Isolation and Characterization of Equine Uterine Extracellular Vesicles: A Comparative Methodological Study

Extracellular vesicles (EVs) have been identified in the uterine fluid in different species and have been pointed as key players in the embryo-maternal dialogue, maternal recognition of pregnancy and establishment of pregnancy. However, little is known about the uterine EVs in the mare. Therefore, the present study aimed at characterizing EVs from uterine lavage of cyclic mares by comparing five EVs isolation methods and the combination of them: (1) ultracentrifugation (UC); (2) concentration of lavage volume by Centricon ultrafiltration (CE); (3) the use of CE with different washing steps (phosphate-buffered saline with or without trehalose); (4) size-exclusion chromatography with iZON-qEV columns, and (5) a combination of the methods with best results based on EVs yield, purity, and protein cargo profiles. Transmission electron microscopy and Western blotting confirmed the isolation of EVs by all methods but with quantitative and qualitative differences. Mass spectrometry provided differences in protein profiles between methods, number of identified proteins, and protein classes. Our results indicate that the combination of CE/trehalose/iZON/UC is an optimal method to isolate equine uterine EVs with good yield and purity that can be applied in future studies to determine the role of equine uterine EVs in embryo-maternal interactions.

Site-specific opening of the blood-brain barrier by extracellular histones

BACKGROUND

Increased extracellular histones in the bloodstream are known as a biomarker for vascular dysfunction associated with severe trauma or sepsis. There is limited information regarding the pathogenic role of circulating histones in neuroinflammation and cerebrovascular endothelial injury. Particularly, it remains unclear whether histones affect the blood-brain barrier (BBB) permeability function.

METHODS

The direct effects of unfractionated histones on endothelial barrier properties were first assessed in brain microvascular endothelial cell monolayers by measuring transendothelial electrical resistance and solute flux. This was followed by in vivo mouse experiments, where BBB function was assessed by quantifying brain tissue accumulation of intravenously injected tracers of different molecular sizes, and comparison was made in mice receiving a sublethal dose of histones versus sterile saline. In parallel, the endothelial barrier ultrastructure was examined in histone- and saline-injected animals under transmission electron microscopy, corresponding to the expression of tight junction and adherens junction proteins.

RESULTS

Histones increased paracellular permeability to sodium fluorescein and reduced barrier resistance at 100 μg/mL; these responses were accompanied by discontinuous staining of the tight junction proteins claudin-5 and zona ocludens-1. Interestingly, the effects of histones did not seem to result from cytotoxicity, as evidenced by negative propidium iodide staining. In vivo, histones increased the paracellular permeability of the BBB to small tracers of < 1-kDa, whereas tracers larger than 3-kDa remained impermeable across brain microvessels. Further analysis of different brain regions showed that histone-induced tracer leakage and loss of tight junction protein expression mainly occurred in the hippocampus, but not in the cerebral cortex. Consistently, opening of tight junctions was found in hippocampal capillaries from histone-injected animals. Protein expression levels of GFAP and iBA1 remained unchanged in histone-injected mice indicating that histones did not affect reactive gliosis. Moreover, cell membrane surface charge alterations are involved in histone-induced barrier dysfunction and tight junction disruption.

CONCLUSIONS

Extracellular histones cause a reversible, region-specific increase in BBB permeability to small molecules by disrupting tight junctions in the hippocampus. We suggest that circulating histones may contribute to cerebrovascular injury or brain dysfunction by altering BBB structure and function.

Mechanisms of sampling interstitial fluid from skin using a microneedle patch

Although interstitial fluid (ISF) contains biomarkers of physiological significance and medical interest, sampling of ISF for clinical applications has made limited impact due to a lack of simple, clinically useful techniques that collect more than nanoliter volumes of ISF. This study describes experimental and theoretical analysis of ISF transport from skin using microneedle (MN) patches and demonstrates collection of >1 µL of ISF within 20 min in pig cadaver skin and living human subjects using an optimized system. MN patches containing arrays of submillimeter solid, porous, or hollow needles were used to penetrate superficial skin layers and access ISF through micropores (µpores) formed upon insertion. Experimental studies in pig skin found that ISF collection depended on transport mechanism according to the rank order diffusion < capillary action < osmosis < pressure-driven convection, under the conditions studied. These findings were in agreement with independent theoretical modeling that considered transport within skin, across the interface between skin and µpores, and within µpores to the skin surface. This analysis indicated that the rate-limiting step for ISF sampling is transport through the dermis. Based on these studies and other considerations like safety and convenience for future clinical use, we designed an MN patch prototype to sample ISF using suction as the driving force. Using this approach, we collected ISF from human volunteers and identified the presence of biomarkers in the collected ISF. In this way, sampling ISF from skin using an MN patch could enable collection of ISF for use in research and medicine.

