血液磁极化疗法对糖尿病兔胰岛功能的影响

目的观察血液磁极化疗法(简称血磁治疗)对糖尿病(DM)的治疗效果和对胰岛功能的影响。方法制备了四氧嘧啶DM兔模型20只,随机分为两组,即DM模型血磁治疗组及DM模型未治疗组,同时设立正常对照组10只,分别测定治疗前后空腹血糖(FPG)、糖化血红蛋白(HbA1c)、胰岛素(INS)及C-肽(C-P),并于观察期结束后处死动物取胰腺组织常规石蜡包埋切片,行HE及Mallory三色法特殊染色观察3组胰岛形态学变化。结果血磁治疗显著降低DM兔的FPG(P<0.001)。DM治疗组INS及C-P水平较治疗前明显升高(P<0.01),与未治疗组相比差异显著(P<0.05)。胰岛病理改变可见治疗组β细胞数量明显多于DM未治疗组,提示血磁疗法具有促进胰岛修复,改善胰岛功能的作用。结论血磁疗法能够促进DM时受损胰岛组织的修复,改善胰岛β细胞分泌功能,降血糖作用明显。     

Specificity in the activation and inhibition by flavonoids of benzo[a]pyrene hydroxylation by cytochrome P-450 isozymes from rabbit liver microsomes

The effect of flavone and 7,8-benzoflavone on the metabolism of benzo[a]pyrene to fluorescent phenols by five cytochrome P-450 isozymes obtained from rabbit liver microsomes was determined. Benzo[a]pyrene metabolism was stimulated more than 5-fold by the addition of 600 microM flavone to a reconstituted monooxygenase system consisting of NADPH, cytochrome P-450 reductase, dilauroylphosphatidylcholine, and cytochrome P-450LM3c or cytochrome P-450LM4. In contrast, an inhibitory effect of flavone on benzo[a]pyrene metabolism was observed when cytochrome P-450LM2, cytochrome P-450LM3b, or cytochrome P-450LM6 was used in the reconstituted system. 7,8-Benzoflavone (50-100 microM) stimulated benzo[a]pyrene metabolism by the reconstituted monooxygenase system about 10-fold when cytochrome P-450LM3c was used, but benzo[a]pyrene hydroxylation was strongly inhibited when 7,8-benzoflavone was added to the cytochrome P-450LM6-dependent system. Smaller effects of 7,8-benzoflavone were observed on the metabolism of benzo[a]pyrene by the cytochrome P-450LM2-, cytochrome P-450LM3b-, and cytochrome P-450LM4-dependent monooxygenase systems. These results demonstrate that the activating and inhibiting effects of flavone and 7,8-benzoflavone on benzo[a]pyrene metabolism depend on the type of cytochrome P-450 used in the reconstituted monooxygenase system.     

MR弥散加权成像对鉴别诊断良恶性椎体压缩性骨折的临床价值研究

目的：探讨MR弥散加权成像（DWI）鉴别诊断良恶性椎体压缩性骨折的临床价值。方法：对57例经临床或病理证实的椎体良恶性压缩性骨折患者行矢状位T1M、T2WI、T2WI／FS及DWI扫描,研究其在常规序列和DWI序列上的表现,将常规MR序列和DWI序列检出率进行比较,测量正常椎体及病变椎体的表观弥散系数（ADC）值,并进行统计学分析。结果：（1）MR常规序列和DWI序列（b=500s／mm2）表现：良性椎体压缩性骨折呈长T1长或等T2改变,T2WI／FS呈高信号,DWI可以呈高信号、等信号及低信号;恶性椎体压缩性骨折呈长T1长T2信号,大部分病灶T2WUFS及DWI呈高信号,少数变现为低信号;（2）MR常规序列和DWI序列（b=500s／mm2）病灶检出率的比较：T1WI、T2WI／FS及DWI序列病灶检出率均高于T2WI序列,其间的差别有显著性意义（P〈0．01）,T1WI、T2WI／FS及DWI序列病灶检出率之间无显著性差异（P〉0．01）;（3）ADC值比较：在DWI（b=500s／mm2）上,良性组ADC值为（2．03±0．83）×10^3mm^2/s,恶性组ADC值为（1．37±0．75）×10^-3mm^2/s,正常组ADC值为（0．36±0．21）×10^-3mm^2／s,成像条件相同时,良性组高于恶性组,两组间有明显的统计学意义（P〈0．05）。结论：DWI可较好的反映椎体的弥散特征,ADC值作为量化指标可对良恶性椎体压缩性骨折进行可靠鉴别。     

