Search

Estrogen plays an important role in male reproduction, critical for sustained fertility in some species. Reducing estrogen's interaction with its receptor(s) in monkey and mouse models is associated with reduced sperm motility and, in some cases, documented elimination of sperm fertilizing ability, suggesting that normal epididymal function may be estrogen dependent. The objective of these experiments was to evaluate the effects of reduced endogenous estrogen on development of epididymal function in the pig, a species in which males have very high levels of endogenous estrogen. Letrozole, a potent inhibitor of estrogen synthesis, was administered to neonatal boars from 1 week of age and markedly suppressed estrogen production. Epididymal function assessed as acquisition of sperm fertilizing ability (in vitro fertilization of zona-free oocytes) was reduced in Letrozole-treated animals at 24 and 28 weeks of age (23% and 30% fertilization, respectively compared with 37% and 54% in vehicle controls) but had recovered by 32 weeks of age. Cauda epididymal sperm numbers were reduced in treated animals (35% of control values at 20 weeks of age) but appeared to be recovering at 32 weeks of age. Reduction of endogenous estrogen had no effect on other aspects of epididymal function (percentage of motile sperm, sperm motion parameters, sperm head morphometrics, or ability of sperm to undergo an acrosome reaction). Reducing endogenous estrogen during postnatal development appears to have transient effects on porcine epididymal function. These transient effects suggest that the pig, with its high endogenous estrogen, may respond differently than other species to reduced estrogen synthesis.

Patients with myasthenia gravis show sensitivity to non-depolarizing neuromuscular blocking drugs, but little is known about differences in this sensitivity between types of myasthenia. In 10 patients with ocular myasthenia gravis and 10 with generalized myasthenia gravis, twitch tension was monitored in the adductor pollicis muscle by supramaximal train-of-four stimulation of the ulnar nerve during anaesthesia with sevoflurane 2.5% and nitrous oxide 60%. After baseline measurement, an initial dose of vecuronium 10 microg kg(-1) was given. When the twitch height stabilized (maximum block after the first 10 microg kg(-1)), the next incremental dose of 10 microg kg(-1) was given and repeated until block, defined as [1-(first twitch/baseline first twitch)] x 100 reached 90%. Maximum block after the first dose of vecuronium in ocular patients was significantly less than that in generalized patients (median 51 vs 91%; P0.05). Onset of block after the first dose of vecuronium was significantly slower in ocular than in generalized myasthenic patients (mean 300 vs 200 s; P0.05). Doses required to attain a block of 90% or more were significantly higher in ocular than in generalized patients (median 20 vs 10 microg kg(-1); P0.05). Clinicians should consider the type of disease according to the Osserman classification when using non-depolarizing neuromuscular. blocking drugs in patients with myasthenia gravis.

We describe the anaesthetic management of a 72-year-old man with myasthenic syndrome. Pre-operatively, he was treated with 3,4-diaminopyridine and showed a strong hand grip. During general anaesthesia with nitrous oxide and sevoflurane in oxygen, a mechanomyograph and two accelerographs were set up for the hands and left foot to monitor neuromuscular function. Insufficient force and acceleration of contraction with 1 Hz stimulation was observed in the hands. In the foot, the twitches produced by 1 Hz and train-of-four stimulation could barely be detected using the accelerograph, and the train-of-four ratio fluctuated between 70 and 100%. No neuromuscular blocking drugs were used during surgery. After discontinuation of sevoflurane, responses to train-of-four stimulation remained small, but a strong response to tetanic stimulation was observed, with post-tetanic facilitation. Extubation was successful, and recovery from anaesthesia was uneventful. Tetanic stimulation and post-tetanic facilitation are important in monitoring neuromuscular function in patients with myasthenic syndrome whose train-of-four responses are insufficient.

The integrated intensity of the IR absorption mode near 640 cm−1 is directly proportional to hydrogen density while that around 2000–2100 cm−1 is not proportional to this. The crystallinity of a sample prepared by hot-wire assisted PECVD (HWAPECVD) is higher than that by PECVD. The hydrogen density of a sample prepared by HWAPECVD is smaller than that by PECVD. The mode near 840 cm−1 in IR absorption spectrum for a sample prepared by HWAPECVD is smaller than that by PECVD. The properties and the role of hydrogen in μc-Si:H are discussed.

Regenerative medicine for patients with peripheral atherosclerosis attracts considerable attention around the world. However, ethical problems persist in gene therapy. This study evaluates the effect of alterative magnetic stimulation on peripheral circulation. The effect of magnetic stimulation as a medical treatment was examined using a thermograph for 11 healthy volunteers. The thermograph was used to measure the rise in skin temperature. The experimental results suggested an improvement in the peripheral circulation. The results of our study suggest the effectiveness of alternative magnetic stimulation on atherosclerosis. We intend to extend our study in order to establish a methodology for regenerative medical treatment for patients with peripheral atherosclerosis. Further, we wish to advance the current research in the field of angiogenesis.

