Anaerobic RSH-dependent tellurite reduction contributes to Escherichia coli tolerance against tellurite.

BACKGROUND: Tellurium is a rare metalloid that exerts high toxicity on cells, especially on bacteria, partly due to reactive oxygen species (ROS) generation. Moreover, it has also been observed that tellurite can target free cell thiols groups (RSH) (i.e. reduced glutathione (GSH)), enhancing the cellular redox imbalance. Additionally, in vitro experiments have suggested that several enzymes can reduce tellurite (IV) to its elemental form (0); where RSH present on their active sites may be responsible for the process. Nevertheless, the mechanisms implemented by bacteria for tellurite reduction and its role in resistance have not been evaluated in vivo. RESULTS: This work shows that tellurite reduction to elemental tellurium is increased under anaerobic conditions in E. coli cells. The in vivo tellurite reduction is related to the intracellular concentration of total RSH, in the presence and absence of oxygen. This metabolization of tellurite directly contributes to the resistance of the bacteria to the oxyanion. CONCLUSIONS: We demonstrated that in vivo tellurite reduction is related to the intracellular thiol concentration, i.e. large availability of cellular RSH groups, results in a more significant reduction of tellurite. Furthermore, we observed that, when the bacterium exhibits less resistance to the oxyanion, a decreased tellurite reduction was seen, affecting the growth fitness. Together, these results let us propose that tellurite reduction and the intracellular RSH content are related to the oxyanion bacterial resistance, this tripartite mechanism in an oxygen-independent anaerobic process.

Retinoic acid synergizes ATO-mediated cytotoxicity by precluding Nrf2 activity in AML cells.

BACKGROUND: Standard therapy for acute promyelocytic leukaemia (APL) includes retinoic acid (all-trans retinoic acid (ATRA)), which promotes differentiation of promyelocytic blasts. Although co-administration of arsenic trioxide (ATO) with ATRA has emerged as an effective option to treat APL, the molecular basis of this effect remains unclear. METHODS: Four leukaemia cancer human models (HL60, THP-1, NBR4 and NBR4-R2 cells) were treated either with ATO alone or ATO plus ATRA. Cancer cell survival was monitored by trypan blue exclusion and DEVDase activity assays. Gene and protein expression changes were assessed by RT-PCR and western blot. RESULTS: ATO induced an antioxidant response characterised by Nrf2 nuclear translocation and enhanced transcription of downstream target genes (that is, HO-1, NQO1, GCLM, ferritin). In cells exposed to ATO plus ATRA, the Nrf2 nuclear translocation was prevented and cytotoxicity was enhanced. HO-1 overexpression reversed partially the cytotoxicity by ATRA-ATO in HL60 cells. The inhibitory effects of ATRA on ATO-mediated responses were not observed in either the ATRA-resistant NB4-R2 cells or in NB4 cells pre-incubated with the RARα antagonist Ro-41-52-53. CONCLUSIONS: The augmented cytotoxicity observed in leukaemia cells following combined ATO-ATRA treatment is likely due to inhibition of Nrf2 activity, thus explaining the efficacy of combined ATO-ATRA treatment in the APL therapy.

Serum oxidative stress is increased in patients with post cholecystectomy bile duct injury.

BACKGROUND: Post-cholecystectomy bile duct injuries are identified by the onset of jaundice as well as elevated bilirubin and alkaline phosphatase levels during the peri-operative period. It is unknown how serum oxidative stress markers are modified in patients with post-cholecystectomy bile duct injuries. OBJECTIVE: To determine serum oxidative stress marker levels (lipid peroxidation by-products, nitrites/nitrates and total antioxidant capacity) in patients with post-cholecystectomy bile duct injuries. PATIENTS AND METHODS: A prospective, transversal and analytical study was designed with two groups. Group 1: 5 healthy volunteer subjects. Group 2: 52 patients with post-cholecystectomy bile duct injuries (43 female and 9 male). An elective bilio-digestive reconstruction was performed at week 8. The serum oxidative stress marker levels were quantified by colorimetric method. RESULTS: Patients with bile duct injuries had a significant increased serum lipid peroxides (malondialdehyde and 4-hydroxy-alkenals) and nitric oxide metabolites (nitrites/nitrates) levels compared to the control group. In contrast, total antioxidant capacity in patients with bile duct injuries remained similar compared to healthy controls. CONCLUSIONS: The results show that oxidative stress is usually associated to bile duct injury.

