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H Rose

Publications and source records attributed to H Rose.

At least 37 records · Page 2Linked to original sources
PubMed1997

Automatic correction of the interfering effect of unsuppressed interspersed repetitive sequences in comparative genomic hybridization analysis.

Comparative genomic hybridization (CGH) is a relatively new technique whose application is increasing. The method has mostly been employed for detection of chromosome aberrations in cancers, and a large amount of data in this field is accumulating. At the same time, efforts are made to improve the technique in order to increase the sensitivity and the generation of reliable results. Based on experimental data, we have developed a computer algorithm for eliminating some of the interfering effects of unsuppressed repetitive sequences in CGH analysis, and thereby improved our CGH analysis system.

Algorithms↗
PubMed1997

Optimization of road networks using evolutionary strategies

A road network usually has to fulfill two requirements: (i) it should as far as possible provide direct connections between nodes to avoid large detours; and (ii) the costs for road construction and maintenance, which are assumed proportional to the total length of the roads, should be low. The optimal solution is a compromise between these contradictory demands, which in our model can be weighted by a parameter. The road optimization problem belongs to the class of frustrated optimization problems. In this paper, a special class of evolutionary strategies, such as the Boltzmann and Darwin and mixed strategies, are applied to find differently optimized solutions (graphs of varying density) for the road network, depending on the degree of frustration. We show that the optimization process occurs on two different time scales. In the asymptotic limit, a fixed relation between the mean connection distance (detour) and the total length (costs) of the network exists that defines a range of possible compromises. Furthermore, we investigate the density of states, which describes the number of solutions with a certain fitness value in the stationary regime. We find that the network problem belongs to a class of optimization problems in which more effort in optimization certainly yields better solutions. An analytical approximation for the relation between effort and improvement is derived.

Journal Article↗
PubMed1997

Detection of chromosomal aberrations in seminomatous germ cell tumours using comparative genomic hybridization.

Comparative genomic hybridization (CGH) was used to evaluate tissue specimens from 16 seminomas in order to elucidate the pathogenesis of germ cell tumours in males. A characteristic pattern of losses and gains within the entire genomes was detected in 94% of the seminomas by comparing the ratio profiles of the tumours with a standard of cytogenetically normal genomic DNA. Losses represented 43% of the total number of alterations often affecting chromosomes and chromosome arms 4, 5, 11, 13q, and 18q. Gains amounted to 57% and were often observed on 1q, 7, 8, 12, 14q, 15q, 21q, and 22q. Aberrations of 12p and 21q appeared most consistently. Results from CGH analysis displayed no relationship to the clinical stages of the malignancy. Some rare aberrations appeared, however, only in clinical stage II and in tumours showing relapse in the contralateral testis following orchiectomy, although the alterations were not present in all of the tumours in question. Losses of 16q13-21 and gains of 9q22.1-22.2 were demonstrated in both groups, while loss of 16p12 and gains of 6p21 and 6q23.3-24 were detected in the latter group as well. In conclusion, a specific pattern of chromosomal alterations was demonstrated in the seminomas by improved detection criteria, which increased specificity and sensitivity. The rare aberrations, which appeared only in tumours in improved detection criteria, which increased specificity and sensitivity. The rare aberrations, which appeared only in tumours in clinical stage II and relapsed tumours, may be linked to tumour progression, invasiveness, and bilateral disease.

Chromosome Aberrations↗
PubMed1996

The effect of anoxia on cardiomyocyte glucose transport does not involve an adenosine release or a change in energy state.

