Synthesis, testing, and characterization of a novel Nafion membrane with superior performance in photoassisted immobilized Fenton catalysis

A new type of Nafion/Fe structured membrane ensuring faster kinetics, higher efficiency, and mechanical properties has been prepared and will be compared in its performance with the Fe-exchanged commercial Dupont 117 Nafion/Fe membrane during the abatement of model organic compounds. During the casting of the laboratory Nafion sample, the iron ions were introduced directly into the Nafion oligomer solution. This novel laboratory Nafion/Fe was tested as an immobilized catalyst in the degradation of several toxic pollutants showing a faster photoassisted degradation kinetics and a wider effective photocatalytic pH range compared to the Fe-exchanged commercial Dupont 117 Nafion/Fe membrane. When carrying out Ar ion sputtering of the 50 topmost catalyst layers, evidence is presented by X-ray photoelectron spectroscopy that Fe ions are found in the inner Nafion layers and seem to be responsible for the immobilized photoassisted Fenton processes leading to the degradation of 4-chorophenol (4-CP) taken as a model organic pollutant for the degradation process reported in this study. In the laboratory sample, the iron oxy/hydroxy Nafion moiety undergoes a transition to a more stable Nafion/Fe species during 4-CP degradation as determined by X-ray diffraction. This more stable form shows a higher iron dispersion and crystallinity compared to the fresh sample and is stabilized by the Nafion matrix avoiding the formation of separate iron phases. By infrared absorption (Fourier transform infrared), evidence is presented for the band of akaganeite-like species at 870 cm(-1) on the laboratory Nafion/Fe sample. This band disappears after 4-CP degradation because of the formation of the more highly dispersed iron species. Sputtering experiments show a decrease of F-containing groups in the laboratory Nafion/Fe samples closer to the catalyst upper layer while the amounts of Fe, C, and in particular O species increase in the topmost layer(s). In particular, the oxygenated species develop in the Nafion/Fe up to approximately 50 A below the catalyst surface. These species remain stable during the long-term Nafion/Fe degradation of 4-CP. Dynamo-mechanical analysis performed on laboratory Nafion/ Fe membrane samples revealed that these membranes possessed a greater mechanical modulus and resistance than the commercial Dupont 117 Nafion membrane.

BOD5 measurements of water presenting inhibitory Cu2+. Implications in using of BOD to evaluate biodegradability of industrial wastewaters

In industrial effluents, the presence of an infinite number of possible mixtures of substances and the high variability of chemical conditions ask for an evaluation of biodegradability by a global and simple method. Biological oxygen demand after five days (BOD5) using synthetic wastewater was studied by two different ways: dilution and manometric methods. It can therefore be established that BOD5 obtained by adding manufactured inocula to the synthetic medium (effluent containing known and easily biodegradable substances) is close to the values obtained with inocula taken from the treated effluent of an urban and a rural purification plant. It was found that BOD5 measurement of effluents presenting factors affecting biodegradation, similar of those found in industrial effluents, is very questionable. The BOD is in this case influenced by the synergic and antagonist interactions between numerous and variable parameters like as pH, nature and concentration of inoculum, concentration of nutriments, amount and nature of assimilable substances, presence of toxicants, and presence of nitrification inhibitors, which are typical of real industrial wastewaters.

Plasmatic homocysteine concentration and its relationship with complications associated to diabetes mellitus

BACKGROUND AND METHODS

In the search for new factors of cardiovascular risk associated to diabetes mellitus (DM), special attention has been paid in recent years to hyperhomocysteinaemia. Therefore, we have established the concentration of homocysteine (Hcy) and other biochemical parameters in the plasma of a group of 57 type 1 and 32 type 2 diabetic patients and 54 control subjects and studied whether plasmatic homocysteinaemia was related to macroangiopathy, nephropathy, retinopathy and neuropathy. Because of significant differences for plasma Hcy values between men and women in the control group, we distinguished between both groups throughout the study.

