Interaction of Brucella abortus with Osteoclasts: a Step toward Understanding Osteoarticular Brucellosis and Vaccine Safety.

Osteoarticular disease is a frequent complication of human brucellosis. Vaccination remains a critical component of brucellosis control, but there are currently no vaccines for use in humans, and no in vitro models for assessing the safety of candidate vaccines in reference to the development of bone lesions currently exist. While the effect of Brucella infection on osteoblasts has been extensively evaluated, little is known about the consequences of osteoclast infection. Murine bone marrow-derived macrophages were derived into mature osteoclasts and infected with B. abortus 2308, the vaccine strain S19, and attenuated mutants S19vjbR and B. abortusΔvirB2 While B. abortus 2308 and S19 replicated inside mature osteoclasts, the attenuated mutants were progressively killed, behavior that mimics infection kinetics in macrophages. Interestingly, B. abortus 2308 impaired the growth of osteoclasts without reducing resorptive activity, while osteoclasts infected with B. abortus S19 and S19vjbR were significantly larger and exhibited enhanced resorption. None of the Brucella strains induced apoptosis or stimulated nitric oxide or lactose dehydrogenase production in mature osteoclasts. Finally, infection of macrophages or osteoclast precursors with B. abortus 2308 resulted in generation of smaller osteoclasts with decreased resorptive activity. Overall, Brucella exhibits similar growth characteristics in mature osteoclasts compared to the primary target cell, the macrophage, but is able to impair the maturation and alter the resorptive capacity of these cells. These results suggest that osteoclasts play an important role in osteoarticular brucellosis and could serve as a useful in vitro model for both analyzing host-pathogen interactions and assessing vaccine safety.

Intratracheal Inoculation with Brucella melitensis in the Pregnant Guinea Pig Is an Improved Model for Reproductive Pathogenesis and Vaccine Studies.

Reproductive failure is the hallmark of brucellosis in animals. An uncommon but important complication in pregnant women who become acutely infected with Brucella melitensis is spontaneous pregnancy loss or vertical transmission to the fetus. Unfortunately, the mechanism behind reproductive failure is still obscure, partially due to the lack of a proper study model. Recently, it was demonstrated that intratracheal (IT) inoculation of nonpregnant guinea pigs would replicate features of clinical disease in humans. To determine if IT inoculation would induce reproductive disease, guinea pigs were infected at mid-gestation and monitored daily for fever and abortions. Fever developed between day 14 to 18 postinoculation, and by 3 weeks postinoculation, 75% of pregnant guinea pigs experienced stillbirths or spontaneous abortions mimicking natural disease. Next, to investigate the guinea pig as a model for evaluating vaccine efficacy during pregnancy, nonpregnant guinea pigs were vaccinated with S19, 16MΔvjbR + Quil-A, or 100 µl PBS + Quil-A (as control). Guinea pigs were bred and vaccinated guinea pigs were challenged at mid-gestation with B. melitensis IT inoculation and monitored for fever and abortions. Vaccination with both vaccines prevented fever and protected against abortion. Together, this study indicates that pregnant guinea pigs are an appropriate animal model to study reproductive disease and offer an improved model to evaluate the ability of vaccine candidates to protect against a serious manifestation of disease.

Brucella abortus and Pregnancy in Mice: Impact of Chronic Infection on Fertility and the Role of Regulatory T Cells in Tissue Colonization.

