Cleaner production and methodological proposal of eco-efficiency measurement in a Mexican petrochemical complex

Abstract In the frame of the Petróleos Mexicanos Institutional Program for Sustainable Development, processes were evaluated in the manufacture operation of the petrochemical industry, with the purpose of reducing their ecological fingerprint. Thirteen cleaner production opportunities were registered in six process plants: ethylene oxide and glycols, acetaldehyde, ethylene, high density polyethylene, polypropylene switch and acrylonitrile, and 45 recommendations in the waste water treatment plant. Morelos is the second most important petrochemical complex in the Mexican and Latin American petrochemical industry. A tool was developed to obtain eco-efficiency indicators in operation processes, and as a result, potential savings were obtained based on best performance, as well as the integrated distribution of Sankey diagrams. Likewise, a mechanism of calculation to obtain economic savings based on the reduction of residues during the whole productive process is proposed. These improvement opportunities and recommendations will result in economic and environmental benefits minimising the use of water, efficient use of energy, raw materials and reducing residues from source, generating less environmental impacts during the process.

Ca 15.3 in breast cancer: comparison of two assays and validation in a Mexican population

Ca 15.3 is a tumor marker used for breast carcinoma, since one epitope is an antigen present in milk fat globules. Serum from 171 patients with breast cancer upon initial presentation was studied for Ca 15.3. In the first 72 cases, the authors compared RIA vs. ELISA using a simple linear regression. On the following 99, only ELISA was performed. With all 171 patients, a clinical association between Ca 15.3 measurement and age, stage and hormone receptors was carried out. Correlation coefficient between RIA and ELISA was 0.85. Of 104 patients below 50 years of age, 88 had normal Ca 15.3 and 16, elevated; 67 were older than 50 years, 46 had normal Ca 15.3 and 21, elevated (p=0.022). Ca 15.3 was elevated in 11% of patients with clinical stages I/II, and 89% in stages III/IV (p=0.0001). The association of Ca 15.3 with hormone receptors was not significant. In conclusion, ELISA and RIA measure Ca 15.3 with comparable results, the first method has the advantage of not using radioactivity. The authors found higher probability of elevated Ca 15.3 in older patients and in those with advanced disease.

Amphotericin B kills unicellular leishmanias by forming aqueous pores permeable to small cations and anions

The polyene antibiotic amphotericin B (AmB) is known to form two types of ionic channels across sterol-containing liposomes, depending on its concentration and time after mixing (Cohen, 1992). In the present study, it is shown that AmB only kills unicellular Leishmania promastigotes (LPs) when aqueous pores permeable to small cations and anions are formed. Changes of membrane potential across ergosterol-containing liposomes and LPs were followed by fluorescence changes of 3,3' dipropylthiadicarbocyanine (DiSC3(5)). In KCl-loaded liposomes suspended in an iso-osmotic sucrose solution, low AmB concentrations (</=0.1 microM) induced a polarization potential, indicating K+ leakage, but no movement of cations and anions was allowed until AmB concentrations greater than 0.1 microM were added. In agreement with these data, it was found that AmB altered the negative membrane potential held across LPs in a manner consistent with the differential cation/anion selectivity exhibited by the channels formed in liposomes. Thus, LPs suspended in an iso-osmotic sucrose solution did not exhibit any AmB-induced membrane depolarization effect brought about by efflux of anions until 0.1 microM or higher AmB concentrations were added. By contrast, LPs suspended in an iso-osmotic NaCl solution and exposed to 0.05 microM AmB exhibited a nearly total collapse of the negative membrane potential, indicating Na+ entry into the cells. The concentration dependence of the AmB-induced permeability to different salts was also measured across vesicles derived from the plasma membrane of leishmanias (LMVs), by using a rapid mixing technique. At concentrations above 0.1 microM, AmB induced the formation of aqueous pores across LMVs with a positive cooperativity, yielding Hill coefficients between 2 to 3. Measured anion selectivity across such aqueous pores followed the sequence: SCN > NO3 > Cl > I > Br > acetate (SO2-4 being impermeable). Cell killing by AmB was followed by fluorescence changes of the DNA-binding compound ethidium bromide (EB). At low concentrations (</=0.1 microM), AmB was found to be nonlethal against LPs but, above this concentration, leishmanias were rapidly killed. The rate and extent of such an effect were found to be dependent on the type of cation and anion present in the external aqueous solution. For both NH+4 and Na+ salts, the measured rank order of AmB cell killing followed the same sequence that was determined for AmB-induced salt permeation across LMVs. Further, replacement of either extracellular Na+ by choline or Cl- by SO2-4, or its partial substitution by sucrose, in iso-osmotic conditions, led to a complete inhibition of the killing effect exerted by otherwise lethal AmB concentrations. Finally, it was shown that tetraethylammonium (TEA+), an organic cation that is known to block AmB-induced salt permeation across LMVs was able to retard the time lag observed for EB incorporation across LPs, indicating that this parameter can be taken to represent the time taken for salt accumulation inside the parasites. The present results thus indicate clearly that low AmB concentrations (</=0.1 microM) were able to form across LPs, cation channels that collapsed the parasite membrane potential but are not lytic. At high concentrations (>/=0.1 microM), a salt influx via the aqueous pores formed by the antibiotic was followed by osmotic changes leading to cell lysis. This last stage is supported by electron microscopy observations of the changes of parasite morphology immediately upon addition of AmB, which indicated that the typical elongated promastigote cell forms became rounded and the flagella swells and round up. The present work is the first demonstration of the in vitro sensitivity of Leishmania promastigotes to osmotic lysis by AmB.

