Initial mechanomyographical signals from twitching fibres of human skeletal muscle.

AIM: To elucidate the origin of characteristic low-frequency sound of contracting skeletal muscle, propagation properties of mechanical and electrical signals along twitching muscle were studied. METHODS: From voluntarily twitching muscle in human vastus medialis muscle, mechanical and electrical signals were simultaneously recorded through the skin with microphones and wire electrodes. RESULTS: The initial part of the mechanical signal recorded by the microphone showed transient pressure decrease (negative-going phase) followed by sustained pressure increase (positive-going phase). The mechanical signals obtained over the nerve insertion lacked the negative-going phase. The onset of the positive-going phase appeared 2.5 +/- 0.2 (mean +/- SEM, n = 7) ms behind the onset of spike potential independently of the sensor position. The onset of the negative-going phase propagated along the muscle at a constant velocity of 29.8 +/- 3.4 m s(-1), which was about ten times faster than the propagation velocity of action potentials (3.2 +/- 0.1 m s(-1)). Extrapolation analyses showed that the negative- and positive-going phases originated at the nerve insertion 2.1 +/- 0.3 and 1.6 +/- 0.1 ms behind the generation of muscle action potentials respectively. Local muscle compression blocked the propagation of only the negative-going phase. CONCLUSIONS: The negative-going mechanical signal represents a passive process, probably the thinning of the internally stretched segments of the twitching muscle. The positive-going phase, on the other hand, represents an active process, probably muscle thickening due to the internal shortening. Each phase, therefore, would convey information about the mechanical properties of resting and contracting muscle fibres respectively.

Effects of inorganic phosphate on cross-bridge behavior after photorelease of ATP in permeabilized cells of rat skeletal muscle.

Effects of 20 mM inorganic phosphate on the cross-bridge behavior after photorelease of ATP from caged ATP was studied by X-ray diffraction in rat skinned psoas muscle fibers at 16 degrees C. In the first 30 ms after the photorelease, tension was similar in the presence and absence of phosphate. The tension development was then suppressed in the presence of phosphate. At 500 ms after the photolysis, it was lower by about 30% in the presence of phosphate. In the presence of phosphate, the intensity of the third meridional reflection from the thick filament at 1/14.4 nm(-1) increased more slowly and was 60% of the level without phosphate at 500 ms after the photolysis. The intensities of the equatorial (1,1) reflection and the actin layer-line at 1/36 nm(-1) decreased to a lower level in the presence of phosphate. These results suggest that phosphate does not affect dissociation of myosin heads from actin, but decreases the number of myosin heads in force-generating conformation and reduces tension. Phosphate may also shift the equilibrium between the detached and attached states towards the former.

Hearing changes and questionnaire responses in patients with paramedian suboccipital vestibular neurectomy.

In order to determine the effectiveness of paramedian suboccipital transmeatal vestibular neurectomy, pre- and postoperative neurotological studies were conducted and questionnaire responses of 30 patients who underwent surgery were evaluated. Hearing was maintained within 10 dB of the preoperative level or improved in 54% of patients 2 years after surgery. Questionnaire responses indicated that all patients suffering from intractable vertigo experienced no vertiginous symptoms after surgery. Based on this study, we conclude that paramedian suboccipital transmeatal vestibular neurectomy is a useful method for relieving ear-related vertigo.

Clinical usefulness of glycerol vestibular-evoked myogenic potentials: preliminary report.

The detection of intense sound-induced vestibular-evoked myogenic potentials (VEMPs) on the sternocleidomastoid muscle comprises the basis of the saccular function test. In order to evaluate the endolymphatic hydrops (EH) of the saccule of the inner ear, a glycerol VEMP (GVEMP) test was performed in 15 patients with unilateral typical Ménière's disease (UMD) and 7 with delayed endolymphatic hydrops (DEH). Using the GVEMP test, 8 of the 15 patients (53%) with UMD were evaluated as being abnormal. In addition, a greater number of patients (67%) were judged to be abnormal when the results of the GVEMP test were combined with those from a glycerol dehydration test, trans-tympanic electrocochleography (ECochG) or furosemide vestibulo-ocular reflex test (FVOR). Four of the 7 patients with DEH (57%) showed abnormal results in the GVEMP test. In particular, in patients with the ipsilateral type of DEH, only the GVEMP test was able to detect the affected side. These findings suggest that the GVEMP test is a new and useful test for EH, and that a test battery comprising the GVEMP test together with one of the other three tests is useful for diagnosing EH of the inner ear.

