The effect of partial replacements of membrane cholesterol by other steroids on the osmotic fragility and glycerol permeability of erythrocytes

Cholesterol metabolism: physiological versus pathological aspects in intracerebral hemorrhage

Cholesterol is an important component of plasma membranes and participates in many basic life functions, such as the maintenance of cell membrane stability, the synthesis of steroid hormones, and myelination. Cholesterol plays a key role in the establishment and maintenance of the central nervous system. The brain contains 20% of the whole body's cholesterol, 80% of which is located within myelin. A huge number of processes (e.g., the sterol regulatory element-binding protein pathway and liver X receptor pathway) participate in the regulation of cholesterol metabolism in the brain via mechanisms that include cholesterol biosynthesis, intracellular transport, and efflux. Certain brain injuries or diseases involving crosstalk among the processes above can affect normal cholesterol metabolism to induce detrimental consequences. Therefore, we hypothesized that cholesterol-related molecules and pathways can serve as therapeutic targets for central nervous system diseases. Intracerebral hemorrhage is the most severe hemorrhagic stroke subtype, with high mortality and morbidity. Historical cholesterol levels are associated with the risk of intracerebral hemorrhage. Moreover, secondary pathological changes after intracerebral hemorrhage are associated with cholesterol metabolism dysregulation, such as neuroinflammation, demyelination, and multiple types of programmed cell death. Intracellular cholesterol accumulation in the brain has been found after intracerebral hemorrhage. In this paper, we review normal cholesterol metabolism in the central nervous system, the mechanisms known to participate in the disturbance of cholesterol metabolism after intracerebral hemorrhage, and the links between cholesterol metabolism and cell death. We also review several possible and constructive therapeutic targets identified based on cholesterol metabolism to provide cholesterol-based perspectives and a reference for those interested in the treatment of intracerebral hemorrhage.

Non-HDL-C, Symptomatic Intracranial Arterial Stenosis, and Recurrent Vascular Risk in Minor Stroke

AIM

We aimed to assess the association between non-high-density lipoprotein cholesterol (non-HDL-C) and symptomatic intracranial artery stenosis (sICAS), as well as the impact of non-HDL-C on recurrent vascular events in patients with mild ischemic stroke ( NIHSS score ≤ 5).

METHODS

This prospective study was based on data from patients presenting within 72 hours of stroke occurrence. We included patients admitted to 8 Chinese hospitals between September 2019 and November 2021. The associations of non-HDL-C with sICAS and recurrent vascular risk were assessed using multivariate regression models and a restricted cubic spline analysis.

RESULTS

Among the 2,544 patients analyzed at 12 months, 652 (25.6%) were diagnosed with sICAS. Elevated non-HDL-C was linked to a higher incidence of sICAS, and the adjusted odd ratios for quintile variables and continuous variables were 1.36 ([95% CI, 1.01-1.81]) and 1.14 ([95% CI, 1.04-1.24). In comparison to those in the first quintile, the adjusted hazard ratio of the fifth quintile of non-HDL-C was 1.19 ([95% CI 0.78-1.80]) for recurrent ischemic stroke and was 0.39 ([95% CI, 0.17-0.91]) for intracranialhemorrhage.

CONCLUSIONS

The non-HDL-C level may be a useful predictor of sICAS. Higher non-HDL-C levels may be associated with a lower risk of intracranial hemorrhage in mild, noncardiogenic stroke, but not a higher risk of recurrent ischemic stroke.

Association between triglyceride-glucose index and carotid atherosclerosis in Chinese steelworkers: a cross-sectional study

This study aims to explore the association between the triglyceride-glucose (TyG) index and the risk of carotid atherosclerosis (CAS) among Chinese steelworkers. This is a cross-sectional study involving a total of 4,203 Chinese steelworkers. The TyG index was calculated using the formula: TyG = Ln [fasting triglycerides (mg/dL) × fasting glucose (mg/dL) / 2]. The association between the TyG index and CAS was analyzed using multivariable logistic regression and restricted cubic spline (RCS) models. The association between TyG and CAS was evaluated across different subgroups, including sex, age, lifestyle, medical history, and the state of occupational exposure. In addition, the TyG index was used to perform calibration and risk reclassification analyses on the fully adjusted model. Feature importance and predictive models were generated using LASSO regression and machine learning methods. In the fully adjusted model, compared to the lowest quartile group, the odds ratios (OR, 95% CI) for CAS, increased CIMT, and plaque in the highest quartile group of the TyG index were 3.199 (2.423 ~ 4.223), 2.877 (2.149 ~ 3.851), and 3.738 (2.700 ~ 5.177), respectively. Steelworkers exposed to occupational hazards had a higher risk of CAS compared to those not exposed. There was a nonlinear positive correlation between the TyG index and CAS (P < 0.05), and the risk of CAS increased when TyG > 8.72. Additionally, the TyG index demonstrated additional predictive capability beyond existing risk factors, significantly improving discriminatory performance (P < 0.05). In LASSO regression, TyG index and other covariables are screened as important feature variables to be incorporated into the development of machine learning models. The TyG index is associated with an increased risk of CAS among steelworkers, underscoring its potential as a reliable and practical predictive tool for assessing CAS risk in this population. Steelworkers with a TyG index>8.72 should receive additional CAS screening and health interventions. In addition, attention should be paid to those exposed to occupational hazards. The TyG index may serve as a simple, rapid, and reliable assessment tool for identifying high-risk individuals with CAS among steelworkers.

Association and its population heterogeneities between low-density lipoprotein cholesterol and all-cause and cardiovascular mortality: A population-based cohort study

BACKGROUND

The association and its population heterogeneities between low-density lipoprotein cholesterol (LDL-C) and all-cause and cardiovascular mortality remain unknown. We aimed to examine the dose-dependent associations of LDL-C levels with specific types of cardiovascular disease (CVD) mortality and heterogeneities in the associations among different population subgroups.

METHODS

A total of 2,968,462 participants aged 35-75 years from China Health Evaluation And risk Reduction through nationwide Teamwork (ChinaHEART) (2014-2019) were included. Cox proportional hazard models and Fine-Gray subdistribution hazard models were used to estimate associations between LDL-C categories (<70.0, 70.0-99.9, 100.0-129.9 [reference group], 130.0-159.9, 160.0-189.9, and ≥190.0 mg/dL) and all-cause and cause-specific mortality.

