon nano-emulsion (ZP-NE) to bypass the barriers and deliver an effective therapy to the brain. Screening studies were carried out wherein the solubility of zaleplon in various oils, surfactants( S) and co-surfactants(CoS) were estimated. Pseudo-ternary phase diagrams were constructed and various nano-emulsion formulations were prepared. These formulations were subjected to thermodynamic stability, in-vitro characterization, histopathological studies and assessment of the gamma aminobutyric acid (GABA) level in plasma and brain in rabbits compared to the market product (Sleep aid®). Stable NEs were successfully developed with a particle size range of 44.6±3.4 to 136.9±1.6 nm. A NE composed of 10% Miglyol® 812, 40% Cremophor® RH40 40%Transcutol® HP and 10% water successfully enhanced the bioavailability and brain targeting in the rabbits, showing a three to four folds increase than the marketed product.

A magnetic resonance multi-atlas for the neonatal rabbit brain

The rabbit model has become increasingly popular in neurodevelopmental studies as it is best suited to bridge the gap in translational research between small and large animals. In the context of preclinical studies, high-resolution magnetic resonance imaging (MRI) is often the best modality to investigate structural and functional variability of the brain, both in vivo and ex vivo. In most of the MRI-based studies, an important requirement to analyze the acquisitions is an accurate parcellation of the considered anatomical structures. Manual segmentation is time-consuming and typically poorly reproducible, while state-of-the-art automated segmentation algorithms rely on available atlases. In this work we introduce the first digital neonatal rabbit brain atlas consisting of 12 multi-modal acquisitions, parcellated into 89 areas according to a hierarchical taxonomy. Delineations were performed iteratively, alternating between segmentation propagation, label fusion and manual refinements, with the aim of controlling the quality while minimizing the bias introduced by the chosen sequence. Reliability and accuracy were assessed with cross-validation and intra- and inter-operator test-retests. Multi-atlas, versioned controlled segmentations repository and supplementary materials download links are available from the software repository documentation at https://github.com/gift-surg/SPOT-A-NeonatalRabbit.

Preferential and Increased Uptake of Hydroxyl-Terminated PAMAM Dendrimers by Activated Microglia in Rabbit Brain Mixed Glial Culture.

Polyamidoamine (PAMAM) dendrimers are multifunctional nanoparticles with tunable physicochemical features, making them promising candidates for targeted drug delivery in the central nervous system (CNS). Systemically administered dendrimers have been shown to localize in activated glial cells, which mediate neuroinflammation in the CNS. These dendrimers delivered drugs specifically to activated microglia, producing significant neurological improvements in multiple brain injury models, including in a neonatal rabbit model of cerebral palsy. To gain further insight into the mechanism of dendrimer cell uptake, we utilized an in vitro model of primary glial cells isolated from newborn rabbits to assess the differences in hydroxyl-terminated generation 4 PAMAM dendrimer (D4-OH) uptake by activated and non-activated glial cells. We used fluorescently-labelled D4-OH (D-Cy5) as a tool for investigating the mechanism of dendrimer uptake. D4-OH PAMAM dendrimer uptake was determined by fluorescence quantification using confocal microscopy and flow cytometry. Our results indicate that although microglial cells in the mixed cell population demonstrate early uptake of dendrimers in this in vitro system, activated microglia take up more dendrimer compared to resting microglia. Astrocytes showed delayed and limited uptake. We also illustrated the differences in mechanism of uptake between resting and activated microglia using different pathway inhibitors. Both resting and activated microglia primarily employed endocytotic pathways, which are enhanced in activated microglial cells. Additionally, we demonstrated that hydroxyl terminated dendrimers are taken up by primary microglia using other mechanisms including pinocytosis, caveolae, and aquaporin channels for dendrimer uptake.

