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Biomedical subjects

K Reiners

Publications and source records attributed to K Reiners.

At least 73 records · Page 4Linked to original sources
PubMed1992

Neurological risk profile in organic erectile impotence.

Thirty men who presented with erectile impotence to the urological department underwent a thorough urological, angiological, and neurological examination with complementary neurophysiological tests of somatosensory and sympathetic and parasympathetic function. Most had vascular and neurological abnormalities. Clinical findings and electrophysiological tests for autonomic dysfunction had the highest yield of abnormal results. Nerve conduction studies and pudendal nerve somatosensory evoked potentials were far less informative. The lack of correlation between vascular and general neurological abnormalities emphasises that patients must be screened for both vascular and neurological dysfunction to prevent unrewarding vascular operation in impotent men.

Adult↗
PubMed1991

Serum interleukin-2 concentrations in Guillain-Barré syndrome and chronic idiopathic demyelinating polyradiculoneuropathy: comparison with other neurological diseases of presumed immunopathogenesis.

Serum concentrations of the cytokine interleukin-2 (IL-2) were quantitated by enzyme-linked immunosorbent assay in 42 patients with Guillain-Barré syndrome, 15 patients with chronic idiopathic demyelinating polyradiculoneuropathy, 37 patients with other neuropathies, 54 patients with other noninflammatory, nondemyelinating neurological disorders, and 26 healthy control subjects. We found markedly increased serum levels of IL-2 in patients with Guillain-Barré syndrome and to a much lesser extent, in patients with chronic idiopathic demyelinating polyradiculoneuropathy. Increased serum concentrations of IL-2 in patients with Guillain-Barré syndrome returned to normal in parallel with recovery from the disease. These findings suggest ongoing T-cell proliferation in patients with Guillain-Barré syndrome and some patients with chronic idiopathic demyelinating polyradiculoneuropathy. IL-2 levels were also raised in patients with active multiple sclerosis, myasthenia gravis, and herpes simplex encephalitis, and some patients with polymyositis, invoking T cells in the pathogenesis of these diseases.

Autoimmune Diseases↗
PubMed1991

Does tremor pace repetitive voluntary motor behavior in Parkinson's disease?

In patients with Parkinson's disease and in normal subjects, the influence of tremor on repetitive voluntary movement was investigated in the index finger by comparing frequency of isometric force tremor with frequency of voluntary alternating isometric contractions. Tremor frequency, measured over the range from 0 to 70% maximum voluntary force, usually increased with force. The tremor frequency band was lower and more often overlapped with the upper voluntary frequency range in patients than in normal subjects. Normal subjects could accurately produce voluntary contractions at all cue frequencies from 1 to 5 Hz. Patients could produce auditory-paced frequencies of 1 and 2 Hz, but at higher cue frequencies, their voluntary contractions were often faster or slower than the cue. The faster or "hastened" voluntary frequencies were within the tremor frequency band, whereas the slowed voluntary frequencies were below it. Maximal voluntary frequency was often greater than the lowest but always less than the highest tremor frequency. It is concluded that parkinsonian tremor may pace voluntary repetitive movements to go faster than intended with the highest tremor frequency being an upper limit for voluntary frequency. Similar mechanisms may underlie the hastened repetitive vocal responses that were also observed in the parkinsonian patients.

Adult↗
PubMed1991

Ultrastructural abnormalities of mitochondria and deficiency of myocardial cytochrome c oxidase in a patient with ventricular tachycardia.

A 30-year-old woman presented with life-threatening ventricular tachycardia without overt heart disease. Ultrastructural investigation of endomyocardial biopsy disclosed abnormally structured and often enlarged mitochondria. Morphometry revealed the ratio of volume density of mitochondria to myofibrils to be markedly increased to 0.667 as compared with five controls (mean: 0.46; range: 0.445-0.479). Investigation of mitochondrial respiratory chain enzymes revealed a 90% reduction in activity of cytochrome c oxidase. Our data suggest that mitochondrial cardiomyopathy may induce malignant ventricular arrhythmias.

Adult↗
PubMed1991

Acute posterior multifocal placoid pigment epitheliopathy with cerebral involvement.

In a patient with angiographically proven cerebral vasculitis five months after acute posterior multifocal placoid pigment epitheliopathy (APMPPE) neurological symptoms promptly responded to steroid treatment. Cerebrospinal fluid (CSF) showed a lymphocytic pleocytosis. Magnetic resonance imaging (MRI) revealed multifocal white matter lesions in the hemispheres and the brain stem suggesting a diffuse subcortical vasculitis.

Cerebral Arterial Diseases↗
PubMed1991

Encephalo-myelo-radiculo-ganglionitis presenting as pandysautonomia.

A 68-year-old man developed pandysautonomia with severe orthostatic dysfunction, fixed heart rate, low serum levels of norepinephrine and epinephrine, absent sympathetic skin responses, and pupillary abnormalities. CSF protein was 92 mg/dl. In spite of a good recovery following corticosteroid administration, a relapse occurred, with accompanying sensory symptoms confined to both arms. Fatal sudden cardiac arrest occurred after 4 months. Autopsy revealed numerous lymphocytic infiltrates, predominantly in autonomic and sensory ganglia and, to a lesser extent, in the nerve roots, spinal cord, and brainstem without evidence for an underlying tumor. This case provides histopathologic evidence for an inflammatory etiology of panautonomic neuropathy in some patients.

Aged↗
PubMed1990

Neurophysiology of fastest voluntary muscle contraction in hereditary neuropathy.

In patients with hereditary motor and sensory neuropathy types I (demyelinative) and II (neuronal) and in normal subjects, isometric force and electromyographic activity of the first dorsal interosseous muscle were recorded during fastest voluntary contractions and during twitches evoked by nerve stimulation. The maximum voluntary force of the first dorsal interosseous muscle was also measured. In patients, fastest voluntary contraction time (i.e., time from onset of contraction to peak force) was prolonged and inversely proportional to maximum voluntary force. Maximum rate of rise of tension (i.e., slope of rise in force) was reduced and directly proportional to maximum voluntary force. In patients with hereditary motor and sensory neuropathy type I, contraction time was longer and the maximum rate of rise of tension was lower than in those with hereditary motor and sensory neuropathy type II. In patients and normal subjects, voluntary contraction time was closely correlated with the duration of electromyographic bursts. In patients, the twitch contraction time was prolonged and inversely proportional to maximum voluntary force. Twitch contraction amplitude was diminished and directly proportional to maximum voluntary force. Neither twitch contraction time nor amplitude were dependent on the type of hereditary motor and sensory neuropathy. Twitch contraction time evoked by proximal nerve stimulation was minimally longer than that evoked by distal stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

T cell activation in Guillain-Barré syndrome and in MS: elevated serum levels of soluble IL-2 receptors.

Guillain-Barré syndrome (GBS), chronic idiopathic demyelinating polyradiculoneuropathy (CIDP), and multiple sclerosis (MS) are disorders with presumed immunopathogenesis. To obtain evidence for T cell activation, we determined serum concentrations of soluble interleukin-2 receptors (sIL-2 R) in 50 patients with GBS, 24 with CIDP, and 54 with MS. Both in GBS and clinically active MS sIL-2 R levels were markedly increased compared with those in patients with other neurologic diseases. Four of 24 CIDP patients had abnormally increased sIL-2 R concentrations. sIL-2 R concentrations decreased with clinical improvement in serial samples taken from GBS patients, but were not otherwise correlated with disease severity. These data establish that T cells are activated in GBS and some patients with CIDP, and corroborate earlier evidence that activated T cells are circulating in the blood of MS patients.

Chronic Disease↗
PubMed1989

The blood-nerve barrier in Wallerian degeneration: a sequential long-term study.

The blood-nerve barrier (BNB) for serum proteins was studied after a crush lesion of the murine sciatic nerve or after transsection with persistent Wallerian degeneration. Using single intraperitoneal injections of biotinylated human albumin, transferrin, IgG, and complement components as tracers, the integrity of the BNB during degeneration and regeneration was determined over time. In Wallerian degeneration induced by crush the BNB became increasingly leaky, with a maximum in the distal stump 8 days after crush (i.e., during early regeneration). When regeneration potentials could first be elicited from the small foot muscles and when thinly myelinated nerve fibers were present, the BNB gradually regained its barrier function and was nearly intact on day 30 after crush. After transsection breakdown of the BNB persisted beyond 30 days. The BNB leakage may foster repair by allowing exchange of trophic factors of large molecular size during nerve regeneration.

Animals↗
PubMed1989

Altered mechanisms of muscular force generation in lower motor neuron disease.

Recruitment and firing rate modulation (FRM) of single motor units (MUs) were evaluated in the first dorsal interosseus muscle in patients with chronic lower motor neuron disorders of primarily neuroaxonal or demyelinating pathology. Residual muscle function was estimated by maximal voluntary force, twitch tension, and compound muscle action potential. The recruitment range of MUs was expanded toward higher relative force levels in all patients. Changes in firing rates per unit force increment were larger in patients with more pronounced muscle atrophy. When this effect was accounted for by calculating FRM for increments of 10% of residual maximal force, patients with subnormal motor nerve conduction velocities showed selective impairment of rate modulation. This was not due to intermittent conduction failure. We conclude that the two force-generating mechanisms, recruitment and FRM, show unspecific compensatory changes related to the loss of MUs and also alterations that are specifically related to the neuroaxonal or demyelinating nature of the neuropathy.

Action Potentials↗
PubMed1989

Good recovery after sublethal ethylene glycol intoxication: serial EEG and CT findings.

