Relationship Between Hematocrit Level and Cardiovascular Risk Factors in a Community-Based Population

Seasonal dynamics of myocardial infarctions in regions with different types of a climate: a meta-analysis

BACKGROUND

It is known that cardiovascular events (CVE) occur more often in winter than in summer. However, dependence of myocardial infarction (MI) risk of on various meteorological factors is still not fully understood. Also, the dependence of the seasonal dynamics of MI on gender and age has not yet been studied. The purpose of our meta-analysis is to reveal dependence of the circannual dynamics of MI hospitalizations on gender, age, and characteristics of a region's climate.

MAIN BODY

Using Review Manager 5.3, we performed a meta-analysis of 26 publications on the seasonal dynamics of MI. In our meta-analysis, the relative MI risk was higher in colder compared to warmer seasons. Old age insignificantly increased the seasonal MI risk; gender did not affect the seasonal dynamics of MI, but MI was more common in men than in women. The severity of the seasonal dynamics of MI risk depended on the climate of the region. In a climate with a small amplitude of circannual fluctuations in air temperature, atmospheric pressure, and partial oxygen density in the air, as well as in regions where air humidity is higher in winter than in summer, an increase in MI risk in winter compared to summer was significant. It was not significant in regions with opposite climatic tendencies.

CONCLUSIONS

Based on the results of our studies, it can be concluded that a decrease in air temperature increases in MI risk; in addition, hypoxia in the hot season can provoke CVE associated with ischemia.

Different Effects of Lard and Vegetable Blend Oil on Intestinal Microorganisms, Enzyme Activity and Blood Routine in Mice

The intake of moderate oils and fats is necessary to maintain the body's energy balance, and the fatty acid composition of different oils and fats varies in their nutrition and function. The study aimed to investigate the effects of lard and vegetable blend oil on gut microbiota, intestinal enzyme activities, and blood routine. Kunming mice were assigned to the three groups: (1) Control group (CK) was gavage administration with distilled water, (2) Plant oil group (ZWY) was gavage administration with edible vegetable blend oil, (3) Lard group (DWY) was gavage administration with lard. After 42 days, microbiological, digestive enzymes, and blood routine were performed. Compared with the CK group, Escherichia coli, Lactobacilli, and Bifidobacteria were significantly decreased (p < 0.05), the activities of protease, cellulase, amylase, and xylanase were markedly reduced (p < 0.05), the hemoglobin was significantly increased (p < 0.05) in the ZWY group and DWY groups, and the hematocrit was increased in the ZWY group (p < 0.05), while other routine blood indices were increased (p > 0.05). Compared to the ZWY group, the activity of cellulase and amylase were significantly increased (p < 0.05), the intestinal microorganism and the routine blood indexes had no significant difference in the DWY group. Lard and vegetable blend oil diet affected the composition of the intestinal microorganisms, and the functions of digestive enzymes. Meanwhile, the levels of digestive enzymes may be correlated with the intestinal microbiota.

Therapeutic Plateletpheresis in Patients With Thrombocytosis: Gender, Hemoglobin Before Apheresis Significantly Affect Collection Efficiency

Background: Thrombocytosis is a common symptom in myeloproliferative neoplasms (MPN), and excessive proliferation may deteriorate into thrombosis, bleeding, myelofibrosis, and may ultimately convert to acute leukemia. This study aimed to investigate the collection efficiency of plateletpheresis (CEPP) and factors influencing its efficacy in patients with thrombocytosis.

Materials and Methods: From September 2010 to December 2016, 81 patients from two institutions in China with myeloproliferative neoplasms and thrombocytosis accompanied by severe symptoms were treated with plateletpheresis by Fresenius COM. TEC machine.