Alzheimer-like brain metabolic and structural features in cholesterol-fed rabbit detected by magnetic resonance imaging

BackgroundHypercholesterolemia is known to increase the risk of AD in later life, the purpose of this study is to illustrate brain metabolic and structural changes in a cholesterol-fed rabbit model of Alzheimer’s Disease (AD) by using clinical 3 T Magnetic Resonance Imaging (MRI).MethodsThe Institutional Animal Care and Use Committee of Zhejiang Chinese Medical University approved the study. Totally 16 Japanese White Rabbits (JWR) were randomly divided into 2 groups including normal control group fed with routine diet (group NC) and high cholesterol diet group (group CD) fed a 2% cholesterol diet with 0.24 ppm copper in the drinking water for 12 weeks. Magnetic resonance spectroscopy (MRS) and structural image of rabbit brain were performed by using a 3 Tesla (T) MRI scanner with an 8 channel Rabbit coil. The chemical metabolites were identified by LC Model including N-acetylaspartate (NAA), creatine (Cr), glutamate (Glu), glutamine (Gln), Glycerophosphatidylcholine (GPC), phosphorylcholine (PCH), and myoinositol (MI). The relative concentrations (/Cr) were analyzed. Additionally, Amyloid-β (Aβ) accumulation in the brain was measured postmortem. For comparisons of MR and Aβ data between groups, two-tailed t-tests were performed.ResultsThe ratio of NAA/Cr (0.76 ± 0.10) and Glu/Cr (0.90 ± 0.14) in group CD were lower than those in the group NC (0.87 ± 0.06, 1.13 ± 0.22, respectively, P < 0.05). Compared to the group NC (2.88 ± 0.09 cm3, 0.63 ± 0.08 cm3, respectively), the cortical and hippocampal volumes (2.60 ± 0.14 cm3 and 0.47 ± 0.07 cm3, respectively) of rabbits brain decreased in the group CD while the third and lateral ventricular volumes enlarged (44.56 ± 6.01 mm3 vs 31.40 ± 6.14 mm3, 261.40 ± 30.98 mm3 vs 153.81 ± 30.08 mm3, P < 0.05). These metabolic and structural changes were additionally accompanied by the significant increase of Aβ1–42 in the cortex and hippocampus (163.60 ± 16.26 pg/mg and 215.20 ± 69.86 pg/mg, respectively, P < 0.05).ConclusionHigh cholesterol diet can induce the brain metabolic and structural changes of the rabbit including lowered level of NAA and Glu and the atrophy of the brain which were similar to those of human AD.

In vivo study of a novel micro-arc oxidation coated magnesium-zinc-calcium alloy scaffold/autologous bone particles repairing critical size bone defect in rabbit

To evaluate the effect of a novel micro-arc oxidation (MAO) coated magnesium-zinc-calcium (Mg-Zn-Ca) alloy scaffold/autologous bone particles to repair critical size bone defect (CSD) in rabbit and explore the novel scaffold in vivo corrosion resistance and biocompatibility. Seventy-two New Zealand white rabbits were randomly divided into 3 groups ( n=24), group A was uncoated Mg-Zn-Ca alloy scaffold group, group B was 10 μm MAO coated Mg-Zn-Ca alloy scaffold group, and group C was control group with only autologous bone graft. The animals were operated to obtain bilateral ulnar CSD (15 mm in length) models. The bone fragment was removed and minced into small particles and were filled into the scaffolds of groups A and B. Then, the scaffolds or autologous bone particles were replanted into the defects. The animals were sacrificed at 2, 4, 8, and 12 weeks after surgery (6 rabbits each group). The local subcutaneous pneumatosis was observed and recorded. The ulna defect healing was evaluated by X-ray image and Van Gieson staining. The X-ray images were assessed and scored by Lane-Sandhu criteria. The percentage of the lost volume of the scaffold (ΔV) and corrosion rate (CR) were calculated by the Micro-CT. The Mg 2+ and Ca 2+ concentrations were monitored during experiment and the rabbit liver, brain, kidney, and spleen were obtained to process HE staining at 12 weeks after surgery. The local subcutaneous pneumatosis in group B was less than that in group A at 2, 4, and 8 weeks after surgery, showing significant differences between 2 groups at 2 and 4 weeks after surgery ( P<0.05); and the local subcutaneous pneumatosis was significantly higher in group B than that in group A at 12 weeks after surgery ( P<0.05). The X-ray result showed that the score of group C was significantly higher than those of groups A and B at 4 and 8 weeks after surgery ( P<0.05), and the score of group B was significantly higher than that of group A at 8 weeks ( P<0.05). At 12 weeks after surgery, the scores of groups B and C were significantly higher than that of group A ( P<0.05). Meanwhile, the renew bone moulding of group B was better than that in group A at 12 weeks after surgery. Micro-CT showed that ΔV and CR in group B were significantly lower than those in group A ( P<0.05). Van Gieson staining showed that group B had better biocompatibility and osteanagenesis than group A. The Mg 2+ and Ca 2+ concentrations in serum showed no significant difference between groups during experiments ( P>0.05). And there was no obvious pathological changes in the liver, brain, kidney, and spleen of the 3 groups with HE staining at 12 weeks. The MAO coated Mg-Zn-Ca alloy scaffold/autologous bone particles could be used to repair CSD effectively. At the same time, 10 μm MAO coating can effectively improve the osteanagenesis, corrosion resistance, and biocompatibility of Mg-Zn-Ca alloy scaffold.

