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Biomedical subjects

R Hennig

Publications and source records attributed to R Hennig.

33 records · Page 2Linked to original sources
PubMed1993

[Thoracolumbar injuries. Surgical treatment of patients with neurological damage].

This article presents the neurological outcome after surgery of a series of 54 patients with damage to the spinal cord and/or cauda equina caused by thoracolumbar injuries. The fractures, dislocations or fracture-dislocations were all reduced and stabilized by a Harrington distraction device or transpedicular fixation system (posterior segment fixator). Peroperative inspection revealed that correction and distraction alone may be inadequate to achieve intraspinal decompression. Additional anterior decompression by posterolateral approach was necessary in 31 patients (57%). In this series there was an unexpected high rate of dural rents. Tears were found in 11 patients (20%) and nerve roots (cauda equina) appeared to have herniated through the tear in eight. Significant improvement of the neurological deficits was obtained in 81%. The improvement rate was much better in patients with incomplete lesions than among those with complete lesions. We are convinced that surgery improves the neurological outcome if carried out at the proper time, after sufficient decompression of the spinal cord and nerve roots, and repair of dural rents.

Adolescent↗
PubMed1991

Proliferative capacity of mononuclear cells in the human lung.

In pulmonary sarcoidosis, a chronic granulomatous disorder with different stages of activity, the proliferative capacity of the alveolar mononuclear cells is unknown. To get a closer look at this proliferation we combined pulse labeling (by means of tritium thymidine incorporation and autoradiography) with an immunocytochemical staining assay. This assay revealed on one single slide simultaneously blue CD4+ lymphocytes, brown CD8+ lymphocytes and red macrophages. We were able to show that CD4+ as well as CD8+ lymphocytes were radiolabeled only in the active state of the disease. But macrophage proliferation occurred independently of the activity of the disease. In other words with this combination of techniques, it is possible to differentiate, on a single slide, three subsets of mononuclear cells, in combination with their proliferative behavior.

Autoradiography↗
PubMed1987

Effects of chronic stimulation on the size and speed of long-term denervated and innervated rat fast and slow skeletal muscles.

This study seeks to identify the mechanisms which motoneurones use to control the contractile force and speed of skeletal muscles. We have stimulated directly slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of adult rats intermittently at 100 Hz for 1-9 months. The muscles were either chronically denervated, denervated and reinnervated, or normally innervated. The stimulation started either immediately, or more commonly, after 1-9 months of denervation. Stimulation starting several months after denervation increased the mean maximum tetanic tension 37 times in SOL and eight times in EDL. These values represented 40 and 12% of the increases obtained by reinnervation after comparable periods of time. In denervated SOL and EDL muscles stimulated directly for more than 2 months, the mean isometric twitch contraction times were 13 and 12.7 ms, as in normal EDL muscles (13 ms). In innervated SOL muscles stimulated directly for 1-4 months, the mean twitch contraction times were 23.6 ms (normally innervated) and 19.2 ms (reinnervated), which were considerably shorter than in normal control SOL muscles (39.2 ms). Single motor unit recordings revealed that the natural (background) nerve impulse activity was essentially unaffected by the stimulation. Twitch contraction time and percentage of type II fibres in SOL muscles were related. The fastest muscles (denervated and stimulated) consisted of 100% type II fibres (with one exception), the second fastest (reinnervated and stimulated) of 70-50%, the third fastest (normally innervated and stimulated) of 45-0%, the second slowest (reinnervated) of 15-0%, and the slowest muscles (innervated controls) of 5-0% type II fibres.

Animals↗
PubMed1987

Gradation of force output in normal fast and slow muscles of the rat.

