Changes in the brain serotonin satiety system in transgenic rats lacking brain angiotensinogen

In transgenic rats, TGR(ASrAOGEN)680, with reduced glial expression of angiotensinogen, changes in brain angiotensinogen are associated with reductions in serotonin (5-HT) content and/or 5-HT metabolism as determined in various brain regions, including the hypothalamus. These rats showed an anxious phenotype upon a first behavioural screen. The present study aimed to extend the search for functional consequences of changes in brain 5-HT with respect to feeding behaviour in these transgenic rats. In feeding experiments, rats were treated with the anorectic drug fenfluramine to probe for functional changes in the serotonergic satiety system. Fenfluramine (0.3 mg/kg, i.p.) reduced food intake in TGR(ASrAOGEN)680 rats whereas the minimal effective dose in wild-type rats was 3 mg/kg, i.p. Although, in the cortex, no differences were apparent in the expression of serotonin 5-HT(1A), 5-HT(1B), 5-HT(2C) receptor and 5-HT transporter mRNAs between TGR(ASrAOGEN)680 and wild-type rats, the expression of mRNAs for the 5-HT(2C) receptor and 5-HT transporter mRNA were significantly higher in the hypothalamus of TGR(ASrAOGEN)680 rats compared to wild-type rats. No differences were found in the mRNA levels for hypothalamic 5-HT(1A) and 5-HT(1B) receptors between TGR(ASrAOGEN)680 and wild-type rats. Taken together, these findings suggest that the transgenic effect on the brain 5-HT system is paralleled by functional changes of the serotonergic feeding system.

Plasticity and impact of the central renin–angiotensin system during development of ethanol dependence

Pharmacological and genetic interference with the renin-angiotensin system (RAS) seems to alter voluntary ethanol consumption. However, understanding the influence of the RAS on ethanol dependence and its treatment requires modeling the neuroadaptations that occur with prolonged exposure to ethanol. Increased ethanol consumption was induced in rats through repeated cycles of intoxication and withdrawal. Expression of angiotensinogen, angiotensin-converting enzyme, and the angiotensin II receptor, AT1a, was examined by quantitative reverse transcription polymerase chain reaction. Increased ethanol consumption after a history of dependence was associated with increased angiotensinogen expression in medial prefrontal cortex but not in nucleus accumbens or amygdala. Increased angiotensinogen expression also demonstrates that the astroglia is an integral part of the plasticity underlying the development of dependence. The effects of low central RAS activity on increased ethanol consumption were investigated using either spirapril, a blood-brain barrier-penetrating inhibitor of angiotensin-converting enzyme, or transgenic rats (TGR(ASrAOGEN)680) with reduced central angiotensinogen expression. Spirapril reduced ethanol intake in dependent rats compared to controls. After induction of dependence, TGR(ASrAOGEN)680 rats had increased ethanol consumption but to a lesser degree than Wistar rats with the same history of dependence. These data suggest that the central RAS is sensitized in its modulatory control of ethanol consumption in the dependent state, but pharmacological or genetic blockade of the system appears to be insufficient to halt the progression of dependence.

Roles of the kallikrein/kinin system in the adaptive immune system

This review deals with the effects of kinins, a family of octa- to decapeptides structurally related to bradykinin (BK), in adaptive immune responses. Herein, we discuss the experimental evidence that kinins may exert influence on multiple players of the immune system (i.e. macrophages, dendritic cells, T and B lymphocytes), and modulate the activation, proliferation, migration and effector functions of these cells. We also give an overview of the possible impact of kinins in human autoimmune diseases and corresponding animal models, with special emphasis on autoimmune neuroinflammation and arthritis. These studies indicate a possible immunomodulatory capacity of kinins beyond our current knowledge of kinin actions regarding the vascular system, and thus the way towards future therapeutic approaches.

[Technical aspects of intraoperative assessment of treatment progress in laser lithotripsy]

BACKGROUND

During laser-induced fragmentation, differences in assessing the intraoperative results can depend on the individual characteristics of the laser system used.

METHODS

Laser parameters like pulse energy and repetition rate, the penetration depth in silicon tissue, and the laser beam width on photographic paper were determined for three different clinical laser systems.

RESULTS

Pulse energy and repetition rate were subject to variations depending on the laser system employed. Significant differences between the three devices were found for penetration depth in silicon and interaction.