Cortical Spreading Depression Closes Paravascular Space and Impairs Glymphatic Flow: Implications for Migraine Headache

Functioning of the glymphatic system, a network of paravascular tunnels through which cortical interstitial solutes are cleared from the brain, has recently been linked to sleep and traumatic brain injury, both of which can affect the progression of migraine. This led us to investigate the connection between migraine and the glymphatic system. Taking advantage of a novel in vivo method we developed using two-photon microscopy to visualize the paravascular space (PVS) in naive uninjected mice, we show that a single wave of cortical spreading depression (CSD), an animal model of migraine aura, induces a rapid and nearly complete closure of the PVS around surface as well as penetrating cortical arteries and veins lasting several minutes, and gradually recovering over 30 min. A temporal mismatch between the constriction or dilation of the blood vessel lumen and the closure of the PVS suggests that this closure is not likely to result from changes in vessel diameter. We also show that CSD impairs glymphatic flow, as indicated by the reduced rate at which intraparenchymally injected dye was cleared from the cortex to the PVS. This is the first observation of a PVS closure in connection with an abnormal cortical event that underlies a neurological disorder. More specifically, the findings demonstrate a link between the glymphatic system and migraine, and suggest a novel mechanism for regulation of glymphatic flow.SIGNIFICANCE STATEMENT Impairment of brain solute clearance through the recently described glymphatic system has been linked with traumatic brain injury, prolonged wakefulness, and aging. This paper shows that cortical spreading depression, the neural correlate of migraine aura, closes the paravascular space and impairs glymphatic flow. This closure holds the potential to define a novel mechanism for regulation of glymphatic flow. It also implicates the glymphatic system in the altered cortical and endothelial functioning of the migraine brain.

Focal Solute Trapping and Global Glymphatic Pathway Impairment in a Murine Model of Multiple Microinfarcts

Microinfarcts occur commonly in the aging brain as a consequence of diffuse embolic events and are associated with the development of vascular dementia and Alzheimer's disease. However, the manner in which disperse microscopic lesions reduce global cognitive function and increase the risk for Alzheimer's disease is unclear. The glymphatic system, which is a brain-wide perivascular network that supports the recirculation of CSF through the brain parenchyma, facilitates the clearance of interstitial solutes including amyloid β and tau. We investigated whether glymphatic pathway function is impaired in a murine model of multiple microinfarcts induced by intraarterial injection of cholesterol crystals. The analysis showed that multiple microinfarcts markedly impaired global influx of CSF along the glymphatic pathway. Although suppression of global glymphatic function was transient, resolving within 2 weeks of injury, CSF tracers also accumulated within tissue associated with microinfarcts. The effect of diffuse microinfarcts on global glymphatic pathway function was exacerbated in the mice aged 12 months compared with the 2- to 3-month-old mice. These findings indicate that glymphatic function is focally disrupted around microinfarcts and that the aging brain is more vulnerable to this disruption than the young brain. These observations suggest that microlesions may trap proteins and other interstitial solutes within the brain parenchyma, increasing the risk of amyloid plaque formation.SIGNIFICANCE STATEMENT Microinfarcts, small (<1 mm) ischemic lesions, are strongly associated with age-related dementia. However, how these microscopic lesions affect global cognitive function and predispose to Alzheimer's disease is unclear. The glymphatic system is a brain-wide network of channels surrounding brain blood vessels that allows CSF to exchange with interstitial fluid, clearing away cellular wastes such as amyloid β. We observed that, in mice, microinfarcts impaired global glymphatic function and solutes from the CSF became trapped in tissue associated with microinfarcts. These data suggest that small, disperse ischemic lesions can impair glymphatic function across the brain and trapping of solutes in these lesions may promote protein aggregation and neuroinflammation and eventually lead to neurodegeneration, especially in the aging brain.

