Effects of ionizing radiation on proliferation and differentiation of osteoblast-like cells

Diagnostic radiation for immediate post-surgical assessment of osseointegrated dental implants has been discouraged, due to the possibility of detrimental effects of ionizing radiation on healing and remodeling of bone. To assess this possibility, we investigated the effects of ionizing radiation on proliferation and differentiation of osteoblasts using osteoblast-like cells isolated from the calvariae of newborn rats (ROB) and a clonal osteoblastic cell line (MC3T3-E1). The cells were exposed on day 3 to a single dose of x-rays at either 40, 100, 400, or 4000 mGy, respectively, from a linear accelerator radiotherapeutic machine (Linac) or a 40-mGy dose from a diagnostic chest x-ray machine. The effects of radiation on cell growth and alkaline-phosphatase-specific (ALP) activity were evaluated at three-day intervals after irradiation up to day 12 in ROB cells, and evaluated at day 12 in MC3T3-E1 cells. At the culture end-point, the effects on formation of bone-like nodules were also evaluated in both ROB and MC3T3-E1 cells. Exposure of 4000 mGy differentially affected the two cell types. It inhibited cell growth and alkaline phosphatase activity, and inhibited DNA content in MC3T3-E1 cells. This irradiation also strongly inhibited the formation of bone-like nodules in ROB cells. On the other hand, exposure of 40-, 100-, and 400-mGy (Linac) and 40-mGy (diagnostic quality) irradiation induced no significant changes in cell growth, alkaline phosphatase activity, and formation of bone-like nodules in ROB cells. These doses also induced no significant changes in DNA content and ALP activity in MC3T3-E1 cells. These results indicate that ionizing radiation at a single dose of up to 400 mGy induces no significant changes in cell growth and differentiation of osteoblast-like cells, at least in vitro. Higher radiation doses (4000 mGy) may exert different effects on cell proliferation and cell differentiation of osteoblasts, depending on the cell types affected. Thus, diagnostic radiation seems to have less effect on proliferation and differentiation of osteoblasts.     

Effects of low doses of ionizing radiation and induced hypothyroidism on the course of pregnancy and the development of the offspring in rats

OBJECTIVES: To determine the appropriate indications and timing for surgery in children with either a perimembranous or a subarterial type of ventricular septal defect (VSD) associated with aortic cusp prolapse. DESIGN: Retrospective review of children with VSD and associated aortic cusp prolapse with or without aortic regurgitation. This review was based on data obtained from clinical findings, two-dimensional echocardiography, cardiac catheterization and angiocardiography. SETTING: Tertiary health care facility with two-dimensional and colour Doppler echocardiographic and cardiac surgery facilities, and a catheterization laboratory. PATIENTS: Forty-eight patients were found to have perimembranous or subarterial VSDs in association with aortic cusp prolapse with or without aortic regurgitation. INTERVENTIONS: All 48 patients had high resolution two-dimensional and colour Doppler echocardiography. Of the 19 patients who underwent surgical closure of their VSD, five also had an aortic valvuloplasty and one had an aortic valve replacement. Cardiac catheterization was performed in 16 of the 19 surgical patients and 12 of the 29 nonsurgical patients. MEASUREMENTS AND MAIN RESULTS: Annual clinical and echocardiographic assessments in the nonsurgical group did not demonstrate increasing aortic insufficiency. Two children in the nonsurgical group showed spontaneous resolution of aortic insufficiency. In the surgical group, four children with VSD and clinical aortic insufficiency had surgery at less than five years of age; two were found to be regurgitant-free, one had trivial clinical aortic insufficiency and the other had echocardiography-only insufficiency. Of the seven surgical patients older than five years with VSD and clinical aortic insufficiency, four were found to be regurgitant-free, one had echocardiography-only regurgitation and two were unchanged. Two children undergoing surgery with VSD and no aortic insufficiency had postoperative echocardiography-only regurgitation, presumably related to cusp deformity from presurgical prolapse. Children with large VSDs with or without aortic cusp prolapse required surgery for indications of shunt size and pulmonary resistance. CONCLUSIONS: For children with small perimembranous VSDs and cusp prolapse, surgery is indicated only if there is clinical evidence of aortic regurgitation and progressive left ventricular enlargement.     

