Action of serotonin on the laryngeal airway in anaesthetized cats

BACKGROUND: Electroencephalography (EEG) screening of pilot candidates has long been established but remains controversial. The EEG records of 0-15% of the test population demonstrate the presence of brief periods of slow waves (theta, 4-7.9 Hz and delta, 0-3.9 Hz). The significance of these EEG findings for pilot selection has not been defined. HYPOTHESIS: We investigated whether the existence of slow waves in the EEG records of cadet pilots was related to differences in their cognitive performance. If so, the EEG could serve as a tool for cognitive assessment in candidate pilot screening. The relationship between spontaneous EEG slowing and cognitive performance has not been investigated although there is evidence of EEG slowing during the performance of short-term memory tasks. METHODS: Some 116 screening EEG records were re-evaluated for the presence of slow wave activity. Cadets with positive records and a control group performed: a) a modified version of Sternberg's visual memory scanning task on a PC computer; and b) the auditory "OddBall" behavioral task for eliciting the P300 evoked response using the Nicolet Spirit Evoked Potential System. RESULTS: Analysis of the behavioral and electrophysiological data was divided in EEG groups: a) Normal; b) Bilateral slowing only during hyperventilation; c) Bilateral slowing; d) Slowing with right dominance; and e) Slowing with left dominance, showed no significant difference among the groups for all parameters measured. CONCLUSIONS: Brief periods of bilateral or focal EEG slow activity in the records of pilot cadets could not predict differences in cognitive function as this was assessed in these experiments. Specific neuropsychological screening procedures might be more valuable for this purpose than the standard EEG screening.     

Audience effects in anticipatory learning: A comparison of drive and practice-inhibition analyses.

96 undergraduates learned a list of nonsense syllables in the presence of the experimenter or alone, with half of each group instructed to anticipate the syllables aloud before presentation. Independent effects on learning were found for practice inhibition and for increased drive. Drive effects occurred when Ss' overt anticipatory responses were being monitored during learning, and practice-inhibition effects resulted from the presence of an audience. These inhibition effects are discussed in terms of self-conscious behavior induced by an audience. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional properties of postganglionic sympathetic neurones supplying the submandibular gland in the anaesthetized rat

Sympathetic neurones supplying the submandibular salivary gland innervate blood vessels, secretory and myoepithelial cells. Here we examined whether these functionally different sympathetic neurones show distinct reflex response patterns. In anaesthetized rats, single unit activity was recorded from postganglionic axons projecting to the gland. Neurones were tested for their responses to stimulation of baroreceptors, cutaneous nociceptors and cold receptors and to gustatory stimuli applied to the tongue. Respiratory modulation was also analysed. Only a few postganglionic neurones identified electrically (5-10%) were spontaneously active. They were excited by noxious and cold stimuli, inhibited by baroreceptor stimulation and exhibited respiratory modulation. None of the units responded to gustatory stimuli. Thus, in anaesthetized rats spontaneously active sympathetic neurones supplying the submandibular gland behave like vasoconstrictor neurones. Sympathetic neurones with other functions are probably silent.     

Bronchospasmolytic and cardiovascular effects in anaesthetized cats of ibuterol and terbutaline given intravenously and after inhalation: drug and prodrug compared

By increasing the number of display items and the physical similarity between the target and the irreveland items it was possible to vary the difficulty of target selection in a visual-search task. The results showed that the accuracy with which the target was located declined as target selection became more difficult. On the other hand, estimates of the cumulative probability and the probability distributions of times necessary to form the icon indicated that these times were not influenced by changes in the difficulty of the task. The latter result supports Neisser's suggestion that the information processing carried out during the first stage analysis can be attributed to the action of a distinct cognitive mechanism.     

