Search PubMed⌕ Search

Biomedical subjects

H Simon

Publications and source records attributed to H Simon.

At least 289 records · Page 16Linked to original sources
PubMed1979

Anatomical relationships between the ventral mesencephalic tegmentum--a 10 region and the locus coeruleus as demonstrated by anterograde and retrograde tracing techniques.

We have searched for anatomical connections between the ventral mesencephalic tegmentum (VMT), including the dopaminergic cell group A10 and the locus coeruleus (LC) region. Tritiated leucine (120--220 nl) and horseradish peroxidase delivered by electrophoresis were injected in the VMT-A10 region. We have demonstrated, on the one hand bilateral projections from the VMT-A10 region to LC, and on the other hand a possible contralateral projection from LC to VMT-A10 region. These relationships, reported for the first time may have some important functional significance.

Animals↗
PubMed1979

Increased utilization of dopamine in the nucleus accumbens but not in the cerebral cortex after dorsal raphe lesion in the rat.

Dihydroxyphenylacetic acid (DOPAC) and dopamine (DA) levels were estimated in the frontal cortex, the nucleus accumbens and the striatum of the rat after electrolytical lesion of the dorsal raphe nucleus. The efficiency of this lesion was tested by measuring the decline in serotonin (5-HT) levels in the striatum. 5-HT levels were reduced by 90% when compared to those of sham-operated rats 11 days after the lesion. As revealed both by the increase in DOPAC levels and in the DOPAC/DA ratio, the rate of DA utilization was markedly increased in the nucleus accumbens, slightly enhanced in the striatum and in contrast remained unaffected in the frontal cerebral cortex 4 days after the lesion. Changes in DOPAC levels in the nucleus accumbens were also seen 11 and 30 days after the lesion but they were less pronounced than those observed at 4 days. These results suggest that neurons originating from the dorsal raphe and projecting to the ventro-tegmental area are regulating the activity of the meso-nucleus accumbens dopaminergic neurons but not that of the meso-cortical dopaminergic neurons.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1979

Definitive disruption of spatial delayed alternation in rats after lesions in the ventral mesencephalic tegmentum.

Prefrontal system dysfunction are revealed in rats in delayed response tasks. In view of the anatomical projections existing from the ventral mesencephalic tegmentum to the prefrontal system we have done this research in order to determine whether cognitive processes are impaired after mesencephalic lesions. Rats learned spatial delayed alternation in a T-maze. After acquisition they were randomly divided in two groups; the experimental group received lesions in the ventral mesencephalic tegmentum at the level of the A10 cell bodies. These lesions induced definitive disruption of the retention of the delayed alternation and the rats were unable to relearn the task. However, these animals were able to perform normally in an operant conditioning with food reinforcement indicating the specificity of the deficit observed with respect to the delayed alteration task. The possible modulating role of dopaminergic A10 neurones is hypothetized.

Animals↗
PubMed1979

Intrarenal pheochromocytoma: report of a case.

To our knowledge the first case of an intrarenal pheochromocytoma is reported. It is important to realize that an intrarenal or apparent intrarenal mass in a hypertensive patient might be a pheochromocytoma so that appropriate precautions can be taken.

Adrenal Glands↗
PubMed1979

[Coronary calcification and luminal diameter in coronary disease (author's transl)].

Two hundred and thirty-six patients with coronary heart disease were examined by coronary angiography and laevo-cardiography. In 111 patients (47%) there was coronary artery calcification. Of these, 108 patients (97%) showed abnormal findings on the coronary angiogram; in 72 patients (67%) coronary stenosis was greater than or equal to 50% of the lumen. The severity of the stenoses increased with the amount of calcification. There were only three false positive findings and the presence of coronary calcification indicates coronary sclerosis with a high degree of probability. Fluoroscopy is the simplest and most sensitive method of examination and is of great value in the non-invasive investigation of coronary sclerosis.

Calcinosis↗
PubMed1979

An index of accessibility for ambulatory health services.

