Search PubMed⌕ Search

Biomedical subjects

G Stock

Publications and source records attributed to G Stock.

At least 73 records · Page 4Linked to original sources
PubMed1979

Failure of anticholinergic drugs to antagonize the increase in dopamine seen after gammahydroxybutyric acid and axotomy.

The increase in dopamine (DA) seen either 30 or 90 min after injection of gammahydroxybutyric acid or 90 min after axotomy of the nigrostriatal DA-fibers was not affected by i.p. injections of either atropine sulfate or atropine methyl nitrate or benztropine. These increases in DA are most probably due to feedback-mechanisms which do not involve cholinergic neurons.

Animals↗
PubMed1979

The influence of chronic deep brain stimulation on excitability and morphology of the stimulated tissue.

Bipolar electrical stimulations of the rostal hippocampus and of the amygdala were performed at irregular intervals in wakeful unrestrained cats via chronically implanted glass-insulated stainless steel electrodes. The excitability of the stimulated tissue remained unchanged during the whole investigation period of six months up to one and a half years, as was revealed by regularly performed comparisons of shape, latency, and amplitude of evoked potentials elicited by electrical stimulation of the rostral hippocampus and recorded within the ipsilateral mammillary body. The histological examination of the stimulated tissue revealed a fibrillary gliosis due to the trauma caused by the insertion of the electrodes, but no signs of additional tissue damage due to electrical stimulation or chronic mechanical irritation. The results indicate that it is possible to perform therapeutic stimulations of deep brain structures for long periods without inducing relevant changes in morphology or electrical responsiveness of the stimulated tissue. No kindling phenomena are to be expected, if the stimulations are performed at irregular intervals.

Amygdala↗
PubMed1979

Chronic electrical stimulation of the thalamic unspecific activating system in a patient with coma due to midbrain and upper brain stem infarction.

Chronic intermittent bipolar electrical stimulation of the left nucleus reticulatus polaris thalami was performed in a patient in a state of subcoma due to ischaemic infarction of wide medial parts of the midbrain, mainly the tegmentum, and the right-sided mediobasal parts of the forebrain. Stimulation immediately resulted in autonomic reactions and behavioural arousal reactions during the periods of stimulation. Longterm effect consisted of a rise in the level of clinical responsiveness for a period of seven weeks. A preexistent severe pneumonia disappeared completely after one week of stimulation and returned after seven weeks. The results are discussed on the basis of the pathoanatomical findings and of the physiological functions of the damaged as well as of the stimulated areas.

Aged↗
PubMed1979

Absence of sympathetic cholinergic vasodilatation in cats during early stages of affective behaviour elicited by stimulation of central amygdala, postero-lateral hypothalamus and locus coeruleus.

1. Stimulation of the central amygdala, postero-lateral hypothalamus and locus coeruleus in cats resulted in a sustained increase in arterial pressure, an increase in heart rate, with a poststimulation bradycardia and an increase in peripheral resistance (vasoconstriction in the vessels of the hindlimbs). The behavioural pattern was characterized by an alerting reaction. Increased stimulus intensities resulted in rage reactions if the amygdala or the hypothalamus were stimulated. 2. Stimulation of the basal amygdala resulted in a cardiovascular pattern characterized by a sympathetic cholinergic vasodilatation. The concomitantly observed behaviour was characterized by alerting, anxious behaviour, eventually resulting in defence. 3. Alerting was not necessarily linked to sympathetic cholinergic vasodilatation. 4. The cardiovascular pattern including sustained vasoconstriction of the vessels of the hindlimbs was supposed to be of greater importance for the induction of hypertension than the cardiovascular pattern, including sympathetic cholinergic vasodilatation.

Affect↗
PubMed1978

Humoral and neurohormonal aspects of blood pressure regulation: focus on angiotensin.

Angiotensin circulates in the blood as a hormone. Its main target organs are vascular smooth muscle, adrenal gland and the kidney. Hormonal angiotensin increases blood pressure by its vasoconstrictor action, by stimulation of aldosterone secretion and subsequent sodium and water retention, and by the stimulation of catecholamine release. Circulating plasma angiotensin also effects brain mechanisms of blood pressure regulation. In addition to this hormonal function, angiotensin is present in the brain as part of an endogenous brain renin-angiotensin system. Brain angiotensin is not secreted into the blood and can be considered a neurohormone with local function. A role of brain angiotensin in the maintenance of high blood pressure of spontaneously hypertensive rats has been demonstrated. Circulating plasma angiotensin appears to influence brain renin levels and vice versa. Stimulation of specific areas in the brain known to be involved in the regulation of the cardiovascular system, stimulate renin secretion from the kidney. The renin-angiotensin system can therefore serve as an example for the intimate interrelationship between humoral and neurohumoral mechanisms of blood pressure regulation.

Angiotensin I↗
PubMed1978

Sleep patterns in cat induced by gammahydroxybutyric acid.

Intravenous injections of gammahydroxybutyric acid (GHBA) (150-200 mg/kg) induce desynchronized sleep (DS) in the cat. This was shown by recording the EEG, eye-movements, the neck EMG, heart-rate and arterial pressure. The decreases in arterial pressure were not different from those recorded during naturally occurring DS. GHBA, given at doses above 200 mg/kg induced anaesthesia, during which arterial pressure was elevated. At the end of GHBA-induced sleep or anaesthesia there was a stage during which the animals were ataxic. The EEG showed a hypersynchronous spike pattern and arterial pressure was markedly elevated.

