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Siegel G, Kauschmann A, Malmsten M, Klüβendorf D, Walter A. Oxygen- and shear stress-dependent regulation of blood flow in human normal and arteriosclerotic coronary arteries. PATHOPHYSIOLOGY 1994. [DOI: 10.1016/0928-4680(94)90325-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Siegel G, Kauschmann A, Klüβendorf D, Walter A, Malmsten M. Blood flow sensing by anionic biopolymers. PATHOPHYSIOLOGY 1994. [DOI: 10.1016/0928-4680(94)91038-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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78
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Siegel G, Pauli G. Determination of the individual efficiency of amplification by means of PCR-MIMIC's. Cell Mol Life Sci 1994. [DOI: 10.1007/bf01956455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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79
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Polzehl J, Stoyan D, Schulze U, Neumann P, Siegel G, Platen E, Girlich HJ, Engelbert HJ. Book review. STATISTICS-ABINGDON 1994. [DOI: 10.1080/02331889408802452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Siegel G, Rückborn K, Schnalke F, Müller J. Endothelial dysfunction in human atherosclerotic coronary arteries. Eur Heart J 1993; 14 Suppl I:99-103. [PMID: 8293787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Human coronary arteries were taken from heart transplant patients. Arteriosclerotic arteries were more depolarized and constricted over the whole PO2 range between 535 and 0 mmHg. During oxygen deficiency, control preparations showed a maximal hyperpolarization of delta V = 10.9 mV and a maximal relaxation of delta T = 0.466 g. Arteriosclerotic arteries, however, became hyperpolarized by merely delta V = 7.1 mV and relaxed by delta T = 0.258 g. In normal coronary arteries, indomethacin reduced the hypoxic hyperpolarization and dilatation at 30 mmHg PO2 by about 51%. The reduction was 27% in arteriosclerotic vessels. The complete removal of the endothelium caused a 49% (73% in arteriosclerotic coronaries) restriction of dilatory vascular reactivity. The relationship was quite similar for a carbogen Krebs solution. The hyperpolarizing and dilatory contribution of prostacyclin was 32% in normal and 12% in arteriosclerotic coronary arteries. The remainder could be attributed to the basal release of endothelium-derived hyperpolarizing factor (EDHF). Thus, it may be concluded that in arteriosclerotic blood vessels, prostacyclin (PGI2) synthesis and release are predominantly diminished. Finally, we found that the ratio PGI2/EDHF in the voltage and tension changes strongly shifted to the PGI2 side with a declining oxygen concentration. This is true for normal and arteriosclerotic vessels. In addition, a disturbed transmembrane cation distribution in the arteriosclerotic coronary vessels may be an additional explanation for the depolarized membrane potential and increased muscle tone. [Na+]i of normal arteries amounted to 16.6, of arteriosclerotic arteries to 60.9 mmol.l-1; [K+]i values were 134.6 in normal and 95.0 mmol.l-1 in arteriosclerotic coronaries, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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81
