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At least 19 recordsLinked to original sources
PubMed1978

Late S phase cells (Chinese hamster ovary) induce early S phase DNA labeling patterns in G1 phase nuclei.

Cells (Chinese hamster ovary) in G1 phase were fused with cells in late S phase to determine if a cell in late S phase can induce DNA synthesis in the nucleus of a G1 cell and, if so, to determine if the DNA synthesis so induced in a G1 phase nucleus has an autoradiographic pattern characteristic of early or of late S phase synthesis. The results indicate (i) that 89% of the G1 nuclei in late-S/G1 binucleates synthesized DNA, while only 2% of the control unfused G1 cells synthesized DNA, and (ii) that in all late-S/G1 binucleates the G1 nucleus was induced to synthesize early S phase DNA. These results are compatible with the idea that a cytoplasmically transmissible factor initiates DNA synthesis but that an intranuclear mechanism defines the temporal order of replication.

Cell Cycle↗
PubMed1992

[The indirect measurement of arterial pressure as a function of cuff width in patients in the immediate preoperative phase, the phase of entry into the operating room and in the postanesthesia phase].

The goal of this study was to compare blood pressure measures using two sizes of cuffs: one standard width (12 cm) and other with correct width that is 0.38 of arm circumference as recommended by American Heart Association. The comparisons were done among surgical patients in mediate perioperative phase, reception area of operation room and postoperative phase during the staying of the patient in the recovery room. The results demonstrated that the arterial blood pressure was hypoestimated by the use of the standard width cuff, reaching values up 30 mmHg in the systolic arterial pressure and 30 mmHg in the diastolic ones.

Adolescent↗
PubMed1992

Effect of cell exposure to top or bottom phase prior to cell partitioning in dextran-poly(ethylene glycol) aqueous phase systems: erythrocytes as a model.

Cells exposed to dextran (Dx)-rich bottom phase prior to cell partitioning in Dx-poly(ethylene glycol) (PEG) aqueous two-phase systems have lower partition ratios than cells exposed to PEG-rich top phase. Aspects of this previously observed phenomenon were explored. In the present work charge-sensitive phases made with Dx T500 and PEG 8000 were used exclusively. It was found that: (1) even on countercurrent distribution (CCD) red cells (RBC) loaded in bottom phase have a lower apparent partition ratio, G, than the same cells loaded in top phase; (2) when part of the same cell population is loaded into top phase and part into bottom phase of the same load cavities for CCD, with the cells loaded into top or bottom bearing an isotopic tracer (51Cr), the cells loaded into top phase have a higher G value than the cells loaded into bottom phase; (3) the shift in the CCD curves of human or of rat RBC between cells loaded in top or bottom phase using systems having the same polymer concentration (though different salt compositions) shows no striking difference and is, for the number of experiments run, not statistically significant; (4) when the quantity of cells loaded for CCD is reduced from 10(9) to 10(8), the G value of cells loaded in top phase is reduced slightly while that of cells loaded in bottom phase is diminished more appreciably; (5) increasing polymer concentrations yield larger differences in G values between (rat) RBC loaded in top or bottom phase; (6) when cells exposed to top or bottom phase, respectively, are centrifuged and suspended in bottom or top phase, respectively, their CCD patterns are qualitatively similar to cells exposed to these latter respective phases initially; (7) rat RBC populations containing 59Fe-labeled cells of different but distinct age are fractionated on CCD irrespective of whether loaded in top or bottom phase. An exception are populations containing very young mature labeled cells (e.g., 4-d old) which are resolved when loaded in top phase but not in bottom phase. Thus cell populations exist which can be resolved by CCD when loaded in one of the phases but not when loaded in the other. Glutaraldehyde-fixed rat RBC containing 4-d old labeled cells are fractionated by CCD irrespective of whether loaded in top or bottom phase.

Animals↗
PubMed1992

Indirect blood pressure measurement in pregnancy: Korotkoff phase 4 versus phase 5.

