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R Schreiber

Publications and source records attributed to R Schreiber.

At least 91 records · Page 5Linked to original sources

Long-term alcohol self-administration and alcohol withdrawal differentially modulate microtubule-associated protein 2 (MAP2) gene expression in the rat brain.

Chronic alcohol intoxication is known to produce neuronal degeneration in the central and peripheral nervous system of experimental animals and of humans. It is suggested that various components of the cytoskeleton undergo profound changes following chronic alcohol use and misuse. Here we studied the expression of the neuronal cytoskeletal microtubule-associated protein 2 (MAP2) following long-term alcohol consumption and subsequent alcohol withdrawal. Alcohol-preferring AA (Alko Alkohol) rats with a high voluntary alcohol consumption for a period of 16 months were compared with age-matched control rats without prior experience with alcohol. For comparison, in a second experiment, heterogeneous Wistar rats that also had voluntary access to alcohol for 8 months were examined following alcohol consumption and withdrawal. In situ hybridization and subsequent dot blot and Northern blot analysis for further quantification revealed that chronically alcoholized animals exhibit markedly decreased MAP2 mRNA levels in several parts of the extrapyramidal system (mainly in the caudate putamen, the substantia nigra pars compacta and the globus pallidus), the mesolimbic system, in several hypothalamic nuclei and in the nucleus inferior colliculus. Other areas such as the hippocampus, frontoparietal cortex and cerebellum were less affected by chronic alcohol intake, however, in these regions the MAP2 mRNA levels were increased during alcohol withdrawal. These results suggest that long-term alcohol self-administration affects central neurons involved in motor control via the influence on the integrity of the cytoskeleton and may thus induce motor dysfunction.

Alcohol Withdrawal Delirium↗

The amiloride-inhibitable Na+ conductance is reduced by the cystic fibrosis transmembrane conductance regulator in normal but not in cystic fibrosis airways.

Cystic fibrosis (CF) airway cells, besides their well-known defect in cAMP-dependent Cl- conductance, are characterized by an enhanced Na+ conductance. In this study we have examined the Na+ conductance in human respiratory tract by measuring transepithelial voltage and resistance (Vte, Rte) and by assessing membrane voltages (Vm) of freshly isolated airway epithelial cells from CF and non-CF patients. Basal amiloride inhibitable (10 micromol/liter) equivalent short circuit current (Isc = Vte/Rte) was significantly increased in CF compared with non-CF tissues. After stimulation by forskolin (10 micromol/liter) a significant depolarization of Vm corresponding to the cAMP-dependent activation of a Cl- conductance was observed in non-CF but not in CF airway cells. In non-CF tissue but not in CF tissue the effects of amiloride and N-methyl-D-glucamine on Vm were attenuated in the presence of forskolin. Also the amiloride-inhibitable Isc was significantly reduced by forskolin (1 micromol/liter) and isobutylmethylxanthine (IBMX; 100 micromol/liter) only in non-CF tissue. We conclude that cystic fibrosis transmembrane conductance regulator acts as a downregulator of epithelial Na+ channels in human airways. This downregulation of epithelial Na+ channels is absent in CF airways, leading to hyperabsorption and to the characteristic increase in mucus viscosity.

1-Methyl-3-isobutylxanthine↗

The role of 5-HT receptor subtypes in the anxiolytic effects of selective serotonin reuptake inhibitors in the rat ultrasonic vocalization test.

