Search results for "gla"

Melatonin formation in different parts of the guinea-pig pineal complex as assessed over 24 hours.

1985

There is morphological evidence that the pineal gland is not a uniformly built organ but rather a complex. In the guinea-pig the gland is 6--7 mm in length and dumbbell-shaped, the proximal part coming into intimate contact with central commissural fibres. The aim of the present 24-hour study was to examine in male guinea-pigs whether the proximal, intermediate and distal areas of the gland are involved in melatonin formation and to compare their rhythmicities. Levels of melatonin in serum and the whole pineal gland as assessed by RIA show day/night ratios of 1 : 1.25 and 1 : 3.3, respectively. Serotonin N-acetyltransferase activity was found to exhibit ratios of 1 : 1.75 (Experiment I) and…

Response of pineal serotonin N-acetyltransferase activity in male guinea pigs exposed to light pulses at night.

1988

Serotonin N-acetyltransferase (NAT), which is crucial for the formation of melatonin, undergoes a typical day/night rhythm in the pineal gland with low levels during daytime and high levels at night. Short pulses of light given at night have been shown to rapidly depress NAT activity in some species, but not in others, the reasons for this difference being unclear. As diurnality and nocturnality of the experimental animals may play a role and since diurnally active animals have been little investigated in this respect, in the present study the diurnally active guinea pig was investigated. Male guinea pigs kept under a lighting regimen of LD 12:12 (lights off at 1700 hrs) were killed between…

Neuropeptide Y effects on pineal melatonin synthesis in the rat

1987

Neuropeptide Y (NPY)-like immunoreactivity is present in the rodent pineal gland. To elucidate possible effects on pineal melatonin synthesis NPY (5 nmol/kg body wt.) was injected into the common carotid artery of male rats. Activities of the melatonin biosynthetic enzymes, serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) were determined by means of radioenzymatic methods. Intact light-exposed animal showed increased NAT activity at day- and at nighttime. Blinded animals showed a more than 10-fold reduction of NAT activity after nocturnal NPY injections. HIOMT activity was only slightly influenced at either time. These results are discussed in terms of the p…

Effects of an earth-strength magnetic field on pineal melatonin synthesis in pigeons

1987

Mechanism of crystallization of fast fired mullite-based glass–ceramic glazes for floor-tiles

2006

Abstract The mechanism of crystallization from a B 2 O 3 -containing glass, with composition based in the CaO–MgO–Al 2 O 3 –SiO 2 system, to a glass–ceramic glaze was studied by different techniques. Glass powder pellets were fast heated, simulating current industrial tile processing methods, at several temperatures from 700 to 1200 °C with a 5 min hold. Microstructural study by field emission scanning electron microscopy revealed that a phase separation phenomenon occurred in the glass, which promoted the onset of mullite crystallization at 900 °C. The amount of mullite in the glass heated between 1100 and 1200 °C was around 20 wt%, as determined by Rietveld refinement. The microstructure …

Effect of boron oxide on the microstructure of mullite-based glass-ceramic glazes for floor-tiles in the CaO–MgO–Al2O3–SiO2 system

2006

Abstract The effect of increasing replacement of Al2O3 by B2O3 in a parent glass on the sintering and further crystallization of mullite was investigated. The composition of the parent glass was chosen in the mullite primary phase field of the CaO–MgO–Al2O3–SiO2 quaternary system. Glass powder pellets were heated under standard (10 °C/min and 2 h of hold time) and fast heatings (25 °C/min and 5 min of hold time) at different temperatures from 700 to 1190 °C. Sintering of B2O3-containing glasses took place in the range between 850 and 1050 °C. X-ray diffraction results showed that mullite formed as unique crystalline phase for glasses containing amounts of B2O3 larger than 6 wt%. For lower a…

Renewable polyol obtained by microwave-assisted alcoholysis of epoxidized soybean oil: Preparation, thermal properties and relaxation process

2019

[EN] The soybean oil polyol (SOP) use as feedstock in the polyurethane industry has been recently emphasized due to its excellent resistance to hydrolysis, which is also applicable in coatings and thermal insulation. In this article, the SOP was obtained by a very fast microwave-assisted alcoholysis of epoxidized soybean oil (ESO). The preparation method, thermal properties, and relaxation process were evaluated. High yields as opening and consumption epoxy group and selectivity of 99.8 mol%, 985 mol%, and 71.2 mol% were obtained. Through titrations, nuclear magnetic resonance and gel permeation chromatography were identified parameters as 0.32 mg KOH.g(-1) acid number, 190 mg KOH.g(-1) hyd…

Prostitución y tratas de blancas

2003

The role of punishment in the works of Adam Smith

2009

The reformation of criminal justice is one of the great themes in Enlightenment culture and concerned its main exponents from Montesquieu to Beccaria, Filangieri, Bentham. One of the traits of greater modernity in the theories worked out by juridical Enlightenment is the resort to the utilitarianinspired economic analysis. Adam Smith doesn't back out of this scientific and civil commitment, but his doctrine appears significantly different though contemporary to juridical Enlightenment, and is also based on economic argumentations. In this work we will look through the main writings which contain the Smithian thought in search of those parts dealing with the theme of punishment and its socia…

Adenoma de células basales de glándula parótida: Caso clínico y revisión de la literatura

2006

El adenoma de células basales de las glándulas salivares es un tipo de adenoma monomorfo de aparición infrecuente. La localización más habitual es la superficie de la glándula parótida. Suele debutar clínicamente como una masa firme y desplazable de crecimiento lento. Histológicamente se observan células isomórficas formando nidos y trabéculas interanastomosadas, con una membrana basal prominente, separadas por un estroma laxo e hialino y ausencia de estroma mixoide o condroide. A diferencia del adenoma pleomorfo, tiende a la multicentricidad y su tasa de recurrencia después de la extirpación quirúrgica es alta. Debido a sus implicaciones pronósticas, el diagnóstico diferencial con el adeno…