Effects of angiotensin II blockade on nitric oxide blood levels in IgA nephropathy.

BACKGROUND: The effects of renin-angiotensin system blockade on nitric oxide (NO), especially in pathological conditions, are far from being established. The influence of kinins and angiotensin type 2 receptor are largely speculative and based mainly on animal studies. This study was aimed to address these aspects in humans. METHODS: Eight IgA nephropathy patients with documented clinical and histological indicators of poor prognosis were given 50 mg of losartan, 10 mg of enalapril, and 40 mg of the NO donor isosorbide 5 mononitrate (as a control of NO generation) in randomized order for 7 days each. Treatment periods were separated by washout periods of 7 days each. Laboratory investigations were performed before and after each study period. Seven healthy controls received losartan and enalapril according to the same study design. RESULTS: Glomerular filtration rate remained stable while effective renal plasma flow increased with each treatment (P<0.05). Under losartan and enalapril, filtration fraction fell (P=0.02), plasma renin activity increased (P<0.05) and urinary aldosterone concentration decreased (P=0.02). Angiotensin-converting enzyme activity was reduced to the limit of detection under enalapril (P<0.001). Blood NO, detected as nitrosylhaemoglobin by a recently developed technique of spin-trap electron paramagnetic resonance, increased significantly, as expected, during treatment with isosorbide 5 mononitrate (P=0.01), with enalapril (P<0.05), and also with losartan (P<0.05). Unlike losartan, enalapril significantly reduced albuminuria (P=0.01) in this short-term period. In the seven healthy controls, neither enalapril nor losartan were able to increase blood NO levels significantly. CONCLUSIONS: Blood levels of nitrosylhaemoglobin, a surrogate marker of NO, increased under blockade of the renin-angiotensin system in patients with IgA nephropathy, but not in healthy volunteers. This increase could contribute to changes of effective renal plasma flow in renal disease states.

Isosorbide 5 mononitrate administration increases nitric oxide blood levels and reduces proteinuria in IgA glomerulonephritis patients with abnormal urinary endothelin/cyclic GMP ratio.

An endothelin urinary hyperexcretion, which is not counterbalanced by an adequate increase in cGMP biosynthesis, was previously detected in some patients with IgA Nephropathy (IgAN). Since this imbalance might potentiate local ET1-mediated hemodynamics effects, 9 IgAN patients with an increased (> or = 0.1) urinary ET1/cGMP ratio (group 1) and 5 IgAN patients with comparable renal function and reduced ET1/cGMP ratio (group 2) were given standard doses of isosorbide 5 mononitrate (as a nitric oxide source). Blood nitric oxide (NO) levels, as detected by electron paramagnetic resonance, significantly increased after isosorbide administration (p < 0.01) and decreased after drug discontinuation in both groups. Nitric oxide levels were significantly related with those of the effective renal plasma flow (p < 0.02), but not with the glomerular filtration rate. Proteinuria levels significantly decreased after drug administration (p < 0.009) in group 1 and returned to baseline levels thereafter, except two cases showing persisting low levels. Values of filtration fraction in the same group decreased after iso5M administration (p < 0.02 compared to basal levels). These results may possibly be related to the counterbalancing effects of nitric oxide on endothelin-mediated mesangial contraction.

Urinary endothelin in glomerulonephritis patients with normal renal function.