Anaerobic RSH-dependent tellurite reduction contributes to Escherichia coli tolerance against tellurite

BACKGROUND: Tellurium is a rare metalloid that exerts high toxicity on cells, especially on bacteria, partly due to reactive oxygen species (ROS) generation. Moreover, it has also been observed that tellurite can target free cell thiols groups (RSH) (i.e. reduced glutathione (GSH)), enhancing the cellular redox imbalance. Additionally, in vitro experiments have suggested that several enzymes can reduce tellurite (IV) to its elemental form (0); where RSH present on their active sites may be responsible for the process. Nevertheless, the mechanisms implemented by bacteria for tellurite reduction and its role in resistance have not been evaluated in vivo. RESULTS: This work shows that tellurite reduction to elemental tellurium is increased under anaerobic conditions in E. coli cells. The in vivo tellurite reduction is related to the intracellular concentration of total RSH, in the presence and absence of oxygen. This metabolization of tellurite directly contributes to the resistance of the bacteria to the oxyanion. CONCLUSIONS: We demonstrated that in vivo tellurite reduction is related to the intracellular thiol concentration, i.e. large availability of cellular RSH groups, results in a more significant reduction of tellurite. Furthermore, we observed that, when the bacterium exhibits less resistance to the oxyanion, a decreased tellurite reduction was seen, affecting the growth fitness. Together, these results let us propose that tellurite reduction and the intracellular RSH content are related to the oxyanion bacterial resistance, this tripartite mechanism in an oxygen independent anaerobic process.

Protective effect of quercetin on experimental chronic cadmium nephrotoxicity in rats is based on its antioxidant properties.

Oxidative stress can play a key role in Cd-induced dysfunctions. Quercetin is a potent oxygen free radicals scavenger and a metal chelator. Our aim was to study the effect of quercetin on Cd-induced kidney damage and oxidative stress as well as its mechanism of action. Wistar rats were distributed in four experimental groups: control rats; Cd; quercetin and Cd+quercetin. Renal toxicity was evaluated by measuring urinary excretion of proteins, albumin, glucose and enzymes markers of tubular necrosis, as well as plasma concentration of creatinine. Plasma TBARS concentration and activity of antioxidant enzymes in kidney were also measured. Renal cell damage was assessed by electron microscopy. Animals that received both Cd and quercetin showed a better renal function than those receiving Cd alone. Cd-induced tubular lesions were markedly reduced in rats that also received quercetin. Cd-induced increase in plasma TBARS was prevented by the administration of quercetin. Total plasma antioxidants and renal superoxide dismutase and glutathione-reductase activities were higher in the group that received Cd and quercetin than in rats that received Cd alone. Quercetin administration does not modify the renal content or the urinary excretion of Cd. In conclusion, quercetin treatment prevents renal tubular damage and increased oxidative stress induced by chronic Cd administration, most probably throughout its antioxidant properties.

Escherichia coli 6-phosphogluconate dehydrogenase aids in tellurite resistance by reducing the toxicant in a NADPH-dependent manner.

Exposure to the tellurium oxyanion tellurite (TeO3(2-)) results in the establishment of an oxidative stress status in most microorganisms. Usually, bacteria growing in the presence of the toxicant turn black because of the reduction of tellurite (Te(4+)) to the less-toxic elemental tellurium (Te(0)). In vitro, at least part of tellurite reduction occurs enzymatically in a nicotinamide dinucleotide-dependent reaction. In this work, we show that TeO3(2-) reduction by crude extracts of Escherichia coli overexpressing the zwf gene (encoding glucose-6-phosphate dehydrogenase) takes place preferentially in the presence of NADPH instead of NADH. The enzyme responsible for toxicant reduction was identified as 6-phosphogluconate dehydrogenase (Gnd). The gnd gene showed a subtle induction at short times after toxicant exposure while strains lacking gnd were more susceptible to the toxicant. These results suggest that both NADPH-generating enzymes from the pentose phosphate shunt may be involved in tellurite detoxification and resistance in E. coli.

