Ear Artery Research Articles

Three-Dimensional High-Resolution Temporal Bone Histopathology Identifies Areas of Vascular Vulnerability in the Inner Ear

Objectives: Hypothesized causes of vestibular neuritis/labyrinthitis include neuroinflammatory or vascular disorders, yet vascular disorders of the inner ear are poorly understood. Guided by known microvascular diseases of the retina, we developed 2 hypotheses: (1) there exist vascular vulnerabilities of artery channels in cases of hypothetical nerve swelling for the superior, inferior, and vestibulocochlear artery and (2) there are arteriovenous crossings that could compromise vascular flow in disease states. Methods: Two fully mounted and stained temporal bones were used to render three-dimensional reconstructions of the labyrinth blood supply. Using these maps, areas of potential vascular compression were quantified in 50 human temporal bones. Results: Although inner ear arteries and veins mostly travel within their own bony channels, they may be exposed (1) at the entrance into the otic capsule, and (2) where the superior vestibular vein crosses the inferior vestibular artery. At the entry into the otic capsule, the ratio of the soft tissue to total space for the superior vestibular artery was significantly greater than the inferior vestibular artery/cochleovestibular artery (median 44, interquartile range 34–55 vs. 14 [9–17], p < 0.0001). Conclusions: Three-dimensional reconstruction of human temporal bone histopathology can guide vascular studies of the human inner ear. Studies of retinal microvascular disease helped identify areas of vascular vulnerability in cases of hypothetical nerve swelling at the entrance into the otic capsule and at an arteriovenous crossing near the saccular macula. These data may help explain patterns of clinical findings in peripheral vestibular lesions.

Multifunctional wound dressing for rapid hemostasis, bacterial infection monitoring and photodynamic antibacterial therapy

Wound management is a major global issue, and there is a growing challenge to develop more effective hemostatic dressings to control bleeding and prevent pathogen infections. In this study, a multifunctional wound dressing was developed to meet the clinical need. The hemostatic layer of wound dressing can quickly stop the bleeding. Meanwhile, the detection layer is used for real-time fluorescence monitoring of the bacterial colonization. When infection occurs, wound dressing is further subjected to illumination for in-situ photodynamic antibacterial treatment. In the rabbit ear artery hemostasis model, the hemostasis time of the wound dressing was 1 s. The detection limit of the wound dressing was 1.4 × 105 CFU/cm2 for Escherichia coli, 5.9 × 105 CFU/cm2 for Staphylococcus aureus, and 3.8 × 106 CFU/cm2 for Pseudomonas aeruginosa, respectively. Compared with the control group, an enhanced wound closure (up to 97.3%) were observed in mice treated with the wound dressing. In vitro and in vivo experiment results suggested that the wound dressing was effective in killing pathogenic bacterial and exhibited good biological compatibility, and induced no inflammatory reaction. The proposed design prevents massive bleeding and wound infection, and further promotes wound healing. Statement of significanceIn this work, we developed a multifunctional wound dressing, capable of rapid hemostasis, colorimetric monitoring of bacterial infection, and in situ photodynamic antibacterial. The hemostatic layer can quickly stop the bleeding due to its large specific surface area and adsorption pore size for platelet at bleeding site. Meanwhile, the detection layer can intelligently monitor the bacterial infection and respond to report bacterial infection by emitting fluorescence. When infection occurs, wound dressing can be used for in-situ photodynamic antibacterial treatment. In vitro and in vivo results showed that the wound dressing was biocompatible, prevented massive bleeding and wound infection, and further promoted wound healing.

Conjugate Electrospun 3D Gelatin Nanofiber Sponge for Rapid Hemostasis.

