Cinzia Lombardi

Headache and cardiovascular risk factors: positive association with hypertension.

The study analyzes the prevalence of cardiovascular risk factors in 1343 patients with severe headache (399 men and 944 women), aged 15 to 64 years; analyses were controlled for sex, age, and type and frequency of headache. Prevalence of various forms of headache was different between men and women. Age and days per year with headache were significantly different among various forms of headache. For men and women with headache, age directly related to prevalence of hypertension, hypercholesterolemia, and obesity. Due to low prevalence, analyses by age were not done for diabetes mellitus. For cigarette smoking, prevalence was not related to age in men, but was inversely related to age in women. With control for age, prevalence of cardiovascular risk factors was not significantly different among patients with different forms of headache, except for cluster headache. Among men with cluster headache, prevalence was high for cigarette smoking, but low for hypercholesterolemia. With control for age, days per year with headache did not relate to prevalence of cardiovascular risk factors except for cigarette smoking in men. Compared to data for a population sample used as control, patients with headache had higher prevalence of hypertension in both sexes, independent of age (odds ratio 1.51, 95% confidence interval 1.28 to 1.80); the difference between patients with headache and the control population was lower with increasing age. The high prevalence of hypertension among patients with headache was not due to overweight. The data indicate that headache is significantly associated with hypertension, but not with other cardiovascular risk factors.

Hydrogen sulphide-generating pathways in haemodialysis patients: a study on relevant metabolites and transcriptional regulation of genes encoding for key enzymes

BACKGROUND Hydrogen sulphide, H(2)S, is the third endogenous gas with putative cardiovascular properties, after nitric oxide and carbon monoxide. H(2)S is a vasorelaxant, while H(2)S deficiency is implicated in the pathogenesis of hypertension and atherosclerosis. Cystathionine beta-synthase (CBS), cystathionine gamma-lyase (CSE) and 3-mercaptopyruvate sulphurtransferase (MPS) catalyze H(2)S formation, with different relative efficiencies. Chronic kidney disease (CKD) is characterized by elevation of both plasma homocysteine and cysteine, which are substrates of these enzymes, and by a high prevalence of hypertension and cardiovascular mortality, particularly in the haemodialysis stage. It is possible that the H(2)S-generating pathways are altered as well in this patient population. METHODS Plasma H(2)S levels were measured with a common spectrophotometric method. This method detects various forms of H(2)S, protein-bound and non-protein-bound. Blood sulphaemoglobin, a marker of chronic exposure to H(2)S, was also measured, as well as related sulphur amino acids, vitamins and transcriptional levels of relevant genes, in haemodialysis patients and compared to healthy controls. RESULTS Applying the above-mentioned methodology, H(2)S levels were found to be decreased in patients. Sulphaemoglobin levels were significantly lower as well. Plasma homocysteine and cysteine were significantly higher; vitamin B(6), a cofactor in H(2)S biosynthesis, was not different. H(2)S correlated negatively with cysteine levels. CSE expression was significantly downregulated in haemodialysis patients. CONCLUSIONS Transcriptional deregulation of genes encoding for H(2)S-producing enzymes is present in uraemia. Although the specificity of the method employed for H(2)S detection is low, the finding that H(2)S is decreased is complemented by the lower sulphhaemoglobin levels. Potential implications of this study relate to the pathogenesis of the uraemic syndrome manifestations, such as hypertension and atherosclerosis.

Hyperhomocysteinemia in uremia--a red flag in a disrupted circuit.

