Linear and nonlinear analysis of dental pulp blood flow oscillations in ageing.

AIM: To investigate the effect of ageing on control mechanisms of pulpal microcirculation using wavelet analysis and to calculate linear and nonlinear parameters of blood flow oscillations, in a healthy general population. METHODOLOGY: Pulpal blood flow (PBF) oscillations were recorded on right maxillary central incisors using laser Doppler Flowmeter (PeriFlux PF 5001, Perimed, Jarfalla, Sweden) on a group of 10 young participants (20-25 years) and a group of 10 older adults (60-70 years). In total, 20 recordings were obtained for at least 20 min (one recording on one tooth per subject). Using wavelet spectral analysis, the amplitude and power were calculated as a linear and Hurst exponent as a nonlinear parameter of PBF oscillations. Differences between the two groups were assessed with the independent Student t-test. RESULTS: Mean PBF levels were significantly lower (P = 0.024) in older adults than in young participants. Relative amplitudes and powers corresponding to the myogenic (P = 0.046, P < 0.001, respectively) and neurogenic activity (P = 0.04, P = 0.01, respectively) were significantly higher, whereas values corresponding to the endothelial function (P = 0.04, P = 0.01, respectively) were significantly lower in older adults than in young participants. Hurst exponents of the total spectrum, myogenic and endothelial component (P < 0.001, P = 0.02, P < 0.001, respectively) of PBF oscillations were significantly lower in older adults in comparison to young participants. CONCLUSIONS: At the level of pulpal microcirculation, ageing was associated with altered blood flow levels, the contribution of different control mechanisms to blood flow oscillations as well as the interaction of vascular smooth muscle and endothelium. Described changes of pulpal haemodynamics contribute to a better understanding of physiological behaviour and decreased adaptability of aged dental pulp to pathological stimuli.

Ethanol concentration changes in blood samples during medium-term refrigerated storage.

OBJECTIVE: Stability of blood alcohol concentration (BAC) in laboratory samples is of great importance when it is necessary to perform repeated analyses. MATERIALS AND METHODS: We have analyzed the stability of BAC in 50 samples, which were taken from apprehended drivers, kept at -18ºC, without preserving agents. Quantitative analyses were performed using headspace sampling gas chromatography (HS-GC) with flame ionizing detection (FID). Samples were analyzed immediately after collection (C1), and after 60 (C60), 120 (C120) and 180 (C180) days. A group of 50 samples, which were kept closed for 180 days at -18ºC, was utilized as a control. RESULTS: We found a significant decrease in BAC between C1 and C180 (= 0.224; SD= 0.144; t = 10.98; p<0.001), and between C1 and C60, C60 and C120, C120 and C180. There was a significant positive correlation (r=0.8) between starting concentration C1, and the value of BAC changes (ΔC). Linear regression analysis (R2=0.64) implies the degree of validity to the proposed model of ΔC change regarding initial BAC. There were significant changes in ΔC between the two groups. CONCLUSIONS: These data underline the significance of air chamber percent (CA%) and ethanol evaporation due to ventilation between liquid and gas phase as a mechanism of ethanol decay.

Reduced muscarinic parotid secretion is underlain by impaired NO signaling in diabetic rabbits.

OBJECTIVES: The influence of experimental diabetes (alloxan, 100 mg kg(-1) ) was studied on rabbit parotid gland function. MATERIAL AND METHODS: Carbachol-induced parotid secretion in vivo, and in vitro quantification of inducible nitric oxide synthase (iNOS) mRNA expression, by real-time RT-PCR, and activity of superoxide dismutase (SOD) and total antioxidant capacity (TAC) in commercial colorimetric assays were measured in parotid glands of non-diabetic and diabetic rabbits. RESULTS: Carbachol-induced dose-dependent increase in parotid secretion significantly reduced in diabetic rabbits. Functional studies in the presence of muscarinic receptor and nitric oxide synthase (NOS) antagonists revealed that in M3 receptor-mediated carbachol secretion, nitric oxide, deriving mainly from neuronal NOS (nNOS) in control, and iNOS in diabetic rabbits, was involved. Also, upregulation of iNOS mRNA expression and enhanced SOD activity and TAC were detected in diabetic glands. CONCLUSIONS: Our data suggest that decreased M3 receptor-mediated parotid secretion in diabetic rabbits appears to be due to alterations in NO signaling, mainly due to iNOS induction, accompanied by elevated antioxidant response.

