Showing papers by "University of California, San Francisco published in 1974"
TL;DR: If human lymphocytes1 or Chinese hamster2 cells are treated with the base analogue 5-bromodeoxyuridine in the latter part of the S period, Giemsa stained chromosomes exhibit a pattern of condensed and extended segments along their length, allowing the identification of the two chromatids, and the observation of sister chromatid exchanges (SCEs) without recourse to autoradiography.
Abstract: IF human lymphocytes1 or Chinese hamster2 cells are treated with the base analogue 5-bromodeoxyuridine (BrdU) in the latter part of the S period, Giemsa stained chromosomes exhibit a pattern of condensed and extended segments along their length. This phenomenon has been attributed to a delay in the spiralisation pattern of the late replicating regions along the chromosomes. Other experiments3 with Chinese hamster ovary (CHO) cells have shown that after two rounds of replication in the presence of BrdU or IdU, sister chromatids stain differentially with Giemsa, allowing the identification of the two chromatids, and the observation of sister chromatid exchanges (SCEs) without recourse to autoradiography. The chromatid with the bifilarly substituted DNA (BrdU substituted in both strands of DNA) is less condensed and stains more weakly with Giemsa than the unifilarly substituted sister chromatid. The yield of SCEs is approximately that observed by autoradiography.
3,159 citations
Book•
01 Jan 1974
TL;DR: This chapter discusses the development of Grammar, Morphology and Syntax, and the Meanings of Language, as well as some Conventions for Building Phrase Structure Trees and Rules.
Abstract: Suponiendo que no hay conocimientos previos de linguistica, este libro es apropiado para una variedad de campos, incluida la educacion, los idiomas, la psicologia, las ciencias cognitivas, la antropologia, el ingles y la ensenanza del ingles como segundo idioma (TESL). tanto a nivel de pregrado como de posgrado. Esta edicion completamente actualizada conserva las descripciones claras, el humor y la pedagogia perfecta que han hecho del libro un exito de ventas perenne, al tiempo que agrega nueva informacion y ejercicios que hacen que cada tema sea fresco, atractivo y actual.
1,343 citations
TL;DR: The chapter presents several proposals for predicting protein hydration based on the amino acid composition of the protein; however, the two main questions concerned include—whether ionic groups are more hydrated than other polar groups, and whether the amide and peptide functions are hydrated or not.
Abstract: Publisher Summary This chapter describes many of the techniques employed to study water–macromolecules interactions, their general usefulness, points out areas of mutual support and contradiction. The chapter also presents hydration of other macromolecules and the hydration of small molecules. Four broadly based approaches to operational definitions of hydration include—(1) preferential hydration, (2) hydrodynamic hydration, (3) structural hydration, and (4) low temperature hydration. The use of high resolution X-ray and neutron diffraction data on protein crystals provides an independent approach for estimation of hydration. The chapter presents several proposals for predicting protein hydration based on the amino acid composition of the protein; however, the two main questions concerned include—whether ionic groups are more hydrated than other polar groups, and whether the amide and peptide functions are hydrated or not. Low pH, and to a much smaller degree, high pH should dehydrate proteins. Intermolecular association via ionic mechanisms should be strongly dehydrating; whereas hydrophobic interactions should not have much effect on hydration levels. Although, there is a presumption that both the enthalpy and the entropy are negative for the process of adding water molecules to isolated proteins, which are maintained in their native conformations, but there is no unequivocal evidence for this.
1,057 citations
880 citations
TL;DR: The studies quantitate the fetal circulatory changes that occur in unanesthetized fetal lambs in utero during maternal hypoxemia and acidemia.
749 citations
TL;DR: Several important statistical aspects of pharmacokinetic analyses by digital computer are discussed including selection of appropriate equations, weighting of data, precision of parameter estimates, comparisons of parameters, analysis of weighted residuals, and criteria useful in the selection of particular models.
Abstract: Several important statistical aspects of pharmacokinetic analyses by digital computer are discussed. These include selection of appropriate equations, weighting of data, precision of parameter estimates, comparisons of parameters, analysis of weighted residuals, and criteria useful in the selection of particular models. Data obtained after administration of isoniazid and isonicotinuric acid to man are analyzed to illustrate the usefulness of the discussed methods.
