Somatosensory evoked potentials in the telencephalon of Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>) following galvanic stimulation of the tail

Electric activity in the brain which is time-locked to a given stimulation of the somatosensory system can be recorded as a somatosensory evoked potential (SEP). We investigated whether a galvanic stimulation of the tail base in Atlantic salmon (Salmo salar) would elicit a SEP in the telencephalon. The telencephalon is central in learning and memory, and activity here may be a prerequisite for processing of external stimuli on a cognitive or emotional level. Anaesthetized salmon (n = 11) were subjected to craniotomy and a recording electrode was inserted into the telencephalon. The fish were given stimulations of four intensities, i.e., 2, 5, 10 and 20 mA. A SEP was elicited in the contralateral dorsal telencephalon for all intensities. This result agrees with findings in other fish species. Furthermore, there was a significant difference between the maximum peak amplitude and mean amplitude of the SEP elicited by putative non-noxious (2 mA) and putative noxious (20 mA) stimulation intensities (P < 0.01). The stronger stimulation intensities also tend to introduce longer-latencies components in the SEP. The results added to the body of literature indicates that the exteroceptive senses are represented by processing within the telencephalon of the fish.     

Lophirones B and C Extenuate AFB1‐Mediated Oxidative Onslaught on Cellular Proteins,Lipids, and DNA through Nrf‐2 Expression

The capability of lophirones B and C to extenuate aflatoxin B₁ (AFB₁)‐mediated onslaught on cellular proteins, lipids, and DNA was investigated for 6 weeks. Lophirones B and C significantly (P < 0.05) increase the expression and specific activity of cytoprotective enzymes (glutathione‐S‐trans‐ferase, nioctinamide adenine dicludeotide:quinone oxidoreductase‐1, epoxide hydrolase, and uridyl glucuronosyl transferase). There was significant (P < 0.05) reduction in the level of antioxidant system in AFB₁‐induced hepatocarcinogenesis. Furthermore, lophirones B and C significantly (P < 0.05) attenuated AFB₁‐mediated decrease in the specific activities of antioxidant enzymes. Oxidative stress biomarkers, malondialdehyde, lipid hydroperoxides, conjugated dienes, protein carbonyl, and fragmented DNA were significantly (P < 0.05) elevated in AFB₁‐treated rats. Although lophirones B and C did not significantly (P < 0.05) alter these biomarkers, an AFB₁‐mediated increase in these biomarkers was significantly attenuated. Results obtained showed that lophirones B and C extenuate AFB₁‐mediated onslaught on cellular proteins, lipids, and DNA by enhancing nuclear erythroid–related factor‐2 expression.     

Effects of interval training at the ventilatory threshold on clinical and cardiorespiratory responses in elderly humans

This study assessed clinical and cardiorespiratory responses after an interval training programme in sedentary elderly adults using the ventilatory threshold (V _th) as the index of exercise training intensity. A selection of 22 subjects were randomized into two groups: 11 subjects served as the training group (TG) and the others as controls (CG). Maximal exercise tests were performed on a treadmill before (T₀), each month (T₁, T₂) and after the 3-month interval training programme period (T₃). The TG subjects were individually trained at the heart rate corresponding to V _th measured at T₀, T₁ and T₂ as the breakpoint in the oxygen uptake-carbon dioxide production relationship. Their training programme consisted of walking/jogging sessions on a running track twice a week. The sessions consisted of varying durations of exercise alternating with active recovery in such a way that the subjects slowly increased their total exercise time from an initial duration of 30 min to a final duration of 1 h. During training the heart rate was continuously monitored by a cardiofrequency meter. Compared with the daily activities of the controls, no training programme-related injuries were observed in TG. Moreover, programme adherence (73%) and attendance (97.3%) were high. The maximal oxygen uptake and V _th were increased in TG, by 20% (P<0.05) and 26% (P<0.01), respectively. Interval training at V _th also significantly increased maximal O₂ pulse (P<0.05) and maximal ventilation (P<0.01). A significant decrease in submaximal ventilation (P<0.05) and heart rate (P<0.01) was also noted. These results would suggest that for untrained elderly adults, an interval training programme at the intensity of V _th may be well-tolerated clinically and may significantly improve both maximal aerobic power and submaximal exercise tolerance. Accepted: 6 January 1998     

