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PubMedDate not supplied

Bulk acoustic wave bacterial growth sensor applied to analysis of antimicrobial properties of tea.

A bulk acoustic wave (BAW) bacterial growth sensor has been proposed for study of inhibitory effects of tea by continuous monitoring of disturbances in Proteus growth in the aqueous extracts of various teas, e.g. green tea, Fuzhuan brick tea, Oolong tea, Kudin tea, and black tea. The kinetic parameters, e.g. asymptote (A), maximum specific growth rate (microm), lag time (lambda), and generation time (g), accurately estimated by using the growth response model, have been first used to characterize antimicrobial properties of tea. All of the parameters were changed via the inhibitory effects by tea. Green tea gives the weakest inhibitory action while others show stronger inhibitory actions. These inhibitory effects have also been examined by using the pour plate count technique. Both of the results show that, in addition to the antimicrobial properties of tea polyphenols and catechins, etc., the inhibitory effects may be attributed to the metabolites produced during the fermentation processing of these teas except green tea. The conventional disk diffusion test has been used to determine the minimum inhibitory concentration (MIC) against P. rettgeri. The MICs of green tea, Fuzhuan brick tea, Oolong tea, and black tea were found to be 1113, 818.0, 681.2, and 510.4 microg/mL, respectively. The BAW bacterial growth sensor has shown to have advantages over other techniques, including the disk diffusion test, photometry, and the impedance method.

Acoustics↗
PubMed2004

Bioaccumulation of chromium from tannery wastewater: an approach for chrome recovery and reuse.

The presence of chromium in the effluent is a major concern for the tanning industry. Currently, chemical precipitation methods are practiced for the removal of chromium from the effluent, but that leads to the formation of chrome-bearing solid wastes. The other membrane separation and ion exchange methods available are unfeasible due to their cost. In this study, the removal of chromium from tannery effluent has been carried out using abundantly available brown seaweed Sargassum wightii. Simulated chrome tanning solution was used for the standardization of experimental trials. Various factors influencing the uptake of chromium, viz., quantity of seaweed, concentrations of chromium, pH of the chrome-bearing wastewater, and duration of treatment, have been studied. Chemical modification of the seaweed through pretreatment with sulfuric acid, magnesium chloride, and calcium chloride showed improved uptake of chromium. Langmuir and Freundlich isotherms have been fitted for various quantities of seaweed. The dynamic method of treatment of protonated seaweed with simulated chrome tanning solution at a pH of 3.5-3.8 for a duration of 6 h gave the maximum uptake of about 83%. A similar uptake has been established for commercial chrome tanning wastewater containing the same concentration of chromium. The Sargassum species exhibited a maximum uptake of 35 mg of chromium per gram of seaweed. Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, and flame photometry studies have been carried out to understand the mechanistic pathway for the removal of chromium. The potential reuse of chromium-containing seaweed for the preparation of basic chromium sulfate (tanning agent) has been demonstrated.

Animals↗
PubMed2003

Biosynthesis of riboflavin. Single turnover kinetic analysis of 6,7-dimethyl-8-ribityllumazine synthase.

6,7-dimethyl-8-ribityllumazine synthase (lumazine synthase) catalyzes the condensation of 5-amino-6-ribitylamino-2,4-(1H,3H)-pyrimidinedione with 3,4-dihydroxy-2-butanone 4-phosphate, affording the riboflavin precursor, 6,7-dimethyl-8-ribityllumazine. Single turnover experiments monitored by multiwavelength photometry were performed with the recombinant lumazine synthase of Bacillus subtilis. Mixing of the enzyme with the pyrimidine type substrate is conducive to a hypsochromic shift as well as a decrease in absorbance of the heterocyclic substrate; the rate constant for that reaction is 0.02 s(-1) microM(-1). Rapid mixing of the complex between enzyme and pyrimidine type substrate with the second substrate, 3,4-dihydroxy-2-butanone 4-phosphate, is followed by the appearance of an early optical transient characterized by an absorption maxima at 330 nm of low intensity which was tentatively assigned as a Schiff base intermediate. The subsequent elimination of phosphate affords a transient with intense absorption maxima at 455 and 282 nm, suggesting an intermediate with an extended system of conjugated double bonds. The subsequent formation of the enzyme product, 6,7-dimethyl-8-ribityllumazine, is the rate-determining step.