The effects of anti-hypertensives and type 2 diabetes on salivary flow and total antioxidant capacity.

OBJECTIVE: The present cross-sectional study aimed to determine the effect of first-line anti-hypertensive drugs (enalapril, metoprolol, and combinations of enalapril with metoprolol and/or hydrochlorothiazide) on salivary gland function and salivary total antioxidant capacity (TAC) in hypertensive patients with/without diabetes mellitus (DM) type 2. MATERIALS AND METHODS: Salivary gland function was measured as xerostomia (interview) and unstimulated whole saliva flow rate (UWSFR) in 447 subjects (387 hypertensive and 60 healthy). Salivary TAC was evaluated by spectrophotometric assay. RESULTS: Enalapril is not xerogenic, while metoprolol and drug combinations are. In the presence of DM type 2, all drugs, except metoprolol, had pronounced xerogenic effect. Binary logistic regression analysis found enalapril to be significantly associated with decreased risk of xerogenic effect development, while DM type 2 with increased risk. In the presence of enalapril in hypertensive patients with/without DM type 2 salivary TAC was similar to that in healthy subjects, while for metoprolol was reduced. CONCLUSIONS: Enalapril is not xerogenic but is antioxidant, which moderately reduces the risk of xerogenic effect development even in the presence of DM type 2. However, metoprolol and drug combinations exhibit xerogenic effect. In DM type 2, xerogenic effect of all drugs was pronounced except of metoprolol.

Maxillary infiltration anaesthesia by ropivacaine for upper third molar surgery.

The main purpose of this study was to assess the clinical efficacy and haemodynamic effects of ropivacaine for infiltration anaesthesia in patients undergoing surgical removal of upper third molars. The safety profile of ropivacaine was also studied by investigating the maximal venous plasma concentration of ropivacaine and the reactivity to ropivacaine of isolated human infraorbital arteries. Ropivacaine in concentrations of 0.5, 0.75 and 1% achieved dose-dependent parameters of maxillary infiltration aneasthesia, clinically relevant in concentrations 0.75 and 1%. Postoperative needs for analgesics were observed in 67-100% of patients. Haemodynamic parameters were stable during surgery with significant changes occuring 10 min after surgery. After maxillary infiltration of 2.0 ml 1% ropivacaine, the maximum venous plasma concentration (Cmax) was 82+/-15 microg/l. On isolated human infraorbital artery, ropivacaine (10(-4)M) induced endothelium-independent contraction. This study suggests that 0.75 and 1% ropivacaine offers adequate and safe intraoperative analgesia but not successful postoperative pain control for the surgical removal of upper third molars.

TMD chronic pain and masseter silent period in psychiatric patients on antidepressive therapy.

The aim of the study was to evaluate the long-term effects of antidepressive therapy on chronic pain and related disability, and masseter silent period in psychiatric depressive patients with temporomandibular disorders (TMD). The study included hospitalized psychiatric depressive patients on antidepressive therapy protocol (tetracyclic antidepressant-maprotiline and anxiolytic-diazepam) (n=30) and non-psychiatric patients seeking prosthodontic treatment (control group, n=38). TMD were diagnosed by Research Diagnostic Criteria for temporomandibular disorders proposed by Dworkin and LeResche. The surface electromyography was recorded from left and right masseter muscles and masseter inhibitory reflex (masseter silent period) was recorded after mechanical stimulation. The incidence of TMD appearance was very similar, of approximately 40% in both group of patients. The results of the study also indicated a higher prevalence of joint related TMD, a lower prevalence of muscular subtype of TMD and a lower grade of chronic pain and related disability in the psychiatric group of patients on antidepressive therapy in comparison with findings in the control group. In the patients on antidepressive therapy with TMD masseter silent period was not prolonged , while in the control group of patients with TMD the prolongation of the silent period was observed. The study provided evidence that long-term, combined therapy (maprotiline and diazepam) in psychiatric depressive patients significantly modulated signs and symptoms of TMD in comparison with the control group.

Lidocaine+clonidine for maxillary infiltration anaesthesia: parameters of anaesthesia and vascular effects.