Invertebrate connectin spans as much as 3.5 microm in the giant sarcomeres of crayfish claw muscle.

In crayfish claw closer muscle, the giant sarcomeres are 8.3 microm long at rest, four times longer than vertebrate striated muscle sarcomeres, and they are extensible up to 13 microm upon stretch. Invertebrate connectin (I-connectin) is an elastic protein which holds the A band at the center of the sarcomere. The entire sequence of crayfish I-connectin was predicted from cDNA sequences of 53 424 bp (17 352 residues; 1960 kDa). Crayfish I-connectin contains two novel 68- and 71-residue repeats, and also two PEVK domains and one kettin region. Kettin is a small isoform of I-connectin. Immunoblot tests using antibody to the 68-residue repeats revealed the presence of I-connectin also in long sarcomeres of insect leg muscle and barnacle ventral muscle. Immunofluorescence microscopy demonstrated that the two repeats, the long spacer and the two PEVK domains contribute to sarcomere extension. These regions rich in charged amino acids, occupying 63% of the crayfish I-connectin molecule, may allow a span of a 3.5 microm distance as a new class of composite spring.

Single turnover of cross-bridge ATPase in rat muscle fibers studied by photolysis of caged ATP.

A mechanical study on skinned rat psoas muscle fibers was performed at about 16 degrees C with X-ray diffraction and caged-ATP photolysis. The amount of photoreleased ATP was set < 0.2 mM for analysis of a 'single turnover' of the cross-bridge ATPase. With regard to the phase of activation, the results under the single turn-over condition were generally consistent with previous results obtained with larger amount of photoreleased ATP. Formation of the ADP-rigor state was mechanically monitored by the 90 degrees out-of-phase component of stiffness at 500 Hz, which was elevated on activation and then decreased to zero with a half-time of 0.2-0.3 s. Intensity changes of the X-ray reflections (e.g. equatorial reflections, actin layer lines and a myosin meridional reflection) indicated that a large number of cross-bridges returned to the rigor structure with a half-time of 0.5-0.7 s. During this phase, tension did not increase but slowly decreased with a half-time of about 1.0 s. The in-phase stiffness increased only 20-30% at the most. These results indicate that, even if the number of cross-bridges formed at any moment during full contraction is small, they can interact with actin and form rigor bonds with a rate of 1 s(-1). The force developed in the rigor formation is probably lost due to the presence of rigor bridges and compliance in the preparation.

New local hyperthermia using dextran magnetite complex (DM) for oral cavity: experimental study in normal hamster tongue.

The possibility of dextran magnetite complex (DM) as a new hyperthermic material was examined in this study. DM suspension of 56 mg ml(-1) iron concentration was locally injected into the normal tongue of golden hamster. DM injected tongues were heated by 500 kHz alternating current (AC) magnetic field and its serial changes in temperature were recorded at 30-s intervals. The temperature of DM injected tongue was maintained at about 43.0-45.0 degrees C for 30 min by changing the AC magnetic field intensity. While temperature elevations of the contralateral tongue and the rectum were only of minor degree. In experiment on the extent of heating area, there was correlation between volume of black stain area and amount of the injected DM suspension (Y = - 18.1 + 1.94X, r = 0.931, P < 0.0001, n = 9 ). Histological examination after heating revealed brown uniform DM accumulation in the connective tissue between fibers of the tongue muscle. Except for vascular dilatations, no tissue damage was seen in the heated tongue. Thus, DM which has the possibility of selective and uniform heating in local hyperthermia might be useful for oral cancer therapy.

[Speech perception ability in a patient with a 8-channel auditory brainstem implant].