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Gosztonyi G, Schmidt V, Nickel R, Rothschild MA, Camacho S, Siegel G, Zill E, Pauli G, Schneider V. Neuropathologic analysis of postmortal brain samples of HIV-seropositive and -seronegative i.v. drug addicts. Forensic Sci Int 1993; 62:101-5. [PMID: 8300019 DOI: 10.1016/0379-0738(93)90052-c] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Between 1987 and 1992 we performed forensic-pathologic and neuropathologic examinations on 70 cases of i.v. drug addicts who died of an overdose. In almost 25% of the cases HIV-positivity was revealed by serological examinations. In all the cases, irrespective of the result of the serological examination, a diffuse, reactive astrocytosis was the most prominent histologic alteration, accompanied by more or less pronounced regressive changes of this cell type in the deep layers of the white matter. Furthermore, also in all the cases, a slight to moderate, reactive proliferation of microglia could be assessed. In a few cases of the HIV-seropositive group a lymphocytic meningitis, viz. meningoencephalitis was found; these changes may indicate an early invasion of the central nervous system (CNS) by the HIV. In spite of these inflammatory alterations, in the latter cases no HIV-specific antigens (p24 and gp41) could be demonstrated in the brain, most probably because of the small number of infectious particles. In order to reveal the earliest phase of invasion of the CNS by the HIV, we performed a search for HIV-specific nucleic acid sequences by the aid of the polymerase chain reaction (PCR) in 8 HIV-seronegative and 8 normal control cases. Although, most probably due to contamination, also the control cases exhibited some PCR-signals, these were more pronounced and appeared with more primer-pairs within the group of HIV-seronegative drug addicts. It is conceivable that HIV penetrates the CNS and is harboured in it in latent form shortly after the primary infection.(ABSTRACT TRUNCATED AT 250 WORDS)
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Malmsten M, Siegel G, Buddecke E, Schmidt A. Cation-promoted adsorption of proteoheparan sulphate. Colloids Surf B Biointerfaces 1993. [DOI: 10.1016/0927-7765(93)80016-r] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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84
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Siegel G, Rückborn K, Schnalke F, Grote J. Membrane physiological reactions of human arteriosclerotic coronary arteries to hypoxia. J Cardiovasc Pharmacol 1992; 20 Suppl 12:S217-20. [PMID: 1282975 DOI: 10.1097/00005344-199204002-00062] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Human coronary arteries were taken from heart transplant patients. Arteriosclerotic arteries were more depolarized and constricted over the whole PO2 range between 535 and 0 mm Hg. During oxygen deficiency, control preparations showed a maximal hyperpolarization of delta V = 10.9 mV and a maximal relaxation of delta T = 0.466 g. Arteriosclerotic arteries, however, became hyperpolarized by merely delta V = 7.1 mV and relaxed by delta T = 0.258 g. In normal coronary arteries, indomethacin reduced the hypoxic hyperpolarization and dilation at 30 mm Hg PO2 by about 51%. The reduction was 26% in arteriosclerotic vessels. The complete removal of the endothelium caused a 49% (74%) restriction of dilatory vascular reactivity. The relationship was quite similar for a carbogen Krebs solution. The hyperpolarizing and dilatory contribution by prostacyclin was 32% in normal and 12% in arteriosclerotic coronary arteries. The remainder could be attributed to the basal release of the endothelial dilator endothelium-derived hyperpolarizing factor (EDHF). Thus, it may be concluded that in arteriosclerotic blood vessels, prostacyclin (PGI2) synthesis and release are predominantly diminished. Finally, we found that the ratio PGI2/EDHF in the voltage and tension changes strongly shifted to the PGI2 side with a declining oxygen concentration. This is true for normal and arteriosclerotic vessels. In accordance with the activation curve for vascular smooth muscle, the hyperpolarization leads to relaxation via a closure of Ca2+ channels. Hyperpolarization of 2.5 mV reduces the tension developed by one-half.
