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At least 1,009 records · Page 56Linked to original sources
PubMed1989

Influence of electrophilic character and glutathione depletion on chemical dysmorphogenesis in cultured rat embryos.

To examine the importance of reduced intracellular glutathione (GSH) in the modulation of dysmorphogenesis and to gain insight into the electrophilic character of the embryotoxic intermediates generated in the rat embryo from N-acetoxy-2-acetylaminofluorene (AAAF) and acetaminophen (APAP) in cultured embryos, the effects of GSH depletion on the embryotoxicity, dysmorphogenesis and covalent binding of these agents were examined. Both AAAF (90 microM) and APAP (500 microM) produced concentration-dependent, statistically significant (P less than or equal to 0.05) decreases in embryonic length as well as embryonic and visceral yolk sac protein content when rat embryos were exposed in vitro between days 10 and 11 of gestation. The predominant malformations observed upon exposure to AAAF and APAP were prosencephalic hypoplasia and abnormal neurulation respectively. Exposure of conceptuses to [3H]APAP followed by separation and fractionation of the cellular RNA, DNA and protein via density gradient centrifugation resulted in detectable binding in fractions that contained protein, but not DNA or RNA. This suggested that the rat conceptus is capable of bioactivating APAP to a soft electrophile that selectively arylates protein. In contrast, conceptuses exposed to [3H]AAAF exhibited detectable binding to RNA, DNA and protein, indicative of conversion to both hard and soft electrophiles. Depletion of GSH was accomplished by pretreating conceptuses with 500 microM L-buthionine-S,R-sulfoximine (BSO) from the start of the culture period (day 9.5) until the morning of day 10. When conceptuses were depleted previously of GSH by BSO, exposure to APAP resulted in significant potentiation (relative to APAP alone) of the observed embryotoxicity. These conceptuses displayed further decreases in both embryonic size and protein content of the embryo and yolk sac, as well as increased incidence of abnormally open anterior neuropores and increased binding (3-fold) of [3H]APAP to protein. In contrast, pretreatment with BSO did not potentiate the AAAF-elicited decreases in embryonic size or protein content, nor the severity of prosencephalic hypoplasia, although a slight increase in binding of [3H]AAAF to DNA was observed. Taken together, these data are consistent with the concept that abnormal neurulation elicited by APAP results from the generation of one or more soft electrophilic species, whereas elicitation of prosencephalic hypoplasia by AAAF appears to be a consequence of conversion to a relatively hard electrophile(s).

2-Acetylaminofluorene↗
PubMed1988

Facilitation of noradrenergic character of sympathetic neurons by co-culturing with heart cells.

Noradrenergic properties of peripheral sympathetic neurons obtained from 10-12-day-old chick embryos were examined under various culture conditions. Sympathetic neurons supported by nerve growth factor in serum-free or serum-containing medium took up significant and almost equivalent amounts of [3H]norepinephrine. The uptake was markedly enhanced when neurons were co-cultured with heart cells, either in the absence or presence of nerve growth factor, for 3 days. The facilitatory effect of heart cells on the uptake was persistent only if the nerve growth factor was present. In its absence there was a gradual decrease in the uptake. Endogenous norepinephrine content was increased by several fold when sympathetic neurons were grown with either heart cells or in a medium conditioned by the heart cells. Sympathetic neurons initially selected in culture by nerve growth factor in regular medium and then exposed to a conditioned medium for 3 days exhibited a marked facilitation of [3H]norepinephrine uptake. The number of surviving neurons was almost constant when culture media were changed. Choline acetyltransferase activity of neurons grown in heart-conditioned medium plus nerve growth factor was not significantly higher than that of neurons grown in regular medium plus nerve growth factor. The overall conclusion of the study is that the noradrenergic character of sympathetic neurons can be further enhanced by heart cells or a medium conditioned by these cells.

Animals↗
PubMed1992

Differences in erythrocyte sodium transport between human plasma and artificial medium: the role and character of sodium efflux and influx stimulating plasma factors.

