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Biomedical subjects

A Lundberg

Publications and source records attributed to A Lundberg.

At least 109 records · Page 6Linked to original sources
PubMed1979

Metabolic substrates, muscle fibre composition and fibre size in late walking and normal children.

In 10 children with delayed walking, muscle specimens were obtained by needle biopsy from the vastus lateralis muscle for determination of ATP, creatine phosphate (CP), glycogen and lactate concentration, as well as fibre composition and fibre size. The values obtained are compared with corresponding results for a control group of 25 children aged 2 months--11 years. Details of the control series are given and its validity as a reference group is discussed. Six children (group I) who showed minor gross motor delay but otherwise normal development at follow-up were found to have lowered ATP, CP and glycogen concentrations, compared to 4 children (group II) who had general developmental delay, and to the control group. The children in group I were shown to have smaller fibre size and a greater difference between type 1 and 2 fibres than the children in group II and in the control group. No differences in the concentrations of metabolic substrates or the morphometric values could be detected between group II and the control group.

Adenosine Triphosphate↗
PubMed1979

Muscle abnormalities in coeliac disease: studies on gross motor development and muscle fibre composition, size and metabolic substrates.

In 11 children with coeliac disease gross motor development was assessed before and during diet treatment using the gross motor subscale of the Denver developmental screening test. ATP, creatine phosphate (CP), glycogen and lactate concentrations, muscle fibre size and fibre composition were measured in specimens obtained by needle biopsy from the vastus lateralis muscle. Before treatment, gross motor development was delayed. ATP, and to a lesser extent, CP and glycogen concentrations were lowered compared to a control group. After treatment, gross motor development was normal and no differences in ATP, CP or glycogen concentrations were found compared to the control group. Fibre size seemed unaffected by the disease. The percentage of type 1 fibres was significantly lower before treatment, compared to values obtained during treatment and from the control group. Whether these metabolic changes were due to the coeliac disease per se or the inactivity which it causes was not possible to establish. In humans, only altered neurogenic influence on the muscles has been previously shown to give changes in fibre composition.

Adenosine Triphosphate↗
PubMed1979

The drawing test -- a tool for assessment of arm-hand function in children of 1--3 years of age.

The construction and evaluation of a simple drawing test for assessment of arm-hand function in children of 1--3 years of age are described. A thick crayon (1.2 x 10 cm) and a piece of white paper (20 x 30 cm) are the only equipment needed. The need, when assessing fine motor development, of a test for evaluation of arm-hand function and the advantages of the test described are discussed. It is concluded that the method is of diagnostic value in children with CNS and neuromuscular disorders and is a useful tool for clinical studies and for routine developmental examination.

Arm↗
PubMed1979

Gross and fine motor performance in healthy Swedish children aged fifteen and eighteen months.

Gross and fine motor performance have been assessed in thirtynine 15-month-old and thirtynine 18-month-old children selected through systematic sampling from a population of healthy newborns. The performance was estimated with corresponding subscales of Denver Developmental Screening Test and Motor age test. In addition fine motor performance was assessed by the "Drawing test" for which the expected performance at 15 and 18 months is given. Of the 78 children, 83% had crawled on hand and knees, 9% crept on their tummy and 8% shuffled on their bottom before walking. Median age for walking was 11.8 months, the 97th percentile 16.0 months. Of the 15-month-old children, 90% walked with ability to stop and start, and 90% of the 18-month-old were in addition able to walk backwards, run stiffly, climb up and down a standard staircase and seat themselves in an armchair of suitable size. Of the 15-month-old, 90% were able to build a tower of two cubes or more, and 90% of the 18-month-old were able to build a tower of three cubes or more (size 1 1/2 inch). Almost 90% of the 15-month-old and all of the 18-month-old had the cognitive ability to coordinate a crayon and paper. In drawing attempts of the 15 month-old, the weak unstable combination with a top-tong/tong grasp and 1/2 pronated forearm was the dominating hand-grasp fore-arm position. In the 18 month-old a more mature grasp and forearm combination, mainly palmar grasp with or without stablizing index finger + overpronated forearm, was found.

Age Factors↗
PubMed1979

Dissociated motor development--developmental patterns, clinical characteristics, causal factors and outcome, with special reference to late walking children.

