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91.
The yeast sterol auxotroph GL-7, which grows well on ergosterol and cholesterol, was used to study the ability of cholesteryl-(2′-hydroxy)-ethyl
ether to substitute for cholesterol. In this compound the 3j3-hydroxyl group of cholesterol is replaced by ethylene glycol
and the resulting ether still retains the amphiphilic character of cholesterol. Cholesteryl-(2Lhydroxy)-ethyl ether was found to support the growth of GL-7 as effectively as cholesterol. Crystal violet permeability and
membrane order parameter determined using a spin label were similar for cells grown on these sterols. The ability of such
ethylene glycol derivatives to substitute for cholesterol in both artificial and natural membranes should help in designing
suitable spacers through which molecules can be linked to cholesterol without affecting the normal function of cholesterol
in membranes. This in turn should prove useful in studies with surface-modified liposomes. 相似文献
92.
Synthesis of a radioactive photoactivable heterobifunctional reagent, N-oxysuccinimide ester of 2-[14C]glycyl carboxy-9-diazofluorene is described. This reagent on photolysis gives rise to a reactive carbene which rapidly inserts
into solvents like methanol. The probe can be easily linked to aldolase which on photolysis gives rise to aldolase dimer,
trimer and tetramer depending on the density of linked probe. This probe has also been linked to concanavalin A. The radioactive
concanavalin A so obtained was incubated with erythrocyte ghosts and photolysed. The membrane protein analysis by gel electrophoresis
indicated that concanavalin A has been covalently crosslinked to band 3. 相似文献
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Behari J 《Indian journal of experimental biology》2010,48(10):959-981
Existence of low level electromagnetic fields in the environment has been known since antiquity and their biological implications are noted for several decades. As such dosimetry of such field parameters and their emissions from various sources of mass utilization has been a subject of constant concern. Recent advancement in mobile communications has also drawn attention to their biological effects. Hand held children and adults alike generally use mobile sources as cordless phones in various positions with respect to the body. Further, an increasing number of mobile communication base stations have led to wide ranging concern about possible health effects of radiofrequency emissions. There are two distinct possibilities by which health could be affected as a result of radio frequency field exposure. These are thermal effects caused by holding mobile phones close to the body and extended conversations over a long period of time. Secondly, there could be possibly non thermal effects from both phones and base stations whereby the affects could also be cumulative. Some people may be adversely affected by the environmental impact of mobile phone base stations situated near their homes, schools or any other place. In addition to mobile phones, appliances like microwave oven etc are also in increasing use. Apart from the controversy over the possible health effects due to the non-thermal effect of electromagnetic fields the electromagnetic interaction of portable radio waves with human head needs to be quantitatively evaluated. Relating to this is the criteria of safe exposure to the population at large. While a lot of efforts have gone into resolving the issue, a clear picture has yet to emerge. Recent advances and the problems relating to the safety criteria are discussed. 相似文献
96.
Rakhi Agarwal S. Raisuddin Shikha Tewari Sudhir K. Goel R. B. Raizada Jai Raj Behari 《Journal of biochemical and molecular toxicology》2010,24(2):123-135
To evaluate the effect of pre‐ or posttreatment of selenium (6 μmol/kg b.w., single intraperitoneal injection) in mercury intoxication, rats were exposed to mercury (12 μmol/kg b.w., single intraperitoneal injection). Exposure to mercury resulted in induced oxidative stress in liver, kidney, and brain tissues. Marked changes in serum biochemical parameters together with alterations in histopathology and an induction in metallothionein‐I and metallothionein‐II mRNA expression in the liver and kidney were observed. Pretreatment with selenium to mercury‐exposed animals had protective effect on the liver, whereas posttreatment had partial protection on restoration of altered oxidative stress parameters. In the kidney, pretreatment with selenium showed partial protection on restoration of altered biochemical parameters, whereas no protection was observed in posttreatment. The pretreatment with selenium resulted in restoration of mercury‐induced metallothionein‐I and metallothionein‐II mRNA expression, which was completely restored in the liver whereas partial restoration was observed in the kidney. Posttreatment with selenium resulted in further induction in metallothionein‐I and metallothionein‐II mRNA expression in the liver and kidney. In the brain, selenium showed partial protection on alerted biochemical parameters. Results indicate that pretreatment with selenium is beneficial in comparison to posttreatment in mercury intoxication. Thus, dietary intake of selenium within safe limit may, therefore, enable us in combating any foreseen effects due to mercury exposure. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:123–135, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20320 相似文献
97.
Eliane R.P. Lala Leila Zalloum Márcia de Oliveira Machado Dalalio Mônica L. Gomes Silvana Marques de Araújo 《Experimental parasitology》2009,123(2):173-181
The correlation of genetic and biological diversity in Trypanosoma cruzi was studied. Strains of T. cruzi II, isolated from humans; and of T. cruzi I, isolated from wild-animal reservoirs and from triatomines in the state of Paraná, Brazil, were used. Thirty-six biological parameters measured in vitro and six in vivo, related to growth kinetics and metacyclogenesis, susceptibility to benznidazole, macrophage infection, and experimental infection in mice were evaluated. Data from RAPD and SSR-PCR were used as genetic parameters. Mantel’s test, group analysis, principal components analysis (PCA), and cladistical analyses were applied. With the Mantel’s test, a low correlation was observed when parameters related to growth kinetics and metacyclogenesis in vitro and development of the experimental infection in vivo were included. The group analysis defined two groups that were separated as to whether they produced patent parasitemia in BALB/c mice. In the larger group, strains derived from wild reservoirs were separated from strains derived from triatomines and humans. The PCA identified two groups that differed as to whether they produced a parasitemia curve in mice. The cladistical analysis supported the previous results. This study shows the importance of the parasite-host relationship for the behavior of the strains, and that the combination of methods supports, extends, and clarifies the available information. 相似文献
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There is growing concern by the public regarding the potential human health hazard due to exposure to microwave frequencies. 2.45 GHz radiation widespread use in industry, research, and medicine, and leakage into the environment is possible. In order to quantitate this, experiments were performed on developing rat brain. Male Wistar 35-day-old rats (n = 6) were used for this study. Animals were exposed to 2.45 GHz radiation for 2 h/day for a period of 35 days at a power density of 0.344 mW/cm(2) (SAR 0.11 W/kg). The control group was sham irradiated. After 35 days these rats were sacrificed and whole brain tissue was isolated for protein kinase C (PKC) assay. For morphological study the forebrain was isolated from the whole brain and PKC activity was measured using P(32) labeled ATP. Our study reveals a statistically significant (p < 0.05) decrease in PKC activity in hippocampus as compared to the remaining portion of the whole brain and the control group. A similar experiment conducted on hippocampus and the whole brain gave a similar result. Electron microscopic study shows an increase in the glial cell population in the exposed group as compared to the control group. This present study is indicative of a significant change after exposure to the above-mentioned field intensity. This suggests that chronic exposures may affect brain growth and development. 相似文献
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