Health risks of ionizing radiation

SETTING: Department of Paediatrics and Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India. OBJECTIVE: To assess the plasma zinc status in children with tuberculosis and to correlate it with nutritional status, activity and severity of disease in relation to antituberculosis therapy. DESIGN: The plasma zinc status of 50 children with different forms of tuberculosis was compared with 10 healthy and 10 malnourished children without tuberculosis at 0, 1, 2, 3 and 6 months of antituberculosis therapy. RESULT: The mean plasma zinc concentration in children with pulmonary tuberculosis (n = 20) was 68.65+/-2.50 microg/dl, central nervous system (CNS) tuberculosis (n = 10) was 64.20+/-3.82 microg/dl, tuberculous lymphadenitis (n = 10) was 63.2+/-3.77 microg/dl and disseminated tuberculosis (n = 10) was 59.0+/-2.75 microg/dl at 0 months. The mean plasma zinc level of healthy children was 129.10+/-3.01 microg/dl and in malnourished non-tuberculous children it was 108.40+/-3.16 microg/dl. Thus children with tuberculosis had significantly lower plasma zinc level than those without tuberculosis, irrespective of their nutritional status (P < 0.001). There was a significant rise in zinc level at the end of 6 months of antituberculosis therapy (P < 0.001). CONCLUSION: Plasma zinc status may prove to be a good objective marker for monitoring the severity of the disease and the response to therapy.     

Targeted inactivation of mouse RAD52 reduces homologous recombination but not resistance to ionizing radiation

The RAD52 epistasis group is required for recombinational repair of double-strand breaks (DSBs) and shows strong evolutionary conservation. In Saccharomyces cerevisiae, RAD52 is one of the key members in this pathway. Strains with mutations in this gene show strong hypersensitivity to DNA-damaging agents and defects in recombination. Inactivation of the mouse homologue of RAD52 in embryonic stem (ES) cells resulted in a reduced frequency of homologous recombination. Unlike the yeast Scrad52 mutant, MmRAD52(-/-) ES cells were not hypersensitive to agents that induce DSBs. MmRAD52 null mutant mice showed no abnormalities in viability, fertility, and the immune system. These results show that, as in S. cerevisiae, MmRAD52 is involved in recombination, although the repair of DNA damage is not affected upon inactivation, indicating that MmRAD52 may be involved in certain types of DSB repair processes and not in others. The effect of inactivating MmRAD52 suggests the presence of genes functionally related to MmRAD52, which can partly compensate for the absence of MmRad52 protein.     

Effect of ionizing radiation on transforming growth factor-beta expression

We report on papers concerning in topic "Diseases of the breast", which were published in the Zentralblatt für Gyn?kologie during the first half of the 20th century. Only 26 publications about senologic problems were found in 44 years. Papers about the mammary theory of eclampsia, mastitis, plastic operations and breast cancer are reported.     

Thoughts on carcinogenic pollution caused by ionizing radiation]

The lacrimal secretion in 99 healthy individuals has been measured by Schirmer's method. The established statistical limits of normal lacrimal secretion were tested in 18 patients submitted to geniculate ganglionectomy because of petrosal neuralgia, in 15 patients with traumatic, in 17 patients with idiopathic, and in 10 patients with herpetic facial palsy. A significant bilateral reduction of lacrimation was found to be as indicative for a unilateral interruption of the parasympathetic iaring. Abnormal unilateral and bilateral values of lacrimation were present in 93% of the traumatic, in 53% of the idiopathic, and in 60% of the herpetic facial palsies respectively. There is evidence that a significantly disturbed lacrimal flow has not only topographic, but also prognostic value in facial nerve palsy.     

Action of ionizing radiation on the functional activity of lymphoid cells]

The contribution of the post-irradiation changes in cyclic nucleotides transformation to the biochemical mechanism of interphase death of irradiated cells is estimated. It is suggested that the biochemical mechanism of interphase death is complex and involves several concurrent trigger mechanisms including cyclic nucleotides regulation system.     

Effects of simultaneous displacive and ionizing radiations and of electric field on radiation damage in ionic crystals

We summarize our recent progress on the formation process of radiation-induced defects, their stability, and cation- and anion-disordering in ionic crystals, such as magnesium aluminate spinel and alpha alumina, under simultaneous displacive and ionizing radiations or under electric field. In those crystals, suppression of dislocation loop formation is observed under simultaneous ionizing and displacive radiations. Cation and anion disordering are also detected through newly developed analytica electron microscopy. Furthermore, the electric field suppresses the formation of dislocation loops and enhances their growth in thinner specimens of ionic crystals. Those results are discussed in terms of the instability of defect clusters under electronic excitation and displacements of structure vacancies and of the interaction between charged defects and electric fields. This article is based on a presentation in the symposium “Terence E. Mitchell Symposium on the Magic of Materials: Structures and Properties” from the TMS Annual Meeting in San Diego, CA in March 2003.     

Effects of acute prenatal ethanol exposure on Bergmann glia cells early postnatal development

The effects of acute ethanol exposure during the prenatal phase of Bergmann glia cell (Bgc) generation were evaluated in three postnatal days. Ethanol exposed rats showed Bgc with reduced soma size, decreased number and width of their fibers, and increased fiber length, when compared with control animals. These differences, however, were significant at postnatal day 12. Our results demonstrate that acute, prenatal exposure to ethanol during critical stages of brain development disrupts Bgc early postnatal development.     

