Influence of central nicotinic receptors on arachidonylcyclopropylamide (ACPA)-induced antinociception in mice

The nicotinic cholinergic receptors have been reported to be involved in several actions of cannabinoids (e.g., bradycardia, hypothermia). However, the influence of central cholinergic system on cannabinoids antinociceptive effect has not been reported. This study investigated the possible part played by nicotinic cholinergic modulator drugs on the antinociceptive effect of central administration of arachidonylcyclopropylamide (ACPA) in mice. The antinociceptive effects of intracerebroventricular (i.c.v.) administration of ACPA using the formalin test have been studied in mice. The effects of nicotine or mecamylamine (a nicotinic cholinergic antagonist) on ACPA analgesia are also studied. i.c.v. administration of ACPA (0.004-1 microg/mice) induced antinociceptive effect in mice. i.c.v. administration of nicotine (0.1 or 0.5 microg/mice) or mecamylamine (2 microg/mice) potentiated or antagonized ACPA antinociceptive effects, respectively. It is concluded that ACPA-induced analgesia is influenced by central nicotinic cholinergic activity.     

Mouth breathing increases the pentylenetetrazole-induced seizure threshold in mice: a role for ATP-sensitive potassium channels

Nasal obstruction and consequent mouth breathing have been shown to change the acid–base balance, producing respiratory acidosis. Additionally, there exists a large body of evidence maintaining that acidosis affects the activity of ATP-sensitive potassium (K_ATP) channels, which play a crucial role in the function of the central nervous system (CNS), for example, in modulating seizure threshold. Thus, in the study described here, we examined whether mouth breathing, induced by surgical ligation of nostrils, could affect the seizure threshold induced by pentylenetetrazole in male NMRI mice. Using the selective K_ATP channel opener (diazoxide) and blocker (glibenclamide), we also evaluated the possible role of K_ATP channels in this process. Our data revealed that seizure threshold was increased 6 to 72 hours after nasal obstruction, reaching a peak 48 hours afterward, compared with either control or sham-operated mice (P < 0.01). There was a significant decrease in pH of arterial blood samples and increase in CO₂ partial pressure (PCO₂) during this time. Systemic injection of glibenclamide (1 and 2 mg/kg, ip, daily) significantly prevented the increase in seizure threshold in 48-hour bilaterally nasally obstructed mice, whereas it had no effect on seizure threshold in sham-operated mice. Systemic injection of diazoxide (25 mg/kg, ip, daily) had no effect on seizure threshold in all groups, whereas higher doses (50 and 100 mg/kg, ip, daily) significantly increased seizure threshold in both 48-hour-obstructed and sham-operated mice. The decrease in seizure threshold induced by glibenclamide (2 mg/kg, ip, daily) was prevented by diazoxide (25 mg/kg, ip, daily). These results demonstrate for the first time that mouth breathing, which could result in respiratory acidosis, increases seizure threshold in mice and K_ATP channels may play a role in this effect.     

Mechanics of breathing after surgical ligation of patent ductus arteriosus in newborns with respiratory distress syndrome

The aim of the study was to detect changes in pulmonary function following ligation of a patent ductus arteriosus (PDA). Pulmonary function was recorded in 16 newborns (birth weight 1,081 +/- 166 g, gestational age 27.6 +/- 1.7 weeks) before and after ligation. No change in resistance of airways or mean airway pressure was observed. We found an increase in dynamic compliance (Cdyn) of 77% (p < 0.01), in tidal volume (TV) of 29% (p = 0.004), and in minute ventilation (MV) of 17% (p < 0.01) after the procedure. We demonstrated that pulmonary function improves after surgical ligation of the PDA. Because of considerable variation in intubated and spontaneously breathing premature newborns, we recommend the analysis of three main parameters: Cdyn, TV and MV for estimation of pulmonary mechanics in these infants.     

The 35% carbon dioxide test in stress and panic research: overview of effects and integration of findings

The carbon dioxide test--a vital capacity breath of air containing 35% carbon dioxide (CO(2))--provokes panic attacks in many individuals with panic disorder (PD). It has thus been extensively used as an experimental model of panic and less frequently as a clinical method of provoking symptoms for interoceptive exposure treatment. Recently, stress researchers have suggested another use for the CO(2) test: that of an acute physiological stressor indexing the human stress response. The purpose of this review is to synthesize findings about the effects of the CO(2) test from both the panic and stress literatures in order to advance understanding about this increasingly popular test. Both panic and stress researchers have examined the fleeting effects of the CO(2) test, finding that the test engenders transient breathlessness, dizziness, and minor anxiety in most participants and panic attacks in those with or at risk for PD. Physiological measurements after the test indicate a brief homeostatic disruption in many bodily systems, including increased respiration, systolic blood pressure, and noradrenaline, and decreased heart rate. Most studies indicate increased cortisol. Possible benefits of integrating findings from the panic and stress research lines, given their common use of the CO(2) test, are discussed.     

Detection of <Emphasis Type=Italic>Theileria annulata</Emphasis> by the PCR-RFLP in ticks (Acari,Ixodidae) collected from cattle in West and North-West Iran

The presence of potential vectors, ticks, and susceptible hosts of bovine malignant theileriosis in all parts of Iran pose a real threat to food animal industry. The present study was conducted to determine the infection rate of ticks collected from naturally occurring bovine theileriosis in West and North-West Iran. Two hundred and thirty seven cattle suspected of suffering from theileriosis were investigated for the presence of Theileria annulata in the blood smears and any tick species on their body. In this study, 402 ticks were obtained from 99 cattle. The examination of 402 ticks by polymerase chain reaction (PCR) using primers derived from the gene encoding heat shock protein70 (Hsp70) revealed that 39.9% of Hyalomma anatolicum anatolicum, 3.5% of H. asiaticum asiaticum, and 18.2% H. anatolicum excavatum, were infected with T. annulata. The results suggest that H. a. anatolicum may play a major role in transmission of T. annulata infection in Iran. Finally, digestion of the PCR products of T. annulata with two different restriction enzymes produced only a single pattern.     

Not all polyanions induce a J-band in the dye pseudoisocyanine

N,N′-diethylpseudoisocyanine chloride (PIC) forms compounds with various vinyl poly+ and DNA, but the shapes of the spectra of the dye-polyanion compounds depend on the nature of the polyanions. PIC forms compounds with 1:1 polyanion/dye stoichiometries with DNA (native and denatured), polymethacrylate and poly(styrenesulfonate); and the spectra of these compounds do not show any pronounced metachromasia or red-shifted J-band. Polyacrylate and poly(vinyl sulfate) form compounds with polyanion/dye stoichiometry of 2:1, and give spectra with extremely sharp and red-shifted J-band. This is the first report on the relation between the polyanion/PIC stoichiometry and the depiction of the J-band of the resulting compound.