Biomedical subjects

G Schalow

Publications and source records attributed to G Schalow.

At least 37 records · Page 2Linked to original sources

PubMed1995

Classification of human peripheral nerve fibre groups by conduction velocity and nerve fibre diameter is preserved following spinal cord lesion.

(1) Single nerve fibre action potentials (APs) of lower sacral nerve roots were recorded extracellularly with two pairs of wire electrodes during an operation in which an anterior root stimulator for bladder control was implanted in 9 humans with a spinal cord lesion and dyssynergia of the urinary bladder. Roots that were not saved and that were used to record from were later used for morphometry. (2) Nerve fibre groups were identified by conduction velocity distribution histograms of single afferent and efferent fibres and partly by nerve fibre diameter distribution histograms, and correlation analysis was performed. Group conduction velocity values were obtained additionally from compound action potentials (CAPs) evoked by electrical stimulation of nerve roots and the urinary bladder. (3) The group conduction velocities and group nerve fibre diameters had the following pair-values at 35.5 degrees C: Spindle afferents: SP1 (65 m/s/13.1 microns), SP2 (51/12.1); touch afferents: T1 (47/11.1), T2 (39/10.1), T3 (27/9.1), T4 (19/8.1); urinary bladder afferents: S1 (41 m/s/-), ST (35/-); alpha-motoneurons: alpha 13 (-/14.4), alpha 12 (65m/s/13.1 microns), alpha 11 (60?/12.1)(FF), alpha 2 (51/10.3)(FR), alpha 3 (41/8.2)(S); gamma-motoneurons: gamma beta (27/7.1), gamma 1 (21/6.6), gamma 21 (16/5.8), gamma 22 (14/5.1); preganglionic parasympathetic motoneurons: (10 m/s/3.7 microns). (4) The values of group conduction velocity and group nerve fibre diameter measured in the paraplegics were very similar to those obtained earlier from brain-dead humans and patients with no spinal cord lesions. Also, the number and the density of myelinated fibres were preserved in the roots. Thus, the classification and identification of nerve fibre groups remained preserved following spinal cord lesion. A direct comparison can thus be made of natural impulse patterns of afferent and efferent nerve fibres between paraplegics (pathologic) and brain-dead humans (supraspinal destroyed CNS, in many respects physiologic). (5) When changing the root temperature from 32 degrees C to 35.5 degrees C, the group conduction velocities changed in the following way in one case: SP2: 40 m/s (32 degrees C) to 50 m/s (35.5 degrees C), S1: 31.3 to 40, ST: 25 to 33.8, M: 12.5 to 13.8; alpha 2: 40 to 50, alpha 3: 33 to 40. The group conduction velocities showed different temperature dependence apart from SP2 fibres and alpha 2-motoneurons. (6) Upon retrograde bladder filling the urinary bladder stretch (S1) and tension receptor afferent (ST) activity levels were undulating and increased.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1995

Detrusor-sphincteric dyssynergia in paraplegics compared with the synergia in a brain-dead human by using the single-fibre action potential recording method.

(1) Humans with spinal cord lesions often show detrusor-sphincteric dyssynergia of the urinary bladder which is reflected urodynamically in the detrusor pressure and a simultaneous increase in electromyographic pelvic floor activity. (2) The time-course of the increase in the secondary muscle spindle afferent activity, induced by the parasympathetic nervous system in muscle spindles contributing to continence, is very similar to that of detrusor pressure. The detrusor-sphincteric dyssynergia is therefore analysed by comparing the natural impulse patterns of secondary muscle spindle afferents (SP2) and sphincteric motoneurons in a brain-dead human with those in patients with spinal cord lesion. The parasympathetic nervous system was activated by painful bladder catheter pulling. (3) In a brain-dead human the sphincteric motoneurons subserving continence were inhibited at a time, when preganglionic parasympathetic efferents increased their activity for 10 s and an SP2 fibre increased its activity for several minutes. In a paraplegic with a strong bladder dysfunction, the SP2 fibre activity increased, due to parasympathetic activation, lasted for approx. 1 min, showed undulations and its amplitude was smaller than that measured in a brain-dead human. The sphincteric motoneurons were not inhibited. (4) In the brain-dead human, an SP2 fibre showed doublet firing with interspike intervals (IIs) of a duration between 10 and 14 ms for low level parasympathetic activation. For high level parasympathetic activation this single parent spindle afferent fibre showed multi-ending regular firing of up to 6 endings with IIs of a duration of predominantly 15 to 25 ms. In one paraplegic with a strong bladder dysfunction the doublet firing was less regular, even though two II peaks at 10.2 and 11.2 ms occurred in a II distribution similar to the brain-dead human. The multi-ending regular firing was replaced by a repeated burst firing. In a second paraplegic with strong detrusor-sphincteric dyssynergia the burst firing consisted of up to 6 impulses with increasing IIs and a first II of approx. 0.2 ms (transmission frequency 5000 Hz). In a third paraplegic with a lesser dysfunction of the bladder a highly activated SP2 fibre showed an activity pattern intermediate to those of multi-ending regular firing and burst firing. (5) The time constant for the activity decrease of a spindle afferent fibre following parasympathetic activation was to 31 s in a paraplegic and approx. 40 s in a brain-dead human. It is concluded that the muscle spindles are unchanged following spinal cord lesion.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1995

