Nitric oxide metabolites in decompensated liver cirrhosis

Methemoglobinemia Caused by Portable Dialysis in the Critically Ill

OBJECTIVE

To evaluate the root cause of a series of methemoglobinemia cases in a medical ICU.

RESULTS

We report a sentinel case of methemoglobinemia that was associated with dialysis sessions using a portable dialysis unit in our hospital. This led to the identification of four additional patients who developed methemoglobinemia while undergoing portable dialysis. We determined that these episodes were caused by inadequate clearance of chloramine from the tap water used for portable dialysis. Introduction of larger capacity carbon filters into the portable dialysis systems resulted in no further cases of methemoglobinemia at our institution.

CONCLUSIONS

Clinicians should be aware of municipal tap water as a potential cause of methemoglobinemia and monitor for excessive levels of oxidants in dialysis water sources. The capacity of the hemodialysis equipment to clear chloramine can vary as a function of external factors. Using a reliable test method to identify chloramines in the water prior to entering the hemodialysis equipment is essential.

Circulating nitric oxide products do not solely reflect nitric oxide release in cirrhosis and portal hypertension

BACKGROUND

Patients with cirrhosis often develop a systemic vasodilatation and a hyperdynamic circulation with activation of vasoconstrictor systems such as the renin-angiotensin-aldosterone system (RAAS), and vasopressin. Increased nitric oxide (NO) synthesis has been implicated in the development of this state of vasodilation and pulmonary dysfunction including increased exhaled NO concentrations. Circulating metabolites (NO(x)) may affect the systemic and pulmonary NO-generation. However, the relations of these abnormalities to the haemodynamic changes remain unclear.

AIMS

The aims of the present study were to measure changes in exhaled NO in relation to circulating NO(x), RAAS, and haemodynamics.

METHODS

Twenty patients (eight child class A and 12 class B patients) underwent a liver vein catheterization with determination of splanchnic and systemic haemodynamics. Circulating NO(x) and exhaled NO were determined in the supine and sitting positions and related to haemodynamics, RAAS and lung diffusing capacity (D(L)CO). Eight matched healthy individuals served as controls.

RESULTS

All patients with cirrhosis had portal hypertension. We found no significant difference in exhaled NO between patients and controls and no changes from the supine to the sitting position. Exhaled NO in the patients correlated significantly with plasma volume, heart rate and D(L)CO. NO(x) concentrations were not significantly increased in the patients. NO(x) correlated with portal pressure and haemodynamic indicators of vasodilatation, but not with exhaled NO concentrations.

CONCLUSION

In patients with moderate cirrhosis, exhaled NO is normal. Circulating NO(x) do not seem to reflect pulmonary and systemic NO release, but NO(x) seems to reflect systemic and splanchnic haemodynamic changes in cirrhosis.

Nitric oxide levels in chronic liver disease patients with and without oesophageal varices

Introduction Patients with chronic liver disease ultimately progress to develop cirrhosis and portal hypertension. Recently it seems well established that nitric oxide disturbances play a key role in the pathogenesis of chronic liver disease and portal hypertension. The aim of this work was to clarify the correlation between chronic liver disease stages, liver function status, esophageal varices presence and nitric oxide disturbances. Subjects and methods All subjects (n = 120) in the present study were classified into; group I which included 15 age and sex matched healthy volunteers (taken as control), group II which included 20 patients with chronic active hepatitis, and group III which included 85 patients with hepatic cirrhosis. All subjects included were subjected to full clinical assessment, routine laboratory investigations, serum nitrate level determination using colorimetric method, abdominal ultrasonography and upper endoscopy. Results Increased serum nitrate level could not be detected in patients with chronic active hepatitis as well as those with early cirrhosis (Child’s class A). Progressive and significant increase of serum nitrate levels were detected in more advanced stages of cirrhosis (Child’s class B & C). The best non-invasive predictor for the presence of oesophageal varices was a combination of platelet count <150.000/mm³, splenomegaly >18 cm, Child’s class B or C and serum nitrate ≥38 μmol/l, with 93.3% sensitivity and 100% specificity. Conclusion Serum nitrate level can be used as a non-invasive predictor for progression of chronic liver disease as well as for the presence of oesophageal varices.