RESULTS

During a median follow-up of 3.7 years, 57,391 and 23,241 deaths from all-cause and overall CVD were documented. We observed J-shaped associations between LDL-C and death from all-cause, overall CVD, coronary heart disease (CHD), and ischemic stroke, and an L-shaped association between LDL-C and hemorrhagic stroke (HS) mortality ( P for non-linearity <0.001). Compared with the reference group (100.0-129.9 mg/dL), very low LDL-C levels (<70.0 mg/dL) were significantly associated with increased risk of overall CVD (hazard ratio [HR]: 1.10, 95% confidence interval [CI]: 1.06-1.14) and HS mortality (HR: 1.37, 95% CI: 1.29-1.45). Very high LDL-C levels (≥190.0 mg/dL) were associated with increased risk of overall CVD (HR: 1.51, 95% CI: 1.40-1.62) and CHD mortality (HR: 2.08, 95% CI: 1.92-2.24). The stronger associations of very low LDL-C with risk of CVD mortality were observed in individuals with older age, low or normal body mass index, low or moderate 10-year atherosclerotic CVD risk, and those without diagnosed CVD or taking statins. Stronger associations between very high LDL-C levels and all-cause and CVD mortality were observed in younger people.

CONCLUSIONS

People with very low LDL-C had a higher risk of all-cause, CVD, and HS mortality; those with very high LDL-C had a higher risk of all-cause, CVD, and CHD mortality. On the basis of our findings, comprehensive health assessment is needed to evaluate cardiovascular risk and implement appropriate lipid-lowering therapy for people with very low LDL-C.

Intensive Versus Moderate Statin-Based Therapies in Patients With Mild Ischemic Stroke: A Prospective Multicenter Cohort Study

BACKGROUND

Statins are widely used for treating patients with ischemic stroke at risk of secondary cerebrovascular events. It is unknown whether Asian populations benefit from more intensive statin-based therapy for stroke recurrence. Therefore, in the present study we evaluated the effectiveness and safety of high-dose and moderate-dose statins for patients who had experienced mild ischemic stroke during the acute period.

METHODS AND RESULTS

This multicenter prospective study included patients with mild ischemic stroke who presented within 72 hours of symptom onset. The outcomes of patients in the high-intensity and moderate-intensity statin treatment groups were compared, with the main efficacy outcome being stroke recurrence and the primary safety end point being intracranial hemorrhage. The propensity score matching method was employed to control for imbalances in baseline variables. Subgroup analyses were conducted to evaluate group differences. In total, the data of 2950 patients were analyzed at 3 months, and the data of 2764 patients were analyzed at 12 months due to loss to follow-up. According to the multivariable Cox analyses adjusted for potential confounders, stroke recurrence occurred similarly in the high-intensity statin and moderate-intensity statin groups (3 months: adjusted hazard ratio [HR], 1.12 [95% CI, 0.85-1.49]; P=0.424; 12 months: adjusted HR, 1.08 [95% CI, 0.86-1.34]; P=0.519). High-intensity statin therapy was associated with an increased risk of intracranial hemorrhage (3 months: adjusted HR, 1.81 [95% CI, 1.00-3.25]; P=0.048; 12 months: adjusted HR, 1.86 [95% CI, 1.10-3.16]; P=0.021). The results from the propensity score-matched analyses were consistent with those from the Cox proportional hazards analysis.

CONCLUSIONS

Compared with moderate-intensity statin therapy, high-dose statin therapy may not decrease the risk of mild, noncardiogenic ischemic stroke recurrence but may increase the risk of intracranial hemorrhage.

REGISTRATION

URL: www.chictr.org.cn/. Unique Identifier: ChiCTR1900025214.

Lipid mixtures (from a liposome kit) and melatonin improve post-thawed Angora goat sperm parameters

Semen freezing and storing has been widely used in reproductive biotechnology, being applied to certain males of livestock breeds or animal species with economic value such as the Angora goat. The development of a semen extender with the cryoprotective agents can prevent the deterioration of sperm parameters after thawing. This study aimed to investigate lipid mixtures (from a liposome kit, Lps) and melatonin (Mel) at different doses to prevent the deterioration of sperm parameters and to provide the cryoprotective effects on sperm DNA. The Angora goat ejaculates were collected and pooled. They were divided into seven equal volumes, and each of them was diluted with the extenders of the experimental groups with additives (Lps 321.99 μg/mL, Lps 841.33 μg/mL, Mel 0.25 mM, Mel 1 mM, Lps 321.99 μg/mL + Mel 1 mM, Lps 841.33 μg/mL + Mel 0.25 mM) and no additives (control group). After the freeze-thawing process, motility, viability, acrosome integrity, DNA double-strand breaks, and abnormal DNA integrity were assessed for different extender groups. It was determined that the use of Lps alone at low dose or the combination of Lps and Mel had significant cryoprotective effects on motility, viability, acrosome integrity, and DNA damage in Angora goat sperm. This study will help us to understand the effects of Lps and Mel used alone or in combination at different doses and which doses give the optimum spermatological parameter rates following the freeze-thawing process, and hence it will shed light on further studies.

Associations of remnant cholesterol with cardiovascular and cancer mortality in a nationwide cohort

The health significance of triglyceride-rich lipoproteins, also known as remnant cholesterol, has been increasingly recognized. However, evidence of their associations with cause-specific mortality in the general population was previously insufficient. To explore these associations and their heterogeneities across subgroups, a prospective cohort study was conducted including 3,403,414 community-based participants from ChinaHEART, an ongoing government-funded public health program throughout China, from November 2014 through December 2022. The study assessed mortality risk of all-cause mortality, cardiovascular disease (CVD) mortality (including mortality from ischemic heart diseases (IHD), ischemic stroke (IS), and hemorrhagic stroke (HS), separately), and cancer mortality (including lung cancer, stomach cancer, and liver cancer, separately). During the 4-year follow-up, 23,646 individuals died from CVD (including 8807 from IHD, 3067 from IS, and 5190 from HS), and 20,318 from cancer (including 6208 from lung cancer, 3013 from liver cancer, and 2174 from stomach cancer). Compared with individuals with remnant cholesterol <17.9 mg/dL, multivariable-adjusted mortality hazard ratios (HRs) for individuals with remnant cholesterol ≥27.7 mg/dL were 1.03 (1.00-1.05) for all-cause mortality, 1.17 (1.12-1.21) for CVD (1.19 (1.12-1.27) for IHD mortality, and 1.22 (1.09-1.36) for IS mortality), and 0.90 (0.87-0.94) for all-cancer mortality (0.94 (0.87-1.02) for lung cancer, 0.59 (0.53-0.66) for liver cancer, and 0.73 (0.64-0.83) for stomach cancer). In summary, this study revealed a correlation between increased remnant cholesterol levels and an elevated risk of cardiovascular disease mortality, as well as a reduced risk of mortality for certain types of cancer.

