174 research outputs found
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Pre- and Post-settlement Processes of Northern Rock Sole (Lepidopsetta polyxystra) in Relation to Interannual Variability in Temperature and Productivity in the Gulf of Alaska
Understanding the effects of climate variability on growth dynamics and timing of early life history events in marine fishes can provide insights into survival, recruitment and productivity. Field collections (2005, 2007, 2009-2011) were combined with otolith microstructural analysis to examine interannual variation in larval and juvenile growth rates, size at hatch and metamorphosis, and the timing of metamorphosis of northern rock sole (Lepidopsetta polyxystra) collected in two nurseries at Kodiak Island, Alaska, USA. Variation in early life characteristics was quantified and related to phytoplankton production, temperature and juvenile densities in nursery grounds. In addition, monthly sampling of juvenile northern rock sole during the initial post-settlement period (July to August) was used to determine if carry-over effects of size and growth occurred across life history stages. Finally, individual growth trajectories of July and August fish were compared for evidence of selective mortality during the initial post-settlement period. Overall, timing of metamorphosis varied across years and was related to annual and interannual variation in water temperature. Conversely, fish size at metamorphosis was similar across years, suggesting that the competency to metamorphose is related to a minimum size and ontogenetic stage. Post-settlement growth was related to temperatures in coastal nurseries as well as temperatures during the larval period, indicating that thermal conditions experienced by larvae may carry over to influence growth in nurseries. Correlations between pre- and post-settlement traits demonstrate that size and growth advantages could persist across life history stages. Growth selective mortality was not evident during the initial post-settlement period; however, differences in hatch size and the timing of metamorphosis between July and August fish suggest a selective loss of individuals. The patterns of selection varied among years, indicating that variation in size acquired early in life and temperature influences on the phenology of metamorphosis may determine the direction of selection and directly influence survival of northern rock sole
Validity of smartphone heart rate variability pre- and post-resistance exercise
The aim was to examine the validity of heart rate variability (HRV) measurements from photoplethysmography (PPG) via a smartphone application pre- and post-resistance exercise (RE) and to examine the intraday and interday reliability of the smartphone PPG method. Thirty-one adults underwent two simultaneous ultrashort-term electrocardiograph (ECG) and PPG measurements followed by 1-repetition maximum testing for back squats, bench presses, and bent-over rows. The participants then performed RE, where simultaneous ultrashort-term ECG and PPG measurements were taken: two pre- and one post-exercise. The natural logarithm of the root mean square of successive normal-to-normal (R-R) differences (LnRMSSD) values were compared with paired-sampl
Acute Blood Flow Responses to Varying Blood Flow Restriction Pressures in the Lower Limbs
International Journal of Exercise Science 16(2): 118-128, 2023. The purpose of this study was to investigate lower limb blood flow responses under varying blood flow restriction (BFR) pressures based on individualized limb occlusion pressures (LOP) using a commonly used occlusion device. Twenty-nine participants (65.5% female, 23.8 ± 4.7 years) volunteered for this study. An 11.5cm tourniquet was placed around participants’ right proximal thigh, followed by an automated LOP measurement (207.1 ± 29.4mmHg). Doppler ultrasound was used to assess posterior tibial artery blood flow at rest, followed by 10% increments of LOP (10-90% LOP) in a randomized order. All data were collected during a single 90-minute laboratory visit. Friedman’s and one-way repeated-measures ANOVAs were used to examine potential differences in vessel diameter, volumetric blood flow (VolFlow), and reduction in VolFlow relative to rest (%Rel) between relative pressures. No differences in vessel diameter were observed between rest and all relative pressures (all p \u3c .05). Significant reductions from rest in VolFlow and %Rel were first observed at 50% LOP and 40% LOP, respectively. VolFlow at 80% LOP, a commonly used occlusion pressure in the legs, was not significantly different from 60% (p = .88), 70% (p = .20), or 90% (p = 1.00) LOP. Findings indicate a minimal threshold pressure of 50%LOP may be required to elicit a significant decrease in arterial blood flow at rest when utilizing the 11.5cm Delfi PTSII tourniquet system
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Pre-settlement processes of northern rock sole (Lepidopsetta polyxystra) in relation to interannual variability in the Gulf of Alaska
Understanding the effects of climate variability on growth dynamics and timing of early life history events in marine fishes can provide insights into survival, recruitment and productivity. We examined interannual variation in indicators of larval growth rates, size at hatch and metamorphosis, and the timing of metamorphosis of northern rock sole (Lepidopsetta polyxystra) over 5 years in two nurseries at Kodiak Island, Alaska, USA. Variation in early life characteristics was quantified using laboratory-validated otolith structural analysis and related to water temperature and spring bloom dynamics in the Gulf of Alaska. Overall, results indicated that temperature contributed more to interannual variation in northern rock sole growth, size and phenology patterns than phytoplankton dynamics. Size at hatch was positively related to winter-spring spawning temperatures. Larval growth metrics were generally consistent with thermal effects as temperatures above 4°C appear necessary, but are not sufficient to support rapid growth. Reflecting the cumulative effects of temperature, the timing of metamorphosis was related to both seasonal and interannual variation in temperature with earlier dates of metamorphosis in warmer years. Conversely, fish size at metamorphosis was similar across years, suggesting that the competency to metamorphose is related to attainment of a minimum size. These results demonstrate the important role of temperature in regulating early life history phenology of northern rock sole and suggest that temperature-driven phenological shifts may also influence the time of spawning and hatching.Keywords: Northern rock sole, Lepidopsetta polyxystra, Metamorphosis, Gulf of Alask
