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Biomedical subjects

J Schuster

Publications and source records attributed to J Schuster.

At least 55 records · Page 3Linked to original sources
PubMed1989

Systematic investigation of degradation effects on spin-lattice relaxation times in mouse-liver by low resolution NMR.

In spite of numerous work on in vitro proton relaxation time investigations of biological tissue, many questions still remain open. In this study we focused on spin-lattice (T1) relaxation time measurements of mouse liver tissue in order to estimate the time-after-excision effects. The post mortem behaviour of excised tissue was measured up to four hours in intervals of about nine minutes. The time course of liver T1 was determined for different temperatures (4 degrees-40 degrees C) for female mice and the effect of starvation (up to 48 hours) on the time course of T1 was investigated for male and female mice at 37 degrees C. We obtained significant differences in liver T1 time course after excision due to different physiological states like sex, starvation and circadian rhythm.

Animals↗
PubMed1989

[Synthesis of peptides, catalyzed by ficin].

Synthesis of a model peptide Z-Ala-Val-Gly-OH catalyzed by ficin in phosphate buffer was studied with water-soluble esters Z-Ala-OCH2CO-Gly-OH and Z-Ala-OCH2CO-NHC2H4SO3Na as carboxyl components. The maximal yield of the peptide was obtained at pH 8-9. The effect of temperature and concentration of reagents was studied in the model reaction.

Catalysis↗
PubMed1988

[Return to work following myocardial infarct].

The aim of this retrospective study involving 471 patients was to investigate the percentage of patients who returned to work after acute myocardial infarction. In the group of 350 patients who did not undergo subsequent aortocoronary bypass operation 70% returned to work, whereby half of these patients started work again within 6 months after infarction. A significantly higher number of patients who were enrolled in a cardiac rehabilitation programme returned to work as compared with patients not participating in such a programme (72% vs. 59%, respectively; p less than 0.04). There was, however, no difference between these 2 groups with respect to either the time point of resumption of work after myocardial infarction or the duration of employment between infarction and eventual retirement. Of the 121 patients who underwent an aortocoronary bypass operation, only 38% returned to work (p less than 0.001 vs. patients without bypass surgery).

Coronary Artery Bypass↗
PubMed1988

Two level entry concept for analog digital conversion package: usage as blackbox or toolkit.

Analog/Digital conversion of up to 16 channels can be set up and executed interactively with sampling rates individually adjusted for each channel. Additionally, asynchron and parallel digital I/0 is provided, including the possibility of triggering the beginning and the end of data acquisition on an external TTL signal. For non-experienced personnel the package can be run fully interactively with help-menus. Conversely, the experienced user can skip the menu level and directly access the A/D conversion card at the programmers' level in FORTRAN, BASIC or PASCAL. This two level approach considerably enhances the versatility of the package. Data structures in memory and on disk are the same for both levels. Thus, data acquired in menu mode can be compatibly accessed and evaluated from the menu--as well as the programmers' level. Furthermore, a concept is presented for a most efficient and convenient transfer of pre-processed data onto an IBM-mainframe for further analysis in SAS. This transfer scheme allows for continued transparency of the data files, should--for technical reasons or due to changes in the type of data acquired--changes or upgradings of the A/D conversion software become necessary. The package is available for IBM-XT/AT personal computers.

Analog-Digital Conversion↗
PubMed1988

[Pulmonary complications following bone marrow transplantation as seen on the x-ray].

In a retrospective study chest radiographs of 87 bone marrow transplant recipients were analysed. 36 patients had pulmonary complications with lung opacifications. Interstitial changes were more frequent than airspace pneumonias. The latter were caused by bacteria and fungi only. The most common cause of pulmonary complications was cytomegalovirus pneumonia. It was characterised uniformly by a bilateral diffuse interstitial pattern. Idiopathic interstitial pneumonias were indistinguishable from CMV infection. Pneumonias caused by Epstein-Barr virus and protozoa, diffuse radiation pneumonitis and leukaemic infiltrates were rare and also associated with interstitial changes.

Adolescent↗
PubMed1988

[Quantitative assessment of the clinical electroretinogram].