Bacillus subtilis↗
PubMed2004

In-soil potassium sensor system.

A potentiometric sensor system based on potassium ion-selective electrodes was developed for agricultural purposes. Sensors were built using PVC ion-selective membranes over an inner solid contact prepared with graphite-epoxy composites. A copper plate was used as a reference electrode. A two-stage electronic circuit composed of current and voltage amplifiers was designed to interface the sensors to a distributed data acquisition system. Three ion-selective sensors and three off-the-shelf temperature sensors and their associated circuits were mounted in a PVC tube to set up a soil probe. The electronic controls were placed in an airtight box fixed at the upper part of the probe. The system was evaluated in the field, where the sensors presented sensibility within the range of 69-71 mV dec(-)(1). Extracts of soil samples were analyzed by a current flame photometry approach, and the results, compared with the probe measurements, showed a linear relationship (r (2) = 0.992 and 0.995, respectively, to 5 and 20 cm depths), which implies viability and instrumentation reliability for agricultural applications.

Ion-Selective Electrodes↗
PubMed2006

A novel formulation approach for preparation of nanoparticulate red mold rice.

Monascus has been used for thousands of years. In China, Monascus has been widely used as a natural food-coloring agent for many kinds of foods. The metabolites of Monascus species, specifically, monacolin K, gamma-aminobutyric acid, and dimerumic acid, have been proven to have cholesterol-lowering, blood pressure-lowering, and antioxidant effects. Nowadays, the public has recognized the importance of Monascus products for its many health benefits. The focus of this study is to explore the effects of nanoparticulate dispersion of red mold rice (RMR) after wet-milling technology treatment. An RMR nanoparticulate formulation was reproducibly obtained after milling in the presence of dispersing agent and water. Furthermore, the physical and chemical properties of these RMR particles were studied using electron microscopy, laser light scattering, pH meter, high-performance liquid chromatography (HPLC), and photometry. The results demonstrate that RMR (mean size = 20.15 microm), processed with wet-milling technology, forms an aqueous-based nanoparticle dispersion (mean particle size of less than 0.41 microm). In addition, HPLC analyses, performed on the secondary metabolites, demonstrated that monacolin K was reduced to 50-92% of its base level and citrinin was reduced to 48-74% of its base level. When testing for the levels of pH, the processed RMR had increased from a pH level of 4.47-4.82 to 5.56-6.4; also, pigment analysis showed that yellow and red pigments were reduced to 36 and 39% of its base level after the wet-milling process. Partial agglomeration has been observed in RMR dispersion when stored in refrigeration after 2 months. RMR can be formulated as a nanoparticulate dispersion without compromising its stability, but its secondary metabolite extraction rate was changed. Further experimentation will be needed to verify safety and functionality evaluations.

Anticholesteremic Agents↗
PubMed2005

Antioxidant properties of natural and synthetic chromanol derivatives: study by fast kinetics and electron spin resonance spectroscopy.

[structure: see text] Chromanol-type compounds act as antioxidants in biological systems by reduction of oxygen-centered radicals. Their efficiency is determined by the reaction rate constants for the primary antioxidative reaction as well as for disproportionation and recycling reactions of the antioxidant-derived radicals. We studied the reaction kinetics of three novel chromanols: cis- and trans-oxachromanol and the dimeric twin-chromanol, as well as ubichromanol and ubichromenol, in comparison to alpha-tocopherol and pentamethylchromanol. The antioxidant-derived radicals were identified by optical and electron spin resonance spectroscopy (ESR). The kinetics of the primary antioxidative reaction and the disproportionation of the chromanoxyl radicals were assessed by stopped-flow photometry in different organic solvents to simulate the different polarities associated with biomembranes. Furthermore, the reduction of the chromanoxyl radicals by ubiquinol and ascorbate was measured after laser-induced one-electron chromanol oxidation in ethanol and in a micellar system, respectively. The rate constants showed that twin-chromanol had better radical scavenging properties than alpha-tocopherol and a significantly slower disproportionation rate of its corresponding chromanoxyl radical. In addition, the radical derived from twin-chromanol is reduced by ubiquinol and ascorbate at a faster rate than the tocopheroxyl radical. Finally, twin-chromanol can deliver twice as many reducing equivalents, which makes this compound a promising new candidate as artificial antioxidant in biological systems.