Serum levels of soluble Fas, nitric oxide and cytokines in acute decompensated cirrhotic patients

AIM: To evaluate plasma levels of nitrite/nitrate (NOx), soluble Fas (sFas) antigen, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in patients with compensated and acute decompensated cirrhosis and to evaluate mediators causing acute decompensation in liver cirrhosis.

METHODS: This prospective study was conducted in the medical intensive care unit of an academic tertiary center. Fifty-five patients with acute decompensation (gastrointestinal hemorrhage, encephalopathy, hydropic decompensation) and twenty-five patients with compensated liver cirrhosis were included. Blood samples were taken for analyses of sFas, Nox, IL-6, TNF-α. Liver enzymes and kidney functions were also tested.

RESULTS: In patients with acute decompensation, plasma sFas levels were higher than in non-decompensated patients (15 305 ± 4646 vs 12 458 ± 4322 pg/mL, P < 0.05). This was also true for the subgroup of patients with alcoholic liver cirrhosis (P < 0.05). The other mediators were not different and none of the parameters predicted survival, except for ALT (alanine-aminotransferase). In patients with portal-hypertension-induced acute hemorrhage, NOx levels were significantly lower than in patients with other forms of decompensation (70.8 ± 48.3 vs 112.9 ± 74.9 pg/mL, P < 0.05). When NOx levels were normalized to creatinine levels, the difference disappeared. IL-6, TNF-α and sFas were not different between bleeders and non-bleeders. In decompensated patients sFas, IL-6 and NOx levels correlated positively with creatinine levels, while IL-6 levels were dependent on Child class.

CONCLUSION: In acute decompensated cirrhotic patients sFas is increased, suggesting a role of apoptosis in this process and patients with acute bleeding have lower NOx levels. However, in this acute complex clinical situation, kidney function seems to have a predominant influence on mediator levels.

Conservation of whole body nitric oxide metabolism in human alcoholic liver disease: implications for nitric oxide production

OBJECTIVE

Patients with advanced liver diseases tend to develop a hyperdynamic circulation which complicates cirrhosis. Impairment of nitric oxide (NO) metabolism has been implicated in the pathogenesis of portal hypertension. The aim of this study was to determine nitric oxide synthase (NOS)-dependent whole body NO production in patients with decompensated liver cirrhosis and portal hypertension.

MATERIAL AND METHODS

Ten patients with decompensated alcoholic liver disease and portal hypertension (Child-Pugh Classifications B and C with no signs of infection) and 10 age- and gender-matched control subjects received an intravenous infusion of L-[15N]2-arginine (50 micromol/min for 30 min). Urine and serum nitrite and nitrate concentrations were determined using ion chromatography-mass spectrometry.

RESULTS

NOS-dependent whole body NO synthesis was estimated by the conversion of [15N]guanidino nitrogen of arginine to urine 15N-nitrite and 15N-nitrate. The amount of 15N-nitrite and 15N-nitrate in the urine of patients and control subjects was significantly correlated with the amount of urine nitrite and nitrate over 36 h (r=0.91 and 0.77, respectively, p<0.0001). However, neither a median of 12 h 15N-nitrite and 15N-nitrate nor nitrite and nitrate excretion in the urine was different between patients and control subjects, 46.4 (9.4-152.2) versus 98.7 (29.9-146.5) nmol/mmol creatinine and 20.6 (2.1-69.0) versus 40.0 (27.0-70.1) micromol/mmol creatinine, respectively. No differences were found in serum nitrite and nitrate concentrations and glomerular filtration rates between patients and control subjects, 111.4 (73.2-158.8) versus 109.3 (83.5-176.4) micromol/l.

CONCLUSION

Our results contraindicate a greater basal NOS-dependent whole body NO production in patients with decompensated liver disease and portal hypertension.