Histocytochemical and immunohistochemical studies related to the role of glycogen in human developing digestive organs

To elucidate the role of glycogen in the epithelium of developing digestive organs, we investigated the appearance of glycogen and glycogen phosphorylase (GP) in these organs. We studied 64 externally normal human embryos at Carnegie stages 13-23 (5.1-28.0 mm in crown-rump length, 4-8 weeks of gestation) by histocytochemical staining for glycogen and immunohistochemical staining with antibodies against two isoenzymes of GP: brain-type (BGP) and muscle-brain-type (MBGP) GP. At stage 13, glycogen appeared in the epithelium of the digestive tract and the parenchyma of the pancreas. As development advanced, glycogen granules increased in number and size in these tissues, and they became evenly distributed in the epithelium of the digestive tract as either single particles or aggregates, as deduced by electron microscopy at late embryonic stages. Immunoreactivity specific both for BGP and for MBGP was detected in the digestive tract and the pancreas from stage 13. As development advanced, both BGP- and MBGP-immunoreactive cells increased in number and in immunoreactivity, and the number of MBGP-immunoreactive cells became larger than that of BGP-immunoreactive cells. By contrast, in hepatic cells, which serve as a major storage site for glycogen in adults, glycogen was detected only from stage 20, in smaller amounts, without formation of aggregates, and no immunoreactivity specific for BGP or MBGP was apparent throughout the embryonic stages examined. Thus, in the epithelium of the digestive tract and the parenchyma of the pancreas, but not in hepatic cells, the appearance and localization of GP coincided almost exactly with that of glycogen. These observations suggest that glycogen in the epithelium of the digestive tract and the parenchyma of the pancreas has not only been synthesized but also degraded from an early embryonic period and may, thus, be related to active cellular metabolism that is specific for embryonic development, including proliferation of the epithelium and interactions between epithelium and mesenchyme.     

Effects of prostaglandins and nitric oxide on the renal effects of angiotensin II in the anaesthetized rat

1. The potential influences of nitric oxide (NO) and prostaglandins on the renal effects of angiotensin II (Ang II) have been investigated in the captopril-treated anaesthetized rat by examining the effect of indomethacin or the NO synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME), on the renal responses obtained during infusion of Ang II directly into the renal circulation. 2. Intrarenal artery (i.r.a.) infusion of Ang II (1-30 ng kg(-1) min(-1)) elicited a dose-dependent decrease in renal vascular conductance (RVC; -38+/-3% at 30 ng kg(-1) min(-1); P < 0.01) and increase in filtration fraction (FF; +49+/-8%; P < 0.05) in the absence of any change in carotid mean arterial blood pressure (MBP). Urine output (Uv), absolute (UNaV) and fractional sodium excretion (FENa), and glomerular filtration rate (GFR) were unchanged during infusion of Ang II 1-30 ng kg(-1) min(-1) (+6+/-17%, +11+/-17%, +22+/-23%, and -5+/-9%, respectively, at 30 ng kg(-1) min(-1)). At higher doses, Ang II (100 and 300 ng kg(-1) min(-1)) induced further decreases in RVC, but with associated increases in MBP, Uv and UNaV. 3. Pretreatment with indomethacin (10 mg kg(-1) i.v.) had no significant effect on basal renal function, or on the Ang II-induced reduction in RVC (-25+/-7% vs -38+/-3% at Ang II 30 ng kg(-1) min(-1)). In the presence of indomethacin, Ang II tended to cause a dose-dependent decrease in GFR (-38+/-10% at 30 ng kg(-1) min(-1)); however, this effect was not statistically significant (P=0.078) when evaluated over the dose range of 1-30 ng kg(-1) min(-1), and was not accompanied by any significant changes in Uv, UNaV or FENa (-21+/-12%, -18+/-16% and +36+/-38%, respectively). 4. Pretreatment with L-NAME (10 microg kg(-1) min(-1) i.v.) tended to reduce basal RVC (control -11.8+/-1.4, +L-NAME -7.9+/-1.8 ml min(-1) mmHg(-1) x 10(-2)), and significantly increased basal FF (control +15.9+/-0.8, +L-NAME +31.0+/-3.7%). In the presence of L-NAME, renal vasoconstrictor responses to Ang II were not significantly modified (-38+/-3% vs -35+/-13% at 30 ng kg(-1) min(-1)), but Ang II now induced dose-dependent decreases in GFR, Uv and UNaV (-51+/-11%, -41+/-14% and -31+/-17%, respectively, at an infusion rate of Ang II, 30 ng kg(-1) min(-1)). When evaluated over the range of 1-30 ng kg(-1) min(-1), the effect of Ang II on GFR and Uv were statistically significant (P < 0.05), but on UNaV did not quite achieve statistical significance (P=0.066). However, there was no associated change in FENa observed, suggesting a non-tubular site of interaction between Ang II and NO. 5. In contrast to its effects after pretreatment with L-NAME alone, Ang II (1-30 ng kg(-1) min(-1)) failed to reduce renal vascular conductance in rats pretreated with the combination of L-NAME and the selective angiotensin AT1 receptor antagonist, GR117289 (1 mg kg(-1) i.v.). This suggests that the renal vascular effects of Ang II are mediated through AT1 receptors. Over the same dose range, Ang II also failed to significantly reduce GFR or Uv. 6. In conclusion, the renal haemodynamic effects of Ang II in the rat kidney appear to be modulated by cyclooxygenase-derived prostaglandins and NO. The precise site(s) of such an interaction cannot be determined from the present data, but the data suggest complex interactions at the level of the glomerulus.     

