17q21 Variants Disturb Mucosal Host Defense in Childhood Asthma.

Rationale: The strongest genetic risk factor for childhood-onset asthma, the 17q21 locus, is associated with increased viral susceptibility and disease-promoting processes.Objectives: To identify biological targets underlying the escalated viral susceptibility associated with the clinical phenotype mediated by the 17q21 locus.Methods: Genome-wide transcriptome analysis of nasal brush samples from 261 children (78 healthy, 79 with wheezing at preschool age, 104 asthmatic) within the ALLIANCE (All-Age-Asthma) cohort, with a median age of 10.0 (range, 1.0-20.0) years, was conducted to explore the impact of their 17q21 genotype (SNP rs72163891). Concurrently, nasal secretions from the same patients and visits were collected, and high-sensitivity mesoscale technology was employed to measure IFN protein levels.Measurements and Main Results: This study revealed that the 17q21 risk allele induces a genotype- and asthma/wheeze phenotype-dependent enhancement of mucosal GSDMB expression as the only relevant 17q21-encoded gene in children with preschool wheeze. Increased GSDMB expression correlated with the activation of a type-1 proinflammatory, cell-lytic immune, and natural killer signature, encompassing key genes linked to an IFN type-2-signature (IFNG, CXCL9, CXCL10, KLRC1, CD8A, GZMA). Conversely, there was a reduction in IFN type 1 and type 3 expression signatures at the mRNA and protein levels.Conclusions: This study demonstrates a novel disease-driving mechanism induced by the 17q21 risk allele. Increased mucosal GSDMB expression is associated with a cell-lytic immune response coupled with compromised airway immunocompetence. These findings suggest that GSDMB-related airway cell death and perturbations in the mucosal IFN signature account for the increased vulnerability of 17q21 risk allele carriers to respiratory viral infections during early life, opening new options for future biological interventions.The All-Age-Asthma (ALLIANCE) cohort is registered at www.clinicaltrials.gov (pediatric arm, NCT02496468).

Neuronal Activity Changes the Number of Neurons That Are Synaptically Connected to OPCs.

The timing and specificity of oligodendrocyte myelination during development, as well as remyelination after injury or immune attack, remain poorly understood. Recent work has shown that oligodendrocyte progenitors receive synapses from neurons, providing a potential mechanism for neuronal-glial communication. In this study, we investigated the importance of these neuroglial connections in myelination during development and during neuronal plasticity in the mouse hippocampus. We used chemogenetic tools and viral monosynaptic circuit tracing to analyze these connections and to examine oligodendrocyte progenitor cells (OPCs) proliferation, myelination, synapse formation, and neuronal-glial connectivity in vivo after increasing or decreasing neuronal activity levels. We found that increasing neuronal activity led to greater OPC activation and proliferation. Modulation of neuronal activity also altered the organization of neuronal-glial connections: while it did not impact the total number of RabV-labeled neuronal inputs, or the number of RabV-labeled inhibitory neuronal (IN) inputs, it did alter the number of RabV-labeled excitatory neuron to OPC connections. Overall, our findings support the idea that neuronal activity plays a crucial role in regulating OPC proliferation and activation as well as the types of neuronal inputs to OPCs, indicating that neuronal activity is important for OPC circuit composition and function.

The development of peripheral microvasculopathy with chronic metabolic disease in obese Zucker rats: a retrograde emergence?