Detrusor-sphincteric dyssynergia in humans with spinal cord lesions may be caused by a loss of stable phase relations between and within oscillatory firing neuronal networks of the sacral micturition center.

(1) Single-fibre action potentials (APs) were recorded with 2 pairs of wire electrodes from lower sacral nerve roots during surgery in patients with spinal cord lesions and in a brain-dead human. Conduction velocity distribution histograms were constructed for afferent and efferent fibres, nerve fibre groups were identified and simultaneous impulse patterns of alpha and gamma-motoneurons and secondary muscle spindle afferents (SP2) were constructed. Temporal relations between afferent and efferent APs were analysed by interspike interval (II) and phase relation changes. (2) In a paraplegic with hyperreflexia of the bladder, urinary bladder stretch (S1) and tension receptor afferents (ST) fired already when the bladder was empty, and showed a several times higher bladder afferent activity increase upon retrograde bladder filling than observed in the brain-dead individual. Two alpha 2-motoneurons (FR) innervating the external bladder sphincter were already oscillatory firing to generate high activity levels when the bladder was empty. They showed activity levels with no bladder filling, comparable to those measured at a bladder filling of 600 ml in the brain-dead individual. A bladder storage volume of 600 ml was thus lost in the paraplegic, due to a too high bladder afferent input to the sacral micturition center, secondary to inflammation and hypertrophy of the detrusor. (3) In a brain-dead human, 2 phase relations existed per oscillation period of 160 ms between the APs of a sphincteric oscillatory firing alpha 2-motoneuron, a dynamic fusimotor and a secondary muscle spindle afferent fibre. Following stimulation of mainly somatic afferent fibres, the phase relations changed only little. (4) In a paraplegic with dyssynergia of the urinary bladder also 2 phase relations existed per oscillation period of 110 ms in a functional unit between the APs of a sphincteric alpha-motoneuron, a fusimotor and a secondary spindle afferent fibre. The phase relations changed with time following stimulation of mainly somatic afferents. A second functional unit organized by phase-related interactions was phase related to the first functional unit. (5) Following painful bladder catheter pulling, the parasympathetic division was transiently activated several times in the paraplegic. At times of activation of the parasympathetic division, 3 broad phase relations occurred within and between the two functional units, indicating that the parasympathetic division in the sacral micturition and defecation center channeled an additional input to the somatic oscillatory firing neuronal networks driving motoneurons which innervate the external bladder and/or anal sphincters.

Action Potentials↗

PubMed1994

Nerve compound action potentials analysed with the simultaneously measured single fibre action potentials in humans.

1. Compound action potentials (APs) and single fibre APs were recorded with two pairs of wire electrodes from an S5 root from a paraplegic patient during surgery. 2. Frequency distribution histograms of single nerve fibre conduction velocities were constructed and nerve fibre group conduction velocities compared with the conduction velocities of the peaks of the compound APs. By increasing the strength of the stimulation, the peaks in the compound AP could be identified, and the threshold order of efferent nerve fibre groups determined. Using additional literature data, it is likely that the primary spindle afferents have the lowest threshold due to electrical nerve root stimulation followed by the alpha 1-motoneurons (FF), the secondary muscle spindle afferents, the alpha 2-motoneurons (FR), the alpha 3-motoneurons (S), the gamma beta, gamma 1 (dynamic), gamma 21 (static), gamma 22 (static), and the parasympathetic motoneurons. 3. In first approximations, the Ap duration increases in the same way as the AP amplitude decreases with decreasing conduction velocity, and the area between the average single fibre AP curve and the base-line is the same for all single fibre APs with an average same distance to the recording electrodes in the root cross-section. By comparing the mean area of a single fibre AP with the areas of the peaks of the compound APs, it was found that 230 single fibre APs contributed to the compound AP. In the secondary spindle afferent fibre and alpha 2-motoneurons groups 53 fibres were stimulated (23%). The alpha 3-motoneuron peak and the afferents in the same velocity range contained 101 fibres (44%), the gamma beta peak contained 9 fibres (4%), the gamma 1 32 (14%), the gamma 21 23 (10%) and the gamma 22 12 (5%) fibres. Additionally two primary spindle afferents and two alpha 1-motoneurons most likely contributed to the compound AP. Since the large peaks in the compound APs did not change their area with increasing stimulation, most likely all muscle spindle afferents and alpha-motoneurons were activated to contribute to the compound AP. 4. Transfer functions of nerves and the stimulation with natural impulse patterns of the adequate afferents to spinal oscillators with respect to continence in paraplegia are discussed.