Resting Energy Expenditure Changes With Weight Loss: Racial Differences

It is controversial whether weight loss reduces resting energy expenditure (REE) to a different magnitude in black and white women. This aim of this study was to determine whether changes in REE with weight loss were different between black and white postmenopausal women, and whether changes in body composition (including regional lean and fat mass) were associated with REE changes within each race. Black (n = 26) and white (n = 65) women (age = 58.2 ± 5.4 years, 25 < BMI < 40 kg/m²) completed a 20‐week weight‐loss intervention. Body weight, lean and fat mass (total body, limb, and trunk) via dual‐energy X‐ray absorptiometry, and REE via indirect calorimetry were measured before and after the intervention. We found that baseline REE positively correlated with body weight, lean and fat mass (total, limb, and trunk) in white women only (P < 0.05 for all). The intervention decreased absolute REE in both races similarly (1,279 ± 162 to 1,204 ± 169 kcal/day in blacks; 1,315 ± 200 to 1,209 ± 185 kcal/day in whites). REE remained decreased after adjusting for changes in total or limb lean mass in black (1,302–1,182 kcal/day, P = 0.043; 1,298–1,144 kcal/day, P = 0.006, respectively), but not in white, women. Changes in REE correlated with changes in body weight (partial r = 0.277) and fat mass (partial r = 0.295, 0.275, and 0.254 for total, limb, and trunk, respectively; P < 0.05) independent of baseline REE in white women. Therefore, with weight loss, REE decreased in proportion to the amount of fat and lean mass lost in white, but not black, women.     

石灰岩山地优势种淡竹生物量分配的影响主因研究

该研究在江西省瑞昌市设置9个淡竹林样地,调查和测定了淡竹林密度、淡竹各构件的生物量和总生物量,以及土壤含水率、土层厚度、林下裸岩率、pH、电导率、全氮和全磷等7个土壤环境因子,并对竹林密度、土壤环境因子和淡竹生物量分配指标进行了相关分析和回归分析。结果表明：(1)密度与淡竹蔸比重相关系数r达0.66( P＝0.02<0.05),而与叶比重、枝比重、秆比重、鞭比重、根比重及根冠比均无显著相关关系;土壤环境因子与生物量分配指标有密切相关,环境主成分Z1与叶比重、秆比重及蔸比重均显著相关(P<0.05),Z2与鞭比重显著相关(P＝0.034<0.05)。(2)密度与土壤环境因子密切相关(P<0.05),控制土壤环境因子的偏相关分析显示密度与淡竹生物量分配不显著相关( P>0.05),而控制密度时,土壤环境因子与淡竹生物量分配仍有显著相关关系(P<0.05);逐步回归分析也验证了偏相关分析的结果,密度被排除出回归方程。分析认为,土壤含水率、土层厚度及土壤养分等环境因子是影响石灰岩山地优势种淡竹生物量分配的主因,密度对生物量分配的影响实为土壤环境因子的间接作用。该研究结果为石灰岩地区植被恢复提供了理论支撑。     

Effect of 120 days of bed-rest with and without countermeasures on the mechanical properties of the triceps surae muscle in young women