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Siegel G, Emden J, Wenzel K, Mironneau J, Stock G. Potassium channel activation in vascular smooth muscle. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1992; 311:53-72. [PMID: 1382365 DOI: 10.1007/978-1-4615-3362-7_5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
1. Numerous compounds and changes in physical state functions shift the membrane potential of vascular smooth muscle to more negative values. The consequence is a vasodilatation because Ca2+ channels are closed. K+ channel opening frequently causes the hyperpolarization. 2. Acidification of the blood substitute solution and a fall in O2 partial pressure dilate arterial vessels. Acidosis is associated with a rise in K+ permeability and a simultaneous fall in Na+ permeability. Prostacyclin has a 20-30% share, and EDHF a 70-80% share, in hypoxic vasodilatation. Experiments with iloprost (PGI2 analogue) confirmed the K+ channel opening properties of this drug. A voltage-dependent K+ channel and a Ca(2+)-activated K+ channel, via the influence of cA-PK or cG-PK, are responsible for the hyperpolarization with iloprost and with oxygen deficiency. 3. Cicletanine and ajoene cause a concentration-dependent membrane hyperpolarization and are potent vasodilators. A cicletanine concentration, which is attained by the dosage given to patients, is sufficient to produce these effects. Ajoene exerts a hyperpolarizing and vasodilating influence even in a concentration which may occur in the extracellular space by the administration of a single garlic clove. 4. The stationary activation curve 'developed force vs. membrane potential' satisfactorily explains the effects of K+ channel openers. The tight electromechanical coupling expressed by this curve comprises a 50% vasorelaxation for a 2.5 mV hyperpolarization. In the linear part of the curve, the coupling ratio is 5.1 mV/g. 5. In the vascular smooth muscle, vasorelaxation can be evoked by membrane hyperpolarization which is linked to a simultaneous increase in K+ outward current and 42K+ efflux. In the case of substances whose influence is solely or partially receptor-mediated, cyclic nucleotides may be involved in vasorelaxation. Since cyclic nucleotides also hyperpolarize through an increase in K+ conductance, the resulting dilatation often cannot be divided into its single components. Therefore, it is sensible not to give the term "K+ channel opener" too fine a definition. The term should be applied to all substances and changes in physical states which predominantly increase the open probability of K+ channels finally via a conformational change in the cell membrane. For example, giving an acidic blood substitute solution (acidosis) is an intervention opening K+ channels. Which K+ channel and which single channel conductance is concerned in a particular case, and which 'mediator' may participate, become secondary questions.
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Siegel G, Walter A, Rückborn K, Buddecke E, Schmidt A, Gustavsson H, Lindman B. NMR Studies of Cation Induced Conformational Changes in Anionic Biopolymers at the Endothelium-Blood Interface. Polym J 1991. [DOI: 10.1295/polymj.23.697] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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87
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Bevan JA, Siegel G. Blood vessel wall matrix flow sensor: evidence and speculation. BLOOD VESSELS 1991; 28:552-6. [PMID: 1782412 DOI: 10.1159/000158903] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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88
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Cama A, Patterson AP, Kadowaki T, Kadowaki H, Siegel G, D'Ambrosio D, Lillioja S, Roth J, Taylor SI. The amino acid sequence of the insulin receptor is normal in an insulin-resistant Pima Indian. J Clin Endocrinol Metab 1990; 70:1155-61. [PMID: 2318937 DOI: 10.1210/jcem-70-4-1155] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Insulin resistance is an early predictor of development of noninsulin-dependent diabetes mellitus (NIDDM) in Pima Indians, a population with the highest reported prevalence of NIDDM. The insulin receptor plays a central role in mediating insulin action, and previous studies have demonstrated that mutations in the insulin receptor gene may cause insulin resistance. Therefore, we have cloned the insulin receptor cDNA from an insulin-resistant Pima Indian to determine if there is a mutation in the patient's insulin receptor gene. We obtained nine cDNA clones spanning exons 4-10 and 12-22 of the patient's insulin receptor gene. Polymorphisms in the nucleotide sequences for codons 523 (Ala), 1058 (His), and 1062 (Leu) provided useful markers to differentiate the patient's two alleles of the insulin receptor gene. These substitutions were silent, in that they did not alter the predicted amino acid sequence. The sequence of exons 1-3 and 11 was determined directly from genomic DNA that had been amplified using the polymerase chain reaction catalyzed by Taq DNA polymerase. Other investigators have reported defects in insulin binding and insulin receptor tyrosine kinase activity in diabetic Pima Indians. However, we did not detect any mutations in this patient's insulin receptor gene. Thus, these observations are consistent with the interpretation that the defects in insulin receptor function are acquired rather than derived from defects in the primary structure of the receptor.
