Cell Assays

Culture-cell assays are also subject to sample retention by the monolayer. Sawada et al. [574] studied the transport of chlorpromazine across MDCK cell... 

Cultured-cell assays also are subject to sample retention by the monolayer. Wils et al. [24] reported retentions as high as 44%, whereas Sawada et al. [25-27] cited values as high as 89%. This is undoubtedly a common phenomenon with research compounds, which are often highly lipophilic, yet the effect seems to be ignored in most reported studies. 

Oldfield s work confirmed the complete pathway and identified all the intermediates via an exhaustive experimental scheme, which included whole cell assays, cell-free extracts of IGTS8 as well as extracts from clones containing individual genes expressed in Escherichia coli. The need for NADH was clearly demonstrated in cell-free assays by amendment of NADH. The experimental evidence for involvement of FMN in the pathway was demonstrated [53,66,67],... 

The specificity of several of the enzymes identified in the 4S pathway of different organisms has been studied. In case of the DBT desulfurizing enzymes, little difference is expected in the specificity of the enzymes, say DszA, from different Rhodococcus strains found to date. This is essentially because the DNA sequence for the enzymes investigated so far has been the same. The difference in the specificity observed with whole cell assays is essentially due to the differences in substrate intake via the cell membrane and not necessarily due to a difference in the intrinsic enzyme specificity. It has been found that while isolated enzyme DszC (from KA2-5-1) can desulfurize up to 4,6 dipropyl DBT, whole cells cannot, indicating substrate transport as limiting factor. 

Analog ent-(+)-8 is 20-fold more potent than racemic acifran and is threefold more potent than niacin in the cAMP whole-cell assay [55]. The selectivity was also improved with respect to acifran with 10-fold selectivity for GPR109A over GPR109B. The importance of the absolute configuration of ent-(+)-8, which is tentatively assigned S, is demonstrated by the 70-fold better cAMP whole-cell activity of the eutomer compared to that of the distomer. 

Temple, L. et al., Comparison of ELISA and plaque-forming cell assays for measuring the humoral immune response to SRBC in rats and mice treated with benzo[a]pyrene or cyclophosphamide, Fundam. Appl. Toxicol., 21, 412, 1993. 

In rodents, sheep red blood cells (SRBC) are routinely used for immunization. The antibody response is determined using the plaque forming cells assay (PFC) or by plasma SRBC-specific antibody titer [21, 22], As an alternative to SRBC, other T-cell-dependent antigen may be used, including keyhole limpet hemocyanin (KLH), tetanus toxoid (TT), or pneumococcal antigen. 

Wilson, S.D., Munson, A.E. and Meade, B.J., Assessment of the functional integrity of the humoral immune response the plaque-forming cell assay and the enzyme-linked immunosorbent assay, Methods, 19, 3, 1999. 

Humoral immunity Plaque forming cell assay Rosette formation, AMP poreforming activity... 

Genotoxic Effects. No studies were located regarding the genotoxic effects of hexachloroethane in humans after inhalation, oral, or dermal exposure. In vitro studies of hexachloroethane using microbial, fungal, and rodent cell assays are summarized in Table 2-4. Tests of prokaryotic cell systems failed to detect gene mutation (Haworth et al. 1983 Roldan-Arjona et al. 1991 Simmon and Kauhanen 1978 ... 

The principal tests can be broadly categorized into microbial and mammalian cell assays. In both cases the tests are carried out in the presence and absence of in vitro metabolic activation enzymes, usually derived from rodent liver. 

---