Biomedical subjects

A Schnitzler

Publications and source records attributed to A Schnitzler.

65 records · Page 4Linked to original sources

PubMed1994

The silent period after transcranial magnetic stimulation is of exclusive cortical origin: evidence from isolated cortical ischemic lesions in man.

In two representative patients suffering from focal isolated ischemic lesions of the arm-associated (patient 1) or leg-associated (patient 2) primary motor cortex excitatory responses (motor evoked potentials, MEPs) and inhibitory phenomena (silent period, SP) following transcranial magnetic motor cortex stimulation (TMS) are demonstrated. Furthermore, supramaximal peripheral nerve stimulations for testing spinal inhibitory actions were performed. Results were compared to a control group of 12 normal subjects. In patient 1, SP induced by TMS in the clinically affected left extensor carpi radialis muscle (ECR) was lacking in the presence of an only marginally reduced MEP and a normal spinal silent period in this muscle. Normal MEPs and SP durations were observed in the right ECR and in the first dorsal interosseus (FDI) and anterior tibial (TA) muscles on both sides. Similarly, in patient 2 a loss of SP induced by TMS in the clinically affected right TA was observed with normal SP durations in the left TA and both FDI muscles and normal MEP amplitudes in all muscles studied. It is concluded that both early and late phases of SP induced by TMS are of cortical origin and generated in the primary motor cortex.

Aged↗

PubMed1992

Body composition and energy metabolism in resting and exercising muslims during Ramadan fast.

Muslims abstain from food and drink from dawn to sunset during Ramadam, the ninth month of the Islamic calendar. The purpose of this study was to examine the changes that occurred in body composition and both resting and exercise metabolism during a 4 week Ramadan fast. Subjects consumed an average of 1220 kcal each day during Ramadan and lost a significant 1.92 kg body weight. The subjects also lost 2.8% fat. Fat-free mass did not change. Serum sodium, chloride, and protein increased during the first week of Ramadan and returned to the pre-fasting levels during the last week. This indicates a state of dehydratation existed during the first week of Ramadan. Consistent with this is first week 1.13 kg body weight loss with no change in percent fat. First week Ramadan tests showed a significant decrease in VO2max with a return to the pre-test levels in the last week. The lower resting afternoon VO2 suggests that during Ramadan the body's metabolism slows down during the day in order to conserve its energy stores, however, exercise economy as measured by submaximal VO2 in mk/kg/min is not affected.

Adult↗

PubMed1991

Differentiation of sympathetic neurones projecting in the hypogastric nerves in terms of their discharge patterns in cats.

1. Sympathetic neurones that project in the hypogastric nerves (HGNs) were analysed for their discharge patterns in anaesthetized cats. The activity of these neurones was recorded from their axons. Afferents from the pelvic organs (urinary bladder, colon, anal canal), and arterial baro-and chemoreceptors were stimulated. 150 postganglionic and nine preganglionic neurones were analysed. 2. The postganglionic neurones exhibited reflex patterns that were typical of visceral vasoconstrictor neurones and various types of motility-regulating neurones. Most motility-regulating neurones and all visceral vasoconstrictor neurones had ongoing activity. 3. Postganglionic motility-regulating neurones were not influenced by stimulation of arterial baro-and chemoreceptors, but showed distinctive reflexes on stimulation of afferents from pelvic organs. Three subgroups of motility-regulating neurones were identified: type 1 neurones (34% of the sample of postganglionic neurones) were excited from the urinary bladder and inhibited or not influenced from the colon. Type 2 neurones (14%) exhibited a reflex pattern reciprocal to that of the type 1 neurones. Anal motility-regulating neurones (8%) were only influenced from the anal canal. The most powerful reflexes in these types of motility-regulating neurones were elicited by mechanical stimulation of the anal mucosa. 4. Postganglionic visceral vasoconstrictor neurones (16% of the sample) were under powerful inhibitory control from the arterial baroreceptors and weakly excited by stimulation of arterial chemoreceptors. Visceral stimuli had little or no effect on most of these neurones. Some visceral vasoconstrictor neurones exhibited some overlap in their functional properties with motility-regulating neurones. 5. Twenty-eight per cent of our sample of postganglionic neurones showed no reflexes to the afferent stimuli used. About half of these neurones had on-going activity. 6. Nine preganglionic neurones with on-going activity were identified. Most of these neurones behaved like visceral vasoconstrictor or motility-regulating neurones. 7. This study shows that the majority of postganglionic neurones that project in the HGNs can be divided into the same functional types as the lumbar preganglionic neurones that project to the inferior mesenteric ganglion. The proportions of the different types of neurones are similar at pre- and postganglionic levels. Thus the centrally generated patterns of activity are most likely faithfully transmitted from the spinal cord to the target organs in the pelvic cavity in functionally separate pathways.

Anal Canal↗

PubMed1973