Benthic and coral reef community field data for Heron Reef, Southern Great Barrier Reef, Australia, 2002-2018

This paper describes benthic coral reef community composition point-based field data sets derived from georeferenced photoquadrats using machine learning. Annually over a 17 year period (2002–2018), data were collected using downward-looking photoquadrats that capture an approximately 1 m² footprint along 100 m–1500 m transect surveys distributed along the reef slope and across the reef flat of Heron Reef (28 km²), Southern Great Barrier Reef, Australia. Benthic community composition for the photoquadrats was automatically interpreted through deep learning, following initial manual calibration of the algorithm. The resulting data sets support understanding of coral reef biology, ecology, mapping and dynamics. Similar methods to derive the benthic data have been published for seagrass habitats, however here we have adapted the methods for application to coral reef habitats, with the integration of automatic photoquadrat analysis. The approach presented is globally applicable for various submerged and benthic community ecological applications, and provides the basis for further studies at this site, regional to global comparative studies, and for the design of similar monitoring programs elsewhere.

Measurement(s)	marine benthic feature
Technology Type(s)	photoquadrat transect surveys
Factor Type(s)	benthic composition
Sample Characteristic - Organism	benthic communities
Sample Characteristic - Environment	coral reef • marine coral reef flat zone • marine coral reef crest • marine coral reef back reef • marine coral reef fore reef
Sample Characteristic - Location	Heron Island Reef, 23–052

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.14034320

Field data sets for seagrass biophysical properties for the Eastern Banks, Moreton Bay, Australia, 2004-2014

This paper describes seagrass species and percentage cover point-based field data sets derived from georeferenced photo transects. Annually or biannually over a ten year period (2004–2014) data sets were collected using 30–50 transects, 500–800 m in length distributed across a 142 km² shallow, clear water seagrass habitat, the Eastern Banks, Moreton Bay, Australia. Each of the eight data sets include seagrass property information derived from approximately 3000 georeferenced, downward looking photographs captured at 2–4 m intervals along the transects. Photographs were manually interpreted to estimate seagrass species composition and percentage cover (Coral Point Count excel; CPCe). Understanding seagrass biology, ecology and dynamics for scientific and management purposes requires point-based data on species composition and cover. This data set, and the methods used to derive it are a globally unique example for seagrass ecological applications. It provides the basis for multiple further studies at this site, regional to global comparative studies, and, for the design of similar monitoring programs elsewhere.

A WAVE2-Arp2/3 actin nucleator apparatus supports junctional tension at the epithelial zonula adherens

WAVE2–Arp2/3 is a major nucleator of actin assembly at the zonula adherens and likely acts in response to junctional Rac signaling. It supports myosin II recruitment to, and tension generation at, the junction.

The epithelial zonula adherens (ZA) is a specialized adhesive junction where actin dynamics and myosin-driven contractility coincide. The junctional cytoskeleton is enriched in myosin II, which generates contractile force to support junctional tension. It is also enriched in dynamic actin filaments, which are replenished by ongoing actin assembly. In this study we sought to pursue the relationship between actin assembly and junctional contractility. We demonstrate that WAVE2–Arp2/3 is a major nucleator of actin assembly at the ZA and likely acts in response to junctional Rac signaling. Furthermore, WAVE2–Arp2/3 is necessary for junctional integrity and contractile tension at the ZA. Maneuvers that disrupt the function of either WAVE2 or Arp2/3 reduced junctional tension and compromised the ability of cells to buffer side-to-side forces acting on the ZA. WAVE2–Arp2/3 disruption depleted junctions of both myosin IIA and IIB, suggesting that dynamic actin assembly may support junctional tension by facilitating the local recruitment of myosin.

Tuba and N-WASP function cooperatively to position the central lumen during epithelial cyst morphogenesis

The process of epithelial lumenogenesis requires coordination of a network of signaling machinery communicated to each cell through subsequent cell divisions. Formation of a single hollow lumen has previously been shown to require Tuba, a Cdc42 GEF, for Cdc42 activation and correct spindle orientation. Using a Caco-2 model of lumenogenesis, we show that knockdown (KD) of the actin regulator N-WASP, causes a multilumen phenotype similar to Tuba KD. Defects in lumenogenesis in Tuba KD and N-WASP KD cells are observed at the two cell stage with inappropriate marking of the pre-apical patch (PAP) - the precursor to lumen formation. Strikingly, both Tuba and N-WASP depend on each other for localization to the PAP. We conclude that N-WASP functions cooperatively with Tuba to facilitate lumenogenesis and this requires the polyproline region of N-WASP.

