Increased synthesis rate of fibrinogen as a basis for its elevated plasma levels in obese female adolescents

Identification of the FGB gene polymorphism and analysis of its association with fat deposition traits in Hu sheep

As a crucial economic trait, fat deposition is directly related to carcass quality and feed efficiency in sheep. The purpose of this study was to investigate the polymorphisms of the FGB gene related to fat deposition and detect the expression features of the FGB gene in different adipose tissues of sheep by using Sanger sequencing, MassARRAY® SNP technique, and quantitative real-time PCR (qRT-PCR). Results showed that in the intron region of the FGB gene, a SNP g. 3378953 A > T has been identified, and significant association was found between perirenal fat weight, perirenal fat relative weight, mesenteric fat weight, and mesenteric fat relative weight (P < 0.05). Moreover, qRT-PCR analysis showed that FGB was expressed in all three adipose tissues, and FGB gene expression level in the AA genotype was significantly lower than that in the AT or TT genotypes (P < 0.05). Therefore, the FGB gene can be used as a candidate gene to reduce fat deposition in Hu sheep breeding, and the selection of the AA genotype in Hu sheep in production practice is more conducive to improving production efficiency.

Differential changes to splanchnic and peripheral protein metabolism during the diet-induced development of metabolic syndrome in rats

Little is known about the effects of the development of metabolic syndrome (MS) on protein and amino acid (AA) metabolism. During this study, we took advantage of the variability in interindividual susceptibility to high fat diet-induced MS to study the relationships between MS, protein synthesis, and AA catabolism in multiple tissues in rats. After 4 mo of high-fat feeding, an MS score (Z_MS) was calculated as the average of the z-scores for individual MS components [weight, adiposities, homeostasis model for the assessment of insulin resistance (HOMA-IR), and triglycerides]. In the small intestine, liver, plasma, kidneys, heart, and muscles, tissue protein synthesis was measured by ²H₂O labeling, and we evaluated the proportion of tissue AA catabolism (relative to protein synthesis) and nutrient routing to nonindispensable AAs in tissue proteins using natural nitrogen and carbon isotopic distances between tissue proteins and nutrients (Δ¹⁵N and Δ¹³C), respectively. In the liver, protein mass and synthesis increased, whereas the proportion of AA catabolism decreased with Z_MS. By contrast, in muscles, we found no association between Z_MS and protein mass, protein synthesis (except for a weak positive association in the gastrocnemius muscle only), and proportion of AA catabolism. The development of MS was also associated with altered metabolic flexibility and fatty acid oxidation, as shown by less routing of dietary lipids to nonindispensable AA synthesis in liver and muscle. In conclusion, MS development is associated with a greater gain of both fat and protein masses, with higher protein anabolism that mainly occurs in the liver, whereas muscles probably develop anabolic resistance due to insulin resistance.

Serum levels of soluble urokinase plasminogen activator receptor as a new inflammatory marker in adolescent obesity

Background & objectives:

Obesity is known for low-grade inflammatory state with enhanced production of inflammatory mediators in children and adolescents. Soluble urokinase plasminogen activator receptor (suPAR) can be generated as a pro-inflammatory marker. This study was conducted to evaluate the role of suPAR, and its association with leptin, adiponectin, interleukin-6 (IL-6), high-sensitive C-reactive protein (hsCRP) and fibrinogen in adolescent obesity.

Methods:

A total of 98 participants, 55 obese individuals and 43 healthy controls, aged between 10 and 17 yr, were included in the study. Serum suPAR, IL-6, leptin and adiponectin were measured using ELISA method.

Results:

Serum suPAR, IL-6, fibrinogen, hsCRP and leptin levels in obese individuals were significantly higher than those of controls (P<0.05 & P<0.001). Serum adiponectin levels in obese individuals were significantly lower than those of controls (P<0.01).

