Embolisation of a high - flow renal arteriovenous fistula with the use of simultaneous transvenous and transarterial approach and balloon-assisted coil embolization.

BACKGROUND: Renal arteriovenous fistula (RAVF) is a rare vascular malformation, which can be asymptomatic or may cause hemorrhage, hypokalaemic hypertension, heart failure and hematuria. Endovascular embolization is a minimally invasive method which can preserve renal parenchyma. In our case, balloon assisted coil embolization with simultaneous transvenous and transarterial approach was used. A remodelling balloon, which is routinely used in neurovascular procedures, was chosen in order to eliminate the risk of coil migration and preserve feeding artery and renal parenchyma. CASE PRESENTATION: We present a case of successful balloon - assisted coil embolization of a high flow renal arteriovenous fistula in a 25-year-old male patient via simultaneous transarterial and transvenous approach with preservation of the feeding artery. CONCLUSION: Endovascular embolisation is a safe and effective treatment of RAVFs with low risk of complications. Simultaneous transarterial and transvenous coil deployment with the use of a flow control balloon catheter can eliminate the risk of coil migration and coil protrusion into the parent artery with permanent RAVF occlusion and renal parenchyma preservation.

Hypoglycaemia requiring medical assistance in patients with diabetes: a prospective multicentre survey in tertiary hospitals.

AIM: Hypoglycaemia is considered a factor contributing to morbidity and mortality in patients with diabetes. The aim of the present study was to examine the frequency, clinical characteristics, predisposing factors and outcomes of iatrogenic hypoglycaemia requiring medical assistance. METHODS: Eight hospitals participated in this prospective survey of documented iatrogenic hypoglycaemia at their emergency departments. Cases with type 2 diabetes (T2D) were compared with a control group, consisting of patients visiting the outpatients' diabetes clinics of the same hospitals during the same time period. RESULTS: Median survey duration was 16.5 months, and 295 episodes of iatrogenic hypoglycaemia were recorded. Frequency varied across centres from 0.25 to 0.78 cases per 100 presenting patients. Most cases (90.8%) were observed in patients with T2D (mean age: 76.7±10.1 years), while 8.1% of events were recorded in patients with type 1 diabetes (mean age: 42.7±18.3 years). Total in-hospital mortality was 3.4%, and all involved patients with T2D. In T2D patients, advanced age (OR: 1.3 [1.20-1.45] for 5-year increase), use of sulphonylureas (OR: 4.0 [2.5-6.36]), use of insulin (OR: 2.35 [1.42-3.95]), lower estimated GFR (OR: 1.15 [1.07-1.23] at 10mL/min) and number of comorbidities (OR: 1.74 [1.34-2.27]) were each independently associated with hypoglycaemia requiring medical assistance. CONCLUSION: Hypoglycaemia requiring medical assistance in patients with diabetes is a moderately common condition seen in emergency departments and has a mortality rate of 3.4%. The majority of cases involve elderly individuals with T2D who are suffering from serious comorbidities and treated with insulin and/or sulphonylureas.

Endovascular treatment of ruptured dissecting posterior inferior cerebellar artery aneurysms.

Dissecting aneurysms of the posterior inferior cerebellar artery (PICA) distal to its origin from vertebral artery (VA) are very rare. Although rare, they associated with a high risk of rebleeding and they present a therapeutic challenge. This study reviewed the clinical presentations, angiographic characteristics of dissecting aneurysms of the PICA and to assess the clinical and angiographic outcomes of patients who underwent endovascular treatment. Ten patients with ten dissecting aneurysms who underwent endovascular treatment were identified in the clinical records of a single medical center from January 2000 to December 2010. The mean follow-up duration was 2.8 years. All patients presented with subarachnoid hemorrhage (SAH). They all underwent endovascular treatment, which included occlusion of the dissected segment and the parent artery after detailed angiographic evaluation of the vascular anatomy, and test occlusion of the PICA. In all patients the endovascular treatment was successfully completed without procedure related complications. Long-term follow-up studies in seven out of ten patients showed complete occlusion of the aneurysm with no new neurologic deficits. The clinical outcome was good in eight cases, whereas two patients with poor clinical condition at admission died during their initial hospital stay. Endovascular occlusion of the parent vessel and the dissected segment is relatively safe treatment option for dissecting aneurysms of the PICA distal to its origin.

