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R Lehmann

Publications and source records attributed to R Lehmann.

342 records · Page 19Linked to original sources
PubMedDate not supplied

Advantages in the analysis of UDP-sugars by capillary electrophoresis-comparison of the conventional HPLC method with two new capillary electrophoretic micro-procedures.

Two different capillary electrophoretic separation modes for the analysis of UDP-sugars have been tested. In comparison to the traditionally used HPLC method the micellar electrokinetic capillary chromatography (MECC) as well as the capillary zone electrophoresis (CZE) results in an improvement of the separation profile and the speed of the analysis.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Nonparenchymal cells cultivated from explants of fibrotic liver resemble endothelial and smooth muscle cells from blood vessel walls.

Tissue specimens from human fibrotic liver obtained by needle biopsy were cultured. Two cell types emerged from the tissue explants. From their morphology and biosynthetic products they resembled smooth muscle cells and endothelial cells from blood vessel walls. In the "endothelial" cells, factor VIII-associated protein was demonstrated by indirect immunofluorescence. Synthesis of collagen types I and III, basement membrane collagen types IV and V, and fibronectin by both cell types was observed by immunofluorescence microscopy. Homogeneous cultures of "smooth muscle cells" were observed in subcultures. After incubation with [14C]glycine, collagen was isolated and characterized by CM cellulose chromatography, and consisted mainly of types I and III. These data suggest involvement of mesenchymal cells in hepatic fibrosis; they presumably originate from blood vessel or sinusoidal walls.

Aged↗
PubMedDate not supplied

Disseminated mucormycosis caused by Absidia corymbifera leading to cerebral vasculitis.

An 18-year-old woman was admitted to hospital because of subcutaneous hematoma and fever of unknown origin. Acute myeloid leukemia was diagnosed and empirical antimicrobial treatment and induction chemotherapy were started. After initial defervescence, fever relapsed 2 days after the onset of neutropenia. The CT scan of the lung was consistent with an invasive fungal infection. Treatment with amphotericin B was started and antimicrobial treatment was continued with liposomal amphotericin B because of an increase in creatinine later. The fever persisted and the patient suddenly developed progressive neurological symptoms. CT scan of the head suggested cerebral infarction and angiography of the extra- and intracranial arteries showed signs of vasculitis. Six days after the onset of neurological symptoms cerebral death was diagnosed. Autopsy revealed non-septate, irregularly branched hyphae in various histologic sections including brain. Absidia corymbifera could be isolated from lung tissue confirming the diagnosis of disseminated mucormycosis. In this case, angiographic findings suggested severe cerebral vasculitis which was in fact caused by thromboembolic dissemination of fungal hyphae. This case underlines the fact that cerebral symptoms in febrile neutropenic patients are highly indicative for fungal infections of the brain.

Absidia↗
PubMedDate not supplied

Age-related reduction in visually evoked cerebral blood flow responses.

The influence of aging on photoreactive flow changes in the posterior cerebral artery (PCA) was investigated in 38 healthy volunteers aged 20-81 years. Mean blood flow velocity (MBFV) was measured at rest and during 10-Hz photic stimulation by transcranial Doppler sonography. The amplitude of the evoked flow response significantly decreased with age (r = -0.39; P < 0.001). In a group of elderly subjects (60-81 years), the evoked blood flow velocity increase was 10.8 +/- 2.7%, which is less than in young subjects aged 20-39 years (14.7 +/- 4.3%; P = 0.001). We conclude that normal aging affects photoreactive flow changes in the occipital lobe. This may limit the application of functional imaging studies based on measurements of blood flow changes in the elderly.

Adult↗
PubMedDate not supplied

Venous Doppler ultrasound assessment of the parasellar region.

The purpose of this report is to present normal values for venous blood flow velocities from the parasellar region using transcranial Doppler ultrasound (2-MHz transducer) with both transtemporal and transorbital approaches and to examine the nature of previously reported low-pulsatility signals with velocities in the arterial range from this area. Forty-three subjects ranging in age from 18 to 56 years (mean +/- SD, 31.9 +/- 10.1 years) were examined. In all subjects, a venous signal directed away from the probe with the source lateral to the internal carotid artery siphon was detected on at least one side. A total of 72 parasellar venous signals were insonated. Signals were considered to belong to the main inflow and outflow vessels of the cavernous sinus. The mean blood flow velocity ranged from 6 to 81 cm/s (mean +/- SD, 27.3 +/- 17.4 cm/s). Typical transients in the Valsalva test confirmed the venous character of the signals. No significant gender, side-to-side or age dependency was observed. A separate analysis was done for venous high-velocity signals defined by a mean blood flow velocity greater than 30 cm/s. They were detected in 21 out of 43 subjects (48.9%) via a transtemporal approach and in 6 of them (14%) via the transorbital route, too. Again, no significant gender, side-to-side or age dependency was noted. In summary, we found a greater variability of venous blood flow velocities in the parasellar region compared to other basal cerebral veins, e.g. the basal vein of Rosenthal. The previously reported low-pulsatility signals with velocities in the arterial range proved to be of venous origin.

Adolescent↗
PubMedDate not supplied

Application of capillary electrophoresis in clinical chemistry--developments from preliminary trials to routine analysis.

Since instruments performing capillary electrophoresis (CE) became commercially available in the late 1980s, information on this relatively new analytical technique has been increasing almost exponentially. At the beginning of the last decade, fundamental discoveries in the field were made mainly in the laboratories of analytical chemists; but now, this separation science is giving increasing impact to the laboratories of clinical chemists. This paper briefly reviews the history, instrumentation, different modes and theory of CE, and the prominent fields of its applications in clinical chemistry.

Amino Acids↗