Biochar and vegetation effects on discharge water quality from organic-substrate green roofs

Green roofs have been increasingly used to improve stormwater management, but poor vegetation performance on roof systems, varying with vegetation type, can degrade discharge quality. Biochar has been suggested as an effective substrate additive for green roofs to improve plant performance and discharge quality. However, research on the effects of biochar and vegetation on discharge quality in the long term is lacking and the underlying mechanisms involved are unclear. We examined the effects of biochar amendment and vegetation on discharge quality on organic-substrate green roofs with pre-grown sedum mats and direct-seeded native plants for three years and investigated the key factors influencing discharge quality. Sedum mats reduced the leaching of nutrients and particulate matter by 6-64% relative to native plants, largely due to the higher initial vegetation cover of the former. Biochar addition to sedum mat green roofs resulted in the best integrated water quality due to enhanced plant cover and sorption effects. Structural equation modeling revealed that nutrient leaching was primarily influenced by rainfall depth, time, vegetation cover, and substrate pH. Although biochar-amended sedum mats showed better discharge quality from organic-substrate green roofs, additional ecosystem services may be provided by native plants, suggesting future research to optimize plant composition and cover and biochar properties for sustainable green roofs.

Is endothelial dysfunction a driving force of COVID-19 induced coagulopathy?

Background/Introduction

There are numerous reports regarding the direct endothelial damage by the SARS-CoV-2 that can lead to activation of both plasma hemostasis and platelet aggregation. However, the mechanism of interaction between endothelium and haemostasis in COVID-19 remains unclear.

Purpose

The aim of our study was to assess the relationship between each link of clot formation process (endothelial function, plasma coagulation, platelet aggregation) with the severity of the disease.

Methods

58 COVID-19 patients were included in our study. Patients were divided into moderate (n=39) and severe (n=18) subgroups. All patients underwent a flow-mediated dilation (FMD) test, impedance aggregation, rotational thromboelastometry, thrombodynamics and von Willebrand factor antigen (vWF: Ag) quantification. All measurements were repeated on days 3 (point 2) and 9 (point 3) of hospitalization.

Results

COVID-19 patients demonstrated the enhanced plasma coagulation (clotting time, s 613,0 [480; 820], clot growth rate, μm/min 32,75 [29,3; 38,7]). At point 1 no significant difference in parameters of plasma coagulation between patients' subgroups was noted. At point 2 a significant decrease in the size (CS, μm 1278.0 [1216.5; 1356.5] vs 965.0 [659.8; 1098.0], p<0,01) and clot growth rate (μm/min 32,4 [29,2; 35,0] vs 17,7 [10,3; 24,4], p<0,01) under the influence of anticoagulants in the moderate subgroup compared with point 1 was observed. We didn't observe such phenomenon in severe subgroup.

There was no significant difference in platelet aggregation between subgroups at point 1. During the course of the disease the patients in the moderate and severe subgroups demonstrated a significant increase in platelet aggregation induced by arachidonic acid and ADP (severe: AUC ARA 48,0 [25,0; 59,0] vs 77,5 [55,8; 92,7], p=0,04; AUC ADP 44,0 [41,0; 56,0] vs 58,0 [45,5; 69,0], p=0,04; moderate: AUC ARA 31,5 [19,8; 50,7] vs 56,0 [39,0; 76,0], p=0,01; AUC ADP 43,0 [20,0; 59,0] vs 56,6 [50,3; 70,5], p=0,04;), in moderate subgroup the significant increase in TRAP-induced aggregation was also noted (AUC TRAP 58,0 [41,0; 69,5] vs 76,0 [58,3; 81,5], p=0,048).

There were no significant differences in the FMD-test results between the patient subgroups. FMD-test results were predominantly within the reference ranges (7,1 [4,0; 8,8]).

Patients in the severe subgroup had significantly higher levels of vWF: Ag (228,0 [205,3; 240,7] vs 232,0 [226,0; 423,0], p=0,03).