712 citations
TL;DR: Labial salivary gland biopsy specimens from seventy-five patients evaluated for Sjogren's syndrome showed the most marked histologic change, and focus score was found to be the most useful histologic index of severity of the disease.
647 citations
TL;DR: These reconstituted vesicles represent a simple model system for a biological proton pump capable of generating ATP from ADP and Pi and catalyzed light-dependent phosphorylation.
630 citations
TL;DR: By means of agarose-gel electrophoresis, endonuclease R.EcoRI-generated fragments of DNA from various viruses were separated, their molecular weights were determined, and complete or partial fragment maps for lambda, phi80, and hybrid phages were constructed.
Abstract: By means of agarose-gel electrophoresis, endonuclease R.EcoRI-generated fragments of DNA from various viruses were separated, their molecular weights were determined, and complete or partial fragment maps for lambda, phi80, and hybrid phages were constructed.
603 citations
TL;DR: Chinese hamster ovary cells grown for two rounds of DNA replication in the presence of BrdUrd contain sister chromatids that fluoresce differentially when stained with Hoechst 33258, and the staining patterns obtained in endoreduplicated cells clearly confirm that the polynucleotide strands of the DNA segregate into sister Chromatids as though the newly synthesized strands were laid on the outside of the replicating double helix.
Abstract: Chinese hamster ovary cells grown for two rounds of DNA replication in the presence of BrdUrd contain sister chromatids that fluoresce differentially when stained with Hoechst 33258. If such fluorescent treatments are followed by incubation in 2 X SSC or water at 62° C and staining in 3% Giemsa, the chromosomes now contain one dark (unifilarly substituted) chromatid and one light (bifilarly substituted) chromatid, i.e. are “harlequinized”. These preparations do not fade and can be studied without resorting to fluorescence microscopy. Sister chromatid exchanges (SCE's) are seen with great clarity and resolution; and all the chromosomes in a cell can be scored, which is contrary to the usual experience with autoradiography. It was found that a) the yield of SCE's is dependent upon the concentration of BrdUrd in which the cells are grown and that the maximum number of SCE's that can occur spontaneously is 0.15 per chromosome per division cycle, b) the yield of SCE's doubles if the cells are exposed to visible light that can cause the photolysis of BrdUrd-containing DNA, and c) chromosomes that appear isolabelled in autoradiographic preparations come from observable multiple exchanges and are not the result of the segregation of DNA from a binemic chromosome. Furthermore, the staining patterns obtained in endoreduplicated cells clearly confirm that the polynucleotide strands of the DNA segregate into sister chromatids as though the newly synthesized strands were laid on the outside of the replicating double helix.
565 citations
TL;DR: The relative quantities of these peptides indicate that α1(III) chains predominate in early fetal skin, but by birth and in later lifeα1(I) chains are approximately 3 times as plentiful.
TL;DR: An analysis of data by sleep cycle was carried out for the main variables concerning sleep with EEG slow waves, sleep with rapid eye movements, and awakenings, and it was suggested that the trends in sleep pattern across the night have significant implications for the brain processes which underlie the electrophysiological manifestations of sleep.
TL;DR: In this article, a simple technique for the detection of mycoplasma contamination of cultured cells was proposed, where parallel cell cultures were incubated 18 h with 3H-uridine or 3Huracil and the ratio of the specific activities of 3H -uridine labeled RNA to 3HURACil labeled RNA ( UdR U ) was determined.
TL;DR: The representation of the cochlear partition within the 3 dimensions of the inferior colliculus of the cat was studied by determining the best frequency of neurons isolated in series of parallel electrode penetrations to suggest small sectors of the basilar membrane of approximately equal length were represented across individual anatomically defined cellular laminae within the nucleus.
TL;DR: The protective action of barbiturates in canine acute focal cerebral ischemia suggests that they should be considered for anesthesia in surgery requiring cerebral vessel occlusion and perhaps even for treatment of acute stroke.