Effect of electron beam irradiation on color and microbial bioburden of red paprika.

The effect of irradiation with electron beams on the microbiological quality and color properties of red paprika was examined. The irradiation doses ranged from 0 to 12.5 kGy. The counts performed were total mesophilic aerobic microorganisms, Enterobacteriaceae, coliforms, sulfite-reducing clostridia, molds, and yeasts. It was concluded that molds, yeasts, and sulfite-reducing clostridia were the most resistant species, although a 10-kGy dose of irradiation leads to optimum sanitation. Extractable color and apparent color were analyzed to appraise the incidence of the irradiation treatments in the color properties of red paprika. Extractable color was determined according to the American Spice Trade Association method, and apparent color was analyzed by reflectance using the CIELab color space. Data showed no significant differences between the color properties of irradiated and nonirradiated samples. Irradiation was a suitable procedure to minimize the bioburden of red paprika with small modifications of its color properties.

[The use of antithrombotic drugs in patients with chronic atrial fibrillation in a local health area]. / Utilización de fármacos antitrombóticos en pacientes con fibrilación auricular crónica en un área sanitaria comarcal.

BACKGROUND: The objective of the study is to assess the degree of ambulatory use of prophylactic antithrombotic therapy in patients with chronic atrial fibrillation (CAF) in a county health area. PATIENTS AND METHODS: A cross-sectional, prospective survey carried out in patients admitted at a community-hospital, detected 44 patients with CAF. RESULTS: The inappropriateness of anti-thrombotic therapy (48%) was associated with no having a previous echocardiography (p < 0.004), not being controlled in a hospital (p < 0.02) and in patients without information on the cardioembolic risks (p < 0.0007). CONCLUSIONS: The antithrombotic prophylaxis is scarcely used in patients affected by CAF in the county health area studied.

[Prognostic index in wound infection and abdominal sepsis]. / Indice pronóstico en infección de heridas y sepsis abdominal.

OBJECTIVE: To establish an abdominal surgical infection prognostic index with all risk factors. SUMMARY BACKGROUND DATA: Individuals, requiring abdominal surgery have an established surgical infection risk of 1% and this risk increases with several factors, such as age over 50 years, (4%), diabetes mellitus (12%), obesity (8%), hospitalization up to 10 days (4%), bad nutrition (2%), surgical time up to 3 h (6%) summer (4%) shock (6%) immunosuppression (6%), contaminated surgery (from 1%-40%), or emergency surgery (4%). METHOD: We reviewed 199 patients and investigated previous disease, total white blood cells, oxygen saturation, albumin, body weight, type of surgery performed in regard to contamination, surgical time, hospitalization time, preoperative hair removal previous to surgery, presence of emergency surgery, and prevalence of remote site infections at time of surgery. All these parameters were reviewed for 48 h before and after the surgical procedure and every risk factor acquired a number with respect to the established risk in the world literature. An index called Prognostic index of surgical infections (PISI) was performed, made up of the addition of risk factors. Every patient was observed 10 days after the surgical procedure searching for abdominal or wound infection and correlating the index with the presence of surgical infection. RESULTS: Patients with a prognostic index of 12 or less did not show infections in any case; those with an index of 13 to 15 points had 30% of risk infection, 16 to 18 obtained 70%, 19 to 21 acquired 90%, and 22 or more obtained 100% of surgical risk infection. Sensitivity was 100% and specificity, nearby 75%. CONCLUSIONS: PISI is a reliable indicator of surgical infection risk because it takes into account all factors that cause troubles in the patients, and has high sensitivity and very good specificity.

