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Biomedical subjects

H Metzger

Publications and source records attributed to H Metzger.

At least 271 records · Page 15Linked to original sources
PubMed1966

Evolution of immunoglobulin polypeptide chains: carboxy-terminal of an IgM heavy chain.

The dipeptide sequence at the carboxy-terminal of a heavy (micro) chain from a human macroglobulin ( IgM) is tyrosylcysteine, although the reverse sequence, cysteinyltyrosine, has not been rigorously excluded. The presence of cysteine at the carboxy-terminal was predicted from a recognition of the chemical homologies among the polypeptide chains of immunoglobulins, and their probable evolutionary origin.

Amino Acid Sequence↗
PubMedDate not supplied

Staining of PO2 measuring points demonstrated for the rat brain cortex.

A combined physiological and histological technique was developed in order to determine the exact position of the tip of a microelectrode used for PO2 measurements within the rat brain cortex. Using this method it was possible both to identify the tissue layer where PO2 measurements had been performed as well as obtain information about the blood capillaries within the surrounding tissue. After the PO2 had been measured small quantities of dye (Alcian Blue 8 GX) were injected through a micropipette attached to the PO2 microelectrode (tip-tip distance 2-5 micron). Subsequently the tissue was fixed by perfusion, 5 micron sections were cut and stained with Cresylviolet. The points where measurements had been made could be seen under a light microscope as green coloured spots of about 100 micron in diameter. The capillary pattern could be demonstrated by silver nitrate perfusion. Information about the capillaries, such as length, distance and the gas exchange surface were obtained via computer analysis of a television image. This method was used to analyse the O2 supply of the optical cortex of the rat. Correlation of the local PO2 distribution with the capillary data revealed differences between the archi- and the neocortex of the rat brain.

Animals↗
PubMedDate not supplied

The influence of electrical stimulation on cortex PO2 level in the rat brain.

Local oxygen consumption of the rat brain cortex was artificially increased through local electrical stimulation of a small tissue sphere 5 mm in diameter. Measurements of the local PO2 distribution within the stimulated tissue as well as the induced field potential were performed with the same gold microelectrode. During stimulation the oxygen consumption increased significantly giving rise to local hypoxia and after 1-3 minutes to local anoxia depending upon the stimulus strength and duration. If however pronounced respiratory hypercapnia was applied the increased demand for oxygen was met by an increase in cerebral blood flow resulting in an almost constant PO2 level. According to these results it is concluded that the anoxic tissue sphere was not large enough to cause changes in the local blood flow. On the other hand recovery from local hypoxia and anoxia as well as reoxygenation of the stimulated tissue were delayed if a general hypoxia already existed.

Animals↗