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Siegel G. Operator-Stable Distributions in Separable Banach Spaces. THEORY OF PROBABILITY AND ITS APPLICATIONS 1990. [DOI: 10.1137/1134056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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90
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Elazar Z, Siegel G, Fuchs S. Association of two pertussis toxin-sensitive G-proteins with the D2-dopamine receptor from bovine striatum. EMBO J 1989; 8:2353-7. [PMID: 2571500 PMCID: PMC401169 DOI: 10.1002/j.1460-2075.1989.tb08363.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The solubilized D2-dopamine receptor from bovine striatum exhibits high and low affinity states for dopaminergic agonists. Guanine nucleotides and pertussis toxin convert the solubilized receptor from a high affinity state to a low one. A D2-receptor preparation partially purified by affinity chromatography on a haloperidol adsorbent, exhibited agonist-stimulated GTPase activity. [32P]ADP-ribosylation by pertussis toxin of this receptor preparation resulted in the specific labeling of two protein bands corresponding to mol. wts of 39 and 41 kd, in SDS-PAGE. Association of these G-proteins with the receptor was specifically inhibited by Gpp(NH)p. Immunoblot analysis of these G-proteins indicated that the 41- and 39-kd protein bands are analogous to brain Gi and Go respectively. These experiments demonstrate that two distinct pertussis toxin-sensitive G-proteins are functionally associated with bovine striatum D2-dopamine receptor.
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Cross AS, Siegel G, Byrne WR, Trautmann M, Finbloom DS. Intravenous immune globulin impairs anti-bacterial defences of a cyclophosphamide-treated host. Clin Exp Immunol 1989; 76:159-64. [PMID: 2503274 PMCID: PMC1541841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Since intravenous immune globulin (i.v.IG) could impair the clearance of autologous IgG-coated erythrocytes by the reticuloendothelial system (RES), we speculated that a patient with leucopenia who died of candida septicaemia following high dose i.v.IG may have had an impairment of his RES function. We therefore studied the ability of intact i.v.IG to impair the clearance of both soluble immune complexes and a relatively avirulent strain of E. coli from the blood of mice made leucopenic with cyclophosphamide. In the presence of leucopenia, 800 micrograms/g i.v.IG prolonged the time to clear 50% of the administered IgG anti-dinitrophenyl immune complex (T1/2) from 2.7 min to 12 min, impaired the clearance of E. coli and lowered the LD50 of the strain five-fold. This impaired clearance of soluble complexes and increased mortality (8/67 versus 37/69, P less than 0.001) following bacterial challenge was present for up to 120 and 60 min, respectively, following the administration of i.v.IG. In contrast, no significant impairment in RES function was noted when 200 micrograms/g i.v.IG was administered to leucopenic mice, or when cyclophosphamide alone was given to mice before challenge with either soluble complexes or bacteria. In addition, no change in LD50 was found when mice were pretreated with 800 micrograms/g i.v.IG alone. These data suggest that high doses of i.v.IG may impair anti-microbial defences of a leucopenic host and thereby convert a relatively avirulent organism into a pathogen.
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Siegel G, Walter A, Bostanjoglo M, Jans A, Kinne R, Piculell L, Lindman B. Ion transport and cation-polyanion interactions in vascular biomembranes. J Memb Sci 1989. [DOI: 10.1016/s0376-7388(00)82414-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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93
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Grote J, Siegel G, Zimmer K, Adler A. The interaction between oxygen and vascular wall. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1989; 248:575-81. [PMID: 2782175 DOI: 10.1007/978-1-4684-5643-1_64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In vascular strips of canine carotid arteries stepwise lowering of oxygen tension from hyperoxic levels of 550 mmHg to 20 mmHg caused in preparations with endothelium a dose-dependent hyperpolarization and relaxation of smooth muscle cells when oxygen tensions between approximately 150 mmHg and 35 mmHg were attained. Pronounced hypoxia with oxygen tensions below 30 mmHg induced a depolarisation and an increase in force generation. During comparable investigations on vessel preparations without endothelium only a slight hyperpolarization and relaxation of the smooth muscle were observed when decreasing the oxygen tension from 550 mmHg to approx. 35 mmHg. In the presence of indomethacin (10(-5) M) a small but significant reduction in the hypoxia-induced hyperpolarization and decrease in smooth muscle tone was found in intact vascular strips with endothelium. Depolarisation and contraction occurred at oxygen tensions below approx. 50-60 mmHg.