Stealthy intracellular bacterial pathogens are known to establish persistent and sometimes lifelong infections. Some of these pathogens also have a tropism for the reproductive system, thereby increasing the risk of reproductive disease and infertility. To date, the pathogenic mechanism involved remains poorly understood. Here, we demonstrate that Brucella abortus, a notorious reproductive pathogen, has the ability to infect the nonpregnant uterus, sustain infection, and induce inflammatory changes during both acute and chronic stages of infection. In addition, we demonstrated that chronically infected mice had a significantly reduced number of pregnancies compared to naive controls. To investigate the immunologic mechanism responsible for uterine tropism, we explored the role of regulatory T cells (Tregs) in the pathogenesis of Brucella abortus infection. We show that highly suppressive CD4+FOXP3+TNFR2+ Tregs contribute to the persistence of Brucella abortus infection and that inactivation of Tregs with tumor necrosis factor receptor II (TNFR2) antagonistic antibody protected mice by significantly reducing bacterial burden both systemically and within reproductive tissues. These findings support a critical role of Tregs in the pathogenesis of persistence induced by intracellular bacterial pathogens, including B. abortus Results from this study indicate that adverse reproductive outcomes can occur as sequelae of chronic infection in nonpregnant animals and that fine-tuning Treg activity may provide novel immunotherapeutic and prevention strategies against intracellular bacterial infections such as brucellosis.

Correction: Garcia-Gonzalez, D.; Rivero, D.; Fernandez-Blanco, E.; Luaces, M.R. A Public Domain Dataset for Real-Life Human Activity Recognition Using Smartphone Sensors. Sensors 2020, 20, 2200.

The authors wish to make the following corrections to this paper [...].

A Public Domain Dataset for Real-Life Human Activity Recognition Using Smartphone Sensors.

In recent years, human activity recognition has become a hot topic inside the scientific community. The reason to be under the spotlight is its direct application in multiple domains, like healthcare or fitness. Additionally, the current worldwide use of smartphones makes it particularly easy to get this kind of data from people in a non-intrusive and cheaper way, without the need for other wearables. In this paper, we introduce our orientation-independent, placement-independent and subject-independent human activity recognition dataset. The information in this dataset is the measurements from the accelerometer, gyroscope, magnetometer, and GPS of the smartphone. Additionally, each measure is associated with one of the four possible registered activities: inactive, active, walking and driving. This work also proposes asupport vector machine (SVM) model to perform some preliminary experiments on the dataset. Considering that this dataset was taken from smartphones in their actual use, unlike other datasets, the development of a good model on such data is an open problem and a challenge for researchers. By doing so, we would be able to close the gap between the model and a real-life application.

The NOD-scid IL2rγnull Mouse Model Is Suitable for the Study of Osteoarticular Brucellosis and Vaccine Safety.

Osteoarticular brucellosis is the most common complication in Brucella-infected humans regardless of age, sex, or immune status. The mechanism of bone destruction caused by Brucella species remained partially unknown due to the lack of a suitable animal model. Here, to study this complication, we explored the suitability of the use of the NOD-scid IL2rγnull mouse to study osteoarticular brucellosis and examined the potential use of this strain to evaluate the safety of live attenuated vaccine candidates. Mice were inoculated intraperitoneally with a single dose of 1 × 104, 1 × 105, or 1 × 106 CFU of B. abortus S19 or the vaccine candidate B. abortus S19ΔvjbR and monitored for the development of side effects, including osteoarticular disease, for 13 weeks. Decreased body temperature, weight loss, splenomegaly, and deformation of the tails were observed in mice inoculated with B. abortus S19 but not in those inoculated with S19ΔvjbR Histologically, all S19-inoculated mice had a severe dose-dependent inflammatory response in multiple organs. The inflammatory response at the tail was characterized by the recruitment of large numbers of neutrophils, macrophages, and osteoclasts with marked bone destruction. These lesions histologically resembled what is typically observed in Brucella-infected patients. In contrast, mice inoculated with B. abortus S19ΔvjbR did not show significant bone changes. Immunofluorescence, in situ hybridization, and confocal imaging demonstrated the presence of Brucella at the sites of inflammation, both intra- and extracellularly, and large numbers of bacteria were observed within mature osteoclasts. These results demonstrate the potential use of the NOD-scid IL2rγnull mouse model to evaluate vaccine safety and further study osteoarticular brucellosis.

