Impact of Hemorheological and Endothelial Factors on Microcirculation

Previous studies showed that endothelial alterations caused by physical stress worsened the hemorheological parameters mainly in patients affected by ischemic vascular diseases: major vascular alterations have been found in patients with very high endothelial dysfunction indexes: these indexes are given by the various substances produced by the endothelium, but it is very difficult to have a value which clearly identifies the real state of the endothelial alteration. The function of the NO, an endogenous vasodilator whose synthesis is catalyzed by NOs, can be determined by the Citrulline/Arginine ratio, which represents the level of activity of the enzyme. A very good index of the endothelial dysfunction is asymmetric dimethylarginine (ADMA), a powerful endogenous inhibitor of NOs; in fact several studies have demonstrated a strong relationship between ischemic vascular disease and high levels of plasmatic ADMA. Our recent studies on heart failure and on ischemic cerebrovascular diseases evaluate endothelial dysfunctions and hemorheological parameters.

Fitz-Hugh-Curtis-syndrome mimicking acute cholecystitis: value of new ultrasound findings in the differential diagnosis

Fitz-Hugh-Curtis is a rare syndrome characterised by perihepatitis following pelvic inflammatory disease. We report the case of a patient with a right ovarian teratoma, abnormal liver tests and pain in the right abdomen and shoulder, initially attributed to an acalculous cholecystitis. Before gynaecological surgery, a repeat ultrasound scan found several small avascular peritoneal masses at the upper dome of the liver, not reported in the initial examination. This prompted laparoscopic exploration of the subdiaphragmatic space, and the final diagnosis of Fitz-Hugh-Curtis-syndrome was made. Such ultrasound finding appears to be a new diagnostic feature of this syndrome.

Sildenafil Prevents Endothelial Dysfunction Induced by Ischemia and Reperfusion via Opening of Adenosine Triphosphate–Sensitive Potassium Channels

Background— Animal studies have demonstrated that administration of sildenafil can limit myocardial damage induced by prolonged ischemia, an effect that appears to be mediated by opening of adenosine triphosphate–sensitive potassium (K ATP ) channels. No study has investigated whether sildenafil can also prevent the impairment in endothelium-dependent vasodilatation induced by ischemia-reperfusion (IR) in humans.

Methods and Results— In a double-blind, placebo-controlled, crossover design, 10 healthy male volunteers (25 to 45 years old) were randomized to oral sildenafil (50 mg) or placebo. Two hours later, endothelium-dependent, flow-mediated dilatation (FMD) of the radial artery was measured before and after IR (15 minutes of ischemia at the level of the brachial artery followed by 15 minutes of reperfusion). Seven days later, subjects received the other treatment (ie, placebo or sildenafil) and underwent the same protocol. Pre-IR radial artery diameter and FMD, as well as baseline radial artery diameter after IR, were similar between visits ( P =NS). After placebo administration, IR significantly blunted FMD (before IR: 7.9±1.1%; after IR: 1.2±0.7%, P <0.01). Importantly, sildenafil limited this impairment in endothelium-dependent vasodilatation (before IR: 7.0±0.9%; after IR: 6.2±1.1%, P =NS; P <0.01 compared with placebo). In a separate protocol, this protective effect was completely prevented by previous administration of the sulfonylurea glibenclamide (glyburide, 5 mg), a blocker of K ATP channels (n=7; FMD before IR: 10.3±1.5%; after IR: 1.3±1.4%, P <0.05).

Conclusions— In humans, oral sildenafil induces potent protection against IR-induced endothelial dysfunction through opening of K ATP channels. Further studies are needed to test the potential clinical implications of this finding.

Diffusion MRI shows increased water apparent diffusion coefficient in the brains of cirrhotics

BACKGROUND

Brain edema and increased intracranial pressure worsen prognosis in patients with end-stage chronic cirrhosis.

OBJECTIVE

To use diffusion-weighted imaging (DWI) to quantify water apparent diffusion coefficient (ADC) in different brain regions of patients with chronic liver failure with or without hepatic encephalopathy.

METHODS

The authors studied 14 patients with viral liver cirrhosis and 12 sex- and age-matched healthy volunteers. Seven patients had no clinical evidence of hepatic encephalopathy; six had grade I hepatic encephalopathy; and one had grade II hepatic encephalopathy. Brain DWI was obtained using a single-shot echo-planar imaging sequence, and four gradient strengths (b values = 0, 300, 600, and 900 s/mm(2)) were applied to calculate the average diffusivity maps.