Animals↗
PubMed1978

Effects of enkephalins on arterial blood pressure are reduced by propranolol.

1. The cardiovascular effects of enkephalins have been tested in normotensive Wistar-Kyoto rats. Methionine-enkephalin and leucine-enkephalin increased blood pressure and heart rate after infusion into the brain ventricles. 2. After intravenous injection, blood pressure was increased by methionine-enkephalin and leucine-enkephalin, but heart rate was increased by methionine-enkephalin only. 3. Propranolol treatment reduced the increases in blood pressure following intraventricular methionine-enkephalin and leucine-enkephalin, while only the methionine-enkephalin-induced increases in heart rate were reduced by propranolol. 4. Heart rate and blood pressure responses after intravenous administration of methionine-enkephalins and leucine-enkephalin were not affected by propranolol. 5. Since opioid peptides occur in the blood and in regions of the brain involved in blood pressure regulation, the demonstrated cardiovascular effects to intraventricular and intravenous enkephalins support a role of these peptides in central and peripheral mechanisms of blood pressure control.

Animals↗
PubMed1977

[Report of a case of trichophyton fungus granulomatosis of the breast and its differential diagnosis to inflammatory carcinoma (author's transl)].

The case of a 34 year old patient is reported who suffered from a chronic dermatatomycosis. The trichophyton fungus granula matosis secondarily invaded the parenchyma of the breast and clinically first presented with signs and mammographic findings suggestive of an inflammatory carcinoma. A similar case report was not located in the international literature. Therefore the clinical and mammographic details and the conclusive microscopic findings of the biopsy of this case are reported for the purpose of differential diagnosis.

Adult↗
PubMed1977

[The problem of limited treatment of carcinoma of the breast. Documentation of the results on 400 operative specimens (author's transl)].

The value of limited treatment without compulsory lymphadenectomy in carcinoma of the breast in only well documented for primary tumors in which the infiltrative size of the primary tumor is with certainly below one centimeter. In contra-distinction to this situation primary tumors of more than 2 cm. in size are characterized by macrometastases and metastases in the regional lymph nodes as well as intramammory lymphogenous spread by contiguity. Compared to the classical concept of indirect hemotogenous spread from the physiologic lymphatic drainage system via the deep veins of the neck, the validity of limited treatment can be seen in the operative specimen in the appropriate cases. Histology shows spread of the type of lymphohemotogenous shunts.

Axilla↗
PubMed1976

Changes in excitability of amygdaloid and septal nuclei induced by medazepam hydrochloride.

Electrical stimulations of the central and basolateral part of the amygdaloid complex and of the septum in freely moving cats elicit changes in arterial pressure (i.e., an increase in pressure during stimulation of the central part of the amygdala, and a decrease followed by an increase during stimulation of the basolateral part of the amygdala and of the septum). These changes within the cardiovascular system are followed by rage reactions when the central part of the amygdala is stimulated, defense patterns when the basolateral part of the amygdala is stimulated, and pitiful mewing as a result of septal stimulation. Medazepam hydrochloride in a dose of approximately 15 mg/kg i.v. given over a period of 3 h, in order to maintain constant blood levels of the drug, attenuated slightly the cardiovascular reactions and elevated markedly the thresholds for psychomotoric behavior. The latencies between the onset of electrical stimulation and the beginning of the increase in arterial pressure were only slightly increased, whereas the latencies for spychomotoric behavior were markedly prolonged due to drug application. The data support the view that medazepam hydrochloride exerts depressant effects on the limbic-hypothalamic level with respect to psychomotoric responses. The effect was not identical for all nuclei tested. The basolateral part of the amygdala was significantly less sensitive to medazepam hydrochloride than the central part of the amygdala.

Amygdala↗
PubMed1976

[The presence of epithelioid glomus structures in the lymph nodes of excised mammary carcinomas (author's transl)].

A report is presented on the demonstration of epithelioid cell clusters within the axillary lymph node group, which - in the absence of knowledge of their structural peculiarities--could be taken for micrometastases of a solid mammary carcinoma. The lymph node material from 400 extensively excised mammary carcinomas with obligatory lymphonodectomy was available for this study. Microscopic inspection of successive sections at intervals of 100 mu was performed following fixation and optical demonstration of all lymph nodes in a picric acid medium. This procedure led to the discovery of epithelioid cell clusters in 18 out of the 400 cases examined. As regards their appearance, with direct allocation to the local vascular stroma, these clusters must be regarded as glomus-like structures. In no case could metastases of a mammary carcinoma and the epithelioid cell foci mentioned here be demonstrated either next to each other or combined. In appearance they are remarkably similar to the already known glomus structures of other sites. The presence of such structure in lymph nodes is most likely attributable to micromorphous malformation of vessels in the sense of hamartia. From a clinical point of view, their fundamental significance consists in the necessary differentialdiagnostic demarcation against metastase of solid carcinoma in the region of origin of the lymph.

Arteriovenous Anastomosis↗