Interpretation & conclusions:

Our findings showed that suPAR, IL-6, fibrinogen, hsCRP and leptin were significantly higher in the obese individuals than those of controls. suPAR may be a good novel biomarker for systemic subclinical inflammation and immune activation linked to adolescent obesity.

Obesity and the dysregulation of fatty acid metabolism: implications for healthy aging

The population of the world is aging. In 2010, an estimated 524 million people were aged 65 years or older representing eight percent of the global population. By 2050, this number is expected to nearly triple to approximately 1.5 billion, 16 percent of the world's population. Although people are living longer, the quality of their lives are often compromised due to ill-health. Areas covered: Of the conditions which compromise health as we age, obesity is at the forefront. Over half of the global older population were overweight or obese in 2010, significantly increasing the risk of a range of metabolic diseases. Although, it is well recognised excessive calorie intake is a fundamental driver of adipose tissue dysfunction, the relationship between obesity; intrinsic aging; and fat metabolism is less understood. In this review we discuss the intersection between obesity, aging and the factors which contribute to the dysregulation of whole-body fat metabolism. Expert commentary: Being obese disrupts an array of physiological systems and there is significant crosstalk among these. Moreover it is imperative to acknowledge the contribution intrinsic aging makes to the dysregulation of these systems and the onset of disease.

Role of serum fibrinogen levels in patients with rotator cuff tears

Although rotator cuff (RC) tendinopathy is a frequent pathology of the shoulder, the real understanding of its aetiopathogenesis is still unclear. Several studies showed that RC tendinopathy is more frequent in patients with hyperglycemia, diabetes, obesity, or metabolic syndrome. This paper aims to evaluate the serum concentration of fibrinogen in patients with RC tears. Metabolic disorders have been related to high concentration of serum fibrinogen and the activity of fibrinogen has been proven to be crucial in the development of microvascular damage. Thus, it may produce progression of RC degeneration by reducing the vascular supply of tendons. We report the results of a cross-sectional frequency-matched case-control study comparing the serum concentration of fibrinogen of patients with RC tears with that of a control group of patients without history of RC tears who underwent arthroscopic meniscectomy. We choose to enrol in the control group patients with pathology of the lower limb with a likely mechanic, not metabolic, cause, different from tendon pathology. We found no statistically significant differences in serum concentration of fibrinogen when comparing patients with RC tears and patients who underwent arthroscopic meniscectomy (P = 0.5). Further studies are necessary to clarify the role of fibrinogen in RC disease.

Metformin use in children with obesity and normal glucose tolerance--effects on cardiovascular markers and intrahepatic fat

OBJECTIVE

To determine if metformin improves markers of inflammation, thrombosis, and intrahepatic fat contents in children with uncomplicated obesity.

METHODS

Obese children with normal glucose tolerance but elevated highly sensitive C-reactive protein (hsCRP) and/or fibrinogen concentrations (>2 standard deviations) were randomized to structured diet/exercise or diet/exercise and metformin for 6 months. Blood samples, dual energy X-ray absorptiometry data, and liver magnetic resonance images were obtained.

RESULTS

Forty-two of 66 recruited children (7-18 years) completed 6 months. Weight loss was modest but more pronounced in the metformin group (-4.9 +/- 1.0 kg) than in the diet/exercise group (-1.7 +/- 1.1 kg, p<0.03), whereas hsCRP and fibrinogen decreased more in the diet/exercise pubertal group. Baseline intrahepatic fat was high but decreased only in the diet/exercise (not metformin) pubertal group.

CONCLUSIONS

Six months of metformin therapy improved weight loss and reduced abdominal adiposity, but did not enhance the beneficial effect of diet and exercise on markers related to inflammation, thrombosis, or hepatic fat in obese children with normal glucose tolerance.

