Microbiota-derived metabolites in colorectal cancer patients in preoperative period.

OBJECTIVE: Short-chain fatty acids (SCFAs) are microbial derived metabolites, which have multiple beneficial properties. The amount of SCFAs depends on several factors, such as age, diet (mainly intake of dietary fiber), and overall health condition. The normal proportion between SCFAs is 3:1:1 for acetate, proprionate and butyrate, respectively. In colorectal cancer (CRC) patients, microbiota alterations have been shown. Consequently, metabolome within the gut might change to a large extent. Therefore, the aim of this study was to analyse the content of SCFAs and the proportion between SCFAs in the stool obtained from CRC patients in preoperative period. PATIENTS AND METHODS: This study included 15 patients with CRC in preoperative period. The stool samples were taken and stored at -80°C in the Fahrenheit Biobank BBMRI.pl, Medical University of Gdansk, Poland. The analysis of SCFAs from stool samples was conducted by means of gas chromatography. RESULTS: This study included mainly males (66.67%, n=10). In all patients, there was abnormal proportion between SCFAs. The extremely higher concentration of butyrate was noted in 2 samples (13.33%) compared to the rest of patients. However, based on normal proportion between SCFAs, the results <1 for butyrate were noted in 93.33% of patients. CONCLUSIONS: SCFAs pool is altered in CRC patients, among others characterized by low level of butyrate. It should be considered to administer butyrate supplementation to CRC patients especially prior to surgery to support an appropriate preparation to this treatment.

The role of occlusion and micro-incontinence in the pathogenesis of penile lichen sclerosus: an observational study of pro-inflammatory cytokines' gene expression.

PURPOSE: To assess the expression of selected cytokines in penile lichen sclerosus (PLS) and associate them with the occurrence of micro-incontinence (MI) in different stages of PLS. METHODS: The skin biopsies from 49 PLS affected, and 13 from nonlesional foreskins (healthy control adult males undergoing circumcision due to phimosis caused by short frenulum) were obtained. All specimens were used for RNA extraction and RT-qPCR. Quantitative assessment of the gene expression of interleukin 1-A (IL-1A), interleukin 1-B (IL-1B), interleukin 1 receptor antagonist (IL-1RN), interleukin 6 (IL-6), transforming growth factor ß1 (TGF-ß1), and interferon-gamma (INF-γ) was performed. To determinate the presence of MI, the patients were asked about voiding patterns, especially leaking tiny drops of urine from the urethral meatus after urination. RESULTS: IL-1A, IL-6, and INF-γ mRNA levels were approximately 150, 16, and 59 times higher in PLS than in control samples, respectively. The highest IL-1A mRNA levels were observed in early PLS (n = 13), INF-γ in moderate PLS (n = 32), while IL-6 in severe PLS (n = 4). MI was noted in 45 PLS patients vs. 0 in control (p < 0.0001). IL-1A and IL-6 vs control ratios were concentration (ca.) 400 and 30 times higher, respectively, in MI PLS samples than in PLS without MI. CONCLUSION: Occlusion and irritating urine effect are associated with the clinical progression of penile LS with increased mRNA expression of IL-1A, INF-γ, and IL-6 pro-inflammatory cytokines in the foreskin.

Cadmium, arsenic, selenium and iron- Implications for tumor progression in breast cancer.

The aim of this study was to determine Cd (cadmium) and As (arsenic) contents in human breast cancer tissues, investigate their interactions with Se (selenium) and Fe (iron), and assess their further implications for tumor progression. Metal contents were determined in 42 tissue sets (tumor and adjacent tissue) collected from 42 women diagnosed with primary breast cancer. Analytical methods included AAS and ICP-MS techniques. Significantly higher contents of Cd (p=0.0003), Se (p<0.0001) and Fe (p=0.0441) whereas significantly lower content of As (p<0.0001) were observed in tumors as compared to adjacent tissues. There was a significant positive correlation between Cd and As contents in tumor tissue. However, only Cd was significantly associated with histological type of tumor, its size, grading and progesterone receptor status. This study support the role of Cd in breast cancer risk and progression. The possible link between As exposure and breast cancer is still not clear.