The study of peripheral vasculopathy with chronic metabolic disease is challenged by divergent contributions from spatial (the level of resolution or specific tissue being studied) and temporal origins (evolution of the developing impairments in time). Over many years of studying the development of skeletal muscle vasculopathy and its functional implications, we may be at the point of presenting an integrated conceptual model that addresses these challenges within the obese Zucker rat (OZR) model. At the early stages of metabolic disease, where systemic markers of elevated cardiovascular disease risk are present, the only evidence of vascular dysfunction is at postcapillary and collecting venules, where leukocyte adhesion/rolling is elevated with impaired venular endothelial function. As metabolic disease severity and duration increases, reduced microvessel density becomes evident as well as increased variability in microvascular hematocrit. Subsequently, hemodynamic impairments to distal arteriolar networks emerge, manifesting as increasing perfusion heterogeneity and impaired arteriolar reactivity. This retrograde "wave of dysfunction" continues, creating a condition wherein deficiencies to the distal arteriolar, capillary, and venular microcirculation stabilize and impairments to proximal arteriolar reactivity, wall mechanics, and perfusion distribution evolve. This proximal arteriolar dysfunction parallels increasing failure in fatigue resistance, hyperemic responses, and O2 uptake within self-perfused skeletal muscle. Taken together, these results present a conceptual model for the retrograde development of peripheral vasculopathy with chronic metabolic disease and provide insight into the timing and targeting of interventional strategies to improve health outcomes.NEW & NOTEWORTHY Working from an established database spanning multiple scales and times, we studied progression of peripheral microvascular dysfunction in chronic metabolic disease. The data implicate the postcapillary venular endothelium as the initiating site for vasculopathy. Indicators of dysfunction, spanning network structures, hemodynamics, vascular reactivity, and perfusion progress in an insidious retrograde manner to present as functional impairments to muscle blood flow and performance much later. The silent vasculopathy progression may provide insight into clinical treatment challenges.

Postoperative complications after gastrointestinal pediatric surgical procedures: outcomes and socio-demographic risk factors.

BACKGROUND: Several socio-demographic characteristics are associated with complications following certain pediatric surgical procedures. In this comprehensive study, we sought to determine socio-demographic risk factors and resource utilization of children with complications after common pediatric surgical procedures. METHODS: We performed a population-based cohort study utilizing the 2016 Healthcare Cost and Use Project Kids' Inpatient Database (KID) to identify and characterize pediatric patients (age 0-21 years) in the United States with common inpatient pediatric gastrointestinal surgical procedures: appendectomy, cholecystectomy, colonic resection, pyloromyotomy and small bowel resection. Multivariable logistic regression modeling was used to identify socio-demographic predictors of postoperative complications. Length of stay and hospitalization costs for patients with and without postoperative complications were compared. RESULTS: A total of 66,157 pediatric surgical hospitalizations were identified. Of these patients, 2,009 had postoperative complications. Male sex, young age, African American and Native American race and treatment in a rural hospital were associated with significantly greater odds of postoperative complications. Mean length of stay was 4.58 days greater and mean total costs were $11,151 (US dollars) higher in the complication cohort compared with patients without complications. CONCLUSIONS: Postoperative complications following inpatient pediatric gastrointestinal surgery were linked to elevated healthcare-related expenditure. The identified socio-demographic risk factors should be considered in the risk stratification before pediatric surgical procedures. Targeted interventions are required to reduce preventable complications and surgical disparities.

Standardized Colon Ascendens Stent Peritonitis in Rats - a Simple, Feasible Animal Model to Induce Septic Acute Kidney Injury.

AKI in septic patients is associated with increased mortality and poor outcome despite major efforts to refine the understanding of its pathophysiology. Here, an in vivo model is presented that combines a standardized septic focus to induce AKI and an intensive care (ICU) setup to provide an advanced hemodynamic monitoring and therapy comparable in human sepsis. Sepsis is induced by standardized colon ascendens stent peritonitis (sCASP). AKI is investigated functionally by measurement of blood and urine samples as well as histologically by evaluation of histopathological scores. Furthermore, the advanced hemodynamic monitoring and the possibility of repetitive blood gas sampling enable a differentiated analysis of severity of induced sepsis. The sCASP method is a standardized, reliable and reproducible method to induce septic AKI. The intensive care setup, continuous hemodynamic and gas exchange monitoring, low mortality rate as well as the opportunity of detailed analyses of kidney function and impairments are advantages of this setup. Therefore, the described method may serve as a new standard for experimental investigations of septic AKI.

Neuron to Oligodendrocyte Precursor Cell Synapses: Protagonists in Oligodendrocyte Development and Myelination, and Targets for Therapeutics.