RESULTS

Patients with DM had higher Hcy than control subjects (11.7+/-5.4 vs. 10.1+/-2.4 micromol/l, p<0.05). Fasting hyperhomocysteinaemia was considered as the mean of the plasma Hcy for control subjects+2 SD (14.9 micromol/l in total group, 15.6 micromol/l in males and 13.9 micromol/l in females). In the studied groups with complications, we found significant differences between normohomocysteinaemic type 1 diabetic patients and those considered hyperhomocysteinaemic by us. On the other hand, patients having type 1 DM and complications had higher plasmatic Hcy concentration than those with no complications.

CONCLUSIONS

We have found a relationship between high Hcy levels and prevalence of macroangiopathy, retinopathy and nephropathy in the type 1 diabetic patients, which was not been observed in the type 2 diabetic patients of our study. As a result, we consider plasmatic Hcy a complication-risk indicator in type 1 DM, and we recommend its use together with already established biochemical parameters in the control of the evolution of the disease.

Reducing infections among women undergoing cesarean section in Colombia by means of continuous quality improvement methods

BACKGROUND

Improving obstetric care in resource-limited countries is a major international health priority.

OBJECTIVE

To reduce infection rates after cesarean section by optimizing systems of obstetric care for low-income women in Colombia by means of quality improvement methods.

METHODS

Multidisciplinary teams in 2 hospitals used simple methods to improve their systems for prescribing and administering perioperative antibiotic prophylaxis. Process indicators were the percentage of women in whom prophylaxis was administered and the percentage of these women in whom it was administered in a timely fashion. The outcome indicator was the surgical site infection rate.

RESULTS

Before improvement, prophylaxis was administered to 71% of women in hospital A; 24% received prophylaxis in a timely fashion. Corresponding figures in hospital B were 36% and 50%. Systems improvements included implementing protocols to administer prophylaxis to all women and increasing the availability of the antibiotic in the operating room. These improvements were associated with increases in overall and timely administration of prophylaxis (P<.001) in both hospitals by time series analysis, with adjustment for volume and case mix. After improvement, overall and timely administration of prophylaxis was 95% and 96% in hospital A and 89% and 96% in hospital B. In hospital A, the surgical site infection rate decreased immediately after the improvements (P<.001). In hospital B, the infection rate began a downward trend before the improvements that continued after their implementation (P =.04).

CONCLUSION

Simple quality improvement methods can be used to optimize obstetric services and improve outcomes of care in resource-limited settings.

Imidazo[1,2-a]quinoxalines: synthesis and cyclic nucleotide phosphodiesterase inhibitory activity

A group of imidazo[1,2-a]quinoxalines have been synthesised from quinoxaline by condensation of an appropriate haloester or intramolecular cyclisation of a keto moiety on an intracyclic nitrogen atom. The reactivity of the heterocycle was explored through diverse reactions such as electrophilic substitution, lithiation and halogen-metal exchange to give access to a new series of derivatives. Confirmation of their structure was mainly performed by NMR, after careful assignment of the signals in comparison to previous attributions made on the parent imidazo[1,2-a]quinoxaline and discussion of available data in the literature. The cyclic nucleotide phosphodiesterase inhibitor activity of some of these derivatives has been assessed on isoenzymes type III and type lV. Compound 15, 4-(methylamino)imidazo[1,2-a]quinoxaline-2-carbonitrile, exhibited potent relaxant activity on smooth muscle, with a potency similar to the one measured with SCA 40, its structural analogue in the imidazo[1,2-a]pyrazine series.

