Sources and fluxes of hydrothermal heat, chemicals and biology within a segment of the Mid-Atlantic Ridge

We have conducted a segment-wide study of the chemical, biological and thermal effects of hydrothermal activity, in a bathymetrically enclosed, 50-km-long segment of the Mid-Atlantic Ridge, at 29°N. Our study involved long-term monitoring of bottom current speeds and temperatures coupled with ‘snap-shot' surveys of the concentrations of hydrothermal shrimp, manganese and particulate plumes occupying the water column enclosed by the axial valley. These data are combined with the calculated volume transport rates for the segment and the results compared with the heat and manganese flux from the Broken Spur vent field, located in the center of the segment. Our current meter data show that the basin-like bathymetry acts to restrict and control flow of water. Warm and shallow water, exported from the segment, is replaced by colder and deeper water. Water column profiles showed an increase in temperature of the water within the ‘Broken Spur' segment, compared with background stations located outside the ridge axis. The average refresh rate for the water column enclosed by the segment was found to be about 262 days. From these data, we calculate that the segment-wide flux of juvenile shrimp is 20×106 individuals per year. We show that the flux of manganese (exported at a rate of 5–6 mol/s) is matched by input from high-temperature effluent discharge at the Broken Spur vent field. We also calculate that the minimum average heat flux exported from the segment is about 275 MW. Of this, more than 90% is pervasively dissipated throughout the segment floor by conductively heated sea water, or simple thermal conduction, that carries little or no manganese to the water column. The remaining 10% or less of the heat flux results from localized, manganese-rich, high-temperature hydrothermal venting.<br/

Lipid-induced insulin resistance is associated with an impaired skeletal muscle protein synthetic response to amino Acid ingestion in healthy young men

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The ability to maintain skeletal muscle mass appears to be impaired in insulin-resistant conditions, such as type 2 diabetes, that are characterized by muscle lipid accumulation. The current study investigated the effect of acutely increasing lipid availability on muscle protein synthesis. Seven healthy young male volunteers underwent a 7-h intravenous infusion of l-[ring-(2)H5]phenylalanine on two randomized occasions combined with 0.9% saline or 10% Intralipid at 100 mL/h. After a 4-h "basal" period, a 21-g bolus of amino acids was administered and a 3-h hyperinsulinemic-euglycemic clamp was commenced ("fed" period). Muscle biopsy specimens were obtained from the vastus lateralis at 1.5, 4, and 7 h. Lipid infusion reduced fed whole-body glucose disposal by 20%. Furthermore, whereas the mixed muscle fractional synthetic rate increased from the basal to the fed period during saline infusion by 2.2-fold, no change occurred during lipid infusion, despite similar circulating insulin and leucine concentrations. This "anabolic resistance" to insulin and amino acids with lipid infusion was associated with a complete suppression of muscle 4E-BP1 phosphorylation. We propose that increased muscle lipid availability may contribute to anabolic resistance in insulin-resistant conditions by impairing translation initiation.This research study was funded by the University of Nottingham and Maastricht University. A.J.M. was supported by a British Nutrition Foundation Drummond Pump Priming Award

Neonatal cranial ultrasonography as predictor of 2 year outcome of very low birthweight infants

Abstract Real time ultrasound scans using an ATL 300C sector scanner with 5–7.5 MHz transducer were performed on days 1, 4, 7 and thereafter as clinically necessary on 153 consecutively discharged very low birthweight (VLBW) infants. One hundred and forty-six long-term survivors were assessed fully at 2 years. The prevalence of cerebroventricular haemorrhage (CVH) in these survivors was 34.2% (grade 1—21.2%; grade 2—4.8%; grade 3—3.4%; grade 4—4.8%), ventricular dilatation 19.9% (including 4.1% with ventriculoperitoneal shunt), and ischaemia 9%. Impairments at 2 years were classified as nil, mild, moderate, severe or multiply severe, based on the criteria of Kitchen et al. Overall, 120 infants (82.2%) were unimpaired and 6.2% had mild, 3.4% had moderate, 4.1% had severe and 4.1% had multiply severe impairment. The major factors associated with impairment were gestational age < 28 weeks, birthweight < 1000 g, vaginal delivery, respiratory distress syndrome, mechanical ventilation, pulmonary air leaks and CVH. When these factors were reanalysed in a logistic regression model for odds ratios, only CVH (P < 0.005) and birth by spontaneous vaginal delivery (P < 0.05) were significant. The prevalence of impairment was 11.4% with no CVH, 6.5% grade 1, 71% grade 2, 20.0% grade 3 and 100.0% grade 4 CVH. The sensitivity of CVH of grade 2 or greater as a screening test was 64.7% for impairment, 78.6% for cerebral palsy and 70% for severe intellectual handicap. The mean general quotient (GQ) (Griffiths) at 2 years for infants with CVH was 89.1, and 97.5 for those without CVH (P < 0.001). Although infants with ventricular dilatation had an average GQ that was 13.1 units less than those with normal ventricles, the difference was only significant in those with a CVH of grade 2–4. The study shows the sonographic diagnosis of CVH and ventricular dilatation, but not ischaemia, to be a useful adjunct in predicting impairment and intellectual performance in VLBW infants but does not replace the need for multidisciplinary follow-up

Impact of COVID-19 on Cardiovascular Testing in the United States Versus the Rest of the World

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-U.S. institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p &lt; 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection