Fibre-type composition of rabbit jaw muscles is related to their daily activity

Skeletal muscles contain a mixture of fibres with different contractile properties, such as maximum force, contraction velocity and fatigability. Muscles adapt to altered functional demands, for example, by changing their fibre-type composition. This fibre-type composition can be changed by the frequency, duration and presumably the intensity of activation. The aim of this study was to analyse the relationship between the spontaneous daily muscle activation and fibre-type composition in rabbit jaw muscles. Using radio-telemetry combined with electromyography, the daily activity of five jaw muscles was characterized in terms of the total duration of muscle activity (duty time) and the number of activity bursts. Fibre-type composition of the muscles was classified by analysing the myosin heavy chain content of the fibres. The amount of slow-type fibres was positively correlated to the duty time and the number of bursts only for activations exceeding 20-30% of the maximum activity per day. Furthermore, cross-sectional areas of the slow-type fibres were positively correlated to the duty time for activations exceeding 30% of the maximum activity. The present data indicate that the amount of activation above a threshold (> 30% peak activity) is important for determining the fibre-type composition and cross-sectional area of slow-type fibres of a muscle. Activation above this threshold occurred only around 2% of the time in the jaw muscles, suggesting that contractile properties of muscle fibres are maintained by a relatively small number of powerful contractions per day.     

Distortions of respiratory parameters during muscular work in investigations using masks

Bulletin of Experimental Biology and Medicine -     

生命信息检测与监测技术

在医疗实践中通常通过检/监测心跳、呼吸、血压、体温等基本的生命体征参数来确定生命信息的有无。本文以军事卫勤理论为依托,探讨了在军事医疗实践中应用的生命信息检/监测技术。随着科技的进步和我军信息化进程的加快,以军事医学、传感器技术、微电子技术、可穿戴技术、通讯技术等为基础的生命信息检/监测技术将在信息化卫生装备中发挥越来越重要的作用。     

Antihypertensive Mechanism of Orally Administered Acetylcholine in Spontaneously Hypertensive Rats

Acetylcholine (ACh) acts as a neurotransmitter and neuromodulator. A small dose of eggplant powder rich in ACh (equivalent to 22 g fresh eggplant/d) has been shown to reduce blood pressure (BP) in individuals with higher BP. Here, we investigated the mechanisms underlying the antihypertensive effects of low-dose orally administered ACh in spontaneously hypertensive rats (SHRs). The effects of ACh on BP and sympathetic nervous activity (SNA), including lumbar SNA (LSNA) and renal SNA (RSNA), were evaluated by subjecting conscious SHRs to a telemetry method. Single oral administration of ACh decreased LSNA and lowered BP. Repeated oral administration of ACh for 30 d decreased RSNA and suppressed the elevated BP. Noradrenaline levels in the urine also decreased. However, vagotomy and co-administration of M3 muscarinic ACh receptor antagonist reversed the BP-lowering effect; the dynamics of non-absorbable orally administered ACh was revealed using stable isotope-labeled ACh. In conclusion, ACh acts on the gastrointestinal M3 muscarinic ACh receptor to increase afferent vagal nerve activity, which decreases SNA by autonomic reflex, suppressing noradrenaline release and lowering BP. This study suggests the use of exogenous ACh as an antihypertensive food supplement for controlling the autonomic nervous system, without absorption into the blood.     

Urinary incontinence detection in elderly inpatient men

Urinary incontinence is a serious medical and social problem affecting approximately 40% of elderly inpatients. Evaluating the extent of the illness and response to therapy requires an accurate method for quantitative measurement of urinary incontinence. Quantitative parameters of urinary loss include the frequency and volume of urinary incontinence. A telemetric incontinence detection instrument designed to measure incontinence frequency is described and the instrument is compared with a standard ?wet check”? incontinence detection technique. The electronic instrument appears to be an accurate method for detection of urine loss and is nonobtrusive to the patients.     

Electrosurgery after cochlear implantation: eighth nerve electrophysiology

HYPOTHESIS: Monopolar electrosurgery below the neck in cochlear implant recipients can be performed without damage to the internal cochlear stimulator, electrode array, and the cochlear nerve. STUDY DESIGN: Prospective pre- and postintervention electrically evoked compound action potential (ECAP) study of cochlear nerve function and behavioral sound perception assessment. METHODS: Neural response telemetry (NRT) was used to measure ECAPs before and after the use of monopolar electrosurgery during coronary artery bypass surgery to assess prosthetic device function and electrophysiologic function of the cochlear nerve. In addition, electrode voltage impedances and behavioral sound perception was measured at the same time intervals. RESULTS: ECAPs, behavioral sound perception, and electrode voltage impedances were within the normal range, within compliance, and similar preoperatively and on postoperative day 6. CONCLUSION: The studies reported herein were a series of measurements designed to test neural integrity and prosthetic device function before and after the use of monopolar electrosurgery. With appropriate precautions, use of monopolar electrosurgery below the neck in cochlear implant recipients can be performed safely.     