This paper discusses an Index developed and used to measure accessibility to health services provided on an outpatient basis at the Kaiser Community Health Foundation, Cleveland, Ohio. The Index is based on four levels of urgency or severity of illness and on the waiting times to get entry into the system. The parameters of the Index, initially established by task force members, were tested on a sample basis against the judgments of Kaiser outpatient facility users and finally refined through the consensus-seeking Delphi technique using a panel representing Kaiser members, gatekeepers, physicians and administrators. The actual times required to gain accessibility in the various process stages and in the various departments were obtained through simulated requests for appointments, by monitoring telephone calls to the various gate-keeping stations, by direct observations, and by the use of a telephone traffic computer. The paper discusses the Index developed, the data collection methodologies, and the data analyses performed.

Ambulatory Care Facilities↗
PubMed1979

Purification and some properties of a hitherto-unknown enzyme reducing the carbon-carbon double bond of alpha, beta-unsaturated carboxylate anions.

2-Enoate-reductase, a previously unknown soluble enzyme is present in Clostridium kluyveri and another Clostridium species growing on (E)-2-butenoate. From the latter the reductase was purified 88-fold with an overall yield up to 74%. The enzyme was pure as judged by polyacrylamide gel electrophoresis with and without sodium dodecyl sulphate as well as by isoelectric focusing. The purification of the enzyme was performed in the presence of (E)-2-methyl-2-butenoate as substrate to keep the enzyme in the oxidized state and under anaerobic conditions. The purification procedure included an ammonium sulphate precipitation, chromatography on DEAE-Sepharose CL-6B, hydroxylapatite and Sepharose CL-6B. The enzyme reduces different alpha,beta-unsaturated carboxylate anions such as (E)-2-butenoate, (E)-2-methyl-2-butenoate, (E)-cinnamate and probably many others in a NADH-dependent reaction to the saturated carboxylate anions. Fumarate, 3-phenyl-2-propinate, 2-enoyl-methyl and CoA esters proved not to be substrates for the purified reductase. NADPH does not act as an electron donor. The enzyme was shown to have a molecular weight of about 450,000 by gel chromatography. It consists of subunits with a molecular weight of 78,000. Per subunit about 1 FAD, 3.5--3.8 atoms of iron and 4.0 labile sulphur atoms have been found indicating a conjugated iron-sulphur flavo-protein. Copper could not be detected. The isoelectric point was 8.4. As shown by absorption spectroscopy the enzyme can be reduced by NADH and reoxidized with dichloroindophenol, hexacyanoferrate III, oxygen and substrates. Addition of 8 mol p-hydroxymercuribenzoate to 1 mol subunit completely destroyed the activity of the reductase. So far no physiological role of the enzyme is known.

Amino Acids↗
PubMed1979

[Computer-Cardiotomography (author's transl)].

Based on our first 200 investigations computed tomography of the heart is demonstrated as a new non-invasive roentgenography on typical examples and compared with the findings of the conventional roentgenogram. With the present technology the following indications for computed tomography of the heart seem to be reasonable: Calculation of size and volume of the cavities of the heart; intracavitary space occupying lesions (tumor, thrombus): demonstration of the thickness of the ventricular wall and ventricular septum and their changes caused by hypertrophy, myocardial infarction or septal defect; demonstration of aortic and ventricular aneurysm; demonstration of pericardial effusion, pericardial tumor, pericardial cyst of lipoma.

Cardiomegaly↗
PubMed1979

[Quantitative gated nuclear cardiography in coronary artery disease after administration of isosorbiddinitrate (author's transl)].

The change in left ventricular volume during a representative cardiac cycle was assessed in 19 patients with CAD and 8 control subjects before and after 10 mg isosorbiddinitrate sublingually. 15mCi99mTc-HSA were administered intravenously. After the tracer had equilibrated, the precordial changes of activity were measured with a gamma-camera connected to a computer. In order to determine the overall left-ventricular function from volume curves, the ejection fraction, the maximal systolic ejection rate and the maximal diastolic filling rate of the left ventricle were measured. For the assessment of regional wall motion abnormalities the volume changes were observed in a cinemode on a colour video display. In addition the relative changes of regional EF, regional stroke volume and the timing of endsystole were recorded as a functional scintigram. The results showed very clear differences between control subjects and patients with CAD. Furthermore differences existed between patients with hypokinesia and those with akinesia or aneurysm. The results emphasize that quantitative gated nuclear cardiography not only provides information concerning the left ventricular function but also allows the assessment of local wall motion as to reversible or irreversible asynergy.

