Effects and consequences of prenatal irradiation

After a brief introduction about the historic development of risk estimates and maximum permissible doses of ionizing radiation, the risks of prenatal irradiation are discussed. Experimental data mainly obtained with mice indicate that the most important risk exists during the period of organogenesis and concerns the induction of malformations. Although in man this period lies between about 10 and 80 days after fertilization for most organs, the main development of the brain occurs later, namely between the 8th and 15th week after conception. Data from Japanese victims of the atomic bomb explosions above Hiroshima and Nagasaki indicate that during development the brain is the most sensitive organ to irradiation and maximal sensitivity is found between the 8th and 15th week after fertilization. A dose of one Gray received during this period induces a severe mental retardation in about 45% of the newborns. The dose response relationship is not significantly different from a linear one without a threshold dose. Studies of intelligence and school performance have shown that 1 Gray received during the 8th-15th week causes a shift of the average intelligence of about 30 points. Irradiation before the 8th week and after the 25th week had no effect on intelligence or mental retardation. During the 16th and 25th week sensitivity was about one fourth of that during the 8th-15th week. Although the irradiation of the embryo and fetus should be avoided as much as possible, the new data have led to an abandonment of the so-called 10-day rule. Generally an accidental irradiation of the embryo or fetus of less than 5 cGy is not considered as a medical indication for abortion. Retrospective studies showed that mothers from children who died from leukemia or other childhood tumors, had been subjected to a diagnostic irradiation of the pelvis or lower abdomen more frequently than mothers from children that did not develop a tumor. It has been estimated that prenatal sensitivity for induction of leukemia and tumors is higher than sensitivity after birth. However, it is still in discussion, whether the relationship between prenatal irradiation and a higher incidence of tumors is of a causal nature.     

Microwave irradiation and instrumental behavior in rats: Unitized irradiation and behavioral evaluation facility

A facility for the exposure of small animals to pulse-modulated microwave radiation ( PM MWR ) concurrent with their performance of operant behavioral tasks is described. The computer-managed facility comprises an array of 32 individual waveguide exposure cells, each enclosing instrumental conditioning apparatus within a plastic subhousing. The distribution of the microwave electric field intensity within the waveguide was measured by a nonperturbing probe and the modifications induced by the behavioral apparatus and animal within the waveguide determined. Input and interior voltage standing wave ratios are presented to characterize the design of the chambers and to demonstrate the suitability of the chambers for whole-body irradiation of rat. The specific absorption rate (SAR) is presented utilizing data derived from incremental thermometric examination of saline loads and of selected sites in rat carcasses. This is compared with the whole-body SAR derived from the input/ output energy balance equation for the waveguide. The results of continuous monitoring of the SAR by the latter method, while unrestrained rats were engaged in operant and exploratory behavior within the waveguide, are utilized to derive a relationship between chamber input power and the dose rate for adult rats behaviorally active within the waveguide. From these data, we conclude that the experimental array provides a practical method for exposing a large number of animals to PM MWR for long periods of time and coincident with the establishment and/or performance of complex operant behavior.     

Immuno-cyto-adhesion and sublethal irradiation]

1. In sublethally irradiated CBA mice, the relative and absolute numbers of spontaneous rosetts forming cells against sheep erythrocytes are markedly decreased in bone marrow. 2. The decrease of the absolute number of spontaneous RFC is also important in the spleen in spite of an increase of the RFC relative number above the normal values between the 8th and 12th day after irradiation. 3. The graft of normal bone marrow cells immediately after irradiation of the shielding of a medullary area during irradiation promotes the recovery of the immunocytoadherence capacity of the bone marrow cells but not of the spleen cells.     

Formaldehyde fixation and microwave irradiation

Summary Formaldehyde is the most commonly used fixative in pathology laboratories. However, due to time pressures, this fixative is often not optimally exploited. the majority of biopsies are only partly fixed when histoprocessing is started, with adverse effects. This paper reports how formaldehyde fixation is improved, by using 1.5 min of microwave irradiation of tissue previously soaked for four hours in the fixation solution. It is argued that this beneficial effect of microwave irradiation can be attributed to the acceleration of the reaction of formaldehyde to the tissue. Formation of free formaldehyde, by the dehydration of methylene glycol present in the tissue when the irradiation starts, is also enhanced. Five different formaldehyde-containing fixatives were evaluated, using five different working protocols. Spleen was taken as a suitable tissue for these tests. The technique described leads to uniform microscopical results. It is a simple method and is suitable for use in routine laboratories.     

