繁殖体数量对外来Ralstonia solanacearum 在红壤中入侵潜力的影响

外来种的繁殖体压力因可调控其他入侵影响因素(如外来种特性)而备受入侵生态学家的关注。前人研究指出剂量-响应曲线能够定量分析繁殖体数量对入侵潜力的影响,但关于该曲线形状的认识尚未统一。利用土壤微宇宙,比较了初始接种量为10³（PP3）、10⁵（PP5）、10⁷（PP7）和10⁹ CFU·g^-1（PP9）的青枯病菌Ralstonia solanacearum进入土壤3 和42 d后的存活量,并对初始接种量和存活量之间关系进行拟合,试图探清地下部微生物入侵的剂量-响应曲线状况。研究发现,不同接种量处理外来R. solanacearum接入土壤3 d后的存活量差异显著（P<0.05）,从大到小依次为PP9、PP7、PP5和PP3,初始接种量和存活量之间拟合的剂量-响应曲线为指数型;而外来Ralstonia solanacearum接入土壤42 d后,除了初始接种量为10⁹ CFU·g^-1处理的存活量稍高外,其余处理间差异不显著,此时的剂量-响应曲线呈直线型（斜率约为0）。结果表明,外来病原菌入侵土壤时的剂量-响应关系会随其进入土壤时间的延长而改变,前期为指数型,后期转为直线型,这说明外来R. solanacearum在红壤中的入侵潜力在入侵前期随繁殖体数量增加而呈指数增长,在入侵后期不受繁殖体数量的影响。     

Liver carcinogenesis by diethylnitrosamine in the rat

Diethylnitrosamine was continuously administered to rats at a dose rate of low toxicity. Ninety-two percent of the animals died with multicentrical hepatocellular carcinomata within a narrow and highly reproducible time interval. Discontinuing the carcinogen during the experiment resulted in a prolonged median time until death, a reduced tumor yield, and a lessened slope of the dose-response curve. Partial hepatectomy after discontinuation of the drug did not change either tumor yield or time of death. The obtained dose-response relationships support the concept that carcinogenic effects of single doses are irreversible and cumulative. Daily, low-dose, total-body x-irradiation had no significant effect on the response of rat liver to the carcinogen.     

Anticonvulsants specific for petit mal antagonize epileptogenic effect of leucine enkephalin

The anticonvulsants ethosuximide, sodium valproate, and trimethadione that are specific for petit mal epilepsy abolished in rats the electrical seizure activity and behavioral abnormalities produced by leucine enkephalin, whereas phenobarbital and phenytoin had no effect. The dose-response curve for naloxone against seizure activity induced by leucine enkephalin was the same as that in gamma-hydroxybutyrate-induced petit mal. These data indicate that the epileptic properties of leucine enkephalin are petit mal-like and raise the possibility of involvement of enkephalinergic systems in. The dose-response curve for naloxone against seizure activity induced by leucine enkephalin was the same as that in gamma-hydroxybutyrate-induced petit mal. These data indicate that the epileptic properties of leucine enkephalin are petit mal-like and raise the possibility of involvement of enkephalinergic systems in petit mal epilepsy.     

d-tubocurarine chloride: effect on insects

Injection of d-tubocurarine chloride into certain insects produces complete flaccid paralysis. The site of injection is closely related to the region of primary paralysis. The effect depends on concentration, with distinct differences in the optimum concentrations for various species so far tested. A dose-response curve has been prepared for Calliphora erythrocephala.     

不同给药时间间隔对吗啡诱导小鼠条件性位置偏爱模型的影响

为比较不同给药时间间隔下,同等剂量的吗啡诱导条件性位置偏爱（CPP）模型的差异,为后续抗吗啡依赖药物的筛选奠定基础,本研究建立了不同时间间隔的吗啡诱导CPP模型,（1）吗啡组（24 h）:连续4 d皮下注射,上午注射吗啡（5 mg·kg?1）,下午注射生理盐水,吗啡给药间隔24 h,建立CPP模型;（2）吗啡组（48 h）:连续8 d皮下注射,1、3、5、7 d注射吗啡（5 mg·kg?1）,2、4、6、8 d注射生理盐水,吗啡给药间隔48 h,建立CPP模型。测定造模前后小鼠在伴药箱的停留时间\造模后CPP得分及CPP模型维持时间。结果表明,吗啡给药时间间隔24 h和48 h均能显著增加小鼠在伴药箱内的停留时间,造模后CPP得分明显增加,吗啡组（24 h）小鼠CPP模型能持续5 d,而吗啡组（48 h）小鼠CPP模型能持续15 d。短期内给药时间间隔不影响CPP模型的形成,与吗啡组（24 h）进行长期对比,给药时间间隔为48 h时,CPP模型维持时间更长、不易消退。     

Paradoxical effects after microinjection of morphine in the periaqueductal gray matter in the rat

Paradoxical, concurrent hyper-and hyporeactivity of a profound nature to specific stimuli occurred when 10 micrograms of morphine was microinjected bilaterally into the periaqueductal gray matter of the rat brain. Both effects at this site were dose-dependent. The hyperreactivity (to previously neutral auditory and visual stimuli) was obtained only with intracerebrally injected morphine and never with intraperitoneally injected morphine or with other opiates administered either way. Rapid tolerance to toxic doses of morphine developed at this site, as well as cross tolerance of the hyporeactivity to painful stimuli between routes (intracerebral to intraperitoneal) of morphine administration. Both the hyper- and hyporeactivity were fully reversible by intracerebral injection of naloxone in the periaqueductal gray. Thus, the periaqueductal gray appears to be a major pathway for morphine action.     