The effect of a 120-day 6° head-down tilt (HDT) bed rest with and without countermeasures on the mechanical properties of the human triceps surae muscle was studied in eight healthy young women subjects. One group [n = 4, mean age 31.5 (SEM 1.7) years] underwent a 120-day HDT only and a second group [n = 4; mean age 28.0 (SEM 1.1) years] underwent HDT with countermeasures (physical training). The results showed that the contractile properties of the skeletal muscle studied changed considerably. After HDT without countermeasures the maximal voluntary contraction (MVC) had decreased by 36% (P < 0.05), and the electrically evoked tetanic tension at 150 Hz (P _o) and isometric twitch contraction (P _t) had decreased by 24% (P < 0.02) and 12% (P < 0.05), respectively. Time- to-peak tension (TPT) of the twitch had significantly increased by 14% (P<0.05), but half-relaxation time (1/2RT), and total contraction time (TCT) had decreased by 19% (P<0.05) and 18% (P<0.05), respectively. The difference between P _o and MVC expressed as a percentage of P _o and referred to as force deficiency (FD), was also calculated. The FD had increased by 40% (P<0.001). The rate of increase of voluntary contractions calculated according to a relative scale had significantly reduced, but for the electrically evoked contraction no substantial changes were observed. After HDT with countermeasures TPT, 1/2RT and TCT of the twitch had decreased by 4%, 7%, 19%, respectively in relation to the control condition. Training had caused a decrease of 3% (P>0.05) in MVC, and P _t, and in P _o of 14%, and of 9% (P>0.05), respectively. The FD had decreased significantly by 10% (P<0.02). The rate of increase of electrically evoked tetanic tension did not change significantly during HDT with countermeasures but the rate of increase in isometric voluntary tension development was increased. Physical training provided a reserve of neuromuscular function, which attenuated the effect of bed rest. The experimental findings indicated that neural as well as muscle adaptation occurred in response to HDT with countermeasures. Accepted: 7 November 1997     

Effects of training for two ball games on the saliva response of adrenocortical hormones to exercise in elite sportswomen

In a group of 20 elite female handball or volleyball players, an evaluation was made of the response to a 4-month training period of cortisol, androstenedione and dehydroepiandrosterone in the saliva. At the beginning of the training programme (W₁) and at the 7th (W₇) and 16th weeks (W₁₆), hormone concentrations were measured on awakening (8 a.m.; resting samples), and also before (t ₀) and at the end (t ₁₂₀) of a 2-h exercise session (simulated match) which took place at 6 p.m. The training programme increased the concentrations of adrenal androgens in the saliva at rest (P<0.05) for both groups of subjects, with no change being noted in cortisol concentrations. In contrast, amongst the volleyball players, stressful stimuli produced by an increase in the amount of training did not affect adrenocortical metabolism during exercise. Indeed, a simulated volleyball match resulted in a decrease in salivary cortisol (P<0.05) and androgen concentrations (P<0.05) without regard for the week chosen for the test investigations. In contrast, a simulated handball match caused an increase in cortisol concentrations at W₁ only (P<0.05), with no change in the adrenal androgens concentration in any week of the training programme. The regulators of these hormones during a period of exercise and during the course of a training programme would seem to be different. Accepted: 30 October 1997     

Control of the rate of phosphocreatine resynthesis after exercise in trained and untrained human quadriceps muscles

We examined the effect of differences in exercise intensity on the time constant (t _c) of phosphocreatine (PCr) resynthesis after exercise and the relationships betweent _c and maximal oxygen uptake (VO_2max) in endurance-trained runners (n = 5) and untrained controls (n = 7) (average VO_2max = 66.2 and 52.0 ml · min^–1 · kg^–1, respectively). To measure the metabolism of the quadriceps muscle using phosphorus nuclear magnetic resonance spectroscopy, we developed a device which allowed knee extension exercise inside a magnet. All the subjects performed four types of exercise: light, moderate, severe and exhausting. The end-exercise PCr: [PCr + inorganic phosphate (P_i)] ratio decreased significantly with the increase in the exercise intensity (P < 0.01). Although there was little difference in the end-exercise pH, adenosine diphosphate concentration ([ADP]) and the lowest intracellular pH during recovery between light and moderate exercise, significant changes were found at the two higher intensities (P < 0.01). These changes for runners were smaller than those for the controls (P < 0.05). The _c remained constant after light and moderate exercise and then lengthened in proportion to the increase in intensity (P < 0.05). The runners had a lowert _c at the same PCr and pH than the controls, particularly at the higher intensity (P < 0.05). There was a significant correlation betweent _c and [ADP] in light exercise and betweent _c and both end-exercise PCr and pH in severe and exhausting exercise (P < 0.05). The threshold of changes in pH andt _c was a PCr: (PCr + P_i) ratio of 0.5. There was a significant negative correlation between the VO_2max andt _c after all levels of exercise (P<0.05).However, in the controls a significant correlation was found in only light and moderate exercise (P < 0.05). These findings suggest the validity of the use oft _c at an end-exercise PCr:(PCr + P_i) ratio of more than 0.5 as a stable index of muscle oxidative capacity and the correlation between local and general aerobic capacity. Moreover, endurance-trained runners are characterized by the faster PCr resynthesis at the same PCr and intracellular pH.     