Hyperhomocysteinemia is an independent cardiovascular risk factor, according to most observational studies and to studies using the Mendelian randomization approach, utilizing the common polymorphism C677T of methylene tetrahydrofolate reductase. In contrast, the most recent secondary preventive intervention studies, in the general population and in chronic kidney disease (CKD) and uremia, which are all negative (with the possible notable exception of stroke), point to other directions. However, all trials use folic acid in various dosages as a means to reduce homocysteine levels, with the addition of vitamins B6 and B12. It is possible that folic acid has negative effects, which offset the benefits; alternatively, homocysteine could be an innocent by‐stander, or a surrogate of the real culprit. The latter possibility leads us to the search for potential candidates. First, the accumulation of homocysteine in blood leads to an intracellular increase of S‐adenosylhomocysteine (AdoHcy), a powerful competitive methyltransferase inhibitor, which by itself is considered a predictor of cardiovascular events. DNA methyltransferases are among the principal targets of hyperhomocysteinemia, as studies in several cell culture and animal models, as well as in humans, show. In CKD and in uremia, hyperhomocysteinemia and high intracellular AdoHcy are present and are associated with abnormal allelic expression of genes regulated through methylation, such as imprinted genes, and pseudoautosomal genes, thus pointing to epigenetic dysregulation. These alterations are susceptible to reversal upon homocysteine‐lowering therapy obtained through folate administration. Second, it has to be kept in mind that homocysteine is mainly protein‐bound, and its effects could be linked therefore to protein homocysteinylation. In this respect, increased protein homocysteinylation has been found in uremia, leading to alterations in protein function.

Frequent de novo monoallelic expression of β-spectrin gene (SPTB) in children with hereditary spherocytosis and isolated spectrin deficiency

This report represents an attempt to define the rate of β‐spectrin de novo mutations affecting mRNA accumulation in patients with hereditary spherocytosis (HS). 19 HS children with haematologically normal parents and varying degrees of spectrin deficiency were studied. 13 of the 19 cases who were heterozygous at the genomic level for polymorphisms in the β‐spectrin coding region were further studied. However, in an analysis of reverse‐transcripted amplified cDNA from the regions of the polymorphisms, seven patients appeared to be homozygous, suggesting the occurrence of de novo mutational events affecting expression of one β‐spectrin allele. We conclude that in HS patients with isolated spectrin reduction and normal parents the apparently recessive pattern of inheritance may frequently be associated with de novo monoallelic expression of β‐spectrin.

Plasma Protein Aspartyl Damage Is Increased in Hemodialysis Patients: Studies on Causes and Consequences

Plasma proteins in hemodialysis patients display a significant increase in deamidated/isomerized Asx (asparagine and aspartic acid) content, a marker of protein fatigue damage. This has been linked to the toxic effects of hyperhomocysteinemia in uremic erythrocytes; however, treatment aimed at abating homocysteine levels did not lead to significant reductions in plasma protein damage. The hypothesis that lack of reduction in protein damage could be due to protein increased intrinsic instability, as result of interference with the uremic milieu rather than to hyperhomocysteinemia, was put forward. The deamidated/isomerized Asx content of normal plasma incubated with several uremic toxins for 24 h, 72 h, and 7 d was measured, identifying a group of toxins that were able to elicit this kind of damage. Uremic toxins were also incubated with purified human albumin, and dose-response experiments with the two most toxic agents in terms of protein damage (guanidine and guanidinopropionic acid) were carried out. The effect of the hemodialysis procedure on protein damage was evaluated. For investigating also the consequences of these alterations, human albumin was treated in vitro to produce an increase in deamidated/isomerized Asx residues, and the effects of albumin deamidation on protein binding were evaluated. Among the uremic toxins that are able to elicit protein damage, guanidine produced a dose-dependent increase in protein damage. No difference was found after a hemodialysis session. Deamidated albumin shows normal binding capacity to warfarin, salicylic acid, or diazepam but reduced binding to homocysteine. In conclusion, uremic toxins, especially guanidine, display an ability to induce significant protein damage, which can in turn have functional consequences.

Hyperhomocysteinemia and macromolecule modifications in uremic patients.

