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Biomedical subjects

G Martin

Publications and source records attributed to G Martin.

At least 451 records · Page 25Linked to original sources
PubMed1976

[Neurophysiologic mechanisms of arterial hypertension under experimental chronic emotional stress].

Neurophysiological studies were conducted with subhuman primates (macaca mulatta) in order to obtain an estimate of central nervous effects of socio-emotional stress. This was combined with continuously aggravated conditioning procedures in view of the possible significance of chronic environmental stress escalation for etiology and pathogenesis of an arterial hypertension model. Our conclusions are based on evoked potentials (EP) as integrative characteristics of cerebral information processing. The EPs were recorded by means of electrodes chronically implanted in brain structures of emotional and cardio-vascular relevance. Multivariate mathematico-statistical analyses of average EPs (AEP) provide an objective measure of stress sensibility of the individual, particularly of the effects of acute and chronic environmental stress factors upon the functional organization of the CNS. By means of a quantitative approach to AEP we were able to demonstrate a disjunction between distinct limbic and hypothalamic structures starting under stress conditions of subchronic character. We assume that the constancy of functionally antagonistic hyperactive excitation foci at diencephalic and supradiencephalic levels and their specific interaction with the equally stress related neocortical functional insufficiency constitutes a decisive pathogenetic central mechanism of neurotic behaviour. Long-term changes of amplification of external and internal afferences could be demonstrated on the basis of hypo- and hyperreactive neuroelectric functional patterns. These processes cause cerebro-visceral regulatory diseases as, e. g., a primary arterial hypertension by restriction of neocortical control and the corresponding efferent reactions for re-establishment of the dynamic homeostasis.

Animals↗
PubMed1976

[Changes in blood pressure, heart rate, respiration frequency and ECG in rhesus monkeys exposed to socio-emotional stress].

Blood pressure, heart rate, respiration frequency and ECG parameters were measured in 3 juvenile male rhesus monkeys under acute and chronic influence of a stepped load schedule including positive (nutritional), negative (pain-related) and socially operant conditioning and phases of a pharmacological sensibilization (angiotensin-II) of the cardiovascular system. The results suggest a general adaptation to the positively operant conditioning, while the latter stressing influences (either single or in combination) produced blood pressure and heart rate elevations, which had the character of dysregulatory functional changes (borderline hypertension model) and were reached by other authors, if at all, only through stronger stress influences.

Animals↗
PubMed1976

[Results of otoplasty (author's transl)].

77 patients with uni- or bilateral otoplasty have been reviewed between 6 months and 5 years postoperatively. Surgery had been performed using a modified Converse technique. A comparison was made between the objective results and the patient's satisfaction. Using our own classification, we listed 64.9% as good results and 3.9% as failures, suggesting a reoperation. 31.2% of the cases demonstrated only some improvement. Evaluating our results listed as "good", the average distance helix: planum mastoideum, measured between the upper and middle third of the ear, was 18.8 mm and between the middle and lower third 18.0 mm.

Adolescent↗
PubMed1975

[Examinations of the thresholds of discomfort of the ears treated by stapedectomy (author's transl)].

Ears treated by stapedectomy often are extremely irritated by noise. To clear up this phenomenon were plotted the thresholds of discomfort by tone- and speechaudiograms in the operated ears as well as in the non-operated. All our patients being examined had the stapedius muscle tendons cut. There was no clinical otosclerosis in the non-operated ears and the audition was the same on either side. A significant increase of the discomfort threshold was seen in the operated ears (93.8% in the toneaudiograms and 78.1% in the speech audiograms). In the tone audiograms the frequencies of 500, 1000 and 2000 cps were the most concerned. We consider this increase of discomfort as a consecutive result of the stapedius tendon cutting. It verifies the protecting function of the stapedius muscle against low frequencies.

Audiometry↗
PubMed1975

Aspirating subdural effusions, so called brain stem shock.

A shift of blood into the head during negative pressure aspiration of subdural haematomas in an infant has been demonstrated, and also that aspiration may restart bleeding. An estimate of the elasticity of a 47 cm circumference skull has been obtained. It is suggested that the observed changes in distribution of blood are sufficient to explain the occasional deaths of infants after aspiration of subdural haematomas and that so-called "brain stem shock" need not be invoked.

Blood Volume Determination↗
PubMed1975

[Selective tomography in the study of the temporo-mandibular joint. (author's transl)].

The majority of temporo-mandibular pains and dysfunction can be related directly or indirectly to the occlusal relationship of the teeth. The first manifestation is a slight reduction of the interarticular space, that must be early diagnosed, to prevent organic changes. Tomography is the one technique able to give a exact information of temporo-mandibular joint. But if we ask to that examination to detect very slight change of the interarticular space, the technique must be accurate and established in function of morphology of the patient; we have observed great variations in direction of the axis of condyles from one person to the other, and even from one side to the other for the same subject. So that, the first stage of the roentgen examination will be a radiograph taken in submentovertical (Hirtz) position. We measure the angle formed by the axis of each condyle and the sagittal median plane. The maim beam wil be directed in the axis of the condyle for sagittal tomography and perpendicularly for frontal tomography. It is important to state precisely that for tomography "closed mouth", the patient must be in terminal occlusion during the whole examination. For tomography "open mouth" we place a wedge between dental arches.

Humans↗
PubMed1975

[Comparative study of neuraminidases from "Diplococcus pneumoniae" and "Clostridium perfringens"].

Neuraminidases have been purified from the culture medium of two microorganisms, one aerobic, Diplococcus neumoniae, the other anaerobic, Clostridium perfringens. The enzymatic properties of the 2 neuraminidases have been studied (pH optimum; effect of cations; activity toward different substrates: neuraminyllactose, dilactaminyllacto-N-tetraose, gangliosides, alpha1-acid glycoprotein, Collocalia glycoprotein, ovine submaxillary mucin, porcin intestinal and human bronchial mucins).

Cations, Divalent↗
PubMed1975

Impacts of environmental stress exposure on central nervous functional patterns. A quantitative approach to evoked potential data.

Albino rats and rhesus monkeys with chronically implanted electrodes in cortical and subcortical, vasomotory and emotionally relevant brain regions were subjected to psycho-nerval stress (short-term stressful CR learning experiments on rats, long-term environmental stress with disturbances of the diurnal rhythm and social hierarchy on rhesus monkeys). Applying average computer techniques and discriminance analyses to evoked potentials (average evoked potentials = AEP to standardized optic-acoustic test stimuli) we were able to objectify the effect of different stress categories on central nervous functional patterns. These phenomena of electrical activity of the CNS proved to be extremely responsive to the stress exposure (avoidance conditioned learning experiments or socio-emotional overstrain). Under moderated stress (CR phases of acquisition and stabilization), time-space patterns of a primary facilitation of AEP could be established, expressing an improved energetic capacity of the CNS (adaptive effect). On the other hand, there was a generalized impairment of bioelectric information processing in temporal correlation with an increase in psycho-nervous stress exposure to rats (CR phases of differentiation). During long-term socio-emotional stress exposure of rhesus monkeys the highly significant changes of AEP-patterns (increasing fall short of the set point of the bioelectric level of activity with segmental differences in the multiphasic evoked potential) are to be interpreted as maladaptive processes in central nervous function under long lasting high stress conditions.

Adaptation, Physiological↗