Developing an excellent hemostatic material with good biocompatibility and high blood absorption capacity for rapid hemostasis of deep non-compressible hemorrhage remains a significant challenge. Herein, a novel conjugate electrospinning strategy to prepare an ultralight 3D gelatin sponge consisting of continuous interconnected nanofibers. This unique fluffy nanofiber structure endows the sponge with low density, high surface area, compressibility, and ultrastrong liquid absorption capacity. In vitro assessments show the gelatin nanofiber sponge has good cytocompatibility, high cell permeability, and low hemolysis ratio. The rat subcutaneous implantation studies demonstrate good biocompatibility and biodegradability of gelatin nanofiber sponge. Gelatin nanofiber sponge aggregates and activates platelets in large quantities to accelerate the formation of platelet embolism, and simultaneously escalates other extrinsic and intrinsic coagulation pathways, which collectively contribute to its superior hemostatic capacity. In vivo studies on an ear artery injury model and a liver trauma model of rabbits demonstrate that the gelatin nanofiber sponge rapidly induce stable blood clots with least blood loss compared to gelatin nanofiber membrane, medical gauze, and commercial gelatin hemostatic sponge. Hence, the gelatin nanofiber sponge holds great potential as an absorbable hemostatic agent for rapid hemostasis.

Rabbit as an animal model for the study of biological grafts in pelvic floor dysfunctions

The aims of this study were to evaluate the feasibility of the New Zealand White (NZW) rabbit for studying implanted biomaterials in pelvic reconstructive surgery; and to compare the occurrence of graft-related complications of a commercial polypropylene (PP) mesh and new developed human dermal matrix implanted at vaginal and abdominal level. 20 white female NZW rabbits were randomized into two groups, experimental group (human acellular dermal matrices-hADM-graft) and control group (commercial PP graft). In each animal, grafts were surgically implanted subcutaneously in the abdominal wall and in the vaginal submucosa layer for 180 days. The graft segments were then removed and the surgical and clinical results were analyzed. The main surgical challenges during graft implantation were: (a) an adequate vaginal exposure while maintaining the integrity of the vaginal mucosa layer; (b) to keep aseptic conditions; (c) to locate and dissect the breast vein abdominal surgery; and (d) to withdraw blood samples from the ear artery. The most abnormal findings during the explant surgery were found in the PP group (33% of vaginal mesh extrusion) in comparison with the hADM group (0% of vaginal graft extrusion), p = 0.015. Interestingly, macroscopic observation showed that the integration of the vaginal grafts was more common in the hADM group (40%) than in the PP group, in which the vaginal mesh was identified in 100% of the animals (p = 0.014). The NZW rabbit is a good model for assessing materials to be used as grafts for pelvic reconstructive surgery and vaginal surgery. Animals are easily managed during the procedures, including surgical intervention and vaginal mucosa approach. Additionally, hADM is associated with fewer clinical complications, as well as better macroscopic tissue integration, compared to PP mesh.

Development of a Mechanically Strong Nondegradable Protein Hydrogel with a Sponge-Like Morphology.

Protein-based hydrogels are important functional materials with many potential applications. However, the relatively small pore size and poor mechanical properties substantially limit their application. Here a superporous bovine serum albumin (BSA) hydrogel is prepared with high porosity and interconnectivity by using BSA and 1,2,7,8-diepoxyoctane (DEO). The equilibrium water contents of hydrogels can reach 76.5%. Moreover, the BSA hydrogels show excellent mechanical properties and excellent deformation recoverability, with a maximum compression modulus of 50 MPa at 75% strain and no residual strain generated after 500 cyclic compression tests. The resulting BSA hydrogel has excellent biocompatibility for cell adherence and is nonbiodegradable for 40 weeks. More importantly, the BSA hydrogel exhibits excellent hemostatic ability, with hemostatic times in a rabbit ear artery and rabbit liver of 33 and 28 s, respectively. Therefore, BSA hydrogels have potential applications as painless nonadherent wound dressings and implant materials for plastic surgery.

Alternative methods for vasopuncturing in veterinary medicine: artificial rabbit ear

Veterinary students often learn to perform basic procedures onlive animals obtained from laboratories or shelters. In the eraof modern technologies, there is a constant endeavour for liveanimals to be replaced by alternative, artificial models. Practicingon different anatomical models contributes to better quality ofstudents’ future approach to animals in practice. For purposes ofthis study, many experiments with various materials were madeuntil solution to cheaper, but efficient method of alternativelearning, was found. We created the artificial rabbit ear with thepurposes of practicing and mastering vasopuncturing techniquefrom both marginal ear vein and central ear artery. Made out ofsilicone materials, it gives elasticity and softness closest to theear auricle, and blood vessels are replaced by inner tubes filledwith artificial color. The model represents anatomically correctfeatures of European brown hare’s ear (Lepus europaeus) withdual purpose, since the accent is put on correct and, of course,humane learning.