IL-1 signalling determines the fate of skin grafts expressing non-self protein in keratinocytes

Although IL-1 is a known inflammatory cytokine during pathogen infection, the role of IL-1 in skin graft rejection, particularly where foreign antigen is expressed exclusively in keratinocytes, is less understood. Here, we use a syngeneic skin graft system, where antigens are expressed in epithelial cells via either a keratin 14 or keratin 5 promoter, to explore the role of IL-1 in graft rejection and induction of epithelial antigen-specific effector CD8(+) T-cell function. Keratin 5 ovalbumin (K5mOVA) transgenic skin grafts destined for rejection demonstrated increased expression of IL-1beta and its receptors compared to K14 HPV16 E7 transgenic grafts that do not reject spontaneously. Rejection of OVA grafts lacking the IL-1 receptor (IL-1R1) was delayed and associated with decreased numbers of antigen-specific CD8 T cells. In contrast, K14E7 grafts survived on immunocompetent, syngeneic recipients with decreased graft levels of IL-1beta and IL-1R1 and 2. However, in the absence of the IL-1 receptor antagonist, IL-1Ra, skin grafts were spontaneously rejected and an E7-specific CD8 T-cell response was primed. Thus, expression of the HPV16E7 oncoprotein in epithelial cells prevents IL-1beta-associated skin graft rejection and induction of antigen-specific CD8 T-cell responses. Enhancing IL-1beta signalling, via blocking of the IL-1 receptor antagonist, may represent an alternative strategy for treatment of HPV16E7-associated cancers.

Myosin II isoforms identify distinct functional modules that support integrity of the epithelial zonula adherens

Classic cadherin receptors cooperate with regulators of the actin cytoskeleton to control tissue organization in health and disease. At the apical junctions of epithelial cells, the cadherin ring of the zonula adherens (ZA) couples with a contiguous ring of actin filaments to support morphogenetic processes such as tissue integration and cellular morphology. However, the molecular mechanisms that coordinate adhesion and cytoskeleton at these junctions are poorly understood. Previously we identified non-muscle myosin II as a target of Rho signalling that supports cadherin junctions in mammalian epithelial cells. Myosin II has various cellular functions, which are increasingly attributable to the specific biophysical properties and regulation of its different isoforms. Here we report that myosin II isoforms have distinct and necessary roles at cadherin junctions. Although two of the three mammalian myosin II isoforms are found at the ZA, their localization is regulated by different upstream signalling pathways. Junctional localization of myosin IIA required E-cadherin adhesion, Rho/ROCK and myosin light-chain kinase, whereas junctional myosin IIB depended on Rap1. Further, these myosin II isoforms support E-cadherin junction integrity by different mechanisms. Myosin IIA RNA-mediated interference (RNAi) selectively perturbed the accumulation of E-cadherin in the apical ZA, decreased cadherin homophilic adhesion and disrupted cadherin clustering. In contrast, myosin IIB RNAi decreased filament content, altered dynamics, and increased the lateral movement of the perijunctional actin ring. Myosin IIA and IIB therefore identify two distinct functional modules, with different upstream signals that control junctional localization, and distinct functional effects. We propose that these two isoform-based modules cooperate to coordinate adhesion receptor and F-actin organization to form apical cadherin junctions.

Cell-cell contact: cooperating clusters of actin and cadherin

Cooperation between cadherins and actin critically influences tissue organization. A new report identifies distinct pools of actin filaments that influence the spatial distribution of cadherins at cell-cell contacts.

E-cadherin adhesion activates c-Src signaling at cell-cell contacts

Cadherin-based cell-cell contacts are prominent sites for phosphotyrosine signaling, being enriched in tyrosine-phosphorylated proteins and tyrosine kinases and phosphatases. The functional interplay between cadherin adhesion and tyrosine kinase signaling, however, is complex and incompletely understood. In this report we tested the hypothesis that cadherin adhesion activates c-Src signaling and sought to assess its impact on cadherin function. We identified c-Src as part of a cadherin-activated cell signaling pathway that is stimulated by ligation of the adhesion receptor. However, c-Src has a biphasic impact on cadherin function, exerting a positive supportive role at lower signal strengths, but inhibiting function at high signal strengths. Inhibiting c-Src under circumstances when it is activated by cadherin adhesion decreased several measures of cadherin function. This suggests that the cadherin-activated c-Src signaling pathway serves positively to support cadherin function. Finally, our data implicate PI3-kinase signaling as a target for cadherin-activated c-Src signaling that contributes to its positive impact on cadherin function. We conclude that E-cadherin signaling is an important activator of c-Src at cell-cell contacts, providing a key input into a signaling pathway where quantitative changes in signal strength may result in qualitative differences in functional outcome.