How do soil microbes exert impact on soil respiration and its temperature sensitivity?

Understanding how soil microorganisms influence the direction and magnitude of soil carbon feedback to global warming is vital to predict future climate change. Although microbial activities are major contributors to soil respiration (R_S) and its temperature sensitivity (Q₁₀), the mechanisms underpinning microbial influence on R_S and Q₁₀ remain unclear. Coupling variation partitioning analysis (VPA), correlation analysis and multiple stepwise linear regression analysis, we illustrate that bacteria mainly affect R_S and its temperature sensitivity (Q₁₀) by shifting bacterial community composition (denoted by principal coordinates analysis). We also found that soil water content (SWC) and available nutrient (AN) were the factor key to changing bacterial community composition (P < 0.05). Co-occurrence network demonstrated that Mod 0 ecological cluster composed of copiotrophic taxa groups was significantly associated with R_S and Q₁₀ (P < 0.01, R > 0.5), including Proteobacteria, Actinobacteria, and Bacteroidetes. Illuminating the mechanisms underpinning the influence of soil microbes on R_S and Q₁₀ values is fundamental to understanding mechanistic soil-climate carbon cycles.     

Positive correlation between plasma nitrite and performance during high-intensive exercise but not oxidative stress in healthy men

Several studies suggest that exercise is associated with elevated oxidative stress which diminishes NO bioavailability. The aim of the present study was to investigate a potential link between NO synthesis and bioavailability and oxidative stress in the circulation of subjects performing high-intensive endurance exercise. Twenty-two male healthy subjects cycled at 80% of their maximal workload. Cubital venous blood was taken before, during and after exercise, and heparinized plasma was generated. Plasma concentrations of nitrite and nitrate were quantified by GC–MS and of the oxidative stress biomarker 15(S)-8-iso-PGF_2α by GC–MS/MS. pH and pCO₂ fell and HbO₂ increased upon exercise. The duration of the 80% phase (d80) was 740 ± 210 s. Subjects cycled at 89.2 ± 3.3% of their peak oxygen uptake. Plasma concentration of nitrite (P < 0.01) and 15(S)-8-iso-PGF_2α (P < 0.05) decreased significantly during exercise. At the end of exercise, plasma nitrite concentration correlated positively with d80 and performed work (w80) (each P < 0.05). Changes in nitrate concentration also correlated positively with d80 (P < 0.05) and w80/kg (P < 0.01). These findings provide evidence of a favorable effect of nitrite on high-intensive endurance exercise. The lack of association between 15(S)-8-iso-PGF_2α and NO bioavailability (nitrite concentration) and NO biosynthesis (nitrate concentration) suggest that oxidative stress, notably lipid peroxidation, is not linked to the l-arginine/NO pathway in healthy male subjects being on endurance exercise.     

Correlation between R/S enantiomer ratio of lansoprazole and CYP2C19 activity after single oral and enteral administration

The purpose of this study was to investigate whether CYP2C19 activity can be estimated from plasma concentrations of lansoprazole enantiomers 4 h (C_4h) after single administration by oral and enteral routes. Sixty‐nine subjects, 22 homozygous extensive metabolizers (homEMs), 32 heterozygous EMs (hetEMs), and 15 poor metabolizers (PMs), participated in the study. After a single oral or enteral dose of racemic lansoprazole (30 mg), plasma concentrations of lansoprazole enantiomers were measured 4 h postdose. The R/S ratio of lansoprazole at 4 h differed significantly among the three groups (P < 0.0001) regardless of the administration route. The R/S ratio of lansoprazole in CYP2C19 PMs ranged from 3.0 to 13.7, whereas in homEMs and hetEMs the ratio ranged from 8.6 to 90 and 2.1 to 122, respectively. The relationship between (S)‐lansoprazole concentration and R/S ratio of lansoprazole at C_4h is given by the following formula: log₁₀ [R/S ratio] = 2.2 – 0.64 × log₁₀ [C_4h of (S)‐lansoprazole] (r = 0.867, P < 0.0001). Thus, phenotyping CYP2C19 using the R/S enantiomer ratio of lansoprazole seems unlikely. However, to obtain a pharmacological effect similar to that in CYP2C19 PMs, we can presume that lansoprazole has a sufficient effect in the patient with an R/S enantiomer ratio at 4 h ≤ 13.70 and (S)‐lansoprazole concentration at 4 h ≥ 50 ng/ml. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

