Constricted Spaces Research Articles

Flow of Tunable Elastic Microcapsules through Constrictions

We design and fabricate elastically tunable monodisperse microcapsules using microfluidics and cross-linkable polydimethylsiloxane (PDMS). The overall stiffness of the microcapsules is governed by both the thickness and cross-link ratio of the polymer shell. Flowing suspensions of microcapsules through constricted spaces leads to transient blockage of fluid flow, thus altering the flow behavior. The ability to tune microcapsule mechanical properties enables the design of elastic microcapsules that can be tailored for desired flow behavior in a broad range of applications such as oil recovery, reactor feeding, red blood cell flow and chemical targeted delivery.

Nuclei migrate through constricted spaces using microtubule motors and actin networks in C. elegans hypodermal cells

Cellular migrations through constricted spaces are a crucial aspect of many developmental and disease processes including hematopoiesis, inflammation and metastasis. A limiting factor in these events is nuclear deformation. Here, we establish an in vivo model in which nuclei can be visualized while moving through constrictions and use it to elucidate mechanisms for nuclear migration. C. elegans hypodermal P-cell larval nuclei traverse a narrow space that is about 5% their width. This constriction is blocked by fibrous organelles, structures that pass through P cells to connect the muscles to cuticle. Fibrous organelles are removed just prior to nuclear migration, when nuclei and lamins undergo extreme morphological changes to squeeze through the space. Both actin and microtubule networks are organized to mediate nuclear migration. The LINC complex, consisting of the SUN protein UNC-84 and the KASH protein UNC-83, recruits dynein and kinesin-1 to the nuclear surface. Both motors function in P-cell nuclear migration, but dynein, functioning through UNC-83, plays a more central role as nuclei migrate towards minus ends of polarized microtubule networks. Thus, the nucleoskeleton and cytoskeleton are coordinated to move nuclei through constricted spaces.

Nuclear migration events throughout development.

Moving the nucleus to a specific position within the cell is an important event during many cell and developmental processes. Several different molecular mechanisms exist to position nuclei in various cell types. In this Commentary, we review the recent progress made in elucidating mechanisms of nuclear migration in a variety of important developmental models. Genetic approaches to identify mutations that disrupt nuclear migration in yeast, filamentous fungi, Caenorhabditis elegans, Drosophila melanogaster and plants led to the identification of microtubule motors, as well as Sad1p, UNC-84 (SUN) domain and Klarsicht, ANC-1, Syne homology (KASH) domain proteins (LINC complex) that function to connect nuclei to the cytoskeleton. We focus on how these proteins and various mechanisms move nuclei during vertebrate development, including processes related to wound healing of fibroblasts, fertilization, developing myotubes and the developing central nervous system. We also describe how nuclear migration is involved in cells that migrate through constricted spaces. On the basis of these findings, it is becoming increasingly clear that defects in nuclear positioning are associated with human diseases, syndromes and disorders.

Nuclei migrate through constricted spaces using microtubule motors and actin networks in C. elegans hypodermal cells.

Cellular migrations through constricted spaces are a crucial aspect of many developmental and disease processes including hematopoiesis, inflammation and metastasis. A limiting factor in these events is nuclear deformation. Here, we establish an in vivo model in which nuclei can be visualized while moving through constrictions and use it to elucidate mechanisms for nuclear migration. C. elegans hypodermal P-cell larval nuclei traverse a narrow space that is about 5% their width. This constriction is blocked by fibrous organelles, structures that pass through P cells to connect the muscles to cuticle. Fibrous organelles are removed just prior to nuclear migration, when nuclei and lamins undergo extreme morphological changes to squeeze through the space. Both actin and microtubule networks are organized to mediate nuclear migration. The LINC complex, consisting of the SUN protein UNC-84 and the KASH protein UNC-83, recruits dynein and kinesin-1 to the nuclear surface. Both motors function in P-cell nuclear migration, but dynein, functioning through UNC-83, plays a more central role as nuclei migrate towards minus ends of polarized microtubule networks. Thus, the nucleoskeleton and cytoskeleton are coordinated to move nuclei through constricted spaces.