Dissociated motor development, defined as marked gross motor delay without any abnormal neurological signs and contrasting to a normal fine motor-adaptive performance, was studied prospectively in a consecutive in a consecutive series of 78 children, 48 girls and 30 boys, aged 7-23 months at first examination. When 17 months of age, 10 of them had become normalized, and in further three a disability explaining their gross motor delay had been diagnosed. At an average age of 4.2 years, the remaining 65 late walkers were, regardless of cause and developmental and neurological findings at final follow-up, characterized by a number of deviating clinical features as muscular hypotonia (71%), shuffling (51%) and dissociated or late pattern of learning to sit (79%). In 30 out of 65 late walkers (46%) a defined clinical condition of probable pathogenetic implication was found. In 35 out of 65 late walkers (54%), no explaining clinical condition was found. They have been designed to be idiopathic late walkers. Except for muscular hypotonia, present in 77%, conventional neurology was normal in this group. Minor neurological signs such as a positive Foerster sign, defect balance reactions in standing, or asymmetry in prewalking locomotion were, however, occasionally and temporarily observed. Girls were overrepresented among idiopathic late walkers, 69% compared to 43% among the symptomatic late walkers. Complete normalization was more common in the idiopathic group (66%) than in the symptomatic group (27%). Early differentiation between the late walkers who were normalized and those who developed mild mental retardation or neurological handicaps was difficult but not quite impossible. Heredity for shuffling, a non-revealing pre- and perinatal history, a developmental pattern of late learning to sit, and shuffling favoured a normal outcome. Creepers with a dissociated pattern of learning to sit and crawlers with muscular hypotonia were found to have an increased risk for later handicap.

Child↗
PubMed1978

Integration in descending motor pathways controlling the forelimb in the cat. 5. Properties of and monosynaptic excitatory convergence on C3--C4 propriospinal neurones.

Recording was made in the C3--C4 segments from cell bodies of propriospinal neurones identified by their antidromic activation from more caudal segments. Monosynaptic excitatory effects from descending motor pathways and primary afferents were investigated by electrical stimulation of higher motor centres and peripheral nerves in the forelimb and neck. The cell bodies were located mainly laterally in Rexed's layer VII. Threshold mapping for single axons showed that they descend in the lateroventral part of the lateral funicle. Antidromic stimulation at different spinal cord levels showed that some neurones terminated in the forelimb segments, others in the thoracic cord or in the lumbar segments. Terminal slowing of the conduction velocity suggested axonal branching over some segments. Monosynaptic EPSPs were evoked in the neurons by stimulation of the contralateral pyramid, red nucleus and dorsal tegmentum-superior colliculus. It is concluded that corticospinal, rubrospinal and tectospinal fibres project directly to both short and long propriospinal neurones. There was marked frequency potentiation in tectospinal synapses. Convergence from two descending tracts was common and in half of the tested cells all three tracts contributed monosynaptic excitation. Experiments with collision of descending volleys and antidromic volleys from the brachial segments demonstrated that the corticospinal and rubrospinal monosynaptic projection to the propriospinal neurones is by collaterals from fibres continuing to the forelimb segments.

Action Potentials↗
PubMed1978

Maximal aerobic capacity of young people with spastic cerebral palsy.

Maximal aerobic capacity in bicycle ergometer tests was studied in nine children (aged 11 to 12 years) and five young men (aged 19 to 23 years), all with a spastic form of cerebral palsy, and compared with non-handicapped control groups. Results showed somewhat lower values for heart rate, oxygen uptake/kg, ventilation/kg and blood lactate concentrations for the majority of the spastic group. The physical work capacity of the handicapped group amounted to about 50 per cent of the corresponding values for the non-handicapped controls. Poor mechanical efficiency in the spastic group is the consequence of high oxygen uptake in relation to the work performed. The poor mechanical performance is mainly caused by the extra amount of energy required for qualitative changes in the muscle (constant hypertonia), involuntary movements and stabilizing movements during exercise on the bicycle ergometer.

Adult↗
PubMed1978

Role of joint afferents in motor control exemplified by effects on reflex pathways from Ib afferents.