Results: After apheresis, the median CEPP was 20.71% (IQR: 9.99–36.69%) and median PLT reduction rate was 25.87% (IQR: 21.78–36.23%). Further analysis showed that no significant difference was observed between PLT count with 800–1,000 × 10⁹/L and > 1,000 × 10⁹/L. The PLT counts significantly decreased (P < 0.001) after plateletpheresis, the red blood cell (RBC), white blood cell (WBC), hemoglobin (HGB), and hematocrit (HCT) levels showed no significant differences before- or after- plateletpheresis. Multivariate analysis showed that female sex (P = 0.009) and HGB (P = 0.010) before apheresis were associated with CEPP. Female (P = 0.022), HCT (P = 0.001) and blood volume (P = 0.015) were associated with the PLT reduction rate. Furthermore, symptoms were relieved after apheresis in patients whose PLT count was 800–1,000 × 10⁹/L accompanied with symptoms.

Conclusions: It is reasonable to perform plateletpheresis when the PLT count is over 800 × 10⁹/L and patients are complicated by clinical symptoms such as dizziness, headache, somnolence, and stupor. Plateletpheresis is effective in removing PLTs especially in females with high HGB.

Cardiovascular Outcomes in Trials of New Antidiabetic Drug Classes

Type 2 diabetes is among the most prevalent chronic diseases worldwide and the prevention of associated cardiovascular complications is an important treatment goal. Sodium–glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide 1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors are second-line options after metformin, while cardiovascular outcome trials have been conducted to establish the cardiovascular safety of these antidiabetic drug classes. SGLT2 inhibitors have been shown to have the best overall mortality, renal and cardiovascular outcomes. Reduction in hospitalisation for heart failure is particularly consistent. GLP-1 receptor agonists have also showed some benefits, especially in stroke prevention. DPP-4 inhibitors showed neutral effects on cardiovascular outcomes, but may increase the incidence of heart failure. Favourable outcomes observed in trials of SGLT2 inhibitors mean that these should be the preferred second-line option. DPP-4 inhibitors are useful for patients with diabetes at low cardiovascular risk.

4D flow evaluation of blood non-Newtonian behavior in left ventricle flow analysis

Blood is generally modeled as a Newtonian fluid, assuming a standard and constant viscosity; however, this assumption may not hold for the highly pulsatile and recirculating intracavitary flow in the left ventricle (LV), hampering the quantification of fluid dynamic indices of potential clinical relevance. Herein, we investigated the effect of three viscosity models on the patient-specific quantification of LV blood energetics, namely on viscous energy loss (EL), from 4D Flow magnetic resonance imaging: I) Newtonian with standard viscosity (3.7 cP), II) Newtonian with subject-specific hematocrit-dependent viscosity, III) non-Newtonian accounting for the effect of hematocrit and shear rate. Analyses were performed on 5 controls and 5 patients with cardiac light-chain amyloidosis. In Model II, viscosity ranged between 3.0 (-19%) and 4.3 cP (+16%), mildly deviating from the standard value. In the non-Newtonian model, this effect was emphasized: viscosity ranged from 3.2 to 6.0 cP, deviating maximally from the standard value in low shear rate (i.e., <100 s^-1) regions. This effect reflected on EL quantifications: in particular, as compared to Model I, Model III yielded markedly higher EL values (up to +40%) or markedly lower (down to -21%) for subjects with hematocrit higher than 39.5% and lower than 30%, respectively. Accounting for non-Newtonian blood behavior on a patient-specific basis may enhance the accuracy of intracardiac energetics assessment by 4D Flow, which may be explored as non-invasive index to discriminate between healthy and pathologic LV.

