胎膜早破与分娩方式的关系及产程观察

目的:探讨胎膜早破对分娩方式与结果的影响,提高对产程观察的重视。方法:统计分析249例孕足月胎膜早破者的分娩方式、产程及母儿并发症,并与249例随机抽取同期孕足月无胎膜早破的产妇进行对照。结果:胎膜早破组自然分娩率明显低于对照组(P<0.05),产褥感染、新生儿窒息发生率明显高于对照组(P<0.05)。结论:胎膜早破易感染,并导致胎儿宫内窘迫和新生儿窒息,与难产、剖宫产有相关性,应合理选择分娩方式,积极处理产程,以确保母婴安全。     

Two Bacillus sphaericus binary toxins share the midgut receptor binding site: implications for resistance of Culex pipiens complex (Diptera: Culicidae) larvae

This work demonstrates that Bin1 and Bin2 toxins, produced by Bacillus sphaericus strains IAB59 and 2362, respectively, share a binding site in midgut brush border membranes (BBMF) from Culex pipiens complex larvae. However, a colony selected with strain IAB59, displaying a resistance ratio of only 42-fold to IAB59, but a 162,000-fold resistance to strain 2362, was found to miss receptors for Bin2 in the BBMF. This correlates with results showing that Bin1, produced in strain IAB59, failed to bind specifically to BBMF from other colony highly resistant to strain 2362. Data indicate the loss of the BBMF bound receptor as a general mechanism of resistance to binary toxins in mosquito.     

Neuroendocrine disruption without direct endocrine mode of action: Polychloro-biphenyls (PCBs) and bisphenol A (BPA) as case studies

Endocrine disruption is commonly thought to be restricted to a direct endocrine mode of action i.e. the perturbation of the activation of a given type of hormonal receptor by its natural ligand. Consistent with the WHO definition of an endocrine disrupter, a key issue is the “altered function(s) of the endocrine system”. Such altered functions can result from different chemical interactions, beyond agonistic or antagonistic effect at a given receptor. Based on neuroendocrine disruption by polychlorinated biphenyls and bisphenol A, this paper proposes different mechanistic paradigms that can result in adverse health effects. They are a consequence of altered endocrine function(s) secondary to chemical interaction with different steps in the physiological regulatory processes, thus accounting for a possibly indirect endocrine mode of action.     

Disinfection and hygiene in the field of food of animal origin

The cleaning/disinfection procedure should minimize the usually high number of microorganisms (10⁷–10⁸ cm²) on surfaces to reasonably low levels of about one log per cm². Aseptic conditions are normally not achieved.Most commerical disinfectants are mixed preparations. The agents used in disinfectants should not provoke changes, neither in chemical pattern, nor in sensoric properties of the food. They should not be the cause for deposition of unhealthy residues or for corrosive influences on premises. The efficacy must be warranted. The disinfection should include bactericidal, fungicidal and possibly virucidal activities with only minimal static effects. The efficacy should be based on a short-term effect even at lower temperatures (about 10°C).Mostly in use are QACs, amphoteric surfactants and biguanides which are combined in many variations. Aldehydes in mixtures are used very seldomly and only in small amounts due to sensoric, corrosive or toxicological reactions. Alcohols are suitable for quick applications but they are flammable. Organic acids and peroxygens will deliver no residues but may be aggressive to tools and man. Alkylamines will have higher static effects and chlorine active compounds will suffer from protein load and pH deviations.In daily practice the efficacy has to be proved by microbiological monitoring, e.g. by cultural or, indirectly, by bioluminescence-techniques (with or without somatic ATP).Residue levels will remain low on premises if the disinfection is performed correctly, in adequate concentrations and with fresh water rinsing in sufficient amounts (about 8 liters per m²).     

