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Biomedical subjects

K Borg

Publications and source records attributed to K Borg.

At least 73 records · Page 4Linked to original sources
PubMed1991

Inclusion body myositis and Welander distal myopathy: a clinical, neurophysiological and morphological comparison.

Five patients with inclusion body myositis (IBM), an acquired inflammatory myopathy, and five patients with Welander hereditary distal myopathy (WDM) were compared clinically and with neurophysiological and morphological techniques. Both diseases have a late insidious onset, but the course of IBM is more severe. IBM mainly affects proximal muscles in the lower extremities, while distal muscle groups are involved in both upper and lower extremities. In WDM there is always a strict distal muscle involvement. The neurophysiological characteristics of the two conditions include both myopathic and neurogenic components. In both diseases there were rimmed vacuoles in muscle fibres and at the ultrastructural level cytoplasmic 15-18 nm filamentous inclusions. Although the histopathology of muscle in IBM and WDM has some common features, inflammatory infiltrates were never found in WDM. Such infiltrates seem to be an important clue to the correct diagnosis of IBM.

Aged↗
PubMed1991

Prior poliomyelitis-reduced capillary supply and metabolic enzyme content in hypertrophic slow-twitch (type I) muscle fibres.

Capillary supply and oxidative and glycolytic enzyme activities were determined in muscle biopsies from the tibialis anterior muscle in six prior polio patients and a control group. The polio patients, who had paresis and atrophy, but were able to walk normally by making maximal use of all remaining anterior tibial motor units, showed type I (slow-twitch) muscle fibre predominance with a mean (SD) of 98 (2%) type I fibres versus 81 (8)% in the controls (p less than 0.01) and muscle fibre hypertrophy, the average type I fibre cross-sectional area being 108% (p less than 0.005) larger than in the controls. The number of capillaries per muscle fibre was not significantly different from that in the control group, but with the increased muscle fibre area in the polio patients, the capillary density was significantly lower. The number of capillaries in contact with type I fibres relative to fibre area was 40% lower in the patients than in the controls (p less than 0.005). The levels of citrate synthase and phosphofructokinase were significantly lower (38% and 33%, respectively, p less than 0.05) in the patients than in the controls, indicating decreased oxidative and glycolytic potentials in the muscle fibres of the polio patients. It is proposed that the abnormal high-frequency activation of all remaining motor units during each step cycle recorded in these patients constitutes a stimulus for type I muscle fibre predominance and hypertrophy but that the overall low muscle usage results in a decreased stimulation of capillary proliferation and mitochondrial enzyme synthesis. The low capillary density and decreased oxidative and glycolytic enzyme potentials might be important factors for the development of muscle weakness, fatigue and muscle pain, which are commonly occurring symptoms in patients with prior poliomyelitis.

Adult↗
PubMed1991

Welander's distal myopathy: clinical, neurophysiological and muscle biopsy observations in young and middle aged adults with early symptoms.

Nine young or middle aged patients with early symptoms of Welander's distal myopathy were subjected to a detailed neurological examination including quantitative sensory testing, determination of motor and sensory nerve conduction velocity (NCV), sensory nerve action potentials, electromyography (EMG) and muscle biopsy from the tibialis anterior muscle (TA). Slight weakness of the extensors of the fingers and hands was found in all nine patients, and of the dorsiflexors of the feet in seven. All patients had a distal sensory disturbance most prominent for temperature which agrees with earlier observations. EMG changes in TA and extensor digitorum communis (EDC) muscles were of myopathic type. Slight abnormalities compatible with either myopathy or early neuropathy were found in one muscle biopsy. These findings indicate that a neurogenic lesion affecting at least the peripheral sensory system is present at an early stage of Welander's distal myopathy and that the neurogenic lesion might precede the myopathic changes.

Adult↗
PubMed1991

Combination of natural teeth and osseointegrated implants as prosthesis abutments: a 2-year longitudinal study.

