The sex difference in haemoglobin levels in adults - mechanisms, causes, and consequences

Hematological reference intervals for adult population of Dire Dawa town, East Ethiopia

Background

Reference interval (RI) for hematological parameters is used to interpret laboratory test results in the diagnosis, management and monitoring of hematologic disorders. Several factors including sex, age, dietary patterns, pregnancy status, ethnicity and geographic location affect hematological RIs. However, manufacturers derived reference value is currently in use in most developing countries including Ethiopia. This study aimed to establish hematological RIs for adult population living in Dire Dawa town, East Ethiopia.

Methods

In this cross-sectional study, 513 apparently healthy adults of Dire Dawa town were enrolled from January to March 2019. From these, 342 (171 males and 171 non-pregnant females) were aged 18–65 years while 171 were pregnant women aged 15–49 years. After obtaining written informed consent, 5ml fresh whole blood was collected of which 2ml was used for hematologic analysis using Mindray BC-3000plus hematology analyzer and 3ml for serological tests. The 2.5^th and 97.5^th RI was computed by non-parametric test employing SPSS version 24. P-value <0.05 was considered statistically significant.

Result

Males had significantly higher reference value for most of red cell parameters (Hgb, RBC, HCT, MCH and MCHC) than females (p <0.05), while most of the WBC parameters were significantly higher in females than males. Moreover, non-pregnant women had higher values for most of red cell parameters than pregnant women. Pregnant women had higher WBC parameters than their non-pregnant counterparts.

Conclusion

The hematologic RIs obtained in this study shows variation between genders, between pregnant and non-pregnant women, from the clinical practice currently utilised in Dire Dawa town and from studies conducted in Ethiopia, African countries as well as the Western population. It underscores the need for utilising gender and pregnancy specific, locally derived hematologic RI for better management, diagnosis and monitoring of hematologic disorders for adults of both genders and pregnant women.

Reference intervals of white blood cell parameters for healthy adults in japan

INTRODUCTION

While white blood cell (WBC) parameters have been suggested to depend on ethnicity and gender, reference intervals in healthy Asian populations are limited. The present study established reference intervals of WBC parameters for healthy adults in Japan.

METHODS

A total of 750 healthy adults (447 women and 303 men; 18-67 years old, median 40 years old) at 7 Japanese centers who participated in regular medical checkups entered this study. The WBC parameters were measured using automated hematocytometers and blood film reviews by a manual microscopic examination.

RESULTS

The reference intervals of the WBC parameters according to gender in healthy adults were determined. Age-specific decreases in WBC counts of both gender groups and in neutrophil counts of women were noted. Favorable correlations between the hematocytometer and microscopic methods were found in neutrophils, lymphocytes, and eosinophils but not in monocytes or basophils.

CONCLUSION

This study suggests the need to consider gender and age in the clinical use of reference intervals of WBC parameters.

Dose-Response Relationship between Endurance Training Prescription Variables and Increases in Aerobic Performance of Healthy and Unhealthy Middle and Very Old Individuals Aged 70 Years and Older: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: The objectives of this systematic review and meta-analysis were to quantify the effectiveness of endurance training (ET) on aerobic performance (i.e., peak oxygen uptake (VO_2peak)) in healthy and unhealthy middle and very old adults aged 70 years and older, and to provide dose–response relationships of training prescription variables (in terms of frequency, and volume). Methods: Several scholarly databases (i.e., PubMed/MEDLINE, SpringerLink, ScienceDirect Journals, and Taylor & Francis Online—Journals) were searched, identifying randomized controlled studies that investigated the effectiveness of ET on VO_2peak in older adults. Standardized mean differences (SMD) were calculated. Results: In terms of changes differences between experimental and control group, ET produced significant large effects on VO_2peak performance (SMD = 2.64 (95%CI 0.97–4.31)). The moderator analysis revealed that “health status” variable moderated ET effect onVO_2peak performance. More specifically, ET produced larger SMD magnitudes on VO_2peak performance in healthy compared with unhealthy individuals. With regard to the dose–response relationships, findings from the meta-regression showed that none of the included training prescription variables predicted ET effects on VO_2peak performance. Conclusions: ET is an effective mean for improving aerobic performance in healthy older adults when compared with their unhealthy counterparts.

Sex Differences In Cardiorespiratory Fitness Are Explained By Blood Volume And Oxygen Carrying Capacity

AIMS

Intrinsic sex differences in fundamental blood attributes have long been hypothesized to contribute to the gap in cardiorespiratory fitness between men and women. This study experimentally assessed the role of blood volume and oxygen (O2) carrying capacity on sex differences in cardiac function and aerobic power.

METHODS AND RESULTS

Healthy women and men (n = 60) throughout the mature adult lifespan (42-88 yr) were matched by age and physical activity levels. Transthoracic echocardiography, central blood pressure and O2 uptake were assessed throughout incremental exercise (cycle ergometry). Main outcomes such as left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (Q), and peak O2 uptake (VO2peak), as well as blood volume (BV) were determined with established methods. Measurements were repeated in men following blood withdrawal and O2 carrying capacity reduction matching women's levels. Prior to blood normalization, BV and O2 carrying capacity were markedly reduced in women compared with men (P < 0.001). Blood normalization resulted in a precise match of BV (82.36 ± 9.83 vs. 82.34 ± 7.70 ml·kg-1, P = 0.993) and O2 carrying capacity (12.0 ± 0.6 vs. 12.0 ± 0.7 g·dl-1, P = 0.562) between women and men. Body size-adjusted cardiac filling and output (LVEDV, SV, Q) during exercise as well as VO2peak (30.8 ± 7.5 vs. 35.6 ± 8.7 ml·min-1·kg-1, P < 0.001) were lower in women compared with men prior to blood normalization. VO2peak did not differ between women and men after blood normalization (30.8 ± 7.5 vs. 29.7 ± 7.4 ml·min-1·kg-1, P = 0.551).

CONCLUSIONS

Sex differences in cardiorespiratory fitness are abolished when blood attributes determining O2 delivery are experimentally matched between adult women and men.

TRANSLATIONAL PERSPECTIVE

Low cardiorespiratory fitness is strongly associated with all-cause and cardiovascular mortality in asymptomatic adults independently of traditional risk factors, relationships seemingly enhanced in middle-aged and older women. Yet, whether the primary hematological determinants of cardiorespiratory fitness that were established in studies comprising men explain the difference between sexes remains uncertain. Importantly, blood attributes are amenable to modification and thus potentially translated into effective targets to improve or preserve cardiovascular health in the general population. The present experimental study demonstrates that blood normalization between men and women eliminate sex differences in cardiorespiratory fitness.

The Association between Serum Hemoglobin and Renal Prognosis of IgA Nephropathy

Immunoglobin A (IgA) nephropathy causes chronic kidney disease worldwide. Therefore, identifying risk factors associated with the progression of IgA nephropathy is crucial. Anemia is a common complication of chronic kidney disease; however, few studies have investigated the effect of serum hemoglobin on the renal prognosis of IgA nephropathy. This study aimed to determine the effect of serum hemoglobin on the progression of IgA nephropathy. We retrospectively analyzed 4326 patients with biopsy-proven IgA nephropathy. We evaluated the effect of serum hemoglobin on IgA nephropathy progression using Kaplan-Meier survival analyses, the log-rank test, and the Cox proportional hazards model. The primary end-point was progression of IgA nephropathy, defined as dialysis initiation or kidney transplantation. Serum hemoglobin showed a nonlinear relationship with the progression of IgA nephropathy. The Cox proportional hazards model showed that the risk of progression of IgA nephropathy decreased 0.87 times for every 1.0 g/dL increase in serum hemoglobin. In subgroup analyses, reduced serum hemoglobin was an independent risk factor for IgA nephropathy progression only in women. There was no statistically significant interaction of serum hemoglobin between men and women (P _interaction = 0.177). Results of Sensitivity analysis were robust and consistent. Serum hemoglobin at diagnosis was an independent predictor for IgA nephropathy progression.