Von Willebrand factor delays liver repair after acetaminophen-induced acute liver injury in mice
Background & Aim: Acetaminophen (APAP)-induced acute liver failure is associated with substantial alterations in the hemostatic system. In mice, platelets accumulate in the liver after APAP overdose and appear to promote liver injury. Interestingly, patients with acute liver injury have highly elevated levels of the platelet-adhesive protein von Willebrand factor (VWF), but a mechanistic connection between VWF and progression of liver injury has not been established. We tested the hypothesis that VWF contributes directly to experimental APAP-induced acute liver injury. Methods: Wild-type mice and VWF-deficient (Vwf−/−) mice were given a hepatotoxic dose of APAP (300 mg/kg, i.p.) or vehicle (saline). VWF plasma levels were measured by ELISA, and liver necrosis or hepatocyte proliferation was measured by immunohistochemistry. Platelet and VWF deposition were measured by immunofluorescence. Results: In wild-type mice, VWF plasma levels, high molecular weight (HMW) VWF multimers, and VWF activity decreased 24 h after APAP challenge. These changes coupled to robust hepatic VWF and platelet deposition, although VWF deficiency had minimal effect on peak hepatic platelet accumulation or liver injury. VWF plasma levels were elevated 48 h after APAP challenge, but with relative reductions in HMW multimers and VWF activity. Whereas hepatic platelet aggregates persisted in livers of APAP-challenged wild-type mice, platelets were nearly absent in Vwf−/− mice 48 h after APAP challenge. The absence of platelet aggregates was linked to dramatically accelerated repair of the injured liver. Complementing observations in Vwf−/− mice, blocking VWF or the platelet integrin αIIbβ3 during development of injury significantly reduced hepatic platelet aggregation and accelerated liver repair in APAP-challenged wild-type mice. Conclusion: These studies are the first to suggest a mechanistic link between VWF, hepatic platelet accumulation, and liver repair. Targeting VWF might provide a novel therapeutic approach to improve repair of the APAP-injured liver. Lay summary: Patients with acute liver injury due to acetaminophen overdose have highly elevated levels of the platelet-adhesive protein von Willebrand factor. It is not known whether von Willebrand factor plays a direct role in the progression of acute liver injury. We discovered that von Willebrand factor delays repair of the acetaminophen-injured liver in mice and that targeting von Willebrand factor, even in mice with established liver injury, accelerates liver repair.</p
The multi-wavelength view of shocks in the fastest nova V1674 Her
Classical novae are shock-powered multi-wavelength transients triggered by a
thermonuclear runaway on an accreting white dwarf. V1674 Her is the fastest
nova ever recorded (time to declined by two magnitudes is t_2=1.1 d) that
challenges our understanding of shock formation in novae. We investigate the
physical mechanisms behind nova emission from GeV gamma-rays to cm-band radio
using coordinated Fermi-LAT, NuSTAR, Swift and VLA observations supported by
optical photometry. Fermi-LAT detected short-lived (18 h) 0.1-100 GeV emission
from V1674 Her that appeared 6 h after the eruption began; this was at a level
of (1.6 +/- 0.4)x10^-6 photons cm^-2 s^-1. Eleven days later, simultaneous
NuSTAR and Swift X-ray observations revealed optically thin thermal plasma
shock-heated to kT_shock = 4 keV. The lack of a detectable 6.7 keV Fe K_alpha
emission suggests super-solar CNO abundances. The radio emission from V1674 Her
was consistent with thermal emission at early times and synchrotron at late
times. The radio spectrum steeply rising with frequency may be a result of
either free-free absorption of synchrotron and thermal emission by unshocked
outer regions of the nova shell or the Razin-Tsytovich effect attenuating
synchrotron emission in dense plasma. The development of the shock inside the
ejecta is unaffected by the extraordinarily rapid evolution and the
intermediate polar host of this nova.Comment: 20 pages, 9 figures, 3 tables. Accepted to MNRA
Improving breast cancer services for African-American women living in St. Louis
A mixed methods, community-based research study was conducted to understand how provider-level factors contribute to the African-American and white disparity in breast cancer mortality in a lower socioeconomic status area of North St. Louis. This study used mixed methods including: (1) secondary analysis of Missouri Cancer Registry data on all 885 African-American women diagnosed with breast cancer from 2000 to 2008 while living in the geographic area of focus; (2) qualitative interviews with a subset of these women; (3) analysis of data from electronic medical records of the women interviewed; and (4) focus group interviews with community residents, patient navigators, and other health care professionals. 565 women diagnosed with breast cancer from 2000 to 2008 in the geographic area were alive at the time of secondary data analysis; we interviewed (n = 96; 17 %) of these women. Provider-level obstacles to completion of prescribed treatment included fragmented navigation (separate navigators at Federally Qualified Health Centers, surgical oncology, and medical oncology, and no navigation services in surgical oncology). Perhaps related to the latter, women described radiation as optional, often in the same words as they described breast reconstruction. Discontinuous and fragmented patient navigation leads to failure to associate radiation therapy with vital treatment recommendations. Better integrated navigation that continues throughout treatment will increase treatment completion with the potential to improve outcomes in African Americans and decrease the disparity in mortality
Abdominal obesity and metabolic syndrome: exercise as medicine?
