Reduced-dose rocuronium for day-case tonsillectomy in children where volatile anaesthetics are not used: operating room time saving

Objectives: Mivacurium, rocuronium, and vecuronium are neuromuscular blocking agents (NMB) commonly used in pediatric day‐case anesthesia. Mivacurium is the most appropriate NMB for short surgical procedures where NMB drugs were required but is not available in all countries. Aim: We evaluated the operating room time minimization after reduced‐dose rocuronium (0.45 mg·kg^?1) during elective day‐case tonsillectomy in children. Methods/Materials: One hundred and five children (6–9 years, ASA I/II status) scheduled for day‐case tonsillectomy were included in prospective, double blind clinical study. Children were randomly divided in three equal groups. All children were premedicated (midazolam 0.25 mg·kg^?1 orally, EMLA). Anesthesia was induced (2.5 mg·kg^?1) and maintained (0.1 mg·kg^?1·min^?2) by propofol and alfentanil (0.0015 mg·kg^?1·min^?1) and supplemented by inhalation mixture of 50% of O2/Air. Neuromuscular block was achieved by vecuronium (0.1 mg·kg^?1) (V) or rocuronium in standard (0.6 mg·kg^?1) (R) or reduced dose (0.45 mg·kg^?1) (LD). Neuromuscular transmission was monitored by acceleromyography. Time analysis of NMB drugs action was performed. Results: Time difference from the end of tonsillectomy to T90 neuromuscular block recovery was significantly shorter in LD Group (7.3 ± 0.41 min), (V = 15.9 ± 1.06, R = 16.0 ± 1.7 min) (P = 0.0011). The onset time of neuromuscular block was prolonged in LD Group (LD=3.1 ± 0.4, R = 1.3 ± 0.4, V = 2.2 ± 0.2 min) (P = 0.0039) without changing the intubating conditions. The maximum operation room time saving per each tonsillectomy was 37% in LD Group (Group V 21%, Group R 17%) (P = 0.0001). Low incidence of postoperative nausea and vomiting (PONV) 3–6% (0.4577) and good visual analog scale (VAS) score (≤2) (0.5969) were found in all study groups 12 h after surgery. Conclusions: Reduced‐dose rocuronium in addition with propofol and alfentanil in children where volatile anesthetics are not used effectively saves the operating room time during short elective surgical procedures, avoids delays in patient recovery, allows high level of acceptable intubating conditions, and improves the optimal surgical work. Low incidences of PONV as VAS score may achieved successfully.     

Refractoriness of neuromuscular transmission: determination by computer subtraction of neurally evoked compound electromyograms

Shortly after elicitation of a muscle response by supramaximal stimulation of its motor nerve, there exists a period of refractoriness of neuromuscular transmission when a second stimulation elicits only a submaximal response or no response at all. Many anaesthetics and neuromuscular blocking and facilitatory drugs change the refractoriness of neuromuscular transmission. Measurement of this refractoriness may improve our understanding of the neuromuscular actions of these drugs and be useful in differential diagnosis. However, the neuromuscular refractory periods (RP) are difficult to measure, and the unavailability of normal values renders accurate determination of drug effects impossible. Based on an existing technique of digitization and time expansion of the neurally evoked compound electromyogram (ncEMG), we developed a computer programme of waveform subtraction, and determined in nine normal awake volunteers the various interstimulus intervals when neuromuscular transmission was refractory (RP₀), 3/4 refractory (RP_.25). half refractory (RP_.5), 1/4 refractory (RP_.75) or non-refractory (RP₁). We confirmed our hypotheses that computer-based waveform subtraction of the digitized ncEMG is a feasible and necessary technique for the accurate determination of the RPs of neuromuscular transmission, and report that the normal values in humans are: RP₀ = 1.0 ± 0.1, RP_.25 = 1.3 ± 0.3, RP_.5 = 1.9 ± 0.3, RP_.75 = 2.9 ± 0.5, and RP₁ = 6.6 ± 1.9 ms (mean ± SD), respectively, in the ulnar nerve-first dorsal interosseous muscle model.     