The vasoconstrictor peptide endothelin-1 (ET1) has only recently been characterized and its effects are at present largely speculative. It has been hypothesized that ET1 acts on mesangial cells to cause vasoactive changes which might ultimately contribute to the development of glomerulosclerosis. Opposite to ET1, nitric oxide (NO) inhibits mesangial cell contraction and proliferation. NO activates soluble guanylic acid cyclase and the final product, cyclic GMP (cGMP), has been recently used as a marker of NO action. Urinary levels of ET1 and cGMP were detected in 58 patients with biopsy-proven glomerulonephritis (GN), including 36 IgA nephropathy (IgAGN), 30 with normal and 6 with impaired renal function, 10 patients with non-IgA mesangial GN and 12 pts with membranous GN (MGN) with normal renal function. Compared to normal controls (0.019 +/- 0.006 ng/min), urine ET1 levels were significantly higher in patients with normal renal function having IgAGN (0.035 +/- 0.017, p < 0.01), MGN (0.028 +/- 0.013, p < 0.05), non-IgA mesangial GN (0.027 +/- 0.012, p < 0.05) and those with IgAGN and renal failure (0.032 +/- 0.011, p < 0.01). However no difference was found between MGN patients and normals by deleting MGN cases with mild to moderate mesangial proliferation. The mean value of urinary cGMP in IgAGN patients with renal failure (0.186 +/- 0.117 nmol/min) was lower (p < 0.05) than that of each group with normal renal function (IgAGN: 0.378 +/- 0.010 nM/min; MGN: 0.338 +/- 0.064 nmol/min, non-IgAGN: 0.436 +/- 0.168 nmol/min). The same significant differences were obtained by correcting cGMP values for creatinine urinary excretion. Urinary ET/cGMP ratio (assumed as an index of the relative balance between vasoconstrictor and vasorelaxing factors) was found to be higher than normal (0.570 +/- 0.010 ng/nmol) both in IgAGN patients with normal renal function (0.103 +/- 0.064 ng/mol, p < 0.05), and in those with renal failure (0.203 +/- 0.108 ng/nmol, p < 0.02). Urinary cGMP values were not related to plasma levels of atrial natriuretic peptide (ANP). These data show that hyperexcretion of ET1 occurs in a number of patients with mesangial proliferative GN. In some of them, mainly those with established glomerular damage, the local production of ET1 is not counter-balanced by adequate cGMP biosynthesis.

Role of platelet-activating factor in polymorphonuclear neutrophil recruitment in reperfused ischemic rabbit heart.

This study investigated the role of platelet-activating factor in the recruitment of polymorphonuclear neutrophils (PMN) in a rabbit model of cardiac ischemia and reperfusion. The accumulation of PMN was evaluated 2 and 24 hours after removal of 40 minutes of coronary occlusion by morphometric analysis and 111In-labeled PMN infiltration. The administration of two structurally unrelated platelet-activating factor-receptor antagonists (SDZ 63-675, 5 mg/kg body weight, and WEB 2170, 5 mg/kg body weight) before reperfusion significantly reduced the accumulation of PMN, as well as the hemodynamic alterations and the size of necrotic area. Two hours after reperfusion, the percentage of increase of 111In-labeled PMN in transmural central ischemic zone was significantly reduced in rabbits pretreated with SDZ 63-675 (51.4 +/- 7.9) or WEB 2170 (32.4 +/- 8.8) with respect to untreated rabbits (107.6 +/- 13.5). The morphometric analysis of myocardial sections confirmed the reduction of PMN infiltration at 2 hours and demonstrated that at 24 hours the phenomenon was even more significant. In addition, SDZ 63-675 and WEB 2170 prevented early transient bradycardia and hypotension and reduced the infarct size, judged by staining with tetrazolium at 2 and 24 hours after reperfusion, and by histological examination at 24 hours. These results suggest that platelet-activating factor is involved in the accumulation of PMN in the reperfused ischemic myocardium and contributes to the evolution of myocardial injury.

Serum and intracellular detection of cytokines in patients undergoing chronic hemodialysis.

Tumor necrosis factor (TNF) was detected, before and after dialysis, in sera from 69 patients and, at various times during dialysis, in 28 patients carefully selected for the absence of intercurrent illness. Blood samples were also sequentially collected for separation of monocytes, and cells were sonicated to detect intracellular TNF. Compared with serum levels obtained from 41 healthy subjects, basal TNF values of the unselected group of 69 patients were significantly higher (p < 0.01), independent of the dialyzer membrane. A significant increase in TNF levels by the end of dialysis was found only with Cuprophan (p < 0.01). In the selected group of 28 patients, no significant changes in TNF values were observed in sequential samples. However, a significant increase of intramonocyte TNF levels was found in Cuprophan patients (p < 0.025). Soluble interleukin-2 receptor (IL-2R) levels, measured in parallel in sera from unselected and selected patients, were found to be very much higher than healthy controls without significant changes during the dialysis procedure. While the diverse profiles of TNF obtained from differently selected patients suggest that mechanisms other than membrane biocompatibility play a role in the appearance of these low cytokine levels, the possible nature of uremic toxin for soluble IL-2R can be envisaged by detection in dialysis patients.

Increased serum neopterin concentration as indicator of disease severity and poor survival in multiple myeloma.

