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Biomedical subjects

J Fischer

Publications and source records attributed to J Fischer.

At least 577 records · Page 32Linked to original sources
PubMed1977

Anxiety, heart rate and their interrelation at mental stress in school children.

Heart rate (HR) was measured in 63 ten year old boys during psychic stress induced by dental examination and the reading of a difficult test before a public. By means of the CMAS questionnaire, a teacher's questionnaire, rating of manifestations during the examination and selfcomparison by the children, we tried to assess the level of their anxiety. We looked for correlations between the individual measures of this personality trait and between anxiety and autonomic (HR) reactivity. From the aspect of HR the whole experiment appeared as a uniform, ever increasing stress, including socalled rest situations. HR was more affected by the stress situations than by individual reactivity. Concerning degree of anxiety we found a correlation only between the score of manifest anxiety (CMAS scale) and HR level: more anxious children had a lower HR under stress than less anxious children. We found no correlation between anxiety reported subjectively (CMAS) and objective observation (teacher, experimenter, other children). It was confirmed that in assessing the child's reactivity in stress the intensity of the stimulus must be taken into account. An analysis of the literature has shown that the results and their interpretation depend much on the methods used.

Anxiety↗
PubMed1976

[Complications due to endocardial and epimyocardial electrodes in 171 patients with artificial pacemakers].

On the basis of experience with 171 patients the advantages and disadvantages of a sutureless, corkscrew-like myocardial electrode are compared with those of endocardial electrodes. Electrode complications were significantly less frequent in patients with sutureless myocardial electrodes and never lead to death. However, a benign postpericardiotomy syndrome was frequent (16% of cases). Electrode dislocation was the main complication in patients with endocardial electrodes.

Electrodes, Implanted↗
PubMed1976

A comparison of two bipolar exercise electrocardiographic leads to lead V5.

ST-segment depression and slope were compared in three lead systems (V5, CC5, and CM5) and in two groups of patients using both visual analysis of electrocardiographic paper and computerized techniques. Bipolar lead CC5 was found to be comparable to lead V5 when visual analysis of electrocardiographic recordings was utilized. Bipolar lead CM5 was found not to be comparable to lead V5 and to be less sensitive if classic criteria for slope were used. The technique of computerized analysis mad measurements of slope and amplitude to a reproducible level not possible with the standard technique. Statistically significant differences were found between the exercise electrocardiographic leads utilizing computerized electrocardiographic analysis . We conclude that computerized techniques of electrocardiographic analysis require new criteria for defining an abnormal repolarization response. The criteria must be specific for different electrocardiographic leads if the repolarization changes in these leads are to have comparable diagnostic significance.

Adult↗
PubMed1976

An attempt to evaluate changes in heart rate in situations induce by symbolic stimuli in children.

Ninetyfive 10 year-old pupils were shown 4 film scenes about first aid in accidents arousing anxiety about possible injuries and fear about the fate of the protagonists. Simultaneously with showing the film heart rate was recorded in the boys who had been previously divided in three groups with a different level of anxiety, according to their rating in the CMAS questionnaire. HR response was observed during the course of the whole film as well as in the sections related to the critical moments of the event -- the moments of injury. -- The mean HR values during projection of the film had a differently steeply rising tendency according to the groups with a different level of anxiety, however, interindividual HR variability as a whole was not influenced by the film. Mean group HR values around the critical moments of the story did not differ statistically significantly (they decreased moderately from the little anxious to the more anxious group). However, after a sufficiently effective scene the group of more anxious children exhibited a significant increase in interindividual variability.

Anxiety↗
PubMed1976

Sequence of events in the activation of adenylate cyclase by cholera toxin.

The toxin of Vibrio Cholera causes fluid secretion from the small intestine by stimulation of adenylate cyclase and elevation of intracellular cyclic AMP concentrations. The toxin is a protein composed of subunits responsible for binding to cell membranes and a subunit responsible for the activation of adenylate cyclase. The binding subunits (B) are non-covalently bonded to the active subunit (A). The latter is composed of two polypeptides A1 and A2 linked by a disulphide bridge. Exposure of the intestine to toxin results in rapid binding to the brush border membrane. Thence follows a gradual increase in adenylate cyclase activity, and stimulation of electrolyte and fluid secretion. Enzyme localization studies show that the brush border does not contain adenylate cyclase. Thus the stimulation of adenylate cyclase by toxin which interacts with the brush border must be indirect. From recent studies it seems that an activator of adenylate cyclase can be found in cytosol from toxin-treated cells. Incubation of toxin with cytosol or dithiothreitol results similarly in the formation of an activator. Preincubation of toxin with cytosol results in more rapid activation of adenylate cyclase in liver cell membranes than direct addition of cytosol and toxin. Preincubation of cholera toxin for activation, by cytosol, is presumed to be due to the splitting of the disulphide band between the A1 and A2 components of the active subunit. The stimulatory ability resides in A1 and both A1 and NAD are required for the activation of adenylate cyclase. The toxin-stimulated adenylate cyclase has similar characteristics to the enzyme stimulated by non-hydrolysable analogs of GTP such as guanylylimidodiphosphate (GppNHp). Stimulation by either cholera or GppNHp is irreversible, the responses to catecholamines are enhanced and the enzyme can be solubilized in the activated state.

