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Biomedical subjects

H Simon

Publications and source records attributed to H Simon.

At least 217 records · Page 12Linked to original sources
PubMed1985

[New therapeutic concepts in fractures of the bony orbits and zygoma].

The causes, types and degrees of zygoma fracture and fractures of the orbital floor and the orbital rim are described in general. The preoperative clinical signs, as seen from the viewpoints of the oto-rhino-laryngologist, the ophthalmologist, and the maxillofacial surgeon, combined with exact x-ray or computer tomograms, determine the timing of the action to be taken by the specialist. Endoscopy of the nose and the maxillary sinus by removing blood clots with an aspirator is of diagnostic as well as therapeutic value. The pros and cons of the different operation techniques are discussed. In blow-out fractures which need a reinforcement of the orbital floor, advantages and disadvantages of several autoplastic, and alloplastic materials are compared. Wire fixation technique is described along with the indication for miniplate osteosynthesis and the support by a balloon catheter. Own results using the ballon catheter emphasise the successful and risk-free technique.

Bone Plates↗
PubMed1985

[Clinical liver transplantation in East Germany].

In the GDR 28 liver transplantations have been performed up to now. The 1 year survival rate amounts to 30%. At present 8 patients are alive between 3 months and 5 years. There were no biliary complications since the biliary reconstruction was performed by using a special 'mucosa suture'-technique. Ischaemic graft failure was a main cause for early postoperative mortality. A better immunosuppressive treatment may help to improve the results of liver transplantation in future.

Adult↗
PubMed1985

[Regeneration of liver parenchyma and sinusoidal cells following partial hepatectomy].

Partial hepatectomy (30 percent of the liver weight) was performed in 225 female Wistar rats, ages 6 weeks, 6 and 9 months. The animals were sacrificed in intervals between 4 hours and 21 d after the operation. The automated microscopic image analysis after Simon et al. (1984) and histoautoradiography were utilized for evaluation of liver cell regeneration. Despite measurement of more than 1,000 cells per animal we were not able to confirm enlargement of hepatocytes as the first reaction to partial hepatectomy The number of liver cells per unit area increased whereas sinusoidal size remained rather constant, corresponding to a decrease in average cell size and in the standard deviation of cell area. The importance of binucleated hepatocytes in the process is emphasized. Measurement of the nucleoli and of the mean extinction values of liver cell nuclei as a measure of the DNA content did not provide any essentially new perspectives. The investigation did however emphasize the importance of the extent of the hepatic resection and the age of the experimental animals on the intensity and subsequent course of liver cell regeneration. Proliferation of the sinusoidal cells themselves after partial hepatectomy could not definitively be demonstrated to be age-dependent.

Age Factors↗
PubMed1985

The influence of vegetative stimuli on the human nasal mucous membrane.

Measuring probes were inserted into the inferior nasal meatus in humans to record the effects of certain defined vegetative stimuli on the cavernous state and the temperature of the mucous membrane. An unilateral carotis compression induces a bilateral reactivity of the mucous membrane in the sense of a sympathicus stimulus. An unilateral bulbus pressure causes a bilateral reaction of the mucous membrane opposite to that of carotis compression. Blocking of the stellate ganglion produces a tonus reduction of the nervus sympathicus as was also found in animal experiments by other authors. Trigeminus stimulation induces a swelling of the nasal mucous membrane, whereas a voluntary breathing stop causes decongestion. Facial blushing, the only undefined and involuntary stimulus, is followed by an unswelling and a decrease of mucous membrane temperature. The results of our investigations are in agreement with analogous animal experiments. This is not surprising as man has a vegetative nervous system which is essentially unchanged from the beginning of evolutionary development. Only blushing is an expression of a reaction behaviour characteristic of human beings only.

Adult↗
PubMed1984

[Value of histopathologic findings following liver transplantation based on biopsy course studies].

A total of forty-four biopsies from nine liver transplantation patients, who had developed complications postoperatively, were studied histologically and, in part, electron-microscopically. Morphologic signs of acute rejection were seen in three patients, while there were indications of chronic rejection in one patient. In combined lesions, such as drug-induced hepatosis, cholangitis, hepatitis, and rejections, the interpretation of biopsy findings may be difficult, and special entities cannot in every case be separated unequivocally. Changes of serum bilirubin and of serum enzyme activity do not run entirely parallel to the microscopically detectable structural lesions. For diagnosis of complications after liver transplantation both the morphologic and the clinical findings must be considered.

