PubMed Health⌕ Search

Biomedical subjects

H M Meinck

Publications and source records attributed to H M Meinck.

At least 91 records · Page 5Linked to original sources
PubMed1982

The forearm ischaemic work test--hazardous to McArdle patients?

A 57-year-old patient suffering from late-onset McArdle's disease developed myoglobinaemia, massive myoglobinuria and marked serum creatine kinase elevation subsequent to a routinely performed forearm ischaemic work test. Twenty hours after the test, enhancement of 99mTc methylene-diphosphonate activity was demonstrated exclusively in the tested forearm. It is concluded that the forearm ischaemic work test is potentially hazardous to McArdle patients, as it might induce myoglobinuria sufficient to result in acute myoglobinuric renal failure.

Exercise Test↗
PubMed1981

Increased ammonia production during forearm ischemic work test in McArdle's disease.

A patient with typical features of late onset McArdle's disease is described. During forearm ischemic work test the patient exhibited an exaggerated increase in ammonia release, largely exceeding normal values. It is suggested, that this is due to an activation of the myokinase/myoadenylate deaminase pathway. Besides lack of lactate release increased ammonia release during ischemia may be a typical feature of McArdle's disease.

Ammonia↗
PubMed1981

[Myoglobinuric renal failure in hyperosmolar diabetic coma (author's transl)].

Acute rhabdomyolysis with myoglobinuric renal failure occurred in a 66-year-old woman who was in hyperosmolar non-ketotic diabetic coma. No previous description of such a case has been found. The clinical picture was characterized by the typical findings of hyperosmolar coma, in addition to excessive serum creatine kinase and myoglobin levels and massive myoglobinuria with acute renal failure. The rhabdomyolysis became fully manifest only under insulin treatment, possibly the result of insulin-induced hypophosphataemia, which seems to be of importance in the causation of the rhabdomyolysis.

Acute Kidney Injury↗
PubMed1981

Reflexes evoked in leg muscles from arm afferents: a propriospinal pathway in man?

Long-loop reflexes from arm afferents onto motoneurones of leg muscles were investigated in 57 healthy subjects by means of H reflex testing and tonic EMG testing. In various tonically activated leg muscles, brachial nerve stimulation exerted stereotyped reflex responses which regularly consisted of an initial depression phase (mean onset latency: 60 ms) and a subsequent facilitatory phase (mean onset latency: 80 ms). H reflex studies, in contrast, only revealed the later facilitation. Except for this difference, both methods led to similar results: fibres responsible for the response were identified as low-threshold skin afferents with a conduction velocity of about 40 m/s. Noxious stimulation reinforced the effects of innocuous stimulation. The receptive field for the reflex response was not restricted to the ipsi- and contralateral arm regions but included the face and the rostral part of the trunk above the buttock. Percutaneous stimulation of dorsal roots C4 and T9, respectively, resulted in a shortening of the onset latencies of both depression and facilitation, with T9 stimulation. It is therefore suggested that the reflexes described are mediated via a directly descending, long spinal pathway.

Adolescent↗
PubMed1981

Some principles of flexor reflex generation in human leg muscles.

Flexor reflexes, evoked by stimulation of the tibial and deep peroneal nerves at the ankle level, were investigated in several ipsi and contralateral human leg muscles. On both sides, the reflex consist of a stereotyped oscillating sequence of inhibition and facilitation, exhibiting specifity to the stimulated site only in the initial ipsilateral phases. The responsible afferents were identified as belonging to a group of non-nociceptice skin afferents with a maximum conduction velocity of about 40-54 m/sec. Interdependence was observed between both latencies and amplitudes of the individual phases of the reflex sequences in synergistic and antagonistic pairs of muscles. It is concluded that the function of such a conjoint reflex generation in different muscles is to ensure an organized and adequate withdrawal.

Electric Stimulation↗
PubMed1980

Neurophysiological effects of etomidate, a new short-acting hypnotic.