Controversy exists regarding which Korotkoff phase should be used to estimate diastolic blood pressure during pregnancy, some authorities recommending phase 5 (disappearance of sounds) and others suggesting phase 4 (muffling). Available data indicate that Korotkoff phase 5 more closely approximates true intraarterial diastolic pressure in pregnant women. Nonetheless, it has been suggested that phase 5 is unmeasurable in a significant number of gravid women, making this end point less desirable. However, studies examining this issue indicate that Korotkoff phase 5 is determinable in more than 90% of gravid women and that the incidence of an indeterminable phase 4 is at least as great as that for phase 5. Moreover, there appears to be greater observer variability in the measurement of phase 4 compared with phase 5. We conclude that available evidence supports recommendations for the use of Korotkoff phase 5 as the preferred end point to estimate diastolic blood pressure during pregnancy. In those few patients having very low or indeterminate phase 5 determinations, both phase 4 and phase 5 should be recorded and the former used to guide patient management. An alternative strategy is to record both phases in all gravid women beginning at the first prenatal visit so that baseline phase 4 values are available in the event that phase 5 becomes indeterminate.

Blood Pressure Determination↗
PubMed1975

Temporary expression of flagellar phase-1 in phase-2 clones of diphasic Salmonella.

Diphasic Salmonella strains, Salmonella typhimurium TM2, S. abony SW803 and their derivatives differing in flagellar shape and antigen type, were found to produce copolymer segments of phase-1 and phase-2 flagellins among flagella in phase 2, except for a strain which is non-flagellate in phase 1. The copolymer segments were not detected in phase-1 clones of any of the strains. The wave-forms of the copolymers are homologous with those of the copolymer filaments obtained by in vitro reconstitution of the corresponding phase-1 and phase-2 flagellins. Thus, in the mutant producing normal flagella in phase 1 and straight ones in phase 2, copolymer segments with curly or small waves appear among the straight filaments. Formation of the copolymers was attributed to temporary derepression of the structural gene for phase-1, flagellin, HI, in phase 2. Copolymerization occurred in a fraction of the phase-2 cell population at late exponential and early stationary phase in nutrient broth cultures. When a phase-2 cell was temporarily derepressed, the copolymers formed almost simultaneously in every growing flagellar filament of the cell. Their formation continued for a short period until the supply of phase-1 flagellin was exhausted after re-establishment of repression. This period was estimated to be 7-7 min on average, fluctuating between 4 and 13 min in a cell population of a straight flagellar mutant whose generation time was 55 min in late exponential phase.

Bacterial Proteins↗
PubMed1992

Lateral diffusion and percolation in two-phase, two-component lipid bilayers. Topology of the solid-phase domains in-plane and across the lipid bilayer.

Fluorescence recovery after photobleaching (FRAP) has recently been used to examine the percolation properties of coexisting phases in two-component, two-phase phosphatidylcholine bilayers [Vaz, W. L. C., Melo, E. C. C., & Thompson, T. E. (1989) Biophys. J. 56, 869-876]. We now report the use of FRAP to study two additional problems in similar systems. The first is the effect of solid-phase obstacles on the lateral diffusion in the fluid phase. The second is the question of whether or not, in a single bilayer, solid-phase domains in one monolayer are exactly superimposed on solid domains in the apposing monolayer. To address the first problem, the lateral diffusion of N-(7-nitrobenzoxa-2,3-diazol-4-yl)-1-palmitoyl-2-oleoylphosp hatidylethanolamine (NBD-POPE), a probe soluble only in the fluid phase when solid and fluid phases coexist, has been studied in the mixture N-lignoceroyldihydrogalactosylceramide (LigGalCer)/dipalmitoylphosphatidylcholine (DPPC). Percolation of the fluid phase occurs at a high mass fraction of solid phase. This indicates that the solid domains have a centrosymmetric shape, a characteristic which makes this a good experimental system to test theoretical simulations of diffusion in an archipelago. It is shown that agreement between theory and experiment is poor, a result that had already been observed when the obstacles were integral membrane proteins. We develop an effective-medium model for diffusion in two-phase systems which explains both our results and those obtained with integral proteins. The distinctive feature of the model is the consideration of an annular region around the obstacles where the lipids are more ordered than in the bulk fluid phase. The diffusion coefficient is then calculated by extending the free area model to two-phase systems, taking these annuli into account. The second question, the organization of the solid-phase domains across the lipid bilayer, is examined in the systems LigGalCer/DPPC and dimyristoylphosphatidylcholine (DMPC)/distearoylphosphatidylcholine (DSPC) by comparing the diffusion of a fluid-phase-soluble, gel-phase-insoluble lipid derivative which spans the two monolayers of a bilayer (NBD-membrane-spanning-phosphatidylethanolamine, NBD-msPE) with that of a probe which is restricted to a single monolayer. In LigGalCer/DPPC, 20:80, the distribution of solid domains in one of the monolayers is independent of the distribution in the apposing monolayer. In contrast, in DMPC/DSPC, 50:50, the solid domains in one monolayer are exactly superimposed upon the solid domains existing in the apposing monolayer.