Action Potentials↗

PubMed1994

Interspike intervals of secondary muscle spindle and urinary bladder afferents in relation to the oscillation periods of sacral spinal oscillators for continence in man.

Two pairs of wire electrodes were used to record afferent and efferent single fibre extracellular action potentials (APs) from human nerve root filaments. The nerve fibres were identified according to the group to which they belong by comparing the afferent and efferent conduction velocity distribution histograms and identifying peaks and ranges of nerve fibre groups. Secondary muscle spindle afferents and alpha 2-motoneurones (FR) were identified by having the same peak group conduction velocity (calibration relation), which is 50 m/s at 36 degrees C. On the basis of AP wave form comparisons, the natural impulse patterns of five secondary muscle spindle afferents, two fusimotor motoneurones and two oscillatory firing alpha 2-motoneurones could be identified in the dorsal S4 root. The patterns of single endings of secondary spindle afferent fibres could be identified. The shortest interspike intervals of single endings of all secondary muscle spindle afferents had the same duration as the shortest interspike intervals of the two fusimotor fibres (80 ms) and equalled a half of the oscillation period of one repetitively firing alpha 2-motoneurone (6 Hz) probably innervating the external anal sphincter (three AP impulse train firing). In another more rostral dorsal root filament (probably S3 or S2) of the same human, the interspike intervals of six secondary spindle afferents were more variable. The values of peaks in the interspike interval distributions ranged from 60 to 102 ms. In the coccygeal root, the interspike interval duration ranged from 160 to 185 ms, directly contributing to the drive of the oscillatory firing alpha 2-motoneurone. The different agreement between the oscillation period and the interspike intervals of the spindle afferents in different segments indicate that the oscillatory firing CNS circuitry was localized within S3 to S5 segments of the conus medullaris for the drive of the anal sphincter. An alpha 2-motoneurone firing repeatedly with 1 to 2 AP impulse trains, innervating most likely the external urethral sphincter, fired at a frequency of 9.1 to 6.7 Hz, a similar frequency of the oscillation as the interspike intervals from two activated stretch receptors of the urinary bladder wall. The measurements of this brain-dead human indicates that in this case the neuronal circuitry driving the external anal sphincter was mainly confined to the sacral micturition and defecation centre, mainly located in the S3 to S5 segments.

Action Potentials↗

PubMed1993

Impulse patterns of single encoding sites of human secondary muscle spindle afferents.

1. By recording single-fibre action potentials (APs) from human sacral nerve roots, the impulse patterns of 6 secondary spindle afferents could be identified, analysed and compared with the impulse trains of oscillatory firing alpha 2-motoneurons. 2. Secondary spindle afferents fired with single APs, doublets, bursts and equidistant APs. On the assumption that the most simple firing pattern of a single fibre with a shortest interspike interval (II) of 80 msec was generated by a single encoding site, the firing patterns of the other afferents could be splitted into firing patterns of single encoding sites with similar II distributions and also with a shortest II of about 80 msec. 3. Successive IIs also reflected the different ways of firing of the secondary muscle spindle afferents. A fibre from a paraplegic with bladder dyssynergia seemed to show a higher activity than a comparable probably normal fibre. The doublet IIs of two secondary spindle afferents ranged from about 9 to 14 msec with peaks at 10.2, 11.2 and 13 msec in the distributions. Multiple encoder sites increased discharge rates of parent fibres, but did not always regularize the output discharge. 4. The simultaneously plotted impulse patterns of 4 secondary spindle afferents showed coordinated firing: they did not fire simultaneously but regularized the summed activity. A phase of 50 msec (range 30 to 70 msec) often occurred between the spindle afferent APs and the impulse trains of an oscillatory firing alpha 2-motoneuron. An afferent drive of the oscillator with a certain phase is likely.

Action Potentials↗

PubMed1993

Phase correlated adequate afferent action potentials as a drive of human spinal oscillators.