Extracellular heat shock protein 70 has novel functional effects on sea urchin eggs and coelomocytes

Numerous reports document that the 70 kDa heat shock proteins are not only intracellular proteins but are also present in blood and other extracellular compartments. How they affect cell function from the extracellular space remains unclear. Using two well-characterized cell types from the sea urchin, we show that extracellular mixtures of the constitutive and inducible forms of the 70 kDa heat shock proteins (Hsc70 and Hsp70, respectively) have dramatic effects on initiation of cell division in fertilized eggs and on the clotting reaction of hypotonically stressed coelomocytes. In suspensions of fertilized eggs to which Hsc70 or a 2:3 mixture of Hsc and Hsp70 was added, progression to the first mitotic division was accelerated. Evidence is provided that the extracellular Hsc70 passes into the egg cells in an unconventional manner, being distributed through the cytoplasm, and that it may alter the intracellular signaling cascade initiated by sperm penetration. In coelomocytes that were stimulated by hypotonic shock to mimic injury, the spreading reaction of the clotting response was significantly inhibited when either Hsp70 or Hsc70 was in the medium. These results suggest that the presence of Hsc and/or Hsp70 in the extracellular fluid may promote mitosis of dividing cells and suppress the reactivity of immune system cells.

Foreseeable pharmaceutical repair of age-related extracellular damage

Various molecular and cellular alterations to our tissues accumulate throughout life as intrinsic side-effects of metabolism. These alterations are initially harmless, but some, which we may term "damage", are pathogenic when sufficiently abundant. The slowness of their accumulation explains why decline of tissue and organismal function generally does not appear until the age of 40 or older. Aging is thus best viewed as a two-part process in which metabolism causes accumulating damage and sufficiently abundant damage causes pathology. Hence, a promising approach to avoiding age-related pathology is periodically to repair the various types of damage and so maintain them at a sub-pathogenic level. Some examples of such types of damage are intracellular and others extracellular. Several types of intracellular damage are highly challenging--sophisticated cellular and genetic therapies will be needed to combat them, which are surely at least 20 years away and maybe much more. Extracellular damage, by contrast, generally appears more amenable to pharmaceutical repair which may be feasible in a shorter timeframe. In this article, the major types of age-related extracellular damage and promising avenues for their repair are reviewed.

Roles of interstitial cells of Cajal in intestinal transit and exogenous electrical pacing

The aims of this study were to investigate the role of interstitial cells of Cajal (ICCs) on small intestinal transit and its responses to exogenous pacing in W/W(v) mice. Eleven W/W(v) mice and their controls implanted with four pairs of gastrointestinal electrodes were used for testing the entrainment of slow waves. Another 20 W/W(v) mice and their controls equipped with a duodenal catheter and one pair of intestinal electrodes were used to test small intestinal transit represented by the geometric center (GC). Results were as follows. (1) The effect of pacing on slow wave frequency was sustained only in controls, and not in W/W(v) mice. (2) Both gastric and intestinal slow waves were completely entrained in controls and W/W(v) mice. Higher energy was required for pacing the stomach than the small intestine. (3) There was no significant difference in small intestinal transit between the controls and the W/W(v) mice (GC: 5.4 vs. 5.5). (4) Pacing showed no effects on small intestinal transit in either wild-type (GC: 5.4 vs. 5.6) or W/W(v) mice (GC: 5.5 vs. 5.7). We conclude that myenteric ICCs may not play an important role in the regulation of small intestinal transit in conscious mice. Gastric and intestinal pacing can be achieved without ICCs.

