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Biomedical subjects

M Pohl

Publications and source records attributed to M Pohl.

126 records · Page 7Linked to original sources
PubMed1982

Reversible blockade of cardiac efferents with procaine instilled into the pericardium of cats.

The blocking of afferent signals from the heart by the instillation of local anaesthetics into the pericardium has frequently been used for studying cardiac reflexes. Yet no attempts have been made to define what effects this has on efferent cardiac drive. Therefore, in nine chloralosed cats with open chests and catheters sewn into the pericardium the procaine concentrations were determined which would block the heart rate responses to electrostimulation of the vagi nerves or the stellate ganglia. The procaine effects on arterial pressure and left ventricular peak positive dP/dt were also evaluated and in 11 cats the vagolytic effects of atropine (0.25 mg . kg-1, intravenous) and intrapericardial procaine (0.1%) were compared. As little as 0.05% procaine attenuated the bradycardia associated with stimulation of the stellate ganglia by only about 30%. Virtual elimination of both sympathetic and vagal drive was achieved with 0.5% procaine having only mild effects on blood pressure and left ventricular dP/dt. Atropine (0.25 mg . kg-1, intravenously) and procaine (0.1% intrapericardially) affected heart rate equally. With procaine in the pericardium it is possible to reversibly and selectively block cardiac efferents and to separate vagal and sympathetic drive by choosing the appropriate concentration of the local anaesthetic.

Animals↗
PubMed1982

Synchronization of double asymmetrical epileptogenic foci in the cerebral cortex of the rat.

Discharges of two asymmetrical penicillin foci progressively synchronized during 25 min after creation of these foci. Section of the corpus callosum seriously impaired but did not completely block this synchronization. Thalamic spreading depression did not significantly change the synchronization in rats with intact corpus callosum. Noncallosal component of synchronization is probably realized through brain stem structures.

Animals↗
PubMed1981

Effect of phenobarbital on cortical epileptogenic foci in the rat.

The activity of epileptogenic foci was studied in acute experiments on adult male rats without general anaesthesia; the animals first received an intraperitoneal injection of phenobarbital [40 mg/kg] and 30 min later a cortical focus was induced by the local application of penicillin. These foci, which were induced in the sensorimotor area, had a lower discharge frequency than in the controls and the formation of projected discharges was delayed. In two symmetrical and asymmetrical cortical foci, activity was synchronized significantly more slowly after phenobarbital than in the controls. The cortical interhemispheric response was not influenced by the administered dose of phenobarbital. In these experiments, phenobarbital had an anti-epileptic effect both on the primary focus and on the spread of epileptic activity from this focus.

Animals↗
PubMed1978

[The effect of early appearing extrasystoles on systemic and coronary circulation].

In 10 anaesthesized dwarf pigs with an open thorax the effects of extrasystoles on systemic and coronary circulation were investigated. The actual effect of an extrasystole depends on the time of its onset. Early extrasystoles hamper the cardiac blood perfusion, with decreases in the stroke volume, mean arterial pressure, coronary blood flow, and elevation of coronary resistance. Extrasystoles setting on later are of minor haemodynamic and coronarodynamic importance. The effects of bigeminy and 2:1 extrasystolia are more adverse than the consequences of extrasystoles with later onset. With cumulation of several consecutive extrasystoles also adverse the haemodynamic coronarodynamic sequelae increase, in dependence on the magnitude of the quotient coupling time /extrasystolic excitation period [ greater than 1.1], or of the quotient: duration of pre- and postextrasystolic intervals/ normal interval of heart action [ greater than 1.5]. The authors point out the importance of haemodynamic findings during early extrasystoles in ischaemic heart disease.

Animals↗
PubMedDate not supplied

The bronchosparing effect of celiprolol, a new beta 1- alpha 2-receptor antagonist on pulmonary function of propranolol-sensitive asthmatics.