Negotiating Gendered Religious Space

Much research on women’s religious participation centers on their abilities to act within constricted institutional spaces. Drawing on five years of ethnographic fieldwork, this study analyzes how African American Muslim women use the mosque as a physical space to enact public performances of religious identity. By occupying, protecting, and appropriating spaces in the mosque for meaningfully gender-specific ways of engaging Islam, the women further a project of religious self-making that bonds African American Muslim women together. In their maneuverings of different forms of physical space as a sisterhood, the women enable themselves to resist gender, economic, and racial oppression. This study reveals that even within men-dominated religious organizations with limited symbolic and material spaces for women, women participants successfully exert agency over their own religious experiences.

The Agitated Shell: Thinspiration and the Gothic Experience of Eating Disorders

The Agitated Shell: Thinspiration and the Gothic Experience of Eating Disorders

Downregulation of NF-κB and PCNA in the regulatory pathways of apoptosis by cyclooxygenase-2 inhibitors in experimental lung cancer

Non-steroidal anti-inflammatory drugs (NSAIDs) are emerging as novel chemopreventive agents against a variety of cancers owing to their capability in blocking the tumor development by cellular proliferation, angiogenesis and by promoting apoptosis. The present study further explored the comparative role of a traditional NSAID, indomethacin and a newly developed coxib, etoricoxib against 9,10-dimethylbenz(a)anthracene (DMBA)-induced lung carcinogenesis in rats. Morphological and histological analysis revealed the occurrence of tumors and lesions along with constricted alveolar spaces in the DMBA treated animals which were largely corrected both by indomethacin and etoricoxib. COX-1 was found to be uniformly expressed in all the groups while COX-2 levels were raised prominently in the DMBA treated animals. Proliferation, as studied by PCNA expression was found to be markedly increased in the DMBA group as compared to the others. Increased NF-κB expression in the DMBA group was found to correct with the co-administration of NSAIDs. Also, fluorescent co-staining of the isolated lung cells revealed a significantly decreased apoptosis and altered mitochondrial membrane potential. In conclusion, these parameters indicate to the chemopreventive action of the two NSAIDs studied in lung cancer and as their mechanism of action suggests, can be achievable both by COX-dependent and COX-independent pathways.

Upregulation of intrinsic apoptotic pathway in NSAIDs mediated chemoprevention of experimental lung carcinogenesis

BackgroundNon-steroidal anti-inflammatory drugs (NSAIDs) act by inhibition of cyclooxygenase-2 (COX-2), which is overexpressed in cancer. The role of COX-2 and apoptosis were evaluated in 9,10-dimethylbenz(a)anthracene (DMBA)-induced lung cancer in rat and chemoprevention with indomethacin, a traditional NSAID and etoricoxib, a selective COX-2 inhibitor. MethodsThe animals were divided into Control, DMBA, DMBA + indomethacin and DMBA + etoricoxib groups. They received a single intratracheal instillation of DMBA while NSAIDs were given orally daily for 32 weeks. Besides morphology and histology of lungs, RT-PCR, western blots and immunohistochemistry were performed for the expression of apoptotic proteins and COX enzymes. Apoptosis was studied by DNA fragmentation and fluorescent staining. ResultsThe occurrence of tumors and lesions was noted in the DMBA animals, besides constricted alveolar spaces and hyperplasia. COX-1 was found to be uniformly expressed while COX-2 level was raised significantly in DMBA group. The apoptotic proteins, apaf-1, caspase-9 and caspase-3 were highly diminished in DMBA group but restored to normal level in NSAIDs groups. Also, apoptosis was suppressed in carcinogen group by DNA fragmentation analysis and fluorescent staining of the lung cells while coadministration of NSAIDs along with DMBA led to the restoration of apoptosis. ConclusionDMBA administration to the rats led to tumorigenesis in the lungs, had no effects on COX-1 expression, while elevating the COX-2 levels and suppressing apoptosis. The treatment with NSAIDs led to the amelioration of these effects. However, etoricoxib which is a COX-2 specific inhibitor, was found to be more effective than the traditional NSAID, indomethacin.