The local anaesthetic and haemodynamic parameters achieved by lidocaine with clonidine or epinephrine, administered for maxillary infiltration anaesthesia, were studied in 40 patients (American Society of Anesthesiologists, physical status 1) who underwent upper third molar surgery. All patients received 2 ml of 2% lidocaine with clonidine (15 microg/ml; n=20) or epinephrine (12.5 microg/ml; n=20) in a randomized, double-blind fashion. Vascular effects were evaluated on the isolated human infraorbital arteries. The parameters of maxillary infiltration anaesthsia produced by a combination of lidocaine+clonidine were similar to those obtained with lidocaine+epinephrine. In both groups, haemodynamic parameters exhibited similar variations, with the exception of a significant reduction in heart rate and systolic blood pressure in the lidocaine+clonidine group and significant increase in heart rate in the lidocaine+epinephrine group, 10 min after surgery. Clonidine (10(-7), 10(-6) and 10(-5)M) produced an endothelium-independent vasocontractile effect on the isolated human infraorbital arteries. The results of this study indicate for the first time in dental anaesthesia that the lidocaine+clonidine combination could be a useful and safe alternative to lidocaine+epinephrine for intraoral infiltration anaesthesia.

Responses of the human submandibular artery to ACh and VIP.

Endothelial vasodilatory substances may play a central role in the local regulation of vascular tone. We hypothesized that these substances can mediate endothelium-dependent vasodilatory responses to acetylcholine (ACh) and vasoactive intestinal peptide (VIP) in the human submandibular artery. We evaluated the contributions of endothelial vasodilatory substances to vessel relaxation in response to ACh and VIP, using different inhibitors of endothelial vasodilation, the nitric oxide synthase inhibitor, the cyclo-oxygenase inhibitor, indomethacin, the potassium channel blocker, and 4-aminopyridine. ACh and VIP caused an endothelium- and concentration-dependent relaxation in this artery. ACh relaxation was completely blocked after the concomitant addition of N(G)-nitro-L-arginine and indomethacin. The vasorelaxant effect of ACh was not influenced by 4-aminopyridine. VIP relaxation was almost completely abolished by 4-aminopyridine, and was partly inhibited by N(G)-nitro-L-arginine, but was not affected by indomethacin. Thus, in the human submandibular artery, ACh and VIP produced endothelium-dependent vasodilation with different underlying mechanisms: release of nitric oxide (NO) and cyclo-oxygenase products for ACh, and release of NO and endothelium-derived hyperpolarizing factor for VIP.

Comparison of clonidine and epinephrine in lidocaine anaesthesia for lower third molar surgery.

The admixture of clonidine or epinephrine to lidocaine for inferior alveolar nerve block was studied with regard to onset, duration, intensity of anaesthesia, postoperative analgesia, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), ST segment depression > or =1 mm and cardiac arrhythmias. Forty healthy patients (ASA I) received 2 ml 2% lidocaine with clonidine (15 microg/ml; n = 20) or epinephrine (12.5 microg/ml; n = 20) in a double-blind fashion for lower third molar surgery. Duration and intensity were not different between groups, while onset was significantly different by subjective evaluation. The need for postoperative pain medication was significantly lower in the clonidine group. There was a significant decrease in SBP and MAP in both groups 35 min after administration of anaesthesia compared with basal values, while DBP was significantly lower only in the clonidine group. There was no significant difference in SBP, DBP and MAP between groups. HR was significantly increased in the epinephrine group 5 min after administration of anaesthesia and during surgery compared with the clonidine group and with basal values. The presented data suggest that clonidine could be a useful and safe alternative to epinephrine for intraoral block anaesthesia.

The effects of acute and chronic lithium treatment on rat submandibular salivation.

OBJECTIVE: Acute and chronic actions of lithium on salivation induced by agonists associated with receptor-linked hydrolysis of membrane inositol phospholipids (carbachol and phenylephrine) and by agonist linked to activation of adenylate cyclase (isoproterenol) were investigated. MATERIAL AND METHODS: In anaesthetized rats, submandibular salivation induced by intravenous injection of carbachol, phenylephrine and isoproterenol, was measured and expressed as volume of fluid (microl) elicited per 100 mg wet weight of each gland per minute. The experiments were repeated after acute and chronic treatment of lithium (7 mg kg(-1)). The results were analysed with unpaired t-test. RESULTS: Chronic, but not acute lithium treatment significantly decreases carbachol- and phenylephrine-induced salivation while isoproterenol-induced salivation was not changed neither after acute nor after chronic administration of lithium. CONCLUSION: The results suggest that hyposalivation during chronic lithium therapy could be mediated by alterations in the phosphatidylinositol cycle and a consequent lack of inositol after agonist stimulation.