Clinical experience in cell-based therapeutics: intervention and outcome

Disc herniation treated by discectomy results in a significant loss of nucleus material and disc height. Biological restoration through the use of autologous disc chondrocyte transplantation (ADCT) offers a potential to achieve functional integration of disc metabolism and mechanics. Nucleus regeneration using autologous cultured disc-derived chondrocytes has been demonstrated in a canine model and in clinical pilot studies. In 2002 a prospective, controlled, randomized, multicentre study comparing safety and efficacy of ADCT plus discectomy, with discectomy alone was initiated. The clinical goals were to provide long-term pain relief, maintain disc height, and prevent adjacent segment disease. Interim analysis was performed after 2 years; Oswestry (Low Back Pain/disability), Quebec Back Pain Disability Scale, as well as Prolo and VAS Score were used for the evaluation. Disc height was assessed by MRI. A clinically significant reduction of low back pain in the ADCT-treated group was shown by all three pain score systems. The median total Oswestry Score was 2 in the ADCT group compared with 6 in the control group. Decreases in the Disability index in ADCT-treated patients correlated with the reduction of low back pain. Decreases in disc height over time were only found in the control group, and of potential significance, intervertebral discs in adjacent segments appeared to retain hydration when compared to those adjacent to levels that had undergone discectomy without cell intervention.

M5 mesoscopic and macroscopic models for mesenchymal motion

In this paper mesoscopic (individual based) and macroscopic (population based) models for mesenchymal motion of cells in fibre networks are developed. Mesenchymal motion is a form of cellular movement that occurs in three-dimensions through tissues formed from fibre networks, for example the invasion of tumor metastases through collagen networks. The movement of cells is guided by the directionality of the network and in addition, the network is degraded by proteases. The main results of this paper are derivations of mesoscopic and macroscopic models for mesenchymal motion in a timely varying network tissue. The mesoscopic model is based on a transport equation for correlated random walk and the macroscopic model has the form of a drift-diffusion equation where the mean drift velocity is given by the mean orientation of the tissue and the diffusion tensor is given by the variance-covariance matrix of the tissue orientations. The transport equation as well as the drift-diffusion limit are coupled to a differential equation that describes the tissue changes explicitly, where we distinguish the cases of directed and undirected tissues. As a result the drift velocity and the diffusion tensor are timely varying. We discuss relations to existing models and possible applications.

Information content of point radiance measurements in turbid media: implications for interstitial optical property quantification

Motivated by a recent report by Dickey et al. [Phys. Med. Biol. 46, 2359 (2001)], who demonstrated optical property retrieval by using relative radiance measurements at a single position, we investigate the uniqueness of relative radiance measurements for quantifying the optical properties of turbid media by studying the solutions of the diffusion and P3 approximations of the Boltzmann transfer equation for a point source. Using the P3 approximation, we investigate the potential of radiance measurements for optical property recovery by examining the optical property response surface for point radiance information. We further derive first-order similarity relations for relative point radiance measurements and use these expressions to examine analytically the effects of noise on optical property retrieval over a wide range of optical properties typical of biological tissue. Finally, optimal experimental configurations are studied and explicit conditions for uniqueness derived that suggest potential strategies for improving optical property recovery. It is expected that point radiance measurements will prove valuable for both on-line treatment planning of minimally invasive laser therapies and optical characterization of tissues.

Extracellular heat shock protein 70: a critical component for motoneuron survival

The dependence of developing spinal motoneuron survival on a soluble factor(s) from their target, muscle tissue is well established both in vivo and in vitro. Considering this apparent dependence, we examined whether a specific component of the stress response mediates motoneuron survival in trophic factor-deprived environments. We demonstrate that, although endogenous expression of heat shock protein 70 (HSP70) did not change during trophic factor deprivation, application of e-rhHsp70 (exogenous recombinant human Hsp70) promoted motoneuron survival. Conversely, depletion of HSP70 from chick muscle extract (MEx) potently reduces the survival-promoting activity of MEx. Additionally, exogenous treatment with or spinal cord overexpression of Hsp70 enhances motoneuron survival in vivo during the period of naturally occurring cell death [programmed cell death (PCD)]. Hindlimb muscle cells and lumbar spinal astrocytes readily secrete HSP70 in vitro, suggesting potential physiological sources of extracellular Hsp70 for motoneurons. However, in contrast to exogenous treatment with or overexpression of Hsp70 in vivo, muscle-targeted injections of this factor in an ex vivo preparation fail to attenuate motoneuron PCD. These data (1) suggest that motoneuron survival requirements may extend beyond classical trophic factors to include HSP70, (2) indicate that the source of this factor is instrumental in determining its trophic function, and (3) may therefore influence therapeutic strategies designed to increase motoneuron Hsp70 signaling during disease or injury.