Conclusion

SARS-CoV-2 infection was characterized by increased levels of vWF:Ag, that could represent the local endothelial damage, meanwhile there was no generalized endothelial dysfunction assessed via FMD-test in moderate to severe patients. At the same time the enhanced plasma coagulation in COVID-19 patients was observed.

FUNDunding Acknowledgement

Type of funding sources: None.

Extracellular acidosis enhances Zika virus infection both in human cells and ex-vivo tissue cultures from female reproductive tract

Zika virus (ZIKV) is a flavivirus transmitted by mosquitoes of the genus Aedes, but unlike other flaviviruses, ZIKV can be sexually transmitted by vaginal intercourse. The healthy vaginal pH ranges from 4.0 to 6.0, reaching values of 6.0-7.0 after semen deposition. Here, we report that low extracellular pH values (range 6.2-6.6) dramatically increase ZIKV infection on cell lines of different origin including some derived from the female genital tract and monocyte-derived macrophages. Furthermore, low pH significantly increased ZIKV infection of human ectocervix and endocervix cultured ex-vivo. Enhancement of infection by low pH was also observed using different ZIKV strains and distinct methods to evaluate viral infection, i.e. plaque assays, RT-PCR, flow cytometry, and fluorescence microscopy. Analysis of the mechanisms involved revealed that the enhancement of ZIKV infection induced by low pH was associated with increased binding of the viral particles to the heparan sulphate expressed on the target cell surface. Acidosis represents a critical but generally overlooked feature of the female genital tract, with major implications for sexual transmission diseases. Our results suggest that low vaginal pH might promote male-to-female transmission of ZIKV infection.

HCV coinfection of the HIV-infected patients with discordant CD4+ T-cell response to antiretroviral therapy leads to intense systemic inflammation

The level of proinflammatory markers was assessed in HIV-infected patients that were coinfected with hepatitis C virus (HCV) and had failed to restore the CD4⁺ T cell counts (immunological nonresponders, INR) during the antiretroviral therapy (ART). Among four patient groups (HIV⁺HCV^- and HIV⁺HCV⁺ subjects with the concordant response to ART; HIV⁺HCV^- and HIV⁺HCV⁺ subjects that were INR), the greatest systemic inflammation was in the latter group. The maximum difference was between the subjects HIV⁺HCV^-INR and HIV⁺HCV⁺ INR: the blood of coinfected patients contained significantly higher concentrations of the IP-10, sCD163, sTNF-RI, and sTNF-RII and of bacterial lipopolysaccharide. Systemic inflammation in HIV/HCV coinfected patients with the discordant response to ART is probably caused by a breach of hepatic barrier for the intestine products.

Stimulating a Canadian narrative for climate

This perspective documents current thinking around climate actions in Canada by synthesizing scholarly proposals made by Sustainable Canada Dialogues (SCD), an informal network of scholars from all 10 provinces, and by reviewing responses from civil society representatives to the scholars’ proposals. Motivated by Canada’s recent history of repeatedly missing its emissions reduction targets and failing to produce a coherent plan to address climate change, SCD mobilized more than 60 scholars to identify possible pathways towards a low-carbon economy and sustainable society and invited civil society to comment on the proposed solutions. This perspective illustrates a range of Canadian ideas coming from many sectors of society and a wealth of existing inspiring initiatives. Solutions discussed include climate change governance, low-carbon transition, energy production, and consumption. This process of knowledge synthesis/creation is novel and important because it provides a working model for making connections across academic fields as well as between academia and civil society. The process produces a holistic set of insights and recommendations for climate change actions and a unique model of engagement. The different voices reported here enrich the scope of possible solutions, showing that Canada is brimming with ideas, possibilities, and the will to act.

Systemic inflammation and liver damage in HIV/hepatitis C virus coinfection

OBJECTIVES

Chronic hepatitis C virus (HCV) and HIV viral infections are characterized by systemic inflammation. Yet the relative levels, drivers and correlates of inflammation in these settings are not well defined.

