Human Mesenchymal Stem Cells as a Carrier for a Cell-Mediated Drug Delivery.

A number of preclinical and clinical studies have demonstrated the efficiency of mesenchymal stromal cells to serve as an excellent base for a cell-mediated drug delivery system. Cell-based targeted drug delivery has received much attention as a system to facilitate the uptake a nd transfer of active substances to specific organs and tissues with high efficiency. Human mesenchymal stem cells (MSCs) are attracting increased interest as a promising tool for cell-based therapy due to their high proliferative capacity, multi-potency, and anti-inflammatory and immunomodulatory properties. In particular, these cells are potentially suitable for use as encapsulated drug transporters to sites of inflammation. Here, we studied the in vitro effects of incorporating synthetic polymer microcapsules at various microcapsule-to-cell ratios on the morphology, ultrastructure, cytokine profile, and migration ability of human adipose-derived MSCs at various time points post-phagocytosis. The data show that under appropriate conditions, human MSCs can be efficiently loaded with synthesized microcapsules without damaging the cell's structural integrity with unexpressed cytokine secretion, retained motility, and ability to migrate through 8 µm pores. Thus, the strategy of using human MSCs as a delivery vehicle for transferring microcapsules, containing bioactive material, across the tissue-blood or tumor-blood barriers to facilitate the treatment of stroke, cancer, or inflammatory diseases may open a new therapeutic perspective.

Nucleofection induces transient eIF2α phosphorylation by GCN2 and PERK.

Nucleofection permits efficient transfection even with difficult cell types such as primary and non-dividing cells, and is used to deliver various nucleic acids, including DNA, mRNA, and small interfering RNA. Unlike DNA and small interfering RNA, mRNA is subject to rapid degradation, which necessitates instant early translation following mRNA delivery. We examined the factors that are important in translation following nucleofection and observed rapid phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α) following nucleofection, which occurred in the absence of the delivered nucleic acid. We studied the involvement of three ubiquitous kinases capable of phosphorylating eIF2α in mammalian cells and identified that nucleofection-mediated phosphorylation of eIF2α was dependent on general control non-derepressible 2 (GCN2) and RNA-dependent protein kinase (PKR)-like endoplasmic reticulum kinase (PERK) but not PKR. A reduction in translation due to eIF2α phosphorylation was observed post nucleofection, demonstrating functional significance. Understanding the impact of nucleofection on translational machinery has important implications for therapeutics currently under development based on the delivery of mRNA, DNA, and small interfering RNA. Strategies to circumvent eIF2α phosphorylation and other downstream effects of activating GCN2 and PERK will facilitate further advancement of nucleic acid-based therapies.

Risk factors for mortality among MDR- and XDR-TB patients in a high HIV prevalence setting.

SETTING: Recent studies suggest that the prevalence of drug-resistant tuberculosis (TB) in sub-Saharan Africa may be rising. This is of concern, as human immunodeficiency virus (HIV) co-infection in multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB has been associated with exceedingly high mortality rates. OBJECTIVE: To identify risk factors associated with mortality in MDR- and XDR-TB patients co-infected with HIV in South Africa. DESIGN: Case-control study of patients who died of all causes within 2 years of diagnosis with MDR- or XDR-TB. RESULTS: Among 123 MDR-TB patients, 78 (63%) died following diagnosis. CD4 count ≤ 50 (HR 4.64, P = 0.01) and 51-200 cells/mm(3) (HR 4.17, P = 0.008) were the strongest independent risk factors for mortality. Among 139 XDR-TB patients, 111 (80%) died. CD4 count ≤ 50 cells/mm(3) (HR 4.46, P = 0.01) and resistance to all six drugs tested (HR 2.54, P = 0.04) were the principal risk factors. Use of antiretroviral therapy (ART) was protective (HR 0.34, P = 0.009). CONCLUSIONS: Mortality due to MDR- and XDR-TB was associated with greater degree of immunosuppression and drug resistance. Efforts to reduce mortality must focus on preventing the amplification of resistance by strengthening TB treatment programs, as well as reducing the pool of immunosuppressed HIV-infected patients through aggressive HIV testing and ART initiation.

Antiviral activities in human saliva.

