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Biomedical subjects

T Franken

Publications and source records attributed to T Franken.

At least 19 recordsLinked to original sources
PubMed1993

Two complementary approaches to study peroxisome biogenesis in Saccharomyces cerevisiae: forward and reversed genetics.

In order to investigate the mechanisms of peroxisome biogenesis and to identify components of the peroxisomal import machinery we studied these processes in the yeast Saccharomyces cerevisiae. The forward genetic approach has led to pas-mutants (peroxisomal assembly) which fall into 12 complementation groups and allowed to identify 10 of the corresponding wild-type PAS genes (PAS 1-7, 9, 11 and 12). Recent sequence analysis data of some of these genes are beginning to provide first hints as to the possible function of their gene products. The PAS genes and their corresponding mutants are presently used to address some important questions of peroxisomal biogenesis. Reversed genetics has been started as a complementary approach to characterize especially the function of peroxisomal membrane proteins. For this purpose we describe a technique to isolate highly purified peroxisomes. This led to the identification of 21 polypeptides as constituents of this organelle. Some of them are presently sequenced.

Adenosine Triphosphatases↗
PubMed1987

[Quantifying aortic valve insufficiency by digital subtraction aortography].

The purpose of this study was to assess the contribution of digital subtraction angiography (DSA) to the quantification of aortic valve regurgitation in 21 patients undergoing heart catheterization. The digital image subtraction was used for densitometric evaluation. The regurgitation was derived from the distribution of contrast volumes during diastole in aortic and left ventricular "regions of interest". DSA-measurements were compared with results of conventional cineangiography. Results showed the following correlation between DSA measurements and cineangiographic estimates (grades I-III): regurgitation 1.7-9.8% in grade I (n = 11), 8.9-22.3% in grade II (n = 5), 31.7 and 32.5% in grade II-III (n = 2), 37-42.4% in grade III (n = 3). DSA and digital densitometry seem to be valuable methods for the quantification of regurgitation. Concerning quantitative measurements in left heart catheterization the digital subtraction aortography is superior to conventional cineangiography and will be helpful to characterize patients with aortic regurgitation more completely.

Adult↗
PubMed1986

[Videodensitometric determination of relative blood regurgitation volume in aortic valve insufficiency].

A simple video densitometric method based on the indicator distribution principle in the region of interest permits the determination of the relative amount of regurgitation between the ascending aorta and the left ventricle in cases of aortic valve insufficiency. The experimental basis and early clinical measurements are described and are compared with the more conventional methods of cine angiography and radionuclide ventriculography.

Adult↗
PubMed1986

[Differential analysis of ventricular contraction using digital subtraction angiography].

One hundred and thirty-six patients with various cardiac abnormalities that had been diagnosed by standard methods, were examined by I-V DSA; images of the left and right ventricles during a representative cardiac cycle were submitted to amplitude and phase analysis, using a Fourier transformation. Temporal differentiation of ventricular function was derived from the best available right anterior oblique projection; the amplitude of cardiac movement of abnormal areas in the myocardium were obtained from a grey scale or colour coding at a fixed point. Comparison with a control group of 35 individuals showed the following pathological findings: hypokinetic segments (33 cases) showed delay, dyskinesias (20 cases) showed complete separation of maximal phases, frequently with a double peak in the phase histogram; disturbances of cardiac rhythm (14 cases) showed atypical localisation of initiation of contraction: in Wolfe-Parkinson-White syndrome this is basal-anterior, in left bundle branch block and VVI stimulation it is apical inferior; in hypertrophic obstructive cardiomyopathy (eight cases) it is postero-basal inferior with high, narrow peaks on the phase histogram. Differential phase analysis on I-V DSA enables one to define cardiac contraction in a simple manner.

Angiography↗
PubMed1986

[Primary radiotherapy of esophageal carcinoma: a therapeutic alternative?].

The authors present the results of primary radiotherapy in 73 patients with esophagus carcinomas. A subgroup of non-circular squamous-cell carcinomas without remote and lymph node metastases (n = 19) shows a prognosis which is very favorable for this tumor. As local therapy of the esophagus carcinoma can only aim at a tolerable course of the disease until the appearance of metastases, the results achieved give occasion to doubt the priority of surgery in case of operable tumors. The question arises if primary radiotherapy wouldn't be an effective and not very risky alternative for patients presenting these favorable criteria.

