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Biomedical subjects

K Mechelse

Publications and source records attributed to K Mechelse.

At least 19 recordsLinked to original sources
PubMed1992

Long-term results of transplantations to repair median, ulnar, and radial nerve lesions by a microsurgical interfascicular autogenous cable graft technique.

A comprehensive analysis of 187 patients (78 median, 86 ulnar, and 23 radial nerve lesions) treated by an interfascicular autogenous nerve grafting technique is presented. After a follow-up of at least 18 months good motor recovery was achieved in 72% of median nerve lesions, 77% of ulnar nerve lesions, and 57% of radial nerve lesions. Good functional sensory recovery was found in 36% of median, 45% of ulnar, and 48% of radial nerve lesions. It appears by multivariate analysis that the results obtained generally were better in younger patients, in patients with a shorter preoperative delay, and in cases with a shorter transplant.

Adolescent↗
PubMed1991

Sleep patterns and blood pressure variability in patients with pure autonomic failure.

Sleep patterns and 24-h blood pressure variability were studied in four female patients (age range: 56-82 years) with pure autonomic failure. All patients had severe symptomatic postural hypotension, without neurological deficits. In these patients the following patterns were observed: (i) a reversed diurnal blood pressure pattern, with the highest values observed at sleep onset; (ii) a prolonged sleep latency and increased amount of stage 3 sleep; (iii) difficulty with getting up after awakening in the morning, due to severe postural hypotension; (iv) an absence of prominent respiratory abnormalities during sleep; and (v) a dissociation between respiratory and haemodynamic findings. It is concluded that isolated deficiency of presumed postganglionic autonomic function influences sleep architecture, probably through absence of buffering of diurnal haemodynamic alterations, such as by postural hypotension and its consequences for body fluid volume regulation. This may be of relevance when sleep patterns are studied in other types of autonomic failure with postural hypotension involving central or preganglionic lesions, as in patients with the Shy-Drager syndrome or multiple system atrophy.

Aged↗
PubMed1991

Sleeping with and without norepinephrine: effects of metoclopramide and D,L-threo-3,4-dihydroxyphenylserine on sleep in dopamine beta-hydroxylase deficiency.

Sleep characteristics are presented for two female patients (aged 21 and 31 years) with central and peripheral dopamine beta-hydroxylase (DBH) deficiency. This deficiency results in the absence of norepinephrine, epinephrine, and their metabolites in plasma, urine, and cerebrospinal fluid, while concentrations of dopamine are increased. The sleep pattern of these patients was studied when they were untreated, after blockade of central dopamine receptors with metoclopramide, and after restoring norepinephrine production with D,L-threo-3,4-dihydroxyphenylserine (DOPS). When the patients were untreated sleep duration was normal, with tendencies of a decreased amount of rapid eye movement (REM) sleep, presence of alpha-delta sleep, and an increased amount of slow-wave sleep. The amount of REM sleep varied between 18 and 21% of sleep period time. Administration of metoclopramide resulted in a slight reduction of REM sleep to 16-17%, whereas wakefulness after sleep onset increased. During treatment with DOPS, an increase in the amount of REM sleep was observed in both patients to an average amount of 27%. These data indicate that in patients with DBH deficiency norepinephrine is not essential for the development of a normal sleep/wake pattern but may have a facilitatory role in the generation of REM sleep.

Adult↗
PubMed1990

A double-blind randomized multicenter dose-ranging trial of intravenous streptokinase in acute myocardial infarction.

Intravenous streptokinase administration is now a widely applied therapy for patients in the early hours of acute myocardial infarction (AMI). The dosages used do not appear to be based on comparative clinical investigations. Therefore a double-blind randomized trial was carried out to establish the optimal dose of streptokinase. A total of 189 patients who had symptoms of AMI for less than 4 hours were treated with 200,000, 750,000, 1,500,000 or 3,000,000 IU streptokinase intravenously. At coronary angiography 2.8 +/- 2.7 hours (mean +/- standard deviation) after the start of streptokinase infusion, patency of the infarct-related coronary artery was observed in 38, 75, 60 and 82% of the patients, respectively, in the 4 groups. The result of the dosage of 200,000 IU was significantly poorer than that of the other dosages (p less than 0.01). The result of a dosage of 3,000,000 IU was significantly better than that of 1,500,000 IU (p less than 0.05), but the differences with 750,000 IU were not significant. Blood transfusion was required in 4 patients (2%), distributed over the 4 groups in 0, 2, 1 and 1 of the patients. One patient had major bleeding; this patient had been treated with 750,000 IU. The 3-month mortality-rate in the whole study population was 5%. Thus, of the 4 doses of streptokinase tested, 750,000 IU is the minimal therapeutic dosage, and the arguments for 1,500,000 IU as standard therapy for comparison with other fibrinolytic drugs are poor. The best results in this study were achieved with 3,000,000 IU, but further research will be needed to establish the efficacy and safety of this new regimen.

