Impairment of antioxidant defense via glutathione depletion sensitizes acute lymphoblastic leukemia cells for Smac mimetic-induced cell death.

Evasion of apoptosis in pediatric acute lymphoblastic leukemia (ALL) is linked to aberrant expression of inhibitor of apoptosis (IAP) proteins and dysregulated redox homeostasis, rendering leukemic cells vulnerable to redox-targeting therapies. Here we discover that inhibition of antioxidant defenses via glutathione (GSH) depletion by buthionine sulfoximine (BSO) primes ALL cells for apoptosis induced by the Smac mimetic BV6 that antagonizes IAP proteins. Similarly, BSO cooperates with BV6 to induce cell death in patient-derived primary leukemic samples, underscoring the clinical relevance. In contrast, BSO does not sensitize non-malignant lymphohematopoietic cells from healthy donors toward BV6, pointing to some tumor selectivity. Mechanistically, both agents cooperate to stimulate reactive oxygen species (ROS) production, which is required for BSO/BV6-induced cell death, as ROS inhibitors (that is, N-acetylcysteine, MnTBAP, Trolox) significantly rescue cell death. Further, BSO and BV6 cooperate to trigger lipid peroxidation, which is necessary for cell death, as genetic or pharmacological blockage of lipid peroxidation by GSH peroxidase 4 (GPX4) overexpression or α-tocopherol significantly inhibits BSO/BV6-mediated cell death. Consistently, GPX4 knockdown or GPX4 inhibitor RSL3 enhances lipid peroxidation and cell death by BSO/BV6 cotreatment. The discovery of redox regulation of Smac mimetic-induced cell death has important implications for developing rational Smac mimetic-based combination therapies.

RIP1 is required for IAP inhibitor-mediated sensitization of childhood acute leukemia cells to chemotherapy-induced apoptosis.

Evasion of apoptosis may contribute to poor treatment response in pediatric acute lymphoblastic leukemia (ALL), calling for novel treatment strategies. Here, we report that inhibitors of apoptosis (IAPs) at subtoxic concentrations cooperate with various anticancer drugs (that is, AraC, Gemcitabine, Cyclophosphamide, Doxorubicin, Etoposide, Vincristine and Taxol) to induce apoptosis in ALL cells in a synergistic manner as calculated by combination index and to reduce long-term clonogenic survival. Importantly, we identify RIP1 as a critical regulator of this synergism of IAP inhibitors and AraC that mediates the formation of a RIP1/FADD/caspase-8 complex via an autocrine/paracrine loop of tumor necrosis factor-α (TNFα). Knockdown of RIP1 abolishes formation of this complex and subsequent activation of caspase-8 and -3, mitochondrial perturbations and apoptosis. Similarly, inhibition of RIP1 kinase activity by Necrostatin-1 or blockage of TNFα by Enbrel inhibits IAP inhibitor- and AraC-triggered interaction of RIP1, FADD and caspase-8 and apoptosis. In contrast to malignant cells, IAP inhibitors and AraC at equimolar concentrations are non-toxic to normal peripheral blood lymphocytes or mesenchymal stromal cells. Thus, our findings provide first evidence that IAP inhibitors present a promising strategy to prime childhood ALL cells for chemotherapy-induced apoptosis in a RIP1-dependent manner. These data have important implications for developing apoptosis-targeted therapies in childhood leukemia.

The nutritional quality of Scenedesmus acutus in a semi-industrial plant in Peru.

The nutritional quality of the flour of the micro-algae Scenedesmus acutus produced in a semi-industrial pilot plant at Sausal, Peru has been tested. The protein content varies between 47.4% and 66.6%. The PER was 2.63 = 0.15 (Casein 3.00 = 0.11), true digestibility 83.4 (Casein 92.4) and BV 60.9 (Casein 73.4). The protein quality did not increase by amino acid supplementation. The 12-week feeding test with micro-algae led to no abnormalities of the weight development, blood parameters, weights of organs and histological datas in the test animals. Further feeding trials and clinical examination on human subjects are recommended before approvement for use in human diet.

[Comparison of 4 methods of evaluating protein quality in vegetable sources]. / Comparación de cuatro métodos de evaluación de calidad proteínica en fuentes vegetales.

This study compares the practical value of the following methods: protein efficiency ratio (PER), blood urea concentration in rats (BUC), relative nutritive value (RNV), and predicted protein value (PPV) to evaluate the protein quality of 41 diets of plant origin. Results demonstrated low correlations between PER and RNV (r = 0.66), PER and PPV (r = 0.53), RNV and PPV (r = 0.54), whereas there was a high negative correlation between PER and BUC (r = -0.89). These different procedures can be useful and valid for distinct and well-defined objectives, but the evaluation of results must be made in accordance with the purpose of the experiment. In assessing the protein quality of foodstuffs, it is therefore recommended that mathematical computer models be developed which take into account the cybernetic system of the amino acid metabolism. This would definitely reduce the actual need of expensive long-term biological assays.

[Phenotypic and technological influences of the Lupinus mutabilis (Tarwi) seed on its methionine availability and sulfur content]. / Influencia fenotípica y tecnológica de la semilla del Lupinus mutabilis (Tarwi) sobre la disponibilidad de metionina y el contenido de azufre.