The development of neuronal circuitry required for cognition, complex motor behaviors, and sensory integration requires myelination. The role of glial cells such as astrocytes and microglia in shaping synapses and circuits have been covered in other reviews in this journal and elsewhere. This review summarizes the role of another glial cell type, oligodendrocytes, in shaping synapse formation, neuronal circuit development, and myelination in both normal development and in demyelinating disease. Oligodendrocytes ensheath and insulate neuronal axons with myelin, and this facilitates fast conduction of electrical nerve impulses via saltatory conduction. Oligodendrocytes also proliferate during postnatal development, and defects in their maturation have been linked to abnormal myelination. Myelination also regulates the timing of activity in neural circuits and is important for maintaining the health of axons and providing nutritional support. Recent studies have shown that dysfunction in oligodendrocyte development and in myelination can contribute to defects in neuronal synapse formation and circuit development. We discuss glutamatergic and GABAergic receptors and voltage gated ion channel expression and function in oligodendrocyte development and myelination. We explain the role of excitatory and inhibitory neurotransmission on oligodendrocyte proliferation, migration, differentiation, and myelination. We then focus on how our understanding of the synaptic connectivity between neurons and OPCs can inform future therapeutics in demyelinating disease, and discuss gaps in the literature that would inform new therapies for remyelination.

A Severe Case of Anaplastic Large Cell Lymphoma in a Previously Healthy Woman: Diagnostic and Therapeutic Challenges.

Anaplastic large cell lymphomas are an aggressive subtype of peripheral T-cell lymphomas that can manifest with a variety of symptoms. Our case highlights the importance of prompt tissue sampling, especially if an associated hemophagocytic lymphohistiocytosis is detected and no clinical improvement is observed upon glucocorticoid treatment.

Clinical characteristics and outcomes for paediatric patients admitted with congenital or acquired syphilis: a population-based cohort study.

OBJECTIVES: Paediatric congenital and acquired syphilis cases have been increasing since 2012 in the USA. Potential differences in associated hospitalisation trends and healthcare utilisation between the two syphilis entities have not yet been assessed. We sought to compare these entities and describe their clinical characteristics, distribution and impact in the USA. METHODS: We conducted a population-based cohort study using the 2016 Kids' Inpatient Database (KID) to identify and characterise syphilis-associated hospitalisations among paediatric patients (age 0-21 years) in the USA during the year of 2016. Length of stay and hospitalisation costs for patients with congenital and acquired syphilis were compared in multivariable models. RESULTS: A total of 1226 hospitalisations with the diagnosis of syphilis were identified. Of these patients, 958 had congenital syphilis and 268 were acquired cases. The mean cost of care for congenital syphilis was $23 644 (SD=1727), while the treatment of a patient with acquired syphilis on average cost $10 749 (SD=1966). Mean length of stay was 8 days greater and mean total costs were $12 895 (US dollars) higher in the congenital syphilis cohort compared with the acquired syphilis cohort. In congenital syphilis, there were greater frequency of cases in the Southern and Western regions of the USA (p<0.001). CONCLUSION: Congenital syphilis was associated with greater healthcare-related expenditure than acquired syphilis in paediatric patients. In addition to improving patient outcomes, congenital syphilis prevention efforts may significantly reduce healthcare utilisation burden and cost.

Altered post-capillary and collecting venular reactivity in skeletal muscle with metabolic syndrome.