Estrogens as regulator of hematopoietic stem cell, immune cells and bone biology

Hematopoietic stem cells provide continuous supply of all the immune cells, through proliferation and differentiation decisions. These decisions are controlled by local bone marrow environment as well as by long-range signals for example endocrine system. Sex dependent differential immunological responses have been described under homeostasis and disease conditions. Females show higher longevity than male counterpart that seems to depend on major female sex hormone, estrogen. There are four estrogens - Estrone (E1), estradiol (E2), Estriol (E3) and Estetrol (E4) that spatially and temporarily present during different female reproductive phases. In this review, we discussed recent updates describing the effects of estrogen on HSC, immune cells and in bone biology. Estradiol (E2) being a major/abundant estrogen is extensively investigated, while effects of other estrogens E1, E3 and E4 are started to unravel recently. Furthermore, clinical effect of estrogen as hormone therapy is discussed in HSC and immune cells perspectives. The data presented in this review is compiled by searches of PubMed, database of American Cancer Society (ACS). We have included article from September 1994 to March 2020 as covering all article in chronological order is not fissile so we included relevant article with substantial information in this specific area of research by using the search term (alone or in combination) estrogen, hematopoietic stem cell, immune cells, gender difference, estrone, estriol, estetrol, therapeutic application, pregnancy, effect on bone.

Oxygen in Red Blood Cell Concentrates: Influence of Donors' Characteristics and Blood Processing

Objective: Unexpectedly wide distribution (<10 to >90%) of hemoglobin oxygen saturation (sO₂) within red cell concentrates (RCCs) has recently been observed. Causes of such variability are not yet completely explained whereas the roles of oxygen and oxidative lesions during the storage of RCCs are known. The objectives of the present study are to characterize sO₂ distribution in RCCs produced in a Swiss blood center and to investigate the influence of processing and donors’ characteristics.

Methods: The level of sO₂ was measured in 1701 leukocyte-depleted RCCs derived from whole blood donations in both top–bottom (TB; component filtered, SAGM) and top–top (TT; whole blood filtration, PAGGSM) RCCs. The sO₂ value was measured non-invasively through the PVC bag prior to storage by resonance Raman spectroscopy. Gender, age, blood type, hemoglobin level, and living altitude of donors, as well as process method and time-to-process were recorded.

Results: Overall, the sO₂ exhibited a wide non-Gaussian distribution with a mean of 51.2 ± 18.5%. Use of top-top kits resulted in a 16% higher sO₂ (P < 0.0001) than with top-bottom ones. Waiting time before processing only had a modest impact, but the blood processing itself reduced the sO₂ by almost 12% (P < 0.0001). sO₂ was also significantly affected by some donors’ characteristics. RCCs from men exhibited 25% higher sO₂ (P < 0.0001) than those donated by women. Multivariate analysis revealed that the apparent correlation observed with hemoglobin level and age was actually due to multicollinearity with the sex variable. Finally, we noticed no significant differences across blood type but found that altitude of residence was associated with the sO₂ (i.e., higher in higher living place).

Conclusion: These data confirm wide sO₂ distribution in RCCs reported recently. The sO₂ was impacted by the processing and also by donors’ characteristics such as the gender and the living altitude, but not by the hemoglobin level, blood group and donor age. This study provides new hints on the factors influencing red blood cells storage lesions, since they are known to be related to O₂ content within the bags, giving clues to better process and to better store RCCs and therefore potentially improve the efficacy of transfusion.

Unique hemoglobin dynamics in female Tibetan highlanders

BACKGROUND

Tibetan highlanders have adapted to hypoxic environments through the development of unique mechanisms that suppress an increase in hemoglobin (Hb) concentration even in high-altitude areas. Hb concentrations generally decrease with increasing age. However, in the highlands, chronic altitude sickness is known to occur in the elderly population. To investigate how aging in a hypoxic environment affects Hb levels in Tibetan highlanders, we focused on the Mustang people, who live above 3500 m. We tried to clarify the pure relationship between aging and Hb levels in a hypoxic environment.

RESULTS

We found that the Hb concentration increased with increasing age in females but not in males. Multivariate analysis showed that age, pulse pressure, the poverty index, and vascular diameter were strongly correlated with the Hb concentration.

CONCLUSIONS

We found unique Hb dynamics among female Tibetan highlanders. As seen in these Hb dynamics, there may be sex-based differences in the adaptive mechanism in Tibetan highlanders.

Is there a gender effect in polycythemia vera?

In recent times, there has been a growing interest in understanding the impact of gender on disease biology and clinical outcomes in Philadelphia-negative chronic myeloproliferative neoplasms. Among those, polycythemia vera (PV) is characterized by increased thrombotic risk, systemic symptoms, and overall reduced survival. Here, we aim to summarize data on whether and to what extent female sex can affect PV biology and outcome. To this end, we will discuss the latest acquisitions in terms of pathogenesis, diagnosis, epidemiology, clinical presentation and symptoms burden, thrombotic risk and related treatment strategies, and prognosis in female patients affected by PV.

Reliability of Capillary Complete Blood Count in Children With Acute Gastroenteritis

Background: To assess the reliability of complete blood count (CBC) in the capillary blood of children with acute gastroenteritis (AGE), with a focus on leukocytes. Methods: This was a retrospective cross-sectional study. Complete blood count was compared between the capillary and venous blood in children admitted to a pediatric gastroenterology department with primary diagnosis of AGE (ICD-10 A09, A08.0, A08.2). Capillary blood was obtained in the emergency room and venous blood was sampled in the ward shortly thereafter during peripheral intravenous line placement. Results: One hundred and forty children were included. The mean (±SD) age and weight of patients were 3.0 ± 2.9 years and 16 ± 9 kg; 26% had leukocytosis. The mean difference between obtaining results of capillary and venous blood tests was 2 ± 1 h. Area under the receiver operating characteristic curve (AUC) for the identification of leukocytosis using the capillary blood was 0.98 (95% CI 0.96-1.0). The sensitivity and specificity were 86 and 98%, respectively (accuracy 95%). The positive and negative predictive values were 94 and 95%, respectively. The intraclass correlation coefficient revealed high concordance between capillary and venous CBC measurements (leukocyte count 0.94, hemoglobin 0.88, erythrocyte count 0.77, hematocrit 0.79, platelet count 0.90). Matched pairs comparisons revealed marginally higher erythrocytes (difference of medians: 0.2 T/L), hemoglobin (0.3 g/dL), hematocrit (1.0%), and platelets (9 G/L) in the capillary blood. Conclusion: Capillary CBC is useful in detecting leukocytosis in children with AGE.

Iron deficiency and pruritus: A cross-sectional analysis to assess its association and relationship

Background:

As generalized pruritus can be a symptom of a systemic disease, iron deficiency may be the underlying internal cause of its symptoms. Because data on the relationship between iron deficiency and generalized chronic pruritus are limited, more research is needed to ensure proper diagnosis and management.

Aims:

To evaluate the prevalence of iron deficiency in patients with generalized chronic pruritus in the southeast region of Rajasthan and to assess the correlation of serum ferritin with iron deficiency variables.

Materials and Methods:

An observational, analytical study was conducted among a total of 200 patients complaining of itching all across the body without any skin lesions for more than 6 weeks and enrolled in the outdoor and indoor Dermatology, Venereology, and Leprology departments of the Government Medical College, Kota. The duration of the study experiment was 1 year from June 2018 to May 2019.

Results:

Females (108; 54%) were more than males (92; 46%) with a ratio of 1.17:1. The mean age of the patients was 37.35 ± 13.56. S. ferritin was found to be below 15 g/L in 58 (29%) patients. Significant correlation was found between S. ferritin and hemoglobin, MCV, MCH, and MCHC, and the P value was <0.05. Maximum number of patients (70; 35%) achieved visual analog scale (VAS) scores between 4 and 9, followed by 50 (25%) patients obtaining scores >9. Similarly, a correlation was found between the VAS score and hemoglobin, MCV, MCH, and MCHC and a statistically significant P value was obtained.

Limitations:

The sample size was small in the study. The overall levels of iron and serum transferrin were not checked, keeping patients' compliance in mind.

Conclusion:

Although statistically significant results were found, limitations were also present in our study; so, further studies for proper diagnosis and management should be conducted in greater depth.

Physiological implications of life at the forest interface of oil palm agriculture: blood profiles of wild Malay civets (Viverra tangalunga)

Agricultural development is a major threat to global biodiversity, and effective conservation actions are crucial. Physiological repercussions of life alongside human-modified landscapes can undermine adaptable species' health and population viability; however, baseline data are lacking for many wildlife species. We assessed the physiological status of a generalist carnivore, the Malay civet (Viverra tangalunga), persisting within an extensively human-modified system in Sabah, Malaysian Borneo. We characterized hematology and serum biochemistry panels from civets sampled across a mosaic landscape comprising tropical forest fragments and oil palm plantations. Intra-population variation in certain blood parameters were explained by expected biological drivers such as sex, age category and sampling season. Furthermore, we determined several erythrocyte measures, immune cell counts and dietary biochemistry markers significantly varied with proximity to oil palm plantation boundaries. These findings were supported by a case study, whereby blood profiles of GPS collared male civets were contrasted based on their exclusive use of forests or use of oil palm plantations. These data provide robust and valuable first insights into this species' physiological status and suggest agricultural landscapes are impacting the persisting population.