1. Intracellular recording from motoneurones to hind limb muscles in the cat was used to investigate the effect of volleys in the posterior nerve to the knee joint on motoneurones and on transmission from Ib afferents. 2. Volleys in the joint nerve facilitate transmission in disynaptic and trisynaptic inhibitory and excitatory reflex pathways from Ib afferents. It is postulated that facilitation, which appears at a strength of 1.5 times threshold, is evoked, not by Ib afferents which 'contaminate' the joint nerve, but by afferents from joints receptors. 3. T;e time course of facilitation of the disynaptic Ib i.p.s.p.s in motoneurones indicates that these joint afferents have disynaptic connexions with the interneurones of the Ib inhibitory pathway. 4. A brief description is given of synaptic effects evoked in motoneurones by graded electrical stimulation of the posterior nerve to the knee joint. At low stimulus strength the effects may be evoked via interneurones of Ib reflex pathways, but some results suggest that other interneuronal paths are utilized as well. Somewhat higher strengths, but occasionally less than 2 times threshold, produce later synaptic effects presumably mediated by reflex paths from the flexor reflex afferents; it does not seem likely that the contributory afferents in the joint nerve have nociceptive function. 5. It is suggested that impulses from impulses from joint receptors can influence tension regulation from Golgi tendon organs; if these receptors are activated in the terminal phase of the movement they may contribute a purposeful decrease of tension. It is pointed out that joint receptors may have an important role in motor regulation by their effects on interneurones of the different neuronal systems controlling motoneurones.

Animals↗
PubMed1978

Reciprocal inhibition during the tonic stretch reflex in the decerebrate cat.

1. The aim of this study was to investigate post-synaptic reciprocal Ia inhibition during the stretch reflex; particularly the extent to which an increased Ia excitation of the Ia inhibitory interneurones will be counteracted by recurrent inhibition from motor axon collaterals. For this purpose we investigated depression of monosynaptic test reflexes antagonist flexors (reciprocal inhibition) during static stretch of quadriceps or triceps surae in unanaesthetized decerebrate cats. 3. With increasing stretch of the extensor muscle there was first a linear augmentation of reciprocal inhibition, but along with the stretch reflex in the extensor a plateau appeared in the inhibition of the flexors, although the extensor stretch reflex (judged by the e.m.g.) increased with further stretching. Within the range of stretching of triceps surae which gave increased stretch reflexes the plateau in the reciprocal inhibition was usually maintained, while during stretching of quadriceps a second phase of augmenting reciprocal inhibition often appeared. Stretch beyond the level which increased the stretch reflex activity gave augmenting reciprocal inhibition both in case of quadriceps and triceps surae. 3. Excitability measurements from central terminals of Ia afferents revealed that the increasing reciprocal inhibition during increasing stretch reflex activity in quadriceps was associated with a primary afferent depolarization in knee flexor Ia afferents; there was no corresponding effect in ankle flexor Ia afferents during stretch reflexes in triceps surae. 4. The primary afferent depolarization evoked in knee flexor Ia afferents by electrical nerve stimulation was then compared with the presynaptic inhibition of knee flexor monosynaptic test reflexes produced by the same stimuli. The results suggest that the second phase of increasing reciprocal inhibition in knee flexors is due to presynaptic inhibition and accordingly that the depth of post-synaptic reciprocal inhibition remains constant at different degrees of stretch reflex activity in both knee and ankle extensors. 5. It is postulated that during increasing stretch reflex activity the increment in Ia excitation and recurrent inhibitio; on to the Ia inhibitory interneurones almost exactly balance each other. It is suggested that recurrent inhibition of Ia inhibitory interneurones may serve as a segmental autoregulatory mechanism to keep 'alpha-gamma-linked reciprocal inhibition' at a constant depth during different levels of agonist activity.

Animals↗
PubMed1977

Cutaneous facilitation of transmission in reflex pathways from Ib afferents to motoneurones.

