Activity Of Various Parts Research Articles

Direct inhibitory effect of erythromycin on the gallbladder muscle

Erythromycin, a macrolide antibiotic, stimulates motor activity in various parts of the gastrointestinal tract in humans and animals. This effect of erythromycin resembles that of motilin, a gastrointestinal hormone, in evoking contractions similar to phase 3 activity of the migrating motor complex. Motilin induces contractions in the canine gallbladder but fails to evoke any response, either in vivo or in vitro, in the human gallbladder. Surprisingly, erythromycin stimulates human gallbladder emptying in healthy volunteers and in persons with diabetic autonomic neuropathy. In the present study we examined the effect of erythromycin on chemically and electrically evoked contractions of isolated gallbladders from guinea pigs and humans by use of isometric force measurements. Carbachol, a muscarinic cholinergic agonist, evoked gallbladder contractions that were diminished by erythromycin in a concentration-dependent manner: at 200 μmol/L the contractions were 86% ± 20% of the control response, at 500 μmol/L they were 63% ± 21% of control, and at 1000 μmol/L they were 41% ± 20% of control ( P <0.05, N = 10, mean ± standard deviation). Electrically evoked gallbladder contractions were reduced to 68% ± 18% of the control response with the addition of 500 μmol/L of erythromycin and to 56% ± 19% of control after the addition of 1000 μmol/L ( P <0.05, N = 8). Guinea pig but not human gallbladders contracted after stimulation with the alpha-adrenergic agonist phenylephrine. Erythromycin reduced these contractions in a concentration-dependent manner but had no effect on gallbladder contractions induced by bradykinin. In human gallbladder strips, erythromycin at 500 μmol/L reduced the contractile response to electrical stimulation to 71% ± 16% of the control value (N = 10 [5 patients], P <0.01) and the carbachol-evoked contractions to 53% ± 24% ( P <0.01, N = 32). The inhibitory effect of erythromycin persisted in the presence of the nerve blocker tetrodotoxin at 1 μmol/L. It is concluded that erythromycin has a direct inhibitory effect on guinea pig and human gallbladder contractions.

Characteristics of atrial activation sequence of atrial fibrillation and flutter in a canine model

In order to induce either atrial fibrillation (af) or atrial flutter (AF) in 22 dogs under pentobarbital anesthesia, a right atriotomy parallel to the sulcus terminalis was performed, but closed with running sutures. Effective refractory periods (ERP) were measured in the sites of the appendages and the bodies in both atria. Further, we developed a computerised mapping system which enabled us to reveal sequential activation of various parts of the heart. As a result, we could assess the circuit of excitation which gave rise to AF. AF occurred in 7 of the 22 dogs, and af in the remaining 15 dogs. It was revealed that during AF there was a counterclockwise (5 dogs) or clockwise (2 dogs) reentrant pathway involving the right atrial free wall and superior vena caval orifice with consequent left atrial activation. Although standard limb lead electrocardiogram showed af, all dogs with sustained af had a regular activation sequence in the left atrium [at a cycle length (period) of 140.1 +/- 16.9 msec, arising either in the left atrial appendage (8 dogs) or adjacent to the left pulmonary vein (7 dogs)]. However, 12 of the 15 dogs had a chaotic activation sequence whereas the other 3 dogs showed a regular activation sequence in the right atrium. Statistically, during AF there was no significant difference between RA ERP (153.2 +/- 12.6 msec), LA ERP (146.4 +/- 14.4 msec) and LA cycle length (period) (140.1 +/- 16.9 msec). During af, there was no significant difference between LA ERP (131.7 +/- 15.2 msec) and LA cycle length (period) (125.7 +/- 9.1 msec), but RA ERP (165.4 +/- 15.5 msec) was significantly longer than the LA cycle length (period) (p < 0.0001). Although in the present experiment regular left atrial activation and complex right atrial activation were observed predominantly, the activation sequence of af was different in each dog. These results clearly indicate that to employ a mapping system like ours is necessary to determine relevant surgical procedures to stop af and AF.