The effect of morphine on the development rate of flies (Diptera: Calliphoridae, Sarcophagidae) reared on rabbit carcasses containing this drug and its implications to postmortem interval estimates

Insects can prove to be a valuable tool in the estimation of PMI in the investigation of homicides, suicides, and other unattended human deaths, in the absence of tissues and body fluids. Aim: The current study aimed to determine morphine concentration in the second, third feeding, third post-feeding instars, and puparial skin of four forensically important flies; Lucilia sericata (Meigen), Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius) (Calliphoridae), and Sarcophaga argyrostoma (Robineau-Desvoidy) (Sarcophagidae) and to evaluate its effect on the rate and pattern of development of these flies. Materials and methods: Three female domestic rabbits, Oryctolagus cuniculus (L.) each weighing 2.5 kg received dosages of 7.5, 15, and 30 mg of morphine over a 3-h period via left ear artery perfusion. For each trial, one other rabbit, weighing 2.5 kg, was used as a control. Morphine was detected in larval instars and puparial skin using ready to use RIA kit. Results: All blood and tissue samples obtained from the rabbits receiving dosages of morphine were positive for the drug. Morphine concentrations for rabbit R2 were 1.2 to 2.6 times greater than those for rabbit R1, and concentrations for rabbit R3 were 1.4 to 3.1 times greater than those for rabbit R2. For each rabbit, morphine concentration in second, third feeding and third post-feeding instars, and puparial skin for all four species, were less than those detected in the tissues. The highest levels of morphine were recorded in the feeding third instars of Chr. megacephala R3 colony, whereas the lowest level of this drug was detected in the feeding third instars of S. argyrostoma R1 colony. Estimations of larval age for L. sericata, Chr. albiceps, Chr. megacephala and S. argyrostoma based on mean length can be significantly in error if presence of morphine in the tissues is not considered. This error can be as great as 24, 27, 6 and 21 h respectively. Conclusion: In cases of badly decomposed and/or skeletonized remains, analyses of collected carrion-feeding insects, may provide the most accurate qualitative sources of toxicological information.

Redefining physiological responses of moose (Alces alces) to warm environmental conditions.

We tested the concept that moose (Alces alces) begin to show signs of thermal stress at ambient air temperatures as low as 14°C. We determined the response of Alaskan female moose to environmental conditions from May through September by measuring core body temperature, heart rate, respiration rate, rate of heat loss from exhaled air, skin temperature, and fecal and salivary glucocorticoids. Seasonal and daily patterns in moose body temperature did not passively follow the same patterns as environmental variables. We used large changes in body temperature (≥1.25°C in 24hr) to indicate days of physiological tolerance to thermal stressors. Thermal tolerance correlated with high ambient air temperatures from the prior day and with seasonal peaks in solar radiation (June), ambient air temperature and vapor pressure (July). At midday (12:00hr), moose exhibited daily minima of body temperature, heart rate and skin temperature (difference between the ear artery and pinna) that coincided with daily maxima in respiration rate and the rate of heat lost through respiration. Salivary cortisol measured in moose during the morning was positively related to the change in air temperature during the hour prior to sample collection, while fecal glucocorticoid levels increased with increasing solar radiation during the prior day. Our results suggest that free-ranging moose do not have a static threshold of ambient air temperature at which they become heat stressed during the warm season. In early summer, body temperature of moose is influenced by the interaction of ambient temperature during the prior day with the seasonal peak of solar radiation. In late summer, moose body temperature is influenced by the interaction between ambient temperature and vapor pressure. Thermal tolerance of moose depends on the intensity and duration of daily weather parameters and the ability of the animal to use physiological and behavioral responses to dissipate heat loads.