1. By recording, with 2 pairs of wire electrodes, single-fibre action potentials (APs) from lower sacral nerve roots of a brain-dead human and a patient with spinal cord lesion, impulse patterns of afferent APs and impulse trains of oscillatory firing motoneurons could be identified and correlated. 2. Two highly activated secondary muscle spindle afferents increased and decreased their activity at about 0.3 Hz. The duration of the doublet interspike interval of a secondary spindle afferent fibre showed no correlation to the oscillation period of the motoneuron. 3. A continuously oscillatory firing motoneuron innervating the external and sphincter showed more transient breaks with the reduction of the number of phase correlated APs from 2 spindle afferents, indicating a looser oscillation. A transient brake of a 157 msec period alpha 2-oscillation could be correlated to the shift of a interspike interval distribution peak from 150 to 180 msec of the adequate afferent input, which suggests a transient loss of the necessary phase relation. 4. Oscillatory firing alpha 2-motoneurons innervating the external bladder and anal sphincters fired independently according to their phase correlated APs from the urinary bladder stretch receptor and muscle spindle afferents respectively; the bladder motoneuron slightly inhibited the anal motoneuron. 5. Receptors of the afferents and innervation sites of oscillatory firing motoneurons could be located within the urinary tract and the anal canal.

Action Potentials↗

PubMed1993

Action potential patterns of intrafusal gamma and parasympathetic motoneurons, secondary muscle spindle afferents and an oscillatory firing alpha 2-motoneuron, and the phase relations among them in humans.

1. Single-fibre action potentials (APs) were recorded from a S4 root of a brain-dead human and a patient with a spinal cord lesion, with 2 pairs of wire electrodes, and distribution histograms of conduction velocity frequencies were constructed. By plotting the intrafusal velocity main gamma peak on a logarithmic scale, the peak splitted into one dynamic ad two static gamma-peaks and an additional peak of parasympathetic fibres. 2. Apart from the doublet firing, a single gamma 1 (dynamic) and a single gamma 21-motoneuron (static) fired with shortest interspike intervals of 80 msec, similarly as a simultaneously firing secondary spindle afferent fibre; with 13 msec the doublet interspike interval of the gamma 1-motoneuron was very similar to that of the spindle afferent fibre. The intrafusal motoneurons fired with patterns very similar to those of secondary spindle afferents, and they did not fire in the oscillatory mode for high activations as alpha 2 and alpha 3-motoneurons do. 3. The stability of the oscillatory firing of a sphincteric alpha 2-motoneuron increased with the increasing phases of approx. 50 msec between the APs of the gamma-motoneurons and the impulse train of the motoneuron following bladder catheter pulling. Moreover, in a certain phase range the number of phases between the APs of a gamma 1-motoneuron and a secondary spindle afferent fibre increased upon stimulation and, as shown earlier, also the number of phase correlations between the APs of some secondary spindle afferents and the impulse train of the oscillatory firing alpha 2-motoneuron increased. Phase relations between the APs of two spindle afferents also increased upon the bladder catheter pulling. During the oscillatory firing of the alpha 2-motoneuron a phase loop seemed to exist from the APs of the alpha 2-motoneuron to the APs of certain gamma-motoneurons, to the APs of certain secondary spindle afferent fibres and back to the APs of the alpha 2-motoneuron, in similarity to the phase recoupling of electronic oscillators. 4. Single gamma-motoneurons changed their activity levels rhythmically, similarly as the secondary spindle afferents, often with a frequency of 0.3 Hz. Parasympathetic intrafusal motoneurons fired at a constant activity level for about 10 sec, and activated up to 6 single encoding sites of a parent secondary spindle afferent fibre. Shortly after the recruitment of a new encoding site, the interspike intervals of the parent fibre were similar again.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1992

Enhancement of nerve fibre regeneration by nucleotides after peripheral nerve crush damage. Electrophysiologic and morphometric investigations.

The effect of nucleotide administration on the regeneration of myelinated nerve fibres following crush injury to the sciatic nerve of the rat was studied using both morphometric and electroneurophysiologic techniques. After a standardized localized crush lesion of the right sciatic nerve, rats were given nucleotides daily at a dosage of 3.0 mg/kg body wt uridine monophosphate (UMP), 2.5 mg/kg body wt cytidine monophosphate (CMP) or 3.0 plus 2.5 mg/kg body wt UMP plus CMP, respectively. Observations were made after 20, 40 and 60 days of nerve regeneration for comparison with age-matched crushed or nonoperated controls. Electroneurophysiologic studies of right sural nerves were performed as single fibre measurements. Morphometry was performed on semithin transverse sections of the right common peroneal nerve with a fully automatic interactive image analysis system. Forty days after crush injury the single fibre conduction velocity of all type II afferents in the UMP/CMP treated group was significantly accelerated. There was a trend (10% greater than or equal to p greater than or equal to 5%) to increase of mean efferent single nerve fibre function at this time. Morphometry of nerve fibres revealed a trend to enlargement of mean fibre area and mean fibre diameter related to increased myelin area and myelin thickness. After 60 days, there was a trend to increase of single fibre conduction velocity of all type II afferents in the UMP/CMP treated group. Automated morphometry revealed a significant increase for the following parameters: fibre area, fibre diameter, myelin area, myelin thickness and axon area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Recruitment within the groups of gamma 1, alpha 2 and alpha 3-motoneurons in dogs and humans following bladder and anal catheter pulling.