Photochemical-biological treatment of a real industrial biorecalcitrant wastewater containing 5-amino-6-methyl-2-benzimidazolone

5-amino-6-methyl-2-benzimidazolone (AMBI), used in the manufacture of dyes, was characterised as a biorecalcitrant compound by means of different biodegradability tests. In order to enhance the biodegradability of this important pollutant, the application of Advanced Oxidation Process (AOPs) as a pretreatment was explored. Some experiments were addressed to find the most efficient AOP. The systems H2O2/hv, TiO2/H2O2/hv, Fe3+/hv, Fe3+/H2O2 and Fe3+/H2O2/hv were compared. The photo-Fenton system was the most efficient and the optimal conditions (AMBI, Fe3+, H2O2 concentrations) for the degradation of AMBI were found. During the photo-Fenton degradation, experiments were also made to obtain information concerning the evolution of: (a) organic carbon and initial compound concentration; (b) the oxidation state; (c) the toxicity; (d) the biodegradability; and (e) the chemical nature of the intermediates. These analyses show that the solution resulting from the treatment of AMBI is biologically compatible and complete mineralisation can be performed by biological means. A combined photochemical (Fenton) and biological flow reactor for the degradation of AMBI was successfully operated in continuous mode at laboratory scale. 100% of the initial concentration of AMBI and 80.3% of Dissolved Organic Carbon (DOC) were removed in 3.5 hours of total residence time. Finally, some field experiments under direct sunlight carried out at the Plataforma Solar de Almeria, Spain, demonstrated that this solar catalytic system is an effective treatment for this kind of industrial wastewater.

Concentrating versus non-concentrating reactors for solar photocatalytic degradation of p-nitrotoluene-o-sulfonic acid

The photocatalytic oxidation of the non-biodegradable p-nitrotoluene-o-sulfonic acid (p-NTS) in homogeneous (photo-Fenton reactions) and heterogeneous (with TiO2) solutions has been studied at a pilot-scale under solar irradiation at the Plataforma Solar de Almeria (PSA). In this study two different reactors were tested: a medium concentrating radiation system (Heliomans, HM) and a non-concentrating radiation system (CPC). Their advantages and disadvantages for p-NTS degradation have been compared and discussed. The degradation rates obtained in the CPC collector are around three times more efficient than in the HM collectors. However, in both systems, 100% of the initial concentration of p-NTS was removed. Kinetic experiments were performed in both systems using TiO2 suspensions. During the photodegradation, the disappearance of p-NTS was followed by HPLC, the mineralization of the solution by the TOC technique, the evolution of NO3-, NO2-, and SO4(2-) concentration by ionic chromatography, the toxicity by the standard Microtox test, and the biodegradability by BOD5 and COD measurements. The obtained results demonstrated the utility of the heterogeneous catalysis (using TiO2 as catalyst) as a pretreatment method that can be followed by a biological process.

[Detection of antibodies to beta-amyloid in carriers of E280A mutation in the presenilin-1 gene]

OBJECTIVE

To investigate some immune component that could contribute to the pathogenesis of Alzheimer's disease associated with the E280A mutation of the presenilin-1 gene (PS-1).

PATIENTS AND METHODS

Serum antibodies against both cardiolipin and beta-amyloid peptides (beta 1-40 and beta 1-42) were quantitated by means of an indirect ELISA technique in carriers of the mutation, either healthy or with Alzheimer's disease, as well as in normal controls without the mutation.

RESULTS

Out of 19 patients with Alzheimer's disease only 2 had increased values of antibodies to cardiolipin, namely: one with 14.58 micrograms/ml of IgM and the other with 36.16 micrograms/ml of IgG. The remaining individuals revealed values under 10 micrograms/ml, considered normal, and there was no significant difference between the groups. Significant serum reactivity (p < 0.001) was detected against both beta-amyloid peptides in the mutation carriers, either with or without Alzheimer's disease, as compared to the control group. No correlation was detected between this antibody response and the mental or functional situation of the patients.

CONCLUSION

beta-amyloid antibodies, present in the mutation carriers, may simply represent a marker of immune activation induced by beta-amyloid with no in vivo effect; however, despite the results, the possibility can not be ruled out of a pathogenic role of these antibodies in early onset Alzheimer's disease.

