Apoptotic bone cells may be engulfed by osteoclasts during alveolar bone resorption in young rats

The alveolar bone is a suitable in vivo physiological model for the study of apoptosis and interactions of bone cells because it undergoes continuous, rapid and intense resorption/remodelling, during a long period of time, to accommodate the growing tooth germs. The intensity of alveolar bone resorption greatly enhances the chances of observing images of the extremely rapid events of apoptosis of bone cells and also of images of interactions between osteoclasts and osteocytes/osteoblasts/bone lining cells. To find such images, we have therefore examined the alveolar bone of young rats using light microscopy, the TUNEL method for apoptosis, and electron microscopy. Fragments of alveolar bone from young rats were fixed in Bouin and formaldehyde for morphology and for the TUNEL method. Glutaraldehyde-formaldehyde fixed specimens were processed for transmission electron microscopy. Results showed TUNEL positive round/ovoid structures on the bone surface and inside osteocytic lacunae. These structures - also stained by hematoxylin - were therefore interpreted, respectively, as osteoblasts/lining cells and osteocytes undergoing apoptosis. Osteoclasts also exhibited TUNEL positive apoptotic bodies inside large vacuoles; the nuclei of osteoclasts, however, were always TUNEL negative. Ultrathin sections revealed typical apoptotic images - round/ovoid bodies with dense crescent-like chromatin - on the bone surface, corresponding therefore to apoptotic osteoblasts/lining cells. Osteocytes also showed images compatible with apoptosis. Large osteoclast vacuoles often contained fragmented cellular material. Our results provide further support for the idea that osteoclasts internalize dying bone cells; we were however, unable to find images of osteoclasts in apoptosis. (C) 2001 Harcourt Publishers Ltd.

The frog Dermatonotus muelleri (Boettger 1885) (Anura Microhylidae) shifts its search tactics in response to two different prey distributions

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Conjugated linoleic acid and cardiac health: Oxidative stress and energetic metabolism in standard and sucrose-rich diets

Studies on conjugated linoleic acid ingestion and its effect on cardiac tissue are necessary for the safe utilization of this compound as supplement for weight loss. Male Wistar 24-rats were divided into four groups (n = 6):(C)given standard chow, water and 0.5 ml saline, twice a week by gavage; (C-CLA)receiving standard chow, water and 0.5 ml of conjugated linoleic acid, twice a week, by gavage; (S)given standard chow, saline by gavage, and 30% sucrose in its drinking water; (S-CLA)receiving standard chow, 30% sucrose in its drinking water and conjugated linoleic acid. After 42 days of treatment S rats had obesity with increased abdominal-circumference, dyslipidemia, oxidative stress and myocardial lower citrate synthase(CS) and higher lactate dehydrogenase(LDH) activities than C. Conjugated linoleic acid had no effects on morphometric parameters in C-CLA, as compared to C, but normalized morphometric parameters comparing S-CLA with S. There was a negative correlation between abdominal adiposity and resting metabolic rate. Conjugated linoleic acid effect, enhancing fasting-VO2/surface area, postprandial-carbohydrate oxidation and serum lipid hydroperoxide resembled to that of the S group. Conjugated linoleic acid induced cardiac oxidative stress in both fed conditions, and triacylglycerol accumulation in S-CLA rats. Conjugated linoleic acid depressed myocardial LDH comparing C-CLA with C, and beta-hydroxyacyl-coenzyme-A dehydrogenase/CS ratio, comparing S-CLA with S. In conclusion, dietary conjugated linoleic acid supplementation for weight loss can have long-term effects on cardiac health. Conjugated linoleic acid, isomers c9, t11 and t10, c12 presented undesirable pro-oxidant effect and induced metabolic changes in cardiac tissue. Nevertheless, despite its effect on abdominal adiposity in sucrose-rich diet condition, conjugated linoleic acid may be disadvantageous because it can lead to oxidative stress and dyslipidemic profile. (c) 2007 Elsevier B.V All rights reserved.

Photosynthetic performance of freshwater Rhodophyta in response to temperature, irradiance, pH and diurnal rhythm