Conduction velocity frequency distribution histograms were constructed from lower sacral root recordings of single intrafusal (gamma) and extrafusal (alpha) motoneurons. The velocity distributions of occasional and stimulated activity before and following bladder and anal catheter pulling were almost identical for dogs and humans. The limits of the velocity ranges of alpha 1(FF), alpha 2(FS) and alpha 3(S) and gamma beta(?)-motoneurons were determined from the broadness of the single peaks. The borders of the partly fused peaks of gamma 1 and gamma 21-motoneurons were estimated from their different functional properties. Activity levels of the alpha 1, alpha 2, alpha 3, gamma beta, gamma 1 and gamma 21-motoneurons were too complex to allow safe conclusions from the dog measurements, probably because of the representation of leg and tail in addition to sphincter functions in the lower sacral root. In the human dorsal S4 root, in which mainly efferent functions of sphincters only were contained, the gamma 21, gamma 1, alpha 2 and alpha 3-motoneurons showed simple behaviour. Distribution changes of conduction velocities in each group of alpha and gamma-motoneurons were used for recruitment analysis. Following stimulation in dogs and humans, within the groups of gamma 1, alpha 3 and alpha 2-motoneurons, slowly conducting fibres were activated before the faster conducting ones. The alpha 3-motoneurons were recruited later than the alpha 2-motoneurons. In the dog, low gamma 1 and alpha 2-motoneuron velocities occurred preferentially 0 to 0.2 s following strong bladder catheter pulling, probably in the mono- and oligosynaptic pathways. Low conduction velocities of alpha 3-motoneurons occurred more often 1 to 1.2 s following stimulation. At 2 to 2.2 s following stimulation, the high gamma 1 and alpha 2-motoneuron velocities were more activated. At 4 to 4.2 s following stimulation, low gamma 1 and alpha 2-motoneuron velocities were recruited again. Following strong bladder catheter pulling, co-recruitment of the gamma 1 and alpha 2-motoneurons seemed to occur. Following anal catheter pulling in the dog there was no co-recruitment of gamma 1 and alpha 2-motoneurons. In the case of gamma 1-alpha 2 co-recruitment, the gamma 1-motoneurons were recruited additionally once in between the co-recruitment. The higher frequency of recruitment of the gamma 1-motoneurons, and the separate recruitment of the gamma 1 and alpha 2-systems, indicate that the activation of gamma 1 and alpha 2-motoneurons are not strongly linked.(ABSTRACT TRUNCATED AT 400 WORDS)

Anal Canal↗

PubMed1992

Ventral root afferent and dorsal root efferent fibres in dog and human lower sacral nerve roots.

Two pairs of wire electrodes were used to record single afferent action potentials from ventral roots and single efferent action potentials from dorsal roots of dogs and humans. A human lower sacral ventral root contained about 20 to 30% afferents among fibres with a diameter larger than 5 microns; a comparable ventral root of a dog contained about 1% afferents. Human S3, S4 and S5 dorsal roots contained 3, 18, and 20 to 30% efferent fibres respectively; a comparable dorsal root of the dog contained less than 1% efferent fibres. Primary and secondary muscle spindle afferents, Golgi tendon organ afferents, and afferents from the mechanoreceptors of the urinary bladder and anal canal mucosa were activated in a dog ventral root by pulling bladder and anal catheters. Their peak group conduction velocities were 82, 57, 71 and 18 m/s at 34 degrees C respectively. The dog afferents conducted more than 30% faster than did comparable human nerve fibres. By strongly pulling the bladder catheter, the static human dorsal root gamma 21-motoneurons increased their activity for about 7 s which in turn strongly increased the dorsal root spindle afferent activity for more than 10 min; the human static intrafusal gamma-motoneurons seemed to show cumulative properties.

Action Potentials↗

PubMed1992

Group conduction velocities and nerve fibre diameters of alpha and gamma-motoneurons from lower sacral nerve roots of the dog and humans.