Abstract: We have found that anesthetic technique modifies the neurological and pathological sequelae of unilateral middle cerebral artery and internal carotid artery occlusion in dogs. Occlusion was performed in seven groups of six dogs during each of the following anesthetic regimens: light (0.8%) halothane, "awake," deep (1.9%) halothane, deep halothane with mean arterial pressure reduced to 55 torr, pentobarbital (56 mg per kilogram), light halothane plus 40 mg per kilogram thiopental begun just before cerebral artery occlusion, and light halothane plus 40 mg per kilogram thiopental begun 15 minutes after occlusion. Body temperature, arterial Pcoco2 Poo2 pH, and blood pressure (except as noted above) were maintained normal. Neurological examinations were performed daily. On the seventh day the dogs were killed and their brains removed for pathological study. Hemiparesis occurred in five of six dogs under light halothane and five of six awake dogs; a mean of 10.8% and 9.6%, respectively, of their right hemispher...
TL;DR: Twelve radiolabeled 14C-pesticides and herbicides were applied to the forearms of human subjects, and the urinary excretion of 14C was quantitated, indicating that all the pesticides and herbicide tested are absorbed.
TL;DR: The serum ferritin assay promises to be a useful tool in the evaluation of iron status, particularly in children, according to known changes in iron stores during development.
TL;DR: Intrinsic optical density, Folin, and Biuret color development have been carefully studied as methods of determining actin concentration in solution and it appears that the Lowry (Folin) method is the most sensitive and reliable method.
TL;DR: Experiments on the induction of sister chromatid exchanges by UV light show that, in Chinese hamster cells, these exchanges can be induced in any stage of the cell cycle, and the induction seems to be independent of DNA repair replication.
Abstract: Experiments on the induction of sister chromatid exchanges (SCE's) by UV light show that, in Chinese hamster cells, these exchanges can be induced in any stage of the cell cycle. The effect is caused by the formation of persistent lesins that lead to exchanges only if the lesion-bearing chromosomes pass through S. UV light can induce e exchanges in cell lines that carry out DNA repair replication efficiently as well as in a cell line that shows little or no repair. The induction of SCE's by UV light thus seems to be independent of DNA repair replication. Post-replication repair might be responsible for the formation of the exchanges, but they encompass longer switches of label than have been observed for this type of repair.
TL;DR: Right ventricular oxygen supply per unit oxygen demand was increased in banded lambs at rest and during isoproterenol infusion, which suggests that hypertrophied myocardium has inefficient oxygen utilization, low oxygen extraction, or both.
Abstract: Chronically hypertrophied right ventricles function normally under high systolic pressures, whereas normal right ventricles fail when they are acutely subjected to similar pressures. This phenomenon may be partly due to adaptation of the coronary circulation as well as to hypertrophy. Knowledge of the magnitude and distribution of coronary blood flow and the degree of coronary vascular reserve are important in understanding the function of hypertrophied myocardium. We studied these variables in 16 awake, 5-12-week-old, tranquilized lambs; 9 of the lambs had had their main pulmonary artery banded at 2 days of age. Pressures, cardiac output, and coronary blood flow (radioactive microsphere method) were measured at rest and during two stress states--isoproterenol and dextran infusion. Ventricular function was similar in control and banded lambs. We found significant right ventricular hypertension and both right ventricular and septal hypertrophy in the banded lambs. Total coronary blood flow per gram was sli...
TL;DR: Using a method for the rapid determination of binding capacity and subcellular distribution of radioactive dexamethasone by cultured lymphoma cells, quantitative steroid-binding experiments suggest that certain receptor-containing variants possess altered receptor molecules.
TL;DR: The present experiments show that specific cytoplasmic “receptors” for glucocorticoids are present in most tissues of the juvenile rat and rabbit which respond to these hormones, suggesting that most physiologic effects of glucocorts are mediated through these receptors.
Abstract: The adrenal glucocorticoids are almost ubiquitous as physiologic regulators in mammalian tissues. The present experiments show that specific cytoplasmic “receptors” for glucocorticoids are present in most tissues of the juvenile rat and rabbit which respond to these hormones. These findings suggest that most physiologic effects of glucocorticoids are mediated through these receptors. A few tissues such as prostate, uterus, and seminal vesicle lack the receptor and thus may not be direct “targets” for glucocorticoids. Receptor levels in juvenile and fetal rabbit tissues are generally similar. However, with rabbit thymus and rat lung there are marked changes during development, suggesting that in some cases developmental changes in receptor levels may determine hormone responsiveness. (Endocrinology 94: 998, 1974)
TL;DR: Results indicate that at least 80% of the high affinity cytochalasin B binding sites are intimately related to this transport system for the sugar transport system.