Crosstalk between neurological, cardiovascular, and lifestyle disorders: insulin and lipoproteins in the lead role

Insulin resistance and impaired lipoprotein metabolism contribute to a plethora of metabolic and cardiovascular disorders. These alterations have been extensively linked with poor lifestyle choices, such as consumption of a high-fat diet, smoking, stress, and a redundant lifestyle. Moreover, these are also known to increase the co-morbidity of diseases like Type 2 diabetes mellitus and atherosclerosis. Under normal physiological conditions, insulin and lipoproteins exert a neuroprotective role in the central nervous system. However, the tripping of balance between the periphery and center may alter the normal functioning of the brain and lead to neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, depression, and multiple sclerosis. These neurological disorders are further characterized by certain behavioral and molecular changes that show consistent overlap with alteration in insulin and lipoprotein signaling pathways. Therefore, targeting these two mechanisms not only reveals a way to manage the co-morbidities associated with the circle of the metabolic, central nervous system, and cardiovascular disorders but also exclusively work as a disease-modifying therapy for neurological disorders. In this review, we summarize the role of insulin resistance and lipoproteins in the progression of various neurological conditions and discuss the therapeutic options currently in the clinical pipeline targeting these two mechanisms; in addition, challenges faced in designing these therapeutic approaches have also been touched upon briefly.

Association between triglyceride glucose index and carotid intima-media thickness in obese and nonobese adults

BACKGROUND

The triglyceride glucose (TyG) index is closely associated with subclinical atherosclerosis. However, the association remains inconclusive among obese and nonobese individuals.

METHODS

This prospective study was conducted in 5751 adults with normal carotid intima-media thickness (CIMT) at baseline. We divided the population into four groups based on the TyG index, which was calculated by the following formula: Ln (fasting triglycerides [mg/dL] × fasting glucose [mg/dL]/2). Information on CIMT was acquired by ultrasonography. Incident elevated CIMT was defined as IMT values greater than 0.9 mm at follow-up. Odds ratios (ORs) and 95% confidence intervals (CIs) of the associations between TyG index and elevated CIMT were estimated using multivariable logistic regression models.

RESULTS

After a median follow-up of 4.3 years, 722 (12.6%) individuals had progressed to elevated CIMT. Compared with the second quartile of the TyG index, the first and fourth quartile both conferred higher risks of elevated CIMT after adjusting for potential confounders. In the total population, the ORs for the first and fourth quartile were 1.29 (95% CI, 1.00-1.66) and 1.42 (95% CI, 1.11-1.83), respectively. Restricted cubic splines demonstrated an approximately U-shaped association between TyG index and elevated CIMT among the total and nonobese adults (P for nonlinearity <.05), but not in those with general or abdominal obesity.

CONCLUSIONS

A U-shaped association was observed between TyG index and elevated CIMT only among nonobese Chinese adults.

Cerebral Small Vessel Disease: Neuroimaging Features, Biochemical Markers, Influencing Factors, Pathological Mechanism and Treatment

Cerebral small vessel disease (CSVD) is the most common chronic vascular disease involving the whole brain. Great progress has been made in clinical imaging, pathological mechanism, and treatment of CSVD, but many problems remain. Clarifying the current research dilemmas and future development direction of CSVD can provide new ideas for both basic and clinical research. In this review, the risk factors, biological markers, pathological mechanisms, and the treatment of CSVD will be systematically illustrated to provide the current research status of CSVD. The future development direction of CSVD will be elucidated by summarizing the research difficulties.

The Association between Low Levels of Low Density Lipoprotein Cholesterol and Intracerebral Hemorrhage: Cause for Concern?

Excessive levels of low-density lipoprotein cholesterol (LDL-C) in the blood are a known risk factor for atherosclerosis, and a common target of treatment for primary and secondary prevention of cerebrocardiovascular disease. As lipid lowering agents including statins, ezetimibe and anti-proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors have shown good therapeutic results, the guidelines are constantly lowering the "optimal" LDL-C goals. However, old and new data point towards an association between low LDL-C and total cholesterol and intracerebral hemorrhage (ICH). In this review we aimed to shed light on this troubling association and identify the potential risk factors of such a potential adverse reaction. With respect to the data presented, we concluded that in patients with high risk of ICH, a cautious approach and individualized therapy strategy are advised when considering aggressive LDL reduction.

Low serum lipid levels, use of statin and cerebral microbleeds: A systematic review and meta-analysis

INTRODUCTION

Previous studies have shown that low serum lipids and statins may be related to cerebral hemorrhage. We made the meta-analysis to evaluate the associations between serum lipid levels or statins treatment and cerebral microbleeds (CMBs) to identify whether the similar correlation also existed.

METHOD

We comprehensively searched the Medline, Embase, Cochrane library, Web of Science, only included English journal articles, and systematically collected the observational studies and randomized controlled trials (RCTs) from September 1975 to August 2021. Random-effects model was used to pool data. Statistical heterogeneity was assessed by I² statistic and chi-square. 11 items checklists recommended by the Agency for Healthcare Research and Quality (AHRQ), Newcastle-Ottawa Scale (NOS), and Cochrane Risk of Bias tool (ROB) were used to evaluate the methodological quality of cross-sectional studies, cohort studies and randomized controlled trial, respectively.

RESULTS

Five cohort studies, two RCTs, and ten cross-sectional studies, including 16,637 subjects and 2663 CMBs patients, were included in our quantitative synthesis. Our study found that after adjusting the covariates, total cholesterol (TC) was significantly inversely correlated with the prevalent CMBs in any location, while total triglycerides (TG) and High-density lipoprotein (HDL) were significantly inversely associated with prevalent deep CMBs. Low-density lipoprotein (LDL) was negatively associated with incident CMBs after adjusted confounders. We did not found statistical differences between statin and CMBs after adjusted covariates.

CONCLUSION

Serum major lipid (TC TG HDL LDL) levels may be inversely associated with CMBs. Currently, no sufficient evidence proves that statin therapy is the risk factor of CMBs.

How unsaturated fatty acids and plant stanols affect sterols plasma level and cellular membranes? Review on model studies involving the Langmuir monolayer technique

The Langmuir monolayer technique has long been known for its usefulness to study the interaction between molecules and mimic cellular membranes to understand the mechanism of action of biologically relevant molecules. In this review we summarize the results that provided insight into the potential mechanism for lowering the plasma level of cholesterol by hypocholesterolemic substances (unsaturated fatty acids (UFAs) and phytocompounds) - in the aspect of prevention of atherosclerosis - and their effects on model biomembranes. The results on UFAs/cholesterol (oxysterols) interactions indicate that these systems are miscible and strongly interacting, contrary to immiscible systems containing saturated fatty acids. Lowering of cholesterol plasma level by UFAs was attributed to the strong affinity between UFAs and sterols, resulting in the formation of high stability complexes, in which sterols were bound and eliminated from the body. Studies on the effect of UFAs and plant sterols/stanols on simplified biomembranes (modeled as cholesterol/DPPC system) indicated that the studied hypocholesterolemic substances modify the biophysical properties of model membrane, affecting its fluidity and interactions between membrane components. Both UFAs and plant sterols/stanols were found to loosen interactions between DPPC and cholesterol and decrease membrane rigidity caused by the excess cholesterol in biomembrane, thus compensating strong condensing effect of cholesterol and restoring proper membrane fluidity, which is of utmost importance for normal cells functioning. The agreement between model - in vitro - studies and biological results prove the usefulness of the Langmuir monolayer technique, which helps in understanding the mode of action of biologically relevant substances.