Tuba stimulates intracellular N-WASP-dependent actin assembly

Tuba is a multidomain scaffolding protein that links cytoskeletal dynamics and membrane trafficking pathways. The N-terminus of Tuba binds dynamin1, and the C-terminus contains domains that can interact with signaling pathways and cytoskeletal regulatory elements. We investigated Tuba localization, distribution and function in B16 melanoma cells. Tuba overexpression stimulated dorsal ruffles that occurred independently of dynamin function. Tuba expression induced actin-driven motility of small puncta that required the C-terminal SH3, GEF and BAR domains. Additionally, Tuba was recruited to lipid vesicles generated by overexpression of phosphatidylinositol-4-phosphate 5-kinase type Ialpha (PIP5Kalpha), localizing prominently to the head of the comets and at lower levels along the actin tail. We propose that Tuba facilitates dorsal ruffling of melanoma cells through direct interaction with actin-regulatory proteins and the recruitment of signaling molecules to lipid microdomains for the coordinated assembly of a cytoskeletal network. Knockdown of Tuba by RNA interference (RNAi) attenuated PIP5Kalpha-generated comet formation and the invasive behavior of B16 cells, implying that Tuba function is required for certain aspects of these processes. These results suggest first that Tuba-stimulated dorsal ruffling might represent a novel mechanism for the coordination of N-WASP-dependent cytoskeletal rearrangements and second that Tuba function is implicated in motility processes.

Myosin 2 is a key Rho kinase target necessary for the local concentration of E-cadherin at cell-cell contacts

Classical cadherins accumulate at cell-cell contacts as a characteristic response to productive adhesive ligation. Such local accumulation of cadherins is a developmentally regulated process that supports cell adhesiveness and cell-cell cohesion. Yet the molecular effectors responsible for cadherin accumulation remain incompletely understood. We now report that Myosin 2 is critical for cells to concentrate E-cadherin at cell-cell contacts. Myosin 2 is found at cadherin-based cell-cell contacts and its recruitment requires E-cadherin activity. Indeed, both Myosin 2 recruitment and its activation were stimulated by E-cadherin homophilic ligation alone. Inhibition of Myosin 2 activity by blebbistatin or ML-7 rapidly impaired the ability of cells to concentrate E-cadherin at adhesive contacts, accompanied by decreased cadherin-based cell adhesiveness. The total surface expression of cadherins was unaffected, suggesting that Myosin 2 principally regulates the regional distribution of cadherins at the cell surface. The recruitment of Myosin 2 to cadherin contacts, and its activation, required Rho kinase; furthermore, inhibition of Rho kinase signaling effectively phenocopied the effects of Myosin 2 inhibition. We propose that Myosin 2 is a key effector of Rho-Rho kinase signaling that regulates cell-cell adhesion by determining the ability of cells to concentrate cadherins at contacts in response to homophilic ligation.

Cortactin is necessary for E-cadherin-mediated contact formation and actin reorganization

Classical cadherin adhesion molecules are key determinants of cell–cell recognition during development and in post-embryonic life. A decisive step in productive cadherin-based recognition is the conversion of nascent adhesions into stable zones of contact. It is increasingly clear that such contact zone extension entails active cooperation between cadherin adhesion and the force-generating capacity of the actin cytoskeleton. Cortactin has recently emerged as an important regulator of actin dynamics in several forms of cell motility. We now report that cortactin is recruited to cell–cell adhesive contacts in response to homophilic cadherin ligation. Notably, cortactin accumulates preferentially, with Arp2/3, at cell margins where adhesive contacts are being extended. Recruitment of cortactin is accompanied by a ligation-dependent biochemical interaction between cortactin and the cadherin adhesive complex. Inhibition of cortactin activity in cells blocked Arp2/3-dependent actin assembly at cadherin adhesive contacts, significantly reduced cadherin adhesive contact zone extension, and perturbed both cell morphology and junctional accumulation of cadherins in polarized epithelia. Together, our findings identify a necessary role for cortactin in the cadherin–actin cooperation that supports productive contact formation.

Minimal mutation of the cytoplasmic tail inhibits the ability of E-cadherin to activate Rac but not phosphatidylinositol 3-kinase: direct evidence of a role for cadherin-activated Rac signaling in adhesion and contact formation

Classic cadherins are adhesion-activated cell signaling receptors. In particular, homophilic cadherin ligation can directly activate Rho family GTPases and phosphatidylinositol 3-kinase (PI3-kinase), signaling molecules with the capacity to support the morphogenetic effects of these adhesion molecules during development and disease. However, the molecular basis for cadherin signaling has not been elucidated, nor is its precise contribution to cadherin function yet understood. One attractive hypothesis is that cadherin-activated signaling participates in stabilizing adhesive contacts (Yap, A. S., and Kovacs, E. M. (2003) J. Cell Biol. 160, 11-16). We now report that minimal mutation of the cadherin cytoplasmic tail to uncouple binding of p120-ctn ablated the ability of E-cadherin to activate Rac. This was accompanied by profound defects in the capacity of cells to establish stable adhesive contacts, defects that were rescued by sustained Rac signaling. These data provide direct evidence for a role of cadherin-activated Rac signaling in contact formation and adhesive stabilization. In contrast, cadherin-activated PI3-kinase signaling was not affected by loss of p120-ctn binding. The molecular requirements for E-cadherin to activate Rac signaling thus appear distinct from those that stimulate PI3-kinase, and we postulate that p120-ctn may play a central role in the E-cadherin-Rac signaling pathway.