Duration of action of an equipotent dose of vecuronium in infants and in children

During general anaesthesia without any volatile anaesthetic agents, ten infants and ten children received incremental doses of vecuronium to achieve a 95% neuromuscular block. Thereafter, the thenar electromyographic response was allowed to recover spontaneously. Total dose of vecuronium to establish a 95.0 ± 0.5% (mean ± SEM) neuromuscular block was 66% greater for children than for infants (73 ± 4 vs. 44 ± 4 μg·kg^?1, P < 0.0001). However, recovery index and time to complete recovery of the neuromuscular function were 88 and 89% longer, respectively, in infants than in children (P < 0.0001). These results of the effect of an equipotent dose of vecuronium in infants and in children confirm that vecuronium is a long acting neuromuscular blocking agent in infants.     

Onset of vecuronium-induced neuromuscular block after a long priming interval

Purpose. We examined whether a new application of the priming principle, i.e., having the priming dose of vecuronium administered before the insertion of the epidural catheter, would hasten the onset of the neuromuscular block induced by the intubating dose of vecuronium. Methods. Forty-five adult female patients scheduled for general anesthesia combined with epidural anesthesia were studied. In group A (n = 15), the priming dose of vecuronium, 0.01 mg·kg⁻¹, was administered before insertion of the epidural catheter. The intubating dose of vecuronium, 0.09 mg·kg⁻¹, was given after the insertion of the epidural catheter. In group B (n = 15), the priming dose of vecuronium, 0.01 mg·kg⁻¹, was given 4 min before the intubating dose of vecuronium, 0.09 mg·kg⁻¹. In the control group (n = 15), no priming dose was given, and only the intubating dose of vecuronium, 0.10 mg·kg⁻¹, was administered. In all three groups, general anesthesia was induced with propofol 2.5 mg·kg⁻¹, and the trachea was intubated when T1/control value (control twitch height in response to train-of-four stimuli) was less than 0.1. Results. In group A, the priming dose was given 16 ± 3 min (mean ± SD) before the administration of the intubating dose. The times to onset of neuromuscular block in groups A and B, and the control group were: 145 ± 30, 184 ± 45, and 219 ± 23 s, respectively (P < 0.05 among the three groups). In all three groups, intubating conditions (graded on a four-point scale) were excellent (P = 0.59). Before the induction of anesthesia, symptoms of paralysis were observed in 5, 4, and 0 patients in groups A and B and the control group, respectively (P < 0.05 between group A or B vs control group). Conclusions. If the priming dose of vecuronium is given after a long priming interval (16 ± 3 min), the time to onset of the neuromuscular block caused by the intubating dose of vecuronium is markedly shorter than when the conventional priming interval of 4 min is employed. Received: March 5, 2001 / Accepted: October 4, 2001     

Neuromuscular function and transmission

Understanding the biological processes and mechanisms underlying neuromuscular function in anaesthetized or sedated patients depends on adequate knowledge of the anatomy, physiology, and pathology of the connections between motor neurons and muscle fibres at neuromuscular junctions. Neuromuscular synaptic integrity depends on: maintenance of Ca²⁺-dependent release of acetylcholine by exocytosis from synaptic vesicles that fuse with active zones in motor nerve terminal membranes; the subsequent depolarizing action of acetylcholine on postsynaptic receptors at motor endplates; and termination of neuromuscular transmission by enzymic action of acetylcholinesterase located in the synaptic basal lamina. Homeostatic mechanisms sustain the magnitude of endplate potentials and the safety factor for neuromuscular transmission; but dysfunction of neuromuscular junctions occurs following administration of neuromuscular blockers or in diseases and other conditions affecting release, action and inactivation of acetylcholine.     