The main objective of this study was to further characterize the plasma factor(s) which stimulate sodium efflux from erythrocytes, which we reported previously. Dialysis of plasma against an artificial medium using membranes with varying molecular mass cut-off points revealed relative molecular mass(es) of the factor(s) of 100-1000 Da. The factor(s) could be absorbed on Dowex at pH 1.5 and Amberlite at pH 11.0, indicating 'Zwitterionic' character. They are hydrophilic and resistant to acid hydrolysis. These characteristics and direct measurements of contents made amino acids likely candidates for the efflux stimulating properties of the factor(s). Indeed, plasma amino acids added to artificial medium could abolish the sodium efflux difference between plasma and the artificial medium. The efflux stimulating effect of amino acids appeared not to be the result of sodium influx stimulation. A coincident finding was that plasma also contains dialyzable sodium influx stimulating factor(s) which are not amino acids.

Adult↗
PubMed1986

Prediction of lithogenic character of human bile by a quaternary system.

The lithogenic character of human gallbladder bile was investigated by a mathematical model on the basis of a clinical data set. Each bile was described by means of the quaternary system bile salts--phospholipids--free fatty acids--cholesterol. Reporting a set of bile samples on the tetrahedron of concentrations, a clear separation emerged between the control bile, the bile from patients with gallstones, and the bile of subjects with gallbladder dyskinesia. This group was characterized by a largely increased content of free fatty acids.

Adult↗
PubMed1983

Development of catecholaminergic phenotypic characters in the mouse locus coeruleus in vivo and in culture.

While abundant studies have begun to elucidate ontogeny of the peripheral nervous system, molecular mechanisms underlying brain development remain obscure. To approach this problem, we initiated parallel in vivo and in vitro studies of the mouse locus coeruleus (l.c.), a brainstem noradrenergic nucleus. The catecholaminergic enzymes tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) were used to monitor phenotype expression and development. TH catalytic activity and immunocytochemical reactivity were initially detectable on gestational Day 13 (E-13) in vivo, and adult levels of activity were approximately by the third postnatal week. Immunotitration studies indicated that the developmental increase was due to accumulation of enzyme molecules and not enzyme activation. The in vivo developmental profile of DBH approximated that of TH. To begin defining regulatory mechanisms, explants of embryonic brainstem were placed in culture. Explantation on E-12, prior to expression of TH or DBH, resulted in the de novo appearance of these phenotypic characters after 4 days. Explantation on E-18, after the enzymes are already expressed, was followed by a striking sixfold rise in TH activity. Immunotitration studies revealed that the increase in TH activity in E-18 cultures was attributable to increased molecule number, reproducing the in vivo results. Moreover, the E-18 explants, cultured for 3 weeks, attained higher plateau levels of TH activity than E-12 cultures, and this differences was due to increased molecule number. Morphometric analysis indicated that 3-week E-12 cultures actually had more l.c. cells than E-18 cultures, indicating that differences in TH were not due to increased cells in the E-18 l.c. Finally, systemic study revealed that the development of TH activity in culture increased progressively from E-11 to E-12 to E-13, suggesting that critical regulatory events occur at this time. Our studies suggest that the l.c. is an excellent model for the study of brain development in vivo and in vitro. Initial phenotypic expression and dramatic development occur in culture in the absence of normal targets, normal afferent innervation and, presumably, normal humoural milieu.

Animals↗
PubMed1990

Mutant characters of knotted maize leaves are determined in the innermost tissue layers.