Direct cadherin-activated cell signaling: a view from the plasma membrane

Classical cadherin adhesion molecules are key determinants of cell recognition and tissue morphogenesis, with diverse effects on cell behavior. Recent developments indicate that classical cadherins are adhesion-activated signaling receptors. In particular, early-immediate Rac signaling is emerging as a mechanism to coordinate cadherin-actin integration at the plasma membrane.

The web and the rock: cell adhesion and the ARP2/3 complex

Cell locomotion entails functional and structural cooperation between cell surface adhesion and the actin cytoskeleton. A new paper by DeMali et al. provides new insights into the link between actin assembly and integrin adhesion at the leading edges of migrating cells.

Cadherin-directed actin assembly: E-cadherin physically associates with the Arp2/3 complex to direct actin assembly in nascent adhesive contacts

Cadherin cell adhesion molecules are major determinants of tissue patterning which function in cooperation with the actin cytoskeleton. In the context of stable adhesion, cadherin/catenin complexes are often envisaged to passively scaffold onto cortical actin filaments. However, cadherins also form dynamic adhesive contacts during wound healing and morphogenesis. Here actin polymerization has been proposed to drive cell surfaces together, although F-actin reorganization also occurs as cell contacts mature. The interaction between cadherins and actin is therefore likely to depend on the functional state of adhesion. We sought to analyze the relationship between cadherin homophilic binding and cytoskeletal activity during early cadherin adhesive contacts. Dissecting the specific effect of cadherin ligation alone on actin regulation is difficult in native cell-cell contacts, due to the range of juxtacrine signals that can arise when two cell surfaces adhere. We therefore activated homophilic ligation using a specific functional recombinant protein. We report the first evidence that E-cadherin associates with the Arp2/3 complex actin nucleator and demonstrate that cadherin binding can exert an active, instructive influence on cells to mark sites for actin assembly at the cell surface.

E-cadherin homophilic ligation directly signals through Rac and phosphatidylinositol 3-kinase to regulate adhesive contacts

Classical cadherins mediate cell recognition and cohesion in many tissues of the body. It is increasingly apparent that dynamic cadherin contacts play key roles during morphogenesis and that a range of cell signals are activated as cells form contacts with one another. It has been difficult, however, to determine whether these signals represent direct downstream consequences of cadherin ligation or are juxtacrine signals that are activated when cadherin adhesion brings cell surfaces together but are not direct downstream targets of cadherin signaling. In this study, we used a functional cadherin ligand (hE/Fc) to directly test whether E-cadherin ligation regulates phosphatidylinositol 3-kinase (PI 3-kinase) and Rac signaling. We report that homophilic cadherin ligation recruits Rac to nascent adhesive contacts and specifically stimulates Rac signaling. Adhesion to hE/Fc also recruits PI 3-kinase to the cadherin complex, leading to the production of phosphatidylinositol 3,4,5-trisphosphate in nascent cadherin contacts. Rac activation involved an early phase, which was PI 3-kinase-independent, and a later amplification phase, which was inhibited by wortmannin. PI 3-kinase and Rac activity were necessary for productive adhesive contacts to form following initial homophilic ligation. We conclude that E-cadherin is a cellular receptor that is activated upon homophilic ligation to signal through PI 3-kinase and Rac. We propose that a key function of these cadherin-activated signals is to control adhesive contacts, probably via regulation of the actin cytoskeleton, which ultimately serves to mediate adhesive cell-cell recognition.

Effects of 2-week ingestion of (-)-hydroxycitrate and (-)-hydroxycitrate combined with medium-chain triglycerides on satiety and food intake

The aim of this study was to assess the effects of 2 weeks of supplementation with (-)-hydroxycitrate (HCA) and HCA combined with medium-chain triglycerides (MCT) on satiety and energy intake. The experimental design consisted of three intervention periods of 2 weeks separated by washout periods of 2 or 6 weeks in a double-blind, placebo-controlled, randomized, and crossover design. Seven male and 14 female normal to moderately obese subjects (mean+/-S.D.; age, 43+/-10 years; body mass index, 27.6+/-2.0 kg/m(2)) participated in this study. Subjects consumed three self-selected meals and four isoenergetic snacks daily with either no supplementation (PLA), with 500 mg HCA (HCA), or 500 mg HCA and 3 g MCT (HCA+MCT). Each intervention period ended with a test day, consisting of a standardized breakfast and ad libitum a lunch and a dinner. There was a significant body weight (BW) loss during the 2 weeks of intervention (PLA, -0.5+/-0.3 kg, P<.05; HCA, -0.4+/-0.2 kg, P<.05; HCA+MCT, -0.7+/-0.2 kg, P<.01), but this reduction was not different between treatments. Twenty-four-hour energy intake (PLA, 8.1+/-0.3 MJ; HCA, 8.3+/-0.3 MJ; HCA+MCT, 8.4+/-0.3 MJ) and the area under the curve of the appetite-related parameters during the test day were similar for all treatments. Two weeks of supplementation with HCA and HCA combined with MCT did not result in increased satiety or decreased energy intake compared to placebo in subjects losing BW.

