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PubMed1982

Biodegradation of Xanthan Gum by Bacillus sp.

Strains tentatively identified as Bacillus sp. were isolated from sewage sludge and soil and shown to elaborate extracellular enzymes that degrade the extracellular polysaccharide (xanthan gum, polysaccharide B-1459) of Xanthomonas campestris NRRL B-1459. Enzyme production by one strain was greatly enhanced when the strain was incubated in a mixed culture. Products of degradation were identified as d-glucuronic acid, d-mannose, pyruvylated mannose, 6-O-acetyl d-mannose, and a (1-->4)-linked glucan. These products correlate with the known structure of the gum. The complexity of the product mixture indicated that the xanthanase was a mixture of carbohydrases. The xanthanase complexes were similar to one another in temperature stability, pH and temperature optima, degree of substrate degradation, and enzymolysis products. Differences in pH stability, salt tolerance, recoverability, and yields of enzyme were observed.

Journal Article↗
PubMed1996

Overproduction of recombinant ribulose 1,5-bisphosphate carboxylase/oxygenase from Synechococcus sp. strain PCC6301 in glucose-controlled high-cell-density fermentations by Escherichia coli K-12.

A predictive and feedback glucose feed controller, previously developed for nutrient-sufficient growth of Escherichia coli to high cell densities, was used to produce large quantities of a heterologous, cyanobacterial recombinant hexadecameric (L8S8) protein, ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) in E. coli. Culture and plasmid stability conditions were optimized to yield the production of approximately 1 g of soluble, active recombinant RubisCO per liter. Recombinant RubisCO also was produced in lactose-induced high-cell-density fermentation of E. coli K-12.

Cyanobacteria↗
PubMed1973

Neisseria gonorrhoeae auxotyping: differentiation of clinical isolates based on growth responses on chemically defined media.

A system is described for differentiating clinïcal isolates of Neisseria gonorrhoeae based on their growth or absence of growth on a set of 11 chemically defined agar media. The complete medium, NEDA, contains all of the compounds required for gonococcal growth; but isolates differ in their ability to grow on NEDA from which selected compounds are individually omitted. The differential compounds include L-proline, L-arginine, L-ornithine, L-methionine, hypoxanthine, uracil, thiamine, and thiamine pyrophosphate. A distinctive pattern of growth responses on the standard media defines an auxotype. Twenty auxotypes were found among a group of 251 gonococci which were isolated from patients examined in the clinics of one city during a 3-month span of time. Another collection of 74 strains from several different countries yielded two additional auxotypes. The stability of the nutritional requirements on which the auxotyping depends was verified in two ways. Cultures isolated from different anatomic sites of a patient or from sexual partners represented the same auxotype, as did cultures which were repeatedly isolated from cases of presumptive treatment failures. Also, the auxotypes of gonococci remained the same after numerous subcultures. The reproducibility of results and the variety and number of auxotypes indicate the potential value of the auxotyping system as an epidemiological tool.

Agar↗
PubMed2002

A novel gene expression control system and its use in stable, high-titer 293 cell-based adeno-associated virus packaging cell lines.

Previous attempts to establish 293cell-based stable and high-titer adeno-associated virus (AAV) packaging cell lines were unsuccessful, primarily due to adenovirus E1-activated Rep gene expression, which exerts cytostatic and cytotoxic effects on the host cells. Control of the two large AAV Rep proteins (Rep78/68) was insufficient to eliminate the adverse effects, because of the leaky expression of the two small Rep proteins (Rep52/40). However, it was unsuccessful to control Rep52/40 gene expression since its promoter is located within the coding sequence of Rep78/68. To tightly regulate all four Rep proteins by using their own promoters, we have developed a novel gene control paradigm termed "dual splicing switch," which disrupts all four Rep genes by inserting into their shared coding region an intron that harbors transcription termination sequences flanked the LoxP sites. As a result, the structure and activities of the Rep gene promoters, both p5 and p19, are not affected; however, all of the Rep transcripts are prematurely terminated and the genes were inactivated. Removal of the terminator by Cre protein reactivates the transcription of all four Rep proteins derived from their own promoters. This switch system was initially tested in the lacZ gene and a 600-fold induction of beta-galactosidase activity was observed. Using the dual splicing switch strategy, we have subsequently established a number of AAV packaging cell lines from 293 cells, which showed a normal growth rate, high stability, and more importantly, high yields of AAV vectors. Such a gene control paradigm is also useful for other viruses, e.g., autonomous parvoviruses. Finally, the high-titer 293-based AAV packaging cell lines should greatly reduce the risk of wild-type adenovirus contamination and provide a scalable AAV vector production method for both preclinical and clinical studies.