Reversible cerebral vasoconstriction syndrome: treatment with multiple sessions of intra-arterial nimodipine and angioplasty.

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by acute severe headache with or without additional neurological symptoms and reversible cerebral vasoconstriction. Unruptured aneurysms have been reported in some cases with RCVS. We describe a severe case of a 50-year-old woman with RCVS presenting as cortical subarachnoid hemorrhage. Cerebral angiogram demonstrated the typical angiographic findings of RCVS and two very small unruptured aneurysms of the left internal carotid artery. The patient was treated with calcium channel blockers and the two aneurysms were successfully treated endovascularly. On day 16 the patient developed new focal neurological symptoms (severe paraparesis) and was successfully treated with intraarterial nimodipine and angioplasty in multiple sessions.

Transcatheter arterial embolization as therapy of renal angiomyolipomas: the evolution in 15 years of experience.

OBJECTIVE: This study aims at presenting the evolution of the embolization technique in treating renal angiomyolipomas (AMLs) either diagnosed in patients with acute bleeding or discovered accidentally. METHODS: Ten patients with renal AMLs have been through thirteen selective transcatheter arterial embolizations for 15 years. Two patients had tuberous sclerosis complex (TSC) with bilateral tumors and were embolized twice. Four embolic materials were employed: PVA particles, Gianturco coils, microspheres and microcoils. Catheterization was achieved by means of 5F Cobra 2 catheters and coaxial microcatheter systems. RESULTS: On an emergency basis, embolization was a first-line treatment. In one case, surgery was necessary; in two patients, a second embolization was performed. When treatment was preventive, a single embolization proved to be sufficient, as well. There was no significant deterioration of the serum creatinine levels in the post-embolization period. CONCLUSION: Selective arterial embolization is a rather safe and effective technique to treat AMLs both urgently and preventively. Different embolic materials can be employed. Microspheres and microcatheters stand for new promising materials.

Prevalence of overweight and abdominal obesity in Greek children 6-12 years old: Results from the National Epidemiological Survey.

OBJECTIVE: To provide estimates of overweight (OW), obesity (OB) and abdominal obesity (AO) in a sample of children throughout the whole of Greece. MATERIAL AND METHODS: This epidemiological, cross-sectional survey examined 3,140 children aged 6-12 y (1,589 boys and 1,551 girls) who were selected by stratified sampling through household family members of Greek adolescents attending school. Participants reported data on height, weight and waist circumference (WC). BMI and Waist-to-Height ratio (WHtR) were calculated. AO was estimated using WC and WHtR. RESULTS: Overall prevalence of OW including OB was 31.2% in boys and 26.5% in girls, while OB prevalence was 9.4% and 6.4% respectively. The prevalence of AO based on WC (AO-WC), was similar in girls (14.2%) and boys (12.5%) while the prevalence of AO, based on WHtR (AO-WHtR), was higher in boys than in girls (25.6% vs 20.0%, p<0.0001). With increasing age, the prevalence of OW and OB decreases in both genders, and AO-WHtR only in girls. Rates of OW were significantly more prevalent in Greeks than in immigrants. CONCLUSIONS: Overweight and obesity in Greek children is very prevalent, particularly in boys, comparable with that reported for Mediterranean European countries. Abdominal obesity also appears high. Preventive and treatment strategies are urgently needed to combat this national epidemic.

Comparative study of the immunohistochemical expression of metalloproteinases 2, 7and 9between clearly invasive carcinomas and "in situ" trophoblast invasion.

