Treatment of an aneurysm of the celiac artery arising from a celiomesenteric trunk. Report of a case.

INTRODUCTION: Visceral artery aneurysms (VAA) are rare, frequently present as a life-threatening emergency and are often fatal. The celiacomesenteric trunk (CMT), a common origin of the celiac trunk (CT) and the superior mesenteric artery (SMA) from abdominal aorta, is quite rare. Aneurysms that involve this celiomesenteric anomaly are even rarer and in the last 32 years have been reported in only 20 cases in the literature. PRESENTATION OF CASE: We describe a case with 30mm aneurysm arising from a CMT. In general, an aneurysm that is 20mm or greater in size is considered to be significant enough to warrant treatment. Abdominal VAA sometimes can be treated with low-invasive procedures: our patient required open surgical repair with the celiac artery replanted on to the aorta. DISCUSSION: The clinical course was complicated only by an increase of hepatic cytolysis enzymes, and by a low output pancreatic fistula, treated conservatively. The patient was discharged on the fifteenth postoperative day. One month after discharge, imaging revealed a good patency of all reconstructed arteries. In the subsequent 36-month follow-up period, the patient reported no clinical episodes. CONCLUSION: Our finding of a very rare case of a celiomesenteric anomaly with a concurrent aneurysm is extremely rare (20 cases in word literature in the last 32 years). The feasibility of the endovascular approach for aneurysms originating from the common celiomesenteric trunk depends mainly on aneurysmal location, diameter and neck size. In case of specific unfit anatomy, a careful surgical treatment can ensure the best results.

Calcium channel subtypes contributing to acetylcholine release from normal, 4-aminopyridine-treated and myasthenic syndrome auto-antibodies-affected neuromuscular junctions.

1 Acetylcholine release at the neuromuscular junction relies on rapid, local and transient calcium increase at presynaptic active zones, triggered by the ion influx through voltage-dependent calcium channels (VDCCs) clustered on the presynaptic membrane. Pharmacological investigation of the role of different VDCC subtypes (L-, N-, P/Q- and R-type) in spontaneous and evoked acetylcholine (ACh) release was carried out in adult mouse neuromuscular junctions (NMJs) under normal and pathological conditions. 2 omega-Agatoxin IVA (500 nM), a specific P/Q-type VDCC blocker, abolished end plate potentials (EPPs) in normal NMJs. However, when neurotransmitter release was potentiated by the presence of the K(+) channel blocker 4-aminopyridine (4-AP), an omega-agatoxin IVA- and omega-conotoxin MVIIC-resistant component was detected. This resistant component was only partially sensitive to 1 micro M omega-conotoxin GVIA (N-type VDCC blocker), but insensitive to any other known VDCC blockers. Spontaneous release was dependent only on P/Q-type VDCC in normal NMJs. However, in the presence of 4-AP, it relied on L-type VDCCs too. 3 ACh release from normal NMJs was compared with that of NMJs of mice passively injected with IgGs obtained from patients with Lambert-Eaton myasthenic syndrome (LEMS), a disorder characterized by a compromised neurotransmitter release. Differently from normal NMJs, in LEMS IgGs-treated NMJs an omega-agatoxin IVA-resistant EPP component was detected, which was only partially blocked by calciseptine (1 micro M), a specific L-type VDCC blocker. 4 Altogether, these data demonstrate that multiple VDCC subtypes are present at the mouse NMJ and that a resistant component can be identified under 'pharmacological' and/or 'pathological' conditions.

N-acetylcysteine inhibits in vivo nitric oxide production by inducible nitric oxide synthase.

This in vivo study evaluates the effect of N-acetylcysteine (NAC) administration on nitric oxide (NO) production by the inducible form of nitric oxide synthase (iNOS). NO production was induced in the rat by the ip administration of 2 mg/100 g lipopolysaccharide (LPS). This treatment caused: (1) a decrease in body temperature within 90 min, followed by a slow return to normal levels; (2) an increase in plasma levels of urea, nitrite/nitrate, and citrulline; (3) the appearance in blood of nitrosyl-hemoglobin (NO-Hb) and in liver of dinitrosyl-iron-dithiolate complexes (DNIC); and (4) increased expression of iNOS mRNA in peripheral blood mononuclear cells (PBMC). Rat treatment with 15 mg/100 g NAC ip, 30 min before LPS, resulted in a significant decrease in blood NO-Hb levels, plasma nitrite/nitrate and citrulline concentrations, and liver DNIC complexes. PBMC also showed a decreased expression of iNOS mRNA. NAC pretreatment did not modify the increased levels of plasma urea or the hypothermic effect induced by the endotoxin. The administration of NAC following LPS intoxication (15 min prior to sacrifice) did not affect NO-Hb levels. These results demonstrate that NAC administration can modulate the massive NO production induced by LPS. This can be attributed mostly to the inhibitory effect of NAC on one of the events leading to iNOS protein expression. This hypothesis is also supported by the lack of effect of late NAC administration.

