Maximum Concentration (maximum + concentration)

Distribution by Scientific Domains


Selected Abstracts


Paliperidone palmitate , review of the efficacy, safety and cost of a new second-generation depot antipsychotic medication

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 2 2010
L. Citrome
Summary Objective:, To describe the efficacy, safety and cost of paliperidone palmitate, a depot antipsychotic medication recently approved for the treatment of schizophrenia. Data sources:, A literature search was conducted by querying the websites http://www.pubmed.gov, http://www.fda.gov, http://www.accessdata.fda.gov/scripts/cder/drugsatfda and http://www.clinicaltrials.gov for the search term ,paliperidone palmitate'. Cost information was obtained from the pharmaceutical vendor servicing a local state-operated psychiatric facility. Study selection:, All available reports of studies were identified. Product labelling provided additional information. Data extraction:, Descriptions of the principal results and calculation of the number needed to treat (NNT) and number needed to harm (NNH) for relevant dichotomous outcomes were extracted from the study reports and synopses. Additional safety outcomes subject to NNH analysis were obtained from product labelling. Data synthesis:, Paliperidone palmitate is a newly available depot formulation of paliperidone (the 9-OH metabolite of risperidone). Upon injection into the deltoid or gluteal muscle, the release of the drug starts as early as day 1, reaches maximum plasma concentrations at 13 days and lasts for as long as 126 days. Maximum concentration following deltoid injection is approximately 28% higher compared with injection into the gluteal muscle, and thus paliperidone palmitate requires initiation by two initial deltoid injections spread 1 week apart to achieve therapeutic concentrations rapidly. Subsequent injections are at 4-week intervals. Acute efficacy was evidenced by four short-term double-blind, randomised, placebo-controlled, fixed-dose studies of acutely relapsed adult inpatients who met DSM-IV criteria for schizophrenia. NNT for a 30% or greater decrease in the Positive and Negative Syndrome Scale total score compared with placebo was consistently lower for the higher dose strengths of 156 and 234 mg, suggesting a therapeutic dose,response. Treatment with paliperidone palmitate at doses between 39 and 156 mg significantly delayed the time to recurrence of symptoms of schizophrenia after 24 weeks of maintained symptom stability. The NNT vs. placebo to avoid a recurrence of symptoms was 5 (95% CI 4,7). Overall, paliperidone palmitate was reasonably well tolerated, with low rates of extrapyramidal symptoms or body weight gain; however, these may be more common at higher doses. Injection site reactions occurred at a rate ranging from 4% to 10%, depending on the dose regimen, compared with 2% for the pooled placebo arms. The acquisition cost of a maintenance dose of paliperidone palmitate calculated on a per day basis is similar to that for risperidone microspheres, but about double the cost for oral paliperidone and approximately 19 times the cost of oral generic risperidone. Conclusions:, Paliperidone palmitate is efficacious for the acute and maintenance treatment of schizophrenia and is reasonably well tolerated. It offers several advantages over other available second-generation depot antipsychotics: it comes in prefilled syringes in a number of different dosage strengths; it does not require refrigeration; it does not require supplementation with oral antipsychotics; it can be administered once monthly; it can be administered with a very small bore needle; the injection volume is small; the injection site can be either the deltoid or gluteal muscles; it does not require an additional precautionary observation period after the injection. For patients for whom oral risperidone or paliperidone is otherwise effective, paliperidone palmitate offers a guaranteed delivery system that enhances adherence. However, the high acquisition cost of paliperidone palmitate will likely be an important obstacle to its routine use. [source]


Singlet Oxygen Detection in Skim Milk by Electron Spin Resonance Spectroscopy

JOURNAL OF FOOD SCIENCE, Issue 2 2003
D.G. Bradley
ABSTRACT: 2,2,6,6-Tetramethyl-4-piperidone (TMPD) can react with singlet oxygen to produce the corresponding nitroxide, 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (TAN), which can be detected by electron spin resonance (ESR) spectroscopy. ESR detected the formation of TAN in 5 ,M riboflavin phosphate buffer, or skim milk containing 20 mM TMPD during illumination. The effects of illumination, riboflavin, and oxygen on the formation of TAN indicated that the presence of each was required for singlet oxygen formation. The photo reduced riboflavin might reduce TAN to the hydroxylamine of TAN, thus decreasing the paramagnetic TAN signal. Maximum concentration of TAN was obtained at an added 10 mM riboflavin in buffer solution or in skim milk after 15 min of illumination in the presence of oxygen. [source]


Pharmacokinetics and pharmacokinetic/pharmacodynamic integration of marbofloxacin in calf serum, exudate and transudate

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2002
F. SHOJAEE ALIABADI
Aliabadi, F. S., Lees, P. Pharmacokinetics and pharmacokinetic/pharmacodynamic integration of marbofloxacin in calf serum, exudate and transudate. J. vet. Pharmacol. Therap.25, 161,174. Marbofloxacin is a fluoroquinolone antimicrobial drug used in cattle for the treatment of respiratory infections. In this investigation the pharmacokinetics (PK) of marbofloxacin were determined after intravenous and intramuscular dosing at a dosage of 2 mg/kg. In addition the ex vivo pharmacodynamics (PD) of the drug were determined in serum and three types of tissue cage fluid (transudate, inflammatory exudate generated by carrageenan and exudate generated by lipopolysaccharide). Marbofloxacin PK was characterized by a high volume of distribution after dosing by both routes (1.28 L/kg intravenous and 1.25 L/kg intramuscular). Corresponding area under the concentration,time curve (AUC) and elimination half-life (t½el) values were 9.99 and 10.11 ,g h/mL and 4.23 and 4.33 h, respectively. Values of AUC for carrageenan-induced exudate, lipopolysaccharide-induced exudate and transudate were, respectively, 8.28, 7.83 and 7.75 ,g h/mL after intravenous and 8.84, 8.53 and 8.52 ,g h/mL after intramuscular dosing. Maximum concentration (Cmax) values were similar for the three tissue cage fluids after intravenous and intramuscular dosing. For in vivo PK data values of AUC: minimum inhibitory concentration (MIC) (AUIC) ratio for serum were 250 and 253, respectively, after intravenous and intramuscular dosing of marbofloxacin against a pathogenic strain of Mannheimia haemolytica (MIC=0.04 ,g/mL). For all tissue cage fluids AUIC values were >194 and >213 after intravenous and intramuscular dosing, and Cmax/MIC ratios were 9 or greater, indicating a likely high level of effectiveness in clinical infections caused by M. haemolytica of MIC 0.04 ,g/mL or less. This was confirmed by both in vitro (serum) and ex vivo (serum, exudate and transudate) measurements, which demonstrated a concentration-dependent killing profile for marbofloxacin against M. haemolytica. Ex vivo, after 24-h incubation, virtually all bacteria were killed (<10 cfu/mL) in all samples collected up to 9 h (serum), 24 h (carrageenan-induced exudate and transudate) and 36 h (lipopolysaccharide-induced exudate). Application of the sigmoid Emax equation to the ex vivo antibacterial data provided, for serum, AUIC24 h values of 37.1 for bacteriostasis, 46.3 for bactericidal activity and 119.6 for elimination of bacteria. These data may be used as a rational basis for setting dosing schedules which optimize clinical efficacy and minimize the opportunities for emergence of resistant organisms. [source]