Stroke-prone spontaneously hypertensive rats have reduced hydroxysteroid 17-β dehydrogenase 7 levels for low cholesterol biosynthesis

Reduced serum cholesterol content was recently reported to be one of the factors responsible for cerebral haemorrhage. Stroke-prone spontaneously hypertensive rats (SHRSP) are known to have lower serum cholesterol content than normotensive Wistar-Kyoto rats (WKY). We previously reported that lower levels of mevalonate pyrophosphate decarboxylase (MPD) and squalene epoxidase (SQE), which are associated with cholesterol biosynthesis in the liver, are involved in the low serum cholesterol content in SHRSP. Here, we investigate the levels of sterol 14-demethylase (CYP51), methylsterol monooxygenase (SC4MOL), and hydroxysteroid 17-β dehydrogenase 7 (HSD17B7), which contribute to the cholesterol synthesis pathway in the conversion of lanosterol to zymosterol, in SHRSP and WKY. The HSD17B7 mRNA levels in the liver of SHRSP were markedly lower than those in WKY, whereas no significant differences were observed in CYP51 and SC4MOL levels in the two types of rats. The relative levels of protein, heteronuclear RNA, and mRNA of HSD17B7 were also significantly lower in SHRSP than in WKY. The degradation rates of HSD17B7 were the same in SHRSP and WKY. The protein levels of HSD17B7 were not significantly reduced in tissues other than the liver, including the brain, lung, heart, spleen, kidney, and testis, in SHRSP. Moreover, HSD17B7 activity was significantly lower in SHRSP than in WKY. Thus, our results indicated that low protein levels and activity of HSD17B7 are responsible for the reduced cholesterol content in SHRSP, indicating that HSD17B7, along with MPD and SQE, is involved in the decreased cholesterol synthesis in the liver of SHRSP.

Low-Density Lipoprotein Cholesterol and Risk of Hemorrhagic Stroke: a Systematic Review and Dose-Response Meta-analysis of Prospective Studies

PURPOSE OF REVIEW

To systematically examine the association between low-density lipoprotein cholesterol (LDL-C) and risk of hemorrhagic stroke.

RECENT FINDINGS

A previous meta-analysis of prospective studies published in 2013 showed that higher concentrations of LDL-C were associated with lower risk of hemorrhagic stroke. Recently, seven large cohort studies were published examining LDL-C and risk of hemorrhagic stroke in different populations. Twelve prospective studies with 476,173 participants and 7587 hemorrhagic stroke cases were included in the current meta-analysis. The results showed that a 10 mg/dL increase in LDL-C was associated with 3% lower risk of hemorrhagic stroke (pooled relative risk [RR] 0.97, 95% confidence interval [CI] 0.95-0.98). The association appeared to be more pronounced in Asians (pooled RR 0.95, 95% CI 0.92-0.98), relative to Caucasians (pooled RR 0.98, 95% CI 0.97-1.00), with a p heterogeneity of 0.05 between two ethnic groups. Further genetic studies and clinical trials with a stricter safety monitoring strategy are warranted to understand the underlying pathogenesis and determine the treatment target of LDL-C range with the lowest risk of hemorrhagic stroke in different population groups.

Low-density lipoprotein cholesterol and risk of intracerebral hemorrhage: A prospective study

OBJECTIVE

To prospectively examine the association between low-density lipoprotein (LDL) cholesterol (LDL-C) concentrations and intracerebral hemorrhage (ICH) risk.

METHODS

The current cohort study included 96,043 participants (mean age 51.3 years) who were free of stroke, myocardial infarction, and cancer at baseline (2006). Serum LDL-C concentrations were assessed in 2006, 2008, 2010, and 2012. Cumulative average LDL-C concentrations were calculated from all available LDL-C data during that period. Incident ICH was confirmed by review of medical records.

RESULTS

We identified 753 incident ICH cases during 9 years of follow-up. The ICH risk was similar among participants with LDL concentrations of 70 to 99 mg/dL and those with LDL-C concentrations ≥100 mg/dL. In contrast, participants with LDL-C concentrations <70 mg/dL had a significantly higher risk of developing ICH than those with LDL-C concentrations of 70 to 99 mg/dL; adjusted hazard ratios were 1.65 (95% confidence interval [CI] 1.32-2.05) for LDL-C concentrations of 50 to 69 mg/dL and 2.69 (95% CI 2.03-3.57) for LDL-C concentrations <50 mg/dL.

CONCLUSIONS

We observed a significant association between lower LDL-C and higher risk of ICH when LDL-C was <70 mg/dL, and the association became nonsignificant when LDL-C ≥70 mg/dL. These data can help determination of the ideal LDL range in patients who are at increased risk of both atherosclerotic disease and hemorrhagic stroke and guide planning of future lipid-lowering studies.

Platelet function, coagulation and fibrinolysis in patients with previous coronary and cerebrovascular ischemic events

OBJECTIVES

Ischemic stroke (IS) or transient ischemic attack (TIA) history is present in 4-17% of patients with coronary artery disease (CAD). This subgroup of patients is at high risk for both ischemic and bleeding events. The aim of this study was to determine the role of platelet aggregability, coagulation and endogenous fibrinolysis in patients with CAD and previous IS or TIA.

METHODS

A prospective case-control study that included 140 stable CAD patients divided into two groups: the CASE group (those with a previous IS/TIA, n=70) and the CONTROL group (those without a previous IS/TIA, n=70). Platelet aggregability (VerifyNow Aspirin® and VerifyNow P2Y12®), coagulation (fibrinogen and thromboelastography by Reorox®) and endogenous fibrinolysis (D dimer and plasminogen activator inhibitor-1) were evaluated.

RESULTS

Patients in the CASE group presented significantly higher systolic blood pressure levels (135.84±16.09 vs 123.68±16.11, p<0.01), significantly more previous CABG (25.71% vs 10%, p=0.015) and significantly higher calcium channel blocker usage (42.86% vs 24.29%, p=0.02) than those in the control group. In the adjusted models, low triglyceride values, low hemoglobin values and higher systolic blood pressure were significantly associated with previous IS/TIA (CASE group). Most importantly, platelet aggregability, coagulation and fibrinolysis tests were not independently associated with previous cerebrovascular ischemic events (CASE group).

CONCLUSION

Platelet aggregability, coagulation and endogenous fibrinolysis showed similar results among CAD patients with and without previous IS/TIA. Therefore, it remains necessary to identify other targets to explain the higher bleeding risk presented by these patients.