METHODS

Seventy-nine HIV-infected patients who had been receiving antiretroviral therapy (ART) for more than 2 years and who had suppressed plasma HIV levels (< 50 HIV-1 RNA copies/mL) were included in the study. Two patient groups, HCV-positive/HIV-positive and HCV-negative/HIV-positive, and a control group comprised of healthy volunteers (n = 20) were examined. Markers of systemic inflammation [interleukin (IL)-6, interferon gamma-induced protein (IP)-10, soluble tumour necrosis factor receptor-I (sTNF-RI) and sTNF-RII], monocyte/macrophage activation [soluble CD163 (sCD163), soluble CD14 and neopterin], intestinal epithelial barrier loss [intestinal fatty acid binding protein (I-FABP) and lipopolysaccharide (LPS)] and coagulation (d-dimers) were analysed. CD4 naïve T cells and CD4 recent thymic emigrants (RTEs) were enumerated.

RESULTS

Plasma levels of IP-10, neopterin and sCD163 were higher in HCV/HIV coinfection than in HIV monoinfection and were positively correlated with indices of hepatic damage [aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the AST to platelet ratio index (APRI)]. Levels of I-FABP were comparably increased in HIV monoinfection and HIV/HCV coinfection but LPS concentrations were highest in HCV/HIV coinfection, suggesting impaired hepatic clearance of LPS. Plasma HCV levels were not related to any inflammatory indices except sCD163. In coinfected subjects, a previously recognized relationship of CD4 naïve T-cell and RTE counts to hepatocellular injury was defined more mechanistically by an inverse relationship to sCD163.

CONCLUSIONS

Hepatocellular injury in HCV/HIV coinfection is linked to elevated levels of certain inflammatory cytokines and an apparent failure to clear systemically translocated microbial products. A related decrease in CD4 naïve T cells and RTEs also merits further exploration.

Decoupling factors affecting plant diversity and cover on extensive green roofs

Supplemental irrigation systems are often specified on green roofs to ensure plant cover and growth, both important components of green roof performance and aesthetics. Properties of the growing media environment too can alter the assemblage of plant species able to thrive. In this study we determine how plant cover, above ground biomass and species diversity are influenced by irrigation and growing media. Grass and forb vegetative cover and biomass were significantly greater in organic based growing media but there was no effect of supplemental irrigation, with two warm season grasses dominating in those treatments receiving no supplemental irrigation. On the other hand, plant diversity declined without irrigation in organic media, and having no irrigation in inorganic growing media resulted in almost a complete loss of cover. Sedum biomass was less in inorganic growing media treatments and species dominance shifted when growing media organic content increased. Our results demonstrate that supplemental irrigation is required to maintain plant diversity on an extensive green roof, but not necessarily plant cover or biomass. These results provide evidence that planting extensive green roofs with a mix of plant species can ensure the survival of some species; maintaining cover and biomass when supplemental irrigation is turned off to conserve water, or during extreme drought.

Antitumor effect of k+/h+-antiporter nigericin on human lung-carcinoma grown in in-vivo-like histocultures

Small shifts of intracellular pH (pH(i)) play a crucial role in many cellular functions, in particular progression through the cell cycle. We present results demonstrating that in the majority of cases, nigericin shows cytostatic effect on tumor cells in the in vivo-like 3-dimensional histocultures of human lung tissues while the normal tissue remains morphologically intact.

Primate embryonic stem cells create their own niche while differentiating in three-dimensional culture systems

Rhesus monkey embryonic stem cells (ESCs) (R366.4), cultured on a three-dimensional (3D) collagen matrix with or without human neonatal foreskin fibroblasts (HPI.1) as feeder cells, or embedded in the collagen matrix, formed complex tubular or spherical gland-like structures and differentiated into phenotypes characteristic of neural, epithelial and endothelial lineages. Here, we analysed the production of endogenous extracellular matrix (ECM) proteins, cell-cell adhesion molecules, cell-surface receptors, lectins and their glycoligands, by differentiating ESCs, forming a micro-environment, a niche, able to positively influence cell behaviour. The expression of some of these molecules was modulated by HPI.1 cells while others were unaffected. We hypothesized that both soluble factors and the niche itself were critical in directing growth and/or differentiation of ESCs in this 3D environment. Creating such an appropriate experimental 3D micro-environment, further modified by ESCs and modulated by exogenous soluble factors, may constitute a template for adequate culture systems in developmental biology studies concerning differentiation of stem cells.