SINE indel polymorphism of <Emphasis Type="Italic">AGL</Emphasis> gene and association with growth and carcass traits in Landrace × Jeju black pig F<Subscript>2</Subscript> population

Genetic polymorphisms in the glycogen debrancher enzyme (AGL) gene were assessed with regard to their association with growth and carcass traits in the F₂ population crossbred Landrace and Jeju (Korea) Black pig. Three genotypes representing the insertion and/or deletion (indel) polymorphisms of short interspersed nuclear element were detected at frequencies of 0.278 (L/L), 0.479 (L/S), and 0.243 (S/S), respectively. The AGL S allele-containing pigs evidenced significantly heavier body weights at birth, the 3rd week, 10th week, and 20th week during developmental stages and higher average daily gains during the late period than were noted in the L/L homozygous pigs (P < 0.05), respectively. However, average daily gains during the early period were not significantly associated with genotype distribution (P > 0.05). With regard to the carcass traits, the S allele pigs (S/-) evidenced significantly heavier carcass weights and thicker backfat than was measured in L/L homozygous pigs (P < 0.05). However, body lengths, meat color, and marbling scores were all found not to be statistically significant (P > 0.05). Consequently, the faster growth rate during the late period and backfat deposition rather than intramuscular fat deposition cause differences in pig productivity according to genotypes of the AGL gene. These findings indicate that the AGL genotypes may prove to be useful genetic markers for the improvement of Jeju Black pig-related crossbreeding systems.     

Ventilatory responses to exercise and carbon dioxide in elderly and younger humans

The present investigation examined the relationship between CO₂ sensitivity [at rest (S _R) and during exercise (S _E)] and the ventilatory response to exercise in ten elderly (61–79 years) and ten younger (17–26 years) subjects. The gradient of the relationship between minute ventilation and CO₂ production ( _E/ CO₂) of the elderly subjects was greater than that of the younger subjects [mean (SEM); 32.8 (1.6) vs 27.3 (0.4); P<0.01]. At rest, S _R was lower for the elderly than for the younger group [10.77 (1.72) vs 16.95 (2.13) 1 · min^–1 · kPa^–1; 1.44 (0.23) vs 2.26 (0.28) 1 · min^–1 · mmHg^–1; P<0.05], but S _E was not significantly different between the two groups [17.85 (2.49) vs 19.17 (1.62) l · min^–1 · kPa^–1; 2.38 (0.33) vs 2.56 (0.21) 1 · min^–1 · mmHg^–1]. There were significant correlations between both S _R and S _E, and _E/ CO₂ (P<0.05; P<0.001) for the younger group, bot none for the elderly. The absence of a correlation for the elderly supports the suggestion that _E/ CO₂ is not an appropriate index of the ventilatory response to exercise for elderly humans.     

Noninvasive skeletal muscle lactate detection between periods of intense exercise in humans