Twenty-three patients with Kennedy Class I mandibular dentition were supplied with prostheses in the posterior parts of the mandible. On one side they were given a prosthesis supported by two implants (prosthesis Type I) and on the other side they received a prosthesis supported by one implant and one natural tooth (prosthesis Type II). Sixty-nine fixtures were inserted and 46 prostheses constructed. Eight of the fixtures were lost during the observation period. The failure rate of the implants was about the same in the two types of prostheses; five fixtures belonged to prostheses Type I (10.9%) and two fixtures belonged to prostheses Type II (8.7%), while one fixture was lost prior to loading. From a theoretical point of view, the combination of a tooth and an osseointegrated implant should encounter problems with regard to the difference in bone anchorage and there should be a risk of biomechanical complications. However, the results of this study did not indicate any disadvantages in connecting teeth and implants in the same restoration.

Adult↗
PubMed1990

Fibre-type composition, structure and cytoskeletal protein location of fibres in anterior tibial muscle. Comparison between young adults and physically active aged humans.

Muscle biopsies were obtained from the anterior tibial muscle (TA) of 15 healthy, sedentary young (23-37 years) and 13 healthy and physically active elderly (66-77 years) volunteers. The mean frequency of type I fibres was lower in the young subjects compared with the elderly, but the mean type I fibre cross-sectional area was equal in the two groups. The type IIA fibres were, however, smaller in the elderly than in young subjects. Capillary density, capillary per fibre ratio, capillaries in contact with type I fibres (CC) and CC in relation to type I and type II fibre area did not differ in the two groups. The number of capillaries in contact with type IIA fibres was higher in the younger group. Only occasional and minor pathological changes were observed in the young subjects. In the elderly, such changes were much more common, including central nuclei, ring fibres, fibre splitting, scattered highly atrophic fibres, moth-eaten fibres and vacuoles. Ring fibres were most easily identified with anti-desmin labelling and highly atrophic fibres exhibited a rough network of labelling. Increased content of actin and spectrin was also observed at the periphery of ring fibres. In the elderly group, a qualitative ultrastructural analysis was also obtained and obvious changes included some myofilament loss, collections of lipofuscin which were also observed in satellite cells, proliferation of the SR-T systems and increased wrinkling of nuclear membranes and sarcolemma.

Adult↗
PubMed1990

Lung function in patients with prior poliomyelitis.

Lung volumes and spirometric flows, maximal respiratory pressures, lung diffusion capacity and blood gases were evaluated in 20 patients with prior poliomyelitis and compared with data from an age- and sex-matched control group. In the polio patients, static lung volumes and pulmonary flow capacity were significantly reduced to approximately 65% of the values of the control group. However, expiratory and inspiratory flows were normal in relation to lung volumes, while maximal respiratory pressures were significantly reduced in the polio patients. Static lung volumes and forced flows were correlated with the maximal respiratory pressures both in the polio patients and in the controls. However, when the muscle force in the polio patients decreased below a certain level, it became more important as a determinant of lung-flow capacity. The polio patients had a significantly increased PCO2 but a normal oxygen saturation and PCO2 was inversely correlated with the maximal respiratory pressures in the patients but not in the controls. The lung diffusion capacity was reduced in the polio patients compared to the controls, but less markedly than vital and total lung capacity. The findings indicate a restrictive respiratory dysfunction and alveolar hypoventilation most probably due to weakness of the respiratory muscles.

Adult↗
PubMed1990

Osseointegrated implants in edentulous jaws: a 2-year longitudinal study.

Osseointegrated implants in 50 edentulous jaws were studied during a 2-year observation period. The implant survival rate was 89% in the maxillae and 97% in the mandibles. The marginal bone loss averaged 1.7 mm in the maxillae and 1.1 mm in the mandibles. Most of this bone loss occurred during the first year. The bone loss was greater in jaws with a preoperatively minor resorption of the alveolar ridge than in those with moderate or advanced resorption. The bone loss was also greater at the medially positioned implants than at those more posterior.

Adult↗
PubMed1989

Neurogenic involvement in distal myopathy (Welander). Histochemical and morphological observations on muscle and nerve biopsies.

