Geochemical and Visual Indicators of Hydrothermal Fluid Flow through a Sediment-Hosted Volcanic Ridge in the Central Bransfield Basin (Antarctica)

In the austral summer of 2011 we undertook an investigation of three volcanic highs in the Central Bransfield Basin, Antarctica, in search of hydrothermal activity and associated fauna to assess changes since previous surveys and to evaluate the extent of hydrothermalism in this basin. At Hook Ridge, a submarine volcanic edifice at the eastern end of the basin, anomalies in water column redox potential (E_h) were detected close to the seafloor, unaccompanied by temperature or turbidity anomalies, indicating low-temperature hydrothermal discharge. Seepage was manifested as shimmering water emanating from the sediment and from mineralised structures on the seafloor; recognisable vent endemic fauna were not observed. Pore fluids extracted from Hook Ridge sediment were depleted in chloride, sulfate and magnesium by up to 8% relative to seawater, enriched in lithium, boron and calcium, and had a distinct strontium isotope composition (⁸⁷Sr/⁸⁶Sr  = 0.708776 at core base) compared with modern seawater (⁸⁷Sr/⁸⁶Sr ≈0.70918), indicating advection of hydrothermal fluid through sediment at this site. Biogeochemical zonation of redox active species implies significant moderation of the hydrothermal fluid with in situ diagenetic processes. At Middle Sister, the central ridge of the Three Sisters complex located about 100 km southwest of Hook Ridge, small water column E_h anomalies were detected but visual observations of the seafloor and pore fluid profiles provided no evidence of active hydrothermal circulation. At The Axe, located about 50 km southwest of Three Sisters, no water column anomalies in E_h, temperature or turbidity were detected. These observations demonstrate that the temperature anomalies observed in previous surveys are episodic features, and suggest that hydrothermal circulation in the Bransfield Strait is ephemeral in nature and therefore may not support vent biota.     

Evaluation of newborn canine viability by means of umbilical vein lactate measurement, apgar score and uterine tocodynamometry

Newborn viability evaluation and early detection of fetal distress could contribute to reducing mortality at birth in canine species. High neonatal mortality rate in dogs is reported subsequent to complicated or uncomplicated whelping. Umbilical vein lactate and tocodynamometry could provide valuable clinical information to the obstetricians so that appropriate medical and surgical treatments or oxygen and warm administration can be properly and timely applied to mother and newborn pup. In humans, the fetal lactate level represents an objective indicator of fetal distress and a valid predictor of babies' survival. Fetal acidosis recognition by umbilical lactate (UL) measurement, APGAR score classification, and uterine activity monitoring during labour, can represent an advanced system in the evaluation of the canine newborn patient. The purpose of this study was to correlate UL levels with canine neonatal morbidity and mortality within 48 h of birth. We evaluated the relationship among neonatal parameters at birth (mucous membrane color, heart and respiratory rate, reflex irritability, mobility, suckling and vocalization, UL, weight, and temperature) with labour characteristics (uterine contractions recorded by the tocodynamometric system of Whelpwise™ Veterinary Perinatal Specialties®, delivery time, and pup presentation), in view to predict pup viability. We considered also vaginal parturition versus elective and emergency Caesarean section, and uterotonic drugs influence on delivery. Umbilical lactate concentration proved to be useful to predict canine neonatal mortality within 48 h of birth (P < 0.05). We identified 5 mmol/L of vein umbilical lactate concentration as the cut off value, allowing us to distinguish between healthy and distressed pups. Higher values of UL were related with distressed pups, whereas lower values characterized vigorous pups. Lactate concentrations lower than 5 mmol/L and APGAR scores higher than 9, related to mean delivery time of 105 min with effective uterine contractions (10 mm of Hg of strength or more, frequency from 4 to 12 contractions per hour, and 2-5 min in duration), should be considered good prognostic factors in canine labour and neonatology.     

Gene Expression Analysis of Children with Acute Hematogenous Osteomyelitis Caused by Methicillin-Resistant Staphylococcus aureus: Correlation with Clinical Severity of Illness

Children with acute hematogenous osteomyelitis (AHO) demonstrate a broad spectrum of clinical manifestations, ranging from mild to severe. Several advances have been achieved in the study of host immune response to acute invasive Staphylococcus aureus infections through gene expression analysis. However, previous research has neither attempted to evaluate the response of children with AHO specific to Methicillin-resistant Staphylococcus aureus (MRSA) nor to correlate gene expression with clinical phenotype. Study objective was to correlate gene expression of children with AHO due to MRSA with clinical severity of illness. Whole blood samples were obtained in Tempus tubes from 12 children with osteomyelitis once cultures obtained directly from the site of infection confirmed to be positive for MRSA. Using an Illumina platform and a systems-wide modular analysis, microarray findings from ten of these children were compared to that of nine healthy (age, ethnicity and gender) matched controls and correlated with clinical severity of illness. Children with AHO from MRSA demonstrated over-expression of innate immunity with respect to neutrophil activity, coagulation, inflammatory response, and erythrocyte development. Concurrently, these children demonstrated under-expression of adaptive immunity with respect to lymphocyte activation and activity of T-cell, cytotoxic or NK cell, and B-cell lines. Three over-expressed genes, P2RX1, SORT1, and RETN, and two under-expressed genes, LOC641788 and STAT 4, were significantly correlated with severity of illness. STAT 4 showed the strongest correlation (R2 = –0.83). STAT4 downregulation could potentially explain under-expression of genes related to adaptive immunity in this cohort of patients with AHO. This study identified specific genes which correspond to disease severity during the early hospitalization of children with AHO from MRSA. Pattern recognition of this combination of genes could help to identify in the future severe clinical phenotypes before the disease is fully manifest and direct appropriate attention and resources to those children.     