Altered cellular calcium regulatory systems in a rat model of cirrhotic cardiomyopathy

BACKGROUND & AIMS

Decreased cardiac contractility has been observed in cirrhosis, but the cause remains unclear. Because cardiomyocyte contraction depends on Ca2+ influx entering via L-type Ca2+ channels (I(Ca,L)s) to activate Ca2+ release from the sarcoplasmic reticulum, we postulated that the Ca2+ transients may be abnormal in cirrhotic cardiomyocytes. We aimed to investigate the status of the cellular Ca2+-regulatory system in a rat model of cirrhotic cardiomyopathy.

METHODS

Cirrhosis was induced by bile duct ligation. The I(Ca,L) protein expression was detected by Western blotting. Ca2+ currents were measured electrophysiologically. The intracellular Ca2+ system, which includes the ryanodine receptor 2 (RYR2), sarcoplasmic reticulum Ca2+-pump adenosine triphosphatase (SERCA2), and Ca2+-binding protein were quantitatively assayed by reverse-transcription polymerase chain reaction and Western blots and functionally by 3H-ryanodine binding and radiolabeled Ca2+ uptake.

RESULTS

I(Ca,L) protein expression was reduced in cirrhotic rats compared with controls, and the peak inward Ca2+ current was significantly less. At all membrane potentials examined, I(Ca,L)s current densities from cirrhotic animals were consistently lower, and the response to maximal isoproterenol stimulation was also significantly lower. Protein expression and messenger RNA transcription for RYR2, SERCA2, and calsequestrin were quantitatively unchanged, and 3H-ryanodine binding characteristics and Ca2+ uptake were also unaltered.

CONCLUSIONS

We conclude that the decreased cardiac contractility in cirrhotic cardiomyocytes is caused by dysfunction of the Ca2+-regulatory system. Plasma membrane I(Ca,L)s are quantitatively reduced and functionally depressed, whereas intracellular systems are intact.

Levels of circulating endothelin-1 and nitrates/nitrites in patients with virus-related hepatocellular carcinoma

A balance between endothelins (ET) and nitric oxide (NO) might interfere with liver haemodynamics and disease progression in various liver diseases. Increased levels of endothelin 1 (ET-1) and nitrites and nitrates (NOx, the end products of NO metabolism) have been reported in hepatocellular carcinoma (HCC), but the balance has not been studied. The purpose of this study was to assess the ratio of NOx to ET-1 in patients with virus-related hepatocellular carcinoma and to investigate its correlation with the extent of the disease. Eighteen patients with virus-related HCC (six Okuda stage I, six Okuda stage II and six Okuda stage III) were included in the study and were compared with 22 patients with viral cirrhosis (14 decompensated, eight compensated) and seven normal controls. ET-1 was measured with an ELISA assay and NOx with a modification of the Griess reaction. Patients with virus-related HCC had the highest levels of circulating ET-1 and NOx (13.24 +/- 0.82 pg/ml and 112.28 +/- 18.56 micromol/l) compared to compensated cirrhosis (9.47 +/- 0.50 pg/ml, P < 0.004 and 54.47 +/- 2.36 micromol/l, P < 0.01), decompensated cirrhosis (9.57 +/- 0.32 pg/ml, P < 0.001 and 90.20 +/- 11.23 micromol/l, NS) and normal controls (8.84 +/- 0.61 pg/ml, P < 0.001 and 51.17 +/- 6.18 micromol/l, P < 0.01). There was a significant increase of ET-1 and NOx at HCC stage III compared to HCC stages I and II, cirhotics and controls. HCC stage III patients also had a NOx/ET-1 ratio that was higher than HCC stages I and II patients, normal controls and patients with compensated cirrhosis. Virus-related HCC patients have high levels of circulating ET-1, compared to compensated or decompensated cirrhosis. Highest levels of ET-1 are produced in Okuda III tumours. NOx are also increased but only in Okuda stage III tumours. The NOx/ET-1 ratio is increased in virus-related HCC and DC. This increase may account for the known increase in tumour blood flow.