A randomized trial of the effects of two novel nicotine replacement therapies on tobacco withdrawal symptoms and user satisfaction

ADDICTION, Issue 7 2010
Hayden McRobbie
ABSTRACT Aims To determine effects on craving, user satisfaction, and consumption patterns of two new nicotine replacement therapies (NRT) used for eight hours after overnight tobacco abstinence. Design In a within-subject, cross-over trial participants were randomly assigned Zonnic® nicotine mouth spray (1 mg/spray), Zonnic® nicotine lozenge (2.5 mg), Nicorette® gum (4 mg) and placebo lozenge on each of four study days. Setting University research unit. Participants Forty-seven dependent adult smokers. Measurements Participants rated their urges to smoke, irritability, concentration and restlessness before and during the first hour of product use on a 100-point scale. A subsample of 11 participants provided blood samples for nicotine analysis. Findings All active products reduced craving significantly more than placebo (mean reductions of 28.6, 25.8, 24.7 and 8.9 points for mouth spray, gum, lozenge and placebo). Mouth spray relieved craving faster than placebo and gum with significant reductions within five minutes of use (mean differences of ,14.5 (95% CI: ,23.0 to ,6.0) and ,10.6 (95% CI: ,19.1 to ,2.1) with placebo and gum respectively. Mouth spray produced a faster time to maximum plasma nicotine concentration (14.5 minutes, 95% CI: 8.0 to 21.0) compared to the lozenge (30.3 minutes, 95% CI: 21.1 to 39.5) and gum (45.8 minutes, 95% CI: 36.2 to 55.4). Maximum concentrations of blood nicotine were higher with mouth spray (10.0 ng/ml) and lozenge (10.8 ng/ml) compared to gum (7.8 ng/ml). Both lozenge and mouth spray were well tolerated. Conclusions The mouth spray and lozenge are at least as effective as 4 mg nicotine gum in relieving craving suggesting that they are likely to be effective in aiding smoking cessation. The mouth spray may be particularly useful for acute craving relief. [source]


Generation of bioaerosols during manual mail unpacking and sorting

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2005
H. Brandl
Abstract Aims:, The dynamics of bioaerosol generation in specific occupational environments where mail is manually unpacked and sorted was investigated. Methods and Results:, Total number of airborne particles was determined in four different size classes (0·3,0·5, 0·5,1, 1,5 and >5 ,m) by laser particle counting. Time dependent formation of bioaerosols was monitored by culturing methods and by specific staining followed by flow cytometry. Besides handling of regular mail, specially prepared letters (,spiked letters') were added to the mailbags to deliberately release powdered materials from letters and to simulate high impact loads. These letters contained various dry powdered biological and nonbiological materials such as milk powder, mushrooms, herbs and cat litter. Regarding the four size classes, particulate aerosol composition before mail handling was determined as 83·2 ± 1·0, 15·2 ± 0·7, 1·7 ± 0·4 and 0·04 ± 0·02%, respectively, whereas the composition changed during sorting to 66·8 ± 7·9, 22·3 ± 3·6, 10·4 ± 4·0 and 0·57 ± 0·27%, respectively. Mail processing resulted in an increase in culturable airborne bacteria and fungi. Maximum concentrations of bacteria reached 450 CFU m,3, whereas 270 CFU of fungi were detected. Conclusions:, Indoor particle concentrations steadily increased during mail handling mostly associated with particles of diameters >1 ,m. However, it was not possible to distinguish spiked letters from nonspiked by simple particle counting and CFU determinations. Significance and Impact of Study:, The dynamics of bioaerosol generation have to be addressed when monitoring specific occupational environments (such as mail sorting facilities) regarding the occurrence of biological particles. [source]


Persistent Organic Pollutants in Fish Oil Supplements on the Canadian Market: Polychlorinated Biphenyls and Organochlorine Insecticides

JOURNAL OF FOOD SCIENCE, Issue 1 2009
Dorothea F.K. Rawn
ABSTRACT:, Fish and seal oil dietary supplements, marketed to be rich in omega-3 fatty acids, are frequently consumed by Canadians. Samples of these supplements (n,= 30) were collected in Vancouver, Canada, between 2005 and 2007. All oil supplements were analyzed for polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs) and each sample was found to contain detectable residues. The highest ,PCB and ,DDT (1,1,1-trichloro-di-(4-chlorophenyl)ethane) concentrations (10400 ng/g and 3310 ng/g, respectively) were found in a shark oil sample while lowest levels were found in supplements prepared using mixed fish oils (anchovy, mackerel, and sardine) (0.711 ng ,PCB/g and 0.189 ng ,DDT/g). Mean ,PCB concentrations in oil supplements were 34.5, 24.2, 25.1, 95.3, 12.0, 5260, 321, and 519 ng/g in unidentified fish, mixed fish containing no salmon, mixed fish with salmon, salmon, vegetable with mixed fish, shark, menhaden (n,= 1), and seal (n,= 1), respectively. Maximum concentrations of the other OCs were generally observed in the seal oil. The hexachlorinated PCB congeners were the dominant contributors to ,PCB levels, while ,DDT was the greatest contributor to organochlorine levels. Intake estimates were made using maximum dosages on manufacturers' labels and results varied widely due to the large difference in residue concentrations obtained. Average ,PCB and ,DDT intakes were calculated to be 736 ± 2840 ng/d and 304 ± 948 ng/d, respectively. [source]


