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At least 1,477 records · Page 82Linked to original sources
PubMed1987

[The character of human placental glucose and amino acid transport activity (using microvillous membrane vesicles)].

To elucidate the character of human placental D-glucose and L-alanine transport activity, we investigated the uptake of D-glucose and L-alanine into microvillous membrane vesicles prepared from human early and term placenta using the rapid filtration technique. 1. The uptake of D-glucose into microvillous membrane vesicles did not depend on the Na+ gradient (extravesicular greater than intravesicular). The uptake of D-glucose into vesicles was three times as great as that of L-glucose. And phloretin prominently inhibited the uptake of D-glucose into vesicles. So, it was indicated that the transport mechanism of D-glucose across microvillous membrane was facilitated diffusion. 2. The uptake of L-alanine into microvillous membrane vesicles depended on Na+ gradient (extravesicular greater than intravesicular), so that the transport mechanism of L-alanine across microvillous membrane was a secondary active one. The transport of L-alanine into vesicles prepared from term placenta increased prominently compared to that of early placenta. On the other hand, the transport activity of D-glucose into vesicles prepared from term placenta did not differ from that of early placenta.

Alanine↗
PubMed1986

[Establishment of the human stomach poorly-differentiated adenocarcinoma (PdGC-81) cell line and its biological character].

The gastric cancer specimen was obtained from a female patient, 65 years old. The metastatic node in the greater omentum, demonstrated by pathology as a poorly-differentiated adenocarcinoma, was cut into small cubes (1 mm3) and cultured. The human stomach poorly-differentiated adenocarcinoma cell line (PdGC-81) was thus established. It had been transferred for 83 generations during 13 months. This cell line showed the following characters: 1. The pathological features of the tumor transplanted in mice was similar to that of the original inoculated lesion. 2. Microscopically, the majority of the cells were elliptical and polygonal epithelial cells with abnormal mitotic figures and 2-4 nucleoli. 3. Electronmicroscopically, there were rich microvilli on the surface of the cells. Desmosomes and abundant ribosomes were also observed. 4. The growth curves of the 33rd and 65th passages were determined. They multiplied 23 and 21 times within 8 days, the doubling times were 41.4 and 43.4 hours. The mitotic indexes attained their peak on day 3 in 33rd passage (80.5%) and on day 4 in 65th passage (72%). 5. The numbers of the chromosomes ranged from 56 to 60. This cell line may be considered as the subtriploid.

Adenocarcinoma↗
PubMed1986

Demonstration of the amphiphilic character of hormone-sensitive lipase by temperature-induced phase separation in Triton X-114 and charge-shift electrophoresis.

Temperature-induced phase separation in Triton X-114 (Bordier, C. (1981) J. Biol. Chem. 256, 1604-1607) and charge-shift electrophoresis (Helenius, A., and Simons, K. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 529-532) were used to examine the amphiphilic character of hormone-sensitive lipase, purified from rat adipose tissue. In contrast to ATP-citrate lyase, a reference hydrophilic protein, the lipase was shown to partition predominantly (approximately 80%) into the detergent-rich phase upon phase separation in Triton X-114. Furthermore, its electrophoretic mobility was markedly shifted anodally and cathodally upon charge-shift electrophoresis in the presence of sodium taurodeoxycholate and cetyltrimethylammonium bromide, respectively. The results demonstrate that hormone-sensitive lipase possesses detergent-binding hydrophobic domain(s) and exhibits the same amphiphilicity as typical intrinsic membrane proteins.

ATP Citrate (pro-S)-Lyase↗
PubMed1985

Effect of thiourea on the testicular steroidogenesis and secondary sexual characters of a tropical freshwater fish, Mystus (M) vittatus (Bloch).

300 ppm of thiourea solution was found to produce significant decline in the interstitial cells of the testes of Mystus (M) vittatus. The regressive changes have been observed both in the number and the size (diameter) of these cells. The thiourea though could not bring about appreciable changes up to the second week, but during third and fourth week marked cellular regression in the interstitial cells has been recorded. Such cellular changes appear to influence the development of the genital papilla and caudal thickening (the secondary sexual characters - SSC) in the male specimens. Changes in the interstitial cells indicative of gonadal steroidogenesis correlated with the SSC is for the first time reported in a tropical fish. Interesting findings have been described and discussed.