In this study we investigated serum neopterin levels in 73 multiple myeloma (MM) patients (63 determinations at diagnosis, 58 in remission, and 35 at relapse), in 56 monoclonal gammopathies of undetermined significance (MGUS), and in 70 normal controls. Median neopterin level was 5.3 nmol/l in normal controls, 6.8 nmol/l in MGUS, and 10.7 nmol/l in MM patients. In comparison to healthy subjects, significantly higher levels were observed in MM patients (p less than 0.0001). A statistical difference was observed between MGUS and MM patients at diagnosis (p less than 0.007). Compared to diagnosis, a further increase was noticed during relapse, suggesting a correlation between neopterin and disease activity. The prognostic significance of raised neopterin levels was confirmed by a survival analysis. Median survival for patients with high values was 20 months, whereas it was 63.9 months for those with low values (log-rank test p less than 0.003). Serum neopterin concentrations also correlated to beta 2 microglobulin levels and the percentage of CD38+ circulating lymphocytes, indicating a link between neopterin and other myeloma prognostic factors.

[Tag 72: a new tumor-associated antigen identified by a monoclonal antibody]. / Tag 72: un nuovo antigene tumore associato riconosciuto da un anticorpo monoclonale.

In order to evaluate the usefulness of Tag 72--tumor associated antigen assay--in gastroenterology, we have studied with Ca 72-4 radioimmunoassay (Centocor) 551 patients suffering benign (233) and neoplastic (318) gastrointestinal diseases and 205 normal controls. The cut-off point was fixed at 6 U/ml. Only in gastric cancers, the Tag 72 assay, with the proposed method, provide additional information in this pathology (sensitivity 30%, specificity 98.7%). The most striking observation to be made from the current study is a poor sensitivity of the test for gastrointestinal cancers, but rather the excellent specificity of the Ca 72-4 IRMA with respect to benign gastrointestinal diseases. The sensitivity of Ca 72-4 assay, vs Ca 19-9 and CEA, for the same diseases, is less, but specificity is better.

Significance of CA 72.4 serum levels in gastrointestinal diseases.

In order to evaluate the usefulness of Ca 72.4 tumor associated antigen assay in gastrointestinal diseases, we have studied 751 patients suffering from benign (376) and neoplastic (375) digestive diseases and 305 normal controls. The cut-off point was fixed at 6 U/ml. The Ca 72.4 assay, with the proposed method, provides additional information only in gastric cancers; the positivity of the marker in gastric neoplasms is 38.4% and the specificity vs gastric ulcers and atrophic gastritis is 99%. In six patients with gastric cancer, the Ca 72.4 is the only positive test. The most striking observation to be made from the current study is a no good sensitivity of the marker for gastrointestinal cancers (29.6% vs 35.7 and 37.6% for CEA and Ca 19-9 respectively), but rather the excellent specificity of the Ca 72.4 immunoassay with respect to being gastrointestinal diseases (98.7%), vs values of specificity for CEA and Ca 19-9 of 94 and 92%. In conclusion, the high specificity of this marker for gastrointestinal neoplasms may be very interesting in follow-up studies. In fact, an elevation of serum levels of Ca 72.4 should always be taken seriously.

Laser-induced vaporization mass spectrometry of rifamycins.

The mass spectra of many rifamycins cannot be obtained by electron ionization (EI) owing to their thermal decomposition. When a laser beam is used to vaporize the sample through an optic fibre inserted in a hollow probe which reaches the sample cup, decomposition is minimized and the EI spectra show abundant molecular ions and fragments of structurally high diagnostic value. These ionic species are easily observed owing to the lack of chemical noise often present in soft ionization methods, such as direct liquid chemical ionization and fast atom bombardment.

[Determination of tumor-associated trypsin inhibitor (TATI) in subjects with gastrointestinal diseases. Preliminary data]. / Dosaggio del tumor associated trypsin inhibitor (TATI) in soggetti con malattie gastrointestinali. Dati preliminari.

Tumor-associated trypsin inhibitor (TATI) is a 6 K dalton protease inhibitor, that was isolated from urine of a patient with ovarian cancer. In our experience, mean serum level of TATI in healthy subjects (n. 120), is 13 micrograms/l (range 5.1-42 micrograms/l). The cut-off point is established in 32 micrograms/l (mean +/- 3 SD). We have examined 357 patients with gastrointestinal diseases: 98 gastric cancer, 50 colon cancers, 52 pancreatic cancers, 32 chronic pancreatitis, 38 IBD, 28 colon polyps, 40 gastric ulcers and 25 non-neoplastic biliary tree diseases. TATI may be a good tumor marker only in gastric cancer. Elevated levels of TATI also occur in obstructive hepatobiliary disease and active pancreatitis or IBD.