Effect Of Age Research Articles

The effect of maternal age on still birth in Africa: A systematic review and meta-analysis.

Stillbirth is a public health as well as a development problem in low and middle-income countries. The studies that found out maternal age as a factor for the risk of stillbirth reported different findings. This systematic review and meta-analysis is believed to fill the inconclusiveness of these findings. Hence, the aim of this systematic review and meta-analysis is to estimate the pooled effect of advanced maternal age on stillbirth in Africa. PubMed & HINARY databases and Google Scholar search engine were searched to access the primary studies. The extracted data using Microsoft excel was exported to Stata 15 software for analysis. The presence of heterogeneity was checked using Cochran's Q statistic and the I 2 test. Publication bias was examined by using funnel plot and Egger's test. The pooled effect measure with DerSimonian and Laird method of random-effect model was reported using odds ratio (OR) with respective 95% confidence interval. Totally, 14 articles are included for the systematic review and meta-analysis. The stillbirth reported by the studies ranges from 15 to 146.7 per 1000 births. The overall OR of advanced maternal age (≥35 years) on stillbirth is 1.42 (1.18, 1.71) when compared with the age group of 20-35 years. The cumulative effect of getting pregnant at advanced age on stillbirth was slightly increasing from year to year. Advanced maternal age is a risk factor for stillbirth. Health Information Communication on the risk of getting pregnant at the advanced ages on stillbirth should be well addressed to all women of reproductive age group.

Statistical evaluation of effect of anthropometric measurements on adolescent idiopathic scoliosis

Scoliosis is a deformity in which there is sideways curvature to the spine. Curves are often S shaped or C shaped. Most common type is the idiopathic type which occurs in 10-12 years of age and early teens, females are more affected than males while the body is growing fast and the curve is commonly to the right side of the body. It however affect all ages of about 3% of general population. This study was set out to evaluate statistically, the effect of age, gender and anthropometric measurements (such as height, weight and body mass index) to the curve formed using 51 patients from Lagos State University Teaching Hospital, Ikeja. It was discovered from the analysis that the ailment is common among females than males. The result also shows that the curve is most common to right hand side. The test of hypothesis conducted reveals that the anthropometric measurements of height, weight and body mass index though positively correlated with but do not have significant effect on the Adolescent Idiopathic Scoliosis curve.

Effects of aging on the bioactive flavonoids and fungal diversity of Pericarpium Citri Reticulatae (Citrus reticulata ‘Chachi’)

Samples of Pericarpium Citri Reticulatae (Citrus reticulata 'Chachi', CP-‘Chachi’), which collected in December of 2017, 2013, 2003 and 1993 with the natural aging process for 5, 10, 20 and 30 years, were used to compared the changes in total polyphenols, total flavonoids and fungal community composition. The relationship among these factors was analyzed. The content of flavonoids in CP-‘Chachi’ was qualitatively and quantitatively determined by HPLC system. ITS (Internal Transcribed spacer) sequencing techniques were used to detect the changes of microbial communities during the aging process of CP-‘Chachi’. The results indicated that the levels of flavonoids and total polyphenols, except for hesperidin, increased aging time, with the most significant growth observed in 5-O-desmethyl nobiletin at 298.36%, while hesperidin decreased by 32.52%. The three most abundant genera were Xeromyces, Symmetrospora and Cladosporium, and the highest number of genera was found in CP-2013. The community composition of CP-1993 and CP-2003 was highly similar, Xeromyces accounted for 84.04% and 83.58% in CP-1993 and CP-2003, respectively. The findings demonstrated that only the abundance of Xeromyces was positively correlated with the accumulation of active components during the aging process of CP-‘Chachi’. This indicated that Xeromyces was considered the dominant genus responsible for the aging quality of CP-'Chachi'. The relationship between the changes in flavonoids and fungal diveresity was preliminarily verified, which provided new insights into the study of the aging mechanism of CP-‘Chachi’ and its influencing factors on quality.

Characteristics of Patients with Clinical Signs and Symptoms of Carpal Tunnel Syndrome but Negative Diagnostic Testing.

