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Biomedical subjects

U Roth

Publications and source records attributed to U Roth.

At least 19 recordsLinked to original sources
PubMed1992

Role of the oral calcium-loading test with measurement of intact parathyroid hormone in the diagnosis of symptomatic subtle primary hyperparathyroidism.

BACKGROUND: This study was designed to assess the diagnostic value of the oral calcium tolerance test with measurement of intact parathyroid hormone by the immunoradiometric assay (IRMA PTH) in the diagnosis of primary hyperparathyroidism in patients with symptoms who have minimal, intermittent, or no elevation of the levels of total calcium and/or intact PTH. METHODS: After baseline levels of IRMA PTH and total calcium were measured, an oral calcium load of 1000 mg elemental calcium was administered to 10 patients with hyperparathyroidism and 18 normal control subjects. Total calcium and IRMA PTH levels were measured at 30, 60, and 120 minutes after the oral calcium load was administered. RESULTS: The mean suppression of the baseline level of IRMA PTH in the patients with hyperparathyroidism was 83.7% +/- 6.5% (mean +/- 1 SEM), but the levels of the normal control subjects fell significantly (p < 0.05) lower to 58.8% +/- 3.7% (mean +/- 1 SEM). CONCLUSIONS: This study suggests that the oral calcium tolerance test may be a valuable adjunct in confirming the diagnosis of primary hyperparathyroidism in patients with symptoms who have minimal, intermittent, or no elevation of the levels of total calcium and/or IRMA PTH:

Administration, Oral↗
PubMed1991

[The value of angiodynography in follow-up of surgical vascular prostheses].

Apart from the proximal anastomosis, aortoiliac/-femoral bypass is accessible to angiodynography. The spectral waves can mostly be derived and analyzed very well. Femoropopliteal grafts can be demonstrated over the whole length, including the anastomoses if they are not located in the adductor (Hunter's) canal. Pathological findings such as stenosis or aneurysms can be easily detected. Because of a large range of scatter, blood velocity or flow are no suitable parameter to determine functioning and prognosis of the bypass. A triphasic spectral waveform in the graft, the failing of aneurysms, stenosis or turbulent blood flow in the anastomosis, a high "Pulsatility Index" and a short systolic blood flow acceleration distal to the bypass, proved to be more important parameters, that can be easily determined via colour coded Doppler sonography.

Adult↗
PubMed1991

[Phantom studies using echo contrast media to improve the Doppler color sonographic imaging of the superficial femoral artery in the adductor canal].

The adductor canal was simulated using 2.6 cm muscular tissue and 2 fasciae to analyse the limits of colour-coded Doppler sonography (angiodynography) in this region. Defects in the spectral signal cause a significant underestimation of mean, peak systolic and peak diastolic (backflow) velocities and of calculated blood flow. Furthermore the pulsatility index is overestimated and the colour-coded visualisation of the arteries is almost lost. For the most part, these changes can be compensated by administration of a sonographic contrast agent (SH U 454). A minimum of 9 mg microbubbles/ml blood is required. Nevertheless, the adjustment of system controls (e.g. transducer power) becomes more difficult and an ideal setting impossible.

Contrast Media↗
PubMed1990

[Duplex sonography: accuracy, reproducibility and possibilities for error. Checking quantitative flow measurements against an in vitro model].

Using a pulsatile model of tubes, duplex-sonographic measurements of flow were compared with actual flow. The correlation coefficient between actual and duplex-sonographically obtained flow was 0.975, mean percentage deviation being -18.1% (P less than 0.0001). The obvious scatter (margin of error -69.2 to +50%) is to be explained by the simulation closely imitating a real situation: the transducer was hand-held and tubes were placed in muscle or fat tissue. Accuracy was increased by multiple measurements, especially when taking into account only the maximal value of any series of measurements. Vessel diameter was easy to measure accurately (mean error less than 0.01% [-18.7 to +9.4%]). Repeated measurements of flow velocity had only a small scatter (coefficient of variance 0.064). In muscle or fat the Doppler signal was attenuated and the error the greater the deeper the level at which measurements were made. Low flow (common in patients with obstructive vascular disease) can also cause faulty results.

Analysis of Variance↗
PubMed1990

[A realistic cardiovascular model for evaluating clinical applicability of duplex and color-Doppler equipment].

To evaluate the accuracy and reliability of colour-coded Doppler devices (CCDD) for practical use, a circulatory phantom with in vivo characteristics was developed. The experimental design consists of a piston-diaphragm metering pump with an adjustable piston volume and frequency of stroke as well as silicone tubings with different elasticity and diameters comparable with cadaver arteries. Depending on physiological conditions, blood as a circulating fluid and the surrounding soft tissues of the artery near the Doppler probe should be employed. The transducer should be manually guided. Thus, comparable to physiological frequency spectral displays, different types of wave forms (e.g. monophasic, triphasic) were initiated to analyze the reliability of CCDDs for practical use.

