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U Nissen

Publications and source records attributed to U Nissen.

8 recordsLinked to original sources
PubMed1984

Obtained pregnancies by AID using frozen semen in relation to specific qualities of the semen.

The results obtained by insemination with 3,418 frozen donor ejaculates with known semen characteristics were analyzed. The concentrations of motile spermatozoa before and after thawing were significantly higher in samples from donors producing pregnancies compared to samples from donors not causing pregnancies. In ejaculates known specifically to have caused a pregnancy even higher concentrations were found. It was assumed that the concentration of motile spermatozoa after thawing was the most important parameter, and by dividing the material into fractions it could be demonstrated that a spermatozoa concentration of more than 20 million/ml is essential for reasonable results.

Female↗
PubMed1984

Evaluation of the quality variations of ejaculates from individual donors for establishing a quality control scheme.

Semen for use in artificial insemination must be of good quality. To satisfy this demand we have to be able to predict the quality of semen from individual donors. Statistical analyses of data on 3,418 ejaculates from 87 donors demonstrated that each donor's ejaculates could be characterized by a lognormal distribution of the sperm concentration, the concentration of motile spermatozoa before freezing and the concentration of motile spermatozoa after thawing. Furthermore, the ratio of the concentration of motile spermatozoa before freezing to the total sperm concentration and the fraction of motile spermatozoa surviving the freezing procedure were found to be constant for individual donors. Based on these observations a statistical quality control scheme for the selection of donors and for the continuous control of semen quality is presented.

Ejaculation↗
PubMedDate not supplied

Virtual labyrinthoscopy: visualization of the inner ear with interactive direct volume rendering.

Computed tomography (CT) is the modality of choice for detailed imaging of the bony labyrinth. Usually, information about the complex three-dimensional anatomic structures of the inner ear is presented as two-dimensional section images. Interactive direct volume rendering is a powerful method for visualization of the labyrinth. Unlike other visualization methods, direct volume rendering enables direct visualization of the bony labyrinth without explicit segmentation prior to the visualization process. Direct volume rendering was applied to visualization of the structures of the temporal bone in five patients without pathologic conditions and four patients with pathologic conditions. In all cases, clear representations of the bony labyrinth and the facial canal were provided. Because standard CT examinations combined with interactive visualization based on direct volume rendering are used, the method is fast and flexible. Therefore, this approach is applicable in routine clinical work. Problems occur in patients with effusion in the temporal bone because adjustment of imaging parameters for proper delineation of the target structures is difficult in this situation. However, direct volume rendering can produce meaningful images of high quality even in these problematic cases. The term virtual labyrinthoscopy is suggested for visualization of the labyrinth by using direct volume rendering.

Cochlea↗