Carpal tunnel syndrome (CTS) is a clinical diagnosis involving numerous confirmatory diagnostic tools, including patient questionnaires, ultrasound (US), and electrodiagnostic studies (EDX.) Patients may experience clinical symptoms of CTS with false negative diagnostic testing. The purpose of this study was to identify characteristics of patients with clinical symptoms of CTS with negative diagnostic testing. An existing database of 295 hands containing the six-item CTS-6, US of the median nerve, and EDX was queried. Patients with symptoms of carpal tunnel scoring 12.5 or higher on CTS-6 were sorted into those with all positive testing or negative testing. In 60 patients, 103 hands had both positive US and EDX and a CTS-6 of 12.5 or higher. Twenty-nine hands in 25 patients had a CTS-6 of 12.5 or higher and both negative ultrasound and EDX. There was a significantly younger average age of 43 (P = 0.007) and lower average BMI of 28 (P < 0.0001) of patients in the negative diagnostic study group, compared with the average age of 53, and a body mass index (BMI) of 34 in the positive diagnostic study. In this series, patients with symptoms of carpal tunnel syndrome and negative diagnostic studies were on average younger and had a lower BMI. These patients may warrant more careful consideration of CTS clinical diagnosis and counseling regarding a higher risk of false-negative confirmatory testing. Further studies are needed to determine possible effects of age and BMI on electrodiagnostic studies and ultrasound testing in CTS.

Lower Mitochondrial Genome Turnover and Greater Mutation Frequency in Skeletal Muscle of Aged Compared to Adult OKC-HET Rats

Mitochondrial genomic integrity, which is supported by processes such as replication, repair, and turnover, is critical in supporting metabolism and organismal health. Accumulation of mitochondrial DNA (mtDNA) mutations contributes to mitochondrial and whole-tissue dysfunction, which lead to chronic diseases including sarcopenia. The underlying mechanisms that promote generation and age-related accumulation of mtDNA mutations are unclear. mtDNA mutants may have a replicative advantage over wild-type mtDNA that propagates the accumulation of mtDNA mutations with age. However, there is limited in vivo data regarding effects of age on mtDNA replication, particularly in skeletal muscle. We hypothesized mtDNA synthesis rates would increase with age as mutation burden increased in skeletal muscle in both male and female rats. Methods: We measured mtDNA synthesis over 14 days using the stable isotope tracer deuterium oxide (D2O) and assessed mtDNA copy number and mutation deletion frequency using digital PCR in quadriceps muscle of 9- and 26 month-old (mo) male and female OKC-HET rats, which have heterogenous mtDNA backgrounds. Results: There were no differences in mtDNA copy number between sexes or ages. However, 26 month-od rats had lower rates of mtDNA synthesis compared to 9 month-old rats (9 mo: 0.509 ± 0.009 %/day, 26 month: 0.371 ± 0.048 %/day; p=0.0024) and greater mtDNA half-lives (9 mo: 132 ± 1.79 days, 216 ± 25.63 days; p=0.0009). Concomitant with lower mtDNA synthesis, 26 month-old rats had greater (p=0.003) mtDNA deletion mutation frequency (2.023e-004 ± 7.18e-005) than 9 month-old rats (9.310e-005 ± 2.404e-005). 26 month-old female rats (1.309e-004 ± 2.386e-005) had a lower (p=0.008) mutation burden than male rats (2.74e-004 ± 4.484e-005). Conclusion: Contrary to our hypothesis, mtDNA synthesis declined with age as mutation burden increased in the quadriceps. Because mtDNA copy number was not different between ages, while synthesis decreased, mtDNA turnover declined with age. Altogether, these results suggest lower mtDNA turnover rates may contribute to age-related mtDNA mutation burden. Future studies should test how modulating mtDNA turnover affects mutation frequency and mitochondrial function. This study was supported by funding from NIH grants R21AG072137 and 5T32AG052363-04. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of aging on recruitment of tenogenic progenitor during tendon-to-bone healing in a rat rotator cuff repair model

Effect of aging on recruitment of tenogenic progenitor during tendon-to-bone healing in a rat rotator cuff repair model