In this review, the authors survey the large number of antibacterial and antiviral proteins present in human saliva. Of interest, most of these antibacterial proteins display antiviral activity, typically against specific viral pathogens. The review focuses on one protein that interacts with both bacteria and viruses-gp340, originally referred to as salivary agglutinin. In the oral cavity, soluble gp340 binds to and aggregates a variety of bacteria, and this is thought to increase bacterial clearance from the mouth. However, when bound to the tooth surface, gp340 promotes bacterial adherence. In the oral cavity, most gp340 is found soluble in saliva and can function as a specific inhibitor of infectivity of HIV-1 and influenza A. In contrast, in the female reproductive track, most gp340 is bound to the cell surface, where it can promote HIV-1 infection.

Momentary reductions of attention permit greater processing of irrelevant stimuli.

Momentary reductions of attention can have extremely adverse outcomes, but it remains unclear whether increased distraction from irrelevant stimuli contributes to such outcomes. To investigate this hypothesis, we examined trial-by-trial relationships between brain activity and response time in twenty healthy adults while they performed a cross-modal selective attention task. In each trial, participants identified a relevant visual letter while ignoring an irrelevant auditory letter, which was mapped either to the same response as the visual letter (congruent trials) or to a different response (incongruent trials). As predicted, reductions of attention (i.e., increases of response time) were associated not only with decreased activity in sensory regions that processed the relevant visual stimuli, suggesting a failure to enhance the processing of those stimuli, but also with increased activity in sensory regions that processed the irrelevant auditory stimuli, suggesting a failure to suppress the processing of those stimuli. Reductions of attention were also linked to larger increases of activity in incongruent than in congruent trials in anterior cingulate regions that detect response conflict, suggesting that failing to suppress the sensory processing of the irrelevant auditory stimuli during attentional reductions allowed those stimuli to more readily activate conflicting responses in incongruent trials. These findings indicate that heightened levels of distraction during momentary reductions of attention likely stem, at least in part, from increased processing of irrelevant stimuli.

Respiratory inflammatory responses among occupants of a water-damaged office building.

UNLABELLED: The National Institute for Occupational Safety and Health (NIOSH) received a request for evaluation of a water-damaged office building which housed approximately 1300 employees. Workers reported respiratory conditions that they perceived to be building related. We hypothesized that these symptoms were associated with airways inflammation. To test this hypothesis, we assessed airways inflammation in employees using exhaled breath condensate (EBC) and the fraction of exhaled nitric oxide (FENO). In September 2001, a health questionnaire was offered to all employees. Based on this questionnaire, NIOSH invited 356 symptomatic and asymptomatic employees to participate in a medical survey. In June 2002, these employees were offered questionnaire, spirometry, methacholine challenge test, allergen skin prick testing, EBC and FENO. FENO or EBC were completed by 239 participants. As smoking is highly related to the measurements that we used in this study, we included only the 207 current non-smokers in the analyses. EBC interleukin-8 (IL-8) levels, but not nitrite, were significantly higher among workers with respiratory symptoms and in the physician-diagnosed asthmatic group. Of the analyses assessed, EBC IL-8 showed the most significant relationship with a number of symptoms and physician-diagnosed asthma. PRACTICAL IMPLICATIONS: Implementation of exhaled breath condensate and exhaled nitric oxide in indoor air quality problems.

Cognitive control in social situations: a role for the dorsolateral prefrontal cortex.

Using functional magnetic resonance imaging (fMRI), we investigated brain activity elicited by a computer-animated child's actions that appeared consistent and inconsistent with a computer-animated adult's instructions. Participants observed a computer-animated adult verbally instructing a computer-animated child to touch one of two objects. The child performed correctly in half of the trials and incorrectly in the other half. We observed significantly greater activity when the child performed incorrectly compared to correctly in regions of the dorsolateral prefrontal cortex (DLPFC) that have been implicated in maintaining our intentions in working memory and implementing cognitive control. However, no such effects were found in regions of the posterior superior temporal sulcus (posterior STS) that have been posited to interpret other people's behavior. These findings extend the role of the DLPFC in cognitive control to evaluating the social outcomes of other people's behavior and provide important new constraints for theories of how the posterior STS contributes to social cognition.

fMRI evidence for both generalized and specialized components of attentional control.

