Role of putrescine in cell proliferation in a colon carcinoma cell line

OBJECTIVES: Putrescine, the precursor for higher polyamine biosynthesis, is necessary for cell growth in mammals. Ornithine decarboxylase (ODC) activity and polyamine production are increased in neoplastic cells. Using colon cancer cell line derived from a tumor with high metastatic potential (CT-26), our objective was to study the effect of exogenous putrescine on ODC regulation, polyamine metabolism, and cell proliferation. METHODS: Cells cultured with fetal calf serum were exposed to 100, 550, and 1000 microM putrescine for 24 h. RESULTS: Intracellular free putrescine, determined by high-performance liquid chromatography, showed a statistically significant increase in exposed cells compared with controls and a significant correlation with levels of the metabolite present in the medium (r = 0.93; P < 0.001). Bromodeoxyuridine incorporation into newly synthesized DNA, a marker of cell proliferation, showed a statistically significant increase in the three putrescine groups as opposed to the control group. In samples with added aminoguanidine, significant increases in DNA synthesis were observed in the 550- and 1000-microM putrescine groups as opposed to the control group. Spermidine and spermine intracellular contents in all three putrescine-treated groups remained below control levels. No statistical differences in ODC enzymatic activity or ODC mRNA content were observed. Newly incorporated putrescine stimulated colon tumor cell growth. CONCLUSIONS: Because neither enhanced conversion into the higher polyamines nor aminoguanidine inhibition of proliferation was observed, we suggest that this effect can be attributed to the putrescine molecule itself.     

Comparison of clinical and environmental samples of Legionella pneumophila at the nucleotide sequence level

Legionella pneumophila serogroup 1 is the most common etiological agent of legionellosis. We have used clinical and environmental isolates from different sources to compare their genetic variability. We have obtained the nucleotide sequence for six protein-coding loci, included in the SBT scheme for L. pneumophila, and three intergenic regions from 127 samples, 47 of environmental origin and 80 from clinical samples. Levels of genetic variability were found to be higher in the environmental than in the clinical samples, but these did not represent a mere subset of the former. Not a single case of full identity between clinical and environmental isolates was found, which raises the possibility that only a specific subset of environmental isolates is actually capable of producing infection in humans. A phylogenetic analysis of the concatenate alignment of the nine loci sequences showed four main groups, each including clinical and environmental isolates, although their distribution was not uniform among them. The comparison of each individual gene tree with the others revealed several cases of incongruence involving samples from both origins, thus suggesting the presence of recombination in the two groups.     

Paroxetine inhibits acute effects of 3,4-methylenedioxymethamphetamine on the immune system in humans

The effect of pretreatment with paroxetine on cell-mediated immune response and release of cytokines after the administration of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") was investigated in a double-blind, randomized, crossover, controlled clinical trial in which 12 healthy male recreational users of MDMA participated. Subjects received 20 mg/day paroxetine (or placebo) for the 3 days before MDMA challenge (100 mg). Acute MDMA administration produced a time-dependent decrease in CD4 T-helper cells, a decrease in the functional responsiveness of lymphocytes to mitogenic stimulation, a simultaneous increase in natural killer (NK) cells as well as cortisol and prolactin stimulation kinetics. A high increase in the release of anti-inflammatory cytokines (transforming growth factor-beta and interleukin-10) with a simultaneous decrease of anti-inflammatory response (interleukin-2) was also observed. Pretreatment with paroxetine partially reduced MDMA effects on CD4 T and NK cells, whereas totally inhibiting the suppression of the immune response to mitogens and alterations in cytokines release. MDMA-induced alterations in the immune system as well as antagonistic effects mediated by paroxetine show a trend toward baseline levels at 24 h. These findings suggest that acute effects of MDMA on immune system are mainly mediated by its interaction with the serotonin transporter and subsequent serotonin release with a possible participation of other neuroendocrine regulatory systems.     