Peptide neurotoxins, small-cell lung carcinoma andneurological paraneoplastic syndromes.

Peptide neurotoxins isolated from the venom of snakes, spiders and snails have represented invaluable tools for the identification and characterisation of membrane ion channels and receptors in vertebrate cells, including human neurons. We here report on the use of these toxins for the characterisation of membrane ion channels and receptors expressed by one of the most aggressive human cancers, small-cell lung carcinoma. This tumour shares many properties with other neuro-endocrine cell types, including the ability of firing action potentials and release hormones in a calcium-dependent manner. Toxins such as alpha-bungarotoxin and omega-conotoxins, among others, have been successfully used to characterise neuronal nicotinic receptors and voltage-dependent calcium channels, respectively, in human small-cell lung carcinoma cells. These receptors and ion channels are not only crucial for the growth of this specific tumour, but also represent autoantigens against which cancer patients build an autoimmune response. Although the aim of this autoimmune response is eventually the destruction of the cancer cells, the circulating antibodies cross-react with similar ion channels and receptors present in normal neurons or other cells, causing a number of different paraneoplastic diseases, the best characterised of which is the Lambert-Eaton myasthenic syndrome. Conotoxin-based radioimmunoassays have become an invaluable tool for the diagnosis and follow up of these paraneoplastic disorders and could represent a step forward in the early diagnosis of small-cell lung carcinoma itself.

Iron-induced oxidant stress leads to irreversible mitochondrial dysfunctions and fibrosis in the liver of chronic iron-dosed gerbils. The effect of silybin.

Hepatic iron toxicity because of iron overload seems to be mediated by lipid peroxidation of biological membranes and the associated organelle dysfunctions. However, the basic mechanisms underlying this process in vivo are still little understood. Gerbils were dosed with weekly injections of iron-dextran alone or in combination with sylibin, a well-known antioxidant, by gavage for 8 weeks. A strict correlation was found between lipid peroxidation and the level of desferrioxamine chelatable iron pool. A consequent derangement in the mitochondrial energy-transducing capability, resulting from a reduction in the respiratory chain enzyme activities, occurred. These irreversible oxidative anomalies brought about a dramatic drop in tissue ATP level. The mitochondrial oxidative derangement was associated with the development of fibrosis in the hepatic tissue. Silybin administration significantly reduced both functional anomalies and the fibrotic process by chelating desferrioxamine chelatable iron.

Circulating pro- and antioxidant factors in iron and porphyrin metabolism disorders.

BACKGROUND: Porphyria cutanea tarda and haemochromatosis are taken to be spontaneous human models of oxidative cellular damage, with an increased risk of fibrosis and cancer evolution. AIM: To define the relative pro-oxidant roles of porphyrin and iron, in their different molecular forms, and their effects on antioxidant biological systems. PATIENTS: A group of 17 patients with porphyria cutanea tarda and a group of 14 patients with primary and secondary haemochromatosis, were compared with 21 healthy controls. METHODS: Plasma retinol, tocopherol, alpha- and beta-carotene, ascorbic acid, glutathione, malonyldialdehyde and red blood cell free iron were determined using high performance liquid chromatography. RESULTS: Only a modest increase in iron stores was demonstrated in the porphyria cutanea tarda group; in the haemochromatosis patients ferritin levels were almost seven times higher. By contrast, there was a sharp and virtually identical increase in red blood cell free iron and malonyldialdehyde in both the patient groups. A significant reduction was observed in retinol, alpha-, beta-carotene and red blood cell glutathione levels being more marked in porphyria cutanea tarda than in haemochromatosis patients. CONCLUSIONS: The study confirms the strong pro-oxidant effects of porphyrins in vivo, through an induction of the free toxic iron form, even though the total iron pool is not greatly expanded. The additional free-iron and porphyrin oxidant effects are documented both in red blood cell and plasma in the porphyria cutanea tarda group. It confirmed that aging exerts a negative influence in terms of pro- and antioxidant balance in all cases, but particularly in the haemochromatosis group.

