Long-term effects of dietary isoflavones on uterine gene expression profiles

Isoflavones (ISOs) are bioactive food ingredients of the traditional East Asian diet and currently discussed as alternatives to classical hormone replacement therapies and for reducing the prevalence of hormone-dependent cancers. Although there are many studies on ISOs, not much is known about their long-term effects.Therefore, we performed an animal experiment analyzing the effects of three different diets: a phytoestrogen-free diet, a diet supplemented with genistein (700 μg/g diet) and an ISO-high diet (232 μg daidzein and 240 μg genistein/g) at two distinct time points, juvenile (21 days) and adult (97 days). Exposure started prior to mating of the parents and throughout the life of the offspring.We observed a stronger increase of uterine wet weights in juvenile offspring with genistein exposure (1018 ± 350 mg/kg BW) than with ISO-high diet (497 ± 133 mg/kg BW). Whereas the expression of proliferation related genes (PCNA; Ki67; IGF-1; IGF-1R), analyzed by real-time-qPCR and Western blot, were significantly down-regulated in juvenile animals exposed to genistein. Additionally, genistein exposure led to estrogenic responses, observed upon increase of complement C3 and decrease of estrogen receptors gene expressions, while the exposure to ISO-high diet did not show these effects.In conclusion, both the time point on which phytoestrogen exposure starts together with the composition of the ingested phytoestrogen containing diet are of great importance for the biological response of the offspring.     

Normalizing the thermal effects of radiofrequency radiation: body mass versus total body surface area

The current guideline for exposure to radiofrequency radiation (RFR) was developed through assessment of the biological effects data collected primarily from the rat. The consensus that a lack of hazardous biological effects occurred below a whole-body-averaged specific absorption rate (SAR) of 4.0 W/kg led to the proposition of a 0.4 W/kg guideline with a built-in safety factor of 10. This paper demonstrates that if the RFR absorption rate in the rat had been normalized with respect to total body surface area rather than body mass, the exposure guideline would be 2.3 W/m2, which translates to an SAR of approximately 0.06 W/kg for an adult human. It is further shown that a given RFR absorption rate, normalized as a fraction of a species' heat loss per unit of surface area, is independent of body mass over a range of 0.03-100 kg; however, a normalization of the RFR absorption rate to heat loss per unit of body mass is highly dependent on the species' mass. Normalizing the rate of RFR absorption to the surface area of the rat indicates that the current RFR exposure guideline of 0.4 W/kg may be too high.     

Thermoregulatory responses of the immature rat following repeated postnatal exposures to 2,450-MHz microwaves

This study was designed to determine the changes that occur in the thermoregulatory ability of the immature rat repeatedly exposed to low-level microwave radiation. Beginning at 6-7 days of age, previously untreated rats were exposed to 2,450-MHz continuous-wave microwaves at a power density of 5 mW/cm2 for 10 days (4 h/day). Microwave and sham (control) exposures were conducted at ambient temperatures (Ta) which represent different levels of cold stress for the immature rat (ie, "exposure" Ta = 20 and 30 degrees C). Physiological tests were conducted at 5-6 and 16-17 days of age, in the absence of microwaves, to determine pre- and postexposure responses, respectively. Measurements of metabolic rate, colonic temperature, and tail skin temperature were made at "test" Ta = 25.0, 30.0, 32.5, and 35.0 degrees C. Mean growth rates were lower for rats exposed to Ta = 20 degrees C than for those exposed to Ta = 30 degrees C, but microwave exposure exerted no effect at either exposure Ta. Metabolic rates and body temperatures of all exposure groups were similar to values for untreated animals at test Ta of 32.5 degrees C and 35.0 degrees C. Colonic temperatures of rats repeatedly exposed to sham or microwave conditions at exposure Ta = 20 degrees C or to sham conditions at exposure Ta = 30 degrees C were approximately 1 degrees C below the level for untreated animals at test Ta of 25.0 degrees C and 30.0 degrees C. However, when the exposure Ta was warmer, rats exhibited a higher colonic temperature at these cold test Ta, indicating that the effectiveness of low-level microwave treatment to alter thermoregulatory responses depends on the magnitude of the cold stress.     

