The volcano mouse Neotomodon alstoni of central Mexico, a biological model in the study of breeding, obesity and circadian rhythms.

The "Mexican volcano mouse" Neotomodon alstoni, is endemic of the Transverse Neovolcanic Ridge in central Mexico. It is considered as least concern species and has been studied as a potential laboratory model from different perspectives. Two lines of research in neuroendocrinology have been addressed: reproduction and parental care, particularly focused on paternal attention and the influence of testosterone, and studies on physiology and behavior of circadian rhythms, focused on the circadian biology of the species, its circadian locomotor activity and daily neuroendocrine regulation of metabolic parameters related to energy balance. Some mice, when captive, spontaneously develop obesity, which allows for comparisons between lean and obese mice of daily changes in neuronal and metabolic parameters associated with changes in food intake and locomotor activity. This review includes studies that consider this species an attractive animal model where the alteration of circadian rhythms influences the pathogenesis of obesity, specifically with the basic regulation of food intake and metabolism and differences related to sex. This study can be considered as a reference to the comparative animal physiology among rodents.

Daytime restricted feeding modifies the daily regulation of fatty acid ß-oxidation and the lipoprotein profile in rats.

Daytime restricted feeding (2 h of food access from 12.00 to 14.00 hours for 3 weeks) is an experimental protocol that modifies the relationship between metabolic networks and the circadian molecular clock. The precise anatomical locus that controls the biochemical and physiological adaptations to optimise nutrient use is unknown. We explored the changes in liver oxidative lipid handling, such as ß-oxidation and its regulation, as well as adaptations in the lipoprotein profile. It was found that daytime restricted feeding promoted an elevation of circulating ketone bodies before mealtime, an altered hepatic daily rhythmicity of 14CO2 production from radioactive palmitic acid, and an up-regulation of the fatty acid oxidation activators, the α-subunit of AMP-activated protein kinase (AMPK), the deacetylase silent mating type information regulation homolog 1, and the transcriptional factor PPARγ-1α coactivator. An increased localisation of phosphorylated α-subunit of AMPK in the periportal hepatocytes was also observed. Liver hepatic lipase C, important for lipoprotein transformation, showed a change of daily phase with a peak at the time of food access. In serum, there was an increase of LDL, which was responsible for a net elevation of circulating cholesterol. We conclude that our results indicate an enhanced fasting response in the liver during daily synchronisation to food access, which involves altered metabolic and cellular control of fatty acid oxidation as well a significant elevation of serum LDL. These adaptations could be part of the metabolic input that underlies the expression of the food-entrained oscillator.

Evaluation of the dispersive component of the surface energy of active carbons as determined by inverse gas chromatography at zero surface coverage.

The methods to obtain the dispersive component of the surface energy (gamma(s)(d)) of active carbons (AC) from inverse gas chromatography (IGC) measurements usually render values much higher than those obtained by other techniques. In this paper this is ascribed to two factors: (i) the high temperatures at that IGC measurements are carried out and (ii) the microporosity of the AC. It is shown that the temperature dependence of the area of the methylene group is an important factor in the high gamma(s)(d) values. Thus, corrections for this dependence should be considered in the calculations. In relation to microporosity, the cooperative effect of the pore walls is also an important factor to be considered in the evaluation of gamma(s)(d). The values gamma(s)(d) obtained after these corrections have their own physical meaning related to ideal flat carbon surfaces. Critical comments are made about some reported relationships between gamma(s)(d), obtained from IGC, and the BET surface area or pore volume of AC as determined from nitrogen adsorption at 77K. These are based on the very different experimental conditions at which nitrogen and IGC measurements are carried out.

Use of specific surface areas in inverse gas chromatography studies at zero surface coverage.

Inverse gas chromatography (IGC) is frequently used to study adsorption processes at zero surface coverage on microporous activated carbons. This allows to determine the thermodynamic adsorption parameters as equilibrium constants, V(S), standard enthalpies of adsorption, Delta HA degrees, standard free energy of adsorption, Delta GA degrees, and so on. Nevertheless, the surface areas of the adsorbents (microporous carbons in this case) are needed for this purpose. The experimental determination of the surface areas of microporous solids is not univocal and the results depend on the adsorbate employed in the measurements, usually N2 or CO2. This means that the thermodynamic parameters obtained by IGC are subjected to a degree of uncertainty depending on whether N2 or CO2 is used to determine the surface area values. The aim of this paper is to discuss which of the two surface area values is more appropriate to be used in IGC measurements at zero surface coverage. Experimental and theoretical considerations are supplied in a thorough discussion which supports that CO2 surface area value is more appropriate. Thus, it is proposed that this should be used instead of the more generally extended nitrogen specific surface area obtained by the BET equation.