HUMORAL RHEOLOGY : I. VISCOSITY STUDIES AND ANOMALOUS FLOW PROPERTIES OF HUMAN BLOOD SYSTEMS WITH HEPARIN AND OTHER ANTICOAGULANTS

1. A modified falling ball viscometer (rolling ball viscometer) for blood and other humors is presented. It is capable of easily measuring flow properties at several stresses, as is required to define satisfactorily the properties of anomalous flow systems. At high shearing stresses, apparent specific viscosity values of 2.5 + are observed, corresponding to 2.2 ±0.2 reported as possible with the biological viscometer of Whittaker and Winton. 2. Previous references to the anomalous flow properties of blood were verified. It was demonstrated that these systems conform to the Bingham concept of anomalous flow. To define completely the flow properties of such systems it is necessary to make determinations at at least two shearing stresses, preferably more. Data are reported for the pseudoviscosity and yield value, the latter being possibly the most specific property of the three bloods studied. 3. Heparin in increasing amounts tended to decrease the apparent viscosity, pseudoviscosity, and yield value of blood. Similar increases of heparin also reduced the viscosites of the serum and plasma. 4. The ratio of the apparent viscosity of blood and its plasma was found to be reasonably constant as reported by Trevan. However, as the apparent viscosity is a function of the shearing stress, it is believed that the relationship for the calculations of corpuscular concentrations, such as the Whittaker and Winton modification of the Hatschek formula, is specific for the instrument and conditions of tests by which it was determined. 5. Heparinized blood was found to exhibit thixotropy, dilatancy, and age-hardening phenomena.     

How the mollusc got its scales: convergent evolution of the molluscan scleritome

Radiation of dramatically disparate forms among the phylum Mollusca remains a key question in metazoan evolution, and requires careful evaluation of homology of hard parts throughout the deep fossil record. Enigmatic early Cambrian taxa such as Halkieria and Wiwaxia (in the clade Halwaxiida) have been proposed to represent stem‐group aculiferan molluscs (Caudofoveata + Solenogastres + Polyplacophora), as complex scleritomes were considered to be unique to aculiferans among extant molluscs. The ‘scaly‐foot gastropod’ (Neomphalina: Peltospiridae) from hydrothermal vents of the Indian Ocean, however, also carries dermal sclerites and thus challenges this inferred homology. Despite superficial similarities to various mollusc sclerites, the scaly‐foot gastropod sclerites are secreted in layers covering outpockets of epithelium and are largely proteinaceous, while chiton (Polyplacophora: Chitonida) sclerites are secreted to fill an invaginated cuticular chamber and are largely calcareous. Marked differences in the underlying epithelium of the scaly‐foot gastropod sclerites and operculum suggest that the sclerites do not originate from multiplication of the operculum. This convergence in different classes highlights the ability of molluscs to adapt mineralized dermal structures, as supported by the extensive early fossil record of molluscs with scleritomes. Sclerites of halwaxiids are morphologically variable, undermining the assumed affinity of specific taxa with chitons, or the larger putative clade Aculifera. Comparisons with independently derived similar structures in living molluscs are essential for determining homology among fossils and their position with respect to the enigmatic evolution of molluscan shell forms in deep time. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 949–954.     

A trade-off between catalytic power and substrate inhibition in TCHQ dehalogenase

Tetrachlorohydroquinone (TCHQ) dehalogenase is profoundly inhibited by its aromatic substrates, TCHQ and trichlorohydroquinone (TriCHQ). Surprisingly, mutations that change Ile12 to either Ser or Ala give an enzyme that shows no substrate inhibition. We have previously shown that TriCHQ is a noncompetitive inhibitor of the thiol-disulfide exchange reaction between glutathione and ESSG, a covalent adduct between Cys13 and glutathione formed during dehalogenation of the substrate. Substrate inhibition of the thiol-disulfide exchange reaction is less severe in the I12S and I12A mutant enzymes, primarily due to weaker binding of TriCHQ to ESSG. These mutations also result in a decrease in the rate of dehalogenation. Because the rate-limiting step in the I12S and I12A enzymes is dehalogenation, rather than the thiol-disulfide exchange reaction, the relatively modest inhibition of the thiol-disulfide exchange reaction does not affect the overall rate of turnover.