Single action potentials and their conduction times were recorded extracellularly from dog and human lower sacral nerve roots. Conduction velocity frequency distribution histograms were constructed and peaks of single extrafusal and intrafusal motoneuron distributions were identified. The electrophysiologically measured roots were removed and morphometrically analysed. Nerve fibre diameter frequency distribution histograms were constructed with respect to 3 myelin sheath thickness ranges, and peaks of single motoneuron group distributions were identified. The identified motoneuron classes, characterized by their group peak values of conduction velocity at about 36 degrees C and fibre diameter were: dog: intrafusal: gamma 22(23ms-1/4.8 microns),gamma 21(33/5.7), gamma 1 (43/6.7),gamma beta?(54/10.1) extrafusal: alpha 3(61ms-1/11.7 microns),alpha 2(72/13.6), alpha 11 (81/15.2), alpha 12(86/16.8),alpha 13(95/19) human: intrafusal: gamma 21(15ms-1/5.8 microns), gamma 1(20/6.8), gamma beta?(27/7.2) extrafusal: alpha 3(37ms-1/8.3 microns),alpha 2(50/10.2), alpha 1(60/13.1) The 60 (alpha 3) to 30% (alpha 1-motoneurons) higher conduction velocities in dogs as compared to humans seem to originate in the 40 (alpha 3) to 30% (alpha 1-motoneurons) larger nerve fibre diameters. However, the myelin sheath seemed to be 0.1 to 0.2 microns thinner in dogs than in humans. The pair-values "conduction velocity-fibre diameter" of the alpha and gamma-motoneuron groups were lying on different correlation curves in the velocity-diameter plane indicating structural and/or geometrical differences between alpha and gamma-motoneurons.

Action Potentials↗

PubMed1992

Acceleration of nerve and muscle regeneration by administration of nucleotides--electroneurophysiological and morphometrical investigations.

The effect of nucleotide administration on the regeneration of myelinated nerve fibres following crush injury to the sciatic nerve of the rat was studied using morphometric techniques. In addition morphometrical investigations of peroneal and soleal muscles were performed at different times. After a localized crush lesion of the right sciatic nerve, rats were given nucleotides daily at a dosage of 3.0 mg/kg body wt uridine monophosphate (UM), 2.5 mg/kg body wt cytidine monophosphate (CMP) or 3.0 plus 2.5 mg/kg body wt UMP plus CMP, respectively. Observations were made after 20, 40 and 60 days of common peroneal nerve regeneration for comparison with age-matched crushed or nonoperated controls. Forty days after daily UMP/CMP administration the single fibre conduction velocity of all type II afferents was significantly accelerated. There was a trend towards increased mean fibre area related to increased myelin area. Mean diameter of type II muscle fibres was increased. After 60 days, there was a trend to increase of single afferent fibre conduction velocity in the UMP/CMP group. In the same group automated morphometry revealed a significant increase of nerve fibre area, myelin area and axon area. At this time an increase was found of type I and/or type II muscle fibres in all animal groups. The present results suggest that both axons (neurons) and myelin sheaths (Schwann cells) of regenerating nerve fibres and regenerating muscle fibres are influenced by nucleotide administration.

Animals↗

PubMed1992

Impulse pattern, innervation density and two point discrimination of skin and mucosal afferents in humans. Considerations for a sensory reinnervation of urinary bladder and anal canal in spinal cord lesions. IV (IV).

1. Single fiber action potentials (Ap's) were recorded with 2 pairs of wire electrodes from a coccygeal nerve root. Simultaneous impulse patterns of 3T0 + 6T1 + 3T2 + 11T3 + 5T4 and 4P single skin afferent units were separated by their different Ap wave forms and conduction velocities. For a rapid touch or pin-prick the afferent units fired on average with 2 Ap's. 2. The touch units had most likely the following receptor properties. T1: rapidly adapting, medium high threshold, sensitive to skin traction over a distance of more than 10 cm. T2: rapidly adapting, high threshold. T3: slowly adapting, lowest threshold among T afferents for a light touch with no movement along the skin. T4: slowly adapting, lowest threshold among T afferents for a light touch with a movement component parallel to the skin surface. The T1 to T4 afferent receptors are the PC, RA, SAI and SAII receptors respectively. The correspondence is not safe. 3. With nerve fibre diameter distribution histograms (morph), myelinated fibre numbers, conduction velocity distribution histograms (electro) and Ap occurrence patterns, innervations were determined. With estimated dermatome areas, innervation densities i of skin dermatomes were calculated for nerve fibre diameters larger than 5 microns: i(electro, morph; Co) = (0.6T0 + 1.2T1 + 2.8T2 + 2.4T3 + 1.2T4 + 1.6P)/cm2, i(morph; S4) = (0.4T0 + 1T1 + 0.8T2 + 1.1T3 + 0.5T4)/cm2, i(electro; S4) = 0.4T0 + 2.3T1 + 2.1T2 + 2T3 + 1.5T4)cm2, i(morph; T9) (lateral)) = (0.8 (T0 or hair follicle) + 1.7T1 + 0.9T2 + 0.7T3 + 0.4T4)/cm2. 4. Innervation densities of mucosal afferent units M of urethra, trigonum vesicae and anal canal through S3 and S4 roots had the following lower limits: i(electro; urethra + trigonum) = 2 M/cm2, i(electro; anal canal) = 3 M/cm2. The innervation density of skin like receptors of the anal canal through an S4 ventral root was with i(electro; anal canal) = (0.5T0 + 2.4T1 + 1.6T2 + 1.2T3 + 0.8T4)/cm2 at least as high as the innervation density of the S4 dermatome. The urethra possesses no skin like receptors in the mucosa. Mechanoreceptor afferents of the mucosa (M) of urethra and anal canal had thresholds similar to those of T3 and T4 afferents. 5. The two point discrimination of a volunteer was for a light touch 30 mm in the S3 and S4 dermatomes and reduced to 25 mm with faster and stronger touch. In the direction of the anus and the os coccygeum the two point discrimination reduced to 25 mm.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1991