Neuromuscular effects of 600 μg·kg−1 of rocuronium in infants during nitrous oxide-halothane anaesthesia

Rocuronium bromide (Zemuron) is a new steroidal nondepolarizing neuromuscular blocking drug. We were interested in determining the effect of a bolus of rocuronium in infants during halothane anaesthesia as we did previously in older children. Eighteen infants (2-11 months) received a bolus of 600 μg·kg^?1, which is equal to twice the dose of rocuronium estimated to produce 95% depression of neuromuscular function (ED₉₅) in children (2-12 yr). Neuromuscular blockade was monitored by recording the electromyographic activity of the adductor pollicis muscle resulting from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10-s intervals. Time (mean ± SEM, range) from administration of 600 μg·kg^?1 rocuronium to 90% (B₉₀) and 100% (B₁₀₀) neuromuscular block was 37 ± 2 (20-60) s and 64 ± 10 (20-180) s, respectively. The time to recovery of neuromuscular transmission to 10% (T₁₀) was 35.3 ± 3.0 (20.7-57.8) min and to 25% of baseline (T₂₅) was 41.9 ± 3.2 (24.3-67.7) min. The recovery index (T₂₅-T₇₅) was 26.6 ± 2.7 (11.7-44.5) min, and the time to recovery of the train-of-four ratio (T₄/T₁) ± 0.75 was 82.1 ± 6.9 (53.2-138.3) min. The plasma concentration of rocuronium when T₁ had recovered to about 30% was 654 ± 34 (417-852) ng·ml^?1 which is similar to that observed in children. Six-hundred μg·kg^?1 of rocuronium has a rapid onset of effect in infants and prolonged duration of action in infants compared to children.     

Evaluation of twitch responses obtained from abductor hallucis muscle as a monitor of neuromuscular blockade: Comparison with the results from adductor pollicis muscle

The twitch responses evoked from the abductor hallucis muscle (AHM) and the adductor pollicis muscle (APM) were examined simultaneously in 20 anesthetized patients following a single bolus intravenous administration of 0.04 mg·kg⁻¹ of vecuronium bromide. The mean onset time of vecuronium-induced depression of AHM twitch responses was significantly slower than that of APM twitch responses (4.9±1.5 minvs 3.7±1.2 min, mean±SD,P<0.001), and when the clinical duration times of vecuronium were compared, AHM twitch responses recovered more quickly than APM twitch responses (15.3±4.1 minvs 19.6±6.7 min,P<0.01), although there was no statistically significant difference in the spontaneous recovery time between AHM and APM (9.8±2.9 minvs 10.0±3.6 min). It is concluded that the twitch responses of AHM may be a useful monitor of neuromuscular blockade in anesthetized patients in whom setting the blockade monitor on the patient's arms is difficult, although monitoring of twitch response of AHM is less sensitive than that of APM in case of vecuronium administration.     

Monitoring of skeletal muscle oxygenation using near-infrared spectroscopy during abdominal aortic surgery

Purpose. To examine the utility of near-infrared spectroscopy (NIRS) in assessing lower-leg perfusion, NIRS was performed on the calf muscles of patients who underwent abdominal aortic surgery. Methods. Thirty patients undergoing elective infrarenal abdominal aortic surgery for abdominal aortic aneurysm (AAA group; n = 16) and aorto-occlusive disease (AOD group; n = 14) were studied. Before induction of anesthesia, NIRS probes were placed over both calf muscles, and muscle oxygen saturation (S_tO2) was continuously monitored throughout the surgery. Results. The preoperative S_tO2 value was significantly lower in the AOD group (57.0 ± 11.2%) than in the AAA group (68.7 ± 7.0%). In both groups, S_tO2 significantly decreased after aortic cross-clamping; the maximal ischemic value of S_tO2 in the AAA group (17.8 ± 7.2%) was significantly lower than that in the AOD group (46.7 ± 17.1%). The time taken to reach maximal ischemia was significantly longer in the AAA group (30 ± 12 min) than in the AOD group (19 ± 12 min). After release of the aortic clamp, the decreased S_tO2 returned to the preoperative level in the AAA group, whereas it increased above the preoperative value in the AOD group. Conclusion. NIRS performed on the calf muscles is a useful method for assessing the changes in lower-leg perfusion during and after abdominal aortic surgery. Received: June 6, 2001 / Accepted: December 5, 2001     