Auditory brainstem implant (ABI) is a central prosthesis that directly stimulates the cochlear nucleus in the brainstem for those who have interrupted auditory nerves and cannot benefit from the cochlear implantation. Speech perception in a recipient of the Nuclues 8 channel ABI, the first in Japan, is reported. A 25-year-old man with bilateral acoustic nerve tumors postlingually deafened due to tumor resection received auditory sensations with 5 channels. The correct answer using a coding strategy, SPEAK, was 35% for 5 vowels and 36% for 5 monosyllables. The use of ABI also improved his lip-reading ability on monosyllables and open-set words. This indicated that he benefited from ABI, although it was limited. Even after 1 year and 3 months of follow-up, he had no serious side effects such an infection or implant rejection.

Activating efficiency of Ca2+ and cross-bridges as measured by phosphate analog release.

To assess the activating efficiency of Ca2+ and cross-bridges, the release rates of phosphate analogs from skinned fibers were estimated from the recovery of contractility and that of stiffness. Estimations were performed based on the assumptions that contractility was indicative of the population of analog-free myosin heads and that stiffness reflected the population of formed cross-bridges. Aluminofluoride (AlFx) and orthovanadate (Vi) were used as phosphate analogs with mechanically skinned fibers from rabbit psoas muscle. The use of the analogs enabled the functional assessment of activation level in the total absence of ATP. Fibers loaded with the analogs gradually recovered contractility and stiffness in normal plain rigor solution. The addition of Ca2+ to the plain rigor solution significantly accelerated their recovery, whereas ADP had no appreciable effect. ATP plus Ca2+(contracting condition) accelerated the recovery by several tens of times. These results indicate that the cross-bridges formed during contraction have prominent activating efficiency, which is indispensable to attain full activation. A comparison between the activating efficiency evaluated from stiffness and that from contractility suggested that Ca2+ is more potent in accelerating the binding of actin to analog-bound myosin heads whereas cross-bridges mainly accelerate the subsequent analog-releasing step.

Influence of height on the spatial orientation and equilibrium of the body.

The sway of the center of gravity for 30 seconds with a stabilometer was examined in 30 volunteers under 3 visual conditions (eyes open with and without fixation and eyes closed) at heights of 0, 1, and 2 m and under 2 visual conditions (eyes open with fixation and eyes closed) at a height of 10 m 22 cm. Eight of the subjects had acrophobia. The sway worsened at 10 m 22 cm but showed no change at 1 or 2 m. The acrophobic group became clearly worse at 10 m 22 cm. In another group of 12 volunteers, the subjects were guided to the roof with the eyes closed, and sway was measured. Sway was also measured with the eyes uncovered and open and again with the eyes closed. The first measurement with the eyes closed showed worse sway, and the second with the eyes open was better, except in 2 subjects who were acrophobic.

Tumor regression by inductive hyperthermia combined with hepatic embolization using dextran magnetite-incorporated microspheres in rats.

We formulated a novel preparation of microspheres incorporating dextran magnetite complex (DM-MS), which enable magnetic field-induced heating for the induction of hyperthermia. Using a 500 kHz magnetic field combined with arteriolar embolization of DM-MS, inductive hyperthermia was performed for the treatment of liver tumors in rats. Three days after treatment, the percentage increase of tumor volume in the embolo-hyperthermia, embolization alone, and control groups were 28%, 124%, and 385%, respectively, with the embolo-hyperthermia group differing significantly from the remaining groups. This study demonstrated the feasibility of combining embolization of DM-MS with hyperthermia as an antitumor therapy.

A pre-active attached state of myosin heads in rat skeletal muscles.

X-ray diffraction experiments were performed on rat soleus and psoas muscles using synchrotron radiation from a multipole wiggler. The X-ray diffraction patterns were recorded at a time resolution of 16.7 ms with an X-ray image intensifier and a CCD video camera. A bundle of 10-15 muscle fibres was activated by photorelease of 2.2 mM ATP from 7 mM caged-ATP at 15 degrees C. In soleus muscle fibres in the presence of 40 microns Ca2+, the tension developed with a half-time of 0.13 s. The intensities of the (1,1) equatorial reflection and the actin layer-lines at 1/36 nm-1 and 1/5.9 nm-1 decreased from their rigor values in the first 16.7 ms frame to a level higher than in the resting state, and then remained unchanged during the tension development. The intensity of the 14.5 nm meridional reflection increased as the tension developed. These results show that after the ATP release some myosin heads are stereospecifically attached to actin well before tension development, and suggest that their number does not change markedly on contraction.