Suppression of CCR5- but not CXCR4-tropic HIV-1 in lymphoid tissue by human herpesvirus 6

HIV-1 infects target cells via a receptor complex formed by CD4 and a chemokine receptor, primarily CCR5 or CXCR4 (ref. 1). Commonly, HIV-1 transmission is mediated by CCR5-tropic variants, also designated slow/low, non-syncytia-inducer or macrophage-tropic, which dominate the early stages of HIV-1 infection and frequently persist during the entire course of the disease. In contrast, HIV-1 variants that use CXCR4 are typically detected at the later stages, and are associated with a rapid decline in CD4+ T cells and progression to AIDS (refs. 2,7-11). Disease progression is also associated with the emergence of concurrent infections that may affect the course of HIV disease by unknown mechanisms. A lymphotropic agent frequently reactivated in HIV-infected patients is human herpesvirus 6 (HHV-6), which has been proposed as a cofactor in AIDS progression. Here we show that in human lymphoid tissue ex vivo, HHV-6 affects HIV-1 infection in a coreceptor-dependent manner, suppressing CCR5-tropic but not CXCR4-tropic HIV-1 replication, as shown with both uncloned viral isolates and isogenic molecular chimeras. Furthermore, we demonstrate that HHV-6 increases the production of the CCR5 ligand RANTES ('regulated upon activation, normal T-cell expressed and secreted'), the most potent HIV-inhibitory CC chemokine, and that exogenous RANTES mimics the effects of HHV-6 on HIV-1, providing a mechanism for the selective blockade of CCR5-tropic HIV-1. Our data suggest that HHV-6 may profoundly influence the course of HIV-1 infection.

Human immunodeficiency virus type 1 (HIV-1) non-B subtypes are similar to HIV-1 subtype B in that coreceptor specificity is a determinant of cytopathicity in human lymphoid tissue infected ex vivo

We sought to determine the relationship between virus-mediated CD4(+) T-lymphocyte cytopathicity and viral coreceptor preference among various human immunodeficiency virus type 1 (HIV-1) subtypes in an ex vivo-infected human lymphoid tissue model. Our data show that all R5 HIV-1 infections resulted in mild depletion of CD4(+) T lymphocytes, whereas all X4 HIV-1 infections caused severe depletion of CD4(+) T lymphocytes regardless of their subtype origin. Thus, at least for the viruses within subtypes A, B, C, and E that were tested, coreceptor specificity is a critical factor that determines the ability of HIV-1 to deplete CD4(+) T cells in human lymphoid tissue infected ex vivo.

CD4 down-modulation by human immunodeficiency virus type 1 Nef correlates with the efficiency of viral replication and with CD4(+) T-cell depletion in human lymphoid tissue ex vivo

The human immunodeficiency virus type 1 (HIV-1) Nef protein is an important virulence factor. Nef has several functions, including down-modulation of CD4 and class I major histocompatibility complex cell surface expression, enhancement of virion infectivity, and stimulation of viral replication in peripheral blood mononuclear cells. Nef also increases HIV-1 replication in human lymphoid tissue (HLT) ex vivo. We analyzed recombinant and primary nef alleles with highly divergent activity in different in vitro assays to clarify which of these Nef activities are functionally linked. Our results demonstrate that Nef activity in CD4 down-regulation correlates significantly with the efficiency of HIV-1 replication and with the severity of CD4(+) T-cell depletion in HLT. In conclusion, HIV-1 Nef variants with increased activity in CD4 down-modulation would cause severe depletion of CD4(+) T cells in lymphoid tissues and accelerate AIDS progression.