Effects of vagotomy on cholecystokinin- and dexfenfluramine-induced fos-like immunoreactivity in the rat brain

This study compared the effects of bilateral subdiaphragmatic vagotomy on the Fos-like immunoreactivity (FLI), a marker of neuronal activation, in rat brain induced by two anorectic agents, cholecystokinin (CCK) and the serotonin agonist, dexfenfluramine (DFEN). In the nonvagotomized rats, both CCK (5 μg/kg, IP) and DFEN (2 mg/kg, IP) Induced FU in the nucleus of the solitary tract (MST), the external subdivision of the lateral parabrachial nuclei (LPBE), the lateral subdivision of the central amygdeloid nucleus (CeL), and the bed nucleus of the stria terminallis (BST). However, subregional distribution of the FLI induced by the two agents was different in most of these regions. Additionally, the area postrema and the medial subdivision of the hypothalamic paraventricular nucleus were preferentially activated by CCK but not DFEN, while the caudate-putemen was activated by DFEM but not CCK. Bilateral subdiaphragmatic vagotomy completely abolished CCK-induced FLI in all the brain regions but did not attenuate DFEN-Induced FLI in any of these regions, including the NST. The results of the present study suggest that DFEN-activation of the NST-LPBE-CeL/BST neuraxis is not mediated by the vague nerve. On the other hand, and consistent with a variety of other data, activation of various parts of the brain by peripherally administered CCK depends on a vagal pathway. These data are discussed in relation to a previously proposed interaction between CCK and serotonin in mediating satiety.

Use of peripheral electrography to evaluate synchronism of electrical activity in different parts of the gastrointestinal tract

Use of the technique of peripheral electrography to study electrical activity in various parts of the gastrointestinal tract in dogs after fasting and during digestion is described, and it is shown that a computerized spectral analysis of peripheral electrograms makes it possible to monitor the cycle of fasting periodic gastrointestinal activity. In the process of digestion, the cycle of fasting periodic activity is disrupted and nonadjacent areas of the gastrointestinal tract exhibit synchronous electrical activity.

Facilitatory effect of hypothalamo-neurophypophysial tract stimulation on milk ejection frequency in the lactating rat

The relative contribution of magnocellular and parvocellular neurones to the patterning of milk ejections was studied by activation of various parts of the hypothalamo-neurohypophysial tract. During suckling of anaesthetised lactating rats, electrical stimulation of the neurohypophysis/neural stalk (15 Hz, 1.5 s on 1.5 s off , 10 min) evoked an increased frequency of milk ejections as detected by intramammary pressure recording. Bilateral stimulation of the paraventricular nuclei produced a similar facilitation in the post-stimulus period, but stimulation of the supraoptic nuclei (with either low current or current sufficient to evoke peripheral oxytocin release) had no effect on the occurrence of milk ejections. These data are consistent with the hypothesis that parvocellular but not magnocellular neurones participate in the regulation of milk ejection frequency.

Neurotoxicological Effects and the Mode of Action of Pyrethroid Insecticides

Neuroexcitatory symptoms of acute poisoning of vertebrates by pyrethroids are related to the ability of these insecticides to modify electrical activity in various parts of the nervous system. Repetitive nerve activity, particularly in the sensory nervous system, membrane depolarization, and enhanced neurotransmitter release, eventually followed by block of excitation, result from a prolongation of the sodium current during membrane excitation. This effect is caused by a stereoselective and structure-related interaction with voltage-dependent sodium channels, the primary target site of the pyrethroids. Near-lethal doses of pyrethroids cause sparse axonal damage that is reversed in surviving animals. After prolonged exposure to lower doses of pyrethroids axonal damage is not observed. Occupational exposure to pyrethroids frequently leads to paresthesia and respiratory irritation, which are probably due to repetitive firing of sensory nerve endings. Massive exposure may lead to severe human poisoning symptoms, which are generally treated well by symptomatic and supportive measures.

Action of free oxygen radicals on contractile activity of various parts of dog ventricle: K.Salba§, A.Sonel, H.Akalin, Ü.Özyurda, K.Ömürlü, H.Gök Cardiology Research Center, Medical School of Ankara University, Ankara-Turkey

Action of free oxygen radicals on contractile activity of various parts of dog ventricle: K.Salba§, A.Sonel, H.Akalin, Ü.Özyurda, K.Ömürlü, H.Gök Cardiology Research Center, Medical School of Ankara University, Ankara-Turkey

An Integrated Load Forecasting-Load Management Simulator: Its Design and Performance