We evaluated whether the anxiolytic effects of selective serotonin reuptake inhibitors (SSRIs) in the rat ultrasonic vocalization (USV) test are preferentially mediated by (indirect) activation of 5-HT1A, 5-HT1B/1D, 5-HT2A, 5-HT3 or 5-HT4 receptors. The SSRIs, paroxetine (ED50 in mg/kg, IP: 6.9), citalopram (6.5), fluvoxamine (11.7) and fluoxetine (> 30), dose dependently reduced shock-induced USV. The effects of paroxetine (3.0 mg/kg, IP) were not blocked by the selective 5-HT1A receptor antagonist, WAY-100635 (3.0 mg/kg, IP), the 5-HT1B/1D receptor antagonist, GR 127935 (30 mg/kg, IP), the nonselective 5-HT2A receptor antagonists, ritanserin (3.0 mg/kg, IP) and ketanserin (1.0 mg/kg, IP), the 5-HT3 receptor antagonist, ondansetron (0.1 mg/kg, IP), or the 5-HT4 receptor antagonist, GR 125487D (3.0 mg/kg, SC). In contrast, the selective 5-HT2A receptor antagonist, MDL 100,907 (0.1 mg/kg, IP), completely prevented the paroxetine-induced reduction of USV. Under similar conditions, WAY-100635 blocked the anxiolytic-like effects of the selective 5-HT1A receptor agonist, 8-OH-DPAT [(+/-)-8-hydroxy-2-(di-n-propylamino)tetralin, 1.0 mg/kg, IP], and ritanserin, ketanserin, and MDL 100,907 blocked the anxiolytic-like effects of the mixed 5-HT2A/2C receptor agonist, DOI [1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, 3.0 mg/kg, IP]. WAY-100635 (1.0 mg/kg, IP) in combination with ritanserin (3.0 mg/kg, IP), but not ondansetron (0.1 mg/kg, IP), GR 125487D (3.0 mg/kg, SC), or GR 127935 (30 mg/kg, IP), attenuated the USV reducing effects of paroxetine. Although the results suggest that selective stimulation of 5-HT1A and 5-HT2A receptors produces a decrease of USV, we postulate that only 5-HT2A receptors play a pivotal role in the effects of SSRIs in this model of anxiety.

Animals↗

Meconium stained amniotic fluid in preterm delivery is an independent risk factor for perinatal complications.

OBJECTIVE: To determine the prevalence and clinical significance of meconium stained amniotic fluid (MSAF) in women with preterm delivery. STUDY DESIGN: The study population consisted of consecutive patients who arrived with intact membranes and delivered preterm, singleton neonates at the Soroka Medical Center between 1 January 1985 and 31 December 1995. Only vertex presentation was included. Antepartum death was excluded from the study. Patients were classified according to the color of amniotic fluid into two groups: MSAF and clear amniotic fluid. Maternal puerperal complications were defined in our study as the presence of at least one of the next variables: clinical chorioamnionitis; major puerperal infection including endometritis, cesarean section or postpartum hemorrhage. Perinatal complications were defined in our study as: (1) intrapartum death (IPD) or postpartum death (PPD); (2) one or more of the following: 1-min Apgar score <3, 5-min Apgar score <7 or small for gestational age. Rates of perinatal complications were assessed at: (1) 24-27 weeks; (2) 28-31 weeks; (3) 32-36 weeks. Logistic regression was used to investigate the relationship of MSAF to perinatal complications and maternal morbidity in a multivariate model. RESULTS: During the study period, a total of 96 566 deliveries occurred in our institution and 4872 (5.0%) deliveries were preterm. Among the women delivering preterm meeting eligibility criteria, 276 (5.7%) women had intrapartum MSAF. A higher rate of IPD and PPD was observed only between 32 and 36 weeks' gestation in patients with MSAF in comparison with patients with clear amniotic fluid [6.1% (14/230) vs. 2.1% (85/4045), respectively, P=0.0001]. A statistically significant higher rate of perinatal complications was found between 28 and 31 weeks' gestation, and even a higher rate was noted between 32 and 36 weeks' gestation in the MSAF group in comparison with patients with clear amniotic fluid [51% (18/35) vs. 27.2% (93/341), respectively, P=0.003; 20% (46/230) vs. 9.8% (396/4045), respectively, P=0.0004]. CONCLUSIONS: (1) MSAF is an independent risk factor for perinatal complications in preterm deliveries (OR=1.73, CI: 1.057-2.43, P=0.001; OR=2.35, CI:1.34-4.12, P=0.002, respectively). (2) MSAF was not found to be an independent risk factor for maternal morbidity.

Adult↗

The contexts for managing depression and its stigma among black West Indian Canadian women.

There is a paucity of literature available to assist nurses and other care providers in knowing how to meet the needs of depressed women from non-dominant cultural backgrounds. To begin to address this need, we conducted a grounded theory study on black West Indian Canadian Women's strategies for managing depression. We discovered a basic social process, Being Strong, that the women used to manage or ameliorate depression. Being strong occurs within the overlapping areas of three social contexts: the cultural stigma of depression, male-female roles and relationships, and belief in Christian doctrine. These contexts are located against a backdrop of visible minority status within a eurocentric society. This socio-cultural contextual material provides the setting within which black West Indian Canadian women live and make decisions. In this article, we present findings related to the social and cultural aspects of the women's situation.