Might a high hemoglobin mass be involved in non-cardiogenic pulmonary edema? The case of the chronic maladaptation to high-altitude in the Andes

Exposure to hypoxic environments when ascending at high altitudes may cause life-threatening pulmonary edema (HAPE) due to a rapid accumulation of extracellular fluid flooding in the pulmonary alveoli. In Andeans, high-altitude adaptation occurs at the expense of being more prone to chronic mountain sickness: relative hypoventilation, excess pulmonary hypertension, and secondary polycythemia. Because HAPE prevalence is high in the Andes, we posit the hypothesis that a high hemoglobine mass may increase HAPE risk. In support of it, high intrapulmonary hypertension along with hyperviscosity produced by polycytemia may enhance sear forces and intravascular hemolysis, thus leading to increased acellular hemoglobin and the subsequent damage of the alveolar and endothelial barrier. It is proposed to investigate the relationship between the vaso-endothelial homeostasis and erythropoiesis in the maladaptation to high altitude and HAPE. This research is especially important when reentry HAPE, since rheologic properties of blood changes with rapid ascent to high altitudes.

Serum trace metal association with response to erythropoiesis stimulating agents in incident and prevalent hemodialysis patients

Alterations in hemodialysis patients' serum trace metals have been documented. Early studies addressing associations levels of serum trace metals with erythropoietic responses and/or hematocrit generated mixed results. These studies were conducted prior to current approaches for erythropoiesis stimulating agent (ESA) drug dosing guidelines or without consideration of inflammation markers (e.g. hepcidin) important for regulation of iron availability. This study sought to determine if the serum trace metal concentrations of incident or chronic hemodialysis patients associated with the observed ESA response variability and with consideration to ESA dose response, hepcidin, and high sensitivity C-reactive protein levels. Inductively-coupled plasma-mass spectrometry was used to measure 14 serum trace metals in 29 incident and 79 prevalent dialysis patients recruited prospectively. We compared these data to three measures of ESA dose response, sex, and dialysis incidence versus dialysis prevalence. Hemoglobin was negatively associated with ESA dose and cadmium while positively associated with antimony, arsenic and lead. ESA dose was negatively associated with achieved hemoglobin and vanadium while positively associated with arsenic. ESA response was positively associated with arsenic. Vanadium, nickel, cadmium, and tin were increased in prevalent patients. Manganese was increased in incident patients. Vanadium, nickel, and arsenic increased with time on dialysis while manganese decreased. Changes in vanadium and manganese were largest and appeared to have some effect on anemia. Incident and prevalent patients' chromium and antimony levels exceeded established accepted upper limits of normal.

Transfusion Status in Liver and Kidney Transplantation Recipients-Results from Nationwide Claims Database

BACKGROUND

This study analyzed the status and trends of transfusion and its associated factors among liver and kidney transplantation recipients.

METHODS

A total of 10,858 and 16,191 naïve liver or kidney transplantation recipients from 2008 to 2017 were identified through the National Health Insurance Service database. The prescription code for transfusion and the presence, number, and amount of each type of transfusion were noted. The odds ratios and 95% confidence intervals were determined to identify significant differences in transfusion and blood components by liver and kidney transplantation recipient characteristics.

RESULTS

In this study, 96.4% of liver recipients and 59.7% of kidney recipients received transfusions related to the transplantation operation, mostly platelet and fresh frozen plasma. Higher perioperative transfusion in women and declining transfusion rates from 2008 to 2017 were observed in both liver and kidney recipients. In liver recipients, the transfusion rate in those who received organs from deceased donors was much higher than that in those who received organs from living donors; however, the mortality rate according to transfusion was higher only in recipients of deceased donor organs. In kidney recipients, a higher mortality rate was observed in those receiving transfusion than that in patients without transfusion.

CONCLUSIONS

In Korea, the transfusion rates in liver and kidney recipients were relatively higher than those in other countries. Sociodemographic factors, especially sex and year of transplantation, were associated with transfusion in solid organ recipients, possibly as surrogates for other causal clinical factors.

Impact of Menstrual Blood Loss and Oral Contraceptive Use on Oxygen-carrying Capacity

PURPOSE

The effect of menstrual blood loss on oxygen-carrying capacity remains equivocal. The purpose of this study was to determine the effect of menstrual blood loss on hemoglobin mass in young, healthy women.

METHODS

Twenty-one women (age, 23 ± 6 yr; height, 168 ± 7 cm; weight, 66.1 ± 12.6 kg) with regular menstrual cycles, either using (n = 10) or not using oral contraceptives, participated in the study. Hemoglobin mass was assessed using carbon monoxide rebreathing on three separate occasions over the course of one menstrual cycle.

RESULTS

Visits for women not using oral contraceptives were performed in the early follicular phase (3 ± 1 d after the onset of menses), late follicular phase (1 ± 1 d after the surge of luteinizing hormone in urine), and luteal phase (9 ± 1 d after the late follicular visit). Visits for women using oral contraceptives were performed in the early follicular phase (3 ± 1 d after the onset of menses), late follicular phase (15 ± 3 d after the onset of menses), and luteal phase (9 ± 2 d after the late follicular visit). Hemoglobin mass was not affected by menstrual cycle phase (early follicular, 618 ± 61; late follicular, 610 ± 65; luteal, 607 ± 68 g; P = 0.52). Interestingly, when normalized to weight, hemoglobin mass was 12% higher in women using oral contraceptives in comparison to nonusers (10.0 ± 1.2 vs 8.9 ± 1.2 g·kg, P < 0.05).

CONCLUSION

Menstrual blood loss had no measurable effect on hemoglobin mass in eumenorrheic women. However, oral contraceptive use resulted in a greater oxygen-carrying capacity, potentially leading to a greater maximal oxygen uptake.

Dietary intake of heme iron is associated with ferritin and hemoglobin levels in Dutch blood donors: results from Donor InSight

Whole blood donors, especially frequently donating donors, have a risk of iron deficiency and low hemoglobin levels, which may affect their health and eligibility to donate. Lifestyle behaviors, such as dietary iron intake and physical activity, may influence iron stores and thereby hemoglobin levels. We aimed to investigate whether dietary iron intake and questionnaire-based moderate-to-vigorous physical activity were associated with hemoglobin levels, and whether ferritin levels mediated these associations. In Donor InSight-III, a Dutch cohort study of blood and plasma donors, data on heme and non-heme iron intake (mg/day), moderate-to-vigorous physical activity (10 minutes/day), hemoglobin levels (mmol/L) and ferritin levels (μg/L) were available in 2,323 donors (1,074 male). Donors with higher heme iron intakes (regression coefficients (β) in men and women: 0.160 and 0.065 mmol/L higher hemoglobin per 1 mg of heme iron, respectively) and lower non-heme iron intakes (β: -0.014 and -0.017, respectively) had higher hemoglobin levels, adjusted for relevant confounders. Ferritin levels mediated these associations (indirect effect (95% confidence interval) in men and women respectively: 0.074 (0.045; 0.111) and 0.061 (0.030; 0.096) for heme and -0.003 (-0.008;0.001) and -0.008 (-0.013;-0.003) for non-heme). Moderate-to-vigorous physical activity was negatively associated with hemoglobin levels in men only (β: -0.005), but not mediated by ferritin levels. In conclusion, higher heme and lower non-heme iron intake were associated with higher hemoglobin levels in donors, via higher ferritin levels. This indicates that donors with high heme iron intake may be more capable of maintaining iron stores to recover hemoglobin levels after blood donation.