Post-printing processing and aging effects on Polyjet materials intended for the fabrication of advanced surgical simulators

Material Jetting (MJ) 3D printing technology is promising for the fabrication of highly realistic surgical simulators, however, the changes in the mechanical properties of MJ materials after post-printing treatments and over time remain quite unknown.In this study, we investigate the effect of different post-printing processes and aging on the mechanical properties of a white opaque and rigid MJ photopolymer, a white flexible MJ photopolymer and on a combination of them. Tensile and Shore hardness tests were conducted on homogeneous 3D-printed specimens: two different post-printing procedures for support removal (dry and water) and further surface treatment (with glycerol solution) were compared. The specimens were tested within 48 h from printing and after aging (30–180 days) in a controlled environment.All groups of specimens treated with different post-printing processes (dry, water, glycerol) exhibited a statistically significant difference in mechanical properties (i.e. elongation at break, elastic modulus, ultimate tensile strength). Particularly, the treatment with glycerol makes the flexible photopolymer more rigid, but then with aging the initial elongation of the material tends to be restored. For the rigid photopolymer, an increase in deformability was observed as a major effect of aging. The hardness tests on the printed specimens highlighted a significant overestimation of the Shore values declared by the manufacturer. The study findings are useful for guiding the material selection and post-printing processing techniques to manufacture realistic and durable models for surgical training.

Cochlear-implant listeners benefit from training with time-compressed speech, even at advanced ages.

This study evaluated whether adaptive training with time-compressed speech produces an age-dependent improvement in speech recognition in 14 adult cochlear-implant users. The protocol consisted of a pretest, 5 h of training, and a posttest using time-compressed speech and an adaptive procedure. There were significant improvements in time-compressed speech recognition at the posttest session following training (>5% in the average time-compressed speech recognition threshold) but no effects of age. These results are promising for the use of adaptive training in aural rehabilitation strategies for cochlear-implant users across the adult lifespan and possibly using speech signals, such as time-compressed speech, to train temporal processing.

The effect of age on cerebral vasospasm and delayed cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage.

The association between patient age and cerebral arterial vasospasm (CVS) and delayed cerebral ischemia (DCI) risk following aneurysmal subarachnoid hemorrhage (aSAH) remains unclear. This study aims to assess the role of age on aSAH-related complications. Single-center retrospective study comprising aSAH patients treated between January 2009 and March 2023. Age was analyzed as continuous and categorical variables (<60yrs vs. ≥60yrs and by decade). Outcomes of interest included radiographic CVS, DCI, cerebral infarction, in-hospital mortality, length-of-stay, ventriculoperitoneal shunt placement, and modified Rankin Scale (mRS) scores at discharge and 3-month follow-up. 925 aSAH patients were included. Most (n=598; 64.6%) were <60yrs old (46±9.1yrs). CVS likelihood was lower in the older cohort (aOR=0.56 [0.38-0.82]). Patients ≥60yrs had higher mortality rates (aOR=2.24 [1.12-4.47]) and worse mRS scores at discharge (aOR=2.66 [1.91-3.72]) and 3-month follow-up (aOR=2.19 [1.44-3.32]). Advanced age did not have a significant effect on DCI or cerebral infarction risk. Higher in-hospital mortality was documented with increasing age (p<0.001). A significant interaction between CVS and age for the outcome of DCI was documented, with a stronger positive effect on poor outcomes (i.e., higher odds of DCI) among patients aged <60 years compared to those aged ≥60. There is an inverse relationship between patient age and CVS incidence following aSAH. Nonetheless, patients ≥60yrs had comparable DCI rates, higher in-hospital mortality, and worse functional outcomes than their younger counterparts. Routine screening and reliance on radiographic CVS as primary marker for aSAH-related complications should be reconsidered, particularly in older patients.