Adaptation, Psychological↗

No evidence for direct activation of the cystic fibrosis transmembrane conductance regulator by 8-cyclopentyl-1,3-dipropylxanthine.

8-Cyclopentyl-1,3-dipropylxanthine (CPX) is a selective A1-adenosine receptor antagonist which has been reported to activate Cl- efflux at very low concentrations in cells carrying the cystic fibrosis (CF) defect, but not in cells expressing the wild-type form of the CF transmembrane conductance regulator (CFTR). CPX was suggested as a new therapeutic drug for the treatment of CF. In the present study, we examined the effects of CPX on various types of recombinant cells (Xenopus oocytes, Chinese hamster ovary cells, CF tracheal cells) and native non-CF and CF respiratory epithelial cells. CPX did not activate a whole-cell conductance when applied at concentrations ranging from 1 nmol/l to 100 micromol/l in oocytes injected with water or expressing either wild-type CFTR or mutant deltaF508-CFTR. Correspondingly, CPX (10 micromol/l) did not activate whole-cell conductance in non-CF or CF respiratory epithelial cells and Chinese hamster ovary cells expressing either wild-type CFTR or deltaF508-CFTR. Instead, CPX depolarized Vm by inhibition of a K+ conductance in CF respiratory epithelial cells. At 10 micromol/l CPX marginally decreased intracellular pH in respiratory epithelial cells, independent of expression of wild-type CFTR or mutant CFTR. According to these data, CPX-induced 36Cl efflux reported in previous studies cannot be attributed to direct activation of deltaF508-CFTR Cl- conductance and is probably related to the CPX-induced changes in intracellular pH.

Animals↗

Imaging ourselves: nurses' metaphors of practice.

Metaphors are vivid, expressive tools popularly used in everyday conversations. The familiarity of metaphors combined with their capacity for generating meaning make the metaphor a powerful heuristic device for effecting nursing discoveries and pedagogical shifts. Exploring nursing metaphors can provide opportunities to develop new understandings of nursing and challenge metaphorical images that may be constraining and/or obscuring significant elements of holistic nursing practice. A research study that examined the metaphorical images of practicing nurses uncovered a wide variety of images. The thematic analysis of the metaphorical descriptions illuminated four major themes: (a) the character of nursing work, (b) power and empowerment, (c) nursing as a growth process, and (d) the relational nature of nursing. Nurses' metaphorical images provide a window into the complexities and ambiguities within nursing practice. The images highlight the significance of social and organizational constraints that influence how nurses take up their practice, the ways in which nurses feel unable to practice holistically, and the struggles nurses encounter when they try.

Adult↗

Role of 5-HT1B, 5-HT2A and 5-HT2C receptors in the generalization of 5-HT receptor agonists to the ethanol cue in the rat.

Although accumulating evidence suggests that serotonergic drugs are able to substitute for the ethanol (EtOH) cue in rats, it is still unclear which 5-HT receptor subtypes are responsible for this phenomenon, and whether these receptors are critically involved in the EtOH cue. In the present study, rats were trained to discriminate EtOH (1000 mg/kg, i.p., t-15 min) from saline in a two-lever food-reinforced procedure, and it was investigated to which extent serotonergic compounds with a certain level of specificity for either 5-HT1B, 5-HT2A or 5-HT2C receptors generalized to the EtOH cue. Subsequently, the involvement of these receptor subtypes was ascertained by the use of selected 5-HT receptor antagonists. The 5-HT1B receptor agonist CP 94,253 (0.3-5 mg/kg, i.p.) and the mixed 5-HT(2C/1B) receptor agonist mCPP (0.1-1 mg/kg, i.p.), but not the preferential 5-HT2A receptor agonist DOI (0.3-1 mg/kg, i.p.), completely generalized to the EtOH cue. Complete generalization of the former two compounds coincided with a decrease in response rate. In antagonism studies, it was shown that the 5-HT1B receptor antagonist GR 127935 (10 mg/kg, i.p.) completely blocked generalization of CP 94,253 to the EtOH cue, suggesting that stimulation of 5-HT1B receptors produces discriminative stimulus effects which are similar to those of EtOH. GR 127935 (10 mg/kg, i.p.), as well as the mixed 5-HT(1B/2C) receptor antagonist metergoline (1 mg/kg, i.p.), and the 5-HT2C receptor antagonist SB 206,553 (1 mg/kg, i.p.) completely blocked generalization of mCPP to the EtOH cue. This suggests that 5-HT1B and 5-HT2C receptors are required for the generalization of mCPP to the EtOH cue. The present findings indicate that activation of 5-HT1B and 5-HT2C, but not of 5-HT2A receptors, mimics the EtOH cue. However, the finding that neither metergoline, nor the 5-HT2A receptor antagonist MDL 100,907 blocked the EtOH cue, suggests that these receptors play only a minor role in the discriminative stimulus effects of a moderately low dose of EtOH.

