[Provoked personality changes in Greek antiquity and present brain washing].
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Greece, Ancient↗
Biomedical subjects
D Kouretas
Publications and source records attributed to D Kouretas.
Amphiareion. A precursor of the Aesculapian temples of ancient Greece.
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Greece, Ancient↗
Nonlinear binding of sex steroids to albumin and sex hormone binding globulin.
We have studied the binding of sex steroids to albumin and sex hormone binding globulin (SHBG) using gel filtration chromatography for the separation of the bound from the free fraction of the steroid. It was found that estradiol binds to the globulin and albumin in a nonlinear manner: a lag period of binding was observed at low concentrations of the proteins, followed by an exponential increase of the bound hormone as the protein concentration increased. The same was observed with dihydrotestosterone (DHT) and albumin but not with globulin. In the presence of a constant concentration of albumin, the increase of SHBG concentrations resulted in a rapid transfer of estradiol from albumin to globulin while the transfer of DHT was moderate. When whole serum was used, the increase of its amount again resulted in the transfer of estradiol from albumin to globulin. Our study showed that a substantial increase of globulin-bound hormone can occur, following small variations of the protein. This offers obvious advantages to the organism, by saving energy, material and time and plays a basic role in estradiol transfer from albumin to the much more biologically active globulin.
Albumins↗
Tannins, xenobiotic metabolism and cancer chemoprevention in experimental animals.
Tannins are plant polyphenolic compounds that are contained in large quantities in food and beverages (tea, red wine, nuts, etc.) consumed by humans daily. It has been shown that various tannins exert broad cancer chemoprotective activity in a number of animal models. This review summarizes the recent literature regarding both the mechanisms involved, and the specific organ cancer models used in laboratory animals. An increasing body of evidence demonstrates that tannins act as both anti-initiating and antipromoting agents. In view of the fact that tannins may be of valid medicinal efficacy in human clinical trials, the present review attempts to integrate results from animal studies, and considers their possible application in humans.
Animals↗
Conservation analysis of rat and human SP-A gene identifies 5' flanking sequences of rat SP-A that bind rat lung nuclear proteins.
As an initial step toward understanding regulation of tissue-specific expression of SP-A, 5' flanking sequences of the rat SP-A gene and human SP-A I gene were cloned, sequenced, and compared using dot matrix analysis. Two regions were identified, each with a considerable degree of homology between the two species. One region was proximal to the TATAA box, at position -225/-17 in rats and -226/-36 in humans, and the other at position -1115/-1026 in rats and -938/-851 in humans. Studies in rats revealed the specific binding of rat lung nuclear proteins to each of the conserved 5' flanking regions identified in rat SP-A. Binding studies using the rat proximal (rPPS) or distal (rDPS) promoter segments, or overlapping fragments of these segments, with rat nuclear extracts detected the presence of a number (1-4) of lung-specific DNA/protein complexes. When nuclear proteins from liver, a nonexpressing tissue, were used the binding profile of certain nuclear proteins differed from that of the lung. These studies, taken together, suggest that sequences within identified conserved DNA segments in the 5' flanking region of the rat SP-A gene contribute to its tissue-specific expression in rats.
Animals↗
Lipid peroxidation and tissue damage.
In recent years it has become apparent that the oxidation of lipids, or lipid peroxidation, is a crucial step in the pathogenesis of several disease states in adult and infant patients. Lipid peroxidation is a process generated naturally in small amounts in the body, mainly by the effect of several reactive oxygen species (hydroxyl radical, hydrogen peroxide etc.). It can also be generated by the action of several phagocytes. These reactive oxygen species readily attack the polyunsaturated fatty acids of the fatty acid membrane, initiating a self-propagating chain reaction. The destruction of membrane lipids and the end-products of such lipid peroxidation reactions are especially dangerous for the viability of cells, even tissues. Enzymatic (catalase, superoxide dismutasse) and nonenzymatic (vitamins A and E) natural antioxidant defence mechanisms exist; however, these mechanisms may be overcome, causing lipid peroxidation to take place. Since lipid peroxidation is a self-propagating chain-reaction, the initial oxidation of only a few lipid molecules can result in significant tissue damage. Despite extensive research in the field of lipid peroxidation it has not yet been precisely determined if it is the cause or an effect of several pathological conditions. Lipid peroxidation has been implicated in disease states such as atherosclerosis, IBD, ROP, BPD, asthma, Parkinson's disease, kidney damage, preeclampsia and others.