TL;DR: To evaluate the safety of prophylactic vasopressor administration prior to obstetric conduction anesthesia, equipotent doses of ephedrine, metaraminol, mephentermine, and methoxamine were administered to 16 nonanesthetized pregnant ewes near term.
Abstract: To evaluate the safety of prophylactic vasopressor administration prior to obstetric conduction anesthesia, equipotent doses of ephedrine, metaraminol, mephentermine, and methoxamine were administered to 16 nonanesthetized pregnant ewes near term. When the maternal blood pressure was increased by 50
TL;DR: The results suggest that local PGE2 production may contribute to the inflammatory changes and bone resorption seen in periodontal disease.
TL;DR: The assembly process in both apical and basal regions conforms with the concept of translational movement of particles within a fluid plasma membrane.
Abstract: Sequential thin-section, tracer (K-pyroantimonate, lanthanum, ruthenium red, and horseradish peroxidase), and freeze-fracture studies were conducted on embryos and larvae of Rana pipiens to determine the steps involved in gap junction assembly during neurulation. The zonulae occludentes, which join contiguous neuroepithelial cells, fragment into solitary domains as the neural groove deepens. These plaque-like contacts also become permeable to a variety of tracers at this juncture. Where the ridges of these domains intersect, numerous 85-A participles apparently pile up against tight junctional remnants, creating arrays recognizable as gap junctions. With neural fold closure, the remaining tight junctional elements disappear and are replaced by macular gap junctions. Well below the junctional complex, gap junctions form independent of any visible, preexisting structure. Small, variegated clusters, containing 4–30 particles located in flat, particle-free regions, characterize this area. The number of particles within these arrays increases and they subsequently blend together into a polygonally packed aggregate resembling a gap junction. The assembly process in both apical and basal regions conforms with the concept of translational movement of particles within a fluid plasma membrane.
TL;DR: A disposable coil of thin-walled Silastic tubing, permeable to oxygen and carbon dioxide, functioned as a "lung" for perfusion of isolated rat liver, comparable to those obtained with more complex oxygenation systems.
TL;DR: It is believed that microspheres 9μ in diameter are probably the best for measuring regional myocardial blood flow, since many previously unemphasized limitations were discovered.
Abstract: The accuracy of regional myocardial blood flow measurements made with microspheres of different sizes is uncertain. Therefore, we simultaneously injected radioactive microspheres of different sizes into the left atria of dogs and sheep; the microsphere diameters were 25µ, 15µ, 9µ, 1-l0µ, and filtered 1-10µ (most > 7µ). Antipyrine was sometimes simultaneously infused for 15-60 seconds. Myocardial blood flow was altered by hemorrhage, tachycardia, supravalvar aortic constriction, or infusion of methoxamine or adenosine triphosphate; left coronary artery branches were occluded on two occasions. Sometimes the percent of untrapped microspheres was estimated. All sizes of microspheres measured similar total myocardial blood flows when the percent of untrapped microspheres was known. All indicators were distributed identically to the right and left ventricular free walls and septum; ischemic areas had a 1% excess of antipyrine. With any pair of microspheres, the larger had a subendocardial excess except for 25µ ...
TL;DR: This chapter discusses different repair processes for photochemical damage in mammalian cells, which involves novel pathways, such as photo reactivation and excision repair that are distinct from normal DNA synthesis and insensitive to many inhibitors that block semi-conservative DNA replication.
Abstract: Publisher Summary This chapter discusses different repair processes for photochemical damage in mammalian cells. Eukaryotic chromosomes respond to DNA and protein damage in different ways. Damage to DNA alone has minimal effect on overall chromosomal structure that is maintained by protein. Damage to protein results in disruption of the chromosome and breaks in DNA. Repair of damage to each chromosomal component is different. Protein damage does not initially involve loss of genetic information, so repair can be affected through normal protein synthesis pathways that are active at all stages of the cell cycle. Repair of DNA involves novel pathways, such as photo reactivation and excision repair that are distinct from normal DNA synthesis and insensitive to many inhibitors that block semi-conservative DNA replication. During normal replication, there is an additional recovery system, S-phase recovery, which enables DNA to be replicated on damaged templates.
TL;DR: Intestinal oxalate absorption as reflected by renalOxalate excretion was studied in normal subjects, in patients with an ileostomy who had total colectomy, and in patients who had ileal resection for regional enteritis.