Patients with distal myopathy (Welander) were subjected to muscle biopsy from the anterior tibial muscle (n = 4) and to nerve biopsy from the sural nerve at the ankle (n = 5) in order to elucidate a possible neurogenic component of the disease. The type I muscle fibres had a larger mean cross-sectional area as compared to normal controls and an increased variation in fibre size with both hypertrophic and atrophic fibres in one and the same biopsy. A normal muscle fibre type composition was found in the patients. Structural muscle fibre abnormalities such as atrophic fibres, mainly angulated, split fibres, rimmed vacuoles and centrally located nuclei were found in all biopsies. A disorganization and loss of myofibrils as well as autolytic vacuoles were the most prominent findings at the ultrastructural level. Two patients had a moderate loss of myelinated sural nerve fibres. The mean nerve fibre density was decreased as compared to normal controls while the mean nerve fibre area and circular diameter were increased due to selective loss of small diameter (A-delta) nerve fibres. The muscle and nerve fibre abnormalities are discussed with reference to neuropathic and myopathic changes. Some muscle fibre abnormalities are typical for a neurogenic disorder while some others are mostly seen in myopathies but may also appear in neurogenic conditions. A neurogenic etiology in Welander distal myopathy is further supported by the finding of loss of small diameter nerve fibres in the sural nerve.

Adult↗
PubMed1989

Uptake of 63Ni2+ in the central and peripheral nervous system of mice after oral administration: effects of treatments with halogenated 8-hydroxyquinolines.

Oral administration of 63Ni2+ to mice resulted in higher levels of the metal in the sciatic nerves, the trigeminal ganglia, spinal nerve roots and the spinal cord than in the cerebellum and the frontal cortex. In the sciatic nerves, the trigeminal ganglia and the spinal nerve roots a high vascular permeability may explain the preferential uptake of the 63Ni2+. The higher accumulation of the 63Ni2+ in the spinal cord than in the examined structures of the brain may be related to a diffusion from the cerebrospinal fluid. Administrations of halogenated 8-hydroxyquinolines [5,7-diiodo-8-hydroxyquinoline (diI-HQ), 5,7-dibromo-8-hydroxyquinoline (diBr-HQ), 5,7-dichloro-8-hydroxyquinoline (diCl-HQ) or 5-chloro-7-iodo-8-hydroxyquinoline (Cl-I-HQ)] together with the 63Ni2+ resulted in increased levels of the metal both in neural and extraneural tissues in comparison with mice given the 63Ni2+ alone. In most instances the tissue-levels of 63Ni2+ were 2-4 times higher in the animals treated with the halogenated 8-hydroxyquinolines than in the controls. Determinations of chloroform/water partition coefficients showed that lipophilic chelates are formed between each of these compounds and the nickel. Our results are probably explained by a facilitated passage of the complexed metal over the walls of the stomach and the intestine. The halogenated 8-hydroxyquinolines are linked with the SMON-syndrome, a disease which occurred primarily in Japan. The possibility that this syndrome may be causally connected with a concomitant intake of these drugs and metals is discussed.

Administration, Oral↗
PubMed1989

Motoneuron firing and isomyosin type of muscle fibres in prior polio.

In patients with prior polio there was an excessive use of remaining motor units and an absence of type II muscle fibres in the tibialis anterior (TA). In the present study, eight subjects with prior polio with more than 90% type I fibres in the TA were examined. The aim was to elucidate whether the lack of type II muscle fibres was due to a selective loss of motoneurons with high threshold and high axonal conduction velocity or due to a muscle fibre transition from type II to type I. There was no decrease of the proportion of motoneurons with high threshold and high axonal conduction velocity. Monoclonal antibodies against fast and slow myosin heavy chains (MHC) were used as histochemical markers and many muscle fibres of type I according to ATPase stainability showed a binding of both anti-fast and anti-slow MHC. It is suggested that the type I muscle fibre dominance in prior polio subjects with excessive use of TA during walking is due to a muscle fibre transition from type II to type I and not to a loss of one class of motor units.

Adult↗
PubMed1988

Use of motor units in relation to muscle fiber type and size in man.