Abstract Hyperhomocysteinemia is present in the majority of well-nourished chronic renal failure and uremic patients. Most observations reported in the literature come from studies carried out in end-stage renal disease patients treated with hemodialysis. The underlying mechanisms of the toxic effects of homocysteine in uremia related to cardiovascular disease and other disturbances are still under scrutiny. As a consequence, macromolecules (i.e., proteins and DNA) have been found to be altered to various extents. One of the mechanisms of homocysteine toxicity is related to the action of its metabolic precursor, S-adenosylhomocysteine, a powerful methyltransferase competitive inhibitor. Disruption of DNA methylation has been demonstrated to occur as a result of hyperhomocysteinemia, and/or is associated with vascular damage. DNA hypomethylation has been found in the mononuclear cell fraction of uremic patients with hyperhomocysteinemia. Proteins are also targets of homocysteine-dependent molecular damage. The formation of oxidative products with free cysteinyl residue thiol groups has been demonstrated to occur in blood. The latter also represents a mechanism for the transport of homocysteine in plasma. In addition, homocysteine thiolactone has been shown to react with free amino groups in proteins to form isopeptide bonds, in particular at the lysine residue level. Another type of isopeptide bond in proteins may result from the deamidation and isomerization of asparaginyl residues, yielding abnormal isoaspartyl residues, which have been demonstrated to be increased in uremic patients. Folate treatment exerts a partial, but significant, homocysteine-lowering effect in uremic patients and has been shown to improve the changes in macromolecules induced by high homocysteine levels. In conclusion, both DNA and proteins are structurally modified in uremia as a consequence of high homocysteine levels. The role of these macromolecule changes in inducing the clinical complications of hyperhomocysteinemia in these patients, although still conjectural in some respects, is at present sustained by several pieces of evidence.

Homocysteinylated Albumin Promotes Increased Monocyte-Endothelial Cell Adhesion and Up-Regulation of MCP1, Hsp60 and ADAM17

Rationale The cardiovascular risk factor homocysteine is mainly bound to proteins in human plasma, and it has been hypothesized that homocysteinylated proteins are important mediators of the toxic effects of hyperhomocysteinemia. It has been recently demonstrated that homocysteinylated proteins are elevated in hemodialysis patients, a high cardiovascular risk population, and that homocysteinylated albumin shows altered properties. Objective Aim of this work was to investigate the effects of homocysteinylated albumin - the circulating form of this amino acid, utilized at the concentration present in uremia - on monocyte adhesion to a human endothelial cell culture monolayer and the relevant molecular changes induced at both cell levels. Methods and Results Treated endothelial cells showed a significant increase in monocyte adhesion. Endothelial cells showed after treatment a significant, specific and time-dependent increase in ICAM1 and VCAM1. Expression profiling and real time PCR, as well as protein analysis, showed an increase in the expression of genes encoding for chemokines/cytokines regulating the adhesion process and mediators of vascular remodeling (ADAM17, MCP1, and Hsp60). The mature form of ADAM17 was also increased as well as Tnf-α released in the cell medium. At monocyte level, treatment induced up-regulation of ICAM1, MCP1 and its receptor CCR2. Conclusions Treatment with homocysteinylated albumin specifically increases monocyte adhesion to endothelial cells through up-regulation of effectors involved in vascular remodeling.

Parallel-Group 8-Week Study on Chlorthalidone Effects in Hypertensives With Low Kidney Function

