By F. Thorus. University of Houston, Downtown.
Another larly in inhalation experiments; (iii) whether the consideration is that chemical and toxicological doses cheap sildalis 120mg overnight delivery erectile dysfunction protocol foods, duration of treatment and route of expo- interactions of components in a mixture may sure were appropriate; (iv) whether the survival alter dose–response relationships order 120mg sildalis otc impotence forum. Te relevance of treated animals was similar to that of con- to human exposure of the test mixture adminis- trols; (v) whether there were adequate numbers tered in the animal experiment is also assessed. When benign tumours (a) occur together Te relevance of results obtained with an with and originate from the same cell type as agent that is analogous (e. Such results may provide stage in the progression to malignancy, they are biological and mechanistic information that is usually combined in the assessment of tumour relevant to the understanding of the process of incidence (Huf et al. Te occurrence of carcinogenesis in humans and may strengthen lesions presumed to be preneoplastic may in cer- the biological plausibility that the agent being tain instances aid in assessing the biological plau- evaluated is carcinogenic to humans (see Part B, sibility of any neoplastic response observed. When detailed informa- ground and age of the animal, and on the dose, tion on survival is not available, comparisons route, timing and duration of the exposure. Te lethal- Te form of the dose–response relation- ity of the tumour also requires consideration: for ship can vary widely, depending on the par- rapidly fatal tumours, the time of death provides ticular agent under study and the target organ. Since many chemicals require metabolic fcult to determine, methods such as the Poly-K activation before being converted to their reac- test that do not require such information can tive intermediates, both metabolic and toxicoki- also be used. When results are available on the netic aspects are important in determining the number and size of tumours seen in experimen- dose–response pattern. Te dose–response relationship Formal statistical methods have been devel- can also be afected by diferences in survival oped to incorporate historical control data into among the treatment groups. Tese methods assign an appropriate weight to (c) Statistical analyses historical and concurrent controls on the basis Factors considered include the adequacy of of the extent of between-study and within-study the information given for each treatment group: variability: less weight is given to historical con- (i) number of animals studied and number exam- trols when they show a high degree of variability, ined histologically, (ii) number of animals with a and greater weight when they show little varia- given tumour type and (iii) length of survival. It is generally not appropriate to discount Te statistical methods used should be clearly a tumour response that is signifcantly increased stated and should be the generally accepted tech- compared with concurrent controls by arguing niques refned for this purpose (Peto et al. For example, a mutation in a between-study variability and are, thus, of little gene that codes for an enzyme that metabolizes relevance to the current experiment. In analys- the agent under study could be discussed in the ing results for uncommon tumours, however, the subsections on toxicokinetics, mechanisms and analysis may be improved by considering histori- individual susceptibility if it also exists as an cal control data, particularly when between-study inherited polymorphism. Historical controls should be selected to resemble the concurrent controls as (a) Toxicokinetic data closely as possible with respect to species, gen- Toxicokinetics refers to the absorption, dis- der and strain, as well as other factors such as tribution, metabolism and elimination of agents basal diet and general laboratory environment, in humans, experimental animals and, where which may afect tumour-response rates in con- relevant, cellular systems. Studies experiments than for epidemiological studies that indicate the metabolic fate of the agent in due to diferences in animal strains, they can be humans and in experimental animals are sum- useful aids in interpreting animal data when the marized briefy, and comparisons of data from experimental protocols are sufciently similar. Mechanistic and other relevant between exposure and the dose that reaches the data target site may be important for the extrapola- tion of hazards between species and in clarifying Mechanistic and other relevant data may pro- the role of in-vitro fndings. Te nature of the mechanistic and other relevant data To provide focus, the Working Group depends on the biological activity of the agent attempts to identify the possible mechanisms by being considered. Relevant topics may include toxi- given to gaps in the data and to data that suggests cokinetics, mechanisms of carcinogenesis, sus- that more than one mechanism may be operat- ceptible individuals, populations and life-stages, ing. Te relevance of the mechanism to humans other relevant data and other adverse efects. Physiological changes refer to exposure- Genotoxicity data are discussed here to illus- related modifcations to the physiology and/or trate the key issues involved in the evaluation of response of cells, tissues and organs. Te adequacy of the reporting of cellular adhesion, changes in steroidal hormones sample characterization is considered and, when and changes in immune surveillance. Examples of func- chromatid exchange, micronucleus formation, tional changes include modifed activities of chromosomal aberrations and aneuploidy. Results changes in gap–junction-mediated intercellular from such tests may also give information on communication. Some end- points described are clearly genetic in nature Molecular changes refer to exposure-related (e. Other relevant data for such materials in selected tissues from animals treated in vivo may include characterization of cellular, tissue provide less weight, partly because they do not and physiological reactions to these materi- exclude the possibility of an efect in tissues other als and descriptions of pathological conditions than those examined. Moreover, negative results other than neoplasia with which they may be in short-term tests with genetic end-points can- associated.