Load management is now a widely practiced option among electric utilities in the United States. As the capital cost for power plant construction has skyrocketed, and the load growth has slowed, the utility industry has found inexpensive capacity through load management. Now, as the load growth is slowly picking up, and the incremental benefit from additional load management activities is diminishing, the capacity (MW) for bulk power purchase is getting more and more expensive. This situation has been aggravated by the proliferation of cogeneration activities in various parts of the country. While cogenerators may be able to supply significant amounts of energy (MWhr), quite often they depend on the electric utility to provide the backup capacity (MW). Consequently the utility supplied peak load capacity has a very low load factor and, therefore, becomes very expensive. Deeply involved in this situation are the electric cooperatives who buy bulk power from electric utilities and resell to their member consumers. A number of such cooperatives (e.g., Old Dominion Electric Cooperative in Virginia) are experiencing load growth higher than what is generally seen among investor-owned electric utilities. This has resulted in higher demand for capacity (MW) by the electric cooperatives while the cost for such capacity has shot up due to the reasons mentioned earlier. The coalescence of these factors have resulted in the necessity on the part of electric cooperative to exercise load control at appropriate times.

Experimental studies on the pathogenesis of retinopathy of prematurity.

The angiogenic activity of various parts of the retina in kittens with oxygen-induced retinopathy has been studied by the use of a corneal micropocket technique and chorioallantoic assay. The results indicate that in retinopathy of prematurity the most important role in the pathogenesis of fibrovascular proliferation is played by the so-called primary avascular retina, that is, that part of the retina which has not yet been vascularised during ontogenesis.

The distribution of N-isopropyl-p-iodoamphetamine in temporary ischemic brain of the mongolian gerbil.

We studied the distribution of N-isopropyl-p-[131I]-iodoamphetamine (IMP) in the ischemic brain of 44 mongolian gerbils. The right common carotid artery was temporarily occluded by a clip and recirculated 3 h later. After given time intervals, 50 microCi of IMP was injected into 18 gerbils which had symptoms. One min after injection (or 10 min, 1 h, or 6 h after injection in other gerbils), each gerbil was killed and autoradiography was performed. IMP activity in various parts of the brain was calculated as %Dose/g from each autoradiogram. At one min after recirculation, partial no flow phenomenon was observed in the right cerebral hemisphere. From 10 min to 24 h after recirculation, a high uptake region was observed partially in the right cerebral hemisphere and thalamus. The high activity disappeared rapidly 10 min after injection. It seemed that this high uptake indicated luxury perfusion at the location of severe tissue damage. In the left side, the low perfusion recovered to an almost normal value at one to three days after recirculation. These results suggested the possibility that IMP could demonstrate luxury perfusion and diaschisis.

Fast photoacoustic transients from dark-adapted intact leaves: oxygen evolution and uptake pulses during photosynthetic induction ? a phenomenology record

Using a photoacoustic technique it has been possible to observe fast oxygen evolution and uptake transients at a high time resolution (approx. 0.2 s), when a dark-adapted leaf is reilluminated. There is initially a rapid pulse of oxygen evolution, correlated with the initial fluorescence rise (total duration under the experimental conditions used about 1-2 s), corresponding presumably to the photoreduction of the plastoquinone pool. This phenomenon may be utilized to calibrate the oxygen-evolution photoacoustic signal. The first pulse is followed by a series of slower bursts of oxygen uptake and evolution, reflecting various pools which are expressed following sequential activation of various parts of the photosynthetic apparatus, until achievement of a steady state.

Characteristics of lysosomal phosphomannosyl-enzyme receptors in the rat heart.

The receptor system recognizing mannose 6-phosphate groups of lysosomal enzymes has been characterized, e.g. in fibroblasts and liver cells. The purpose of this study was to demonstrate the presence of a phosphomannosyl receptor system in rat heart muscle. The characterization of receptors was accomplished with beta-N-acetylglucosaminidase (beta-GA) secreted by rat embryo fibroblasts after ammonium chloride stimulation. The receptor binding of ligand enzymes was saturated by adding increasing concentrations of beta-GA and the binding increased linearly when the content of membrane protein was increased. The binding of beta-GA was inhibited by mannose and glucose phosphates, especially mannose 6-phosphate. Mannose itself did not inhibit binding of the enzyme, showing that the binding was not mediated by mannose receptors. Alkaline phosphatase treatment of beta-GA decreased the binding of ligand enzymes to receptors. Alkaline conditions increased the dissociation of receptor-ligand complexes, whereas the dissociation was minimal between pH 5.5 and 6.5. The proportion of endogenous beta-GA activity in membranes, probably representing receptor-bound location, varied between 40 and 55% of the total activity in various parts of rat cardiac muscle. The differences in the content of phosphomannosyl receptors, however, were insignificant between various cardiac muscle samples. At the organelle level the highest specific binding capacity, as well as the highest endogenous beta-GA activity, was in the sarcolemmal fraction. These results suggest that phosphomannosyl receptors also function in the endocytosis and transport of lysosomal enzymes in cardiomyocytes, as well as in several other cell types studied.