Animals↗
Albumin possesses intrinsic enolase activity towards dihydrotestosterone which can differentiate benign from malignant breast tumors.
Serum albumin was found to possess enolase activity towards the dihydrotestesterone (DHT) molecule, converting it from its 3-keto to 3-enol form. This activity was accompanied by albumin during all stages of purification, as well as following various treatments, a fact indicating that the enzymatic activity was an intrinsic property of albumin molecule and did not represent an impurity of the preparation. Enolase activity was decreased in parallel with the quantity of intact albumin molecules when proteolytic enzymes were used for their degradation. The activity was strongly inhibited by Ni (II) and Cu (II) ions, which bind to 3-histidine of the albumin molecule, as well as by oleic acid and cholesterol. It was also inhibited, in a reversible manner by surface-active agents. Enolase activity was found in all mammalian species studied, the specific activity however was very low in the serum of dogs. The administration of DHT to mice did not influence the albumin or enolase levels in their serum. The optimum pH of enolase was at 9.2, with a carbonate buffer solution. In addition to the serum enolase activity was found to be a feature of intracellular albumin. The two albumins exhibited the same specific activity and the same Km for DHT. The study of cytosolic albumin, obtained from human mammary gland tissue, revealed that benign and malignant tumors of this gland differed substantially with respect to their percentage of albumin. Significant differences were also observed in enolase activity, a consequence of the existence of a fraction of albumin in the malignant tissue in a polymeric form. This form exhibited a decreased enzymatic activity, compared to its monomeric form, exclusively encountered in benign breast specimens. The last observation, along with the quantitative differences of albumin in the two tissues, offers a possibility of reliable differentiation between benign and malignant breast tumors.
Animals↗
Dietary administration of tannic acid lowers plasminogen activator activity in the liver of C3H hepatoma bearing male mice.
BACKGROUND: This study was undertaken to investigate if low-dose dietary administration of tannic acid exerts its chemopreventive activity on hepatocarcinogenesis in male C3H mice through changes of plasminogen activator activity (PAA), plasminogen activator inhibition (PAI) or plasmin inhibition (Pl) in the liver of C3H hepatoma bearing male mice. MATERIALS AND METHODS: Tannic acid was administered in the drinking water of hepatoma bearing C3H mice, in a concentration of 0.0075% (group B), 0.015% (group C) and 0.03% (group D) for 9 months. PAA, PAI and PI were measured by spectrophotometric methods in macroscopically healthy liver regions. RESULTS: Tannic acid induced a decrease of PAA (53%) and an increase of PAIs (50%) in the livers of group D while tannic acid received mice showed a dramatic decrease in liver carcinomas incidence (0% vs 33.3% in the control group). CONCLUSION: The decrease of PAA in the liver of C3H hepatoma bearing male mice, might be correlated with the chemopreventive activity of tannic acid in hepatoma development.
Animals↗
Isolation and characterization of a protein from Mendole (Spicara maena) eggs that binds to DNA and inhibits its replication as well as its acid precipitation.
Proteins that bind and protect nucleic acids from acid precipitation have been characterized from human and mouse plasma. In the present study, one protein from Mendole (Spicara maena) eggs was purified to homogeneity, by means of acetone fractionation and Sephadex G-100 gel filtration. The protein inhibited DNA replication, exerted by various DNA polymerases. Amino-acid sequence analysis in the amino terminus revealed a unique sequence. Its possible physiological role is discussed.
Acids↗
A modified method for the detection of differentially expressed mRNAs without using radioactivity.
We present here a modification of the original differential display approach using a single oligo(dT) primer for the reverse transcription reaction (instead of the various oligo(dT)NM primers that subdivide the pool of mRNAs) and a combination of 25-mer or 26-mer arbitrary primers together with 30-mer anchored primers for the PCR reaction. The PCR products are, then, efficiently separated in a non-denaturing polyacrylamide gel and the bands are visualized after staining with silver nitrate. The model for the development of our differential display approach was seven clones of an insect species: the aphid Myzus pesicae (Sulzer) (Homoptera: Aphididae). We believe that our modified differential display technique, with the efficient resolution of the DNA bands in a non-denaturing gel and staining with silver can be applied as an alternative non-radioactive detection of differentially expressed messages in various cell populations. In addition, the method could be used as a supplementary tool to other techniques for examining inter- and intraspecific genetic variation in aphids.