In order to evaluate the EEG of patients with epilepsy, chaos analysis was performed for the subdural EEG time series data. The chaos attractor was reconstructed in the phase space and the correlation dimension. KS entropy calculated from the Lyapunov exponents was evaluated. Before the seizure attack, the KS entropy showed a lower value when compared with the time series data recorded during healthy condition. The results of our study suggest that it is possible to predict the seizure attack by the chaos analysis of the EEG signal. Further, we aim at developing an automatic control system for predicting a seizure attack by the use of local cooling of the focus with Peltier elements.

Photoinduced structural change in hydrogenated amorphous silicon (a-Si:H) has been studied by a sensitive bending detection method using an optical lever. We observed that a-Si:H films show not only thermal expansion due to a photothermal effect but also residual and persistent expansion after light soaking. The volume change is recovered by thermal annealing at 200 °C. A dehydrogenated sample annealed at 550 °C and a microcrystalline sample, in which photoinduced defects are not created, show little photoinduced expansion. The photoinduced expansion and photoinduced defect density show identical time evolution. These results suggest that the photoinduced expansion is related to the photoinduced defect creation. A quantitative evaluation of the photoinduced expansion indicates that the photoinduced structural change is spread over several molecular volumes around a photocreated defect.

A rotary blood pump (RP) is desirable as a small ventricular assist device (VAD). However, an RP is nonpulsatile. We tried to develop a device that attaches a pulse to the RP. We also tried to develop a pulse-generating equipment that was not air-pressure driven. The ball screw motor was considered a candidate. The application of a small-sized shape memory alloy was also attempted. An electrohydraulic system was adopted, and actuator power was connected to the diaphragm. The diaphragm was placed on the outer side of the ventricle. Most RPs that have been developed all over the world drain blood from the ventricle. The wave of a pulse should be generated if a pulse is added by the drawn part. The output assistance from the outer side of the ventricle was attempted in animal experiments, and the device operated effectively. This device can be used during implantable operation of RP. This may serve as an effective device in patients experiencing problems in peripheral circulation and in the function of internal organs.

A new skin-transparent signal transmission method is proposed. For applications on high energy-consumption medical devices such as total artificial hearts or implantable FES (functional electrical stimulation) systems, we constructed a transcutaneous signal transmission system using figure-of-eight coils, as it is apparent that these applications need feedback and/or controlling signals for stable and safe operation. By employing figure-of-eight coils, we could reduce noise coming from around the coil and still suppress noise emitted from the transmitting coil. In the animal experiment using a goat, we could successfully observe the fluctuation in the amount of the transmitted energy through skin with figure-of-eight coils of 30 mm in diameter. Meanwhile, figure-of-eight coils didn't cause any unfavorable interferences with the electromagnetically driven ventricular assist device connected to the goat's heart at the time.

We focus on a membrane excitation model of finite and bent nerves elicited by magnetically induced electric fields. We simulated nerve excitation by changing the length of an axon and the distance between the coil and the nerve. The computer simulation suggests that the termination points of nerves or the bending part of an axon are low threshold stimulation sites when magnetically stimulated with a figure-eight coil. We also suggest that a short axon is more easily excited than an infinitely long axon of the same thickness. These results give useful information in understanding neuronal responses to magnetic stimulation of both central and peripheral nervous systems.

We describe the anaesthetic management of a 72-year-old man with myasthenic syndrome. Pre-operatively, he was treated with 3,4-diaminopyridine and showed a strong hand grip. During general anaesthesia with nitrous oxide and sevoflurane in oxygen, a mechanomyograph and two accelerographs were set up for the hands and left foot to monitor neuromuscular function. Insufficient force and acceleration of contraction with 1 Hz stimulation was observed in the hands. In the foot, the twitches produced by 1 Hz and train-of-four stimulation could barely be detected using the accelerograph, and the train-of-four ratio fluctuated between 70 and 100%. No neuromuscular blocking drugs were used during surgery. After discontinuation of sevoflurane, responses to train-of-four stimulation remained small, but a strong response to tetanic stimulation was observed, with post-tetanic facilitation. Extubation was successful, and recovery from anaesthesia was uneventful. Tetanic stimulation and post-tetanic facilitation are important in monitoring neuromuscular function in patients with myasthenic syndrome whose train-of-four responses are insufficient.