The effects of 2-week ingestion of (--)-hydroxycitrate and (--)-hydroxycitrate combined with medium-chain triglycerides on satiety, fat oxidation, energy expenditure and body weight

OBJECTIVE

Assessment of the effect of 2-week supplementation with (--)-hydroxycitrate (HCA) and HCA combined with medium-chain triglycerides (MCT) on satiety, fat oxidation, energy expenditure (EE) and body weight (BW) loss.

DESIGN

Three intervention periods of 2 weeks separated by washout periods of 4 weeks. Double-blind, placebo-controlled, randomised and cross-over design.

SUBJECTS

Eleven overweight male subjects (mean+/-s.d.; age, 47+/-16 y; body mass index, 27.4 +/- 8.2 kg/m(2)).

INTERVENTION

Subjects consumed three self-selected meals and four iso-energetic (420 kJ) snacks daily with either no supplementation (PLA), 500 mg HCA (HCA) or 500 mg HCA and 3 g MCT (HCA+MCT). Each intervention ended with a 36 h stay in the respiration chamber.

RESULTS

There was a significant BW loss during the 2 weeks of intervention (PLA, -1.0 +/- 0.4 kg, P<0.05; HCA, -1.5 +/- 0.5 kg, P<0.01; HCA+MCT, -1.3 +/- 0.2 kg, P<0.001), but this reduction was not different between treatments. 24 h EE (PLA, 11.8 +/- 0.2 MJ; HCA, 11.7 +/- 0.1 MJ; HCA+MCT, 11.5 +/- 0.1 MJ), 24 h RQ (0.85 +/- 0.00 in all treatments) and the area under the curve of the appetite-related parameters were not different between treatments.

CONCLUSION

Two-week supplementation with HCA and HCA combined with MCT did not result in increased satiety, fat oxidation, 24 h EE or BW loss compared to PLA, in subjects losing BW.

The effect of addition of modified guar gum to a low-energy semisolid meal on appetite and body weight loss

OBJECTIVE

To investigate the effect of addition of modified guar gum (GG) to a low-energy semisolid meal on appetite and body weight (BW) loss.

SUBJECTS

Twenty eight mainly overweight male volunteers (age, 19-56 y; body mass index, 29+/-2 kg x m(-2); BW, 89.4+/-9.2 kg).

DESIGN

Baseline of one week with self-selected diet. Three treatments of 2 weeks with a low-energy diet divided over three times a day, consisting of a semisolid meal with (SSM+) or without GG (SSM) or a solid meal (SM) with the same energy content (947 kJ) and macronutrient composition, and a dinner of the subject's own choice. Washout periods lasted 4 weeks.

RESULTS

Compared to baseline values, reduction in energy intake and BW loss were similar for SSM+, SSM and SM. Appetite (hunger, desire to eat or estimation of how much one could eat) was increased in SSM and in SM compared to baseline, but not in SSM+. Satiety and fullness in SSM+, SSM and SM were similar to baseline. Any intervention was more effective on BW loss when it took place the first time compared to the second and third times (2.6+/-0.2 kg, 1.7+/-0.2 kg and 1.1+/-0.2 kg, respectively; P<0.001). The SM-SSM+-SSM sequence was more effective on BW loss compared to the SSM+-SSM-SM sequence (5.6+/-1.0 and 2.5+/-0.6 kg, respectively; P<0.05).

CONCLUSION

All the three treatments were equally effective with respect to BW loss. GG addition to a semisolid meal prevented an increase in appetite, hunger and desire to eat, which increase was present in the other treatments. However, differences between treatments were not statistically significant. The order effect shows that repeated 2-week bouts of dieting become increasingly ineffective. The sequence SM-SSM+-SSM was more effective than the sequence SSM+-SSM-SM, probably because compliance was relatively higher with the SSM+ or SSM diet, and compliance decreased towards the end of the complete experiment.

The effect of different dosages of guar gum on gastric emptying and small intestinal transit of a consumed semisolid meal

BACKGROUND

There is no consensus about the effect of guar gum supplementation on gastrointestinal transit. It has been suggested that guar gum slows gastric emptying and intestinal transit, thus inducing an increased feeling of satiety.