Cell Line↗
PubMed2006

Synthesis and properties of water-soluble core-shell-shell silica-CdSe/CdS-silica nanoparticles.

This paper describes the synthesis of highly water-soluble and fluorescent core-shell-shell silica-CdSe/CdS-silica nanoparticles (CSS silica-QDs-silica NPs). We used cadmium nitrate and 1,1-dimethyl-2-selenourea precursors to synthesize CdSe quantum dots (QDs) in aqueous solution under simultaneous illumination with a diode-pumped solid state green laser and a Xe-Hg lamp. After passivation of the CdSe QDs with CdS, the CdSe/CdS QDs were then conjugated covalently to (3-mercaptopropyl)trimethoxysilane (MPS); we call these nanoparticles "MPS-QDs". We mixed the MPS-QDs with tetraethoxysilane (TEOS), ethanol, and NH3. By controlling the concentrations of the reagents, the stirring speed, and the reaction time, we synthesized CSS silica-QDs-silica NPs having sizes ranging from 75 to 190 nm. The incubation time for preparing the MPS-QDs and their concentrations are important parameters in determining the morphologies of the CSS silica-QDs-silica NPs. When we mixed 50 nM MPS-QDs, 1.1 mM TEOS, and 78 mM NH3 and reacted them at a stirring speed of 750 rpm, we obtained 85-nm-diameter CSS silica-QDs-silica NPs having a QD shell thickness of about 20 nm. The CSS silica-QDs-silica NPs provide a strong photoluminescence intensity (quantum yield 88%) and exhibit enhanced stability both photochemically and in high-conductivity media (e.g., 1.0 M NaCl).

Cadmium Compounds↗
PubMedDate not supplied

Changing the pH of the external aqueous phase may modulate protein entrapment and delivery from poly(lactide-co-glycolide) microspheres prepared by a w/o/w solvent evaporation method.

The milk model protein, beta lactoglobulin (BLG), was encapsulated into microspheres prepared by a multiple emulsion/solvent evaporation method. The effect of the pH of the outer aqueous phase on protein encapsulation and release as well as on microsphere morphology has been investigated. At all tested pH values, the encapsulation efficiency was shown to decrease with increasing the initial amount of BLG. This was correlated with the reduced stability of the primary emulsion as the initial BLG increased. In addition, reducing the solubility of BLG in the external aqueous phase by decreasing the pH to the isoelectric point of BLG (pI 5.2) resulted in an improved protein encapsulation. Moreover, it was shown that combining pH modification and optimal stability of the first emulsion yielded microspheres with a high encapsulation efficiency. However, release kinetic studies revealed that a significant burst release was observed with microspheres loaded with large amounts of BLG, especially when prepared in a medium at pH 5.2. This burst effect was attributed to morphology changes in the microsphere surface which was characterized by the presence of pores or channels able to accelerate the release of BLG. These pores were assumed to result from the presence of large amounts of protein molecules on the microsphere surface, that aggregate during microsphere formation at pH 5.2. Indeed, single adsorption experiments have shown that BLG had a higher affinity for the particle surface when the pH was close to the pI. Thus, reducing the solubility of a protein in the external aqueous phase allows the product of microspheres with a better encapsulation efficiency, although this benefit is provided by a strong adsorption of the protein on microsphere surface.

Adsorption↗
PubMed2002

Detection of Piscirickettsia salmonis in fish tissues by an enzyme-linked immunosorbent assay using specific monoclonal antibodies.

An enzyme-linked immunosorbent assay (ELISA) for the detection of Piscirickettsia salmonis in fish tissue samples was developed. The test uses a combination of different monoclonal antibodies specific against P. salmonis in the capture step of the assay. The antibodies 7G4, 6E2 and 2C1 chosen for the capture step are bound to the solid support with an adhesive protein purified from a bivalve mollusc, resulting in a high yield of adsorption and binding stability. The monoclonal antibody 7G4, used as a second antibody, is conjugated to horseradish peroxidase. The resulting ELISA test detected 7 different isolates of P. salmonis and does not cross-react with several other fish pathogens, revealing a high specificity and sensitivity. The test also detects P. salmonis in kidney tissue of infected coho salmon with 98% correlation with the immunofluorescence assay.