Diffusion↗
PubMed1978

[The 3 phases of schizophrenic psychosis and their phase-specific psychotherapy].

It is not the diagnostic evaluation but merely the phase in which we find our patient, that determines about the process of psychotherapy with schizophrenic patients. There are three phases--or, more approximately, four phases (phase one to three plus "phase zero")--to be differentiated: Phase Zero: This phase precedes an obvious clinical appearance of psychosis. Patients feel ridiculous in their anxiety and are not yet capable to create the symptomatology of psychosis.--Intensive participation in those strange perceptions and the attempt to witness the same experiences as the patient does, often help to prevent the formation of a severe psychosis. Phase One: Deep psychosis with common symptomatology. Verbal communication in the usual form is no more possible. Only answering the patient in his own language--speaking as he speaks and behaving as he does--helps to overcome his permanent isolation. Phase Two: Stage where the patient leaves his psychotic world and does not yet live in the world of his "healthy" surroundings.--In this phase psychotherapy intends to lead towards a confrontation with the previous psychotic experiences in order to integrate them into his personality. Phase Three: Phase of return towards a more adequate behaviour.--In this phase the therapist helps his patient to build up his "narcissistic coat" in order to create a shelter, where he can retreat; out of this "cocoon" he is able to observe what happens around him, without being thrown back into a severe psychotic crisis. On the other hand there may arise situations of "relapses" (so-called intermediary stages). These phases, which resemble common depression, can be understood as substitutes of the former psychotic situation. It is insight in its uttermost distinction that leads to secondary stages. Therefore psychotherapy will be most helpful, when the understanding of the circumstances that lead to such situations, is not evaded but promoted; the more intensely these promotions, the better the prognosis.

Humans↗
PubMed1992

Erythrocyte partitioning in dextran-poly(ethylene glycol) aqueous phase systems. Events in phase and cell separation.

Early events in the partitioning process which involve characteristic kinetics of cell- and phase-specific interactions and phase separation have been described previously. This paper reports on red cell-phase droplet interactions pertaining at the time of usual phase sampling (i.e., the time at which a clear bulk interface is first apparent) and beyond in cell partitioning and countercurrent distribution experiments. In non-charge-sensitive phase systems close to the critical point, cells can be free or attached to phase droplets. Cells that are free are virtually completely in the top phase, whereas different cell populations that show essentially complete binding to droplets can nevertheless have different partition ratios and be separated, thus reflecting the effects of the difference in the cells' avidity for the phase droplets during the early, elapsed events in partitioning. At higher polymer concentrations (i.e., higher interfacial tensions), the cell populations, completely bound to phase droplets, partition completely to the interface, and consequently cannot be separated. When such systems are made charge-sensitive by the generation of a Donnan potential between the phases or made into affinity systems by the incorporation of PEG ligands (e.g., PEG-palmitate), there is a decrease in the avidity of the cells for phase droplets. The resulting increase in the ratio of free to droplet-bound red cells in the top phase at the time of sampling correlates with an increase in the partition ratio, P, observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cubic phases of lipid-containing systems. The structure of phase Q223 (space group Pm3n). An X-ray scattering study.

The hexagonal (H) and the cubic (Q223) phases of the systems dodecyltrimethylammonium chloride-water and palmitoyllysophosphatidy choline-water have been studied by X-ray scattering techniques. The signs of the reflections of phase H were determined by a systematic study as a function of the water content, those of phase Q223 were assessed using a pattern recognition approach based upon the axiom that the histograms of the electron density maps of phases Q223 and H, extrapolated to the same concentration and properly normalized in scale and shape, are very similar to each other. In the case of phase Q223, all the sign combinations (the phi-sets) compatible with the observed reflections were generated, and each of the corresponding histograms was compared with the histogram of the map of phase H. One novelty of this work is the use of a highly sensitive criterion to estimate the similarity of the histograms, namely the distance in the six-dimensional space of the moments [mean value of (delta rho)n]1/n, for 3 greater than or equal to n greater than or equal to 8. In the two systems, the use of this criterion has led to the unambiguous choice of one electron density map. The maps show that the structure of phase Q223 consists of disjointed micelles (of type I), belonging to two different classes: those of one class are quasi-spherical in shape and are centered at the points a, those of the other class are disc-shaped and are centred at the points c. The results of this work rule out a structure formed by a cage-like distribution of rods enclosing a set of quasi-spherical micelles and is consistent with previous proposals. This is the second example, after that of phase Q227, of a micellar cubic phases in lipid-containing systems; all the known examples of phase Q223 are of type I, those of phase Q227 of type II.