The discharge patterns of 16 motor units in extensor digitorum longus (EDL) and soleus (SOL) muscles of freely moving adult rats, described by Hennig & Lømo (1985), were further analysed with respect to their role in grading muscle force output. The units fell into three distinct classes, termed EDL-1, EDL-2 and SOL-1, probably corresponding to type FF, FR and S units. The EDL-1 units generated only single impulses or impulse trains of short duration (phasic firing) which had high frequency and usually started with a short interspike interval (initial doublet). The EDL-2 and SOL-1 units generated single impulses and impulse trains of both short and long durations (phasic and tonic firing) without initial doublets. The frequency was high in EDL-2 and low in SOL-1 units. In EDL-2 and SOL-1 units, the mean durations of the first interspike intervals in a train decreased as the number of impulses per train increased. In EDL-1 units they did not change. Both SOL and EDL muscles were simulated through the nerve at different regular frequencies and tension-frequency (T-F) curves constructed. The EDL-2 units fired naturally most often at frequencies corresponding to the steepest part of the EDL T-F curve. The EDL-1 and SOL-1 units fired naturally most often at frequencies where the T-F curves of their respective muscles began to flatten before maximum tetanic tension was reached. Stimulus trains starting with an initial doublet produced maximum rate of tension development (optimum impulse pattern). At optimum intervals the force increased from about 20 to 85% of maximum tetanic tension when the number of stimuli was increased from 1 to 7. It is concluded that the natural firing pattern of EDL-1 units and the contractile properties of EDL muscle fibres are normally matched so that the force can develop at maximum rate to maximum levels at the start of contractions. Tension output is apparently regulated primarily through varying number of impulses per train in EDL-1 units; in SOL-1 and EDL-2 units both rate and number of impulses are important.

Animals↗
PubMed1987

Section of fibular nerve affects activity pattern and contractile properties of soleus motor units in adult rats.

Transection of the common fibular (FIB) nerve caused an immediate reduction in the total amount of soleus (SOL) motor unit activity, which declined further during the following 10 days and then remained stable at less than half of normal values. In addition, there was an immediate reduction in median impulse rate from about 20.0 to 14.9 Hz followed by a return to normal values during the first 10 days. Short interval (3-4 ms) double discharges, occurring either in isolation or at the same regular intervals as single impulses, were observed 2-5 days after FIB nerve section in a few motor units. Brief, high frequency impulse bursts with interspike intervals of 12-16 ms were observed in a few units from the third day and until the end of the experiment (up to 31 days). It was not established whether the high frequency discharge pattern occurred only in a fixed population of the SOL motor units, or whether the units could switch between high and low frequency activity. Two months after FIB nerve section, the SOL muscle in the same leg contracted faster than normal (mean isometric twitch contraction time 29.6 ms, n = 4; vs. 38.7 ms, n = 8), contained a larger than normal percentage of type II fibres (13-36 vs. 0-0.2%) and weighed less than the contralateral SOL muscles (180 vs. 206 mg). SOL muscles (n = 4) in the opposite leg were comparable to normal SOL muscles except for a small reduction in mean isometric twitch contraction time (35.5 ms).

Adenosine Triphosphatases↗
PubMed1987

Late reinnervation of the rat soleus muscle is differentially suppressed by chronic stimulation and by ectopic innervation.

Soleus (SOL) and extensor digitorum longus (EDL) muscles in adult rats were kept denervated for 2 months by four repeated freezes at 2-week intervals of the sciatic nerve. Reinnervation was studied in the absence or presence of chronic muscle stimulation, starting 1 month before reinnervation began. In addition, reinnervation was studied in SOL muscles where a previously transplanted fibular (FIB) nerve had formed ectopic neuromuscular junctions outside the original endplate area. After repeated freezes only, reinnervation was complete judged by tension measurements and histochemical examinations in SOL (n = 7) and EDL (n = 8) muscles. In directly stimulated muscles reinnervation was incomplete, and the force tensions evoked from indirect stimulation was on average 87 (n = 5) and 82% (n = 5) of direct muscle stimulation in SOL and EDL muscles, respectively. Of ectopically innervated SOL muscle fibres, only 26% became reinnervated in 12 muscles. Denervation and reinnervation increased the number of muscle fibres in stimulated (n = 4) and unstimulated (n = 5) EDL muscles by 18 and 15%, respectively. In stimulated (n = 4) and unstimulated (n = 7) SOL muscles, on the other hand, the number of muscle fibres remained normal. The stronger suppression of reinnervation in ectopically reinnervated compared to chronically stimulated SOL fibres indicates that reinnervation can also be suppressed by activity independent influences from the foreign nerve.