Insulin resistance is associated with at least threefold increased risk for prothrombotic state in severely obese youngsters

Obesity in childhood increases the risk for early adult cardiovascular disease. However, the underlying mechanism is not fully known. The aims of this study were to measure levels of prothrombotic factors and examine their possible association with obesity and insulin resistance in obese children and adolescents. A total of 313 obese children and adolescents were recruited. In a cross-sectional design, we measured anthropometric parameters, plasminogen activator inhibitor-1-antigen (PAI-1-Ag), von Willebrand factor-antigen (vWF-Ag), fibrinogen (FB), lipids, fasting glucose, and insulin (FI) levels. Insulin resistance was estimated using the homeostasis model assessment for insulin resistance (HOMA-IR) index. Boys presented significantly higher PAI-1-Ag levels than girls (82.6 vs. 71.3 ng/ml, p = 0.01). Higher levels of PAI-1-Ag (96.8 vs. 69 ng/ml, p < 0.001), vWF-Ag (123.5 vs. 107.6%, p = 0.004) but not FB (353.1 vs. 337.6 mg/dl, p = 0.137) were found in insulin-resistant (IR) participants after adjusted for age, gender, and pubertal stage. IR patients were at 2.98 (CI: 1.084-8.193) and 4.86 (CI: 1.119-15.606) times greater risk for high PAI-1-Ag and vWF-Ag levels, respectively. All three prothrombotic factors were positively correlated with body mass index (BMI) and FI levels (p < 0.05), but only PAI-1-Ag and vWF-Ag were significantly correlated with HOMA-IR index (p ≤ 0.001). After adjustment for confounding factors, both BMI and HOMA-IR indices remained significantly associated with PAI-1-Ag (r₂ = 0.225, p < 0.001) and vWF-Ag levels (r₂ =0.077, p = 0.003).

CONCLUSION

This study shows that obesity in youngsters, when accompanied with insulin resistance, is associated with at least threefold increased risk for elevated levels of prothrombotic factors, contributing to the early development of atherothrombosis. This impaired prothrombotic state may partially explain the increased risk for developing cardiovascular disease later in adulthood.

Nontraditional risk factors and biomarkers for cardiovascular disease: mechanistic, research, and clinical considerations for youth: a scientific statement from the American Heart Association

The rapid increase in the prevalence and severity of obesity in children is likely to lower the age of onset and increase the incidence of cardiovascular disease worldwide. Understanding the pathophysiology and improving the clinical management of cardiovascular disease involve a knowledge of novel risk factors and biomarkers. The clinical and mechanistic roles of these novel biological factors during childhood are currently being investigated. The goals of this scientific statement are to present the existing knowledge and theoretical framework of nontraditional risk factors for cardiovascular disease as they relate to children and adolescents, to describe the relevance and weight of available experimental and clinical evidence and the therapeutic implications pertaining to nontraditional risk factors in the pediatric population, and to stimulate further research with a goal of developing valid and reliable approaches to identify and validate novel risk factors that will aid in the clinical evaluation and perhaps prediction of cardiovascular disease in the pediatric population. Although several biomarkers are promising, substantial research is required before nontraditional risk factors can be used to identify and reduce cardiovascular disease risk in children and adolescents.

Haemostatic alterations in overweight children: associations between metabolic syndrome, thrombin generation, and fibrinogen levels

BACKGROUND

The metabolic syndrome (MetS) is associated with central obesity and leads to increased morbidity and mortality due to cardiovascular disease (CVD). Since obesity is associated with a hypercoagulable state, it has been speculated that hypercoagulation is linking MetS to CVD.

METHODS

We prospectively examined 81 overweight children and 32 normal-weight children aged 10-16 years. We analyzed blood pressure, fasting lipids, glucose, insulin, fibrinogen, and thrombin generating test determining time to peak (TTPeak), peak, time preceding the thrombin burst (lag-time), and 'endogenous' thrombin potential (ETP).

RESULTS

Overweight children demonstrated significantly higher fibrinogen levels (p<0.001), shorter lag-time (p<0.001), and TTPeak (p=0.038) compared to normal-weight children. Furthermore, ETP (p<0.001) and peak (p<0.001) were significantly higher in overweight than in normal-weight children. Fibrinogen and all parameters of the clotting test correlated significantly (p always <0.05) to body mass index (BMI) but not significantly to insulin resistance index HOMA-IR or occurrence of MetS in multiple linear backward regression analyses adjusted for age and gender.