OBJECTIVE

To investigate whether addition of guar gum to a semisolid meal affects gastrointestinal transit.

DESIGN

Eight male subjects were randomly studied four times. They consumed a standard semisolid test meal containing either 0 g, 2.5 g, 3.5 g, or 4.5 g of guar gum. The test meals contained 1 mCi 99mTc-hepatate for scintigraphy and 5 g lactulose for the H2-breath test. Scintigraphic scanning was performed for at least two hours, and gastric half-emptying time (T1/2) was calculated. Breath samples were collected at 15 minute intervals and analyzed for H2-enrichment. The orocecal transit time (OCTT) was then determined. A parameter of intestinal transit (PIT) was obtained by subtracting the T1/2 from the OCTT.

RESULTS

There were no significant differences (in minutes) between the different tests in both T1/2 (0 g, t = 88.2 +/- 11, 2.5 g, t = 83.3 +/- 11.9, 3.5 g, t = 83.3 +/- 13.6, 4.5 g, t = 72.4 +/- 7.2, p = 0.86) and PIT (0 g, t = 149.9 +/- 26.6, 2.5 g, t = 145.5 +/- 25.6, t = 3.5 g, t = 175.3 +/- 17.6, t = 4.5 g, t = 152.6 +/- 22.4, p = 0.52).

CONCLUSION

Addition of guar gum to a semisolid meal up to a dosage of 4.5 g does not affect gastrointestinal transit. Other mechanisms than gastrointestinal motility are involved in a possible satiating effect of guar gum supplementation.

Feline peripheral blood mononuclear cells express message for both CXC and CC type chemokine receptors

The feline immunodeficiency virus (FIV) causes a disease in cats similar in clinical presentation and disease progression to that of HIV and AIDS. It is now known that, for HIV infection, as well as primary binding of virus to the CD4 receptor, entry and infection of cells requires coreceptors which are members of the chemokine group of G-protein coupled receptors. Because of the similarity of HIV and FIV, we hypothesised that coreceptors are required for the entry and infection of cells by FIV. Using a feline cDNA library derived from a feline IL-2 sensitive lymphocyte cell line, we identified the presence of message for both CC and CXC chemokine receptors. The feline CXCR4 has been shown to facilitate fusion by FIV [44] and we suggest that the feline CCR5 receptor mediates infection of feline cells by M-tropic strains of FIV.

Measurement of Plasma Renin Activity with Use of HPLC-Electrospray-Tandem Mass Spectrometry

Background: The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA).

Methods: After incubation (37 °C for 3 or 18 h), samples were prepared using C18 solid-phase extraction. [Val]5Ang1 was used as the internal standard (IS). Chromatography was performed on a C18 column, using 200 mL/L ammonium acetate buffer–800 mL/L methanol as the mobile phase. The flow rate was 150 μL/min, with a chromatographic run time of 5 min/sample. Mass spectrometric detection was in the positive ionization mode with selected reaction monitoring (Ang1 m/z 649.0→784.0; IS m/z 641.9→770.4).

Results: The assay was linear over the range 2.5–500 ng Ang1/mL, which corresponded to a limit of detection (signal-to-noise ratio of 3:1) of PRA of 0.14 ng Ang1 · mL−1 · h−1. The imprecision (CV) of the assay at PRA values of 26.1, 13.5, 3.2, and 0.78 ng Ang1 · mL−1 · h−1 was 7.0%, 7.0%, 15%, and 11%, respectively. Absolute recoveries were 92.3% (Ang1) and 87.4% (IS). Incubation times of 3 h vs 18 h in the PRA assay gave good agreement at PRA &lt;2 ng Ang1 · mL−1 · h−1, but samples with a PRA of 2–5 ng Ang1 · mL−1 · h−1 gave lower PRA results after incubation for 18 h than after 3 h. We compared the HPLC-ESI-MS/MS assay and an RIA for the determination of PRA, with PRA incubation times of 3 h and 1.5 h, respectively. The mean PRA based on RIA of Ang1 was higher than that obtained using HPLC-ESI-MS/MS.

Conclusion: The HPLC-ESI-MS/MS method allows sensitive and specific measurement of PRA. The higher activities measured with the RIA method highlight its potential for overestimation of PRA.

Measurement of plasma renin activity with use of HPLC-electrospray-tandem mass spectrometry

BACKGROUND

The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA).

METHODS

After incubation (37 degrees C for 3 or 18 h), samples were prepared using C18 solid-phase extraction. [Val]5Ang1 was used as the internal standard (IS). Chromatography was performed on a C18 column, using 200 mL/L ammonium acetate buffer-800 mL/L methanol as the mobile phase. The flow rate was 150 microL/min, with a chromatographic run time of 5 min/sample. Mass spectrometric detection was in the positive ionization mode with selected reaction monitoring (Ang1 m/z 649.0-->784.0; IS m/z 641.9-->770.4).