CONCLUSIONS

Further investigations to ascertain the ablation threshold and fragmentation rate can be based on these findings. Intraoperative assessment of the lithotripsy results should take technical aspects of the laser equipment, stone consistency, and the surgeon's experience into consideration.

Influence of human tryptophan hydroxylase 2 N- and C-terminus on enzymatic activity and oligomerization

Tryptophan hydroxylase (TPH) catalyses the first and rate limiting step in the biosynthesis of the neurotransmitter serotonin. There are two TPH isoenzymes in humans, encoded by two different genes: TPH1 and the recently described TPH2. We have expressed both human enzymes and various deletion mutants of TPH2 (DeltaN44, DeltaC17, DeltaC19, DeltaC51) in COS7 cells. TPH1 and 2 displayed different kinetic properties with a lower K(m) value of TPH1. Removal of 44 amino acids from the N-terminus of TPH2 resulted in a 3-4-fold increased V(max), which indicates a strong inhibitory function of this part on the enzymes activity. TPH1 and 2 were able to form homooligomers and also heterooligomers with each other. The different deletion mutants (DeltaC17, DeltaC19 and DeltaC51), which lack the putative C-terminal leucine zipper tetramerization domain, existed as monomeric enzymes. While short deletions (DeltaC17 and DeltaC19) hardly changed V(max) values, the DeltaC51 mutant lost 99% of TPH activity. These data identify a region between the C-terminal oligomerization domain and the catalytic domain, which is indispensable for TPH2 activity.

Adverse effects of drug therapies on male and female sexual function

Sexual dysfunctions (SD) are adverse effects of common drug therapies that have rarely been considered in investigations so far. Possibly it is barely known that many widespread and frequently prescribed medications and drug therapies can have significant impact on vascular and nerval processes as well as on endocrinologic and psychoneuroendocrinologic systems and therefore can influence sexual functions. Impotence and disorders of the erectile function can mainly be caused by antidopaminergic mechanisms, whereas ejaculatory disorders and anorgasmia often can be explained by antiserotoninergic effects. Anticholinergic and adrenoloytic agents can also cause a particular impairment of erectile functions. The following considerations will show that the detection and treatment of SD (also in women!) should be given much more attention since drug-induced SDs occur predominantly in indications where a SD itself can be a symptom of the disease.

Chronic endothelin receptor blockade reduces end-organ damage independently of blood pressure effects in salt-loaded heterozygous Ren-2 transgenic rats

The present study was performed to evaluate the role of an interaction between the endothelin (ET) and the renin-angiotensin systems (RAS) in the development and maintenance of hypertension and in hypertension-associated end-organ damage in heterozygous male and female transgenic rats harboring the mouse Ren-2 renin gene (TGR). Twenty-eight days old heterozygous TGR and age-matched transgene-negative normotensive Hannover Sprague-Dawley rats (HanSD) were randomly assigned to groups with normal-salt (NS) or high-salt (HS) intake. Nonselective ET(A)/ET(B) receptor blockade was achieved with bosentan (100 mg.kg(-1).day(-1)). All male and female HanSD as well as heterozygous TGR on NS exhibited 100 % survival rate until 180 days of age (end of experiment). HS diet in heterozygous TGR induced a transition from benign to malignant phase hypertension. The survival rates in male and in female heterozygous TGR on the HS diet were 46 % and 80 %, respectively, and were significantly improved by administration of bosentan to 76 % and 97 %, respectively. Treatment with bosentan did not influence either the course of hypertension (measured by plethysmography in conscious animals) or the final levels of blood pressure (measured by a direct method in anesthetized rats) in any of the experimental groups of HanSD or TGR. Administration of bosentan in heterozygous TGR fed the HS diet markedly reduced proteinuria, glomerulosclerosis and attenuated the development of cardiac hypertrophy compared with untreated TGR. Our data show that the ET receptor blockade markedly improves the survival rate and ameliorates end-organ damage in heterozygous TGR exposed to HS diet. These findings indicate that the interaction between the RAS and ET systems plays an important role in the development of hypertension-associated end-organ damage in TGR exposed to salt-loading.

Interface problems: structural constraints on interpretation?