Peroxynitrite in Sarcoidosis: Relation to Mycobacterium Stationary Phase.

There is evidence that the same mycobacterial heat shock proteins (Mtb-HSPs), especially HSP16, the main marker of mycobacteria dormant stage, occur in sarcoid tissues and in circulated immune complexes and prompt the immune responses against the different genetic background, leading to the development of acute sarcoidosis (SA)/Löfgren syndrome, chronic SA, latent tuberculosis (TB), or active TB. In SA there is increased monocytes phagocytic activity, decreased clearance of antigens/immune complexes by monocytes, which are resistant to apoptosis, and decreased serum microbicidal/degradable nitrate/nitrite (NOx) concentration. Reduction in NOx may result from the reaction of NOx with superoxide with subsequent production of peroxynitrite (ONOO-). In this study, therefore, we evaluated NOx and ONOO- levels in supernatants of peripheral blood mononuclear cells cultures treated with Mtb-HSPs from 20 SA patients, 19 TB patients, and 21 healthy volunteers using Griess and rhodamine fluorescence methods. We found significantly greater NOx and ONOO- concentrations with/without Mtb-HSPs stimulation in SA and TB patients than in controls. However, there were significantly lower NOx and higher ONOO- levels after Mtb-HSPs induction in SA than TB patients. In summary, in contrast to active TB, increased ONOO- concentration may explain the low level of NOx with induction of M. tuberculosis genetic dormancy program via higher Mtb-HSP16 expression in SA.

Elucidating structure-function relationships from molecule-to-cell-to-tissue: from research modalities to clinical realities.

The National Academy of Engineering selected 'Imaging' as one of the greatest engineering achievements of the 20th century (Greatest Engineering Achievements of the 20th Century. 2009 (cited 2008, November 10); available from: http://www.greatachievements.org/). The combination of different imaging modalities and technologies for mapping bimolecular and/or biological processes within single cells or even whole organs has extraordinary potential for revolutionizing the diagnosis and treatment of pathophysiological disorders, and thus for mitigating the significant social and economic costs associated with the clinical management of disease. Such integrated imaging approaches will eventually lead to individualized programs for disease prevention through advanced diagnosis, risk stratification and targeted cell therapies resulting in more successful and efficient health care. The goal of this article is to provide readers with a current update of selected of state-of-the-art imaging modalities which would likely to lead to improved clinical outcomes if employed in an integrated approach, including use of ultramicrosensors to detect reactive oxygen/nitrogen species in a single cell, use of electron tomography to visualize and characterize cellular organization in three dimensions (3D), and molecular imaging strategies to assess naturally occurring and therapeutic peripheral and myocardial angiogenesis using targeted radiolabeled tracers.

Involvement of Rho-kinase in P2Y-receptor-mediated contraction of renal glomeruli.

The involvement of Rho-kinase in P2Y-receptor induced contraction of isolated rat renal glomeruli was investigated. The contraction effects have been investigated based on changes in the intracapillary volume of isolated glomeruli. ATP was found to induce time- and concentration-dependent contraction of isolated glomeruli. Other tested nucleotides (ADP, UTP) and ATP analogues (beta,gamma-methylene-ATP, 2-methylothio-ATP) contracted glomeruli in similar magnitude whereas AMP had no effect. Furthermore, the contractive effect of ATP was prevented in the presence of an antagonist of P2Y-receptors, reactive blue 2. However, a selective antagonist of A1-receptors, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), had no effect. Contraction induced by ATP, ADP, and UTP, in contrast to 2-methylothio-ATP and beta,gamma-methylene-ATP, was prevented in the presence of Rho-kinase's inhibitor, (R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide dihydrochloride monohydrate (Y-27632). These findings suggest the involvement of Rho-kinase pathways in P2Y-induced contraction of isolated glomeruli.

Cerivastatin potentiates nitric oxide release and enos expression through inhibition of isoprenoids synthesis.