Animals↗
PubMed1985

[How does one confirm the definitive character of the menopause on a clinical basis].

The statement of the definitive character of the menopause is not easy, save in the case of surgical castration. In all other cases one has seen the reappearance of the menstrual periods after several months of amenorrhoea. Although, in principle, amenorrhoea of an entire year's duration corresponds to the menopause, there are exceptions. In the case of women who are undergoing contraceptive treatment, the only means of knowing if they are menopausal consists of interruption of the oestro-progestational contraception and of advising the use of a local contraceptive for a period of several months.

Adult↗
PubMedDate not supplied

Studies on the familial character of endemic Balkan nephropathy. Possible role of the toxic hydric factor in the determination of "familial agglomerations" in endemic Balkan nephropathy.

The study was carried out in an attempt to explain the familial character of endemic Balkan nephropathy and of agglomeration of cases in certain households and in the ascendency of certain families. The hypotheses of a genetic disease or that of an infectious etiology have been taken into consideration in previous studies - by chromosomal analyses and statistical-mathematic tests of contagiousness - without being able to find arguments in support of one or the other hypotheses. This study brings important elements in favour of the possible role of ecologic factors and mainly of the hydrictoxic one, in the determination of the familial agglomerations in endemic nephropathy. Thus using radionuclear determination methods, we could demonstrate in a locality of the endemic area that around the water sources with high content of nephrotoxic oligoelements (cadmium, chromium, manganese, cobalt) there are more diseased families than around water sources poorer in these oligoelements.

Balkan Nephropathy↗
PubMed1979

Clostridium perfringens type A: certain characters of epidemiologic significance.

Survival of spores of Cl. perfringens type A was significantly greater than that of vegetative cells in acid pH (pH 1.2). Survival of spores in soil varied from strain to strain. Time required for 5 million spores to be reduced to 500 per gram of soil varied from 2 to 8 months with an average of 4.5+/-2.3 months. Quantitative and qualitative heat resistance studies revealed that a majority of the Indian and all the American strains tested were heat-sensitive. These characters of Cl. perfringens have an important bearing on the epidemiology of food poisoning due to this agent.

Clostridium perfringens↗
PubMedDate not supplied

[Character of functional connections between sensomotor cortex neurons during isolated and combined stimulation of thalamic nuclei].

In experiments on curarized cats pronounced transformations of the "excitatory" component of the "inhibitory-excitatory" dependence of two close neurones in the sensorimotor cortex were found following multiple isolated VPL and VL stimulation. The effects of repetitive stimulation of thalamic nuclei were opposite to each other: VPL stimulation mainly weakened the "excitatory" component of the "inhibitory-excitatory" connection, whereas VL stimulation generally enhanced it. In the course of combined stimulations of both nuclei the character of interneuronal relations, established under the influence of isolated stimuli, showed further changes. Modifications of interneuronal dependence, resulting from thalamic stimulation, could last for several minutes after cessation of all stimulations.

Animals↗
PubMedDate not supplied

[Character of short-term changes in the total number of soil bacteria, including ammonifiers, during the growing season].

The total incidence of bacteria and the number of ammonificators were assayed to the direct count and plating techniques, respectively, several times within the vegetative period in the course of ten days under the field conditions. The incidence of the former and the latter varied though not in parallel, and the variations were temporal. The total bacterial incidence depended considerably on soil water content; in ammonificators, moisture determined only the level at which their number changed. The character of oscillations is suggestive of the rate of microbial growth at different periods of the vegetative stage. Daily determination of their number several times within the same period may result in contradictory conclusions.

Ammonia↗
PubMed1968

Taxonomic characters in the genus Echinococcus (Cestoda: Taeniidae).

