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Biomedical subjects

B Falck

Publications and source records attributed to B Falck.

At least 19 recordsLinked to original sources
PubMed1995

Influence of recording site within the muscle on motor unit potentials.

The influence of the recording site on the motor unit potentials (MUPs) was investigated in the brachial biceps muscle of 8 healthy subjects. The MUPs were recorded with a concentric needle electrode and analyzed with a new decomposition EMG program we call multi-MUP analysis. MUPs had shorter durations and smaller amplitudes at superficial recording sites than at deeper sites in the muscle. This is mainly due to the cannula of the concentric electrode, which records a higher potential at superficial recording sites and partially cancels the recorded potentials from the tip in a differential recording. The MUPs had longer durations and higher amplitudes distally than in the middle of the muscle. The longer durations and spike durations are probably due to increased temporal dispersion at a greater distance from the endplate zone. We do not have an adequate explanation for the larger amplitudes distally in the biceps, they may be due to anatomical factors. To increase the diagnostic sensitivity of quantitative MUP analysis the recordings should be obtained from standardized recording sites.

Adult↗
PubMed1992

Muscle pathology in idiopathic cricopharyngeal dysphagia. Enzyme histochemical and electron microscopic findings.

The structural changes in the cricopharyngeal muscle (CM) were examined ultrastructurally and by enzyme histochemistry in five patients suffering from idiopathic cricopharyngeal dysphagia (ICD). Diagnosis was established by fiberoptic esophagoscopy, esophageal manometry and cineradiography. Cricopharyngeal myotomy was performed with marked improvement in all patients. Intraoperatively, a biopsy was taken from the CM. Additionally, all patients underwent neurological examination for possible generalized muscle disease, and a biopsy was taken from a limb muscle. CM from nine cadavers without known history of dysphagia served as control. The control samples disclosed structural changes which were considered to be pathological in other skeletal muscles, and required that the criteria for CM pathology we modified accordingly. In three patients changes in CM histology suggested specific pathogenesis: one patient had evidence for a generalized myositis but was only symptomatic for dysphagia. Another patient had muscle fiber atrophy and slight inflammation in her CM, possibly due to alcohol abuse. The third patient had loss of CM fibers with replacement by connective tissue enough to cause functional disturbances. In two patients no cause for dysphagia was found in either immunohistochemistry or electron microscopic studies. These results demonstrate the special structural features of the CM and indicate that ICD can have multiple etiologies.

Adenosine Triphosphatases↗
PubMed1992

Diagnostic function of the microhuman prototype of the expert system--MUNIN.

This paper describes the diagnostic function of a prototype expert system for electromyography (EMG). The prototype was restricted to a limited "Microhuman" anatomy with only 6 muscles and 8 nerves, and a corresponding limitation on the number of local nerve lesions. It attempted to give a detailed description of the most important groups of generalized nerve and muscle disorders, and the commonly used parameters from needle EMG and nerve conduction studies were included. The system can be used both for "diagnostic" and for "causal" reasoning. In diagnostic reasoning, the system's probabilistic inference engine is used to reason from test results through 14 different aspects of neuromuscular pathophysiology to disorders. In causal reasoning, the system reasons in the opposite direction from disorders through pathophysiology to expected test results. The diagnostic function of the system was illustrated by 3 cases: a normal subject, a patient with a bilateral carpal tunnel syndrome and a patient with both a diabetic polyneuropathy and a bilateral carpal tunnel syndrome.

Carpal Tunnel Syndrome↗
PubMed1991

Effects of helodermin and VIP on insulin and glucagon secretion in the mouse.

Helodermin and vasoactive intestinal polypeptide (VIP) are structurally related peptides. We have examined their effects on insulin and glucagon secretion in the mouse. Following intravenous injection, helodermin and VIP equipotently increased plasma glucagon levels with a maximal effect obtained at the dose level of 2 nmol/kg. The maximal response was not augmented by giving the two peptides together at maximal dose levels, showing that helodermin and VIP stimulate glucagon secretion by activating the same mechanisms. Furthermore, both peptides markedly potentiated glucagon secretion stimulated by the cholinergic agonist carbachol, showing that they sensitize glucagon secretion for muscarinic activation. This sensitizing action was abolished by methylatropine, whereas the direct glucagonotropic action of the peptides was insensitive to muscarinic antagonism. Plasma insulin levels were not affected by helodermin but slightly increased by VIP. The study suggests that helodermin and VIP (1) stimulate basal glucagon secretion by the same mechanism, which is insensitive to muscarinic antagonism, (2) sensitize the glucagon secretion for cholinergic activation, and (3) have no or only weak effect on insulin secretion.

Animals↗
PubMed1991

Effects of neuropeptide Y on insulin and glucagon secretion in the pig.