Analysis and Democracy: The Antecedents of the Deliberative Approach of Ecosystems Valuation

As a political institution, open deliberation on public policy can enhance legitimacy and procedural justice. As a science, decision-aiding deliberative procedures can help overcome bounded rationality of individuals. Integrating the two modes of inquiry would be perfect for capturing the plural values of the environment. However, the analytic requirements seem to point in a different direction from the political ideals. Legitimacy problems arise when the supposedly unconstrained process is professionally ‘guided’. But rigorous decision aids fail to work without some degree of cognitive guidance. A trend in ecosystems valuation research is the use of analytic techniques in the deliberative processes of value articulation. In this paper an analytic – deliberative approach is assessed against a deliberative democracy theory. This approach seeks to facilitate deliberation within individuals and to engineer preference towards instrumental rationality. The evaluative framework allows predetermination of the range of outcomes. Little room has been made for value debates, thus the moral need for actual discussion is weak. Being expert centred, the framework provides constricted spaces for empowerment. Alternative expressions unintelligible to the science may be put at a disadvantage. The scope for a reflexive democratic institution appears limited. A promising deliberative valuation approach should be integrative, including analytic and political elements as complementary to each other, and should be democratic in its production.

Types of Human Gathering in Small-scale Elderly Care Facility

Individualized care in small-scale nursing homes is becoming more prevalent in Japan in order to meet the personal needs and respect the dignity of the elderly. Since the philosophy of care and the subsequent activities of nursing home staff are changing drastically with the increase in individualized care, creating a comfortable care environment and providing a well-designed space must be taken into consideration. This paper attempts to clarify the actual conditions of a care environment in which individualized care is provided by analyzing the activities of both the residents and care staff. Data were collected from behavioral observations and examination of patterns in the use of space at an elderly care facility that has both Group Living and a Day Service.The results of this paper are as follows:1) Several types of support, such as Direct care, Conversation care, Organizing groups and Beholding occur at the same time with a varying number of participants, and change depending on the situation.2) While Direct care and Beholding are the main types of support for Group Living residents, for those using the Day Service, Conversation care is the main type.3) The care environment should comprise connected spaces, such as a kitchen and dining room, rather than individual or constricted spaces.

Landscape and Social Relations at Charleston Townhouse Sites (1770–1850)

Restoration projects at Charleston townhouse properties, both public and private, have provided opportunities for archaeological exploration on a variety of scales. In the eighteenth and nineteenth centuries, these properties were the homes of wealthy planters and merchants and enslaved African Americans, who lived and worked in the service buildings and work yard. The inter-dependence of these diverse occupants, their daily affairs, and the landscape elements under their purview has been revealed in the research of scholars from a host of disciplines, including archaeology. Townhouse compounds included support structures and activity areas required to meet the range of daily life affairs, from the necessary to the luxurious. While the front of the house, and the formal garden, presented a well-ordered facade, the work yard housed the facilities for the necessities of daily life, in an often dirty, noisy, and unordered space. The deliberate separation of space and placement of specialized service buildings and their occupants created an urban landscape suitable to the social values, as well as physical needs, of the townhouse owners. Thus, owner and slave lived in a compound that was physically close, but socially distinct. Archaeological case studies are used here to explore the racial power dynamics embodied in the urban townhouse landscape. The archaeological mixing of material from master and slave is, however, a material reflection of the racial power dynamics played out in constricted urban spaces.

Can You Hear Me Now? Found: 2 ‘Lost’ Hearing Aids in Otic Canal of Elderly Woman with Mild Dementia

Introduction/Objective: Innovation renders hearing aids inconspicuous so they are able to fit small auricular spaces, and have better cosmetic appeal. Long-term care providers strive to augment and correct sensory deficits. Apart from enhancing quality of life, intact hearing helps mitigate risk of delirium and depression. Hearing aids – unlike eyeglasses, are designed to be camouflaged by adaptation to skin color and miniaturization. When fractured, hearing aid parts may get concealed in constricted spaces like the ear canal. Furthermore, earwax can cover and cement broken parts, with potential for complications like otitis or perforation.