We investigated whether localized ¹H nuclear magnetic resonance spectroscopy (NMRS) using stimulated echoes (STEAM) with a long mixing time (t _m) allowed the suppression of the fat signal and detection of lactate in skeletal muscle. The ¹H NMRS sequence was first validated in three isolated and perfused rabbit biceps brachii muscles. Spectra were obtained on a wide-bore spectrometer using a dual-tuned probe (¹H and ³¹P). Death was simulated by ceasing the muscle perfusion, which allowed post-mortem changes to be followed. During and after the simulated death, changes in levels of pH and in content of energy-rich compounds were observed with ³¹P NMRS. Our results showed an inverse linear relationship between pH and lactate in each of the three rabbits (r = 0.93, P < 0.001; r = 0.92, P < 0.01; r = 0.89, P < 0.01) and a decrease in phosphocreatine and concomitant increase in lactate. We then investigated whether this sequence allowed repeated detection of lactate in human soleus muscle during the recovery between periods of intense exercise (force-velocity test, F-v test). Seven subjects mean age 25.1 (SEM 0.8) years participated in this study. Soleus muscle lactate was detected at rest and for 3 min 30 s of the 5-min recovery between periods using a 2.35-T 40-cm bore magnet spectrometer. Arm venous plasma lactate concentration was measured at rest, during the F-v test when the subject stopped pedalling (S₁), and at the end of each 5-min recovery between periods (S₂). Results showed that the venous plasma lactate concentration at S₁ and S₂ increased significantly from the beginning of the F-v test to peak anaerobic power (W _an,peak) (P < 0.001). The spectra showed that muscle lactate resonance intensity rose markedly when W _an,peak was achieved. The muscle lactate resonance intensity plotted as a percentage of the resting value increased significantly at W _an,peak compared with submaximal braking forces (P < 0.05). We concluded from these results that localized ¹H NMRS using STEAM with a long t _m allows suppression of the fat signal and repeated detection of lactate on isolated perfused skeletal muscle in animals and between periods of intense exercise in humans. Accepted: 19 January 1998     

Leaf anatomy and photosynthetic acclimation in <Emphasis Type="Italic">Valeriana jatamansi</Emphasis> L. grown under high and low irradiance

Relationship of leaf anatomy with photosynthetic acclimation of Valeriana jatamansi was studied under full irradiance [FI, 1 600 mol(PPFD) m^–2 s^–1] and net-shade [NS, 650 mol(PPFD) m^–2 s^–1]. FI plants had thicker leaves with higher respiration rate (R _D), nitrogen content per unit leaf area, chlorophyll a/b ratio, high leaf mass per leaf area unit (LMA), and surface area of mesophyll cell (S _mes) and chloroplasts (S _c) facing intercellular space than NS plants. The difference between leaf thickness of FI and NS leaves was about 28 % but difference in photon-saturated rate of photosynthesis per unit leaf area (P _Nmax) was 50 %. This indicates that P _Nmax can increase to a larger extent than the leaf thickness with increasing irradiance in V. jatamansi. Anatomical studies showed that the mesophyll cells of FI plants had no open spaces along the mesophyll cell walls (higher S _c), but in NS plants wide open spaces along the mesophyll cell wall (lower S _c) were found. Positive correlation between S _c and P _Nmax explained the higher P _Nmax in FI plants. Increase in mesophyll thickness increased the availability of space along the mesophyll cell wall for chloroplasts (increased S _c) and hence P _Nmax was higher in FI plants. Thus this Himalayan species can acclimate to full sunlight by altering leaf anatomy and therefore may be cultivated in open fields.     

Sympathetic nerve regulation of cochlear blood flow during increases in blood pressure in humans

