The Hemagglutinin of Bat-Associated Influenza Viruses Is Activated by TMPRSS2 for pH-Dependent Entry into Bat but Not Human Cells

New World bats have recently been discovered to harbor influenza A virus (FLUAV)-related viruses, termed bat-associated influenza A-like viruses (batFLUAV). The internal proteins of batFLUAV are functional in mammalian cells. In contrast, no biological functionality could be demonstrated for the surface proteins, hemagglutinin (HA)-like (HAL) and neuraminidase (NA)-like (NAL), and these proteins need to be replaced by their human counterparts to allow spread of batFLUAV in human cells. Here, we employed rhabdoviral vectors to study the role of HAL and NAL in viral entry. Vectors pseudotyped with batFLUAV-HAL and -NAL were able to enter bat cells but not cells from other mammalian species. Host cell entry was mediated by HAL and was dependent on prior proteolytic activation of HAL and endosomal low pH. In contrast, sialic acids were dispensable for HAL-driven entry. Finally, the type II transmembrane serine protease TMPRSS2 was able to activate HAL for cell entry indicating that batFLUAV can utilize human proteases for HAL activation. Collectively, these results identify viral and cellular factors governing host cell entry driven by batFLUAV surface proteins. They suggest that the absence of a functional receptor precludes entry of batFLUAV into human cells while other prerequisites for entry, HAL activation and protonation, are met in target cells of human origin.     

Acute phase response to recombinant interleukin-6 and macrophage- and fibroblast-derived crude cytokine preparations in primary cultures of mouse hepatocytes

A number of acute phase proteins were determined by electroimmunoassay in media from CBA mouse hepatocytes cultured for 2 days with human recombinant IFN beta 2/IL-6, as well as with conditioned media from LPS-stimulated rat macrophages, and of murine L fibroblasts. It was found that human recombinant IL-6 caused three-fold increase in secretion of fibrinogen, while haptoglobin, complement C3 and transferrin were increased respectively, to 168 per cent, 151 per cent, and 145 per cent of the control. DEX(10(-7) M) in DMEM supplemented with 5 per cent FCS, enhanced the IL-6 effect on the three positive acute phase proteins. IL-6 elevated haptoglobin mRNA in mouse hepatocytes to a degree comparable with the concentration of the protein in the culture medium. The effect of conditioned media from murine fibroblasts and peritoneal rat macrophages was generally similar to that of recombinant IL-6. However, both natural preparations of the cytokines caused decrease in albumin and alpha-1-proteinase inhibitor secretion.     

ADP-Ribosylation of Brain Neuronal Proteins Is Altered by In Vitro and In Vivo Exposure to Inorganic Mercury

Abstract: ADP-ribosylation is an essential process in the metabolism of brain neuronal proteins, including the regulation of assembly and disassembly of biological polymers. Here, we examine the effect of HgCl₂ exposure on the ADP-ribosylation of tubulin and actin, both cytoskeletal proteins also found in neurons, and B-50/43-kDa growth-associated protein (B-50/GAP-43), a neuronal tissue-specific phosphoprotein. In rats we demonstrate, with both in vitro and in vivo experiments, that HgCl₂ markedly inhibits the ADP-ribosylation of tubulin and actin. This is direct quantitative evidence that HgCl₂, a toxic xenobiotic, alters specific neurochemical reactions involved in maintaining brain neuron structure.     

The Ontogeny of Vocal Sequences: Insights from a Newborn Wild Chimpanzee (Pan troglodytes schweinfurthii)

International Journal of Primatology - Observations of early vocal behaviours in non-human primates (hereafter primates) are important for direct comparisons between human and primate vocal...     

Association of chest wall motion and tidal volume responses during CO2 rebreathing

Yan, Sheng, Pawel Sliwinski, and Peter T. Macklem.Association of chest wall motion and tidal volume responses during CO₂ rebreathing.J. Appl. Physiol. 81(4):1528-1534, 1996.The purpose of this study is to investigate theeffect of chest wall configuration at end expiration on tidal volume(VT) response duringCO₂ rebreathing. In a group of 11 healthy male subjects, the changes in end-expiratory andend-inspiratory volume of the rib cage (Vrc,E andVrc,I, respectively) and abdomen (Vab,E and Vab,I, respectively) measured by linearizedmagnetometers were expressed as a function of end-tidalPCO₂(PET_CO2). The changes inend-expiratory and end-inspiratory volumes of the chest wall(Vcw,E and Vcw,I,respectively) were calculated as the sum of the respectiverib cage and abdominal volumes. The magnetometer coils were placed atthe level of the nipples and 1-2 cm above the umbilicus andcalibrated during quiet breathing against theVT measured from apneumotachograph. TheVrc,E/PET_CO2 slope was quite variable among subjects. It was significantly positive (P < 0.05) in fivesubjects, significantly negative in four subjects(P < 0.05), and not different fromzero in the remaining two subjects. TheVab,E/PET_CO2slope was significantly negative in all subjects(P < 0.05) with a much smallerintersubject variation, probably suggesting a relatively more uniformrecruitment of abdominal expiratory muscles and a variable recruitmentof rib cage muscles during CO₂rebreathing in different subjects. As a group, the meanVrc,E/PET_CO2,Vab,E/PET_CO2, andVcw,E/PET_CO2slopes were 0.010 ± 0.034, 0.030 ± 0.007, and0.020 ± 0.032 l / Torr, respectively;only theVab,E/PET_CO2 slope was significantly different from zero. More interestingly, theindividualVT/PET_CO2slope was negatively associated with theVrc,E/PET_CO2(r = 0.68,P = 0.021) and Vcw,E/PET_CO2slopes (r = 0.63,P = 0.037) but was not associated withtheVab,E/PET_CO2slope (r = 0.40, P = 0.223). There was no correlation oftheVrc,E/PET_CO2 andVcw,E/PET_CO2slopes with age, body size, forced expiratory volume in 1 s, orexpiratory time. The groupVab,I/PET_CO2 slope (0.004 ± 0.014 l / Torr) was not significantlydifferent from zero despite theVT nearly being tripled at theend of CO₂ rebreathing. Inconclusion, the individual VTresponse to CO₂, althoughindependent of Vab,E, is a function ofVrc,E to the extent that as theVrc,E/PET_CO2slope increases (more positive) among subjects, theVT response toCO₂ decreases. These results maybe explained on the basis of the respiratory muscle actions andinteractions on the rib cage.