KEYWORDS: Matrix metalloproteinases (MMPs) are endopeptidases considered to participate in the transient invasive property of trophoblastic cells during embryo implantation and placentation. The same molecules play an important role in the invasive and metastatic potential of cancer cells. The aim of this study was to compare the immunohistochemical expression of MMP2, 7and 9between clearly invasive carcinomas and "in situ" trophoblast invasion in an effort to illuminate their distinct roles in uncontrolled and controlled invasion.
We performed an immunohistochemical analysis of 45 clearly invasive carcinomas of various organs (colorectal, gastric, breast, pulmonary, renal) and 40 first trimester gestation specimens (before the 9th week of gestation). The markers expression was evaluated semiquantitavely, seperately in cancer parenchymal and gestational trophoblastic cells as well as cancer stromal and decidual cells, according to apercentage scale (0 %, 50% of cells) and according to staining intensity (0, +, ++, +++).
MMP9 was expressed more often in the malignant parenchymal as well as in the malignant stromal component of carcinomas than in the trophoblastic (p=0, 0118) and decidual (p=0,017) component of gestations respectively. Although all carcinomas and almost all gestation specimens stained for MMP2 and MMP7, the immunostaining for both molecules was statistically more extensive and intense in trophoblasts and decidual cells by comparison to cancerous elements.
In conclusion, although there seems to be adirect link between cancer invasion and MMP9 immunohistochemical expression, the role of MMP2 and MMP7 appears to be more complicated underlining the complexity of the mechanisms involved in cancer spreading.

Outcomes of kidney transplantation in Greek and Albanian patients: a single centre experience.

BACKGROUND AND AIM: It has been reported that racial and ethnic (genetic make up), as well as socioeconomic differences may affect the results of kidney transplantation. Socioeconomic factors are quite difficult to differentiate from genetic factors. It is not surprising that a group with poorer access to health care, less private insurance and less income does less well with serious medical problems. The aim of this study was to compare the outcomes of kidney transplantations in Greek (G) and Albanian (A) patients. PATIENTS AND METHODS: Twenty nine transplanted patients of Albanian ancestry were matched with 29 Greek patients retrospectively. Their mean age was 34 (G) and 31 (A) years, there were 21 men and 8 women in each group (G, A) and they received 26 kidneys from living related donors and 3 kidneys from cadaveric donors respectively. Arterial blood pressure (ABP), body weight (BW), serum creatinine, serum total protein and albumin, total cholesterol, HDL-cholesterol and triglycerides, 24 hour proteinuria were measured on 7th, 15th postoperative day, 1st , 3rd , 6th month and 1st year after transplant. BMI was calculated before and 1 year after transplantation and acute rejection episodes were recorded too. Methylprednizolone (MP), cyclosporine (CsA) dose /kg BW were calculated at baseline, 1, 3, 6, 12 months after transplant. Cumulative patient and graft survival at 1 and 5 years were calculated too. RESULTS: Patient survival at 1 and 5 years was 100% / 93.1% and 100% /93.1% respectively (p: NS). Graft survival at 1 and 5 years was 100% / 93.10% and 93.75% / 86.45% respectively (p: NS). BW (but not BMI) and total cholesterol levels in Greek patients were higher compared to those of Albanian patients during the 1st post transplant year (p: 0.044 and p: 0.021 respectively). MP dose in A patients was higher during the first year (p: 0.05). CONCLUSION: Patients and graft survival do not present difference between G and A patients. There is significant difference on cholesterol profile between G and A patients. A larger number of transplants are possibly needed to allow us to draw firm conclusions.

Successful embolization of a giant perimedullary arteriovenous fistula of the cervical spine in a 6-year-old child.

CASE: We report a case of a 6-year-old boy with a giant perimedullary arteriovenous fistula of the cervical spine who presented with progressive tetraparesis. METHOD: Transarterial glue embolization was performed and complete occlusion of the fistula was achieved. RESULT: The patient's symptoms resolved completely during the next year.