Blood-brain barrier permeability measurement by biexponentially modeling whole-brain arterial spin labeling data with multiple T2 -weightings

Blood-brain barrier (BBB) permeability assessment remains of ongoing interest in clinical practice and research. Transitions between intravascular (IV) and extravascular (EV) gray matter (GM) compartments may provide information regarding the microstructural status of the BBB. Due to different transverse relaxation times (T₂ ) of water protons in vessels and GM, it is possible to determine the compartment in which these protons are located. This work presents and investigates the feasibility of a simplified analytical approach for compartmentalizing the proportions of magnetically marked water protons into IV and EV GM components by biexponentially modeling T₂ -weighted arterial spin labeling (ASL) data. Numerous model assumptions were used to stabilize the fit and achieve in vivo applicability. Particularly, transverse relaxation times of IV and EV water protons were determined from the analysis of two supporting T₂ -weighted ASL measurements, utilizing a monoexponential signal model. This stabilized a two-parameter biexponential fit of ASL data with T₂ preparation (PLD = 0.9/1.2/1.5/1.8 s, TE_T2Prep  = 0/30/40/60/80/120/160 ms), which thereby robustly provided estimates of the IV and EV compartment fractions. Experiments were conducted with three healthy volunteers in a 3 T scanner. Averaged over all subjects, the labeled water protons inherit T_2,IV  = 200 ± 18 ms initially and adapt T_2,EV  = 91 ± 2 ms with a longer retention time in cerebral structures. Accordingly, the EVlocated ASL signal fraction rises with increasing PLD from 0.31 ± 0.11 at the shortest PLD of 0.9 s to 0.73 ± 0.02 at the longest PLD of 1.8s. These results indicate a transition of the water protons from IV to EV space. The findings support the potential of biexponential modeling for compartmentalizing ASL spin fractions between IV and EV space. The novel integration of monoexponential parameter estimates stabilizes the two-compartment model fit, suggesting that this technique is suitable for robustly estimating the BBB permeability in vivo.

Sex differences in fatigability following exercise normalised to the power-duration relationship

KEY POINTS

Knee-extensors demonstrate greater fatigue resistance in females compared to males during single-limb and whole-body exercise. For single-limb exercise, the intensity-duration relationship is different between sexes, with females sustaining a greater relative intensity of exercise. This study established the power-duration relationship during cycling, then assessed fatigability during critical power-matched exercise within the heavy and severe intensity domains. When critical power and the curvature constant were expressed relative to maximal ramp test power, no sex difference was observed. No sex difference in time to task failure was observed in either trial. During heavy and severe intensity cycling, females experienced lesser muscle de-oxygenation. Following both trials, females experienced lesser reductions in knee-extensor contractile function, and following heavy intensity exercise, females experienced less reduction in voluntary activation. These data demonstrate that whilst the relative power-duration relationship is not different between males and females, the mechanisms of fatigability during critical power-matched exercise are mediated by sex.

ABSTRACT

Due to morphological differences, females demonstrate greater fatigue resistance of locomotor muscle during single-limb and whole-body exercise modalities. Whilst females sustain a greater relative intensity of single-limb, isometric exercise than males, limited investigation has been performed during whole-body exercise. Accordingly, this study established the power-duration relationship during cycling in 18 trained participants (eight females). Subsequently, constant-load exercise was performed at critical power (CP)-matched intensities within the heavy and severe domains, with the mechanisms of fatigability assessed via non-invasive neurostimulation, near-infrared spectroscopy and pulmonary gas exchange during and following exercise. Relative CP (72 ± 5 vs. 74 ± 2% P_max , P = 0.210) and curvature constant (51 ± 11 vs. 52 ± 10 J P_max ^-1 , P = 0.733) of the power-duration relationship were similar between males and females. Subsequent heavy (P = 0.758) and severe intensity (P = 0.645) exercise time to task failures were not different between sexes. However, females experienced lesser reductions in contractile function at task failure (P ≤ 0.020), and greater vastus lateralis oxygenation (P ≤ 0.039) during both trials. Reductions in voluntary activation occurred following both trials (P < 0.001), but were less in females following the heavy trial (P = 0.036). Furthermore, during the heavy intensity trial only, corticospinal excitability was reduced at the cortical (P = 0.020) and spinal (P = 0.036) levels, but these reductions were not sex-dependent. Other than a lower respiratory exchange ratio in the heavy trial for females (P = 0.039), no gas exchange variables differed between sexes (P ≥ 0.052). Collectively, these data demonstrate that whilst the relative power-duration relationship is not different between males and females, the mechanisms of fatigability during CP-matched exercise above and below CP are mediated by sex.

The Association between Serum Bilirubin Levels and Colorectal Cancer Risk: Results from the Prospective Cooperative Health Research in the Region of Augsburg (KORA) Study in Germany

Emerging studies have suggested that bilirubin, particularly unconjugated bilirubin (UCB), has substantial anti-inflammatory and antioxidant properties that protect against oxidative stress-associated diseases such as cancer. Few observational studies have investigated the etiological role of bilirubin in colorectal cancer (CRC) development. In this case-control study, nested in the population-based prospective cohort of the Cooperative Health Research in the Region of Augsburg (KORA) study in south Germany, pre-diagnostic circulating UCB concentrations were measured by high-performance liquid chromatography in 77 CRC cases and their individually matched controls. Multivariable unconditional logistic regression was used to estimate the odds ratios (OR) and 95% confidence intervals (CI) for associations between log-transformed UCB levels (log-UCB), standardized per one-standard-deviation (one-SD) increment, and CRC risk. The models were a priori stratified by sex based on previous evidence. In the fully adjusted models, each one-SD increment in log-UCB was indicative of a positive association with CRC risk (OR, 1.20; 95% CI, 0.52-2.79) among men, and of an inverse association (OR, 0.76; 95% CI, 0.34-1.84) among women (Pheterogeneity = 0.4 for differences between men and women). We found little evidence for sex-specific associations of circulating bilirubin with CRC risk, and further studies are needed to confirm or refute the potential associations.

Circulating bilirubin levels and risk of colorectal cancer: serological and Mendelian randomization analyses

BACKGROUND

Bilirubin, a byproduct of hemoglobin breakdown and purported anti-oxidant, is thought to be cancer preventive. We conducted complementary serological and Mendelian randomization (MR) analyses to investigate whether alterations in circulating levels of bilirubin are associated with risk of colorectal cancer (CRC). We decided a priori to perform analyses separately in men and women based on suggestive evidence that associations may differ by sex.

METHODS

In a case-control study nested in the European Prospective Investigation into Cancer and Nutrition (EPIC), pre-diagnostic unconjugated bilirubin (UCB, the main component of total bilirubin) concentrations were measured by high-performance liquid chromatography in plasma samples of 1386 CRC cases and their individually matched controls. Additionally, 115 single-nucleotide polymorphisms (SNPs) robustly associated (P < 5 × 10-8) with circulating total bilirubin were instrumented in a 2-sample MR to test for a potential causal effect of bilirubin on CRC risk in 52,775 CRC cases and 45,940 matched controls in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colon Cancer Family Registry (CCFR), and the Colorectal Transdisciplinary (CORECT) study.

RESULTS

The associations between circulating UCB levels and CRC risk differed by sex (Pheterogeneity = 0.008). Among men, higher levels of UCB were positively associated with CRC risk (odds ratio [OR] = 1.19, 95% confidence interval [CI] = 1.04-1.36; per 1-SD increment of log-UCB). In women, an inverse association was observed (OR = 0.86 (0.76-0.97)). In the MR analysis of the main UGT1A1 SNP (rs6431625), genetically predicted higher levels of total bilirubin were associated with a 7% increase in CRC risk in men (OR = 1.07 (1.02-1.12); P = 0.006; per 1-SD increment of total bilirubin), while there was no association in women (OR = 1.01 (0.96-1.06); P = 0.73). Raised bilirubin levels, predicted by instrumental variables excluding rs6431625, were suggestive of an inverse association with CRC in men, but not in women. These differences by sex did not reach formal statistical significance (Pheterogeneity ≥ 0.2).

CONCLUSIONS

Additional insight into the relationship between circulating bilirubin and CRC is needed in order to conclude on a potential causal role of bilirubin in CRC development.

The effect of sleep duration on hemoglobin and hematocrit: observational and Mendelian randomization study

STUDY OBJECTIVE

Observationally sleep duration is positively associated with hemoglobin (Hgb), whether this association is causal and consistent by sex remains unclear. Here, we assessed the association of sleep duration with Hgb and hematocrit (Hct) observationally in late adolescence in a population-representative Chinese birth cohort "Children of 1997" with validation using Mendelian randomization (MR) in adults.

METHODS

In the "Children of 1997" birth cohort (recruited = 8327, included = 3144), we used multivariable linear regression to assess the adjusted associations of sleep duration (measured as time in bed) with Hgb and Hct at 17.5 years and any sex differences. Using two-sample MR, we assessed the effect of sleep duration on Hgb and Hct, based on 61 single nucleotide polymorphisms (SNPs) applied to genome-wide association studies of Hgb and Hct in adults (n = 361 194).

RESULTS

Observationally, self-reported sleep duration was positively associated with Hct (0.034 standard deviations [SDs] per hour, 95% confidence interval [CI] 0.019 to 0.049), but not with Hgb. Using MR longer sleep increased Hct (0.077 SD per hour, 95% CI 0.035 to 0.119) and Hgb (0.065 SD per hour, 95% CI 0.020 to 0.109) using Mendelian randomization pleiotropy residual sum and outlier (MR PRESSO), with more pronounced associations in men.

