Protease sensitivity and nuclease resistance of the scrapie agent propagated in vitro in neuroblastoma cells.

The scrapie agent has been propagated in vitro in mouse neuroblastoma cells. To further characterize the tissue culture-derived scrapie agent, we studied the effects of protease and nuclease digestion on the agent derived from these cells. The scrapie agent in these cells was found to be resistant to protease digestions for short times but was inactivated by prolonged digestion at high protease concentrations. In contrast, digestion with a variety of nucleases did not alter the agent titer. These results demonstrate that the agent requires an essential protein or proteins for infectivity. If the agent also contains a nucleic acid genome, it must be more nuclease resistant than the majority of cellular DNA and RNA. These properties of the tissue culture-derived scrapie agent were identical to those of brain-derived scrapie agent and thus cannot be attributed to secondary effects of tissue pathology, since the infected cell cultures show no cytopathic effects as a result of infection.     

Antigenic relationships among five reovirus-like (RVL) agents by complement fixation (CF) and development of new substitute CF antigens for the human RVL agent of infantile gastroenteritis.

The human reovirus-like (HRVL) agent, Nebraska calf diarrhea virus (NCDV), epizootic diarrhea of infant mice (EDIM) virus, simian agent (SA)-11, and the "O" (offal) agent were found to be similar, if not identical, in reciprocal complement fixation (CF) tests employing hyperimmune animal sera. In addition, in CF tests with paired sera from 35 diarrhea patients who shed the HRVL agent, 74% developed serologic evidence of infection with the HRVL antigen, 43% with NCDV, 51% with EDIM virus, 57% with SA-11, and 71% with the "O" agent. Thus, in addition to the NCDV, which had previously been described as a suitable substitute CF antigen for the HRVL agent, the SA-11, "O", and EDIM viruses may also be utilized as substitute antigens for the HRVL agent. However, the "O" agent appears to be the most efficient of the four substitute CF antigens and thus should be used preferentially when the HRVL agent is not available. The "O" agent was about as efficient as the HRVL agent and significantly more efficient than the NCDV for detecting seroresponses. The greatest efficiency for detecting infection with the HRVL agent resulted when sera were tested with both the HRVL and "O" agents as 31 (89%) of the patients developed serologic evidence of infection with one or both antigens. The finding of additional substitute CF antigens for the HRVL agent may have implications in the immunoprophylaxis against human disease.     

化学-生物发酵联用技术对稻草腐熟的效果及红外光谱研究

采用傅立叶变换红外光谱(FTIR),研究了化学—生物联用处理对稻草腐熟的影响．结果表明,稻草经各化学—生物联用处理7d,其腐熟效果均比对照好．其中化学熟化剂A-生物熟化剂A联用处理后,稻草颜色暗褐色,容易折断,明显腐熟．FTIR分析表明,经处理后稻草的酚羟基、醇羟基和甲基含量降低,脂肪族化合物部分降解,芳构化成分增多,尤其是取代芳环增多,氧化缩合作用增强,加快了稻草的腐殖化进程．比较各熟化剂及其配合对稻草的腐熟效果表明,化学熟化剂A>化学熟化剂B。生物熟化剂A>生物熟化剂B>生物熟化剂C,其中化学熟化剂A-生物熟化剂A联用处理对稻草腐熟效果最好．     

微生物复合菌剂的制备

【背景】微生物复合菌剂比单一菌剂更能够在土壤中高效、稳定发挥作用促进作物生长,是微生物菌剂发展的趋势,但是目前对构建微生物复合菌剂的研究不够深入。【目的】研制可显著促进水稻生长的微生物复合菌剂,并构建微生物复合菌剂的数学模型。【方法】将解淀粉芽孢杆菌(Bacillus amyloliquefaciens) FH-1与7株植物促生细菌按照生物量1:1的比例复配成微生物复合菌剂,利用水稻盆栽实验筛选高效复合微生物菌剂。利用生化方法对各个菌株的促生特性进行测定。分析植物特征和菌株促生特性间的相关性关系,并据此利用一般线性方程构建复合菌剂的数学模型。【结果】与空白对照CK相比,复合菌剂FN显著提升水稻的苗长20.79%、根长26.67%和鲜重74.84%(P0.05),是7种微生物复合菌剂中综合效果最佳的微生物复合菌剂。偏相关分析结果表明解无机磷能力、产铁载体能力和产ACC脱氨酶能力在促进植物生长过程中可能发挥着更重要的作用。根据菌剂促生特性与植物特征的偏相关性结果,构建了微生物复合菌剂数学模型,预测准确率可达97%以上。【结论】成功研制了高效促进水稻生长的微生物复合菌剂,并构建了微生物复合菌剂的数学模型,可为微生物复合菌剂的研制提供一定的科学指导。     