CONCLUSIONS

The increased fibrinogen levels and the changes in the thrombin generation test points towards a haemostatic alteration in overweight children. The parameters of the clotting test were related to the degree of overweight but not to insulin resistance or occurrence of MetS questioning a direct association between MetS and the coagulation system. Longitudinal studies are needed to confirm these findings.

Obesity without established comorbidities of the metabolic syndrome is associated with a proinflammatory and prothrombotic state, even before the onset of puberty in children

BACKGROUND

Metabolic syndrome (MS)-related comorbidities in obesity, such as hypertension, dyslipidemia, and glucose intolerance, are increasingly recognized in children, predisposing them to early cardiovascular disease.

OBJECTIVE

The objective of the study was to investigate whether markers of inflammation and prothrombosis are abnormal in obese children without established MS comorbidities across puberty, as compared with lean, age-matched controls.

SUBJECTS AND METHODS

Obese children (body mass index >95%) with normal fasting glucose, blood pressure, cholesterol and triglycerides were recruited; lean controls (body mass index 10-75%) had no first-degree relatives with MS. High-sensitivity C-reactive protein (hsCRP), IL-6, plasminogen activator inhibitor 1, and fibrinogen concentrations were measured. Body composition was assessed by waist circumference and dual-energy x-ray absorptiometry.

RESULTS

Of 623 children screened, 203 enrolled (106 males, 97 females), aged 7-18 yr, 115 obese, 88 lean (balanced for age and gender), 99 prepubertal, and 104 pubertal. Many screen failures were due to silent comorbidities. Obese subjects with insulin resistance but without MS comorbidities had about 10 times higher hsCRP concentrations than controls and higher fibrinogen, IL-6, and plasminogen activator inhibitor-1 (P < 0.01 all). Differences were significant, even in the prepubertal cohort. hsCRP and fibrinogen correlated with waist circumference (r = 0.73 and 0.40, respectively) and percent fat mass (r = 0.76 and 0.47) (P < 0.0001).

CONCLUSION

Childhood obesity per se is associated with a proinflammatory and prothrombotic state before other comorbidities of the MS are present and even before the onset of puberty. Whether biomarkers like hsCRP and fibrinogen are useful in assessing cardiovascular risk and whether these abnormalities are reversible with earlier therapeutic interventions in very young obese children requires further study.

Fibrinogen kinetics and protein turnover in obese non-diabetic males: effects of insulin

BACKGROUND

Although hyperfibrinogenemia and insulin resistance are common in obesity and diabetes mellitus, the impact of obesity per se on fibrinogen turnover and the insulin effects on fibrinogen and protein kinetics is unknown.

METHODS

We measured fibrinogen and albumin fractional (FSR) and absolute (ASR) synthesis rates, as well as protein turnover, in non-diabetic, obese and in control male subjects both before and following an euglycemic, euaminoacidemic, hyperinsulinemic clamp, using L-[(2)H(3)]-Leucine isotope infusion.

RESULTS

In the obese, basal fibrinogen concentrations was approximately 25% greater (p < 0.035), and fibrinogen pool approximately 45% greater (p < 0.005), than in controls. Both FSR and ASR of fibrinogen were similar to control values. With hyperinsulinemia, although fibrinogen FSR and ASR were not significantly modified with respect to baseline in either group, fibrinogen ASR resulted to be approximately 50% greater in the obese than in controls (p < 0.015). Hyperinsulinemia equally stimulated albumin synthesis and suppressed leucine appearance from endogenous proteolysis in both groups. Amino acid clearance was also similar. In the obese, the insulin-mediated glucose disposal was approximately 50% lower (p < 0.03) than in controls, and it was inversely correlated with fibrinogen ASR during the clamp in both groups (r = - 0.58).