Tumor proliferation and invasion are intrinsically coupled and unraveled through tunable spheroid and physics-based models.

Proliferation and invasion are two key drivers of tumor growth that are traditionally considered independent multicellular processes. However, these processes are intrinsically coupled through a maximum carrying capacity, i.e., the maximum spatial cell concentration supported by the tumor volume, total cell count, nutrient access, and mechanical properties of the tissue stroma. We explored this coupling of proliferation and invasion through in vitro and in silico methods where we modulated the mechanical properties of the tumor and the surrounding extracellular matrix. E-cadherin expression and stromal collagen concentration were manipulated in a tunable breast cancer spheroid to determine the overall impacts of these tumor variables on net tumor proliferation and continuum invasion. We integrated these results into a mixed-constitutive formulation to computationally delineate the influences of cellular and extracellular adhesion, stiffness, and mechanical properties of the extracellular matrix on net proliferation and continuum invasion. This framework integrates biological in vitro data into concise computational models of invasion and proliferation to provide more detailed physical insights into the coupling of these key tumor processes and tumor growth. STATEMENT OF SIGNIFICANCE: Tumor growth involves expansion into the collagen-rich stroma through intrinsic coupling of proliferation and invasion within the tumor continuum. These processes are regulated by a maximum carrying capacity that is determined by the total cell count, tumor volume, nutrient access, and mechanical properties of the surrounding stroma. The influences of biomechanical parameters (i.e., stiffness, cell elongation, net proliferation rate and cell-ECM friction) on tumor proliferation or invasion cannot be unraveled using experimental methods alone. By pairing a tunable spheroid system with computational modeling, we delineated the interdependencies of each system parameter on tumor proliferation and continuum invasion, and established a concise computational framework for studying tumor mechanobiology.

Mechanical and Functional Responses in Astrocytes under Alternating Deformation Modes Using Magneto-Active Substrates.

This work introduces NeoMag, a system designed to enhance cell mechanics assays in substrate deformation studies. NeoMag uses multidomain magneto-active materials to mechanically actuate the substrate, transmitting reversible mechanical cues to cells. The system boasts full flexibility in alternating loading substrate deformation modes, seamlessly adapting to both upright and inverted microscopes. The multidomain substrates facilitate mechanobiology assays on 2D and 3D cultures. The integration of the system with nanoindenters allows for precise evaluation of cellular mechanical properties under varying substrate deformation modes. The system is used to study the impact of substrate deformation on astrocytes, simulating mechanical conditions akin to traumatic brain injury and ischemic stroke. The results reveal local heterogeneous changes in astrocyte stiffness, influenced by the orientation of subcellular regions relative to substrate strain. These stiffness variations, exceeding 50% in stiffening and softening, and local deformations significantly alter calcium dynamics. Furthermore, sustained deformations induce actin network reorganization and activate Piezo1 channels, leading to an initial increase followed by a long-term inhibition of calcium events. Conversely, fast and dynamic deformations transiently activate Piezo1 channels and disrupt the actin network, causing long-term cell softening. These findings unveil mechanical and functional alterations in astrocytes during substrate deformation, illustrating the multiple opportunities this technology offers.

Human exposures to Brucella canis from a pregnant dog during an international flight: Public health risks, diagnostic challenges and future considerations.