[Comparative study of soft diet or clear liquids in the resumption of oral intake in the postoperative period]. / Análisis comparativo entre reinstalar la vía oral en el postoperatorio con dieta blanda o líquidos claros.

BACKGROUND: The reinstitution of oral intake in patients who have undergone intraabdominal surgery has traditionally progressed in a stepwise fashion beginning with clear liquids, liquid diet and after an adequate tolerance regular diet. OBJECTIVE: To determine if the reinstitution of oral intake after major abdominal surgery with regular diet offers benefits into which it's not harmful for patients and reduce the in-hospital stay. TYPE OF STUDY: Prospective, randomized, open study conducted between October 1996 to May 1997. MATERIAL AND METHODS: Patients aged 18 and older submitted to elective or urgent surgery of the abdomen and pelvis were included with the exception of: bariatric surgery, esophageal resection, pyloroplasty, pancreato-duodenal resection, laparoscopic surgery and patients under ventilatory support or with enteral or parenteral nutrition. As soon as postoperative ileus disappeared patients were randomly assigned to receive regular diet (group 1) or clear liquids (group 2) as the first oral intake. Oral diet tolerance was evaluated as well as the caloric and protein intake, the in-hospital stay and the cost. RESULTS AND MEASUREMENTS: Group 1 was conformed by 63 patients, and group 2 for 69 patients. There was no difference between, sex, age, kind of surgery (elective or emergency) and the type of pathology. 96.6% of patients in group 1 tolerated regular diet and 96.9% of patients in group 2 tolerated clear liquids. Only two patients of each group required oral intake suspension. The in-hospital stay was 2.6 +/- 2.0 days in group 1 against 3.4 +/- 2.6 in group 2 (P = < 0.005), the cost of the in-hospital stay period after the beginning of oral intake was 2726 +/- 2107 pesos in group 1 against 3547 +/- 2690 in group 2 (P = < 0.005), the caloric and protein intake were 1307 +/- 523 Kcals with 55.9 +/- 23.2 grams of proteins in group 1 and 651 +/- 204 Kcals and 0 grams of proteins in group 2 (P = < 0.00001). CONCLUSIONS: No difference was found in adverse reactions with the use of regular diet as the first meal. The in-hospital stay and the cost were reduced significantly and the calories and grams of proteins are higher in group 1. These results suggest that the routine use of clear liquids as the initial postoperative diet may be unnecessary and nutritionally suboptimal when compared with regular diet.

[Hartmann's procedure. Institutional experience with 92 consecutive cases]. / Operación de Hartmann. Experiencia institucional de 92 casos consecutivos.

BACKGROUND: Since it's description in 1923, Hartmann's procedure is widely used for the surgical treatment of acute left colonic complications when preoperative bowel lavage is not feasible and/or there is high risk of anastomotic dehiscence. OBJECTIVE: Analyze the results of Hartmann's operation in the surgical treatment of consecutive patients at a single institution during a 30-month interval. TYPE OF STUDY: Prospective, non-randomized and longitudinal study. MATERIAL AND METHODS: Patients treated with the Hartmann procedure between March 1995 and September 1998. Surgical indication, intraoperative findings, morbidity and mortality were analyzed as well as the rate of reestablishment of bowel continuity and it's morbimortality. RESULTS: Ninety-two patients underwent a Hartmann procedure. The mean patient's age was 60 +/- 25 years (range of 21 to 88 years) and 60% were older than 65 years. An emergency operation was carried out in 91% of the cases. Most of the patients had intra-abdominal sepsis (56%) and benign colonic process (83%). The morbidity rate was 34% and mortality rate 19. During follow-up the bowel continuity was reestablished in 32% of the cases without fatalities. CONCLUSIONS: Hartmann's procedure is a good option for non-elective surgical treatment complicated rectosigmoid pathology. The morbidity and mortality of the operation are highly dependent on the degree of preoperative sepsis and the patient's preexisting condition. The rate of reestablishment of bowel continuity was low probably because of short follow-up.

