Increases in serum lipid and lipoprotein levels with movement from the supine to standing position in adult men and women

Relationship between dyslipidemia and diabetic retinopathy in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Diabetic retinopathy (DR) affects more than 80% of patients with diabetes. However, literature on the association between serum lipids and DR in patients with type 2 diabetes mellitus (T2DM) is inconsistent. Hence, in this study, we aimed to investigate the relationship between baseline serum lipids and the incidence of DR in patients with T2DM.

METHODS

We searched relevant articles in the PubMed, Embase databases, and the Cochrane Library up to February 7, 2022, and reviewed the reference lists of the included articles to identify appropriate cohort studies. The weighted mean difference (WMD) and the corresponding 95% confidence intervals (CIs) were calculated.

RESULTS

Thirteen cohort studies, including 7459 participants, were included in the present study. Higher levels of total cholesterol (2.94 mg/dL, 95% CI 1.32, 4.56), triglycerides (8.13 mg/dL, 95% CI 5.59, 10.66), and low-density lipoprotein cholesterol (2.53 mg/dL, 95% CI 1.02, 4.04) at baseline were observed in patients with later onset of DR. However, no significant difference in the high-density lipoprotein cholesterol level (0.27 mg/dL, 95% CI - 0.91, 1.45) was observed between patients with DR and without DR.

CONCLUSION

The present results suggest that baseline triglyceride and cholesterol levels are significantly associated with the occurrence of DR in patients with T2DM. Thus, patients with T2DM may benefit from lowering serum lipids. Future studies exploring the relationship between longitudinal changes in serum lipids and DR occurrence are warranted.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022319978.

Fasting, non-fasting and postprandial triglycerides for screening cardiometabolic risk

Fasting triacylglycerols have long been associated with cardiovascular disease (CVD) and other cardiometabolic conditions. Evidence suggests that non-fasting triglycerides (i.e. measured within 8 h of eating) better predict CVD than fasting triglycerides, which has led several organisations to recommend non-fasting lipid panels as the new clinical standard. However, unstandardised assessment protocols associated with non-fasting triglyceride measurement may lead to misclassification, with at-risk individuals being overlooked. A third type of triglyceride assessment, postprandial testing, is more controlled, yet historically has been difficult to implement due to the time and effort required to execute it. Here, we review differences in assessment, the underlying physiology and the pathophysiological relevance of elevated fasting, non-fasting and postprandial triglycerides. We also present data suggesting that there may be a distinct advantage of postprandial triglycerides, even over non-fasting triglycerides, for early detection of CVD risk and offer suggestions to make postprandial protocols more clinically feasible.

Time required for resetting postural effects on serum constituents in healthy individuals

OBJECTIVE

We investigated postural effects on concentrations of commonly measured serum analytes and sought for optimal duration of sitting before venipuncture in an outpatient setting.

METHODS

Seven healthy volunteers changed posture serially at 30-minute (min) intervals from lying, sitting, slowly walking, sitting, and to lying again. At the end of the first lying posture, wing-needle was inserted into cubital vein and 3mL of blood was drawn every 5min. All the serum was stored at -80°C until the time of collective measurements for 16 major chemistry analytes two weeks later.

RESULTS

Concentrations of macromolecular analytes (albumin, total cholesterol, alkaline phosphatase, etc.) in supine position were increased (on average 5-7%) after 30min of sitting and further increased (10-14%) during 30min of walking. After slow walking, time required for return of values to the levels of sitting posture took approximately 20min. Concentrations of small molecules (sodium, urea, etc.) did not show any variation by the postural changes. Potassium and inorganic phosphate showed walking-related increase in concentrations. Creatinine was lowered in sitting posture, which implicates postural changes in renal flow.

CONCLUSION

It is generally recommended to sit for 20min or more before venipuncture, although the effect of prior physical movement remains a little longer for potassium and inorganic phosphate.

European Health Examination Survey--towards a sustainable monitoring system

BACKGROUND

 Health examination surveys (HESs), including both questionnaire and physical measurements, and in most cases also collection of biological samples, can provide objective health indicators. This information complements data from health interview surveys and administrative registers, and is important for evidence-based planning of health policies and prevention activities. HESs are valuable data sources for research. The first national HESs in Europe were conducted in the late 1950s and early 1960s. They have recently been carried out in an increasing number of countries, but there has been no joint standardization between the countries.

METHODS

The European Health Examination Survey Pilot Project was conducted in 2009-2012. The European Health Examination Survey Pilot Reference Centre was established and pilot surveys were conducted in 12 countries.

