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PubMed1999

Sparfloxacin selects gyrase mutations in first-step Mycoplasma hominis mutants, whereas ofloxacin selects topoisomerase IV mutations.

The role of mutations in the genes for GyrA and ParC in quinolone resistance in Mycoplasma hominis was studied. Selection with sparfloxacin gave mutations at GyrA83 (Ser-->Leu; Escherichia coli numbering) or GyrA87 (Glu-->Lys), and mutants had increased levels of resistance to sparfloxacin (8- to 16-fold) but not to ofloxacin. Selection with ofloxacin gave changes at ParC80 (Ser-->Ile) or ParC84 (Glu-->Lys), and mutants were four- to eightfold more resistant to ofloxacin but not to sparfloxacin. Selection of second-step mutants from strains with ParC mutations with either quinolone yielded double mutants with additional mutations at GyrA83 (Ser-->Trp or Ser-->Leu) or GyrA87 (Glu-->Lys). Second-step selection of GyrA mutants gave additional mutations at ParC80 (Ser-->Ile) or ParC84 (Glu-->Lys). Two-step mutants showed high levels of resistance to ofloxacin (MICs, 64 to 128 microg/ml) and moderate levels of resistance to sparfloxacin (MICs, 2 to 8 microg/ml). The primary target of ofloxacin in first-step mutants of Mycoplasma hominis was ParC, whereas that for sparfloxacin was GyrA.

Anti-Infective Agents↗
PubMed1974

Faecal fat excretion after truncal, selective, and highly selective vagotomy for duodenal ulcer.

Faecal fat excretion was measured on a metabolic ward in 16 patients with duodenal ulcer before operation, and in patients who were in good health more than one year after truncal vagotomy and pyloroplasty (n = 11), bilateral selective vagotomy and pyloroplasty (n = 9), or highly selective vagotomy without a drainage procedure (HSV, n = 12). Excretion of faecal fat was significantly greater (p < 0.01) in patients after both truncal and selective vagotomy with drainage than in patients before operation. Fat excretion in HSV patients was little different from that of preoperative patients. If steatorrhoea is defined as a faecal fat output of more than 6 g per day, one of 16 preoperative patients with duodenal ulcer (6%) had steatorrhoea, one of 12 HSV patients (8%) had steatorrhoea, one of nine patients after selective vagotomy and pyloroplasty (11%) had steatorrhoea but five of 11 patients after truncal vagotomy and pyloroplasty (45%) had steatorrhoea.

Adult↗
PubMed2005

Pushing around the locus of selection: evidence for the flexible-selection hypothesis.

Attention operates at an early stage in some experimental paradigms and at a late stage in others, which suggests that the locus of selection is flexible. The present study was designed to determine whether the locus of selection can vary flexibly within a single experimental paradigm as a function of relatively modest variations in stimulus and task parameters. In the first experiment, a new method for assessing the locus of selection was developed. Specifically, attention can influence perceptual encoding only if it is directed to the target before a perceptual representation of the target has been formed, whereas attention can influence postperceptual processes even if attention is cued after perception is complete. Event-related potentials were used to confirm the validity of this method. The subsequent experiments used cueing tasks in which subjects were required to perceive and remember a set of objects, and the difficulty of the perception and memory components of the task were varied. When the task overloaded perception but not working memory, attention influenced the formation of perceptual representations but not the storage of these representations in memory; when the task overloaded working memory but not perception, attention influenced the transfer of perceptual representations into memory but not the formation of the perceptual representations. Thus, attention operates to select relevant information at whatever stage or stages of processing are overloaded by a particular stimulus-task combination.

Adolescent↗
PubMed2001

Looking beyond selection probabilities: adaptation of the chi(2) measure for the performance analysis of selection methods in GAs.

Viewing the selection process in a genetic algorithm as a two-step procedure consisting of the assignment of selection probabilities and the sampling according to this distribution, we employ the chi(2) measure as a tool for the analysis of the stochastic properties of the sampling. We are thereby able to compare different selection schemes even in the case that their probability distributions coincide. Introducing a new sampling algorithm with adjustable accuracy and employing two-level test designs enables us to further reveal the intrinsic correlation structures of well-known sampling algorithms. Our methods apply well to integral methods like tournament selection and can be automated.

Algorithms↗
PubMed1996

Selective expression of insulin-like growth factor system components during porcine ovary follicular selection.