The present study was carried out to determine the content of available methionine and sulphur in seed cultivars of Lupinus mutabilis from different Andean regions, and to study the influence of processing on methionine and sulphur contents. An additional objective was to evaluate interrelationships among these chemical characteristics and protein quality, as measured by the protein efficiency ratio (PER) method. Results revealed a high variability in the content of available methionine and sulphur between the different ecotypes and varieties of Lupinus mutabilis. Fertilization with CaSO4 (200 kg/ha) did alter the content of available methionine and sulphur in Lupinus albus seeds. Traditional water-debittering of lupines did not affect the methionine content of the seeds, whereas oil-extraction and alcohol-debittering led to a decrease in available methionine (14 and 23% reduction, respectively). Production of a protein isolate further reduced the methionine content (54%). Regression analysis revealed a high correlation between available methionine and sulphur (r = 0.83), between sulphur and PER (r = 0.98) in the processed lupine samples, and lupine mixtures with other protein sources.

Influencia fenotipica y tecnologica de la semilla del Lupinus mutabilis (Tarwi) sobre la disponibilidad de metionina y el contenido de azufre. / Phenotypic and technological influences of the Lupinus mutabilis (Tarwi) seed on the methionine availability and sulfur content

Se estudio la influencia del procesamiento del Lupinus mutabilis sobre el contenido de metionina disponible y azufre, asi como su variabilidad en semillas de diferentes regiones andinas. Ademas, se relacionaron los resultados de las determinaciones quimicas de metionina, disponible y azufre del lupino con su calidad proteinica expressada por el indice de eficiencia proteinica (PER). Los resultados en los ecotipos y variedades de tarwi estudiados revelaron gran variabilidad en el contenido de metionina disponible y azufre. La fertilizacion con CaSO4 (200 kg/ha) afecto el contenido de metionina disponible y azufre en las semillas de Lupinus albus. El desamargado tradicional con agua del Lupinus mutabilis no tuvo efecto sobre el contenido de metionina disponible. La harina de tarwi sometida a extraccion de aceite, y la harina desamargada con alcohol, disminuyen significativamente su contenido de metionina disponible y azufre (14 y 23%, respectivamente) siendo mayor este descenso durante la obtencion del aislado proteinico (54%). Se encontraron altos coeficientes de correlacion entre metionina disponible y PER (r=0.98) en muestras de lupino procesado y mezclas de lupino con otras fuentes de proteina

Comparacion de cuatro metodos de evaluacion de calidad proteinica en fuentes vegetales. / Comparison of 4 methods for evaluation of protein quality in vegetable sources

Se comparo la utilidad practica de los metodos de indice de eficiencia proteinica (PER), concentracion de urea en sangre de ratas, valor nutritivo relativo (VNR) determinado a traves de la bacteria Streptococcus zymogenes, y de prediccion del valor proteinico (PPV), a fin de evaluar la calidad de la proteina de origen vegetal de 41 dietas. Se obtuvo baja correlacion entre los valores de PER y NRV (r= 0.66), PER y PPV (r=0,53), NRV y PPV (r=0.54) en contraste con la correlacion entre PER y urea, que resulto ser mas alta (r= -8.89).Los diferentes metodos pueden ser utiles y valiosos para objetivos distintos y definidos, pero los resultados de cada procedimiento se valoran de acuerdo a los objetivos del presente estudio. Para determinar la calidad proteinica de los alimentos, se recomienda la busqueda de computadoras de modelos matematicos, que abarquen el sistema cibernetico del metabolismo de los aminoacidos. Ello disminuiria el empleo actual de ensayos prolongados y costosos con seres vivientes

Composition and protein quality of Lupinus mutabilis.

The chemical composition and the protein quality of three samples of Lupinus mutabilis (a raw, semi-sweet variety; cooked, water-extracted seeds; and alcohol-extracted oil cake) were studied. The protein content varied from 47.7% dry weight (raw seeds) to 65.3% (oil-cake). Compared to the FAO reference pattern sulfur- containing amino acids are first limiting. The water-extracted sample contained 26.9% oil and the polyunsaturated/saturated fatty acid ratio of 30 seed samples was 5.3. Alkaloid content of raw seed was high (3.3%), but could be reduced or nearly eliminated by water-and-alcohol extraction or plant breeding. Other anti-nutritive substances were present only in trace quantities. Protein quality measured as protein efficiency ratio (PER) gave low values for the non-supplemented lupin proteins (1.34 semi-sweet variety; 1.53 water-extracted seeds; 1.19 oil-cake; 3.09 casein), but the PER's were improved by the addition of 0.2% DL-methionine to the diets (3.05, 2.69, 2,81, respectively). Raw as well as processed lupin protein showed an excellent apparent digestibility (80.0-85.8%, casein 87.1%). Studies of net protein utilization (NPU) and biological value (BV) confirmed the importance of methionine supplementation, The true digestibility of 92% was equivalent to that of casein.

[Establishment of optimal conditions at laboratory and pilot plant levels for the preparation of a protein isolated from Lupinus mutabilis]. / Establecimiento de las condiciones óptimas a nivel de laboratorio y de planta piloto para la preparación de un aislado proteínico de Lupinus mutabilis.

Laboratory conditions were first investigated to determine are optimum processing parameters for the preparation of a protein isolate from the ground, defatted, commercial flakes of Lupinus mutabilis. The extraction variables were: pH (2-10); solvent to lupine ratio (5:1 to 40:1); temperature (28 degrees C - 60 degrees C) and time (10-50 min). The isoelectric point of the lupine protein was found to be pH 4.5 with a protein solubility higher than 80% above pH 8.0. Using 70-100 mesh, ground defatted flakes, and extracting at pH 8.7 for 60 min, a protein isolate was obtained on acidification to pH 4.5 which was 99.8 protein (dry basis), compared to 55.25% protein for the original material. This protein isolate represented 32% of the initial material and 57.6% of the initial nitrogen. When making pilot plant assays we found that the yield of protein isolate decreased to 20.4% of the original material and 36.4% of the initial nitrogen. The protein efficiency ratio for the protein isolate was 2.15 when supplemented with methionine, and had a digestibility of 89.33