[Interleukin 18 (IL-18) and other immunological parameters as markers of severity in acute pancreatitis]. / Interleucina-18 (IL-18) y otros parámetros inmunológicos como marcadores de gravedad en la pancreatitis aguda.

OBJECTIVE: Our aim was to prospectively compare the behavior of interleukin 18 (IL-18) levels and other immunological parameters during the first week of hospitalization between acute pancreatitis patients with and without severity criteria, as well as between patients with and without late pseudocyst development. PATIENTS AND METHODS: In 36 patients with acute pancreatis we compared sTNF-RI, IL-1Ra, IL-6, and IL-18 levels at days 1, 2, 3 and 7 after hospitalization between mild pancreatitis, severe pancreatitis, and a "control" group (13 patients) with uncomplicated biliary colic, as well as between patients with and without pseudocyst. RESULTS: On comparing mild to severe pancreatitis, IL-18 was significantly higher only the first day in severe pancreatitis, while the other parameters were steadily higher after the second day. In patients developing pseudocyst, IL-18 was also noticeably higher the first day. CONCLUSIONS: IL-18 appears to be the earliest marker of complications and severity in acute pancreatitis at both the systemic and local level (pseudocyst).

Vitamins C and E prevent AZT-induced leukopenia and loss of cellularity in bone marrow. Studies in mice.

A major limitation in the use of AZT for AIDS treatment is the occurrence of side effects, such as leukopenia. The effects of antioxidant vitamins C and E on AZT-induced leukopenia were investigated in mice. Mice were divided into four groups: (1) controls; (2) AZT-treated; (3) treated with AZT plus vitamins C and E; and (4) pre-treated with vitamins and then treated with AZT plus vitamins. Our results demonstrate that AZT causes leukopenia in mice, which was abrogated by administration of vitamins C and E in the pre-treated group. These vitamins prevented the decrease in cellular content induced by AZT in bone marrow and diminished peroxide levels in myeloid precursors in bone marrow. AZT also caused an increase in plasma malondialdehyde and blood oxidized glutathione levels, which was prevented by the administration of antioxidant vitamins. In conclusion, oxidative stress is involved in AZT-induced leukopenia which may be prevented by antioxidant treatment.

Pulmonary injuries and cytokine levels after the intraperitoneal administration of pancreatic homogenates in rats.

INTRODUCTION: Our objective was to investigate the effects of the administration of pancreatic homogenates, with or without enzymatic activation, to healthy animals regarding cytokine serum levels and the development of pulmonary distress. MATERIAL AND METHODS: 106 male Wistar rats, divided into three groups, were studied: group A, intraperitoneal administration of homogenates activated with enterokinase; group B, homogenates without enterokinase; and group C, control group with administration of physiological saline solution. Each group was divided into 4 subgroups according to the time of sacrifice: 0, 2, 6 and 24 hours. We studied the pulmonary and pancreatic histology, serum parameters of renal and hepatic function, and serum levels of IL-1beta, IL-6 and TNFalpha. RESULTS: There was no mortality in any group. Pancreatic disorders in A and B groups were noted at 24 hours. These two groups had statistically significant higher transaminase serum levels than those of the control group, as well as statistically significant higher creatinine levels in group A. IL-1beta showed a statistically significant higher level at 6 h in both groups, A and B, but was higher in group A, which also exhibited significant pulmonary histologic damage with respect to controls at 6 h. CONCLUSIONS: The higher IL-1beta level in group A may result from production by peritoneal macrophages under the influence of homogenate enzymatic activation. This may be the reason for lung damage.

Lung changes and cytokine levels in a model of experimental acute pancreatitis.

AIM: Prognosis of acute pancreatitis is related mainly to systemic involvement. The establishment of this systemic inflammation is mediated by proinflammatory cytokines. Our aim is to study serum levels of some proinflammatory cytokines and the associated damage of the lung in a model of experimental acute pancreatitis. EXPERIMENTAL DESIGN: Eighty seven male Wistar rats were divided into two groups: group A (control) with saline solution administration; group B with acute pancreatitis induced by intraperitoneal caerulein (50 mg/kg every hour, 4 doses). The animals were killed at 0, 2, 6 and 24 hours of the last dose of caerulein or saline solution. Pancreatic and pulmonary histology were examined, and serum levels of IL-1 beta, TNF-alpha and IL-6 were evaluated, as well as some laboratory parameters as indicators of systemic involvement. RESULTS: The administration of caerulein induced an acute edematous pancreatitis without mortality and with a trend towards resolution in 24 hours. IL-1 beta in animals with acute pancreatitis showed significantly higher levels than in the control group at 6 hours. Serum transaminases, urea and creatinine were also significantly higher at 2 and 6 h. The group with acute pancreatitis showed histological lung damage all over the study. CONCLUSIONS: In our model of acute pancreatitis we observed systemic involvement as judged by alterations of serum transaminases and parameters of renal function, as well as histological lung damage, that correlated with an increase in serum levels of IL-1b.

Zidovudine (AZT) causes an oxidation of mitochondrial DNA in mouse liver.

