Polyphenol oxidase inactivation from apple juice by Al-based metal-organic frameworks: New anti-browning strategy in fruits and vegetables.

Polyphenol oxidase (PPO) is critical due to enzymatic browning in fruits and vegetables, developing economic impact in fruits industry. Metal-Organic Frameworks (MOF) have shown interesting characteristics such as water stability, low toxicity, and good adsorption yield, making them good candidates for PPO inactivation. Al-based-MOFs, MIL-53(Al), DUT-5, and MIL-110 were tested as PPO inactivators in apple juice by enzyme-MOF interactions at r.t. through two possible mechanisms, i) substrate scavengers (substrates:catechol and 4-methylcatechol) or ii) enzyme activity modifiers. The scavenging behavior of Al-based-MOFs was moderate, in the same magnitude, being catechol adsorption better than 4-methylcatechol. PPO activity was reduced by at least 70% by MIL-53(Al)/DUT-5 in 10/30 min respectively, and MIL-110 inactivated PPO in 50 min with some structural modifications. Enzyme-MOF interactions are major responsible for PPO inactivation. This could be a new applicability of MOFs, as an alternate PPO inactivation process, easily included in juice processing, retaining sensorial/nutritional properties, developed at r.t thus energy-cost-effective.

Purification and biochemical characterization of polyphenol oxidase from soursop (Annona muricata L.) and its inactivation by microwave and ultrasound treatments.

The soursop (Annona muricata L.) is a climacteric fruit that may undergo enzymatic browning during ripening, mainly by the activity of polyphenol oxidase (PPO). Soursop PPO was purified 160-fold by hydrophobic interaction and ion-exchange chromatography. The native structure has a molecular weight of 112 kDa corresponding to a dimeric structure. The protein has an optimum pH and temperature of 6.5 and 25°C, respectively; and activation energy of 40.97 kJ·mol-1 . The lowest Km value was observed for caffeic acid (0.47 mM); the best substrate was 4-methyl-catechol (1,067 U·mM-1  min-1 ). Inactivation assays showed that PPO was completely inactivated by tropolone, Na2 S2 O5 and ascorbic acid, and thermally at 55°C for <5 min, microwave exposure reduced activity to 57% at 70 W in 30 s and ultrasound treatment diminished activity to 43% at 120 W in 220 s. This study allows a better understanding of soursop PPO behavior and provides inactivation information. PRACTICAL APPLICATIONS: The conservation of fresh fruits is complicated due to the enzymatic reactions that are present in fruits, such as enzymatic browning. The enzymes responsible for these reactions can be inactivated by, different chemical compounds as well as by the use of emerging technologies, such as microwaves and sonication, which seek to satisfy the consumer needs to obtain fresh products with good nutritional characteristics and adequate safety.

Purification and partial biochemical characterization of polyphenol oxidase from mango (Mangifera indica cv. Manila).

Polyphenol oxidase (PPO) is an enzyme widely distributed in the plant kingdom that has been detected in most fruits and vegetables. PPO was extracted and purified from Manila mango (Mangifera indica), and its biochemical properties were studied. PPO was purified 216-fold by hydrophobic interaction and ion exchange chromatography. PPO was purified to homogeneity, and the estimated PPO molecular weight (MW) by SDS-PAGE was ≈31.5 kDa. However, a MW of 65 kDa was determined by gel filtration, indicating a dimeric structure for the native PPO. The isolated PPO showed the highest affinity to pyrogallol (Km = 2.77 mM) followed by 4-methylcatechol (Km = 3.14 mM) and catechol (Km = 15.14 mM). The optimum pH for activity was 6.0. PPO was stable in the temperature range of 20-70 °C. PPO activity was completely inhibited by tropolone, ascorbic acid, sodium metabisulfite, and kojic acid at 0.1 mM.

Effects of selective activation of M1 and M4 muscarinic receptors on object recognition memory performance in rats.

Acetylcholine signaling through muscarinic receptors has been shown to benefit memory performance in some conditions, but pan-muscarinic activation also frequently leads to peripheral side effects. Drug therapies that selectively target M1 or M4 muscarinic receptors could potentially improve memory while minimizing side effects mediated by the other muscarinic receptor subtypes. The ability of three recently developed drugs that selectively activate M1 or M4 receptors to improve recognition memory was tested by giving Long-Evans rats subcutaneous injections of three different doses of the M1 agonist VU0364572, the M1 positive allosteric modulator BQCA or the M4 positive allosteric modulator VU0152100 before performing an object recognition memory task. VU0364572 at 0.1 mg/kg, BQCA at 1.0 mg/kg and VU0152100 at 3.0 and 30.0 mg/kg improved the memory performance of rats that performed poorly at baseline, yet the improvements in memory performance were the most statistically robust for VU0152100 at 3.0 mg/kg. The results suggested that selective M1 and M4 receptor activation each improved memory but that the likelihood of obtaining behavioral efficacy at a given dose might vary between subjects even in healthy groups depending on baseline performance. These results also highlighted the potential of drug therapies that selectively target M1 or M4 receptors to improve memory performance in individuals with impaired memory.