KEY POINTS: With the development of the metabolic syndrome, both post-capillary and collecting venular dilator reactivity within the skeletal muscle of obese Zucker rats (OZR) is impaired. The impaired dilator reactivity in OZR reflects a loss in venular nitric oxide and PGI2 bioavailability, associated with the chronic elevation in oxidant stress. Additionally, with the impaired dilator responses, a modest increase in adrenergic constriction combined with an elevated thromboxane A2 production may contribute to impaired functional dilator and hyperaemic responses at the venular level. For the shift in skeletal muscle venular function with development of the metabolic syndrome, issues such as aggregate microvascular perfusion resistance, mass transport and exchange within with capillary networks, and fluid handling across the microcirculation are compelling avenues for future investigation. ABSTRACT: While research into vascular outcomes of the metabolic syndrome has focused on arterial/arteriolar and capillary levels, investigation into venular function and how this impacts responses has received little attention. Using the in situ cremaster muscle of obese Zucker rats (OZR; with lean Zucker rats (LZR) as controls), we determined indices of venular function. At ∼17 weeks of age, skeletal muscle post-capillary venular density was reduced by ∼20% in LZR vs. OZR, although there was no evidence of remodelling of the venular wall. Venular tone at ∼25 µm (post-capillary) and ∼75 µm (collecting) diameter was elevated in OZR vs. LZR. Venular dilatation to acetylcholine was blunted in OZR vs. LZR due to increased oxidant stress-based loss of nitric oxide bioavailability (post-capillary) and increased α1 - (and α2 -) mediated constrictor tone (collecting). Venular constrictor responses in OZR were comparable to LZR for most stimuli, although constriction to α1 -adrenoreceptor stimulation was elevated. In response to field stimulation of the cremaster muscle (0.5, 1, 3 Hz), venular dilator and hyperaemic responses to lower frequencies were blunted in OZR, but responses at 3 Hz were similar between strains. Venous production of TxA2 was higher in OZR than LZR and significantly higher than PGI2 production in either following arachidonic acid challenge. These results suggest that multi-faceted alterations to skeletal muscle venular function in OZR may contribute to alterations in upstream capillary pressure profiles and the transcapillary exchange of solutes and water under conditions of metabolic syndrome.

Increased peripheral vascular disease risk progressively constrains perfusion adaptability in the skeletal muscle microcirculation.

To determine the impact of progressive elevations in peripheral vascular disease (PVD) risk on microvascular function, we utilized eight rat models spanning "healthy" to "high PVD risk" and used a multiscale approach to interrogate microvascular function and outcomes: healthy: Sprague-Dawley rats (SDR) and lean Zucker rats (LZR); mild risk: SDR on high-salt diet (HSD) and SDR on high-fructose diet (HFD); moderate risk: reduced renal mass-hypertensive rats (RRM) and spontaneously hypertensive rats (SHR); high risk: obese Zucker rats (OZR) and Dahl salt-sensitive rats (DSS). Vascular reactivity and biochemical analyses demonstrated that even mild elevations in PVD risk severely attenuated nitric oxide (NO) bioavailability and caused progressive shifts in arachidonic acid metabolism, increasing thromboxane A2 levels. With the introduction of hypertension, arteriolar myogenic activation and adrenergic constriction were increased. However, while functional hyperemia and fatigue resistance of in situ skeletal muscle were not impacted with mild or moderate PVD risk, blood oxygen handling suggested an increasingly heterogeneous perfusion within resting and contracting skeletal muscle. Analysis of in situ networks demonstrated an increasingly stable and heterogeneous distribution of perfusion at arteriolar bifurcations with elevated PVD risk, a phenomenon that was manifested first in the distal microcirculation and evolved proximally with increasing risk. The increased perfusion distribution heterogeneity and loss of flexibility throughout the microvascular network, the result of the combined effects on NO bioavailability, arachidonic acid metabolism, myogenic activation, and adrenergic constriction, may represent the most accurate predictor of the skeletal muscle microvasculopathy and poor health outcomes associated with chronic elevations in PVD risk.

Distinct temporal phases of microvascular rarefaction in skeletal muscle of obese Zucker rats.

Evolution of metabolic syndrome is associated with a progressive reduction in skeletal muscle microvessel density, known as rarefaction. Although contributing to impairments to mass transport and exchange, the temporal development of rarefaction and the contributing mechanisms that lead to microvessel loss are both unclear and critical areas for investigation. Although previous work suggests that rarefaction severity in obese Zucker rats (OZR) is predicted by the chronic loss of vascular nitric oxide (NO) bioavailability, we have determined that this hides a biphasic development of rarefaction, with both early and late components. Although the total extent of rarefaction was well predicted by the loss in NO bioavailability, the early pulse of rarefaction developed before a loss of NO bioavailability and was associated with altered venular function (increased leukocyte adhesion/rolling), and early elevation in oxidant stress, TNF-α levels, and the vascular production of thromboxane A2 (TxA2). Chronic inhibition of TNF-α blunted the severity of rarefaction and also reduced vascular oxidant stress and TxA2 production. Chronic blockade of the actions of TxA2 also blunted rarefaction, but did not impact oxidant stress or inflammation, suggesting that TxA2 is a downstream outcome of elevated reactive oxygen species and inflammation. If chronic blockade of TxA2 is terminated, microvascular rarefaction in OZR skeletal muscle resumes, but at a reduced rate despite low NO bioavailability. These results suggest that therapeutic interventions against inflammation and TxA2 under conditions where metabolic syndrome severity is moderate or mild may prevent the development of a condition of accelerated microvessel loss with metabolic syndrome.