Photodynamic Therapy Versus Glucose for the Treatment of Telangiectasia: A Randomised Controlled Study in a Rabbit Ear Model

Telangiectasia is a common venous formation that mainly affects women and causes discomfort, including psychological distress. This study compared photodynamic therapy (PDT) with glucose for vessel sclerosis in a rabbit ear model. Thirty-six ears of 18 rabbits were randomly divided into four groups: Group 1: only injection of Photogem (4mg/mL); Group 2: only light (635nm, 100mW/cm2, 8min, 48J/cm2); Group 3: glucose 75% injection; Group 4: PDT procedure with injection of Photogem and illumination immediately after. Injections were made into the central ear artery. After injection or sham procedures, manual compression of the marginal vein was maintained for 8min in all ears. Follow up was immediately after the procedures, and one and six days later. The percentage of length reduction of spider veins, the target vessels, was analysed in digital photographs with Image J software. Ear thermographs were made with a thermocamera device and average temperatures were collected for analysis. Ear biopsies were obtained after six days. Endothelium average, inflammation, fibrosis, necrosis, skin burn, and vascular thrombosis were assessed using a specific score. The mean vessel length reduction was 26% for Group 4, 2.4% for Group 3, .4% for Group 1, and 0 for Group 2, highlighting that in Group 4, the vessel lengths were significantly reduced compared with the other groups (p<.001). In the thermal analysis, in Group 3, the temperature was unchanged from the initial temperature and the central diameter vessel increased after six days, while, in Group 4, the temperature decreased and the vessels were not clearly detected, suggesting a reduction of the vessels and smaller infusion. Histology showed no difference among groups and one case of necrosis was found in Group 4. PDT was associated with significantly more target vessel sclerosis than glucose injection and controls.

Construction of a composite sponge containing tilapia peptides and chitosan with improved hemostatic performance

Despite superior hemostasis and repair function, tilapia peptide's application as wounding dressing is greatly limited due to its poor biostability. To expand its application in wounding dressing area, chitosan (CS), with antibacterial activity, biocompatibility and biodegradability, was used to encapsulate tilapia peptides using ionic crosslink method. The results show 10.6w% (loading capacity) of the tilapia peptides are homogenously dispersed in surface or interior of the as-fabricated chitosan/tilapia peptides microspheres (CS/TPM), which leads to greatly improved biostability. In addition, a new composite sponge using CS/TPM as fillers and CS as matrix was then constructed (S-CS/TPM) and used for hemorrhage control. The results indicate that S-CS/TPM can absorb large volume of water, accelerate blood clotting, increase platelet adhesion and promote conversion of fibrinogen to fibrin. Compared with the CS andCS/TPM, the hemostatic efficiency of S-CS/TPM in New Zealand rabbit ear and femoral artery models is much higher. Particularly, the bleeding time was shortened greatly, and the bleeding volume was reduced significantly. In conclusions, our results suggested that S-CS/TPM is a promising hemostatic adjuvant.

Enhancement of hemostatic property of plant derived oxidized nanocellulose-silk fibroin based scaffolds by thrombin loading

To combat post-surgical and traumatic bleeding conditions effective hemostasis is of great importance. The study was designed to investigate the effect of thrombin (Th) loading on hemostatic performance of TEMPO-oxidized cellulose nanofiber (TOCN)-silk fibroin (SF) scaffolds. Addition of SF with TOCN significantly (***P < 0.001) increased blood absorption capacity and improved biocompatibility of TOCN. Thrombin loading potentiated platelet activation and hemostatic property of scaffolds (TOCN-SF-Th) compared to samples without thrombin (TOCN-SF). The hemostatic time of TOCN-SF5-Th in rabbit ear artery bleeding model was reduced (*** P < 0.001) to 114 s from 220 s of TOCN-SF5. Reduction in bleeding time and blood loss of TOCN-SF5-Th in rat tail amputation and liver avulsion model was comparable to commercial hemostat (Floseal). Surface morphology (SEM) of samples applied on bleeding site showed that RBCs and fibrin fiber could strongly interact with TOCN-SF and TOCN-SF-Th scaffolds. The result suggests that TOCN-SF-Th can be a promising candidate for designing hemostatic agents.