[Tobacco advertising and promotions: changes in reported exposure in a cohort of Mexican smokers]. / Autorreporte de exposición a publicidad y promoción de tabaco en una cohorte de fumadores mexicanos.

OBJECTIVE: To determine in a population-based sample of smokers the level exposure to tobacco industry marketing through different channels before and after their restriction through the General Tobacco Control Law of 2008. MATERIALS AND METHODS: Data were analyzed from a cohort of adult smokers from four Mexican cities who were surveyed in 2007 and 2008. GEE models were estimated for each indicator of advertising and promotion exposure. RESULTS: Increases were found in report of receiving free samples of tobacco (3.7-8.1%), branded clothing (3.6-6.4%), noticing tobacco industry sponsored events (1.9-4.7%) and noticing ads in bars (21.4-28%). Noticing outdoor advertising decreased over this time (54.7 a 47.2%). CONCLUSIONS: Our findings confirm tobacco industry shifting of marketing efforts when advertising and promotion bans are not comprehensive. There is a need to monitor compliance with marketing bans while working to make them comprehensive.

Autorreporte de exposición a publicidad y promoción de tabaco en una cohorte de fumadores mexicanos / Tobacco advertising and promotions: changes in reported exposure in a cohort of Mexican smokers

OBJETIVO: Determinar en población fumadora el nivel de exposición a la mercadotecnia de la industria tabacalera (IT), a través de diferentes métodos de promocionar sus productos, antes y durante la publicación de la Ley General para el Control del Tabaco (LGCT) en 2008. MATERIAL Y MÉTODOS: Estudio de cohorte en fumadores adultos (n=941 pre-LGCT y n=1 051 post-LGCT) de cuatro ciudades mexicanas. Se realizaron análisis multivariados mediante modelos de ecuaciones de estimación generalizada (GEE). RESULTADOS: Se incrementó el autorreporte de recepción de muestras gratis de cigarros (3.7 a 8.1%), ropa o artículos con marcas o logos (3.6 a 6.4%), haber visto información sobre eventos especiales (1.9 a 4.7%), y publicidad en bares y discotecas para mayores de edad (21.4 a 28%). Se observaron decrementos de publicidad en exteriores (54.7 a 47.2%). CONCLUSIÓN: Es necesaria una política integral con prohibiciones totales de la publicidad y promoción de los productos de tabaco que integre mayor vigilancia y sanciones para lograr la disminución y prevención del consumo de tabaco.

OBJECTIVE: To determine in a population-based sample of smokers the level exposure to tobacco industry marketing through different channels before and after their restriction through the General Tobacco Control Law of 2008. MATERIALS AND METHODS: Data were analyzed from a cohort of adult smokers from four Mexican cities who were surveyed in 2007 and 2008. GEE models were estimated for each indicator of advertising and promotion exposure. RESULTS: Increases were found in report of receiving free samples of tobacco (3.7-8.1%), branded clothing (3.6-6.4%), noticing tobacco industry sponsored events (1.9-4.7%) and noticing ads in bars (21.4-28%). Noticing outdoor advertising decreased over this time (54.7 a 47.2%). CONCLUSIONS: Our findings confirm tobacco industry shifting of marketing efforts when advertising and promotion bans are not comprehensive. There is a need to monitor compliance with marketing bans while working to make them comprehensive.

[Monitoring strategy for control of tobacco in Mexico: advertising, promotion and sponsorship, packaging and labeling]. / Estrategia de vigilancia para el control del tabaco en México: publicidad, promoción y patrocinio, empaque y etiquetado.

OBJECTIVE: To describe strategies used in the publicity, marketing, and sale, of tobacco products in 12 cities in Mexico. MATERIAL AND METHODS: Tobacco products points of sale (POS) were identified within a 500 m radius of Global Youth Tobacco Survey (2005-2006) schools. We used observational surveys and an online Geographic Information System (GIS). RESULTS: In the 257 schools visited, we found, on average, 8.3 stores and 5 street vendors around each of them. Forty-four percent of the stores had interior tobacco publicity, 8.3% had tobacco products at children's eye level, 6.5% had some promotion, 33.6% had a no selling to minors sign, and 44.4% of stores and 58.8% of street vendors sold single cigarettes. CONCLUSIONS: Tobacco products are largely publicized and marketed around schools. There is no compliance of tobacco control legislation in regards to selling to minors and single cigarettes. It is necessary to implement a surveillance system to monitor strategies for tobacco control and the tobacco industry.

