Plasmid borne virulence of Enterobacter hafniae.

The strain classified as Enterobacter hafniae has been isolated in a severe epidemy of porcine diarrhoea. Its pathogenicity has been found to be cotransmissible with resistance to oxytetracycline when the strain was grown in a mixed culture with some nonpathogenic E. hafniae strains as well as with Escherichia coli. Toxinogenity seems to be responsible for virulence of the strain.     

Foam separation of microbial cells

Batch foam separation has been employed to separate Saccharomyces carlsbergensis cells from their broth without the use of any external surface-active agent. A model has been developed to predict the foamate cell concentration as well as the variation of cell concentration in the bulk liquid in the foam column as a function of time. The model assumes a linear equilibrium relation between the cell concentrations at the interface and the bulk. The foam has interface as well as interstitial liquid. The interface is assumed to be in equilibrium with the interstitial liquid, which in turn is assumed to have the same concentration as the bulk. The interfacial area is calculated by assuming the foam bubbles to be pentagonal dodecahedral in shape. The model has been found to explain the results of foam separation of cells quite well, particularly with respect to the effect of bubble size and aeration rate.     

A critical analysis of a left-handed double helix model for B-DNA fibers.

A search for a left-handed double helix model for B-DNA fibers has been undertaken. The model has to present good stereochemistry and also to be in agreement with X-ray and infrared data. Dihedral angles as well as atomic coordinates and calculated intensities curves are given for the best model obtained. Comparison with experimental results shows that this model must be rejected as a candidate for the representation of B-DNA fibers.     

Nonlinear process modeling of fructosyltransferase (FTase) using bootstrap re-sampling neural network model

Recently, the increased demand of fructooligosaccharides (FOS) as a functional food has alarmed researchers to screen and identify new strains capable of producing fructosyltransferase (FTase). FTase is the enzyme that converts the substrate (sucrose) to glucose and fructose. The characterization of complex sugar such as table sugar, brown sugar, molasses, etc. will be carried out and the sugar that contained the highest sucrose concentration will be selected as a substrate. Eight species of macro-fungi will be screened for its ability to produce FTase and only one strain with the highest FTase activity will be selected for further studies. In this work, neural networks (NN) have been chosen to model the process based on their excellent ‘resume’ in coping with nonlinear process. Bootstrap re-sampling method has been utilized in re-sampling the data in this work. This method has successfully modeled the process as shown in the results.     

Analysis on folding of misgurin using two-dimensional HP model

Misgurin is an antimicrobial peptide from the loach, while the hydrophobic-polar (HP) model is a way to study the folding conformations and native states in peptide and protein although several amino acids cannot be classified either hydrophobic or polar. Practically, the HP model requires extremely intensive computations, thus it has yet to be used widely. In this study, we use the two-dimensional HP model to analyze all possible folding conformations and native states of misgurin with conversion of natural amino acids according to the normalized amino acid hydrophobicity index as well as the shortest benchmark HP sequence. The results show that the conversion of misgurin into HP sequence with glycine as hydrophobic amino acid at pH 2 has 1212 folding conformations with the same native state of minimal energy -6; the conversion of glycine as polar amino acid at pH 2 has 13,386 folding conformations with three native states of minimal energy -5; the conversion of glycine as hydrophobic amino acid at pH 7 has 2538 folding conformations with three native states of minimal energy -5; and the conversion of glycine as polar amino acid at pH 7 has 12,852 folding conformations with three native states of minimal energy -4. Those native states can be ranked according to the normalized amino acid hydrophobicity index. The detailed discussions suggest two ways to modify misgurin.     

Immunological structure of the populations of the upper and middle Volga River regions in relation to the causative agent of yersiniosis and its determining factors

The study of the immunological structure of the population in respect of intestinal yersiniosis at territories with different hydrothermal conditions has revealed the presence of a greater immune stratum (23.9% with the average agglutination titer being 1.8 +/- 0.09 log D) in humid areas, such as the region of the Upper Volga, in comparison with dry areas, such as the region of the Middle Volga, where the level of the immune stratum has proved to be twice as low (10.6% with the average agglutination titer being 0.8 +/- 0.1 log D). At both territories no essential differences in the risk of infection between the inhabitants of rural and urban areas, as well as between different professional and age groups have been revealed, with the exception of persons over 51 years of age, among whom the occurrence of seroconversions has proved to be lower.     

The role of oral acyclovir in the management of genital herpes simplex.