Coreceptor choice and T cell depletion by R5, X4, and R5X4 HIV-1 variants in CCR5-deficient (CCR5delta32) and normal human lymphoid tissue

Coreceptor utilization by HIV-1 is an important determinant of pathogenesis. However, coreceptor selectivity is defined in vitro, while in vivo critical pathogenic events occur in lymphoid tissues. Using pharmacological inhibitors, we recently provided evidence that coreceptor selectivity by the R5X4 dual-tropic isolate 89.6 was more restricted in ex vivo infected lymphoid tissue than in vitro [S. Glushakova, Y. Yi, J. C. Grivel, A. Singh, D. Schols, E. De Clercq, R. G. Collman, and L. Margolis (1999). J. Clin. Invest. 104, R7-R11]. Here we extend those observations using CCR5-deficient (CCR5Delta32) lymphoid tissue as well as additional primary isolates. We definitively show that neither CCR5 nor secondary coreceptors used in vitro mediate 89.6 infection in lymphoid tissue. We also demonstrate that restricted coreceptor use in lymphoid tissue ex vivo compared with in vitro utilization occurs with other dual-tropic primary isolates and is not unique to 89.6. For all strains tested that are dual tropic in vitro, severe CD4 T cell depletion in lymphoid tissue correlated with preferential CXCR4 use in this ex vivo system.

Replication of simian immunodeficiency virus (SIV) in ex vivo lymph nodes as a means to assess susceptibility of macaques in vivo

Six macaques, apparently uninfected, following low-dose exposure to the pathogenic SIV(mac251) and SIV(SME660) by the mucosal route, were used in a pilot study to investigate whether infectability of ex vivo lymph nodes could predict resistance and/or susceptibility to SIV infection in vivo. Of six macaques exposed to the less-pathogenic virus SIV(MNE), four resisted viral infection. Analysis of the susceptibility of the PBMC of these four animals before SIV(MNE) challenge indicated that all of them were resistant to infection by the SIV(BK28) isolate and, in three of them, this resistance was dependent on CD8+ T cells. Blocks of lymph nodes of these four macaques were resistant to SIV(MNE) infection ex vivo following SIV(MNE) viral challenge exposure. However, the same blocks from the same animals were permissive to the more virulent SIV(251(32H)). Accordingly, three of these macaques were readily infected following challenge exposure with SIV(251(32H)). Lymphoproliferative responses in blood or lymph nodes, local C-C chemokine production in the lymph-node explants, and cytotoxic T-cell activity measured throughout the study did not correlate with ex vivo resistance or susceptibility to in vivo infection. In conclusion, PBMC and lymph-node resistance or susceptibility to infection ex vivo appeared to correlate with in vivo infectivity and, thus, these approaches should be further tested for their predictive value for in vivo infection.

Human immunodeficiency virus type 1 induces apoptosis in CD4(+) but not in CD8(+) T cells in ex vivo-infected human lymphoid tissue

Progression of human immunodeficiency virus (HIV) disease is associated with massive death of CD4(+) T cells along with death and/or dysfunction of CD8(+) T cells. In vivo, both HIV infection per se and host factors may contribute to the death and/or dysfunction of CD4(+) and CD8(+) T cells. Progression of HIV disease is often characterized by a switch from R5 to X4 HIV type 1 (HIV-1) variants. In human lymphoid tissues ex vivo, it was shown that HIV infection is sufficient for CD4(+) T-cell depletion. Here we address the question of whether infection of human lymphoid tissue ex vivo with prototypic R5 or X4 HIV variants also depletes or impairs CD8(+) T cells. We report that whereas productive infection of lymphoid tissue ex vivo with R5 and X4 HIV-1 isolates induced apoptosis in CD4(+) T cells, neither viral isolate induced apoptosis in CD8(+) T cells. Moreover, in both infected and control tissues we found similar numbers of CD8(+) T cells and similar production of cytokines by these cells in response to phorbol myristate acetate or anti-CD3-anti-CD28 stimulation. Thus, whereas HIV-1 infection per se in human lymphoid tissue is sufficient to trigger apoptosis in CD4(+) T cells, the death of CD8(+) T cells apparently requires additional factors.