The purpose of this work was to show that regulation of the blood flow to the cochlea by the sympathetic nervous system occurs in humans at the level of the cochlear microcirculation during increases in blood pressure and that its involvement depends on the pressure level. Eight anaesthetized patients undergoing tympanoplasty for hearing disease took part in a pharmacological protocol of stimulation and inhibition of the autonomic nervous system (ANS) to provide variations in systolic blood pressure (BP_S) and cochlear blood flow (CBF). The CBF was measured by laser-Doppler flowmetry. Changes in autonomic nerve activity were brought about by changes in baroreceptor activity (BR) initiated by the injection of an α adrenergic agent before and after sympathetic and parasympathetic blockade. The CBF variations (δCBF) were plotted against BP_S increases at each stage of the ANS inhibition. The BR diminished significantly after α blockade, after α and β blockade, and after α and β blockade and atropine, by 50% (P < 0.01), 29% (P < 0.05), and 95% (P < 0.001) respectively. The BP_S increased significantly (P < 0.01) by 36 (SD 9)%, 47 (SD 1)%, and 67 (SD 16)% respectively. The CBF response to an increase in BP_S exhibited two opposing variations in the patients: CBF decreased significantly in one group, and increased significantly in the other group. In both groups, δCBF decrease and δCBF increase, respectively, were significant after ANS blockade; even so the decrease and increase, respectively, levelled off at BP_S around 160 mmHg before ANS blockade. For BP_S below 160 mmHg, correlations between δCBF and BP_S were significant before inhibition and after inhibition of ANS. For BP_S above 160 mmHg, BP_S and δCBF were not correlated before inhibition of ANS, and were significantly correlated after inhibition of ANS. For BP_S below 160 mmHg, CBF response to the BP_S increase was the same before and after ANS blockade, i.e. ANS control did not predominate; even so, for BP_S above 160 mmHg, the CBF response to BP_S increase was different before and after ANS blockade: CBF varied significantly after ANS blockade as it varied for BP_S below 160 mmHg, while it remained constant before ANS blockade that elicited ANS control of CBF. In conclusion, sympathetic nerve regulation via its vasomotor tone at the level of cochlear microcirculation occurred markedly when the blood pressure was above 160 mmHg; the autonomic nervous system would appear to control the cochlear blood flow against large variations in blood flow in response to hypertensive phenomena. Accepted: 7 October 1996     

Mitochondrial DNA diversity of the vulnerable Chinese Egret (Egretta eulophotes) from China

The genetic diversity and population structure of the vulnerable Chinese Egret (Egretta eulophotes) were surveyed in the present study from three archipelagoes that cover the most southerly to the very northerly parts of the Chinese distribution range of this species, using a 433-bp fragment of the mitochondrial control region (CR). Among 90 individual samples, 31 different haplotypes were defined by 30 polymorphic sites. Overall haplotype diversity, nucleotide diversity and mean sequence divergence (p-distance) of this egret were 0.920, 0.0088 and 1.11%, respectively. NJ tree and parsimony network for the CR haplotypes of the Chinese Egret showed little genetic structure, and analysis of molecular variance indicated low but significant genetic differentiation (haplotype-based Φ_ST = 0.03267, P < 0.05 and distance-based Φ_ST = 0.04194, P < 0.05) among populations. The significant Fu’s F _S tests (Fu’s F _S  = −16.946, P < 0.01) and mismatch distribution analysis (τ = 4.463, SSD = 0.0081, P = 0.12) suggested that the low genetic differentiation and little geographical structure of the genetic differentiation might be explained by the population expansion. The Mantel test (haplotype-based F _ST, r = 0.639, P = 0.34 and distance-based F _ST, r = 0.947, P = 0.15) suggest that the significant genetic differentiation among populations was likely due to isolation by distance.     

Influence of stand density on soil CO2 efflux for a Pinus densiflora forest in Korea

We investigated the influence of stand density [938 tree ha⁻¹ for high stand density (HD), 600 tree ha⁻¹ for medium stand density (MD), and 375 tree ha⁻¹ for low stand density (LD)] on soil CO₂ efflux (R _S) in a 70-year-old natural Pinus densiflora S. et Z. forest in central Korea. Concurrent with R _S measurements, we measured litterfall, total belowground carbon allocation (TBCA), leaf area index (LAI), soil temperature (ST), soil water content (SWC), and soil nitrogen (N) concentration over a 2-year period. The R _S (t C ha⁻¹ year⁻¹) and leaf litterfall (t C ha⁻¹ year⁻¹) values varied with stand density: 6.21 and 2.03 for HD, 7.45 and 2.37 for MD, and 6.96 and 2.23 for LD, respectively. In addition, R _S was correlated with ST (R ² = 0.77–0.80, P < 0.001) and SWC (R ² = 0.31–0.35, P < 0.001). It appeared that stand density influenced R _S via changes in leaf litterfall, LAI and SWC. Leaf litterfall (R ² = 0.71), TBCA (R ² = 0.64–0.87), and total soil N contents in 2007 (R ² = 0.94) explained a significant amount of the variance in R _S (P < 0.01). The current study showed that stand density is one of the key factors influencing R _S due to the changing biophysical and environmental factors in P. densiflora.     

