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Biomedical subjects

K Moldenhauer

Publications and source records attributed to K Moldenhauer.

6 recordsLinked to original sources
PubMed2002

[Biplane angiographic volumetry of the right and left heart ventricle with optical image pairing].

Compared to single plane angiographic systems, biplane systems offer the possibility of a merged evaluation of the two x-ray projections. A computer program was developed that allows the assessment of enddiastolic and endsystolic volumes and frame-by-frame analysis of the left and right ventricle based on representing the biplane angiograms as optimal paired images. Optimal pairing means the magnifications are fitted, resulting in identical scales for objects located in the isocenter of the gantry; furthermore the images are rotated such that paired epipolar lines in both planes represent the same cross section of a centered object. The improved border tracing is proved by comparing the vertical extents from the lateral and frontal projection of the right ventricle. The standard deviation of the differences were significantly (p < 0.01) reduced as compared to the generally used unpaired evaluation.

Angiography↗
PubMed1998

Centrotemporal spikes in families with rolandic epilepsy: linkage to chromosome 15q14.

OBJECTIVE: To localize a gene predisposing to benign epilepsy of childhood with centrotemporal spikes (BECTS). BACKGROUND: BECTS, or rolandic epilepsy, is the most prevalent idiopathic epilepsy syndrome in childhood. Functional relevant defects in the alpha 4 subunit of the neuronal nicotinic acetylcholine receptor (AChR) have been demonstrated in autosomal dominant nocturnal frontal lobe epilepsy, which, like BECTS, is an idiopathic partial epilepsy. METHODS: A DNA linkage study was conducted screening all chromosomal regions known to harbor neuronal nicotinic AChR subunit genes. Twenty-two nuclear families with BECTS were analyzed. RESULTS: In an "affected-only" study, best p values and lod scores were reached between D15S165 and D15S1010 on chromosome 15q14. In multipoint nonparametric linkage analysis a nominal p value of 0.000494 was calculated by GENEHUNTER. Best parametric results were obtained under an autosomal recessive model with heterogeneity (multipoint lod score 3.56 with 70% of families linked to the locus). These markers are localized in direct vicinity to the alpha 7 subunit gene of the AChR. CONCLUSIONS: We found evidence for linkage of BECTS to a region on chromosome 15q14. Either the alpha 7 AChR subunit gene or a closely linked gene are implicated in pedigrees with BECTS. The disorder is genetically heterogeneous. Surprisingly, the same chromosomal area has been reported to be linked to the phenotype in families with an auditory neurophysiologic deficit as well as in families with juvenile myoclonic epilepsy, another idiopathic but generalized epilepsy syndrome.

Adolescent↗
PubMed1982

Quantitative analysis of structure and function of the cardiovascular system by roentgen-video-computer techniques.

A survey of the evolution of roentgen-video-computer techniques is given which was initiated by the development of videodensitometry by Wood and his associates. Following fundamental studies of the usefulness and limitations of x-ray equipment for quantitative measurements and the applicability of the Lambert-Beers law to x-ray absorption, videodensitometry has been used experimentally and clinically for various circulatory studies and has proved to be particularly valuable for the quantitation of aortic, pulmonic, and mitral valvular regurgitation. The second offspring of these techniques, so-called videometry, uses dimensional measurements from single and biplane angiocardiograms for the assessment of size, shape, and contraction pattern of the heart chambers. Volumes of the right and left ventricles can be determined clinically with a standard error of estimate below 10%. On the basis of these studies, normal values have been derived for all age groups, and they depict geometric changes of the growing heart. Cardiac index and ejection fractions proved to be age-independent biologic constants. Finally, methods for complete digital processing of video-image sequences in an off-line and real-time mode are described which allow digital image storage and documentation, dynamic background subtraction for contrast enhancement, and intravenous angiocardiography, in addition to functional imaging by parameter extraction from a matrix of pixel densitograms. Wall thickness and motion determinations, regional flow distribution measurements, and various image-composition techniques are also feasible.

Absorptiometry, Photon↗