Characteristics of neuronal activity in prefrontal cortex during performance of spatial delayed reactions in monkeys.

Several types of neurons were differentiated on the basis of a study of neuronal activity in various parts of the cortex near the sulcus principalis during the execution of spatial delayed reactions by monkeys. It was established that the different types of neurons are represented in different numbers in different parts of the cortex near the sulcus principalis. The determination of several factors influencing the activity of these neurons and the comparison of data on their quantitative representation in the anterior, middle, and posterior parts of the cortex near the sulcus principalis with the existing behavioral data obtained after local ablations of identical regions of the brain made it possible to postulate that neurons belonging to the different types are involved in the analysis of different processes and represent different functional units.

Central catecholamine metabolism and hypothalamic self-stimulation behaviour in two inbred strains of mice

These experiments were conducted in order to better understand the role of catecholaminergic neurons in intracranial self-stimulation behaviour (ICSS) elicited from the lateral hypothalamus (LH). Two strains of mice which differ in their ICSS rate and their thresholds were studied. In a first time, we compared the catecholamine (CA) content and activity in various parts of the brain including cell bodies and nerve terminals of the main CA bundle. We used for this determination a high performance liquid chromatographic separation and an electrochemical detection. We observed that the BALB/c strain is distinguished by a higher CA activity than the DBA/2 strain. This correlates with a higher ICSS response rate in the BALB/c strain. The effects of stimulation on CA metabolism were then investigated, the electrodes being implanted specifically either in the dorsal or the ventral part of the LH and the biochemical data obtained analysed separately. Significant enhances of CA turn-over (TO) were noted in nerve terminals as hippocampus, cortex and accumbens. These results provide further evidence for the involvement of dorsal noradrenergic bundle and mesolimbic dopaminergic bundle in LH ICSS. Stimulation in the dorsal part of the LH produced the higher ICSS rate and seemed to induced a larger variation of the CA TO. We noted also that the CA metabolism was always more altered in the DBA/2 than in the BALB/c strain, which is surprising in regard to the behaviour and remains unclearly explained.

Histamine and histamine-N-methyltransferase in the goat brain.

Histamine concentrations and histamine-N-methyltransferase (HMT) (EC 2.1.1.8) activities were assayed in the goat brain, since this animal has been used for the purpose of assessing the physiological role of histamine in the central nervous system. The highest histamine concentrations were found in the hypothalamus (616 +/- 88 ng/g), 'thalamus' (244 +/- 41), preoptic area (242 +/- 95) and 'area postrema' (170 +/- 52), and are three to tenfold higher than the average concentration in the whole brain (76 +/- 9). The pineal body and choroid plexus contained very high concentrations of histamine (5800 and 5400 ng/g, respectively) and the pituitary gland had about the same as the hypothalamus (564 +/- 248 ng/g). There was little variation in the HMT activity in various parts of the brain and in the glands. In the cerebrospinal fluid both histamine concentration and HMT activity were very low, some increase occurred post mortem, but not within 20 minutes of death. The results indicate that the distribution of histamine and that of HMT in the goat brain are fairly similar to those in other mammalian brains, supporting the assumption that histamine might have a physiological function in the brain, especially in the hypothalamus.