RESULTS

The assay was linear over the range 2.5-500 ng Ang1/mL, which corresponded to a limit of detection (signal-to-noise ratio of 3:1) of PRA of 0.14 ng Ang1. mL-1. h-1. The imprecision (CV) of the assay at PRA values of 26.1, 13.5, 3.2, and 0.78 ng Ang1. mL-1. h-1 was 7.0%, 7.0%, 15%, and 11%, respectively. Absolute recoveries were 92.3% (Ang1) and 87.4% (IS). Incubation times of 3 h vs 18 h in the PRA assay gave good agreement at PRA <2 ng Ang1. mL-1. h-1, but samples with a PRA of 2-5 ng Ang1. mL-1. h-1 gave lower PRA results after incubation for 18 h than after 3 h. We compared the HPLC-ESI-MS/MS assay and an RIA for the determination of PRA, with PRA incubation times of 3 h and 1.5 h, respectively. The mean PRA based on RIA of Ang1 was higher than that obtained using HPLC-ESI-MS/MS.

CONCLUSION

The HPLC-ESI-MS/MS method allows sensitive and specific measurement of PRA. The higher activities measured with the RIA method highlight its potential for overestimation of PRA.

Urine color, osmolality and specific electrical conductance are not accurate measures of hydration status during postexercise rehydration

BACKGROUND

The aim of the study was to determine whether urine color, osmolality and specific electrical conductance (SEC) provide an accurate index of hydration status and of fluid requirements during the recovery phase after an acute exercise-induced dehydration.

METHODS

EXPERIMENTAL DESIGN

eight well-trained healthy males were dehydrated about 3% of body mass, 3 times, by cycling in the heat. To rehydrate after exercise, three types of drinks frequently consumed by athletes postexercise, i.e. a caffeinated soft drink (CC), a mineral water (MW), or a carbohydrate-electrolyte solution (CES) were ingested ad libitum and in randomized cross-over design during the first 2 hrs of an observation period lasting 6 hrs.

MEASURES

urine was sampled each hour for determination of color, osmolality and SEC. Net rehydration was calculated from fluid intake and fluid loss by sweat and urine.

RESULTS

Fluid intake amounted 2.6 +/- 0.2 kg for CC, 2.2 +/- 0.2 kg for MW and 2.8 +/- 0.3 kg for CES representing 116%, 96% and 127% of fluid lost by sweat. Urine output showed a negative correlation with color, osmolality and SEC (p < 0.001). These variables were highly interrelated (p < 0.001). However, the level of rehydration did not correlate with any of the measured urinary variables (p > 0.05).

CONCLUSIONS

Urine color, SEC and osmolality are poor indicators of hydration status measured from the balance between fluid intake and urine output up to 6 hrs postexercise.

Effect of caffeinated drinks on substrate metabolism, caffeine excretion, and performance

The effect of addition of different dosages of caffeine (Caf) to a carbohydrate-electrolyte solution (CES) on metabolism, Caf excretion, and performance was examined. Subjects (n = 15) ingested 8 ml/kg of water placebo (Pla-W), 7% CES (Pla-CES), or 7% CES with 150, 225, and 320 mg/l Caf (CES-150, CES-225, and CES-320, respectively) during a warm-up protocol (20 min) and 3 ml/kg at one-third and two-thirds of a 1-h time trial. Performance was improved with Caf supplementation: 62.5 +/- 1.3, 61.5 +/- 1.1, 60.4 +/- 1.0, 58.9 +/- 1.0, and 58.9 +/- 1.2 min for Pla-W, Pla-CES, CES-150, CES-225, and CES-320, respectively. The postexercise urinary Caf concentration (range 1.3-2.5 microg/ml) was dose dependent and always far below the doping level of the International Olympic Committee (12 microg/ml) in all subjects. Sweat Caf excretion during exercise exceeded postexercise early-void urinary Caf excretion. Caffeinated CES did not enhance free fatty acid availability, ruling out the fact that performance improvement resulted from enhanced fat oxidation. It is concluded that addition of relatively low amounts of Caf to CES improves performance and that postexercise urinary Caf concentration remained low.