Pressure sores secondary to immobilization with cervical collar: a complication of acute cervical injury

Cervical collars are essential in the treatment of patients with suspicion or verification of acute cervical spine injury (ACSI). One of the complications of these devices is the development of pressure scores (PS). This study aims to determine its incidence in our unit, the characteristics of patients with ACSI who suffer PS due to the collar and to describe aspects related with these injuries. We include 92 patients with ACSI hospitalized more than 24 hours from January 2002 to December 2003. We analyze demographic variables, incidence, risk factors and characteristics of the PS that develop. The incidence of these lesions was 23.9%. Patients with PS presented: a higher injury severity score (ISS) (37.5 9.8 vs. 31.3 14.9), a greater percentage of catheter carriers of intracraneal pressure (ICP) (55.6% vs. 16.2%), longer time of mechanical ventilation (15.4 8.2 vs. 6.1 9) and longer stays (24.6 10.9 vs. 10 10.3), all statistically significant (p< 0.05). A total of 38 PS were detected, 7 (RI 5-13.8) being the median of the detection day. The chin, occipital and suprascapular zone were the most frequent locations. A total of 42.1% were grade II and 39.5% grade III. The occipital injuries were the most serious and those detected the latest. We conclude that a high index of suspicion of PS due to collar in patients with ACSI, elevated ISS, monitoring of ICP, mechanical ventilation and prolonged stays is required. The occipital zone requires special attention due to the seriousness of the injuries recorded. We suggest a specific multidisciplinary protocol for this problem.     

Rat CCl4‐induced cirrhosis plus total portal vein ligation: a new model for the study of hyperammonaemia and brain oedema

Introduction: Animal models used to study hyperammonaemic disorders related to chronic liver disease are unsatisfactory. These animals only develop hyperammonaemia and brain oedema when fed with diets supplemented with amonium acetate. Aim: To develop a novel experimental model of hyperammonaemia and brain oedema in CCl₄‐induced cirrhosis in rats. Methods: Four groups were studied: rats with sham intervention (S), rats with total portal vein ligation (TPVL), cirrhotic rats (LC), and cirrhotic rats with TPVL (LC+TPVL). When ascites was diagnosed, oral glutamine challenge (OGC) test was performed. Blood, liver, lungs and brain samples were collected to quantify liver function parameters, plasmatic and cerebral ammonia, endotoxaemia, liver and brain histology, brain oedema and portosystemic shunting degree. Results: LC+TPVL rats showed a significant increase in portosystemic shunting when compared with LC group and a significant derangement in liver function when compared with TPVL group. These alterations resulted in a significant increase in plasmatic and brain ammonia concentrations and a higher plasmatic endotoxaemia as compared with others. Similarly, the area under OGC curve was significantly increased in LC+TPVL group as compared with the others, and correlates with portal shunting. Low‐grade brain oedema was only observed in LC+TPVL group. All cirrhotic groups showed liver regeneration nodules and type‐II Alzheimer astrocytes Conclusion: LC+TPVL reproduce the main alterations – portosystemic shunting, plasmatic and cerebral hyperammonaemia and low‐grade brain oedema – observed in cirrhotic patients with hepatic encephalopathy.     

Prevención no farmacológica de la neumonía asociada a ventilación mecánica

Ventilator-associated pneumonia (VAP) is the first cause of mortality due to nosocomial infections in the intensive care unit. Its incidence ranges from 9% to 67% of patients on mechanical ventilation. Risk factors are multiple and are associated with prolonged stays in hospital and intensive care units. Additional costs for each episode of VAP range from 9,000 € to 31,000 €.     

Release profile and transscleral permeation of triamcinolone acetonide loaded nanostructured lipid carriers (TA-NLC): in vitro and ex vivo studies

Nanostructured lipid carriers (NLC) have been developed for sustained release of triamcinolone acetonide (TA), a corticosteroid commonly indicated for macular edema, neovascularization, and other ocular inflammatory disorders. TA-NLC were prepared by high-pressure homogenization and characterized for in vitro release by dialysis bag. Ex vivo permeation profile was assessed using rabbit sclera isolated and mounted in Franz diffusion cells. TA-NLC were placed in episcleral donor compartment and choroidal side was perfused with HEPES buffer. Tissue sections underwent drug wash-out, following analysis by validated RP-HPLC of drug content and perfused fractions collected over 24 hours. Drug release followed one-order kinetics and permeability studies confirmed that TA is able to diffuse across rabbit sclera in sustained profile, following zero-order kinetics. Strong tissue binding was observed, providing a drug depot. These findings are of potential use when designing future TA therapy strategies for ocular diseases of posterior segment.