Aged↗
PubMed1986

[Intravenous DSA of the heart: functional studies of the left ventricle in coronary heart disease at rest and following stress].

Intravenous digital subtraction angiography (i.v. DSA) of the heart is performed for demonstration of the morphologic and functional peculiarities of the left heart chamber, especially the ejection fraction and regional wall motion abnormalities. Employment of both geometric and video densitometric computation techniques resulted in a good correlation with direct ventriculography (r = 0.945), video densitometry, however, with a tendency to values up to 10% higher. Comparative DSA studies during rest and following exercise in 25 patients with coronary heart disease were suitable to discover pathologic strain reactions of the myocardium in 4 cases, typically depending on angiographic findings of the coronary arteries. In this way a simple method for better estimation of a deficit in coronary blood supply and its functional impact on myocardial performance may become useful.

Angina Pectoris↗
PubMed1985

[Morphometric and densitometric assessment of left ventricular function in the digital subtraction angiocardiogram].

The paper deals with the early clinical experience, using a new DSA installation with a specially programmed cardiological module. DSA provides very good contrast and special resolution and morphometric estimation of the ejection fraction and regional movement of the left ventricular myocardium derived from DSA. This is as good as the results of the left cardiogram. The significant advantage of DSA ist the ability to make a rapid and simple diagnosis. In addition, it is possible with densitometric methods to calculate ventricular volume curves and to provide phasic indications of the amplitude to contraction of the left ventricle. These investigations have so far proved valuable and provide new scope for the radiological evaluation of left ventricular function.

Absorptiometry, Photon↗
PubMed1985

[Importance of computed tomography in the diagnosis and differential diagnosis of primary adrenal tumors].

In the present study, 29 patients with primary adrenal tumours and one with an extra-adrenal paraganglioma were examined. With an accuracy of over 90%, computed tomography is the method of choice if there is clinical suspicion of a suprarenal tumour. Pathological changes greater than 8 to 10 mm can be demonstrated. Low absorption values, up to 25 HU, are found predominantly with hyperplasias and adenomas. Phaeochromocytomas, carcinomas and metastases, on the other hand, show significantly higher densities between 30 and 60 HU. CT also demonstrates neighbouring structures. Differentiation between benign and malignant processes is also possible by demonstrating tumour infiltration or metastases.

Adenoma↗
PubMed1985

[ECG-triggered DSA of the aortic arch and the supra-aortal vessels of the neck].

220 examinations were conducted in 55 patients (40 men and 15 women) to explore the question whether there are any changes in the area of the aortic arch and the supra-aortal vessels. The examinations were conducted intraindividually according to ECG-triggered and non-ECG-triggered DSA technique. The technical conditions with regard to x-ray film, volume of contrast media, and patient positions, were the same for the purpose of comparing the results with regard to the number of x-ray films, image quality, incidence of artifacts and changes in exposure to irradiation. It was found that ECG-triggered DSA yielded a greater number of diagnostically useful and qualitatively superior images with reduced irradiation exposure in a shorter time than non-ECG-triggered DSA.

Angiography↗
PubMed1984

[Value of ultrasound in screening for liver metastases and liver involvement in malignant systemic disease].

The value of sonography as a primary screening method for the diagnosis of liver metastases or liver involvement by malignant lymphoma has been investigated in 163 patients. The following results were obtained: sensitivity 92%, specificity 80%, accuracy 85%. In 109 patients CT findings were also considered. The high proportion of correct positive and low proportion of low false negative findings makes sonography the method of choice for primary screening. The figures also indicate that if sonography is negative, other diagnostic procedures are unnecessary. If sonography is abnormal, but the findings are not clear, then computed tomography is indicated.

Adult↗
PubMed1984

[Venous digital subtraction angiography of the renal arteries in hypertensive patients].

We carried out 1890 venous digital subtraction angiograms; this included 113 patients with hypertension in order to exclude renal artery stenosis. On four occasions it was used following surgery on a renal artery. Renal artery stenosis or occlusion was demonstrated in twelve patients, and other vascular diseases or anomalies were found in 24. Two abnormal renal arteries were found following renal artery surgery. The results are compared with smaller groups of patients examined by DSA, and with the results of conventional subtraction methods reported in the literature. In only eight patients (6.8%) DSA provided insufficient information and had to be supplemented by aortography. The method has proved to be a valuable and simple screening method for the investigation of hypertension.

