Bioenergetics and neuroimaging research: a neuropathophysiological linkage in the setting of cocaine use amongst persons with HIV

Despite innovations in antiretroviral therapy (ART) that have transformed HIV infection from an acute illness with high mortality risk into a chronic, largely manageable disease, the viral reservoir that persists in brain continues to pose a risk for neurocognitive impairment and other deleterious clinical outcomes. ART regimens can inhibit viral integration and suppress replication to nondetectable levels in plasma and cerebrospinal fluid (CSF) but do not eliminate viral reservoirs, including that in brain [1]. Moreover, HIV transcripts within CSF cells have been associated with brain injury despite suppressive ART [2]. Comorbid HIV and cocaine use exacerbates brain atrophy and neurocognitive decline despite viral suppression [3–5]. Intersecting factors disrupted by chronic cocaine use among people with HIV (PWH) contribute to HIV-associated neuropathology, including neurotransmitter signaling (particularly dopamine), neuroinflammation, blood–brain–barrier (BBB) integrity, and energy metabolism. Further, the neuropathological severity associated with HIV and cocaine is spatially heterogenous [6–8]. The healthy brain is energetically expensive and complex with region-specific, unique functional roles [9–11]. Further, compartmentalization of HIV infection in brain contributes to this heterogeneity [12]. Mechanistic links between HIV and cocaine require additional characterization to assess region-dependent contributions to develop therapeutic interventions for cocaine use disorder comorbid with HIV. Mamidi et al.[13] focused on associations between chronic cocaine use and HIV on glucose uptake. Using 18F-FDG PET/CT in a 2 × 2 experimental design with HIV (present/absent) and cocaine (present/absent) (N = 63), they showed the lowest uptake with both HIV and cocaine. One factor – HIV or cocaine – showed intermediate uptake, and neither factor showed the highest uptake. The pronounced impact of cocaine on HIV-associated neuropathology is, in part, due to disruption of dopaminergic neurotransmission. The dopamine system is linked to inflammation and immunological function. Brain regions with high basal dopamine levels, such as the striatum and substantia nigra, are amongst the most vulnerable to HIV [14]. Dopamine exposure to human macrophages results in elevated production of pro-inflammatory cytokines and chemokines [14]. Acutely, elevated dopamine concentrations due to cocaine use increase oxidative stress, exacerbated by Tat [15,16]. Chronically, cocaine use is associated with dopamine depletion, demonstrated by PET scanning research [17]. In addition, HIV itself is associated with dopamine depletion as well as neurocognitive impairment and depression [18] not investigated here. This constellation suggests a synergistic effect of HIV and cocaine on dopaminergic transmission. To the extent that dopaminergic neurotransmission impacts glucose uptake, only additive effects of HIV and cocaine were reported here. No interaction of HIV and cocaine was observed. A major hallmark of chronic HIV is elevated pro-inflammatory cytokine and chemokine production. Suppressed PWH still have elevated neuroinflammation in the parietal and occipital cortex and the globus pallidus. Neuroinflammation is associated with decreased neurocognitive performance and increased white matter damage supported by a PET study with [11C] PBR28 and neuropsychological testing [8]. Viral proteins, Tat and gp120, both facilitate the production of pro-inflammatory cytokine and chemokines that decrease BBB tight junction protein expression and are directly neurotoxic [19]. Loss of BBB integrity allows free virus and HIV-infected monocytes to enter brain, exacerbating neuronal damage [20]. Similarly, cocaine increases neuroinflammatory markers by activating microglial cells and disrupting BBB integrity – decreasing tight junction protein expression in human pericytes [21]. When measuring chronic cocaine-induced microglial activation in vivo, rhesus macaques displayed increased TSPO PET expression in dopamine-rich regions via [3H] PK-11195 [6,7]. However, humans with a history of chronic cocaine use assessed with TSPO PET via [11C] PBR28 displayed no significant changes [6,22]. Of note, increased TSPO expression using current tracers does not distinguish between microglial and astrocytic activation. Further, there are other limitations with the utility of both PK-11195 and PBR28 tracers. Hence, PET scanning studies are currently inconclusive, though studies using other methodologies support neuroinflammatory effects associated with cocaine. Cocaine has been linked with increased TNF-α expression and is well known to stimulate HIV replication through induction of NF-κB and activation of transcription through the HIV LTR. The increased expression of TNF-α induced by HIV might exacerbate that by cocaine. Pro-inflammatory cytokine production has been associated with dopamine depletion outside of HIV infection. This suggests an intrinsic link between chronic HIV despite suppression, ongoing neuroinflammation, and persistent dopamine depletion, which is associated with depression and neurocognitive symptoms. This linkage may also reflect the results reported here and suggests the possible clinical utility of TNF-α inhibitors and dopaminergic agonists for the treatment of depressive and neurocognitive symptoms in virally suppressed PWH, supporting normalization of brain glucose uptake. In adults, the brain\u27s immense energetic demands require roughly 20% of all glucose and constitute approximately the same proportion of total oxygen consumption during resting conditions [23,24]. Maintenance of brain metabolic homeostasis is particularly sensitive to metabolic coupling between types of brain cells that contribute to clinical disorders when disrupted [25–27]. Viral–host interactions after an infection like HIV shift bioenergetics for incompletely understood reasons. Changes in energetic metabolism have been reported to occur in vitro using cultured astrocytes, neurons, and microglia due to Tat and gp120 [28–30], cytokines and chemokines [31], oxidative stress [32], and ART [33]. In vivo, virally suppressed PWH display decreased glucose uptake in the frontal cortex and the anterior cingulate cortex via FDG-PET [34,35]. Altogether, these changes suggest a shift from metabolism of primarily glucose to other oxidative substrates. Moreover, in vitro, cocaine is associated with a similar metabolic shift [29]. As suggested above, energetic demands vary across brain regions. Recent studies suggest that the brain also uses other substrates, such as fatty acids, lactate, pyruvate, glutamate, glutamine, and ketone bodies, more frequently than previously considered [10,11,36]. The composition of substrates used may shift under various factors such as age, diet, brain activity or injury, cognitive reserve, and the presence of viral infections like HIV [26,37]. Hence, future studies should expand from the general study of glucose uptake as the primary substrate to other substrates and associated changes in oxidative stress and mitochondrial function. Clinical research suggests the importance of associated interacting comorbidities, such as cardiovascular disease, with HIV [38] and cocaine [39]. It should be noted that age, ethnicity, and education and concomitant opioid use were not able to be separately analyzed here. Of note, older age is also associated with dopamine depletion, suggesting a more prominent effect amongst older PWH. In addition to future studies examining other energy substrate outcome measures; improved control of extraneous factors; and integration of clinical outcomes of cocaine use among PWH, neuroimaging studies can be particularly helpful in examining spatial heterogeneity in energetic effects induced by toxic HIV protein and transcript burden as well as pro-inflammatory cytokine secretion associated with cocaine use. Yet, these methods incompletely capture metabolic changes in brain. It can be concluded that there remains much to explore as to how the bioenergetic shifts occurring due to HIV and cocaine may be mechanistically linked to clinical outcomes