The clinical application of electroretinography has been limited until now by the lack of standardisation, especially of stimulus conditions. Normal values for the electroretinographic response parameters can only be used if patients are examined under the conditions which were given for the examination of healthy subjects. It is shown in this paper that the inexpensive apparatus designed by Kooijman and Damhof (1981) can be calibrated by any user simply and at justifiable expense. Normal values for the amplitudes and peak times for the a- and b-wave are presented. The normal range of the values has been defined with regard to the frequency distribution. According to the authors' results, methods of descriptive statistics in skewed distributions are mainly necessary at low stimulus intensities. The descriptive methods for normal distributions were regularly applied at higher stimulus intensities. In general, however, ERG parameters are normally distributed as shown by the distribution of the residuals between the linear regression of the parameter to the logarithm of the corneal illuminance and the measured values. The influence of age on the amplitude was calculated according to the results of Lehnert and Wünsche (1966) and the lower limits of the normal range are given for four age groups. The data presented here may be used as normal values provided that the simple calibration methods are applied. Thus electroretinography is no longer a method merely for the laboratory, but can be used in clinics and offices as well. However, a prerequisite is that the physician has sufficient experience in ophthalmological electrophysiology.

Adult↗
PubMed1988

Computation of derived diagnostic quantities during intermittent coronary sinus occlusion in dogs.

The haemodynamic responses to pressure controlled intermittent coronary sinus occlusion (PICSO) were recorded intraoperatively in dogs. After analogue-digital conversion the data for coronary sinus pressure were submitted to numerical analysis for detection of systolic and diastolic envelopes and their subsequent fitting by a non-linear model. From the model variables derived quantities, such as plateau and rise times, were constructed so as to resemble the most important features of coronary sinus pressure rise during each occlusion-release cycle. The derived quantities were then monitored during all consecutive cycles throughout the entire experiment. In each dog the measurements were taken during normal coronary artery perfusion, left anterior descending coronary artery infarction, and reperfusion. The analysis comprise time course, stability, and physiological correlates of the derived quantities, on some of which a closed loop regulation may be based. Predicted plateaus (systolic and diastolic) and mean integrals (systolic and diastolic) were found to be stable quantities which, on subaveraging of about five successive estimates, yielded a 10% accuracy on the mean. By contrast, the rise times required subaveraging of about 15 cycles to achieve the same relative stability. It is concluded that, on subaveraging, derived quantities lend themselves for closed loop regulation input. Thus this quantitative assessment of numerical coronary sinus pressure analysis, as obtained from animal data, may lay the basis for future human application.

Animals↗
PubMed1988

Intermittent coronary sinus occlusion in humans: pressure dynamics and calculation of diagnostic quantities.

Pressure controlled intermittent coronary sinus occlusion (PISCO) was applied in 30 patients undergoing coronary artery bypass surgery. The occlusion and release times were manually adjusted according to visual control of the intraoperatively monitored coronary sinus pressure. In six patients the coronary sinus measurements were additionally digitised with a personal computer before postoperative mathematical analysis, which comprised automatic detection of systolic peaks, diastolic troughs, and the calculation of derived quantities. The purpose of the analysis was (a) to assess quantitatively human coronary sinus pressure dynamics, (b) to determine whether visual control and interpretation of coronary sinus pressure rise could be replaced by a mathematical model, and (c) to ascertain whether the occlusion and release cycle lengths were adequate. Numerical estimates for intraindividual and interindividual spread of calculated quantities were produced, the mathematically obtained results were related to a possible physiological interpretation, and the most efficient method of statistical analysis was ascertained. These results form the numerical basis for a closed loop adjustment of pressure controlled intermittent coronary sinus occlusion cycling.

Aged↗
PubMed1988

Changing with the times to keep the meaning of mission.

In the fall of 1987, the Franciscan Sisters of the Poor Health System, Inc. (HSI), took over Madison Square Garden's Felt Forum to hold a fund-raiser. Called the Franciscan Health Care Games, the weekend-long event pitted employees from 14 HSI facilities against one another in basketball and volleyball tournaments; featured 40 stars of film, television, and the sports world in competition; and ended with a gala dinner for 950 people. The event, a first for the Franciscans, raised $800,000. Some of the programs the money will benefit include: The Young Fathers Project, a program in Cincinnati that helps fathers between the ages of 16 and 21 adjust to being a parent. Eldercare, which provides health services to some 5,000 elderly patients at 13 congregate housing sites throughout the Columbus, OH, area. The St. Elizabeth Medical Center in Dayton, OH, which helps support services at a hotel for the homeless sponsored by St. Vincent de Paul Society.