Responses of net photosynthetic rates to temperature, irradiance, pH/inorganic carbon and diurnal rhythm were analyzed in 15 populations of eight freshwater red algal species in culture and natural conditions. Photosynthetic rates were determined by oxygen concentration using the light and dark bottles technique. Parameters derived from the photosynthesis-irradiance curves indicated adaptation to low irradiance for all freshwater red algae tested, confirming that they tend to occur under low light regimes. Some degree of photoinhibition (β = -0.33-0.01 mg O2 g-1 DW h-1 (μmol photons m-2 s-1)-1) was found for all species/populations analyzed, whereas light compensation points (lc) were very low (≤ 2 μmol photons m- photons s-1) for most algae tested. Saturation points were low for all algae tested (lk = 6-54 μmol photons m-2 S-1; lS = 20-170 μmol photons m-2 s-1). Rates of net photosynthesis and dark respiration responded to the variation in temperature. Optimum temperature values for net photosynthesis were variable among species and populations so that best performances were observed under distinct temperature conditions (10, 15, 20 or 25°C). Rates of dark respiration exhibited an increasing trend with temperature, with highest values under 20-25°C. Results from pH experiments showed best photosynthetic performances under pH 8.5 or 6.5 for all but one species, indicating higher affinity for inorganic carbon as bicarbonate or indistinct use of bicarbonate and free carbon dioxide. Diurnal changes in photosynthetic rates revealed a general pattern for all algae tested, which was characterized by two relatively clear peaks, with some variations around it: a first (higher) during the morning (07.00-11.00 hours.) and a second (lower) in the afternoon (14.00-18.00 hours). Comparative data between the 'Chantransia' stage and the respective gametophyte for one Batrachospermum population revealed higher values (ca 2-times) in the latter, much lower than previously reported. The physiological role of the 'Chantransia' stage needs to be better analyzed.

Polyphenoloxidase activity in peaches after vibration

The vibration during transportation is one of the main causes of fruit damage. The actual methodologies used for damage evaluation in fruits seem to be subjective, since most of them are based on visual evaluation. In this study the effect of vibration, for one and two hours, on polyphenoloxidase (PPO) activity in peach pulp was investigated. The relation among PPO activity variation, postharvest time and resting time were also considered. Results showed that vibration affects PPO activity. However, it was not possible to correlate PPO activity variation and vibration.

ECLAC Notes Nº 33

Explosive Rise in Remittances from Latin America Emigrants to their Families To Grow Old in Latin America and Caribbean Opinion by José Luis Machinea Highlights: Rural Poverty, a Persistent Issue Indicators Urban Residential Segregation Perpetuates Inequiality Recent Titles Calendar

Notas de la CEPAL Nº 33

Contenidos: Explosivo aumento en remesas que emigrantes latinoamericanos envían a sus familias de origen. Envejecer en América Latina. Columna de Opinión de José Luis Machinea: Compleja agenda de negociaciones comerciales para el 2004. Precisiones: La pobreza rural, una situación que perdura Indicadores Segregación residencial urbana perpetúa desigualdad. Publicaciones Recientes. Calendario de Eventos

Notas de Población Vol.33 N° 83

Las relaciones entre población y pobreza han sido uno de los focos de interés y actividad del Centro Latinoamericano y Caribeño de Demografía (CELADE)- División de Población de la CEPAL desde sus inicios, hace ya 50 años. En este contexto el CELADE organizó la Reunión de expertos sobre población y pobreza en América Latina y el Caribe en noviembre de 2006 con el objetivo general de examinar y analizar las interrelaciones relevantes entre las tendencias y los factores demográficos, la pobreza y las políticas de protección social en la realidad actual de América Latina y el Caribe. Los temas abordados en la reunión fueron: i) los aspectos conceptuales y metodológicos de las interrelaciones entre población y pobreza, con particular referencia a la situación de América Latina y el Caribe; ii) las diversas maneras en que la pobreza afecta y se ve afectada por variables y fenómenos demográficos, distinguiendo entre estos últimos a la salud sexual y reproductiva, el envejecimiento de la población y las migraciones internas e internacionales; iii) los efectos de las políticas orientadas a enfrentar la pobreza, a dar protección social a la población en general y a grupos específicos como las mujeres, los jóvenes y la población indígena; iv) la dinámica de la población de los países de la región y su influencia en los requerimientos sociales presentes y futuros, y v) las políticas de protección social aplicadas en América Latina y el Caribe, en particular su importante aporte a la superación de la pobreza de la población, y la consideración en estas de las realidades y tendencias demográficas. En este y el siguiente número de la revista “Notas de población” se dan a conocer algunos de los estudios presentados en esa reunión. Los diez artículos seleccionados cumplen con varios requisitos —amén de su calidad—, entre otros originalidad y focalización en las prioridades temáticas de la revista. En este número se presentan cinco artículos, el primero de los cuales es un análisis desde una perspectiva conceptual de las relaciones entre población y pobreza en el actual contexto socioeconómico, político y programático. Asimismo, se incluyen un artículo en que se examinan las relaciones entre el comportamiento reproductivo y la pobreza, otro en que se analizan los vínculos entre envejecimiento y pobreza, otro que se centra en la migración internacional y la pobreza y un último consistente en un análisis del efecto de algunos fenómenos demográficos a escala de hogar sobre la probabilidad de salir o de entrar a la pobreza.