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Biomedical subjects

H G Ross

Publications and source records attributed to H G Ross.

30 records · Page 2Linked to original sources
PubMed1976

[Indications and results of cerclage in cervical incompetence (author's transl)].

The results of 79 cerclage operations in gestation are reported. The rate of abortion increased in cases of more severe symptomatics: firstly, without labour and bleeding: 83 p.c. successful operations; secondly, with labour: 77 p.c.; thirdly, bleeding and without labour: 70p.c.; and lastly, with labour and bleeding: 40p.c. Before treatment with tocolytic pharmaca was possible, the period of gestation time could not successfully be prolonged if labour had started. With tocolytic pharmaca 56p.c. patients of this group gave birth to a living child. The rate of premature children was 23p.c. Cerclage operations were most successful after the 25th week of gestation. When applied before the 16th week of gestation, the success rate was below 69p.c. Treatment with tocolytic pharmaca increased the indication for cerclage operations. Cerclage operations together with tocolytic treatment are indicated in cases where labour and bleeding occur in gestation.

Female↗
PubMed1976

Effect of oxotremorine on the response of antidromically activated Renshaw cells in decerebrate cats.

In intercollicular decerebrate cats, some of which were made spinal in addition, the effect of oxotremorine (intravenous injection, 10-30 mug/kg) was tested on antidromically activated Renshaw cells. Methylatropine premedication prevented the otherwise often fatal drop in blood pressure; ipsilateral dorsal roots L6-S1 and contralateral hindlimb nerves were cut to exclude segmental receptor interference. During supramaximal stimulation of ventral root L7 or the gastrocnemius nerves, an increase of activity ranging from 10-110% was observed. The drug occasionally evoked spontaneous discharges in Renshaw cells, or enhanced activity already present. Alpha motoneuron activity decreased in most cases. The interaction of oxotremorine with atropine and eserine was also investigated on Renshaw cells. Our results suggest that one of the effects of oxotremorine may be a disbalance between motor output and recurrent inhibition.

Animals↗
PubMed1975

Neurochemical changes in the cat's spinal cord due to orthodromic tetanic stimuli. I: phospholipids.

Posttetanic potentiation of monosynaptic reflexes has been used as a paradigm for neuronal plasticity. The explanation for this phenomenon is an increased responsiveness of the synaptic junctions. This would basically require chemical changes of the nervous structures involved. The ventral horn area of the spinal cord was therefore analyzed neurochemically. The determination of the phospholipids revealed an alteration of their composition. Sphingomyelin, phosphatidylcholine and phosphatidylinositide/serine behaved differently, whereas phosphatidylethanolamine and the total phospholipid content remained unchanged.

Animals↗
PubMedDate not supplied

Learning "what" and "how" in a human motor task.

We studied the development of implicit and of verbally declared knowledge for normal human subjects who learned an unfamiliar motor task in one learning session. The exploratory nature of motor learning and a special period for optimizing skill were followed in real time. Subjects understood the goal for task success, but they had to learn a motor strategy of what pattern of serial movements to make and the tactics of how much to scale their amplitudes and timing. We compared the time course for acquiring tactical skill with that for acquiring knowledge of strategy and of tactics, and their necessary cues. Implicit and declarative knowledge were distinguished from one another by correlating subjects' verbal self-reports with movement kinematics and their results. Implicit generation of the correct strategy and of the tactics developed in an exploratory manner from the beginning of the learning session. Implicit strategy learning soon gave way to conscious efforts, but tactical learning remained implicit until its first unambiguous verbal declaration (with one exception). First strategy declarations were voiced before those for tactics, during trial-and-error learning that did not require task success, and referred to reversing the direction of hand movements (one exception). In contrast, first declarations of tactics almost always required actual or imminent success, referred to when direction was to be reversed, and it was achieved near the top of a sigmoid learning curve that rose to tactical skill (with one exception). During the sigmoid rise, movement amplitudes and timing were optimized in a distinct manner, although tactics usually adapted thereafter to movements of more moderate speed that could still be successful.

Adult↗