In situ hybridization was used to map anatomical patterns of insulin-like growth factor (IGF) system gene expression in the gilt ovary through the estrous cycle. IGF-I, IGF-II< and IGF-I receptor messenger RNAs (mRNAs) were coexpressed in granulosa cells of developing and dominant follicles through the follicular phase. IGF-I and IGF-I receptor mRNAs were selectively concentrated in healthy follicles, whereas IGF-II mRNA was found in all follicles regardless of incipient or overt atresia. IGF-binding protein-1 (IGFBP-1) was not detected in the gilt ovary at any stage. IGFBP-2 mRNA was most abundant in granulosa cells of small follicles and in the ovarian vasculature regardless of cycle stage. IGFBP-2 mRNA persisted in granulosa cells of preovulatory follicles and corpora lutea. IGFBP-3 mRNA was not detected in developing follicles, but was detected in all luteal phase corpora lutea, apparently expressed by theca lutein cells. IGFBP-4 demonstrated a highly dynamic pattern of gene expression, closely tracking LH receptor gene expression throughout the follicular and luteal phases of the estrous cycle. IGFBP-4 mRNA was concentrated in the theca of medium to large growing follicles, but was not detected in granulosa cells until the emergence of dominant follicles in the late follicular stage, when the granulosa cells showed morphological evidence of luteinization as well as LH receptor gene expression. IGFBP-4 mRNA expression continued in granulosa cells of corpora lutea during the luteal phase and was not detected in atretic follicles. IGFBP-5 mRNA was concentrated in the surface or germinal epithelium and in capillary endothelium, particularly in capillaries of corpora lutea. In summary, there is selective expression of IGF-I, IGF-I receptor, and IGFBP-2 and -4 mRNAs during the process of follicular selection in the gilt ovary, with IGFBP-4 expression being closely associated with follicular selection and luteinization. These observations support an important role for autocrine/paracrine IGF action modulated by IGFBP-2 and -4 in both follicular growth and differentiation in the porcine ovary.

Animals↗
PubMed2005

An improved method for constructing and selectively silanizing double-barreled, neutral liquid-carrier, ion-selective microelectrodes.

We describe an improved, efficient and reliable method for the vapour-phase silanization of multi-barreled, ion-selective microelectrodes of which the silanized barrel(s) are to be filled with neutral liquid ion-exchanger (LIX). The technique employs a metal manifold to exclusively and simultaneously deliver dimethyldichlorosilane to only the ion-selective barrels of several multi-barreled microelectrodes. Compared to previously published methods the technique requires fewer procedural steps, less handling of individual microelectrodes, improved reproducibility of silanization of the selected microelectrode barrels and employs standard borosilicate tubing rather than the less-conventional theta-type glass. The electrodes remain stable for up to 3 weeks after the silanization procedure. The efficacy of a double-barreled electrode containing a proton ionophore in the ion-selective barrel is demonstrated in situ in the leaf apoplasm of pea (Pisum) and sunflower (Helianthus). Individual leaves were penetrated to depth of approximately 150 microm through the abaxial surface. Microelectrode readings remained stable after multiple impalements without the need for a stabilizing PVC matrix.

Journal Article↗
PubMed1991

Denopamine (beta 1-selective adrenergic receptor agonist) and isoproterenol (non-selective beta-adrenergic receptor agonist) equally increase heart rate and myocardial oxygen consumption in dog heart.

The effects of denopamine (a beta 1-selective adrenergic receptor agonist) and isoproterenol (a non-selective beta-adrenergic receptor agonist) on heart rate, left ventricular contractility, and left ventricular oxygen consumption (VO2) at the same left ventricular volume were compared in excised cross-circulated dog hearts. Denopamine and isoproterenol increased heart rate and VO2 to a comparable extent at a comparably increased contractility. Moreover, the oxygen cost of contractility which quantifies VO2 for excitation-contraction coupling was the same between the two agents. These findings contradict the previously reported smaller increases in heart rate and VO2 by denopamine than by isoproterenol in open-chest dog hearts, which have been mainly attributed to the beta 1-selectivity of denopamine. Our results suggest that in isolated and denervated hearts, the degree of beta 1-selectivity of a beta-agonistic agent does not directly determine the relative potencies of its inotropic and chronotropic effects and the oxygen cost of contractility.

Adrenergic beta-Agonists↗
PubMed2004

Selection for cognitive control: a functional magnetic resonance imaging study on the selection of task-relevant information.

The complex environment we live in makes it necessary to distinguish relevant from irrelevant information constantly and reliably. The aim of the present study was to investigate the neural substrate underlying the selection of task-relevant information. We devised a new paradigm in which participants had to switch between two different tasks that were instructed by task cues. The task cues had a relevant and an irrelevant cue dimension. In congruent trials, both cue dimensions indicated the same task; in incongruent trials, they indicated different tasks; and in neutral trials, only the relevant dimension indicated a task. By comparing trials in which both cue dimensions were informative (congruent and incongruent trials) with trials in which only the relevant dimension was informative (neutral trials), we were able to show that the lateral prefrontal cortex and a region in the intraparietal sulcus are involved in the selection of task-relevant information. Furthermore, the present paradigm allows the influence of the selected task and stimulus dimension to be investigated. No significant influence was found in the prefrontal cortex, indicating that this region serves a very abstract role in the selection of task-relevant information.