CONCLUSIONS

In obese, non-diabetic males, post absorptive fibrinogen production is normal. Whole-body amino acid disposal, basal and insulin-responsive protein degradation, and albumin synthesis are also normal. However, the greater fibrinogen ASR in the obese with hyperinsulinemia, and the inverse relationship between insulin sensitivity and clamp fibrinogen production, suggest a role for hyperinsulinemia and/or insulin resistance on fibrinogen production in obesity.

Correlates of plasma fibrinogen (FG) levels in a random sample of community-dwelling elderly

The aim of this study was to evaluate the association between plasma FG levels and coexisting cardiovascular diseases (CVD) risk factors, comorbidities, functional status and cognitive function in a random sample of 270 (163 women and 107 men) community-dwelling elderly aged 65-79 years. The assessment included demographic and social variables, health status, nutritional state, physical and cognitive function. Physical activity was assessed by the Stanford Usual Activity Questionnaire. The average plasma FG level was lower in men 3.1+/-0.9 g/l (+/-SD) than in women 3.6+/-1.1g/l. In the whole group of elderly people, body mass index (BMI), percentage of body fat, calf circumference as well as total and low density cholesterol were positively correlated with FG levels, whereas the Stanford Moderate Index-negatively. Multifactor analysis of variance (ANOVA) revealed that female gender, calf circumference and the Stanford Moderate Index are the factors that independently predict FG levels. In conclusion, FG seems not to be related to functional status or cognitive function of older individuals. Nevertheless, our findings suggest that female gender, excess body fatness and low physical activity have an independent contribution to higher plasma FG levels in community-dwelling older subjects.

Diabetic nephropathy is associated with increased albumin and fibrinogen production in patients with type 2 diabetes

AIMS/HYPOTHESIS

Hyperfibrinogenaemia and albuminuria are cardiovascular risk factors, often coexisting in diabetic and non-diabetic people. Albuminuria in turn is associated with a compensatory albumin overproduction in non-diabetic patients. It is not known whether the presence of albuminuria in patients with type 2 diabetes mellitus is associated with greater albumin and fibrinogen production rates than in normoalbuminuric patients. SUBJECTS, MATERIALS, AND METHODS: Using leucine isotope methods, we measured fractional and absolute synthesis rates (FSR, ASR) of albumin and fibrinogen in post-absorptive type 2 diabetic patients with either normal (n=11) or increased (n=10) urinary albumin excretion.

RESULTS

In albuminuric patients, albumin FSR (16.2+/-1.5%/day) and ASR (20.5+/-1.9 g/day) were greater (p<0.02 and p<0.05, respectively) than in normoalbuminuric patients (FSR=11.5+/-1.1%/day; ASR=15.7+/-1.2 g/day). Fibrinogen FSR was similar between patients with normal and increased albumin excretion, but concentration, the circulating pool and ASR of fibrinogen were 40 to 50% greater (p<0.035) in patients with albuminuria. Albuminuria was positively correlated with albumin ASR, with fibrinogen concentration, the fibrinogen pool and ASR, whereas albumin synthesis was inversely correlated with calculated oncotic pressure.

CONCLUSIONS/INTERPRETATION

Synthesis of albumin and fibrinogen is upregulated in type 2 diabetic patients with increased urinary albumin excretion. Albuminuria is associated with enhanced fibrinogen and albumin synthesis.

Obesity-Related Cardiovascular Risk in Children and the Role of Lifestyle Changes

Overweight and obesity in children present significant public health concerns because of the link with numerous chronic health conditions, especially type 2 diabetes and cardiovascular disease. Perhaps obesity is only the visible pointer of other underlying risk factors for these disease conditions in childhood. Although an imbalance between energy consumed and expended appears to be the simplistic underlying problem for the increased prevalence of obesity, it is a complex condition, with various contributing factors, and may be considered the metabolic factory for various risk factors for cardiovascular disease, both modifiable and nonmodifiable. It has also been recognized that the risk factors emerge quite early in the clinical course of obesity. Physical activity-based lifestyle change appears to be the most variable component of energy expenditure and therefore has been the obvious choice and the target of behavioral interventions to modify body weight in children. This review focuses on the obesity-related nontraditional risk factors for cardiovascular disease in children and the role of lifestyle changes in modulating these risk factors.