RESULTS

Mean ADC values in the brains of patients with cirrhosis were significantly increased in all selected regions of interest (caudate, putamen, and pallidus nuclei; occipital, parietal, and frontal lobe white matter) except in the thalamus. Venous ammonia was linearly related to ADC values in deep gray and white matter regions of interest.

CONCLUSIONS

Brain water apparent diffusion coefficient is increased in patients with chronic liver disease and may be useful in monitoring patients with hepatic encephalopathy.

[Can the treatment with L-carnitine improve the inflammation in chronic hemodialysis patients?]

PURPOSE

Inflammation in patients on chronic hemodialysis (HD) is related to malnutrition and atherosclerosis; anemia is also often present in these patients. It has been demonstrated that l-carnitina treatment, in addition to reducing the need for erythropoietin (EPO), improves nutritional parameters and cardiac performance.

METHODS

To evaluate the effect of l-carnitine on the inflammatory pathology in patients on chronic HD, we studied 11 patients with no sure signs of malnutrition, flogistic and infective pathologies and with C-reactive protein (CRP) <2 mg/dL. We evaluated at baseline, after 6 and 12 months CRP, serum albumin, hemoglobin (Hb),nPCR and EPO weekly requirement.

RESULTS

We observed a reduction in CRP (from 0.88 +/- 0.65 to 0.42 +/- 0.17 mg/dL after 6 months and to 0.50 + 0.36 mg/dL after 12 months), an increase in serum albumin (from 10.9 +/- 1.23 to 2.08 +/- 1.88 and to 11.8 +/- 1.15 g/dL) and an increase in nPCR (from 0.96 +/- 0.09 to 1.15 +/- 0.2 and to 1.16 +/- 0.18 g/kg/die); EPO weekly requirement decreased (from 7363 +/- 2941 to 5909 +/- 3207 units after 6 months and to 5363 +/- 3139 units after 12 months).

CONCLUSION

These results seem to underline a positive effect of l-carnitine on the inflammatory pathology of patients on chronic hemodialytic treatment.

Different haemodynamic effects of a single dose of long-acting isosorbide-5-mononitrate in healthy subjects and patients with cirrhotic portal hypertension

BACKGROUND

The action pathways of nitrates are hypothesised to be deranged in cirrhosis.

AIM

In order to confirm it, the acute haemodynamic effects of isosorbide-5-mononitrate in cirrhotic patients and controls was investigated.

PATIENT

Nine cirrhotics and nine healthy controls.

METHODS

Evaluation in the fasting state, 90 min after isosorbide-5-mononitrate or placebo (double-blind on two different days) and then 30 and 120 min after eating a standard meal. Various systemic and splanchnic haemodynamic parameters, including arterial impedance, assessed as Doppler pulsatility index, were measured.

RESULTS

isosorbide-5-mononitrate reduced arterial pressure and increased heart rate and mesenteric pulsatility index both in controls and in cirrhotics, whereas the following parameters behaved differently in the two groups (P < 0.05): hepatic pulsatility index decreased (-9%) and the portal velocity increased (+13%) in controls, whereas hepatic pulsatility increased (+18%) and portal velocity decreased (-18%) in cirrhotics. The two groups presented a similar pattern of changes in most variables under placebo after a meal. In controls, the administration of isosorbide-5-mononitrate blunted the postprandial mesenteric vasodilation and related changes in splanchnic and systemic circulation, expected at 30 min, in comparison to those observed under placebo. In cirrhotics, instead, the postprandial pattern was similar under placebo and isosorbide-5-mononitrate.

CONCLUSIONS

The acute administration of isosorbide-5-mononitrate produces different haemodynamic effects in healthy and diseased livers, both in the fasting state and after a meal, consistent with the hypothesis of a deranged response of the intrahepatic microcirculation to nitrates in cirrhosis.

Increased prevalence of fatty liver in arterial hypertensive patients with normal liver enzymes: role of insulin resistance

BACKGROUND

The conditions associated with fatty liver disease presenting with normal liver enzymes and the mechanism involved in its development remain to be fully elucidated.

AIMS

The aim of the present study was to test the hypothesis that fatty liver with normal liver enzymes occurs more frequently in arterial hypertensive patients and to establish whether this condition is associated with insulin resistance.

PATIENTS

A total of 55 non-obese, non-diabetic, non-heavy alcohol drinking patients with arterial hypertensive and normal liver enzymes and 55 sex and age matched healthy subjects were enrolled into the study.

METHODS

Plasma metabolic parameters, body mass index, and the presence of fatty liver were investigated. Insulin resistance was estimated from plasma insulin and glucose as the homeostasis model assessment index. Stepwise logistic regression and multivariate regression analysis were used on the combined sample to identify variables independently associated with fatty liver and insulin resistance.