Low-Level Microwave Irradiations Affect Central Cholinergic Activity in the Rat

Sodium-dependent high-affinity choline uptake was measured in various regions of the brains of rats irradiated for 45 min with either pulsed or continuous-wave low-level microwaves (2,450 MHz; power density, 1 mW/cm2; average whole-body specific absorption rate, 0.6 W/kg). Pulsed microwave irradiation (2-microseconds pulses, 500 pulses/s) decreased choline uptake in the hippocampus and frontal cortex but had no significant effect on the hypothalamus, striatum, and inferior colliculus. Pretreatment with a narcotic antagonist (naloxone or naltrexone; 1 mg/kg i.p.) blocked the effect of pulsed microwaves on hippocampal choline uptake but did not significantly alter the effect on the frontal cortex. Irradiation with continuous-wave microwaves did not significantly affect choline uptake in the hippocampus, striatum, and hypothalamus but decreased the uptake in the frontal cortex. The effect on the frontal cortex was not altered by pretreatment with narcotic antagonist. These data suggest that exposure to low-level pulsed or continuous-wave microwaves leads to changes in cholinergic functions in the brain.     

Effect of short-and long-term exposure to low environmental temperature on brain regional GABA metabolism

Single exposure of adult male rats to low environmental temperature (LET, 12 ± 0.5°C) for 2 h significantly increased the hypothalamic and striatal GABA levels without affecting those in other regions of brain. The activity of glutamate decarboxylase (GAD) was elevated in hypothalamus (H) and corpus striatum (CS) under these conditions. GABA accumulation rate (measured with ethanolamine-O-sulfate, an inhibitor of GABA-transaminase) was also increased in both H and CS of rats exposed to LET for 2 h. Unlike after a single exposure, the repeated exposure (2 h/day) for 7, 15, and 30 onsecutive days did not change the hypothalamic GABA metabolism. No change in GABA metabolism was observed in CS when rats were repeatedly exposed to LET for 7 consecutive days. Prolongation of repeated exposure to LET (2 h/day) for 15 and 30 consecutive days decreased the striatal GABA level and increased the activity of GABA-transaminase, although GAD activity was not altered under these conditions. These results suggest that single exposure to LET accelerates GABA synthesis and may reduce the GABAergic activity in both H and CS; whereas repeated exposure to LET for 15 or 30 consecutive days enhances GABAergic activity with the stimulation of GABA utilization only in CS without affecting its synthesizing process. Thus, it may be suggested that the hypothalamic and striatal GABA system may play a characteristic role in response to short-and long-term exposure to LET.     

Analysis of electric and magnetic fields leaking from induction heaters

Results are presented of an investigation on electric and magnetic fields leaking from inductive (magnetic) heaters that are used for thermal processing of high-power electron tubes and lasers in an industrial plant. Measurements of electric and magnetic fields were done using both commercially available and laboratory-developed instrumentation. Isotropic H-field sensors were developed to allow quantitative evaluation of high-intensity magnetic fields. Ten induction heaters with nominal A.C. power ranging from 2.5 kW to 15 kW and operating at frequencies between 300 kHz and 790 kHz were surveyed. Electric field strengths up to 8 kV/m and magnetic field strengths up to 20 A/m were measured.     

+G_z暴露时,家兔心率和心水平动脉压关系的研究

在动物离心机上测定了7只轻度麻醉家免暴露于+G_Z时心、眼水平动脉压和心率的变化。+G_Z作用5-12s时、心水平动脉压(HABP)降至最低水平,然后开始代偿性回升。当+G_Z增大到一定值时,于加速度达峰值后,HABP降为0 mmHg、并在峰值后5.5±1.7s降到最大负值,继之代偿性升为正值,并常再度降为负值。我们称HABP的这种变化状态为“临界状态”。+G_Z暴露时,心率以两种型式发生改变:第一种,随着G值增大,心率发生不同程度增快,当加速度达某一G值时,心率突然减慢至2次/秒左右;第二种,当G值≥3时,在暴露过程中,心率逐渐减慢,并在某一G值,心率减慢到2次/秒左右。心率和HABP关系密切。当HABP达临界状态时,心率减慢至2次/秒左右并出现明显节律不整。以心率减慢到2次/秒左右作为家免+G_Z耐力终点是合适的,该指标规律性强,重复性好,实验方法对动物无损伤又易实施。按此标准,测得7只家免的+G_Z耐力为4.85±0.47G。     