AIMS: This report documents the exposure of passengers and crew of a commercial international flight to the zoonotic pathogen Brucella canis after an infected dog aborted in the passenger cabin of the aircraft. This case demonstrates the challenges associated with brucellosis screening and the risks that airline personnel, airport employees and travellers face when animals with unrecognized zoonotic infections are transported. METHODS/RESULTS: The public health investigation of this case was conducted by the Centers for Disease Control, the Illinois Department of Health and the Illinois Department of Agriculture, in collaboration with a local veterinary clinic and several academic and federal diagnostic laboratories. It included an extensive diagnostic evaluation of the dam and aborted foetuses to confirm a diagnosis of canine brucellosis. Passengers, airline personnel and staff from the veterinary clinic where the dogs were treated underwent risk assessments, and clinic staff also received detailed guidance regarding infection prevention practices. CONCLUSIONS: Animal shelters and breeding programs are recommended to screen dogs routinely for brucellosis, but it is not unusual for domestic or imported animals to have unknown health histories, including the dog's brucellosis status, at the time of purchase, adoption, or re-homing. Testing recommendations and requirements vary by state, making it challenging for state public health and animal health agencies to monitor and respond appropriately. This case highlights the importance of Brucella spp. screening in sexually intact dogs prior to breeding, purchase, or domestic or international transportation of the dogs. The transportation of pregnant dogs may present a previously unrecognized public health threat in addition to contributing to unnecessary stress and health risks for pregnant animals.

Handgrip Strength Is Associated with Specific Aspects of Vascular Function in Individuals with Metabolic Syndrome.

BACKGROUND: Metabolic syndrome (MetS) is a disorder associated with an increased risk for the development of diabetes mellitus and its complications. Lower isometric handgrip strength (HGS) is associated with an increased risk of cardiometabolic diseases. However, the association between HGS and arterial stiffness parameters, which are considered the predictors of morbidity and mortality in individuals with MetS, is not well defined. OBJECTIVE: To determine the association between HGS and HGS asymmetry on components of vascular function in adults with MetS. METHODS: We measured handgrip strength normalized to bodyweight (HGS/kg), HGS asymmetry, body composition, blood glucose, lipid profile, blood pressure, pulse wave velocity (PWV), reflection coefficient (RC), augmentation index @75 bpm (AIx@75) and peripheral vascular resistance (PVR) in 55 adults with a diagnosis of MetS between 25 and 54 years old. RESULTS: Mean age was 43.1 ± 7.0 years, 56.3% were females. HGS/kg was negatively correlated with AIx@75 (r = -0.440), p < 0.05, but these associations were not significant after adjusting for age and sex. However, when interaction effects between sex, HGS/kg and age were examined, we observed an inverse relationship between HGS/kg and AIx@75 in the older adults in the sample, whereas in the younger adults, a weak direct association was found. We also found a significant association between HGS asymmetry and PVR (beta = 30, 95% CI = 7.02; 54.2; p <0.012). CONCLUSIONS: Our findings suggest that in people with MetS, maintaining muscle strength may have an increasingly important role in older age in the attenuation of age-related increases in AIx@75-a marker of vascular stiffness-and that a higher HGS asymmetry could be associated with a greater vascular resistance.

Primary and memory immune responses against rough Brucella canis are less robust compared to smooth B. abortus and B. melitensis following intratracheal infection in mice.

Brucella canis is the cause of canine brucellosis, a globally distributed, zoonotic pathogen which primarily causes disease in dogs. B. canis is unique amongst the zoonotic Brucella spp. with its rough lipopolysaccharide, a trait typically associated with attenuation in gram-negative bacteria. Unfortunately, no vaccine is available against B. canis, and vaccine development is hampered by a limited understanding of the immune response required to combat it and the course of infection following a physiologically relevant, mucosal route of inoculation. To address these concerns and analyze the impact of the rough phenotype on the immune response, we infected mice intratracheally with rough B. canis or smooth B. melitensis or B. abortus. Bacterial colonization and histologic lesions were assessed in systemic target organs as well as locally in the lungs and draining mediastinal lymph node. Mice were also reinfected with Brucella following antibiotic treatment and cytokine production by T lymphocytes in the lung and spleen was assessed by flow cytometry to investigate the memory immune response. Despite its rough phenotype, B. canis established a persistent infection at the same level of colonization as the smooth strains. However, B. canis induced significantly less granulomatous inflammation in the spleen as well as a lack of bronchial-associated lymphoid tissue (BALT) hyperplasia in the lungs. These differences coincided with increased IL-10 and decreased IFN-γ in the spleen of B. canis-infected mice. Previous exposure to all Brucella strains provided protection against colonization following secondary challenge, although induction of IFN-γ by T lymphocytes was seen only in the lungs during B. canis infection while the smooth strains induced this cytokine in the spleen as well. Neither Brucella strain induced significant polyfunctional T lymphocytes, a potential immunomodulatory mechanism that appears to be independent of lipopolysaccharide phenotype.