Plant lipids: Key players of plasma membrane organization and function

The plasma membrane (PM) is the biological membrane that separates the interior of all cells from the outside. The PM is constituted of a huge diversity of proteins and lipids. In this review, we will update the diversity of molecular species of lipids found in plant PM. We will further discuss how lipids govern global properties of the plant PM, explaining that plant lipids are unevenly distributed and are able to organize PM in domains. From that observation, it emerges a complex picture showing a spatial and multiscale segregation of PM components. Finally, we will discuss how lipids are key players in the function of PM in plants, with a particular focus on plant-microbe interaction, transport and hormone signaling, abiotic stress responses, plasmodesmata function. The last chapter is dedicated to the methods that the plant membrane biology community needs to develop to get a comprehensive understanding of membrane organization in plants.

Membrane permeabilization of phosphatidylcholine liposomes induced by cryopreservation and vitrification solutions

Membranes are the primary site of freezing injury during cryopreservation or vitrification of cells. Addition of cryoprotective agents (CPAs) can reduce freezing damage, but can also disturb membrane integrity causing leakage of intracellular constituents. The aim of this study was to investigate lipid-CPA interactions in a liposome model system to obtain insights in mechanisms of cellular protection and toxicity during cryopreservation or vitrification processing. Various CPAs were studied including dimethyl sulfoxide (DMSO), glycerol (GLY), ethylene glycol (EG), dimethyl formamide (DMF), and propylene glycol (PG). Protection against leakage of phosphatidylcholine liposomes encapsulated with carboxyfluorescein (CF) was studied upon CPA addition as well as after freezing-and-thawing. Molecular interactions between CPAs and phospholipid acyl chains and headgroups as well as membrane phase behavior were studied using Fourier transform infrared spectroscopy. A clear difference was observed between the effects of DMSO on PC-liposomes compared to the other CPAs tested, both for measurements on CF-retention and membrane phase behavior. All CPAs were found to inhibit membrane leakiness during freezing. However, exposure to high CPA concentrations already caused leakage before freezing, increasing in the order DMSO, EG, DMF/PG, and GLY. With DMSO, liposomes were able to withstand up to 6M concentrations compared to only 1M for GLY. Cholesterol addition to PC-liposomes increased membrane stability towards leakiness. DMSO was found to dehydrate the phospholipid headgroups while raising the membrane phase transition temperature, whereas the other CPAs caused an increase in the hydration level of the lipid headgroups while decreasing the membrane phase transition temperature.

Thyroid Hormone Status in Sitosterolemia Is Modified by Ezetimibe

OBJECTIVES

To assess the association between biomarkers of thyroid status and 5α-stanols in patients with sitosterolemia treated with ezetimibe (EZE).

STUDY DESIGN

Eight patients with sitosterolemia (16-56 years of age) were studied during 14 weeks off EZE therapy and 14 weeks on EZE (10 mg/day). Serum thyroid biomarkers (free triiodothyronine [FT3], free thyroxine [FT4], FT3/FT4 ratio, thyroid-stimulating hormone), 5α-stanols (sitostanol and cholestanol), and cholestanol precursors (total cholesterol and its synthesis marker lathosterol, and 7α-hydroxy-4-cholesten-3-one cholestenol) were measured at baseline and during the 14 weeks off EZE and on EZE.

RESULTS

EZE increased FT3/FT4 (10% ± 4%; P = .02). EZE reduced plasma and red blood cells sitostanol (-38% ± 6% and -20% ± 4%; all P < .05) and cholestanol (-18% ± 6% and -13% ± 3%; all P < .05). The change in plasma cholestanol level on EZE inversely correlated with the change in FT3/FT4 (r = -0.86; P = .01). EZE lowered total cholesterol (P < .0001) and did not affect 7α-hydroxy-4-cholesten-3-one cholestanol. EZE increased (P < .0001) lathosterol initially, but the level was not sustained, resulting in similar levels at week 14 off EZE and on EZE.

CONCLUSION

In patients with STSL, 5α-stanols levels might be associated with thyroid function. EZE reduces circulating 5α-stanols while increasing FT3/FT4, implying increased conversion of T4 to T3, thus possibly improving thyroid hormone status.

TRIAL REGISTRATION

ClinicalTrials.govNCT01584206.

Effects of an extension of the equilibration period up to 96 hours on the characteristics of cryopreserved bull semen

This study was designed to investigate the effects of an equilibration period up to 96 hours and three extenders (AndroMed, OPTIXcell, and Triladyl) on the quality of cryopreserved bull semen and to evaluate, whether an extension of the equilibration time to 72 hours does affect fertility in the field. One ejaculate of 17 bulls was collected and divided into three equal aliquots and diluted, respectively, with the three extenders. Each aliquot was again divided into five parts and equilibrated for 4, 24, 48, 72, and 96 hours before freezing in an automatic freezer. Sperm motility, plasma membrane and acrosome integrity (PMAI), and DNA fragmentation index (% DFI) were measured during equilibration. In addition to the parameters measured during equilibration, the percentage of viable sperm cells with high mitochondrial membrane potential (HMMP) was measured immediately after thawing, and after 3 hours of incubation at 37 °C. Sperm motility was assessed using CASA, and PMAI, HMMP, and % DFI were measured using flow cytometry. Equilibration time did affect all parameters before freezing (P < 0.01), and also the extender affected all parameters except HMMP (P < 0.05). After thawing, all parameters except HMMP immediately after thawing were influenced by the equilibration period (P < 0.001), whereas all parameters except % DFI immediately after thawing were influenced by the extender (P < 0.001). The changes of semen characteristics during 3 hours of incubation were also dependent on the equilibration time and the extender used in all parameters (P < 0.01). In the field study, semen of nine bulls was collected thrice weekly, processed using Triladyl egg yolk extender, and frozen in 0.25 mL straws with 15 × 10⁶ spermatozoa per straw. In total, the nonreturn rates on Day 90 after insemination (NRR90) of 263,816 inseminations in two periods were evaluated. Whereas semen collected on Mondays and Wednesdays was equilibrated for 24 hours in both periods, semen collected on Fridays was equilibrated for 4 hours in period one and equilibrated for 72 hours in period 2. No differences in NRR90 could be found (P > 0.05). In conclusion, extension of the equilibration time from 4 hours to 24-72 hours can improve motility and viability of cryopreserved semen after thawing. The extent of improvement in semen quality is dependent on the extender used. Prolongation of the equilibration period from 4 hours to 72 hours had no effect on fertility in the field.

Phenotypic homogeneity with minor deviance in osmotic fragility of Sahel goat erythrocytes in non-ionic sucrose media during various physiologic states

BACKGROUND

Erythrocyte swelling in non-ionic sucrose media and the subsequent osmotic lysis are influenced by mechanisms of regulatory volume adjustment and osmotic water permeability. Kinetics of transmembrane water and ion fluxes in varied physiologic states may determine the phenotype of erythrocyte osmotic fragility (EOF) and affect estimates of EOF.