Alphaproteobacteria↗
PubMed2005

Sequential treatment of mood and anxiety disorders.

OBJECTIVE: Administration of treatments in a sequential order is a common practice in clinical medicine, but has received insufficient attention in psychiatry. The aim of this review was to survey the literature concerned with a sequential use of pharmacotherapy and psychotherapy in mood and anxiety disturbances. DATA SOURCES AND STUDY SELECTION: A review of the clinical trials in which treatment components were used in a sequential order (i.e., pharmacotherapy followed by psychotherapy, psychotherapy followed by pharmacotherapy, one drug treatment following another, or one psychotherapeutic technique following another) was performed. Studies were identified by using MEDLINE (English language articles published from 1967 to March 2005; keywords: sequential treatment, drugs and psychotherapy, combined treatment related to depressive disorder, bipolar disorder, depression, mania, anxiety disorders, panic disorder, social phobia, obsessive-compulsive disorder, generalized anxiety disorder, and posttraumatic stress disorder) and a manual search of the literature and Index Medicus for the years 1960 to 2005. DATA SYNTHESIS: In unipolar recurrent depression, the sequential use of pharmacotherapy was found to reduce relapse rate. In bipolar disorder, the use of psychotherapeutic strategies in patients who were already undergoing treatment with mood stabilizers was also found to yield clinical benefits. In anxiety disorders, the sequential use of pharmacotherapy and psychotherapy was not found to improve long-term outcome. CONCLUSION: The sequential treatment of mood and anxiety disorders does not fall within the realm of maintenance strategies. It is an intensive, 2-stage approach, which is based on the fact that one course of treatment with a specific treatment (whether pharmacotherapy or psychotherapy) is unlikely to entail solution to the complex array of symptoms of patients with mood and anxiety disorders. The sequential model introduces a conceptual shift in current assessment methods.

Antidepressive Agents↗
PubMed1999

Long-range electron transfer in rigid 3(10)-helical oligopeptides containing redox cyclic alpha-amino acids.

Intrahelical photoinduced electron transfer processes (ET) in conformationally restricted oligopeptides have been studied by nanosecond time-resolved transient spectroscopy. The helical peptides were constructed from sterically hindered alpha-aminoisobutyric acid (Aib) and two cyclic alpha-amino acids (Aib class) bearing electron acceptor and donor side chains (DkNap, ThQx). This helical backbone design provides high conformation stability, as previously demonstrated, and yields reliable 3(10)-helical architectures in solution. The forward ET between ThQx and 3DkNap is followed by a slow back ET thus giving rise to an accumulation of the charge-separated ion pairs for hundreds of nanoseconds. We demonstrate the modulation of electronic interactions by the number of intervening Aib residues separating acceptor-donor side chains and propose modifications of the peptide framework by inclusion of a non-Aib amino acid residue. These well-defined and sterically stable frameworks are suited for the precise evaluation of intrahelical electron transfer processes mediated by peptides.

Aminoisobutyric Acids↗
PubMed1975

Effects of a multi-hour immersion with intermittent exercise on urinary excretion and tilt table tolerance in athletes and nonathletes.

The circulatory and diuretic responses of athletes and non-athletes to 6-h water i-mersion with intermittent swimming exercise (series I) as well as to 8-h inactive immersions (series II) were studied. With simultaneous intermittent exercise, the normally arising diuresis during a water bath was strongly suppressed in athletes and even abolished in nonathletes. In subsequent tilt table tests, 3 of 11 (27.3%) athletes of series I and 3 of 4 (75%) of series II collapsed, whereas all nonathletes tolerated the vertical position without any subjective complaints. By use of the so-called "orthostatic index" (4) the later group, however, was also shown to yield a substantially better orthostatic stability in series I than in series II. The protective effect of intermittent physical activity for simulation of the weightless state can possibly be explained by assuming a less-reduced plasma volume via a diminished urinary excretion.

Adaptation, Physiological↗
PubMed2003

[Long circulating nanocapsules: interest in the treatment of severe malaria with halofantrine].