Estrategia de vigilancia para el control del tabaco en México: publicidad, promoción y patrocinio, empaque y etiquetado / Monitoring estrategy for control of tobacco in Mexico: advertising, promotion and sponsorship, packaging and labeling

Objetivo. Describir las estrategias de publicidad, mercadeo, y venta productos del tabaco en 12 ciudades de México. Material y métodos. Los puntos de venta de tabaco, a 500mts alrededor de escuelas participantes de la Encuesta de Tabaquismo en Jóvenes (2005-2006), fueron identificados usando formatos observacionales y un Sistema de Información Geográfica en línea. Resultados. En promedio se encontraron 8 establecimientos y 5 puestos de calle alrededor de las 257 escuelas visitadas. 44.4 por ciento de los establecimientos tenía publicidad en interior, 8.3 por ciento poseían productos a la altura de los ojos de los niños y 6.5 por ciento tenía alguna promoción. El 33.6 por ciento tenía letrero de prohibición de venta a menores, en tanto que 44.4 por ciento de los establecimientos y 58.8 por ciento puestos de calle vendían cigarros sueltos. Conclusiones. Los productos de tabaco son ampliamente publicitados y comercializados alrededor de las escuelas. Existe un alto incumplimiento de las leyes referentes a la venta a menores y por menores. Es urgente implementar un sistema que permita una vigilancia continua de las estrategias de la industria y para el control del tabaco.

Objective. To describe strategies used in the publicity, marketing, and sale, of tobacco products in 12 cities in Mexico. Material and Methods. Tobacco products points of sale (POS) were identified within a 500 m radius of Global Youth Tobacco Survey (2005-2006) schools. We used observational surveys and an online Geographic Information System (GIS). Results. In the 257 schools visited, we found, on average, 8.3 stores and 5 street vendors around each of them. Forty-four percent of the stores had interior tobacco publicity, 8.3 percent had tobacco products at children's eye level, 6.5 percent had some promotion, 33.6 percent had a no selling to minors sign, and 44.4 percent of stores and 58.8 percent of street vendors sold single cigarettes. Conclusions. Tobacco products are largely publicized and marketed around schools. There is no compliance of tobacco control legislations in regards to selling to minors and single cigarettes. It is necessary to implement a surveillance system to monitor strategies for tobacco control and the tobacco industry.

PAR1 is selectively over expressed in high grade breast cancer patients: a cohort study.

BACKGROUND: The protease-activated receptor (PAR1) expression is correlated with the degree of invasiveness in cell lines. Nevertheless it has never been directed involved in breast cancer patients progression. The aim of this study was to determine whether PAR1 expression could be used as predictor of metastases and mortality. METHODS: In a cohort of patients with infiltrating ductal carcinoma studied longitudinally since 1996 and until 2007, PAR1 over-expression was assessed by immunoblotting, immunohistochemistry, and flow citometry. Chi-square and log rank tests were used to determine whether there was a statistical association between PAR1 overexpression and metastases, mortality, and survival. Multivariate analysis was performed including HER1, stage, ER and nodes status to evaluate PAR1 as an independent prognostic factor. RESULTS: Follow up was 95 months (range: 2-130 months). We assayed PAR1 in a cohort of patients composed of 136 patients; we found PAR1 expression assayed by immunoblotting was selectively associated with high grade patients (50 cases of the study cohort; P = 0.001). Twenty-nine of 50 (58%) patients overexpressed PAR1, and 23 of these (46%) developed metastases. HER1, stage, ER and PAR1 overexpression were robustly correlated (Cox regression, P = 0.002, P = 0.024 and P = 0.002 respectively). Twenty-one of the 50 patients (42%) expressed both receptors (PAR1 and HER1 P = 0.0004). We also found a statistically significant correlation between PAR1 overexpression and increased mortality (P = 0.0001) and development of metastases (P = 0.0009). CONCLUSION: Our data suggest PAR1 overexpression may be involved in the development of metastases in breast cancer patient and is associated with undifferentiated cellular progression of the tumor. Further studies are needed to understand PAR1 mechanism of action and in a near future assay its potential use as risk factor for metastasis development in high grade breast cancer patients.

Glutathione depletion activates mitogen-activated protein kinase (MAPK) pathways that display organ-specific responses and brain protection in mice.

Because mitogen-activated protein kinases (MAPK) are downstream effectors of antioxidant responses, changes in GSH levels in an organism might induce organ-specific responses. To test our hypothesis, mice were treated intraperitoneally with L-buthionine-S-R-sulfoximine (BSO) to inhibit GSH synthesis. A time-related GSH depletion in the liver and kidney correlated with p38(MAPK) phosphorylation and induction of thioredoxin 1 (Tx-1) transcription. This positive regulation was associated with nuclear translocation of NF-kappaB and ATF-2 and c-Jun phosphorylation in the liver, but only c-Jun phosphorylation in the kidney. Increased levels of GSH were observed in the brain together with extracellular regulated kinase 2 (ERK2) activation, Nrf2 nuclear accumulation, and increases in transcription of Nrf2, xCT, gamma-glutamylcysteine synthetase (gammaGCSr), and Tx-1. Pretreatment with MAPK inhibitors SB203580 and U0126, or addition of the exogenous thiol N-acetylcysteine, abrogated both p38(MAPK) and ERK2 activation as well as downstream effects on gene expression. No effect on gammaGCSr was observed. These results indicate that in mice, GSH depletion is associated with p38(MAPK) phosphorylation in the liver and kidney and with ERK2 activation in the brain, in what could be considered part of the brain's protective response to thiol depletion.