METHODS

Effects of sex, age, late pregnancy (third trimester) and lactation on the haemolysis of Sahel goat erythrocytes incubated in a series of hyposmotic non-ionic sucrose media were investigated.

RESULTS

The fragiligram was sigmoidal in 72 (97%) out of 74 goats. Two male (3%) goats with low and high extreme median erythrocyte fragilities (MEF), had non-sigmoidal curves. The mean fragilities at osmolarities of 30-300 mosmol/L of sucrose and the mean osmolarities responsible for 10%-90% haemolysis (CH10-CH90) were not significantly different between males and non-pregnant dry (NPD) females, amongst the age groups and between pregnant or lactating and NPD female goats. The MEF (CH50) of the goats were at osmolarities of 126-252 mosmol/L (median of data: 171 mosmol/L) with a mean of 175.24±16.20 mosmol/L. Therefore, phenotypic homogeneity of EOF occurred with minor deviance, since EOF variables were not differentiated by sex, age, late pregnancy or lactation.

CONCLUSIONS

Physiologic states of the goat did not affect EOF phenotype in non-ionic sucrose media. Sigmoidal fragility phenotype seemed to be homogeneously conserved by osmoregulatory mechanisms not partitioned by sex, age, late pregnancy or lactation, but a minor non-sigmoidal curve might have occurred due to altered erythrocyte osmotic behaviour that would require further investigation.

Serum cholesterol levels, HMG-CoA reductase inhibitors and the risk of intracerebral haemorrhage. The Multicenter Study on Cerebral Haemorrhage in Italy (MUCH-Italy)

OBJECTIVE

Although a concern exists that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) might increase the risk of intracerebral haemorrhage (ICH), the contribution of these agents to the relationship between serum cholesterol and disease occurrence has been poorly investigated.

METHODS

We compared consecutive patients having ICH with age and sex-matched stroke-free control subjects in a case-control analysis, as part of the Multicenter Study on Cerebral Haemorrhage in Italy (MUCH-Italy), and tested the presence of interaction effects between total serum cholesterol levels and statins on the risk of ICH.

RESULTS

A total of 3492 cases (mean age, 73.0±12.7 years; males, 56.6%) and 3492 control subjects were enrolled. Increasing total serum cholesterol levels were confirmed to be inversely associated with ICH. We observed a statistical interaction between total serum cholesterol levels and statin use for the risk of haemorrhage (Interaction OR (IOR), 1.09; 95% CI 1.05 to 1.12). Increasing levels of total serum cholesterol were associated with a decreased risk of ICH within statin strata (average OR, 0.87; 95% CI 0.86 to 0.88 for every increase of 0.26 mmol/l of total serum cholesterol concentrations), while statin use was associated with an increased risk (OR, 1.54; 95% CI 1.31 to 1.81 of the average level of total serum cholesterol). The protective effect of serum cholesterol against ICH was reduced by statins in strictly lobar brain regions more than in non-lobar ones.

CONCLUSIONS

Statin therapy and total serum cholesterol levels exhibit interaction effects towards the risk of ICH. The magnitude of such effects appears higher in lobar brain regions.

Genetic loci for serum lipid fractions and intracerebral hemorrhage

BACKGROUND

Serum total cholesterol and its fractions are inversely associated with intracerebral hemorrhages (ICH) and their potential subclinical precursor, cerebral microbleeds. To ascertain whether there is a genetic basis for this inverse association, we studied established genetic loci for serum total, LDL, and HDL cholesterol, and triglycerides in their association with ICH and microbleeds.

METHODS

Data on 161 genetic variants for serum lipids was collected in 9011 stroke-free participants (mean age 65.8, SD 10.2; 57.9% women) of the population-based Rotterdam Study. Participants were followed from baseline (1997-2005) up to 2013 for the occurrence of ICH. A subset of 4179 participants underwent brain MRI for microbleed assessment between 2005 and 2011. We computed genetic risk scores (GRS) for the joint effect of lipid variants. Cox proportional hazards and logistic regression models were used to investigate the association of GRS of lipid fractions with ICH and microbleeds.

RESULTS

After a mean follow-up of 8.7 (SD 4.1) years, 67 (0.7%) participants suffered an ICH. Microbleed prevalence was 19.6%. Higher genetic load for high serum total and LDL cholesterol was associated with an increased risk of ICH. Higher genetic load for high serum LDL cholesterol was borderline associated with a higher prevalence of multiple lobar microbleeds.

CONCLUSIONS

Genetic susceptibility for high serum total and LDL cholesterol is positively associated with incident ICH and borderline associated with multiple lobar microbleeds. We did not find a genetic basis for the previously reported inverse association between serum lipid levels and ICH.

Involvement of microRNA214 and transcriptional regulation in reductions in mevalonate pyrophosphate decarboxylase mRNA levels in stroke-prone spontaneously hypertensive rat livers

Hypocholesterolemia has been epidemiologically identified as one of the causes of stroke (cerebral hemorrhage). We previously reported that lower protein levels of mevalonate pyrophosphate decarboxylase (MPD), which is responsible for reducing serum cholesterol levels in stroke-prone spontaneously hypertensive rats (SHRSP), in the liver were caused by a reduction in mRNA levels. However, the mechanism responsible for reducing MPD expression levels in the SHRSP liver remains unclear. Thus, we compared microRNA (miR)-214 combined with the 3'-untranslated region of MPD mRNA and heterogeneous nuclear RNA (hnRNA) between SHRSP and normotensive Wistar Kyoto rats (WKY). miR-214 levels in the liver were markedly higher in SHRSP than in WKY, whereas hnRNA levels were significantly lower. These results indicate that the upregulation of miR-214 and downregulation of MPD transcription in the liver both play a role in the development of hypocholesterolemia in SHRSP.

Risk Factors for Early Hemorrhagic Progression after Traumatic Brain Injury: A Focus on Lipid Profile

The purpose of this study was to identify the risk factors related to the hemorrhagic progression (HP) of brain contusion in patients after traumatic brain injury (TBI). Recently, many studies have reported abnormal lipid levels associated with hemorrhagic stroke. Unlike hemorrhage stroke, however, the lipid profiles in patients with TBI have not been examined. Therefore, we evaluated the risk factors of HP in patients with TBI and focused on lipid profiles. Fifty-six patients with TBI with mild to moderate injuries (Glasgow Coma Scale ≥9) who initially did not need surgical intervention were enrolled in this study. Patients underwent repeated computed tomography (CT) scans at 4 h and 24 h after injury. Magnetic resonance imaging (MRI) was performed 7 days after the initial injury. In each noncontrast CT scan, the hemorrhage volume was quantified using the ABC/2 technique. Clinical features, previous medical history, initial CT, and microbleeding on follow-up MRI were analyzed retrospectively. There were 31 (55%) patients in whom significant HP developed (volume >30%). Current smoking (p=0.034), higher initial systolic blood pressure (p=0.035), and lower triglyceride levels (p=0.039) were significantly associated with HP. Current smoking and a triglyceride (TG) level <150 mg/dL were the only statistically significant predictors of HP in the multivariate analysis (p=0.019, p=0.021, respectively). HP with TBI is common in patients who currently smoke and have lower TG levels (150 mg/dL). These patients should be monitored closely, and surgery may be considered before deterioration occurs.