Adult↗
PubMed1984

Functional recovery following transplantation of ventral mesencephalic cells in rat subjected to 6-OHDA lesions of the mesolimbic dopaminergic neurons.

Lesion of mesolimbic dopaminergic neurons induces hypoactivity and hypo-exploration in a new environment, lack of hyperactivity to amphetamine and hyperresponsiveness to apomorphine. Transplantation of embryonic dopaminergic cells from rat embryos into the deafferented nucleus accumbens restores, 8 weeks after grafting, some of the deficits obtained after the lesion. Spontaneous activity and behavioral responses in an open-field are improved and some of the grafted rats show a complete recovery of amphetamine-induced hyperactivity. However, hyperresponsiveness to apomorphine has not been significantly reduced by the treatment. These results indicate that transplanted dopaminergic neurons can restore some of the functional activities of the n. accumbens.

Animals↗
PubMed1984

Neuroleptic-like disruption of the conditioned avoidance response requires destruction of both the mesolimbic and nigrostriatal dopamine systems.

An examination of the ability to learn an active avoidance response was made in rats subjected to 6-hydroxydopamine (6-OHDA) lesions of the individual terminal areas of the midbrain dopamine (DA) system or a lesion to all these terminal regions in one group. Lesions were made by infusing 8 micrograms (base) of 6-OHDA in 2 microliter of vehicle into the following forebrain regions (each region representing a separate group of rats); frontal cortex, nucleus accumbens, corpus striatum and a double lesion of nucleus accumbens and corpus striatum. A separate group of rats received a smaller 6-OHDA lesion of the ventral substantia nigra. Only those rats with the combined double lesion of both the nucleus accumbens and corpus striatum (90% total depletion of dopamine) showed a severe deficit in acquisition of active avoidance. However, the rats with the separate 6-OHDA lesions to the mesolimbic or nigrostriatal DA systems did show the appropriate blockade of the amphetamine-induced locomotion or stereotyped behavior, respectively. In contrast, the rats with the double lesion showed no response to a low or high dose of amphetamine, remained cataleptic for the duration of the experiment but rapidly recovered from transient aphagia and adipsia (less than 10 days post lesion). Results suggest that a severe deficit in acquisition of an active avoidance response, similar to that observed with high doses of neuroleptics, requires destruction of all of the dopamine innervation of nucleus accumbens and corpus striatum. Results also suggest that both the mesolimbic and nigrostriatal dopamine systems act in concert to produce response enabling to important environmental events, and that the severe response enabling deficits observed in Parkinson's disease involves not only degeneration of the nigrostriatal dopamine system, but of the mesolimbic dopamine system as well.

Animals↗
PubMed1984

Cortical cholinergic projections from the basal forebrain of the rat, with special reference to the prefrontal cortex innervation.

The topographic organization of cells containing choline-acetyltransferase (CAT) and located within the magnocellular nuclei of the basal forebrain was studied by correlating maximum CAT decrease in one or another cortical region with a given localization of the cell lesions. Lesions were made by using ibotenic acid. Lesions affecting the ventral pallidum decreased CAT activity in the antero-medial prefrontal cortex and lesions of the internal and ventral borders of the pallidum decreased CAT activity in sensori-motor and parieto-temporal cortices. None of these lesions produced a decrease of CAT activity in the hippocampus. These results suggest that it is possible to show the presence of a specific cholinergic projection from the basal forebrain to the medial-associative prefrontal cortex of the rat.

Animals↗
PubMed1984

6-Hydroxydopamine lesion of the dopamine mesocorticolimbic cell bodies increases (+)-amphetamine self-administration.

The effect of 6-OHDA lesions of the dopaminergic mesocorticolimbic cell bodies on intravenous (+)-amphetamine self-administration in the rat was assessed. An acquisition paradigm was used in which the rat had to discriminate between an active and an inactive lever. Each press on the active lever delivered 7.5 micrograms/kg (+)-amphetamine. The lesioned animals acquired this discrimination faster and hence self-administered a larger amount of drug. Thus dysfunction of dopaminergic neurons can induce an enhanced vulnerability to drugs which may be abused by humans.