Neurodevelopment of children exposed to prolonged anesthesia in infancy: GABA study interim analysis of resting-state brain networks at 2, 4, and 10-months old

BackgroundPrevious studies have raised concerns regarding neurodevelopmental impacts of early exposures to general anesthesia and surgery. Electroencephalography (EEG) can be used to study ontogeny of brain networks during infancy. As a substudy of an ongoing study, we examined measures of functional connectivity in awake infants with prior early and prolonged anesthetic exposures and in control infants. MethodsEEG functional connectivity was assessed using debiased weighted phase lag index at source and sensor levels and graph theoretical measures for resting state activity in awake infants in the early anesthesia (n = 26 at 10 month visit, median duration of anesthesia = 7 [2, 7 h]) and control (n = 33 at 10 month visit) groups at ages approximately 2, 4 and 10 months. Theta and low alpha frequency bands were of primary interest. Linear mixed models incorporated impact of age and cumulative hours of general anesthesia exposure. ResultsModels showed no significant impact of cumulative hours of general anesthesia exposure on debiased weighted phase lag index, characteristic path length, clustering coefficient or small-worldness (conditional R2 0.05–0.34). An effect of age was apparent in many of these measures. ConclusionsWe could not demonstrate significant impact of general anesthesia in the first months of life on early development of resting state brain networks over the first postnatal year. Future studies will explore these networks as these infants grow older

Effects of aging on vasoconstrictor responses of diaphragm arterioles

Introduction: In health, the diaphragm is the most important inspiratory muscle and the only skeletal muscle that is continuously recruited throughout life. Because of the diaphragm’s importance to generating the exercise hyperpnea and wealth of evidence that diaphragm fatigue and exhaustion can impair exercise tolerance, we were interested in whether the exercise intolerance that attends older populations might be associated with altered diaphragm vasomotor control. While it is known that aging compromises peripheral skeletal muscle vasomotor control, it is not known if similar impairments are present in the respiratory muscle vasculature, namely the diaphragm. Therefore, we tested the hypothesis that advanced age decreases diaphragm arteriole contractile responses to alpha-adrenergic agonists. Methods: 4–5 month old Fischer rats and 22–24 month old Fischer rats were divided by age into two groups: young (Y) and old (O). In Y and O, diaphragm first order (1A) arterioles (~200μm diameter, ~2μm in length) were isolated, cannulated, and pressurized to develop spontaneous tone. Following this, contractile responses to cumulative doses of norepinephrine (NE) and phenylephrine (PE) (10−9 to 10−4M) were determined. Results and Conclusion: The physical characteristics of the two groups differed as O were heavier than Y. However, with respect to the diaphragm 1A arterioles, there were no differences in spontaneous tone development (%) or maximal diameter (μm) between Y (38 ± 4%; 132 ± 19μm) and O (37 ± 4%; 157 ± 14 μm; both P &gt;0.05). In diaphragm 1A arterioles, the maximal vasoconstrictor response to NE was also not different between O and Y animals (O: 37 ± 8% vs. Y: 45 ± 1%; p &gt; 0.05). However, the maximal vasoconstrictor response to PE was greater in Y compared to O (O: 29 ± 3% vs. Y: 39 ± 5%; p ≤ 0.05). These data support that aging may reduce a1 adrenergic receptor mediated vascular control, altering the vasoconstrictive responsiveness of diaphragm resistance vessels. We are increasing our group sizes to test the robustness of this conclusion. This work was supported by the Sustained Momentum for Investigators with Laboratories Established (SMILE) Grants awarded to T.I.M and D.C.P. by Kansas State University College of Veterinary Medicine and the National Institute on Aging 1R15AG078060 awarded to B.J.B and D.C.P. A.G.H and K.M.S. were financially supported by Ruth L. Kirschstein National Research Service Awards 1F31HL167618-01 and 1F31HL170643-01, respectively. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of aging and exercise on Mitochondria-ER contacts (MERCs) in skeletal muscle