A Machine Learning Enhanced Mechanistic Simulation Framework for Functional Deficit Prediction in TBI.

Resting state functional magnetic resonance imaging (rsfMRI), and the underlying brain networks identified with it, have recently appeared as a promising avenue for the evaluation of functional deficits without the need for active patient participation. We hypothesize here that such alteration can be inferred from tissue damage within the network. From an engineering perspective, the numerical prediction of tissue mechanical damage following an impact remains computationally expensive. To this end, we propose a numerical framework aimed at predicting resting state network disruption for an arbitrary head impact, as described by the head velocity, location and angle of impact, and impactor shape. The proposed method uses a library of precalculated cases leveraged by a machine learning layer for efficient and quick prediction. The accuracy of the machine learning layer is illustrated with a dummy fall case, where the machine learning prediction is shown to closely match the full simulation results. The resulting framework is finally tested against the rsfMRI data of nine TBI patients scanned within 24 h of injury, for which paramedical information was used to reconstruct in silico the accident. While more clinical data are required for full validation, this approach opens the door to (i) on-the-fly prediction of rsfMRI alterations, readily measurable on clinical premises from paramedical data, and (ii) reverse-engineered accident reconstruction through rsfMRI measurements.

Evaluation of the safety profile of the vaccine candidate Brucella melitensis 16MΔvjbR strain in goats.

Small ruminant brucellosis is caused by the Gram negative cocci-bacillus Brucella (B.) melitensis, the most virulent Brucella species for humans. In goats and sheep, middle to late-term gestation abortion, stillbirths and the delivery of weak infected offspring are the characteristic clinical signs of the disease. Vaccination with the currently available Rev. 1 vaccine is the best option to prevent and control the disease, although it is far from ideal. In this study, we investigate the safety of the B. melitensis 16MΔvjbR strain during a 15-month period beginning at vaccination of young goats, impregnation, delivery and lactation. Forty, 4 to 6 months old, healthy female crossbreed goats were randomly divided into four groups (n = 10) and immunized subcutaneously with a single vaccine dose containing 1x109 CFU of B. melitensis 16MΔvjbR delivered in alginate microcapsules or non-encapsulated. Controls received empty capsules or the commercially available Rev.1 vaccine. Seven months post-vaccination, when animals were sexually mature, all goats were naturally bred using brucellosis-free males, and allowed to carry pregnancies to term. Blood samples to assess the humoral immune response were collected throughout the study. At two months post-delivery, all dams and their offspring were euthanized and a necropsy was performed to collect samples for bacteriology and histology. Interestingly, none of the animals that received the vaccine candidate regardless of the formulation exhibited any clinical signs associated with vaccination nor shed the vaccine strain through saliva, vagina or the milk. Gross and histopathologic changes in all nannies and offspring were unremarkable with no evidence of tissue colonization or vertical transmission to fetuses. Altogether, these data demonstrate that vaccination with the mutant strain 16MΔvjbR is safe for use in the non-pregnant primary host.

Characterization of epididymal and testicular histologic lesions and use of immunohistochemistry and PCR on formalin-fixed tissues to detect Brucella canis in male dogs.