Antioxidants↗
PubMed2005

Biosynthesis of isoprenoids. purification and properties of IspG protein from Escherichia coli.

[Structure: see text]. The IspG protein is known to catalyze the transformation of 2-C-methyl-d-erythritol 2,4-cyclodiphosphate into 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate in the nonmevalonate pathway of isoprenoid biosynthesis. We have found that the apparent IspG activity in the cell extracts of recombinant Escherichia coli cells as observed by a radiochemical assay can be enhanced severalfold by coexpression of the isc operon which is involved in the assembly of iron-sulfur clusters. The recombinant protein was isolated by affinity chromatography under anaerobic conditions. With a mixture of flavodoxin, flavodoxin reductase, and NADPH as the reducing agent, stringent assay methods based on photometry or on 13C NMR detection of multiply 13C-labeled substrate/product ratios afforded catalytic activities greater than 60 nmol mg(-1) min(-1) for the protein "as isolated" (i.e., without reconstitution of any kind). Lower apparent activities were found using photoreduced deazaflavin as an artifactual electron donor, whereas dithionite was unable to serve as an artificial electron donor. The apparent Michaelis constant for 2-C-methyl-D-erythritol 2,4-cyclodiphosphate was 700 microM. The enzyme was inactivated by EDTA and could be reactivated by Mn2+. The pH optimum was at 9.0. The protein contained 2.4 iron ions and 4.4 sulfide ions per subunit. The replacement of any of the three conserved cysteine residues afforded mutant proteins which were devoid of catalytic activity and contained less than 6% of Fe2+ and less than 23% of S2- as compared to the wild-type protein. Sequence comparison indicates that putative IspG proteins of plants, the apicomplexan protozoan Plasmodium falciparum, and bacteria from the Bacteroidetes/Chlorobi group contain an insert of about 170-320 amino acid residues as compared with eubacterial enzymes.

Amino Acid Sequence↗
PubMed2000

PolyHEMA and polyHEMA-poly(MMA-co-AA) as substrates for culturing Vero cells.

Poly (2-hydroxyethyl methacrylate), polyHEMA, is known to prevent cellular attachment and spreading. This hydrogel is used to culture cells not dependent on anchorage. Blending polyHEMA with a copolymer of methyl methacrylate and acrylic acid introduces negative charges to the hydrogel and improves its mechanical characteristics. PolyHEMA and the blend were tested for attachment and proliferation of Vero cells. Dense and porous samples of the hydrogels were used. Attachment assays included cellular quantification with MTT photometry and cellular morphology with the scanning electron microscopy after 2 h culture. Proliferation assays were carried out with 5 and 10 days culture. Cellular morphology included cytochemistry of resin sections and scanning electron microscope observations. Hydrogels allowed a few cells to attach and proliferate. The cells growing on the surface of hydrogels were organized in various layers and showed a differential morphology. Cells located inside the pores remained rounded. The hydrogels showed the possibility of inducing differentiated phenotypic expression.

Journal Article↗
PubMed1988

Development of acute tolerance to bumetanide: constant-rate infusion studies.

Bumetanide was administered intravenously to four mongrel dogs as a bolus of 8.7 micrograms/kg, immediately followed by a constant-rate infusion of 0.35 microgram/min/kg at 0.036 ml/min. Treatment A consisted of a 90-min equilibration period and first hour (Phase I) of study in which animals were maintained under euvolemic conditions. During the subsequent 3 hr of Treatment A (Phase II), animals were maintained under hydropenic conditions. These experiments were then repeated 1 week later (Treatment B) with the temporal aspects of hydration reversed (Phase III, hydropenia; Phase IV, euvolemia). Serial plasma and urine samples were assayed for bumetanide by high-performance liquid chromatography (HPLC) and for sodium by flame photometry. The bumetanide excretion rate was not significantly different during the 4 hr of Treatment A, although minor differences were observed between Phase III and Phase IV of Treatment B. The sodium excretion rate showed significant differences between euvolemic and hydropenic conditions of both treatments. A two- to threefold difference in the sodium excretion rate persisted even when slight differences (less than 20%) in bumetanide excretion rates were taken into account. These results demonstrate that an acute tolerance does develop to constant-rate infusions of bumetanide when inadequate fluid and electrolyte replacement occurs and that this tolerance can be reversed by rehydration.