The use of a liquid organic source for n‐type doping in hydrogenated amorphous silicon (a‐Si:H) is described. Tertiarybutylphosphine (TBP) vapor is added to silane in a rf glow discharge process to produce doped a‐Si:H thin films. Impurity levels from parts per million to about 1% phosphorus have been incorporated into the film with this method. Measurements of dark conductivity, photoconductivity, conductivity activation energy, electron spin resonance, and sub‐gap optical absorption of the TBP‐doped films are compared to those published for films doped with phosphine.

To analyze the hemodynamic parameters during prosthetic circulation as an entity, non linear mathematical techniques were used. To compare natural and prosthetic circulation, two pneumatically actuated ventricular assist devices were implanted as biventricular bypasses in chronic animal experiments using adult goats to consitute the biventricular bypass complete prosthetic circulation model with ventricular fibrillation. After implantation, these goats were placed in a cage and extubated after waking. All hemodynamic parameters with the natural circulation without biventricular bypass pumping, and the artificial circulation with biventricular bypass pumping under ventricular fibrillation were recorded under awake conditions. By the use of a non linear mathematical technique, the arterial blood pressure waveform was embedded into a four dimensional phase space and projected into three dimensional phase space. The Lyapunov numeric method is used as an adjunct to the graphic analysis of the state space. A phase portrait of the attractor showed a high dimension complex structure, with three dimensional solid torus suggesting deterministic chaos during natural circulation. However, a simple attractor, such as a limit cycle attractor, was observed during artificial circulation. Positive Lyapunov exponents during artificial circulation suggest the lower dimensional chaotic system. Thus, hemodynamic parameters during prosthetic circulation must be carefully controlled when unexpected stimuli are fed from outside.

To investigate the drive condition of the artificial heart from a neurophysiological point of view, the dynamic transduction characteristics of the baroreflex system were analyzed by means of sympathetic neurograms. Two pneumatically actuated ventricular assist devices were implanted as biventricular bypasses (BVBs) in adult mongrel dogs to compare the natural heart circulation and prosthetic circulation. After BVB pumping was initiated, the natural heart was electrically fibrillated. Renal sympathetic nerve activity (RSNA) was recorded to analyze sympathetic outflow. Coherence function between the arterial pressure and RSNA was calculated to evaluate the linearity of the baroreflex system. The largest peak coherency was observed when BVB was driven at the frequency of natural heart beat prior to electrical fibrillation, which suggests that the baroreflex system shows the largest linearity at this frequency. These results suggest the possibility that the natural heart beat frequency is the setting frequency at which the baroreflex system transfers the hemodynamic rhythm to the sympathetic outflow.

To evaluate the effect of total artificial heart replacement on the autonomic nervous system, sympathetic neurograms were analyzed by power spectrum and coherence function. Two pneumatically driven, sac type ventricular assist devices were implanted as biventricular bypasses (BVB) in adult, mongrel dogs. After initiation of BVB pumping, the natural heart was electrically fibrillated to form a BVB TAH model. Renal sympathetic nerve activity (RSNA) was recorded using a bipolar electrode attached to the left renal sympathetic nerve. RSNA was amplified and integrated by use of an R-C integrator. Power spectra of the RSNA and values of squared coherence between the arterial pressure wave form and the RSNA were calculated by computer. In animals with total artificial hearts (TAHs), coherence at the cardiac rhythm frequency was decreased, and coherence at the TAH pumping rhythm frequency was increased. These results indicate that the arterial pulse wave observed in TAH animals contributed to the sympathetic neurogram.

Photothermal deflection spectroscopy (PDS) at 77 K is described. The sample is immersed in liquid nitrogen with the liquid nitrogen acting as both the cooling and the deflecting medium. The experimentally obtained thermal diffusion length and relative change of refractive index of liquid nitrogen are compared with those of carbon tetrachloride. The construction of the liquid‐nitrogen cryostat is the key factor in reducing the noise. A sensitivity of αd=10−4 is obtained for the present system. This technique enables the sensitive measurement of PDS at low temperatures.

A new type of synchronous electrophrenic respirator developed by the authors has been applied to dogs with incomplete respiratory failure produced by blocking the 1st thoracic cord and the C6 and C1 branches of both phrenic nerves (sometimes including a unilateral C5 branch). This respirator stimulated the distal stump of the phrenic nerve synchronously with the feeble impulses from the proximal stump of the nerve, resulting in a suitable control of respiration. The minute ventilatory volume and the partial pressures of the expiratory end-tidal gases were adjusted automatically by this respirator, from the state of hypoventilation to the normal control level, accompanied by an overshoot and damped oscillations. The arterial-bloodgases also exhibited a satisfactory recovery from the hypoventilation. The inhalation of high concentrations of carbon dioxide during the synchronous, electrophrenic respiration produced similar responses to those observed in normal dogs. Accordingly, it was found that the synchronous electrophrenic respirator could operate as an element of the respiratory-feedback system.