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Biomedical subjects

U Schmidt

Publications and source records attributed to U Schmidt.

At least 361 records · Page 20Linked to original sources
PubMed1986

Ultrastructural study comparing the efficacy of five different methods of intraoperative myocardial protection in the human heart.

The quality of myocardial protection during cardiac arrest in cardiac operations was investigated in 310 patients. Eighty patients underwent aortic valve replacement and 230 had coronary artery bypass grafting. Four different cardioplegic solutions (Kirsch, Bretschneider, St. Thomas' Hospital, and Hamburg) and the method of induced fibrillation were tested by ultrastructural analysis of the degree of ischemic injury at the end of the cardiac arrest period. Hypothermia was identical in all five groups. In this study, subendocardial and subepicardial needle biopsies were evaluated by a standardized scoring system. Chemical cardioplegia produced mainly moderate ultrastructural injury independent of the time of ischemia. Kirsch cardioplegia and the intermittent fibrillation procedure produced ischemic injury of greater and unpredictable severity. Only with Kirsch cardioplegia was a correlation observed between the duration of intraoperative arrest and the degree of injury, which is indicative of a lack of myocardial protection. The tolerance to ischemia was significantly better in patients undergoing bypass grafting than in those with aortic valve disease and therefore longstanding hypertrophy. In conclusion, the Bretschneider, St. Thomas' Hospital, and Hamburg solutions provide satisfactory myocardial protection but are not able to completely prevent myocardial ischemic injury. Kirsch cardioplegia and the intermittent fibrillation procedure provide insufficient myocardial protection. Patients with left ventricular hypertrophy are at a greater risk during cardiac operations than patients undergoing coronary bypass operations.

Aortic Valve↗
PubMed1986

[Toxoplasmosis after bone marrow transplantation].

An opportunistic infection with Toxoplasma gondii is a rare complication in the immunocompromised host following bone marrow transplantation. In addition to the variability in the clinical picture, difficulty in interpretation of the antibody titers is one of the main obstacles limiting early diagnosis of manifest toxoplasmosis. This report deals with 3 patients out of 86 bone marrow transplant recipients who had manifest toxoplasmosis mainly affecting the central nervous system and cardiac muscle. The clinical picture was that of acute disseminated encephalitis and myocarditis, while the nature of the disease was only disclosed at autopsy.

Adult↗
PubMed1986

[The dissemination of Salmonella by meat and meat products from swine].

Pork and pork products which are consumed raw, e.g. mincemeat or fresh Bologna sausage, are relatively often contaminated with salmonellae. In the average of one year we detected salmonellae in about 5% of the samples investigated. Due to seasonal and local influences up to 45% of the minced meat samples can be positive for salmonellae. In minced meat salmonellae grow only at temperatures above 7 degrees C. During frozen storage of meat for several weeks, the salmonella count decreases on an average of about 50%. A damaging of surviving salmonellae by the freezing and thawing process was not observed. On the contrary, in thawed mincemeat stored at 8 degrees C the growth of salmonellae is stimulated, i.e. they grow better than in mincemeat not frozen before. Growth of salmonellae in Bologna sausage ("frische Mettwurst") can be inhibited by adding of at least 2.5% nitrit curing salt, 0.3% glucono-delta-lactone, and lactic acid starter cultures, even if the product is stored at temperatures up to 25 degrees C. Likewise in spreadible and sliceable fermented sausage ("streichfähige und schnittfeste Rohwurst") no growth of salmonellae is to be expected, if a similar technology secures a sufficient microbiological stability during the ripening and smoking process. Therefore, the dissemination of salmonellae by pork and pork products can be avoided by technological measures, but also by a reasonable conduct of the consumer in the household.

Animals↗
PubMed1985

Species differences in the formation of butadiene monoxide from 1,3-butadiene.

When 1,3-butadiene is incubated with liver postmitochondrial fractions from mouse, rat, monkey or man and a NADPH-regenerating system, the formation rate of butadiene monoxide is different in the four species. With the exception of the rhesus monkey, the amount of epoxide is proportional to the monooxygenase activity. The sequence of epoxide formation is B6C3F1 mouse, Sprague Dawley rat, man, rhesus monkey. The ratio between mouse and monkey was about 7:1. When 1,3-butadiene is incubated with homogenates from lung tissue, only tissues from mouse and rat produce measurable butadiene monoxide concentrations. The monooxygenase activity in lung tissue of the mouse was only 1/30 that in mouse liver. By contrast, lung tissue formed epoxide concentrations comparable to those formed by liver tissue, whereas monkey and human lung tissue did not produce any measurable levels of butadiene monoxide. The data might suggest that the results of recent rodent inhalation studies with 1,3-butadiene could not automatically be extrapolated to man.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1985

The onset of senescence is affected by DNA rearrangements of a discontinuous mitochondrial gene in Podospora anserina.

Mapping and transcription studies have revealed that in Podospora anserina the causative agent of senescence, a mitochondrial plasmid (plDNA), is identical with intron 1 of the discontinuous gene for cytochrome-c-oxidase subunit 1 (COI), which is 2 kpb from the discontinuous gene for cytochrome b (Cytb). A mitochondrial mutant (ex1) devoid of the COI, but not of the Cytb gene provides longevity. A molecular model for the onset of senescence is presented.

Amino Acid Sequence↗
PubMed1985

The influence of moderate-intensity noise on the click-evoked compound action potential of the guinea pig, Cavia porcellus.