Short-term effects of chlorthalidone are unknown in low kidney function. The effects of 8-week treatment with 25-mg chlorthalidone on the top of ongoing treatment were compared between control hypertensives and low kidney function hypertensives as assessed by estimated glomerular filtration rate <60 mL/min×1.73 m2. Screening period consisted of 2 visits for patient selection and pretreatment laboratory evaluations (baseline). Inclusion criteria were uncontrolled hypertension on nondiuretic antihypertensive treatment. Exclusion criteria were chlorthalidone contraindications, refused consent, treatment with >3 antihypertensive drugs, severe hypertension, severe comorbidities, unreliable estimated glomerular filtration rate. Treatment period consisted of 5 visits (weeks 1, 2, 4, 6, and 8). Post-treatment laboratory evaluations were performed 3 to 4 days before week-8 visit. The 2 groups differed for baseline estimated glomerular filtration rate (low kidney function and control: n=60 and 60; mean, 39 and 76; range, 15–59 and 60–104) but not for sex, age, and baseline blood pressure. Week-8 blood pressure changes were a decrease in both groups (low kidney function and control: systolic pressure, −20 and −23; 95% confidence interval, −22/−18 and −26/−19; diastolic pressure, −9 and −10, −11/−7, and −13/−8) without significant between-group differences. Incidence of adverse events was similar in the 2 groups (15.0% and 16.7%). Baseline estimated glomerular filtration rate did not predict blood pressure changes and adverse events in either groups (P>0.6). In both groups, post-treatment changes were a decrease for estimated glomerular filtration rate and serum potassium, an increase for serum uric acid (P<0.01). Data show that short-term chlorthalidone effects were not reduced in hypertensives with low kidney function.

Relation of urinary urea to blood pressure: interaction with urinary sodium.

A previous study reported that urinary markers of protein intake are inversely related to blood pressure via unknown mechanisms. In man and rats, protein intake affects renal function and increases renal sodium excretion. The present study investigates the relation between markers of protein intake and blood pressure and the possible role of sodium in this relation. Blood pressure status, overnight urinary urea as index of protein intake, urinary and plasma sodium, and other variables were measured in a population sample of 3705 men and women, aged 25–74 years, without high plasma creatinine. Urinary urea was inversely related to blood pressure and hypertension: in multivariate analyses, 6.5 mmol/h higher urinary urea (about one s.d. in men and women) was related to 4.25 mm Hg lower systolic blood pressure (95% confidence interval = 1.34–8.49), and to 0.65 lower risk of hypertension (95% CI 0.34–0.87). An interaction was found between overnight urinary sodium and the relation of urinary urea to blood pressure: the relation was significant only in persons with overnight urinary sodium above the median. Urinary urea was significantly and inversely also related to plasma sodium. Data confirm an inverse relation to blood pressure of protein intake as measured by urinary urea. The possibility of sodium-related mechanisms is supported by the interaction of urinary sodium with the relation and by the inverse association of urinary urea with plasma sodium. The hypothesis is made that high protein intake could counteract sodium-dependent blood pressure rise via stimulation of renal sodium excretion.

A population-based approach for the definition of chronic kidney disease: the CKD Prognosis Consortium.

INTRODUCTION The Kidney Disease: Improving Global Outcomes (KDIGO) foundation promoted the establishment of the Chronic Kidney Disease (CKD) Prognosis Consortium to meta-analyze the association of estimated glomerular filtration rate (eGFR) and albuminuria with incidence of various outcomes in samples of general populations from all over the world. METHODS Variables in meta-analysis included eGFR by the Modification of Diet in Renal Disease (MDRD) Study equation, the urinary albumin to creatinine ratio (uACR) as index of albuminuria, together with proteinuria at dipstick urinalysis and classical markers of cardiovascular risk. Overall, 105,872 participants had uACR measurements, and 1,128,310 participants had dipstick measurements. RESULTS The association with mortality was continuous over the whole range of uACR/proteinuria and J-shaped for eGFR which was associated with an excess risk for values <75 and ≥120 ml/min per 1.73 m². Results were similar for the association of eGFR or uACR/proteinuria with renal failure. The associations of eGFR and uACR/proteinuria with death or renal failure were independent of each other. Findings were consistent across population samples from North America, Asia, Oceania and Europe, as well as in individuals with age <65 years and individuals with age ≥65 years. CONCLUSIONS Data support the threshold of 60 ml/min for CKD definition but suggest that eGFR in the range 60-74 ml/min could represent the early stages of CKD. This first set of results of the CKD Prognosis Consortium represents an important step in the evidence-based definition of CKD. Conclusions should be reevaluated with eGFR calculation by equations less biased for normal-high eGFR.