Human immunodeficiency virus type 1 coreceptor preferences determine target T-cell depletion and cellular tropism in human lymphoid tissue

The present study sought to determine how usage of coreceptors by human immunodeficiency virus type 1 dictates cell tropism and depletion of CD4(+) T cells in human lymphoid tissues cultured ex vivo. We found that coreceptor preferences control the marked, preferential depletion of coreceptor-expressing CD4(+) lymphocytes. In addition, there was a strong, but not absolute, preference shown by CXCR4-using strains for lymphocytes and by CCR5-using strains for macrophages.

Development of Kudoa thyrsites (Myxozoa: Myxosporea) in netpen-reared Atlantic salmon determined by light microscopy and a polymerase chain reaction test

The intramuscular phase of development of Kudoa thyrsites, the myxosporean associated with post-mortem myoliquefaction, or 'soft flesh syndrome', is described using histological preparations of the musculature of seawater netpen-reared Atlantic salmon Salmo salar. Hatchery-reared Atlantic salmon were naturally exposed to the infective stage while held in the experimental seawater netpens of the Pacific Biological Station in Nanaimo, British Columbia, Canada. In fish exposed during the summer of 1995, K. thyrsites infections were first detected in the somatic musculature at 13 wk post-exposure (p.e.) using only light microscopy. In the 1997 exposure, infections were first detected at 6 wk p.e. using a PCR test and at 9 wk p.e. using light microscopy. The earliest stage detected by histology was a small plasmodium containing 4 nuclei. No host response was observed that was directly related to the presence of intact plasmodia within muscle fibers. However, a response was associated with ruptured plasmodia, which was characterized by chronic, multifocal inflammation between the muscle fibers.

Preferential coreceptor utilization and cytopathicity by dual-tropic HIV-1 in human lymphoid tissue ex vivo

Many HIV-1 isolates at the late stage of disease are capable of using both CXCR4 and CCR5 in transfected cell lines, and are thus termed dual-tropic. Here we asked whether these dual-tropic variants also use both coreceptors for productive infection in a natural human lymphoid tissue microenvironment, and whether use of a particular coreceptor is associated with viral cytopathicity. We used 3 cloned dual-tropic HIV-1 variants, 89.6 and its chimeras 89-v345.SF and 89-v345.FL, which use both CCR5 and CXCR4 in transfected cell lines. In human lymphoid tissue ex vivo, one variant preferentially used CCR5, another preferentially used CXCR4, and a third appeared to be a true dual-tropic variant. The 2 latter variants severely depleted CD4(+) T cells, whereas cytopathicity of the virus that used CCR5 only in lymphoid tissue was mild and confined to CCR5(+)/CD4(+) T cells. Thus, (a) HIV-1 coreceptor usage in vitro cannot be unconditionally extrapolated to natural microenvironment of human lymphoid tissue; (b) dual-tropic viruses are not homogeneous in their coreceptor usage in lymphoid tissue, but probably comprise a continuum between the 2 polar variants that use CXCR4 or CCR5 exclusively; and (c) cytopathicity toward the general CD4(+) T cell population in lymphoid tissue is associated with the use of CXCR4.

Nef enhances human immunodeficiency virus replication and responsiveness to interleukin-2 in human lymphoid tissue ex vivo

The nef gene is important for the pathogenicity associated with simian immunodeficiency virus infection in rhesus monkeys and with human immunodeficiency virus type 1 (HIV-1) infection in humans. The mechanisms by which nef contributes to pathogenesis in vivo remain unclear. We investigated the contribution of nef to HIV-1 replication in human lymphoid tissue ex vivo by studying infection with parental HIV-1 strain NL4-3 and with a nef mutant (DeltanefNL4-3). In human tonsillar histocultures, NL4-3 replicated to higher levels than DeltanefNL4-3 did. Increased virus production with NL4-3 infection was associated with increased numbers of productively infected cells and greater loss of CD4(+) T cells over time. While the numbers of productively infected T cells were increased in the presence of nef, the levels of viral expression and production per infected T cell were similar whether the nef gene was present or not. Exogenous interleukin-2 (IL-2) increased HIV-1 production in NL4-3-infected tissue in a dose-dependent manner. In contrast, DeltanefNL4-3 production was enhanced only marginally by IL-2. Thus, Nef can facilitate HIV-1 replication in human lymphoid tissue ex vivo by increasing the numbers of productively infected cells and by increasing the responsiveness to IL-2 stimulation.