Requirement for glycine in activation of NMDA-receptors expressed in Xenopus oocytes

Receptors for N-methyl-D-aspartate (NMDA) are involved in many plastic and pathological processes in the brain. Glycine has been reported to potentiate NMDA responses in neurons and in Xenopus oocytes injected with rat brain messenger RNA. Glycine is now shown to be absolutely required for activation of NMDA receptors in oocytes. In voltage-clamped oocytes, neither perfusion nor rapid pressure application of NMDA onto messenger RNA-injected oocytes caused a distinct ionic current without added glycine. When glycine was added, however, NMDA evoked large inward currents. The concentration of glycine required to produce a half-maximal response was 670 nanomolar, and the glycine dose-response curve extrapolated to zero in the absence of glycine. Several analogs of glycine could substitute for glycine, among which D-serine and D-alanine were the most effective. The observation that D-amino acids are effective will be important in developing drugs targeted at the glycine site.     

Disposition of morphine in man

The disposition of morphine was investigated by means of radioimmunoassay after a single intravenous dose (10 milligrams per 70 kilograms) was administered to 10 adult normal male subjects who had not received other drugs for 2 weeks preceding the study. A multiphasic decline in serum concentrations of morphine occurred. Detectable blood concentrations of morphine, or of a metabolite, or of both persisted for 48 hours after a single intravenous dose.     

Implication of nonlinear kinetics on risk estimation in carcinogenesis

Efforts in estimating carcinogenic risk in humans from long-term exposure to chemical carcinogens have centered on the problem of low-dose extrapolation. For chemicals with metabolites that interact with DNA, it may be more meaningful to relate tumor response to the concentration of the DNA adducts in the target organ rather than to the applied dose. Many data suggest that the relation between tumor response and concentration of DNA adducts in the target organ may be linear. This implies that the nonlinearities of the dose-response curve for tumor induction may be due to the kinetic processes involved in the formation of carcinogen metabolite--DNA adducts. Of particular importance is the possibility that the kinetic processes may show a nonlinear "hockey-stick" like behavior which results from saturation of detoxification or DNA repair processes. The mathematical models typically used for low-dose extrapolation are shown potentially to overestimate risk by several orders of magnitude when nonlinear kinetics are present.     

麦麸添加量和粒度对面团揉混特性的影响

 【目的】研究麦麸对面团流变学特性的影响规律及机理,为麦麸膳食纤维在食品加工中的应用提供依据。【方法】以山农优麦2号小麦面粉为试验材料,通过添加4个粒度（0.16—0.43、0.43—1.0、1.5—2.0、2.0—2.5 mm）,4个添加量（5%、10%、15%、20%）的麦麸,研究麦麸添加量和粒度对面团揉混特性的影响。【结果】随着麸皮添加量的增加,中线峰值高度、中线峰值宽度、8 min中线高度、8 min中线积分面积、中线曲线尾高度和中线曲线尾积分面积显著降低,而8 min带宽、中线曲线尾宽度和中线峰值右侧切线斜率显著增加;添加量处理间对中线峰值时间、中线峰值积分面积和中线峰值左侧切线斜率的影响差异不显著。随着麸皮粒度的增大,中线峰值时间、8 min带宽和中线曲线尾宽度、中线峰值右侧斜率显著增加,但麸皮粒度处理间对其它揉混特性指标的影响差异不显著。【结论】麦麸纤维显著降低面团的中线峰值高度、8 min中线高度、中线峰值积分面积和8 min中线积分面积;而显著增加中线峰值时间和8 min带宽、中线曲线尾宽和中线峰值右侧切线斜率。面团中线峰值时间、8 min带宽和中线曲线尾宽度、中线峰值右侧切线斜率随着麸皮粒度的增大显著增加。     

渭河流域(关中段)经济发展与水环境质量演变关系研究

通过对关中地区经济发展与渭河流域(关中段)水环境质量状况的分析,模拟了关中经济发展和渭河水环境质量演变关系,研究了演变关系的趋势,并提出相应的建议,以期为两者之间协调发展提供科学决策的依据。结果表明,关中地区人均GDP与高锰酸钾指数曲线近似"倒U型"曲线的右半段,走势良好。而人均GDP与氨氮指标的曲线与传统的EKC曲线不相吻合,类似"倒U+U"形。说明关中地区在渭河的治理过程中投入较大,环保措施得当,但近两年在氨氮控制上还需加大力度。     

Morphine: conditioned increases in self-administration in rhesus monkeys

Operant responding in three monkeys was maintained by intravenous presentations of morphine. Nalorphine produced reliable increases in morphine-reinforced responding. With successive daily nalorphine injections there was a decreased latency of self-administration responding for morphine, and substituted saline injections produced conditioned increases in morphine-reinforced responding.     