Plasma fibrinogen levels and cardiovascular risk factors in Japanese schoolchildren

BACKGROUND

Plasma fibrinogen level has been recognized as an independent risk factor for atherosclerosis and its thrombotic complications in adults. The present study aimed to clarify the association between plasma fibrinogen levels and cardiovascular risk factors in Japanese children.

METHODS

A total of 294 schoolchildren (145 boys and 149 girls) aged 10-13 years in a town in Nagano Prefecture, Japan, were surveyed in 2000 for body mass index (BMI), plasma fibrinogen, serum C-reactive protein (CRP), serum total cholesterol, serum high-density lipoprotein (HDL) cholesterol, hemoglobin (Hb) A1c, and ratio of serum total cholesterol to serum HDL cholesterol (TCHR).

RESULTS

The mean value and standard deviation of plasma fibrinogen level among the schoolchildren was 226.0+/-39.7 mg/dL for boys and 245.3+/-40.9 mg/dL for girls; significantly higher for girls. Among plasma fibrinogen tertiles, serum CRP tended to increase with plasma fibrinogen in both boys and girls. An increasing trend was also found in serum total cholesterol in boys, and in TCHR, HbA1c and BMI in girls. Multiple linear regression analysis revealed significant associations of plasma fibrinogen with serum CRP and HbA1c in both sexes, with TCHR in boys, and with BMI in girls.

CONCLUSIONS

Plasma fibrinogen levels were associated with cardiovascular risk factors such as serum CRP, TCHR, HbA1c, and BMI in Japanese schoolchildren.

Albumin and fibrinogen synthesis and insulin effect in type 2 diabetic patients with normoalbuminuria

OBJECTIVE

Insulin stimulates albumin synthesis but inhibits that of fibrinogen in both type 1 diabetic and healthy subjects. In type 2 diabetes, fibrinogen production is increased both in the postabsorptive state and in response to hyperinsulinemia. No data exist on the rate of albumin synthesis and its response to insulin in type 2 diabetes.

RESEARCH DESIGN AND METHODS

We measured fractional synthesis rates (FSRs) and absolute synthesis rates (ASRs) of both albumin and fibrinogen in postabsorptive normoalbuminuric type 2 diabetic patients at their spontaneous glucose levels (study A), as well as albumin FSR and ASR before and after a hyperinsulinemic-euglycemic euaminoacidemic clamp (study B), using leucine isotope methods.

RESULTS

In postabsorptive type 2 diabetes (study A), albumin FSR (11.2 +/- 0.9%/day) and albumin ASR (15.4 +/- 1.2 g/day) were not different from control values (albumin FSR: 9.4 +/- 0.7%/day; albumin ASR: 13.8 +/- 1.2 g/day, P > 0.1 for both). In contrast, in the type 2 diabetic subjects, both fibrinogen FSR (24.9 +/- 2.1%/day) and ASR (2.4 +/- 0.2 g/day) were greater (P < 0.025 and P < 0.007, respectively) compared with the control subjects (FSR: 18.6 +/- 1.51%/day; ASR: 1.6 +/- 0.2 g/day). Worse metabolic control in the type 2 diabetic patients was associated with hyperfibrinogenemia and increased leucine rate of appearance, whereas neither the (increased) fibrinogen ASR nor the (normal) albumin production was affected. In study B, after hyperinsulinemia (raised to approximately 860 nmol/l), albumin FSR and ASR increased by approximately 25% versus basal (P < 0.04) and to the same extent in both type 2 diabetic and control subjects.