Alcohol Drinking↗

S 16924 ((R)-2-[1-[2-(2,3-dihydro-benzo[1,4] dioxin-5-yloxy)-ethyl]-pyrrolidin-3yl]-1-(4-fluoro-phenyl)-ethanone), a novel, potential antipsychotic with marked serotonin (5-HT)1A agonist properties: II. Functional profile in comparison to clozapine and haloperidol.

S 16924 antagonized locomotion provoked by dizocilpine and cocaine, reduced conditioned avoidance responses and blocked climbing elicited by apomorphine, models predictive of control of the positive symptoms of schizophrenia: its median inhibitory dose (ID)50 was 0.96 mg/kg, s.c. vs. 1.91 for clozapine and 0.05 for haloperidol. Rotation elicited in unilateral, substantia nigra-lesioned rats by the D1 agonist, SKF 38393, and by the D2 agonist, quinpirole, was blocked equipotently by S 16924 (0.8 and 1. 7) and clozapine (0.6 and 2.0), whereas haloperidol preferentially blocked quinpirole (0.02) vs. SKF 38393 (1.8). S 16924 more potently inhibited the head-twitches elicited by 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and the locomotion provoked by phencyclidine than it inhibited the locomotion elicited by amphetamine (ID50s = 0.15 and 0.02 vs. 2.4). Clozapine showed a similar preference (0.04 and 0.07 vs. 8.6), but not haloperidol (0. 07 and 0.08 vs. 0.04). The discriminative stimulus (DS) properties of DOI were also blocked by S 16924 (ID50 = 0.17) and clozapine (0. 05) but not by haloperidol (>0.16). S 16924 fully (100%) generalized [effective dose (ED)50 = 0.7] to a clozapine DS and clozapine (0.23) fully generalized to a S 16924 DS whereas haloperidol (>/=0.08) only partially generalized (</=50%) to their DS in each case. Power spectra analysis of electroencephalograms from frontal cortex showed that both S 16924 (2.0) and clozapine (5.0) reinforced frequencies in the 7 to 8 Hz range whereas haloperidol (0.5) preferentially reinforced frequencies in the 10 to 14 Hz range. In a model of perturbation of cognitive-attentional function, significant latent inhibition was obtained with S 16924 (0.08) and clozapine (0.16), but not haloperidol (0.0063 and 0.04): higher doses of S 16924 (2.5), clozapine (5.0) and haloperidol (0.1) all blocked disruption of latent inhibition by amphetamine (1.5). Catalepsy was provoked by haloperidol (0.04-0.63) but not by S 16924 (>/=80.0) or clozapine (>/=80.0). Further, S 16924 (ID50 = 3.2) and clozapine (5.5) inhibited induction of catalepsy by haloperidol. This action of S 16924 was abolished by the 5-HT1A receptor antagonist, WAY 100,635 (0.16), which less markedly attenuated the anticataleptic action of clozapine. Further, although gnawing elicited by methylphenidate was inhibited by S 16924 (ID50 = 8.4), clozapine (19.6) and haloperidol (0.04), only the action of S 16924 was blocked by WAY 100,635 (0.16). Haloperidol potently (0.01-0.16, approximately 24-fold) increased prolactin levels whereas they were less markedly affected by S 16924 (2.5-40.0, 4-fold) and clozapine (10.0-40.0, 3-fold). Clozapine displayed high affinity at cloned, human, muscarinic (M1) and native, histamine (H1) receptors (Kis = 4.6 and 5.4 nM, respectively), whereas S 16924 (>1000 and 158) and haloperidol (>1000 and 453) displayed low affinity. In conclusion, S 16924 displays a profile of activity in diverse models of potential antipsychotic and extrapyramidal properties similar to that of clozapine and different to that of haloperidol. In particular, reflecting its partial agonist actions at 5-HT1A receptors, S 16924 inhibits rather than induces catalepsy in rats. However, in contrast to clozapine, S 16924 displays only low affinity for muscarinic and histaminic receptors.