Recovery of neuromuscular blockade caused by vecuronium is delayed in patients with hypertriglyceridemia

We investigated the effects of hypertriglyceridemia on the onset and recovery of neuromuscular blockade, induced by vecuronium, over the adductor pollicis muscle, electromyographically. Eighteen adult patients with hypertriglyceridemia (hypertriglyceridemia group) and 18 healthy patients with normal serum triglyceride (control group) were studied. The supramaximal stimulating current for train-of-four (TOF) in the hypertriglyceridemia group was significantly higher than that in the control group (45.7 ± 16.7 vs 31.5 ± 9.8 mA; mean ± SD; P = 0.004). The onset of vecuronium 0.1 mg·kg⁻¹-induced neuromuscular blockade in the hypertriglyceridemia group did not significantly differ from that in the control group (240 ± 60 vs 279 ± 88 s; P = 0.132). Times from vecuronium to the return of T1, T2, T3, and T4 in the hypertriglyceridemia group were significantly longer than those in the control group (31.4 ± 6.2 vs 25.5 ± 6.2 min for T1; P = 0.008). During recovery from neuromuscular blockade, T1/control did not differ between the two groups. However, the TOF ratios (T4/T1) in the hypertriglyceridemia group were significantly lower than those in the control group 80–120 min after vecuronium (P < 0.05). We conclude that, in patients with hypertriglycemidemia, a higher current is needed to elicit supramaximal response of the adductor pollicis muscle, and recovery from vecuronium-induced neuromuscular blockade is delayed.     

Sex‐related differences in neuromuscular control: Implications for injury mechanisms or healthy stabilisation strategies?

Sex‐related differences in neuromuscular activation have been previously identified and are thought to be an underlying contributor to the ACL injury mechanism. During dynamic tasks evaluating the role of muscle action as it relates to joint stability is difficult since individual muscle contributions to force generation are confounded by biomechanical factors of movement. The purpose of this study was to examine sex‐related differences in knee muscle action during a weight‐bearing isometric exercise and identify the stabilising role of these muscles. Healthy young adults stood with their dominant leg in a boot fixed to a force platform. A force matching protocol required participants to modulate normalised ground reaction forces in various combinations of anterior‐posterior, medial‐lateral loads while maintaining a constant joint position. Normalised electromyographic data of eight muscles crossing the knee joint were displayed in polar plots. Patterns were quantified with an orientation analysis and mean activation magnitudes were computed. Females demonstrated symmetrical activation patterns with significantly greater activation in the rectus femoris (p = 0.037), lateral gastrocnemius (p = 0.012), and tensor fascia lata (p = 0.005) compared to males. High between‐subject reliability (ICC = 0.772–0.977) was observed across groups suggesting we have identified fundamental sex‐related differences in knee joint stabilisation strategies. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:310–317, 2014.     