The relaxant effect of vasoactive intestinal polypeptide in the isolated canine uterine artery: the role of endothelium.

The purpose of this study was to examine the effect of vasoactive intestinal polypeptide (VIP) on the uterine artery obtained from non-pregnant dogs. VIP (3 x 10(-9)-3 x 10(-7) M) induced concentration-dependent relaxation in canine uterine arteries with intact endothelium, pre-contracted with 10(-5) M phenylephrine (pEC(50) = 7.52 +/- 0.02, maximal response was 82.19 +/- 2.15%, n = 36). The administration of the cyclooxygenase inhibitor indomethacin (10(-5) M) or 4-aminopyridine (4-AP), a blocker of potassium channels (10(-5) M), did not modify the relaxation induced by VIP. Contrary to this, N(G)-nitro-L-arginine (L-NOARG) (10(-5) M) inhibited relaxation is evoked by VIP. Indomethacin applied with L-NOARG did not provoke further inhibition of VIP-induced relaxation. In the presence of both L-NOARG and L-NOARG + indomethacin, 4-AP led to the further inhibition of VIP-induced relaxation of canine uterine artery. It is concluded that VIP induces endothelium-dependent relaxation of uterine arteries of non-pregnant dogs, which can be entirely explained by the production of nitric oxide (NO) from the endothelial cells. We proposed that when NO synthesis is inhibited, VIP induces further relaxation, independent of the edothelium-derived relaxing factors, probably through activation of K(+) channels.

Endothelium-dependent relaxation of canine uterine artery in response to acetylcholine: the possible involvement of alternative pathways.

The effect of acetylcholine on the isolated, pre-contracted, uterine artery of non-pregnant dog was investigated. Acetylcholine-induced concentration-dependent relaxation of isolated canine uterine artery with endothelium (pEC50 = 6.48 +/-0.01, n = 37) and was without effect on arterial segments denuded of endothelium. Indomethacin, 4-aminopyridine (10-5 m) and pre-contraction with K+-rich Krebs-Ringer bicarbonate solution had no effect on acetylcholine-induced relaxation. NG-nitro-l-arginine (l-NOARG) (10-5 m) inhibited relaxation evoked by acetylcholine. Indomethacin applied with l-NOARG led to further inhibition of acetylcholine-induced relaxation. In the presence of both l-NOARG and indomethacin, 4-aminopiridine did not provoke further inhibition of acetylcholine-induced relaxation of canine uterine artery. It is concluded that the acetylcholine-induced relaxation of canine uterine artery is probably mediated by endothelial production of nitric oxide (NO). However, if NO-synthase is inhibited, acetylcholine-induced vasorelaxation may be, in part, mediated through activation of cyclooxygenase pathway.

Effects of captopril and bradykinin on chorda tympani-induced salivation in cat.

The effects of captopril and bradykinin on chorda tympani-induced salivation were studied in the submandibular gland of anesthetized cat. Captopril and bradykinin, but not des-Arg9-bradykinin, increased salivation evoked by electrical stimulation of chorda tympani. These potentiated effects of captopril and bradykinin were suppressed by Hoe-140, a kinin B2 receptor antagonist, or by concomitant addition of N(G)-nitro arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, and aspirin, a cyclooxygenase inhibitor. It appears that captopril potentiates chorda tympani-induced salivation through endogenously accumulated bradykinin, which acts on kinin B2 receptors, mediating production of nitric oxide and cyclooxygenase products.

Spectrophotometric and electrochemical study of protolytic equilibria of some oximes-acetylcholinesterase reactivators.

Newly synthesized oximes, mono and bis imidazole derivatives, which promise to be more effective acetylcholinesterase reactivators than standard antidotes used, were investigated by spectrophotometric and electrochemical methods. The electrochemical investigations confirmed the existence of overlapping equilibria, obtained by spectrophotometric methods. Dissociation constants of those oximes were also obtained by numerical treatment of overlapping equilibria, using the Lavendberg Marquardt least square method, and when compared with the same for some similar compounds, were found to be very effective acetylcholinesterase reactivators. The distribution of ionic forms of the investigated oximes, as a dependence of pH values, was calculated from the obtained values of dissociation constants. The results indicated that many oxime anions will be available at physiological pH 7.4 and a relative increased ability to reactivate inhibited acetylcholinesterase could be expected.