Oral acyclovir is an antiviral nucleoside analogue that has recently been released in Canada for use in selected patients with genital infections by the herpes simplex virus. First episodes of genital herpes should be treated with oral acyclovir as soon as the diagnosis is considered. Most people with recurrent genital herpes do not require systemic drug therapy. Selected patients with severe or long-lasting recurrences, recurrences associated with long prodromal periods (greater than 12 to 24 hours) or systemic complications such as erythema multiforme and eczema herpeticum may receive measurable benefit from treatment at the onset of symptoms. In most patients frequently recurrent disease can be suppressed with long-term therapy. Since long-term safety beyond 1 year has not been established, suppressive therapy should be stopped at least once per year to reassess the recurrence pattern. Acyclovir has not been adequately tested for safety in pregnancy and should not be prescribed for pregnant women unless the potential benefits outweigh the risks. Careful attention to disease severity, accurate diagnosis and exclusion of other causes of genital lesions will ensure that the drug is used only when beneficial.     

Chemically Assisted Phytoextraction: A Review of Potential Soil Amendments for Increasing Plant Uptake of Heavy Metals

The contamination of soils by trace metals has been an unfortunate sideeffect of industrialization. Some of these contaminants can interfere with vulnerable enduses of soil, such as agriculture or nature, already at relatively low levels of contamination. Reversely, conventional civil–technical soil-remediation techniques are too expensive to remediate extended areas of moderately contaminated soil. Phytoextraction has been proposed as a more economic complementary approach to deal with this specific niche of soil contamination. However, phytoextraction has been shown to be a slow-working process due to the low amounts of metals that can be annually removed from the soil under normal agronomic conditions. Therefore, extensive research has been conducted on process optimization by means of chemically improving plant availability and the uptake of heavy metals. A wide range of potential amendments has been proposed in the literature, with considerable attention being spent on aminopolycarboxylic acids such as ethylenediaminetetraacetic acid (EDTA). However, these compounds have received increasing criticism due to their environmental persistence and associated risks for leaching. This review presents an overview of potential soil amendments that can be employed for enhancing metal uptake by phytoextraction crops, with a distinct focus on more degradable alternatives to persistent compounds such as EDTA.     

Effect of cholesterol and protein content on membrane fluidity and 3β-hydroxysteroid dehydrogenase activity in mitochondrial inner membranes of bovine adrenal cortex

The steroid biosynthetic enzymes in the adrenal cortex are localised in endoplasmic reticulum and mitochondrial membranes. For some of the enzymes in endoplasmic reticulum the activity appears to be modulated by lipid fluidity, (21-hydroxysteroid hydroxylase and 3β-hydroxysteroid dehydrogenase). A mechanism for the regulation of corticosteroid biosynthesis mediated by the membrane fluidity has been suggested. Therefore a study of the mitochondrial inner membrane of the bovine adrenal cortex has been undertaken in comparison with a previous study of the endoplasmic reticulum. The kinetic parameters of the 3β-hydroxysteroid dehydrogenase were studied as a function of pH and temperature. No thermal transition can be observed in the Arrhenius plot for this enzyme in contrast with the results obtained for the microsomal enzyme. Membrane fluidity using, as fluorescent probes, diphenylhexatriene and a set of n-(9-anthroyloxy) fatty acids has been also studied as a function of temperature with or without addition of cholesterol. No thermal transition in the lipid phase can be observed. The addition of cholesterol to total mitochondrial membrane as to a lipid extract of the membrane decreases fluidity to the same extent as it does with microsomes. The presence of a large amount of protein in mitochondria has an effect which is additive to that of the cholesterol.     

Mycobacterial lipoarabinomannan: an extraordinary lipoheteroglycan with profound physiological effects

Detailed structural and functional studies over the last decade have led to current recognition of the mycobacterial lipoarabinomannan (LAM) as a phosphatidylinositol anchored lipoglycan with diverse biological activities. Fatty acylation has been demonstrated to be essential for LAM to maintain its functional integrity although the focus has largely been on the arabinan motifs and the terminal capping function. It has recently been shown that the mannose caps may be involved not only in attenuating host immune response, but also in mediating the binding of mycobacteria to and subsequent entry into macrophages. This may further be linked to an intracellular trafficking pathway through which LAM is thought to be presented by CD1 to subsets of T-cells. The implication of LAM as major histocompatibility complex (MHC)-independent T-cell epitope and the ensuing immune response is an area of intensive studies. Another recent focus of research is the biosynthesis of arabinan which has been shown to be inhibitable by the anti- tuberculosis drug, ethambutol. The phenomenon of truncated LAM as synthesized by ethambutol resistant strains provides an invaluable handle for dissecting the array of arabinosyltransferases involved, as well as generating much needed structural variants for further structural and functional studies. It is hoped that with more systematic investigations based on clinical isolates and human cell lines, the true significance of LAM in the immunopathogenesis of tuberculosis and leprosy can eventually be explained.      