RESULTS

 European standardized protocols for key measurements on main chronic disease risk factors (height, weight, waist circumference, blood pressure, blood lipids and fasting glucose or HbA1c) were prepared. European-level training and external quality assessment were organized. Although the level of earlier experience, infrastructures, economic status and cultural settings varied between the pilot countries, it was possible to standardize measurements of HESs across the populations. Obtaining high participation rates was challenging.

CONCLUSION

 HESs provide high-quality and representative population data to support policy decisions and research. For future national HESs, centralized coordination, training and external quality assessment are needed to ensure comparability of the results. Further studies on effects of different survey methods on comparability of the results and on recruitment and motivation of survey participants are needed.

The Pakistan Risk of Myocardial Infarction Study: a resource for the study of genetic, lifestyle and other determinants of myocardial infarction in South Asia

The burden of coronary heart disease (CHD) is increasing at a greater rate in South Asia than in any other region globally, but there is little direct evidence about its determinants. The Pakistan Risk of Myocardial Infarction Study (PROMIS) is an epidemiological resource to enable reliable study of genetic, lifestyle and other determinants of CHD in South Asia. By March 2009, PROMIS had recruited over 5,000 cases of first-ever confirmed acute myocardial infarction (MI) and over 5,000 matched controls aged 30-80 years. For each participant, information has been recorded on demographic factors, lifestyle, medical and family history, anthropometry, and a 12-lead electrocardiogram. A range of biological samples has been collected and stored, including DNA, plasma, serum and whole blood. During its next stage, the study aims to expand recruitment to achieve a total of about 20,000 cases and about 20,000 controls, and, in subsets of participants, to enrich the resource by collection of monocytes, establishment of lymphoblastoid cell lines, and by resurveying participants. Measurements in progress include profiling of candidate biochemical factors, assay of 45,000 variants in 2,100 candidate genes, and a genomewide association scan of over 650,000 genetic markers. We have established a large epidemiological resource for CHD in South Asia. In parallel with its further expansion and enrichment, the PROMIS resource will be systematically harvested to help identify and evaluate genetic and other determinants of MI in South Asia. Findings from this study should advance scientific understanding and inform regionally appropriate disease prevention and control strategies.

Patient hydration: a major source of laboratory uncertainty

Movement of body water from compartment to compartment during any time period is attributable to forces active within and upon each space. The result of these forces leads to transfer of water between intravascular and extravascular compartments, as well as shifts between extracellular and intracellular spaces. The importance of these shifts and of the associated mechanism was described by Ernest Starling in 1896 in very much the same manner as it is viewed today. The end result of fluid transfer and its physiological and laboratory consequences has not been fully appreciated. Despite awareness that fluid shifts can affect laboratory analytical results, little recent investigation has addressed the problem in the routine clinical laboratory. Thus, the potential for significant misinterpretation remains. For example, it is known that individual laboratory test values can vary widely, depending on many factors including the subject's posture during and immediately before phlebotomy, leading to significant changes in the interpretation of blood analyte values. Furthermore, a variety of ubiquitous environmental effects have additional impact on fluid distribution and thus on test values. In other words, patient hydration status is a major pre-analytical variable that needs to be addressed by the clinical laboratory. The need to adjust data for patient hydration status is especially important in the case of colloid analytes for which the dynamic range includes a narrow "gray zone" where hydration changes of a few percentage points can change the clinical implications. The crucial importance of this adjustment is underscored by the fact that neither the testing laboratory nor the clinician are aware of this unseen circumstance and are thus compelled to work with data that do not necessarily reflect the clinical situation.

Standardization of total cholesterol measurement in population surveys--pre-analytic sources of variation and their effect on the prevalence of hypercholesterolaemia

BACKGROUND

The estimation of population distribution of total cholesterol, as well as other blood lipids requires population surveys. Comparability of the estimates over time or between populations requires a predefined, standardized measurement protocol. This paper will assess the effect of variation in the pre-analytic procedures, on the estimation of population distribution of total cholesterol and the prevalence of hypercholesterolaemia. Implications of variation to real survey results are demonstrated on data collected during the WHO MONICA Project.

DESIGN AND METHODS

The extent (%) of pre-analytic variations were determined by literature review. Simulations were then used to estimate the effect of these variations on the distribution of total cholesterol values. Three populations were selected as examples for different population distributions of total cholesterol levels and variations resulting from seasonal and postural changes, use of tourniquet, and serum versus plasma collection were simulated both individually and in combinations.