CONCLUSIONS

Our novel findings indicate sleep increases both Hgb and Hct, particularly in men, perhaps contributing to its restorative qualities. Potential difference by sex and the implications of these findings warrant investigation.

Erythrocyte Characteristics and the Risk of Depression in Late Life: A Population-Based Prospective Study

OBJECTIVES

Inflammation and vascular dysregulation may contribute to the development of depression and impose a burden on erythropoiesis. This study aimed to identify the association of erythrocyte indices with the severity of depressive symptoms and risk of developing depressive disorders in the older people.

DESIGN

A prospective cohort study on a randomly sampled Korean older population; the baseline assessment from 2010 to 2012, the first follow-up assessment from 2012 to 2014, and the second follow-up assessment from 2014 to 2016 (mean follow-up duration = 3.4 years).

SETTING

A nationwide and community-based cohort.

PARTICIPANTS

A total of 4451 Koreans aged 60 years or older.

METHODS

We examined the associations of the values and changes in mean corpuscular volume, mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) with the risk of prevalent and incident depression using logistic regression analyses.

RESULTS

High MCH and MCHC in female participants and high MCHC in male participants were associated with high geriatric depression scale scores and risk of prevalent depression. In female participants, high- and middle-MCH tertile groups showed a 2.68- and 2.34-fold higher risk of incident depression than did the low tertile group. In male participants, the high-MCH tertile group showed a 1.79-fold higher risk of incident depression than did the low tertile group. In both sexes, the participants whose MCV changed to the high or middle tertile or remained in the high or middle tertile during the follow-up period, and whose MCH increased to the high tertile or remained in the high tertile, were at a higher risk of incident depression.

CONCLUSIONS AND IMPLICATIONS

Changes in erythrocyte may be associated with the risk of depression in older adults. This prospective study proposes a new perspective of the old hematologic parameters for understanding the pathophysiology of late-life depression.

Impact of Genetically Predicted Red Blood Cell Traits on Venous Thromboembolism: Multivariable Mendelian Randomization Study Using UK Biobank

Background

Red blood cell (RBC) transfusion and erythropoiesis‐stimulating agent administration are cornerstones of clinical practice, yet concerns exist as to potential increased risk of thrombotic events. This study aims to identify RBC traits most relevant to venous thromboembolism (VTE) and assess their genetically predicted effects on VTE in the general population.

Methods and Results

We used multivariable mendelian randomization with bayesian model averaging for exposure selection. We obtained genetic variants predicting any of 12 RBC traits from the largest genome‐wide association study of hematological traits (173 480 participants of European ancestry) and applied them to the UK Biobank (265 424 white British participants). We used univariable mendelian randomization methods as sensitivity analyses for validation. Among 265 424 unrelated participants in the UK Biobank, there were 9752 cases of VTE (4490 men and 5262 women). Hemoglobin was selected as the plausible important RBC trait for VTE (marginal inclusion probability=0.91). The best‐fitting model across all RBC traits contained hemoglobin only (posterior probability=0.46). Using the inverse variance–weighted method, genetically predicted hemoglobin was positively associated (odds ratio, 1.21 per g/dL unit of hemoglobin; 95% CI, 1.05–1.41) with VTE. Sensitivity analyses (mendelian randomization–Egger, weighted median, and mendelian randomization pleiotropy residual sum and outlier test) gave consistent estimates.

Conclusions

Endogenous hemoglobin is the key RBC trait causing VTE, with a detrimental effect in the general population on VTE. Given men have higher hemoglobin than women, this finding may help explain the sexual disparity in VTE rates. The benefits of therapies and other factors that raise hemoglobin need to be weighed against their risks.

Free breathing lung T1 mapping using image registration in patients with idiopathic pulmonary fibrosis

PURPOSE

To assess the use of image registration for correcting respiratory motion in free breathing lung T₁ mapping acquisition in patients with idiopathic pulmonary fibrosis (IPF).

THEORY AND METHODS

The method presented used image registration to synthetic images during postprocessing to remove respiratory motion. Synthetic images were generated from a model of the inversion recovery signal of the acquired images that incorporated a periodic lung motion model. Ten healthy volunteers and 19 patients with IPF underwent 2D Look-Locker T₁ mapping acquisition at 1.5T during inspiratory breath-hold and free breathing. Eight healthy volunteers and seven patients with IPF underwent T₁ mapping acquisition during expiratory breath-hold. Fourteen patients had follow-up scanning at 6 months. Dice similarity coefficient (DSC) was used to evaluate registration efficacy.

RESULTS

Image registration increased image DSC (P < .001) in the free breathing inversion recovery images. Lung T₁ measured during a free breathing acquisition was lower in patients with IPF when compared with healthy controls (inspiration: P = .238; expiration: P = .261; free breathing: P = .021). Measured lung T₁ was higher in expiration breath-hold than inspiration breath-hold in healthy volunteers (P < .001) but not in patients with IPF (P = .645). There were no other significant differences between lung T₁ values within subject groups.

CONCLUSIONS

The registration technique significantly reduced motion in the Look-Locker images acquired during free breathing and may improve the robustness of lung T₁ mapping in patients who struggle to hold their breath. Lung T₁ measured during a free breathing acquisition was significantly lower in patients with IPF when compared with healthy controls.

Establishment of Reference Intervals for Blood Cell Analysis of Adult Tibetan Farmers and Herdsmen Over 4100 Meters Above Sea Level in Tibet Based on a Health Survey

Yang, Wei, Song Zhao, Dan Liu, Guangming Su, Dongwei Zhang, Gui La, Yu Deng, Pian Ni, and Xiuru Guan. Establishment of reference intervals for blood cell analysis of adult Tibetan farmers and herdsmen over 4100 meters above sea level in Tibet based on a health survey. High Alt Med Biol. 21:223-231, 2020. Background: High altitude has substantial influence on reference intervals (RIs) for blood cell analysis. However, the currently used RIs for blood cell analysis in China have not been investigated in people from high-altitude areas, which may potentially cause confusion regarding disease diagnosis and treatment of Tibetan farmers and herdsmen from high-altitude areas. Therefore, it is necessary to establish blood cell analysis RIs that are suitable for people in high-altitude areas. Methods: In total, 1145 healthy Tibetan farmers and herdsmen were recruited who have lived at an altitude from 4100 to 5280 m in Kangma, Tibet, for a long time. The C28-A3 guideline from the Clinical and Laboratory Standards Institute was used to establish the RIs for hemoglobin (HGB) concentrations and red blood cell (RBC), white blood cell (WBC), and platelet (PLT) counts from the blood results of Tibetan participants. Results: There were significant gender differences in blood cell RIs for Tibetan farmers and herdsmen who lived above 4100 m above sea level in Kangma, Tibet. Compared with currently used RIs in China, RIs for HGB concentrations and RBCs in Kangma were significantly higher, whereas WBCs were similar and PLT count was lower. Conclusions: The currently used RIs in China may not be applicable to adult Tibetan farmers and herdsmen above 4100 m in Tibet. The newly obtained RIs can supplement the currently used RIs.

Hyperlactatemia in diabetic ketoacidosis is common and can be prolonged: lactate time-series from 25 intensive care admissions

Hyperlactatemia is a documented complication of diabetic ketoacidosis (DKA). Lactate responses during DKA treatment have not been studied and were the focus of this investigation. Blood gas and electrolyte data from 25 DKA admissions to ICU were sequenced over 24 h from the first Emergency Department sample. Hyperlactatemia (> 2 mmol/L) was present in 22 of 25 DKA presentations [mean concentration = 3.2 mmol/L]. In 18 time-series (72%), all concentrations normalized in ≤ 2.6 h (aggregate decay t¹/₂ = 2.29 h). In the remaining 7 (28%), hyperlactatemia persisted > 12 h. These were females (P = 0.04) with relative anemia (hemoglobin concentrations 131 v 155 g/L; P = 0.004) and lower nadir glucose concentrations (5.2 v 8.0 mmol/L, P = 0.003). Their aggregate glucose decay curve commenced higher (42 mmol/L v 29 mmol/L), descending towards a lower asymptote (8 mmol/L v 11 mmol/L). Tonicity decay showed similar disparities. There was equivalent resolution of metabolic acidosis and similar lengths of stay in both groups. Hyperlactatemia is common in DKA. Resolution is often rapid, but high lactates can persist. Females with high glucose concentrations corrected aggressively are more at risk. Limiting initial hyperglycemia correction to ≥ 11 mmol/L may benefit.