A rare case of acoustic neuroma extending from the cerebellopontine angle to the external auditory canal.

A 57-year-old woman presented with tinnitus and complete hearing loss in her right ear and a mild right-sided facial palsy. She was found to have an atypical acoustic neuroma involving the internal auditory canal, labyrinth, and middle ear, extending into both the cerebellopontine angle and the external auditory canal. The tumour was completely removed as a two-stage surgical procedure. The underlying mechanism for the atypical extension is discussed.

Clinical results of treatment of advanced esophageal carcinoma with hyperthermia in combination with chemoradiotherapy.

Chemoradiotherapy combined with hyperthermia was administered to 35 patients with advanced esophageal carcinoma who either required preoperative treatment or had nonresectable disease. As a rule, each patient received a total dose of 30 Gy in 15 daily fractions of 2 Gy, 5 d/wk. Bleomycin or cisplatin, in combination with fluorouracil, was employed as chemotherapy. Hyperthermia was applied by intraluminal heating twice a week for a total of six sessions using an apparatus (IH-500T; Japan Crescent Co Ltd; Tokyo, Japan) (radiofrequency, 13.56 MHz) with an intraesophageal applicator and two extracorporeal applicators placed on the chest and back. This treatment method obtained a response rate of 80%, consisting of a complete response rate of 22.9% and partial response of 57.1%. In 15 cases, the tumor became resectable (resectability rate, 42.9%) following treatment. The histologic study of the resected specimens revealed absence of viable tumor cells in five patients (33.3% of the resected cases) (markedly effective), and in six patients (40.0%), the combined therapy was considered to be moderately effective. No complications considered due to hyperthermia itself were recognized. The overall 5-year survival rate was 11.8%. In conclusion, chemoradiotherapy combined with hyperthermia was locally effective, yielding an overall response of 80.0%. However, the prognosis of the patients remains unfavorable. Advanced esophageal carcinoma requires treatment taking into account lymphatic and hematogenic metastasis at the beginning of treatment.

[Effects of OK-432 intraportal administration on cell-mediated immune responses].

The effects of OK-432 and/or MMC on host immunity were studied in patients with advanced colorectal cancer. OK-432 was administered to the portal vein, and MMC was dispersed into the peritoneal cavity for prevention of liver metastasis. In the MMC group, NK activity was significantly reduced at 7 days postoperatively, while such a reduction was not seen in the OK and OK + MMC groups. The administration of OK-432 decreased the postoperative proportion of suppressor T cells in the lymphocyte subsets more than that of MMC group. Our results strongly suggest that intraoperative administration of BRM to the patients with advanced colorectal cancer can significantly prevent postoperative immunosuppression.

Mechanical study of rat soleus muscle using caged ATP and X-ray diffraction: high ADP affinity of slow cross-bridges.

1. The cross-bridges in slow- and fast-twitch fibres (taken, respectively, from soleus and psoas muscles of rats) were examined in mechanical experiments using caged ATP and X-ray diffraction, to compare their binding of ATP and ADP. 2. Caged ATP was photolysed in rigor fibres. When ADP was removed from pre-photolysis fibres, the initial relaxation (+/- Ca2+) in soleus was as fast as that in psoas fibres, whereas the subsequent contraction (+Ca2+) was slower in soleus than in psoas. The ATPase rate during the steady-state contraction was also slower in soleus fibres. 3. When ADP was added to pre-photolysis fibres (+/- Ca2+), tension developed even in the initial phase, the overall tension development being biphasic. Both initial and late components of the Ca(2+)-free contraction were enhanced when ADP was added before photolysis, although pre-photolysis ADP was not a prerequisite for the late component. The effect of ADP was greater in soleus than in psoas fibres. Static experiments on rigor fibres revealed a higher ADP affinity in soleus fibres. 4. The intensity of the actin layer-line from ADP rigor soleus fibres decreased rapidly on photorelease of ATP. We conclude that, despite the tight ADP binding of the soleus cross-bridge, its isometric reaction is not rate limited by the 'off' rate of ADP.