Interferon effects upon fluorouracil metabolism by HL-60 cells.

In order to better understand the synergistic antiproliferative effects of interferon in combination with fluorouracil (FUra), we studied effects of alpha 2-interferon upon FUra induced inhibition of thymidylate synthase of HL-60 cells. The 50% inhibitory dose for FUra decreased from approximately 75 microM to 10 microM following interferon treatment, as measured by whole cell activity assays. Enhanced FUra inhibition of cytosolic [3H] - FdUMP binding of interferon treated cells was also noted. FdUMP accumulation following FUra treatment increased over 10 fold in interferon treated cells, but dUMP did not increase. These results suggest that interferon can sensitize cells to FUra inhibition of thymidylate synthase by enhancing accumulation of FdUMP.

[Symptoms related to the use of agricultural pesticides. The perspective from the primary care service]. / Síntomas relacionados con el uso de plaguicidas agrícolas. La perspectiva desde la consulta de atención primaria.

OBJECTIVE: To find whether agricultural workers seen in the general medical clinic attend due to symptoms connected with the use of pesticides. DESIGN: A crossover descriptive study comparing agricultural workers with a control group. SETTING: Primary care. PARTICIPANTS: The clinical histories of 40 agricultural workers and a control group (sample of 58 paired for age and gender) who had been seen over the previous year. MEASUREMENTS AND MAIN RESULTS: Age, gender, frequency of attendance, motives for consultation, risk factors and the number of consultations for symptoms possibly due to exposure to pesticides--in line with a previously composed list. There were no differences in frequency of attendance, overall reasons for consultation or risk factors. It was seen that agricultural workers consulted 4 times more than the control group for suspected pesticide poisoning (p = 0.0015). CONCLUSIONS: In our health area agricultural workers present symptoms which should probably be attributed to insufficient protection against pesticides. The primary care doctor working in rural zones where these products are heavily used must be able to identify these symptoms and take appropriate measures.

[Description of the habits of agricultural workers in relation to the applying of pesticides]. / Descripción de los hábitos de los agricultores en relación con la aplicación de plaguicidas.

OBJECTIVES: To find the habits of farm-workers when they apply these products, to detect dangerous practices, to find the most important defects in farm-workers' protection and to analyse the personal variables associated with the level of self-protection. DESIGN: Descriptive cross-sectional study. SETTING: Primary Care. Rural Health Centre. PARTICIPANTS: Farm-workers and spouses in our Health Area who underwent a health examination. MEASUREMENTS AND MAIN RESULTS: A questionnaire was designed specifically for the study and filled out by the doctor or nurse at the centre where the person interviewed was registered. 72.8% of the farm-workers had inadequate protection. 79.3% said they had suffered on some occasion symptoms related to pesticide use. CONCLUSIONS: In the rural health areas where there is intensive agriculture, exposure to pesticides is a major health problem, as these substances are hazardous and people applying them wear inadequate protection. Action strategies in this field involve integrating health at work services into health centres. Health education tasks have to be coordinated with the agricultural organisations in the area, such as associations for the defense of plants, cooperatives, etc.

Endometriosis apendicular. Informe de un caso. / Apendicceal endometriosis.Report of a case

La endometriosis apendicular tiene una frecuencia menor de 1 por ciento de las endometriosis pelvicas. Su diagnostico en la mayor parte de las ocasiones es incidental. Se informa un caso de endometriosis apendicular en una mujer en la cuarta decada de la vida, con antecedentes de esterilidad primaria, que ingreso con cuadro doloroso abdominal en cuadrante inferior derecho sin otros datos clinicos, radiologicos e do laboratorio que sugirieran el diagnostico. Se intervino con diagnostico preoperatorio de apendicitis aguda y se el realizo apendicectomia. El estudio histopatologico demostro focos endometrioides en la serosa apendicular sin datos de apendicitis aguda. La endometriosis debe considerarse entre las posibilidades diagnosticas en mujeres con cuadros "apendiculares" en los dias premenstruales y menstruales