Association between anemia and renal prognosis in autosomal dominant polycystic kidney disease: a retrospective study

BACKGROUND

Though anemia is a sign of poor renal prognosis in chronic kidney disease (CKD), hemoglobin (Hb) levels are typically higher in autosomal dominant polycystic kidney disease (ADPKD) than in other kidney diseases, and anemia has not been examined as a potential prognosticator. Thus, we investigated anemia as a factor for renal prognosis in ADPKD.

METHODS

In total, 115 non-dialysis patients, 48 men and 67 women, with ADPKD were evaluated. The renal outcome of a 50% reduction in the estimated glomerular filtration rate or renal replacement therapy was examined using the Cox regression analysis and Kaplan-Meier analysis.

RESULTS

Patients were followed for a median of 5.5 years and 50 patients had reached the end point. The mean age of the patients at the first visit was 45.9 ± 13.3 years. The overall mean Hb was 12.90 ± 1.85 g/dL, and the mean Hb in men and women was 13.82 ± 1.72 g/dL and 12.25 ± 1.65 g/dL, respectively. Hb levels and uric protein content were statistically significant factors for poor renal prognosis, while hypertension and genetic mutations failed to reach significance. Furthermore, statistical significance was found in men with Hb < 12 g/dL and in women with Hb < 11 g/dL. Anemia had significant association with kidney disease progression in patients with ADPKD.

CONCLUSIONS

We found that anemia might be a factor for poor renal prognosis in ADPKD. Furthermore, a sex difference was found, wherein men with Hb < 12 g/dL and women with Hb < 11 g/dL were at risk of renal disease progression.

Association of estimated plasma volume status with hemodynamic and echocardiographic parameters

BACKGROUND

Estimated plasma volume status (ePVS) has diagnostic and prognostic value in patients with heart failure (HF). However, it remains unclear which congestion markers (i.e., biological, imaging, and hemodynamic markers) are preferentially associated with ePVS. In addition, there is evidence of sex differences in both the hematopoietic process and myocardial structure/function.

METHOD AND RESULTS

Patients with significant dyspnea (NYHA ≥ 2) underwent echocardiography and lung ultrasound within 4 h prior to cardiac catheterization. Patients were divided according to tertiles based on sex-specific ePVS thresholds calculated from hemoglobin and hematocrit measurements using Duarte's formula. Among the 78 included patients (median age 74.5 years; males 69.2%; HF 48.7%), median ePVS was 4.1 (percentile_25-75 = 3.7-4.9) mL/g in males (N = 54) and 4.8 (4.4-5.3) mL/g in females (N = 24). Patients with the highest ePVS had more frequently HF, higher NT-proBNP, larger left atrial volume, and higher E/e' (all p values < 0.05), but no difference in inferior vena cava diameter or pulmonary congestion assessed by lung ultrasound (all p values > 0.10). In multivariable analysis, higher E/e' and lower diastolic blood pressure were significantly associated with increased ePVS. The association between ePVS and congestion variables was not sex-dependent except for left-ventricular end-diastolic pressure, which was only correlated with ePVS in females (Spearman Rho = 0.53, p < 0.01 in females and Spearman Rho = - 0.04, p = 0.76 in males; p_interaction = 0.08).

CONCLUSION

ePVS is associated with E/e' regardless of sex, while only associated with invasively measured left-ventricular end-diastolic pressure in females. These results suggest that ePVS is preferably associated with left-sided hemodynamic markers of congestion.

tmap: an integrative framework based on topological data analysis for population-scale microbiome stratification and association studies

Untangling the complex variations of microbiome associated with large-scale host phenotypes or environment types challenges the currently available analytic methods. Here, we present tmap, an integrative framework based on topological data analysis for population-scale microbiome stratification and association studies. The performance of tmap in detecting nonlinear patterns is validated by different scenarios of simulation, which clearly demonstrate its superiority over the most commonly used methods. Application of tmap to several population-scale microbiomes extensively demonstrates its strength in revealing microbiome-associated host or environmental features and in understanding the systematic interrelations among their association patterns. tmap is available at https://github.com/GPZ-Bioinfo/tmap.

Sex-specific Associations Between Serum Hemoglobin Levels and the Risk of Cause-specific Death in Korea Using the National Health Insurance Service-National Health Screening Cohort (NHIS HEALS)

Objectives

The purpose of this study was to determine the associations between blood hemoglobin (Hgb) levels and the risk of death by specific causes.

Methods

Using the National Health Insurance Services-National Health Screening Cohort (n=487 643), we classified serum Hgb levels into 6 sex-specific groups. Cox regression analysis was used to analyze the associations between Hgb levels and the risk of cause-specific death.

Results

Hgb levels in male population showed a U-shaped, J-shaped, or inverse J-shaped association with the risk of death from ischemic heart disease, acute myocardial infarction, liver cancer, cirrhosis and chronic obstructive pulmonary disease (COPD) (all non-linear p<0.05; hazard ratio [HR]; 95% confidence interval [CI]) for the lowest and the highest Hgb levels for the risk of each cause of death in male population: HR, 1.14; 95% CI, 0.98 to 1.34; HR, 2.87; 95% CI, 1.48 to 5.57; HR, 1.16; 95% CI, 0.96 to 1.40; HR, 3.05; 95% CI, 1.44 to 6.48; HR, 1.36; 95% CI, 1.18 to 1.56; HR, 2.11; 95% CI, 1.05 to 4.26; HR, 3.64; 95% CI, 2.49 to 5.33; HR, 5.97; 95% CI, 1.44 to 24.82; HR, 1.62; 95% CI, 1.14 to 2.30; HR, 3.84; 95% CI, 1.22 to 12.13, respectively), while in female population, high Hgb levels were associated with a lower risk of death from hypertension and a higher risk of death from COPD (overall p<0.05; HR, 1.86; 95% CI, 1.29 to 2.67 for the lowest Hgb levels for hypertension; overall p<0.01, HR, 6.60; 95% CI, 2.37 to 18.14 for the highest Hgb levels for COPD). For the risk of lung cancer death by Hgb levels, a linear negative association was found in male population (overall p<0.01; the lowest Hgb levels, HR, 1.17; 95% CI, 1.05 to 1.33) but an inverse J-shaped association was found in female population (non-linear p=0.01; HR, 1.25; 95% CI, 0.96 to 1.63; HR, 2.58; 95% CI, 1.21 to 5.50).

Conclusions

Both low and high Hgb levels were associated with an increased risk of death from various causes, and some diseases showed different patterns according to sex.

Single Nucleotide Polymorphisms in PEMT and MTHFR Genes are Associated with Omega 3 and 6 Fatty Acid Levels in the Red Blood Cells of Children with Obesity

Polyunsaturated fatty acids (PUFAs) play important roles in health and disease. PUFA levels are influenced by nutrition and genetic factors. The relationship between PUFA composition in red blood cells (RBCs) and genetic variations involved in PUFA metabolism has not been investigated in children with obesity. This study evaluated the association between several genetic variations and PUFA levels in RBCs in children with obesity. One hundred ninety-six children with obesity (101 females, 95 males) were evaluated using anthropometric measurements, dietary intakes, plasma and RBC PUFA quantification, blood biochemistry, and 55 single nucleotide polymorphisms within 14 genes. phosphatidylethanolamine N-methyltransferase (PEMT) rs1109859 and methylenetetrahydrofolate reductase gene (MTHFR) rs4846052 genotypes were associated with PUFA levels in RBCs. PUFA intake did not influence the RBC eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels. Higher RBC DHA and EPA levels were observed for PEMT rs1109859 GG and GA genotypes versus the AA genotype. Higher levels of RBC DHA, EPA, arachidonic acid (ARA), and linoleic acid (LA) and were observed for MTHFR rs4846052 TT genotype versus TC and CC genotypes. Genetic variations in PEMT rs1109859 and MTHFR rs4846052 were associated with different PUFA levels in RBC membranes and are estimators for PUFA species in RBCs. Further research is needed to establish whether these genotype-specific alterations are specific to overweight children.