Endothelium dysfunction, which is often defined as a decrease in NO bioavailability, is one of the earliest manifestations of endothelium-impaired function disorders, including atherosclerosis. Although improvement in NO bioavailability has been attributed to the lowering of serum cholesterol levels, recent studies suggest that HMG-CoA reductase inhibitors, statins, may have direct effects on NO bioavailability by little known mechanisms that are independent of serum cholesterol levels. The long-term effect of cerivastatin on NO release from endothelial cells was determined by using highly sensitive electrochemical microsensors and was correlated with endothelial NO synthase (eNOS) levels. To explore whether changes in isoprenoid synthesis affect NO bioavailability and eNOS expression, human endothelial cells were treated with cerivastatin, L-mevalonate (MVA; 1.5 mmol/L), geranylgeranylpyrophosphate (GGPP; 1 mg/mL) and farnesylpyrophosphate (FPP; 1 mg/mL). Cerivastatin increased spontaneous (by 53% +/- 6) and an eNOS-stimulated NO release (by 41 +/- 6% for calcium ionophore and by 47 +/- 5% acetylcholine) as well as eNOS expression (by 118 +/- 6%) in the same concentration-range. Cerivastatin-dependent increase in both NO release and eNOS expression was revealed after approximately 4 h of exposure reaching the maximum after approximately 10 h. Co-treatment with MVA or GGPP, but not FPP or LDL, reversed the effects of cerivastatin. These findings indicate that the long-term effect of cerivastatin resulting in enhanced NO bioavailabilty in endothelial cell is, at least in part, due to up-regulation of eNOS by blocking isoprenoids synthesis.

Nitric oxide as a second messenger in parathyroid hormone-related protein signaling.

Parathyroid hormone (PTH)-related protein (PTHrP) is produced in smooth muscles and endothelial cells and is believed to participate in the local regulation of vascular tone. No direct evidence for the activation of endothelium-derived nitric oxide (NO) signaling pathway by PTHrP has been found despite attempts to identify it. Based on direct in situ measurements, it is reported here for the first time that the human PTH/PTHrP receptor analogs, hPTH(1--34) and hPTHrP(1--34), stimulate NO release from a single endothelial cell. A highly sensitive porphyrinic microsensor with a response time of 0.1 ms and a detection limit of 1 nmol/l was used for the measurement of NO. Both hPTH(1--34) and hPTHrP(1--34) stimulated NO release at nanomolar concentrations. The peak concentration of 0.1 micromol/l hPTH(1--34)- and 0.1 micromol/l hPTHrP(1--34)-stimulated NO release was 175+/-9 and 248+/-13 nmol/l respectively. This represents about 30%--40% of maximum NO concentration recorded in the presence of (0.1 micromol/l) calcium ionophore. Two competitive PTH/PTHrP receptor antagonists, 10 micromol/l [Leu(11),d -Trp(12)]-hPTHrP(7--34)amide and 10 micromol/l [Nle(8,18),Tyr(34)]-bPTH(3--34)amide, were equipotent in antagonizing hPTH(1--34)-stimulated NO release; [Leu(11),d -Trp(12)]-hPTHrP(7--34)amide was more potent than [Nle(8,18),Tyr(34)]-bPTH(3--34)amide in inhibiting hPTHrP(1--34)-stimulated NO release. The PKC inhibitor, H-7 (50 micromol/l), did not change hPTH(1--34)- and hPTHrP(1--34)-stimulated NO release, whereas the combined effect of 10 micromol/l of the cAMP antagonist, Rp-cAMPS, and 50 micromol/l of the calmodulin inhibitor, W-7, was additive. The present studies show that both hPTH(1--34) and hPTHrP(1--34) activate NO production in endothelial cells. The activation of NO release is through PTH/PTHrP receptors and is mediated via the calcium/calmodulin pathway.

The role of P2Y-receptors in the regulation of glomerular volume.