Twelve normotensive asthmatics who demonstrated bronchoconstriction after a single oral dose of 80 mg of propranolol received (according to a double-blind, randomized, crossover design) placebo, celiprolol 200 mg, and celiprolol 400 mg at intervals of at least three days. Pulmonary function parameters were measured by whole body plethysmography just before treatment and hourly for three hours. Thereafter, terbutaline (0.5 mg), a beta2 agonist, was administered in aerosol form at 15-minute intervals for a total of five doses. This design permitted a safety assessment of the effect of placebo and celiprolol on resting pulmonary function and the evaluation of any interaction between this beta blocker and terbutaline. Propranolol 80 mg produced a statistically significant decrease in a forced one second expiratory volume and forced vital capacity, and a pronounced rise in airways resistance as compared with either dose of celiprolol or with placebo (P less than .001). The effect of celiprolol was not statistically distinguishable from placebo. Terbutaline caused further net bronchodilation after administration of celiprolol and placebo but, even at supratherapeutic doses, failed to restore pulmonary function parameters to baseline levels after treatment with propranolol. The bronchosparing effect of celiprolol may be due to its unique pharmacologic profile, which includes cardioselectivity, modest beta 2-agonist activity, and alpha 2-receptor blockade.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

[Sclerosing peritonitis without reduced ultrafiltration as complication of peritoneal dialysis].

UNLABELLED: Peritoneal dialysis (PD) is the preferred method of renal replacement therapy in childhood and adolescence while waiting for a kidney transplant. As major complication, encapsulating peritoneal sclerosis (EPS), sometimes also referred to as "sclerosing peritonitis", may develop after prolonged periods of PD and lead to severe therapeutical problems. CASE REPORT: A 20-year-old patient with a history of three unsuccessful kidney transplants due to recurrence of his focal segmental glomerulosclerosis presented after 9 years of PD with acute abdominal pain and reduced bowel movements. Infectious peritonitis was excluded, ultrafiltration with 800-1 000 ml per day with low (1,36 %) glucose dialysate was not impaired. Plain abdominal X-ray, ultrasound and CT-scan illustrated characteristic peritoneal calcifications. Diagnosis of EPS was confirmed by peritoneal biopsy. The patients was switched to hemodialysis, enteral nutrition was continued, and the follow-up (now 16 months) was uncomplicated with the exception of a sterile ascites, which was twice relieved. Diagnostic and therapeutic options are discussed. CONCLUSION: In contrast to most reports, EPS may develop with unchanged ultrafiltration after prolonged periods of PD. We recommend regular functional and imaging studies in patients at risk.

Adolescent↗
PubMedDate not supplied

Localization of the origin of self-sustained afterdischarges (SSADs) in the rat: I. The spike-and-wave type of SSAD.

The genesis of the thalamocortical self-sustained afterdischarge (SSAD) composed of spike-and-wave (S + W) rhythm was studied in adult male albino rats. Under control conditions, rhythmic electrical stimulation of the specific somatosensory nucleus of the thalamus always elicited type S + W SSAD. An electrolytic lesion of the nonspecific thalamic nuclei did not prevent generation of type S + W SSAD, while stimulation of the ventrobasal complex evoked both type S + W SSAD and another type of SSAD composed of large waves with superimposed fast activity. Elimination of the cortex (by suction or spreading depression) ipsilateral to the stimulated thalamus completely suppressed any possibility of the formation of type S + W SSAD; elimination of the contralateral cortex did not affect it. Our results suggest that the cortex is the decisive factor in the genesis of S + W rhythm, while the thalamus markedly influences the conditions of its formation.

Animals↗
PubMedDate not supplied

Effects of age, gender and ear side on SOAE parameters in infancy and childhood.