Knotted (Kn1), a dominant mutation in maize, perturbs normal leaf development. Mutant leaves have localized regions of extra growth called knots and, in addition to the normal ligule, ectopic fringes of ligule are found on the leaf blade. Previous clonal analysis showed that the epidermal genotype was immaterial in knot formation. To establish which inner leaf layer was required for formation of knots and ectopic ligule we used a closely linked albino mutation to mark X-ray-induced clonal sectors of wild type (kn) tissue in Kn1 plants. The sectors examined frequently changed in composition of layers in the leaf both transversely and longitudinally. We present results that show that both mutant characters are determined in the middle mesophyll-bundle sheath (MMBS) layer. We show that a lateral vein can produce a knot when only half the MMBS layer around the lateral vein contains the mutant gene. We also show that the ectopic ligule in Kn1 has contributions from both the adaxial epidermal and adaxial mesophyll layer.

In Vitro Techniques↗
PubMed1994

Workstation network system which enables international exchange of characters and images at the University of Tokyo Hospital.

The circumstances when physicians want to exchange information are analyzed and the necessary requirements for workstations are discussed. Although there are many requirements, it will not be necessary to incorporate every requirement onto a single workstation. In the international setting, the capability of handling non-alphabetic characters is also important. The requirements for image display should be classified for those physicians who make their diagnosis primarily on the basis of images and those who use images as additional diagnostic information. On the basis of these discussions, the system of the University of Tokyo Hospital, which is now being implemented, is described. The system will be a network of approximately 300 workstations with one mainframe computer.

Computer Communication Networks↗
PubMed1990

Levamisole resistance in Trichostrongylus colubriformis: a sex-linked recessive character.

Reciprocal crosses between susceptible and levamisole resistant strains of Trichostrongylus colubriformis produced F1 offspring consistent with resistance being inherited as a sex-linked recessive character. The resistance status of the offspring of the backcrosses of the F1 to both parental strains supported this hypothesis. The results are consistent with resistance being controlled by a single gene, or a tightly linked group of genes, but indicate that other autosomal loci have minor effects. The results contrast with the reported observations that resistance to the benzimidazole anthelmintics is polygenic and autosomal. The results are discussed relative to a general evolutionary model for anthelmintic resistance which predicts that selection from the upper extreme of an anthelmintic tolerance distribution results in polygenicity.

Animals↗
PubMed1976

Physiological and morphological characters in two pyrimethamine-resistant lines of Plasmodium berghei SP11 after cryopreservation.

The authors describe the characters in two pyrimethamine-resistant lines of Plasmodium berghei berghei SP 11-RR after long storage at very low temperatures. In one case the line had maintained its original virulence but lost its resistance to pyrimethamine. Gametocytogenesis increased and cyclical transmission was successful. Furthermore, parasites crossed the blood-brain barrier and provoked cerebral malaria. In the other case no physiological changes could be detected. The authors conclude that, after cryopreservation, biological behaviour should always be carefully observed.

Animals↗
PubMed1990

Evolution of sexual preferences in quantitative characters.

An analysis of equilibria and dynamics of the means, variances, and covariances of female mating preference for a quantitative male secondary sexual character following a Gaussian model is presented. For many combinations of viability and sexual selection parameters the evolving Gaussian distribution of phenotypes can diverge. The results on the cases of convergence and their limiting forms suggest some reinterpretations of Fisher's "runaway" process of sexual selection. One possibility is to interpret Fisher's postulated "initial advantage not due to female preference" as a shift in viability selection where runaway evolution occurs if the mean preferred trait evolves beyond its new viability optimum (due to sexual selection). This definition is contrasted with situations in which the new viability optimum is undershot. The quantitative and qualitative conclusions differ from models that approximate genetic covariance evolution involving a constant covariance.

Biological Evolution↗
PubMed1995

Expression of crumbs confers apical character on plasma membrane domains of ectodermal epithelia of Drosophila.