The neurophysiological effects of 0.3 mg/kg etomidate injected i.v. within 30 sec were investigated in 22 healthy volunteers, 7 of whom were premedicated with Thalamonal and fentanyl. About 30 sec after injection, a short period of delta activity (deep sleep) occurred in the EEG, successively normalizing within the next 6-8 min. EEG arousal reactions to various stimuli were blocked for several minutes. In the premedicated group neither motor hyperactivity nor monosynaptic reflex alterations were observed. In contrast, 9 out of 5 non-premedicated subjects exhibited various kinds of motor hyperactivity, consisting most often of asynchronous clonic bursts of activity in the EMG. Clonus was not related to EEG events, and could persist beyond behavioural and EEG recovery. In 12 subjects, the monosynaptic H reflex was enhanced up to 6 X of control. The plantar reflex was reinforced to a generalized withdrawal reaction, sometimes a positive Babinski sign was observed. It is assumed that clonus is generated in spinal circuits, whereas supraspinal structures may contribute to the more complex forms of motor hyperactivity.

Adult↗
PubMed1980

Response patterns of human lumbo-sacral motoneurone pools to distant somatosensory stimuli.

The response of human lumbo-sacral motoneurones to electrical stimuli applied to the trunk, the face and the arms was evaluated by means of H reflex testing in extensors and averaging the rectified tonic EMG recorded from extensors as well as flexors. In extensor and flexor muscles, the reflex pattern consisted of a non-reciprocal inhibition-facilitation, occurring with latencies of about 60 and 80 msec, respectively. With reflex testing, only facilitation was observed in extensors, beginning after a conditioning-test interval of about 40 msec and peaking at about 80 msec. This discrepancy was interpreted to indicate excitation supraliminal in a facilitatory and subliminal in an inhibitory pathway, the latter requiring an additional input to impinge on motoneurones. Afferents responsible for the described reflex actions were identified as belonging mainly to low-threshold skin nerve fibres, conducting with a maximum velocity of about 45--50 m/sec. However, medium threshold skin afferents as well as muscle and joint afferents may also play a role. Stimulation of C5 and T10 skin areas close to the neuraxis revealed similar effects, the latencies being shorter or equal with T10 compared with C5 stimulation. The possibility of a directly descending propriospinal pathway is discussed, mediating the inhibitory as well as the excitatory reflex actions described.

Adolescent↗
PubMed1976

Occurrence of the H reflex and the F wave in the rat.

In adult rats the tibial nerve was stimulated at the ankle and the evoked EMG of the foot muscles was recorded. A low threshold reflex discharge was elicited that was subsequently depressed by stronger stimuli eliciting the direct (M) wave. This discharge was abolished by cutting the dorsal roots (except for 1-3% postulated to be due to recurrent discharge). It had a central latency of about 2 msec, was depressed by stimulation rates above 0.3/sec and showed posttetanic depression, all of which are also properties of the rats's monosynaptic reflex. By analogy it is assumed to be an H reflex.

Animals↗
PubMed1976

[Descending long-loop reflexes in the human spinal cord I. Facilitation of the triceps surae H reflex following stimulation of forelimb afferences (author's transl)].

The H reflex in the triceps surae muscle was elicited by just supraliminal stimulation of the tibial nerve. It was conditioned by paired impulses to the brachial plexus or the forelimb nerves and in some cases to other sites of the body. With a conditioning test interval of 32-47 msec a facilitation occurred which reached its maximum at about 80 msec and lasted for about 400 msec. The facilitation evoked by ipsilateral conditioning had a shorter latency than that from contralateral (ipsilateral: 32-42 msec, contralateral; 37-47 msec). The facilitation at the optimum interval (about 80 msec) ranged between 1;5 and 11.3 times of the control values. Ipsilateral conditioning was slightly more effective than the contralateral one (Fig. 1, 2). Stimulation of different forelimb nerves at an interval of 80 msec showed only insignificant differences in the amount of facilitation but was more effective than skin stimulation in the most cases (Fig. 3). Varying the intensity of the conditioning stimulus showed that facilitation occurred with just perceptable stimuli but it became more pronounced as soon as pain threshold (2-3 time of perception threshold) was exceeded (Fig. 3). This suggests that facilitation was mainly due to activation of nociceptor afferents. From the onset of facilitation and the conduction velocities of the respective forelimb and hindlimb afferents (cf. 6) a central reflex lantency of about 43 msec was calculated. To get further insight into the central connections of the reflex loop the H reflex was conditioned by paravertebral stimulation at C5 and L1 level. Both stimuli caused a distinct facilitation. However, the latency of the onset was 10-15 msec shorter with lumbar stimulation than with cervical stimulation. This and the similar time course of facilitation seen in animal experiments (12) suggest that an early part of facilitation is mediated via a descending propriospinal pathway. The major part, however, is supposed to be mediated via supraspinal pathways and seems to be related to a startle response.

Animals↗