The case of a young man with sublethal ethylene glycol poisoning is reported. Complete recovery occurred after 12 days of deep coma and a prolonged flaccid tetraplegia. The lesions of gross degree in the CNS, demonstrated by serial CT, resolved and electrophysiological testing as well as neuromuscular signs improved. The recovery, clinically and radiographically, over 35 days was dramatic. Ethylene glycol intoxication should always be considered in the differential diagnosis of acute severe encephalopathy because complete recovery is possible with correct therapy.

Adult↗
PubMed1987

Stability of frequency during long-term recordings of hand tremor.

During recording of physiological postural hand tremor over a period of 60 min tremor peak frequency (PF) did not change in 14 normal subjects as long as the mechanical conditions were not changed. In contrast, tremor amplitude and synchronization of the corresponding EMG varied considerably. Any alteration in hand mechanics such as changing hand position or adding masses led to changes of PF according to the alteration in mechanical resonant properties. The results show that PF of physiological postural hand tremor is mainly determined by mechanical factors. There is no evidence for a systematic decrease of PF (Stiles et al. 1976) or for the emergence of a formerly described (Lippold 1981) 4-6 Hz tremor component with prolonged maintenance of posture. In the pathological tremor forms of Parkinson's disease or essential tremor PF also remained unchanged during prolonged maintenance of posture.

Adolescent↗
PubMed1987

Regeneration following tibial nerve crush in the rabbit: the effect of proximal constriction.

In order to test the regenerative capacity of atrophic axons, a constricting ligature was placed around the proximal tibial nerve of the rabbit, and the nerve crushed at the ankle one week later. Axonal atrophy with altered g ratios was subsequently confirmed in fibres distal to the site of ligature and proximal to the site of crush. In nerves with tight proximal ligatures the reinnervation of plantar muscles and the subsequent recovery of distal motor latency were delayed, indicating impaired regeneration. This result may be relevant to the "double-crush" theory of nerve damage.

Action Potentials↗
PubMed1987

Differential effects of changes in mechanical limb properties on physiological and pathological tremor.

The effect of changes in mechanical limb properties on the peak frequency of different tremor forms was analysed. Wrist tremor was recorded by an accelerometer fixed to the dorsum of the hand and demodulated surface EMG was recorded from the wrist extensors, while the extended hand was loaded with successively heavier weights. Physiological tremor was characterised by flat EMG spectra and a gradual decrease in tremor peak frequency with increasing load, as would be expected from the properties of a passive spring-mass-system. Also the peak frequency of activated physiological tremor characterised by increased synchronisation between motor units decreased in frequency with increasing loads. EMG spectra showed clear peaks of activity at the various mechanically determined tremor frequencies. In contrast, in two pathological tremor forms, the postural tremor in Parkinsonian patients and essential tremor, peak frequency tended to remain stable irrespective of changes in load. The method therefore allows a simple distinction between physiological and these two pathological tremors.

Adolescent↗
PubMed1986

Normal myelination of regenerating peripheral nerve sprouts despite circulating antibodies to galactocerebroside in rabbits.

Rabbits were immunized with galactocerebroside and a crush lesion was created in the tibial nerve before the onset of experimental allergic neuritis. Normal regeneration and myelination of distal peripheral nerve sprouts occurred and was identical to that of controls, although circulating antigalactocerebroside antibodies were present and nerve roots showed typical signs of beginning experimental allergic neuritis.

Animals↗
PubMed1986

The muscle activity spectrum: spectral analysis of muscle force as an estimator of overall motor unit activity.

Starting from the observation that the part above 6 Hz of the power spectrum of force tremor during isometric contractions can be related to the unfused twitches of motor units firing asynchronously, an attempt was made to study the usefulness of force tremor spectral analysis as a global descriptor of motoneurone pool activity. To compensate for the mechanical low-pass filter characteristic of skeletal muscle which leads to increased damping of mechanical ripples at higher frequencies, a numerical compensation rule was derived from data obtained by electrical microstimulation of small ensembles of motor units (MUs). Hidden line plots of consecutive partially overlapping spectra allowed visualization of changes in spectral composition during ongoing muscle activity. The resulting muscle activity spectra (MAS) showed broad peaks according to the range of onset firing rates in normal subjects. These tended to shift to higher frequencies with increasing force. Under conditions with increased synchronization of the MUs these broad peaks were replaced by sharp peaks corresponding to the burst repetition rate. Patients with different motor dysfunctions were selected to illustrate how alterations of MU activity are reflected in the MAS. Decreased or increased firing rates were observed as well as abnormal states of synchronization. It is concluded that the MAS provides useful information about some aspects of the discharge characteristics of ensembles of MUs and therefore represents a method to monitor some qualitative 'image' of the MU activities within a muscle.

Adolescent↗