Association of maternal short stature with stunting in Mexican children: common genes vs common environment

OBJECTIVE

To evaluate the association between stunting in children and maternal short stature, controlling for potential environmental confounders.

DESIGN

1988 Mexico National Nutrition Survey.

SETTING

Mexico

SUBJECTS

The final sample size was 4663 pairs of children (<5 y) and their mothers (12-49 y) from a total of 13 236 surveyed houses.

MAIN OUTCOME MEASURES

Stunting (height-for-age Z-scores <-2).

RESULTS

The prevalence of stunting in children was 19%, and 10% of the mothers exhibited short stature (<145 cm). In the crude analysis, mothers with short stature were significantly more likely to have stunted children (odds ratio (OR)=4.0; 95% confidence interval (CI)=3.2-4.8; P-value <0.001). In a multiple logistic regression model the OR for child stunting was reduced, but remained significant OR=2.0; 95% CI=1.6-2.6; P-value <0.001) after adjustment for region, urban/rural residence, socio-economic status, household size, child age and presence of infection in the past 14 d, and maternal age, body mass index (BMI), and educational level. Adjusted ORs varied between regions (Mexico City, OR=3.9; North Mexico, OR=3. 1; Central Mexico, OR=2.0; South Mexico, OR=1.6. Comparison of crude vs adjusted estimates pointed to regional differences in the proportion of association between maternal and child short statures explained by environmental determinants.

CONCLUSIONS

Maternal stature, reflecting her potential height and early environment, appeared to contribute to child height independently of the shared risk factors that could affect stature. Nonetheless, we could explain much of the association between stunting in children and maternal short stature by environmental factors, and part of the residual variability may be due to unmeasured determinants. Regional differences pointed to a predominance of environmental factors in explaining child stunting in poorer regions.

Questionnaire assessment of antioxidants and retinol intakes in Mexican women

BACKGROUND

In order to assess intake of antioxidants and retinol, we evaluated the validity and reproducibility of a semiquantitative food frequency questionnaire.

METHODS

Data were collected from 110 women, aged 15-54 years, who resided in the southern part of Mexico City. Study participants were asked to complete the food frequency questionnaire before and after completing four series of 4 days of 24-h diet recalls. We obtained the 24-h recalls at 3-month intervals designed to account for seasonal variability. In addition, we measured serum blood levels of retinol and various carotenoids at 3 and 9 months after baseline.

RESULTS

Intraclass correlation coefficients for intake of energy-adjusted daily nutrients, assessed by the questionnaires 1 year apart, ranged from 0.23 for lutein/zeaxanthin to 0.50 for total carotenes. Correlation coefficients between energy-adjusted nutrient intakes were measured by means of the sixteen 24-h dietary recalls, and the second questionnaire ranged from 0.09 for lutein/zeaxanthin to 0.45 for total carotenes. These correlations were higher after adjusting for day-to-day variations in diets ranging from 0.11 for lutein/zeaxanthin to 0.49 for vitamin C. Correlation coefficients between intake and biochemical measures were 0.32 for alpha-carotene, 0.34 for beta-carotene, and 0.40 for total carotene after adjusting for age, body mass index, cholesterol and triglyceride plasma levels, smoking status, and caloric intake.

CONCLUSIONS

These data support the ability of our food frequency questionnaire to provide valid information on the relative intake of these nutrients and to confirm its usefulness in epidemiological studies of diet-disease relations. However, its application outside Mexico City or in different age or gender populations will require additional modifications and validation efforts.

Validity and reproducibility of a food frequency questionnaire to assess dietary intake of women living in Mexico City

OBJECTIVE

To assess the reproducibility and validity of a 116 item semi-quantitative food frequency questionnaire (FFQ), designed to assess the relation between dietary intake and chronic diseases.