填充料和通气对污泥堆肥过程的影响

试验研究了不同配比的以料和通气状况对污泥堆肥起始升温的影响。结果表明,填充料含是量高的配比升温速度明显比填充料含量低的配比快;高填充料配比的堆体（填充料占堆料的１／２～１／３）在超始升温阶段可以不进行氢气的供给;低填充料的配比和加入回流堆肥的配比（填充料占堆料的１／４～１／９）,由于堆体的孔隙少,则必须进行通气量的调节。     

Hydrolysis of synthetic esters by the antibacterial agent in serum

Yotis, William W. (Loyola University, Chicago, Ill.). Hydrolysis of synthetic esters by the antibacterial agent in serum. J. Bacteriol. 91:488-493. 1966.-An antistaphylococcal serum agent was assayed colorimetrically, manometrically, and titrimetrically for esterase activity. p-Nitrophenol acetate, triacetin, l-lysine methyl and ethyl ester, and norleucine methyl ester were hydrolyzed by the antistaphylococcal agent. Acetylcholine and benzoylcholine esters, triolein, tristearin, and p-tosylarginine methyl ester were not attacked by this agent. With p-nitrophenol acetate as substrate, optimal activity occurred at pH 7.4. Incubation at 60 C for 30 min reduced drastically the esterase activity of the antistaphylococcal agent, and incubation at 75 C for 30 min abolished the esterase activity of this agent. Almost complete inhibition of esterase activity was observed with 0.001 m HgCl(2), ZnSO(4), and ethylenediaminetetraacetic acid (EDTA). EDTA inhibition could be reversed by the addition of CaCl(2), but not MgCl(2). Cysteine reversed the inhibition of HgCl(2). NaF, atoxyl, diisopropyl fluorophosphate, quinine, and physostigmine did not influence the esterase activity of the antibacterial agent. The demonstration of esterase activity of both the antistaphylococcal agent and coagulase may shed further light on the reported ability of coagulase to neutralize the antistaphylococcal activity of this agent, or the prevention of absorption of the agent on the staphylococcal cell surface. In addition, the colorimetric procedure described in this report may be a convenient tool in assaying the potency of the antistaphylococcal agent.     

Description of a Viral Agent Found in Blood Obtained from Patients with Infectious Hepatitis

A small, double-stranded deoxyribonucleic acid viral agent (agent Y) has been found in blood from patients with infectious hepatitis. The agent was propagated in chimpanzee liver tissue culture which had been grown and maintained on unheated agamma calf serum. A causal relationship between this agent and the occurrence of human disease cannot be determined from the data presented.     

Sedimentation characteristics of the scrapie agent from murine spleen and brain.

Sedimentation profiles of the scrapie agent in extracts of murine spleen and brain were determined by analytical differential centrifugation. Infectivity profiles of the agent from the two tissues were similar. Sedimentation of the agent was not substantially altered by detergent treatment with sodium deoxycholate. In the presence of detergent, centrifugation at an omega2t value of 3.0 x 1010 rad2/s in a fixed-angle rotor sedimented 90% of the agent. Comparative studies with radioisotopically labeled Simian virus 40 showed that centrifugation at an omega2t value of 1.6 x 10(10) rad2/s removed 90% of the virions. The sedimentation profile of the scrapie agent was similar to that observed for cellular ribosomal RNA. Heating infectious extracts of spleen to 80 degrees C for 30 min resulted in the destruction of 95% of the RNA while sedimentation of the scrapie agent was unchanged. These studies establish a limited range of particle sizes for the scrapie agent.     

Effect of redox agents on the non-electrolyte isotonic concentrations and on the equivalent pore radius of skeletal muscles of the frog

Oxidizing and/or reducing agents inversely influence the alterations in the speed of mass changes (dw/dt) due to osmotic perturbations: an oxidizing agent increases while a reducing agent decreases it. The values for isotonic concentration (Ciso) increased for all of the tested non-electrolytes in the presence of an oxidizing agent, while decreased in the presence of a reducing one. The Staverman's reflection coefficient values (sigma) showed changes opposite in direction, so that the direct correlation between the size of test molecules and sigma values remained unchanged. An oxidizing agent increases and a reducing agent decreases the equivalent pore radius (EPR).     