In male dogs, Brucella canis frequently causes epididymitis, ultimately resulting in testicular atrophy and infertility. Although B. canis predominantly affects the epididymis, the misleading term "orchitis" is still commonly used by clinicians. Of additional concern, diagnosis in dogs remains challenging because of variable sensitivity and specificity of serologic assays and fluctuations in bacteremia levels in infected dogs, reducing the sensitivity of blood culture. We describe here the histologic lesions in the scrotal contents of 8 dogs suspected of being infected with B. canis and clinically diagnosed with orchitis. We explored the possibility of using immunohistochemistry (IHC) and real-time PCR (rtPCR) in formalin-fixed, paraffin-embedded (FFPE) tissues to detect the presence of B. canis. Epididymitis of variable chronicity was identified in all 8 dogs, with only 3 also exhibiting orchitis. Using rtPCR, the presence of B. canis was identified in 4 of 8 dogs, with 3 of these 4 dogs also positive by IHC. These results suggest that rtPCR and IHC are promising techniques that can be used in FFPE tissues to detect B. canis when other detection techniques are unavailable. Additionally, accurate recognition of epididymitis rather than orchitis in suspect cases could aid in accurate diagnosis.

Constitutive Models for Dynamic Strain Aging in Metals: Strain Rate and Temperature Dependences on the Flow Stress.

A new constitutive model for Q235B structural steel is proposed, incorporating the effect of dynamic strain aging. Dynamic strain aging hugely affects the microstructural behavior of metallic compounds, in turn leading to significant alterations in their macroscopic mechanical response. Therefore, a constitutive model must incorporate the effect of dynamic strain aging to accurately predict thermo-mechanical deformation processes. The proposed model assumes the overall response of the material as a combination of three contributions: athermal, thermally activated, and dynamic strain aging stress components. The dynamic strain aging is approached by two alternative mathematical expressions: (i) model I: rate-independent model; (ii) model II: rate-dependent model. The proposed model is finally used to study the mechanical response of Q235B steel for a wide range of loading conditions, from quasi-static loading ( ε ˙ = 0.001   s - 1 and ε ˙ = 0.02   s - 1 ) to dynamic loading ( ε ˙ = 800   s - 1 and ε ˙ = 7000   s - 1 ), and across a broad range of temperatures ( 93   K - 1173   K ). The results from this work highlight the importance of considering strain-rate dependences (model II) to provide reliable predictions under dynamic loading scenarios. In this regard, rate-independent approaches (model I) are rather limited to quasi-static loading.

Medical imaging based in silico head model for ischaemic stroke simulation.

Stroke is one of the most common causes of death and a leading factor of disability in adults worldwide. It occurs when the blood supply to part of the brain is significantly reduced, potentially leading to the formation of brain oedema. Owing to the rigid nature of the skull, brain expansion results in the shifting of tissue structure, often captured by measurement of the midline shift (MLS). Clinically, MLS has been used in practice as an indication of stroke severity, potential tissue damage and as a way to assess whether decompressive surgery should be performed. However, a growing body of research points towards limitations in such predictive ability. Inspired by the recent progress made in traumatic brain injury simulations, in silico experiments appear as the ideal candidate to elucidate stroke consequences on brain tissues, e.g., morphological changes, in particular in the overarching context of computer model assisted clinical decision making support. To this end, two biologically-informed finite element head models, human and rat, were constructed to support such analysis. The main components of the models include magnetic resonance imaging-derived grey matter, white matter, cerebrospinal fluid and skull, while the human head model also includes the vasculature, additional cerebral components and axonal tractography. Constitutive models representing the mechanical behaviour of each component account in particular for the behaviour of brain tissues during the swelling process accompanying oedema development. The rat model was leveraged for the calibration of the swelling parameters, in turn used for the simulation of human stroke. Human oedema development as a result of stroke was simulated at three frequent locations: basal ganglia, fronto-opercular/anterior insula and temporo-parietal. All three cases exhibit a quadratic MLS evolution with time with the basal ganglia and temporo-parietal showing the largest and smallest values, respectively, at any given time. A proposed injury criterion for axonal tract damage was shown to be larger in the temporo-parietal case. Taken together, these results point towards i) the importance of considering stroke location when using the MLS as an indication of stroke severity, and ii) the potential lack of correlation between MLS value and tissue damage. Ultimately, we propose an in silico methodology that may hold promise in predicting stroke evolution based on an estimate of MLS and stroke location at a given time.

