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71.
Several strains of photoautotrophically grown Spirulina spp. contained poly-beta-hydroxybutyrate (PHB) at concentrations never exceeding a few milligrams per gram of dry weight. Under mixotrophic growth conditions in the presence of acetate, PHB reached values greater than 2.5% of dry weight. With pyruvate, no significant effect on PHB accumulation was obtained. 相似文献
72.
The production of a proteinase from Lactobacillus helveticus CRL 581 was studied. The highest specific activity was found at the early exponential growth phase of cells cultured in milk.
The lowest levels of proteinase were detected in MRS broth, while in the casein–yeast extract–glucose broth enzyme production
increased gradually during the fermentation and reached maximal values at the stationary phase. The proteinase, found to be
associated with the cell membrane fraction, hydrolyzed β-casein more rapidly than α-casein. The enzyme was not released from
washed cells in the presence or absence of calcium, which suggests that the enzyme did not undergo self-digestion.
Received: 28 January 1997 / Accepted: 8 March 1997 相似文献
73.
A Neuro-Comparative Study between Single/Successive Thorium Dose Intoxication and Alginate Treatment
Mohamed M. Rezk 《Biological trace element research》2018,185(2):414-423
The adult male albino rats were grouped into five groups (control group and four variably treated groups with thorium (Th) in single or successive with or without alginate treatment). The IP administration of thorium nitrate (13.6 mg/kg b.wt.) induced a regional distribution and accumulation ordered as cerebellum > cerebral cortex > brain stem > hippocampus > hypothalamus > striatum. Also, it induces a significant increase in Na+, Ca2+, and Fe3+ ion content and malondialdehyde (MDA) level while K+ ions and glutathione (GSH) level were significantly decreased. On the other hand, the daily oral administration of 5% alginate showed a significant decreasing in the accumulation of thorium in the different brain areas and mitigated its hazardous effects. By the alginate treatment, Na+, Ca2+, Fe3+, and level of MDA were declined while K+ ions and GSH level showed a significant increase. The improvement of the investigated parameters was attributed to the specific chelating, regeneration, and antioxidant properties of the alginate. So, alginate administration could ameliorate the hazardous effects of thorium nitrate. 相似文献
74.
75.
Herein, we report the results of irreversible inhibition of guinea pig liver transglutaminase (TGase) by a series of 24 novel dipeptides containing either an alpha,beta-unsaturated amide or an epoxide functional group. Their inactivation rate constants were measured using a direct continuous spectrophotometric method and were found to vary between 421 x 10(3) and 3000 x 10(3)M(-1)min(-1). 相似文献
76.
Predictivity of an in vitro model for acute and chronic skin irritation (SkinEthic) applied to the testing of topical vehicles 总被引:2,自引:0,他引:2
A. de Brugerolle de Fraissinette V. Picarles S. Chibout M. Kolopp J. Medina P. Burtin M.E. Ebelin S. Osborne F. K. Mayer A. Spake M. Rosdy B. De Wever R.A. Ettlin A. Cordier 《Cell biology and toxicology》1999,15(2):121-135
An in vitro human reconstructed epidermis model (SkinEthic) used for screening acute and chronic skin irritation potential
was validated against in vivo data from skin tolerability studies. The irritation potential of sodium lauryl sulfate (SLS),
calcipotriol and trans-retinoic acid was investigated. The in vitro epidermis-like model consists of cultures of keratinocytes
from human foreskin on a polycarbonate filter. The modulation of cell viability, the release and gene expression of proinflammatory
cytokines, interleukins 1α and 8, and morphological changes were evaluated during 3 days as endpoints representative for an
inflammatory reaction. The cumulative irritation potential of the topical products was evaluated in a human clinical study
by visual scoring and biophysical measurement of inflammatory skin reaction after repeated 24 h applications over 3 weeks
under Finn chamber patches. All topical products that were nonirritating in the human study were noncytotoxic and did not
induce cytokine expression in the in vitro acute model (day 1 exposure). All irritating controls exhibited specific cell viability
and cytokine patterns, which were predictive of the in vivo human data. The ranking of mild to moderate skin irritation potential
was based on the lack of cytotoxicity and the presence of cytokine patterns including gene expression specific for each irritant,
using the chronic in vitro model (up to 3 days exposure).
The human reconstructed epidermis model SkinEthic was shown to be a reliable preclinical tool predicting the irritation potential
of topical products. Moreover, it is a useful model in a two-step tiered strategy for screening acute and chronic irritation
potential for the selection of vehicles for new topical drugs.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
77.
78.
Xiuqing Wang Daphne Moutsoglou 《In vitro cellular & developmental biology. Animal》2009,45(10):584-591
Primary fibroblast-like cells isolated from the peripheral blood of a healthy pig were immortalized by transduction of cells
with a replication-defective retrovirus vector expressing the E6/E7 proteins of human papillomavirus type 16 (pLXSN-16E6E7).
The immortalized cells grow rapidly in cell culture and exhibit a distinct cell surface phenotype that was positive for CD90,
CD44, collagen I, and vimentin and negative for CD14 and MHC II. Additionally, these immortalized blood derived-fibroblast-like
cells had the potential to differentiate into osteoblasts and adipocytes in vitro as evidenced by the deposition of calcium,
increased alkaline phosphatase activity, upregulated osteogenic and adipogenic marker gene expression, and accumulation of
fat droplets in cells when osteogenic (dexamethasone, ascorbic acid, and β-glycerophosphate) or adipogenic supplements (dexamethasone,
3-isobutyl-1-methylxanthine, indomethacin, and insulin) were added to the culture. Overall, the results suggest that the immortalized
blood-derived fibroblast-like cells exhibit some of the features of mesenchymal precursor cells, which may have implications
in tissue repair and remodeling process. 相似文献
79.
Roberta L. Millstein 《Journal of the history of biology》2008,41(2):339-367
Biologists and philosophers have been extremely pessimistic about the possibility of demonstrating random drift in nature,
particularly when it comes to distinguishing random drift from natural selection. However, examination of a historical case
– Maxime Lamotte’s study of natural populations of the land snail, Cepaea nemoralis in the 1950s – shows that while some pessimism is warranted, it has been overstated. Indeed, by describing a unique signature
for drift and showing that this signature obtained in the populations under study, Lamotte was able to make a good case for
a significant role for␣drift. It may be difficult to disentangle the causes of drift and selection acting in a population,
but it is not (always) impossible. 相似文献
80.