Endovascular treatment of peripheral intracranial aneurysms.

BACKGROUND AND PURPOSE: Distally located cerebral aneurysms are difficult to treat with preservation of the parent vessel. We report the angiographic results and clinical outcome for 27 patients with peripheral cerebral aneurysms. METHODS: From January 2000 to June 2005, 27 patients, 13 female and 14 male, presented to our institution with peripheral intracranial aneurysms and were treated endovascularly. None of these aneurysms were mycotic in origin. The age of our patients ranged from 23 to 76 years with a mean age of 53. Twenty of the 27 patients had subarachnoid and/or intracerebral hemorrhage upon presentation. In 5 patients, the aneurysm was an incidental finding. One patient with a fusiform P2 aneurysm presented with cranial nerve III palsy, and another patient with P4 aneurysm had visual disturbances. Locations of the aneurysms were as follows: posterior cerebral artery in 9 patients, superior cerebellar artery in 5 patients, anterior inferior cerebellar artery in 1 patient, posterior inferior cerebellar artery in 5 patients, middle cerebral artery (MCA) in 5 patients, and anterior cerebral artery in 2 patients. RESULTS: Seven patients were treated with selective embolization with Guglielmi detachable coils (GDCs). Nineteen patients with fusiform aneurysms underwent parent artery occlusion (PAO). Fifteen PAOs were performed with coils and 4 with glue. One patient with a MCA aneurysm was found at the time of planned embolization to have spontaneously thrombosed the aneurysm and the distal branch of the MCA, 1 day after the initial diagnostic angiogram. Five patients (5/18 or 27.7%) who underwent PAO developed neurologic deficits. Two patients (2/18 or 11.1%) had permanent neurologic deficits (a visual field defect). CONCLUSION: Our results support that distally located aneurysms can be treated with endovascular PAO in the cases in which selective occlusion of the aneurysmal sac with GDC or surgical clipping cannot be achieved.

First national epidemiological survey on the prevalence of obesity and abdominal fat distribution in Greek adults.

AIM: To provide estimates of the prevalence of obesity, overweight and body fat distribution among the adult population of Greece. DESIGN: Epidemiological, cross-sectional nationwide survey providing self-reported data. SUBJECTS: A total of 17,341 men and women aged from 20 to 70 years and classified into five 10-year age groups participated. The selection was conducted by stratified sampling through household family members of Greek children attending school. MEASUREMENTS: The participants reported data on weight, height, waist and hip circumference. BMI and waist-to-hip ratio were calculated. Abdominal obesity was defined as waist circumference > or = 102 cm in men and > or = 88 cm in women. RESULTS: In the total population, the mean BMI was 26.5 kg/m2, (27.3 in men, 25.7 in women). The overall prevalence of obesity was 22.5%, (26% in men, 18.2% in women) while that of overweight was 35.2% (41.1% in men, 29.9% in women). The percentages of obesity and overweight in men were similar in almost all age groups, while in women they progressively increased with age. Abdominal obesity was more frequent among women than men (35.8 vs. 26.6%, respectively), especially after the age of 50. CONCLUSIONS: Excess body weight is reaching epidemic proportions in Greece and obesity rates are among the highest, if not the highest, in Western society. The problem affects particularly men, and women after menopause. Interestingly, more women than men present with abdominal obesity. Preventive and treatment strategies are urgently needed to stop the obesity epidemic in this Mediterranean European country.

The J-shape effect of alcohol intake on the risk of developing acute coronary syndromes in diabetic subjects: the CARDIO2000 II Study.