The effect of different rehydration drinks on post-exercise electrolyte excretion in trained athletes

Eight well-trained cyclists were dehydrated (median [P25-P75 percentiles]) 3.21 [2.97-3.56]% of body mass by cycling in the heat (28 C). During the first 2 h of recovery, the subjects randomly ingested ad libitum either a caffeinated soft drink (CC), a low Na+ mineral water (MW), or an isotonic carbohydrate-electrolyte solution (CES). Fluid intake and urine loss amounted respectively to 2.77 [2.34-2.85] kg, 1.00 [0.82-1.20] kg for CC, 2.15 [1.86-2.79] kg, 0.96 [0.40-1.49] kg for MW, and 2.86 [2.15-3.58] kg, 1.10 [0.86- 1.50] kg for CES. Electrolyte retention was calculated from electrolyte intake with the drink and loss with the urine. Consumption of CC and MW which were low in electrolytes resulted in marked loss of Na+, K+, Cl-, Mg2+ and Ca2+. Consumption of CES resulted in Na+, Mg2+ and Ca2+ retention while K+ and Cl- loss were not influenced. The significantly lower Na+, Mg2+ and Ca2+ loss with CES compared to both CC and MW may be explained by its higher electrolyte content in CES, compared to CC and MW, which only had minor amounts of these electrolytes. Furthermore, it was shown that CC potentiated urinary Mg2+ and Ca2+ excretion. It is concluded that: 1) Post-exercise MW or CC ingestion results in a negative electrolyte balance, 2) Caffeine containing beverages potentiate Mg2+ and Ca2+ excretion; 3) Consumption of CES containing moderate amounts of Na+, Mg2+ and Ca2+ results in sufficient replacement to compensate for urinary losses.

Inhibition of apoptosis in human tumour cells by okadaic acid

Gamma-radiation, tetrandrine, bistratene A, and cisplatin were all found to induce pronounced morphological changes characteristic of apoptosis and extensive DNA fragmentation in the human BM13674 cell line 8 h after treatment. Apoptosis induced in BM13674 cells by these diverse agents was markedly inhibited by 1 microM okadaic acid, a tumour promoter that inhibits protein phosphatases 1 and 2A. This compound also inhibited the appearance of apoptosis in fresh human leukaemia cells that had been exposed to gamma-radiation. The inhibition of apoptosis was confirmed using fluorescence microscopy and DNA gel electrophoresis. Dephosphorylation of a limited number of proteins was shown to be associated with apoptosis and okadaic acid prevented these dephosphorylations. Previous studies on the BM13674 cell line showed that an inhibitor of protein synthesis failed to prevent apoptosis in these cells. The present data provides further support that posttranslational modification of proteins, in particular, phosphorylation/dephosphorylation status, plays an important role in inhibition/activation of programmed cell death in different human cells after exposure to several cytotoxic agents.

Cellular processes in atherogenesis: potential targets of Ca2+ channel blockers

Atherosclerosis is characterized by increased endothelial permeability, monocyte infiltration, intimal smooth muscle cell (SMC) proliferation, platelet aggregation and the accumulation of lipids, calcium and extracellular matrix components in the vessel wall. In various animal studies and recently in humans it could be established that Ca2+ channel blockers delayed the progression of the atherosclerotic process at the stage of early lesions. This review surveys the interaction of Ca2+ channel blockers with various membrane proteins (purinergic receptors, nucleoside transporter, peripheral benzodiazepine receptors, multi-drug resistance protein) which are involved in signal transduction and their potential impact on the observed antiatherosclerotic effects. Although the precise mechanisms have yet to be fully elucidated, it has been clearly shown that these drugs inhibit smooth muscle cell proliferation and migration, improve cellular lipoprotein metabolism in vascular cells, alter phospholipid turnover, decrease platelet adhesion in the vessel wall, reduce extracellular matrix synthesis and protect against radical induced cell damage. Most of these effects are independent of Ca2+ flux across voltage-operated Ca2+ channels. However, all these processes are relevant to the pathogenesis of atherosclerosis and therefore the elucidation of the antiatherogenic mechanisms of Ca2+ channel blockers at the cellular level is of great interest. The future development of Ca2+ channel blockers with altered molecular structures optimized for their antiatherosclerotic targets may provide a useful tool in the therapy of atherosclerosis and risk factor intervention. The protective mechanisms are related to a stabilization of cell membrane integrity, the modulation of secretory activities and cell/cell communication processes rather than to a lowering of plasma lipoprotein levels.

The possible role of histamine in the coritsone induced gastric acid hypersecretion of the guinea-pig

1. The effects of cortisone treatment combined with agents influencing histamine metabolism were studied on the free and total acid output in pylorus ligated guinea-pigs.2. It was found that reduction in the synthesis of histamine produced by the administration of alpha-methylDOPA significantly inhibited the acid response to cortisone.3. Enhancement of the oxidative deamination of histamine brought about by the administration of diamine oxidase or heparin inhibited cortisone induced acid hypersecretion significantly.4. Inhibition of the oxidative deamination of histamine by aminoguanidine and iproniazid resulted in a significant increase of the cortisone induced acid hypersecretory response.5. Inhibition of the methylation of histamine by chlorpromazine or 1,4-methylhistamine inhibited the cortisone induced hypersecretory response significantly.6. Studies with labelled histamine indicated that cortisone increases the sequestration of histamine to the stomach.