RCFA For Recurring Impeller Failures In A 4.7 Mtpa LNG Train Propane Compressor

Lecturepg. 1-18A Root Cause Failure Analysis (RCFA) for repeated impeller blade failures in a five stage centrifugal propane compressor is described. The initial failure occurred in June 2007 with a large crack found in one blade on the third impeller and two large pieces released from adjacent blades on the fourth impeller. An RCFA was performed to determine the cause of the failures. The failure mechanism was identified to be high cycle fatigue. Several potential causes related to the design, manufacture, and operation of the compressor were examined. The RCFA concluded that the design and manufacture were sound and there were no conclusive issues with respect to operation. A specific root cause was not identified. In June 2009, a second case of blade cracking occurred with a piece once again released from a single blade on the fourth impeller. Due to the commonality with the previous instance this was identified as a repeat failure. Specifically, both cases had occurred in the same compressor whereas, two compressors operating in identical service in adjacent Liquefied natural Gas (LNG) trains had not encountered the problem. A second RCFA was accordingly launched with the ultimate objective of preventing further repeated failures. Both RCFA teams were established comprising of engineers from the End User (RasGas), the OEM (Elliott Group) and an independent consultancy (Southwest Research Institute). The scope of the current investigation included a detailed metallurgical assessment, impeller modal frequency assessment, steady and unsteady computational fluid dynamics (CFD) assessment, finite element analyses (FEA), fluid structure interaction (FSI) assessment, operating history assessment and a comparison change analysis. By the process of elimination, the most probable causes were found to be associated with: Vane wake excitation of either the impeller blade leading edge modal frequency from severe mistuning and/or unusual response of the 1-diameter cover/blades modal frequency: Mist carry over from third side load upstream scrubber; End of curve operation in the compressor rear section