AIMS: To identify the threshold of alcohol consumption above which the balance of risk and benefit becomes adverse in diabetic subjects. METHODS: We studied demographic, lifestyle, dietary and clinical information in 216 hospitalized diabetic patients (171 men, 63 +/- 9 years old, 45 women, 67 +/- 5 years old) with a first event of an acute coronary syndrome (ACS) and 196 frequency matched (age-sex) diabetic controls, without any clinical evidence of coronary heart disease. Alcohol consumption was quantified and a measure for the comparisons was predetermined to be a wine glass (100 ml of wine, 12 g of ethanol) and its alcohol equivalents. RESULTS: Alcohol consumption was associated with an age-adjusted J-shape relationship with total cholesterol, blood pressure and smoking (all P < 0.001). A J-shape association was also found between alcohol intake and the risk of ACS (OR = 2.54-2.43 x (alcohol intake) + 0.80 x (alcohol intake)2, R2 = 0.96, P < 0.001), adjusted for several risk factors and interactions between alcohol intake and smoking status, job and familial stress, and low income. In particular, low alcohol consumption (< 12 g/day) was associated with a 47% (OR = 0.53, 95% CI 0.28-0.97) reduction of the prevalence of ACS, while a higher intake (12-24 and > 24 g/day) increased the prevalence by 2.7-fold (OR = 2.72, 95% CI 1.39-5.38) and 5.4-fold (OR = 5.44, 95% CI 1.21-24.55), respectively. CONCLUSIONS: Alcohol intake is a significant predictor of coronary events. Low-to-moderate intake seems to be associated with a reduction in the prevalence of ACS in diabetes, whereas higher consumption is associated with an increase in lipids and blood pressure levels, and also the risk of developing ACS.

Cortical laminar necrosis in brain infarcts: serial MRI.

High-signal cortical lesions are observed on T1-weighted images in cases of brain infarct. Histological examination has demonstrated these to be "cortical laminar necrosis", without haemorrhage or calcification. We report serial MRI in this condition in 12 patients with brain infarcts. We looked at high-signal lesions on T1-weighted images, chronological changes in signal intensity and contrast enhancement. High-signal cortical lesions began to appear about 2 weeks after the ictus, were prominent at 1-2 months, then became less evident, but occasionally remained for up to 1.5 years. They gave high signal or were isointense on T2-weighted images and did not give low signal at any stage. Contrast enhancement of these lesions was prominent at 1-2 months, and less apparent from 3 months, but was seen up to 5 months.

Glibenclamide improves postprandial hypertriglyceridaemia in type 2 diabetic patients by reducing chylomicrons but not the very low-density lipoprotein subfraction levels.

AIM: There are scarce data dealing with the degree of postprandial lipaemia after sulphonylurea administration. The aim of this study was to examine the effect of acute glibenclamide administration on postprandial lipaemia in Type 2 diabetic patients. METHODS: Eight randomly selected Type 2 diabetic individuals, aged 43-65 years (mean, 54 years), who had never received any anti-diabetic drug, were included in the study. Each patient was given a 485 kcal mixed meal (45% fat, 40% carbohydrate and 15% protein) twice on separate days after an overnight fast: once with placebo and once with 5 mg glibenclamide, per os, in a random order. The two tests were performed with an interval of 7 days. Venous blood samples were drawn just before and 2 h, 4 h and 6 h after meal consumption. Total triglyceride levels in plasma, in chylomicrons (CM), in CM-deficient plasma, in very low-density lipoprotein (VLDL) subfractions (VLDL-1, VLDL-2) and in intermediate-density lipoprotein (IDL) were determined. Free fatty acid (FFA) and total cholesterol levels in plasma, as well as high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol levels in CM-deficient plasma, were also measured. Finally, serum glucose, insulin and C-peptide concentrations were measured in each sample. RESULTS: As expected there was a significant decrease in postprandial glycaemia after glibenclamide administration compared to placebo (mean area under the curve values: AUC = 53.3 +/- 18.2 and 69.1 +/- 21.6 mm/h, P = 0.00009). In addition, the mean AUC values of insulin and C-peptide were significantly greater after drug administration. The AUC values of total plasma triglyceride and of CM triglyceride following glibenclamide administration were significantly lower compared to placebo, while the AUC values of postprandial triglyceride in CM-deficient plasma and of postprandial triglyceride in VLDL-1, VLDL-2 and IDL were not different after drug administration compared to placebo. Finally, no significant differences were noted in the AUC values of total cholesterol, LDL cholesterol, HDL cholesterol and plasma FFA levels after glibenclamide administration. CONCLUSIONS: These results demonstrate that glibenclamide administration improves postprandial hypertriglyceridaemia acutely by reducing postprandial triglycerides of intestinal origin.