Noise-induced alterations of the click-evoked compound potential (CAP) were studied by means of electrodes chronically implanted near the round window in 15 pigmented guinea pigs aged 3-6 months. The potentials were recorded before, during and after exposure to continuous pink noise maintained at an intensity of 80, 90 or 100 dB SPL for 120 h. During the exposure phase the CAP thresholds of all the animals tested increased exponentially, nearly leveling out by approximately 48 h to form an asymptotic threshold shift. Recovery after the end of exposure also occurred exponentially, with a return to the original threshold for neural excitation after at most 72 h. There was no detectable change in amplitude, latency or inter-peak interval of the CAP when correlated with the change in threshold.

Acoustic Stimulation↗
PubMed1985

Ontogenetic development of neural responses in the olfactory bulb of laboratory mice.

In laboratory mice (strain NMRI) the ontogenetic development of single unit activity in the olfactory bulb was investigated. From postnatal day 10 on, spontaneously active neurons were recorded with glass-microelectrodes, and their responses to olfactory stimuli were tested (butyric acid, geraniol, grass- and nest-odour). From day 10 to 13 only very few neurons were recordable (and most of these elements were too weak and were lost before being stimulated). At day 14 the number of recordable neurons increased rapidly, and by day 15 spontaneously active neurons reached adult level in terms of incidence and electric properties. There were 3 types of neurons: respiration synchronous elements; bursting neurons not correlated with respiration; continuously, but randomly, firing elements (about 60% of all neurons). Reactions to odour stimuli (excitation, ca. 50%; inhibition, ca. 34%; complex reactions, ca. 12%; change in activity pattern, ca. 4%) occurred as soon as the cells were stable enough for testing. The reaction patterns showed no age specific differences; the duration of the responses varied from 100 ms to 100 s. In younger animals (P11-P14) the percentage of responses was slightly smaller (47%) than in the older ones (P30-P50; 64% response to olfactory stimulation). For some of the odours tested the proportion of responding cells differed depending on age (for instance grass odour evoked a response in 40% of the cells in young ones, but in 65% in adults).

Action Potentials↗
PubMed1985

Inhibition of human and canine diamine oxidase by drugs used in an intensive care unit: relevance for clinical side effects?

Three hundred and forty-one drugs, commonly used in intensive care units (ICU), were chosen for an investigation of possible activation or inhibition of the histamine metabolizing enzyme diamine oxidase (DAO). After examination of 164 substances, using both canine and human DAO in an in vitro screening test, 61 agents inhibited DAO activity to various degrees. Of these, 44 inhibited the enzyme from both species, 4 inhibited the canine enzyme only and 13 the human DAO only. No compound tested was able to enhance the enzyme activity. The inhibiting agents included representatives of all major therapeutic groups. A particularly strong inhibition was observed with the neuromuscular blocking drugs d-tubocurarine, pancuronium and alcuronium, however, the other commonly used neuromuscular blocking drug, suxamethonium, was without effect. Similarly with the cephalosporines, cefotiame and cefuroxime caused a marked inhibition of the human DAO activity, whereas another regularly-used substance of this class, cefotaxime, inhibited neither the human nor the canine enzyme in concentrations up to 10(-3) M. The observation that within a given therapeutic group some members inhibit and others do not, could be useful in choosing a therapy concept which minimizes the risk of a more severe 'histamine' reaction in seriously ill patients.

Amine Oxidase (Copper-Containing)↗
PubMed1985

The influence of permanent odor stimuli on the postnatal development of neural activity in the olfactory bulbs of laboratory mice.

Young laboratory mice were kept from birth in a surrounding with one dominating synthetical odor substance (geraniol, C10H18O; experimentals); the controls were bred under normal conditions. Between postnatal days 10 and 35 the development of the neural activity in the olfactory bulb and the response to the synthetical (geraniol) and a natural odor (nest material) were tested at 6 different stages of age. By means of a computer the total energy and the frequency composition (power spectra) of the electrophysiologically leaded potentials were analyzed at the time of stimulation and without stimulation. The developmental increment of neural activity was retarded at the experimentals, but the typical high-frequency waves (oscillations) appeared about 5-6 days earlier than in the controls. Both odor substances induced neural responses measured by energy and frequency changes in the power spectra. In controls none of the odors leads to noticeable changes in the composition of frequencies at days 10 and 14. Beginning at postnatal day 18 the odor substances of nest material evoked increasing neural reactions; at all stages of age geraniol induced only slight alterations in the power spectra. In the experimentals responses could be measured first at day 14. The changes in power spectra rapidly increased in the following 3 weeks and the responses to geraniol reached several times more intense levels than in the controls. The influence of permanent olfactory stimuli on the ontogenetic development of the olfactory bulb and the extreme plasticity of this system are discussed.

Acyclic Monoterpenes↗
PubMed1985

The influence of moderate-intensity noise on the compound action potential evoked by tone bursts in the guinea pig, Cavia porcellus.

Noise-induced changes in the compound action potential (CAP) evoked by tone bursts in the frequency range 0.5-24 kHz were studied in 15 pigmented guinea pigs by means of chronically implanted electrodes positioned near the round window. The animals were exposed for 120 h to continuous pink noise at the intensities 80, 90 and 100 dB SPL. During the exposure period, all the animals exhibited an exponential rise in CAP threshold, leveling out after 24-72 h (asymptotic threshold shift, ATS). The largest threshold shifts were recorded during exposure to 100 dB SPL, for frequencies in the range 8-12 kHz. In the recovery phase, after the end of noise exposure, the threshold to tones at all frequencies tested fell exponentially, reaching the original level in about 72 h in all cases.

Animals↗