Sepsis-induced acute kidney injury by standardized colon ascendens stent peritonitis in rats - a simple, reproducible animal model.

BACKGROUND: Up to 50% of septic patients develop acute kidney injury (AKI). The pathomechanism of septic AKI is poorly understood. Therefore, we established an innovative rodent model to characterize sepsis-induced AKI by standardized colon ascendens stent peritonitis (sCASP). The model has a standardized focus of infection, an intensive care set up with monitoring of haemodynamics and oxygenation resulting in predictable impairment of renal function, AKI parameters as well as histopathology scoring. METHODS: Anaesthetized rats underwent the sCASP procedure, whereas sham animals were sham operated and control animals were just monitored invasively. Haemodynamic variables and blood gases were continuously measured. After 24 h, animals were reanesthetized; cardiac output (CO), inulin and PAH clearances were measured and later on kidneys were harvested; and creatinine, urea, cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) were analysed. Additional sCASP-treated animals were investigated after 3 and 9 days. RESULTS: All sCASP-treated animals survived, whilst ubiquitous peritonitis and significantly deteriorated clinical and macrohaemodynamic sepsis signs after 24 h (MAP, CO, heart rate) were obvious. Blood analyses showed increased lactate and IL-6 levels as well as leucopenia. Urine output, inulin and PAH clearance were significantly decreased in sCASP compared to sham and control. Additionally, significant increase in cystatin C and NGAL was detected. Standard parameters like serum creatinine and urea were elevated and sCASP-induced sepsis increased significantly in a time-dependent manner. The renal histopathological score of sCASP-treated animals deteriorated after 3 and 9 days. CONCLUSIONS: The presented sCASP method is a standardized, reliable and reproducible method to induce septic AKI. The intensive care set up, continuous macrohaemodynamic and gas exchange monitoring, low mortality rate as well as the opportunity of detailed analyses of kidney function and impairments are advantages of this setup. Thus, our described method may serve as a new standard for experimental investigations of septic AKI.

C-Peptide reduces mitochondrial superoxide generation by restoring complex I activity in high glucose-exposed renal microvascular endothelial cells.

Hyperglycemia-mediated microvascular damage has been proposed to originate from excessive generation of mitochondrial superoxide in endothelial cells and is the suggested mechanism by which the pathogenesis of diabetes-induced renal damage occurs. C-peptide has been shown to ameliorate diabetes-induced renal impairment. Yet, the mechanisms underlying this protective benefit remain unclear. The objective of this study was to determine whether C-peptide affords protection to renal microvascular endothelial cell mitochondria during hyperglycemia. Conditionally immortalized murine renal microvascular endothelial cells (MECs) were exposed to low (5.5 mM) or high glucose (25 mM) media with either C-peptide (6.6 nM) or its scrambled sequence control peptide for 24 or 48 hours. Respiratory control ratio, a measure of mitochondrial electrochemical coupling, was significantly higher in high glucose renal MECs treated with C-peptide than those of high glucose alone. C-peptide also restored high glucose-induced renal MEC mitochondrial membrane potential changes back to their basal low glucose state. Moreover, C-peptide prevented the excessive mitochondrial superoxide generation and concomitant reductions in mitochondrial complex I activity which are mediated by the exposure of the renal MECs to high glucose. Together, these data demonstrate that C-peptide protects against high glucose-induced generation of mitochondrial superoxide in renal MECs via restoration of basal mitochondrial function.

4D Cone-beam CT reconstruction using a motion model based on principal component analysis.