RESULTS

Hypertensive patients had a significantly higher prevalence of fatty liver (30.9% v 12.7%; p<0.041), higher insulin resistance (mean 2.27 (SD 1.81) v 1.56 (0.70); p = 0.022), and slightly higher body mass index (24.9 (3.0) v 24.0 (2.2); p = 0.043) than controls. Multivariate logistic regression identified insulin resistance (odds ratio 1.66 (95% confidence interval (CI) 1.03-2.52)) and body mass index (OR 1.22 (95% CI 1.00-1.49)) as factors independently associated with fatty liver. Multivariate regression analysis showed insulin resistance to be predicted by alanine transaminase (p = 0.002), presence of arterial hypertension (p = 0.029), and body mass index (p = 0.048).

CONCLUSION

The higher prevalence of non-alcoholic fatty liver in non-obese hypertensive patients with normal liver enzymes appears to be related to increases in insulin resistance and body weight.

Endothelium and hemorheology

Hemorheological alterations which can be found in ischaemic vascular diseases are well known and widely studied; less clear is the relationship between these alterations and endothelial function. Our studies showed that modifications in endothelial function caused by physical stress are associated with a worsening in hemorheological parameters mainly in patients affected by ischaemic vascular diseases: major vascular alterations have been found in patients with very high levels of plasma markers endothelial dysfunction. The control of the basal tone of the vessels is given by the complex interaction between vasoconstrictor and vasodilator endothelial factors and when this equilibrium is broken we have the endothelial dysfunction. From a methodological point of view we can find an endothelial dysfunction index determining the various substances produced by the endothelium, but it is very difficult to have a value which clearly identifies the real state of the endothelial alteration. The function of the NO, which is one of the more powerful endogenous vasodilators and whose synthesis is catalysed by nitric oxide synthase (NOS), can be determined by the ratio between blood concentrations of citrulline and arginine (the co-product and the precursor of the way of NO synthesis), which represents the level of activity of the enzyme. A very affordable index of the endothelial dysfunction is the asymmetric dimethylarginine (ADMA), a powerful endogenous inhibitor of NOS; in fact several studies demonstrated a strong relationship between ischaemic vascular diseases and high levels of plasma ADMA. Evaluation of these parameters is measured by means of high performance liquid chromatography (HPLC): this technique provides very affordable results and allows to obtain evaluations of substances in very small concentrations, like ADMA.

[Fluticasone propionate in the treatment of airway inflammations (asthma and rhinitis)]

Inflammation is the pathogenetic basis of many airway diseases like asthma and rhinitis. This provides the rationale for a therapy with antiinflammatory drugs like inhaled corticosteroids (ICS), which are able to suppress the underlying pathologic processes, ensuring an effective control of the disease and improving patients's quality of life. Within ICS, fluticasone is endowed of a potent antiinflammatory activity, due to its high affinity for the the glucocorticoid receptor (allowing the use of 50% of the dose of other ICS) and of a negligible oral bioavailability (<1%), indicating a low potential for systemic exposure. Due to its high therapeutical index, fluticasone can be used in the management of severe asthma or other airway diseases at doses devoid of relevant unwanted systemic effects. Scientific literature has broadly demonstrated its efficacy and safety, even at high doses and in the long term use.

Fluidodynamic evaluation of arteriovenous fistulae for hemodialysis

Arteriovenous fistulae (AVF) are commonly used in dialysis treatment of uremic patients. However, many AVF create problems and have to be re-examined. Problems arise in the cannulation site and must be treated with antibiotics, and stenosis, both in the arterial and in the venous side of the AVF. In the worst case, the AVF must be replaced for treatment to continue. However, this can only be repeated once before the AVF site is no longer viable. This increases the discomfort, the morbidity and the mortality of the dialysis patient. Several kinds of AVF were studied to determine whether flow disturbances give rise to these complications. Many studies have already demonstrated the importance of hemodynamic factors in vascular disease pathogenesis. These factors include: the pulsatility of flow, the elasticity of the vessel, the non-Newtonian blood, flow behavior and, very importantly for AVF, the vessel geometry. In model studies, intimal changes have been observed in bends and bifurcations, regions of vessel construction and vessel stenosis. In these regions, blood flow changes abruptly and this contributes to arterial disease. We prepared several one-to-one, true-to-scale elastic silicon rubber models of different AVF. The AVF models were based on angiographic studies of chronic dialysis patients and on AVF from the arms of cadavers. The models had a similar compliance to that of the human blood vessel. Flow was visualized using photoelasticity apparatus and a birefringent blood-like fluid. This method is suitable to analyze the spatial configuration of flow profiles, to differentiate laminar flow from disturbed flow, and to visualize flow separation, vortex formation and secondary flow. It was found that AVF create disturbances that are not found under normal physiological flow conditions. The X-formed AVF was very unsatisfactory, creating significant flow disturbances. The AVF had high velocity fluctuations. These could lead, for example, to aneurysm formation. A better configuration would be an end-to-end AVF. However, this formation creates other complications. For example, there is not enough blood to the hand and parts of the hand lose feeling. The recommended AVF would be an end-to-side anastomosis. In this case, attention is needed for placement geometry, to minimize additional flow disturbances. Several models as well as patient angiographic studies are discussed.