IMPACT OF COAL SURFACE MINING AND RECLAMATION ON SUSPENDED SEDIMENT IN THREE OHIO WATERSHEDS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2000
James V. Bonta
ABSTRACT: Prior to PL95,87 little research had been conducted to determine the impacts of mining and reclamation practices on sediment concentrations and yields on a watershed scale. Furthermore, it was unknown whether sediment yield and other variables would return to undisturbed levels after reclamation. Therefore, three small watersheds, with differing lithologies and soils, were monitored for runoff and suspended sediment concentrations during three phases of watershed disturbances: undisturbed watershed condition, mining and reclamation disturbances, and post-reclaimed condition. Profound increases in suspended-sediment concentrations, load rates, and yields due to mining and reclamation activities, and subsequent drastic decreases after reclamation were documented. Even with increases in runoff potential, reductions in suspended-sediment concentrations and load rates to below or near undisturbed-watershed levels is possible by using the mulch-crimping technique and by removing diversions. Maximum concentrations and load rates occurred during times of active disturbances that exposed loose soil and spoil to high-intensity rains. Sediment concentrations remained elevated compared with the undisturbed watershed when diversions were not well maintained and overtopped, and when they were not removed for final reclamation. Diversions are useful for vegetation establishment, but should be maintained until they are removed for final reclamation after good vegetative cover is established. [source]


Quantitative repeated open application testing with a rinse-off product in methyldibromo glutaronitrile-sensitive patients: results of the IVDK

CONTACT DERMATITIS, Issue 6 2010
Annice Heratizadeh
Background: While the use of methyldibromo glutaronitrile (MDBGN) in leave-on products is clearly associated with high sensitization or elicitation risk, such a clear-cut relation could be questioned with regard to rinse-off products. Objective: The objective of this study was to find a maximum non-eliciting concentration for rinse-off products in MDBGN patch test-positive patients. Patients and methods: We performed a use-related test [repeated open application test (ROAT)] in patients sensitized to MDBGN with a liquid soap containing three concentrations of MDBGN (50, 200, and 400 p.p.m. MDBGN, respectively). The soap at 50 p.p.m. was used twice daily for 4 weeks. If no reaction of the skin was observed, the product with the next higher concentration was used for another 4 weeks, etc. Results: In total, 32/37 evaluated cases [86.5%; lower exact one-sided 95% confidence limit (CL): 73.7%] did not react to any of the preparations. The remaining reacted as follows: 1/37 reacted to 50 p.p.m., 3/37 to 200 p.p.m., and 1/37 to 400 p.p.m. The cumulative non-response to 50 p.p.m. was 97.3% (lower CL: 87.8%). Conclusions: The majority of subjects sensitized to MDBGN-tolerated rinse-off products containing a maximum concentration of 400 p.p.m. A concentration in rinse-off products in the range of 50 p.p.m. could be regarded as safe for most individuals already sensitized. These concentrations will presumably prevent induction (sensitization) also. [source]


Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix -dominated freshwater lakes

ENVIRONMENTAL MICROBIOLOGY, Issue 10 2005
Ingmar Janse
Summary Microcystin concentrations in two Dutch lakes with an important Planktothrix component were related to the dynamics of cyanobacterial genotypes and biovolumes. Genotype composition was analysed by using denaturing gradient gel electrophoresis (DGGE) profiling of the intergenic transcribed spacer region of the rrn operon (rRNA-ITS), and biovolumes were measured by using microscopy. In Lake Tjeukemeer, microcystins were present throughout summer (maximum concentration 30 µg l,1) while cyanobacterial diversity was low and very constant. The dominant phototroph was Planktothrix agardhii. In contrast, Lake Klinckenberg showed a high microcystin peak (up to 140 µg l,1) of short duration. In this lake, cyanobacterial diversity was higher and very dynamic with apparent genotype successions. Several genotypes derived from DGGE field profiles matched with genotypes from cultures isolated from field samples. The microcystin peak measured in Lake Klinckenberg could be confidently linked to a bloom of Planktothrix rubescens, as microscopic and genotypic analysis showed identity of bloom samples and a toxin-producing P. rubescens culture. Toxin-producing genotypes were detected in the microbial community before they reached densities at which they were detected by using microscopy. Cyanobacterial biovolumes provided additional insights in bloom dynamics. In both lakes, the microcystin content per cell was highest at the onset of the blooms. Our results suggest that while genotypic characterization of a lake can be valuable for detection of toxic organisms, for some lakes a monitoring of algal biomass has sufficient predictive value for an assessment of toxin production. [source]


Acute and chronic toxicity of nickel to marine organisms: Implications for water quality criteria

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2002
John W. Hunt
Abstract Acute and chronic toxicity tests were conducted to determine the effects of nickel on three U.S. west coast marine species: a fish (the topsmelt, Atherinops affinis), a mollusk (the red abalone, Haliotis rufescens), and a crustacean (the mysid, Mysidopsis intii). The 96-h median lethal concentration (LC50) for topsmelt was 26,560 mg/L, and the chronic value for the most sensitive endpoint in a 40-d exposure was 4,270 mg/L. The median effective concentration (EC50) for 48-h abalone larval development was 145.5 ,g/L, and the chronic value for juvenile growth in a 22-d exposure through larval metamorphosis was 26.43 mg/L. The mysid 96-h LC50 was 148.6 ,g/L, and the chronic value for the most sensitive endpoint in a 28-d, whole life-cycle exposure was 22.09 ,g/L. The abalone and mysid acute values were lower than other values available in the literature. Acute-tochronic ratios for nickel toxicity to the three species were 6.220, 5.505, and 6.727, respectively, which were similar to the only other available saltwater value of 5.478 (for Americamysis [Mysidopsis] bahia) and significantly lower than the existing values of 35.58 and 29.86 for freshwater organisms. Incorporation of data from the present study into calculations for water quality criteria would lower the criterion maximum concentration and raise the criterion continuous concentration for nickel. [source]