The crumbs protein of Drosophila is an integral membrane protein, with 30 EGF-like and 4 laminin A G domain-like repeats in its extracellular segment, which is expressed on the apical plasma membrane of all ectodermally derived epithelia. Here, we present evidence to show that the insertion of crumbs into the plasma membrane is necessary and sufficient to confer apical character on a membrane domain. Overexpression of crumbs results in an enormous expansion of the apical plasma membrane and the concomitant reduction of the basolateral domain. This is followed by the redistribution of beta Heavy-spectrin, a component of the membrane cytoskeleton, and by the ectopic deposition of cuticle and other apical components into these areas. Strikingly, overexpression of the membrane-bound cytoplasmic portion of crumbs alone is sufficient to produce this dominant phenotype. Our results suggest that crumbs plays a key role in specifying the apical plasma membrane domain of ectodermal epithelial cells of Drosophila.

Animals↗
PubMed1995

Degradation-resistant character of synthetic hydroxyapatite blocks filled in bone defects.

The long-term changes of both the implanted hydroxyapatite (HA) blocks and the bone around them were observed radiologically to investigate the clinical usefulness of HA. HA blocks were used as a space filler in surgically created bone defects of seven cases due to curettage of bone tumours or removal for bone grafts, and they were followed up for 78 to 109 months. Bone formation around HA blocks peaked within 1 year after implantation, and then it faded gradually. However, shapes of HA blocks were rarely changed in all the cases. A clear zone around HA blocks was never observed . HA blocks were biocompatible and demonstrated a character resistant to degradation.

Adolescent↗
PubMed1986

Influence of CONH2 or COOH as C-terminus groups on the antigenic characters of immunogenic peptides.

The influence of the presence of a terminal COOH or CONH2 on the antigenic characters of synthetic immunogenic peptides has been studied on a streptococcal synthetic vaccine model. The obtained results show that when a peptide amide is used, the antibodies raised specifically against the amide group recognize neither free COOH nor the parent protein. The carboxamide group is thus unsuitable as was postulated for raising antibodies which recognize the peptide bond.

Amides↗
PubMed1986

Correlation of the character of intramolecular melting with digestibility by pepsin in precipitating and non-precipitating pig anti-Dnp antibodies.

Precipitating and non-precipitating pig anti-2,4-dinitrophenyl group (Dnp) antibodies were investigated by differential adiabatic scanning microcalorimetry in the pH range 3.7-4.5. The partial heat capacity functions obtained revealed a notable difference between the two antibody types when the analysis was done at pH 4.5 or 4.0. The transition observed at temps around 50 degrees C in a non-precipitating antibody was absent in a precipitating antibody. Under analogous conditions, pH 4.5, the precipitating antibody was fully resistant to pepsin, while the non-precipitating antibody yielded appropriate F(ab')2 and pFc'fragments. At pH 3.7 no substantial difference in the partial heat capacity function could be observed between the two antibody types. Below pH 4.0 the precipitating antibody became susceptible to peptic cleavage and yielded fragments of the same general character as the non-precipitating antibody. This finding lends support to the view that the structural block in immunoglobulin G that melts first, i.e. at temps near 50 degrees C, is the CH2 domain or a part of it.

2,4-Dinitrophenol↗
PubMed1979

The Munchausen spectrum: borderline character features.

In this paper the author presents a continuum of disease simulation that ranges from hysteria to malingering, with a range of relative unawareness to awareness of producing such deception. Focus is on the particular group of patients who consciously and repeatedly simulate disease. The frequency and form of such disease mimicry vary within such a group. A continuum in terms of frequency ranges from occasional adventures to the simulation of disease as the center of a person's life. Two groups of patients designated as exhibiting Munchausen Syndrome are defined within this continuum: (a) those who work (mostly as nurses or in other medical professions) and (b) those called "hospital hobos" --the more prototypical Munchausen patient. The author takes a somewhat different approach to Munchausen Syndrome in that it is viewed as a subgroup of the borderline character. Further, the often found exhortation for psychiatric treatment of Munchausen patients is reexamined, and caution regarding such zeal and its potential negative effects is registered.

Adult↗
PubMed1986

Two simian virus 40 (SV40)-transformed cell lines from the mouse striatum and mesencephalon presenting astrocytic characters. I. Immunological and pharmacological properties.