Effect of Ganciclovir on murine cytomegalovirus-induced hearing loss in a mouse model

We evaluated the effect of Ganciclovir on murine cytomegalovirus (MCMV)-induced hearing impairment in a mouse model by studying modulations in auditory brainstem response (ABR) and pathological changes in the inner ear. MCMV infection was established via trans-brain. For this purpose, 24 BALB/c newborn mice were randomly and equally divided into control group (10 μl of sterile normal saline was injected); model group (10 μl of MCMV TCID50—10⁴ IU/0.1 ml was injected); and interfered group (Trans-brain MCMV; Ganciclovir at the rate of 60 mg/kg was intraperitoneally injected). ABR audiometry was performed after 14 days. Acoustic vesicles were obtained for MCMV-PCR analysis and histopathological examination. Comparing ABR in model group against controls, incubation period of wave was lengthened (F = 9.151, P = 0.011–0.05) and wave amplitude was cut down (F = 5.095, P = 0.043–0.05). Comparing ABR in model group against interfered group, incubation period and amplitude of wave were F = 13.797 (P = 0.003–0.05) and F = 14.587 (P = 0.002–0.05), respectively. Cochlear histopathological changes in model group included thickening of vestibular membrane, lymphocytic infiltration, and fibrous degeneration of cochlear duct. In Ganciclovir interfered group, however, these pathologic changes were less significant as compared with those of model group. We, therefore, conclude that Ganciclovir treatment at the early stage of MCMV-induced hearing impairment inhibits the disease progression in infected mice.     

Exercise-induced oxyhemoglobin desaturation and pulmonary diffusing capacity during high-intensity exercise

The purpose of this investigation was to examine if exercise-induced arterial oxyhemoglobin desaturation selectively observed in highly trained endurance athletes could be related to differences in the pulmonary diffusing capacity (D _L) measured during exercise. The D _L of 24 male endurance athletes was measured using a 3-s breath-hold carbon monoxide procedure (to give D _LCO) at rest as well as during cycling at 60% and 90% of these previously determined O_2max. Oxyhemoglobin saturation (S _aO₂%) was monitored throughout both exercise protocols using an Ohmeda Biox II oximeter. Exercise-induced oxyhemoglobin desaturation (DS) (S _aO₂% < 91% at O_2max) was observed in 13 subjects [88.2 (0.6)%] but not in the other 11 nondesaturation subjects [NDS: 92.9 (0.4)%] (P ≤ 0.05), although O_2max was not significantly different between the groups [DS: 4.34 (0.65) l / min vs NDS: 4.1 (0.49) l / min]. At rest, no differences in either D _LCO [m1 CO · mmHg⁻¹ · min⁻¹: 41.7 (1.7) (DS) vs 41.1 (1.8) (NDS)], D _LCO / _A [8.2 (0.4) (DS) vs 7.3 (0.9) (NDS)], MVV [l / min: 196.0 (10.4) (DS) vs 182.0 (9.9) (NDS)] or FEV₁/FVC [86.3 (2.2) (DS) vs 82.9 (4.7) (NDS)] were found between groups (P ≥ 0.05). However, _E /O₂ at O_2max was lower in the DS group [33.0 (1.1)] compared to the NDS group [36.8 (1.5)] (P ≤ 0.05). Exercise D _LCO (m1 CO · mmHg⁻¹ · min⁻¹) was not different between groups at either 60% O_2max [DS: 55.1 (1.4) vs NDS: 57.2 (2.1)] or at 90% O_2max [DS: 61.0 (1.8) vs NDS: 61.4 (2.9)]. A significant relationship (r = 0.698) was calculated to occur between S _aO₂% and _E /O₂ during maximal exercise. The present findings indicate that the exercise-induced oxyhemoglobin desaturation seen during submaximal and near-maximal exercise is not related to differences in D _L, although during maximal exercise S _aO₂ may be limited by a relatively lower exercise ventilation. Accepted: 25 September 1996