Modelling of colloid leaching from unsaturated, aggregated soil

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2007
M. Laegdsmand
Summary The migration of colloids in soils can enhance the leaching of strongly sorbing contaminants. We present a model for the simulation of colloid leaching from unsaturated, aggregated soil media under stationary flow. Transport in the intra-aggregate pores is simulated by convection,dispersion, and transport in the interaggregate pores, and a stagnant layer of water surrounding the aggregates, is simulated by diffusion. The model describes the release of colloids from soil aggregates, sorption and desorption processes at the air,water interfaces, and flocculation and subsequent straining from the flowing water. All three processes were simulated as functions of ionic strength. Transport of ions in intra-aggregate pores was simulated by Fickian diffusion. The model was calibrated against experimental results of colloid leaching from columns packed with natural soil aggregates. The aggregates were of two soils differing in organic matter content. On each soil a single calibrated parameter set could describe the experiments with the three ionic strengths. The parameters for release of colloids from the aggregate surface and the sorption properties of the air,water interface were different for the two soils. The key parameters for leaching were the thickness of the stagnant layer of water surrounding the aggregates, the mechanical dispersion, the maximum concentration of colloids at the surface of the aggregates, the sorption capacity and rate coefficient of the colloids at the air,water interface, and the colloid diffusion coefficient. Simulations were also done with two additional irrigation intensities at one ionic strength. Simulated leaching was greater than measured leaching at both irrigation intensities, but the diffusion-controlled release of colloids from the aggregates was simulated correctly. [source]


Liquid,vapour partition of ethanol in bakery products

FLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2006
Paola Pittia
Abstract Ethanol is a common ingredient in formulated foods, naturally present or added in liquid form in order to achieve the desired sensorial properties. In many complex foods this volatile compound could also serve interesting technological functions, as well as extending their shelf-lives, owing to its capacity to inhibit or reduce the rate of microbial growth. At the European level there are no known restrictions regarding the use of ethanol in foods as a preservative, while in Italy, current regulations allow its addition as an anti-moulding agent in pre-packed bread, at a maximum concentration of 2% on a dry weight basis. This research studied the effect of water activity (aw) and water content on the ethanol vapour pressure of sliced white bread, previously equilibrated at various aw values and with 2% ethanol added. Different aw values were obtained by both rehydration from previously freeze-dried bread, and dehydration from the fresh product. The results showed that both aw and moisture affected the vapour pressure of ethanol as a consequence of water,solute and ethanol,solute interactions in the matrix. These interactions varied according to the modality of equilibration (desorption or absorption) at a given aw. The results are discussed in terms of ethanol activity (ae), computed as the ratio between the ethanol vapour pressure in bread and the vapour pressure of pure ethanol at the same temperature. This index, analogous to aw, proved to be useful in evaluating the ,freedom' of the ethanol present in a food matrix to be released in the vapour phase. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Determination of enalapril and enalaprilat by enzyme linked immunosorbent assays: application to pharmacokinetic and pharmacodynamic analysis

FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2002
Khalid Matalka
We have developed two enzyme linked immunosorbent assay (ELISA) methods for determining enalapril and enalaprilat in plasma. In this study, 48 healthy subjects received an oral dose of either 10 or 20 mg of enalapril and plasma concentrations of enalapril and enalaprilat were determined by their specific ELISA methods. These plasma concentrations and blood pressure measurements were applied to evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of both enalapril and enalaprilat. The enalapril values for the area under the curve (AUC0,,) were 480 ± 216 and 832 ± 325 ngh/mL, maximum plasma concentrations (Cmax) were 310 ± 187 and 481 ± 185 ng/mL, and times required to reach the maximum concentration (tmax) were 1.13 ± 0.22 and 1.09 ± 0.33 h for 10 and 20 mg doses, respectively. The enalaprilat values for AUC0,, were 256 ± 122 and 383 ± 158 ngh/mL, Cmax values were 57 ± 29 and 72.9 ± 33.6 ng/mL and tmax values were 4.28 ± 1.45 and 4.05 ± 01.22 h for 10 and 20 mg doses, respectively. The Cmax values of enalapril were ,10 times higher than those in the literature, which were determined by angiotensin converting enzyme (ACE) inhibition assays following alkaline hydrolysis, but similar to those of enalaprilat. The PD profiles revealed a significant correlation between enalaprilat concentrations in plasma and the decrease in systolic and diastolic blood pressures (r=,0.95 with P < 0.001 and r=,0.95 with P < 0.001), respectively, following a single oral dose of enalapril. These ELISA methods have the advantage of being simple, accurate, sensitive, and do not depend on enalaprilat binding to ACE. Such methods can be used for analysis and kinetic testing of enalapril and enalaprilat in biological fluids. [source]


Controllable Soluble Protein Concentration Gradients in Hydrogel Networks,

ADVANCED FUNCTIONAL MATERIALS, Issue 21 2008
Brian J. Peret
Abstract Here, controlled formation of sustained, soluble protein concentration gradients within hydrated polymer networks is reported. The approach involves spatially localizing proteins or biodegradable, protein-loaded microspheres within hydrogels to form a protein-releasing "depot." Soluble protein concentration gradients are then formed as the released protein diffuses away from the localized source. Control over key gradient parameters, including maximum concentration, gradient magnitude, slope, and time dynamics, is achieved by controlling the release of protein from the depot and subsequent transport through the hydrogel. Results demonstrate a direct relationship between the amount of protein released from the depot and the source concentration, gradient magnitude, and slope of the concentration gradient. In addition, an inverse relationship exists between the diffusion coefficient of protein within the hydrogel and the slope of the concentration gradient. The time dynamics of the concentration gradient profile can be directly correlated to protein release from the localized source, providing a mechanism for temporarily controlling gradient characteristics. Therefore, each key biologically relevant parameter associated with the protein concentration gradient can be controlled by defining protein release and diffusion. It is anticipated that the resulting materials may be useful in 3D cell culture systems, and in emerging tissue engineering approaches that aim to regenerate complex, functional tissues. [source]