Carbachol-induced oxygen consumption in slices from developing rat submandibular and parotid glands.

In contrast to the submandibular gland, the developing rat parotid gland shows refractoriness to cholinergic secretagogues until 2 wks of age. To assess the underlining mechanism of this refractoriness, I investigated changes in oxygen consumption as a function of animal age in slices from rat submandibular and parotid glands, measuring both basal and carbachol-stimulated levels. The oxygen consumption was determined by a direct manometric method in the Warburg apparatus. Carbachol-induced oxygen uptake in submandibular gland slices was observed by 1 day of age and reached the adult level of stimulation by 3 wks of age. In the parotid gland, carbachol failed to stimulate oxygen uptake in the early post-natal period, and the first response was detected at 2 wks of age, reaching the adult level at 4 wks of age. Para-fluorohexahydro-sila-diphenidol (pFHHSiD), a selective M3 antagonist, inhibited carbachol-induced oxygen uptake in both glands, while pirenzepine, a selective M1 antagonist, had no effect, suggesting that the M3 muscarinic receptors are involved in this process. The respiratory effect of carbachol, in both glands, was inhibitable by ouabain and, to a lesser extent, by furosemide, indicating that carbachol-enhanced oxygen uptake is due to Na,K-ATPase and that the furosemide-sensitive co-transport of Na+ entry is underdeveloped in immature cells. The ouabain-sensitive Na,K-ATPase activity in the parotid gland increased from birth until 28 days of age. At the time of parotid gland refractoriness to carbachol, Ca2+ ionophore A23187 caused an increase of oxygen uptake only in the presence of extracellular Ca2+. In the presence of carbachol, the effect of ionophore was significantly higher than that of ionophore alone. These results raise the possibility that the refractoriness of the parotid gland to carbachol is due to the inability of carbachol to increase Ca2+ uptake rather than to the lack of distal limb, which resides on the pathway from receptor stimulation to Na,K-ATPase activation.

Stable isotopes in periphyton and sediments from the Kolubara River and its tributaries.

A series of periphyton, sediment, and water samples has been collected from the Kolubara River and its tributaries at selected locations, characterized by heavy industrialization, and analysed for stable isotopes by X-ray-fluorescence spectrometry. The results of measurements for stable metals revealed that the anthropogenic contribution essentially overwhelms the natural system of the catchment. Thus, concentrations of heavy metals near points of industrial discharge were significantly higher than background concentrations. The existing primary and secondary waste water-treatment plants associated with heavy industry of the area must therefore be revived, and control should be instituted at the sources of pollution. The bioaccumulation factors (BF), and sediment distribution coefficients (K(D)), and concentration ratios (CR) for sixteen stable isotopes were calculated. It is shown that the concentration ratios of periphyton over sediment for Mn, Zn, As, Sb, I, Ba, and Pb exceeded unity. Furthermore, the recorded partition coefficients were indicative of the distribution and mobility of the stable metals in the Kolubara River environment.

Differentiation of alpha adrenoceptors mediating increase of oxygen consumption in rat submandibular salivary gland slices.

Clonidine, noradrenaline and adrenaline (in the presence of propranolol), but not phenylephrine and methoxamine, stimulated an increase in the oxygen consumption of these slices that was blocked by yohimbine but not by prazosin. The stimulation was inhibited by ouabain and required the presence of Ca2+ in the incubation medium. The calcium ionophore A 23187 stimulated oxygen consumption in the tissue slices and enhanced the respiratory effect of clonidine. Atropine and (D-Pro2, D-Trp7.9)-substance P failed to block the respiratory response to clonidine in concentrations that inhibited the respiratory effects of carbachol and substance P, respectively. Release of acetylcholine from the unstimulated gland slices was reduced by clonidine or Ca2+ omission. Yohimbine prevented the clonidine effect and stimulated acetylcholine resting release. Nifedipine did not affect either the release of acetylcholine or the clonidine-induced reduction of acetylcholine release but blocked the oxygen uptake due to clonidine or to release acetylcholine.