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Biomedical subjects

J Maes

Publications and source records attributed to J Maes.

34 records · Page 2Linked to original sources
PubMed1979

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.

Age Factors↗
PubMed1979

[Development of estradiol, progesterone, and prostaglandins E and F2 alpha levels during pregnancy in mice].

17 beta estradiol, progesterone, prostaglandin E and prostaglandin F2 alpha were determined in the plasma of mice at different times of pregnancy. Estradiol displays a preimplantation peak on day 4. Other peaks are visible at the end of the implantation period (day 6) and on day 10. Progesterone increases when implantation begins (day 5). Prostaglandins increase at the beginning of pregnancy and decrease temporarily before implantation. Other peaks are also apparent for prostaglandin E on days 5.5 and 11.

Animals↗
PubMed1978

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.

Aminoisobutyric Acids↗
PubMed1978

Increased ALA dehydratase activity and spleen weight in lead-intoxicated rats. A consequence of increased blood cell destruction.

Lead was given in the diet (1%) to rats from birth and at different times the animals were studies for delta amino levulinic acid dehydratase (ALAD) activity, spleen weight, 59Fe incorporation in erythrocytes and 51Cr-labeled erythrocytes survival. The increased ALAD and spleen weight found after lead treatment is explained as a consequence of a shortened survival, which results in a younger age of circulating erythrocytes with higher ALAD activity.

Animals↗
PubMed1978

Heme synthesis in the lead-intoxicated mouse embryo.

Incorporation of 55Fe and of [14C]glycine was studied in control embryos and mothers and in those which had received lead in the diet from day 7 of pregnancy. Incorporation of Fe into heme of embryonic liver which increases markedly for controls on day 17 of pregnancy was depressed greatly and showed no such increase in lead-intoxicated embryos. These embryos were retarded in growth but had normal heme concentrations in body and liver. Incorporation of glycine into embryonic heme and proteins was not affected. Data on incorporation in the mothers are also presented. It is thought that the impaired synthesis of heme in lead-intoxicated embryos limits their body growth during the late phase of pregnancy.

Animals↗
PubMed1977

Plasma hormone levels in normal and lead-treated pregnant mice.

Dietary lead (0.5%) was given to mice which, after mating, exhibited a vaginal plug. Estradiol, progesterone and prostaglandins E and F 2 alpha were determined in the plasma by radioimmuno assay at different times thereafter. The increase in estradiol and decrease in prostaglandins prior implantation are not greatly altered by lead treatment, whereas the subsequent increase in progesterone and later in estradiol is abolished. It is concluded that the lower number of pregnancies seen in lead-treated mothers is due to a maternal hormonal imbalance caused by lead.

Animals↗
PubMedDate not supplied

Relation between number of hemopoietic stem cells in newborn mice and their radiosensitivity.

Fractionation of a radiation exposure causes greater damage in newborn mice than a single application since it induces radioresistant foetal hemopoietic stem cells to differentiate prematurely to more radiosensitive adult ones. In the present investigation, it was studied whether other agents that give rise to extensive stem cell destruction also lead to such a change in radiosensitivity. Indeed, treatment with cytostatic drugs which reduces the number of spleen colony forming units (CFU-s) and total cells also diminished the D0 value of the surviving cells 3 days later. Adriamycin was most effective in causing damage to hemopoietic stem cells and in inducing micronuclei in bone marrow; it also had the most marked action on the D0 of the surviving stem cells.

Aging↗