The Relationship Between Alcohol and Glycohemoglobin: A Biopsychosocial Perspective

With the rising prevalence of type 2 diabetes mellitus (T2DM), there is debate regarding biological and psychosocial risk factors. While it is well established that alcohol lowers glycohemoglobin (HbA1c) levels, it is less clear whether alcohol consumption is protective of T2DM. It is also unclear how gender and ethnicity influence the utility of HbA1c screening as a tool for T2DM diagnosis, particularly in the context of alcohol use. This cross-sectional study utilized the National Health and Nutrition Examination Survey 2013–2014 dataset and was restricted to adults 20 years and older, nonpregnant, and not on antihypertensive medication (n = 4299) to evaluate the relationship between alcohol use and HbA1c. A multilinear regression model controlled for gender, ethnicity, education level, body mass index, and age. After controlling for covariates, both moderate (β = −0.073; p = 0.033) and heavy drinking (β = −0.167; p < 0.001) are associated with reduced HbA1c levels. Additionally, female gender is a significant negative predictor of HbA1c (β = −0.052; p = 0.024) and all ethnic groups have higher levels of HbA1c compared with non-Hispanic whites. Plausible biological mechanisms are discussed. The clinical utility of HbA1c as a screening tool for T2DM without considering alcohol use, gender, and ethnicity may lead to diagnostic errors. Individualized approaches and focused efforts toward health equity are needed to address rising rates of T2DM.

An Integrative Proteomic/Lipidomic Analysis of the Gold Nanoparticle Biocorona in Healthy and Obese Conditions

Introduction: When nanoparticles (NPs) enter a physiological environment, a coating of biomolecules or biocorona (BC) forms on the surface. Formation of the NP-BC is dependent on NP properties, the physiological environment, and time. The BC influences NP properties and biological interactions such as cellular internalization, immune responses, biodistribution, and others, leading to pharmacological and toxicological consequences. To date, examination of the NP-BC has focused primarily on protein components and healthy conditions. Therefore, we evaluated the protein and lipid content of BCs that formed on physicochemically distinct gold nanoparticles (AuNPs) under healthy and obese conditions. A comprehensive understanding of the NP-BC is necessary for the translation of in vitro toxicity assessments to clinical applications. Materials and Methods: AuNPs with two coatings (poly-N-vinylpyrrolidone [PVP] or citrate) and diameters (20 or 100 nm) were incubated in pooled human serum, and an integrated proteomic/lipidomic approach was used to evaluate BC composition. Macrophages were utilized to evaluate differential immune responses due to variations in the AuNP-BC. Results: AuNPs form distinct BCs based on physicochemical properties and the surrounding environment, with the obese BC containing more proteins and fewer lipids than the healthy BC. Differential macrophage inflammatory responses were observed based on AuNP properties and BC composition. Discussion and Conclusion: Overall, these findings demonstrate that AuNP size and coating, as well as physiological environment, influence the protein and lipid composition of the BC, which impacts cellular responses following exposure. These findings demonstrate that incorporation of BCs representing distinct physiological conditions may enhance the translatability of nanosafety in vitro studies.

No longer beeting around the bush: a review of potential sex differences with dietary nitrate supplementation

Over the last decade there has been substantial interest in the health and athletic performance benefits associated with acute and chronic dietary nitrate (NO3–) supplementation. Dietary NO3–, commonly found in leafy green and root vegetables, undergoes sequential reduction to nitrite and nitric oxide (NO) via the enterosalivary circulation. Importantly, NO has been shown to elicit a number of biological effects ranging from blood pressure reduction to improved exercise economy and athletic performance. However, a common absence within biological research is the lack of female participants, which is often attributed to the added complexity of hormonal fluctuations throughout the menstrual cycle. Despite mounting evidence supporting significant anthropometric, metabolic, and physiological differences between the sexes, this problem extends to the field of dietary NO3– supplementation where women are underrepresented as research participants. This review examines the existing dietary NO3– supplementation research with regards to dietary NO3– pharmacokinetics, resting blood pressure, exercise economy and performance, and mechanisms of action. It also provides evidence and rationale for potential sex differences in response to dietary NO3– supplementation and future directions for this field of research.

Novelty Dietary NO3– supplementation has been shown to have positive impacts on health and athletic performance in generally male populations. However, women are underrepresented in dietary NO3– supplementation research. The present evidence suggests that sex differences exist in response to dietary NO3– supplementation and this review highlights avenues for future research.

Modelling the relationships between haemoglobin oxygen affinity and the oxygen cascade in humans

KEY POINTS

Haemoglobin affinity is an integral concept in exercise physiology that impacts oxygen uptake, delivery and consumption. How chronic alterations in haemoglobin affinity impact physiology is unknown. Using human haemoglobin variants, we demonstrate that the affinity of haemoglobin for oxygen is highly correlated with haemoglobin concentration. Using the Fick equation, we model how altered haemoglobin affinity and the associated haemoglobin concentration influences oxygen consumption at rest and during exercise via alterations in cardiac output and mixed-venous P O 2 . The combination of low oxygen affinity haemoglobin and reduced haemoglobin concentration seen in vivo may be unable to support oxygen uptake during moderate or heavy exercise.

ABSTRACT

The physiological implications, with regard to exercise, of altered haemoglobin affinity for oxygen are not fully understood. Data from the Mayo Clinic Laboratories database of rare human haemoglobin variants reveal a strong inverse correlation (r = -0.82) between blood haemoglobin concentration and P₅₀ , an index of oxygen affinity [Hb = -0.3135(P₅₀ ) + 23.636]. In the present study, observed P₅₀ values for high, normal and low oxygen-affinity haemoglobin variants (13, 26 and 39 mmHg) and corresponding haemoglobin concentrations (19.5, 15.5 and 11.4 g dL^-1 respectively) are used to model oxygen consumption as a fraction of delivery at rest ( V ̇ O 2  = 0.25 L min^-1 , cardiac output = 5.70 L min^-1 ) and during exercise ( V ̇ O 2  = 2.75 L min^-1 , cardiac output = 18.9 l min^-1 ). With high-affinity haemoglobin, the model shows that normal levels of oxygen consumption can be achieved at rest and during exercise at the assumed cardiac output levels, with reduced oxygen extraction both at rest (16.8% high affinity vs. 21.7% normal) and during exercise (55.8% high affinity vs. 72.2% normal). With low-affinity haemoglobin, which predicts low haemoglobin concentration, oxygen consumption at rest can be sustained with the assumed cardiac output, with increased oxygen extraction (31.1% low affinity vs. 21.7% normal). However, exercise at 2.75 l min^-1 cannot be achieved with the assumed cardiac output, even with 100% oxygen extraction. In conclusion, the model indicates chronic alterations in P₅₀ associate directly with Hb concentration, highlighting that human Hb variants can serve as 'experiments of nature' to address fundamental hypotheses on oxygen transport and exercise.

Hemoglobin concentration and anemia diagnosis in venous and capillary blood: biological basis and policy implications

Anemia is an important public health challenge and accurate prevalence estimates are needed for program planning and tracking progress. While venous blood assessed by automated hematology analyzers is considered gold standard, most population‐based surveys use point‐of‐care diagnostics and capillary blood to estimate population prevalence of anemia. Several factors influence hemoglobin (Hb) concentration, including human and analytic error, analysis method, and type of instrument, but it is unclear whether biological variability exists between venous and capillary blood. The objective of this paper was to systematically review sources of Hb variability and the potential biological basis for venous and capillary differences. We use data from a recent survey in the state of Uttar Pradesh, India, to illustrate the implications on anemia prevalence estimates. Significant differences in Hb concentration between capillary and venous blood samples are common. Most but not all find capillary Hb concentration to be higher than venous. Instrument/method variability and human error play an important role, but cannot fully explain these differences. A normative guide to data collection, analysis, and anemia diagnosis is needed to ensure consistent and appropriate interpretation. Further research is needed to fully understand the biological implications of venous and capillary Hb variability.

Transwomen in elite sport: scientific and ethical considerations

The inclusion of elite transwomen athletes in sport is controversial. The recent International Olympic Committee (IOC) (2015) guidelines allow transwomen to compete in the women's division if (amongst other things) their testosterone is held below 10 nmol/L. This is significantly higher than that of cis-women. Science demonstrates that high testosterone and other male physiology provides a performance advantage in sport suggesting that transwomen retain some of that advantage. To determine whether the advantage is unfair necessitates an ethical analysis of the principles of inclusion and fairness. Particularly important is whether the advantage held by transwomen is a tolerable or intolerable unfairness. We conclude that the advantage to transwomen afforded by the IOC guidelines is an intolerable unfairness. This does not mean transwomen should be excluded from elite sport but that the existing male/female categories in sport should be abandoned in favour of a more nuanced approach satisfying both inclusion and fairness.