Cardiac Output↗
PubMed1979

Binding of complement by complexes between antibodies to nucleic acid constituents and short oligodeoxyribonucleotides.

Oligodeoxyribonucleotides act as inhibitors of the complement fixation caused by complexes between antibodies to defined oligodeoxyribonucleotides and denatured DNA. At concentrations higher than 50 micrograms oligodeoxyribonucleotide/ml complement fixation occurred in the absence of antigen. The extent of complement binding depends on the specificity of the antibodies as well as on the composition of the oligodeoxyribonucleotides. Complement fixation is observed most strongly with antisera to oligodeoxyribonucleotides and to denatured DNA, which belong predominantly to the IgM class. With two LE-sera, containing antibodies to denatured and to native DNA, no complement fixation was found. It is supposed that specific interactions of the oligodeoxyribonucleotides with amino acid residues closely neighbored to the antibody combining site lead to conformational changes in the antibody molecules and to an activation of the complement binding site.

Animals↗
PubMed1978

Disappearance of hoarding and disorganization of eating behavior after ventral mesencephalic tegmentum lesions in rats.

The effects of ventral mesencephalic tegmentum (VMT) radio-frequency lessions on spontaneous and complex behaviors, such as food hoarding and alimentary patterns, were investigated. Activity measures indicated that VMT lesions increased horizontal activity in a circular corridor as well as in an open field whereas vertical activity (rearing) was decreased. After 12 hr of food deprivation, food hoarding and alimentary patterns were evaluated in a square open field to which rats had free access from their home cage. Control rats hoarded food and had organized feeding behavior, but experimental rats did not hoard. Moreover, increasing the open-field illumination did not reverse this deficit. Similarly, the VMT lesion induced disruption of the adaptative alimentary behavior in response to food deprivation. A strong correlation was observed between hoarding scores and the extent of locomotor hyperactivity. These results are discussed in terms of a possible implication of limbic-midbrain mechanisms in which the meso-cortico-limbic dopaminergic A10 neurons originating in the VMT might have a primary role.

Animals↗
PubMed1978

[Quantitative functional analysis of the left ventricle in coronary heart disease. An evaluation of current methods. II. Correlation of results. Global and regional contractility parameters (author's transl)].

In the first part of the present paper, the basic methods for quantitative angiocardiography are described. In the second part, a variety of results are tabulated and discussed, derived from selective coronary arteriography, laevocardiography, left ventricular pressure measurements and heart size as seen on conventional chest X-rays. Various correlations have been derived from these. It was not possible to find an quantitative relationship between coronary sclerosis and myocardial function. The reason for this depends on the fact that the parameters derived from laevocardiography represent integrated global function. The significance of regional contractility is stressed.

Angiocardiography↗
PubMed1978

[Functional scintigraphy during contraction of the left ventricle. III. Findings in patients with coronary heart disease (author's transl)].

Left ventricular volume curves were measured by a noninvasive technique after equilibration of 99m TC human serum albumin in 27 patients with angiographically proven coronary heart disease. Compared with normals, patients with coronary insufficiency showed a significant reduction in the ejection fraction and of maximal emptying and filling times of the left ventricle during rest. In mildly affected patients with normal ejection fractions, maximal filling was already reduced in keeping with the well known loss of compliance of the left ventricle due to coronary disease.

Cardiac Volume↗
PubMed1978

[Fast computer tomography for investigation of the heart--"computer cardiotomography". Methods and early results (author's transl)].

The early results in the investigation of normal and pathological hearts using fast computer tomography are presented. By means of tomographic sections of cadaver hearts, it has been shown that it is possible to distinguish the ventricular cavities and individual cardiac walls by this non-invasive method. Changes in volume of the ventricles and atria due to various forms of stress are easily distinguishable. Myocardial scars can be distinguished from other circumscribed myocardial defects. The particular advantages of this method, which is non-invasive, painless and easily repeatable, do not need to be stressed. The technique adds a significant dimension to previously available non-invasive diagnostic methods, such as ultrasound echo-cardiography.

Aortic Valve↗