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Lampson LA, Whelan JP, Siegel G. Functional implications of class I MHC modulation in neural tissue. Ann N Y Acad Sci 1988; 540:479-82. [PMID: 3207280 DOI: 10.1111/j.1749-6632.1988.tb27142.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Lampson LA, Siegel G. Defining the mechanisms that govern immune acceptance or rejection of neural tissue. PROGRESS IN BRAIN RESEARCH 1988; 78:243-7. [PMID: 3247427 DOI: 10.1016/s0079-6123(08)60290-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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96
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Grote J, Siegel G, Zimmer K, Adler A. The influence of oxygen tension on membrane potential and tone of canine carotid artery smooth muscle. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1988; 222:481-7. [PMID: 3364274 DOI: 10.1007/978-1-4615-9510-6_57] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In vascular smooth muscle of canine carotid artery segments the decrease in oxygen tension from approximately 550 mmHg to approximately 30 mmHg leads to a dose-dependent hyperpolarization and relaxation of the vessel strip. At PO2 values below approximately 15-20 mmHg depolarization and subsequent contraction were found. All changes of the parameters investigated were reversible. Indomethacin (10(-5) M) had no significant effect on the hypoxia-dependent potential and tension changes. The hyperpolarized part of the activation curve was obtained by plotting tension versus membrane potential values.
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Siegel G. Vague Convergence for Convolutions and for Infinitely Divisible Functions. THEORY OF PROBABILITY AND ITS APPLICATIONS 1987. [DOI: 10.1137/1131021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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98
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Siegel G. Home care: the roles of hospitals and materials managers. JOURNAL OF HEALTHCARE MATERIEL MANAGEMENT 1987; 5:46-7, 50-2. [PMID: 10280403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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100
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Siegel G, Grunz H, Grundmann U, Tiedemann H, Tiedemann H. Embryonic induction and cation concentrations in amphibian embryos. CELL DIFFERENTIATION 1985; 17:209-19. [PMID: 2416476 DOI: 10.1016/0045-6039(85)90495-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Explanted ectoderm from early gastrulae of Triturus alpestris was treated with the Na-K ionophore gramicidin (10(-9) to 10(-5) M) and the Ca-ionophore A 23187 (10(-7) to 10(-5) M). The ectoderm developed almost exclusively to atypical epidermis as in the control explants. When the ectoderm was treated with ouabain (10(-4) M), intracellular Na+ increased about 4.4-fold and K+ was reduced by half. Mesenchyme cells in small number differentiated in about 40% of the ouabain-treated explants. The time course of total Na+ and K+ ion concentrations was measured over a period of 72 h in ectoderm of T. alpestris after induction with vegetalizing factor and in control explants. In the first 15 h after explantation, no significant differences between control and induced explants were found. Thereafter, the steady state concentration of K+ decreased in the induced explants, whereas the steady-state concentration of Na+ slightly increased. The membrane resting potential recorded intracellularly of ectoderm sandwiches from early gastrula stages was found to be -41.3 mV in control and -59.3 mV in induced explants. From the specific conductances and permeabilities of non-induced and induced cells it is concluded that the induction process leads to a differentiation of the cell membrane, which acquires the characteristics of ionic selectivity. Ectoderm from Ambystoma mexicanum forms neural or neuroid tissue, mesenchyme and melanophores after explantation in salt solution in up to 50% of the explants without any additions. Isolated Ambystoma ectoderm is therefore not suitable for test experiments.
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