Adult↗
PubMed1984

[A multivariate prognosis model for Hodgkin disease].

The authors describe the application of the linear discriminatory analysis as a pattern of prognosis for a group of 83 irradiated patients with Hodgkin disease. They investigated which combination of primary characteristics allows the most accurate discrimination between a group of patients with favorable prognosis and a group with unfavorable prognosis. Stage, histology, age, and clinical symptomatology proved to be valuable discriminatory factors. The accuracy of the discriminatory criterium is 75%. The results are compatible with the temporally comparable observations about prognostic factors. The method is suitable for gaining further quantitative knowledge.

Adolescent↗
PubMed1983

[A new simple procedure for immersion sonography of the scrotal contents in real time technic. II: contribution to the differential diagnosis of diseases of the scrotal contents].

In this communication the experiences obtained in 221 patients with a newly developed immersion method for scrotal sonography are analysed. The specific criteria for testicular neoplasms are derived from 22 patients with 100% true-positive diagnosis. In this context, the diagnostic difficulties in defining and identifying the benignity of an affection are discussed. The typical sonographic alterations of scrotal structures in diseases like epididymitis, epididymo-orchitis, spermatocele, varicocele and trauma are also described. An approach to calculating the testicular volume and hydrocele volume is given. The increase in diagnostic reliability makes this method suitable for pre-invasive diagnosis. The simple and non-hazardous procedure can be recommended as a routine method.

Epididymitis↗
PubMed1983

[Digital video subtraction angiography of the abdominal aorta, the pelvic and leg arteries].

The arterial system can be demonstrated after intravenous contrast injection by means of DVSA. The abdominal aorta, pelvic and lower limb arteries were examined in this way in 152 patients. Occlusions, stenoses and areas of dilatation could be recognised. In 8% of the patients the aortic bifurcation or common iliac arteries were not adequately visualised. In other respects, the results of DVSA were comparable with conventional arteriography. Because of limited image size, DVSA is particularly indicated where the vascular changes can be localised accurately by clinical means. The method is well suited for observing the results of surgery or percutaneous angioplasty. The indications for arteriography have been reduced as a result of DVSA.

Angiography↗
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

[Digital subtraction angiography (DSA) of the upper extremities].

Amongst 1500 digital subtraction angiograms, there were 93 examinations of the arteries of the upper extremities. After intravenous contrast injection, DSA provided good demonstration of the subclavian, axillary, brachial, radial and ulnar arteries. In order to demonstrate the arteries in the hand and fingers, an intra-arterial injection of 5 ml contrast into the brachial artery has proved satisfactory. DSA makes the examination easier and quicker and reduces the risk of complications. Conventional catheter angiography is now required only for a few selected problems.

Angiography↗
PubMed1983

[Clinical aspect and noninvasive diagnosis of cardiac myxomas].

The alteration of cardiac function in the presence of intracardiac tumors varies considerably according to their localization, size, and mode of insertion. Various cardiovascular diseases can be mimicked, e.g., primary valve dysfunction, cardiomyopathy, intracardiac shunts. Embolic events are frequent secondary symptoms. However, subtle noninvasive techniques such as M-mode and sector echocardiography, pulsed Doppler echocardiography, digital video subtraction angiography (DVSA), and computed tomography permit a thorough diagnosis of intracardiac tumorous masses without heart catheterization and catheter angiography. In this paper, myxomas within the left atrium (LA) and the right ventricle (RV) are described. Leading symptoms were systemic embolism and mitral stenosis (LA localization), low cardiac output and right to left shunt (RV localization). First suspicion of intracardiac tumor was raised by M-mode and sector echocardiography, whereas the diagnosis of LA myxoma was in one case missed by computed tomography and the RV myxoma was missed by right ventricular catheterization. In that case, only the four-chamber subxiphoidal sector echogram substantiated the diagnosis and explained the hemodynamic constellation of very low pulmonary pressures combined with right to left shunt. By the new technique of DVSA, all three tumors were plainly visualized. Nevertheless, echocardiography proved to be the most reliable technique of detecting intracardiac tumors.

Aged↗