CONCLUSIONS

In normoalbuminuric type 2 diabetic patients, postabsorptive albumin synthesis and its response to insulin were normal, whereas fibrinogen synthesis was increased, irrespective of metabolic control. Furthermore, in normoalbuminuric type 2 diabetic patients, a normal insulin sensitivity with respect to albumin production but a selective hepatic dysregulation of fibrinogen metabolism were present.

New paradigms in neuroendocrinology: relationships between obesity, systemic inflammation and the neuroendocrine system

Obesity may be an independent risk factor for coronary artery disease and contribute to a chronic state of systemic inflammation leading to atherosclerosis and metabolic abnormalities, such as diabetes, insulin resistance, dyslipidemia and hypertension. Visceral fat, in fact, may act as an endocrine organ, synthesizing and releasing atherogenic inflammatory cytokines, whose circulating levels depend on the individual's nutritional state, and the extent and anatomical location of fat stores. Unsuspected viral infections might also be involved in enhancing autocrine/paracrine mechanisms of cytokine release from omental fat. Elevated levels of blood cytokines may interact with the neuroendocrine system, autonomic nerves and peripheral lymphatic organs. This may lead to local inflammatory reactions in many body compartments, in particular in the heart tissue, possibly affecting the process of circulatory recovery in obese subjects, and predisposing these patients to a greater risk of myocardial inflammatory disease than individuals with normal body mass index. Circulating levels of inflammatory cytokines might be considered to determine risk categories for development of cardiovascular complications in obese subjects. In addition, their reduction with pharmacological antagonists might prevent and/or control acute cardiovascular events and increase energy expenditure in obese patients, especially after surgical treatment, through reduction of cytokine inhibition of the hypothalamic-pituitary-thyroid axis.

Established and recently identified coronary heart disease risk factors in young people: the influence of physical activity and physical fitness

Epidemiological studies have identified several risk factors for coronary heart disease (CHD), many of which are present in young people. [For the purpose of this review, the phrase "young people" embraces both children and adolescents.] One such risk factor is hypertension. In adults, exercise is thought to have a positive effect on blood pressure levels; however, findings are inconclusive for young people. Despite its association with CHD, obesity is on the increase in Western society's young population; prevention and intervention during early years is needed. An active lifestyle is considered to have a beneficial effect on body fatness. Lipoprotein profiles are directly associated with CHD status. In adults, there is some evidence that physical activity and/or fitness have a favourable effect on lipoprotein levels. Although information regarding the younger population is more ambiguous, it tends to concur with these findings. High levels of lipoprotein(a), are considered an independent risk factor for CHD. Relatively little has been written on young people, although some studies have postulated a favourable relationship with physical activity. An inverse relationship between aerobic fitness and CHD has been confirmed in adults; an association is not as easily verified for young people. Physical activity is similarly deemed to have a beneficial effect on health status. A high-fat diet has been linked to CHD in adults, and evidence to date reports similar findings for young people. Smoking increases the risk of CHD and even moderate smoking during youth could have damaging long-term consequences. There is some evidence that smoking is related to physical activity and fitness levels in young people. In adults, high levels of homocyst(e)ine have been associated with CHD. As yet, little has been written on the relationship between physical activity or physical fitness and homocysteine status in young people. High levels of plasma fibrinogen have been linked to CHD. Several studies have explored the relationship between plasma fibrinogen and physical activity and/or fitness in adults, but findings are inconclusive; for young people, the ambiguity is even greater. C-reactive protein is a molecular marker for CHD but, to date, little attention has been given to this aspect, especially amongst young people. The link between high levels of plasminogen activator inhibitor-1 and CHD has been confirmed, although the essence of this relationship is not established. There is a paucity of data on the younger population and the relevance of collating such information is questionable. For the younger population, most research is limited to the established CHD risk factors and further investigations of recently identified CHD risk factors are needed.