1. The effect of volleys in low threshold cutaneous afferents upon transmission of synaptic action from Ib afferents to motoneurones has been investigated with intracellular recording from alpha motoneurones to hind limb muscles. 2. There was facilitation from cutaneous afferents of transmission in excitatory and inhibitory reflex pathways from Ib afferents without any evidence for difference in effect on di- and trisynaptic pathways. It is postulated that volleys in cutaneous afferents evoke excitatory action in interneurones of these reflex pathways. 3. The time course of the facilitation suggest that cutaneous afferents have disynaptic excitatory connexions with the interneurones intercalated in the disynaptic Ib inhibitory pathways to motoneurones. 4. Some observations are reported suggesting that interneuronal transmission in Ib inhibitory pathways to motoneurones might be facilitated from Ia afferents. 5. The findings are discussed in relation to the presumed role of Ib reflex action in regulating muscle tension.

Action Potentials↗
PubMed1976

Integration in descending motor pathways controlling the forelimb in the cat. 1. Pyramidal effects on motoneurones.

Stimulation of the contralateral pyramid and intracellular recording from forelimb motoneurones was used to investigate corticimotoneuronal pathways in the cat. A train of pyramidal volleys evokes short-latency EPSPS in flexor motoneurones and in many extensor motoneurones. The latency for the onset after the effective pyramidal volley-usually the third - strongly indicates a disynaptic linkage. These disynaptic EPSPs were common in triceps motoneurones to fast heads but rare in those to slow heads. Pyramidal IPSPs with a slightly longer latency, suggesting a trisynaptic linkage, were found in both flexor and extensor motoneurones. They were common in motoneurones to slow heads of triceps. Disynaptic pyramidal IPSPs were found only occasionally. In addition pyramidal volleys may evoke late large EPSPs and/or IPSPs in any combination with the short-latency PSPs.

Animals↗
PubMed1976

Integration in descending motor pathways controlling the forelimb in the cat. 2. Convergence on neurones mediating disynaptic cortico-motoneuronal excitation.

With intracellular recording from forelimb motoneurones the spatial facilitation technique has been used to investigate interaction between descending pathways and forelimb afferents. As previously shown for the hindlimb, pyramidal volleys effectively facilitate interneuronal transmission in reflex pathways from different primary afferents. Evidence is presented suggesting disynaptic excitation from corticospinal fibres of interneurones in the reciprocal Ia inhibitory pathway. Interneurones of other reflex pathways from group I muscle afferents recieve monosynaptic pyramidal excitation. During pyramidal facilitation volleys in cutaneous afferents may evoke PSPs in motoneurones after a central delay of 1.3 ms suggesting that the minimal linkage is disynaptic. Information regarding convergence on the neurones intercalated in the disynaptic cortico-motoneuronal pathway was obtained by investigating the effect from primary afferents and from other descending pathways on the disynaptic pyramidal EPSPs. Volleys in cutaneous and group I muscle affferents facilitate transmission in the disynaptic cortico-motoneuronal transmission with a time course showing oligosynaptic (probably monosynaptic) action the intercalated neurone. Rubrospinal volleys likewise effectively facilitate disynaptic cortico-motoneuronal pathway with a time course showing oligosynaptic (probably monosynaptic) action on the intercalated neurone. Rubrospinal volleys likewise effectively facilitate disynaptic cortico-motoneuronal transmission with a time course showing monosynaptic action on the intercalated neurone. Spatial facilitation experiments involving three tests revealed that those intercalated neurones which receive convergent monosynaptic excitation from corticospinal and rubrospinal fibres are excited also from cutaneous forelimb afferents. Disynaptic cortico-motoneuronal transmission was also monosynaptically facilitated by stimuli in the dorsal mesencephalic tegmentum probably activating tectospinal fibres. Disynaptic, presumed tectospinal EPSPs were facilitated from cutaneous forelimb afferents. The convergence onto the neurones intercalated in the disynaptic excitatory cortico-motoneuronal pathway suggests that these neurones integrate the activity in different descending pathways and primary forelimb afferents.

Animals↗
PubMed1976

Oxygen consumption in relation to work load in students with cerebral palsy.

Eighteen adolescents with various forms of cerebral palsy performed tests on a mechanically braked ergometer bicycle. VO2 was measured at different loads and net mechanical efficiency calculated. It was found that efficiency was poor at light loads for most of the students but that there were significant intergroup differences in mechanical efficiency at higher loads. The leveling-off plateau demonstrated by healthy adolescents was only attained by a few of the disabled students. It was concluded that the muscle hypertonia and involuntary movements were responsible for the high level of energy expended in the mechanical work performed.

Adolescent↗