Animals↗
PubMed1986

[Cardiac effects of Cordemcura in vitro].

Cordemcura has a dose-dependent inotropic effect in the Langendorff-perfused guinea pig heart, in the isolated spontaneously active atria of the guinea pig as well as in the isolated electrically stimulated rabbit papillary muscle. Tachyphylaxy symptoms and arrhythmogene side-effects have not been observed. The dose-dependent coronardilatory effect caused by Cordemcura as observed at the isolated heart of a guinea-pig appears intensely. The positive inotropic effect by Cordemcura on an isolated electrically stimulated papillary muscle of a rabbit is linked with a significant decrease of the relaxation time t2, whereas there is no change in the time to peak force t1. Both mean velocity of force development S1 as well as the mean velocity of relaxation S2 are increased by Cordemcura.

Aminopyridines↗
PubMedDate not supplied

Firing patterns of motor units in normal rats.

Skeletal muscles consist of motor units which may differ considerably in contractile properties and types of usage. Some units participate mainly in relatively rare, quick movements and contract rapidly and are easily fatigued (type FF); others contribute to the maintenance of posture and hence contract slowly and are fatigue-resistant (type S), while others are both fast and fatigue-resistant (type FR). Our understanding of motor control mechanisms and the dependence of contractile properties on usage would be enhanced if more quantitative information were available concerning the firing patterns of individual motor units during normal motor behaviour. Therefore, we have made continuous recordings for extended periods from single motor units in the fast extensor digitorum longus (edl) and the slow soleus (sol) muscle of freely moving adult rats. By counting the total number of discharges for each unit, and by determining the distributions of interspike intervals and the duration of the individual impulse trains, we have obtained information about firing rate, amount of use, modulation of muscle force and tonic and phasic behaviour for 16 motor units. We now report that these units fall into three classes apparently corresponding to type FF and FR in the edl muscle and type S in the soleus muscle.

Action Potentials↗
PubMedDate not supplied

The solution to hyperglucagonemia after pancreas transplantation in inbred rats.

BACKGROUND: We studied the possible role of the diseased host pancreas and site of venous graft drainage in the development of hyperglucagonemia after pancreas transplantation, to identify the crucial steps of the technique capable of eliminating hyperglucagonemia and its possible diabetogenic effect. METHODS: Therefore, we compared 4 groups of inbred rats: (1) heterotopic pancreas transplantation with either systemic (n = 9); or (2) portal (n = 5) venous drainage after prior induction of diabetes with streptozotocin; (3) orthotopic pancreaticoduodenal transplantation with portal venous drainage after prior pancreaticoduodenectomy (n = 7), and (4) sham-operation (Sham; n = 10). The postoperative period was 6 months. RESULTS: Only heterotopic transplantation with systemic venous drainage and loss of glucagon's first pass hepatic extraction, resulted in arterial hyperglucagonemia, whereas the arterial plasma insulin level was only slightly higher in comparison with the other groups. After either type of heterotopic transplantation the glucagon content of host pancreata remained unchanged, whereas the insulin content was approximately 5% of that in the pancreas of Sham rats. The insulin and glucagon contents of all grafts were similar to those of the control pancreas in Sham rats, and the insulin release was sufficient to normalize fasting plasma glucose and lipids after either type of transplantation. CONCLUSION: To remove the diseased host pancreas appears unnecessary, as the hyperglucagonemia and the concomitant slight hyperinsulinemia, capable of preventing glucagon's diabetogenic effects, are due to loss of the first pass hepatic extraction by systemic venous drainage alone. This disadvantage can be eliminated by portal venous graft drainage.

Animals↗