Background: Metabolic syndrome is defined as a cluster of at least three out of five clinical risk factors: abdominal (visceral) obesity, hypertension, elevated serum triglycerides, low serum high-density lipoprotein (HDL) and insulin resistance. It is estimated to affect over 20% of the global adult population. Abdominal (visceral) obesity is thought to be the predominant risk factor for metabolic syndrome and as predictions estimate that 50% of adults will be classified as obese by 2030 it is likely that metabolic syndrome will be a significant problem for health services and a drain on health economies.Evidence shows that regular and consistent exercise reduces abdominal obesity and results in favourable changes in body composition. It has therefore been suggested that exercise is a medicine in its own right and should be prescribed as such. Purpose of this review: This review provides a summary of the current evidence on the pathophysiology of dysfunctional adipose tissue (adiposopathy). It describes the relationship of adiposopathy to metabolic syndrome and how exercise may mediate these processes, and evaluates current evidence on the clinical efficacy of exercise in the management of abdominal obesity. The review also discusses the type and dose of exercise needed for optimal improvements in health status in relation to the available evidence and considers the difficulty in achieving adherence to exercise programmes. Conclusion: There is moderate evidence supporting the use of programmes of exercise to reverse metabolic syndrome although at present the optimal dose and type of exercise is unknown. The main challenge for health care professionals is how to motivate individuals to participate and adherence to programmes of exercise used prophylactically and as a treatment for metabolic syndrome
Evaluation of Microorganisms Cultured from Injured and Repressed Tissue Regeneration Sites in Endangered Giant Aquatic Ozark Hellbender Salamanders
Investigation into the causes underlying the rapid, global amphibian decline provides critical insight into the effects of changing ecosystems. Hypothesized and confirmed links between amphibian declines, disease, and environmental changes are increasingly represented in published literature. However, there are few long-term amphibian studies that include data on population size, abnormality/injury rates, disease, and habitat variables to adequately assess changes through time. We cultured and identified microorganisms isolated from abnormal/injured and repressed tissue regeneration sites of the endangered Ozark Hellbender, Cryptobranchus alleganiensis bishopi, to discover potential causative agents responsible for their significant decline in health and population. This organism and our study site were chosen because the population and habitat of C. a. bishopi have been intensively studied from 1969–2009, and the abnormality/injury rate and apparent lack of regeneration were established. Although many bacterial and fungal isolates recovered were common environmental organisms, several opportunistic pathogens were identified in association with only the injured tissues of C.a. bishopi. Bacterial isolates included Aeromonas hydrophila, a known amphibian pathogen, Granulicetella adiacens, Gordonai terrae, Stenotrophomonas maltophilia, Aerococcus viridans, Streptococcus pneumoniae and a variety of Pseudomonads, including Pseudomonas aeruginosa, P. stutzeri, and P. alcaligenes. Fungal isolates included species in the genera Penicillium, Acremonium, Cladosporium, Curvularia, Fusarium, Streptomycetes, and the Class Hyphomycetes. Many of the opportunistic pathogens identified are known to form biofilms. Lack of isolation of the same organism from all wounds suggests that the etiological agent responsible for the damage to C. a. bishopi may not be a single organism. To our knowledge, this is the first study to profile the external microbial consortia cultured from a Cryptobranchid salamander. The incidence of abnormalities/injury and retarded regeneration in C. a. bishopi may have many contributing factors including disease and habitat degradation. Results from this study may provide insight into other amphibian population declines
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