CXCR4 utilization is sufficient to trigger CD4+ T cell depletion in HIV-1-infected human lymphoid tissue

The human chemokine receptors CCR5 and CXCR4 have emerged as the predominant cofactors, along with CD4, for cellular entry of HIV-1 in vivo whereas the contribution of other chemokine receptors to HIV disease has not been yet determined. CCR5-specific (R5) viruses predominate during primary HIV-1 infection whereas viruses with specificity for CXCR4 (R5/X4 or X4 viruses) often emerge in late stages of HIV disease. The evolution of X4 viruses is associated with a rapid decline in CD4+ T cells, although a causative relationship between viral tropism and CD4+ T cell depletion has not yet been proven. To rigorously test this relationship, we assessed CD4+ T cell depletion in suspensions of human peripheral blood mononuclear cells and in explants of human lymphoid tissue on exposure to paired viruses that are genetically identical (isogenic) except for select envelope determinants specifying reciprocal tropism for CXCR4 or CCR5. In both systems, X4 HIV-1 massively depleted CD4+ lymphocytes whereas matched R5 viruses depleted such cells only mildly despite comparable viral replication kinetics. These findings demonstrate that the coreceptor specificities of HIV-1 are a causal factor in CD4+ T cell depletion ex vivo and strongly support the hypothesis that the evolution of viral envelope leading to usage of CXCR4 in vivo accelerates loss of CD4+ T cells, causing immunodeficiency.

Long term organ culture of human prostate tissue in a NASA-designed rotating wall bioreactor

PURPOSE

To maintain ex vivo integral prostatic tissue including intact stromal and ductal elements using the NASA-designed Rotating Wall Vessel (RWV) which maintains colocalized cells in an environment that promotes both three-dimensional cellular interactions together with the uniform mass transfer of nutrients and metabolic wastes.

MATERIALS AND METHODS

Samples of normal prostate were obtained as a byproduct of transurethral prostatectomy or needle biopsy. Prostatic tissue dissected into small 1 x 1 mm. blocks was cultured in the Rotating Wall Vessel (RWV) Bioreactor for various time periods and analyzed using histological, immunochemical, and total cell RNA assays.

RESULTS

We report the long term maintenance of benign explanted human prostate tissue grown in simple culture medium, under the simulated microgravity conditions afforded by the RWV bioreactor. Mesenchymal stromal elements including blood vessels and architecturally preserved tubuloglandular acini were maintained for a minimum of 28 days. Cytokeratins, vimentin and TGF-beta2 receptor and ligand were preserved through the entire culture period as revealed by immunocytochemistry. Prostatic acid phosphatase (PAP) was continuously expressed during the culture period, although somewhat decreased. Prostatic specific antigen (PSA) and its transcript were down regulated over time of culture. Prostatic carcinoma cells from the TSU cell line were able to invade RWV-cultured benign prostate tissue explants.

CONCLUSIONS

The RWV bioreactor represents an additional new technology for culturing prostate tissue for further investigations concerning the basic physiology and pathobiology of this clinically important tissue.

Zoogeography of the parasites of Pacific halibut (Hippoglossus stenolepis) in the northeast Pacific

The parasite fauna of 336 adult Pacific halibut (Hippoglossus stenolepis) from 15 geographic localities along the North American coast, ranging from northern California to the northern Bering Sea, was examined to assess zoogeographic and latitudinal zonation of Pacific halibut parasites in the eastern North Pacific. Results show the existence of three zoogeographic zones in the northeast Pacific with boundaries near the southern Queen Charlotte Islands and in the vicinity of Kodiak Island. "Fuzziness" around these boundaries probably reflects small-scale fish movement and the complexity of parasite life cycles. These boundaries roughly correspond to those previously established using the fish and invertebrate faunas. Parasite species richness appears to be more directly correlated with halibut abundance than with latitude; parasite abundance appears to be correlated with temperature and therefore negatively correlated with latitude.