Cellular adaptation to morphine in rats

The respiration of KCl-stimulated cortical slices of brain from control rats is markedly depressed by morphine, whereas the respiration of those from rats chronically dosed with morphine is unaffected. The results demonstrate an adaptation to morphine at the cellular level which is concomitant with the adaptation of the whole animal to morphine     

Morphine in cow and human milk: could dietary morphine constitute a ligand for specific morphine (mu) receptors?

Morphine has been found in cow and human milk at concentrations of 200 to 500 nanograms per liter. Multistep purification yields a material that has immunological, biological, pharmacological, and chemical properties identical to those of morphine. Similar morphine-like material, which has been tentatively identified in some common plant sources, may be a ubiquitous dietary constituent and a possible source for the material in milk. Since morphine (mu) receptors have a low affinity for enkephalins, and since morphine-like materials have been described in brain and intestine, it is possible that morphine in food may be the source of this material and a normal ligand specific for mu receptors.     

人工林首次间伐时间确定方法的探讨

该文根据林分断面积连年生长量曲线的几何特征，提出以林分断面积连年生长量曲线的下降速度与过峰点和右拐点的直线斜率相等的点作为间伐起始点，以右拐点作为间伐终点，据此，在推导了确定间伐时间的一般方法的同时，具体给出了以Ｒｉｃｈａｒｄｓ生长函数为基础的间伐时间确定方法。最后，以贵州农学院林学系在贵州马尾松分布区内收集的５６９块马尾松人工林常规标准地资料为基础，对以上方法进行了试用。并将试用结果与间伐、密度试验的研究结果对比，说明了该方法的有效性。     

Morphine: radioimmunoassay

The development of a radioimmunoassay for morphine is described.The hapten morphine is made antigenic by coupling it to a protein at the phenolic group of the molecule. Extremely low concentrations of morphine (0.5 nanogram) can be measured by this assay procedure.     

Enhanced morphine analgesia in mice lacking beta-arrestin 2

The ability of morphine to alleviate pain is mediated through a heterotrimeric guanine nucleotide binding protein (G protein)-coupled heptahelical receptor (GPCR), the mu opioid receptor (muOR). The efficiency of GPCR signaling is tightly regulated and ultimately limited by the coordinated phosphorylation of the receptors by specific GPCR kinases and the subsequent interaction of the phosphorylated receptors with beta-arrestin 1 and beta-arrestin 2. Functional deletion of the beta-arrestin 2 gene in mice resulted in remarkable potentiation and prolongation of the analgesic effect of morphine, suggesting that muOR desensitization was impaired. These results provide evidence in vivo for the physiological importance of beta-arrestin 2 in regulating the function of a specific GPCR, the muOR. Moreover, they suggest that inhibition of beta-arrestin 2 function might lead to enhanced analgesic effectiveness of morphine and provide potential new avenues for the study and treatment of pain, narcotic tolerance, and dependence.     

渐近非扩张型半群殆轨道的若干性质

设C为Hilbert空间H的非空子集，G为右可逆半群，在引入渐近非扩张曲线的基础上，对非Lipschitzian右可逆半群的殆轨道做了研究，得到了渐近非扩张型半群殆轨道的几个性质，给出了渐近非扩张型半群殆轨道成为渐近非扩张曲线的条件。     

Effect of deuteration of N--CH3 group on potency and enzymatic N-demethylation of morphine

Substitution of deuterium for the N-methyl hydrogens of morphine produced a significant reduction in the potency and lethality of morphine in mice regardless of the route of administration. There was no effect on the time of onset, maximal effect, or duration of action. N-demethylation by rat liver microsomal enzymes was characterized by a smaller reaction rate constant, a higher energy of activation, and a larger Michaelis constant with respect to the deuterated morphine. These findings indicated that deuteration of the N-methyl group of morphine not only caused reduction in potency, but also a reduction in the rate of oxidative N-demethylation, and a distinct weakening of the binding to the enzyme active centers.     

马尾松人工林标准树高曲线模型的研究

为准确预测林分各径阶高，用试验林和固定样地资料，分析了树高曲线与林龄，立地和密度的关系。结果表明树高曲线随林龄、立地指数的增大、曲线向右上方移动，而与林分密度无关。分析了国内外树高曲线模型研究状况，针对研究中存在的问题，采用再次参数化方法，把立地指数、林龄引入树高曲线模型，创建１３个新模型。用２００块标准地树高曲线资料，采用迭代法分别进行了拟合。经比较，选出有生物学意义扩展后Ｒｉｃｈａｒｄｓ函数，