10B concentration evaluation in autoradiography images by optical density measurements.

The quantification and analysis of the tracks forming the autoradiography image of a tissue section is essential for the measurement of particle emitter concentration and distribution (e.g. (10)B) in the sample. Conventional counting techniques cannot be used when track density is high because of track overlapping. A densitometry supported by image analysis method suitable for these cases has been developed. Optical density measurements obtained for boron solutions of known concentrations showed a linear behavior in the range of concentrations under consideration.

Low energy proton irradiation effects on alveolar macrophages from young and aged rats.

A prospective study was undertaken to assess the radiotoxicity of accelerated particles in pulmonary alveolar macrophages (AM). We evaluated the effects of a single dose (10-75 Gy) of an external low-energy (20 MeV) proton beam on cultured AM oxidative metabolism and phagocytic function. Macrophages are the first line of defense against invading pathogens and are known to generate superoxide anion (O2), nitric oxide (NO), and mediators of antimicrobial and antitumoral defense mechanisms. We obtained AM by bronchoalveolar lavage from young (1-2 month old) and aged (9-12 month old) male Wistar rats. Cell viability, phagocytosis, O2 and NO production in control and proton-irradiated cultured AM were evaluated The effect of proton irradiation on cell viability was dose-dependent The higher doses induced a dramatic decrease in viability in the aged population. Phagocytosis increased 1.3-1.4 fold inboth populations irrespective of the dose delivered. Generation of O2 was always higher in the aged population for all the doses assayed and showed no significant variation from the control values. In the young population a clear increase was observed with doses of 25 and 50 Gy. NO production in AM from young animals rose in a dose-dependent manner. Conversely, proton irradiation did not affect NO production in macrophages from aged animals. The results of this study demonstrate that AM isolated from young and aged rats are functionally different and show a distinct behavior when exposed to proton irradiation. These findings suggest that age may condition response and must be taken into account when accelerated particle-radiotherapy protocols are considered as a valid therapeutic option for the treatment of cancer. To the best of our knowledge, this is the first report comparing sham-irradiated and proton-irradiated young and aged AM.

In vivo response to the different LET regions of a 55 MeV helium ion beam.

We evaluated the in vivo response to heavy particle irradiation in rat tail epidermis using silver-stained nucleolar organizer regions (AgNOR) as the end-point. The energy degradation of the beam across the circular section of the tail allowed us to study the damage elicited by two different LET regions of a helium beam, i.e. non-Bragg peak (NBP) and Bragg peak (BP), at different sites on the same sample. The tails were locally irradiated with a helium ion beam at different fluences. AgNOR exhibited marked variations between tissue areas only a few micrometers apart within each tail exposed to a given beam fluence. An analysis of the AgNOR variations in NBP and BP areas of tails exposed to different beam fluences revealed a dose-dependent effect. The AgNOR provide quantitative evidence of differential damage in neighboring tissue areas exposed to different LET regions of a helium-ion beam.

Simultaneous analysis of skin response to the different L.E.T. regions of a 55 MeV helium ion beam.

Rat tail epidermis was used to analyze the in vivo response of a biological system to heavy particle irradiation. The conical configuration of the rat tail gives rise to a variable energy degradation of the beam thus yielding information on the damage elicited by 2 different L.E.T. regions of the helium beam at different sites on the same sample. Cytochrome oxidase activity and epidermal thickness were used to analyze the metabolic and structural radioinduced response. Quantitative evaluation of radiation damage revealed marked variations within a few micrometers of tissue.

Hair follicle response to the variable l.e.t. of a helium ion beam.

A homogeneous population of hair follicles in the rat tail has been used to analyse the in vivo response of a biological system to heavy particle irradiation. The conical configuration of the rat tail gives rise to a variable energy degradation of the beam thus yielding information on the damage elicited by the increasing l.e.t. of the helium beam at different sites on the same sample. By means of scanning electron microscopy three different zones were observed as direct evidence of helium ion penetration in the tail. Quantitative evaluation of radiation damage yielded results concerning hair follicle damage after increasing doses for different regions of the ionization curve.

Effects of X-irradiation on rat hair follicles.

The alterations of normal growth of hair follicles following irradiation of rat tails with X-rays have been analysed. The changes in follicle length are attributed to a series of deleterious events occurring in the hair matrix after irradiation. A dose-dependent reduction of length was demonstrated for a given post-irradiation interval. An approximate exponential response was obtained for all conditions excepting low doses for which a marked reduction of follicle length was observed a short time after irradiation and was ascribed to the depletion of highly radiosensitive cells. At later post-irradiation times this response was obscured by the resumption of follicle growth.

[A new method of preserving chicken eggs at environmental temperature]. / Estudio sobre un nuevo método de conservación de huevos de gallina a temperatura ambiente.

A new method of preserving eggs at room temperature is discussed. The method consists in the "plastification" in situ of the shell, using a liquid synthetic polyvinyl chloride acetate plastic. The plastified eggs and controls were stored under laboratory conditions at 22 degrees C, and the following variables were studied in relation to time: pH of the thick and fluid white, and of the yolk, loss of weight, diameter, yolk index and Haugh units. The results indicated that this new method preserves edible eggs for periods longer than 135 days.