MATERIAL AND METHODS

To test the reproducibility of the FFQ questionnaire, the FFQ was administered twice to 134 women residing in Mexico City at an interval of approximately one year; to assess the validity we compared results obtained by the FFQs with those obtained by four 4-day 24-hour recalls at three month intervals. Validity and reproducibility were evaluated using regression analysis and Pearson and intraclass correlation coefficients of log-e and calorie-adjusted nutrient scores.

RESULTS

Mean values for intake of most nutrients assessed by the two food frequency questionnaires were similar. However, means for the 24-hr recall were significantly lower. Intraclass correlation coefficients for nutrient intakes, assessed by questionnaires, administered one year apart, ranged from 0.38 for cholesterol to 0.54 for crude fiber. Correlation coefficients between energy-adjusted nutrient intakes, measured by diet recalls, and the first FFQ ranged from 0.12 for polyunsaturated fatty acids to 0.67 for saturated fatty acids. Regression coefficients between 24-hr recall and FFQ,s were all significant were significant for all nutrients, except for polyunsaturated fat, folic acid, vitamin E and Zinc.

CONCLUSIONS

These data indicate that this semi-quantitative FFQ is reproducible and provides a useful estimate by which to categorize individuals by level of past nutrient intake. However, its application outside Mexico City or in different age and gender populations will require additional modifications and validation efforts.

Dietary studies in countries experiencing a health transition: Mexico and Central America

Several countries, including Mexico, are experiencing changes in health patterns that are characterized by an increase in the prevalence of chronic diseases and changes in the principal causes of death, coexisting with deficiencies in the intake of energy and micronutrients, particularly in children. Several factors may explain these changes, including dietary habits. To evaluate food consumption in a population undergoing a health transition, a food-frequency questionnaire was developed, validated, and used to study the dietary determinants of chronic diseases in Mexico. Nutrient deficiency and the relation between maternal child-feeding behaviors and dietary intake by the child were evaluated with use of 24-h recalls, food-frequency methods. and estimation of food intake by observation. The observation method was extremely useful for studies in rural areas.

[Reproducibility of a questionnaire for studying climacteric]

OBJECTIVE

This study evaluated the reproducibility of a questionnaire concerned with the clinical and epidemiological aspects of menopause.

MATERIAL AND METHODS

The study population consisted of a hundred perimenopausal Mexican women seeking care at gynecology and obstetric health care services. Their participation was voluntary and they answered the same questionnaire two times with a 15-30 day lag between each application.

RESULTS

The Kappa coefficient was high (0.81-1.0) for categorical variables such as: type of menstrual cycles, type of menopause, breast-feeding, use of estrogen during menopause and use of hormonal contraceptives. The Kappa coefficient was moderate (0.7-0.8) for symptoms related to menopause such as hot flashes, sweating, painful coitus, vaginal dryness and a decrease in libido. Mean differences were calculated for continuous variables such as age at menarche, age at menopause, time using estrogen and the duration of breast-feeding, the majority had a value of zero and 95% confidence intervals for these mean differences included the null value. The questionnaire also included other characteristics such as tobacco consumption and a short food frequency questionnaire, which showed high concordance (Kappa 0.7-1.0).

CONCLUSIONS

The results of this study show that this questionnaire has a high level of reproducibility and can be useful as a research tool to explore menopause in Mexican women.

[Familial hyperphosphatasemia of intestinal origin]

To clarify the diagnostic laboratory procedures before a case of unknown origin hyperphosphatasemia, we have studied the electrophoretic separation of serum alkaline phosphatase activity on agarose gel with and without neuraminidase. Sera were collected from a family, four of whom showed hyperphosphatasemia. Alkaline phosphatase isoenzyme patterns on agarose gel electrophoresis demonstrated that two persons out of the six members tested had unusual isozymes, the hydrophilic and the hydrophobic intestinal isozyme representing more than 50% of total alkaline phosphatase. The advantages of this method are its simplicity and low cost. The early recognition of this benign abnormality should help to avoid unnecessary diagnostic tests (i.e. image or radioisotopic examination).