Freeze Fracturing↗
PubMed1992

Biomechanical properties of duodenal wall and duodenal tone during phase I and phase II of the MMC.

We used a new method, impedance planimetry, to look at variations in compliance, tone, and distension-induced peristaltic activity during phase I and phase II of the migrating myoelectric complex (MMC) in the human duodenum. A balloon was inflated stepwise with pressures up to 30 cmH2O in the duodenum, while the pressure and balloon cross-sectional area (CSA) were measured simultaneously. The biomechanical wall parameters were calculated from these measurements. Nine duodenal phase IIIs were recorded in six subjects. A balloon pressure of 20 cmH2O induced a smaller CSA in early phase I [266 (236-324) mm2] than in late phase II [385 (276-474) mm2] (P < 0.05). Balloon distensions elicited no contractions in phase I, whereas they increased contractile activity 60% (P < 0.05) proximal to the balloon and 4% distal to the balloon in late phase II. Step distensions in phase I with balloon pressures between 10 and 30 cmH2O increased the CSA from 40 (30-81) to 645 (603-704) mm2. It increased circumferential wall tension from 35 (28-63) to 429 (402-466) mm x cmH2O and the pressure elastic modulus from 9.7 (9.0-14.7) to 33.8 (27.6-33.8) cmH2O, respectively. Thus compliance differs from phase I to phase II. This is most likely caused by increased smooth muscle tone during phase I. Duodenal wall stiffness increases with the balloon pressure applied.

Adult↗
PubMed1992

The inverted hexagonal phase is more sensitive to hydroperoxidation than the multilamellar phase in phosphatidylcholine and phosphatidylethanolamine aqueous dispersions.

The effect of phase behaviour (hexagonal II phase and lamellar phase) on the peroxidation of membrane phospholipids has been investigated in dilinoleoyl phosphatidylcholine (DLPC)/dilinoleoyl phosphatidylethanolamine (DLPE) aqueous dispersions. Peroxidation was initiated with a water-soluble radical inducer 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPN). The phospholipid morphology was monitored by 31P-nuclear magnetic resonance (NMR). Phospholipid hydroperoxides (PCOOH and PEOOH) were determined by chemiluminescence high-performance liquid chromatography (CL-HPLC). In pH-induced phase transition systems, DLPE in the bilayer state was much less oxidized than in the hexagonal II state. In composition-induced phase transition systems, the formation of total hydroperoxides and the consumption of alpha-tocopherol in the hexagonal II phase were greater than in the bilayer phase. These data suggest that the hexagonal II phase is more sensitive to hydroperoxidation than the bilayer phase in phospholipid aqueous dispersions.

Chromatography, High Pressure Liquid↗
PubMed1992

Interneuronal interaction between members of quadrature phase and anti-phase pairs in the cat's visual cortex.

Interactions between adjacent simple cells recorded simultaneously from the same microelectrode placement were studied by correlational analysis. The receptive fields of pairs of such cells exhibit either 90 degrees (quadrature phase) or 180 degrees (anti-phase) phase relationships. We now show that the majority of quadrature phase pair members do not receive common input from the immediately precedent stage along the visual pathway, nor do these cells interact with each other. The anti-phase pairs show relatively strong mutual inhibition. These results suggest that each of the physically adjacent phase-related simple cells receives excitatory input from a distinct group of pre-cortical cells, and that mutual inhibitions between members of anti-phase pairs are used to construct the inhibitory subzones of these cells. We propose a model which incorporates these new results and provides a parsimonious explanation for the construction of both quadrature phase and anti-phase pairs.

Animals↗
PubMed1992

Temperature dependence of retention in reversed-phase liquid chromatography. 1. Stationary-phase considerations.