Clinical Pharmacokinetics of Frovatriptan

HEADACHE, Issue 2002
P. Buchan PhD
Objective.,To review available data on the clinical pharmacokinetics of frovatriptan. Background.,Preclinical data suggest that the pharmacokinetic profile of frovatriptan may differ from that of the currently available triptans. Methods.,Studies of healthy volunteers, subjects with renal or hepatic impairment, elderly subjects, and patients with migraine during and between attacks were reviewed. Results.,Oral bioavailability of frovatriptan is 22% to 30%, and although the time to maximum concentration is typically 2 to 3 hours, approximately 60% to 70% of plasma maximum concentration is achieved within 1 hour of dosing. Frovatriptan distributes into erythrocytes, with binding reversible and time dependent. The relatively long terminal elimination half-life (about 26 hours) confers good systemic exposure and may produce a long duration of therapeutic action, thus reducing migraine recurrence and the need for redosing. Systemic exposure to frovatriptan generally correlates with dose between 1 and 100 mg. Blood and plasma frovatriptan concentrations are consistently higher in females, but there is no need to adjust dose according to gender. Pharmacokinetics are essentially unaffected by food and were predictable after repeat dosing; steady state is approached in about 4 to 5 days. Pharmacokinetics were changed only slightly in subjects with renal impairment or mild-to-moderate hepatic impairment, elderly individuals, and during migraine attacks. Frovatriptan is principally metabolized by the CYP1A2 isoenzyme of cytochrome P-450 and is cleared by the kidney and liver, each having sufficient capacity to compensate for impairment of the other. Conclusions.,Frovatriptan can be taken without regard for food intake, and because of the large therapeutic margin and shallow dose-response curve, there is no need for dosage adjustment in the elderly, in women taking a combined oral contraceptive, in patients with mild-to-severe renal impairment, mild-to-moderate hepatic impairment, or according to gender. The long duration of exposure may reduce the likelihood of early migraine recurrence. [source]


Feather keratin hydrolysis by a Vibrio sp. strain kr2

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2000
S. Sangali
The aim of the study was to characterize feather-degrading bacteria isolated from poultry industry waste. A Vibrio sp. strain kr2 producing a high keratinolytic activity when cultured on native feather-containing broth was isolated. The bacterium grew with an optimum at pH 6·0 and 30 °C, where maximum feather-degrading activity was also observed. Keratinase production was similar at both 25 and 30 °C, while the maximum concentration of soluble protein was reached at 30 °C. Reduction of disulphide bridges was also observed, increasing with cultivation time. The keratinase of strain kr2 was active on azokeratin, azocasein, benzoyl-arginine- p -nitroanilide and Ala-Ala- p -nitroanilide as substrates. The amino acid composition of the feather hydrolysate was determined, presenting similarities with that reported for feather lysate, feather meal and raw feathers. A novel feather-degrading bacterium was isolated and characterized, showing high keratinolytic activity. Complete feather degradation was achieved during cultivation. Strain kr2 shows potential for use for biotechnological processes involving keratin hydrolysis. [source]


Synthesis of Diacylglycerols Containing CLA by Lipase-Catalyzed Esterification

JOURNAL OF FOOD SCIENCE, Issue 7 2006
In-Hwan Kim
ABSTRACT:, Diacylglycerols (DAG) were prepared by esterification of glycerol with conjugated linoleic acid (CLA) in the presence of an immobilized 1,3-regiospecific lipase from Rhizomucor miehei and vacuum conditions. The effects of several parameters, namely, temperature, enzyme loading, stirring speed, and vacuum, on the concentration and the purity of the DAG were studied. The reaction temperature influenced both the reaction rate and the concentration of the DAG. The rate of DAG synthesis increased as the enzyme loading increased. However, for high enzyme loadings, the concentration of triacylglycerols (TAG) increased significantly at long reaction times and, as a result, the purity of the DAG decreased. When the stirring speed increased from 150 to 450 rpm, the DAG concentration increased significantly. However, at stirring speeds above 450 rpm, no significant increases in DAG concentration were observed. When the pressure was decreased from 20 to 3 mmHg, the maximum concentration of DAG increased from 76.0% to 80.5%. No increase in the DAG concentration was observed when the pressure was decreased from 3 to 1 mm Hg, even though a slightly higher DAG purity was achieved at 1 mm Hg. For the range of absolute pressures tested, the concentrations of 1,2-DAG were less than 1%. [source]


Improvement of dissolution and oral absorption of ER-34122, a poorly water-soluble dual 5-lipoxygenase/cyclooxygenase inhibitor with anti-inflammatory activity by preparing solid dispersion

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002
Ikuo Kushida
Abstract Several formulation approaches were attempted to improve the dissolution and the oral absorption of ER-34122, which is a novel dual 5-lipoxygenase/cyclooxygenase inhibitor with potent anti-inflammatory activity. The solid dispersion of ER-34122 with hydroxypropylmethylcellulose (TC-5RW), which is an inert solid carrier, resulted in a significant improvement in the dissolution rate of ER-34122. The solid dispersion was prepared by a solvent evaporation method using ethanol and water. The solid-state characteristics of the solid dispersion, the corresponding physical mixture, and ER-34122 alone were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy (FTIR), and an automated controlled-atmosphere microbalance. The X-ray powder diffraction patterns suggest that the solid dispersion exists in a totally amorphous state and the others exist in a crystalline state. The FTIR spectra results suggest that ER-34122 can interact with TC-5RW through intermolecular hydrogen bonding in the solid dispersion. This interaction may cause a stabilization of ER-34122 in the higher-energy, faster-dissolving amorphous state. The dissolution rate of ER-34122 from the solid dispersion was significantly greater than that from the physical mixture or the pure drug. Furthermore, when orally administrated to beagle dogs, ER-34122 showed about a 100-fold increase in both maximum concentration (Cmax) and area under the curve of concentration versus time (AUC) compared with the pure drug. Consequently, it was determined that the solid dispersion technique with TC-5RW provides a promising way to increase the dissolution rate and the oral absorption of poorly water-soluble drugs such as ER-34122. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:258,266, 2002 [source]