Neuropeptide Y (NPY)-nerves occur in the pancreas. We therefore infused synthetic porcine NPY directly into the pancreatic artery in anaesthetized pigs to study its direct in vivo influence on pancreatic blood flow and on insulin and glucagon secretion. NPY was given both under basal, normoglycemic conditions, and during an ongoing intravenous infusion of glucose, which raised plasma glucose levels to 20 mM. NPY was infused at 0.5 (n = 2), 5 (n = 3), 35 (n = 7), or 175 (n = 5) pmol/min. We found that NPY at 5, 35, and 175 pmol/min inhibited glucagon secretion. Furthermore, at 35 and 175 pmol/min, NPY also reduced pancreatic blood flow. In contrast, only at 175 pmol/min, NPY inhibited basal and glucose-stimulated insulin secretion. We conclude that in the pig NPY might participate in the regulation of glucagon secretion (as an inhibitor) and of pancreatic blood flow (as a vasoconstrictor). In contrast, NPY does not seem to be involved in the regulation of insulin secretion.

Analysis of Variance↗
PubMed1991

Electromyography and morphology during regeneration of muscle injury in rats.

Healing of the partially ruptured rat gastrocnemius muscle was studied correlating electromyographical findings with morphological changes. Fibrillation potentials and positive sharp waves were seen both proximal and distal to the injury 7 days after the injury and disappeared in the proximal part by day 14 and in the distal part by day 21. Late components of motor action potential were observed from day 14 onwards. Denervation was mainly myogenic, i.e. caused either by rupture of myofibres, whence the abjunctional stump lost its contact with the neuromuscular junction on the adjunctional stump, or by necrosis of the segment of the ruptured myofibre lying underneath the neuromuscular junction. Lesser extent of denervation was neurogenic, i.e. caused by damage to intramuscular nerve fibres. The reinnervation occurs either by regeneration of the necrotized myofibres, by regeneration of the severed nerves, or by collateral innervation of new neuromuscular junctions in the abjunctional stumps. The present study indicates that electromyography may be useful in the diagnosis and follow-up of skeletal muscle injuries.

Animals↗
PubMed1991

Quantification of Birbeck's granules in human Langerhans' cells.

A proper understanding of the function of Birbeck's granules requires that they should be counted under various conditions. We now present a simple quantification method which does not depend on specific assumptions concerning size, shape or location of the particles counted and can, moreover, be applied for counting other subcellular structures as well. A population of 69 serially sectioned human Langerhans' cells had an average of 290 granules and no cell contained fewer than 96 granules, indicating that as they degrade, granules are continuously formed. Suprabasal Langerhans' cells contained significantly more granules than did the basal cells.

Biopsy↗
PubMed1991

Functionally different Langerhans' cells in human epidermis.

Experiments comparing the L-dopa histofluorescence method for the visualization of epidermal Langerhans' cells and immunocytochemical labelling with monoclonal anti-T6 antibodies have demonstrated the existence of two functionally different human Langerhans' cells: those that take up L-dopa by a mediated transport and those that lack the capacity to take up L-dopa.

Biological Transport↗
PubMed1990

Linkage disequilibrium detected between dystrophia myotonica and APOC2 locus in the Finnish population.

Three polymorphic loci APOC2, CKMM and p134C were used to haplotype 15 Finnish dystrophia myotonica (DM) families representing about one third of all DM patients in this isolated population. Compound APOC2 and CKMM haplotypes reveal linkage disequilibrium: 90% of DM chromosomes co-occur with the haplotypes that occur in 31% of normal chromosomes only. The same disequilibrium is present when only polymorphisms occurring at the APOC2 locus are used. Surprisingly, no statistically significant linkage disequilibrium was discovered at the CKMM locus alone. Of the meiotic events, 84% were informative when both APO2 and CKMM loci were used. When studied selectively, 60% of meiotic events were informative at the APOC2 locus, whereas CKMM alone resulted in 65% meiotic informativeness. The distal marker p134C was found to have an unfortunately low information content in our population.

Alleles↗
PubMed1990

The effect of Xylometazoline on the mucosa of human maxillary sinus.

A stuffy and running nose are two of the most expressed symptoms of acute rhinosinusitis and have made the use of decongestants very common. The medication, oral or nasal, gives relief from symptoms but its effect on the healing of the infection, positive or negative, is not clear. The effect of Xylometazoline on the blood flow, the pulse amplitude and the gas exchange in the antral mucosa of the maxillary sinus was studied in five healthy subjects. Our experiments show that the mucosal pulse amplitude and the blood flow are strongly reduced by insufflation of Xylometazoline but the gas exchange in the mucosa is only lowered to a minor extent. The reduction in gas exchange is not great enough to allow the gas mixture to be altered. The defence mechanisms in the antral mucosal lining, i.e. the mucociliary-, the immuno- and the phagocytotic mechanisms are all dependent on the blood flow and the gas exchange through narrow maxillary ostia of the pumping effect generated by the mucosal pulse wave. The reduction in blood flow and pulse amplitude in the maxillary mucosa caused by Xylometazoline leads us to consider that, although not harmful then it is at least not helpful, in healing rhinosinusitis. Since oral decongestants have almost the same effect on the mucosa as nasal decongestants, we do not think that any of the medicines faciliate the healing of infections in the upper airways even if they make the patient feel better during the infection.