A comparison of evening primrose oil and sunflower oil for the management of papulocrustous dermatitis in cats

Eleven cats with papulocrustous dermatitis were randomly assigned to one of two groups and supplemented with either evening primrose oil or sunflower oil for 12 weeks. Clinical scores were assessed at intervals of three weeks and blood samples were taken for the analysis of plasma and erythrocyte fatty acid concentrations. The cats in both groups improved during the period of treatment and the concentration of linoleic acid in erythrocyte phospholipid increased in the cats fed evening primrose oil. Six weeks after the supplement was withdrawn the cats fed evening primrose oil had deteriorated less than those fed sunflower oil.     

A comparison of the effects of tramadol and morphine on gastric emptying in man

In a previous study using an electrical bioimpedance technique and the paracetamol absorption test, we demonstrated that 0.09 mg.kg-1 of morphine delayed gastric emptying in healthy human volunteers. The aim of this study was to investigate whether analgesic doses of tramadol would cause a delay in gastric emptying similar to conventional opioids. Using the same volunteers and techniques as in our previous study, placebo or tramadol (1 mg.kg-1) was given in a randomised, double-blinded, cross-over placebo-controlled study. Gastric emptying was measured concurrently by a noninvasive epigastric bioimpedance technique and by the paracetamol absorption test. After the ingestion of 500 ml of deionised water plus paracetamol 1.5 g, the mean (SEM) time taken for gastric volume to decrease to 50% (t0.5) was recorded. No difference in gastric emptying rates (t0.5) between placebo, 7.7 (1 min), and tramadol, 9.5 (2 min), was noted. In our previous study, morphine prolonged t0.5 to 21 (3) min (p < 0.03). The maximum concentration and area under the curve of serum paracetamol concentrations following morphine were significantly different from placebo (p < 0.05) and tramadol (p < 0.05). We conclude that tramadol at a dose of 1 mg.kg-1 does not delay gastric emptying in humans.     

Vincristine disturbs spontaneous firing of the afferent nerve fibre in ampullary electroreceptor organs

Ampullary electroreceptor organs of the catfish were apically exposed to 0.3 mM vincristine in order to investigate the part played by the microtubular system in stimulus transduction. The main effects were repetitive firing of the afferent fibre, a reduction of the mean spontaneous activity and a reduction of the spike amplitude two to four days after exposure to vincristine. The mean sensitivity was less susceptible to vincristine than the spontaneous activity. Since the shape of the frequency curves remained unchanged and similar effects as described above were also observed after denervation, we conclude that vincristine most likely does not affect electroreceptor cell functioning, but causes degeneration of the afferent fibre.     

Maternal effects on the development of spontaneous hypertension.