BACKGROUND: Extracellular ATP signaling affects the cells of renal glomeruli via activation of P2-purinoceptors, denoted as P2X and P2Y. Through either of these purinoceptors, ATP is able to stimulate an increase in intracellular [Ca2+]. P2Y-receptors are expressed on mesangial and endothelial cells, thus may participate in contraction and relaxation of glomeruli, respectively. Moreover, P2Y-receptors possess activity of ecto-ATPase which may lead to dephosphorylation of ATP and generation of adenosine. The aim of the present study was to investigate the involvement of P2Y-receptors in responses of renal glomeruli to extracellular ATP. MATERIAL AND METHODS: Renal glomeruli were isolated from rats by sieving technique. [3H]-inulin was used to measure the intracapillary volume of isolated glomeruli. Changes of intracapillary volume reflect contraction and relaxation of the glomeruli. ATP and adenosine concentration in the incubation mixture were measured using luminometric methods. RESULTS: Extracellular ATP (1 microM) induced relaxation of Ang II-precontracted glomeruli in time-dependent manner. The glomeruli relaxed completely at 2nd minute of incubation. The relaxation was considerably diminished at 5th minute of incubation as compared to 2nd minute. Relaxing effect was completely prevented by an antagonist of P2Y-receptors i.e. reactive blue 2. The decrease in ATP concentration with time was accompanied by a rise in adenosine concentration which led to contraction of glomeruli. Non-metabolised analogue of ATP, an agonist of P2Y-receptors i.e. 2-methylthio-ATP (1 microM) induced complete relaxation at 2nd minute of incubation but there was no effect at 5th minute of incubation. CONCLUSIONS: The extracellular ATP through activation of P2Y-receptors may regulate the volume of renal glomeruli, which in turn influences on the glomerular filtration rate, through at least two mechanisms: one is ATP-dependent glomerular relaxation in the initiate phase and the other is glomerular contraction caused by either ATP itself or adenosine formed from ATP hydrolysis in maintenance phase.

Studies on potential involvement of protein kinase C in glomerular insensitivity to atrial natriuretic factor on low sodium intake.

BACKGROUND: Atrial natriuretic factor (ANF)-induced increase in glomerular filtration rate (GFR) is inhibited on low sodium intake. It has been shown that activation of renin-angiotensin system on low sodium intake antagonizes the biological effect of ANF by interfering in the intracellular metabolism of cGMP. We have previously indicated that the renin-angiotensin system increases activity of Ca2+/calmodulin dependent-cyclic GMP phosphodiesterase (cGMP-PDE) in glomeruli and thereby inhibits the ANF-induced increase in GFR in low sodium-treated rats. The aim of the present study was to investigate whether low sodium intake might change glomerular cGMP metabolism by the alternative branch of the signal transduction pathway, namely protein kinase-C (PKC) activation. MATERIAL AND METHODS: cGMP formation and PKC activity were examined in isolated glomeruli from the rats maintained for five days on a normal or a low sodium diet. Renal hemodynamic parameters in clearance experiments during infusion of ANF (0.5 Kg/min/kg body weight) in both groups of rats were also evaluated. RESULTS: Low sodium intake inhibited ANF-dependent increase in GFR and nephrogenous cGMP excretion, whereas urinary sodium excretion did not differ appreciably in rats on either diet. The basal and ANF-stimulated cGMP formation in isolated glomeruli was significantly inhibited in low sodium-treated rats as compared to normal sodium-treated rats. The inhibitory effect of low sodium intake on basal and ANF-stimulated glomerular cGMP formation was completely prevented by a selective cGMP-PDE inhibitor, zaprinast, but not affected by PKC activator, PMA, or PKC inhibitor, H-7. The activity of PKC in glomeruli neither in membrane fraction nor in cytosol fraction did not differ significantly between normal and low sodium-treated rats. CONCLUSIONS: These results demonstrate that the blunted glomerular response to ANF in rats on low sodium intake is due to decrease ability of cGMP formation in glomeruli by increasing activity of cGMP-PDE without altering activity of PKC.

Statin-stimulated nitric oxide release from endothelium.