The action of anoxia on glucose transport was investigated in isolated resting rat cardiomyocytes. Incubation of these cells in the absence of oxygen for 30 min resulted in a 4- to 5-fold increase in glucose transport (with a lag period of 5-10 min). Up to 40 min of anoxia failed to alter the cellular concentrations of ATP, phosphocreatine, and creatine. Adenosine deaminase (1.5 U/ml), the A1-adenosine receptor antagonist 1,3-diethyl-8-phenylxanthine (1 microM), or the A2-selective antagonist 3,7-dimethyl-1-propargylxanthine (20 microM) had no effect on anoxia-dependent glucose transport. Moreover, adenosine (10-300 microM, added under normoxia) did not stimulate glucose transport. Wortmannin (1 microM) did not influence the effect of anoxia, but completely suppressed that of insulin. On the other hand, the effects of anoxia and insulin were not additive. These results indicate (i) that the effect of anoxia on cardiomyocyte glucose transport is not mediated by a change in energy metabolism, nor by an adenosine release; (ii) that it probably does not involve a phosphatidylinositol 3-kinase, in contrast to the effect of insulin, and (iii) that the signal chains triggered by anoxia or insulin may converge downstream of this enzyme, or, alternatively, that anoxic conditions may impair the action of the hormone.

Adenosine↗
PubMed1996

Contraction-independent effects of catecholamines on glucose transport in isolated rat cardiomyocytes.

The effects of catecholamines on glucose transport were studied in noncontracting isolated rat cardiomyocytes. alpha-Adrenergic treatment (phenylephrine, or norepinephrine + propranolol) led to an approximately fourfold stimulation of glucose transport in basal cells (no insulin). The effect of phenylephrine was suppressed by the alpha 2-antagonist yohimbine or the beta-antagonist propranolol. The beta-adrenergic agonist isoproterenol partially counteracted the action of phenylephrine (but not that of insulin). Phenylephrine increased glucose transport in two phases with apparent half times of 3.2 and 13.0 min, respectively. Correspondingly, different EC50 values were found after 10 and 45 min on phenylephrine addition (5.0 +/- 1.9 vs. 31.6 +/- 9.6 microM, respectively). Maximal stimulation by phenylephrine was at least partially additive to that of insulin and of other stimulators of glucose transport (e.g., H2O2, vanadate, lithium). Phenylephrine significantly increased the level of cell surface glucose carriers GLUT-1 (1.54-fold) and GLUT-4 (1.78-fold), as assessed by using the specific photolabel 2-N-[4-(1-azi-2,2,2-trifluoroethyl)benzoyl]- 1,3-bis(D-mannos-4-yloxy)propyl-2-amine. In conclusion, catecholamines stimulate cardiomyocyte glucose transport through alpha 1-adrenergic receptors independently or downstream of a contraction-evoked stimulus. This effect is at least partially explained by a recruitment of glucose transporters to the cell surface. The mechanism(s) and/or signals involved differ from those triggered by insulin and insulinomimetic agents.

Adrenergic Agents↗
PubMed1996

Signals mediating stimulation of cardiomyocyte glucose transport by the alpha-adrenergic agonist phenylephrine.

Phenylephrine, a potent stimulator of cardiomyocyte glucose transport (GT), caused a rapid rise in cytosolic Ca2+ by 30%. Agents inducing a similar Ca2+ response did not stimulate (angiotension II, vasopressin) or inhibited GT by 20% (elevated extracellular Ca2+). Stimulation of GT by phorbol myristate acetate was additive to both phases of phenylephrine's effect (4 min, 60 min). Phenylephrine had no influence on the adenosine 3', 5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) levels. Agents raising cAMP (isoproterenol) or cGMP (e.g., nitroprusside) did not stimulate GT. Wortmannin (inhibitor of 1-phosphatidylinositol 3-kinase) suppressed the action of insulin on GT but not that of phenylephrine. In contrast, the Na+/H+ exchange inhibitor amiloride (which blocks phenylephrine-induced cytosolic alkalinization or even lowers cellular pH) depressed the effect of phenylephrine by 50%, whereas insulin-stimulated GT was little affected. However, raising extracellular pH up to 8.4 failed to increase GT. Lowering pH to 6.8 decreased phenylephrine's effect by 40% whereas insulin-dependent GT was not significantly altered. Clorgyline, tranylcypromine (monoamine oxidase inhibitors), and added catalase suppressed the slow phase of phenylephrine's action, whereas amiloride also affected the fast phase. We conclude that 1) stimulation of cardiomyocyte GT by phenylephrine does not involve cAMP, cGMP, or 1-phosphatidylinositol 3-kinase; 2) protein kinase C activation cannot explain the full extent of stimulation; 3) Ca2+ release or cytosolic alkalinization may be required but is not sufficient to trigger phenylephrine's action, and 4) the slow phase of stimulation is mediated by the monoamine oxidase-dependent degradation of phenylephrine and by the resulting H2O2 formation.