Unregulated actin polymerization by WASp causes defects of mitosis and cytokinesis in X-linked neutropenia

Specific mutations in the human gene encoding the Wiskott-Aldrich syndrome protein (WASp) that compromise normal auto-inhibition of WASp result in unregulated activation of the actin-related protein 2/3 complex and increased actin polymerizing activity. These activating mutations are associated with an X-linked form of neutropenia with an intrinsic failure of myelopoiesis and an increase in the incidence of cytogenetic abnormalities. To study the underlying mechanisms, active mutant WASpI294T was expressed by gene transfer. This caused enhanced and delocalized actin polymerization throughout the cell, decreased proliferation, and increased apoptosis. Cells became binucleated, suggesting a failure of cytokinesis, and micronuclei were formed, indicative of genomic instability. Live cell imaging demonstrated a delay in mitosis from prometaphase to anaphase and confirmed that multinucleation was a result of aborted cytokinesis. During mitosis, filamentous actin was abnormally localized around the spindle and chromosomes throughout their alignment and separation, and it accumulated within the cleavage furrow around the spindle midzone. These findings reveal a novel mechanism for inhibition of myelopoiesis through defective mitosis and cytokinesis due to hyperactivation and mislocalization of actin polymerization

The Malta cistern mapping project : expedition II

This paper documents the second of two archeological expeditions that employed several underwater robot mapping and localization techniques. The goal of this project is to explore and map ancient cisterns located on the islands of Malta and Gozo. Dating back to 300 B.C., the cisterns of interest acted as water storage systems for fortresses, private homes, and churches. They often consisted of several connected chambers, still containing water. A Remotely Operated Vehicle (ROV), was deployed into cisterns to obtain video and sonar images. Using a variety of sonar based mapping techniques, two-dimensional maps of 18 different cisterns were created.peer-reviewe

A switchable controlled-NOT gate in a spin-chain NMR quantum computer

A method of switching a controlled-NOT gate in a solid-stae NMR quantum computer is presented. Qubits of I=1/2 nuclear spins are placed periodically along a quantum spin chain (1-D antiferromagnet) having a singlet ground state with a finite spin gap to the lowest excited state caused by some quantum effect. Irradiation of a microwave tuned to the spin gap energy excites a packet of triplet magnons at a specific part of the chain where control and target qubits are involved. The packet switches on the Suhl-Nakamura interaction between the qubits, which serves as a controlled NOT gate. The qubit initialization is achieved by a qubit initializer consisting of semiconducting sheets attached to the spin chain, where spin polarizations created by the optical pumping method in the semiconductors are transferred to the spin chain. The scheme allows us to separate the initialization process from the computation, so that one can optimize the computation part without being restricted by the initialization scheme, which provides us with a wide selection of materials for a quantum computer.Comment: 8 pages, 5 figure

Placental uptake and metabolism of 25(OH)vitamin D determine its activity within the fetoplacental unit