Filling pressures in post-myocardial infarction patients: comparison between isometric and dynamic exercise

The purpose of this study was to determine if isometric exercise (handgrip) using a substantial muscle mass and intensity could be substituted for dynamic exercise in the assessment of left ventricular function in myocardial infarct (MI) patients. Forty patients with documented MI were assigned, on the basis of their previous exercise ECG responses, to either an exercise-induced ischaemic group (Group 1) or to a non-exercise ischaemic group (Group 2). Eight apparently healthy males served as controls. Pulmonary capillary pressure (PCP) was measured at rest, during volume loading and during isometric and dynamic exercise. Mean PCP in Group 1 increased progressively from 7.5 +/- 2.9 mmHg at rest, to 11.6 +/- 3.8 mmHg during volume loading, to 18.8 +/- 10.2 mmHg during the isometric exercise and to 25.2 +/- 10.1 mmHg during the dynamic exercises. For Group 2, the respective values were 9.6 +/- 6.3, 13.1 +/- 6.4, 18.7 +/- 13.7 and 18.4 +/- 9.8 and for the controls 8.9 +/- 1.9, 11.3 +/- 1.2, 13.3 +/- 3.3 and 11.8 +/- 3.6 mmHg. The results of this study indicate that isometric exercise of 50% MVC using both hands can adequately replace dynamic exercise in the diagnosis of left ventricular function in post MI patients.

[Left ventricular function assessment using a floating catheter in dynamic and isometric (handgrip) stress in normal and heart infarct patients]

Left ventricular function was examined in a control group of 8 healthy men (average age 26 +/- 6.2 years) and was compared to 40 post-MI patients (average age 50 +/- 8.2 years, 39 men, one woman). It was measured using the floating-catheter technique under isometric exercise (50% of maximal voluntary contraction using both hands) and also under dynamic exercise (progressive supine bicycle-ergometry). In the control group, there was a significant increase in heart rate, arterial blood-pressure and the average PCP from rest to isometric exercises. PCP was noted to stay within its normal range (less than 20 mm Hg) under both modes of exercise. There was no significant difference comparing the effects of dynamic and isometric exercise (isometric: PCP 13.3 +/- 3.3 mm Hg; dynamic: PCP 11.8 +/- 3.6 mm Hg). In Group I (20 post-MI-patients showing ischemia during exercise-ECG) PCP stayed normal under isometric exercise (PCP 18.8 +/- 10.2 mm Hg). Under dynamic exercise, their PCP increased up to a pathological level (PCP 24.9 +/- 10.1 mm Hg, p less than 0.01). In Group II (20 post-MI-patients with lacking proof of ischemia during exercise-ECG) there was no significant difference between the increase in PCP under isometric vs dynamic exercise (isometric: PCP 18.7 +/- 13.4 mm Hg; dynamic: PCP 18.5 +/- 10.0 mm Hg).

CONCLUSION

The results lead to the conclusion that isometric exercise alone (50% of maximal voluntary contraction using both hands, handgrip) can replace dynamic exercise in the diagnosis of LV malfunction in post-MI patients who do not show ischemia during exercise-ECG.