RESULTS

Depending on the population distribution of total cholesterol, differences in pre-analytic procedures can explain a difference of up to 1.12 mmol/l in the mean total cholesterol between populations, and a difference up to 41% in the prevalence of hypercholesterolaemia (> or =6.5 mmol/l).

CONCLUSIONS

Variation in results on measured total cholesterol levels due to differences in procedures during the pre-analytic stage can diminish substantially the reliability and comparability of measurements among surveys over time and between populations. The effect of pre-analytic variation in the population estimates of total cholesterol can be extensively reduced by standardization and training.

The effects of errors in lipid measurement and assessment

Accurate cholesterol and lipoprotein measurements have provided dependable and powerful basic risk factors for cardiovascular disease. A battery of total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and triglycerides (TG) is recommended in the initial evaluation for classification of patients (based on lipids) into highly desirable, desirable, borderline, high, and very high lipid risk factor for cardiovascular disease. Treatment is based largely on the LDL cholesterol measurement result of the patient. The risk factor score of a patient greatly increases when other risk factors for cardiovascular disease exist, along with increased lipid risk factors. Attainment of the needed acceptable accurate lipid and lipoprotein measurements depends upon prevention or control of multiple sources of errors or variation that can exist in preanalytic, analytic, and postanalytic stages of determination of the reported result. Highly important is to control nonfasting, posture, diet, and alcohol intake in the preanalytic part, elimination of matrix effects and use of accurate calibrators in the analytic part, and check for transcription errors in preparation of reports in the postanalytic part of the measurement of lipids.

Changes in plasma homocyst(e)ine in the acute phase after stroke

BACKGROUND AND PURPOSE

Elevated plasma homocyst(e)ine [H(e)] concentration has been associated with an increased risk of stroke. Although the literature suggests that H(e) increases from the acute to the convalescent phase after a stroke, it is not known whether H(e) changes within the acute period.

METHODS

A prospective, multicenter study was conducted to examine changes in H(e) during the 2 weeks after an incident stroke. Blood samples were collected at days 1, 3, 5, 7, and between 10 and 14 days after the stroke.

RESULTS

Seventy-six participants (51 men) were enrolled from 9 sites from February 1997 through June 1998. Mean age was 65.6 years, and subjects had at least two H(e) measurements. The estimated mean H(e) level at baseline was 11.3+/-0.5 micromol/L, which increased consistently to a mean of 12.0+/-0.05, 12.4+/-0.5, 13.3+/-0.5, and 13.7+/-0.7 micromol/L at days 3, 5, 7, and 10 to 14, respectively. The magnitude of the change in H(e) was not affected by age, sex, smoking status, alcohol use, history of hypertension or diabetes, or Rankin Scale Score.

CONCLUSIONS

; These data suggest that the clinical interpretation of H(e) after stroke and the eligibility for clinical trials assessing treatment for elevated H(e) levels require an adjustment in time since stroke to properly interpret the observed H(e) levels.

Monthly intra-individual variation in lipids over a 1-year period in 22 normal subjects

OBJECTIVES

Previous reports on biological variation in lipids differ widely in the time interval between sampling, the number of samples analyzed per patient and the total study period. The present investigation was carried out to determine monthly intra-individual variation in lipids over 1 year and to establish whether there was a consistent change in lipid values over the summer months. The importance of taking this variation into consideration during the assessment of risk of coronary heart disease (CHD) was also examined.

DESIGN AND METHODS

Cholesterol, triglycerides, HDL, apo A1, and apo B were measured at monthly intervals for 12 months in 22 healthy, free-living volunteers (11 females, 11 males) by standardized methods.

RESULTS

When compared to analytical variation, biological variation was the dominant component of the intra-individual changes observed during the 1-year study period. As expected, triglycerides showed the greatest biological variation; the ratio of biological/analytical variation was 33.1. Much smaller ratios were observed for the other lipids measured in this study with values ranging from 4.2 to 6.8. Different subjects attained their maximum and minimum values in virtually every month of the year. There were significant reductions in cholesterol, HDL, LDL, and apo A1 in the summer months while triglycerides showed a non-significant increase and apo B a non-significant decrease during this period.

CONCLUSIONS

All the analytes showed considerable intra-individual variation. It is, therefore, important to measure lipids sequentially over several weeks to arrive at an average value for risk stratification for CHD.

Declining cholesterol and mortality in a sample of older nursing home residents

OBJECTIVE

To examine the association between declining serum cholesterol and mortality in a sample of older nursing home residents.

DESIGN

A retrospective cohort study.

SETTING

A 203-bed nursing home.