Tere quinone and 11 purchase sildalis 120 mg line erectile dysfunction rates,12-dihydroxykavain-o-quinone discount 120mg sildalis visa erectile dysfunction treatment in india, was no signifcant increase in the incidence of two electrophilic metabolites, were identifed any neoplasm in females (Behl et al. Te glucuronic acid and sulfate conjugates of these two urinary metabolites were detected in 4. Mechanistic and Other a human volunteer who ingested a single dose of a dietary supplement containing kava extract Relevant Data (about 90 mg of kavalactones) (Johnson et al. Demethylation and methysticin, dihydromethysticin, yangonin, hydroxylation products were found in human desmethoxyyangonin, and dihydroyangonin). Te metab- intestinal tract, distributed to tissues, and olites were mainly excreted as conjugates (Köppel eliminated. In male F344 rats given kavain at a single Ten urinary metabolites were identifed when oral dose of 100 mg/kg bw, the maximum blood kavain was given as a therapeutic oral dose of concentration of kavain was measured at 0. Te struc- hours, afer which plasma concentrations declined tures of kavain and its metabolites are shown in with a mean terminal half-life of 1. Te major metabolite was a hydroxydi- mean oral bioavailability of kavain in F344 rats hydrokavain. Faecal excretion methysticin and dihydromethysticin (30–45 accounted for about 14% of the administered minutes). In addition, there In male F344 rats given an intravenous injec- were no diferences in the pharmacokinetics of tion of kavain at a dose of 7 mg/kg bw, kavain was kavain when administered as a single dose or as rapidly eliminated from the systemic circulation, repeated doses (Mathews et al. Systemic Oral absorption of kavain, dihydrokavain, clearance and volume of distribution were 89 mL/ methysticin, dihydromethysticin, yangonin, minutes per kg and 2. Kavain and dihydrokavain rapidly distributed out of the plasma into tissues were rapidly absorbed from the gastrointestinal and quickly cleared from the body (Mathews tract (with a peak at 10 minutes), followed by et al. Eight were deter- and 7,8-dihydrokavain; the compounds were mined structurally and two remained uniden- rapidly eliminated afer intraperitoneal admin- tifed. Both hydroxylated and ring-opened istration (100 mg/kg bw) of individual kava products were formed (Fig. Te maximum With methysticin, only small amounts of concentrations of kavain and 7,8-dihydroka- two metabolites (11,12-dihydroxykavain and vain were 64. Te maximum concentrations of demethylenation of the methylenedioxyphenyl desmethoxyyangonin and yangonin were 10. No kava extract was given intraperitoneally to male ring-opened products were detected (Fig. Kava extract (up to 10 000 µg/plate) was not With 7,8-dihydrokavain, large amounts of the mutagenic in Salmonella typhimurium strains parental compound were found in the urine. Te proposed metabolic pathways Kava extracts were not mutagenic in an assay in for 7,8-dihydrokavain are depicted in Fig. Severe to carcinogenesis liver failure has not been observed in people using kava in the traditional way in islands in Efects on hepatic cell physiology the South Pacifc (Moulds & Malani, 2003; Anke & Ramzan, 2004). A kava extract was tested for carcinogenicity in one study in mice and one study in rats treated by gavage. Summary of Data Reported cant increase in the incidence of hepatoblastoma in males, and of hepatocellular adenoma or 5. In male rats, the same extract Te kava (or kava kava) plant Piper caused a signifcant increase in the incidence of methysticum is a perennial tropical shrub that testis interstitial (Leydig) cell adenoma; however, is widely cultivated in Oceania. Te rhizome the incidence in controls was low compared with of the plant was originally used as an ingre- that in historical controls. Tere was no signif- dient in local traditional drinks with psychop- cant increase in the incidence of any neoplasm harmacological properties, and as traditional in female rats. More recently, rhizome extracts have been used in medicinal products, food or dietary supplements, and cosmetics.