PURPOSE: To provide a proof of concept validation of a novel 4D cone-beam CT (4DCBCT) reconstruction algorithm and to determine the best methods to train and optimize the algorithm. METHODS: The algorithm animates a patient fan-beam CT (FBCT) with a patient specific parametric motion model in order to generate a time series of deformed CTs (the reconstructed 4DCBCT) that track the motion of the patient anatomy on a voxel by voxel scale. The motion model is constrained by requiring that projections cast through the deformed CT time series match the projections of the raw patient 4DCBCT. The motion model uses a basis of eigenvectors that are generated via principal component analysis (PCA) of a training set of displacement vector fields (DVFs) that approximate patient motion. The eigenvectors are weighted by a parameterized function of the patient breathing trace recorded during 4DCBCT. The algorithm is demonstrated and tested via numerical simulation. RESULTS: The algorithm is shown to produce accurate reconstruction results for the most complicated simulated motion, in which voxels move with a pseudo-periodic pattern and relative phase shifts exist between voxels. The tests show that principal component eigenvectors trained on DVFs from a novel 2D/3D registration method give substantially better results than eigenvectors trained on DVFs obtained by conventionally registering 4DCBCT phases reconstructed via filtered backprojection. CONCLUSIONS: Proof of concept testing has validated the 4DCBCT reconstruction approach for the types of simulated data considered. In addition, the authors found the 2D/3D registration approach to be our best choice for generating the DVF training set, and the Nelder-Mead simplex algorithm the most robust optimization routine.

Pulmonary particulate matter and systemic microvascular dysfunction.

Pulmonary particulate matter (PM) exposure has been epidemiologically associated with an increased risk of cardiovascular morbidity and mortality, but the mechanistic foundations for this association are unclear. Exposure to certain types of PM causes changes in the vascular reactivity of several macrovascular segments. However, no studies have focused upon the systemic microcirculation, which is the primary site for the development of peripheral resistance and, typically, the site of origin for numerous pathologies. Ultrafine PM--also referred to as nanoparticles, which are defined as ambient and engineered particles with at least one physical dimension less than 100 nm (Oberdorster et al. 2005)--has been suggested to be more toxic than its larger counterparts by virtue of a larger surface area per unit mass. The purpose of this study was fourfold: (1) determine whether particle size affects the severity of postexposure microvascular dysfunction; (2) characterize alterations in microvascular nitric oxide (NO) production after PM exposure; (3) determine whether alterations in microvascular oxidative stress are associated with NO production, arteriolar dysfunction, or both; and (4) determine whether circulating inflammatory mediators, leukocytes, neurologic mechanisms, or a combination of these play a fundamental role in mediating pulmonary PM exposure and peripheral microvascular dysfunction. To achieve these goals, we created an inhalation chamber that generates stable titanium dioxide (TiO2) aerosols at concentrations up to 20 mg/m3. TiO2 is a well-characterized particle devoid of soluble metals. Sprague Dawley and Fischer 344 (F-344) rats were exposed to fine or nano-TiO2 PM (primary count modes of approximately 710 nm and approximately 100 nm in diameter, respectively) at concentrations of 1.5 to 16 mg/m3 for 4 to 12 hours to produce pulmonary loads of 7 to 150 microg in each rat. Twenty-four hours after pulmonary exposure, the following procedures were performed: the spinotrapezius muscle was prepared for in vivo microscopy, blood samples were taken from an arterial line, and various tissues were harvested for histologic and immunohistochemical analyses. Some rats received a bolus dose of cyclophosphamide 3 days prior to PM exposure to deplete circulating neutrophils and bronchoalveolar lavage (BAL) was performed in separate groups of rats exposed to identical TiO2 loads. No significant differences in BAL fluid composition based on PM size or load were found in these rats. Plasma levels of interleukin (IL)-2, IL-18, IL-13, and growth-related oncogene (GRO) (also known as keratinocyte-derived-chemokine [KC]) were altered after PM exposure. In rats exposed to fine TiO2, endothelium-dependent arteriolar dilation was significantly decreased, and this dysfunction was robustly augmented in rats exposed to nano-TiO2. This effect was not related to an altered smooth-muscle responsiveness to NO because arterioles in both groups dilated comparably in response to the NO donor sodium nitroprusside (SNP). Endogenous microvascular NO production was similarly decreased after inhalation of either fine or nano-TiO2 in a dose-dependent manner. Microvascular oxidative stress was significantly increased among both exposure groups. Furthermore, treatment with antioxidants (2,2,6,6-tetramethylpiperdine-N-oxyl [TEMPOL] plus catalase), the myeloperoxidase (MPO) inhibitor 4-aminobenzoic hydrazide (ABAH), or the nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) inhibitor apocynin partially restored NO production and normalized arteriolar function in both groups. Neutrophil depletion restored dilation in PM-exposed rats by as much as 42%. Coincubation of the spinotrapezius muscle with the fast sodium (Na+) channel antagonist tetrodotoxin (TTX) restored arteriolar dilation by as much as 54%, suggesting that sympathetic neural input may be affected by PM exposure. The results of these experiments indicate that (1) the size of inhaled PM dictates the intensity of systemic microvascular dysfunction; (2) this arteriolar dysfunction is characterized by a decreased bioavailability of endogenous NO; (3) the loss of bioavailable NO after PM exposure is at least partially caused by elevations in local oxidative stress, MPO activity, NADPH oxidase activity, or a combination of these responses; and (4) circulating neutrophils and sympathetic neurogenic mechanisms also appear to be involved in the systemic microvascular dysfunction that follows PM exposure. Taken together, these mechanistic studies support prominent hypotheses that suggest peripheral vascular effects associated with PM exposure are due to the activation of inflammatory mechanisms, neurogenic mechanisms, or both.