Dissociate cultures were initiated from embryonic rostral mesencephalic and striatal tissues dissected from the mouse brain and previously incubated with a simian virus 40 (SV40) suspension. After several weeks in culture foci of fastly dividing cells were resuspended and cloned by successive dilutions. Several clones expressing the SV40 nuclear T antigen were obtained by these procedures and two of them, one mesencephalic (F7-Mes) and one striatal (F12-Str) were screened for the expression of glial or neuronal characters. Both clones possess adenylate cyclase-linked beta 2-adrenergic receptors. They also take up and synthesize gamma-aminobutyric acid (GABA) in amounts compatible with a glial origin. As is the case for astrocytes, the uptake of GABA is inhibited by beta-alanine and rather insensitive to the presence of diaminobutyric acid (DABA), a specific inhibitor of the neuronal GABA carrier. The most convincing evidence that F7-Mes and F12-Str belong to the astrocytic lineage comes from the fact that the two cell lines synthesize glial fibrillary acidic protein (GFAP) as demonstrated by immunofluorescence and immunoblotting. In an accompanying paper we also show that these lines behave like astrocytes when considered from the point of view of neuroglial interactions.

Animals↗
PubMed1986

Two simian virus 40 (SV40)-transformed cell lines from the mouse striatum and mesencephalon presenting astrocytic characters. III. A light and electron microscopic study.

In two preceding papers we described the cloning of two astrocytic cell lines by simian virus 40 (SV40) transformation of embryonic mouse mesencephalon (F7-Mes) and striatum (F12-Str). The characterization of these lines as belonging to the astrocytic lineage is based on pharmacological, immunocytochemical and physiological data. Here we present quantitative and qualitative data on the morphological aspects of these two astrocytic clones observed under light and electron microscopy. We show that the clones present ultrastructural characters reminiscent of the morphology of young astrocytes. On one hand, they are rather similar to primary astrocytes in culture; on the other, they differ both from a clonal fibroblastic cell line (BT2) and from embryonic mouse fibroblasts in primary culture. These astroblastic clones display 4 morphologically different cell populations which we called types I, II, III and IV. Types II and III are very similar and represent the most predominant cells; their morphologies strongly remind of that of astroblasts. Type I corresponds to glioblasts and does not account for more than 15-20% of the total population. Type IV, which is very similar to differentiated velamentous astrocytes, normally represent ca. 5% of the cells. However, when the transformed cells are treated with mitomycin or mitomycin + dibutyryl cyclic AMP (dbcAMP), the proportion of type IV cells increases very much (up to more than 50% of the cells) while types I, II and III become less numerous. Morphological analysis therefore confirms that the two cell lines derived from the SV40 transformation of 14-day-old embryonic mesencephalic and striatal cells belong to the astrocytic lineage. Moreover, it seems that they can differentiate in vitro in cell culture conditions either spontaneously or under the action of pharmacological treatments known to enhance normal astrocyte maturation.

Animals↗
PubMed1992

Partial characterization, progressive development and correlations of some neoplastic characters in 20-methylcholanthrene-induced transformed murine embryonal fibroblasts.

Non-trypsinized primary fibroblast cells from 20-day-old Swiss mouse embryo was transformed by 20-methylcholanthrene (MCA) and was designated as CNCI-PM-20. The progressive development of some transformation related characters such as morphological alterations, reduced population doubling time, increased saturation density, reduced serum requirement, increased plating efficiency, loss of density dependent growth inhibition, anchorage-independent growth and tumorigenicity in mice clearly demonstrated the multistep process of carcinogenesis as well as the neoplastic nature of the cell line. Furthermore, the association of reduced requirement of serum and loss of density-dependent growth inhibition with tumorigenicity were also observed. Finally, anchorage-independent growth, greater malignant nature of transformed foci and increased number of giant cells may be required for tumorigenicity of this cell line.

Animals↗