Animals↗
Influence of storage conditions on protein profile of pepper seeds, analyzed by SDS-PAGE.
Seeds were stored under variable conditions for long or short periods of time at 5 degrees C or 25 degrees C after which they were germinated and total proteins were analyzed by SDS-PAGE. An 80 KDa protein was expressed only in the seeds that had been recently harvested (1 year storage period). A protein of 60 KDa was detected in much higher amounts in the seeds harvested in 1987 and stored at 5 degrees C for 14 years, as well as in seeds harvested in 2000 compared with the seeds harvested in 1989 and stored at 25 degrees C for 12 years. A 50 KDa protein was present in the seeds harvested in 1987 and stored at 5 degrees C, as well as in the seeds harvested in 2000 but not in the seeds harvested in 1989 and stored at 25 degrees C. It is proposed that SDS-PAGE can be used to identify proteins in germinating pepper seeds, that vary with the storage conditions. Such information could be of value for seed control and the evaluation of seed vigour.
Capsicum↗
Value of serum protective activity against acid precipitation of poly (U) in the differentiation between cirrhotic patients with and without hepatocellular carcinoma.
The serum protective activity against acid precipitation of poly (U) and a-fetoprotein levels were compared in 39 cirrhotic patients with hepatocellular carcinoma (HCC) and in 33 patients with chronic liver disease (CLD) alone, in order to differentiate malignant and nonmalignant chronic liver disease. All but one (97.4%) patients with HCC were found to have serum protective activity levels of greater than or equal to 21 micrograms/ml, whereas all but one (97%) patients with CLD had serum protective activity levels of less than or equal to 20 micrograms/ml. Mean serum protective activity levels were significantly higher in the HCC group than in those with CLD (p less than 0.0001). Serum a-fetoprotein concentrations of over 500 ng/ml, suggesting malignancy, were observed in 54% of patients with HCC and in 15% of patients with CLD. Application of the best discriminating values for protective activity (greater than 21 micrograms/ml) and for a-fetoprotein (greater than 500 ng/ml) to 72 patients with or without HCC revealed an efficiency of 97.2% for protective activity and only 68.1% for a-fetoprotein.
Adult↗
Increased protective activity against acid precipitation of poly(U) in the serum of tumor-bearing mice.
Transplantation of leukemia L1210 cells into DBA/2 mice and of Ehrlich ascites tumor cells into BALB/C mice resulted in a significant increase of protective activity against acid precipitation of poly (U) in the serum. The increase was observed as early as one day after the tumor transplantation and seems to be connected with cancer growth, since inoculation of L1210 cells into BALB/C mice did not affect the protective activity, evidently as a result of their well established inability to cause cancer in this strain. Furthermore, no increase of activity was observed when bacteria were inoculated into mice, or when the latter were partially hepatectomized. The results suggest that the protective activity against acid precipitation of poly (U) could prove to be a tumor marker for the early detection of cancer growth.
Animals↗
Enzymatic conversion of dihydrotestosterone from 3-keto to 3-enol form in the rat prostate.
Dihydrotestosterone (DHT) is the active androgen, as well as a strong tumor promoter in the prostate, where several enzymes are essential for the regulation of its activity. We localized four enzymes promoting the enolization of the 3-keto group of DHT in rat prostate. The enzymes were purified by ion-exchange chromatography, acetone fractionation and gel filtration to homogeneity, and found to have molecular sizes of 19.5, 22.0, 44.5 and 21.5 kDa. A partial characterization of the four enzymes revealed that their structure consisted of a common chain of 14.5 kDa with various subunits which differentiate the four enzymes from each other. All the enzymes exerted their activity only on 5-dihydro 3-keto steroids. The total enzymatic activity was strongly influenced by animal age, being very low before sexual maturation, as well as after castration. In the latter case the level of total activity fell to about 8% control animals. Activity was also estimated in human, pork, ram and bovine prostate and it was found that all these species have 20-25 times lower enzyme levels than rat. These results, in combination with the practically exclusive localization of the enzymes in the prostate, suggest a role relating to the bioavailability of DHT in this gland.
Age Factors↗