Five experiments investigated the interpretation of quantified noun phrases in relation to discourse structure. They demonstrated, using questionnaire and on-line reading techniques, that readers in English prefer to give a quantified noun phrase in (VP-external) subject position a presuppositional interpretation, in which the noun phrase limits or restricts the interpretation of an already available set, rather than giving it a nonpresuppositional or existential interpretation, in which it introduces completely new entities into the discourse. Experiment 1 showed that readers prefer a presuppositional interpretation of three ships over the existential interpretation in Five ships appeared on the horizon. Three ships sank. Experiment 2 showed longer reading times in sentences that are disambiguated toward the existential interpretation than in sentences that permit the presuppositional interpretation. Experiment 3 suggested that the presuppositional preference is greater when the phrase three ships occurs outside the verb phrase than when it occurs inside the verb phrase. Experiment 4 showed that Korean subjects marked with a topic marker received more presuppositional interpretations than subjects marked with a nominative marker. Experiment 5 showed that German subjects in VP-external (but nontopic) position received more presuppositional interpretations than VP-internal subjects. The results suggest the syntactic position of a phrase is one determinant of its interpretation, as expected according to the mapping hypothesis of Diesing (1992).

Effects of sodium restriction and cyclooxygenase-2 inhibition on the course of hypertension, proteinuria and cardiac hypertrophy in Ren-2 transgenic rats

The present study was performed to evaluate the effects of sodium intake and of chronic cyclooxygenase-2 (COX-2) inhibition on systolic blood pressure (SBP) in heterozygous male transgenic rats harboring the mouse Ren-2 renin gene (TGR) and in transgene-negative normotensive Hannover Sprague-Dawley (HanSD). Twenty-eight days old TGR and HanSD were randomly assigned to groups fed either normal salt (NS) or low sodium (LS) diets. COX-2 blockade was achieved with NS-398 (1 mg x kg(-1).day(-1) in drinking water). During an experimental period of 26 days, SBP was repeatedly measured by tail plethysmography in conscious animals. We found that the LS diet prevented the development of hypertension in TGR and did not change SBP in HanSD. Low sodium intake also prevented proteinuria and cardiac hypertrophy in TGR. On the other hand, irrespective of sodium intake chronic COX-2 inhibition did not alter the course of SBP in either TGR or HanSD. The present data indicate that TGR exhibit an important salt-sensitive component in the developmental phase of hypertension. They also suggest that systemic COX-2-derived prostaglandins do not act as vasodilatory counterregulatory agents in TGR in which an exaggerated vascular responsiveness to angiotensin II is assumed as the pathophysiological mechanism in the development of hypertension.

Interlaboratory comparison to evaluate a standardized calibration procedure for the headspace analysis of aromatic solvents in blood

The determination of volatile organic compounds in blood by headspace gas chromatography is one of the central and long-established analytical techniques in occupational medical biomonitoring. Nevertheless, the relatively low success rate in intercomparison programs shows that the headspace technique is insufficiently standardized. A critical stage of the analytical procedure seems to be the preparation of calibration standards in biological matrices. As part of an extensive interlaboratory comparison by the Analyses of Hazardous Substances in Biological Materials working group of the DFG Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, three typical procedures were compared with one another using typical aromatic solvents as an example. The best correlations between the participating laboratories and the best results for the analyses of samples from interlaboratory comparisons were obtained when highly concentrated stock solutions of the aromatic compounds in ethanol were first diluted with physiological saline and then used for spiking horse blood in headspace vials. This procedure can be easily standardized and is therefore recommended by the Analyses of Hazardous Substances in Biological Materials working group for the preparation of headspace calibration standards for aromatic compounds.

Genetic targeting of the brain renin-angiotensin system in transgenic rats: Impact on stress-induced renin release

The advance of genetic technologies to permit tissue-specific targeted gene manipulation allowed the development of transgenic models with alterations of the renin-angiotensin (RAS) solely in the brain. We have used such methodology to develop a transgenic rat with a brain specific alteration of the RAS [TGR(ASrAOGEN)], in order to elucidate a causative role for the brain RAS and its relevance in different pathophysiological processes. The TGR(ASrAOGEN) rats have decreased levels of angiotensinogen (AOGEN) throughout the brain because of an antisense inhibition of the astroglial AOGEN synthesis. In this review we aimed at summarizing the experience obtained from utilizing the TGR(ASrAOGEN) rat model to study the brain RAS and present novel results providing evidence for the involvement of this system in stress-induced renin release.