Behavior↗
PubMed1980

Insulin release and carbohydrate tolerance in hyperthyroid patients during non-selective or selective beta-1-adrenoceptor blockade.

The insulin release and the glucose disappearance rate (K-value) during an iv glucose tolerance test were evaluated in 20 hyperthyroid patients before and during treatment with either a non-selective (propranolol, n = 10) or a selective (metoprolol, n = 10) beta-1-adrenoceptor blocking agent. Mean daily doses were 240 mg of propranolol and 280 mg of metoprolol, administered four times daily for 10 to 14 days. The insulin increase after glucose injection remained unchanged during treatment with each drug. Fasting blood glucose concentrations and the K-values were not altered during treatment. Sixteen patients were re-investigated 10 to 36 weeks later when euthyroid due to treatment by surgery, thyrostatic drugs or radioiodine. In the euthyroid state mean serum insulin concentrations after the glucose load were not significantly different from the values found when the patients were hyperthyroid. However, mean fasting blood glucose concentrations decreased from 5.5 mmol/l to 5.0 (P less than 0.01) and the mean K-value increased from 1.5 to 2.0 (P less than 0.05) when the patients were euthyroid. It is concluded that short-term treatment of hyperthyroid patients with non-selective or selective beta-1-adrenoceptor blocking agents does not impair the glucose stimulated insulin secretion or the carbohydrate tolerance.

Adrenergic beta-Antagonists↗
PubMed2005

Comparison of selective media for the isolation of Rhodococcus equi and description of a new selective plating medium.

In order to improve the isolation rate of Rhodococcus equi from animals and soil, the efficacy of four previously described selective media (CAZ-NB, M3T, NANAT and TINSDALE) and that of four other media (NC, PNP, TCP and TVP) composed by us was compared and evaluated. Two selective plating media proved to be the best for the isolation of R. equi from contaminated samples. One of them was CAZ-NB containing ceftazidime, novobiocin and cycloheximide, while the other was the newly composed TCP containing trimethoprim, cefoperazone, polymyxin B, cycloheximide and potassium tellurite as selective components. These two media allowed the growth of at least 62-72% of R. equi present in the artificially contaminated samples, and the inhibition of unwanted contaminant bacteria and fungi was satisfactory with both media. TCP medium proved to be superior to CAZ-NB since the colony morphology of R. equi was much more characteristic (shiny, smooth, black colonies 3-5 mm in diameter) on it, and it inhibited the unwanted contaminant bacterial and fungal flora more effectively, especially in the case of faecal and soil samples. Therefore, TCP is recommended as a new, highly selective plating medium for the isolation of R. equi from contaminated samples.

Bacteriological Techniques↗
PubMed2004

Selective and non-selective determination of heavy metal ions in flowing solutions by fast stripping cyclic voltammetry.

A simple and fast stripping voltammetric detection method has been designed for selective and non-selective measurements of heavy metal ions in a flow-injection system. A special computer numerical method is introduced for calculating the analyte signal and noise reduction, where the signal is calculated based on the partial and total charge exchange at electrode surface. For a selective determination, the currents are integrated in the range of the oxidation and reduction of the analyte. For non-selective measurements, the integration range is set for the whole potential scan range (including oxidation and reduction of the Au surface). The time for stripping has been shown to be less than 300 ms. The main advantages of the detection method are as follows: first, removal of oxygen from the measured solution is not required; second, it is sufficiently fast for the determination of heavy metal ions in various chromatographic analysis methods. The limit of detection for tested ions was between 3 x 10(-9) and 6 x 10(-10) M, and the relative standard deviation at 50 ppb Pb2+ was 4.7% for 10 runs.

Journal Article↗
PubMed2005

Preclinical pharmacology of bilastine, a new selective histamine H1 receptor antagonist: receptor selectivity and in vitro antihistaminic activity.

