Fatal outcome of human influenza A (H5N1) is associated with high viral load and hypercytokinemia

Avian influenza A (H5N1) viruses cause severe disease in humans, but the basis for their virulence remains unclear. In vitro and animal studies indicate that high and disseminated viral replication is important for disease pathogenesis. Laboratory experiments suggest that virus-induced cytokine dysregulation may contribute to disease severity. To assess the relevance of these findings for human disease, we performed virological and immunological studies in 18 individuals with H5N1 and 8 individuals infected with human influenza virus subtypes. Influenza H5N1 infection in humans is characterized by high pharyngeal virus loads and frequent detection of viral RNA in rectum and blood. Viral RNA in blood was present only in fatal H5N1 cases and was associated with higher pharyngeal viral loads. We observed low peripheral blood T-lymphocyte counts and high chemokine and cytokine levels in H5N1-infected individuals, particularly in those who died, and these correlated with pharyngeal viral loads. Genetic characterization of H5N1 viruses revealed mutations in the viral polymerase complex associated with mammalian adaptation and virulence. Our observations indicate that high viral load, and the resulting intense inflammatory responses, are central to influenza H5N1 pathogenesis. The focus of clinical management should be on preventing this intense cytokine response, by early diagnosis and effective antiviral treatment.     

Blood flow augmentation by intrinsic venular contraction in vivo

Venomotion, spontaneous cyclic contractions of venules, was first observed in the bat wing 160 years ago. Of all the functional roles proposed since then, propulsion of blood by venomotion remains the most controversial. Common animal models that require anesthesia and surgery have failed to provide evidence for venular pumping of blood. To determine whether venomotion actively pumps blood in a minimally invasive, unanesthetized animal model, we reintroduced the batwing model. We evaluated the temporal and functional relationship between the venous contraction cycle and blood flow and luminal pressure. Furthermore, we determined the effect of inhibiting venomotion on blood flow. We found that the active venous contractions produced an increase in the blood flow and exhibited temporal vessel diameter-blood velocity and pressure relationships characteristic of a peristaltic pump. The presence of valves, a characteristic of reciprocating pumps, enhances the efficiency of the venular peristaltic pump by preventing retrograde flow. Instead of increasing blood flow by decreasing passive resistance, venular dilation with locally applied sodium nitroprusside decreased blood flow. Taken together, these observations provide evidence for active venular pumping of blood. Although strong venomotion may be unique to bats, venomotion has also been inferred from venous pressure oscillations in other animal models. The conventional paradigm of microvascular pressure and flow regulation assumes venules only act as passive resistors, a proposition that must be reevaluated in the presence of significant venomotion.     

Non-closure of peritoneum after abdominal hysterectomy for uterine carcinoma does not increase late intestinal radiation morbidity

Background/AimTo evaluate whether non-closure of the visceral peritoneum after total abdominal hysterectomy (TAH) and bilateral salpingo-oophorectomy (BSO) in patients with uterine corpus carcinoma influences the volume of the small intestine within the irradiated volume during adjuvant radiotherapy or late radiation intestinal toxicity.Materials and methodsA total of 152 patients after TAH + BSO with adjuvant pelvic radiotherapy were studied. The state of peritonealization was retrospectively evaluated based on surgical protocols. The volume of irradiated bowels was calculated by CT-based delineation in a radiotherapy planning system. The influence of visceral peritonealization upon the volume of the small intestine within the irradiated volume and consequent late morbidity was analyzed.ResultsVisceral peritonealization was not performed in 70 (46%) of 152 studied patients. The state of peritonealization did not affect the volume of the irradiated small intestine (p = 0.14). Mean volume of bowels irradiated in patients with peritonealization was 488 cm³ (range 200–840 cm³, median 469 cm³); mean volume of bowels irradiated in patients without peritonealization was 456 cm³ (range 254–869 cm³, median 428 cm³). We did not prove any significant difference between both arms. Nor did we observe any influence of non-peritonealization upon late intestinal morbidity (p = 0.34).ConclusionNon-closure of the visceral peritoneum after hysterectomy for uterine corpus carcinoma does not increase the volume of the small intestine within the irradiated volume, with no consequent intestinal morbidity enhancement.     

Association of mast cell-derived VEGF and proteases in Dengue shock syndrome

Background

Recent in-vitro studies have suggested that mast cells are involved in Dengue virus infection. To clarify the role of mast cells in the development of clinical Dengue fever, we compared the plasma levels of several mast cell-derived mediators (vascular endothelial cell growth factor [VEGF], soluble VEGF receptors [sVEGFRs], tryptase, and chymase) and -related cytokines (IL-4, -9, and -17) between patients with differing severity of Dengue fever and healthy controls.