BACKGROUND: There is increasing evidence that loss of endothelium-derived NO is a major factor in cardiovascular complication events, and that NO might exert antiatherosclerotic actions. The beneficial effects of HMG CoA reductase inhibitors (statins) therapy in atherosclerosis outweigh those expected from simply lowering low-density lipoprotein (LDL) cholesterol, and may be related to the direct action in the endothelium. Based on these concepts, in the studies described here, the effect of new statin derivatives on nitric oxide (NO) and superoxide (O2-) release in bovine endothelial cells was tested. MATERIAL AND METHODS: Highly sensitive electrochemical NO and O2--microsensors were placed near the surface of endothelial cells, and the concurrent kinetics of NO and O2-- release were measured in situ. RESULTS: All tested statins stimulated NO release. The peak concentration of NO after stimulation with 1 Kmol/l Lovastatin, 1 Kmol/l Atorvastatin, 1 Kmol/l Pravastatin, or 1 Kmol/l Simvastatin was about 77%, 73%, 72%, and 44% lower, respectively, as compared with the NO peak concentration after stimulation with 1 Kmol/l calcium ionophore A23187 (receptor-independent agonist). The tested statins stimulated NO release in a modest way, which resulted in diminishing O2- generation during activation of nitric oxide synthase. Moreover, the kinetics of O2- release after administration of the statins suggested that these compounds may also scavenge O2-. The NO/O2- peak concentration ratio after the NOS agonists administration was as follows: 7.51 for CaI, 6.56 for Lovastatin, 6.00 for Atorvastatin, 4.17 for Pravastatin and 6.25 for Simvastatin. CONCLUSIONS: The tested statins, i.e. Lovastatin, Atorvastatin, Pravastatin and Simvastatin demonstrate variable potency to enhance the NO/O2- concentration ratio after stimulation of NOS, resulting in an increase of NO bioavailability in endothelial cells.

Cicletanine stimulates nitric oxide release and scavenges superoxide in endothelial cells.

Cicletanine ((+/-)3-(4-chlorophenyl)-1,3-dihydro-7-hydroxy-6-methylfuro-[3,4-c] pyridine) 3-(4-chlorophenyl)-1,3-dihydro-7-hydroxy-6-methylfuro-[3,4-c] pyridine) is a novel antihypertensive vasodilator with an incompletely understood mechanism of action. In the studies described here, the release of nitric oxide and superoxide (O2-) stimulated by cicletanine was measured simultaneously in the endothelium of isolated rat aortic rings. Highly sensitive electrochemical nitric oxide and O2- microsensors were placed near the surface of endothelial cells and the kinetics of nitric oxide and O2- release were monitored in situ. The response times for nitric oxide and O2- microsensors were 100 micros and 50 micros, respectively, and detection limit was 10(-9) M. Cicletanine stimulated nitric oxide release in aorta endothelium at (micromolar) therapeutic concentrations that were consistent with the concentrations of the compound to induce endothelium-dependent vasorelaxation in isolated rat aorta. The peak concentration of nitric oxide was 160+/-8 nM. This concentration was about 70% and was 60% lower as compared with the nitric oxide peak concentration observed after stimulation with receptor-independent agonist (calcium ionophore A23187) and receptor-dependent agonist (acetylcholine), respectively. However, after administration of cicletanine, only a small concentration of O2- was recorded (peak 3.1+/-0.2 nM) contrary to a large concentration (27+/-1.35 nM) observed after stimulation with A23187). Cicletanine not only stimulated nitric oxide release but also was a potent scavenger of O2- at nanomolar level. Both of these effects may contribute to potent vasorelaxation properties of cicletanine and its long-term therapeutic actions, resulting in cardiovascular tissue protection.

Nitric oxide measurements during endotoxemia.