Hypercholesterolemia and microvascular dysfunction: interventional strategies.

Hypercholesterolemia is defined as excessively high plasma cholesterol levels, and is a strong risk factor for many negative cardiovascular events. Total cholesterol levels above 200 mg/dl have repeatedly been correlated as an independent risk factor for development of peripheral vascular (PVD) and coronary artery disease (CAD), and considerable attention has been directed toward evaluating mechanisms by which hypercholesterolemia may impact vascular outcomes; these include both results of direct cholesterol lowering therapies and alternative interventions for improving vascular function. With specific relevance to the microcirculation, it has been clearly demonstrated that evolution of hypercholesterolemia is associated with endothelial cell dysfunction, a near-complete abrogation in vascular nitric oxide bioavailability, elevated oxidant stress, and the creation of a strongly pro-inflammatory condition; symptoms which can culminate in profound impairments/alterations to vascular reactivity. Effective interventional treatments can be challenging as certain genetic risk factors simply cannot be ignored. However, some hypercholesterolemia treatment options that have become widely used, including pharmaceutical therapies which can decrease circulating cholesterol by preventing either its formation in the liver or its absorption in the intestine, also have pleiotropic effects with can directly improve peripheral vascular outcomes. While physical activity is known to decrease PVD/CAD risk factors, including obesity, psychological stress, impaired glycemic control, and hypertension, this will also increase circulating levels of high density lipoprotein and improving both cardiac and vascular function. This review will provide an overview of the mechanistic consequences of the predominant pharmaceutical interventions and chronic exercise to treat hypercholesterolemia through their impacts on chronic sub-acute inflammation, oxidative stress, and microvascular structure/function relationships.

Carbon monoxide has antioxidative properties in the liver involving p38 MAP kinase pathway in a murine model of systemic inflammation.

OBJECTIVE: Reactive oxygen species (ROS) are important in the hepatocellular injury process during a systemic inflammation. We examined the role of carbon monoxide (CO) on the hepatic generation of ROS with in-vivo and in-vitro models of systemic inflammation. METHODS: Using a murine model of bilateral hindlimb ischemia-reperfusion (I/R) we examined the effect of CO treatment on hepatic ROS formation, oxidative status, and cell injury. Cultured HUVEC were used to investigate intracellular pathways. RESULTS: CO treatment reduced hepatic lipid peroxidation, re-established total hepatic glutathione and glutathione disulfide (GSH/GSSG) levels and reduced hepatocellular injury. Inhibition of heme oxygenase (HO) during treatment with CO during hindlimb I/R failed to alter the antioxidant qualities provided by CO. The production of ROS after tumor necrosis factor-α (TNF-α) stimulation in HUVEC was diminished after exposure to CO. Treatment with CO during HO inhibition reduced both ROS formation and cell injury. Inhibiting the p38 MAPK (mitogen-activated protein kinase) pathway with pyridinyl imidazol (SB203580) revealed that the antioxidant potential of CO involved the activation of p38 MAPK. CONCLUSIONS: CO has direct antioxidant potential independently of any HO activity during systemic inflammation. The antioxidant effects afforded by CO involve the activation of the p38 MAPK pathway.