Carrier proteins determine local pharmacokinetics and arterial distribution of paclitaxel

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2001
Mark A. Lovich
Abstract The growing use of local drug delivery to vascular tissues has increased interest in hydrophobic compounds. The binding of these drugs to serum proteins raises their levels in solution, but hinders their distribution through tissues. Inside the arterial interstitium, viscous and steric forces and binding interactions impede drug motion. As such, this might be the ideal scenario for increasing the amount of drug delivered to, and residence time within, arterial tissues. We quantified carrier-mediated transport for paclitaxel, a model hydrophobic agent with potential use in proliferative vascular diseases, by determining, in the presence or absence of carrier proteins, the maximum concentration of drug in aqueous solution, the diffusivity in free solution, and the diffusivity in arterial tissues. Whereas solubility of paclitaxel was raised 8.1-, 21-, and 57-fold by physiologic levels of ,1 -acid glycoproteins, bovine serum albumin, and calf serum over that in protein-free solution, diffusivity of paclitaxel in free solution was reduced by 41, 49, and 74%, respectively. When paclitaxel mixed in these solutions was applied to arteries both in vitro and in vivo, drug was more abundant at the tissue interface, but protein carriers tended to retain drug in the lumen. Once within the tissue, these proteins did not affect the rate at which drug traverses the tissue because this hydrophobic drug interacted with the abundant fixed proteins and binding sites. The protein binding properties of hydrophobic compounds allow for beneficial effects on transvascular transport, deposition, and distribution, and may enable prolonged effect and rationally guide local and systemic strategies for their administration. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1324,1335, 2001 [source]


Pharmacokinetic characterization of 14C-vascular endothelial growth factor controlled release microspheres using a rat model

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2002
Tae-Kyoung Kim
The objectives of this study were to characterize the pharmacokinetics of vascular endothelial growth factor (VEGF) in poly(lactic-co-glycolic) acid (PLGA) microspheres using a rat model, and to develop a pharmacokinetic model for this controlled release formulation. 14C-VEGF was encapsulated using a solid-in-oil-in-water emulsification method. The microspheres were administered subcutaneously to rats and the pharmacokinetic parameters were compared with those of protein solutions. Intravenous administration of protein solutions resulted in short half-lives and subcutaneous administration resulted in rapid clearance from the subcutaneous tissue, with high plasma concentrations as expressed by rapid absorption and elimination. The subcutaneous administration of the VEGF microspheres produced low plasma concentrations and high subcutaneous concentrations over a period of 7 weeks. The area under the curve (AUC), the time required to achieve the maximum concentration (tmax), the maximum concentration (Cmax) in blood samples and the elimination rate constant (kel) values at the subcutaneous tissue site were selected to compare the pharmacokinetic characterization of VEGF microspheres with that of protein solutions. The in-vivo release profiles of the proteins were slower than the in-vitro release profiles and they followed the same trend as the in-vitro and in-vivo PLGA degradation rates. The PLGA microsphere degradation was the determinant step for VEGF release from the microspheres and its absorption at the subcutaneous site. Microspheres appear to be an attractive system for the localized rate-controlled delivery of VEGF. 14C-Methylation via reductive alkylation of VEGF did not affect its mitogenic activity, however approximately 25% activity was lost following release from PLGA microspheres. This loss of activity may be due to degradation in an acidic environment as a result of PLGA degradation. [source]


Crystallographic Texture Development in Bismuth Sodium Titanate Prepared by Reactive-Templated Grain Growth Method

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2004
Toshio Kimura
Bi0.5Na0.5TiO3 (BNT) and 0.94Bi0.5Na0.5TiO3·0.06BaTiO3 (BNT,BT) bulk ceramics with extensive ,100, texture were prepared by the reactive-templated grain growth method, using platelike Bi4Ti3O12 (BIT) particles as templates for BNT. Calcined compacts were composed of matrix grains with random orientation and ,100,-oriented grains transformed from aligned BIT particles, and the texture developed by the growth of oriented grains during sintering. Ceramics with extensive texture were obtained by using the starting mixture containing the maximum concentration of platelike BIT to form the maximum volume fraction of oriented grains. [source]


Pharmacokinetics and pharmacokinetic/pharmacodynamic integration of orbifloxacin in Korean Hanwoo cattle

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2009
G. ELIAS
The pharmacokinetics and pharmacodynamics of orbifloxacin were studied in six clinically healthy Hanwoo cows after intravenous (i.v.) and intramuscular (i.m.) administration at a dose of 3 mg/kg. Orbifloxacin concentrations were determined by high performance liquid chromatography with fluorescence detection. Steady-state volume of distribution and clearance of orbifloxacin after i.v. administration were 0.92 L/kg and 0.24 L/h·kg, respectively. Following i.m. administration, a slow and complete absorption with absolute bioavailability of 101.4%, and a maximum concentration (Cmax) of 1.17 ,g/mL at 1.04 h were observed. The in vitro serum protein binding was 14.76%. The in vitro antibacterial activity of orbifloxacin against a pathogenic strain of Mannheimia haemolytica (M. haemolytica), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was determined. The ex vivo activity of orbifloxacin against M. haemolytica strain was also determined, and these data were integrated with the ex vivo bacterial counts to establish AUC24h/MIC values producing bacteriostatic action, bactericidal action and elimination of bacteria. Mean values were 32.7, 51.6 and 102.6 h, respectively. From these data, we predict that orbifloxacin, when administered i.m. at a dosage of 2.5,5 mg/kg once a day, would be effective against bovine pathogens, such as M. haemolytica. Additional studies may be needed to confirm its efficacy in a clinical setting, and to evaluate the penetration of the drug in diseased tissues. [source]


Hydrogenated castor oil nanoparticles as carriers for the subcutaneous administration of tilmicosin: in vitro and in vivo studies

