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Biomedical subjects

M R Davey

Publications and source records attributed to M R Davey.

At least 37 records · Page 2Linked to original sources
PubMed1999

Haemoglobin (Erythrogen)-enhanced post-thaw growth of cryopreserved cells.

Supplementation of semi-solid R2 culture medium with a commercial bovine haemoglobin (Hb) solution (Erythrogen) at 1:50-1:500 (v:v), had beneficial effects on the growth, following cryopreservation, of cells of the Indica rice, Oryza sativa cv. Pusa Basmati 1. The mean absorbance, as assessed by triphenyl tetrazolium chloride reduction, of rice cells at 8 d post-thawing, was increased by up to 60% (P < 0.05), compared to cells recovered in the absence of Hb. Erythrogen (1:50-1:500 v:v) promoted an increase in biomass, of up to 25% over control (P < 0.05), at 24 d post-thawing. Cell suspensions, re-established by transfer to liquid medium of cells initially thawed and cultured with Erythrogen for 24 d, exhibited increased (up to 2-fold) growth rates over a subsequent 20-d period, compared to cells recovered without Hb.

Cells, Cultured↗
PubMed1999

Culture of cells at perfluorocarbon-aqueous interfaces.

Protoplasts (wall-less cells) isolated enzymatically from leaf tissues of Manihot esculenta, Passiflora edulis and Petunia parodii, and from cell suspensions of Oryza sativa, Passiflora giberti, Petunia hybrida and Salpiglossis sinuata, were cultured for up to 35 d at an interface between the inert, oxygen-gassed perfluorocarbon (PFC) liquid, perfluorodecalin, overlaid with liquid or semi-solidified aqueous media. The maximum increase in mitotic division, as assessed by initial plating efficiency (IPE) occurred with protoplasts of O. sativa, which showed a 4-fold increase above the control over 35 d. Similar, but less pronounced increases in IPE of 90-103% occurred with S. sinuata, P. giberti and P. parodii following culture with oxygenated PFC. The least responsive species was M. esculenta, where the mean IPE after 25 d was increased by 33% over control. For those totipotent protoplast systems (e.g. P. edulis, P. giberti, O. sativa and P. parodii) phenotypically normal plants were regenerated following initial culture with oxygenated PFC. The advantages of such an interface system include (1) ease of sterilisation of the PFC by autoclaving, (2) the recycleability and, hence, recovery of the PFC, thereby offsetting the high initial costs, and (3) the ability to aspirate cells at the interface.

Cell Culture Techniques↗
PubMed1998

Perfluorochemicals: their applications and benefits to cell culture.

The properties of perfluorochemical liquids, particularly their high gas solubility, enables them to be exploited in cell biotechnology. They can facilitate respiratory-gas delivery to prokaryotic and eukaryotic cells in culture; in some systems, they can stimulate production of biomass, yields of commercially important cellular products and, for plant systems, expression of totipotency. The recoverability, and hence recycleability, of perfluorochemicals from aqueous systems makes their routine use a commercially feasible option. This article reviews the applications and beneficial effects of perfluorochemicals in cultured microbial, animal and plant cells, including both aerobic and anaerobic systems.

Animals↗
PubMed1998

Enhanced mitosis in cultured protoplasts: beneficial effects of oxygenated perfluorocarbon and haemoglobin.

Cell suspension-derived protoplasts of Petunia hybrida cv. Comanche were cultured for up to 10 d in (1) aqueous medium, (2) aqueous medium overlaying an oxygenated (10 mbar, 15 min) perfluorochemical liquid (perfluorodecalin; PFC), (3) aqueous medium containing 1:50 (v:v) of the commercial haemoglobin (Hb) solution (Erythrogen), (4) aqueous medium supplemented with 1:50 (v:v) of Erythrogen overlaying oxygenated PFC. Treatments 2, 3, and 4 enhanced mean mitotic division by 111%, 80% and 139% respectively, compared to controls. Both fresh-Hb and stored-Hb significantly (P < 0.05) enhanced mitotic division, although this was 45% greater with fresh-Hb compared to stored-Hb. Both oxygenated PFC and Erythrogen provide approaches for enhancing cellular oxygen supply to eukaryotic cells. Commercially, the recoverability and recycleability of PFCs make these compounds a more attractive option in comparison to Erythrogen, despite a high initial investment cost.

Animals↗
PubMed1998

Enhanced post-thaw viability of cryopreserved cells by oxygenated perfluorocarbon or Pluronic F-68.