Cross-fostering spontaneously hypertensive rat (SHR) pups to Wistar-Kyoto (WKY) normotensive mothers influenced physical development, resting mean arterial pressure and heart rate, open-field behavior, and sympathetic-adrenal medullary responses to stressors. Cross-fostering WKY pups to SHR mothers at birth, however, did not affect these developmental processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The protective effects of CP-060S on ischaemia- and reperfusion- induced arrhythmias in anaesthetized rats

1. CP-060S is a novel sodium and calcium overload inhibitor, and is also characterized as a calcium channel blocker. As these activities have each been shown independently to ameliorate ischaemia damage in the myocardium, the combination may synergistically exert cardioprotection. In this study, therefore, the protective effect of CP-060S against ischaemia- and reperfusion-induced arrhythmia was evaluated in anesthetized rats. 2. Rats were anaesthetized with pentobarbitone, and the left anterior descending coronary artery was occluded for either 5 min with subsequent reperfusion (a reperfusion-induced arrhythmia model) or 30 min without (an ischaemia-induced arrhythmia model). All drugs were intravenously administered 1 min before the onset of occlusion. 3. In the reperfusion-induced arrhythmia model, the animals in the vehicle-treated group exhibited ventricular tachycardia (VT) in 100%, ventricular fibrillation (VF) in 89%, and death caused by sustained VF in 56%. CP-060S (30-300 microg kg(-1)) dose-dependently suppressed the incidences of arrhythmias. Significant decreases occurred at 100 microg kg(-1) in VF (incidence: 42%) and mortality (8%), and at 300 microg kg(-1) in VT (50%), VF (33%) and mortality (8%). This protective effect of CP-060S was 10 times more potent than that of a pure calcium channel blocker, diltiazem (30-1000 microg kg(-1)) we tested, in terms of effective dose ranges. As both drugs decreased myocardial oxygen consumption estimated by rate-pressure product to a similar extent, the calcium channel blocking activity of CP-060S would not seem to be sufficient to explain its potency. 4. In the same model, co-administration of ineffective doses of diltiazem (300 microg kg(-1)) and a sodium and calcium overload inhibitor, R56865 (100 microg kg(-1)), produced significant suppression of VT (incidence: 62%), VF (46%) and mortality (8%). By contrast, co-administration of R56865 at the same dose with CP-060S (300 microg kg(-1)) did not add to the effect of a single treatment of CP-060S. 5. In the ischaemia-induced arrhythmia model, CP-060S (300 microg kg(-1)) significantly decreased the incidence of VF from 75% to 29%, whereas diltiazem (1 mg kg(-1)) was ineffective. 6. These results suggest that CP-060S inhibits both ischaemia- and reperfusion-induced arrhythmia. The combination of the calcium channel blocking effect and the calcium overload inhibition was hypothesized to contribute to these potently protective effects.     

Pharmacokinetics and effects of intravesical oxybutynin on the paediatric neurogenic bladder

We have recently shown that the Ca2+ response in endothelial cells evoked by readdition of Ca2+ to the medium after store depletion caused by a submaximal concentration of agonist can involve Ca2+ release from Ca2+ stores sensitive to both inositol 1,4, 5-trisphosphate and ryanodine. The present experiments were performed to determine whether this mechanism might also exist in other types of cell. For this purpose, we used the human carcinoma cell line A431, which has a varied resting [Ca2+]i. We found that the amplitude of the Ca2+ response evoked by Ca2+ readdition did not correlate with the amplitude of the preceding UTP-evoked Ca2+ release, but did positively correlate with the initial [Ca2+]i. An inspection of the two patterns of response seen in this study (the large biphasic and small plateau-shaped Ca2+ responses) revealed that there is an accelerating rise in [Ca2+]i during the biphasic response. Application of ryanodine during the plateau-shaped Ca2+ response reversibly transformed it into the biphasic type. Unlike ryanodine, caffeine did not itself evoke Ca2+ release, but it caused a further [Ca2+]i rise when [Ca2+]i had already been elevated by thapsigargin. These data suggest that in A431 cells, as in endothelial cells, the readdition of Ca2+ after agonist-evoked store depletion can evoke Ca2+-induced Ca2+ release. This indicates that Ca2+ entry may be overestimated by this widely used protocol.     