Effects of glibenclamide on postprandial coagulation activation.

BACKGROUND AND AIM: Previous data indicate that even mild postprandial hyperglycaemia in diabetic subjects, who are concerned to be in good control, activates haemostasis. The aim of this study was to investigate the effect of the oral administration of 5 mg glibenclamide on postprandial activation of coagulation in type 2 diabetics. METHODS AND RESULTS: We designed a placebo controlled, randomised study. After an overnight fast, each subject (n = 16, age 50-68 yr.) underwent a standard test meal (600 Kcal: carbohydrates 40%, lipids 50%, proteins 10%) preceded by one tablet of glibenclamide (5 mg) or placebo. The two tests were performed randomly, with an interval of 7 days. Blood samples were collected at baseline and 2 and 4 hours after the meal to measure the concentrations of glucose, insulin, c-peptide, triglycerides as well as of d-dimers, fibrinogen, F1.2 and TAT. The postprandial levels of TAT, fibrinogen, F1.2, d-dimers, insulin, glucose and triglycerides were significantly higher compared to baseline values. CONCLUSIONS: The postprandial levels of glucose, triglycerides, fibrinogen, F1.2, TAT and d-dimers were lower after glibenclamide administration as compared to placebo, while the concentrations of insulin and c-peptide were higher. Thus, acute administration of glibenclamide reduces the postprandial activation of coagulation.

Coronary-subclavian steal syndrome: treatment with percutaneous transluminal angioplasty and stent placement.

The aim of this study was to assess the efficacy of percutaneous transluminal angioplasty (PTA) and stenting in the management of the coronary-subclavian steal syndrome (CSSS). A 56-year-old man presented with CSSS due to occlusion of the left subclavian artery. He was treated with PTA and placement of two stents in the left subclavian artery. Systolic blood pressure became equal in both arms and dizziness disappeared. There were no complications. Percutaneous transluminal angioplasty and stenting can effectively and safely manage CSSS.

Nitric oxide metabolites in cystic fibrosis lung disease.

Although the activity of nitric oxide (NO) synthases are increased in lung tissue of patients with cystic fibrosis, the concentrations of nasal and exhaled NO have recently been found to be decreased in cystic fibrosis. This could either be due to reduced NO formation or metabolism of NO within airway fluids. In this study, the stable NO metabolites, nitrate and nitrite, were determined in the saliva and sputum of 18 stable cystic fibrosis patients, 21 cystic fibrosis patients during a pulmonary exacerbation, and in saliva and endotracheal secretions of normal controls. Median saliva concentrations of NO metabolites (nitrate plus nitrite) were 704 mumol/l (95% confidence interval (CI) 419 to 1477) in stable cystic fibrosis patients, 629 mumol/l (95% CI 382 to 1392) in cystic fibrosis patients presenting with pulmonary exacerbation, and 313 mumol/l (95% CI 312 to 454) in controls. Median sputum NO metabolite concentration in stable cystic fibrosis was 346 mumol/l (95% CI 311 to 504). This was not significantly different from cystic fibrosis patients presenting with pulmonary exacerbation (median 184 mumol/l, 95% CI 249 to 572), but significantly higher than in endotracheal secretions of controls (median 144 mumol/l, 95% CI 96 to 260). Sputum NO metabolite concentration in cystic fibrosis pulmonary exacerbation significantly increased during antibiotic treatment. A positive correlation was observed between sputum NO metabolites and lung function in stable cystic fibrosis, suggesting less airway NO formation in cystic fibrosis patients with more severe lung disease. These data indicate that decreased exhaled NO concentrations in cystic fibrosis patients may be due to retention and metabolism of NO within the airway secretions. However, sputum NO metabolites are not a useful marker of airway inflammation in cystic fibrosis lung disease.