A hypothesis on p34cdc2 sequestration based on the existence of Ca(2+)-coordinated changes in H+ and MPF activities during Xenopus egg activation [corrected]

The entry into, and exit from, mitosis are controlled by a universal M-phase promoting factor (MPF) composed of at least p34cdc2 and a cyclin. Embryonic systems are convenient for studying the association and dissociation of the active MPF complex because oocytes and eggs are naturally arrested at a specific point of the cell cycle until progression to the next point is triggered by a hormonal signal or sperm. In amphibians, eggs prior to fertilization are arrested at metaphase 2 of meiosis due to the presence of a stabilized MPF complex. Fertilization (egg activation) produces a transient increase in intracellular free Ca2+, a propagating Ca2+ wave, that specifically triggers the destruction of cyclin, leading to MPF inactivation and entry into the first embryonic inter-phase. We have recently shown that intracellular pH (pHi) variations in amphibian eggs, a large increase at fertilization and small oscillations during the embryonic cell cycle, were temporally and functionally related to the corresponding changes in MPF activity. In addition, the recent finding that the pHi increase at fertilization in Xenopus eggs is a propagating, Ca(2+)-dependent pH wave which closely follows the Ca2+ wave, together with the absence in the egg plasma membrane of pHi-regulating systems responsible for that pHi increase, suggest the existence of cortical or subcortical vesicles acidifying in the wake of the Ca2+ wave, thus producing the pH wave.(ABSTRACT TRUNCATED AT 250 WORDS)     

A mite survey in the dumpsters for urban solid rubbish

Summary The presence of house dust mites and storage mites in dumpsters was investigated in 3 different areas of Venice hinterland. The aim of this study was to find a relationship between some reported respiratory symptoms among 6 workers who were responsible for moving the dumpsters to the truck and the bio-aerosol released from such operation. These symptoms were closely related to the work and after allergological evaluation we found sensitisation to house dust mites in all 6 employees. The mine exposure in the workplace was assessed by a standardized sampling and analysis of dust obtained after brushing the inside surfaces of dumpsters. In 50% of the specimens (10/20) we found mites belonging to the following families: Pyroglyphidae (Dermatophagoides spp.), Acaridae (Acarus siro) and a lower amount of Cheyletidae (Cheyletus spp.). An indirect test (guanine test) was also performed and gave positivity in 16 dust samples (80%). The insides of dumpsters showed to be an optimal environment for mites survival and reproduction because of cracks and grooves on the walls, the high humidity level and the presence of mould. These mites probably come from dwelling places and other environments (markets, slaughters-houses, farms, etc.). This suggests that mites allergens can be released during rubbish discharging from the dumpsters and represent a possible risk for the employees.     

冲击波负压对大鼠肺致伤效应的初步观察

观察了不同的冲击波负压峰值对大鼠肺的影响。各种条件下的冲击波负压值可由负压发生装置来模拟调节,这种装置可满足化爆、核爆和爆炸性减压下负压参数的一般要求,参数稳定,重复性好。冲击波负压峰值范围为-13～-90kPa,下降时间为1～90ms,持续时间为14～2 000ms。6组Wistar系大鼠,分别暴露在-47.2～-84.0kPa的冲击波负压环境中,伤后立即解剖动物,重点观察肺伤情。实验结果显示,在上述冲击波负压环境中,肺可出现从无伤至极重度伤;出血、充血以及肺表面压痕酷似肺冲击伤的病理表现。随着冲击波负压峰值的变化,各组肺伤情亦随着变化,冲击波负压峰值(△P)和减压倍数(P_i/P_a)分别与肺出血面积和动物死亡率相关显著或非常显著。本实验提示,一定条件下的冲击波负压具有明显的致伤作用,且伤情变化范围与超压所致肺伤情变化范围相同,超压和冲击波负压在一定条件下可通过伤情指标等效。