In Vivo flow Cytometry Combined with Intravital Microscopy to Monitor Synchronous Kinetics of Transplanted BM-MNCs in Peripheral Blood and Bone Marrow

Limited sources and finite numbers of hematopoietic stem cells (HSCs) have always been difficult problems to overcome in clinical HSC transplantation (HSCT). Improving the bone marrow (BM) homing efficiency of HSC has become an intensely studied topic. HSC homing involves the kinetics of transplanted cells in the peripheral blood (PB), the cell distribution in various organs and tissues, and the targeted homing of HSC to the BM. However, it is difficult to monitor the dynamic homing in living mice. The objective of this study is to establish a platform for monitoring the kinetics of transplanted BM-MNCs in the PB and the synchronous homing of BM-MNCs in the BM in living mice by a combination of in vivo flow cytometry (IVFC) and calvarium intravital microscopy.IVFC is a new in vivo technology that can quantitatively and continuously monitor fluorescence-labeled cells circulating in an anesthetized mouse. When a circulating fluorescent cell passes through the laser slit across the selected ear artery, fluorescence can be excited and recorded. Therefore, this method can provide continuous information on cellular behavior over time in the same living mouse without requiring extracting a blood sample at every time point. Calvarium intravital microscopy is another in vivo technology that allows a direct view of the dynamic homing of transplanted cells in the BM of a living mouse. Although the skull and femur are different bone types, the homing behavior and function of HSCs in the cross-road intersection region of coronal and sagittal sutures are comparable to those in the long bones in terms of immunophenotype and propagation. With calvarium intravital microscopy combined with in vivo flow cytometry, we here continually monitor the synchronous dynamic homing of transplanted BM-MNCs in the skull marrow in living mouse.By detecting the fluorescent cells in circulation, we obtained the kinetics of transplanted BM-MNCs in the PB over 24 h. Interestingly, the number of BM-MNCs decreased rapidly about 90% in the PB within the first 4 h after transplantation, further decreasing from 4 h to 6 h, and remaining at a low level from 6 h to 24 h. We further applied calvarium intravital microscopy to directly visualize the localization and the synchronous homing kinetics of BM-MNCs in the mouse skull marrow after transplantation. Interestingly, the BM-MNCs were mainly distributed over the large vessels in the cross-road intersection of coronal and sagittal sutures at 24 h, especially within the anterior half of this region (90-95% of total fluorescent cells). We then mainly measured the synchronous homing kinetics of BM-MNCs in the anterior half region at 2, 6, and 24 h in the mice, and found out that the homing of BM-MNCs in the skull marrow indeed increased gradually in the same mouse with the same pattern in different transplanted mice. Both the data obtained by IVFC and the calvarium intravital microscopy had a good linear correlation with their respective conventional in vitro flow cytometry data. By combining the conventional in vitro data, we also found a similar synchronous kinetics of BM-MNCs in the PB and the BM. All these data suggest that the BM-MNCs cleared from the PB might home to the BM over time after transplantation.In summary, as an important source of HSCs, BM-MNCs have been successfully applied to clinical HSCT. Understanding the early homing mechanism of transplanted BM-MNCs can enhance the marrow homing efficiency and engraftment of HSCs. Some other in vivo methods have been developed to study the homing of transplanted BM-MNCs to BM, including magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), endoscopic probing, and femur drilling to a laser-detectable depth. Compared to these methods, our method by calvarium intravital microscopy is mildly invasive, while the homing kinetics of BM-MNCs to the BM can be directly viewed and measured at the single-cell level. DisclosuresNo relevant conflicts of interest to declare.

