The effect of 100 Hz magnetic field combined with X-ray on hepatoma-implanted mice

Our previous cellular experiments demonstrated that 100 Hz magnetic field (MF) was effective at enhancing apoptosis of liver cancer cells BEL‐7402 induced by X‐ray irradiation. This study was performed to further explore the possible synergism between 100 Hz MF and X‐ray in treatment of hepatoma‐implanted Balb/c mice. 100 Hz MF exposure with a mean flux density of 0.7 mT was performed inside an energized solenoid coil. Six MV X‐ray irradiation was generated using a linear accelerator. Tumor growth and survival of mice implanted with H22 cells were evaluated by measuring the tumor diameters and overall days of survival. Six groups treated with 100 Hz MF or X‐ray alone or a combination of MF and X‐ray were examined. Furthermore, the effects of different numbers of MF exposure periods on tumor growth and mice survival were examined when combined with 4 Gy X‐ray. Data referring to overall survival days and tumor diameters of the above groups were compared using log‐rank test and Student's t‐test. Our results showed that five periods of combined 100 Hz MFs and 4 Gy X‐ray could significantly extend the overall days of survival and reduce the tumor size compared to MF or X‐ray alone. Also, a greater number of 100 Hz MF exposure periods could further improve the survival and inhibit tumor growth in hepatoma‐implanted mice when combined with 4 Gy X‐ray. In conclusion, these findings suggested that 100 Hz MF could possibly synergize with 4 Gy X‐ray in terms of survival improvement and tumor inhibition in hepatoma‐implanted mice. Bioelectromagnetics 32:322–324, 2011. © 2011 Wiley‐Liss, Inc.     

A direct method for determination of the time integral of corticosterone availability in interstitial fluid of rats

A novel method for direct determination of the time integral of free corticosterone levels in interstitial fluid was used to measure corticosterone availability at rest and during free-operant shock-avoidance (SA) training in male rats. The method employs a subcutaneously implanted device to continuously accumulate the free hormone at a rate proportional to local concentration. The proportional rate of accumulation is maintained by providing mass-action corticosterone binding capacity within the device such that the device establishes a diffusion gradient for free corticosterone. The rate of uptake is limited so as to avoid disturbing equilibrium between free and bound hormone in the environment of the device. Corticosterone accumulation increased to 3× baseline during SA and was dexamethasone suppressible. These findings demonstrate the utility of a method uniquely combining specific measurement of free hormone with time integration to yield estimates of hormone availability during behavioral performance by an untethered subject. The method is suggested to be applicable to measurement of an extremely wide variety of drugs and hormones, under generally nonconstraining conditions.     

AN INTRAPERITONEAL RADIO TRANSMITTER FOR SEA OTTERS

A small intraperitoneal radio transmitter was developed and used successfully in California sea otters. The transmitter weighs about 120 g and has an internal antenna. Thirty-five implanted transmitters were located for an average of 526 d. The carcasses of five animals that died were recovered; there were no complications associated with the transmitters in these individuals. Reproductive performance of the adult females with implanted transmitters appeared normal. The main advantages of this transmitter are its reliability and long life. It has enabled the collection of significant new information on California sea otters.     

Effects of surgically implanted transmitters on swimming performance, food consumption and growth of wild Atlantic salmon parr

Experiments were conducted on wild Atlantic salmon Salmo salar parr to determine the effect of surgically implanted dummy transmitters on swimming performance, food consumption and growth. Swimming performance of tagged fish (tag 1·7–3·7% of fish mass) was similar to that of control fish 1, 5 and 10 days after surgery. Negative effects on growth, however, were found up to day 36 of a 45 day experiment (tag 0·9–2·6% of fish mass). Consumption rates were similar between tagged and control fish and did not explain differences in growth.     

Effects of implanted dummy transmitters on mortality, growth and tissue reaction in rainbow trout, Salmo gairdneri Richardson

For the first time, workers in the U.K. with a Home Office licence may surgically implant transmitters into wild fish in order to track them. A laboratory study was designed to investigate the effects of intraperitoneally implanted transmitters on rainbow trout. No significant difference in mortality or growth occurred between control, sham-implanted and implanted groups of fish over a 7-month period. Transmitters became encapsulated by connective tissue, the composition of which is described. Three fish expelled transmitters via the body wall without subsequent mortality or morbidity. Histological evidence suggests pressure necrosis of the body wall adjacent to the tag to be the mechanism of expulsion. With good surgical procedure, intraperitoneal implantation appears to provide a suitable technique for attaching transmitters to fish, and may be preferable to existing methods for many fish.     

N+离子注入长豇豆对硝酸还原酶及氮代谢的影响

不同剂量的Ｎ＾＋离子注入长豇豆种子。豇豆开花结荚后，低剂量Ｎ＾＋离子处理能增加叶片的ＮＲ活性，促进ＮＯ＾－３－Ｎ向氨基酸和蛋白质的转化；减少ＮＯ＾－３－Ｎ的积累，提高叶片蛋白质和氨基酸含量。高剂量Ｎ＾＋离子处理抑制官种转化，豇豆结荚后期，叶片ＮＯ＾－３－Ｎ积累增多。     

Thermal mitigation of Pseudomonas aeruginosa biofilms

Bacterial biofilms infect 2–4% of medical devices upon implantation, resulting in multiple surgeries and increased recovery time due to the very great increase in antibiotic resistance in the biofilm phenotype. This work investigates the feasibility of thermal mitigation of biofilms at physiologically accessible temperatures. Pseudomonas aeruginosa biofilms were cultured to high bacterial density (1.7?×?10⁹ CFU cm^?2) and subjected to thermal shocks ranging from 50°C to 80°C for durations of 1–30 min. The decrease in viable bacteria was closely correlated with an Arrhenius temperature dependence and Weibull-style time dependence, demonstrating up to six orders of magnitude reduction in bacterial load. The bacterial load for films with more conventional initial bacterial densities dropped below quantifiable levels, indicating thermal mitigation as a viable approach to biofilm control.     

簇生沿丝伞液体发酵培养及其发酵物体内抗肿瘤活性研究

采用中心组合旋转设计法确定了簇生沿丝伞液体深层培养菌丝体的最佳方案。采用H22荷瘤小鼠进行体内抗肿瘤试验,对簇生沿丝伞发酵物的抗肿瘤活性进行了探究。结果表明,当培养基配方为麦芽糖59.27g/L,蛋白胨:酵母粉=1:1为8.04g/L,磷酸二氢钾:硫酸镁:硫酸铵=1:1:1为2.27g/L时,生物量达到最高,为15.06g/L。簇生沿丝伞发酵物的抑瘤率与剂量存在明显的量效关系,200mg/kg时,抑瘤率达最高,为54.71%,且白细胞数和IL-2的含量与对照组相比均显著增高。