Zidovudine (3'-azido-2',3'-dideoxythymidine [AZT]) inhibits human immunodeficiency virus replication and delays progression of acquired immune deficiency syndrome. We have recently found that, in muscle, AZT causes oxidative damage to mitochondrial DNA (mtDNA) and other signs of mitochondrial oxidative damage. The aim of this work was to test if AZT causes oxidative damage to liver mtDNA. In our study, an experimental mouse model was used in which mice were administered AZT (10 mg/kg body weight/d) in drinking water. Liver mtDNA of mice treated with AZT had 40% more of the oxidized, mutagenic nucleoside, 8-oxo-7,8-dihydroxy-2'deoxyguanosine (8-oxo-dG) than untreated controls. This oxidative damage to mtDNA is caused by a significant increase (of over 240%) in peroxide production by liver mitochondria from AZT-treated mice, which was prevented by dietary administration with vitamins C and E.

AZT treatment induces molecular and ultrastructural oxidative damage to muscle mitochondria. Prevention by antioxidant vitamins.

AIDS patients who receive zidovudine (AZT) frequently suffer from myopathy. This has been attributed to mitochondrial (mt) damage, and specifically to the loss of mtDNA. This study examines whether AZT causes oxidative damage to DNA in patients and to skeletal muscle mitochondria in mice, and whether this damage may be prevented by supranutritional doses of antioxidant vitamins. Asymptomatic HIV-infected patients treated with AZT have a higher urinary excretion (355+/-100 pmol/kg/d) of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxo-dG) (a marker of oxidative damage to DNA) than untreated controls (asymptomatic HIV-infected patients) (182+/-29 pmol/kg/d). This was prevented (110+/-79 pmol/kg/d) by simultaneous oral treatment with AZT plus antioxidant vitamins (C and E). Mice treated with AZT also had a significantly higher urinary excretion of 8-oxo-dG than controls. Skeletal muscle mtDNA of mice treated with AZT had more 8-oxo-dG than controls. mt lipoperoxidation was also increased and skeletal muscle glutathione was oxidized. These effects may be due to an increased peroxide production by muscle mitochondria of AZT-treated animals. Dietary supplements with vitamins C and E at supranutritional doses protect against oxidative damage to skeletal muscle mitochondria caused by AZT.

Transcription termination downstream of the Saccharomyces cerevisiae FBP1 [changed from FPB1] poly(A) site does not depend on efficient 3'end processing.

Efficient transcription termination downstream of poly(A) sites has been shown to correlate with the strength of an upstream polyadenylation signal and the presence of a polymerase pause site. To further investigate the mechanism linking termination with 3'-end processing, we analyzed the cis-acting elements that contribute to these events in the Saccharomyces cerevisiae FBP1 gene. FBP1 has a complex polyadenylation signal, and at least three efficiency elements must be present for efficient processing. However, not all combinations of these elements are equally effective. This gene also shows a novel organization of sequence elements. A strong positioning element is located upstream, rather than downstream, of the efficiency elements, and functions to select the cleavage site in vitro and in vivo. Transcription run-on analysis indicated that termination occurs within 61 nt past the poly(A) site. Deletion of two UAUAUA-type efficiency elements greatly reduces polyadenylation in vivo and in vitro, but transcription termination is still efficient, implying that FBP1 termination signals may be distinct from those for polyadenylation. Alternatively, assembly of a partial, but nonfunctional, polyadenylation complex on the nascent transcript may be sufficient to cause termination.

Analysis of the structure of a natural alternating d(TA)n sequence in yeast chromatin.

We address here the question of the in vivo structure of a natural alternating d(TA)n sequence found at the 3' region of the Saccharomyces cerevisiae FBP1 gene. This sequence consists of 13 TA pairs interrupted by a TT dinucleotide in the middle of the tract. Previous experiments with cruciform-specific nucleases S1 and Endonuclease VII demonstrated the presence in vitro of a cruciform in this region. We also showed this region to be part of a nuclease hypersensitive site flanked by nucleosomes in yeast chromatin. Here we demonstrate, by means of S1 in vivo footprinting, that in yeast plasmids also adopts in vivo a non B-DNA structure where is not a cruciform. A theoretical analysis of this region that it contains a site susceptible to superhelical stress duplex destabilization. The locations and conditions under which alternative structures form in the wild-type sequence and in deletion mutants agree with these theoretical predictions, suggesting that some kind of denaturation is the alternative structure adopted by the sequence in vivo. This suggests that negative superhelical stress sufficient for local denaturation exists in nucleosomal DNA. We also demonstrate by micrococcal nuclease digestions that the deletion of the alternating d(TA)n sequence modifies the chromatin hypersensitive site but does not affect nucleosome positioning.

Chromatin structure of the yeast FBP1 gene: transcription-dependent changes in the regulatory and coding regions.

We have studied the chromatin structure of the Saccharomyces cerevisiae FBP1 gene, which codes for fructose-1,6-bisphosphatase. A strong, constitutive, DNase I, micrococcal nuclease and S1 nuclease hypersensitive site is present close to the 3' end of the coding region. In the repressed state, positioned nucleosomes exist around this site, and subtle changes occur in this nucleosomal organization upon derepression. A DNase I hypersensitive region is located within the promoter between positions -540 and -400 and its extends towards the gene in the derepressed state, leading to an alteration of nucleosomal positioning. Psoralen crosslinking of chromatin, which is used for the first time to study the mobility of restriction fragments from an RNA polymerase II gene, revealed that part of the promoter is nucleosome-free, in accordance with the results of DNase I digestion. A model is presented that, based on the chromatin structure, puts forward the hypothesis that the promoter UAS is located between -540 and -340. Finally, psoralen crosslinking, as well as digestions with micrococcal nuclease or restriction endonucleases suggests that most if not all of the copies of the active FBP1 gene are covered by nucleosomes.