Amphetamines↗

S 18126 ([2-[4-(2,3-dihydrobenzo[1,4]dioxin-6-yl)piperazin-1-yl methyl]indan-2-yl]), a potent, selective and competitive antagonist at dopamine D4 receptors: an in vitro and in vivo comparison with L 745,870 (3-(4-[4-chlorophenyl]piperazin-1-yl)methyl-1H-pyrrolo[2, 3b]pyridine) and raclopride.

The novel benzoindane S 18126 possessed > 100-fold higher affinity at cloned, human (h) D4 (Ki = 2.4 nM) vs. hD2 (738 nM), hD3 (2840 nM), hD1 (> 3000 nM) and hD5 (> 3000 nM) receptors and about 50 other sites, except sigma1 receptors (1.6 nM). L 745,870 similarly showed selectivity for hD4 (2.5 nM) vs. hD2 (905 nM) and hD3 (> 3000 nM) receptors. In contrast, raclopride displayed low affinity at hD4 (> 3000 nM) vs. hD2 (1.1 nM) and hD3 receptors (1.4 nM). Stimulation of [35S]-GTPgammaS binding at hD4 receptors by dopamine (DA) was blocked by S 18126 and L 745,870 with Kb values of 2.2 and 1.0 nM, respectively, whereas raclopride (> 1000 nM) was inactive. In contrast, raclopride inhibited stimulation of [35S]-GTPgammaS binding at hD2 sites by DA with a Kb of 1.4 nM, whereas S 18126 (> 1000 nM) and L 745,870 (> 1000 nM) were inactive. As concerns presynaptic dopaminergic receptors, raclopride (0.01-0.05 mg/kg s.c. ) markedly enhanced DA synthesis in mesocortical, mesolimbic and nigrostriatal dopaminergic pathways. In contrast, even high doses (2. 5-40.0 mg/kg s.c.) of S 18126 and L 745,870 were only weakly active. Similarly, raclopride (0.016 mg/kg i.v.) abolished inhibition of the firing rate of ventrotegmental dopaminergic neurons by apomorphine, whereas even high doses (0.5 mg/kg i.v.) of S 18126 and L 745,870 were only weakly active. As regards postsynaptic dopaminergic receptors, raclopride potently (0.01-0.3 mg/kg s.c.) reduced rotation elicited by quinpirole in rats with unilateral lesions of the substantia nigra, antagonized induction of hypothermia by PD 128, 907, blocked amphetamine-induced hyperlocomotion and was effective in six further models of potential antipsychotic activity. In contrast, S 18126 and L 745,870 were only weakly active in these models (5.0-> 40.0 mg/kg s.c.). In six models of extrapyramidal and motor symptoms, such as induction of catalepsy, raclopride was likewise potently active (0.01-2.0 mg/kg s.c.) whereas S 18126 and L 745,870 were only weakly active (10.0-80.0 mg/kg s.c.). In freely moving rats, raclopride (0.16 mg/kg s.c.) increased levels of DA by + 55% in dialysates of the frontal cortex. However, it also increased levels of DA in the accumbens and striatum by 70% and 75%, respectively. In contrast to raclopride, at a dose of 0.16 mg/kg s.c. , neither S 18126 nor L 745,870 modified frontal cortex levels of DA. However, at a high dose (40.0 mg/kg s.c.), S 18126 increased dialysate levels of DA (+ 85%) and noradrenaline (+ 100%), but not serotonin (+ 10%), in frontal cortex without affecting DA levels in accumbens (+ 10%) and striatum (+ 10%). In conclusion, S 18126 and L 745,870 behave as potent and selective antagonists of cloned, hD4 vs. other dopaminergic receptor types in vitro. However, their in vivo effects at high doses probably reflect residual antagonist actions at D2 (or D3) receptors. Selective blockade of D4 receptors was thus associated neither with a modification of dopaminergic transmission nor with antipsychotic (antiproductive) or extrapyramidal properties. The functional effects of selective D4 receptor blockade remain to be established.

