Lethal Effects of Helianthemum lippii (L.) on Acanthamoeba castellanii Cysts in Vitro

Acanthamoeba spp. commonly cause Acanthamoeba keratitis which is typically associated with the wear of contact lenses. Therefore, finding an economic, efficient, and safe therapy of natural origin is of outmost importance. This study examined the in vitro lethal potential of ethyl acetate and methanol extracts of Helianthemum lippii (L.) (sun roses) against Acanthamoeba castellanii cysts isolated from patients with amoebic keratitis. Both extracts proved to be potent as regard to their lethal effects on A. castellanii cysts with comparable results to chlorhexidine. The ethyl acetate was more promising with cumulative lethality. It showed a highly significant lethal percentage along the duration of treatment. The analysis of the more potent ethyl acetate extract revealed the presence of 2.96 mg/100 g of total phenolics, 0.289 mg/100 ml of total flavonoids and 37 mg/100 mg of total tannins which highlighted their phytomedicinal role.     

Effects of inhibition of ornithine aminotransferase on thioacetamide-induced hepatogenic encephalopathy

Repeated administration of thioacetamide (TAA) to CD1 mice produced hepatic failure and biochemical and behavioral effects characteristic of hepatogenic encephalopathy (HE). The symptoms in mice resembled those previously observed in rats after similar treatments. It is, howeve, obvious that both in rats and mice the severity of symptoms depends not only on dose and dosing schedule of TAA, but also on strain and body weight (age). Administration of 5-fluoromethylornithine (5FMOrn), a selective inactivator of ornithine aminotransferase (OAT), significantly reduced mortality, and it ameliorated most of the TAA-induced pathologic symptoms, such as hypothermia, decreased locomotor and exploratory behavior, pathologic liver function and amino acid patterns. The most prominent biochemical consequence of 5FMOrn administration is the elevation of ornithine concentrations in tissues, including the brain, and in body fluids. Elevated ornithine concentrations are, therefore, the most likely basis for the therapeutic effects of 5FMOrn. In agreement with this notion is the enhancement of citrulline and urea formation. These findings and the observation that administration of ornithine in combination with a branched-chain 2-oxoacid ameliorated the pathologic symptoms of portal-systemic encephalopathy suggest inhibition of OAT in the treatment of this disease. The liver protective effect of 5FMOrn is not yet understood; the enhancement of regenerative processes is a likely explanation.Abbreviations GABA 4-aminobutyrate - GABA-T 4-aminobutyrate aminotransferase - GOT plasma glutamate oxaloacetate transaminase - HE hepatogenic encephalopathy - LDH plasma lactate dehydrogenase - MAO monoamine oxidase - OAT ornithine aminotransferase - TAA thioacetamide - 5FMOrn 5-fluoromethylornithine Special issue dedicated to Dr. Claude Baxter.     

Oxidative Damages and Repair in Euglena gracilis Exposed to Ozone II. Membrane Permeability and Uptake of Metabolites

Significant injuries to the plasma membrane were detected inEuglena gracilis cells during ozone exposure (240 µ1.liter¹,delivery rate of l µmol.min^–1), as assessed by measuringthe alterations of vitamin B₁₂ and acetate uptakes and the leakageof intracellular K⁺ (Rb⁺). A rapid decrease in the uptake ofvitamin B₁₂ and acetate was observed within 15 min of treatment,indicating that both transport systems are very sensitive toO₃. On the other hand, the leakage of intracellular K⁺ ions,as measured by the efflux of ⁸⁶Rb⁺ from prelabelled cells, couldonly be detected after 30 min of O₃ exposure. These resultssuggest that the initial metabolic symptoms of injury is atthe level of the two transport systems examined and that thealteration of the membrane permeability to K⁺ ions appears asa second step in the cascade of oxidative events at the plasmamembrane level. When Euglena cells were allowed to recover underautotrophic growth conditions following O₃ treatment, vitaminB₁₂ and ⁸⁶Rb⁺ (K⁺) ions uptakes returned gradually to controllevel within 5 h of the recovery period. Acetate uptake returnedto control level at a slower rate and needed 20 h for completerecovery. These results indicate that the cells were able toactively repair most of the initial oxidative damages inducedby O₃. The metabolic significance of the repair mechanism(s)is discussed. (Received December 25, 1989; Accepted July 23, 1990)     

The wheat wcs120 gene family. A useful model to understand the molecular genetics of freezing tolerance in cereals