[Natural killer cytolytic activity in renal and prostatic cancer]

Natural killer cytolytic activity, the basis of cancer immunotherapy that uses cytolytic cells, may be impaired in cancer. The aim of this work was to study in vitro the natural killer cytolytic activity and its response to the immunomodulators interleukin-2, interferon and phytohemagglutinin stimulated lymphocyte proliferation in a group of 9 patients with renal cell cancer and 6 with prostatic cancer. The results were compared with those of 20 normal volunteers. Twelve patients were operated and were studied twice 48 h and 14 days after surgery. Natural killer cytolytic activity was significantly lower in renal cell and prostatic cancer patients than controls (3.3 +/- 1.6, 4.9 +/- 2.2 and 20.6 +/- 3.7% of specific lysis respectively). This activity was not modified in cancer patients by interleukin-2 50 UI/ml or interferon 3000 UI/ml and did not differ in the two postoperative periods. Phytohemagglutinin stimulated lymphocyte proliferation was also lower in cancer patients, compared to controls (stimulation index of 18 +/- 3 and 26.5 +/- 5 respectively). It is concluded that these patients have a low immunological level and that this study is the first step towards an immunological characterization of cancer patients that are candidate to adoptive immunotherapy.

Enhancement of natural killer cell activity in septic shock patients by a mixture of the calcium ionophore A23187 and the phorbol ester TPA: in vitro studies

Preincubation of peripheral blood lymphocytes from drug-free, healthy volunteers with a mixture of the calcium ionophore A23187 (Io) and the phorbol ester TPA (12-O-tetradecanoylphorbol-13-acetate) consistently resulted in a significant enhancement (dose-dependent; maximum immunostimulation obtained with the Io + TPA final mixture concentration of 10 uM + 250 ng/ml, respectively) of natural killer cell activity (NKCA) (n = 8; mean +/- SD of 16.8 +/- 8.9 and 52.0 +/- 18.0, paired Student's t-test p < 0.005; effector-to-target cell ratio of 30:1). Results from the same protocol, but using samples from septic shock patients followed a similar trend; however, and perhaps reflecting the significantly lower baseline NKCA in this group of individuals (n = 7), the mean value reached for this cellular immune function after incubation with Io + TPA was significantly lower than that of the treated controls' group (mean +/- SD of 19.8 +/- 11.6 and 52.0 +/- 18.0, respectively, Student's t-test p < 0.005). As expected from the role of calcium in the activation of NKCA, incubation with the Io significantly increased baseline NKCA, which was largely unchanged by TPA. Expression of the CD56+ and CD16+ phenotypes in septic shock patients did not correlate directly with NKCA, suggesting that this condition may be associated with changes in the function rather than the quantity of these cellular markers.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro studies of natural killer cell activity in septic shock patients. Response to a challenge with alpha-interferon and interleukin-2

Natural killer cell activity (NKCA) in patients with septic shock was statistically significantly lower than the value recorded for a group of drug-free, healthy volunteers [9.1 +/- 7.8 (n = 20) and 20.6 +/- 16.6 (n = 15), respectively; Student's test, p < 0.05]. As expected, preincubation of peripheral blood lymphocytes from samples taken from a group of controls with either alpha-interferon or interleukin -2 resulted in an enhancement of NKCA for each and everyone of the subjects studied; however, results from a similar protocol using patient samples showed a lack of consistency, both in the direction and magnitude, in the elicited changes in NK lytic function. Whereas samples from same patient responded with either an increase or a decrease in NKCA to preincubation with both immunostimulators, others responded with NKCA upmodulation to one and downmodulation to other of these test substances. A better knowledge of the mechanism(s) responsible for the depressed expression of NKCA in septic shock patients, and its altered response to alpha-interferon and interleukin-2, could generate new modalities in the diagnosis and therapy of this condition.