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2009
C. HAN
Tilmicosin-loaded solid lipid nanoparticles (SLN) were prepared with hydrogenated castor oil (HCO) by o/w emulsion,solvent evaporation technique. The nanoparticle diameters, surface charges, drug loadings and encapsulation efficiencies of different formulations were 90,230 nm, ,6.5,,12.5 mV, 40.3,59.2% and 5.7,11.7% (w/w), respectively. In vitro release studies of the tilmicosin-loaded nanoparticles showed a sustained release and the released tilmicosin had the same antibacterial activity as that of the free drug. Pharmacokinetics study after subcutaneous administration to Balb/c mice demonstrated that a single dose of tilmicosin-loaded nanoparticles resulted in sustained serum drug levels (>0.1 ,g/mL) for 8 days, as compared with only 5 h for the same amount of tilmicosin phosphate solution. The time to maximum concentration (Tmax), half-life of absorption (T½ ab) and half-life of elimination (T½ el) of tilmicosin-loaded nanoparticles were much longer than those of tilmicosin phosphate solution. Tissue section showed that drug-loaded nanoparticles caused no inflammation at the injection site. Cytotoxicity study in cell culture and acute toxicity test in mice demonstrated that the nanoparticles had little or no toxicity. The results of this exploratory study suggest that the HCO,SLN could be a useful system for the delivery of tilmicosin by subcutaneous administration. [source]


Relative oral bioavailability of microgranulated amoxicillin in pigs

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2002
P. Anfossi
A new microgranulated formulation of amoxicillin trihydrate for in-feed medication was developed using a lipogelled matrix. Its relative bioavailability was compared with powdered drug in pigs and an assessment was made to determine whether therapeutic concentrations were achieved. Microgranules containing 10% (MICR10) and 30% (MICR30) amoxicillin and free amoxicillin trihydrate powder (reference, AMX) were administered at dosages of 50 mg of amoxicillin/kg b.w. using a three-way-crossover design. Amoxicillin analysis in serum was performed by a sensitive high performance liquid chromatography (HPLC) method with fluorometric detection, using an extraction procedure already described for edible tissues of fish and adapted and validated for pig serum. The oral bioavailability of both microgranulated formulations was higher than that of the reference formulation [relative bioavailability (F): 153.9 ± 58.2% for MICR10; 126.2 ± 70.5% for MICR30] and the area under the concentration,time curve (AUC) values of MICR10 and AMX formulations were significantly different (P < 0.05). Differences between the mean maximum concentration (Cmax), time of Cmax (tmax) and mean residence time (MRT) of the drug formulations were not significant. Microgranulated amoxicillin is suitable for in-feed administration to pigs and, because of its higher oral bioavailability compared with the powdered compound, it may be more effective for the treatment of susceptible infections. [source]


Pharmacokinetics of ibafloxacin following intravenous and oral administration to healthy Beagle dogs

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2002
M. COULET
The pharmacokinetics of ibafloxacin, a new veterinary fluoroquinolone antimicrobial agent, was studied following intravenous (i.v.) and oral administration to healthy dogs. The mean absolute bioavailability of ibafloxacin after oral doses of 7.5, 15 and 30 mg/kg ranged from 69 to 81%, indicating that ibafloxacin was well absorbed by dogs. Ibafloxacin was also absorbed rapidly [time of maximum concentration (tmax) 1.5 h], reaching a mean maximum concentration (Cmax) of 6 ,g/mL at 15 mg/kg, well distributed in the body [large volume of distribution at steady state (Vss) and Varea of 1.1 L/kg and 4 L/kg, respectively], and exhibited an elimination half-life of 5.2 h and a low total body clearance (8.7 mL/min/kg). Both Cmax and area under the concentration,time curve (AUC) showed dose proportionality over the dose range tested (7.5,30 mg/kg). The pharmacokinetics of ibafloxacin was similar following single and repeated dosage regimens, implying no significant accumulation in plasma. Food promoted the absorption of ibafloxacin by increasing Cmax and AUC, but did not change tmax. High amounts of the metabolites, mainly 8-hydroxy- and, 7-hydroxy-ibafloxacin were excreted in urine and faeces, either unchanged or as glucuronide conjugates. Following oral administration of 15 mg ibafloxacin/kg, the total recovery of ibafloxacin, its metabolites and conjugates in urine and faeces was 61.9,99.9% of the dose within 48 h. [source]


Bioavailability and disposition of sodium and procaine penicillin G (benzylpenicillin) administered orally with milk to calves

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2001
J. M. B. Musser
Eighteen 1-week-old Holstein calves were randomly assigned to one of three groups: (a) sodium penicillin G administered intravenously, (b) sodium penicillin G administered orally, or (c) procaine penicillin G administered orally. All calves were dosed with penicillin G at 4.0 mg/kg BW. At 5 weeks of age, the calves were dosed again. Blood samples were taken serially for 24 h after both dosings. Plasma was assayed for penicillin G by high performance liquid chromatography (HPLC). For i.v. administration, the area under the concentration,time curve (AUC), 7456 and 5508 ng/mL h, and systemic clearance, 0.54 and 0.73 L/kg h, were significantly different (P < 0.05) at 1 and 5 weeks of age, respectively. There were no significant differences between orally administered sodium and procaine penicillin G within the same age groups. Following oral (p.o.) administration, there were significant differences (P < 0.01) at 1 and 5 weeks of age in the AUC, 760 and 409 ng/mL h, terminal half-life, 2.1 and 1.6 h, time of maximum concentration (TMAX), 3.0 and 2.3 h, and maximum plasma concentration (CMAX), 85 and 58 ng/mL, respectively. Bioavailability was 10.2 and 7.4% at 1 and 5 weeks, respectively. [source]