几种主要眼遗传病在我国的发病情况与遗传规律

中国遗传学会眼科遗传协作组于1979年成立后,组织了对国内主要眼遗传病发病情况及遗传规律的研究,现已进行了70万人的普查,整理分析了各种眼遗传病5000余家系。本文报告了先天性红绿色盲、高度近视、视网膜色素变性、先天性上睑下垂、先天性小眼球、先天性白内障、先天性青光眼、Leber视神经萎缩、家族性角膜营养不良、先天性原发性眼球震颤、先天性眼内组织缺损、先天性无虹膜、视网膜母细胞瘤、家族性黄斑变性、近视和原发性青光眼的群体患病率与遗传规律。     

Processing of Cry1Ab delta-endotoxin from Bacillus thuringiensis by Manduca sexta and Spodoptera frugiperda midgut proteases: role in protoxin activation and toxin inactivation

Activation of Cry protoxins is carried out by midgut proteases. This process is important for toxicity and in some cases for specificity. Commercial proteases have been used for in vitro protoxin activation. In the case of Cry1A protoxins, trypsin digestion generates a toxic fragment of 60–65 kDa. Here, we have analyzed the in vitro and in vivo activation of Cry1Ab. We found differences in the processing of Cry1Ab protoxin by Manduca sexta and Spodoptera frugiperda midgut proteases as compared to trypsin. Midgut juice proteases produced two additional nicks at the N-terminal end removing helices 1 and 2a to produce a 58 kDa protein. A further cleavage within domain II splits the toxin into two fragments of 30 kDa. The resulting fragments were not separated, but instead coeluted with the 58 kDa monomer, in size-exclusion chromatography. To examine if this processing was involved in the activation or degradation of Cry1Ab toxin, binding, pore formation, and toxicity assays were performed. Pore formation assays showed that midgut juice treatment produced a more active toxin than trypsin treatment. In addition, it was determined that the 1 helix is dispensable for Cry1Ab activity. In contrast, the appearance of the 30 kDa fragments correlates with a decrease in pore formation and insecticidal activities. Our results suggest that the cleavage in domain II may be involved in toxin inactivation, and that the 30 kDa fragments are stable intermediates in the degradation pathway.     

Metabolic networks evolve towards states of maximum entropy production

A metabolic network can be described by a set of elementary modes or pathways representing discrete metabolic states that support cell function. We have recently shown that in the most likely metabolic state the usage probability of individual elementary modes is distributed according to the Boltzmann distribution law while complying with the principle of maximum entropy production. To demonstrate that a metabolic network evolves towards such state we have carried out adaptive evolution experiments with Thermoanaerobacterium saccharolyticum operating with a reduced metabolic functionality based on a reduced set of elementary modes. In such reduced metabolic network metabolic fluxes can be conveniently computed from the measured metabolite secretion pattern. Over a time span of 300 generations the specific growth rate of the strain continuously increased together with a continuous increase in the rate of entropy production. We show that the rate of entropy production asymptotically approaches the maximum entropy production rate predicted from the state when the usage probability of individual elementary modes is distributed according to the Boltzmann distribution. Therefore, the outcome of evolution of a complex biological system can be predicted in highly quantitative terms using basic statistical mechanical principles.     

The biology of insecticidal activity and resistance

Identifying insecticide resistance mechanisms is paramount for pest insect control, as the understandings that underpin insect control strategies must provide ways of detecting and managing resistance. Insecticide resistance studies rely heavily on detailed biochemical and genetic analyses. Although there have been many successes, there are also many examples of resistance that still challenge us. As a precursor to rational pest insect control, the biology of the insect, within the contexts of insecticide modes of action and insecticide metabolism, must be well understood. It makes sense to initiate this research in the best model insect system, Drosophila melanogaster, and translate these findings and methodologies to other insects. Here we explore the usefulness of the D. melanogaster model in studying metabolic-based insecticide resistances, target-site mediated resistances and identifying novel insecticide targets, whilst highlighting the importance of having a more complete understanding of insect biology for insecticide studies.     

奥杜威工业石制品分类综述

石制品是旧石器时代考古的主要研究对象,其分类是旧石器生产技术和文化研究的基础与前提,然而,中国旧石器时代考古有关石制品分类目前尚无一致标准,这对开展旧石器时代考古学术研究的国际交流产生了负面影响。鉴于似奥杜威(Oldowan-like)或模式I工业在我国古人类石器工业面貌占有非常特殊的地位,因此,本文对以非洲为代表的奥杜威(Oldowan)工业(模式I)石器技术研究中有关石制品的分类体系进行整合和梳理,同时借鉴Mary Leakey、Glynn Isaac和Nicholas Toth等为代表的不同分类系统,并对中国境内有关石制品分类的现状进行讨论。