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Biomedical subjects

P Walther

Publications and source records attributed to P Walther.

48 records · Page 3Linked to original sources
PubMed1984

Detection of protein A gold 15 nm marked surface antigens by backscattered electrons.

Colloidal gold has become an important marker in electron microscopy. Due to its scattering properties colloidal gold is easily detected in TEM. Because of the material dependent signal, preferentially backscattered electrons are used in the SEM. In the present study, we used a YAG (cerium dotted yttrium aluminum garnet) single crystal annular scintillator mounted directly below the objective pole piece. The secondary (SE) and backscattered (BSE) images of protein A gold marked cell surface proteins on two test specimens were compared: Red blood cells with a smooth and yeasts with a highly structured surface. After freeze-drying, the specimens were coated with a layer of carbon (5-10 nm) to enhance conductivity. The specimens were observed in a field emission SEM. In the SE mode a distinction between the gold particles and organic structures was hardly possible; this mode, however, gave good surface information. In the BSE mode, individual gold particles of 10 to 15 nm were easily detected. Thus the combination of the high resolution surface image and the material dependent BSE image provides an accurate localization of the surface antigens.

Acetylcholinesterase↗
PubMed1982

Aspiration biopsy of prostate.

Needle biopsy of the prostate has been widely practiced for more than twenty-five years, whereas transrectal aspiration biopsy, first described fifty years ago, has not. We describe our experience using the transrectal aspiration biopsy and correlate the results with histologic studies of the prostate obtained by conventional needle biopsy and surgical specimens. Aspiration needle biopsy of the prostate has a high degree of diagnostic accuracy, it causes minimal inconvenience and discomfort, the results are rapidly available, the ease of entering the suspected area in the prostate is more precise than with conventional needle biopsy, and sampling of prostate can be greater. The disadvantages of aspiration biopsy are that the technique, being unfamiliar to most urologists, must be learned and requires an experienced cytologist for interpretation. Cytologic evaluation by aspiration biopsy and the histologic diagnosis by conventional needle biopsy are complementary.

Biopsy, Needle↗
PubMed1979

[Comparative studies of the preparation of alpha-gliadin].

alpha-gliadin was prepared from wheat flour by two different methods. The products were compared electrophoretically and by double radial immuno-diffusion. The alpha-gliadin fraction proved to be identical in the immunological test. Only the alpha-gliadin preparation received by ion exchange chromatography is suitable for further purification by multiple gel filtrations.

Electrophoresis, Polyacrylamide Gel↗
PubMed1976

A latex bag tonometer for determining the anaesthetic blood/gas partition coefficient.

Many techniques for measurement of the tissue/gas partition coefficient are valid. Each has specific advantages and shortcomings. All the methods require suitable analytic equipment and means for controlling temperature. The disadvantages of a particular technique, the ability to cope with them and the availability of the necessary apparatus are the determining factors in choosing the best method. The latex bag tonometer has a precision and ease which compares favourably with previously described techniques for measuring anaesthetic blood/gas partition coefficients. The technique was successfully used to show the effect of in vivo haemodilution on the halothane blood/gas partition coefficient.

Anesthesiology↗
PubMedDate not supplied

Structural modifications in the stratum corneum by effect of different solubilizing agents: a study based on high-resolution low-temperature scanning electron microscopy.

The action of different solubilizing agents (chloroform-methanol mixtures and the nonionic surfactant octyl glucoside, OG) on the structural organization of the stratum corneum (SC) was investigated by means of the double-layer high-resolution low-temperature scanning electron microscopy technique. Chloroform-methanol mixtures were able to remove mainly the lipid without a significant loss of cohesion in the SC tissue. However, OG treatment caused a partial disaggregation of the corneocytes and their envelopes and, at a macroscopic level, a loss of cohesion in the whole SC tissue. As for lipid domains, after OG treatment the formation of rough structures was detected, probably associated with the disorder in the lipid lamellae. The formation of these new structures could be attributable to the interaction of the lipids with the proteins liberated from the corneocytes. Hence, a direct correlation may be established between the preservation of the structure of the corneocytes and the corneocyte envelope and the cohesion of the whole SC tissue.

Animals↗
PubMedDate not supplied

Response time of the Narkotest anesthetic gas monitor.

Response time (RT) of the Narkotest anesthetic gas monitor was measured for 7 inhalation anesthetics, using a 5 L/min fresh gas flow (FGF). Time to 63 percent of maximum response (RT63) and to 95 percent of maximum response (RT95) was directly related to rubber/gas and oil/gas partition coefficients. RT95 ranged from 7 seconds for N2O to 843 seconds for methoxyflurane. RT measured at 0.5 L/min FGF was markedly prolonged over RT at 5 L/min. When the Narkotest was placed on the expiratory limbs of circle-absorber breathing circuits, the difference between the calibrated Narkotest reading (Fn) and the mixed expired circuit concentration (Fc) was shown to depend on the rate of increase of the circuit concentration.

Anesthesia, Inhalation↗