Analyses of frequency of infection, specific infectivity, and prion protein biosynthesis in scrapie-infected neuroblastoma cell clones.

Scrapie, a spongiform encephalopathy of sheep and goats, is caused by a poorly understood transmissible agent in which no nucleic acid has been conclusively identified. Biochemical characterization of agent derived from animal tissues has not been precise because of the tenacious association of the agent with tissue components. As an approach toward obtaining homogeneous preparations of agent generated in vitro, we cloned scrapie-infected neuroblastoma cells. By frequency analysis, nearly every cell in expanded cultures contained scrapie agent. We also analyzed cell-dose infectivity relationships and developed a standard curve which allowed various cultures to be compared. Since a proteinase K (PK)-resistant form of a protein designated prion protein (PrP) has been found in partially purified preparations of scrapie agent from infected animal spleens and brains, we sought to identify this protein in cell cultures. No PK-resistant PrP was found in infected or uninfected cultures, although the PK-sensitive PrP was readily detected. These results suggested that PK-resistant PrP may not be an essential component of the infectious scrapie agent.     

PEG-g-poly(GdDTPA-co-L-cystine): a biodegradable macromolecular blood pool contrast agent for MR imaging

Biodegradable PEGylated Gd-DTPA l-cystine copolymers, PEG-g-poly(GdDTPA-co-l-cystine), were prepared and tested as a blood pool contrast agent in mice. The biodegradable macromolecular agent was designed to be broken down into smaller Gd complexes by endogenous thiols via the disulfide-thiol exchange reaction to facilitate the clearance of Gd complexes after the contrast-enhanced MRI examination. Gd-DTPA l-cystine copolymers were synthesized by condensation polymerization of l-cystine and DTPA-dianhydride in water followed by chelating with Gd(OAc)(3). MPEG-NH(2) (MW = 2000) was then conjugated to the polymeric backbone in different ratios. The macromolecular contrast agent was readily degraded with the incubation of l-cysteine. It also demonstrated superior contrast enhancement in the heart and blood vessels as compared to a low molecular weight control agent, Gd-(DTPA-BMA). At 1 h postcontrast, the PEGylated macromolecular agent still showed prominent enhancement, while little contrast enhancement was detectable in the blood pool by the control agent. PEG-g-poly(GdDTPA-co-l-cystine) shows promise as an MR blood pool imaging agent.     

基于超声的多模式功能化对比剂研究进展

超声对比剂的使用使得超声诊断更加准确,扩大了超声成像的应用范围。但单一影像技术难以满足肿瘤等重大疾病临床诊断和治疗的需求。因此开发以超声对比剂为核心,具有多模式成像功能,或同时兼备肿瘤诊断和治疗功能的多模式功能化对比剂是目前的一大研究热点。多模式成像的结合可以实现优势互补,诊断和治疗功能的结合为使得肿瘤等重大疾病的解决提供了新理念和新希望,具有重要意义。本文就基于超声的多模式功能化对比剂进行综述。     

Molecular properties, partial purification, and assay by incubation period measurements of the hamster scrapie agent

The scrapie agent causes a progressive degeneration of the central nervous system of animals after a prolonged incubation period. Measurements of incubation period length, defined as the time from inoculation to the onset of clinical signs of neurological dysfunction, were related to the titer of the agent and the dilution of the inoculated sample. Equations defining the relationship provide a new assay for the agent requiring fewer animals than end point titrations. By use of this incubation period assay, the scrapie agent from hamster brain was found to have an s20,w of < 300 S but > 30 S assuming rho p = 1.2 g/cm3. A partially purified fraction P3 was obtained by differential centrifugation and sodium deoxycholate extraction. When P3 was extracted with phenol, virtually no infectivity was found in the aqueous phase even after examining such variables as pH, salt concentration, and predigestion of samples with proteinase K. Nonionic and nondenaturing, anionic detergents did not inactivate the scrapie agent; in contrast, denaturing detergents inactivated the agent. Sodium dodecyl sulfate (NaDodSO4) inactivated greater than 90% of the agent at a NaDodSO4 to protein ratio of 1.8 g/g. Inactivation by NaDodSO4 appears to be a cooperative process. Addition of a nonionic detergent to form mixed micelles with NaDodSO4 prevented inactivation of the agent by NaDodSO4. Weak chaotropic ions do not inactivate the scrapie agent while strong chaotropic ions like SCN- and Cl3CCOO- destroy infectivity at concentrations of 0.2 M. These data provide evidence in support of a protein component within the scrapie agent which is essential for maintenance of infectivity. Thus, it is unlikely that the scrapie agent is composed only of a "naked" nucleic acid as is the case for the plant viroids.     