[Acceleration of muscle regeneration by nucleotide administration. Experimental morphometric studies].

Morphometric studies of the peroneus longus muscle as well as of the soleus muscle were performed 20, 40 and 60 days after crush injury of sciatic nerve and continuous administration of nucleotides. 96 female Wistar rats were used in the experiments. Under ether anesthesia a crush injury was performed on the right sciatic nerve. 53 rats were injected daily with nucleotides (uridine monophosphate [UMP], cytidine monophosphate [CMP] or UMP plus CMP [UMP/CMP], respectively), and 43 control animals were given injections of saline. Morphometric studies of right peroneus longus and soleus muscles were performed with the aid of a semiautomatic technique to measure muscle fibre diameters. After 20 days there were no differences between mean muscle fibre diameters. 40 days after the beginning of the experiments semiautomated morphometry revealed an increase of type II fibre diameters in the UMP/CMP group. There were enlargements of type II fibres in the UMP and the CMP group after 60 days. At the same time larger diameters of type I fibres were found in the UMP/CMP group (trend) and in the UMP group. In conclusion the results presented here indicate, that the administration of nucleotides possibly represents a new opportunity for the treatment of traumatic nerve and muscle lesions.

Animals↗

PubMed1991

Conduction velocities and nerve fibre diameters of touch, pain, urinary bladder and anal canal afferents and alpha and gamma-motoneurons in human dorsal sacral roots.

1. Single action potentials were recorded extracellularly at 2 sites from human sacral dorsal nerve roots, and their conduction time measured. Conduction velocity frequency distribution histograms were constructed from afferent and efferent nerve fibres. Conduction velocity distribution peaks could be identified from afferents of mechanoreceptors of the skin, the bladder, the anal canal, of stretch and flow receptors of the urinary bladder, from spindle afferents and from the 3 alpha (extrafusal) and 3 gamma-motoneuron (intrafusal) classes. The electrophysiologically measured roots were removed and morphometrically analysed. Nerve fibre diameter frequency distribution histograms were constructed with respect to 3 myelin sheath thickness ranges. Nerve fibre diameter distribution peaks could partly be correlated to the corresponding conduction velocity distribution peaks. 2. Identified nerve fibre classes, characterized by their group peak values of conduction velocity and fibre diameter were at about 36 degrees C (age 30 years): Spindle afferents: SP1 (60 msec-1/13.2 microns) SP2 (50/12.0?); touch afferents: TO (49 msec-1/13.0 microns), T1 (44/11.2), T2 (39/10.1), T3 (31/9.1), T4 (20/8.3); pain afferents: P (13 msec-1/?); mucosa touch afferents from bladder and anal canal: M (12.5 msec-1/?); bladder afferents from stretch receptors measuring probably mural tension: S1 (42.5 msec-1/?), ST (38/?) and from flow receptors: S2 (12.5/?); alpha-motoneurons: alpha 1 (60 msec-1/13.1 microns) [FF], alpha 11 (?/12.0) [F (int)], alpha 2 (50/10.2) [FR], alpha 3 (37/8.3) [S]; gamma-motoneurons: gamma beta (27 msec-1/7.2 microns), gamma 1 (20/6.7), gamma 2 (15/6.2). 3. Because of the strong temperature dependence of the conduction velocities a calibration of the structure of the velocities, which was almost independent of temperature, is defined by the condition that the alpha 2-motoneurons have the same peak conduction velocity then the secondary spindle afferents (SP2); the T1 touch afferents have about 10% lower velocity values. 4. Touch afferents and alpha-motoneurons had a different velocity-diameter relation, which indicated differences in the myelin sheath thickness and/or membrane properties. The conduction velocities of the touch afferents were more temperature-dependent than those of the alpha-motoneurons. Within the classes of touch afferents and alpha-motoneurons the temperature dependence increased towards smaller class peak values. 5. Through the use of action potential wave form comparisons it was possible to identify action potentials from single nerve fibres in each class of touch afferents (T0 to T4). Activity patterns of single touch units could partly be analysed.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1991