Royal Jelly Reduces Cholesterol Levels, Ameliorates Aβ Pathology and Enhances Neuronal Metabolic Activities in a Rabbit Model of Alzheimer's Disease.

Alzheimer’s disease (AD) is the most common form of dementia characterized by aggregation of amyloid β (Aβ) and neuronal loss. One of the risk factors for AD is high cholesterol levels, which are known to promote Aβ deposition. Previous studies have shown that royal jelly (RJ), a product of worker bees, has potential neuroprotective effects and can attenuate Aβ toxicity. However, little is known about how RJ regulates Aβ formation and its effects on cholesterol levels and neuronal metabolic activities. Here, we investigated whether RJ can reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in an AD rabbit model induced by 2% cholesterol diet plus copper drinking water. Our results suggest that RJ significantly reduced the levels of plasma total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C), and decreased the level of Aβ in rabbit brains. RJ was also shown to markedly ameliorate amyloid deposition in AD rabbits from Aβ immunohistochemistry and thioflavin-T staining. Furthermore, our study suggests that RJ can reduce the expression levels of β-site APP cleaving enzyme-1 (BACE1) and receptor for advanced glycation end products (RAGE), and increase the expression levels of low density lipoprotein receptor-related protein 1 (LRP-1) and insulin degrading enzyme (IDE). In addition, we found that RJ remarkably increased the number of neurons, enhanced antioxidant capacities, inhibited activated-capase-3 protein expression, and enhanced neuronal metabolic activities by increasing N-acetyl aspartate (NAA) and glutamate and by reducing choline and myo-inositol in AD rabbits. Taken together, our data demonstrated that RJ could reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in AD rabbits, providing preclinical evidence that RJ treatment has the potential to protect neurons and prevent AD.

Washout effect in rabbit brain: in-beam PET measurements using 10C, 11C and 15O ion beams

In particle therapy, in-beam positron emission tomography (PET) is expected to enable in situ noninvasive confirmation of the treatment delivery. For accurate range and dose verification or three-dimensional (3D) volume imaging, however, correction of the biological washout effect in a living body is necessary. In this study, we measured the washout rate in a rabbit brain using the recently developed technology for oxygen beam radiation as well as carbon ion beam radiation. To measure components of washout, three radionuclides, 10C, 11C and 15O, which were generated as secondary beams in the Heavy Ion Medical Accelerator in Chiba (HIMAC), were irradiated on the rabbit brain under two conditions, live and dead. In-beam data were acquired by our whole body dual-ring OpenPET, which enables 3D in-beam imaging. Regions of interests (ROIs) were set as a 3D positron distribution and the time activity curves (TACs) of the irradiated field were acquired. We obtained the washout rate for those conditions based on multiple component model analysis. A difference between washout speed in 11C ions and the 15O ions was observed. The observed medium and slow biological decay rates of 11C ions in rabbit brain were 0.30 min−1 and 0.004 min−1, respectively. Those values were consistent with the previous rabbit study results acquired by other imaging modalities, such as the pair of positron cameras or our single-ring small animal OpenPET prototype. The observed medium and slow biological decay rates of 15O ions were 0.72 min−1 and 0.024 min−1, respectively, which were faster than those of the 11C ion. Also, the medium biological decay rate of 15O ions was close to the washout rate in cerebral blood flow (CBF) measurements by dynamic PET with 15O-labeled water. These results should help to establish an accurate washout correction model.