Adrenergic alpha-Agonists↗
PubMed1996

Economy of contraction of cardiomyocytes as influenced by different positive inotropic interventions.

In the present study the effects of the novel cardiotonic agent EMD-57033 on contraction and energetic demand of isolated, electrically stimulated cardiomyocytes were investigated and compared with the effects of enhancement of extracellular calcium and of the beta-mimetic isoproterenol. In a specially designed setup [H. Rose, K.H. Strotmann, S. Pöpping, Y. Fischer, D. Kulsch, and H. Kammermeier. Am. J. Physiol. 261 (Heart Circ. Physiol. 30): H1329-H1334, 1991] parameters of contractile behavior and metabolic demand (O2 consumption) of isolated cardiac myocytes were measured. For a given enhancement of contractile performance (cell shortening) the increase in energetic demand (VO2) after application of EMD-57033 were markedly lower than on treatment with elevated extracellular Ca2+ concentration or with isoproterenol. This economization of positive inotropic effects was proposed to be due to two factors. First, stimulation-related ion cycling was only slightly enhanced with marked increase in contraction amplitude after application of EMD-57033. Second, calcium sensitization reflected in a leftward shift of the calcium concentration needed for half-maximum force development could be interpreted to be mediated by modulation of the cross-bridge dynamics of the myofilaments, where reduction of the switch-off rate of the cross bridges and prolongation of their force-generating states were presumed to be involved. Lowered pH (7.0) decreased economy of contraction. EMD-57033 restored contraction amplitude and economy of contraction at lowered pH.

Animals↗
PubMed1995

5-hydroxytryptamine stimulates glucose transport in cardiomyocytes via a monoamine oxidase-dependent reaction.

This study deals with the effect of 5-hydroxytryptamine (5-HT; serotonin) on glucose transport in isolated rat cardiac myocytes. In these cells, 5-HT (10-300 microns), as well as tryptamine, 5-methoxytryptamine and dopamine, elicited a 3-5 fold increase in glucose transport, as compared with control. This effect was maximal after 90 min, and was concomitant with a 1.8- and 1.5-fold increase in the amounts of glucose transporters GLUT1 and GLUT4 at the cell surface of the cardiomyocytes, as determined by using the photoaffinity label 3H-2-N-[4-(1-azi-2,2,2-trifluoroethyl)benzoyl]-1,3-bis-(D-manno s-4-yl) propyl-2-amine (3H-ATB-BMPA). In contrast, 3-3000 microM of the selective 5-HT receptor agonists 5-carboxyamido-tryptamine, alpha-methyl-serotonin, 2-methyl-serotonin or renzapride failed to stimulate glucose transport. The effect of 5-HT was not affected by (i) the 5-HT receptor antagonists methysergide (1 microM), ketanserin (1 microM), cyproheptadine (1 microM), MDL 72222 (1 microM) or ICS 205-930 (3 microM), nor by (ii) the adrenergic receptor antagonists prazosin (1 microM), yohimbine (1 microM) or propranolol (5 microM), nor by (iii) the dopaminergic antagonists SCH 23390 (1 microM) or haloperidol (1 microM). The monoamine oxidase inhibitors clorgyline (1 microM) and tranylcypromine (1 microM) completely suppressed the effect of 5-HT, whereas the control and insulin-stimulated rates of glucose transport were unaffected. Addition of catalase or glutathione diminished the 5-HT-dependent stimulation of glucose transport by 50%; these two factors are known to favour the degradation of H2O2 (which can be formed during the deamination of amines by monoamine oxidases). Glutathione also depressed the stimulatory action of exogenously added H2O2 (20 microM) by 30%. Furthermore, in cells treated with 5_HT, a time-dependent accumulation of 5-hydroxy-1H-indol-3-ylacetic acid (a product of 5-HT metabolism via monoamine oxidases) was observed, which paralleled the changes in glucose transport. In conclusion, the stimulation of glucose transport by 5-HT in cardiomyocytes is not mediated by a 5-HT1, 5-HT2, 5-HT3 or 5-HT4 receptor, nor by an adrenergic or dopaminergic receptor, but is likely to occur through the degradation of by a monoamine oxidase and concomitant formation of H2O2.