Metabolism and trafficking of N-type voltage-operated calcium channels in neurosecretory cells.

The N-type voltage-operated calcium channel has been characterized over the years as a high-threshold channel, with variable inactivation kinetics, and a unique ability to bind with high affinity and specificity omega-conotoxin GVIA and related toxins. This channel is particularly expressed in some neurons and endocrine cells, where it participates in several calcium-dependent processes, including secretion. Omega-conotoxin GVIA was instrumental not only for the biophysical and pharmacological characterization of N-type channels but also for the development of in vitro assays for studying N-type VOCC subcellular localization, biosynthesis, turnover, as well as short-and long-term regulation of its expression. We here summarize our studies on N-type VOCC expression in neurosecretory cells, with a major emphasis on recent data demonstrating the presence of N-type channels in intracellular secretory organelles and their recruitment to the cell surface during regulated exocytosis.

Membrane potential of hepatic mitochondria after acute cocaine administration in rats--the role of mitochondrial reduced glutathione.

Cocaine hepatotoxicity may be mediated by oxidative damage, possibly involving mitochondrial injury. The effect of an acute dose of cocaine in rats on the mitochondrial level of reduced glutathione, nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADPH), important determinants in cellular defense against oxidative stress, was investigated. Under these conditions, the extent of lipid peroxidation was assessed as thiobarbituric acid reactive substances formation and the energy transducing capability of the inner mitochondrial membrane was evaluated by membrane potential measurements. Female Wistar albino rats were given an acute 50 mg/kg intraperitoneal dose of cocaine and, 6 hours later, hepatic and mitochondrial biochemical analyses were made. Rats administered intraperitoneally, 7.5 hours before the sacrifice, a specific inhibitor of glutathione synthesis, L-buthionine-(S,R)-sulphoximine, either alone or in combination with cocaine, underwent in parallel the same determinations. Cocaine intoxication did not impair mitochondrial functions, although a significant increase of lipid peroxidation occurred. By contrast the combination of L-buthionine-(S,R)-sulphoximine with cocaine induced a severe derangement of mitochondrial functional efficiency, a large depletion of reduced glutathione, and a further enhancement of lipid peroxidation. The mitochondrial functional anomalies were largely restored by the use of cyclosporin A, ethyleneglycotetraacetic acid (EGTA) and glutathione methylmonoester. A nonspecific calcium dependent inner membrane permeabilty transition (pore opening) accounted for the partial loss of mitochondrial coupled functions at a period of cocaine intoxication when no cell damage occurred. The level of mitochondrial glutathione played a critical role in protecting inner membrane functional integrity against cocaine-induced oxidative stress.

'Free' iron, as detected by electron paramagnetic resonance spectroscopy, increases unequally in different tissues during dietary iron overload in the rat.

'Free' iron concentration, as determined by electron paramagnetic resonance (EPR) spectroscopy, and lipid peroxidation (LPO), as determined by thiobarbituric acid test, were assessed in the lung, heart, liver, spleen, brain and kidney of rats subjected to experimental iron overload. Two tests, Desferal- and NO-available iron, were used to measure 'free' iron and gave comparable results. The most pronounced accumulation of 'free' iron was observed in liver, kidney and spleen. Differences between control and iron loaded animals increased during the initial 90 days of treatment. Between 90 and 180 days 'free' iron concentration reached a steady state level, or even decreased, as in the case of liver. Lipid peroxidation level, measured in the organs of both treated and matched controls, did not give any significant difference during the initial 90 days of treatment. A significant augmentation was observed in liver, kidney, spleen and heart at 180 days. The results of the present research show that, under conditions of moderate siderosis, the occurrence of LPO is partially related to the level of 'free' iron.

Antioxidant activity of silybin in vivo during long-term iron overload in rats.

BACKGROUND & AIMS: Hepatic iron toxicity may be mediated by free radical species and lipid peroxidation of biological membranes. The antioxidant property of silybin, a main constituent of natural flavonoids, was investigated in vivo during experimental iron overload. METHODS: Rats were fed a 2.5% carbonyl-iron diet and 100 mg.kg body wt-1.day-1 silybin for 4 months and were assayed for accumulation of hepatic lipid peroxidation by-products by immunocytochemistry, mitochondrial energy-dependent functions, and mitochondrial malondialdehyde content. RESULTS: Iron overload caused a dramatic accumulation of malondialdehyde-protein adducts into iron-filled periportal hepatocytes that was decreased appreciably by silybin treatment. The same beneficial effect of silybin was found on the iron-induced accumulation of malondialdehyde in mitochondria. As to the liver functional efficiency, mitochondrial energy wasting and tissue adenosine triphosphate depletion induced by iron overload were successfully counteracted by silybin. CONCLUSIONS: Oral administration of silybin protects against iron-induced hepatic toxicity in vivo. This effect seems to be caused by the prominent antioxidant activity of this compound.