BACKGROUND: Excessive continuous NO release from inducible NO synthase over prolonged periods under pathological conditions, such as endotoxemia, contributes significantly to circulatory failure, hypotension, and septic shock. This NO production during endotoxemia is accompanied by superoxide release, which contributes to the fast decay of NO. Therefore, the amount of NO that diffuses to target sites may be much lower than the total amount released under pathological conditions. METHODS: We performed in vivo and ex vivo measurements of NO (electrochemical) and ex vivo in situ measurements of superoxide, peroxynitrite (chemiluminescence), and nitrite and nitrate (ultraviolet-visible spectroscopy). We determined the effect of lipopolysaccharide administration (20 mg/kg) on diffusible NO, total NO (diffusible plus consumed in chemical reactions), and superoxide and peroxynitrite release in the pulmonary arteries of rats. RESULTS: An increase in diffusible NO generated by constitutive NO synthase was observed immediately after administration of lipopolysaccharide, reaching a plateau (145 +/- 18 nmol/L) after 540 +/- 25 s. The plateau was followed by a decrease in NO concentration and its subsequent gradual increase after 45 min because of NO production by inducible NO synthase. The concentration of superoxide increased from 16 +/- 2 nmol/L to 30 +/- 3 nmol/L after 1 h and reached a plateau of 41 +/- 4 nmol/L after 6 h. In contrast to the periodic changes in the concentration of diffusible NO, the total concentration of NO measured as a sum of nitrite and nitrate increased steadily during the entire period of endotoxemia, from 2.8 +/- 0.2 micromol/L to 10 +/- 1.8 micromol/L. CONCLUSIONS: The direct measurement of NO concentrations in the rat pulmonary artery demonstrates dynamic changes throughout endotoxemia, which are related to the production of superoxide and the subsequent increase in peroxynitrite. Monitoring endotoxemia with total nitrate plus nitrite is not sensitive to these fluctuations in NO concentration.

Cyclic GMP-dependent relaxation of isolated rat renal glomeruli induced by extracellular ATP.

The relaxing effect of extracellular ATP on renal glomeruli has been investigated by applying ATP and its analogues to suspensions of angiotensin II-precontracted rat renal glomeruli. Based on changes of glomerular [3H]inulin space (GIS) the relaxation of glomeruli was analysed in the presence of agonists: ATP, ADP, AMP, UTP, 2-methylthio-ATP (P2Y agonist), beta,gamma-methylene-ATP (P2X agonist) and adenosine. ATP, 2-methylthio-ATP, ADP and UTP induced concentration-dependent relaxation whereas AMP, beta,gamma-methylene-ATP and adenosine had no effect. The rank order of relaxation potency was 2-methylthio-ATP > ATP > ADP > UTP. An inhibitor of constitutive nitric oxide synthase (NOS), Nomega-nitro-L-arginine (NNA) prevented the ATP-induced increased accumulation of L-citrulline and the relaxation effect of ATP. An inhibitor of the neuronal isoform of NOS, 7-nitroindazole, had no effect on the relaxation effect of ATP. The relaxing effect of ATP was prevented in the presence of inhibitors of cyclic guanylyl cyclase: methylene blue (MB) and the more specific inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ). ATP stimulated an accumulation of cGMP that was diminished in the presence of MB. We indicated that extracellular ATP may relax the glomeruli via activation of P2Y receptors with the subsequent activation of the endothelial isoform of nitric oxide synthase and soluble guanylyl cyclase. We suggest that, based on the described mechanism, extracellular ATP may increase the filtration surface which, in turn, may influence the glomerular filtration rate.

Bidirectional action of extracellular ATP on intracapillary volume of isolated rat renal glomeruli.

Receptors for extracellular nucleotides (P2-purinoceptors) are expressed in renal glomerulus; both on mesangial and endothelial cells. In the present study we have evaluated the potential role of ATP in the regulation of glomerular contraction and relaxation. Using [3H]-inulin we measured the Glomerular Inulin Space (GIS), (that reflects mainly glomerular intracapillary volume), in the presence of ATP and its analogues e.g. 2-methylthio-ATP (P2Y-receptor agonist) and beta,gamma-methylene-ATP (P2X-receptor agonist). Incubation of the intact glomeruli with ATP or 2-methylthio-ATP or beta,gamma-methylene-ATP induced a decrease of GIS in similar magnitude as angiotensin II e.g.: about 10% of the basal value. When glomeruli were precontracted with angiotensin II it was observed that both ATP and 2-methylthio-ATP induced an increase of GIS to the basal value, similarly to atrial natriuretic factor. Furthermore, there was no relaxing effect with beta,gamma-methylene-ATP. We suggest that, these bidirectional changes of the intracapillary volume induced by the extracellular ATP may contribute to regulation of glomerular dynamics.

The protective role of nitric oxide in the brain ischemia.