Aldosterone↗
PubMed1987

Development of acute tolerance to bumetanide: bolus injection studies.

Bumetanide was administered intravenously to four mongrel dogs, in a random crossover fashion, at doses of 0.05 mg/kg (I), 0.15 mg/kg (II), and 0.5 mg/kg (III) where urinary losses were replaced with lactated Ringer's solution at 1.5 ml/min (hydropenic conditions) or at a dose of 0.5 mg/kg (IV) where urinary losses were replaced with lactated Ringer's solution isovolumetrically (euvolemic conditions). Serial plasma and urine samples were assayed for bumetanide by high-performance liquid chromatography (HPLC) and for sodium by flame photometry. There were no significant differences in the pharmacokinetic parameters of bumetanide among Treatments I-IV. The dynamic parameters Emax (maximum effect attributable to the drug) and s (slope factor) were not different between treatments. However, a consistent, demonstrable increase in ER50 (urinary excretion rate of drug producing 50% of Emax) was observed among Treatments I (2.34 micrograms/min), II (3.92 micrograms/min), and III (6.54 micrograms/min); also, a significant decrease in ER50 was observed between Treatment III (6.54 micrograms/min) and Treatment IV (2.66 micrograms/min). These results show that hydration status has a marked effect on natriuretic and diuretic response and that tolerance can rapidly develop within a single intravenous dose of bumetanide.

Animals↗
PubMed1999

Effects of pharmaceutical compounds on ciliary beating in human nasal epithelial cells: a comparative study of cell culture models.

PURPOSE: To test two in vitro human nasal epithelial cell culture systems for their ability to screen the effects of pharmaceutical compounds on ciliary beating. METHODS: Human nasal epithelial cells were cultured as monolayer and in a sequential monolayer-suspension culture with in vitro ciliogenesis. The influence of reference cilio-stimulatory compounds (glycocholate, isoprenaline), reference cilio-inhibitory compounds (chlorocresol, diphenhydramine) and pH on ciliary beating was investigated using computerized microscope photometry. RESULTS: Sodium glycocholate (0.5% w/v) maximally and reversibly increased CBF of the cells in both culture systems by 26 +/- 4% (monolayer) and 18 +/- 6% (suspension). Similarly, isoprenaline (10(-3) M) maximally, but irreversibly increased CBF of the cells by 14 +/-3% (monolayer) and 17 +/- 4% (suspension). Chlorocresol (0.005% w/ v) reversibly reduced the CBF of the cells by 50 +/- 6% (monolayer) and 34 +/- 4% (suspension); at a higher concentration (0.1% w/v) it resulted in instantaneous and irreversible ciliostasis. Diphenhydramine (0.1% w/v) reversibly reduced CBF in both culture systems by 45 +/- 13% (monolayer) and 69 +/- 5% (suspension); irreversible cilio-stasis occurred in less than 2 minutes in both culture systems upon cell exposure to diphenhydramine (1.0% w/v). In the monolayer culture system, CBF was stable only within the physiological pH range of 6.5-8.0; ciliary beating in the suspension culture remained stable within a pH range of 4.0-10.0. CONCLUSIONS: Both cell culture systems are suitable for screening the effects of pharmaceutical compounds on ciliary beating. Especially the sequential monolayer-suspension culture appears to be very promising as ciliary activity can be preserved for as long as 6 months.

Anti-Allergic Agents↗
PubMed2004

Halothane alters contractility and Ca2+ transport in ventricular myocytes from streptozotocin-induced diabetic rats.