HIV: from molecular recognition to tissue pathogenesis

Dramatic progress has been made recently in identifying both viral and cellular molecules responsible for binding and fusion of HIV-1 to target cells. In vivo, HIV-1 infection is transmitted by viruses that recognize chemokine receptor CCR5, while viruses isolated at later stages of HIV disease often recognize another chemokine receptor, CXCR4. It is still not understood how this molecular tropism of HIV-1 is translated into the virus' ability to compromise normal cell functions, which results in impairment of lymphoid tissue and causes AIDS. Here, we discuss how the new molecular findings might relate to HIV pathogenesis in cells and tissues.

Domains in cell plasma membranes investigated by near-field scanning optical microscopy

Near-field scanning optical microscopy (NSOM) uses the near-field interaction of light from a sharp fiber-optic probe with a sample of interest to image surfaces at a resolution beyond the diffraction limit of conventional optics. We used NSOM to image fluorescently labeled plasma membranes of fixed human skin fibroblasts, either dried or in buffer. A patchy distribution of a fluorescent lipid analog suggestive of lipid domains was observed in the fixed, dried cells. The sizes of these patches were consistent with the sizes of domains implied by fluorescence photobleaching recovery measurements. Patches of fluorescent lipid analog were not spatially correlated with patches of transmembrane proteins, HLA class I molecules labeled with fluorescent antibody; the patchiness of the HLA class I molecules was on a smaller scale and was not localized to the same regions of membrane as the lipid analog. Sizes of HLA patches were deduced from a two-dimensional spatial autocorrelation analysis of NSOM images that resolved patches with radii of approximately 70 and approximately 600 nm on fixed, dried cells labeled with IgG and 300-600 nm on cells labeled with Fab and imaged in buffer. The large-size patches were also resolved by far-field microscopy. Both the spatial autocorrelation analysis and estimates from fluorescence intensity indicate that the small patches seen on fixed, dried cells contain approximately 25-125 HLA-I molecules each.

Coalition building for prevention: lessons learned from the North Carolina Community-Based Public Health Initiative

This article examines the four-year development of the North Carolina Community-Based Public Health Initiative consortium (NC CBPHI). The NC CBPHI consisted of four separate county coalitions and differed in both its agenda and membership from the many examples of coalitions described in the literature. This article presents and describes evaluation findings that identify six factors as important in coalition functioning and success in the CBPHI coalitions. These factors are: participation, communication, governance and rules for operation, staff/coalition member relationships, technical assistance and skills training, and conflict recognition and containment. Selected CBPHI coalition activities are also described and implications for public health practitioners are presented.

The parasites of Pacific halibut (Hippoglossus stenolepis) in the eastern North Pacific: host-level influences

Fifty-nine metazoan parasite taxa were identified from 536 Pacific halibut (Hippoglossus stenolepis) of three size classes (recruits (<10 cm), juveniles (10-55 cm), and subadults/adults (55-102 cm)). Pacific halibut harbor parasite communities that are among the richest and most abundant found in those marine fishes studied to date. The parasites are largely host generalists, being found in a wide variety of marine fishes. These three features appear to be due, in part, to the interplay of the large size, wide diet, extensive mobility, and long life-span of halibut, plus the lack of specificity in the marine system and the ability of marine parasites to be transferred trophically from prey fishes to piscivorous fishes. The parasite community in halibut is more similar to those in other flatfishes than to those in ecological analogs, suggesting that phylogeny is an important determinant as well. There are no differences in infections due to host sex. Recruits harbor few parasites, but parasite species and particularly individuals accumulate with host age and length and reflect the shift from a crustacean to a fish diet. Growth rate influences the number of parasite individuals in a given fish, probably reflecting food intake. The smallest fish in the 5-, 6-, and 7-year age-classes have more parasite individuals than slightly larger fish in the same age-class and weigh less than expected for their size; they may be debilitated by parasites.