Plant sulfur nutrition: From Sachs to Big Data

Together with water and carbon dioxide plants require 14 essential mineral nutrients to finish their life cycle. The research in plant nutrition can be traced back to Julius Sachs, who was the first to experimentally prove the essentiality of mineral nutrients for plants. Among those elements Sachs showed to be essential is sulfur. Plant sulfur nutrition has been not as extensively studied as the nutrition of nitrogen and phosphate, probably because sulfur was not limiting for agriculture. However, with the reduction of atmospheric sulfur dioxide emissions sulfur deficiency has become common. The research in sulfur nutrition has changed over the years from using yeast and algae as experimental material to adopting Arabidopsis as the plant model as well as from simple biochemical measurements of individual parameters to system biology. Here the evolution of sulfur research from the times of Sachs to the current Big Data is outlined.     

The use of fibrin glue in skin grafts and tissue-engineered skin replacements: a review.

Fibrin glue has been widely used as an adhesive in plastic and reconstructive surgery. This article reviews the advantages and disadvantages of its use with skin grafts and tissue-engineered skin substitutes. Fibrin glue has been shown to improve the percentage of skin graft take, especially when associated with difficult grafting sites or sites associated with unavoidable movement. Evidence also suggests improved hemostasis and a protective effect resulting in reduced bacterial infection. Fibrin, associated with fibronectin, has been shown to support keratinocyte and fibroblast growth both in vitro and in vivo, and may enhance cellular motility in the wound. When used as a delivery system for cultured keratinocytes and fibroblasts, fibrin glue may provide similar advantages to those proven with conventional skin grafts. Fibrin glue has also been shown to be a suitable delivery vehicle for exogenous growth factors that may in the future be used to accelerate wound healing.     

Bone grafts and bone morphogenetic proteins in spine fusion

Spinal fusions are being performed for various pathologies of the spine. Stabilizing vertebral segments by eliminating motion across those segments becomes critical in dealing with pathologies of the spine that lead to instability. The use of autograft has been the gold standard for spine fusion. However, due to complications such as donor site morbidity, increased operating time, and limited supply, the use of allograft as a graft extender has become an acceptable practice especially in fusions spanning multiple segments. The discovery and isolation of novel proteins (i.e., bone morphogenetic proteins, BMPs), which initiate the molecular cascade of bone formation, have experimentally been shown in numerous animal studies to be as effective as autografts. Although the use of BMPs has exciting applications in spine surgery, long-term clinical studies must be evaluated for its efficacy in various applications in humans. The use of biomimetic materials such as hydroxyapatite (HA), or tricalcium phosphate (TCP) has also been examined in several animal models as bone graft substitutes or carriers. Although these materials have shown some promise in specific site applications, more work remains in elucidating an efficacious combination of these materials and BMPs that can be as effective as autografts. This review will present the status of bone grafts, bone morphogenetic proteins, gene therapy, and work that has been done to facilitate spinal fusion and simultaneously eliminate the need for bone graft. This revised version was published online in July 2006 with corrections to the Cover Date.     

Gene therapy of primary T cell immunodeficiencies

Gene therapy of severe combined immunodeficiencies has been proven to be effective to provide sustained correction of the T cell immunodeficiencies. This has been achieved for 2 forms of SCID, i.e SCID-X1 (γc deficiency) and adenosine deaminase deficiency. Occurrence of gene toxicity generated by integration of first generation retroviral vectors, as observed in the SCID-X1 trials has led to replace these vectors by self inactivated (SIN) retro(or lenti) viruses that may provide equivalent efficacy with a better safety profile. Results of ongoing clinical studies in SCID as well as in other primary immunodeficiencies, such as the Wiskott Aldrich syndrome, will be thus very informative.     

重组大肠杆菌产琥珀酸研究进展

琥珀酸作为一种优秀的C4平台化合物, 广泛用于生物高分子、食品与医药等行业, 市场潜在需求量巨大。采用微生物发酵法生产琥珀酸, 可利用廉价的可再生资源, 实现石油的原料替代, 而且过程污染小, 环境友好, 且在发酵过程中可吸收固定温室气体CO2, 开辟了其利用的新途径, 近年来引起了广泛关注。在丁二酸生产菌株中, 大肠杆菌由于其遗传背景清楚, 易操作易调 控, 培养基要求简单, 生长迅速等优点, 近年来被广泛用于研究以获得产琥珀酸优秀生产菌株。本工作系统综述了产琥珀酸大肠杆菌构建中所采用的基因工程策略及代谢工程技术, 并探讨了今后研究的方向。     

