No abstract available.

Inhibition of K⁺ outward currents by linopirdine in the outer hair cells (OHCs) of circling mice (homozygous (cir/cir) mice), an animal model for human deafness (DFNB6 type), was investigated using a whole cell patch clamp technique. Littermate heterozygous (+/cir) and ICR mice of the same age (postnatal day (P) 0 –P6) were used as controls. Voltage steps from –100 mV to 40 mV elicited small inward currents (–100 mV~–70 mV) and slow rising K⁺ outward currents (–60 mV ~40 mV) which activated near –50 mV in all OHCs tested. Linopirdine, a known blocker of K⁺ currents activated at negative potentials (I(K,n)), did cause inhibition at varying degree (severe, moderate, mild) in K⁺ outward currents of heterozygous (+/cir) or homozygous (cir/cir) mice OHCs in the concentration range between 1 and 100 µM, while it was apparent only in one ICR mice OHC out of nine OHCs at 100 µM. Although the half inhibition concentrations in heterozygous (+/cir) or homozygous (cir/cir) mice OHCs were close to those reported in I(K,n), biophysical and pharmacological properties of K⁺ outward currents, such as the activation close to –50 mV, small inward currents evoked by hyperpolarizing steps and TEA sensitivity, were not in line with I(K,n) reported in other tissues. Our results show that the delayed rectifier type K⁺ outward currents, which are not similar to I(K,n) with respect to biophysical and pharmacological properties, are inhibited by linopirdine in the developing (P0~P6) homozygous (cir/cir) or heterozygous (+/cir) mice OHCs.
Animals ; Deafness ; Hair Cells, Auditory, Outer* ; Humans ; Mice* ; Mice, Inbred ICR ; Models, Animal ; Tea

No abstract available.
Humans

This study was purosed to investigate maternal and fetal clinical parameters effecting on maternal serum alpha-fetoprotein(MSAFP) levels at late normal singleton pregnancies. The subjects of this study were 171 pregnant women with gestational age of 36 to 42 weeks, and didn`t have any medical or gynecologic diseases. They delivered fetuses within three days after blood test of MSAFP. MSAFP levels were measured by enzyme-immunoassay. The analysed clinical parameters included fetal sex, fetal weight, gestatioal age, maternal age, gravidity, parity, maternal weight and maternal total weight gain during pregnancy. The results were as follows: At uncomplicated late pregnancies, 1. Male fetus bearers had higher MSAFP(mean: 191.8 ng/ml, SD: 80.8 ng/ml, n=79) than female-fetus bearers(mean 153.6 ng/ml, SD 73.0 ng/ml, n=92)(p=0.0014). 2. Multiparas had higher MSAFP(mean: 192.7 ng/ml, SD: 77.9 ng/ml, n=80) than nulliparas(mean: 152.3 ng/ml, SD 75.1 ng/ml, n=91)(p=0.0007). 3. MSAFP did not have correlation with maternal age, maternal weight, maternal total wight gain during pregnancy, gestational age, fetal weight. According to the above results, fetal sex and parity are the factors that influences MSAFP levels at uncomplicated late pregnancies. So MSAFP values should be interpreted with cautions.
Female ; Fetal Weight ; Fetus ; Genital Diseases, Female ; Gestational Age ; Gravidity ; Hematologic Tests ; Humans ; Male ; Maternal Age ; Parity ; Pregnancy* ; Pregnant Women ; Weight Gain

The intra-articular tibial plateau fracture can induce many complications of the knee joint after conservative treatment or operative treatment. Recent experience could decrease the complications with accurate anatomical reduction, stable internal fixation and early knee ROM exercise, but still unsatisfactory results were reported from 20% to 40%. The authors analyzed the 30 cases that could be follow-up from 1 year to 6 years and were treated with operative methods, and the following results were obtained. 1. The most common cause of injury was traffic accident (14 cases-46.4%). 2. The most common fracture type by Hohls classification was type VI (13 cases-43.1%). 3. According to Blokker's criteria, 26 cases (86.7%) among 30 cases had satisfactory results. 4. The one of the most important factor influencing end results was thught to be the anatomical reduction of the articular margin.
Accidents, Traffic ; Classification ; Follow-Up Studies ; Knee ; Knee Joint

The developmental changes of convergence ratios of medial nucleus of trapezoid body (MNTB) axons to single lateral superior olive (LSO) neuron were investigated using voltage clamp technique in homologous (cir/cir) circling mice, animal model for the congenital deafness with autosomal recessive inheritance. As the developmental reduction of convergence ratio reported in rats indicates the presence of synaptic refinement, we aimed to find out whether the similar reduction of convergence ratio also occurs in circling mice. Heterologous (+/cir) mice were used as control and mice younger than postnatal (P) day 4 or older than P9 were used. The convergence ratios of MNTB axons to single LSO neuron were 29.16+/-2.7 (n=12, P9) in homologous (cir/cir) mice, while they were 37.89+/-3.8 (n=9, P9) in heterozygous (+/cir) mice. The significant changes were observed only in heterozygous (+/cir) mice, which indicated that synaptic refinement of MNTBLSO synapses occurs in heterozygous (+/cir) mice, not in homozygous (cir/cir) mice. Considering homologous (cir/cir) mice being animal model for the congenital deafness, our data might contribute to the understanding of developmental changes of brain stem auditory circuits of congenitally deaf patients.
Animals ; Axons ; Brain Stem ; Deafness ; Humans ; Mice ; Models, Animal ; Neurons ; Olea ; Rats ; Synapses ; Wills