Animals↗
PubMed1984

Contributions of the mesencephalic dopaminergic system and the trigeminal sensory pathway to the ventral tegmental aphagia syndrome in rats.

Four experiments examined the neural substrates for the aphagia and adipsia syndrome resulting from damage of the ventral tegmental region. Radiofrequency (RF) lesions at the level of the mesencephalon in rats showed that the most effective site for producing aphagia and adipsia was in an intermediate zone between the substantia nigra and the ventral tegmental area. Injection of the neurotoxin 6-hydroxydopamine (6-OHDA) into this intermediate zone led to a less severe feeding deficit, suggesting that both dopaminergic and non-dopaminergic neurons are involved in the mesencephalic aphagic syndrome. As the lemniscus trigeminalis was destroyed after the RF lesion of the intermediate zone, the hypothesis of trigeminal projection involvement was tested by lesioning (RF) the sensory trigeminal nucleus. These rats were aphagic but they recovered and their deficit was less severe than after RF lesion of the mesencephalic intermediate zone. In the last experiment, a combined 6-OHDA lesion of the mesencephalic intermediate zone and RF lesion of the trigeminal sensory nucleus led to a more severe deficit in feeding behavior than either lesion alone. These results further demonstrate that feeding behavior is under the control of a complex system involving several neural pathways.

Animals↗
PubMed1984

The nose as an indicating organ of vegetative controlling mechanisms.

Long-term examinations on test persons of an average age of 28 years were carried out by means of thermistors for measuring the mucous membrane temperature and by means of photo transistors for measuring the state of cavernous tissues. The tactile stimulus during the insertion of the probe regularly leads to a temperature increase and a swelling of the nasal mucous membrane. Pronounced changes in the temperature do not take a linear course but are interrupted by intercurrent temperature inversions. The changes in the state of cavernous tissues take a course synchronous to this. After the first tactile stimulus there adjusts a preliminary temperature equilibrium in the mucous membrane temperature and in the cavernous state. Then there follow temperature oscillations taking a completely different course, of changing amplitudes and frequencies. These temperature oscillations may take courses in the same or in opposite directions in the two nose halves. The causes proposed for discussion, on the one hand for the intercurrent temperature inversions in case of considerable temperature changes, and on the other hand for the differing temperature oscillations after the attainment of the preliminary temperature equilibrium, are central regulating mechanisms, while at the same time analogous animal experiments are taken into consideration.

Adult↗
PubMed1984

[Comparative protein analytic studies of various intravenous 7S-immunoglobulin preparations].

Seven different commercial intravenous 7S-immunoglobulin preparations have been examined by electrophoresis, immunoelectrophoresis, quantitative determination of immunoglobulins and other proteins, gel chromatography and analytical ultracentrifugation. No significant difference concerning IgG and monomeric immunoglobulin concentrations was observed. The content of IgM, dimers and polymers showed slight, that of IgA considerable differences. All immunoglobulin preparations comply with the European Pharmacopoea requirements. The rate of adverse reactions should be equally low due to similar dimer and polymer contents. IgA-free preparations are considered to be more suitable in primary hypogammaglobulinaemia whereas IgA-containing preparations could be of benefit in acquired hypogammaglobulinaemia. While the presence of an intact immunoglobulin molecule is thought to be essential for its full therapeutic efficacy, the influence of the preparation method is still in debate.

Blood Protein Electrophoresis↗
PubMed1984

Cardiac metabolism of 15 (p-I-123 phenyl-) pentadecanoic acid after intracoronary tracer application.

Myocardial turnover of omega-(p123I-Phenyl-) pentadecanoic acid and release of its metabolites into the coronary sinus and peripheral blood has been studied in patients with coronary artery and valvular heart disease. After intracoronary tracer injection myocardial extraction fractions of 45-53% in control subjects were observed. In patients with coronary artery disease (CAD) normal to reduced values (34-61%) were established. Hydrophilic catabolites of I-PPA, probably p123I-benzoic and -hippuric acid as well as small amounts of the non-metabolized tracer were found in coronary sinus and peripheral blood. Myocardial tracer uptake and clearance patterns were clearly different in normal myocardium when compared to that obtained in patients with CAD. Thus, evaluation of myocardial I-PPA metabolism might provide a new diagnostic tool for assessment of integrity of the heart's muscular metabolic function.