The aim of the work was to develop a new submicronic delivery system that can be used with poorly water soluble drugs for which sustained circulating concentrations are necessary. This system consists of oily core surrounded by a shell made of a copolymer of poly (D,L-lactid) and poly (ethylene glycol). Covalent coupling between the hydrophylic poly (ethylene glycol) and poly (D,L lactid) and high molecular weight of the poly (ethylene glycol) chains yield long circulating particles after intra-venous administration in mice. Halofantrine, a very effective drug administrated for the treatment of severe malaria caused by Plasmodium, for which no injectable preparation exists. Results showed that percentage of loading, yield of encapsulation and physical stability were more favourable with surface modified nanocapsules. Release of halofantrine was clearly related to partition between oil and external medium. Serum proteins in the medium, increased halofantrine release from nanocapsules and poly (ethylene glycol) grafted nanocapsules reduced this phenomenum. The pharmacokinetics of the free drug was modified to maintain it in blood circulation. It is important to note that high plasma concentrations of halofantrine were correlated with higher activity against parasites in mice infected with Plasmodium berghei.

Animals↗
PubMed2006

[Comparison of different transformation methods for Monascus sp].

In order to facilitate the producer of polyketide pathway, four different transformation methods were tested and compared in an attempt to develop the genetic transformation system of Monascus sp. Using vector pBC-Hygro, the fungus was transformed to be hygromycin B-resistant, by conventional transformation as well as electroporation based on protoplast, electroporation based on germinated conidia, and restriction enzyme-mediated integration (REMI). Electroporation based on germinated conidia was found to be inappropriate for transforming Monascus sp. due to a low transformation frequency. The conventional transformation and electroporation technique based on protoplasts were thought not to be fit for transforming Monascus sp., due to a low stability of transformants though they yielded up to 135 transformants and 125 transformants per microgrammol/Lol/Le DNA, respectively. Transformant number was increased by 20-fold by REMI (2,500 transformants per microgrammol/Lol/Le DNA) and 70%-75% of them were stable. REMI technique would be very beneficial to the establishment of the genetic transformation system of Monascus sp.

DNA, Recombinant↗
PubMed2006

Mood stabilizers and atypical antipsychotics: bimodal treatments for bipolar disorder.

Treatment options for bipolar disorder have rapidly expanded over the last decade, but providing optimal management remains an elusive goal. The authors reviewed the literature on the efficacy of agents with the best clinical evidence supporting their use in bipolar disorder, including the mood stabilizers lithium, valproate, lamotrigine, and carbamazepine, as well as the atypical antipsychotics olanzapine, risperidone, quetiapine, ziprasidone, and aripiprazole. Most medications appear to be more effective for symptoms of mood elevation than for symptoms of depression. The efficacy, tolerability, and safety profiles of agents must be considered when making clinical decisions. Several agents, including lithium, valproate, olanzapine, quetiapine, and risperidone, can cause problematic weight gain. In addition, the use of atypical antipsychotics has been associated with an increased risk of metabolic abnormalities such as dyslipidemia, hypergylycemia, and diabetes mellitus. In most patients, monotherapy offers inadequate efficacy. Further investigation of combinations of agents such as mood stabilizers and atypical antipsychotics may yield valuable insights into the potential of combination therapies to enhance clinical outcomes in patients with bipolar disorder.

Anticonvulsants↗
PubMed1991

[Determination of six Ephedra alkaloids in Chinese Ephedra (Ma Huang) by gas chromatography].

Six Ephedra alkaloids, namely ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine and methylpseudoephedrine, in 12 species of Chinese Ephedra were successfully separated and determined by gas chromatography with the highly specific and sensitive nitrogen phosphorus detector (GC/NPD). The column used (HP-5) had a cross linked 5% phenylmethylsilicone phase. Diphenylamine was used as the internal standard to check the reproducibility of the extraction yields of the alkaloids, the stability of the detector response and to quantify the alkaloids. The contents of the six alkaloids were calculated according to their regression equations. The way for the preparation of crude drug samples was improved, the diethyl ether extract of the alkalized crude sample was directly analysed by GC. The method is simple, rapid and sensitive. The results are in agreement with those of the HPLC method.

Alkaloids↗
PubMed1982

The stereochemical course of ribulosebisphosphate carboxylase. Reductive trapping of the 6-carbon reaction-intermediate.