Colloid straining within water‐saturated porous media: Effects of colloid size nonuniformity

Groundwater suspensions consist of colloidal particles of nonuniform size, yet most published studies of colloid straining in porous media have been conducted with monodisperse colloidal suspensions. In this technical note, we report the results of column experiments on the straining of monodisperse suspensions (3.1 or 5.1 μm microspheres) and a bidisperse suspension (containing 3.1 and 5.1 μm microspheres) within water‐saturated quartz sand. The experiments are similar to those described by Xu et al. (2006) in which chemical conditions were prescribed to minimize physicochemical deposition and straining represented the dominant mechanism of colloid immobilization. We find that the straining rates of the monodisperse suspensions can be quantified with published, empirically based expressions that use the ratio of colloid diameter to sand grain diameter as the predictor variable. The straining kinetics of the bidisperse suspension cannot be quantified with these empirical expressions when the mass‐averaged microsphere size is used for the colloid diameter. Analysis of the data from the experiments with the bidisperse suspension suggests that retention of the 5.1 μm microspheres constricted pore spaces with dimensions between 3.1 and 5.1 μm, which enhanced the straining of the 3.1 μm microspheres. A model that accounts for this effect and that uses one fitting parameter in coordination with parameters estimated from column experiments with the monodisperse suspensions describes the observations made in the bidisperse experiment with good success.

Leukocyte polarization in cell migration and immune interactions.

Cell migration plays a key role in a wide variety of biological phenomena. This process is particularly important for leukocyte function and the inflammatory response. Prior to migration leukocytes undergo polarization, with the formation of a lamellipodium at the leading edge and a uropod at the trailing edge. This cell shape allows them to convert cytoskeletal forces into net cell-body displacement. Leukocyte chemoattractants, including chemokines, provide directional cues for leukocyte motility, and concomitantly induce polarization. Chemoattractant receptors, integrins and other adhesion molecules, cytoskeletal proteins and intracellular regulatory molecules change their cellular localization during cell polarization. A complex system of signal transduction molecules, including tyrosine kinases, lipid kinases, second messengers and members of the Rho family of small GTPases is thought to regulate the cytoskeletal rearrangements underlying leukocyte polarization and migration. The elucidation of the mechanisms and signals that control this complex reorganization will lead to a better understanding of critical questions in cell biology of leukocyte migration and polarity.

Microtubule retraction into the uropod and its role in T cell polarization and motility.

Spherical circulating T cells must polarize to extravasate. We have found that the polarization process includes a drastic reconfiguration of the tubulin cytoskeleton. In spherical T cells, the nucleus is surrounded by microtubules radiating from the microtubule organizing center (MTOC). During polarization the uropod (a slender posterior appendage) forms at the site of the MTOC. As the uropod buds out, the MTOC is carried in its distal tip. The attached microtubules retract into the uropod lumen, collapsing like the spokes of an umbrella into a compact sheaf. Experiments with microtubule inhibitors show that the retracted microtubules do not support the uropod or produce motive force. Instead, the data suggest that retraction of the relatively rigid microtubules into the streamlined uropod increases T cell deformability, thereby facilitating migration through constricted spaces. Microtubule retraction, therefore, may prove to be a strategy for accelerating extravasation without disassembly of the microtubule-based transport system.