Mitochondrial dysfunction is a prominent factor contributing to age-associated loss of muscle mass and force (a.k.a., sarcopenia). Yet, events preceding age-related mitochondrial dysfunction, which may allow the development of new therapies, remain poorly understood. Physical coupling of the outer mitochondrial membrane (OMM) to the endoplasmic or sarcoplasmic reticulum (ER), termed mitochondria ER contact sites (MERCs), modulate several mitochondrial processes influencing cellular function. In an energetically demanding and primarily post-mitotic tissue, we hypothesized that alterations in MERCs correlate with the development of sarcopenia. We also hypothesized that MERCs respond to exercise training and may contribute to beneficial muscular remodeling in older adults. To address these, we studied three age groups of male C57BL6N mice: young adults (Y, 5 mo. of age), old (O, 20 mo. of age), and very old (VO, 31 mo. of age). An additional group of old mice underwent 8-9 weeks of treadmill training (OET). Muscle mass and contractile function decreased with aging; VO animals displayed ~25% decline in maximum tetanic force vs. Y mice (p&lt;0.0001). Fatigability (assessed via repetitive sub-maximal contractions) increased by ~10% with aging but was attenuated in the OET group (p&lt;0.001). In saponin-permeabilized muscle fibers, aging did not affect mitochondrial oxidative capacity. However, H2O2 emission was nearly doubled in the O group (p&lt;0.01) and this trend was partially alleviated by exercise training. Assessed via TEM, aging decreased the size of MERCs (i.e., length of SR and OMM apposition) by around 20% (p&lt;0.01). Interestingly, OET animals displayed ~50% increase in MERC coverage (i.e., proportion of OMM covered by SR; p&lt;0.0001). Immunoblots of cellular MERC fractions revealed that MERC proteins associated with calcium exchange were altered with age and exercise. The OMM channel, VDAC1, was reduced by 20% in O muscles (p=0.02), while Grp75, a tether protein, was ~25% higher in OET (p=0.02). Quantitative proteomic analyses revealed various MERC proteins being modified by aging and exercise. Our findings indicate that changes in MERC structure and protein composition may underlie early events preceding the development of sarcopenia and that exercise-mediated adaptations at MERCs may contribute to the beneficial adaptations in aging skeletal muscle. Supported by the University of Iowa Fraternal Order of Eagles Diabetes Research Center (UIowa FOEDRC). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of Aging and Fatigue on Human Skeletal Muscle Cellular Contractile Function

Aging is associated with a reduction in skeletal muscle mass and function, known as sarcopenia. While reductions in contractile force are typically explained by loss in muscle cellular cross sectional area (CSA) loss of contractile power during high velocity contractions exceed reductions in force and cannot be solely explained by loss of muscle size and are observed at the single fiber within the same myosin heavy chain isoform (MHC). These phenomenon may be explained by myosin binding protein C (MyBP-C), which is known to modulate contractile force and velocity in a phosphorylation-dependent manner in both cardiac and skeletal muscle. Few studies have investigated the inherent contractile performance of single fibers between old and young adults, and none have explored the effects of altered MyBP-C phosphorylation on single fiber function. Therefore, the PURPOSE of this study was to investigate the effects of age and fatigue-induced MyBP-C phosphorylation on single fiber contractile performance. We HYPOTHESIZED that isometric tension will be enhanced in older adults but velocity and power will be reduced, and fatigue will enhance velocity and power in single fibers. To test this hypothesis, we recruited 4 young (18-35) and 3 older (65-80) adult males to perform a single bout of unilateral knee extensions at 30% maximal voluntary isometric contraction (MVIC) until task failure. Immediately following, a bilateral biopsy of the vastus lateralis (VL) muscle was performed on the fatigued and non-fatigued control limbs. Tissue was either flash frozen for western blot or prepared for mechanical analysis of single fiber tension (Tmax), velocity (Vmax), and power (Pmax) under optimal intracellular metabolic conditions. Our analyses were limited to MHC IIA due to differences in fiber type distribution between the groups. Our RESULTS showed that neither age nor fatigue had an effect on contractile performance in MHC IIA fibers. However, independent analysis of fatigue within age groups suggest trends towards an increase in velocity (p=0.055) in young (MHC IIA) and reduction in tension (p=0.085) in old (MHC I) adult fibers. We CONCLUDE that fatigue may modulate contractile function in the single fiber in an age- and fiber-type dependent manner. Future studies will be aimed at collecting multiple fiber types and investigating the role of biological sex. Wu Tsai Human Performance Alliance. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Nonlinear mechanisms of CO2 emissions in growing and shrinking cities: an empirical study on integrated effects of aging and industrial structure in Japan