Autosomal dominant inheritance of the DeMyer Sequence

Holoprosencephaly (HPC) may be an isolated trait or may be associated with other craniofacial defects. As an isolated trait, HPC has been reported to be inherited as an autosomal recessive, while autosomal dominant inheritance has been reported for sequences or syndromes in which HPC occurs. This paper presents a family in which several people have variable combinations of craniofacial defects. The most severely affected relatives have HPC, while others have only mild facial dysmorphia and decreased bitemporal diameters. One relative has a single central incisor in the maxilla. The pattern of defects in this family is inherited as an autosomal dominant. Other families with the reported pattern of defects, including single central incisors as minimal manifestations, are cited. Because HPC is found only occasionally in the pattern of defects, the term DeMyer Sequence is proposed as a more appropriate designator than the more commonly used Holoprosencephaly Sequence.     

Pegylated liposomal doxorubicin in the treatment of AIDS-related Kaposi's sarcoma

Kaposi's sarcoma is a vascular tumor of skin and viscera first described in 1872. Prior to the 1980s, this disease was rarely seen in the Western world, but was quite prevalent in Sub-Saharan African countries. Since the onset of the HIV pandemic in the 1980s, the incidence of Kaposi's sarcoma has increased markedly in Africa and continues to be a significant problem in association with AIDS in Western countries. Many therapies have been demonstrated to be effective in the treatment of HIV-related Kaposi's sarcoma, including alitretinoin gel, interferon alpha, and various forms of cytotoxic chemotherapy. Antiretroviral therapy combined with cytotoxic agents has yielded significantly greater efficacy than chemotherapy alone. However, as reviewed in this report, pegylated liposomal doxorubicin has been established as the treatment of choice for patients with AIDS-associated Kaposi's sarcoma in Western countries. Compelling preclinical and clinical evidence, reviewed herein, has demonstrated that the nanoparticle (pegylated liposome) delivery system of this formulation leads to greater tumor localization of doxorubicin and consequent improved efficacy, as well as reduced toxicity.     

Quality assurance of monoclonal products: Virologic and molecular biologic considerations

Summary The FDA has set limits concerning the viral and molecular contamination of monoclonal antibody products intended for human use. Industry has an obligation to be as familiar with these limits as it has been with federal requirements pertaining to pyrogens and bacteria. The assessment of risk from polynucleotides, based on molecular biologic and existing technical limitations, is discssed, as is the strategy of validating the purification of monoclonal antibodies of viral contaminants in terms of an indicator organism concept.     

Staphylococcus lugdunensis Cultured from the Amniotic Fluid at Caesarean Section

Staphylococcus lugdunensis is a virulent coagulase-negative staphylococcus. It behaves like and can be mistaken in culture for Staphylococcus aureus. While originally thought to be a skin commensal rarely responsible for opportunistic infection, it was rapidly established as a significant human pathogen. It has been mainly associated with native and prosthetic valve endocarditis, osteomyelitis, and skin and soft tissue cellulitis, but has also been reported as a cause of fasciitis as well as peritonitis. Staphylococcus lugdunensis has been reported as a cause of endometritis but has not been previously isolated from amniotic fluid. Here, amniotic fluid samples were collected in the course of a larger study on amniotic fluid bacteriology, with prior ethical approval and informed patient consent. Amniotic fluid was obtained at Caesarean Section by direct needle aspiration from the intact amnion. Analysis with Staphylococcal API test kits led to identification of Staphylococcus lugdunensis in two cases. The clinical significance of the finding in these reported cases is undetermined. Staphylococcus lugdunensis has been shown to be a cause of serious and potentially fatal morbidities, but this is the first report of its culture from amniotic fluid. As caesarean delivery is accepted as the single most important factor associated with post-partum infectious complications in both mother and neonate, the identification of this pathogen is a new concern.     

Recovery of free enzymes from product liquors by bio-affinity adsorption: Trypsin binding by immobilised soybean inhibitor

Summary Soybean trypsin inhibitor immobilised to sub-micron ferrite particles functions as an affinity adsorbent for trypsin and the adsorbed enzyme may be recovered following elution in dilute acid. Trypsin can be adsorbed from casein solutions that is has digested. Equilibrium is reached in under 2 min with an effective dissociation constant as low as 10^–7 M, allowing recoveries of more than 90% of added enzyme under realistic conditions.These results suggest that bioaffinity adsorbents could be used to recover an enzyme that has converted a macromolecular substrate. The operation of such a process is discussed, and some interactions are described that could be used with suitably high affinity adsorbents for other enzymes.