Expression of matrix metalloproteinase-9 in pleural effusions of tuberculosis and lung cancer

BACKGROUND

Matrix metalloproteinase (MMP)-9 has been implicated in the development of pleural effusions.

OBJECTIVES

The aim of this study was to assess the expression of MMP-9 in pleural effusions of tuberculosis, lung cancer and transudates.

METHODS

Ninety-one patients (37 tuberculous pleural effusions, 42 malignant pleural effusions of lung cancer and 12 transudates) were included. Concentrations of pleural fluid MMP-9 and tissue inhibitors of matrix metalloproteinase (TIMP)-1 were determined by immunoassay. We also investigated the cellular localization of MMP-9 and TIMP-1 by reverse-transcriptase polymerase chain reaction on lymphocytes from pleural effusions and by immunohistochemical analysis of pleural tissues.

RESULTS

Pleural fluid MMP-9 levels, MMP-9/total protein and MMP-9/TIMP-1 ratios were significantly higher in tuberculous pleural effusions, whilst TIMP-1 levels were similar in the three groups. MMP-9 levels positively correlated with TIMP-1 and lactate dehydrogenase levels, and negatively with pH and glucose levels in pleural effusions. MMP-9 mRNA expression in lymphocytes tended to be higher in malignant pleural effusions of lung cancer than in the other groups without reaching statistical significance. The strongest immunoreactivity for MMP-9 was observed in epithelioid cells of tuberculous pleural tissues. Much lower levels of MMP-9 expression were found in tumor cells of pleural tissues.

CONCLUSIONS

MMP-9 is increased in tuberculous pleural effusions compared with transudates and malignant pleural effusions of lung cancer and is produced predominantly by epithelioid cells in the granulomas of tuberculous pleural tissues.

Cartilage interstitial fluid load support in unconfined compression following enzymatic digestion

Interstitial fluid pressurization plays an important role in cartilage biomechanics and is believed to be a primary mechanism of load support in synovial joints. The objective of this study was to investigate the effects of enzymatic degradation on the interstitial fluid load support mechanism of articular cartilage in unconfined compression. Thirty-seven immature bovine cartilage plugs were tested in unconfined compression before and after enzymatic digestion. The peak fluid load support decreased significantly (p < 0.0001) from 84 +/- 10% to 53 +/- 19% and from 80 +/- 10% to 46 +/- 21% after 18-hours digestion with 1.0 u/mg-wet-weight and 0.7 u/mg-wet-weight of collagenase, respectively. Treatment with 0.1 u/ml of chondroitinase ABC for 24 hours also significantly reduced the peak fluid load support from 83 +/- 12% to 48 +/- 16% (p < 0.0001). The drop in interstitial fluid load support following enzymatic treatment is believed to result from a decrease in the ratio of tensile to compressive moduli of the solid matrix.

Tuberculous Effusion: ADA Activity Correlates with CD4+ Cell Numbers in the Fluid and the Pleura

BACKGROUND

Adenosine deaminase (ADA) is a commonly used marker in the diagnosis of tuberculous effusion and there is evidence that its production is linked to T cells and monocytes. Data on the correlation between ADA and T cells or macrophages in tuberculous effusions are conflicting. Furthermore, no studies have examined a possible correlation between pleural tissue infiltration and ADA.

OBJECTIVES

We undertook this study to examine cell subsets in the fluid and the pleura in tuberculous effusion and their correlation to ADA. The use of cell subsets as a marker in the differential diagnosis was also examined.

METHODS

Pleural fluid from 36 patients with tuberculous and 34 patients with malignant effusion as well as pleural tissue biopsies from 16 patients with tuberculous pleurisy were examined. The APAAP and the avidin-biotin complex immunocytochemical methods were used to examine CD4+ T cells and macrophages (CD68+), while ADA activity was measured by the Giusti colorimetric method.