PARTICIPANTS

Persons aged 65 and older, resident in the nursing home on January 1, 1988, or admitted through December 31, 1989, were eligible (n = 185) for the study. Follow-up for mortality was conducted until June 30, 1991. Fifty-five survivors with two or more cholesterol levels recorded before January 1, 1990, and the 76 decedents with two or more recorded cholesterol levels constituted the analytic sample (71% of eligible subjects).

OUTCOME MEASURE

Mortality of the nursing home residents.

RESULTS

Cholesterol declined 31.1 mg/dL/yr (95% confidence interval [CI], 19.7 to 42.6) among decedents, versus 4.2 mg/dL/yr (95% CI, -4.9 to 13.2) among survivors. The association between cholesterol decline (absolute or relative rates) and mortality was examined using logistic regression controlling for age, sex, and tube feeding. Compared with a referrent group with no change or increase, declining cholesterol greater than 45 mg/dL/yr was accompanied by an adjusted relative odds for death of 6.2 (95% CI, 2.1 to 18.4); declining cholesterol greater than 20% per year was accompanied by an adjusted relative odds for death of 7.3 (95% CI; 2.4 to 22.2). Extreme declines greater than 20% per year occurred in 47% of decedents but in only 15% of survivors.

CONCLUSION

Precipitously declining cholesterol appeared to be a marker for mortality in the sample and may help explain the low cholesterol-mortality association in older nursing home residents.

Pronounced and rapid plasma volume reduction upon quiet standing as revealed by a novel approach to the determination of the intravascular volume change

Plasma volume (PV) changes to 15 min quiet standing were analysed (Hb/Hct-alterations) in two studies (nine and 11 healthy males). Data confirmed and extended our findings that blood, arterial or venous, sampled on standing fails to reveal the induced overall haemoconcentration (PV loss). First, standing led to markedly incomplete mixing of blood between circulatory compartments. Secondly, with sampling of antecubital venous blood, haemoconcentration was strongly affected by regional plasma loss and, apparently equally important, by regional blood flow. These difficulties were circumvented, however, by the finding that the PV restitution (haemoconcentration) in the recumbent subject after standing fitted invariably a monoexponential function with striking precision. It allowed, by extrapolation, a seemingly superior definition of the PV reduction at the very end of standing as supported by the fact that PV changes from Hb/Hct and from IgM protein concentration changes were similar, refuting that Fcell-changes contributed to the pronounced Hb/Hct changes. The described novel approach revealed a nicely reproducible PV loss of no less than 692 +/- 46 mL (18.1 +/- 0.6%, Study I; 18.4 +/- 0.5%, Study II), or approximately 11% reduction of blood volume, showing that quiet standing leads to a much more rapid and haemodynamically important decrease in PV than reported previously. Yet, PV was virtually restored within 20 min of recumbency after standing, with 50% recovery within 6 min and regain of as much as 70 mL in the very first min. The latter data indicate that the body possesses a surprising capacity for rapid fluid transfer from the extra- to the intravascular space.

Acute psychological stress and epinephrine infusion in normolipidemic and hyperlipidemic men: effects on plasma lipid and apoprotein concentrations

This study examined whether psychological stress and the infusion of epinephrine increase plasma lipid and apoprotein concentrations in normolipidemic and hyperlipidemic men. Subjects were studied during three separate 6-hour laboratory sessions: a control session, during which subjects rested quietly while blood samples and hemodynamic measurements were obtained; a stress session, during which subjects were presented with two challenging mental tasks, followed by quiet rest; and an epinephrine infusion session, during which subjects received a low-dose infusion of epinephrine followed by quiet rest. The stress and epinephrine infusion manipulations produced the expected changes in plasma epinephrine and norepinephrine levels, blood pressure, and heart rate. Free fatty acid concentration increased markedly during epinephrine infusion and less dramatically but consistently during mental stress. Both stress and epinephrine infusion produced acute increases in plasma total, low-density lipoprotein, very low-density lipoprotein, and high-density lipoprotein cholesterol and apoprotein B concentrations, but comparable increases during the control session were not observed. Changes in albumin concentration (an index of plasma volume) were associated with changes in lipid concentrations during psychological stress. Epinephrine increases during psychological stress were correlated with increases in free fatty acid and triglyceride levels both during and after task administration. It was concluded that psychological or pharmacological stress induced in the laboratory produces changes in lipid concentrations, which at least during psychological stress, may be attributed to concomitant changes in plasma volume. The association between task-induced changes in epinephrine and changes in free fatty acid and triglyceride levels, also supports the hypothesis that psychological stress increases lipolysis.