A central question in the study of selective attention is whether top-down attentional control mechanisms are generalized or specialized for the type of information that is to be attended. The current study examined this question using a voluntary orienting task that cued observers to attend to either one of two locations or to one of two colors. Location (spatial) and color (nonspatial) conditions were presented either randomly intermixed within the same block of trials or in separate blocks. Functional magnetic resonance imaging revealed that directing attention to a location or to a color activated a network of overlapping dorsal frontal and parietal areas, previously implicated in attentional control. The pattern of observed overlap was not affected by the intermixed versus blocked presentation of location and color conditions. Although portions of the frontal-parietal network were more active in response to location cues than to color cues, a secondary analysis also revealed that medial dorsal frontal and parietal cortex were specifically engaged in shifting visual attention regardless of the cued dimension (location or color). Together, the present results support the conclusion that attentional control is the combination of a generalized network that works in concert with subregions of the frontoparietal network that are highly specialized for directing attention based on the content of the to-be-attended information.

The neural circuitry underlying the executive control of auditory spatial attention.

Although a fronto-parietal network has consistently been implicated in the control of visual spatial attention, the network that guides spatial attention in the auditory domain is not yet clearly understood. To investigate this issue, we measured brain activity using functional magnetic resonance imaging while participants performed a cued auditory spatial attention task. We found that cued orienting of auditory spatial attention activated a medial-superior distributed fronto-parietal network. In addition, we found cue-triggered increases of activity in the auditory sensory cortex prior to the occurrence of an auditory target, suggesting that auditory attentional control operates in part by biasing processing in sensory cortex in favor of expected target stimuli. Finally, an exploratory cross-study comparison further indicated several common frontal and parietal regions as being involved in the control of both visual and auditory spatial attention. Thus, the present findings not only reveal the network of brain areas underlying endogenous spatial orienting in the auditory modality, but also suggest that the control of spatial attention in different sensory modalities is enabled in part by some common, supramodal neural mechanisms.

Engineering and public health at CDC.

Engineering is the application of scientific and technical knowledge to solve human problems. Using imagination, judgment, and reasoning to apply science, technology, mathematics, and practical experience, engineers develop the design, production, and operation of useful objects or processes. During the 1940s, engineers dominated the ranks of CDC scientists. In fact, the first CDC director, Assistant Surgeon General Mark Hollis, was an engineer. CDC engineers were involved in malaria control through the elimination of standing water. Eventually the CDC mission expanded to include prevention and control of dengue, typhus, and other communicable diseases. The development of chlorination, water filtration, and sewage treatment were crucial to preventing waterborne illness. Beginning in the 1950s, CDC engineers began their work to improve public health while developing the fields of environmental health, industrial hygiene, and control of air pollution. Engineering disciplines represented at CDC today include biomedical, civil, chemical, electrical, industrial, mechanical, mining, and safety engineering. Most CDC engineers are located in the National Institute for Occupational Safety and Health (NIOSH) and the Agency for Toxic Substances and Disease Registry (ATSDR). Engineering research at CDC has a broad stakeholder base. With the cooperation of industry, labor, trade associations, and other stakeholders and partners, current work includes studies of air contaminants, mining, safety, physical agents, ergonomics, and environmental hazards. Engineering solutions remain a cornerstone of the traditional "hierarchy of controls" approach to reducing public health hazards.

The neural bases of momentary lapses in attention.

Momentary lapses in attention frequently impair goal-directed behavior, sometimes with serious consequences. Nevertheless, we lack an integrated view of the brain mechanisms underlying such lapses. By investigating trial-by-trial relationships between brain activity and response time in humans, we determined that attentional lapses begin with reduced prestimulus activity in anterior cingulate and right prefrontal regions involved in controlling attention. Less efficient stimulus processing during attentional lapses was also characterized by less deactivation of a 'default-mode' network, reduced stimulus-evoked sensory activity, and increased activity in widespread regions of frontal and parietal cortex. Finally, consistent with a mechanism for recovering from attentional lapses, increased stimulus-evoked activity in the right inferior frontal gyrus and the right temporal-parietal junction predicted better performance on the next trial. Our findings provide a new, system-wide understanding of the patterns of brain activity that are associated with brief attentional lapses, which informs both theoretical and clinical models of goal-directed behavior.

Brain regions activated by endogenous preparatory set shifting as revealed by fMRI.