Adrenergic Antagonists↗
PubMed1995

Comparative genomic hybridization in clinical cytogenetics.

We report the results of applying comparative genomic hybridization (CGH) in a cytogenetic service laboratory for (1) determination of the origin of extra and missing chromosomal material in intricate cases of unbalanced aberrations and (2) detection of common prenatal numerical chromosome aberrations. A total of 11 fetal samples were analyzed. Seven cases of complex unbalanced aberrations that could not be identified reliably by conventional cytogenetics were successfully resolved by CGH analysis. CGH results were validated by using FISH with chromosome-specific probes. Four cases representing common prenatal numerical aberrations (trisomy 21, 18, and 13 and monosomy X) were also successfully diagnosed by CGH. We conclude that CGH is a powerful adjunct to traditional cytogenetic techniques that makes it possible to solve clinical cases of intricate unbalanced aberrations in a single hybridization. CGH may also be a useful adjunct to screen for euchromatic involvement in marker chromosomes. Further technical development may render CGH applicable for routine aberration screening.

Chromosome Aberrations↗
PubMed1995

Children's gender-based reasoning about toys.

The goal of these studies was to investigate how preschool children use gender-based reasoning in making judgments about toy preferences for themselves and for others. In Studies 1 and 2, children (n = 22, n = 71) were shown unfamiliar, non-sex-typed toys and asked to rate how much they, other girls, and other boys would like each toy. As expected, children made gender-based inferences: "What I like, children of my sex will also like, and children of the other sex will not like." Study 3 was designed to assess how children use gender-based reasoning to make decisions about attractive and unattractive toys when they are given gender labels. Children (n = 91) were shown unfamiliar toys varying in attractiveness that were given explicit gender labels (e.g., "this is a toy girls really like") or no label. With a different experimenter (to avoid demand characteristics), children rated their own and others' liking of the toys. Children used gender labels to guide their own preferences and their expectations for others. Even with very attractive toys, children liked toys less if they were labeled as being for the other sex, and expected other girls and boys to do the same. The role of gender-based reasoning in cognitive theories of gender and on children's play preferences is discussed.

Child, Preschool↗
PubMed1995

Effect of a hawthorn extract on contraction and energy turnover of isolated rat cardiomyocytes.

The hawthorn extract LI 132 (crataegus), prepared from leaves and flowers, and standardised to 2.2% flavonoids, was investigated with respect to its effect on (1) the contraction, (2) the energy-turnover and (3) the apparent refractory period (t(ref)) of isolated cardiac myocytes from adult rats. (1) The contractile behaviour of attached myocytes was analyzed by an image processing system. (2) The energy turnover was calculated from the decrease in oxygen content in the myocyte suspension, brought about by cellular respiration. It was differentiated between energy turnover related to cell shortening and that required for ionic transport processes by application of the contraction-inhibiting agent 2,3-butanedione monoxime. (3) The apparent refractory period (t(ref)) was evaluated by pacing the myocytes with increasing stimulation rates and determining the frequency at which failure of single contractions occurred. For these purposes, the myocytes were incubated in a stimulation chamber, which is part of a computer-assisted system allowing to simultaneously evaluate the mechanics and energetics of electrically induced contraction. Within a range of 30-180 microg/ml, the hawthorn extract exhibited a positive inotropic effect on the contraction amplitude accompanied by a moderate increase of energy turnover both for mechanical and ionic processes. In comparison with other positive inotropic interventions, such as application of the beta-adrenergic agonist isoprenaline, or of the cardiac glycoside ouabain (g-strophantin), or elevation of the extracellular Ca++-concentration, the effects of the hawthorn extract were significantly more economical with respect to the energetics of the myocytes. Furthermore the extract prolonged the apparent refractory period in the presence and the absence of isoprenaline, which be indicative for an antiarrhythmic potential.