Not more than 4 species of cestodes of the genus Echinococcus Rudolphi, 1801, are recognised as valid. The larval stage of at least 3 of them is able to develop in man, causing respective types of hydatid disease. Accurate characterization of these cestodes, including both larval and adult stages, is essential for identification, upon which depends development of methods for preventing infection of man and domestic animals. Because morphological characteristics of the larval cestodes may be modified according to the species of host in which they develop, identification should be based upon taxonomic characters of specimens from the respective natural hosts, which can be identified by means of ecological investigations in endemic areas in combination with controlled infection of experimental animals. The morphological and biological characteristics of the known species are discussed, and the two species most important to public health and economically-E. granulosus (Batsch, 1786) and E. multilocularis Leuckart, 1863-are distinguished.

Echinococcus↗
PubMed1977

Influence of a progestogen on the cytophysiologic character of the bovine adenohypophysis.

The objective in the present experiment was to study the effects of melengestrol acetate (0.5 mg for 14 days starting at day 15 of the estrous cycle) on the cytophysiologic character of the bovine adenohypophysis. Twelve Hereford and Angus heifers were used. A combination of thick-thin sectioning of resin-embedded material was used to aid in specific identification of individual hypophyseal cells. Alterations were not observed in the cytophysiologic activity of the presumptive prolactin-, somatotropin-, thyrotropin- or corticotropin-secreting cells. A marked increase in chromophobes was observed in animals given melengestrol acetate. Evidence indicated that these chromophobes originated from gonadotropin-secreting cells.

Animals↗
PubMed1977

The mechanism of group differences in the character of the vaccinal process in immunization against natural smallpox.

The effect of antigenic polymorphism of the ABO-system blood groups on the character of the vaccinal process after immunization against natural smallpox was investigated. The increased susceptibility of persons possessing A antigen to the harmful effect of smallpox vaccine virus is due to hereditary rather than to acquired factors. The leukocytes of peripheral blood of these persons showed a poorer binding capacity with respect to the smallpoxvaccine virus; they also exhibited a high rate of chromosomal aberration after vaccination, resulting to some extent from increased proliferative ability of the cells.

ABO Blood-Group System↗
PubMedDate not supplied

[Character of proprioceptive information processing during learning in rats chronically intoxicated with alcohol].

A conditioned alimentary reflex was elaborated in rats placed into K-shaped maze after 8 months of intoxication with 35 degrees alcohol. The most important changes in experimental animals, as compared to intact ones, were revealed in the character of processing of proprioceptive information coming to the brain during learning. It was found that in the animals temporal relations between the processes of analysis and synthesis and the fixation of memory trace changed. Unlike intact animals, in "alcoholic" ones the new proprioceptive information as related to the previous experience was fixed in the long-term memory and only afterwards underwent analytic and synthetic processing. It is suggested that learning was not in enlarging the information capacity of each singled-out motor unit of full decision, but in their combination into one and only one decision.

Alcoholism↗
PubMed1978

Quantitative structure-activity relationships. VI. Non-linear dependence of biological activity on hydrophobic character: calculation procedures for bilinear model.

The bilinear model, log 1/C = a log P--b log (betaP + 1) + c, is a new model for the qunatitative description of non-linear relationships between hydrophobic character and biological activity. In contrast to the parabolic Hansch model the bilinear model considers the particular effect that a linear relationship exists between lipophilicity and biological activity up to a point where this linear relationship breaks down to a non-linear relationship. Two different calculation procedures for the bilinear mode, a stepwise iteration method and the Taylor series iteration method, are explained and demonstrated with examples. The bilinear model and the parabolic Hansch model are compared by means of the statistical parameters r, s and F, by a partial F test and by an analysis of the residuals obtained with both models.

Mathematics↗
PubMed1979

Regular character of chromatin degradation in lymphoid tissues after treatment with biological alkylating agents in vivo.