Effects of prenatal exposure to N-methylpyrrolidone on postnatal development and behavior in rats

Pregnant rats (Mol:WIST) were exposed to 150 ppm N-methylpyrrolidone for 6 hours per day on gestation days 7-20. The dose level was selected so as not to induce maternal toxicity or decrease viability of offspring. In the preweaning period, the exposed offspring had a lower body weight and their physical development was delayed. Neurobehavioral evaluation of the male pups revealed no effects on basal functions of the central nervous system. The animals appeared normal and motor function (rotarod), activity level (open field), and performance in learning tasks with a low grade of complexity were similar in the two groups. However, in more difficult tasks such as the reversal procedure in Morris water maze and operant delayed spatial alternation (Skinner boxes), performance was impaired in exposed offspring.     

Effects of ionizing radiation (neutrons/gamma rays) on plasma lipids and lipoproteins in rats

Two closely related genes, the presenilins ( PS ), located at chromosomes 14q24.3 and 1q42.1, have been identified for autosomal dominant Alzheimer disease (AD) with onset age below 65 years (presenile AD). We performed a systematic mutation analysis of all coding and 5'-non-coding exons of PS -1 and PS -2 in a population-based epidemiological series of 101 unrelated familial and sporadic presenile AD cases. The familial cases included 10 patients of autosomal dominant AD families sampled for linkage analysis studies. In all patients mutations in the amyloid precursor protein gene ( APP ) had previously been excluded. Four different PS -1 missense mutations were identified in six familial cases, two of which where autosomal dominant cases. Three mutations resulted in onset ages above 55 years, with one segregating in an autosomal dominant family with mean onset age 64 years (range 50-78 years). One PS -2 mutation was identified in a sporadic case with onset age 62 years. Our mutation data provided estimates for PS -1 and PS -2 mutation frequencies in presenile AD of 6 and 1% respectively. When family history was accounted for mutation frequencies for PS -1 were 9% in familial cases and 18% in autosomal dominant cases. Further, polymorphisms were detected in the promoter and the 5'-non-coding region of PS -1 and in intronic and exonic sequences of PS -2 that will be useful in genetic association studies.     

The nature of the development of autoimmune hemolytic anemia in thymectomized animals exposed to the action of ionizing radiation

To study the character of the experimental autoimmune haemolytic anaemia formation in thymectomized mice, which were irradiated in 1.0 Gy dose. Shown, autoimmune process is result in most aggressive course in thymectomized irradiated mice with autoimmune anaemia than in irradiated mice with autoimmune anaemia. This pathology was connected with decrease of the T-suppressor function. Via 20th weeks the autoimmune process was practically depressed.     

Effects of all-trans-retinoic acid on limb development in the genetic polydactyly mouse

Pdn/+ female mice, mated with Pdn/+ males, were treated with 40 mg/kg body weight of all-trans-retinoic acid (RA) intraperitoneally on day 10 or 11 of gestation, and effects on the limb development were investigated. RA treatment induced the shortening of stylopodium and zygopodium. In the present experiment, we focused on the differences between genotypes in the shortening of stylopodium and zygopodium induced by RA. The effects of RA were milder in Pdn/Pdn than +/- (Pdn/+ and/or +/+) fetuses. The differences between genotypes in the effects of RA were more significant in the group treated on day 11 than on day 10 of gestation. Cartilage of stylopodium and zygopodium was longer in day-13 Pdn/Pdn embryos exposed to RA on day 11 of gestation than those in similarly treated +/- embryos. Many apoptotic cells were observed in the mesenchyme of the forelimb plates at 12 hr after injection of RA on day 11 of gestation. These results suggest that the Pdn gene might influence the apoptosis induced by RA in the mesenchymal cells of the limb, causing milder effects in the shortening of stylopodium and zygopodium in Pdn/Pdn fetuses.     

Germ cell loss in the XXY male mouse: altered X-chromosome dosage affects prenatal development

Attempts to describe the clinical heterogeneity of schizophrenia have consisted of categorical subtyping and a dimensional approach using factor analysis. The latter has yielded three dimensions or subsyndromes: positive, negative and disorganisation. The aim of this study is to explore to what degree these subsyndromes are correlated within 114 sibling pairs (185 individuals) with DSM-III-R schizophrenia or schizo-affective disorder who were assessed for the lifetime presence or absence of the positive, negative, affective and disorganisation subsyndromes. Ratings were based on the core symptoms of each subsyndrome using a modified Krawieka scale. First rank symptoms were also included in the analysis. Coincidence was assessed by application of the binomial theorem to the frequency of occurrence of subsyndromes in this set of siblings. The disorganisation subsyndrome was shared above chance expectation (chi2=9.15, P < 0.01 for all sibling pairs). The significant results for the disorganisation subsyndrome suggest that it may be a suitable phenotypic marker for genetic linkage studies.