Comparison of six rabbit liver cytochrome P-450 isozymes in formation of a reactive metabolite of acetaminophen

This laboratory has recently reported the isolation of an ethanol-inducible form of rabbit liver microsomal cytochrome P-450, designated isozyme 3a. In view of the reports of others that the hepatotoxicity of acetaminophen is increased in ethanol-treated animals and the human alcoholic, we have determined the activity of the six available P-450 isozymes in the activation of the drug to give an intermediate which forms a conjugate with reduced glutathione. Isozymes 3a, 4, and 6, all of which are present in significant amounts in the liver microsomes from rabbits chronically administered ethanol, exhibited the highest activities in the reconstituted enzyme system, whereas isozymes 3b and 3c were 10- to 20-fold less effective, and phenobarbital-inducible isozyme 2 was essentially inactive, even in the presence of cytochrome b5. The results obtained thus indicate that induction by ethanol of P-450 isozyme 3a (or a homologous enzyme in other species) may contribute to the toxicity of acetaminophen but that other cytochromes also play a significant role.     

Comparison of four modeling tools for the prediction of potential distribution for non-indigenous weeds in the United States

This study compares four models for predicting the potential distribution of non-indigenous weed species in the conterminous U.S. The comparison focused on evaluating modeling tools and protocols as currently used for weed risk assessment or for predicting the potential distribution of invasive weeds. We used six weed species (three highly invasive and three less invasive non-indigenous species) that have been established in the U.S. for more than 75 years. The experiment involved providing non-U. S. location data to users familiar with one of the four evaluated techniques, who then developed predictive models that were applied to the United States without knowing the identity of the species or its U.S. distribution. We compared a simple GIS climate matching technique known as Proto3, a simple climate matching tool CLIMEX Match Climates, the correlative model MaxEnt, and a process model known as the Thornley Transport Resistance (TTR) model. Two experienced users ran each modeling tool except TTR, which had one user. Models were trained with global species distribution data excluding any U.S. data, and then were evaluated using the current known U.S. distribution. The influence of weed species identity and modeling tool on prevalence and sensitivity effects was compared using a generalized linear mixed model. Each modeling tool itself had a low statistical significance, while weed species alone accounted for 69.1 and 48.5% of the variance for prevalence and sensitivity, respectively. These results suggest that simple modeling tools might perform as well as complex ones in the case of predicting potential distribution for a weed not yet present in the United States. Considerations of model accuracy should also be balanced with those of reproducibility and ease of use. More important than the choice of modeling tool is the construction of robust protocols and testing both new and experienced users under blind test conditions that approximate operational conditions.     

Transient expression of β-glucuronidase in plastids of various plant cells and tissues delivered by a pneumatic particle gun

Chloroplast expression plasmids pTRBCL-GUS (tobaccorbcL promoter-gusA-tobaccorbcL terminator) and pHHU3004 (spinach ‘x gene’ promoter-gusA-spinachrbcL terminator) and a control nuclear expression plasmid pBI221 (CaMV 35S promoter-gusA-NOS terminator) were introduced separately into cultured cells and tissues of tobacco andArabidopsis thaliana, as well as into cultured cells of the lower land plants liverwort and hornwort by a pneumatic particle gun. The pTRBCL-GUS and pHHU3004 plasmids produced many blue spots in the BY-2 cells and the roots ofArabidopsis thaliana, but not in any of the green cells or tissues. The results suggest that the pTRBCL-GUS and pHHU3004 plasmids are expressed more in proplastids and amyloplasts than in chloroplasts. GUS activities of the BY-2 cells bombarded with pTRBCL-GUS and pHHU3004 were insensitive to α-amanitin treatment (10 and 50 μg/ml), while that of the cells with pBI221 greatly decreased by the same treatment. Hence, it is likely that the pTRBCL-GUS and pHHU3004 plasmids were substantially expressed in the proplastids.     

A simple pressure filtration apparatus for field use

A simple apparatus for pressure-filtering water samples in the field is described. It is used in conjunction with the low pressure outlet of a standard regulator attached to an aqualung. The apparatus is useful in situations where electricity to run electric vacuum pumps is not available and is superior to conventional hand vacuum pumps.