The restructuring of the united nations economic and social system: Background and analysis

Restructuring, or the reform and rationalisation of United Nations (UN) structures in the economic and social sectors, has been a major issue before the UN for the past several years. Interest in restructuring, however, was evident even in the 1 960s when the Jackson Report and similar exercises were undertaken in an effort to bring about a more efficient alignment of UN structures involved in the promotion of economic and social development. ' Approximately 80 per cent of the budgets of the organisations in the UN system are today devoted to the promotion of economic and social development. The UN system has indeed become an important purveyor of resources on a global scale, yet the basic institutional design of the system is one that was forged in 1945 with somewhat different purposes in mind. The UN system has responded to the challenige of development by adding a plethora of new units and organisations to carry out responsibilities not adequately dealt with by existing ones. The growth and fragmentation of the system have created different types of problems. At a time when it is increasingly recognised that an integrated approach to development is essential, it is becoming more and more difficult to coordinate, in a mutually supporting and reinforcing fashion, the activities of various parts of the system. The proliferation of new bodies also led to fragmentation and the loss of coherence in the system as a whole. Indeed, there has been for some time a widespread belief that the system has become so unwieldy as to be incapable of responding to the wishes of the international community. Developed nations, including the socialist states, are for the most part interested in structural and institutional reform for they provide the largest portions of the budgets of the The 'Jackson Report', a study prepared by Sir Robert Jackson for the UN Development Programme, was completed in 1970. See A Study of the Capacity of the United Nations Development System, UN Publication, Sales No E.70.I. 1, 1970. For further background on the general problem see Martin Hill, The United Nations System: coordinating its economic and social work London: Cambridge University Press, 1978. This study was prepared under the auspices of UNITAR. This paper evolved out of research undertaken in connection with a UNITAR Seminar on The Restructuring of the United Nations System: implications for the creation of a New International Economic Order, held at Schloss Hernstein, Austria in 1978. We are grateful to theseminar participants for allowing us to draw upon the ideas put forward in the discussions. We also appreciate the useful comments offered by other international officials and diplomats. However, we assume responsibilityfor the views and opinions expressed in the paper which are personal

99mTc-Unithiol Complex, a New Radiopharmaceutical for Kidney Scintigraphy

The distribution of 99mTc-Unithiol complex was studied by macro-autoradiography in rats and in rabbit kidneys, and the presence of activity in the renal cortex was easily demonstrated. Using micro-autoradiography, the accumulation of activity in various parts of the nephron was observed to concentrate in the cells of the proximal and distal tubuli to a larger extent than in the glomeruli.

Pattern of distribution of dopamine-.BETA.-hydroxylase activity in normal subjects and in patients with mitral stenosis or left to right shunts.

Eighteen patients with mitral stenosis and twelve patients with left-to-right shunts heart disease and six normal subjects were catheterized and plasma dopamine-β-hydroxylase (DBH) activities in various parts of cardiovascular system were measured in order to assess the role of sympathetic activity in pulmonary hypertension. Arteriovenous differences of DBH activities were positive in normal subjects and patients with normal pulmonary artery pressure. A negative difference was found in patients with pulmonary hypertension. DBH activity in patients with pulmonary hypertension was significantly elevated compared with that of normal subjects. There was a weak correlation between mean pulmonary artery pressure and DBH activity in pulmonary artery. There were significant differences between normal, mitral stenosis with pulmonary hypertension and left-to-right shunts heart diseases about the pattern of distribution of DBH activity among these groups. A significant difference of the distribution between mitral stenosis with normal pulmonary artery pressure and that with pulmonary hypertension was also found. These findings suggested that a prolonged, increased level of sympathetic nervous system activity among patients with mitral stenosis and left-to-right shunt heart disease developed pulmonary hypertension. Thus, a significant contribution of sympathetic nervous activity to the establishment of pulmonary hypertension was suggested.

Multichannel recording of human gastric electrical activity from the body surface

A method of simultaneous multichannel derivation and recording of gastric potentials from the surface of the anterior abdominal wall is described. By multichannel electrogastrography electrical activity can be recorded selectively in different parts of the stomach from the surface of the anterior abdominal wall. Spatiotemporal and correlation analysis of electrical activity of various parts of the stomach was carried out during digestion.

Regulation of brain mitochondrial monoamine oxidase activity in experimental closed head injuries

Mitochondrial monoamine oxidase (MAO) activity in various parts of the brain (cerebral hemispheres, brain stem, cerebellum) was studied in experiments on rabbits in the normal state and 1.5 h and 1 and 5 days after closed head injury. Serotonin creatininesulfate was used as the substrate. Acute closed head injury was shown to cause a sharp decrease in MAO activity in the various parts of the brain of the experimental animals. Stimulation of the activity of the nervous system of the injured animals was shown to restore brain MAO activity.