General anaesthetics have previously been shown to have profound effects on myocardial function. Moreover, many patients suffering from diabetes mellitus are anaesthetised during surgery. This study investigated compromised functioning of cardiac myocytes from streptozotocin (STZ)-induced diabetic rats and the additive effects of halothane on these dysfunctions. Ventricular myocytes were isolated from 8 to 12 weeks STZ-treated rats. Contraction and intracellular free calcium concentration ([Ca2+]i) were measured in electrically field-stimulated (1 Hz) fura-2-AM-loaded cells using a video-edge detection system and a fluorescence photometry system, respectively. L-type Ca2+ current was measured in whole cell, voltage-clamp mode. Halothane significantly (p < 0.01) depressed the amplitude and the time course of the Ca2+ transients in a similar manner in myocytes from control and STZ-treated rats. However, the effect of halothane on the amplitude of shortening and L-type Ca2+ current was more pronounced in myocytes from STZ-treated animals compared to age-matched controls. Myofilament sensitivity to Ca2+ was significantly (p < 0.01) increased in myocytes from STZ-treated rats compared to control. However, in the presence of halothane the myofilament sensitivity to Ca2+ was significantly (p < 0.05) reduced to a greater extent in myocytes from STZ-treated rats compared to controls. In conclusion, these results show that contractility, Ca2+ transport and myofilament sensitivity were all altered in myocytes from STZ-treated rats and these processes were further altered in the presence of halothane suggesting that hearts from STZ-induced diabetic rats are sensitive to halothane.

Anesthetics, Inhalation↗
PubMed1987

Solid hydrocarbon aerosols produced in simulated Uranian and Neptunian stratospheres.

Optical constants n and k are measured for thin hydrocarbon films produced from charged particles (RF plasma) irradiation of (1) 100% CH4; (2) 7% CH4, 93% H2; (3) 0.5% CH4, 99.5% H2; (4) 0.0002% CH4, 99.3% H2 (with impurities); and (5) 3 to 25% CH4, 25% He, remainder H2--all at submillibar pressures. In all experiments, yellow to deep brown-red solid products are synthesized which are hypothesized to be, at least in part, the unidentified visible and near-UV chromophores in the stratospheres of Uranus and Neptune. Results for experiments 2, 3, and 4 are in good mutual accord, but are significantly different from experiments 1 and 5. He in the precursor gases affects the product composition. Typical solid products for experiments 5 show, at 0.55 micrometer wavelength, n = 1.60 +/- 0.05, 3 x 10(-2) > or = k > or = 3 x 10(-3), and [C/H] approximately equal to 0.7. These results are, for n and k respectively, consistent with and in excellent agreement with those derived from high phase angle Voyager 2 photometry of Uranus (Pollack et al., this issue). Aerosols produced directly from the atmosphere by precipitating magnetospheric charged particles may be competitive with those produced by UV and charged particle irradiation of simple hydrocarbon condensates. The optical and chemical properties of aerosols in the Uranian and Neptunian atmospheres may evolve toward higher values of n and k and higher carbon content as the particles sediment through changing radiation and thermal environments.

Aerosols↗
PubMed2000

Diclofenac drops to treat inflammation after cataract surgery.

PURPOSE: To compare the anti-inflammatory effect of topical diclofenac sodium 0.1% in a fixed combination with gentamicin 0.3% to the anti-inflammatory effect of dexamethasone phosphate 0.1% in a prospective randomized double-masked double-dummy study in patients undergoing cataract surgery. SETTING: Trial performed from June 1991 to April 1992 at the Hôpital Jules Gonin, Department of Ophthalmology, University of Lausanne, Lausanne, Switzerland. METHODS: Inclusion of patients scheduled for extracapsular cataract extraction (ECCE) with implantation of an all PMMA intraocular lens (IOL). Double-masked comparison of post-operative inflammation in two randomized treatment groups: (1) fixed diclofenac sodium 0.1%/gentamicin 0.3% and vehicle drops 4X/day until day 12-14 and diclofenac sodium 0.1% 3X/day until day 28. (2) dexamethasone phosphate 0.1% drops 4X/day until postoperative day 12-14 and 3X/day until day 28 and gentamicin 0.3% drops 4X/day until day 12-14. Anterior chamber flare and cells, measured by laser flare-cell photometry, were analyzed as the primary outcomes. RESULTS: Eighty-seven patients were recruited, 45 being assigned to the diclofenac group and 42 to the dexamethasone control group. Diclofenac was significantly better than dexamethasone at controlling flare at day 3 (p< or =0.01) and day 12-14 (p< or =0.002). Mean anterior chamber cells were also significantly lower at day 12-14 (p< or =0.021) and day 28 (p< or =0.012). The commonest adverse event was transient punctate keratitis, which occurred in 15 diclofenac and 3 dexamethasone patients. CONCLUSIONS: While both treatments were effective at controlling post-operative inflammation, the diclofenac-gentamicin combination followed by diclofenac alone was significantly better at suppressing flare and cells but showed a slightly higher incidence of punctate keratitis and eye discomfort.