Oscillatory firing of single human sphincteric alpha 2 and alpha 3-motoneurons reflexly activated for the continence of urinary bladder and rectum. Restoration of bladder function in paraplegia.

1. By recording with 2 pairs of wire electrodes from human sacral nerve roots (S3-S5) rhythmic as well as occasional firing was observed in alpha 2 and alpha 3-motoneurons in response to physiologic stimulation of the urinary bladder and the anal canal. The rhythmic firing consisted of periodically occurring impulse trains, most likely produced by true spinal oscillators which drove the motoneurons. 2. Alpha 2-motoneurons, innervating fast fatigue-resistant muscle fibres, were observed to fire with impulse trains of about 2 to 4 action potentials (Ap's). These impulse trains occurred every 110 to 170 msec (5-9 Hz). Alpha 3-motoneurons, innervating slow fatigue-resistant muscle fibres, fired about every 1400 msec (approximately 0.7 Hz) with impulse trains of about 11 to 60 Ap's. Alpha 1-motoneurons, innervating fast fatigue muscle fibres, and gamma-motoneurons were not observed in the continuous oscillatory firing mode. 3. Sphincteric motoneurons were observed most likely in the oscillatory firing mode in response to the sustained stretch (reflex) of the external and sphincter or to retrograde filling of the bladder (urethro-sphincteric guarding reflex), in order to preserve continence. A urethral sphincteric alpha 2-motoneuron increased its mean activity from 0.5 to 18 Ap's/sec during retrograde filling by changing its firing pattern from the occasional spike mode via the transient oscillatory firing mode to the continuous oscillatory mode. Up to a filling of the bladder of 500 ml the mean activity of the stretch receptors, measuring probably mural tension, increased roughly proportionally and the sphincteric motoneuron increased its activity to about 1 Ap/sec in the occasional spike mode. Up to 600 ml, the motoneuron responded in the transient oscillatory mode with mean activities of up to 5 Ap's/sec. With higher bladder fillings, the flow receptors afferents fired additionally, probably according to pressure symptoms, and the motoneuron switched into the continuous oscillatory firing mode and increased its activity up to 18 Ap's/sec at 700 ml. When the bladder was about 800 ml full, the stretch afferent activity decreased, the flow receptor activity increased strongly and the alpha 2-motoneuron activity decreased; the overflow incontinence had probably started. Micturition was not observed, probably because of brain death. 4. It is suggested that one adequate stimulus for an alpha 2-motoneuron of the external anal sphincter to jump into the oscillatory firing mode, was the activity from secondary spindle afferent (SP2) fibres from external anal sphincter muscle spindles.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1990

Feeder arteries, longitudinal arterial trunks and arterial anastomoses of the lower human spinal cord.

1. To study the arterial blood supply of the lower human spinal cord dye was injected into the thickest feeder artery and dinner diameters were measured of the arteries to and in the thoraco-lumbar spinal cord territory. 2. The arterial thoraco-lumbar territory consisted mainly of a ventral (A. spinalis anterior) and 2 dorsolateral longitudinal trunks (Aa. spinalis posterolaterales) linked by 2 sacral anastomoses. These longitudinal trunks were from the spinal cord segment T8 to the conus medullaris comparably thick and were fed to more than 80% by the 2 thickest radicular-medullary arteries. 3. The thickest feeder artery (Artery of Adamkiewicz, A. spinalis magna) had on average an inner diameter of 0.7 mm, contributed according to flow calculations 68% of the blood and fed from the left ventral side, mostly at T10 or L1 levels. The second thickest feeder had an inner diameter of 0.5 mm, supplied 18% of the necessary blood and fed mostly from the left dorsal side at the L1 level. The third thickest feeder with an inner diameter of 0.4 mm, contributed 7% from the left dorsal side. 4. Since the cruciate sacral anastomoses are in 20% of the cases thin or not present, the thickest ventral feeder artery and thickest dorsal feeder artery should be saved in operations in this region. Also the longitudinal arterial trunks should be saved to secure a sufficient blood supply of the cord.

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