The use of the musculus tibialis anterior during walking and the type and size of its muscle fibers were determined in 15 young normal subjects (29 +/- 4 years) and in 13 old healthy subjects (70 +/- 3 years). In the average step cycle 16 +/- 6% of the maximal surface EMG was recorded during the swing phase and 44 +/- 15% during 100 msec at the heel strike. Single motor unit recordings showed that low-threshold units fired at 10-15 Hz during the swing and at 20-25 Hz during the heel strike peak. Usually, high-threshold units did not participate in the ordinary step cycle. A significantly higher mean use was found in the old subjects as compared with the young ones presumably due to lower muscle power in relation to body weight. In the young subjects 76 +/- 7% of the muscle fibers were type 1 and 22 +/- 7% were type 2A. In the old subjects 84 +/- 9% were type 1 and 15 +/- 8% were type 2A. In the young subjects the mean cross-sectional area of type 1 fibers was 3950 +/- 950 microns2 and of type 2 fibers was 8070 +/- 1850 microns2. In the old subjects the corresponding numerals were 4050 +/- 890 microns2 and 5700 +/- 1970 microns2, respectively. The significance of physiological variations in use for muscle fiber type composition and size is discussed.

Adult↗
PubMed1988

Effects of excessive use of remaining muscle fibers in prior polio and LV lesion.

Twenty-three subjects with weakness of musculus tibialis anterior (TA) due to prior poliomyelitis (n = 19) or prior LV lesion (n = 4) were examined regarding the use of remaining TA motor units during walking and the consequences of long-term overuse for the TA muscle fibers. Subjects with an excessive overuse exhibited almost only type 1 muscle fibers and with marked hypertrophy. Subjects who did not use remaining TA fibers because of too-severe paralysis had a normal fiber type differentiation and fiber atrophy. The use of remaining TA motor units was correlated to the type 1 muscle fiber percentage (r = 0.69) and to the type 1 fiber size (r = 0.78). Identical changes were observed in subjects with prior poliomyelitis and in subjects with prior LV lesion and were, thus, not specific for poliomyelitis. The changes in fiber type composition may be explained by a transition of type 2 to type 1 muscle fibers in accordance with previously reported experimental transneuronal stimulation through implanted electrodes in animals.

Adolescent↗
PubMed1988

Effects of some chelating agents on the uptake and distribution of 203Hg2+ in the brown trout (Salmo trutta): studies on ethyl- and isopropylxanthate, diethyl- and diisopropyldithiophosphate, dimethyl- and diethyldithiocarbamate and pyridinethione.

Brown trout, Salmo trutta, were exposed to water containing 0.1 microgram/l 203Hg2+, alone or with potassium ethylxanthate (PEX), sodium isopropylxanthate (SIX), sodium diethyldithiophosphate (SEP), sodium diisopropyldithiophosphate (SIP), sodium dimethyldithiocarbamate (SMC), sodium diethyldithiocarbamate (SEC) or sodium pyridinethione (SPyr), respectively. After 1 week the uptake and distribution of the 203Hg2+ in the fish were examined by gamma spectrometry. SIX, SIP, SMC, SEC and SPyr induced 2-3 times higher 203Hg2+ concentrations in most tissues in comparison with trout exposed to 203Hg2+ only. In the trout exposed to PEX slightly enhanced 203Hg2+ levels were found only in some tissues, and after exposure to SEP a few tissues showed decreased 203Hg2+ concentrations. Determinations of chloroform/water partition coefficients showed that lipophilic chelates are formed between all the examined substances and the 203Hg2+. However, SIX, SIP, SMC, SEC and SPyr, which induced markedly increased tissue levels of the metal, formed 203Hg2+ complexes with higher lipophilicities than SEX and SEP. A facilitated penetration of the lipophilic 203Hg2+ complexes over the gill membranes may underly the increment in the tissue levels of the metal, and the relative lipophilicity of the complexes may be of importance for this effect. In some instances, as with SEP, the 203Hg2+ chelated in complexes with low lipophilicity may even be less able to acumulate in some tissues than the non-complexed metal.

Animals↗
PubMed1988

Effect of thiram and dithiocarbamate pesticides on the gastrointestinal absorption and distribution of nickel in mice.