Rats and rabbits as pharmacokinetic screening tools for long acting intramuscular depots: case study with paliperidone palmitate suspension

Development of prodrug of 9-hydroxyrisperidone (paliperidone) long-acting intramuscular injection has enabled delivery over four-week time period with improved compliance.The key aim of this work was to establish a reliable preclinical model which may potentially serve as a screening tool for judging the pharmacokinetics of paliperidone formulation(s) prior to human clinical work.Sparse sampling composite study was used in rats, (Wistar/Sprague–Dawley (SD; n = 10)) and a serial blood sampling study design was used in rabbits (n = 4). Animals received intramuscular injection of paliperidone palmitate in the thigh muscle at dose of 16 (rats) and 4.5 mg/kg (rabbits). Samples were drawn in rats (retro-orbital sinus) and rabbits (central ear artery) and were analysed for paliperidone using liquid chromatography–mass spectrometry/ mass spectrometry (LC-MS/MS) assay. The plasma data was subjected to pharmacokinetic analysis.Following intramuscular injection of depot formulation in Wistar/SD rats and rabbits, absorption of paliperidone was slow and gradual with median value of time to reach maximum concentration (Tmax) occurring on day 7. The exposures (i.e. area under the curve (AUC; 0–28) days) were 18,597, 21,865 and 18,120 ng.h/mL, in Wistar, SD and rabbits, respectively. The clearance was slow and supported long half-life (8–10 days).Either one of the two models can serve as a research tool for establishing pharmacokinetics of paliperidone formulation(s).

Dexmedetomidine Modification of the Chemoreflex Response to Severe Arterial Hypoxia in the Rabbit

The carotid body contains alpha‐2 adrenoceptors but selective agonists given during hypoxia have shown inhibition or enhancement of carotid sinus nerve activity in vivo (1), and in vitro (2). Dexmedetomidine (DM) is a highly‐selective alpha‐2 adrenergic agonist currently used for clinical sedation and analgesia (3,4) but its effects on integrated chemoreflex control during hypoxia are unknown. We examined the hypothesis that DM would selectively alter components of the cardiorespiratory responses to severe arterial hypoxia (PaO2 &lt;35 mm Hg). An ear artery and vein of 6 New Zealand White female rabbits were cannulated (lidocaine 2%). Mean arterial pressure (AP), arterial blood gases, heart rate (HR), minute ventilation (VE), tidal volume (VT), respiratory frequency (f) and oxygen saturation (ear SpO2) were measured breathing room air, followed by 5 minutes of hypoxia (FiO2 7–8%). After a one‐hour recovery period, the measurements were repeated during intravenous DM infusions (4 or 40 mcg/kg/hr), breathing room air followed by exposure to a matched hypoxic stimulus. One dose of DM was studied on each of two experimental days, one week apart. Behavioural responses were recorded before and during DM infusions. Data were analysed using two‐way repeated measures ANOVA. Significant differences were accepted at the p&lt;0.05 level. In the absence of DM, hypoxia alone evoked a reflex fall in HR and f, with increases in VT, VE and AP. In rabbits breathing room air, DM alone caused dose‐dependent falls in f, VE, HR and AP, while VT was unchanged. With DM plus hypoxia, the reflex bradycardia was absent at the higher dose. The increase in VT remained intact during both doses, while the rise in VE was attenuated due to an unchanged f. The AP increased from a lowered baseline. DM produced dose‐dependent sedation. We conclude reflex vagal control of heart rate during severe hypoxia is modified by DM. There are dose‐dependent effects on AP and components of ventilation. The increase in VT in response to hypoxia during DM infusion indicates that chemotransduction at the carotid body is intact. The data suggest the main sites of action of dexmedetomidine on cardiorespiratory control during hypoxia are within the CNS and not at the carotid body.Support or Funding InformationJohn Hunter Hospital Charitable Trust and Hunter Medical Research InstituteThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A multiscale active structural model of the arterial wall accounting for smooth muscle dynamics.