RESULTS

Our results showed that, in pleural fluid, CD4+ cells and ADA were significantly higher in tuberculous compared to malignant effusion (p<0.001 for all measurements). In pleural tissue biopsies, macrophages were the predominant cells but CD4+ T cells were also abundant. A significant correlation was found between ADA and CD4+ numbers in pleural fluid and tissue (r=0.45, p<0.01; r=0.75, p<0.001, respectively). ADA had high sensitivity and specificity for differential diagnosis while cell subsets did not.

CONCLUSIONS

These results indicate that ADA activity correlates to CD4+ T cell infiltration in the pleura and the fluid. Moreover, ADA but no cell subsets may be used as markers of tuberculous effusion.

Influence of Lactation History on Breast Nipple Aspirate Fluid Yields and Fluid Composition

Analysis of nipple aspirate fluid (NAF) can be useful for understanding the impact that various lifestyle factors have on the biology of the breast. In this study, breast NAF was obtained at baseline from premenopausal women who volunteered for a dietary intervention trial. The influence of lactation history on both fluid yields and fluid composition was explored. We examined the levels of fat-soluble micronutrients (tocopherols, carotenoids, retinol), one lipid oxidation product (8-isoprostane), cholesterol, and protein in NAF. Roughly half of the women in the trial had never lactated, but this did not affect fluid yields appreciably. Carotenoid and tocopherol levels were significantly higher in NAF from women who lactated 6 months or more versus women who had lactated for shorter periods of time or never, but 8-isoprostane, protein, and cholesterol levels were not affected appreciably by lifetime lactation history. Longer times after weaning were associated with higher cholesterol levels, and there also was a suggestion the fat-soluble micronutrients declined with time after weaning. This is of interest since high cholesterol levels in breast fluid have been associated with an increased breast cancer risk, while carotenoids and tocopherols are thought to be protective. The results of this study provide further evidence of the potential benefits of prolonged lactation via its influence on NAF composition.

A potential role for nitric oxide pathway in tuberculous pleural effusion

SETTING

Tuberculous pleural effusion leads to an immune response involving mainly immune and mesothelial cells. Nitric oxide (NO) produced by these cells may have antimycobacterial effects against Mycobacterium tuberculosis.

OBJECTIVE

To investigate the possible role of NO in connection with the arginase enzyme, which controls the synthesis of NO through arginine depletion.

DESIGN

Pleural fluid samples from 20 patients with tuberculous pleural effusion were used for arginase activity and NO level determination. Results were compared with those from 12 lung cancer, 12 pneumonia and 12 congestive heart failure (CHF) patients.

RESULTS

Pleural arginase activity in tuberculosis patients was found to be significantly decreased compared to lung cancer and pneumonia groups, while the NO level was higher in tuberculosis patients. All groups except the CHF group had significant correlations between NO level and white blood cell count. Arginase activity and red blood cell count correlated significantly in lung cancer and CHF groups.

CONCLUSION

The arginine-NO pathway seems to be involved in the pathogenesis of tuberculous pleural effusion. Decreased arginase activity may cause arginine accumulation, which may then lead to increased NO synthesis by immune and mesothelial cells, reflecting a host defence mechanism.

Modelling solid tumour growth using the theory of mixtures

In this paper the theory of mixtures is used to develop a two-phase model of an avascular tumour, which comprises a solid, cellular, phase and a liquid phase. Mass and momentum balances which are used to derive the governing equations are supplemented by constitutive laws that distinguish the two phases and enable the stresses within the tumour to be calculated. Novel features of the model include the dependence of the cell proliferation rate on the cellular stress and the incorporation of mass exchange between the two phases. A combination of numerical and analytical techniques is used to investigate the sensitivity of equilibrium tumour configurations to changes in the model parameters. Variation of parameters such as the maximum cell proliferation rate and the rate of natural cell death yield results which are consistent with analyses performed on simpler tumour growth models and indicate that the two-phase formulation is a natural extension of the earlier models. New predictions relate to the impact of mechanical effects on the tumour's equilibrium size which decreases under increasing stress and/or external loading. In particular, as a parameter which measures the reduction in cell proliferation due to cell stress is increased a critical value is reached, above which the tumour is eliminated.