Low toxicity of nitric oxide against endothelial cells under physiological oxygen partial pressures.

Cultured rat liver endothelial cells were incubated with 1 and 2 mM spermineNONOate at different O2 concentrations in the incubation atmosphere. (Z)-1-{N-[3-Aminopropyl]-N-[4-(3-aminopropylammonio) butyl]-amino}diazen-1-ium-1,2- diolate (spermineNONOate), at 2 mM, was highly cytotoxic at 21% and 95% O2 (as measured by lactate dehydrogenase release); more than 80% of the cells were damaged after 6 h of incubation. Cytotoxicity induced by 2 mM spermineNONOate was significantly decreased at 10%, 5% and 0% O2; cell death was 54%, 36% and 25% respectively after 6 h of incubation. In contrast, 1 mM spermineNONOate was almost non-toxic towards the cells. Only at 95% O2 was a slight damaging effect, of 25%, observed. The nitric oxide (.NO) concentrations released from 1 and 2 mM spermineNONOate were determined as varying between 5 and 12 microM and between 12 and 22 microM respectively as measured by the oxyhaemoglobin and the NO cheletropic spin-trapping methods. The decomposition rate of spermineNONOate and the resulting .NO concentrations were independent of O2 at all applied concentrations. Likewise, the steady-state concentrations of H2O2 remained at approx. 1 nM at all O2 concentrations, as measured with the fluorescent dye scopoletin. L-Tyrosine and L-ascorbate, both of which are known to scavenge reactive nitrogen species, markedly diminished spermineNONOate-induced cytotoxicity at 95% O2. The formation of 3-nitrotyrosine, indicating the reaction of L-tyrosine with nitrogen dioxide (.NO2) and/or peroxynitrite anions, was enhanced in incubations with spermineNONOate at 21% and 95% O2. The results demonstrate that at O2 partial pressures typically found under physiological conditions and at .NO concentrations that can occur in vivo, .NO alone is almost non-toxic towards cultured rat liver endothelial cells. .NO at these concentrations in vivo, however, exerts toxic effects at supraphysiological O2 partial pressures, owing to its oxidation to reactive nitrogen species such as .NO2.

Metabolites of nitric oxide in the lower respiratory tract of children.

UNLABELLED: Nitric oxide (NO) is produced in the upper and lower respiratory tract and can be detected in exhaled air of both healthy individuals and subjects with pulmonary diseases. Recent studies have shown that exhaled NO is mainly derived from the upper airways. There is, however, evidence that in aqueous solutions NO is rapidly converted to distinct oxides of nitrogen. We therefore studied the stable NO metabolites nitrate and nitrite in broncho-alveolar lavage (BAL) fluid and serum as indicators of NO formation in the lower respiratory tract. The study population consisted of 31 healthy children undergoing elective surgery for non-pulmonary illnesses and 13 immunosuppressed children with pneumonia. Nitrate and nitrite were determined photometrically. Nitrate was found in BAL fluid of all children. In children with pneumonia, nitrate concentrations in BAL fluid were significantly higher than in healthy children. A significant correlation was observed between nitrate in BAL fluid and serum of immunosuppressed children with pneumonia. Nitrite was not detected in any of the BAL fluid or serum samples. CONCLUSIONS: Our results suggest that in the lower airways significant amounts of NO are metabolised to nitrate. Studies on NO in pulmonary diseases should therefore include determination of nitrate in lower airway fluids.