Gender Differences in Dose of Erythropoietin to Maintain Hemoglobin Target in Hemodialysis Patients

Dialysis patients receiving erythropoietin (EPO) for anemia management are a challenge due to the significant interindividual variability in erythropoietic response. Our objective was to determine if there is a gender-dependent difference in the EPO doses required to maintain the hemoglobin (Hb) targets in adult patients undergoing hemodialysis. We conducted a historic cohort study with a 12-month follow-up. We include patients with the Hb target, normal serum albumin, and normal transferrin saturation index. Monthly data were gathered for the following: Hb level, EPO doses, and intravenous iron doses. In the 11 hemodialysis facilities included, 1844 patients were on hemodialysis. We considered 389 patients for follow-up, 190 of which were excluded mainly for failing to keep the Hb level in the established range. The final cohort for analysis included 141 men (70.9%) and 58 women (29.1%). At baseline, men weighed more than women (P < 0.001). At the end of the follow-up period, the EPO required to maintain Hb level between 10 and 13 g/dl was significantly higher in women in the monthly dose, weekly dose, and weekly EPO dose/patient weight, with no difference in the monthly iron dose. There was a significant association between female gender and the use of high EPO doses (odds ratio, 4.1; 95% confidence interval, 1.4–12.2; P = 0.01). Our study demonstrates that women require higher doses of EPO to achieve Hb targets.

Sex-Gender Variable: Methodological Recommendations for Increasing Scientific Value of Clinical Studies

There is a clear sex-gender gap in the prevention and occurrence of diseases, and in the outcomes and treatments, which is relevant to women in the majority of cases. Attitudes concerning the enrollment of women in randomized clinical trials have changed over recent years. Despite this change, a gap still exists. This gap is linked to biological factors (sex) and psycho-social, cultural, and environmental factors (gender). These multidimensional, entangled, and interactive factors may influence the pharmacological response. Despite the fact that regulatory authorities recognize the importance of sex and gender, there is a paucity of research focusing on the racial/ethnic, socio-economic, psycho-social, and environmental factors that perpetuate disparities. Research and clinical practice must incorporate all of these factors to arrive at an intersectional and system-scenario perspective. We advocate for scientifically rigorous evaluations of the interplay between sex and gender as key factors in performing clinical trials, which are more adherent to real-life. This review proposes a set of 12 rules to improve clinical research for integrating sex-gender into clinical trials.

Greater anemia tolerance among hospitalized females compared to males

BACKGROUND

Although females have a lower baseline hemoglobin (Hb) compared to males, it is unknown whether females have a greater tolerance for anemia when hospitalized. We tested the hypothesis that females tolerate severe anemia better than males, with decreased inpatient mortality in this setting.

STUDY DESIGN AND METHODS

We conducted a retrospective cohort study in 230,644 adult patients admitted to Johns Hopkins Hospital from January 2009 to June 2016. The relationships between nadir Hb and percentage change in Hb with inpatient mortality were assessed for nontransfused males and females. A multivariable logistic regression was used to determine risk-adjusted differences between males and females for the likelihood of inpatient mortality at nadir Hb levels of 5, 6, and 7 g/dL.

RESULTS

Males had increased mortality when nadir Hb was 6.0 g/dL or less (p < 0.05), whereas females did not. The risk-adjusted likelihood for inpatient mortality was greater for males compared to females at a nadir Hb of 6 g/dL or less (odds ratio, 1.84; 95% confidence interval, 1.09-3.16) (p = 0.02), but this sex-related difference was not significant at a nadir Hb of 5 or 7 g/dL or less. Inpatient mortality increased significantly in both males and females when the percentage decrease in Hb was greater than 50% from baseline (p < 0.05).

CONCLUSIONS

Compared to males, females tolerate a lower nadir Hb, but a similar percentage change in Hb, before an increase in inpatient mortality is recognized. The findings suggest that females may be "preconditioned" to tolerate anemia better than males.

Physiological and pathological skeletal muscle T1 changes quantified using a fast inversion-recovery radial NMR imaging sequence

We investigated the response of skeletal muscle global T1 under different physiological and pathological conditions using an inversion-recovery radial T1 mapping sequence. Thirty five healthy volunteers, seven patients with Becker muscular dystrophy (BMD) and seven patients with sporadic inclusion body myositis (IBM) were investigated in order to evaluate the effects of gender, age, muscle group, exercise and pathological processes on global T1 values. In addition, the intramuscular fat content was measured using 3-point Dixon and the global T2 and water T2 (T2_H2O) were determined with a multi-spin-echo sequence. In the muscles of healthy volunteers, there was no impact of age on global T1. However, we measured a significant effect of sex and muscle group. After exercise, a significant 7.7% increase of global T1 was measured in the recruited muscles, and global T1 variations were highly correlated to T2_H2O variations (R = 0.91). In pathologies, global T1 values were reduced in fat infiltrated muscles. When fat fraction was taken into account, global T1 values were higher in IBM patients compared to BMD. Global T1 variations are a sensitive indicator of tissue changes in skeletal muscle related to several physiological and pathological events.

Coagulation changes induced by lower-body negative pressure in men and women

We investigated whether lower-body negative pressure (LBNP) application leads to coagulation activation in whole blood (WB) samples in healthy men and women. Twenty-four women and 21 men, all healthy young participants, with no histories of thrombotic disorders and not on medications, were included. LBNP was commenced at −10 mmHg and increased by −10 mmHg every 5 min until a maximum of −40 mmHg. Recovery up to 10 min was also monitored. Blood samples were collected at baseline, at end of LBNP, and end of recovery. Hemostatic profiling included comparing the effects of LBNP on coagulation values in both men and women using standard coagulation tests, calibrated automated thrombogram, thrombelastometry, impedance aggregometry, and markers of thrombin formation. LBNP led to coagulation activation determined in both plasma and WB samples. At baseline, women were hypercoagulable compared with men, as evidenced by their shorter “lag times” and higher thrombin peaks and by shorter “coagulation times” and “clot formation times.” Moreover, men were more susceptible to LBNP, as reflected in their elevated factor VIII levels and decreased lag times following LBNP. LBNP-induced coagulation activation was not accompanied by endothelial activation. Women appear to be relatively hypercoagulable compared with men, but men are more susceptible to coagulation changes during LBNP. The application of LBNP might be a useful future tool to identify individuals with an elevated risk for thrombosis, in subjects with or without history of thrombosis.

NEW & NOTEWORTHY LBNP led to coagulation activation determined in both plasma and whole blood samples. At baseline, women were hypercoagulable compared with men. Men were, however, more susceptible to coagulation changes during LBNP. LBNP-induced coagulation activation was not accompanied by endothelial activation. The application of LBNP might be a useful future tool to identify individuals with an elevated risk for thrombosis, in subjects with or without history of thrombosis.

Sex differences in stress and immune responses during confinement in Antarctica

Background

Antarctica challenges human explorers by its extreme environment. The effects of these unique conditions on the human physiology need to be understood to best mitigate health problems in Antarctic expedition crews. Moreover, Antarctica is an adequate Earth-bound analogue for long-term space missions. To date, its effects on human physiology have been studied mainly in male cohorts though more female expeditioners and applicants in astronaut training programs are selected. Therefore, the identification of sex differences in stress and immune reactions are becoming an even more essential aim to provide a more individualized risk management.

Methods

Ten female and 16 male subjects participated in three 1-year expeditions to the German Antarctic Research Station Neumayer III. Blood, saliva, and urine samples were taken 1–2 months prior to departure, subsequently every month during their expedition, and 3–4 months after return from Antarctica. Analyses included cortisol, catecholamine and endocannabinoid measurements; psychological evaluation; differential blood count; and recall antigen- and mitogen-stimulated cytokine profiles.

Results

Cortisol showed significantly higher concentrations in females than males during winter whereas no enhanced psychological stress was detected in both sexes. Catecholamine excretion was higher in males than females but never showed significant increases compared to baseline. Endocannabinoids and N-acylethanolamides increased significantly in both sexes and stayed consistently elevated during the confinement. Cytokine profiles after in vitro stimulation revealed no sex differences but resulted in significant time-dependent changes. Hemoglobin and hematocrit were significantly higher in males than females, and hemoglobin increased significantly in both sexes compared to baseline. Platelet counts were significantly higher in females than males. Leukocytes and granulocyte concentrations increased during confinement with a dip for both sexes in winter whereas lymphocytes were significantly elevated in both sexes during the confinement.

Conclusions

The extreme environment of Antarctica seems to trigger some distinct stress and immune responses but—with the exception of cortisol and blood cell counts—without any major relevant sex-specific differences. Stated sex differences were shown to be independent of enhanced psychological stress and seem to be related to the environmental conditions. However, sources and consequences of these sex differences have to be further elucidated.