Pregnancy 25-hydroxyvitamin D [25(OH)D] concentrations are associated with maternal and fetal health outcomes. Using physiological human placental perfusion and villous explants, we investigate the role of the placenta in regulating the relationships between maternal 25(OH)D and fetal physiology. We demonstrate active placental uptake of 25(OH)D3 by endocytosis, placental metabolism of 25(OH)D3 into 24,25-dihydroxyvitamin D3 and active 1,25-dihydroxyvitamin D [1,25(OH)2D3], with subsequent release of these metabolites into both the maternal and fetal circulations. Active placental transport of 25(OH)D3 and synthesis of 1,25(OH)2D3 demonstrate that fetal supply is dependent on placental function rather than simply the availability of maternal 25(OH)D3. We demonstrate that 25(OH)D3 exposure induces rapid effects on the placental transcriptome and proteome. These map to multiple pathways central to placental function and thereby fetal development, independent of vitamin D transfer. Our data suggest that the underlying epigenetic landscape helps dictate the transcriptional response to vitamin D treatment. This is the first quantitative study demonstrating vitamin D transfer and metabolism by the human placenta, with widespread effects on the placenta itself. These data demonstrate a complex interplay between vitamin D and the placenta and will inform future interventions using vitamin D to support fetal development and maternal adaptations to pregnancy.</jats:p

P. falciparum and P. vivax Epitope-Focused VLPs Elicit Sterile Immunity to Blood Stage Infections

In order to design P. falciparum preerythrocytic vaccine candidates, a library of circumsporozoite (CS) T and B cell epitopes displayed on the woodchuck hepatitis virus core antigen (WHcAg) VLP platform was produced. To test the protective efficacy of the WHcAg-CS VLPs, hybrid CS P. berghei/P. falciparum (Pb/Pf) sporozoites were used to challenge immunized mice. VLPs carrying 1 or 2 different CS repeat B cell epitopes and 3 VLPs carrying different CS non-repeat B cell epitopes elicited high levels of anti-insert antibodies (Abs). Whereas, VLPs carrying CS repeat B cell epitopes conferred 98% protection of the liver against a 10,000 Pb/Pf sporozoite challenge, VLPs carrying the CS non-repeat B cell eptiopes were minimally-to-non-protective. One-to-three CS-specific CD4/CD8 T cell sites were also fused to VLPs, which primed CS-specific as well as WHcAg-specific T cells. However, a VLP carrying only the 3 T cell domains failed to protect against a sporozoite challenge, indicating a requirement for anti-CS repeat Abs. A VLP carrying 2 CS repeat B cell epitopes and 3 CS T cell sites in alum adjuvant elicited high titer anti-CS Abs (endpoint dilution titer \u3e1x106) and provided 80–100% protection against blood stage malaria. Using a similar strategy, VLPs were constructed carrying P. vivax CS repeat B cell epitopes (WHc-Pv-78), which elicited high levels of anti-CS Abs and conferred 99% protection of the liver against a 10,000 Pb/Pv sporozoite challenge and elicited sterile immunity to blood stage infection. These results indicate that immunization with epitope-focused VLPs carrying selected B and T cell epitopes from the P.falciparum and P. vivax CS proteins can elicit sterile immunity against blood stage malaria. Hybrid WHcAg-CS VLPs could provide the basis for a bivalent P. falciparum/P. vivax malaria vaccine

Correlations of Gene Expression with Blood Lead Levels in Children with Autism Compared to Typically Developing Controls

The objective of this study was to examine the correlation between gene expression and lead (Pb) levels in blood in children with autism (AU, n = 37) compared to typically developing controls (TD, n = 15). We postulated that, though lead levels did not differ between the groups, AU children might metabolize lead differently compared to TD children. RNA was isolated from blood and processed on Affymetrix microarrays. Separate analyses of covariance (ANCOVA) corrected for age and gender were performed for TD, AU, and all subjects (AU + TD). To reduce false positives, only genes that overlapped these three ANCOVAs were considered. Thus, 48 probe sets correlated with lead levels in both AU and TD subjects and were significantly different between the groups (p(Diagnosis × log2 Pb) < 0.05). These genes were related mainly to immune and inflammatory processes, including MHC Class II family members and CD74. A large number (n = 791) of probe sets correlated (P ≤ 0.05) with lead levels in TD but not in AU subjects; and many probe sets (n = 162) correlated (P ≤ 0.05) with lead levels in AU but not in TD subjects. Only 30 probe sets correlated (P ≤ 0.05) with lead levels in a similar manner in the AU and TD groups. These data show that AU and TD children display different associations between transcript levels and low levels of lead. We postulate that this may relate to the underlying genetic differences between the two groups, though other explanations cannot be excluded