Weathering rates as a function of flow through an alpine soil

The effect of flow on release rates of solutes from soil in a 39-m 2 alpine catchment in the Colorado Rockies was measured during the summers of 1990–1994. Flow rates through the soil were varied by augmenting natural rainfall with deionized irrigation water. Daily water inputs averaged between 96 and 2161 day − during the five field seasons, and mean discharge (inputs minus evapotranspiration) varied from 35 to 175 1 day −1. Volume-weighted mean concentrations of base cations and silica decreased only moderately in response to the increased water inputs. Input fluxes of solutes in precipitation were similar in each of the study seasons, but output fluxes of base cations and silica in surface outflow increased substantially in conjunction with the average water input rate for the season. Weathering rates calculated from the chemical fluxes increased substantially in response to increases in water input rates. The increases appear to be largely attributable to enhanced transport of solutes from the soil matrix under high flow conditions. At high flow, physical flushing of micropores presumably occurs to a greater extent than during low-flow periods because of greater soil wetness and higher hydrologic head. Increased flushing would also cause an increased rate of diffusion of solutes from microcracks in mineral surfaces and constricted pore spaces in response to an increased concentration gradient between those regions and adjacent areas in the soil matrix. Another consequence of the increased flushing that occurs during periods of high flow is that concentrations throughout the soil matrix tend to be lower, which might increase chemical weathering rates of some silicate minerals such as microcline, which are relatively close to saturation. Decreased Si concentrations under high-flow conditions appear to promote dissolution of amorphous aluminosilicates or desorption of Si from mineral surfaces, buffering Si concentrations in the soil solutions. Thus, both physical transport of solutes and subsequent chemical effects appear to be responsible for the positive relation observed between fluxes of weathering products and water input rates.

Acute response to sodium hypochlorite in rainbow trout acclimatized to pulp and paper mill effluents

Rainbow trout ( Salmo gairdneri) fingerlings were exposed to sodium hypochlorite (NaClO) in semistatic LC 50 tests for 48 h in dechlorinated Helsinki tap water and water from Lake Vatia (21 km downstream from a kraft pulp mill). Fish were also exposed for 17 days to Lake Vatia water after which an acute exposure to sodium hypochlorite was made, for which physiological samples were analyzed. The 48 h LC 50 of bleached kraft pulp mill effluent was 35%. The 17 days' caging period in the recipient water 21 km downstream from the mill caused disturbances in osmotic regulation, depletion of liver glycogen and inhibition of liver UDP-glucuronosyltransferase. The gills of the exposed fish were microscopically examined. The epithelium of the secondary lamellae in the NaClO exposed gills was thicker than in the controls (48 h LC 50 0.35 mg Cl 2/l) and the lamellae were curled with constricted blood spaces. The gill epithelium of fish exposed to NaClO in water from Lake Vatia was swollen and vacuolized (48 h LC 50 0.09 mg Cl 2/l). The gills of fish exposed to 20% pulp mill effluent as well as the gills of fish acclimatized for 17 days in Lake Vatia water were quite normal in structure. However, after hypochlorite exposure the gills of the pre-acclimatized fish were almost totally destroyed (48 h LC 50 0.07 mg Cl 2/l).

Ultrastructural observations on the cytoarchitecture of axons processed by rapid-freezing and freeze-substitution

The structure and organization of axons in the cervical connective of wild-type Drosophila fruit flies were examined in anticipation of studies of various neurological mutants. Dissected flies were rapid-frozen from the living state against a copper block cooled with liquid helium, freeze-substituted, and prepared for electron microscopic examination of thin sections. These cryotechniques showed new details of the structure of cell organelles and cytoplasm in Drosophila axons. The cytoplasmic matrix of axons and glia consists of a material with a fine granular texture enmeshed in a three-dimensional meshwork of short, fine filaments which vary in shape, size and electron density. No neurofilaments are present, but bundles of microtubules are interwoven into the filamentous matrix of the axoplasm. The round wall of microtubules (27 nm overall diameter) is composed of twelve cylindrical protofilaments with a typical substructural periodicity. Mitochondria frequently make contact with microtubules in both axons and glial processes. A thin layer of electron-dense filamentous matrix, which appears to be an axonal basal lamina, contacts most of the axonal exoplasmic surface, especially that of axons where they are surrounded by processes of glial cells, but is scant wherever single axons are contiguous. Thus, an axonal basal lamina occupies the constricted spaces around axons, where extracellular K+ accumulates during neural activity.