油茶皂素化学和物理特性及其开发利用研究

油茶皂素学名茶皂角甙,结构糖是由葡萄糖醛酸,阿拉伯糖,木糖及半乳糖组成,结构酸是由反（顺）白芷酸及醋酸组成。茶皂角甙是由结构相似５─７种三萜类皂甙元构成。油茶皂素的表面活性主要是结构一端为疏水的脂肪酸基团,另一端为结构糖,结构酸亲水基团,吸附和胶团化,使皂素可用来做乳化剂,洗涤剂,发泡剂,分散剂,润湿剂,洗发剂,清洗剂,柔软剂等。     

Discovery of an agent in wastewater sludge that reduces the heat required to inactivate reovirus.

An agent that causes heat inactivation of reovirus to occur at reduced temperatures has been found in both raw and anaerobically digested sludge. This agent is originally associated with sludge solids but can be washed from these solids by blending with water. The activity of the agent was considerably greater in alkaline than in acid solutions, probably because it is insoluble at low pH. The agent was shown to be nonvolatile and heat stable up to 300 degrees C but was inactivated within 30 min at 400 degrees C. The rate of heat inactivation of reovirus by the agent was found to occur in a bimodal fashion and to be relatively rapid, even at 35 degrees C. Finally, it was found that this agent did not accelerate heat inactivation of poliovirus, but instead may be the component of sludge previously found to protect poliovirus against inactivation by heat.     

Discovery of an agent in wastewater sludge that reduces the heat required to inactivate reovirus.

An agent that causes heat inactivation of reovirus to occur at reduced temperatures has been found in both raw and anaerobically digested sludge. This agent is originally associated with sludge solids but can be washed from these solids by blending with water. The activity of the agent was considerably greater in alkaline than in acid solutions, probably because it is insoluble at low pH. The agent was shown to be nonvolatile and heat stable up to 300 degrees C but was inactivated within 30 min at 400 degrees C. The rate of heat inactivation of reovirus by the agent was found to occur in a bimodal fashion and to be relatively rapid, even at 35 degrees C. Finally, it was found that this agent did not accelerate heat inactivation of poliovirus, but instead may be the component of sludge previously found to protect poliovirus against inactivation by heat.     

Squalamine analogues as potential anti-trypanosomal and anti-leishmanial compounds

This paper concerns the synthesis of various simplified analogues of the novel anti-microbial agent, squalamine. The compounds were then investigated for activity against Trypanosoma brucei, the causative agent of African trypanosomiasis, Trypanosoma cruzi, the causative agent of Chagas disease and Leishmania donovani, the causative agent of visceral leishmaniasis. Several compounds showed in vitro activity, especially against T. brucei and L. donovani. However, one compound showed poor in vivo activity.     

Preliminary characterization of an organism isolated from a case of Viluy encephalomyelitis indicates a protozoal, rather than viral, aetiology

A microbial agent was isolated previously from a case of Viluy encephalomyelitis and named the 'KPN agent' after the initials of the patient. Here a detailed characterization of nucleic acids extracted from the purified KPN agent is presented. The agent contains both DNA and RNA, and has its own tRNAs and some other low-Mr RNAs, including 5S RNA. These findings, and the isolation of eukaryotic-type ribosomes, suggest that the KPN agent is not a virus, as believed before, but a more complex micro-organism, with protein-synthesizing capacity. The nucleotide sequence of the 5S RNA in the ribosomes of the KPN agent is identical with the sequence of 5S RNA of Acanthamoeba castellanii. The novel protozoan nature of the KPN agent is discussed in relation to other unusual properties of this micro-organism. Some implications of these results for the aetiology of Viluy encephalomyelitis are also discussed.     

Biochemical differentiation of pathotypes of the Synchytrium endobioticum (Schilb). Perc pathogen of potato tumor

Biochemical perculiarities of the potato tumours development on the plants infected with the agent of cancer Synchytrium endobioticum (Schilb). Perc. The experiment is dedicated to ascertaining contrast biochemical peculiarities of tumours on potato plants infected with the agent of cancer. The results of researches were used for the detection of the disease agent, its differentiation and identification of pathotypes of the cancer agent in the centres.