Acute effects of exercise on plasma lipids, noradrenaline levels and plasma volume

1. Total plasma cholesterol, high-density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), noradrenaline, haematocrit, haemoglobin and heart rate were measured in blood sampled from an antecubital vein in nine volunteers after 1 min standing and at intervals up to 1 h following 5 min of vigorous bicycle exercise. 2. Heart rates and plasma noradrenaline levels rose substantially immediately following exercise and gradually returned toward baseline levels 60 min post-exercise. 3. Total plasma cholesterol levels rose by 24% immediately post-exercise and slowly returned to baseline levels 60 min post-exercise. Similar changes were observed for LDL-C (20.2%) and HDL-C (27.7%). As a result, LDL:HDL ratios did not alter. 4. These changes in total plasma cholesterol, HDL-C and LDL-C were explained by changes in plasma volume that occurred as a consequence of vigorous exercise. 5. Changes in plasma volume may be a mechanism by which some environmental factors such as stress are associated with elevated plasma cholesterol levels.

Outcome of cholesterol screening in a community pharmacy

The purpose of our study was to determine if a community pharmacist could affect total blood cholesterol (TBC) of ambulatory patients by a program of education, consultation, and cholesterol screening. Of 241 initially screened individuals, 57 patients with TBC greater than 5.17 mmol/L (greater than 200 mg/dL) met the inclusion criteria of this six-month study. Of these, 51 completed the study. Outcome was determined by changes in TBC measured during the initial screening and after two follow-up visits. Pharmacist intervention included obtaining TBC concentrations and reporting the results to patients, teaching patients about the role of cholesterol in illness and health, explaining risk factors associated with cardiovascular disease, and providing follow-up communication with patients. Data were analyzed using ANOVA, Mann-Whitney, and chi-square. The mean TBC was 5.84 mmol/L (225.7 mg/dL) for the study group and 4.23 mmol/L (163.8 mg/dL) for participants with TBC less than 5.17 mmol/L (less than 200 mg/dL (p less than 0.0001). There was a significant difference (p = 0.0124) in mean age for the study group (36.4 years) versus other participants (30.0 years) but no difference in distribution by gender (p = 0.18). ANOVA showed significant differences in TBC during the three visits (p less than 0.0001). There was a significant decrease in mean TBC concentrations between visits 1 and 2 and between visits 1 and 3 (p less than 0.0001), but no difference between visits 2 and 3 (p = 0.48). Compared with mean baseline values, 81.4 and 72.6 percent of the patients had a decline in TBC at visits 2 and 3, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet collection with the Autopheresis-C apheresis system

This report describes a new system for collection of platelet concentrate (PC) and cell-free plasma (PPP) from apheresis donors. The system uses two separation devices and requires only a single venipuncture. The Plateletcell device separates primary platelet concentrate (PPC) from anticoagulated whole blood and the Plasmacell-C device separates the PPC into PC and PPP. Results of functional studies performed indicate that the separation process does not alter viability of either the PPC, the PC, or the PPP. Platelet function after 5 days of storage is maintained. An average yield of 3.4 +/- 0.7 x 10(11) platelets in 201 g of PC and 422 g of PPP were harvested in 71 +/- 13 min of donor time from donors with preprocedure hematocrits averaging 42.5 +/- 2.0% and preprocedure platelet counts averaging 265 +/- 61 x 10(3)/microliters.

Influences of the normal menstrual cycle on physiologic functioning during behavioral stress

The purpose of this study was to evaluate the influence of the normal menstrual cycle on lipoprotein, cardiovascular, and neuroendocrine stress responses. Fifteen normally-cycling, healthy women participated in a series of behavioral tasks during the menstrual, follicular, and luteal phases of their menstrual cycle. These women had established menstrual cycle regularity for the three months prior to enrollment in this study, were free from menstrual cycle disturbances, biochemically confirmed that they ovulated, and displayed appropriate patterns of reproductive hormone fluctuations during the study period. Heart rate, blood pressure, low density lipoprotein-cholesterol, and total cholesterol all demonstrated significant elevations from baseline levels during tasks. No differences in the magnitude of stress responses during the three menstrual cycle phases were noted for any physiological variable. We conclude that the hormonal fluctuations that occur in healthy, normally-cycling women during the menstrual cycle do not influence the stress responses that were investigated here. Significant influences of menstrual cycle phase previously reported in the literature, albeit not in a consistent direction, may have been due to the recruitment of women with menstrual cycle irregularities, and to the failure to adequately verify menstrual cycle phase.