人工耳蜗植入术术中检测的临床应用

目的分析电极阻抗测试和神经反应遥测(NRT)技术在人工耳蜗手术中的应用,评估人工耳蜗植入术术中电极阻抗测试、NRT的临床意义,探讨术中检测的方式及注意事项。方法对12例植入Nucleus24型人工耳蜗的患者于术中及术后1个月进行电极阻抗测试、NRT,并比较术中、术后ECAP阈值的差异。结果91.7%(11/12)的患者术中电极阻抗测试正常;8.3%(1/12)的患者其中1个电极出现开路。91.7%(11/12)的患者记录到良好的NRT反应波形;8.3%(1/12)的患者术中NRT测试未获得分化良好的ECAP。术中、术后ECAP阈值具有显著的相关性。结论电极阻抗测试可以及时了解电极的工作状况。NRT技术可以有效地应用于Nucleus人工耳蜗植入患者的术中检测,同时协助开机时不能进行心理物理测试的儿童完成映射图的调试。     

Reversible End-of-Life Indicator Leading to Erroneous Pacemaker Replacement-Pitfalls of Telemetry

In several modern pacemakers, end-of-life (EOL) is indicated by a single-step rate drop, which is initiated by a voltage-sensitive electronic switch. This switch may also be activated by other causes, such as very short voltage drops, low temperatures, and electrocautery. We report a case in which a Cordis 233 F Sequicor II pulse generator was operating at 51.6 bpm in VOO mode at the time of implantation. As telemetry seemed to indicate that back-up pacing (the EOL indicator in this model was "off", it was erroneously assumed that the pacemaker was not working properly. The unit was replaced by another impulse generator. At laboratory testing, the pacemaker was within specifications, when back-up pacing was separately programmed off. In conclusion, physicians should be aware of the new phenomenon of reversible EOL indicators, and that they may not rely on telemetry in this respect. Future pacemakers should incorporate a telemetry message which prevents similar misunderstandings.     

Phase locked loop: an application in temperature telemetry and a method for its evaluation

Application of a phase locked loop (PLL) in the front end circuitry of a temperature telemetry system is outlined. Some of the features inherent in PLL operation are discussed which make them more powerful than a Schmitt trigger circuit, and applicable to analysis of many types of frequency signals. The general mode of PLL operation is outlined and a simple method developed whereby PLL behavior can be optimized.     

Telemetric monitoring of adrenocorticotrophin-induced hypertension in mice

1. The mouse is the animal of choice for studies involving genetic manipulation and transgenic and knockout mice are valuable tools for physiological studies. We have studied adrenocorticotrophin (ACTH)- and steroid-induced hypertension in both rat and humans. The aim of the present study was to develop a model of ACTH-induced hypertension in the mouse and to assess a chronically implanted telemetric device for measurement of blood pressure (BP). 2. Male Swiss Outbred and Quackenbush Swiss (QS) mice (35-45 g) were implanted with TA11PA-C20 BP devices (Data Sciences International, St Paul, MN, USA) under isoflurane anaesthesia. Seven to 10 days later, mice were monitored telemetrically for baseline BP for 4 days. Mice were then randomly allocated to: (i) sham treatment with normal saline s.c.; or (ii) ACTH at 500 microg/kg per day, s.c. Mice were monitored 24 h/day for 10 days. 3. Sham treatment (n = 7) did not affect BP (114 +/- 2/84 +/- 1 to 115 +/- 2/84 +/- 1 mmHg; P = NS). Adrenocorticotrophin treatment (n = 5) raised BP from 112 +/- 7/82 +/- 4 to 138 +/- 3/104 +/- 4 mmHg, which was significantly different from sham treatment (P = 0.0021 for systolic BP; P < 0.0001 diastolic BP). The increase in BP with ACTH was comparable with that seen in previous studies in humans, sheep and rat. Sham and ACTH-treated animals each lost 3% bodyweight. 4. Administration of ACTH (500 microg/kg per day) raises BP in two strains of mice, measured using a telemetry system. This model will allow the selective use of transgenic and/or knockout mice to further elucidate the mechanism of ACTH- and steroid-induced hypertension.