Evaluation of the Efficacy of the Brucella canis RM6/66 ΔvjbR Vaccine Candidate for Protection against B. canis Infection in Mice.

Brucella canis is a Gram-negative, facultative intracellular bacterium and the causative agent of canine brucellosis, a highly contagious disease of dogs that can be transmitted to humans. Unfortunately, no vaccine is available to prevent infection. We recently characterized the kinetics of B. canis infection in the mouse model, establishing the required dose necessary to achieve systemic infection. The objective of this study was to investigate the utility of the mouse model in assessing canine brucellosis vaccine candidates and to subsequently investigate the safety and efficacy of a live attenuated vaccine, the B. canis RM6/66 ΔvjbR strain. Mice vaccinated with a dose of 109 CFU of the vaccine strain by both intraperitoneal and subcutaneous routes were afforded significant protection against organ colonization and development of histopathologic lesions following intraperitoneal challenge. Addition of an adjuvant or a booster dose 2 weeks following initial vaccination did not alter protection levels. Vaccination also resulted in a robust humoral immune response in mice, and B. canis RM6/66 ΔvjbR was capable of activating canine dendritic cells in vitro These data demonstrate that the B. canis RM6/66 ΔvjbR strain shows promise as a vaccine for canine brucellosis and validates the mouse model for future vaccine efficacy studies.IMPORTANCE Canine brucellosis, caused by Brucella canis, is the primary cause of reproductive failure in dogs and represents a public health concern due to its zoonotic nature. Cases in dogs in the United States have been increasing due to the persistent nature of the bacterium, deficiencies in current diagnostic testing, and, most importantly, the lack of a protective vaccine. Current estimates place the seroprevalence of B. canis in the southern United States at 7% to 8%, but with the unprecedented rates of animals moving across state and international borders and the lack of federal regulations in regard to testing, the true seroprevalence of B. canis in the United States may very well be higher. Vaccination represents the most effective method of brucellosis control and, in response to the demand for a vaccine against B. canis, we have developed the live attenuated B. canis RM6/66 ΔvjbR vaccine strain capable of protecting mice against challenge.

Vaccine Candidate Brucella melitensis 16MΔvjbR Is Safe in a Pregnant Sheep Model and Confers Protection.

As a natural host species for Brucella melitensis, pregnant sheep offer an ideal model to evaluate vaccine candidates for safety. B. melitensis strain Rev. 1 has been used almost exclusively to prevent brucellosis in small ruminants, but it causes abortions when given to pregnant animals. To evaluate the comparative safety of the candidate Brucella melitensis 16MΔvjbR, pregnant sheep (n = 6) were vaccinated subcutaneously with 1 × 1010 CFU/ml of 16MΔvjbR or 1 × 109 CFU/ml Rev. 1 at a highly susceptible stage of gestation (approximately 70 days). 16MΔvjbR resulted in only 1 abortion (1 of 6) compared with 4 of 6 (66.7%) abortions in the Rev. 1 cohort. The placenta was evaluated by culture to determine if vaccination resulted in colonization. As another measure of safety, effects of B. melitensis on the fetus/offspring (vertical transmission) was evaluated by culture and histopathology of fetal tissues to determine if vaccination prevented infection of the fetus. Vaccination with 16MΔvjbR resulted in less vertical transmission than Rev. 1. To determine if vaccination was efficacious and could reduce tissue colonization in sheep, the same cohort of sheep were challenged 5 weeks postpartum by conjunctival inoculation with 1 × 107 CFU/ml B. melitensis Protection was similar between Rev. 1 and 16MΔvjbR, with no statistical difference in colonization in the target organs. Overall, the 16MΔvjbR vaccine was considered safer than Rev. 1 based on a reduced number of abortions and limited infection in the offspring. Future experiments are needed to further refine the vaccine dose to increase the safety margin and to evaluate protection in pregnant ewes.IMPORTANCE Brucellosis is one of the most commonly reported zoonotic disease with a worldwide distribution. Of the 12 Brucella species, Brucella melitensis is considered the most virulent and causes reproductive failure (abortions/stillbirths) in small ruminants, which can spread the disease to other animals or to humans. Vaccination of small ruminants is a key measure used to protect both human and animal health. However, the commercially available live-attenuated vaccine for Brucella melitensis Rev. 1 retains virulence and can cause disease in animals and humans. In order to evaluate the safety and efficacy in sheep, we vaccinated pregnant sheep with 16MΔvjbR Our results indicate that 16MΔvjbR was safer for use during pregnancy, provided a similar level of protection as Rev. 1, and could be considered an improved candidate for future vaccine trials.