Nipple Aspirate Fluid Cytology and the Gail Model for Breast Cancer Risk Assessment in a Screening Population

BACKGROUND

Recent guidelines suggest that chemoprevention with tamoxifen may be appropriate for women who have a 5-year risk of breast cancer greater than 1.66% calculated using the Gail model.

OBJECTIVES

To determine whether nipple aspirate fluid (NAF) cytology combined with the Gail model provides breast cancer risk assessment that is superior to either method alone.

METHODS

Prospective observational cohort of 6,904 asymptomatic women. Breast cancer cases were identified through follow-up with the women and linkage to cancer registries. We used proportional hazards modeling to recalculate the coefficients for the predictor variables used in the Gail model. NAF cytology was added to create a second model. The two models were compared using the concordance statistic (c-statistic).

RESULTS

During 14.6 years of follow-up, 400 women were diagnosed with breast cancer. There were 940 (14%) women with hyperplasia and 109 (1.6%) women with atypical hyperplasia found in NAF. Adding NAF cytology results to the Gail model significantly improved the model fit (P < 0.0001). The c-statistic for the Gail model was 0.62, indicating only modest discriminatory accuracy. Adding NAF cytology to the model increased the c-statistic to 0.64. NAF cytology results had the largest effect on discriminatory accuracy among women in the upper third of Gail model risk. The relative incidence for the highest quintile of risk score compared with the lowest quintile was 7.2 for the Gail model and 8.0 for the model including NAF cytology.

CONCLUSION

NAF cytology has the potential to improve prediction models of breast cancer incidence, particularly for high-risk women.

Increase in a distinct pulmonary macrophage subset possessing an antigen-presenting cell phenotype and in vitro APC activity following silica exposure

Silica inhalation results in chronic lung inflammation and fibrosis. While the role of the alveolar macrophage (AM) is considered key to the effects of silica on lung pathology, the etiology is not completely understood. Evidence suggests an increase in antigen presenting cell (APC) activity as a contributing factor to this process, as well as potential roles for both AM and interstitial macrophages (IM) in silicosis. In order to study the effects of crystalline silica on the APC activity of pulmonary macrophages, mice were exposed intranasally and changes in pulmonary macrophage populations were assessed using flow cytometry. Following intranasal instillation of silica, a significant increase in the APC activity of AM was observed, as well as a significant increase in a subset of IM expressing classic APC markers (MHC class II, CD11c). In addition, an in vitro system using bone marrow-derived macrophages (BMDM) was generated to assess the effects of silica on the APC activity of macrophages in vitro. Data using BMDM in the in vitro APC assay demonstrated a significant increase in APC activity following silica exposure, but not following exposure to saline or a control particle (TiO(2)). Using a combination of in vivo and in vitro experiments, the current study describes a significant increase in an interstitial macrophage subset with an APC phenotype, as well as an increase in the APC activity of both AM and BMDM, as a direct result of exposure to crystalline silica. These studies suggest a specific mechanism, macrophage subset activation, by which crystalline silica exposure results in chronic pulmonary inflammation and, eventually, fibrosis.

Quantitative analysis of biological effect on membrane fouling in submerged membrane bioreactor

The objective of this study is to investigate solids concentration and extracellular polymeric substance (EPS) effects on the membrane fouling in the submerged membrane bioreactor. The relationship between the solids retention time (SRT) and the amount of EPS is observed in three lab-scale MBRs. Additionally, the EPS effect on membrane fouling is quantified by calculating the specific cake resistance (alpha) using an unstirred batch cell test. By observing the sludge over a long period under various SRT scenarios, a wide range of EPS and membrane fouling data is obtained. These observations provide sufficient evidence of the functional relationship between SRT, EPS and alpha. As SRT decreases, the amount of EPS bound in sludge floc becomes higher in the high MLSS condition (> 5,000 mg/L). The amount of EPS in the sludge floc has positive influence on alpha. A sigmoid trend between EPS and alpha is observed and the functional relationship obtained by dimensional analysis is consistent with the experimental results.