Effects of crude oil vapors on the cardiovascular flow of embryonic Gulf killifish

Direct contact with toxicants in crude oil during embryogenesis causes cardiovascular defects, but the effects of exposure to airborne volatile organic compounds released from spilled oil are not well understood. The effects of crude oil-derived airborne toxicants on peripheral blood flow were examined in Gulf killifish (Fundulus grandis) since this model completes embryogenesis in the air. Particle image velocimetry was used to measure in vivo blood flow in intersegmental arteries of control and oil-exposed embryos. Significant effects in oil-exposed embryos included increased pulse rate, reduced mean blood flow speed and volumetric flow rate, and decreased pulsatility, demonstrating that normal-appearing oil-exposed embryos retain underlying cardiovascular defects. Further, hematocrit moderately increased in oil-exposed embryos. This study highlights the potential for fine-scale physiological measurement techniques to better understand the sub-lethal effects of oil exposure and demonstrates the efficacy of Gulf killifish as a unique teleost model for aerial toxicant exposure studies.

Testosterone Therapy and Cardiovascular Risk: A Critical Analysis of Studies Reporting Increased Risk

BACKGROUND

Treatment of "adult-onset hypogonadism" (AOH) with exogenous testosterone therapy (TTh) to raise serum testosterone (T) levels may influence cardiovascular (CV) risk factors in patients with AOH, whereas low endogenous T levels are associated with an increased CV risk and mortality.

AIM

To critically evaluate studies reporting increased CV risk associated with TTh and to provide an overview of the risks and benefits of restoring T levels through exogenous TTh.

METHODS

A review of publications focusing on the association between TTh and increased CV risk was conducted, and the study methodologies and conclusions of each were critically evaluated. Further, recent clinical and epidemiological studies associating AOH or TTh with a change in CV risk, and pertinent hematologic and vascular effects noted in animal studies and in vitro, as well as in clinical practice were also reviewed.

OUTCOMES

A review of the literature shows that untreated testosterone deficiency and/or low T is associated with an increase in CV risk and adverse outcomes, with numerous studies and meta-analyses to support a positive association between exogenous TTh and an improvement in CV risk factors in men with AOH.

RESULTS

Numerous studies in the literature demonstrate the positive benefits of using TTh; however, since 2013, some publications have suggested a link to increased CV risk associated with TTh. A number of these studies retrospectively analyzed insurance claims databases using diagnosis codes, procedures codes, and prescription information. Many reviews published since have pointed out the methodological flaws and debatable conclusions of these studies.

CLINICAL IMPLICATIONS

A careful assessment of the patient's current health status and CV risk factors should be weighed against the benefits and possible risks resulting from TTh, and consideration should be given to deferring treatment pending resolution or stabilization of CV disease or risk factors.

STRENGTHS & LIMITATIONS

In this review, we provide an in-depth analysis of studies reporting increased CV risk with TTh. Many of the studies were not well-designed, randomized, double-blind, prospective clinical trials but rather post hoc analyses of cohort data. These studies may reflect bias in how treatment and nontreatment decisions are made or reflect conclusions based on widely cited methodological flaws.

CONCLUSION

Appropriate patient selection supported by low pre-treatment T levels and monitoring T levels during treatment with the goal of achieving and maintaining physiologic levels all contribute to the safe and effective use of TTh in men with AOH. Khera M, Miner M, Jaffe J, et al. Testosterone Therapy and Cardiovascular Risk: A Critical Analysis of Studies Reporting Increased Risk. J Sex med 2021;18:83-98.

Improved Erythrocyte Deformability Induced by Sodium-Glucose Cotransporter 2 Inhibitors in Type 2 Diabetic Patients

PURPOSE

Sodium-glucose cotransporter 2 (SGLT-2) inhibitors are antidiabetic drugs that improve cardiovascular outcomes. Hemoglobin and hematocrit values increase after SGLT-2 inhibitor administration. Although these factors increase blood viscosity and the risk of cardiovascular disease, SGLT-2 inhibitors have protective effects on the cardiovascular system. The mechanisms for this paradoxical phenomenon remain unclear, and the effect of SGLT-2 inhibitors on hemorheology has not been studied.