Relationship between free iron level and rat liver mitochondrial dysfunction in experimental dietary iron overload.

The concentration of total iron in the hepatic tissue and mitochondria from rats fed a 2.5% carbonyl iron supplemented diet progressively increased up to 40 days, then reached nearly a steady-state. By contrast the level of free iron (desferrioxamine-chelatable) exhibited a transient but significant increase at 40 days of treatment, only in this period of treatment the induction of lipid peroxidation and the resulting mitochondrial abnormalities in calcium transport was observed too. The enhancement of the energy dissipating mitochondrial calcium cycling was found to be associated with a significant decrease of endogenous mitochondrial ATP content. As to the pathophysiological mechanism for hepatocellular injury in iron overload, these results indicated that the transit pool of free iron may play a critical role in initiating organelle dysfunctions, at least in this experimental model of iron overload.

Lipid hydroperoxide induced mitochondrial dysfunction following acute ethanol intoxication in rats. The critical role for mitochondrial reduced glutathione.

It has been found that acute ethanol (EtOH) intoxication of rats caused depletion of mitochondrial reduced glutathione (GSH) of approximately 40%. A GSH reduction of similar extent was also observed after the administration to rats of buthionine sulphoximine (BSO), a specific inhibitor of GSH synthesis. Combined treatment with BSO plus EtOH further decreased mitochondrial GSH up to 70% in comparison to control. Normal functional efficiency was encountered in BSO-treated mitochondria, as evaluated by membrane potential measurements during a complete cycle of phosphorylation. In contrast a partial loss of coupled functions occurred in mitochondria from EtOH- and BSO plus EtOH-treated rats. The presence in the incubation system of either GSH methyl monoester (GSH-EE), which normalizes GSH levels, or of EGTA, which chelates the available Ca2+, partially restores the mitochondrial phosphorylative efficiency. Following EtOH and BSO plus EtOH intoxication, the presence of fatty-acid-conjugated diene hydroperoxides, such as octadecadienoic acid hydroperoxide (HPODE), was detected in the mitochondrial membrane. Exogenous HPODE, when added to BSO-treated mitochondria, induced, in a concentration-dependent system, membrane potential derangement. The presence of either GSH-EE or EGTA fully prevented a drop in membrane potential. The results obtained suggest that fatty acid hydroperoxides, endogenously formed during EtOH metabolism, brought about non-specific permeability changes in the mitochondrial inner membrane whose extent was strictly dependent on the level of mitochondrial GSH.

Fur (ferric uptake regulation) protein and CAP (catabolite-activator protein) modulate transcription of fur gene in Escherichia coli.

A fusion between the fur (ferric uptake regulation) gene, known to mediate negative regulation of iron absorption in Escherichia coli, and lacZ was constructed in vitro. beta-Galactosidase levels of cells harboring this fusion were under the control of sequences contained in a 185-bp DNA fragment located upstream of the fur structural gene. The fusion was prepared in multicopy (pVLN102 plasmid) and low-copy-number states, the latter constructed as a lambda phage lysogen carrying a fur'-'lacZ insert. DNase I footprinting experiments with purified Fur protein, performed on a 250-bp restriction fragment carrying the promoter region of the fusion, showed the presence of a single Fur-protected site overlapping the -10 region of a potential promoter sequence. Examination of the DNA sequences located upstream of the fur gene revealed a possible binding site for the catabolite-activator protein (CAP). beta-Galactosidase synthesis of E. coli cells harboring the fusion were measured in fur, crp and cya genetic backgrounds and compared with the corresponding levels in wild-type strains. The data obtained indicate a moderate autoregulation of fur expression by its gene product and also a significant stimulation by the cAMP-CAP system. Transcription start sites were mapped by primer-extension experiments with total RNA obtained in vivo from cells harboring pVLN102. The results show that transcription of the fur gene is initiated from at least two different sites separated by 6 bp, which appear to originate from two overlapping promoters sensitive to catabolic activation.