Energy gradients for the homeostatic control of brain ECF composition and for VT signal migration: introduction of the tide hypothesis

The present paper enlightens a new point of view on brain homeostasis and communication, namely how the brain takes advantage of different chemical-physical phenomena such as pressure waves, and temperature and concentration gradients to allow the renewal of the extra-cellular fluid (i.e., the homeostasis of the brain internal milieu) as well as some forms of intercellular communications (Volume Transmission) at an energy cost much lower than the classical synaptic transmission (the prototype of Wiring Transmission). In particular, the possible functional meaning of the intracranial pressure waves is discussed in the frame of the so called "tide hypothesis" which maintains that the pressure waves, created by the cardiac pump, modulate the cerebro-spinal fluid flow from and towards the subarachnoid space as well as towards and from the Virchow-Robin spaces. These fluid push-pull movements favor both the migration of signals and the extra-cellular fluid renewal, especially in the cerebral cortex.

Delineating bone's interstitial fluid pathway in vivo

Although interstitial fluid flow has been suggested to play a role in bone adaptation and metabolism, the constituents and ultrastructure of this interstitial fluid pathway are not well understood. Bone's lacunar-canalicular porosity is generally believed to be a continuous interstitial fluid pathway through which osteocytes sense external mechanical loading as well as obtain nutrients and dispose of wastes. Recent electron microscopy studies have suggested that a fiber matrix surrounds the osteocytic cell processes and fills this pericellular fluid space. However, studies injecting tracer molecules into the bone vasculature have provided conflicting results about the pore size or the fiber spacing of the interstitial fluid pathway. In addition, whether the smaller collagen-apatite porosity in adult bone is also a continuous fluid pathway is still unclear. To delineate bone's interstitial fluid pathway, four tracers of various size were injected into rats: reactive red (approximately 1 nm), microperoxidase (MP, approximately 2 nm), horseradish peroxidase (HRP, approximately 6 nm), and ferritin (approximately 10 nm). Five minutes after injection, the tibiae were harvested and processed using histological protocols optimized to minimize processing time to reduce possible redistribution of tracer molecules. The number of blood vessels and osteocytic lacunae labeled with the tracers per unit bone area was then measured for mid-diaphysial cross-sections of the tibia. While none of the tracers was detected within the mineralized bone matrix (the collagen-apatite porosity) using light microscopy, all the tracers except ferritin were found to pass through the canaliculi and appear in the osteocytic lacunae. These results indicate that while small tracers (<6 nm) readily pass through the lacunar-canalicular porosity in the absence of mechanical loading, there appears to be an upper limit or cutoff size between 6 and 10 nm for molecular movement from bone capillaries to osteocytic lacunae in rat long bone. This range of pore size contains the most likely fiber spacing (approximately 7 nm) that has been proposed for the lacunar-canalicular annular space based on the presence of a proteoglycan fiber matrix surrounding the osteocyte.

Circulating sodium pump inhibitors in five volume-expanded humans

BACKGROUND

We have previously reported the isolation from human placentas of an inhibitor of the sodium pump (Na/K ATP-ase) of molecular weight 370 Da, which is considered to have a dihydropyrone-substituted steroid (bufenolide) structure.

OBJECTIVE

To examine if this inhibitor is present outside of the pregnant state.

METHODS

We examined the plasma ultrafiltrate of patients who were clinically volume-expanded. During the period of this study five such patients were identified. One was receiving haemofiltration for acute renal failure and four were being treated by plasma exchange. High performance liquid chromatograph (HPLC) purified fractions obtained from each of these five patients inhibited the human leucocyte sodium pump in vitro.

RESULTS

Each of the purified fractions that inhibited the leucocyte ATP-ase in vitro contained a compound of mass 370 Da, the same mass as that found previously in placental extracts. This inhibitory factor was absent from HPLC purified fractions of plasma ultrafiltrate obtained from fifty-five patients who were clinically normovolaemic. Negative ion mass spectrometry (MS)/MS of the inhibitory material produced the fragmentation pattern characteristic of the placenta-derived pump inhibitor in only one of the five samples. The other four samples, although having the same mass, exhibited a different fragmentation pattern.

CONCLUSION

The results suggest that an inhibitor of the sodium pump, identical in mass to that obtained from human placentas, circulates in the plasma of volume-expanded patients. The fragmentation pattern observed in negative ion mass spectrometry in the majority of the volume expanded patients may represent the presence of an isomer of the sodium pump inhibitor previously described in placental material.