Dosimetric calibration and characterization for experimental mouse thoracic irradiation using orthovoltage x rays.

An experimental irradiation setup was designed to deliver a conformal field of thoracic irradiation to mice. The objective is to provide accurate dosimetric evaluation for the experimental setup, which involves a pie cage device holding up to 10 mice with concentric Cerrobend® shields to collimate the beam. The setup uses 250 kVp X rays, and it also involves an air gap, off-axis prescription point and plastic bag containing anesthetic isoflurane gas. The dose rate in cGy/min was determined as follows: absolute dose calibration for the open cone, measurements of output factor and percentage depth dose for the narrow ring-shaped lung aperture, measurements of bag attenuation, and evaluation of other factors specific to the treatment geometry. Dose enhancement at the skin surface caused by electron contamination from shielding material was also studied. The results showed an overall 25 ± 4% drop at lung mid-plane relative to the standard irradiation setup with the open cone. The increased surface dose from scattered electrons was reduced by addition of the air gap and plastic bag. In conclusion, more accurate dose delivery is achieved when correction factors specific to the animal irradiation setup are applied. Care should be taken when experiments with shields in direct contact with animal skin are involved.

Fatty acid composition of the milk lipids of Fulani women and the serum phospholipids of their exclusively breast-fed infants.

We previously reported that, relative to milk of women elsewhere in the world, the lipid fraction of milk of Fulani women in northern Nigeria contained relatively low proportions of alpha-linolenic acid and docosahexaenoic acid (DHA). This led us to question the essential fatty acid status of Fulani infants and the relation between the proportion of critical n-3 and n-6 fatty acids in the serum phospholipids of the mothers, their milk, and the serum phospholipids of their exclusively breast-fed infants. We were also interested in the effect de novo intermediate chain length-fatty acids (C10-C14) had on the proportions of critical and non-essential fatty acids in milk. Capillary gas-liquid chromatography was used to analyze the fatty acid content of the total milk lipids of 34 Fulani women, as well as the fatty acid content of serum phospholipids of the women and their breast-fed infants during the first 6 months of life. The proportions of critical n-3 and n-6 fatty acids in the milk of the Fulani women were adequate, but the proportions of these same fatty acids were low in their exclusively breast-fed infants. The serum phospholipids of the infants contained 18.8% linoleic acid, 0.13% alpha-linolenic acid, 12.8% arachidonic acid, and 3.40% DHA, whereas, the mean percentages of linoleic, alpha-linolenic, arachidonic and DHA in the serum phospholipids of the Fulani mothers' were 21.4, 0.20, 9.79, and 1.97, respectively. There was a strong positive correlation between fatty acid content of serum phospholipids of Fulani women and the fatty acid content of their milk lipids. As the proportion of C10-C14 fatty acids in the milk lipids increased, the proportions of critical n-3 and n-6 fatty acids in milk remained relatively constant; however, proportions of three non-essential fatty acids decreased dramatically. C10-C14 fatty acids do not appear to displace critical n-3 and n-6 fatty acids in milk.