Artificial kidney: status of the art and new perspectives

Extracorporeal dialysis was first performed in 1943 and has become a routine for End Stage Renal Patients from the early sixties. In the last 30 years researchers have focused on biocompatibility of artificial materials and optimisation of removal of uremic toxins by the membrane as in the long term treatment many complications like amylodosis heart and bone lesions, accelerated amyloidosis and immune system failure can occur. From this point of view high flux dialytic membranes are currently considered more biocompatible therefore being able to prevent such diseases.

Inflammatory response of a new synthetic dialyzer membrane. A randomised cross-over comparison between polysulfone and helixone

Hemodialysis patients suffer from chronic inflammation due to intradialytic contact of blood with artificial materials. The FX 60 dialyzer which belongs to the new FX-class series of dialyzers is composed of the new membrane Helixone. This membrane is derived from the original Fresenius Polysulfone membrane. The FX-class design is based on modified geometry of fibres and housing and has resulted in a new dialyzer with improved efficiency, safety and ease of handling compared to the F series (F 60S) dialyzer. The aim of the study was to investigate whether the biocompatibility pattern in terms of inflammatory parameters of the new type of polysulfone dialyzer has changed compared to the standard. A clinical in vivo study was conducted to compare the intradialytic inflammatory response of the two dialyzers, FX 60 and F 60S. Eight chronic dialysis patients were selected for the study: mean age 65.5 +/- 15.5 years, mean time on dialysis 100 +/- 95 months. The randomized cross-over study involved a treatment period of 2 weeks (total 6 sessions), one week with each dialyzer, starting with one or the other according to the randomization scheme. Blood samples were taken at 0 (T0), 15, 60, and 240 minutes to evaluate white blood cell (WBC) count, complement factor C5a, leukocyte elastase, soluble intercellular adhesion molecule 1 (sICAM-1), platelet count, C-reactive protein (CRP). At 15 min, WBC count showed a comparably, low decrease for both dialyzers: -7.6% for FX 60 versus -6.6% for F 60S, p=not significant (ns). At the same time the C5a concentration decreased from 15.0 +/- 7.5 ng/ml to 13.5 +/- 6.7 ng/ml (p=ns) for FX 60, and from 15.1 +/- 12.5 ng/ml to 14.9 +/- 25.0 ng/ml for F 60S (p=ns). The elastase concentration progressively increased over time with no statistical difference between the two dialyzers. The levels of sICAM-1, CRP, and platelet count were similar at each time point for both dialyzers, varying around the baseline values (p=ns). No significant difference emerged in terms of inflammatory response between the two dialyzers, hemo demonstrating that the biocompatibility of the F-series was maintained in the FX-class series of dialyzers and is independent of design factors.

[Alkylphenols: assessment of risks for aquatic ecosystems and for human health with particular reference to endocrine effects]

(Alkylphenols: evaluation of the risk to aquatic ecosystems and human health with reference to endocrine effects).--Endocrine disrupting chemicals (EDC) are a heterogeneous group of substances that can interfere with many endocrine functions. Their effects have been demonstrated in different taxa and they are suspected to affect human health. Alkylphenols are an important group of EDC. They are formed from the degradation of alkylphenol polyethoxylates in the environment or in the sewage treatment plants. They are generally characterized by a high bioconcentration factor (BCF) and accumulate both in sediments and aquatic species. Alkylphenols (APE) show estrogenic activity: studies on fish and rodents put into evidence on both reproductive and developmental effects. In a recent study, the levels of APE detected in seafood from the Adriatic Sea showed a no negligible human health risk for strong fish consumers.

