Biomedical subjects

Thomas Schmidt

Publications and source records attributed to Thomas Schmidt.

41 records · Page 3Linked to original sources

PubMed2002

Screening crystallisation conditions using fluorescence correlation spectroscopy.

We investigate the potential of fluorescence correlation spectroscopy (FCS) in screening for crystallisation conditions. Solutions that nucleate protein crystals must have different interactions than solutions that do not give rise to crystals. Due to these different interactions the average mean squared displacement of the individual proteins changes. By monitoring protein self-diffusion, we can distinguish crystallizing from non-crystallizing solutions. The method introduced can be applied at extremely low concentrations in femtoliter volumes as an early diagnostic for molecular association. Based on our preliminary findings FCS has the potential to become a routine screening method for crystallography.

Apoferritins↗

PubMed2002

Painting of parental chromatin in Beta hybrids by multi-colour fluorescent in situ hybridization.

Sugar beet (Beta vulgaris L.) is a relatively young crop and has a narrow gene pool. In order to introduce genetic variability into the crop, interspecific hybrids, selected from crosses with wild beets of the sections Corollinae and Procumbentes, have been generated. The introgressed B. procumbens chromatin carries resistance genes to beet cyst nematode Heterodera schachtii Schm. These lines are important for breeding of nematode-resistant sugar beet, while Corollinae species are potential donors of tolerance to biotic and abiotic stresses such as drought or saline soils. We have used in situ hybridization of genomic DNA to discriminate the parental chromosomes in these interspecific hybrids. Suppression of cross-hybridization by blocking DNA was not necessary indicating that the investigated Beta genomes contain sufficient species-specific DNA enabling the unequivocal determination of the genomic composition of the hybrids. Interspecific hybrid lines with an additional chromosome (2n = 18 + 1), chromosome fragment (2n = 18 + fragment) or translocation of B. procumbens (2n = 18) were analysed by genomic in situ hybridization (GISH) at mitosis and meiosis. Species-specific satellites and ribosomal genes used in combination with genomic DNA or in rehybridization experiments served as landmark probes for chromosome identification in hybrid genomes. The detection of a B. procumbens translocation of approx. I Mbp demonstrated the sensitivity and resolution of GISH and showed that this approach is a powerful method in genome analysis projects of the genus Beta.

Animals↗

PubMed2002

The finger in flight: real-time motor control by visually masked color stimuli.

Current theories of dual visual systems suggest that color is processed in a ventral cortical stream that eventually gives rise to visual awareness but is only indirectly involved in visuomotor control mediated by the dorsal stream. If the dorsal stream is indeed less sensitive to color than the ventral stream, color stimuli blocked from awareness by visual masking should also be blocked from guiding fast motor responses. In this study, pointing movements to one of two isoluminant color targets were preceded by consistent or inconsistent color primes. Trajectories were strongly affected by priming, with kinematics implying a continuous flow of color information into executive brain areas while the finger was already moving. Motor effects were more sensitive to color of the primes than were deliberate attempts to identify the primes in forced-choice tasks based on visual awareness. Priming was observed even when masking was complete.

Adolescent↗

PubMed1999

Symbolic dynamics of jejunal motility in the irritable bowel.

Different studies of the irritable bowel syndrome (IBS) by conventional analysis of jejunal motility report conflicting results. Therefore, our aim is to quantify the jejunal contraction activity by symbolic dynamics in order to discriminate between IBS and control subjects. Contraction amplitudes during fasting motility (phase II) are analyzed for 30 IBS and 30 healthy subjects. On the basis of a particular scale-independent discretization of the contraction amplitudes with respect to the median, IBS patients are characterized by increased block entropy as well as increased mean contraction amplitude. In a further more elementary level of analysis these differences can be reduced to specific contraction patterns within the time series, namely the fact that successive large contraction amplitudes are less ordered in IBS than in controls. These significant differences in jejunal motility may point to an altered control of the gut in IBS, although further studies on a representative number of patients have to be done for a validation of these findings. (c) 1999 American Institute of Physics.

Journal Article↗

PubMedDate not supplied

[Accidental injury of medial rectus muscle in endoscopic surgery of ethmoidal sinus: case report and survey of literature].

BACKGROUND: Ophthalmologic complications of endoscopic sinus surgery are rare, consequences may be serious. PATIENTS: Two patients are presented who suffered lesions of the internal rectus muscles during endoscopic ethmoidectomy. The clinical picture of this rare complication resembles that of a paralysis of the medial rectus muscle. THERAPY AND COURSE: In one patient the very thinned medial rectus muscle was tucked in a first surgical step. In the second step the external rectus muscle was recessed. Fusion in primary gaze was possible. In the second patient surgery was planned, he died however. CONCLUSION: Because of the anatomy the medial rectus muscle is endangered in endoscopic ethmoidectomy. Considered to the frequency of this surgery the incidence however is rare.

Aged↗