The retention mechanism in reversed-phase liquid chromatography (RPLC) has been investigated by examining the temperature dependence of retention, with emphasis on the role of the stationary phase in the retention process. Both chromatographic temperature studies and differential scanning calorimetry were used to examine the role of alkyl chain bonding density on the retention mechanism in RPLC. Phase transitions of reversed-phase stationary phases were observed at bonding densities greater than 2.84 mumol/m2. Thermodynamic constants for the transfer of a solute from the mobile phase to the stationary phase (delta H degrees and delta S degrees) were calculated for low bonding density columns, and comparison of these values to previously reported values for the partitioning of a nonpolar solute from the bulk organic liquid to water indicated that the chromatographic retention process is not well-modeled by bulk-phase oil-water partitioning processes. In addition, this data showed that the entropic contribution to retention becomes more significant with respect to the enthalpic contribution as the stationary-phase bonding density is increased, providing additional support that partitioning, rather than adsorption, is the relevant model of retention.

Chromatography, High Pressure Liquid↗
PubMed1992

Differences in radiation response between cells in S-phase and non-S-phase cells of the granulocyte/macrophage progenitor (GM-CFC) compartment.

Studies were performed to investigate the radiation response of granulocyte/macrophage progenitor cells from canine bone marrow in different proliferative states, and in which way it will change if the S-phase cells are eliminated from the irradiated populations. To obtain progenitor cells of different proliferative states, bone marrow cell suspensions were kept in liquid cultures for 1 or 3 days in the presence of colony stimulating activity. Radiation dose response curves were determined (a) for the total population of progenitor cells under normal conditions (fraction of cells in S-phase 35%), (b) in a state of rapid cycling (fraction of S-phase cells 53% to 57%), and (c) after sterilization of S-phase cells by pretreatment with 3H-thymidine. The rapidly proliferating progenitor cells showed a strong decrease in their radiosensitivity (D0 = 0.84 Gy) within the first day in suspension culture when compared to the normal population (D0 = 0.50 Gy). The cell populations from which the S-phase cells had been eliminated were found more sensitive than the respective total populations (D0 values in the range from 0.44 Gy to 0.50 Gy). The D0 values for the S-phase cells were between 0.57 Gy and 1.13 Gy depending on the proliferative state of the cell populations. These data indicate that granulocyte/macrophage progenitor cells during progression through the S-phase become less radiosensitive than they are in other phases of the cell cycle.

Animals↗
PubMed1992

Retention of C60 and C70 fullerenes on reversed-phase high-performance liquid chromatographic stationary phases.

The separation of C60 and C70 fullerenes on four different polysiloxane stationary phases was examined. It was determined that polar solvents can be used as mobile phases effectively for the separation of fullerene molecules. Unlike previously published work, a polymeric octadecyl siloxane (ODS) stationary phase provided higher separation factors for C70/C60 than did monomeric ODS stationary phases or phenyl substituted stationary phases. For example, for a methanol-diethyl ether (50:50, v/v) mobile phase and C60, k' approximately 5.0 separation factors, alpha = 3.3, were achieved with polymeric ODS compared to alpha = 2.2, with a monomeric ODS stationary phase. A linear solvation energy relationship (LSER) was used to model the importance of solvent interactions and stationary phase interaction to solute retention.

Carbon↗
PubMed1991

Growth phase-regulated expression of bolA and morphology of stationary-phase Escherichia coli cells are controlled by the novel sigma factor sigma S.

The novel sigma factor (sigma S) encoded by rpoS (katF) is required for induction of many growth phase-regulated genes and expression of a variety of stationary-phase phenotypes in Escherichia coli. Here we demonstrate that wild-type cells exhibit spherical morphology in stationary phase, whereas rpoS mutant cells remain rod shaped and are generally larger. Size reduction of E. coli cells along the growth curve is a continuous and at least biphasic process, the second phase of which is absent in rpoS-deficient cells and correlates with induction of the morphogene bolA in wild-type cells. Stationary-phase induction of bolA is dependent on sigma S. The "gearbox" a characteristic sequence motif present in the sigma S-dependent growth phase- and growth rate-regulated bolAp1 promoter, is not recognized by sigma S, since stationary-phase induction of the mcbA promoter, which also contains a gearbox, does not require sigma S, and other sigma S-controlled promoters do not contain gearboxes. However, good homology to the potential -35 and -10 consensus sequences for sigma S regulation is found in the bolAp1 promoter.

Bacterial Proteins↗