Late changes in biochemistry and blood flow in rat brain locally exposed to 30, 40, or 60 Gy.

Rat brain was exposed to 30, 40 or 60 Gy of roentgen rays and different biochemical and physiologic parameters were assayed from one day to 2 years. The most important changes noted were an intermediate increase in DNA, an intermediate to late--dependent on dose--increase in collagen, a decrease in sialic acid, an early to intermediate increase in serotonin, an increase in cathepsin, an early depression, and intermediate enhancement and a late decrease in alpha amino isobutyrate uptake by brain, and an early reduction, an intermediate--and sometimes late--increase in blood flow. These changes suggest that all three principal systems 2n the brain, nerve cells, glia and vascular system, participate in late changes.

Effect of dietary lead on placental blood flow and on fetal uptake of alpha-amino isobutyrate.

Large amounts of lead administered to pregnant mice can prevent implantation, cause embryonic death or retarded growth. Placental blood supply measured by injected radioactive microspheres is of the order of 23% of the cardiac output for a litter of eight mice on day 18 of pregnancy. In lead-treated animals, not only placental blood flow per embryo but also that per embryo weight is reduced. On the other hand, uptake of a non metabolizable amino acid, alpha amino isobutyrate is not altered by lead treatment. It is noteworthy that about 40% of this amino acid go to the embryo during pregnancy. In view of the normal substrate uptake at a reduced bloodflow it remains undecided whether an insufficient supply by the placenta or a reduction in hem synthesis described earlier is the factor responsible for the retardation in fetal growth.

Intestinal enzyme distribution after supralethal irradiation.

The activity of some intestinal enzymes has been studied after 2 kR irradiation. Brush border enzymes, maltase and leucineaminopeptidase (LAP) show an increase 20 hours after irradiation, while after 72 hours their activities are reduced to very low levels. Lysosomal enzymes show a completely different behaviour: acid phosphatase activity increases only 72 hours after irradiation, whereas beta glucuronidase increases significantly after 20 hours and reaches values two or three times higher than controls after 72 hours. The histologic picture at the first interval after irradiation shows gross alterations in the crypt region, but the villi appear nearly normal. Seventy-two hours after irradiation the whole epithelium is affected and very numerous leukocytes are present in the stroma.

In vivo absorption of carbohydrates in rats with gastro-intestinal radiation syndrome.

Absorption of glucose and sucrose by intestine from supralethally irradiated rats was investigated using an in vivo preparation. An activation of glucose absorption one day day after exposure is followed by a marked fall in glucose and sucrose absorption on day 3. Experiments under different conditions of loading indicate that at 20 hours active transport of glucose is already impaired although the maximum velocity is increased. After 3 days maximum velocity and active transport decrease markedly. Inverstase activity increases after 20 hours, but this is not accompanied by an increased sucrose absorption. The defect in sucrose absorption 72 hours after irradiation is paralleled by a decrease in invertase activity.

Late effects in the central nervous system. A study of biochemical alterations after local exposure of the rat brain to 2 krd.

The brain area of female rats three months of age was exposed to 2 krd of X-rays, and various biochemical parameters were retermined as well as NAD(H) in vivo fluorescence of the brain surface after time intervals from one day to 18 months. During the early period, an increase in the uptake of alpha-aminobutyrate (AIB) and a temporary depression in beta-glucuronidase and cathepsin activity followed by an activation at one month was seen. Somewhat later, acid phosphatase increases. During the intermediate period, DNA and serotonin content and AIB uptake by brain increase, whereas AIB uptake by heart and muscle decreases. A fall in sialic acid content is also noted at this time. During the late phase collagen increases, AIB uptake by brain and liver decreases. No changes were found with respect to NAD(H) fluorescence and its response to breathing of low oxygen concentrations.

[Measurement of the blood flow in various areas of the rat brain by means of microspheres]. / Mesure du flux sanguin dans les différentes régions du cerveau du rat au moyen de microsphères

A method is described to measure regional blood flow in different structures of the rat brain. Microspheres (15 micron) are injected, the brain is sectioned, stained for myeline, radioautographs are prepared and the microspheres in the different structures are counted. The values obtained for different brain structures are counted. The values obtained for different brain regions (cortex, corpus callosum, thalamus hipocampus, hypothalamic region, colliculi, cerebellum, pons, medulla) compare well with those published by others on larger animals. In rats fed 1% of lead from birth, higher blood flow is found in the cortex and a lower one in the interior part of the brain compared to controls.

Influence of phospholids on liver damage. I. Carbontetrachloride poisoning and alterations in amino acid uptake, peroxidation, sialic acid content, and lysosomal enzymes.

Changes in peroxidation, amino acid uptake [alpha-amino isobutyrate (AIB)], sialic acid content and lysosomal enzymes were followed in rats after carbon-tetrachloride enzymes were followed in rats after carbontetrachloride poisoning and treatment with phospholipids (EPL). Uptake and retention of AIB by liver and brain increased after CCI4 poisoning. EPL had no effect on these changes. EPL diminished markedly, however, the excessive peroxidation caused by CC14.

Absorption of radioactive lead (210Pb) by different parts of the intestine in young and adult rats.

Absorption of radioactive lead (210Pb) was studied in an intestinal preparation from adult and young rats. Absorption was higher in the jejunal parts than in the duodenum or colon. Moreover, absorption in young rats was greater than in adults. No difference in absorption was found after loading with large amounts of lead. Maintaining the animals on a low calcium diet decreased rather than increased lead absorption.