Arterial wall dynamics arise from the synergy of passive mechano-elastic properties of the vascular tissue and the active contractile behaviour of smooth muscle cells (SMCs) that form the media layer of vessels. We have developed a computational framework that incorporates both these components to account for vascular responses to mechanical and pharmacological stimuli. To validate the proposed framework and demonstrate its potential for testing hypotheses on the pathogenesis of vascular disease, we have employed a number of pharmacological probes that modulate the arterial wall contractile machinery by selectively inhibiting a range of intracellular signalling pathways. Experimental probes used on ring segments from the rabbit central ear artery are: phenylephrine, a selective α1-adrenergic receptor agonist that induces vasoconstriction; cyclopiazonic acid (CPA), a specific inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase; and ryanodine, a diterpenoid that modulates Ca2+ release from the sarcoplasmic reticulum. These interventions were able to delineate the role of membrane versus intracellular signalling, previously identified as main factors in smooth muscle contraction and the generation of vessel tone. Each SMC was modelled by a system of nonlinear differential equations that account for intracellular ionic signalling, and in particular Ca2+ dynamics. Cytosolic Ca2+ concentrations formed the catalytic input to a cross-bridge kinetics model. Contractile output from these cellular components forms the input to the finite-element model of the arterial rings under isometric conditions that reproduces the experimental conditions. The model does not account for the role of the endothelium, as the nitric oxide production was suppressed by the action of L-NAME, and also due to the absence of shear stress on the arterial ring, as the experimental set-up did not involve flow. Simulations generated by the integrated model closely matched experimental observations qualitatively, as well as quantitatively within a range of physiological parametric values. The model also illustrated how increased intercellular coupling led to smooth muscle coordination and the genesis of vascular tone.

Carbon nanotube-modified oxidized regenerated cellulose gauzes for hemostatic applications

Functionalized carbon nanotubes have recently received interest because of their unique properties, especially in the biomedical field. In this research, unmodified multiwalled carbon nanotubes (MWCNTs), and functionalized carbon nanotubes with amino groups (MWCNTs-NH2) and carboxyl groups (MWCNTs-COOH) were grafted to oxidized regenerated cellulose (ORC) gauze to fabricate novel functionalized ORC, and the performance of the functionalized gauze was investigated. The functionalized ORC was characterized by FT-IR, XPS and SEM, which showed the different kinds of CNTs grafted on its surface. The XPS results demonstrated the successful incorporation of functionalized MWCNTs in the active layer of modified ORC gauze. Meanwhile, the specific surface area of the CNTs modified functionalized ORC gauze was improved in varying degrees, whereas the porosity was slightly decreased. Furthermore, hydrophilicity experiment results presented a significant increment in water uptake of the functionalized CNTs grafted to the surface of the ORC gauze. Results of the hemostatic performance test on rabbit ear artery and liver showed that compared with the original ORC gauze, the bleeding time was significantly reduced when using the functionalized CNTs modified ORC hemostatic gauze. Moreover, the results also showed that the MWCNTs-COOH/ORC functionalized gauze had outstanding hemostatic efficiency.

Different chemical groups modification on the surface of chitosan nonwoven dressing and the hemostatic properties

The hemostatic properties of surface modified chitosan nonwoven had been investigated. The succinyl groups, carboxymethyl groups and quaternary ammonium groups were introduced into the surface of chitosan nonwoven (obtained NSCS, CMCS and TMCS nonwoven, respectively). For blood clotting, absorbance value (0.105±0.03) of NSCS1 nonwoven was the smallest (CS 0.307±0.002, NSCS2 0.148±0.002, CMCS1 0.195±0.02, CMCS2 0.233±0.001, TMCS1 0.191±0.002, TMCS2 0.345±0.002), which indicated the stronger hemostatic potential. For platelet aggregation, adenosine diphosphate agonist was added to induce the nonwoven to adhered platelets. The aggregation of platelet with TMCS2 nonwoven was highest (10.97±0.16%). Further research of blood coagulation mechanism was discussed, which indicated NSCS and CMCS nonwoven could activate the intrinsic pathway of coagulation to accelerate blood coagulation. NSCS1 nonwoven showed the shortest hemostatic time (147±3.7s) and the lowest blood loss (0.23±0.05g) in a rabbit ear artery injury model. These results demonstrated that these surface modified chitosan nonwoven dressings could use as a promising hemostatic intervention, especially NSCS nonwoven dressing.

Bone marrow cell composition and morphology in healthy juvenile female New Zealand White rabbits (Oryctolagus cuniculus).