Viability and growth following cryopreservation have been examined following (i) culture of Oryza sativa cv. Taipei 309 (Japonica rice) in medium overlaying oxygenated perfluorocarbon (PFC) liquid (Flutec PP6), and (ii) culture of two cvs. of Japonica rice (Taipei 309, Tarom), and Lolium multiflorum in media with Pluronic F-68 (0.01-0.2% w/v). The mean viability of cv. Taipei 309 rice cells following 4 days in medium overlaying oxygenated Flutec (0.45 +/- 0.07; n = 20) was significantly (P < 0.05) greater than control (0.35 +/- 0.08). Cell viability of cv. Tarom was increased by 400% (P < 0.001) with 0.1% (w/v) Pluronic F-68 in the recovery medium. Mean cell viability was also elevated 3-fold (P < 0.001) and 2-fold (P < 0.05) with 0.2% (w/v) and 0.01% (w/v) Pluronic, respectively. A 2-fold increase (P < 0.001) in viability occurred for Taipei 309 cells exposed to 0.01% (w/v) Pluronic F-68; that of Lolium cells was increased by 31% (P < 0.01) under similar conditions. Pluronic F-68 (0.01% w/v) also stimulated biomass, by 29-32%, in both cvs. Taipei 309 and Lolium at 30 days post-thawing.

Biomass↗
PubMed1997

Detection of single-copy genes in DNA from transgenic plants by nonradioactive Southern blot analysis.

Improvements to the sensitivity, speed, and reproducibility of digoxigenin (DIG)-labeled probes and chemiluminescent substrates makes these compounds increasingly popular to detect nucleic acids. High sensitivity and low background are essential in Southern blot analysis, particularly with plant DNA. This article describes a nonradioactive system to detect single-copy genes in transgenic plants. Labeling using the polymerase chain reaction (PCR) was employed to produce highly sensitive and reusable DIG-labeled probes. The background was reduced by immobilizing the DNA onto nylon filters by alkaline transfer and by minimized gel handling; the signal-to-noise ratio was improved by modification of the detection procedure.

Blotting, Southern↗
PubMed1997

Pharmacological activity of feverfew (Tanacetum parthenium (L.) Schultz-Bip.): assessment by inhibition of human polymorphonuclear leukocyte chemiluminescence in-vitro.

The bioactivity of feverfew (Tanacetum parthenium) leaf extracts has been analysed, by use of a human polymorphonuclear leukocyte (PMNL) bioassay, to assess the relative contributions of solvent extraction and parthenolide content to the biological potency of the extract. Extracts prepared in acetone-ethanol (system 1) contained significantly more parthenolide (mean +/- s.d. 1.3 +/- 0.2% dry leaf weight) than extracts in chloroform-PBS (phosphate-buffered saline; system 2; 0.1 +/- 0.04% dry leaf weight) or PBS alone (system 3; 0.5 +/- 0.1% dry leaf weight). Extract bioactivity, measured as inhibition of phorbol 12-myristate 13-acetate-induced, 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol)-enhanced PMNL, chemiluminescence, followed a similar trend. Extracts inhibited phorbol 12-myristate 13-acetate-induced oxidative burst by amounts which, if solely attributable to parthenolide, indicated parthenolide concentrations for the respective solvent systems of 2.2 +/- 0.6%, 0.2 +/- 0.1% and 0.9 +/- 0.1% dry leaf weight. The mean ratio of parthenolide concentration to the parthenolide equivalent/PMNL-bioactivity value, for acetone-ethanol and PBS extracts were both 1:1.7. Parthenolide, although a key determinant of biological activity for T. parthenium leaf extracts based on the PMNL-bioassay, seems not to be the sole pharmacologically-active constituent. The identical and elevated bioactivity-parthenolide ratios for both organic and aqueons-phase leaf extracts suggest that a proportion of the other bioactive compounds have solubilities similar to that of parthenolide.

Chromatography, High Pressure Liquid↗
PubMed1997

Haemoglobin-enhanced mitotic division in cultured protoplasts.

Protoplasts from cell suspensions of albino Petunia hybrida cv. Comanche were cultured for 9 days in nutrient medium containing Erythrogen, a purified bovine haemoglobin solution (supplied at 10% w/v) at 1:50-1:500 (v/v). In some assessments, the non-ionic surfactant Pluronic F-68 (Poloxamer 188), was also added to the culture medium at 0.01-1.0% (w/v). Erythrogen at 1:50 (v/v) increased the mean initial protoplast plating efficiency (IPE; 18.5 +/- 0.8%, n = 5 throughout) by 64% (P < 0.001) above that of controls (11.3 +/- 0.4%). Supplementation of medium with 1:50 (v:v) Erythrogen and 0.01% (w/v) Pluronic F-68, increased the mean IPE (24.4 +/- 1.4%) by 92% (P < 0.001) over control (12.7 +/- 1.1%). Similar results were obtained for mesophyll protoplasts of Passiflora suberosa, with 1:50 and 1:100 (v/v) Erythrogen increasing the mean IPEs to 87% and 93% respectively, over controls. This beneficial and synergistic effect of Erythrogen with Pluronic F-68, on mitotic division of cultured Petunia and Passiflora protoplasts, should also facilitate the culture of isolated protoplasts and cells of other, agronomically-important, species.

Animals↗
PubMed1997

Changes in cell biochemistry in response to culture of protoplasts with oxygenated perfluorocarbon.