Adrenergic alpha-Agonists↗
PubMed1990

Blood flow and pulse amplitude in the mucosa of the human maxillary sinus in relation to body posture.

The paranasal sinuses are non-collapsible ventilated gas pockets without any known function. They should, however, be adequately ventilated to stay healthy. Persons lying in a recumbent body position compared to persons sitting or standing upright have reduced antral mucosal blood flow, a reduction of 35%, and a congested mucosa which reduces both the mucosal gas exchange and the perostial ventilation, creating a more anaerobic antral gas mixture facilitating pathogenic bacterial growth and reduced ciliary activity. It is, therefore, recommendable for patients with sinusitis to treat themselves or be treated in an upright or semi-recumbent body position.

Adult↗
PubMed1990

A prospective study of patients with sciatica. A comparison between conservatively treated patients and patients who have undergone operation, Part I: Patient characteristics and differences between groups.

Based on a prospective study on 342 sciatica patients examined with rhizography, the aim was to determine which factors others than the rhizography finding and the grade and duration of symptoms were related to the selection of patients to undergo operation. Compared with surgically treated patients, conservatively treated patients who did not undergo operation and who had pathologic rhizography findings had pessimistic attitudes to possible surgery, often expressed a desire to retire, and considered their work as physically stressful. The women in this group were older and had lower pain indices than women who underwent operation. Conservatively treated patients with negative rhizography had more severe occupational handicaps, minor expectations of possible surgery, physically more strenuous jobs requiring difficult physical positions, and lower indices for pain and ADL than did the operated patients. The social and ergonomic background problems are emphasized in sciatica patients conservatively treated after rhizography.

Adult↗
PubMed1990

A prospective study of patients with sciatica. A comparison between conservatively treated patients and patients who have undergone operation, Part II: Results after one year follow-up.

The prospective study included 122 sciatica patients who had not undergone operation (NOPs) and 220 sciatica patients who had undergone operation (OPs); all had been examined by rhizography. The follow-up study was done on 110 (90%) of the NOPs and 212 (96%) of the OPs. The NOPs were divided into two groups: 30 patients with pathologic rhizography (PR) and 80 patients with negative rhizography (NR). Pain-, ADL-, and occupation-handicap indices showed that after the 1 year follow-up the OP group had the best result and the NR group the lowest result. The PR group had nearly as good a result as the OP group. Thus, sciatica patients are candidates for conservative therapy, even though they have pathologic findings in rhizography, if the symptoms are mild. To improve therapeutic outcome, more accurate diagnostic tools are needed to develop specific therapy especially for those sciatica patients with negative rhizography.

Adult↗
PubMed1989

Connective tissue changes of the multifidus muscle in patients with lumbar disc herniation. An immunohistologic study of collagen types I and III and fibronectin.

The connective tissue components, Types I and III collagen fibronectin, were immunohistologically analyzed using their specific antibodies for localization and semiquantitative estimation in 24 patients (11 women and 13 men, all under 55 years of age) operated on for herniated lumbar intervertebral disc. Nine cadavers without known back problems (2 women, 7 men) served as controls. In controls, Type I collagen was present in the endo- and perimysial structures of the muscle, more conspiciously in the former. Type III collagen, together with fibronectin, were more abundant in the perimysium than in the endomysium. Thickening of these structures was not evident in the controls. In most patients Types I and III collagen and fibronectin distribution was similar to that of the controls. However, fibrotic changes of both and endo- and perimysial structures involved all Types I and III collagen and fibronectin in ten cases. In two patients an increase in Type I collagen staining intensity in the endomysium was recorded and thickening of the endomysial structures was observed in six patients. There were correlations with the severity of the connective tissue structural changes to atrophy of the muscle and furthermore to disability of the patient in the 1-year postoperative check-up. These findings suggest that if marked fibrosis of the muscle occurs, it can be a factor impairing recovery from the disease during the long-term postoperative course.

Adult↗
PubMed1989

The relationship between body posture and pressure in occluded maxillary sinus of man.

One of the most common symptoms in sinusitis is pain over the infected cavity increasing when the patient is bending forward or lying down. It is commonly thought that this increase in pain is a result of increased pressure in the paranasal cavities when bending forward. In this investigation we have found that changing the body position from sitting to recumbent or even to "head between knees" gives a manometrical pressure rise in the sinus that is too small to cause a pressure-mediated pain. The pain is probably caused by a dilation in the blood vessels of the infected mucosa when the patient is bending forward or lying down.

Adult↗