For the first time, this research aims to reveal how population age changes the nexus of industrial structure upgrading-carbon emissions under urban growth and shrinkage using a panel threshold model. Population aging, industrial structure upgrading, and CO2 emission mitigation represent three main challenges for urban development globally. However, only a few studies have integrated these challenges under the same framework, especially in the context of differentiated urban development patterns. Taking Japan as an example, urban development patterns are classified into four types using urban population and population density data from 2010 to 2020, including growth type, potential shrinking type, smart shrinking type, and continuous shrinking type. Each type’s CO2 emission patterns regarding energy consumption are then examined. After controlling for several socioeconomic and urban land scale variables, population aging and industry structure were used as the threshold variable and the key explanatory variable in the panel threshold model, respectively. The results showed that growing cities have lower carbon than any of the shrinking cities in terms of CO2 emissions per capita. A single-threshold effect of population aging was detected that changes the nexus of industrial structure upgrading-CO2 emissions in potentially shrinking cities and continuously shrinking cities, while no such nonlinear effect was detected in the growing group. The mitigating effect of industrial structure upgrading on CO2 emissions per capita increases as the aging level crosses 23.71% in potentially shrinking cities. In contrast, the promoting effect of industrial structure upgrading on CO2 emissions per capita weakens as the aging level crosses 20.27% in continuously shrinking cities. This study implies a nonlinear mechanism of CO2 emissions considering the integrated effects of aging and industrial structure, contributing to developing a rational and efficient emission reduction strategy considering differentiated urban development patterns.

Chloroquine Treatment Causes Diaphragm Muscle Denervation

Chloroquine (CQ), an antimalarial agent, inhibits autophagy by preventing the autophagosome from fusing with the lysosome, emulating the effects of aging. Autophagy is a cellular digestion process that contributes to homeostasis through degradation of cytoplasmic structures in the cell. Aging effects include autophagy impairment, leading to the accumulation of altered proteins and organelles, thus contributing to subsequent cell damage and death. Previous studies in phrenic motor neurons show an age-dependent increase in key autophagy proteins LC3 and p62, reflecting autophagy impairment and autophagosome accumulation. In addition, acute chloroquine administration in old mice decreases maximal transdiaphragmatic pressure generation, suggesting a neuromuscular effect in aging. We hypothesized that treatment with the autophagy inhibitor chloroquine alters pre-synaptic morphology and increases the proportion of denervated diaphragm muscle fibers. Adult male and female 6-month C57BL6 mice were used to examine diaphragm muscle neuromuscular junction (NMJ) morphology and denervation. The autophagy inhibitor chloroquine (10 mg/kg/d) or vehicle was administered via daily intraperitoneal injections for 7 days. Confocal microscopy was used to compare pre- and post-synaptic morphology and denervation. There was evidence of a decrease in pre-synaptic volume without evidence of post-synaptic volume changes in chloroquine treated mice compared to vehicle. As expected, vehicle treated mice did not show evidence of substantial denervation. In contrast, chloroquine treated mice showed an increased proportion of denervated NMJs. The morphological changes observed were similar to those previously reported in the diaphragm muscles of 24-month-old mice. These findings reveal the effects at the neuromuscular junction of inhibiting autophagy and implicate impaired autophagy as a mechanism of aging effects. Supported by NIH R01 AG057052 and Mayo Clinic. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The missing toxic link: Exposure of non-target native marsupials to second-generation anticoagulant rodenticides (SGARs) suggest a potential route of transfer into apex predators