A comparison of the effects of training and secondary tasks on tracking behavior.

In attempting to estimate what kind of a mechanism would best replace the human operator in a man-machine system, 6 sailors operated radar sets while their performance was studied by electronic computers (analog). The effects of training and secondary scores were studied in terms of errors. The type of mechanism it would take to replace the man depended upon the level of training the man had received. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of aging on the rat bladder and its innervation

1) Measurements of the cystometrogram, of the responsiveness of bladder muscle to pelvic nerve efferent stimulation and of the sensitivity of the pelvic nerve afferents to pressure and volume during distensions have been made in the bladders of young adult (2-3 months) and aged (26-29 months) rats, anesthetized with mixtures of urethane and chloralose. 2) The pressure-volume relationship differed in young adult and aged rats. The bladders of the aged rats held up to nearly six times the volume of the young animals, and these volumes were accommodated at lower pressures in the aged animals. The pressure at which micturition contractions appeared was similar in young adult and aged animals. 3) The passive pressure associated with each of a series of distending volumes was recorded when a pelvic nerve was cut unilaterally. The distal cut end of this cut pelvic nerve was stimulated for 10 s at 20 Hz, using square wave pulses of 10 V and 1.0 ms. The active pressure-volume relationship was constructed from this data. Both the active and the passive relationships were shifted to the right in the aged animals, and it was evident that aging was associated with a reduction in the maximal pressure generated during pelvic nerve stimulation. Also the change in intravesical pressure induced by bladder contraction was less in aged animals. 4) The most sensitive mechanoreceptor afferents appear to have pressure and volume thresholds that do not change significantly during aging. While the distension-sensitive afferents in the pelvic nerve appear to have a similar sensitivity to intravesical pressure in young adult and aged rats, they were less able to monitor volume in the aged animals. The stimulus response relationship for volume was often less steep in the aged animals. 5) In this study, aging was shown to be associated with a large increase in bladder volume and a reduced sensitivity of pelvic nerve afferents to volume, and a reduced ability to raise bladder pressure during contraction of bladder smooth muscle. The changes in bladder function associated with aging are discussed.     

Testosterone has potent, selective effects on the morphology of pelvic autonomic neurons which control the bladder, lower bowel and internal reproductive organs of the male rat

Although gonadal steroids are important determinants of the development and activity of various neuronal circuits in the brain and spinal cord, their function has been relatively poorly studied in the peripheral nervous system. In the present work, the effects of pre- and postpubertal castration were examined on the morphology of autonomic neurons that supply pelvic visceral organs in male rats. These neurons were identified by peripheral injection of fluorescent retrograde tracers and, in the major pelvic ganglion, were further classified as sympathetic or parasympathetic by means of immunostaining for tyrosine hydroxylase. Sizes of ganglion cell somata were indicated by areas of nucleated profiles in cryosections. The results show that, irrespective of whether castration was carried out at two or seven weeks-of-age, noradrenergic pelvic neurons that supply the vas deferens, prostate gland, urinary bladder or colon achieved only approximately 60% of the size of those in unoperated controls. In contrast, cholinergic pelvic neurons were unaffected by castration unless they supplied reproductive targets. Pre- and paravertebral sympathetic neurons that supplied the pelvic viscera were only slightly smaller following castration or were unchanged, depending on their target. All effects of castration were prevented by testosterone replacement following surgery. Androgen receptor-immunoreactivity was particularly prevalent in the nuclei of some pelvic ganglion neurons. The studies suggest that circulating androgens are essential for the maturation and maintenance of the structure of select groups of autonomic neurons that supply the viscera. The presence of androgen receptor immunoreactivity in many of these neurons indicates that direct neuronal effects of androgens are possible. However this does not exclude other less direct mechanisms of steroid action on neurons, such as by an effect on target organs, neurotrophic factor release or peripheral vascular supply. These studies point to the androgenic steroids as potentially important determinants of autonomic reflex function.