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Biomedical subjects

J Schuster

Publications and source records attributed to J Schuster.

At least 19 recordsLinked to original sources
PubMed1992

The non-random dic(9;12) translocation in acute lymphoblastic leukemia is associated with B-progenitor phenotype and an excellent prognosis.

A dicentric translocation involving the short arms (p) of chromosomes 9 and 12 was identified in 15 of 2303 successfully banded cases of acute lymphoblastic leukemia (ALL) in children, consecutively entered on protocols of the Pediatric Oncology Group (1986-1990) or St Jude Children's Research Hospital (1984 and 1990). The dic(9;12)(p1?1;p1?2) was seen only in patients with a B progenitor cell immunophenotype: the frequency was 0.8% among pre-B cases (4/508) and 0.9% (11/1177) among early pre-B cases. Laboratory and clinical characteristics were similar to those of the general population of children with ALL, with the exception of a marked male preponderance (12/15 cases). Flow cytometric studies revealed a leukemic cell DNA index of 1.0 in all cases. All fifteen patients are in continuous complete remission at a median follow-up duration of 57+ months (range 9-93+ months). These findings suggest that the dic(9;12) is a recurrent chromosomal translocation in pediatric ALL, occurs exclusively in B-progenitor ALL, and unlike other non-random translocations, is associated with an excellent prognosis.

Adolescent↗
PubMed1990

Transoesophageal pacing for perioperative control of neonatal paroxysmal supraventricular tachycardia.

The perioperative management of a 16-day-old infant with recurrent supraventricular tachycardia (SVT) is discussed. Vagal manoeuvres and medication were not adequate in controlling the SVT. Since the patient was scheduled for extensive surgery in the prone position, it was decided to use transoesophageal pacing as the method of choice for conversion of SVT. Transoesophageal pacing succeeded several times in overriding the SVT and restoring normal heart rate and haemodynamic variables. The advantages and disadvantages of various methods of treating SVT in the newborn are discussed.

Cardiac Pacing, Artificial↗
PubMed1990

The distally-based radial forearm free flap with valvulotomy of the cephalic vein; a preliminary report.

The radial forearm free flap is widely used in microsurgical reconstruction where a thin, hairless flap is required. While the radial artery may be based either proximally or distally, the venous drainage is generally proximally based in order to provide normal flow through the valves. We have utilised this flap in two patients, based distally on both the radial artery and cephalic vein by removing the valves of the cephalic vein. This technique has been employed widely in peripheral vascular surgery of the lower limb and is called the "in-situ" technique. We have found it to be efficacious in taking a proximal skin paddle, which decreases donor site morbidity and allows for a long vascular pedicle. This paper reports on these two patients and describes the technique of valvulotomy of the cephalic vein.

Adult↗
PubMed1990

[Pulmonary transfer factor for carbon monoxide (TLco) in healthy children and in children with chronic lung diseases, measured with an improved rebreathing technique].

TLco, FRC-He and IVC were tested in 86 subjects (5-29 years). 46 children were healthy, 21 patients had cystic fibrosis, 13 bronchial asthma and 6 allergic alveolitis. The test gas included 14% helium and 0.3% CO. The wash in time was 18 s, the measuring time 20 s. All children were measured at rest and in a sitting position. The rebreathing volume was 3/4 of the VC plus 300 ml additional volume. The results showed a good reproducibility. The TLco increases with age, height, weight and body surface area, the correlation with VC, FRC and TLC was better. A differentiation between healthy children and patients suffering from lung disease is possible. The clearest results were shown in the case of patients suffering from CF.

Asthma↗
PubMed1989

Computation of diagnostic data from coronary sinus pressure: a comparison between two possible models.

We have evaluated two mathematical models to describe the increase in coronary sinus pressure (CSP) following pressure controlled intermittent coronary sinus occlusion (PICSO). The models are evaluated and compared on the basis of human and canine data. Both models were fitted by non-linear least squares algorithms. Next, derived quantities, such as plateau, rise-time and mean integral of the coronary sinus pressure were calculated from the model parameters. Corresponding quantities for the two models were compared with regard to mean values, rate of successful calculation and specific features characterizing the human or canine case. One model was found to be superior for investigational purposes. The other model was found to be more stable in critical situations and is therefore suggested for usage in closed loop regulation of PICSO. Physiologically, the differences in mean values of the derived quantities between the two models were found to be negligible. The formal statistical significance of the differences is but a consequence of the large number of PICSO cycles analysed.

Algorithms↗
PubMed1989

Analysis of relaxation time data from a low-resolution 1H-NMR-pulse-spectrometer.

Systematic investigations have been undertaken in order to evaluate the potential of low resolution NMR for characterization of biological tissue (in vitro) during early post mortem period. Test measurements from corn-oil samples are compared with computer simulated data. Furthermore, time-after-excision dependence of mouse-liver tissue is presented using the in vitro protocol developed in our laboratory. Quantitative data from biexponential model fit are shown and results are discussed in terms of the "best guess" model.

Animals↗
PubMed1989

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

Despite numerous work on spin-lattice (T1) relaxation in vitro, not much attention has been paid on spin-spin (T2) relaxation until now. In this study we are presenting spin-spin relaxation time measurements of mouse liver tissue in order to estimate the time-after-excision effects. The post mortem behaviour of excised tissue was investigated up to four hours in intervals of about nine minutes. The time course of liver T2 was determined for different temperatures (4 degrees - 40 degrees C) for female mice. In order to describe the similar behaviour of T2 and pH changes in mouse liver after excision, we are suggesting an empirical model to correlate this data. In contrast to T1 results published recently, we found no significant differences in liver T2 time course after excision due to different physiological states like sex, starvation or circadian rhythm. T1/T2-behaviour after tissue excision is discussed in an attempt to separate various relaxation mechanisms.

Animals↗
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↗