Animals↗

Partial interferon-gamma receptor 1 deficiency in a child with tuberculoid bacillus Calmette-Guérin infection and a sibling with clinical tuberculosis.

Complete interferon-gamma receptor 1 (IFNgammaR1) deficiency has been identified previously as a cause of fatal bacillus Calmette-Guérin (BCG) infection with lepromatoid granulomas, and of disseminated nontuberculous mycobacterial (NTM) infection in children who had not been inoculated with BCG. We report here a kindred with partial IFNgammaR1 deficiency: one child afflicted by disseminated BCG infection with tuberculoid granulomas, and a sibling, who had not been inoculated previously with BCG, with clinical tuberculosis. Both responded to antimicrobials and are currently well without prophylactic therapy. Impaired response to IFN-gamma was documented in B cells by signal transducer and activator of transcription 1 nuclear translocation, in fibroblasts by cell surface HLA class II induction, and in monocytes by cell surface CD64 induction and TNF-alpha secretion. Whereas cells from healthy children responded to even low IFN-gamma concentrations (10 IU/ml), and cells from a child with complete IFNgammaR1 deficiency did not respond to even high IFN-gamma concentrations (10,000 IU/ml), cells from the two siblings did not respond to low or intermediate concentrations, yet responded to high IFN-gamma concentrations. A homozygous missense IFNgR1 mutation was identified, and its pathogenic role was ascertained by molecular complementation. Thus, whereas complete IFNgammaR1 deficiency in previously identified kindreds caused fatal lepromatoid BCG infection and disseminated NTM infection, partial IFNgammaR1 deficiency in this kindred caused curable tuberculoid BCG infection and clinical tuberculosis.

Adolescent↗

Inhibition of epithelial Na+ currents by intracellular domains of the cystic fibrosis transmembrane conductance regulator.

Cystic fibrosis is characterized by an impaired cyclic adenosine 3,5-monophosphate (cAMP) activated Cl- conductance in parallel with an enhanced amiloride sensitive Na+ conductance (ENaC) of the respiratory epithelium. Very recently, acute downregulation of ENaC by the cystic fibrosis transmembrane conductance regulator (CFTR) was demonstrated in several studies. The mechanism, however, by which CFTR exerts its inhibitory effect on ENaC remains obscure. We demonstrate that cytosolic domains of human CFTR are sufficient to induce inhibition of rat epithelial Na+ currents (rENaC) when coexpressed in Xenopus oocytes and stimulated with 3-isobutyl-1-methylxanthine (IBMX). Moreover, mutations of CFTR, which occur in cystic fibrosis, abolish CFTR-dependent downregulation of rENaC. Yeast two hybrid analysis of CFTR domains and rENaC subunits suggest direct interaction between the proteins. Enhanced Na+ transport as found in the airways of cystic fibrosis patients is probably due to a lack of CFTR dependent downregulation of ENaC.

1-Methyl-3-isobutylxanthine↗

Substitution of the selective serotonin reuptake inhibitors fluoxetine and paroxetine for the discriminative stimulus effects of ethanol in rats.

Rats trained to discriminate ethanol (EtOH, 1 g/kg IP) from saline in a two-lever procedure completely generalized to the selective serotonin reuptake inhibitors (SSRIs) fluoxetine and paroxetine. Substitution of fluoxetine was completely blocked by the selective 5-HT2A receptor antagonist MDL 100,907 and not affected by the selective 5-HT1A receptor antagonist WAY-100635. It is suggested that the previously reported effectiveness of SSRIs in reducing EtOH consumption could be based on similarities in discriminative stimulus effects of SSRIs and EtOH. Stimulation of 5-HT2A receptors may underlie these stimulus similarities and contribute to the EtOH intake-reducing effects of SSRIs.

Animals↗