Methodology/Principal Findings

The study was performed at Children''s Hospital No. 2, Ho Chi Minh City, and Vinh Long Province Hospital, Vietnam from 2002 to 2005. Study patients included 103 with Dengue fever (DF), Dengue hemorrhagic fever (DHF), and Dengue shock syndrome (DSS), as diagnosed by the World Health Organization criteria. There were 189 healthy subjects, and 19 febrile illness patients of the same Kinh ethnicity. The levels of mast cell-derived mediators and -related cytokines in plasma were measured by ELISA. VEGF and sVEGFR-1 levels were significantly increased in DHF and DSS compared with those of DF and controls, whereas sVEGFR-2 levels were significantly decreased in DHF and DSS. Significant increases in tryptase and chymase levels, which were accompanied by high IL-9 and -17 concentrations, were detected in DHF and DSS patients. By day 4 of admission, VEGF, sVEGFRs, and proteases levels had returned to similar levels as DF and controls. In-vitro VEGF production by mast cells was examined in KU812 and HMC-1 cells, and was found to be highest when the cells were inoculated with Dengue virus and human Dengue virus-immune serum in the presence of IL-9.

Conclusions

As mast cells are an important source of VEGF, tryptase, and chymase, our findings suggest that mast cell activation and mast cell-derived mediators participate in the development of DHF. The two proteases, particularly chymase, might serve as good predictive markers of Dengue disease severity.     

Fine structural localization of alkaloid synthesis in endoplasmic reticulum of submergedClaviceps purpurea

Cyanide-insensitive mitochondria from Saccharomycopsis lipolytica possess an exogenous NADH dehydrogenase, located outside the inner mitochondrial membrane, and linked to coupling site II. These mitochondria are able to oxidize exogenous NADH via two pathways: (1) a cyanide- and antimycin-sensitive pathway, or cytochrome pathway, and (2) a cyanide- and antimycin-insensitive pathway, or alternative pathway. Although the oxidation of exogenous NADH through the cytochrome pathway occurs with an ATP/0 ratio tending to 2, it proceeds, per molecule of NADH oxidized, with the apparent ejection in the outer medium of only 3 protons instead of 4 protons, as is the case with glycerol 3-phosphate as control substrate, but leaves 1 hydroxyl ion in the outer medium after decay of the protonmotive force. These properties were used to demonstrate the non electrogenic function of the alternative pathway. Indeed, the oxidation of exogenous NADH via the alternative pathway proceeds without apparent ejection of protons, although this oxidation generates an electron flux in the alternative pathway as demonstrated by the net appearance in the outer medium of 1 hydroxyl ion per atom of oxygen reduced, appearance which proves sensitive to benhydroxamic acid, a specific inhibitor of the alternative pathway. The non electrogenicity of the alternative pathway is accompanied by the absence of ATP synthesis as expected from Mitchell's chemiosmotic model. The absence of energy conservation when the electron transfer proceeds via the alternative pathway is not the result of an uncoupling property of an active alternative pathway, as the oxidation of malate plus pyruvate via coupling site I and the alternative pathway occurs with an ATP/0 ratio tending to 1.     

Stabilization of the transition state in the active center of aminoacyl-tRNA-synthetase

The mechanism for transition state stabilization in the activation of amino acids by aminoacyl-tRNA synthetases is proposed. We carried out a quantum mechanical study on system modelling the attack of the amino acid carboxylate on the alpha-phosphate group of ATP. The activation barrier is reduced by improved hydrogen binding between a phosphoryl oxygen atom and a proton donor group of the enzyme. The relative stabilization of the transition state is found to be about 8 kcal/mol. On the basis of results obtained for the reaction in gas phase, in aqueous solution and in the active site the nature of the enzyme catalysis is discussed.     

Anticataleptic effect of delta sleep-inducing peptide and its action on brain monoamine oxidase in rats genetically predisposed to catalepsy

Rats with genetic susceptibility to catalepsy (GC strain) were compared with Wistar rats (W). After an intraperitoneal administration of 120 micrograms/100 g delta sleep-inducing peptide (DSIP) in GC rats the duration of cataleptic freezing was shortened (13.8 +/- 9.5 sec against 27.2 +/- 7.5 sec in control). MAO-B activity decreased due to DSIP administration both in GC and W rats. It is hypothesized that the DSIP effect MAO-B in GC rats may correct the lost MAO-A function in deamination of dopamine, a common MAO-A and MAO-B substrate, and the dopaminergic neurotransmission in catalepsy.     

Polymorphism for supernumerary chromosomes in populations of Rana temporaria L

Occurrence of B-chromosomes in four populations of Rana temporaria L. in Minsk, its suburb and Berezinski? biosphere reserve has been studied. The percentage of individuals with B-chromosomes and the average number of B-chromosomes per genome are shown to multiply increase in the population inhabiting for 40 years in the region polluted with waste products. The results obtained are discussed from the standpoint of the action of mechanism for the accumulation of additional chromosomes due to environmental pollution.