Adrenergic beta-Agonists↗
PubMed1994

Long-chain fatty acid-binding to albumin: re-evaluation with directly measured concentrations.

In studies on uptake of fatty acids (FA) into organs, the unbound (or free) fatty acid fraction is commonly calculated from the concentration bound to albumin and from published binding constants. However, there is some dispute on the methods used for determining those binding constants. We developed a method allowing direct measurement of unbound FA by extending the previous studies of Svenson et al. [1] and Reed et al. [2]. Albumin was coupled to a solid phase (Sepharose 4B), loaded with FA and equilibrated with an aqueous solution. Laurate, palmitate and oleate concentrations in the aqueous phase were determined at different molar ratios of FA to albumin (r) and at different temperatures. FA albumin-binding constants (Ki) increase with chain length and decrease with temperature, in accordance with data obtained by others. However, the unbound concentrations measured are markedly lower than those obtained from binding constants, and the resulting Ki values markedly higher. This difference is presumed to result from (1) our direct measurement of unbound FA and (2) utilizing different more physiological conditions. Recalculating kinetic parameters from published FA uptake data, we found considerably different Km and Vmax values compared to the original data. Thus, the FA-binding characteristics measured in this study may influence the interpretation of FA uptake substantially.

Albumins↗
PubMed1993

Phenylarsine oxide and hydrogen peroxide stimulate glucose transport via different pathways in isolated cardiac myocytes.

The aim of this study was to investigate the stimulating effects of sulfhydryl reagents on glucose transport in isolated rat heart muscle cells and to compare them with the action of insulin. Low concentrations of the sulfhydryl oxidants hydrogen peroxide (H2O2) and diamide (5-100 microM), but also of phenylarsine oxide (PAO) (0.5-3 microM), that is known to specifically react with vicinal SH-groups, stimulated the rate of 2-deoxy-D-glucose uptake by a factor of 4 to 8 in these cells, while higher concentrations were inhibitory. The stimulating effects of H2O2 or diamide, and, to a significantly lesser extent, those of PAO or insulin, were depressed in cells pretreated with the sulfhydryl-alkylating agent N-ethylmaleimide (56-100 microM). H2O2 raised the Vmax and lowered the Km of 3-O-methyl-D-glucose uptake, while PAO or insulin solely increased Vmax. The increase in glucose transport caused by H2O2 was antagonized by the beta-adrenergic agonist isoprenaline (1 microM) or by a membrane-permeant cyclic AMP analog, whereas the effects of PAO or insulin were not altered. The action of H2O2 was additive with the stimulation induced by the protein phosphatase inhibitors okadaic acid (1 microM) or vanadate (6 mM), whereas the responses to PAO or insulin were reduced in the presence of these agents. Finally, H2O2 and PAO, but not insulin, acted additively with the protein kinase C ligand phorbol myristate acetate (0.8 microM) and with phospholipase C (0.03 units/ml). We conclude that, in cardiac myocytes, H2O2, on the one hand, and PAO (and possibly insulin), on the other hand, stimulate glucose transport via at least two distinct, SH-dependent pathways. These pathways, in turn, differ from a protein kinase C- and from a phospholipase C-mediated mechanism.

3-O-Methylglucose↗
PubMed1993

Fatty acid transfer across the myocardial capillary wall.