Driver behaviour during flashing green before amber: a comparative study

The paper discusses the results of extensive measurements of drivers' stopping behaviour during signal programmes with and without flashing green before amber. Ten locations in Switzerland, Austria, and Germany were recorded with a video camera and analysed using an image-processing system. About 5000 cycles were documented. The analysis shows that the flashing green increases the number of early stops, as drivers tend to underestimate the duration of the time to the end of amber. Discrete choice models of the stopping behaviour are estimated for inclusion in suitable microsimulation models of traffic flow. The model results show that speed and distance to stop line, and their interaction (potential time to the stop line with unchanged speed) explain the stopping process.

Long-term culture and differentiation of rat embryonic stem cell-like cells into neuronal, glial, endothelial, and hepatic lineages

The in vitro differentiation of mouse embryonic stem cells into different somatic cell types such as neurons, endothelial cells, or myocytes is a well-established procedure. Long-term culture of rat embryonic stem cells is known to be hazardous, and attempts to differentiate these cells in vitro so far have been unsuccessful. We herein describe stable long-term culture of an alkaline phosphatase-positive rat embryonic stem cell-like cell line (RESC) and its differentiation into neuronal, endothelial, and hepatic lineages. RESCs were characterized by typical growth in single cells as well as in embryoid bodies when cultured in the presence of leukemia inhibitory factor. RESC expressed stage-specific-embryonic antigen-1 and the major histocompatibility complex class I molecule. For neuronal differentiation, cells were incubated with medium containing 10(-6) M retinoic acid for 14 days. For endothelial differentiation, RESCs were grown on Matrigel for 14 days, and for induction of hepatocyte-specific antigen expression, RESCs were grown in medium supplemented with fibroblast growth factor-4. Differentiated cells exhibited typical morphological changes and expressed neuronal (nestin, mitogen-activated protein-2, synaptophysin), glial (S100, glial fibrillary acid protein), endothelial (panendothelial antibody, CD31) and hepatocyte-specific (alpha-fetoprotein [alphaFP], albumin, alpha-1-antitrypsin, CK18) antigens. In addition, expression of hepatocyte-specific genes (alphaFP, transthyretin, carbamoyl-phosphate synthetase, and coagulation factor-2) was detected by reverse transcription polymerase chain reaction. We were able to culture RESCs under stable, long-term conditions and to initiate programmed differentiation of RESCs to endothelial, neuronal, glial, and hepatic lineages in the rat species.

Chronic endothelin receptor blockade reduces end-organ damage independently of blood pressure effects in salt-loaded heterozygous Ren-2 transgenic rats

The present study was performed to evaluate the role of an interaction between the endothelin (ET) and the renin-angiotensin systems (RAS) in the development and maintenance of hypertension and in hypertension-associated end-organ damage in heterozygous male and female transgenic rats harboring the mouse Ren-2 renin gene (TGR). Twenty-eight days old heterozygous TGR and age-matched transgene-negative normotensive Hannover Sprague-Dawley rats (HanSD) were randomly assigned to groups with normal-salt (NS) or high-salt (HS) intake. Nonselective ET(A)/ET(B) receptor blockade was achieved with bosentan (100 mg.kg(-1).day(-1)). All male and female HanSD as well as heterozygous TGR on NS exhibited 100 % survival rate until 180 days of age (end of experiment). HS diet in heterozygous TGR induced a transition from benign to malignant phase hypertension. The survival rates in male and in female heterozygous TGR on the HS diet were 46 % and 80 %, respectively, and were significantly improved by administration of bosentan to 76 % and 97 %, respectively. Treatment with bosentan did not influence either the course of hypertension (measured by plethysmography in conscious animals) or the final levels of blood pressure (measured by a direct method in anesthetized rats) in any of the experimental groups of HanSD or TGR. Administration of bosentan in heterozygous TGR fed the HS diet markedly reduced proteinuria, glomerulosclerosis and attenuated the development of cardiac hypertrophy compared with untreated TGR. Our data show that the ET receptor blockade markedly improves the survival rate and ameliorates end-organ damage in heterozygous TGR exposed to HS diet. These findings indicate that the interaction between the RAS and ET systems plays an important role in the development of hypertension-associated end-organ damage in TGR exposed to salt-loading.