Use of ultrasonography to evaluate muscle thickness and blood flow in free flaps

The purpose of this study was to investigate the common belief that a microvascular transfer of a non-innervated free muscle flap loses muscle bulk over time. Sixteen patients (latissimus dorsi = 8, rectus abdominis = 7, and gracilis muscle = 1) were evaluated an average of 41 months after free flap transfer. Latissimus dorsi and lower extremity flaps displayed significantly more swelling than the other flaps. Flap bulk was measured by ultrasound. The mean thickness of upper extremity flaps was 10.3 ± 1.8 mm (control muscles 11.8 ± 2.8), lower-extremity 14.5 ± 3.7 mm (control muscles 10.9 ± 0.7), latissimus dorsi 14.3 ± 2.2 mm (control muscles 10.3 ± 0.8, P = 0.018), and rectus abdominis 11.2 ± 1.2 mm (control muscles 12.4 ± 1.9). Color Doppler ultrasonography was used to detect the pedicles of the free flaps and also to measure the peak velocity of blood flow intramuscularly and in the pedicles. In the upper extremities (n = 5) the pedicles could be found in only 20% of cases whereas in the lower extremities (n = 11) 91% of pedicles were located. (P = 0.013). Peak flow within the free flaps was significantly higher in the lower extremity (50% of the peak flow of the common femoral artery) than in the upper extremity (5% of the peak flow of the common femoral artery, P = 0.013). This study demonstrated that non-innervated free muscle flaps in the extremities maintain the original muscle thickness, although lower extremity and latissimus dorsi flaps have a trend to be thicker. Most pedicles of free muscle flaps in the upper extremities could not be located by ultrasound. However, flaps in the lower extremities most often have patent pedicles and also more vigorous intramuscular blood flow. © 1995 Wiley-Liss, Inc.     

Comparison of respiratory sparing effect between pancuronium and three new nondepolarizing muscle relaxants in rats

Purpose There is a large difference in sensitivity between respiratory muscles and other limb muscles. This phenomenon, known as the respiratory sparing effect (RSE), is well established withd-tubocurarine, pancuronium, and succinylcholine. The purpose of this study is to evaluate the RSE of these new relaxants, vecuronium, pipecuronium, and ORG9426. Methods The study was done in vivo using rats. Mechanical twitch responses of tibialis anterior muscle and diaphragm stimulated with the sciatic nerve and phrenic nerve, respectively, were recorded simultaneously to monitor neuromuscular transmission. Changes of mechanical twitch responses from both muscles were compared following the injection of four kinds of muscle relaxants (pancuronium, picuronium, recuronium, and ORG9426). Results T, D (%) represents the maximum depression in tibialis anterior and diaphragm, respectively. T−D (%), which means the sensitivity difference between the two kinds of muscle, was calculated by subtracting D from T. The T−Ds of pancuronium, pipecuronium, vecuronium, and ORG9426 were 86.0±2.6%, 81.4±1.9%, 77.7±2.1%, and 74.6±2.7%, respectively. Conclusions The results indicated that the blockade produced by each muscle relaxant was lower in the diaphragm than in the anterior tibialis muscle. T−D was significantly smaller with vecuronium or ORG9426 than with pancuronium.     

Bridging a 30 mm defect in the canine ulnar nerve using vessel‐containing conduits with implantation of bone marrow stromal cells

Previously, we showed that undifferentiated bone marrow stromal cell (uBMSC) implantation and vessel insertion into a nerve conduit facilitated peripheral nerve regeneration in a rodent model. In this study, we investigated the efficacy of the uBMSC‐laden vessel‐containing conduit in repair of segmental nerve defects, using a canine model. Eight beagle dogs were used in this study. Thirty‐millimeter ulnar nerve defects were repaired with the conduits (right forelimbs, n = 8) or autografts (left forelimbs, n = 7). In the conduit group, the ulnar artery was inserted into the l‐lactide/ε‐caprolactone tube, which was filled with autologous uBMSCs obtained from the ilium. In the autograft group, the reversed nerve segments were sutured in situ. At 8 weeks, one dog with only nerve repair with the conduit was sacrificed and the regenerated nerve in the conduit underwent immunohistochemistry for investigation of the differentiation capability of the implanted uBMSCs. In the remaining seven dogs, the repaired nerves underwent electrophysiological examination at 12 and 24 weeks and morphometric measurements at 24 weeks. The wet weight of hypothenar muscles was measured at 24 weeks. At 8 weeks, almost 35% of the implanted uBMSCs expressed glial markers. At 12 weeks, amplitude (0.4 ± 0.4mV) and conduction velocity (18.9 ± 14.3m/s) were significantly lower in the conduit group than in the autograft group (3.2 ± 2.5 mV, 34.9 ± 12.1 m/s, P < 0.05). Although the nerve regeneration in the conduit group was inferior when compared with the autograft group at 24 weeks, there were no significant differences between both groups, regarding amplitude (10.9 ± 7.3 vs. 25.3 ± 20.1 mV; P = 0.11), conduction velocity (23.5 ± 8.7 vs 31.6 ± 20.0m/s; P = 0.35), myelinated axon number (7032 ± 4188 vs 7165 ± 1814; P = 0.94), diameter (1.73 ± 0.31 vs 2.09 ± 0.39μm; P = 0.09), or muscle weight (1.02 ± 0.40 vs 1.19 ± 0.26g; P = 0.36). In conclusion, this study showed that vessel‐containing tubes with uBMSC implantation may be an option for treatment of peripheral nerve injuries. However, further investigations are needed. © 2015 Wiley Periodicals, Inc. Microsurgery 36:316–324, 2016.     