Effects of fatty acids on hepatic amino acid catabolism and fibrinogen synthesis in young healthy volunteers

Increased synthesis rate of fibrinogen, an independent risk factor for cardiovascular disease, was recently reported in obese insulin-resistant female adolescents with chronic elevated nonesterified fatty acids (NEFA). It is unknown whether a short-term change of NEFA concentrations controls hepatic fibrinogen synthesis. Therefore, 10 healthy male volunteers (24.5 +/- 3.3 yr, body mass index 23.5 +/- 2.9 kg/m2) were investigated in random order under basal and elevated NEFA for 8 h. Leucine metabolism, the fractional synthesis rates (FSR) of plasma fibrinogen, and endogenous urea production rates were measured during primed, continuous infusion of [1-13C]leucine and [15N2]urea, respectively. Plasma alpha-[13C]ketoisocaproic acid and [15N2]urea enrichment values were measured with GC-MS. Plasma fibrinogen was isolated with the beta-alanine method, and fibrinogen-related [13C]leucine enrichment was analyzed by GC-CIRMS. Lipofundin infusion and subcutaneous heparin tripled NEFA and triglycerides in the tests. Plasma glucose, circulating insulin, human C-peptide, and plasma glucagon were not changed by the study procedure. Fibrinogen FSR were significantly lower in tests with NEFA elevation (18.44 +/- 4.67%) than in control tests (21.48 +/- 4.32%; P < 0.05). Plasma fibrinogen concentrations measured were not significantly different (NEFA test subjects: 1.85 +/- 0.33, controls: 1.97 +/- 0.54 g/l). Parameters of leucine metabolism, such as leucine rate of appearance, leucine oxidation, and nonoxidative leucine disposal, were not influenced by NEFA elevation, and endogenous urea production remained unchanged. NEFA contributes to short-term regulation of fibrinogen FSR in healthy volunteers under unchanged hormonal status, leucine metabolism, and overall amino acid catabolism. Its contribution might be of relevance at least after fat-rich meals, counteracting by reduction of FSR the blood viscosity increase implied by hyperlipidemia.

Impact of albumin synthesis rate and the acute phase response in the dual regulation of fibrinogen levels in hemodialysis patients

BACKGROUND

Fibrinogen is a risk factor for cardiovascular disease. It also is an acute phase protein (APP) and its plasma concentration increases with inflammation. Fibrinogen synthesis correlates with albumin synthesis in nephrotic patients and in patients with an expanded plasma volume even when serum albumin is normal and there is no inflammatory disease. The relationships among albumin synthesis, the acute phase response and plasma fibrinogen levels in hemodialysis patients are unknown.

METHODS

In 74 hemodialysis patients, albumin synthesis, plasma volume (PV) and acute phase proteins (APPs) C-reactive protein (CRP), alpha1 acid glycoprotein (alpha1 AG), ceruloplasmin (Cer), and interleukin 6 (IL-6) were measured in serum and fibrinogen in plasma, and the results analyzed by multiple regression analysis. CRP, IL-6, alpha1 AG, Cer and fibrinogen were measured monthly, which enabled us to determine whether changes in these APPs correlated with the levels of and variability in plasma fibrinogen over time using a longitudinal modeling approach. Length of follow-up for the 74 patients ranged from 3.25 to 67.5 months.

RESULTS

Baseline fibrinogen (548.6 +/- 106. 4 mg/dL) was significantly greater than levels reported for normal adults and correlated positively with albumin synthesis (P < 0.001), age (P < 0.001) and log CRP (P = 0.002) and negatively with PV (P < 0.001). Longitudinally, fibrinogen varied positively with long-lived APPs, Cer and alpha1 AG, as well as the short-lived APP, CRP.

CONCLUSION

Plasma fibrinogen concentration is high in HD patients and directly correlates with increased albumin synthesis rates and the serum levels of APPs. Fibrinogen levels also correlate negatively with PV. Fibrinogen levels vary over time in synchrony with levels of other long-lived APPs, supporting the hypothesis that fibrinogen is regulated in part as a component of the acute phase response and in part by factors that increase albumin synthesis.