METHODS

We evaluated the hemorheological parameters of 63 patients of whom 38 received metformin with a dipeptidyl peptidase 4 (DPP-4) inhibitor, while 25 received metformin with SGLT-2 inhibitor. Blood viscosity was measured using a cone-and-plate viscometer, erythrocyte aggregation was measured using a modified erythrocyte sedimentation rate method, and erythrocyte membrane fluctuation was measured as deformability, using a diffraction optical tomography.

RESULTS

Both blood viscosity and erythrocyte aggregation increased in the SGLT-2 inhibitor group, although erythrocyte deformability was significantly improved compared with that of the DPP-4 inhibitor group (DPP-4 inhibitor 43.71 ± 5.13 nm; SGLT-2 inhibitor 53.88 ± 4.88 nm; p < 0.001). When the two groups were compared after propensity score matching, no differences in blood viscosity at high shear rates and erythrocyte aggregation were observed, although erythrocyte deformability was significantly improved in the SGLT-2 inhibitor group (DPP-4 inhibitor 45.01 ± 5.28 nm; SGLT-2 inhibitor 53.14 ± 4.72 nm; p = 0.001).

CONCLUSION

This study demonstrates that erythrocyte deformability was improved in the SGLT-2 inhibitor group compared with that in the DPP-4 inhibitor group. This improvement in erythrocyte deformability is expected to have a protective effect on the cardiovascular system.

Individual differences in haemoglobin concentration influence bold fMRI functional connectivity and its correlation with cognition

Resting-state connectivity measures the temporal coherence of the spontaneous neural activity of spatially distinct regions, and is commonly measured using BOLD-fMRI. The BOLD response follows neuronal activity, when changes in the relative concentration of oxygenated and deoxygenated haemoglobin cause fluctuations in the MRI T2* signal. Since the BOLD signal detects changes in relative concentrations of oxy/deoxy-haemoglobin, individual differences in haemoglobin levels may influence the BOLD signal-to-noise ratio in a manner independent of the degree of neural activity. In this study, we examined whether group differences in haemoglobin may confound measures of functional connectivity. We investigated whether relationships between measures of functional connectivity and cognitive performance could be influenced by individual variability in haemoglobin. Finally, we mapped the neuroanatomical distribution of the influence of haemoglobin on functional connectivity to determine where group differences in functional connectivity are manifest.

In a cohort of 518 healthy elderly subjects (259 men), each sex group was median-split into two groups with high and low haemoglobin concentration. Significant differences were obtained in functional connectivity between the high and low haemoglobin groups for both men and women (Cohen’s d 0.17 and 0.03 for men and women respectively). The haemoglobin connectome in males showed a widespread systematic increase in functional connectivity correlation values, whilst the female connectome showed predominantly parietal and subcortical increases and temporo-parietal decreases. Despite the haemoglobin groups having no differences in cognitive measures, significant differences in the linear relationships between cognitive performance and functional connectivity were obtained for all 5 cognitive tests in males, and 4 out of 5 tests in females.

Our findings confirm that individual variability in haemoglobin levels that give rise to group differences are an important confounding variable in BOLD-fMRI-based studies of functional connectivity. Controlling for haemoglobin variability as a potentially confounding variable is crucial to ensure the reproducibility of human brain connectome studies, especially in studies that compare groups of individuals, compare sexes, or examine connectivity-cognition relationships.

Association between insulin resistance and haematological parameters: A cohort study from adolescence to adulthood

BACKGROUND

The aim of this study was to quantify the relationship between insulin resistance and haematological parameters from adolescence to adulthood.

METHODS

Participants from the EPITeen cohort were evaluated at 13, 17, and 21 years, through standardized procedures. A fasting blood sample was obtained, and insulin resistance was evaluated by the homeostatic model assessment (HOMA-IR). The cross-sectional association between HOMA-IR and haematological parameters at 21 years was quantified in 1671 participants by multivariate linear regression coefficients (β) and 95% confidence intervals (95%CI). For the longitudinal analysis (n = 496), trajectories of insulin and glucose were estimated using model-based clustering, and haematological parameters were compared according to trajectories using ANOVA.