A role of nitric oxide in ischemia/reperfusion (I/R) injury of brain in normotensive (Sprague-Dowley rats, SD) and stroke-prone spontaneously hypertensive rats (SHR-SP) was studied. Cerebral ischemia was produced in rats by occlusion of the middle cerebral artery (MCA). NO and O2- releases in the brain in response to MCA occlusion followed by reperfusion were simultaneously monitored (2h) using electrochemical microsensors. The size of infarct was evaluated in the course of I/R from images of brain slices stained with 2,3,5-triphenyltetrazolium chloride. Similar patterns of NO and O2- releases were exhibited for SD and SHR-SP rats in the entire course of the experiments. However, the concentration of NO release was significantly lower during I/R in SHR-SP than in SD rats (the maximal NO concentration was 2.61 +/- 0.22 micromol/L for SD and 1.51 +/- 0.16 micromol/L for SHR-SP rats; *P < 0.01). In contrast, the concentration of O2- release during cerebral ischemia was significantly higher in SHR-SP than SD rats (the maximal increase was 122 +/- 24 nmol/L for SD and 220 +/- 44 nmol/L for SHR-SP rats; *P<0.01). The infarct sizes revealed in the course of I/R were larger in SHR-SP than SD rats (1.8 +/- 0.4% vs. 1.1 +/- 0.4% at 30 min., 2.84 +/- 0.8% vs. 2.21 +/- 0.6% at 100 min. and 9.20 +/- 1.1% vs. 5.8 +/- 0.6% at 180 min. ofthe brain weights, respectively; *P < 0.01 for each time-point). These studies indicate that nitric oxide plays a protective role during I/R and deficiency of NO in SHR-SP rats is due to excess of O2- production. The deficiency in NO concentration correlates positively with the increase of cerebral I/R injury.

Cicletanine: new insights into its pharmacological actions.

Cicletanine ((+/-)3-(4-chlorophenyl)-1,3-dihydro-7-hydroxy-6-methylfuro-[3,4-c ] pyridine) 3-(4-chlorophenyl)-1,3-dihydro-7-hydroxy-6-methylfuro-[3,4-c] pyridine) is a novel antihypertensive agent that has been shown to possess vasorelaxant, natriuretic, and diuretic properties in preclinical and clinical studies. The mechanism(s) by which cicletanine induces these biological effects has not been definitely established, although it appears to differ from that of other classes of antihypertensive drugs. The salidiuretic activity appears to be the result of an action of the sulfoconjugated metabolite of cicletanine, which inhibits the apical Na+-dependent Cl-/HCO3- anion exchanger in the distal convoluted tubule. The mechanism of the vasodilating effect of cicletanine seems to be complex; it may include stimulation of vascular prostaglandin synthesis, inhibition of the low Km cyclic GMP phosphodiesterases, and blockade of Ca2+ channels either directly or indirectly through a K+-channel opening effect. The drug has also been shown to interact with alpha-adrenergic, vascular histamine, and muscarinic receptors. We have also reviewed the other vascular effects of the drug, such as stimulation of nitric oxide synthesis and inhibition of both myosin light chain kinase and protein kinase C. Cicletanine protects cardiovascular and renal systems against the injuries induced by hypertension, in addition to its lowering of arterial pressure. Similarly to the vasorelaxant action of cicletanine, the various properties of the drug likely contribute to its protective effect against injury in hypertension.

A dental fears typology of oral surgery patients: matching patients to anxiety interventions.

Two studies are described in which dental patients were administered the Dental Fear Survey (DFS) and then received 1 of 5 anxiety reduction interventions to prepare them for extraction of 3rd-molar teeth. Interventions included standard clinic treatment, oral premedication, and several relaxation-based procedures. Dependent variables were self-reported and observer-rated distress. In the 1st study (N = 231), cluster analyses of the DFS subscales revealed that patients could be subtyped as low-fear, high-fear, or cue-anxious patients who admitted fear only in response to specific stimuli. Dental fear subtypes were distinguishable by situational cognitions reported, and fear subtype interacted with anxiety intervention to predict distress. These results were replicated in the 2nd study (N = 150). The results are seen as supportive of a multidimensional view of dental anxiety.

Modulation by low sodium intake of glomerular response to cicletanine and atrial natriuretic factor.