The effect of β-sitosterol on the properties of cholesterol/phosphatidylcholine/ganglioside monolayers--the impact of monolayer fluidity

In this paper the influence of one of phytosterols, namely β-sitosterol on cholesterol (Chol)/phosphatidylcholine (PC)/ganglioside (GM3) monolayers was examined to find the correlation between the properties of model system and the effect of phytocompound. The studied monolayers differed in condensation and fluidity, which were modified by the structure of phosphatidylcholine. It was found that the incorporation of β-sitosterol into cholesterol/phosphatidylcholine/ganglioside films changes their morphology, condensation and interactions between the lipids. The substitution of cholesterol more strongly decreased the condensation and stability of the film containing PC molecules having monounsaturated chains than more densely packed monolayer composed of saturated phosphatidylcholine. However, thorough analysis of data obtained so far suggests that the magnitude of β-sitosterol effect is determined by the composition of the system rather than its fluidity itself. Moreover, the results collected herein correlate well with the findings that phytosterol more strongly inhibits the growth of cancer cells, which at a given proportion of cholesterol to phospholipids in membranes, have more unsaturated fatty acids within phospholipids molecules.

Low cholesterol as a risk factor for primary intracerebral hemorrhage: A case-control study

Introduction:

An inverse association between serum cholesterol and the risk of hemorrhagic stroke has been noted in epidemiological studies. We performed a case–control study to assess the relationship between primary intracerebral hemorrhage (ICH) and low serum cholesterol.

Materials and Methods:

Prospectively recruited fully evaluated patients with ICH were compared with a control group based in a primary care practice, i.e. age- and sex-matched individuals attending the routine preventive health check-up. Low cholesterol was defined by the sex-specific lowest quintile of the population.

Results:

The proportion of ICH patients with low cholesterol was significantly higher than the controls (68% vs. 43%). Mean total cholesterol was also signficantly low in ICH patients compared with controls (177 mg/dL vs. 200 mg/dl; P-value = 0.0006). Low-density lipoprotein cholesterol (LDL-c) and triglycerides were also significantly low in ICH patients compared with controls. Mean LDL-C in the ICH patient group was 114 mg/dL, whereas it was 128.5 mg/dL in the control group (P-value = 0.016). There was no significant difference in the high-density lipoprotein (HDL) levels in both groups. In a subgroup analysis, both men and women in the ICH group had a significantly low mean cholesterol compared with the control group. Although lower mean cholesterol was seen in both young and older individuals in the ICH group than in controls, the difference was significant only in the older group (age >45 years). In multivariate analysis, presence of low cholesterol remained a significant predictor of hemorrhage. The odds ratio of low cholesterol in the hemorrhage cases was 2.75 (95% CI = 1.44–5.49) unadjusted and 2.15 (1.13–4.70) adjusted for age and hypertension.

Conclusions:

This study confirms an increased risk of primary ICH associated with low cholesterol both in men and women, especially in older individuals.

Formation and diffusivity characterization of supported lipid bilayers with complex lipid compositions

The moving edge of a hydrodynamically manipulated supported lipid bilayer (SLB) can be used to catalyze SLB formation of adsorbed lipid vesicles that do not undergo spontaneous SLB formation upon adsorption on SiO(2). By removing the lipid reservoir of an initially formed SLB, we show how a hydrodynamically moved SLB patch composed of POPC can be used to form isolated SLBs with compositions that to at least 95% represent that of the adsorbed lipid vesicles. The concept is used to investigate the diffusivity of lissamine rhodamine B 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (rhodamine-DHPE) in SLBs made from complex lipid compositions, revealing a decrease in diffusivity by a factor of 2 when the cholesterol content was increased from 0% to 50%. We also demonstrate how the concept can be used to induce stationary domains in SLBs containing 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and cholesterol (39:21:40 mol %, respectively). Because the method serves as a means to form SLBs with lipid compositions that hamper SLB formation via spontaneous rupture of adsorbed lipid vesicles, it opens up the possibility for new biophysical investigations of SLBs with more nativelike compositions.

Liposomes for cryopreservation of bovine sperm

In this study, the effect of various unilamellar liposomes on cryopreservation of bovine spermatozoa has been investigated. Liposomes were composed of saturated lipids with various acyl chain lengths: DSPC (18:0), DPPC (16:0), DMPC (14:0), or DLPC (12:0). Alternatively, liposomes were prepared using unsaturated egg phosphatidylcholine (EPC) or DOPC (18:1, neutral), alone or in combination with lipids with various head groups: DOPS (negatively charged), DOPG (negatively charged), and DOPE (neutral). Fourier transform infrared spectroscopy studies showed that bovine sperm membranes display a gradual phase transition from 10 to 24 (o)C. Phase transition temperatures of the liposomes varied from -20 to +53 (o)C. Sperm was incubated in the presence of liposomes for either 6 or 24 h at 4 °C prior to freezing. Postfreeze survival rates were determined based on the percentage of progressively motile cells as well as the percentage of acrosome- and plasma membrane-intact cells. With DOPC liposomes a postthaw progressive motility of 43% was obtained compared with 59% using standard egg yolk freezing extender. Postthaw progressive motility increased up to 52% using DOPC:DOPG (9:1) liposomes, whereas DOPC:DOPS or DOPC:DOPE liposomes did not increase survival compared with DOPC liposomes. Among the saturated lipids, only DMPC was found to increase cryosurvival, up to 44% based on progressive motility. DLPC liposomes caused a complete loss in cell viability, already prior to freezing, whereas DPPC and DSPC liposomes neither positively nor negatively affected cryosurvival. Taken together, the higher postthaw survival obtained with DOPC:DOPG liposomes as compared with DOPC liposomes can likely be attributed to increased liposome-sperm interactions between the charged phosphatidylglycerol groups and charged regions in the sperm membranes. Interestingly, the lipid phase state of the liposomes during preincubation is not the decisive factor for their cryoprotective action.