RESULTS

At 21 years, after adjustment for BMI, positive associations (β [95%CI]) were found between HOMA-IR and red blood count (0.05 [0.03;0.07] in females; 0.02 [0.00;0.04] in males); and haematocrit (0.29 [0.12;0.46] in females; 0.21 [0.04,0.38] in males). In females, HOMA-IR was inversely associated with packed cell volume (PCV) (-0.35 [-0.66;-0.05]) and iron levels (-3.98 [-6.94,-1.03]) but positively associated with white blood cells (0.31 [0.19;0.43]) and platelets (7.66 [3.93;11.39]). In males, a higher HOMA-IR was significantly associated with higher haemoglobin (0.09 [0.03;0.16]). Regarding the longitudinal analysis, similar trends were found, but statistical significance was not reached.

CONCLUSIONS

Both longitudinal and cross-sectional analyses support the hypothesis that insulin resistance is associated with increased red blood cells count and haematocrit in young adults, even within normal ranges of insulin and glucose.

A hospital based retrospective study of factors influencing therapeutic leukapheresis in patients presenting with hyperleukocytic leukaemia

Therapeutic leukapheresis is a rapid and effective method to reduce early mortality of patients with hyperleukocytic leukaemia (HLL). However, few studies on factors influencing the efficiency have been reported. In this study, 67 cases who underwent leukapheresis were retrospectively analysed and factors related to the collection efficiency of leukapheresis (CE_WBC) were also evaluated. Paired t test showed that there was a significant decrease in statistics of white blood cell (WBC) counts after apheresis. The results of two independent samples nonparametric test suggested that WBC counts, platelet (PLT) counts, haematocrit (HCT), hemoglobin (HGB), serum chlorine (Cl) and globulin (GLB) before leukapheresis correlated with the CE_WBC. Multiple linear regression analysis with background stepwise variable selection indicated that only WBC and HCT before leukapheresis had an influence on CE_WBC significantly. Kaplan-Meier analysis and Cox regression model indicated that lymphocyte (LY) and mean corpuscular hemoglobin (MCH) pre-apheresis as independent factors significantly affected the prognostic survival of patients with HLL. Moreover, platelets and red blood cell were contaminated in the product of leukapheresis. It is an urgent problem to be solved in order to realise higher efficacy and higher purity of WBC collection to improve the survival of patients with HLL through optimising instruments.

Erythrocytosis Following Testosterone Therapy

INTRODUCTION

A rapid increase in awareness of androgen deficiency has led to substantial increases in prescribing of testosterone therapy (TTh), with benefits of improvements in mood, libido, bone density, muscle mass, body composition, energy, and cognition. However, TTh can be limited by its side effects, particularly erythrocytosis. This review examines the literature on testosterone-induced erythrocytosis and polycythemia.

AIM

To review the available literature on testosterone-induced erythrocytosis, discuss possible mechanisms for pathophysiology, determine the significance of formulation, and elucidate potential thromboembolic risk.

METHODS

A literature review was performed using PubMed for articles addressing TTh, erythrocytosis, and polycythemia.

MAIN OUTCOME MEASURES

Mechanism, pharmacologic contribution, and risk of testosterone-induced erythrocytosis.

RESULTS

For men undergoing TTh, the risk of developing erythrocytosis compared with controls is well established, with short-acting injectable formulations having the highest associated incidence. Potential mechanisms explaining the relation between TTh and erythrocytosis include the role of hepcidin, iron sequestration and turnover, erythropoietin production, bone marrow stimulation, and genetic factors. High blood viscosity increases the risk for potential vascular complications involving the coronary, cerebrovascular, and peripheral vascular circulations, although there is limited evidence supporting a relation between TTh and vascular complications.