1. The aim of the study was to investigate whether cicletanine (CIC), as a potential inhibitor of cyclic GMP phosphodiesterase, is able to restore glomerular response to atrial natriuretic factor (ANF) in rats under conditions of diet deprived of sodium. We examined the effects of CIC on glomerular filtration rate (GFR), natriuresis and nephrogenous cyclic GMP excretion in response to ANF and the effects of both agents on intracapillary volume and cyclic GMP accumulation in isolated glomeruli of rats on normal and low sodium diets. 2. CIC (0.25 mg min-1 kg-1 BW) of ANF (0.5 microgram min-1 BW) alone, given in pharmacological doses, increased Cin significantly in normal sodium rats, whereas the effect of each agent was blunted in low sodium diet rats. Pretreatment with CIC restored the increase in C(in) in response to ANF infusion in low sodium diet rats. In rats on either diet, there were no differences in the extent of diuresis and natriuresis induced by CIC or ANF alone. In contrast to FENa, combined effects of both agents on V and UNa V in rats on normal and low sodium diets were observed. 3. In normal sodium diet rats, CIC 10(-4) M or ANF 10(-6) M alone inhibited angiotensin II 10(-6) M (AII)-induced decrease in intracapillary volume reflected by the glomerular [3H]-inulin space (GIS). In contrast, CIC or ANF alone did not inhibit AII-induced decrease in GIS in low sodium diet rats. Both agents given together inhibited AII-induced decrease in GIS in low sodium diet rats. 4. CIC both alone and in combination with ANF increased nephrogenous cyclic GMP excretion and cyclic GMP accumulation in isolated glomeruli of rats on normal and low sodium diets. In rats on either diet, CIC abolished the difference in ANF-stimulated increase in nephrogenous cyclic GMP excretion and cyclic GMP accumulation in glomeruli. 5. These results suggest that CIC and ANF alone induce relaxation of glomeruli and a resultant increase in glomerular filtration rate in normal sodium diet rats; in contrast, these effects are blunted in the low sodium diet rats. CIC restores glomerular response to ANF in low sodium diet rats, apparently involving inhibition of the cyclic GMP phosphodiesterase.

[Significant negative correlation between fasting plasma insulin and ambulatory blood pressure in patients on chronic hemodialysis]. / Znamienna ujemna korelacja miedzy stezeniem insuliny na czczo i ambulatoryjnym cisnieniem tetniczym u chorych przewlekle dializowanych.

Positive correlation between blood pressure and insulin is well established in patients with essential hypertension. The aim of the present study was to examine the relationship between fasting plasma insulin level and ambulatory blood pressure (ABPM) in patients with chronic renal failure. The study group consisted of 20 patients (11 females, 9 males, mean age 39 +/- 12 years) on chronic haemodialysis (mean 2.5 years). Fasting plasma insulin (FPI) was measured by radioimmunoassay. The patients were investigated before and after haemodialysis. FPI significantly increased after haemodialysis from 18.4 +/- 12.0 to 40.1 +/- 31.9 mIU/l (p < 0.01), while creatinine concentration decreased from 1158 +/- 130 to 910 +/- 159 mumol/l (p < 0.001). Night-time systolic blood pressure (SBP) was significantly lower during the day of haemodialysis (141.9 +/- 19.6 mmHg vs. 136 +/- 27.7 mmHg, p < 0.05). 24-hour and daytime SBP was nonsignificantly lower after haemodialysis. 24-hour diastolic blood pressure (DBP) was significantly lower during the day of haemodialysis (92.9 +/- 12.5 mmHg vs. 87.3 +/- 14.3 mmHg, p < 0.05), as well as daytime (94.9 +/- 12.1 mmHg vs. 88.8 +/- 14.6 p < 0.05) and night-time DBP (88.9 +/- 16.0 mmHg vs. 83.8 +/- 17.4 mmHg p < 0.05). FPI was found to be significantly negatively correlated with 24-hour, daytime and night-time SBP on the day of haemodialysis (r = -0.63, p < 0.005; r = 0.64, (p < 0.005 and r = -0.54, p < 0.05, respectively). The significant negative correlation between FPI and 24-hour SBP suggests that insulin could reveal its hypotensive effect after the haemodialysis.