Experimental study and mechanism analysis on bioeffects by nanosecond electromagnetic pulses

The athermal bioeffects caused by nanosecond electromagnetic pulses with body cells was studied by using a broad band transverse EM-wave cell (BTEM CELL). The experimental system and preliminary mechanism analysis were presented.     

猕猴桃品种‘金桃’采收指标与果实软熟品质相关性研究

分别对河南省27个果园的中华猕猴桃（Actinidia chinensis Planch.）品种‘金桃’果实的5项采收生理指标及果实软熟时的8项品质性状进行测定,采用主成分分析法对果实软熟时的品质指标进行综合评分,并对果实的采收生理指标、果实软熟品质指标及综合分值间进行相关性分析。结果显示,采收时的生理指标（干物质、色度角、硬度和可溶性固形物）均与果实软熟品质综合分值间呈极显著相关,其中干物质相关系数最高,为0.437。干物质与体现果实软熟品质的关键指标（可溶性固形物、总糖和糖酸比）均呈极显著性相关。研究结果表明‘金桃’果实采收时,干物质含量是果实软熟时品质的重要评价指标,而可溶性固形物和色度角是评判采收期的辅助指标。     

Regulation of GABAB receptors by histamine and neuronal activity in the isolated spinal cord of neonatal opossum in culture.

The aim of these experiments has been to analyse the properties of receptors for the transmitter gamma-aminobutyric acid (GABA) in developing mammalian nervous system. Changes in responses of GABAB receptors have been measured after alterations of the chemical environment and the level of electrical activity. We have previously shown that when the central nervous system (CNS) of the new-born opossum, Monodelphis domestica, is cultured for three to five days in the presence of histidine, inhibition by baclofen, a GABAB agonist, disappears (Stewart et al. 1991). We have now investigated whether histidine acts indirectly by way of conversion to histamine. As with histidine, culture with 150 microM histamine for five days virtually abolished the inhibition by baclofen. The effects of histidine, as well as histamine, were blocked by mepyramine, a histamine H1-receptor antagonist, and by ranitidine, an H2-antagonist. Tetrodotoxin (TTX), which blocks all electrical activity, protected preparations from the action of histidine but not histamine. Our results suggest that histidine is converted to histamine, which reduces the efficacy of GABAB agonists. We conclude that, in the developing mammalian CNS, transmitter levels and electrical activity can selectively influence the properties of receptors.     

A new method for estimating gross phosphorus mineralization and immobilization rates in soils

Phosphorus availability in soils is controlled by both the sizes of P pools and the transformation rates among these pools. Rates of gross P mineralization and immobilization are poorly known due to the limitations of available analytical techniques. We developed a new method to estimate P transformation rates in three forest soils and one grassland soil representing an Alfisol, an Ultisol, and Andisol, and a Mollisol. Three treatments were applied to each soil in order to separate the processes of mineral P solubilization, organic P mineralization, and solution P immobilization. One set of soils was retained as control, a second set was irradiated with -rays to stop microbial immobilization, and a third was irradiated and then autoclaved, also stop phosphatase activity. All three sets of samples were then incubated with anion exchange resin bags under aerobic conditions. Differences in resin P among the three treatments were used to estimate gross P mineralization and immobilization rates. Autoclaving did not affect resin-extractable P in any of the soils. Radiation did not alter resin-extractable P in the forest soils but increased resin-extractable P in the grassland soil. This increase was corrected in the calculation of potential P transformation rates. Effects of radiation on phosphatase activity varied with soils but was within 30% of the original values. Rates of P gross mineralization and immobilization ranged from 0.6–3.8 and 0–4.3 mg kg-soil^-1 d^-1, respectively, for the four soils. The net rates of solubilization of mineral P in the grassland soil were 7–10 times higher than the rates in forest soils. Mineralization of organic P contributed from 20–60% of total available P in the acid forest soils compared with 6% in the grassland soil, suggesting that the P mineralization processes are more important in controlling P availability in these forest ecosystems. This new method does not require an assumption of equilibrium among P pools, and is safer and simpler in operation than isotopic techniques.     

EPR studies of spin-labeled bovine plasma amine oxidase: the nature of the substrate-binding site.

The carbonyl cofactor of bovine plasma amine oxidase (EC 1.4.3.6), recently shown to be 6-hydroxydopa (also known as topa), has been spin labeled to the extent of one label per enzyme dimer molecule, using 4-amino-2,2,6,6-tetramethylpiperidine-N-oxyl (4-amino-TEMPO) and 4-hydrazino-TEMPO followed by reduction with borohydride. By studying the EPR spectra of the labeled enzyme, it has been deduced that there is no magnetic interaction between the copper and the spin label, and that the spin label is at least 1.3 nm distant from the copper(II) ion in the resting enzyme. The bound label is strongly immobilized, is in a sterically constricted environment, and is not accessible to small anions. Removal of the copper does not alter the EPR spectrum of the label. The results are similar to results for porcine plasma amine oxidase, and show that the copper is not close to, and does not directly interact with, the topa-bound substrate.     

龟纹瓢虫幼虫的食物搜索行为

本试验采用Nakamuta(1982)装置研究龟纹瓢虫Propylea japonica(Thunberg)幼虫的食饵搜索行为,结果表明:1.五种刺激均能激发搜索行为由广域型转换为地域集中型;2.摄食时间与GUT呈正相关;3.摄食的最后一个食饵大小决定GUT的长短;4.摄食后0—15秒的搜索速度小、弯曲角度大.     

Predictors of Condom Use among Peer Social Networks of Men Who Have Sex with Men in Ghana,West Africa

Ghanaian men who have sex with men (MSM) have high rates of HIV infection. A first step in designing culturally relevant prevention interventions for MSM in Ghana is to understand the influence that peer social networks have on their attitudes and behaviors. We aimed to examine whether, in a sample of Ghanaian MSM, mean scores on psychosocial variables theorized to influence HIV/STI risk differed between peer social networks and to examine whether these variables were associated with condom use. We conducted a formative, cross-sectional survey with 22 peer social networks of MSM (n = 137) in Ghana. We assessed basic psychological-needs satisfaction, HIV/STI knowledge, sense of community, HIV and gender non-conformity stigmas, gender equitable norms, sexual behavior and condom use. Data were analyzed using analysis of variance, generalized estimating equations, and Wilcoxon two sample tests. All models were adjusted for age and income, ethnicity, education, housing and community of residence. Mean scores for all psychosocial variables differed significantly by social network. Men who reported experiencing more autonomy support by their healthcare providers had higher odds of condom use for anal (AOR = 3.29, p<0.01), oral (AOR = 5.06, p<0.01) and vaginal (AOR = 1.8, p<0.05) sex. Those with a stronger sense of community also had higher odds of condom use for anal sex (AOR = 1.26, p<0.001). Compared to networks with low prevalence of consistent condom users, networks with higher prevalence of consistent condom users had higher STD and HIV knowledge, had norms that were more supportive of gender equity, and experienced more autonomy support in their healthcare encounters. Healthcare providers and peer social networks can have an important influence on safer-sex behaviors in Ghanaian MSM. More research with Ghanaian MSM is needed that considers knowledge, attitudes, and norms of their social networks in the development and implementation of culturally relevant HIV/STI prevention intervention strategies.