An ongoing controversy concerns whether executive control mechanisms can actively reconfigure the cognitive system in preparation for switching to a new task set. To address this question, we recorded brain activity from 14 healthy participants, using event-related functional magnetic resonance imaging, while they performed a cued attention task. Critically, in any particular trial, the cued task set was either the same as that in the previous trial or switched. As was hypothesized, cue-related, switch-specific preparatory activity was observed in a network of dorsal frontal and parietal brain areas that are typically associated with cognitive control processes. Moreover, the magnitude of switch-specific preparatory activity varied with the number of possible task sets that could be presented in a given trial block. These findings provide compelling support for the existence of top-down, preparatory control processes that enable set switching. Furthermore, they demonstrate that global task structure is a critical determinant of whether switch-specific preparatory activity is observed.

Tuberculosis mortality by industry in the United States, 1990-1999.

OBJECTIVE: To identify occupations and industries with elevated respiratory tuberculosis (TB) mortality in the United States for the period 1990-1999, we used National Center for Health Statistics multiple-cause-of-death data, restricted to certain states for which information on decedents' usual industry and occupational information was available and limited to US residents aged > or =15 years. DESIGN: A total of 7686 deaths between 1990 and 1999 were attributed to respiratory TB. Proportionate mortality ratios (PMRs), adjusted for age, sex, and race, were calculated from US census occupation and industry classifications. RESULTS: Industries and occupations involving potential contact with infected cases (e.g., health care workers), those with silica exposure and silicosis (e.g., mining and construction), and those associated with low socioeconomic status had significantly elevated TB mortality. CONCLUSIONS: Overall, the pattern of findings echoes that described in various prior reports, which indicates that the potential for exposure and disease development still persists among certain worker groups. The findings should be useful in guiding occupationally targeted TB prevention programs.

Hemispheric asymmetries for different components of global/local attention occur in distinct temporo-parietal loci.

Data from brain-damaged and neurologically intact populations indicate hemispheric asymmetries in the temporo-parietal cortex for discriminating an object's global form (e.g. the overall shape of a bicycle) versus its local parts (e.g. the spokes in a bicycle tire). However, it is not yet clear whether such asymmetries reflect processes that (i) bias attention toward upcoming global versus local stimuli and/or (ii) attend/identify global versus local stimuli after they are presented. To investigate these possibilities, we asked sixteen healthy participants to perform a cued global/local attention task while their brain activity was recorded using event-related functional magnetic resonance imaging (fMRI). The results indicated a novel double dissociation. Hemispheric asymmetries for deploying attention toward expected global versus local object features were specific to the intraparietal sulcus (iPs). However, hemispheric asymmetries for identifying global versus local features after they were presented were specific to the inferior parietal lobe/superior temporal gyrus (IPL/STG). This double dissociation provides the first direct evidence that hemispheric asymmetries associated with different components of global/local attention occur in distinct temporo-parietal loci. Furthermore, it parallels an analogous dissociation reported in a recent fMRI study of spatial orienting, suggesting that global/local attention and spatial attention might rely on similar cognitive/neural mechanisms.

Dorsal anterior cingulate cortex resolves conflict from distracting stimuli by boosting attention toward relevant events.

In everyday life, we often focus greater attention on behaviorally relevant stimuli to limit the processing of distracting events. For example, when distracting voices intrude upon a conversation at a noisy social gathering, we concentrate more attention on the speaker of interest to better comprehend his or her speech. In the present study, we investigated whether dorsal/caudal regions of the anterior cingulate cortex (dACC), thought to make a major contribution to cognitive control, boost attentional resources toward behaviorally relevant stimuli as a means for limiting the processing of distracting events. Sixteen healthy participants performed a cued global/local selective attention task while brain activity was recorded with event-related functional magnetic resonance imaging. Consistent with our hypotheses, greater dACC activity during distracting events predicted reduced behavioral measures of interference from those same events. dACC activity also differed for cues to attend to global versus local features of upcoming visual objects, further indicating a role in directing attention toward task-relevant stimuli. Our findings indicate a role for dACC in focusing attention on behaviorally relevant stimuli, especially when the achievement of our behavioral goals is threatened by distracting events.

The neural mechanisms for minimizing cross-modal distraction.

