Relation between the site of origin of ventricular premature complexes and the presence and severity of coronary artery disease

Dopamine-beta-hydroxylase (DBH) and norepinephrine (NE) have been determined in over 350 plasma samples from 174 subjects while resting supine (basal sample), standing, or exercising. Although increments in both NE and DBH were found with postural change, the further increase in plasma levels of NE during exertion was not attended by any change in levels of DBH. There was no significant correlation between basal levels of DBH and NE nor was there any correlation in their increments after standing or exercising. DBH activity in plasma of subjects with moderate essential hypertension was not different from that of normotensive subjects. It is concluded that plasma DBH is a poor index of acute sympathetic neuronal activity.     

Characteristics of the cortical input of the hippocampus. Functional differences in the lateral and medial entorhinal cortex

Extracellular investigation in unanaesthetized rabbits revealed low reactivity of the lateral entorhinal cortex neurones (lEC, field 28b) to visual and auditory stimuli. Only 25% of cells responded to them by diffuse long-latency reactions, while in medial EC (mEC, field 28a) 70% of neurones responded to these stimuli with short-latency patterned reactions. The neurones of lEC were selectively responsive to different somatosensory stimuli. Among reactions short-latency on-effects were observed. In some cells application of these stimuli switched on rhythmic bursts of spikes (frequency about 3-4 Hz) or regular activity of pacemaker type. The lEC neurones responded by short-latency driving to electrical stimulation of prefrontal cortex, while mEC neurones were responsive to stimulation of posterior non-primary neocortical areas. The data are discussed in the light of recent morphological findings on cortico-cortical connections of EC.     

Nuclease activity of the cytoplasmic ribosomes of hepatocytes and several experimental hepatomas

The nuclease activities of proteins, constituents of cytoplasmic ribosomes obtained from normal liver rats (Wistar) and C3HA mice as well as from hepatomas (both solid and ascites forms) transplanted into the above animals, were studied. RNA in membrane-bound ribosomes of normal rat liver incubated at 37 degrees C undergoes endogeneous hydrolysis resulting in formation, apart from acid-soluble products, of 6S, 8S and 11S fragments comprising 15 to 20% of the original amount of RNA. In contrast, in hepatoma membrane-bound ribosomes RNA treated likewisely remains intact. The proteins responsible for the RNase activity isolated from ribosomes were subsequently fractionated using ammonium sulfate and chromatography on DEAE-Sephadex columns and their properties were studied. The RNase activity completely disappeared from the membrane-bound ribosomes of Zajdela, 27 rat hepatomas and Guelstein hepatoma 22A, but not from the slow growing Guelstein hepatoma 48.