Anticoagulant rodenticides (ARs) are used globally to control rodent pests. Second-generation anticoagulant rodenticides (SGARs) persist in the liver and pose a significant risk of bioaccumulation and secondary poisoning in predators, including species that do not generally consume rodents. As such, there is a clear need to understand the consumption of ARs, particularly SGARs, by non-target consumers to determine the movement of these anticoagulants through ecosystems. We collected and analysed the livers from deceased common brushtail possums (Trichosurus vulpecula) and common ringtail possums (Pseudocheirus peregrinus), native Australian marsupials that constitute the main diet of the powerful owl (Ninox strenua), an Australian apex predator significantly exposed to SGAR poisoning. ARs were detected in 91 % of brushtail possums and 40 % of ringtail possums. Most of the detections were attributed to SGARs, while first-generation anticoagulant rodenticides (FGARs) were rarely detected. SGAR concentrations were likely lethal or toxic in 42 % of brushtail possums and 4 % of ringtail possums with no effect of age, sex, or weight detected in either species. There was also no effect of the landscape type possums were from, suggesting SGAR exposure is ubiquitous across landscapes. The rate of exposure detected in these possums provides insight into the pathway through which ARs are transferred to one of their key predators, the powerful owl. With SGARs entering food-webs through non-target species, the potential for bioaccumulation and broader secondary poisoning of predators is significantly greater and highlights an urgent need for routine rodenticide testing in non-target consumers that present as ill or found deceased. To limit their impact on ecosystem stability the use of SGARs should be significantly regulated by governing agencies.

Effect of ageing on machining performance of grey cast iron and its compensation by cutting speed management

Grey cast iron is known for its poor machinability directly after casting, but attains excellent machining performance after ageing. The present work explores the impact of cutting speed on the performance of pcBN machining for non-aged material. Findings suggest that tool wear can be minimized by identifying an optimal cutting speed that supports the formation of a stable Al2O3 and MnS build-up layer (BUL). Insufficient BUL protection accelerates pcBN wear by diffusion, while at very high speeds protective Al2O3 is replaced by weaker (Fe,Mn)2SiO4 and (Fe,Mn)O, and oxidation accelerates tool wear. The higher mechanical properties of aged GCI facilitate generation of high enough temperatures for stable deposition of Al2O3 BUL.

Habitual Sleep and Muscle Sympathetic Nerve Activity in Humans

Short habitual sleep duration and inadequate sleep effciency are associated with poor cardiovascular health. Although a potential mediator of this relationship is augmented sympathetic activity, only one study to date has assessed the relationship between objectively measured habitual sleep duration and direct muscle sympathetic nerve activity (MSNA) in humans. Moreover, the proportion of resting MSNA that can be independently explained by habitual sleep while controlling for other key variables remains unknown. The purpose of the present study was to assess the independent relationship between total sleep time (TST), sleep effciency (SE), and MSNA in a large population of young males and females. We hypothesized that short TST and low SE would be associated with elevated MSNA and blood pressure. A minimum 7 days of at-home, objective actigraphy sleep monitoring was collected in 66 healthy young adults (35 males, 31 females; 24±1 years; 26±1 kg/m2). In each participant, the average of three seated brachial blood pressures was recorded and used to determine resting mean arterial blood pressure (MAP). All participants underwent an autonomic function test that simultaneously assessed heart rate (HR, electrocardiogram), beat-to-beat blood pressure (finger plethysmography) and MSNA (microneurography) during 10 minutes of quiet rest. Resting MAP (83±1 mmHg), HR (64±1 beats/min) and MSNA (19±1 bursts/min) were normally distributed. Habitual TST was significantly correlated with MSNA (r=-0.265, p=0.032), but was not associated with resting MAP (r=-0.153, p=0.219) or HR (r=-0.205, p=0.098). SE was not associated with any of the outcome variables (all p&gt;0.25). Multiple regression was used to test the independent relationship between TST, MAP, HR, and MSNA while accounting for effects of age, sex, and body mass index (BMI). The regression model significantly predicted MAP (R2=0.253, p=0.001) and MSNA (R2=.211, p=0.005), but not HR (R2=.047, p=0.560). TST did not independently explain any additional variance in MAP (ΔR2=0.004, p=0.562) beyond that ascribed to the effects of age, sex, and BMI. In contrast, TST independently explained an additional 5% of the variance in MSNA (ΔR2=0.053, p=0.048). In a large sample of healthy young males and females, our results indicate that habitual TST explains only a minor proportion of the observed variance in resting MSNA between participants. NIH (AA-024892). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Aging and Hypertension on Ambulatory Blood Pressure, Arterial Stiffness, and Wave Reflection in Mid-life Adults