Oral administration of dimethyldithiocarbamate pesticides (ferbam, ziram or sodium dimethyldithiocarbamate) or thiram together with nickel resulted in increased levels of the metal in several tissues of rats, in comparison with animals given only nickel. In contrast, the administration of nickel together with ethylene- or propylenebisdithiocarbamates (zineb, maneb, nabam or propineb) resulted in unchanged tissue levels or, most marked for nabam, reduced the tissue concentrations of the metal. Among the compounds which were able to increase tissue levels of nickel, thiram was the most effective one, followed in decreasing order by ferbam, ziram and sodium dimethyldithiocarbamate. The central nervous system was among the tissues which showed the highest relative increase. For thiram, an accumulation of nickel was observed in the pancreatic islets. The results are discussed in relation to the formation of chelates between nickel and the studied compounds or their metabolites.

Animals↗
PubMed1988

Diagnostic value of quantitative sensory testing (QST) in carpal tunnel syndrome.

The initial sensory symptoms of carpal tunnel syndrome (CTS) are usually intermittent and the clinical neurological examination is often normal. The aim of the present study was to determine the rate of impairment of different somatosensory modalities in CTS by means of the following tests: vibrametry, tactile pulses, von Frey hairs, two-point discrimination (2-PD), graphesthesia and warm and cold perception thresholds. The material consisted of 33 hands with CTS from 22 patients. Each of the first 3 tests was abnormal with elevated thresholds in 17 CTS hands (52%), 2-PD was abnormal in 10 hands (30%), graphesthesia in 8 hands (24%), and warm and cold thresholds in only 5 hands (15%). There was an overlap so that at least one test was abnormal in 27 of the 33 CTS hands (82%). Thus, impairment of sensibility can be demonstrated in a majority of patients with CTS if more than one test is applied. Vibrametry and von Frey hairs are recommended instead of the commonly used 2-PD, since abnormality was more often revealed and since they are equally easy to apply. No individual test was sensitive enough to qualify as a diagnostic criterion when it was applied with the hand in resting position. A significant increase in both sensitivity and specificity can be expected for any test if it is combined with provocation, such as wrist flexion, as has been demonstrated for vibrametry.

Adult↗
PubMed1988

Autonomic cardiovascular responses in antecedent poliomyelitis.

Autonomically mediated cardiovascular responses were evaluated in 20 subjects with antecedent poliomyelitis and compared to data from an age- and sex-matched control group. The polio subjects had a lower heart rate response to the Valsalva manoeuvre but the same respiratory sinus arrhythmia as the controls. From this it is concluded that the polio subjects had a normal vagal function. The polio subjects had a greater initial heart rate increase but the same blood pressure response to the orthostatic position as the controls. This indicates a normal function of the sympathetic nerves. The greater heart rate increase is most likely caused by a displacement of blood to the legs because of muscle atrophy. The polio subjects had a smaller blood flow increase as an initial response to an isometric handgrip than the controls. This might be attributed to a reduced beta-adrenergic vasodilation, possibly due to a reduced central vasomotor drive. It is concluded that subjects with antecedent poliomyelitis have no significant dysfunction of the peripheral autonomic nerves. Thus, there is no deterioration of the peripheral autonomic nerve function in parallel with the progressive muscle atrophy and paralysis earlier described in post-polio subjects.

Adult↗
PubMed1988

Effect of potassium ethylxanthate and sodium diethyldithiocarbamate on the accumulation and disposition of nickel in the brown trout (Salmo trutta).

Brown trouts, Salmo trutta, were exposed to water containing 0.1 or 10 micrograms/l of 63Ni2+, alone or with potassium ethylxanthate or sodium diethyldithiocarbamate. After one and three weeks the accumulation and disposition of the 63Ni2+ in the fish were examined by liquid scintillation spectrometry and whole-body autoradiography. The sodium diethyldithiocarbamate was found to greatly enhance the uptake of 63Ni2+ in several tissues of the trouts. Potassium ethylxanthate was without effect. Diethyldithiocarbamate is known to form lipophilic complexes with metals, including nickel, and a facilitated penetration of the complexed nickel over the cellular membranes of the gills and other tissues is a likely mechanism underlying our results. The ethylxanthate is also able to form a lipophilic nickel-chelate, although of a lower lipophilicity than the nickel-diethyldithiocarbamate-complex. This variance in lipophilicity may explain why the disposition of the 63Ni2+ was affected by the diethyldithiocarbamate, but not by the ethylxanthate.

Animals↗