Экспериментально-теоретические исследования закономерностей электроакустических импедансных характеристик головного мозга биологических объектов

Purpose: To determine frequency-dependent impedance characteristics of the brains of the experimental animals.&#x0D; Material and methods: The developed by us 2-microphone interferometer technology was used in the acoustic impedance characteristics determination. The two standard microphones mounted stationary on a lateral surface of the interferometer measure the sound pressure levels and the phase difference between them. According to these data, the complex reflection coefficient and the impedance components of the test sample mounted on the end of the interferometer are calculated.&#x0D; The electrical impedance characteristics were measured by two electrodes method with the usage of parallel electrodes. The sample was placed between two electrodes and values of electrical impedance were detected by the electric current flowing through them.&#x0D; The object of the investigation was the rabbit brain.&#x0D; Results: The maximum acoustic absorption coefficient of the rabbit’s brain, on average, is registered at a frequency of 160–180 Hz and reaches 0.7. Then, as the frequency increases, the absorption coefficient decreases and at an average frequency of 760 Hz is 0.43. It can be noted that the spread in the data is maximum in the frequency range up to 240 Hz. The coefficient of variation varies from 23 to 10 %. At frequencies above 300 Hz, the coefficient of variation is less than 5 %. A low value of the coefficient of variation indicates a sufficiently accurate and reliable data.&#x0D; The difference in the magnitude of the spread between low frequencies in comparison with the spreads at medium and high frequencies reaches 2–4 times. This difference is caused by methodological errors. First of all, this is due to the fact that the waveguide is round with a diameter equal to 3.3 cm, and the whole brain of the rabbit resembles in a greater degree an oval. It is impossible for the rabbit’s whole brain to completely cover the circular surface of the waveguide section, there will always be gaps that bring in an element of uncertainty at low frequencies. At higher frequencies, this circumstance no longer affects the measurement error significantly.&#x0D; The presence of a maximum at frequencies of 160–180 Hz does not correspond to theoretical concepts. With the help of additional experiments with non-biological samples, it was possible to establish that this maximum is caused by an irregular geometric shape of the rabbit’s whole brain. Depending on the position of small dimples in the brain tissue and other irregularities, the maximum of the absorption coefficient appears. Those it is also a methodological error that characterizes rather the degree of overlapping of the waveguide section and the contact surface of the sound wave with the brain.&#x0D; In this series of experiments, it was also estimated how the values of the acoustic characteristics of the brain of rabbits vary with time. The first measurements were made 10–15 minutes after the extraction of the brain, the second measurement after 20 minutes, the third after 1 hour. It can be noted that the average values are almost identical starting from frequencies from 300 Hz and higher. There are small deviations in the readings at low frequencies. Over time, the absorption coefficient at low frequencies increased from 0.65 to 0.75.&#x0D; The analysis of the electrical impedance characteristics and loss factor calculations indicates that the range of the loss factor variation at a frequency of 1 kHz, for all experimental animals ranges from 0.04 to 0.07 and at a frequency of 100 kHz – from 0.06 to 0.09.&#x0D; Conclusion: The represented measuring systems allow obtaining the necessary acoustic and electrical impedance characteristics of biotissues; these data are important for the physical and mathematical modelling of the sound and EM waves’ interaction with the human body.

Effects of simulated 100 m Trimix conventional diving on oxidative stress and inflammatory reaction in rabbits

To investigate the effects of simulated 100 m Trimix conventional diving on tissue inflammatory cytokines in rabbits. Eight New Zealand rabbits were performed a simulated 100 m Trimix conventional diving program which was established according to the Haldane theory. The expression levels of interferon-gamma(IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), myeloperoxidase(MPO) and matrix metallo proteinase-9 (MMP-9) in rabbits lung and brain tissues were detected by Elisa after diving decompression. The tissue wet/dry ratio was calculated. The serum levels of superoxide dismutase (SOD),glutathione(GSH), catalase(CAT), malondiadehyde(MDA) and lipid peroxide(LPO) were detected by Elisa method in rabbits before and after diving. The expressions of IFN-γ, TNF-α, IL-6, IL-8, MPO and MMP-9 in simulated diving group rabbits were significantly increased compared with the intact group(P<0.05, P<0.01); the simulated diving rabbits tissues wet/dry ratio had no significant changes compared with the intact group. After diving, the activities of SOD and GSH were decreased significantly (P<0.01), while the contents of CAT, MDA and LPO were increased significantly (P<0.01). The simulated 100 m Trimix conventional diving had significant impact on oxidative stress and inflammatory reaction in rabbits, the results of wet/dry ratio showed that the diving rabbits had no tissue edema after decompression.