Anniversaries and Special Events↗
PubMed1987

Model of the haemodynamic reactions to intermittent coronary sinus occlusion.

Coronary sinus pressure data have been obtained from anaesthetized dogs during pressure controlled intermittent coronary sinus occlusion. It is the main aim of this paper to provide a mathematical procedure for modelling the typical time course of sinus pressure after temporary obstruction of the sinus. The model is produced by fitting a parameterized function to the systolic and diastolic pressures in order to represent mathematically the shape of the curves. The parameters characterize the rise in coronary sinus pressure following occlusion, and are used to calculate 'derived quantities' which mimic the physician's visual assessment of trace recordings and their clinical implications in certain forms of coronary sinus pressure reaction. This procedure should be thought of as a kind of pattern recognition which reflects the changing state of the myocardium. The mathematical results are shown to bear a close resemblance to the clinical effects of coronary sinus occlusion.

Animals↗
PubMed1987

R-wave amplitude changes during exercise stress testing: patients with dilative cardiomyopathy compared to patients with coronary artery disease.

R-wave amplitude (RWA) depends to a large extent on the left ventricular filling volume. Changes of RWA are attributed to the Brody-effect. Exercise has been shown to induce a decrease of RWA in a healthy population and an increase in patients with coronary artery disease (CAD). No clear data exist for cardiomyopathy (CMP). Controls (n = 12), patients with CMP (n = 32) and CAD (n = 58) were compared. Alterations of RWA (Wilson lead V5) were correlated with parameters of a bicycle exercise test including resting and exercise hemodynamics and parameters of LV-function including EF, LVEDV and LVEDP. CMP compared to CAD had smaller RWA at rest (0.78 +/- 0.47 vs 1.32 +/- 0.72 mV, P less than 0.01). During comparable levels of exercise CMP (EF 35 +/- 14%) showed no significant changes of RWA. CAD (EF 57 +/- 16%) presented an increase of RWA by +0.11 +/- 0.23 mV (P less than 0.01), while controls showed a straight decline of RWA (-0.31 +/- 0.24 mV). In patients with CAD delta RWA (RWA max exercise - RWA rest) was a more sensitive parameter for detection of disease (assuming delta RWA greater than or equal to +0.1 mV, 36/58 patients) than maximal ST-segment changes (ST-segment-depression in lead V5 greater than or equal to 0.2 mV at 0.08 sec after J-point, 22/58 patients). Precordial leads V2, V4, V5 and V6 showed similar changes. This paper supports the theory that changes of wall thickness or changes in the amount of air respective to the amount of fluid in the lungs are responsible for RWA changes. These changes are clearly dependent on the severity of the disease and on left ventricular function. Therefore measurement of RWA changes during exercise may offer additional information in patients with CAD as well as in patients with CMP.

Adult↗
PubMed1987

[Sonographic findings in 133 malignant breast tumors in relation to their connective tissue content].

The sonographic results of 133 histologically proven breast malignancies are reviewed retrospectively and compared with the physical, mammographic and histopathologic findings. All tumours are classified in three groups according to their cell-fibrous tissue relation. The ultrasound features that are typical of each category are demonstrated and discussed. A close relationship is found between the sonographic findings and the amount of connective tissue in breast carcinomas. Tumours with a predominance of fibrous tissue show sonographic characteristics regarded as typical of malignancy, such as irregular form, hazy contours, heterogeneous internal echos, and dorsal acoustic middle shadow. In contrast, ultrasound findings suggestive of benign lesions--regular form, smooth contours, increased dorsal echos--prevail in carcinomas with little connective tissue. Because of its superior accuracy in detection of carcinoma in radiodense breasts, sonography is a useful complementary method to mammography. On the other hand, echography cannot replace mammography as a screening method, since its sensitivity in detecting non-invasive and small carcinomas is distinctly lower.

Adult↗