Introduction: Age-associated increases in blood pressure are partly due to increased arterial stiffness and wave reflection. How these vascular changes during aging contribute to daily fluctuations in blood pressure and hypertension remain to be elucidated. Therefore, the purpose of this study is to compare ambulatory blood pressure, arterial stiffness, and wave reflection between young healthy adults, mid-life adults without hypertension, and mid-life adults with hypertension. Methods: Twenty-five young (age: 26 ± 4 yr and body mass index [BMI]: 23.9 ± 2.5 kg/m2) and 31 mid-life adults (age: 57 ± 4 yr and BMI: 25.4 ± 2.6 kg/m2), free of obesity and major clinical diseases and non-smokers, were included. Hypertension was defined by the current use of anti-hypertension medications or offce seated blood pressure (BP) ≥ 130/80 mmHg. Young adults with hypertension were excluded. Twenty-four-hour ambulatory BP monitoring (Oscar 2™, SunTech Medical®) and assessment of aortic arterial stiffness and wave reflection (SphygmoCor XCEL, AtCor Medical) were performed in all participants. Results: Daytime, nighttime, and 24-hr systolic BP was similar between young adults (YA) and mid-life adults without hypertension (MA; n=12; P&gt;0.9 vs. YA), while mid-life adults with hypertension (MAHTN; n=19) had higher offce, 24-hr, daytime, and nighttime systolic and diastolic BP compared to YA and MA (p&lt;0.01 vs. YA and MA). Compared to YA, MA had higher nighttime diastolic BP (P=0.02). Aortic arterial stiffness, measured by carotid-to-femoral pulse wave velocity, was the highest in MAHTN (p&lt;0.001 vs. YA and P=0&lt;0.01 vs. MA), followed by MA (p&lt;0.01 vs. YA) and YA. Aortic wave reflection, measured by augmentation index and reflection magnitude, was higher in MA and MAHTN compared to YA but was similar between MA and MAHTN (p&lt;0.001 for MA vs. YA; p&lt;0.001 for MAHTN vs. YA; and P&gt;0.9 for MA vs. MAHTN). Conclusions: Our findings indicate that 1) mid-life adults with hypertension had higher ambulatory BP and arterial stiffness than mid-life adults without hypertension and young adults; 2) despite normal offce blood pressure, mid-life adults without hypertension had higher nighttime diastolic BP and arterial stiffness than young adults; and 3) regardless of hypertension, mid-life adults had higher wave reflection than young adults. These findings suggest that 1) vascular aging may present prior to the diagnosis of hypertension based on offce BP; 2) arterial stiffness, rather than wave reflection, may contribute to the development of hypertension during aging; and 3) compared to offce BP, ambulatory BP may be a more sensitive marker of age-associated increases in blood pressure. NIAAA K99/R00 AA028537 to CLH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of age and sex on cardiac function in mice

It is well established that maximal cardiac output declines with advancing age. Age-related decline in cardiac output could result from changes in either systolic or diastolic function that are also apparent at rest. We investigated the effects of age on systolic and diastolic function in male and female mice. Mice were studied at 4-7months and 17-20 months. Echocardiography was performed with FujiFilm Visual Sonics VevoF2 to obtain ejection fraction, fractional shortening, and E/A ratio. In male mice, fractional shortening decreased by 25% (young: 31.26±1.24, old: 23.31±1.82, P=0.002 young v. old) and ejection fraction decreased by 19.77% (young: 58.23±1.63, old: 46.71±3.05, P=0.002 young v. old) with age. In female mice, fractional shortening and ejection were stable with age. E/A decreased with age in both male (young: 1.53±0.09, old: 1.18±0.07, P=0.02 young v. old) and female (young: 1.64±0.08, old: 1.28±0.07, P=0.002 young v. old) mice. These data indicate that systolic function declines with age in male, but not female mice. In contrast, diastolic function declines with age in both male and female mice. Further analysis is needed to determine how these changes in resting cardiac function correlate with changes in exercise capacity in male and female mice. NIH R01HL166591. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.