Neuromuscular effects of rocuronium in children during halothane anaesthesia

Rocuronium bromide, a nondepolarizing muscle relaxant has been shown to have a short onset and intermediate duration of action in adults and young children. We evaluated onset time, intubating conditions, as well as duration of action of rocuronium in children ages four to 12 years during nitrous oxide-halothane anaesthesia. Following a stable recording of train-of-four (TOF) impulses at the ulnar nerve, patients were given rocuronium 600 μg˙kg^?1 intravenously. We found that the time to 90% and 100% neuromuscular (N-M) block of the (TOF) was 51 ± 18 s and 66 ± 32 s respectively. Intubation was achieved at 94 ± 31 s and rated as good or excellent in all cases. Time to recovery of N-M transmission to 25%, 75% and 90% of control was 29 ± 8 min, 42 ± 14 min and 46 ± 16 min respectively. Heart rate increased ～12 BPM after drug injection, while the blood pressure remained unchanged. From our data we conclude that, as in other age groups, rocuronium has a rapid onset, intermediate duration of action in children 4–12 years of age, and appears devoid of significant side effects.     

Monitoring of vecuronium-induced neuromuscular block at the sternocleidomastoid muscle in anesthetized patients

Purpose

To assess the degree of neuromuscular block acceleromyographically at the sternocleidomastoid muscle.

Methods

Eighteen adult patients scheduled for air–oxygen–sevoflurane–fentanyl and epidural anesthesia were studied. In the patients, the right accessory nerve and the sternocleidomastoid muscle were stimulated and the contraction of the sternocleidomastoid muscle was evaluated acceleromyographically. Simultaneously, the response of the adductor pollicis muscle was measured electromyographically. Supramaximal stimulating current, degree of maximum neuromuscular block after vecuronium 0.1 mg/kg, and onset of or recovery from vecuronium-induced neuromuscular block were compared between the two muscles.

Results

The supramaximal stimulating current at the sternocleidomastoid muscle was significantly higher than that at the adductor pollicis muscle (54.8 ± 7.1 vs. 33.7 ± 10.3 mA, mean ± SD, P < 0.001). The onset of neuromuscular block at the sternocleidomastoid muscle did not significantly differ from that at the adductor pollicis muscle (214 ± 117 vs. 161 ± 87 s, P = 0.131). The degree of maximum neuromuscular block at the sternocleidomastoid muscle was significantly less than that at the adductor pollicis muscle (93.6 ± 3.1 vs. 99.2 ± 2.5%, P < 0.001). During recovery from neuromuscular block, T1/control and train-of-four ratio measured at the sternocleidomastoid muscle were significantly higher than those at the adductor pollicis muscle 10–30 and 40–120 min after vecuronium, respectively (P < 0.05).

Conclusion

The sternocleidomastoid muscle is more resistant to vecuronium than the adductor pollicis muscle. Recovery from neuromuscular block is faster at the sternocleidomastoid muscle than at the adductor pollicis muscle.     