OBJECTIVES: In the developing auditory cortex, maturation of electrophysiological properties and cell types before and after hearing onset has been reported previously. However, the exact timing of firing pattern change has not been reported. In this study, firing pattern change was investigated from postnatal day 3 (P3) to P12 in auditory cortical layer II/III neurons to investigate whether firing pattern changes dramatically after a specific point during development. METHODS: ICR mice pups aged from P3 to P12 were sacrificed to obtain 300-mm-thick brain slices containing the primary auditory cortex. From cortical layer II/III neurons, the patterns of action potential firing generated by current injection were examined using whole cell current clamp technique and the characteristics of Na⁺ currents involved in action potential firing were investigated using whole cell voltage clamp technique. RESULTS: From P3 to P6, most cells did not show action potential firing (29 of 46 cells), and some cells responding to current injection showed a single action potential at the initial depolarizing current step (17 of 46 cells). This firing pattern changes from P7. From P7 to P9, cells begin to show regular spiking to current injection. The spiking frequency increased after P10. In studying Na⁺ current with whole cell voltage clamp, Na⁺ current densities increased gradually (32.0±2.0 pA/pF [P3–P6, n=7], 51.2±2.0 pA/pF [P7–P9, n=13], and 69.5±3.7 pA/pF [P10–P12, n=13]) in low external [Na⁺] condition. Na⁺ current recovery was accelerated and inactivation curves shifted to hyperpolarization with age. CONCLUSION: As regular spiking cells were observed from P7 but never from P3 to P6, P7 might be regarded as an important milestone in the development of auditory cortical layer II/III neurons. This change might mainly result from the increase in Na⁺ current density.
Action Potentials ; Animals ; Auditory Cortex ; Brain ; Fires ; Hearing ; Mice ; Mice, Inbred ICR ; Neurons

Because synaptic refinement of medial nucleus of trapezoid body (MNTB) - lateral superior olive (LSO) synapses is most active during the first postnatal week and the long term depression (LTD) has been suggested as one of its mechanisms, LTD of MNTB-LSO synapses was investigated in neonatal rat brain stem slices with the whole cell voltage clamp technique. In Mg2+ free condition, tetanus (10 stimuli at 10 Hz for 2 min) in the current clamp mode induced a robust LTD of isolated D, L-APV-sensitive postsynaptic currents (PSCs) for more than 30 min (n=6, 2.4+/-0.4% of the control), while isolated CNQX-sensitive PSCs were not suppressed (n=6, 95.3+/-1.6%). Tetanus also elicited similar LTD in the isolated GABAergic/glycinergic PSCs (n=5, 3.6+/-0.5%) and mixed PSCs (GABAergic/glycinergic/glutamatergic) (n=4, 2.2+/-0.7%). However, such a strong LTD was not observed in the mixed PSCs when 10 mM EGTA was added in the internal solution (n=10), indicating that postsynaptic Ca2+ rise is needed for the strong LTD. This robust LTD might contribute to the active synaptic refinement occurring during the first postnatal week.
Animals ; Brain Stem ; Depression ; Egtazic Acid ; Olea ; Rats* ; Synapses* ; Synaptic Potentials ; Tetanus

To investigate the short-term vestibular responses in the pilots, the 4 successive velocity step tests were done on the 25 pilots, who are in active service in ROKAF (Republic of Korea Air Force), and the obtained results were compared with those of the non-pilots. As the repeated rotations might alter the vestibulo-ocular reflex (VOR), sinusoidal harmonic acceleration (SHA) test at a frequency of 0.16 Hz were also given before and after the 4 successive velocity step tests to investigate the changes of gain and phase of VOR. In the 25 pilots (mean age 31 year), the mean values of the slow cumulative eye position (SCEP), the time integral of eye velocity during nystagmus and time constants were gradually reduced with 4 successive trials. These values were significantly greater than those obtained in the 25 non-pilots. The gain of vestibulo-ocular reflex (VOR) induced by SHA test at a frequency of 0.16 Hz decreased from 0.64+/-0.04 to 0.58+/-0.03 in the pilots, while the VOR gain increased from 0.59+/-0.03 to 0.78+/-0.06 in the non-pilots. However, this result did not indicate that the pilots' gains of VOR were out of normal range. In another SHA tests in which the 30 pilots participated, the gains, phases and the symmetries of VOR lied in the very normal range in every test frequencies (0.01, 0.02, 0.04, 0.08, 0.16, 0.32 Hz). From the above results, it might be suggested that the vestibular responses of the pilots are different with those of the non-pilots.
Acceleration ; Exercise Test ; Korea ; Reference Values ; Reflex, Vestibulo-Ocular

BACKGROUND: The present study is undertaken to acquire normative data of health-related physical fitness(HRPF) of Republic of Korea Air Force(ROKAF) aircrews and to provide norm-referenced standard of HRPF. METHODS: From 15 May 1998 through 14 December 1999, 1284 KAF pilots are checked muscular strength, muscular endurance, flexibility, and body fat percentage. RESULTS: The grip strength was relatively maintained, but flexibility, back strength, and muscular endurance were declined according to promotion and aging. And the incidence of obesity determined by bioelectrical impedence analysis was higher than that assessed on the basis of height and weight. CONCLUSION: It is suggested that many pilots who were normal in BMI have abdominal or visceral obesity. Further studies must be made on the health promotion program for the pilots, on the changes in physical fitness, and on the criterion-referenced standard of HRPF of the pilots.
Adipose Tissue ; Aging ; Hand Strength ; Health Promotion ; Incidence ; Obesity ; Obesity, Abdominal ; Physical Fitness* ; Pliability ; Republic of Korea