Adenylyl Cyclases↗
PubMed1976

[Demonstration of bacteria and fungi in tissues by topo-optic aldehyde bisulfite toluidine blue (ABT) reaction].

Reaction with aldehyd-bisulfit-toluidinblue (ABT)--as a selective topo-optical reaction for vicinal OH-and amino-OH groups, appears to be suitable for demonstration of bacteria in tissues. Cell membranes and capsules of bacteria and fungi contain large quantity of carbo-hydrates, therefore they show strong basophilic staining after ABT reaction. Double refringement brought about by orientated dye-binding seems to be the sign of the linear arrangement of polysaccharides composing cell membranes and capsules of bacteria. Practical importance of the reaction is shown on examples. Diagnostic advantages of it are also discussed.

Animals↗
PubMed1976

Molecular order of carbohydrate components in cell walls of bacteria, fungi and algae according to the topo-optical reaction of the vicinal OH groups.

Selective topo-optical staining of vicinal OH groups with aldehyde-bisulphite-toluidine blue (ABT) has been used for studying the molecular structural order of polysaccharide components in microbial cell walls and capsules. (i) By intensive metachromatic staining in the light microscope, the method demonstrates carbohydrates, containing free vicinal OH or acylaminohydroxyl groups. (ii) The birefringence induced by oriented toluidine blue binding of the ABT reaction, provides information about the linear order of the reacting carbohydrate chains, a possibility not offered by other ultrastructural methods. Furthermore the different optical character of birefringence induced by ABT is indicative of the presence of (a) tangentially oriented polysaccharide chains in the cell wall of the molds and bacterial capsules; or (b) radially oriented OH groups suggesting helical glycan chains of peptidoglucomannane and mucopeptide in the yeasts and bacterial cell walls.

Bacteria↗
PubMed1976

Demonstration of microorganisms in tissues by the ABT and KOH-ABT topo-optical reactions.

The aldehyde-bisulphite-toluidine blue (ABT) reaction, as a selective topo-optical test of vicinal OH and amino-OH groups is suited for the selective demonstration in tissues of microorganisms of polysaccharide containing cells. Alkaline pretreatment of the polysaccharide cell walls, releases, by splitting the O-acyl radicals, further vicinal OH groups for the ABT reaction, thus actually increases the sensitivity of the method. The topo-optical reactions are characterized by a strong birefringence induced by oriented dye-binding, due to the linear arrangement of polysaccharides composing the cell wall. Differences in the character of birefringence have made it possible to work out a new method for the analysis of the cell wall ultrastructure as well as to demonstrate microorganisms in tissues. The practical value of the reactions is illustrated by examples.

Aldehydes↗
PubMed1976

Shortened duration of action of 1-deamino-8-D-arginine vasopressin (DDAVP) in patients with diabetes insipidus requiring high doses of peroral antidiuretic drugs.

The antidiuretic effects of graded intravenous and intranasal doses of a new vasopressin analogue (DDAVP) were investigated in two groups of patients with pituitary diabetes insipidus. In the first group, three patients with a high requirement of maintenance doses of peroral anti-diuretic drugs were included; and in the second group, ten patients with a normal (usual) requirement were included. Comparing the antidiuretic responses during 24-hour collection periods, DDAVP, on a microgram basis, was less effective in the "high peroral-dose requirement" patients. The duration of action of single intravenous doses (0.04-24 micrograms) of DDAVP was significantly shortened in the "high peroral-dose requirement" group. However, comparing the peak responses induced by increasing doses of DDAVP in the two groups, there was no demonstrable diminution in the anti-diuretic ability of DDAVP in the "high peroral-dose requirement" patients. Although the possibility of a smaller remnant reserve of ADH was also considered, shortened duration of action ot DDAVP suggests more probably enhanced metabolic breakdown of vasopressin in "high peroral-dose requirement" patients.

Adult↗