Pancuronium dose-response revisited

We were interested in determining the cumulative dose-response relationship of pancuronium in infants and children during nitrous oxide–halothane anaesthesia. Neuromuscular blockade was monitored by recording the electromyographic activity of the adductor pollicis muscle from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10 s intervals. Forty patients were divided into four equal groups according to age: 3–6 months, 7–12 months, 13–47 months and 48–83 months. The effective dose, ED₅₀ (mean ± SEM), of pancuronium in these age groups was 24 ± 2, 30 ± 2, 34 ± 3, 29 ± 2 μgμkg^-1, respectively; the ED₉₅ (mean ± SEM) was 45 ± 2, 52 ± 3, 62 ± 6, 62 ± 4 μgμkg^-1, respectively. The ED₉₅ of pancuronium was significantly less (P < 0.05) for infants from 3 to 6 months of age than for children from 13 to 83 months of age. Infants thus appear to be more sensitive than children to the neuromuscular blocking effects of pancuronium during halothane anaesthesia.     

Attenuation of the process of muscle regeneration in the toad gastrocnemius muscle by low energy laser irradiation

The effect of number, frequency, and timing of HeNe (6.0 mW; 31.2J/cm²) and Ga-As-diode (average power at 2.82 Hz-0.005 mW) laser irradiations on the process of muscle regeneration at 14 days following cold injury to the toad gastrocnemius muscle was investigated using histomorphometric methods. The volume fraction (percent of total injured area) of mononucleated cells, myotubes and degenerated fibers was 10 ± 1%, 0%, and 4 ± 1%, respectively, in the HeNe laser irradiated muscles (5 irradiations every alternate day, beginning on the 4th day after injury), whereas in the control nonirradiated muscles, these values were significantly higher comprising 57 ± 2% (P < 0.01), 11 ± 1% and 10 ± 2% (P < 0.05), respectively. The volume fraction of young myofibers in injured areas that were subjected to the same laser irradiation regime was 8.6-fold significantly higher (P < 0.01) than their volume fraction in control muscles. The histomorphometric results were the same for injured zones of muscles that were laser irradiated only once, on the 9th day postinjury, and for those that received five consecutive irradiations every alternate day. Muscle regeneration was equally promoted by single Ga-As-diode laser or HeNe irradiation. Multiple irradiations of Ga-As-diode laser caused some pathological changes in the newly formed muscular structures. It is concluded that the process of skeletal muscle regeneration is markedly promoted by low energy laser irradiations, but that the effect depends on the number, timing, and frequency of irradiations and the type of laser used. © 1994 Wiley-Liss, inc.     

The effects of nandrolone decanoate on bone mass and metabolism in ovariectomized rats with osteopenia

The effects of nandrolone decanoate (ND) treatment on bone mass and metabolism were studied in ovariectomized (OVX) rats with osteopenia. The 6-month-old rats were divided into Sham (n = 12) and OVX (n = 24). The OVX rats were allowed to lose bone for 6 weeks. At 6 weeks post ovariectomy, the OVX rats were divided into two groups: (1) OVX + Vehicle and (2) OVX + ND. The effects of ND on bone mineral density (BMD), bone mineral content (BMC), and bone metabolism were studied by dual-energy X-ray absorptiometry (DXA) and biochemical markers including urinary pyridinoline (Pyr), deoxypyridinoline (Dpyr), and serum osteocalcin. After 24 weeks of treatment, histomorphometry of the right tibiae and the wet weight of the gastrocnemius and soleus skeletal muscles were also examined. Ovariectomy resulted in a significant increase in biochemical markers and a significant decrease in spine BMD (0.221 ± 0.016 g/cm² in OVX group vs 0.239 ± 0.008 g/cm² in Sham group) and BMC (0.550 ± 0.055 g in OVX group vs 0.605 ± 0.042 g in Sham group) at 6 weeks post ovariectomy. Spine BMD (0.227 ± 0.017 g/cm²), femoral BMD (0.263 ± 0.012 g/cm²), and bone density of femur (1.035 ± 0.036 g/cm³) in the OVX + ND group were significantly greater than those in the OVX + Vehicle group (0.204 ± 0.013 g/cm² for spine BMD, 0.243 ± 0.009 g/cm² for femoral BMD, 0.938 ± 0.06 g/cm³ for bone density of femur) after 24 weeks of treatment. ND treatment decreased urinary Pyr and Dpyr significantly in OVX rats. Histomorphometric findings indicated that ND-treated rats had greater cancellous bone volume, greater trabecular number, greater trabecular thickness, and less trabecular separation than vehicle-treated OVX rats. OVX rats had greater wet weight of the gastrocnemius and soleus muscles than rats treated with ND. The data suggest that the effect of ND on bone mass is not influenced by the condition of the muscles in OVX rats. Our findings indicate that ND blocks further bone loss by inhibition of bone resorption in OVX rats with osteopenia. Received: August 25, 1999 / Accepted: January 28, 2000     