Surface characterisation of plasma-modified poly(ethylene terephthalate).

This paper reports the modifications produced by nitrogen and helium cold plasmas on the surface of PET. The changes have been studied by diffuse reflectance Fourier transform spectroscopy (DRIFTS), atomic force microscopy (AFM) and inverse gas-solid chromatography (IGSC). Nitrogen and oxygen atoms seem to appear on the surface of PET as a consequence of the exposure to the atmosphere after the treatments with plasmas. AFM shows that both plasmas altered in different extent the surface of PET as they break the polymer chains producing low molecular products which appear as bumps on the surface. The surface area and the porosity of PET does not change by plasma treatments even after 15 min. The dispersive component of the surface free energy, gamma(s)(d), decreases after long treatments with nitrogen plasma whereas it remains almost unchanged after long treatment with helium plasma.

Effects of oxygen and carbon dioxide plasmas on the surface of poly(ethylene terephthalate).

Poly(ethylene terephthalate) was exposed to oxygen and carbon dioxide plasmas for different periods of time. The surface-modified samples were characterized by infrared spectroscopy, atomic force microscopy, and inverse gas-solid chromatography. The main difference between both types of plasma was connected to the time scale of degradation, which was much faster when using oxygen plasma. Aggregate globular features were produced by different treatments due to chain scission and further recombination of evolved products. Oxygenated functionalities were introduced in significant amounts after long exposure times to the oxygen plasma. As a consequence, the specific component of the surface free energy was clearly observed to increase after these long treatments.

On the characterization of chemical surface groups of carbon materials.

This paper deals with the use of several methods to characterize the chemical surface groups of carbon materials. Several samples embracing a wide range of acidic and basic characteristics have been used for this purpose. The quantitative determinations have been carried out by selective titrations in aqueous solutions, thermal programmed desorption connected to mass spectrometry (TPD-MS), and ammonia adsorption-desorption, measured by thermogravimetry (TG). The results show some inconsistencies between the different experimental methods. These mainly arise because chemical transformations can be produced during the experiments. Moreover, the textural characteristics of the carbon materials and the existence of pi electrons on the graphitic planes are important factors to be considered in the discussion of the results.

Effect of Some Oxidation Treatments on the Textural Characteristics and Surface Chemical Nature of an Activated Carbon.

The changes produced in an activated carbon by treatment in aqueous solutions of (NH(4))(2)S(2)O(8) and H(2)O(2) are compared with the modifications produced by oxygen plasma. These changes are monitored by measuring the textural characteristics (surface areas, porosity, pore size distributions) and surface chemical groups. The former are studied by N(2) and CO(2) adsorption, mercury porosimetry and hydrocarbon adsorption at zero surface coverage. The chemical surface groups are determined by chemical titrations and FTIR Spectroscopy. The results show large differences between the changes produced by treatment in aqueous solutions and those produced by oxygen plasma. Whereas both treatments in aqueous solution modify the textural characteristics, oxygen plasma maintains the surface area and pore network. However, plasma treatment introduces larger amounts of oxygen chemical groups than treatment in aqueous solution. Copyright 2000 Academic Press.

[Neurosurgical patients in intermediate care. Annual study 1995]. / Paciente neuroquirúrgico en cuidados intermedios. Estudio anual, 1995.

The critical neurosurgical patient requires specialized nursing care. His satisfactory recovery depend an our nurses's work, since their permanence beside the patient and an appropriate treatment make them indispensable. A descriptive and retrospective study of 68 neurosurgical patients admitted at the Intermediate Therapy Unit of the "Gustavo Alderguia" Clinical ans Surgical Teaching Hospital was conducted to determine within the Nursing Care Process (NCP) the main specific nursing procedures and those variables of interest, such as sex, age, type of operation, NCP, mechanical ventilation, medication, evolution, and the nursing procedures carried out. A computerized system was used to analyze the data and the chi-square test of statistical significance. Of the 68 patients studied, 33 were males (p < 0.001). Patients aged 26-30 were the most affected. 13 patients were operated on, and NCP was performed in 20% of the cases. The most important nursing care activities were the vital signs checking, the measurement of diuresis, and the active surveillance of neurological focalization and phlebitis (p < 0.001).