Interstitial transudate of isolated isometrically working perfused rat hearts was analyzed to investigate fatty acid (FA) release and transfer across the capillary wall. Unsaturated FA were released under certain conditions. Lowering medium FA (16:0) with constant or varying FA/A-ratio (A: albumin) decreased interstitial FA-concentration down to 17% of arterial FA-concentration. This was accompanied by reduced uptake-rate. Transcapillary diffusion-resistance, unless markedly altering, cannot be responsible for this observation. Calculated diffusion-rates of FA and FA* protein-complexes in the endothelial cytoplasm and interstitium indicate that FA-transfer takes place almost exclusively bound to carrier-proteins. The apparent permeability surface-area-values of FA for transendothelial FA-transfer are three orders of magnitude higher than those for sucrose; diffusion-coefficients for FA across the endothelium are close to those in water, excluding substantial diffusion-barrier of the capillary wall. Dissociation-rate-constants calculated from experimental data are in the range of those reported for FA* albumin-complexes in vitro. Thus the observed transcapillary FA-gradients are apparently due to the limited dissociation-rate of the FA*albumin-complex in the intravascular space.

Animals↗
PubMed1992

Alanine and hyperosmolarity are responsible for the stimulation of cardiomyocyte glucose transport by samples containing a glucose tolerance factor.

Low-molecular-weight, cationic samples, that were previously reported to contain a glucose tolerance factor, were obtained by partial purification from yeast extract. These samples increased the rate of glucose transport in isolated cardiomyocytes 2.0- to 2.5-fold. A further purification by gel filtration led to the separation of two active components that were identified as (i) L-alanine and (ii) an elevated osmolarity. Moreover, the effect of partially purified fractions (before gel filtration) (i) was decreased upon alanine depletion with alanine dehydrogenase and (ii) was mimicked by the additive action of alanine and of a hyperosmolar medium. These findings indicate that the effect of this partially purified material is not accounted for by a putative glucose tolerance factor. Interestingly, alanine elicited its effect at concentrations that correspond to physiological plasma values, which suggests that this amino acid might be involved in the regulation of glucose transport in cardiomyocytes. Furthermore, the effect of alanine was prevented by DL-cycloserine (1 mM) or aminooxyacetate (1 mM), but not by cycloheximide (35 microM), indicating that (a) transamination reaction(s), but not protein synthesis, is required.

Adipose Tissue↗
PubMed1992

Negative inotropic effects of the new class I antiarrhythmic agents berlafenone and alprafenone on electrically stimulated isolated cardiomyocytes.

Isolated cardiac myocytes from adult rats were used in a stimulation chamber to investigate the negative inotropic effects of propafenone and the new compounds berlafenone (1-2'-biphenyloxy)-3-tert-butylamino-propanol-2-hydrochloride, GK 23 G; CAS 18965-97-4) and alprafenone (1-(4-methylphenyl)-3-[3'-(2-hydroxy-3-tert-pentylaminopropoxy)-4'- methoxyphenyl]-1-propanonhydrochloride, AH 141; CAS 124316-02-5). This chamber is part of a new device that allows the simultaneous evaluation of mechanics and of the energetics of electrically induced contractions of the myocytes. 1. The contractile behaviour of attaches myocytes was analysed by an image processing system using digitized frames of a CCD camera. 2. The metabolic demand for excitation-contraction coupling was calculated from the drop in oxygen tension (registered by a Clark electrode) caused by suspended myocytes when stimulated in the presence of the contraction inhibiting agent 2,3-butanedione monoxime in the stimulation chamber. 3. The apparent refractory period was evaluated by pacing the myocytes with increasing stimulation rates and determining the frequency at which failure of single contractions occurred. All 3 agents produced a reduction in contraction amplitude of the electrically stimulated myocytes with a similar dose-response relationship (IC50 approx. 10 mumol/l). 4 mumol/l berlafenone reduced the contraction amplitude to 62% of control. Under these conditions the energy expenditure of the contracting cells for excitation and excitation-contraction coupling (ion-cycling) was also reduced (77 +/- 17% of control). Since most of this energy is used for Ca2+ (greater than 80%) it may be concluded that a reduced Ca2+ release causes the negative inotropic action of berlafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