The aim of the present study was to reassume the chromatin changes occurring in lymphoid tissues of mice treated with alkylating agents of the nitrogen-mustard type in relation to recent evidence on the nucleosomal organization of chromatin and to our new data on the regular character of chromatin degradation in lymphoid tissues of irradiated mice. DNA was isolated from nuclei at various intervals (1-18 h) after treatment of mice and subjected to gel electrophoresis in polyacrylamide gels. Thymus chromatin from treated mice has been shown to degrade in a regular fashion and to yield discrete DNA fragments, resembling those that originate in lymphoid tissues of irradiated mice or in thymus nuclei digested with micrococcal nuclease in vitro. With increasing interval after treatment higher amounts of smaller DNA fragments appear. Chromatin in spleen cells responds to treatment in a similar way, whilst no degradation in vivo takes place in liver chromatin. Chromatin of LS/BL lymphosarcoma cells in mice treated with alkylating agents or with irradiation suffers from a similar regular degradation. The results stress the significance of the action of liberated or activated endogenous nuclease(s) in the development of chromatin damage in lymphoid cells after treatment with alkylating agents.

Alkylating Agents↗
PubMed1981

Preservation of gastric gland character in transplantable gastric adenocarcinoma (SG2B) of rats.

The morphological and biochemical characteristics of a transplantable tumor line of rat gastric carcinoma (SG2B), that developed in a Wistar strain rat after treatment with N-methyl-N'-nitro-N-nitrosoguanidine and then 4-nitro-quinoline 1-oxide were examined at the 60th passage. The tumor was serially transplanted into newborn rats by subcutaneous and intraperitoneal routes and has been passed through 60 transplant generations over a 4-year period. The tumors appeared to be well-differentiated tubular adenocarcinomas throughout successive passages, and at each generation transplants were almost identical to the original gastric adenocarcinoma as judged by light and electron microscopic observation. Ultrastructurally, the neoplastic cell contained abundant free ribosomes and exhibited few mucin granules. The microville on the apical cell surface were short and irregularly spaced. Electrophoresis showed that pepsinogens (Pg) 3 and 4 were present but no Pg 1 was detectable at the 60th passage, as was the case in the tissue at the 2nd and 5th passages. The pepsinogen content of the tissue at the 60th passage was similar to that at the 5th passage. The tumor tissue has thus retained the morphological and biochemical character of a pyloric gland type tumor for a long time (over 4 years) during serial transplantation.

4-Nitroquinoline-1-oxide↗
PubMedDate not supplied

[Factors influencing the pulse character of RNA elongation in vitro by E. coli RNA polymerase].

Pause location along primary structure of two RNA fragments each 200 nucleotide residues in the length synthesized from A1 promoters of T7 phage DNA and delta D111 T7 phage DNA was analyzed. No correlation between the location of pauses and GC-rich or self complementary regions of RNA were found. The location of pauses does not change upon the variation of the temperature or ionic strength. Concurrent variation of all four NTP concentrations also did not influence pausing pattern. However the distribution of pauses depends highly on the ratio of the individual substrate concentrations. Substitution of GTP by ITP changes the pausing pattern completely. Inorganic pyrophosphate (PPi) of inhibits RNA elongation preferentially in the regions: NAUN, CGUAG. The study of PPi action on RNA terminated with 3' OCH3-NMP suggest that the sequence-specific inhibition of RNA elongation may be a result of pyrophosphorolysis of terminal nucleotide residues of RNA. It was proposed that the pulse character of RNA elongation stems rather from differences in the kinetic constants of nucleotides attachment and pyrophosphorolysis from the 3'-termini of RNA than by termination signals encoded in the primary structure of DNA. The stable location of pauses in certain short oligonucleotides: AUG, AUU, AAU and some others is in favour of the hypothesis.

Base Sequence↗
PubMedDate not supplied

[Regularity in the extreme character of the ontogenetic development of ovarian activity in the reproductive function self-regulation system].

Opposite conclusions were drawn depending on the sex hormones which different authors used to assess the functional condition of the ovaries at various age periods. A new index--reception coefficient (RC)--is suggested proceeding from the systemic approach to find the way out from this inconsistency. This coefficient represents the ratio of the peripheral hormone value and the gonadotropin level inducing it. Regularities of the extreme character in the ontogenetic development of the ovarian activity were established by means of RC: the maximum ovarian function under normal conditions fell on the age group of 20--29 years, and the minimum--on the age groups of under 7 and over 50 years. A sharp decline of the ovarian function began in the age group of 40--49 years.

Adolescent↗