[Stimulating conditions of cold air caloric test].

This study is to clarify the effects of stimulating conditions on caloric response evoked by cold air stimulation. The five parameters of caloric nystagmus (latency, maximum slow phase velocity [Max. spv], Max. spv arrival time, frequency and duration) were examined. The different stimulating air temperature(0 degree C, 5 degrees C, 10 degrees C, 15 degrees C, 20 degrees C), flow rate (3.0, 4.0, 5.0, 6.0 l/m) and period(30, 45, 60, 90 sec) were used to evoke caloric nystagmus in normal subjects. 1. Effect to temperature When the intensity of air irrigation temperature increased, Max. spv, frequency and duration also tended to increase. Out of the five parameters, the duration of caloric nystagmus was the most relevant to the intensity of irrigation temperature. 2. Effect of stimulating period When the period of caloric stimuli increased, the Max. spv and its duration also increased. But, when the stimulating period was 90 seconds, the slow phase velocity reached to the maximum responses 60 seconds after starting the stimulation. Therefore, it is not necessary to stimulate for more than 60 seconds. 3. Caloric response evoked by 60 sec, 5.0 l/m at 5 degrees C air irrigation showed the same response as the caloric nystagmus provoked by 20 ml of water at 20 degrees C for 20 sec.

Compensation after sudden loss of unilateral vestibular function and optokinetic after-nystagmus.

UNLABELLED: After unilateral labyrinthectomy or vestibular neurectomy, optokinetic after-nystagmus (OKAN) to the ipsilateral side was abolished, then gradually recovered. We studied whether the compensation could be evaluated by observing OKAN. METHODS: Unilateral labyrinthectomy or vestibular neurectomy was performed under general anesthesia in cases of severe inner ear origin vertigo. Eye movements were recorded by electronystagmography (ENG), and the duration of OKAN was measured. RESULTS: The duration of OKAN to the ipsilateral side was shorter than that to the contralateral side (85%), the ipsilateral side was longer in 15% after labyrinthectomy. After vestibular neurectomy, the duration of OKAN to the ipsilateral side was shorter in 90%, and in 10% it became symmetrical. CONCLUSION: The stage of compensation after unilateral labyrinthectomy or vestibular neurectomy can be seen by measuring the duration of OKAN.

Differential effects of adrenocorticotropin in vivo on cytochromes P4502D16 and P450c17 in the guinea pig adrenal cortex.

Studies were performed to compare the effects of ACTH treatment in vivo on cytochromes P4502D16 and P450c17 in the guinea pig adrenal cortex. In untreated animals, CYP2D16 protein and messenger RNA (mRNA) expression as well as xenobiotic-metabolizing activities (bufuralol 1'-hydroxylase, benzphetamine N-demethylase, and benzo(a)pyrene hydroxylase) were far greater in the inner (zona reticularis) than the outer (zona fasciculata plus zona glomerulosa) zones of the cortex. ACTH treatment for 3 or 7 days significantly decreased the rates of xenobiotic metabolism in both the inner and outer adrenal zones. Western and Northern blot analyses revealed that adrenal CYP2D16 protein and mRNA concentrations were significantly decreased by ACTH. In contrast to its inhibitory effects on CYP2D16, ACTH treatment increased steroid 17 alpha-hydroxylase activity in the adrenal inner zone, but did not affect outer zone activity. Microsomal CYP17 protein concentrations were not affected by ACTH despite increases in CYP17 mRNA levels in both zones. The results indicate that ACTH causes down-regulation of adrenal CYP2D16, probably at the transcriptional level. Thus, modulation of CYP2D16 by ACTH is opposite that for the steroidogenic P450 isozymes, suggesting unique regulatory mechanisms. In addition, the data suggest that posttranscriptional mechanisms contribute to ACTH regulation of 17 alpha-hydroxylase activity in the guinea pig adrenal cortex.