Muscle fibre types of the lumbrical,interossei, flexor,and extensor muscles moving the index finger

Abstract

The aim of this study was to determine the fibre types of the muscles moving the index fingers in humans. Fifteen forearms of eight adult cadavers were used. The sampled muscles were the first lumbrical (LM), first volar interosseous (VI), first dorsal interosseus (DI), second flexor digitorum profundus (FDP), second flexor digitorum superficialis (FDS), and extensor digitorum (ED). Six micrometer thick sections were stained for fast muscle fibres. The procedure was performed by applying mouse monoclonal anti-skeletal myosin antibody (fast) and avidin-biotin peroxidase complex staining. Rectangular areas (0.38 mm × 0.38 mm) were photographed and the boundaries of the muscle areas were marked on the translucent film. The numbers and sizes of the muscle fibres in each part were evaluated by the image analyser program and calculated per unit area (1 mm²). The proportion of the fast fibres was significantly (p = 0.012) greater in the intrinsic muscles (55.7 ± 17.1%) than in the extrinsic muscles (45.9 ± 17.1%). Among the six muscles, the VI had a significantly higher portion (59.3%) of fast fibres than the FDS (40.6%) (p = 0.005) or the FDP (45.1%) (p = 0.023). The density of the non-fast fibres was significantly (p = 0.015) greater in the extrinsic muscles (539.2 ± 336.8/mm²) than in the intrinsic muscles (383.4 ± 230.4/mm²). Since the non-fast fibres represent less fatigable fibres, it is thought that the extrinsic muscles have higher durability against fatigue, and the intrinsic muscles, including the LM, should move faster than the FDS or FDP because the MP joint should be flexed before the IP joint to grip an object.     

Rocuronium in infants, children and adults during balanced anaesthesia

We studied 20 infants, 20 children and 20 adults during balanced anaesthesia to compare the neuromuscular blocking effects of rocuronium in these age groups. Neuromuscular function was recorded by adductor pollicis emg and a cumulative log-probit dose-response curve of rocuronium was established. Thereafter, full spontaneous recovery of the neuromuscular function was recorded. Onset time of the first dose of rocuronium was shorter in children than in infants or adults. The potency of rocuronium was greatest in infants and least in children; the ED₅₀ doses (mean ± SD) being 149 ± 36 μg˙kg^?1 in infants, 205 ± 52 μg˙kg^?1 in children and 169 ± 47 μg˙kg^?1 in adults (P<0.05 between infants and children) and the ED₉₅ doses being 251 ± 73 μg˙kg^?1, 409 ± 71 μg˙kg^?1 and 350 ± 77 μg˙kg^?1, respectively (P<0.05 between all groups). The emg recovery following an average 94.5 ± 4.8% neuromuscular blockade established by rocuronium was roughly similar in all study groups. Thus, one ED₉₅ dose of rocuronium, unlike vecuronium, acts as an intermediate-acting agent in all age groups.