OBJECTIVE To provide contemporary preliminary guidelines for the morphological evaluation of bone marrow in conjunction with CBC results for healthy juvenile (3- to 6-month-old) female New Zealand White rabbits (Oryctolagus cuniculus). ANIMALS 22 female New Zealand White rabbits. PROCEDURES Each rabbit was sedated, and a blood sample (3 mL) was collected from an ear artery for a CBC, after which the rabbit was euthanized. Within 5 minutes after euthanasia, bone marrow samples were obtained from the femur for cytologic and histologic evaluation. Bone marrow specimens for cytologic evaluation were stained with modified Wright stain, and those for histologic evaluation were stained with either H&E or Prussian blue stain. RESULTS The CBC results were within published reference ranges for all rabbits except 4, each of which had mild leukopenia. Cytologic assessment of bone marrow revealed a median myeloid-to-erythroid ratio of 0.7 and 2.8 megakaryocytes/low-power field (magnification, 100X), and the median percentages of lymphocytes, plasma cells, and macrophages were 11.5%, 0.1%, and 0%, respectively. The myeloid-to-erythroid ratio was not significantly correlated with any CBC variable. On histologic evaluation of bone marrow, the cellularity ranged from 30% to 50%, there were 2.1 to 7.7 megakaryocytes/hpf (magnification, 400X), and no iron stores were visible in H&E or Prussian blue-stained specimens. CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study provided contemporary preliminary guidelines for the evaluation of bone marrow in healthy laboratory rabbits.

Preparation and evaluation of chitosan/alginate porous microspheres/Bletilla striata polysaccharide composite hemostatic sponges.

We prepared a novel hemostatic material using chitosan (CS), alginate, and Bletilla striata, which showed good biocompatibility and hemostatic properties. Alginate-calcium porous microspheres (Alg) were prepared by emulsification/cross-linking methods, and Bletilla striata polysaccharide (Bsp) was extracted from the tubers by water extraction and alcohol precipitation. To improve the water absorption and accelerate the blood coagulation, Alg and Bsp were mixed with chitosan solution to form CS/Alg and CS/Alg/Bsp composite sponges by lyophilization. Based on SEM images, the microspheres exhibited good spherical shape, possessed many pores on the surface, and were well dispersed in the CS/Alg5 and CS/Alg10 composite sponges. The CS/Alg10 composite sponges showed higher water absorption and porosity. In addition, the cytotoxicity assay and hemostatic property of the CS/Alg and CS/Alg/Bsp composite sponges were tested by CCK-8 assay, in vitro blood clotting, red blood cell (RBC) adhesion, and rabbit ear artery bleeding. These ternary composite sponges could be used as potential novel hemostatic materials in surgical treatment.

A rabbit model of aneurysmal subarachnoid hemorrhage by ear central artery-suprasellar cistern shunt

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening hemorrhagic cerebrovascular disease. The concept of early brain injury (EBI), induced by sharply increased intracranial pressure (ICP) and low cerebral perfusion pressure (CPP) with cerebral global ischemia following aneurysm rupture, has been increasingly accepted. However, EBI has not been well studied partly due to lack of an ideal animal model. The purpose of this study was to establish a new aSAH model which can mimic the pathophysiological damage of EBI. Right frontal craniotomy was performed on New Zealand rabbits for placing a PE-50 tube at the suprasella cistern and an ICP probe at the anterior cranial fossa. The central ear artery was punctured and blood was shunted into the suprasellar cistern through the PE-50 tube. ICP, blood pressure, CPP and heart rate peri-aSAH were monitored throughout the experiments. The rabbits were examined for neurological deficits at 24h post-SAH. Brain coronal sections near the optic chiasma were assessed by HE and Cresyl violet staining. Three minutes after SAH induction, the ICP peaked to 61.7±9.8mmHg while CPP decreased to nadir 23.5±8.9mmHg, and both were gradually restored in 15min. At 24h post-SAH, significant neurological deficits were found in SAH rabbits as compared to the sham-operated animals. In addition, neuronal degeneration and loss were also detected. Our results indicate that a new rabbit model of aSAH with EBI is successfully established. Moreover, this model is controllable, economical, and no side-injury to the main artery.