Hamster performance

Vaccine candidates are based on the two viral surface proteins, gD and gB (80). Recombinant methods are used to express the proteins, either in Chinese hamster ovary (CHO) cells or in baculovims. The proteins are purified as subunits and formulated with different adjuvants. Clinical trials with these vaccine candidates have been performed, but the results to date have not been encouraging. 

Since our backbone 2 aPNA incorporates six Lys residues in its peptide sequence and is cationic at a physiological pH, we were optimistic that this aPNA would be taken up into cells without the need for any external carrier system. To answer the simple question of whether b2 aPNAs are intemahzed, a standard fluorescence microscopy experiment was performed to see if whole cells that were incubated with a fluorescent-labeled aPNA would internahze labeled material [70]. Chinese Hamster Ovary (CHO) cells in culture were incubated with BODIPY-la-beled TCCCT(b2) at 37 °C for various periods of time. Following incubation, the cells were rinsed in phosphate-buffered sahne (PBS), fixed with 4% formaldehyde at ambient temperature for 20 min, then washed with PBS and stored in a refrigerator until examined by fluorescence microscopy. 

Additional studies were performed with eukaryotic cell systems (i.e. Chinese hamster ovary cells, rat bone mar-... 

Chinese Hamster CHO/Hgprt System. Chinese hamster ovary (CHO) cells have 21 or 22 chromosomes with one intact X chromosome and a large acrocentric marker chromosome (Natarajan and Obe, 1982). The use of these cells in mammalian mutation experiments was first reported by Hsie et al. (1975), and was refined into a quantitative assay for mutagenicity testing by O Neill. The performance of this system has been reviewed by the USA EPA Gene-Tox Program. The experimental procedure for this assay is similar to the V79/Hgprt system already described, and for more detailed descriptions the reader is referred to Li et al. (1987). 

Hagman and Sivertsson discussed the work performed at Pharmacia and Upjohn52 on monitoring and controlling bioprocesses. They followed the protein production-derived form Chinese hamster cells (CHO-cells) in a 500-1 reactor over a 3-month period. The diagrams of the flow cell and pumping/NIR system are displayed, and the logic behind the work outlined. External and on-line calibrations were performed. 

Some new materials perspective for advanced biomedical technologies, especially carbon nanoparticles like fullerenes, are potentially mutagenic, carcinogenic and immunogenic [16,65], Therefore, standard tests of the morphological transformation of Syrian hamster embryonic cells in cultures on these materials (described in detail by [68,69]) can be performed. Immune activation of bone and vascular cells on the materials can be estimated by increased concentration of immunoglobulin and selectin adhesion molecules (ICAM-1, VCAM-1, ELAM-1), which bind cells of the immune system [15,16,18,19,23], as well as by the production of cytokines, such as tumor necrosis factor alpha or interleukins beta [55],... 

Males also depend on testosterone for olfactory performance. If in hamsters testosterone is converted to estrogen by subcutaneous silastic implants of the aromatase inhibitor l,4,6-androstatriene-3,17-dione, their sexual sniffing decreases. They sniff less toward novel females and no longer discriminate between males and females (Steel and Hutchinson, 1987). Castration affects odor detection performance in male rats (Doty and Ferguson-Segall 1989). 

The most comprehensive attempt to assess interspecies differences in susceptibility to toxic responses, based on two different dose correction approaches (body weight versus body surface area), was pubhshed in the classic paper by Freireich et al. (1966, as reviewed in Davidson et al. 1986, Calabrese et al. 1992, Grbnlund 1992). The authors attempted to standardize various toxicological studies for 18 anticancer dmgs performed in adult mice, rats, hamsters, dogs, monkeys, and humans. The findings of this study led to the conclusion that the toxic effects of an agent were similar across species when the dose was measured on the basis of the body surface area. 

We performed a systematic molecular and behavioural screen to identify locomotor factors secreted by the SCN. To find secreted factors not previously documented in the SCN, we screened a hamster SCN cDNA library in a yeast secretiomtrap system (Klein et al 1996). We then carried out a behavioural screen in which newly identified and previously documented (Earnest et al 1999, Miller et al 1996, Ma et al 1992) SCN factors were tested for an effect on circadian locomotor activity by constant infusion into the 3rd ventricle of hamsters for 2 to 3 weeks (Kramer et al 2001). In general, constant infusion of a SCN locomotor factor should alter locomotor activity reversibly without affecting the underlying SCN circadian clock. A locomotor inhibitory factor, for example, should block locomotor activity for the duration of the infusion. Because the SCN clock should not be affected, the circadian rhythm of locomotor activity should reappear with its expected phase and period upon cessation of the infusion, fn contrast, constant infusion of SCN factors involved only in outputs other than locomotor activity should have no effect on locomotor behaviour. 

Few split-dose experiments have been performed with chemicals. Popescu et aL (1984) observed that with split doses of carcinogen separated by 2 to 24 hours only N-acetoxy-2-fluorenylacetamide enhanced transformation of Syrian hamster embryo ceUs while doses of N-methyl-N -nitro-N-nitrosoguanidine, mitomycin C or ultraviolet light were less effective than single doses, and no effect of dose fractionation was observed with methyl methanesulfonate. 

Diepoxybutane also reacts with nucleosides, nucleotides and DNA. Adducts at N of adenine were identified in incubations (pH 7) containing deoxyadenosine, deoxyadenosine monophosphate or poly(dA-dT)(dA-dT), as determined by mass spectrometry, or calf tliymus DNA as determined by a high-performance liquid chromatography/ 32P-postlabelling method (Leuratti et al., 1994). By the latter method, the authors demonstrated adduct formation to N of adenine in DNA from Chinese hamster ovary cells incubated with diepoxybutane at 37°C. 

This chapter provides a synopsis of the salient host tissue responses that relate to implanted sensor performance and describes in detail the development and current adaptation of the window chamber-biosensor method to address host tissue factors. The use of normoglycemic and diabetic animal models, specifically the Syrian hamster and Fat Sand Rat, to study the role of the microvasculature on sensor function is described. Limitations of the window chamber-biosensor method are also outlined. Finally, some important and useful features of standard brightfield, fluorescence, confocal, and multiphoton imaging as they apply to the window chamber are noted. 

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