Blood Flow Velocity↗
PubMed1990

[Phantom studies of the value of color-coded Doppler sonography in arterial occlusive disease of the lower extremities].

A new practically orientated phantom for evaluating Doppler Duplex equipment was developed and used to determine the possibilities and limits of color coded Doppler Sonography (Angiodynography) in the diagnosis of arterial occlusive disease of the lower extremity. The problems that may occur in quantifying flow in these arteries are analyzed. The influence of superimposed slices of various soft-tissues on flow quantification, on the spectral waves and on color coded visualisation of the arteries and the possibility to compensate those changes by the use of sonographic contrast agents are discussed.

Arterial Occlusive Diseases↗
PubMed1988

Strategy for the characterization of autoantigens in autoimmune diseases. Investigation of the target antigens of antimitochondrial antibodies by radioimmunoassay, immunoblotting, monoclonal antibodies and affinity chromatography.

We present a strategy to characterize specific antigen/autoantibody systems using polyclonal sera from patients as a probe and crude antigenic preparations such as mitoplasts. Sera from patients with primary biliary cirrhosis (PBC) are characterized by at least one of two specific subtypes of antimitochondrial antibodies (AMA), anti-p48 or anti-p62. Immunoblotting of such sera with mitoplast preparations derived from human, rat and rabbit livers revealed three proteins of approximately 27, 48 and 68 kDa as target antigens. On the basis of the molecular weight of these antigens we were able to purify them by elution from preparative SDS gels. Immunization of NZB mice with the high molecular weight component (the 68 kDa antigen from human liver mitoplasts) elicited a monoclonal antibody. The 68 kDa protein was then isolated by affinity chromatography and may well represent the prime target antigen of anti-p62 antimitochondrial antibodies. This experimental approach could be applied to protein target antigens of other autoantibodies.

Animals↗
PubMed1986

Left heart function in chronic obstructive lung disease.

In patients with varying degrees of chronic obstructive pulmonary disease (COPD), simultaneous measurements of central hemodynamics and left ventricular radionuclide ventriculograms at rest and during exercise were made. In 21 of these patients, satisfactory echocardiograms could be performed. In seven of the patients, arterial blood pressure at rest was increased. Decreased compliance of the left ventricle was thought to be present in patients with COPD and additional arterial hypertension. The left ventricular ejection fraction (LVEF) at rest was in the high normal range in all patients. During exercise, no further increase was observed. This pattern of LVEF response seems to be typical in patients with COPD. Because the highest values were observed in the more severe COPD and right ventricular hypertrophy, it is unlikely that an impairment of left ventricular function is caused by COPD. In five of 27 patients, an abnormal decrease of LVEF and regional hypokinesis occurred during exercise, thus suggesting additional coronary heart disease. The fact that at least 30% of the patients with COPD suffered from arterial hypertension and 20% of the patients exhibited unexpected ischemia detected by regional hypokinesis in RNV during exercise, but not in the ECG, may be of practical relevance. Coronary angiography was not indicated because most of these patients were over 65 and the factor limiting the working capacity was ventilatory impairment and not angina pectoris, in all patients. For this reason, a diagnostic uncertainty remains with regard to additional coronary heart disease in the older patients with advanced chronic obstructive pulmonary disease.

Aged↗
PubMed1986

Pulmonary gas exchange and central hemodynamics at rest and during exercise in patients with chronic obstructive pulmonary disease.

Right-heart catheterization and ergometry with arterial and mixed venous blood gas analysis were performed in 27 patients with a wide range of chronic obstructive pulmonary diseases. The purpose of the examination was to evaluate the risk in patients for lung surgery or to detect additional heart diseases. Patients who developed exertional hypoxia (group 1) were compared with others who did not (group 2). In all patients the steady-state maximal workload was determined by ventilatory dysfunction. Both groups had normal values for mixed venous pO2 and normal increase of the circulatory parameters during exercise. The patients with exertional hypoxia differed from the others in that they showed no decrease of venous admixture and alveolar-arterial oxygen gradient. In addition, these patients had increasing pCO2 values at rest compared with exercise, indicating alveolar hypoventilation and ventilation-perfusion mismatching. Because of the good correlation of the absolute values of FEV1 (forced expiratory volume in 1 s) with pulmonary artery pressures, parameters of gas exchange and working capacity, this lung function parameter seems to have a central role in predicting the functional state of patients with chronic obstructive disease. Ergometry and blood gas analysis should be performed in addition because these values cannot be predicted with the calculated postoperative FEV1.

Aged↗