The carboxylation of ribulosebisphosphate involves a 6-carbon reaction-intermediate, 2-carboxy-3-keto-D-arabinitol 1,5-bisphosphate. This labile intermediate, radiolabeled with 14CO2, was reduced (and thereby stabilized) with NaB[3H4]. This yielded a doubly labeled mixture with the chromatographic properties of 2-carboxy- and 4-carboxy-D-arabinitol 1,5-bisphosphate. These products (as their respective gamma-lactones) were chromatographically resolved from the gamma-lactones of 2-carboxy-D-ribitol and 2-carboxy-D-xylitol 1,5-bisphosphate, the other possible reduction products to be considered. Reduction of the 6-carbon reaction-intermediate by NaBH4 required prior denaturation of the enzyme. Of various denaturants tested, only acid was rapid enough to give good yields of the carboxypentitol bisphosphates. The reduction products of the reaction-intermediate inhibited the carboxylase stoichiometrically. In contrast to 2-carboxyribitol and 2-carboxyxylitol bisphosphate, 2-carboxy- and 4-carboxyarabinitol bisphosphate are exceptionally potent, essentially irreversible, slow-binding inhibitors of ribulosebisphosphate carboxylase.

Carbon Radioisotopes↗
PubMed1996

Studying temperament via construction of the Toddler Behavior Assessment Questionnaire.

The Toddler Behavior Assessment Questionnaire (TBAQ) was constructed by an iterative process of item generation intended to ensure content validity, by repeated item analyses focused on internal consistency and discriminant properties, and by scale revision. During the construction and initial validation processes reported in this article, data from 1,012 records were utilized. Internal consistency reliability estimates typically exceeded .80 for each scale. Evidence for convergent validity with other temperament questionnaires and for longitudinal stability was also obtained. Besides yielding a promising instrument, this assessment research has conceptual ramifications. For instance, components of negative affectivity (anger proneness and fearfulness) were independent, and item analyses suggested that shyness and other fears were independent as well. Consistent with most current views of temperament, the TBAQ temperament scales revealed some relationship and/or contextual specificity, as exemplified by the finding of only moderate parental agreement. The rank ordering on most temperament dimensions was impressively preserved from age 12 months, when the Infant Behavior Questionnaire (IBQ) was used, to age 18 months, when the TBAQ was used (especially when subtle differences between the IBQ and TBAQ were taken into account). Most of the analyses benefit from replication.

Child Behavior↗
PubMed1997

First-order differential-delay equation for the baroreflex predicts the 0.4-Hz blood pressure rhythm in rats.

We have described a 0.4-Hz rhythm in renal sympathetic nerve activity (SNA) that is tightly coupled to 0.4-Hz oscillations in blood pressure in the unanesthetized rat. In previous work, the relationship between SNA and fluctuations in mean arterial blood pressure (MAP) was described by a set of two first-order differential equations. We have now modified our earlier model to test the feasibility that the 0.4-Hz rhythm can be explained by the baroreflex without requiring a neural oscillator. In this baroreflex model, a linear feedback term replaces the sympathetic drive to the cardiovascular system. The time delay in the feedback loop is set equal to the time delay on the efferent side, approximately 0.5 s (as determined in the initial model), plus a time delay of 0.2 s on the afferent side for a total time delay of approximately 0.7 s. A stability analysis of this new model yields feedback resonant frequencies close to 0.4 Hz. Because of the time delay in the feedback loop, the proportional gain may not exceed a value on the order of 10 to maintain stability. The addition of a derivative feedback term increases the system's stability for a positive range of derivative gains. We conclude that the known physiological time delay for the sympathetic portion of the baroreflex can account for the observed 0.4-Hz rhythm in rat MAP and that the sensitivity of the baroreceptors to the rate of change in blood pressure, as well as average blood pressure, would enhance the natural stability of the baroreflex.

Activity Cycles↗
PubMed2000

Better conditions for mammalian in vitro splicing provided by acetate and glutamate as potassium counterions.

We demonstrate here that replacing potassium chloride (KCl) with potassium acetate (KAc) or potassium glutamate (KGlu) routinely enhances the yield of RNA intermediates and products obtained from in vitro splicing reactions performed in HeLa cell nuclear extract. This effect was reproducibly observed with multiple splicing substrates. The enhanced yields are at least partially due to stabilization of splicing precursors and products in the KAc and KGlu reactions. This stabilization relative to KCl reactions was greatest with KGlu and was observed over an extended potassium concentration range. The RNA stability differences could not be attributed to heavy metal contamination of the KCl, since ultrapure preparations of this salt yielded similar results. After testing various methods for altering the salts, we found that substitution of KAc or KGlu for KCl and MgAc(2)for MgCl(2)in splicing reactions is the simplest and most effective. Since the conditions defined here more closely mimic in vivo ionic concentrations, they may permit the study of more weakly spliced substrates, as well as facilitate more detailed analyses of spliceosome structure and function.

Glutamates↗