CONCLUSION

Short-acting injectable testosterone is associated with greater risk of erythrocytosis compared with other formulations. The mechanism of the pathophysiology and its role on thromboembolic events remain unclear, although some data support an increased risk of cardiovascular events resulting from testosterone-induced erythrocytosis. Ohlander SJ, Varghese B, Pastuszak AW. Erythrocytosis Following Testosterone Therapy. Sex Med Rev 2018;6:77-85.

Erythrocytosis and Polycythemia Secondary to Testosterone Replacement Therapy in the Aging Male

INTRODUCTION

Testosterone replacement therapy (TRT) is a common treatment for hypogonadism in aging males. Men with low to low-normal levels of testosterone have documented benefit from hormone replacement. Recent meta-analyses have revealed that increases in hemoglobin (Hb) and hematocrit (Hct) are the variants most commonly encountered. Clinically, this response is described as erythrocytosis or polycythemia secondary to TRT. However, the recent Food and Drug Administration warning regarding the risk for venothromboembolism (VTE) has made the increases in Hb and Hct of more pertinent concern. The risks associated with androgen replacement need further examination.

AIM

To review the available literature on erythrocytosis and polycythemia secondary to TRT. To discuss potential etiologies for this response, the role it plays in risk for VTE, and recommendations for considering treatment in at-risk populations.

METHODS

A literature review was performed through PubMed regarding TRT and erythrocytosis and polycythemia.

MAIN OUTCOME MEASURES

To assess the mechanisms of TRT-induced erythrocytosis and polycythemia with regard to basic science, pharmacologic preparation, and route of delivery. To review Hct and risk for thrombotic events. To offer clinical suggestions for therapy in patients at risk for veno-thrombotic events.

RESULTS

Men undergoing TRT have a 315% greater risk for developing erythrocytosis (defined as Hct > 0.52) when compared with control. Mechanisms involving iron bioavailability, erythropoietin production, and bone marrow stimulation have been postulated to explain the erythrogenic effect of TRT. The association between TRT-induced erythrocytosis and subsequent risk for VTE remains inconclusive.

CONCLUSIONS

All TRT formulations cause increases in Hb and Hct, but injectables tend to produce the greatest effect. The evidence regarding the risk for VTE with increased Hct is inconclusive. For patients with risk factors for veno-thrombotic events, formulations that provide the smallest effect on blood parameters hypothetically provide the safest option. Further trials are needed to fully evaluate the hematological side effects associated with TRT. Jones SD Jr, Dukovac T, Sangkum P, Yafi FA, and Hellstrom WJG. Erythrocytosis and polycythemia secondary to testosterone replacement therapy in the aging male. Sex Med Rev 2015;3:101-112.

Impact of hematocrit on measurements of the intrinsic brain

Blood oxygenation level dependent (BOLD)–based functional MRI (fMRI) is a widely utilized neuroimaging technique for mapping brain function. Hematocrit (HCT), a global hematologic marker of the amount of hemoglobin in blood, is known to impact task-evoked BOLD activation. Yet, its impact on resting-state fMRI (R-fMRI) measures has not been characterized. We address this gap by testing for associations between HCT level and inter-individual variation in commonly employed R-fMRI indices of intrinsic brain function from 45 healthy adults. Given known sex differences in HCT, we also examined potential sex differences. Variation in baseline HCT among individuals were associated with regional differences in four of the six intrinsic brain indices examined. Portions of the default (anterior cingulate cortex/medial prefrontal cortex: ACC/MPFC), dorsal attention (intraparietal sulcus), and salience (insular and opercular cortex) network showed relationships with HCT for two measures. The relationships within MPFC, as well as visual and cerebellar networks, were modulated by sex. These results suggest that inter-individual variations in HCT can serve as a source of variations in R-fMRI derivatives at a regional level. Future work is needed to delineate whether this association is attributable to neural or non-neuronal source of variations and whether these effects are related to acute or chronic differences in HCT level.