Computational model of the mechanoelectrophysiological coupling in axons with application to neuromodulation.

For more than half a century, the action potential (AP) has been considered a purely electrical phenomenon. However, experimental observations of membrane deformations occurring during APs have revealed that this process also involves mechanical features. This discovery has recently fuelled a controversy on the real nature of APs: whether they are mechanical or electrical. In order to examine some of the modern hypotheses regarding APs, we propose here a coupled mechanoelectrophysiological membrane finite-element model for neuronal axons. The axon is modeled as an axisymmetric thin-wall cylindrical tube. The electrophysiology of the membrane is modeled using the classic Hodgkin-Huxley (H-H) equations for the Nodes of Ranvier or unmyelinated axons and the cable theory for the internodal regions, whereas the axonal mechanics is modeled by means of viscoelasticity theory. Membrane potential changes induce a strain gradient field via reverse flexoelectricity, whereas mechanical pulses result in an electrical self-polarization field following the direct flexoelectric effect, in turn influencing the membrane potential. Moreover, membrane deformation also alters the values of membrane capacitance and resistance in the H-H equation. These three effects serve as the fundamental coupling mechanisms between the APs and mechanical pulses in the model. A series of numerical studies was systematically conducted to investigate the consequences of interaction between the APs and mechanical waves on both myelinated and unmyelinated axons. Simulation results illustrate that the AP is always accompanied by an in-phase propagating membrane displacement of ≈1nm, whereas mechanical pulses with enough magnitude can also trigger APs. The model demonstrates that mechanical vibrations, such as the ones arising from ultrasound stimulations, can either annihilate or enhance axonal electrophysiology depending on their respective directionality and frequency. It also shows that frequency of pulse repetition can also enhance signal propagation independently of the amplitude of the signal. This result not only reconciles the mechanical and electrical natures of the APs but also provides an explanation for the experimentally observed mechanoelectrophysiological phenomena in axons, especially in the context of ultrasound neuromodulation.

Two mechanisms regulate directional cell growth in Arabidopsis lateral roots.

Morphogenesis in plants depends critically on directional (anisotropic) growth. This occurs principally perpendicular to the net orientation of cellulose microfibrils (CMFs), which is in turn controlled by cortical microtubules (CMTs). In young lateral roots of Arabidopsis thaliana, growth anisotropy also depends on RAB-A5c, a plant-specific small GTPase that specifies a membrane trafficking pathway to the geometric edges of cells. Here we investigate the functional relationship between structural anisotropy at faces and RAB-A5c activity at edges during lateral root development. We show that surprisingly, inhibition of RAB-A5c function is associated with increased CMT/CMF anisotropy. We present genetic, pharmacological, and modelling evidence that this increase in CMT/CMF anisotropy partially compensates for loss of an independent RAB-A5c-mediated mechanism that maintains anisotropic growth in meristematic cells. We show that RAB-A5c associates with CMTs at cell edges, indicating that CMTs act as an integration point for both mechanisms controlling cellular growth anisotropy in lateral roots.