Coronary Disease↗
PubMed1983

On the occurrence of enoate reductase and 2-oxo-carboxylate reductase in clostridia and some observations on the amino acid fermentation by Peptostreptococcus anaerobius.

Enoate reductase present in Clostridium kluyveri and Clostridium spec. La 1 could be detected in three strains of C. tyrobutyricum and ten clostridia belonging to the groups of proteolytic and saccharolytic or proteolytic species, respectively. In C. pasteurianum, C. butyricum and C. propionicum enoate reductase could not be found even after growth on (E)-2-butenoate. A 2-oxo-carboxylate reductase was present in rather low activities in the non-proteolytic clostridia which produce enoate reductase. High activities (up to 10 U/mg protein) of 2-oxo-carboxylate reductase were found in six of ten proteolytic clostridia. The substrate specificities of the enoate reductase and the 2-oxo-carboxylate reductases from the proteolytic clostridia were determined with different alpha, beta-unsaturated carboxylates (enoates) and 2-oxo-carboxylates, respectively. Enoates as well as 2-oxo-carboxylates are intermediates of the pathway by which amino acids are degraded. An explanation is offered for the long known but not understood fact that in the Stickland reaction isoleucine always acts as an electron donor and leucine and phenylalanine can be electron acceptors as well as donors. Peptostreptococcus anaerobius converting some amino acids to the same products as C. sporogenes did this also with the intermediates which were found for the reductive deamination of amino acids in C. sporogenes, however, in crude extracts reduction of enoates occurred only in an activated form.

Alcohol Oxidoreductases↗
PubMed1983

[Digital subtraction angiocardiography].

One hundred patients with a variety of cardiac abnormalities were examined by digital subtraction angio-cardiography; the quality of the image was almost as good as conventional cinecardiograms. Image frequency of 25 pictures per second provides a reliable analysis of cardiac contraction and, in many situations, makes it unnecessary to perform selective angio-cardiography. Compared with selective catheter techniques, digital subtraction cardiography has various advantages. Because of its low risk and small patient stress, it is particularly suitable for follow-up examination after various therapeutic measures.

Adult↗
PubMed1983

On nitroaryl reductase activities in several Clostridia.

Crude extracts of Clostridium kluyveri, Clostridium spec. La 1, Clostridium sporogenes and Clostridium pasteurianum catalyse the NADH-dependent reduction of the nitro group of p-nitrobenzoate. The former three Clostridia also use pyruvate as electron donor for this reduction. The NADH-dependent reductases have been partially purified and characterized from Clostridium kluyveri. Nitroalkyl compounds as well as nitrite, sulfite, sulfate and hydroxylamine are no substrates. Based on chromatographic behavior, separation pattern, yields, stability, pH optima, molecular masses and EPR studies the three NADH-dependent nitroaryl group reducing enzymes in Clostridium kluyveri (three activities in Clostridium spec. La 1 and two activities in Clostridium sporogenes) are different from alcohol dehydrogenase, aldehyde dehydrogenase, 3-hydroxy-butyryl-CoA dehydrogenase, butyryrl-CoA dehydrogenase, 2-enoate reductase, ferredoxin-NAD and ferredoxin-NADP reductase. The physiological roles of the nitroaryl reductases are not known. The reductase activities show losses of 80-90% during classical protein purification procedures. One of the three nitroaryl reductases exhibits a pH optimum of 10.5. The crude extract reveals a pH optimum at 11.5. The first step of the reduction reaction leads to the nitroradical anion (1 electron transfer). The electron transfer to p-nitrobenzoate is also catalysed by ferrodoxin-NAD reductase from NADH and by ferredoxin-NADP reductase from NADP. Partially purified 2-oxo-acid synthases from Clostridium sporogenes catalyse with low rates the reduction of p-nitrobenzoate as well as 2-nitroethanol in the presence and absence of ferredoxin using pyruvate or 2-oxo-4-methylpentanoate as electron donors, respectively. The NADH-dependent reduction of p-nitro-benzoate accounts for at least 70% and the 2-oxo acid-dependent reduction for about 5% of the total nitroaryl reductase activity in the Clostridia. It seems that the pyridine nucleotide-dependent nitroaryl reductases are enzymes so far unknown in Clostridia.

Clostridium↗