Winter, as compared with spring cereals, possess better acclimation mechanisms that allow them to overwinter and survive freezing temperatures. This difference is genetically programmed and involves a complex genetic system. To understand the nature of this system and its regulation by low temperature, genes associated with freezing tolerance in wheat ( Triticum aestivum L.) were identified and characterized. Among these, the wcs120 gene family encodes a group of proteins ranging in size from 12 to 200 kDa. As shown by biochemical, immunohistochemical, molecular and genetic analyses, this gene family is specific to the Poaceae, highly abundant and coordinately regulated by low temperature. Furthermore, accumulation of WCS protein is directly correlated with the development of freezing tolerance. These analyses also revealed a regulatory control of the vernalization process over low temperature gene expression in winter cereals. Recent studies suggest that the molecular mechanisms controlling the expression of these genes involve negative regulatory factors that are modulated by phosphorylation.     

Chromosome mapping of low-temperature induced Wcs120 family genes and regulation of cold-tolerance expression in wheat

Low-temperature (LT) induced genes of the Wcs120 family in wheat (Triticum aestivum) were mapped to specific chromosome arms using Western and Southern blot analysis on the ditelocentric series in the cultivar Chinese Spring (CS). Identified genes were located on the long arms of the homoeologous group 6 chromosomes of all 3 genomes (A, B, and D) of hexaploid wheat. Related species carrying either the A, D, or AB genomes were also examined using Southern and Western analysis with the Wcs120 probe and the WCS120 antibody. All closely related species carrying one or more of the genomes of hexaploid wheat produced a 50 kDa protein that was identified by the antibody, and a Wcs120 homoeologue was detected by Southern analysis in all species. In the absence of chromosome arm 6DL in hexaploid CS wheat no 50 kDa protein was produced and the high-intensity Wcs120 band was missing, indicating 6DL as the location of Wcs120 but suggesting silencing of the Wcs120 homoeologue in the A genome. Levels of proteins that cross-reacted with the Wcs120 antibody and degrees of cold tolerance were also investigated in the Chinese Spring/Cheyenne (CS/CNN) chromosome substitution series. CNN chromosome 5A increased the cold tolerance of CS wheat. Densitometry scanning of Western blots to determine protein levels showed that the group 5 chromosome 5A had a regulatory effect on the expression of the Wcs120 gene family located on the group 6 chromosomes of all three hexaploid wheat genomes.     

Water cytotoxicity and dioxins bioaccumulation in an Egyptian delta wetland ecosystem

Manzala Lake, as one of the main Egyptian wetland ecosystems, is facing risks of pollution. An in vitro cytotoxicity test using a mammalian cell line was employed to determine the toxicity of multiple pollutants in the water and Tilapia zillii fish sampled from the lake. The concentrations of seven polychlorinated dibenzo-p-dioxins and ten polychlorinated dibenzofurans were investigated in water and muscle of the fish in 2014. Cytotoxicity testing showed that the percentage inhibition of cell viability in the studied sites ranged between 56.16% and 83.22%. Dioxin analysis indicated that the average concentrations of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzofuran and 1,2,3,4,6,7,8,9-octachlorodibenzofuran were higher than the toxic equivalence quotients (TEQs) set by the World Health Organization (WHO) in all water and fish muscle samples; however, the average concentration of 2,3,7,8-tetrachlorodibenzofuran was higher only in fish muscle samples. The bioaccumulation factor (BAF) ranged dramatically between 2 and 58.5 for the detected dioxins. Adverse human health effects through the consumption of fish are not expected, because dioxin levels in fish muscle are deemed safe for human consumption. Implementation of a strategic multidisciplinary action plan is strongly recommended to sustain this delta wetland ecosystem.     

Metabolic routes of GABA formation in chick embryo brain

Sobue and Nakajima (1978) reported that GABA formation from putrescine is significant in chick embryo brain between days 6 and 8 of incubation. They attributed an important functional role to the putrescine-derived GABA. We found that depletion of putrescine and spermidine in chick embryos by inhibition of ornithine decarboxylase activity did not decrease the in vivo rate of GABA formation, showing that putrescine is, from a quantitative point of view, a negligible source for GABA in chick embryo brain. The changes of brain GABA levels obtained after administration of glutamate decarboxylase inhibitors and in vitro determinations of glutamate decarboxylase activity were compatible with the assumption that GABA is mainly formed by decarboxylation of l-glutamate, even during early brain development. Participation of the NAD⁺-dependent, aerobic transformation of glutamate into GABA (Seiler and Wagner, 1976) in the overall GABA production of chick embryo brain could, however, not be excluded.