OBJECTIVE: This study aimed to establish the receptor selectivity and antihistaminic activity of bilastine, a new selective antihistamine receptor antagonist. DESIGN AND METHODS: In vitro experiments were conducted using a receptor binding screening panel and guinea-pig and rat tissues. Antihistaminic activity was determined using H1 receptor binding studies and in vitro H1 antagonism studies conducted in guinea-pig tissues and human cell lines. Receptor selectivity was established using a receptor binding screening panel and a receptor antagonism screening conducted in guinea-pig, rat and rabbit tissues. Inhibition of inflammatory mediators was determined through the Schultz-Dale reaction in sensitised guinea-pig ileum. RESULTS: Bilastine binds to histamine H1-receptors as indicated by its displacement of [3H]-pyrilamine from H1-receptors expressed in guinea-pig cerebellum and human embryonic kidney (HEK) cell lines. The studies conducted on guinea-pig smooth muscle demonstrated the capability of bilastine to antagonise H1-receptors. Bilastine is selective for histamine H1-receptors as shown in receptor-binding screening conducted to determine the binding capacity of bilastine to 30 different receptors. The specificity of its H1-receptor antagonistic activity was also demonstrated in a series of in vitro experiments conducted on guinea-pig and rat tissues. The results of these studies confirmed the lack of significant antagonism against serotonin, bradykinin, leukotriene D4, calcium, muscarinic M3-receptors, alpha1-adrenoceptors, beta2-adrenoceptors, and H2- and H3-receptors. The results of the in vitro Schultz-Dale reaction demonstrated that bilastine also has anti-inflammatory activity. CONCLUSIONS: These preclinical studies provide evidence that bilastine has H1- antihistamine activity, with high specificity for H1-receptors, and poor or no affinity for other receptors. Bilastine has also been shown to have anti-inflammatory properties.

Animals↗
PubMedDate not supplied

[Selection and pharmacological characterisation of Procoralan, a selective inhibitor of the pacemaker If current].

The screening of a series of benzocycloalkane derivatives led to the selection of Procoralan (ivabradine), the first selective inhibitor of the depolarizing If (funny) current of the sinus node, for the treament of myocardial ischaemia. In vitro, this compound reduces the spontaneous beating rate of isolated right rat atria and the firing rate of the action potential of rabbit sinus node preparations. This effect is explained by a reduction in the diastolic depolarisation slope of the action potential and underlies a selective inhibition of the pacemaker If current. In vivo, it induces a selective reduction in heart rate both at rest and during exercise. It preserves myocardial contractility, atrioventricular conduction and ventricular repolarisation duration. Ivabradine exerts a similar anti-ischaemic activity in exercise-induced myocardial ischaemia in pigs to that of a beta-blocker and, furthermore, it limits to a greater extent ischaemic myocardial contractile dysfunction.

Animals↗
PubMed2002

Selective entorhinal and nonselective cortical-hippocampal region lesions, but not selective hippocampal lesions, disrupt learned irrelevance in rabbit eyeblink conditioning.

Prior experiments, as well as computational models, have implicated the hippocampal region in mediating the influence of nonreinforced stimulus preexposure on subsequent learning. Learned irrelevance (LIRR) is a preexposure task in which uncorrelated preexposures to the conditioned stimulus (CS) and the unconditioned stimulus (US) produce a retardation of subsequent CS-US conditioning. In the work presented here, we report the results of tests of LIRR in eyeblink conditioning in rabbits with sham lesions, nonselective cortical-hippocampal region lesions, selective hippocampal lesions, and selective entorhinal lesions. Sham-lesioned rabbits that had been preexposed to the CS and the US exhibited slower acquisition of conditioned response, as compared with context-preexposed controls. Nonselective cotical-hippocampal region lesions disrupted LIRR, whereas selective hippocampal lesions had no detrimental effect on LIRR. Selective entorhinal lesions disrupted LIRR. These findings fit other recent empirical findings and theoretical predictions that some classical conditioning tasks previously thought to depend on the hippocampus depend, rather, on the entorhinal cortex.

Animals↗
PubMed1992

T-helper functions in lines of mice selected for high or low antibody production (Selection III): modulation by anti-CD4+ monoclonal antibody.

T-helper function was evaluated in mice genetically selected for high (H) or low (L) antibody (Ab) responsiveness to Salmonella flagellar antigen (Ag) (Selection III). In this Selection as opposed to what was demonstrated in Selections I, II and IVA, the interline difference was not proven to be based upon the modification of Ag processing and presentation at macrophage level. CD4+/CD8+ lymph node ratio is similar in HIII and LIII mice, both lines being equally susceptible to in vivo depletion of CD4+ T cells by GK 1-5 monoclonal antibody (mAb) treatment. Nevertheless, the Ab responsiveness of the two lines was differently modulated by GK 1-5 mAb: the inhibition of Ab responses to various Ag required lower mAb doses and was long lasting in LIII as compared to the transient effect of higher mAb doses observed in HIII. LIII mice were also refractory to Salmonella-induced reversion of GK 1-5 mAb inhibition. Moreover, in vitro specific I proliferation was constantly lower in LIII, though its IL-2 production was unexpectedly similar to that of HIII T cells. Results of in vivo and in vitro experiments are thus consistent with a defective response of T-helper cells to immunogenic challenge in LIII mice.