Induction of chromosome shattering by ultraviolet irradiation and caffeine: comparison of whole cell and partial-cell irradiation

Synchronized and asynchronously growing cells of a V79 sub-line of the Chinese hamster were either partial-cell irradiation (λ, 254 nm) or laser-UV-microirradiated (λ, 257 nm). Post-incubation with caffeine (1–2 mM) often resulted in chromosome shattering, which was a rare event in the absence of this compound. In experiments with caffeine, the following results were obtained.

Shattering of all the chromosomes of a cell (generalized chromosome shattering, GCS) was induced by partial-cell irradiation at the first post-irradiation mitosis when the UV fluence exceeded and “threshold” valued in the sensitive phases of the cell cycle (G1 and S). GCS was also induced by laser-UV-microirradiation of a small part of the nucleus in G1 of S whereas microirradiation of cytoplasm beside the nucleus was not effective. An upper limit of the UV fluence in the non-irradiated nuclear part due to scattering of the microbeam was experimentally obtained. This UV fluence was significantly below the threshold fluence necessary to induce GCS in whole-cell irradiation experiments. In other cells, partial nuclear irradiation resulted in shattering of a few chromosomes only, while the majority remained intact (partial chromosomes shattering, PCS). G1/early S was the most sensitive phase for induction of GCS by whole-cell and partial nuclear irradiation. The frequency of PCS was observed to increase when partial nuclear irradiation was performed either at lower incident doses or at later stages of S. We suggest that PCS and GCS indicate 2 levels of chromosome damage which can be produced by the synergistic action of UV irradiation and caffeine. PCS may be restricted to microirradiated chromatin whereas GCS involves both irradiated and unirradiated chromosomes in the microirradiated nucleus.     

Breast reconstruction following lumpectomy and irradiation

The traditional approach to breast cancer has been the surgical mastectomy. The cosmetic deformity resulting from this procedure has led to the development of our current methods of breast reconstruction. The inherent attraction of lumpectomy and radiotherapy has been its equation with improved cosmesis. This procedure may be an effective alternative to surgery from the cancer perspective and does produce, in the majority of patients, an acceptable cosmetic result. However, this paper demonstrates that it may produce a result that is less optimal than mastectomy with postoperative breast reconstruction. The etiology of the increased deformity can either be the localized lumpectomy with marked internal derangement of breast volume or the radiation therapy itself. In addition, those who develop a combination require a solution to both. We describe three patients who illustrate these problems and believe that a greater awareness of these potential complications should be available to aid patients in choosing their cancer treatment.     

Biological effects of phytoecdysteroids and chronic low-dose irradiation

The influence of serpistene in dose of 5 and 50 mg/kg on chronic low-dose gamma-irradiation (22.6 cGy) effects on cytogenetic (abnormal sperm cell, marrow bone micronucleus) and function and morphology (thyroid and adrenal glands) parameters of mice was estimated. The serpistene modifies effects of gamma-irradiation depends on the administration regime and a dose of the substance. The most expressive radioprotective effect on endocrine organs after serpistene prophylactic administration was found. The prophylactic dose was 5 mg/kg for adrenal gland and both doses--for thyroid gland. The most expressive radioprotective effect on marrow bone cells after serpistene therapeutic administration in a dose of 5 mg/kg was found. The most expressive antimutagenic effect on somatic and germinal cells of prophylactic and therapeutic administration in a dose of 50 mg/kg was found.     

Biochemical reception and ionizing irradiation of the body

The authors present the idea of the importance of studying the mechanism of biochemical reception of biologically active compounds (BAC) particularly the reception of prostaglandins after the effect of ionizing radiation on eucaryotes as a factor playing a significant role in understanding the radiation sickness pathogenesis. The perspectives of studying BAC reception are prognosticated for searching new radiomodifying agents (radioprotectors and means for treating radiation sickness).