Superoxide dismutase (superoxide oxidoreductase; EC 1.15.1.1; SOD) was measured in enzymatically isolated protoplasts of Salpiglossis sinuata following culture in aqueous nutrient medium overlaying oxygen-gassed perfluorodecalin (Flutec PP6; BNFL Fluorochemicals, UK). SOD was extracted from harvested, lysed protoplast-derived cells after 1, 3, 7 and 14 days of culture and assayed spectrophotometrically. Protoplasts cultured with oxygenated PFC (+/- s.e.m, n = 5) showed significant increases in mean SOD activity to 4.2 +/- 0.1 U after 1 day (P < 0.05) and 9.3 +/- 0.7 U after 3 days (P < 0.01), with a fall in mean SOD after 7 days (5.1 +/- 0.9 U), similar to control. The decrease in SOD after 7 days correlated closely with a progressive fall in pO2 in the PFC phase over the same period. In contrast, control protoplasts (medium alone) or protoplasts cultured in medium overlaying non-oxygenated PFC showed no significant changes in mean SOD activity over the 14-day culture assessment period.

Cells, Cultured↗
PubMed1997

Perfluorochemicals and cell biotechnology.

Perfluorochemical (PFC) liquids have properties, especially high gas solubility, which make these compounds useful in medicine and biotechnology. PFCs are being employed to facilitate respiratory gas supply to both prokaryotic and eukaryotic cells and, in some systems, to improve biomass production and yields of commercially-important cellular products. Animal (including human) and plant cells have also been cultured at the interface between PFC liquids and aqueous culture medium, while fluorocarbon polymers have been employed as gaspermeable membranes in eukaryotic cell cultures. This paper presents an overview of the applications and beneficial effects of PFCs in microbial, animal and plant culture systems. PFCs have been compared with other physical and chemical options for manipulating respiratory gas supply to cultured cells. PFC-facilitated improvements in cell culture technology will have increasingly important biotechnological implications.

Animals↗
PubMed1997

Beneficial effects of oxygenated fluorocarbon on the in vitro culture of protoplasts and cell electrofusion products.

Electrofused Passiflora protoplasts (P. edulis, P. giberti) were plated in KPR medium overlaying oxygen-gassed perfluorodecalin (Flutec PP6). Oxygenated PFC significantly (P < 0.05) enhanced protoplast division, as reflected by an increase in mean plating efficiency of up to 62% (P < 0.05) over 14 days. After 21 days of culture, the liquid phase containing dividing protoplast-derived cells, was removed from the PFC surface and overlaid onto MS-based agar medium for callus proliferation. Forty days later, protoplast-derived calli were transferred to one of two regeneration protocols, previously determined using unfused parental protoplasts. Calli derived from electrofusion-treated protoplasts exhibited organogenesis or somatic embryogenesis, depending on the regeneration procedure. The regeneration efficiency after 121 days for protoplasts initially cultured with oxygenated PFC was over 2-fold greater (P < 0.01) than control. These results indicate that oxygenated PFC can enhance growth and regeneration of protoplasts and their fusion products.

Cell Fusion↗
PubMed1996

Preservation of viable biological samples for experiments in space laboratories.

Standard viable preservation methods for biological samples using low temperatures have been investigated concerning their storage capabilities under higher temperature levels than usual. For a representative set of organism classes (plants, mammalian cells, arthropods and aquatic invertebrates), the minimum appropriate storage conditions have been identified by screening storage temperatures at -196 degrees, -80 degrees, -20 degrees, +4 degrees, +20 degrees/25 degrees C for periods from 2 days to 4 weeks. For storage below 0 degree C, as a typical cryopreservative, dimethylsulfoxide (DMSO) was used. For some samples, the addition of trehalose (as cryopreservative) and the use of a nitrogen atmosphere were investigated. After storage, the material was tested for vitality. The findings demonstrated that acceptable preservation can be achieved under higher storage temperatures than are typically applied. Small, dense cultured plant cells survive for 21 d when moderately cooled (+4 degrees to -20 degrees C); addition of trehalose enhances viability at -20 degrees C. For mammalian cells, the results show that human lymphocytes can be preserved for 3 d at 25 degrees C, 7 d at 4 degrees C and 28 d at -80 degrees C. Friend leukaemia virus transformed cells can be stored for 3 d at 25 degrees C, 14 d at 4 degrees C and 28 d at -80 degrees C. Hybridoma cells can be kept 7 d at 4 degrees C and 28 d at -20 degrees C or -80 degrees C. Model arthropod systems are well preserved for 2 weeks if maintained at lower temperatures that vary depending on the species and/or stage of development; e.g., 12 degrees C for Drosophila imagoes and 4-6 degrees C for Artemia nauplii. For aquatic invertebrates such as sea urchins, embryonic and larval stages can be preserved for several weeks at +6 degrees C, whereas sperm and eggs can best be stored at + 4 degrees C for up to 5 d at maximum. These results enhance the range of feasible space experiments with biological systems. Moreover, for typical terrestrial preservation methods, considerable modification potential is identified.

Animals↗