Aged↗
PubMed1990

Sleep patterns in congenital dopamine beta-hydroxylase deficiency.

Sleep patterns of two young female patients with congenital dopamine beta-hydroxylase deficiency are described. In this orthostatic syndrome central and peripheral noradrenergic failure occurs as a result of impaired beta-hydroxylation of dopamine. Consequently, the levels of dopamine and its metabolites are elevated. The relative importance of noradrenaline deficit in the face of dopamine excess for sleep-regulatory mechanisms can be inferred from the sleep pattern of these patients. No subjective sleep complaints were reported. The sleep patterns showed a high percentage of slow-wave sleep in both patients (29% and 34% of sleep period time) and a relatively low to normal percentage of REM sleep (18% and 21%). A normal cyclic REM sleep pattern was observed. Alpha-delta sleep occurred during light sleep (15% and 8%); consequently, the amount of stage 2 sleep was reduced. These results indicate that functional insufficiency of the noradrenergic system in two patients with dopamine beta-hydroxylase deficiency is not associated with profound changes in the (REM) sleep pattern. This supports a modulatory or permissive role for noradrenaline in REM sleep mechanisms.

Adult↗
PubMed1990

Flumazenil does not improve hepatic encephalopathy associated with acute ischemic liver failure in the rabbit.

The effect of flumazenil, a benzodiazepine antagonist, on hepatic encephalopathy was studied in rabbits with acute hepatic failure induced by a two-stage liver devascularization procedure. The rabbits were randomized for treatment with 5 mg/kg of flumazenil or the placebo. The drug was administered at two easily recognizable time points in the course of the encephalopathy: first, when the righting reflex was disturbed, and second, when the animal could no longer achieve to the sitting position. The response after flumazenil did not differ from that after the placebo, as measured by clinical evaluation and automated EEG analysis. Furthermore, the progression of the encephalopathy, as measured by the survival time after the first injection, was not affected by flumazenil.

Acute Disease↗
PubMed1987

Provocation of epicondylalgia lateralis (tennis elbow) by power grip or pinching.

The etiology of epicondylalgia lateralis humeri (tennis elbow) is not fully understood. A biomechanical model is introduced for those types of epicondylalgia where damage at the origin of the wrist and finger extensor muscles is caused by overloading. It shows that grasping and pinching always cause a flexing moment at the wrist joint. To avoid flexion of the joint, there must be equilibrium of moments, which is attained by activity of the extensor muscles. Simultaneous measurements of force and electromyograms support the biomechanical model.

Adult↗
PubMed1981

Cadaver nerve allografts in dogs.

Cadaver nerve allografts were studied in major histocompatibility complex-identical beagle donor/recipient combinations. Grafts were removed 3 and 6 hours after the death of the donor, preserved at -70 degrees C and transplanted as 7 cm long grafts at a later date. Graft function and histology was evaluated 9 to 11 months after transplantation by electromyographic examination and histological studies, respectively. Cadaver nerve allografts removed 3 and 6 hours after death show exactly the same excellent regeneration as the freshly removed cryopreserved nerve allografts in major histocompatibility complex identical combinations. This information is of value for future attempts to establish nerve banks of a many as possible different major histocompatibility types. Such banks will be required to accommodate the necessary donor/recipient matching for clinical nerve allografting.

Animals↗
PubMed1978

Hereditary sensory neuropathy, a new type.

Two brothers with a new type of hereditary sensory neuropathy are described. The main clinical feature is late onset sensory ataxia without ulcerating acropathy or other autonomic abnormality. The older patient also has oculomotor dysfunction and extensor plantar responses.

Ataxia↗
PubMed1977

Role of tissue typing on preserved nerve allografts in dogs.

Histocompatibility seems to play an important role in the regeneration of nerve allografts. Compatible tissue typed nerve allografts behave more like autografts and are, therefore, more readily accepted by the host tissue without producing evident tissue rejection. The influence of histocompatibility difference becomes more marked if the graft is longer than 30-40 mm. Irradiation as a means of reducing the immune reaction of the nerve allografts does not seem to have any beneficial effect along with tissue typing. Preservation of nerve grafts at - 70°C does not have any untoward effect.

Animals↗
PubMed1977

Nerve allografts and histocompatibility in dogs.

The histocompatibility requirements for successful frozen nerve allografts were studied in 46 dogs. Major canine histocompatibility (DLA) differences appeared to be of vital importance for nerve regeneration and function, as judged by histological and electromyographic performance 7 to 9 months after grafting. Minor histocompatibility differences did not appear to lead to rejection of the frozen nerve allografts. Graft irradiation did not improve the acceptability of frozen DLA-mismatched grafts. The effect of DLA matching was much more pronounced in allografts 7 cm long than in allografts 4 cm long. The results indicate the need for a bank of frozen human histocompatible (HLA) nerve allografts, and a study of the effect of partial or complete HLA matching on their survival.

Animals↗