Integration of skeletal muscle resistance arteriolar reactivity for perfusion responses in the metabolic syndrome.

Previous study suggests that with evolution of the metabolic syndrome, patterns of arteriolar reactivity are profoundly altered and may constrain functional hyperemia. This study investigated interactions between parameters of vascular reactivity at two levels of resistance arterioles in obese Zucker rats (OZR), translating these observations into perfusion regulation for in situ skeletal muscle. Dilation of isolated and in situ resistance arterioles from OZR to acetylcholine, arachidonic acid (AA), and hypoxia (isolated arterioles only) were blunted vs. lean Zucker rats (LZR), although dilation to adenosine was intact. Increased adrenergic tone (phenylephrine) or intralumenal pressure (ILP) impaired dilation in both strains (OZR>LZR). Treatment of OZR arterioles with Tempol (superoxide dismutase mimetic) or SQ-29548 (prostaglandin H2/thromboxane A2 receptor antagonist) improved dilator reactivity under control conditions and with increased ILP, but had minimal effect with increased adrenergic tone. Arteriolar dilation to adenosine was well maintained in both strains under all conditions. For in situ cremasteric arterioles, muscle contraction-induced elevations in metabolic demand elicited arteriolar dilations and hyperemic responses that were blunted in OZR vs. LZR, although distal parallel arterioles were characterized by heterogeneous dilator and perfusion responses. alpha-Adrenoreceptor blockade improved outcomes at rest but had minimal effect with elevated metabolic demand. Treatment with Tempol or SQ-29548 had minimal impact at rest, but lessened distal arteriolar perfusion heterogeneity with increased metabolic demand. In blood-perfused gastrocnemius of OZR, perfusion was constrained primarily by adrenergic tone, while myogenic activation and endothelium-dependent dilation did not appear to contribute significantly to ischemia. These results of this novel, integrated approach suggest that adrenergic tone and metabolic dilation are robust determinants of bulk perfusion to skeletal muscle of OZR, while endothelial dysfunction may more strongly regulate perfusion distribution homogeneity via the impact of oxidant stress and AA metabolism.

Alteration of renal respiratory Complex-III during experimental type-1 diabetes.

BACKGROUND: Diabetes has become the single most common cause for end-stage renal disease in the United States. It has been established that mitochondrial damage occurs during diabetes; however, little is known about what initiates mitochondrial injury and oxidant production during the early stages of diabetes. Inactivation of mitochondrial respiratory complexes or alteration of their critical subunits can lead to generation of mitochondrial oxidants, mitochondrial damage, and organ injury. Thus, one goal of this study was to determine the status of mitochondrial respiratory complexes in the rat kidney during the early stages of diabetes (5-weeks post streptozotocin injection). METHODS: Mitochondrial complex activity assays, blue native gel electrophoresis (BN-PAGE), Complex III immunoprecipitation, and an ATP assay were performed to examine the effects of diabetes on the status of respiratory complexes and energy levels in renal mitochondria. Creatinine clearance and urine albumin excretion were measured to assess the status of renal function in our model. RESULTS: Interestingly, of all four respiratory complexes only cytochrome c reductase (Complex-III) activity was significantly decreased, whereas two Complex III subunits, Core 2 protein and Rieske protein, were up regulated in the diabetic renal mitochondria. The BN-PAGE data suggested that Complex III failed to assemble correctly, which could also explain the compensatory upregulation of specific Complex III subunits. In addition, the renal F0F1-ATPase activity and ATP levels were increased during diabetes. CONCLUSION: In summary, these findings show for the first time that early (and selective) inactivation of Complex-III may contribute to the mitochondrial oxidant production which occurs in the early stages of diabetes.