The neural circuitry that increases attention to goal-relevant stimuli when we are in danger of becoming distracted is a matter of active debate. To address several long-standing controversies, we asked participants to identify a letter presented either visually or auditorily while we varied the amount of cross-modal distraction from an irrelevant letter in the opposite modality. Functional magnetic resonance imaging revealed three novel results. First, activity in sensory cortices that processed the relevant letter increased as the irrelevant letter became more distracting, consistent with a selective increase of attention to the relevant letter. In line with this view, an across-subjects correlation indicated that the larger the increase of activity in sensory cortices that processed the relevant letter, the less behavioral interference there was from the irrelevant letter. Second, regions of the dorsolateral prefrontal cortex (DLPFC) involved in orienting attention to the relevant letter also participated in increasing attention to the relevant letter when conflicting stimuli were present. Third, we observed a novel pattern of regional specialization within the cognitive division of the anterior cingulate cortex (ACC) for focusing attention on the relevant letter (dorsal ACC) versus detecting conflict from the irrelevant letter (rostral ACC). These findings indicate novel roles for sensory cortices, the DLPFC, and the ACC in increasing attention to goal-relevant stimulus representations when distracting stimuli conflict with behavioral objectives. Furthermore, they potentially resolve a long-standing controversy regarding the key contribution of the ACC to cognitive control.

Fucosylated lactosamines participate in adhesion of HIV-1 envelope glycoprotein to dendritic cells.

Carbohydrates expressed on HIV-1 gp160 are purported to bind to several receptor types that affect virus pathophysiology. Here, we define a potential role for fucosylated glycans involved in the adhesion of cells expressing anchored HIV-1 glycoprotein or HIV virions to human dendritic cells (DCs). We observe that a monoclonal antibody (FH6), with reactivity toward an extended dimeric form of a fucosyl lactosamine, binds to gp120 transfectants, blocking adhesion of these cells and virus particles to human DCs. We observe that serum antibodies induced by peptide mimetic of fucosylated carbohydrate core structures emulate the monoclonal antibody reactivity pattern, showing enhanced reactivity to HIV-1 envelope-expressing cell line and blocking the adhesion of these cells to human DCs. These results suggest a potential role for initial adherence of virally infected cells or virions mediated by fucosylated lactosamines expressed on the envelope protein. As these carbohydrates function as adhesion molecules associated with homing and dissemination processes, such interactions may contribute to the HIV infection process.

Conflict monitoring in the human anterior cingulate cortex during selective attention to global and local object features.

Parallel processing affords the brain many advantages, but processing multiple bits of information simultaneously presents formidable challenges. For example, while one is listening to a speaker at a noisy social gathering, processing irrelevant conversations may lead to the activation of irrelevant perceptual, semantic, and response representations that conflict with those evoked by the speaker. In these situations, specialized brain systems may be recruited to detect and resolve conflict before it leads to incorrect perception and/or behavior. Consistent with this view, recent findings indicate that dorsal/caudal anterior cingulate cortex (dACC), on the medial walls of the frontal lobes, detects conflict between competing motor responses primed by relevant versus irrelevant stimuli. Here, we used a cued global/local selective attention task to investigate whether the dACC plays a general role in conflict detection that includes monitoring for conflicting perceptual or semantic representations. Using event-related functional magnetic resonance imaging (fMRI), we found that the dACC was activated by response conflict in both the global and the local task, consistent with results from prior studies. However, dACC was also activated by perceptual and semantic conflict arising from global distracters during the local task. The results from the local task have implications for recent theories of attentional control in which the dACC's contribution to conflict monitoring is limited to response stages of processing, as well as for our understanding of clinical disorders in which disruptions of attention are associated with dACC dysfunction.

A role for top-down attentional orienting during interference between global and local aspects of hierarchical stimuli.

Various models of selective attention propose that greater attention is allocated toward target stimuli when conflicting distracters make selection more difficult, but compelling evidence to support this view is scarce. In the present experiment, 15 participants performed a cued global/local selective attention task while brain activity was recorded with event-related functional magnetic resonance imaging. The presence of conflicting versus nonconflicting distracters during target processing activated regions of frontal, parietal, and visual cortices that were also activated when participants oriented attention in response to global- and local-task cues. These findings support models in which conflict between target and distracter stimuli is resolved by more selectively focusing attention upon target stimuli.

Effects of practice on executive control investigated with fMRI.

Various models of executive control predict that practice should modulate the recruitment of executive brain mechanisms. To investigate this issue, we asked 15 participants to perform a cued global/local attention task while brain activity was recorded with event-related functional magnetic resonance imaging (fMRI). Practice significantly reduced the recruitment of left inferior parietal regions that were engaged when participants oriented attention in response to global and local cue stimuli. In contrast, practice increased the recruitment of midline frontal regions that were engaged by interference between global and local forms during target processing. These findings support models of executive control in which practice increases the tendency for stimuli to automatically evoke task-relevant processes and responses.