Cell proliferation assessment

Humphreys, N.E., Dearman, R.J., and Kimber, I., Assessment of cumulative allergen-activated lymph node cell proliferation using flow cytometry, Toxicol Sci., 73, 80, 2003. 

Whysner J, Ross PM, Williams GM (1996) Phenobarbital mechanistic data and risk assessment enzyme induction, enhanced cell proliferation, and tumor promotion. Pharmacol Ther 71 153-191... 

An example of a TIE approach is that described by Desbrow et al. [7]. In this work, the endocrine disrupting activity detected in effluents of seven UK WWTPs by means of a yeast-based screening assay [52] was mainly attributed to the presence of estradiol, estrone, and ethynylestradiol. However, to assess the estrogenic activity different bioassays may be used, e.g., the yeast-based recombinant estrogen receptor-reporter assay (YES), the MCF-7 cell proliferation (E-screen), and the estrogen receptor-mediated chemically activated... 

Type IV hypersensitivity responses are elicited by T lymphocytes and are controlled by accessory cells and suppressor T cells. Macrophages are also involved in that they secrete several monokines, which results in proliferation and differentiation of T cells. Thus, there are numerous points along this intricate pathway in which drugs may modulate the final response. To achieve a Type IV response, an initial high-dose exposure or repeated lower-dose exposures are applied to the skin the antigen is carried from the skin by Langerhans cells and presented to cells in the thymus to initiate T-cell proliferation and sensitization. Once sensitized, a second challenge dose will elicit an inflammatory response. Thus, before sensitivity can be assessed, each of the models used to evaluate dermal hypersensitivity requires as a minimum ... 

Further evidence implicating 5-HT2b receptors in drug-associated VHD came in the years following our predictions. In 2003, we used primary cultures of human heart valve interstitial cells (hVICs) to assess whether fenfluramine and/or norfenfluramine induced cell proliferation - an in vitro approximation of the proliferative lesions found in the valves of VHD patients - in a 5-HT2b receptor-dependent manner [11], Treatment of primary hVIC cultures with either fenfluramine or norfenfluramine increased biochemical indices of cell proliferation, an effect that was blocked by cotreatment with a 5-HT2b receptor-selective antagonist [11]. 

Moved] Cranberry fruit of Early Black cultivar was fractionated chromatographically and fractions were analyzed for flavonoid content. The effects of the flavonoid fractions and ursolic acid, an abundant triterpenoid in cranberry peel, were assessed in two models of colon cancer and one model of breast cancer. Clonogenic soft agar assays were used to determine the effect of these compounds on tumor colony formation in HCT-116, HT-29 and MCF-7 cells. MTT and trypan blue assays were performed to assess their ability to inhibit tumor cell proliferation. TUNEL assays were performed to assess apop-totic response to the cranberry compounds. The proanthocyanidins inhibited tumor colony formation in HCT-116 and HT-29 cells in a dose-dependent manner, with greater effect on the HCT-116 cell line. Ursolic acid strongly inhibited tumor colony formation in both colon cell lines. These compounds also decreased proliferation in all three tumor cell lines with the HCT-116 cell line most strongly affected. (150 words)... 

Hormesis, in which compensatory adaptive changes precede and occur at lower doses than degenerative changes, was detected for half of the toxic drugs for cell proliferation, cell morphology and mitochondria [4, 33]. Hormesis could not be assessed for parameters that normally have low values, such as intracellular calcium measured by fluo4 or membrane permeability measured by toto-3, because assay methods were not sufficiently sensitive. However, for calcium, more sensitive dyes. 

Casanova. M., Conolly, R.B. Heck, H.d A. (1996) DNA-protein cross-links (DPX) and cell proliferation in B6C3F, mice but not Syrian golden hamsters exposed to dichloromethane phannacokinetics and risk assessment with DPX as dosimeter. Fundam. appl. Toxicol, 31, 103— 116... 

Many proliferation-associated antigens have been reported as clinically useful indicators of proliferative activity (1). Of these, the so-called proliferating cell nuclear antigen (PCNA) and Ki-67 have been identified as the most useful in both immunohistochemistry (see Chapter 27) and flow cytometry (FCM). PCNA is an auxiliary protein to DNA polymerase 8 (2,3) and is intimately associated with DNA replication, but also DNA repair (4,5). Ki-67 is a large protein associated with nuclear nonhistone proteins (6,7), and is expressed in all actively proliferating cells (8,9). Expression of these two proteins, in a cell population should equate to the growth fraction, i.e., the proportion of cells involved in an active cell cycle. However, there are apparent inconsistencies when these two proteins have been compared with one another (10) and with other methods of assessing cell proliferation (11). 

Because MIB-1 monoclonal antibody is used extensively to determine the cell proliferation index, its applications are discussed below. This antibody detects the nuclear antigen Ki-67 expressed in proliferating cells but not in resting cells. The antibody reacts with the nuclei of cells in mid-Gj (first gap), S (DNA synthesis), G2 (second gap), and M (mitosis) phases, but not in the G0 or quiescent phases. The use of MIB-1 antibody is one of the simplest and most reliable labeling techniques for assessing the rate of proliferation of a neoplastic cell population. Thus, the antibody can be used to assess the growth fraction (i.e., the number of cells in cell cycle) of normal, reactive, and neoplastic tissues. 

However, be aware that in spite of the usefulness of the MIB-1 antibody in assessing the rate of cell proliferation, the classification of cancers (e.g., breast cancer) by the size of the primary tumor and the presence and extent of lymph node metastases does not adequately explain differences in the clinical outcome of individual patients. Cell proliferation indices are commonly used, along with other diagnostic parameters, to estimate the risk of recurrence of a cancer for individual patients. Therefore, it is important to understand the relationship between various indices of proliferation such as MIB-1 labeling index and detection by either in situ hybridization or polymerase chain reaction. This approach will lead to quality assurance in diagnosis. 

Dong, H., Bertler, C., Schneider, E., and Ritter, M. A. 1997. Assessment of cell proliferation by AgNOR scores and Ki-67 labeling indices and a comparison with potential doubling times. Cytometry 28 280-288. 

Sallinen, P., Haapasalo, H., Kerttula, T., Rantala, L, Kalimo, H., Collan, Y., Isola, J., and Heikki, H. 1994. Sources of variation in the assessment of variation in the assessment of cell proliferation using proliferating cell nuclear antigen immunohistochemistry. Analy. Quant. Cytol. Histol. 76 261-268. 

Skin safety of niosomes was tested in a number of studies. As an example, the toxicity of polyoxyethylene alkyl ether vesicles containing Ci2-i8 alkyl chains and 3 and 7 oxyethylene units was assessed by measuring the effect on proliferation of cultured human keratinocytes [47]. It was found that the length of either polyoxyethylene headgroup or alkyl chain had only a minor influence on keratinocyte proliferation. However, the ether surfactants were much more toxic than esters tested in this study. The concentrations of ether surfactants required to inhibit cell proliferation by 50% were 10-fold lower than for ester surfactants. Neither the HLB nor the critical micelle concentration values or cholesterol content affected keratinocyte proliferation. 

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