Buffers and instru- should agree with one another to indi- ments can be further checked by com- cate that the sample is homogeneous buy 120mg sildalis with mastercard impotence depression. Some food (v) Indicating electrodes may be products may consist of a mixture of checked for proper operation by first using an acid buffer and then a base liquid and solid components that differ buffer purchase 120 mg sildalis fast delivery impotence at 70. The following Standardization control should be ad- are examples of preparation procedures justed so that the meter reads exactly for pH testing for each of these cat- 4. Electrodes should be rinsed with egories: water, then blotted and immersed in a (i) Liquid and solid component mix- pH 9. Adjust the tempera- meters this shorting is done by switch- ture of the aqueous layer to 25 °C and ing the instrument to standby, and in determine its pH. With the instrument shorted the sieve, blend to a uniform paste, ad- out, standardization control should be just the temperature of the paste to 25 turned from one extreme to another. This operation should produce a deflec- (c) Mix aliquots of solid and liquid tion greater than ±1. Adjust the tem- to 25 °C and determine the equilibrated perature of the blend to 25 °C and de- pH. Alter- tents of the container to a uniform natively, blend the entire contents of paste, adjust the temperature of the the container to a uniform paste, ad- paste to 25 °C, and determine the just the temperature of the paste to 25 equilibrated pH. Blend used in lieu of the potentiometric the solid in a blender to a paste con- method if the pH is 4. The colorimetric method add a small amount of distilled water for pH involves the use of indicator to some samples to facilitate the dyes in solutions that gradually change blending. An indi- water will not alter the pH of most cator that has the greatest color food products, but caution must be ex- change at approximately the pH of the ercised concerning poorly buffered sample being tested is selected. No more than 20 milliliters of is determined by the color of the indi- distilled water should be added to each cator when exposed to the sample 100 grams of product. Most indicator pared paste after adjusting the tem- solutions are prepared as a 0. In testing, a few drops of indicator of a semisolid consistency, such as pud- solution are added to 10-milliliter por- dings, potato salad, etc. Colors ed to a paste consistency, and the pH should be compared using a bright may be determined on the prepared background. If more fluidity is required, 10 to tions can be made on white porcelain 20 milliliters of distilled water may be spot plates, the test colors being com- added to 100 grams of product. Adjust pared thereon with a set of color stand- the temperature of the prepared paste ards. For spe- fitted with sets of tubes of standard in- cial product mixtures such as anti- dicator solutions of known pH. A paper tape maining product to a paste, and deter- treated with indicator dye is dipped mine the pH of the blended paste. Depending more fluidity is required, add 10 to 20 upon the pH of the solution, the tape milliliters of distilled water to each 100 will change color and an approximate grams of product and blend. Adjust the pH can be determined by comparison temperature of the prepared paste to 25 with a standard color chart. Adjust ability of this incorporation by ref- the temperature of the prepared paste erence is given in paragraph (a)(4)(ii) of to 25 °C and determine its pH.
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