We investigated 267 infants and children aged 9 days to 16.8 years to study the spontaneous otoacoustic emission (SOAE) data prevalence, number per ear, level and frequency as a function of growth. Dependence on age, gender and ear side was statistically analyzed using the method of generalized estimation equations. Except in the 1st year of life, SOAE prevalence per ear and SOAE number per ear decreased significantly with increasing age. Both SOAE parameters were significantly higher in female than in male subjects, with gender difference of SOAE prevalence per ear being more distinct in the 1st year of life. Although a clear ear side effect on SOAE prevalence per ear could already be seen in ears of female children in this age group, only SOAE number per ear was significantly higher in right ears than in left ears from the 1st year of life on. Except in the first 12 months, SOAE level and SOAE frequency decreased significantly with increasing age. Neither a significant gender difference nor a significant ear side difference could be determined. Our results found in infancy and childhood are discussed within the framework of the current literature.

Adolescent↗
PubMedDate not supplied

[Three-dimensional visualization of stationary flow behind artificial heart valves].

The visualization and quantitative analysis of flow offers a possibility for the hydrodynamic characterization of artificial heart valves. Different types of valves can be compared if velocity profile and the turbulent shear stress caused by the prosthesis are known. The tracer technique was selected, since it permits visualization also of turbulent flow through the valve. With the aid of a simple optical device the three-dimensional flow pattern behind the valve is determinable. The main features of the method are: The regions of interest can easily be identified. Velocity profiles can be determined and shear stress and turbulence intensities estimated. The experimental setup is simple, calibration is not necessary, and it can be used for turbulent flows. The method can be used only with transparent fluids and vessels; measurements in blood are not possible. Because of the large number of measuring points required the method is very time-consuming. The use of an automatic picture analyzing system would make it possible to increase the number of pictures processed, and thus increase resolution. The velocity profile of a three-finger-valve, the TAD 29, was established at a distance of 20 mm from the ring, and compared with known profiles from the literature. The valve has an opening angle of 70 degrees. All typical regions for the flow of an artificial heart valve, such as jet, stagnation gone, backflow and turbulence were demonstrated.

Blood Flow Velocity↗
PubMedDate not supplied

[Not Available].

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Education, Medical↗
PubMedDate not supplied

Effects of loreclezole on metrazol-induced phenomena in developing rats.

A potential antiepileptic drug, loreclezole, was studied in rats of 7, 12, 18, 25 and 90 days old. Metrazol-induced motor phenomena served as a model. Loreclezole did not consistently influence isolated myoclonic jerks or minimal metrazol seizures (predominantly clonic with preserved righting ability). Major metrazol seizures, i.e., generalized tonic-clonic seizures, were suppressed by loreclezole in a dose-dependent manner in all age-groups, except in the 7 day old group where outlined changes did not reach statistical significance. Severity of seizures was significantly diminished at all developmental stages studied. Loreclezole exhibits nearly the same profile of action as phenytoin and carbamazepine in this model.

Animals↗
PubMedDate not supplied

Immunocytochemical evidence for calcitonin gene-related peptide-like neurons in the dorsal horn and lateral spinal nucleus of the rat cervical spinal cord.

Calcitonin gene-related peptide (CGRP) in the dorsal horn of the rat spinal cord was assumed until now to be principally of primary afferent origin. It is shown here, on the basis of both light and electron microscopic immunocytochemical evidence, that some cell bodies of the dorsal horn and lateral spinal nucleus (LSn) of the rat cervical spinal cord contain a CGRP-like immunoreactivity. At the light microscopic level, immunoreactive cell bodies were observed in animals pretreated with colchicine injected intraventricularly, CGRP-like cell bodies were morphologically heterogeneous and distributed in the three superficial layers of the dorsal horn. They were very rare in lamina I and more numerous in laminae II and III. A group of immunoreactive cell bodies was also observed in the LSn. Using electron microscopic techniques, a few immunoreactive cell bodies were observed even in control animals. In addition, relatively numerous immunoreactive dendrites were observed in lamina II. The specificity of the reaction and the physiological implications of the results are discussed.

Animals↗