Platelet activation and PDGF-AB release during dialysis

During hemodialysis the blood-membrane contact causes a release of platelet granule content, which contains Platelet Derived Growth Factor (PDGF-AB). In view of its possible role in accelerated atherosclerotic processes, we evaluated the intra- and post-dialytic changes in PDGF-AB serum levels during hemodialysis sessions performed with Hemophan and Polysulfone membranes. PDGF-AB, PF4, betaTG and MPV levels were determined in the peripheral blood in 30 patients each of whom underwent 6 dialysis sessions: 3 with Hemophan (HE) membrane and 3 with Polysulfone (PS) membrane, interpolated by a wash out session with PS membrane. Blood samples were taken at times 0', 30', 120', 180', 240' during dialysis sessions and at 1, 4 and 20 hours after the end of the session. Statistical analysis was done using the ANOVA one way test and Student's t test PDGF-AB serum levels initially increased and, except for a sharp fall at 120', remained constantly high during HD with both membranes tested, not returning to basal values until 20 hours after the end of the session. PF4, betaTG and MPV all showed a similar trend to PDGF. No statistically significant difference was found between the two membranes tested. PDGF-AB, a powerful growth factor in cells of mesenchymal origin, is released during dialysis mainly as a result of the blood-membrane contact. This we found regardless of the type of dialyzer we tested, and, above all, proved to return very slowly to basal values. We speculate that the release of PDGF-AB could play a part like other atherosclerosis risk-factors in the appearance and worsening of atherosclerotic lesions in hemodialysis patients.

Abnormal brain energy metabolism shown by in vivo phosphorus magnetic resonance spectroscopy in patients with chronic liver disease

We used phosphorus magnetic resonance spectroscopy (31P-MRS) to assess in vivo the brain bioenergetics of 28 patients with liver cirrhosis. Seven had clinical hepatic encephalopathy (HE), nine hepatocellular carcinoma. 31P-MRS was performed by the DRESS localisation technique on occipital lobes. Brain phosphocreatine was significantly reduced in patients with or without overt HE, and inorganic phosphate was increased in both groups of patients. The cytosolic phosphorylation potential (PP), the relative rate of oxidative metabolism and the regulatory [ADP] were all abnormal. Brain PP was inversely correlated with serum ammonia concentration only in patients without liver cancer. The degree of bioenergetic failure was significantly higher in the presence of overt encephalopathy. We conclude that patients with liver cirrhosis had a derangement of brain energy metabolism, and that 31P-MRS offers a non-invasive method for investigating the underlying mechanisms of HE, with relevant implications in the identification and management of this condition.

Influence of the spleen on portal haemodynamics: a non-invasive study with Doppler ultrasound in chronic liver disease and haematological disorders

BACKGROUND

Splanchnic haemodynamic parameters for the differential diagnosis of splenomegalies of different origins are still suboptimal and the role of spleen enlargement in cirrhosis remains controversial. In an attempt to elucidate these questions, we assessed splanchnic haemodynamics in chronic liver diseases and various other disorders with splenomegaly.

METHODS

Study groups comprised: (i) patients with chronic liver disease (89 with cirrhosis, 35 with chronic hepatitis), (ii) patients with splenomegaly without relevant portal hypertension (14 with haematological splenomegaly and 25 liver transplant recipients without complications), (iii) 15 patients with arterial hypertension, (iv) 22 healthy controls. In all subjects, spleen size, portal flow parameters and splenic artery resistance index were measured using duplex-Doppler ultrasound.

RESULTS

Splenic artery resistance index was significantly and selectively increased in patients with cirrhosis (0.63, whereas all other group means ranged between 0.53 and 0.56; P < 0.01). Portal flow velocity was significantly decreased in cirrhosis (P < 0.01). The combination of these two parameters provided an accuracy of 87.5% in distinguishing portal hypertensive from haematological splenomegaly. In patients with cirrhosis, the degree of spleen enlargement was positively correlated with increasing portal flow volume, portal vein diameter and variceal size, whereas splenic resistance index and portal velocity did not differ in connection with spleen size.

CONCLUSIONS

Splenoportal Doppler sonography provides specific findings in cirrhosis and may therefore be a useful tool in differentiating between splenomegaly of portal hypertensive or haematological origin. In patients with cirrhosis, the presence of splenomegaly is associated with the presence of larger oesophageal varices.

[Current treatment of choroidal neovascularization in age-related macular degeneration]

Age-related macular degeneration (AMD) is currently the leading cause of severe visual acuity loss in people over the age of 50 in the Western world. Most of the visual loss is due to choroidal neovascularization (CNV). Laser photocoagulation is the only proven treatment for selected cases of AMD; however, it can only be used with less than 20% of patients at the time of diagnosis. Among experimental therapies currently being tested, photodynamic therapy has recently proven its efficacy in randomized multicenter studies for predominantly classic subfoveal pure occult type CNVs.