Animals↗
PubMed2006

[Effects of selective and non-selective cyclooxygenase-2 inhibitor on the growth of colon cancer cells].

OBJECTIVE: To evaluate the effects of selective and non-selective cyclooxygenase-2 on the growth and apoptosis of colon cancer cell lines in vitro. METHODS: The proliferation of colon cancer cells was determined by MTT assay, and the cell cycle progression was analyzed by flow cytometric assay. Annexin V/PI staining in combination with flow cytometric assay was used to detect apoptosis induced by NSAIDs. RESULTS: It was found that celecoxib, meloxicam and aspirin could inhibit the growth of HT-29 or SW480 cell and showed a concentration dependent pattern. COX-2 protein was expressed in HT-29 and LS174-T, but not in SW480 cells. In addition, PCNA levels in both HT-29 cell and SW480 cells were reduced by aspirin and celecoxib. Both aspirin (10 mmol/ L) and celecoxib (50 micromol/L) induced apoptosis of HT-29 and SW480 colon cancer cells, the apoptosis rates were 4.8%, 17.7% and 5.1%, 20.4% respectively. CONCLUSION: Both COX-2 selective and non-selective inhibitors can potentially inhibit the growth of colon cell lines and such inhibitory effect on COX-2 negative colon cancer cells is also evident.

Apoptosis↗
PubMedDate not supplied

[Portal perfusion following selective and non-selective diversions in portal hypertension].

Derivative procedures to treat portal hypertension deprive the liver of the portal flow. Selective procedures maintain portal perfusion to the liver, but, nevertheless, have a slow tendency to lost it; low diameter portosystemic shunts partially maintain also portal flow. A study to compare postoperative portal blood flow was designed. In twenty three patients, twelve of them with a distal spleno renal shunt (DSRS) and eleven with a low diameter mesocaval interposition shunt (12 mm. Ring Reinformaced GORE-TEX) (LDMCI) a portal blood flow determination using computerized liver perfusion scintigraphy was performed in the postoperative period. In the DSRS group, no case of encephalopathy or rebleeding was recorded. All shunts were patent. Preoperative liver perfusion scintigraphy (LPS) showed a portal perfusion index (PPI) of 38.26% (range 25.2 to 62%) and in the postoperative period a PPI of 13.7 (range 0.8 to 31.7%). In the LDMCI, one case of encephalopathy (9%) and one case of rebleeding (9%) was recorded. LPS showed a preoperative PPI of 28.13% (range 12.4 to 55.7%) and in the postoperative period a PPI of 10.57% (range 0.8 to 20.4%). In the postoperative period, either with a selective or no selective shunt, a reduction in portal blood flow to the liver is to be expected, more apparent in patients with a total shunt. LDMCI control effectively the recurrence of bleeding esophageal varices, maintaining portal perfusion, too. Thus, LDMCI constitutes and excellent alternative for patients in whom a selective shunt is not possible to perform or indicated, particularly in those with portal hypertension secondary to alcoholic liver cirrhosis.

Humans↗
PubMed1989

Selective per-operative cholangiography and scoring method for selection.

A prospective clinical study was undertaken over a period of 3 years on a series of 210 consecutive cases of gall stones to review a selective policy for per-operative cholangiography (PC). All patients had elective cholecystectomy and routine PC. A scoring method (SM) based on pre and per-operative surgical criteria was adopted to determine the necessity of PC before this was attempted. The study revealed that PC was indicated in 64 cases (30.5%) only. Of these 64 patients 20 had abnormal cholangiograms of which 18 proved positive on exploration. There were two false positive results (0.95%) of PC but no false negative result. Of 146 patients (69.5%) not clinically indicated for routine PC, 145 had normal cholangiograms and one had a small (5 mm diameter) silent stone (0.47%) in the Common Bile Duct (CBD). The scoring method failed to predict this case of silent stone. PC was technically unsatisfactory in 4 cases (1.9%). Thus by adopting the selective policy X-rays could have been avoided in 69.5% cases in which only a small silent stone would have been overlooked. However, this stone could have passed into the duodenum spontaneously or else it could have been removed by endoscopic sphincterotomy had it caused any symptoms. It is concluded that routine PC is not always necessary, a selective policy may be preferred and a scoring method may be used as a guide for selection of the cases.

Adult↗