Plasma pharmacokinetics of warfarin enantiomers in cats

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2000
S.A. SMITH
The purpose of this study was to determine the dispositions of S-warfarin and R-warfarin in normal cats following intravenous and oral administrations of racemic warfarin. Citrated blood samples were collected from 10 cats prior to and at times 5, 15, and 30 min, 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 72, 96, and 120 h following a single intravenous bolus of 0.5 mg/kg of racemic warfarin. After a 21-day washout period, samples were then similarly collected in three groups of four cats for 120 h following oral administration of 0.1, 0.25, and 0.5 mg/kg racemic warfarin. S-warfarin and R-warfarin were detected using a high-performance liquid chromatography assay validated for cat plasma. Drug concentration,time curves were subjected to non-compartmental analysis. Median pharmacokinetic parameters associated with the intravenous administration of 0.5 mg/kg racemic warfarin were as follows: t1/2 (S:28.2, R:18.3 h), area under the plasma concentration,time curve (AUC; S:33.0, R:24.6 h*,g/mL), area under the moment curve (AUMC; S:1889, R:527.8 h*h*,g/mL), and mean residence time (MRT; S:38.7, R:20.9 h). For each parameter, S-warfarin was significantly different from R-warfarin (P<0.05). Warfarin was absorbed rapidly after oral administration, and the dosage did not affect the time to maximum concentration (S:0.87, R:0.75 h). Oral dosage significantly influenced maximum plasma concentration (ng/mL, S:1267, R:1355 at 0.5 mg/kg; S:614.9, R:679.4 at 0.25 mg/kg; S:250.5, R:367.6 at 0.1 mg/kg), AUC (h*,g/mL, S:45.12, R:30.91 at 0.5 mg/kg; S:22.98:, R:18.99 at 0.25 mg/kg; S:3.922, R:3.570 at 0.1 mg/kg) and AUMC (h*h*,g/mL, S:2135, R:1062 at 0.5 mg/kg; S:943.1, R:599.9 at 0.25 mg/kg; S:132.2, R:59.03 at 0.1 mg/kg), but not t1/2 (S:23.5, R:11.6 h) nor MRT (S:26.3, R:13.5 h). Both warfarin enantiomers were highly (>96.5%) protein-bound. Quantitation of the warfarin content in commercially available tablets indicated an unequal distribution of the drug throughout the tablet. [source]


Inactivation of Salmonella enterica serovar enteritidis in shell eggs by sequential application of heat and ozone

LETTERS IN APPLIED MICROBIOLOGY, Issue 6 2008
J.J. Perry
Abstract Aims:, To assess the contribution of ozone to lethality of Salmonella enterica serovar Enteritidis in experimentally inoculated whole shell eggs that are sequentially treated with heat and gaseous ozone in pilot-scale equipment. Methods and Results:, Whole shell eggs were inoculated with small populations of Salmonella Enteritidis (8·5 × 104,2·4 × 105 CFU per egg) near the egg vitelline membrane. Eggs were subjected to immersion heating (57°C for 21 min), ozone treatment (vacuum at 67·5 kPa, followed by ozonation at a maximum concentration of approx. 140 g ozone m,3 and 184,198 kPa for 40 min) or a combination of both treatments. Survivors were detected after an enrichment process or enumerated using modified most probable number technique. Ozone, heat and combination treatments inactivated 0·11, 3·1 and 4·2 log Salmonella Enteritidis per egg, respectively. Conclusions:, Sequential application of heat and gaseous ozone was significantly more effective than either heat or ozone alone. The demonstrated synergy between these treatment steps should produce safer shell eggs than the heat treatment alone. Significance and Impact of the Study:, Shell eggs are the most common vehicle for human infection by Salmonella Enteritidis. Many cases of egg-related salmonellosis are reported annually despite efforts to reduce contamination, including thermal pasteurization of shell eggs and egg products. Treatment with ozone-based combination should produce shell eggs safer than those treated with heat alone. [source]


Pharmacokinetics of valerenic acid after single and multiple doses of valerian in older women

PHYTOTHERAPY RESEARCH, Issue 10 2010
Gail D. Anderson
Abstract Insomnia is a commonly reported clinical problem with as many as 50% of older adults reporting difficulty in falling and/or remaining asleep. Valerian (Valeriana officinalis) is a commonly used herb that has been advocated for promoting sleep. Valerenic acid is used as a marker for quantitative analysis of valerian products with evidence of pharmacological activity relevant to the hypnotic effects of valerian. The objective of this study was to determine the pharmacokinetics of valerenic acid in a group of elderly women after receiving a single nightly valerian dose and after 2 weeks of valerian dosing. There was not a statistically significant difference in the average peak concentration (Cmax), time to maximum concentration (Tmax) area under the time curve (AUC), elimination half-life (T1/2) and oral clearance after a single dose compared with multiple dosing. There was considerable inter- and intra-subject variability in the pharmacokinetic parameters. Cmax and AUC deceased and T1/2 increased with increased body weight. The variability between the capsules was extremely low: 2.2%, 1.4% and 1.4%, for hydroxyvalerenic acid, acetoxyvalerenic acid and valerenic acid, respectively. In conclusion, large variability in the pharmacokinetics of valerenic acid may contribute to the inconsistencies in the effect of valerian as a sleep aid. Copyright © 2010 John Wiley & Sons, Ltd. [source]


Growth-related variations in the Bacillus cereus secretome

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 10 2007
Nathalie Gilois
Abstract Using 2-DE, transcriptional gene fusions and cell cytotoxicity assays, we followed changes in the Bacillus cereus strain ATCC14579 secretome, gene expression and culture supernatant cytotoxicity from the end of the vegetative phase up to 5,h after entry into the stationary phase. The concentration of each of the 22 proteins in the culture supernatant was determined at various times. In addition, the stability of the proteins was studied. Fifteen of these proteins, including 14 members of the virulence regulon PlcR, were known or predicted to be secreted. All of the secreted proteins reached a maximum concentration during early stationary phase, but there were significant differences in the kinetics of their concentrations. The time courses of protein concentrations were in agreement with gene expression data, except for cytotoxin CytK, which was unstable, and for the metalloprotease InhA1. Supernatant cytoxicity also peaked in early stationary phase, and the kinetics of cytotoxicity paralleled the time course of concentration of the PlcR-controlled toxin, CytK. Our concomitant study of the time course of protein concentrations, gene expression and supernatant cytotoxicity reveals that the pathogenic potential of B. cereus peaks during the transition state. It also suggests that there is diversity in the regulation of gene expression within the PlcR regulon. [source]