Aged↗
PubMed1994

Spectral sensitivity, photopigments, and color vision in the guinea pig (Cavia porcellus).

Behavioral discrimination tests and electroretinogram (ERG) flicker photometry were used to measure spectral sensitivity and to define the spectral mechanisms of the guinea pig (Cavia porcellus). Results from these 2 approaches converge to indicate that guinea pig retinas contain rods with peak sensitivity of about 494 nm and 2 classes of cone having peak sensitivities of about 429 nm and 529 nm. The presence of 2 classes of cones suggests a retinal basis for a color vision capacity. Behavioral tests of color vision were conducted that verified this prediction: Guinea pigs have dichromatic color vision with a spectral neutral point centered at about 480 nm. The cone pigment complement of the guinea pig is different from that known to characterize other rodents.

Animals↗
PubMedDate not supplied

Detection of intracellular Ca2+ transients in sympathetic neurones using arsenazo III.

Changes in cytosolic calcium ion concentration ([Ca2+]i) have been implicated in a wide variety of cellular stimulus--transduction roles. In nerve cells, it is believed that electrical activity raises [Ca2+]i by allowing influx of Ca2+ through voltage-dependent channels in the surface membrane. Elevation of neuronal [Ca2+]i may also occur due to release of Ca2+ from intracellular storage sites. Transient increases in [Ca2+]i are thought to trigger neurotransmitter release, and to modulate axonal transport, energy metabolism and growth cone movement. Intracellular Ca2+ also appears to regulate membrane potassium channels and thereby to regulate electrical excitability. Although [Ca2+]i transients have been measured in a few giant invertebrate neurones, detection of such transients in a vertebrate neurone has not been previously reported. We have measured [Ca2+]i in bullfrog sympathetic neurones by photometry of a microinjected calcium indicator dye, arsenazo III (refs 14-16), and report here that action potentials and voltage-clamped depolarizations cause long-lasting increases in [Ca2+]i. Aslo, exposure to the drug theophylline can cause spontaneous periodic increases in [Ca2+]i. Comparisons of [Ca2+]i signals with simultaneous intracellular recordings of membrane potential suggest that the kinetics of the post-tetanic hyperpolarization (PTH) following a series of action potentials or the spontaneous hyperpolarizations induced by theophylline directly reflect the kinetics of the [Ca2+]i transient.

Action Potentials↗
PubMed2000

Unusual spectral energy distribution of a galaxy previously reported to be at redshift 6.68.

Observations of distant galaxies are important both for understanding how galaxies form and for probing the physical conditions of the Universe at early times. It is, however, very difficult to identify galaxies at redshifts z > 5, because they are so faint and have few spectral characteristics. We previously reported the probable identification of a galaxy at z = 6.68, based on one line and an apparent break in the spectrum just shortwards of that, which we interpreted as Lyman alpha emission and the Lyman alpha break, where photons with shorter wavelengths are absorbed by the intervening neutral hydrogen gas. Here we present optical photometry that shows moderate detections of light in the B- and V-band images, which are inconsistent with the expected absence of flux shortwards of the Lyman alpha break for alpha galaxy at z > 5, and inconsistent with the previous flux measurement. Moreover, the spectral energy distribution for this object cannot readily be fitted by any known galaxy spectral template at any redshift, so the redshift is undetermined.

Journal Article↗