Liposomes composed of unsaturated lipids for membrane modification of human erythrocytes

Previous studies have shown that certain saturated lipids protect red blood cells (RBCs) during hypothermic storage but provide little protection during freezing or freeze-drying, whereas various unsaturated lipids destabilize RBCs during hypothermic storage but protect during freezing and freeze-drying. The protective effect of liposomes has been attributed to membrane modifications. We have previously shown that cholesterol exchange and lipid transfer between liposomes composed of saturated lipids and RBCs critically depends on the length of the lipid acyl chains. In this study the effect of unsaturated lipids with differences in their number of unsaturated bonds (18:0/18:1, 18:1/18:1, 18:2/18:2) on RBC membrane properties has been studied. RBCs were incubated in the presence of liposomes and both the liposomal and RBC fraction were analyzed by Fourier transform infrared spectroscopy (FTIR) after incubation. The liposomes caused an increase in RBC membrane conformational disorder at suprazero temperatures. The fluidizing effect of the liposomes on the RBC membranes, however, was found to be similar for the different lipids irrespective of their unsaturation level. The gel to liquid crystalline phase transition temperature of the liposomes increased after incubation with RBCs. RBC membrane fluidity increased linearly during the first 8 hours of incubation in the presence of liposomes. The increase in RBC membrane fluidity was found to be temperature dependent and displayed Arrhenius behaviour between 20 and 40°C, with an activation energy of 88 kJ mol⁻¹. Taken together, liposomes composed of unsaturated lipids increase RBC membrane conformational disorder, which could explain their cryoprotective action.

Serum lipid levels and the risk of intracerebral hemorrhage: the Rotterdam Study

OBJECTIVE

Low serum total cholesterol levels are associated with an increased risk of symptomatic intracerebral hemorrhage and with presence of asymptomatic cerebral microbleeds. The relative contribution of lipid fractions to these associations is unclear and requires investigation. We determined whether serum HDL-cholesterol, LDL-cholesterol, and triglycerides are associated with risk of intracerebral hemorrhage and presence of cerebral microbleeds.

METHODS AND RESULTS

Nine thousand sixty-eight stroke-free community-dwelling persons aged ≥55 were followed from baseline (1990-2001) up to January 1, 2009, of whom 85 suffered from intracerebral hemorrhage during follow-up. Brain MRI was carried out in 789 healthy participants, of whom 162 had cerebral microbleeds. Triglycerides were strongly and inversely associated with intracerebral hemorrhage, independently of HDL-cholesterol, LDL-cholesterol, and potential confounders [hazard ratio for highest versus lowest quartile: 0.20 (0.06-0.69)]. Triglycerides were also associated with deep or infratentorial microbleeds [odds ratio for highest versus lowest quartile: 0.37 (0.14-0.96)], but not with strictly lobar microbleeds. No associations were found for HDL-cholesterol or LDL-cholesterol.

CONCLUSIONS

Low serum triglyceride levels were associated with an increased risk of intracerebral hemorrhage and with the presence of deep or infratentorial cerebral microbleeds. This provides novel insights into the role of lipid fractions, particularly triglycerides, in the etiology of intracerebral hemorrhage.

Membrane Stability during Biopreservation of Blood Cells

SUMMARY: Storage methods, which can be taken into consideration for red blood cells and platelets, include liquid storage, cryopreservation and freeze-drying. Red blood cells can be hypothermically stored at refrigerated temperatures, whereas platelets are chilling sensitive and therefore cannot be stored at temperatures below 20 °C. Here we give an overview of available cryopreservation and freeze-drying procedures for blood cells and discuss the effects of these procedures on cells, particularly on cellular membranes. Cryopreservation and freeze-drying may result in chemical and structural modifications of cellular membranes. Membranes undergo phase and permeability changes during freezing and drying. Cryo- and lyoprotective agents prevent membrane damage by different mechanisms. Cryoprotective agents are preferentially excluded from membrane surfaces. They decrease the activation energy for water transport during freezing and control the rate of cellular dehydration. Lyoprotectants are thought to stabilize membranes during drying by forming direct hydrogen bonding interactions with phospholipid head groups. In addition, lyoprotectants can form a glassy state at room temperature. Recently liposomes have been investigated to stabilize blood cells during freezing and freeze-drying. Liposomes modify the composition of cellular membranes by lipid and cholesterol transfer, which can stabilize or destabilize the low temperature response of cells.

Risk factors for intracerebral hemorrhage in a pooled prospective study

BACKGROUND AND PURPOSE

Few prospective studies have reported risk factors for intracerebral hemorrhage (ICH), and results are inconsistent. We studied risk factors for ICH in a pooled cohort of the Atherosclerosis Risk in Communities Study (ARIC) and the Cardiovascular Health Study (CHS).

METHODS

The ARIC cohort was recruited in 1987 to 1989 and involves 15 792 men and women, aged 45 to 64 years at baseline, sampled from 4 US communities. The CHS cohort was recruited in 1989 to 1993 and involves 5888 men and women, aged 65 or over at baseline, sampled from 4 US communities. Baseline measurements included many potential vascular risk factors. The cohorts were followed for incident stroke events.

RESULTS

Over 263 489 person-years of follow-up, 135 incident ICH events occurred. In a multivariable model, age, African-American ethnicity (versus Whites), and hypertension were positively associated with incident ICH, whereas low-density lipoprotein cholesterol and triglycerides were inversely related to incident ICH. Participants with systolic blood pressure >or=160 mm Hg or diastolic blood pressure >/=110 mm Hg had 5.55 (95% CI 3.07 to 10.0) times the rate of ICH as nonhypertensives. Sex, smoking, alcohol intake, body mass index, waist-to-hip ratio, waist circumference, and diabetes were not related to ICH.

CONCLUSIONS

In this pooled cohort the risk factors for ICH were older age, African-American ethnicity, hypertension, lower LDL-C, and lower triglycerides.

Plant sterol or stanol consumption does not affect erythrocyte osmotic fragility in patients on statin treatment

OBJECTIVE

To assess the effects of plant sterol or stanol ester consumption on their incorporation into erythrocytes and their effects on osmotic fragility of red blood cells.

DESIGN

Double-blind, randomized, placebo-controlled intervention trial.

SUBJECTS AND INTERVENTION

Forty-one subjects on stable statin treatment - who already have increased serum plant sterol and stanol concentrations - first received for 4 weeks a control margarine. For the next 16 weeks, subjects were randomly assigned to one of three possible interventions. Eleven subjects continued with control margarine, 15 subjects with plant sterol ester enriched and 15 subjects with plant stanol ester-enriched margarine. Daily plant sterol or stanol intake was 2.5 g. Erythrocyte haemolysis was measured spectrophotometrically at five different saline concentrations.

RESULTS

Despite significant (P = 0.004) increases of, respectively, 42 and 59% in cholesterol-standardized serum sitosterol and campesterol concentrations in the plant sterol group as compared to the control group, campesterol levels in the red blood cells did not change (P = 0.196). Osmotic fragility did not change significantly (P = 0.757) in the plant sterol and plant stanol groups as compared to the control group.

CONCLUSION

We conclude that plant sterol and stanol ester consumption for 16 weeks does not change osmotic fragility of erythrocytes in statin-treated patients.

SPONSORSHIP

Netherlands Organisation for Health Research and Development (Program Nutrition: Health, Safety and Sustainability, Grant 014-12-010).