     

Glycoforms of serum α1-acid glycoprotein as markers of inflammation and cancer

1-acid glycoprotein (AGP) is a serum acute phase glycoprotein which possesses five N-linked complex type heteroglycan side chains which may be present as bi-, tri- and tetraantennary structures. Depending upon the content of biantennary structure on AGP, up to four glycoforms of AGP are present in serum. These glycoforms can be easily estimated in body fluids by means of crossed affinity-immunoelectrophoresis (CAIE) with the lectin, Concanavalin A (Con A). Con A selectively binds biantennary structures; the more biantennary structures on AGP, the stronger the binding. In acute inflammation, a relative increase of AGP glycoforms with biantennary units is observed - a type I glycosylation change. In some chronic inflammatory states there is an relative decrease of AGP glycoforms with biantennary heteroglycans — a type II glycosylation change. Moreover, in certain other states such as pregnancy, estrogen administration or liver damage, type II glycosylation changes are also seen. A detailed analysis of the clinical applications of the assessment of AGP glycoforms in sera of patients with rheumatic diseases, AIDS and various types of cancers is presented. Accumulated data shows that AGP glycoforms may be very useful in the detection of intercurrent infections in the course of rheumatoid arthritis, systemic lupus erythematosus, or myeloblastic leukaemia, and in the detection of secondary infections in human immunodeficiency virus infected individuals. AGP glycoforms are also very useful in differentiation between various forms of trophoblastic disease and are helpful in monitoring the treatment of these patients. Finally, AGP glycoforms provide valuable information for differentiation between primary and secondary liver cancer.     

Monocyte-produced prostaglandin induces Fcγ receptor expression on human T cells

Incubation of human T cells for 18 hr with prostaglandin E₂ (PGE₂ 3 × 10^?6M) causes a slight but significant increase in the percentage of Tγ cells and a reduction in Tμ cells. When PGE was added to “non-Tγ” cells, the increase in the percentage of Tγ cells was more marked (from 1.5% Tγ without PGE to 11% Tγ with PGE₂, P < 0.001). Supernates from cultures of human monocytes also caused an increase in Tγ cells (10% Tγ without supernate to 18% with supernate, P < 0.01), and this increase was blocked if the monocytes were cultured with indomethacin, a prostaglandin synthetase inhibitor (9% Tγ cells). Thus, monocytes may regulate Fcγ receptors on T cells via PGE₂ production.     

Effects of cytokine combinations on acute phase protein production in two human hepatoma cell lines.

We evaluated the effects of binary combinations of four cytokines on production of the positive acute phase proteins alpha-1 antichymotrypsin, haptoglobin and fibrinogen, and the negative acute phase proteins albumin and alpha-fetoprotein (AFP) in two human hepatoma cell lines. The effects of the cytokine combinations on the five proteins varied; each protein exhibited a unique and specific pattern of response to the cytokine combinations. In Hep G2 cells, antichymotrypsin was induced by all four cytokines, IL-6, IL-1, TNF-alpha, and transforming growth factor beta 1 alone, and their effects in binary combinations could be attributed to additive or minimally synergistic interactions. Fibrinogen was induced only by IL-6 and this induction was inhibited by IL-1 alpha, TNF-alpha or transforming growth factor beta 1. Haptoglobin was also induced only by IL-6, but TNF-alpha was the only cytokine that inhibited this induction at all concentrations of IL-6. Each of the four cytokines alone down regulated production of AFP and albumin. However, binary combinations of the four cytokines were simply additive, for the most part, in inhibiting AFP production, whereas the inhibitory effects of combinations of cytokines on albumin production differed significantly from simple additive effects. These observations, taken together with studies of effects of cytokine combinations on other acute phase proteins, indicate that the various acute phase proteins respond differently to different combinations of cytokines and that the potential exists for highly specific regulation of synthesis of individual plasma proteins by cytokine interactions. These findings imply that the acute phase response in vivo represents the integrated sum of multiple, separately regulated changes in gene expression.