Episodic release of methane bubbles from peatland during spring thaw.

Methane (CH(4)) flux into the atmosphere during spring thaw was investigated in a small ombrotrophic peatland (141 degrees 48'E, 43 degrees 19'N, Japan) using the conventional chamber method. More than 50 chamber deployments on top of the snow cover were carried out and continued for more than 165h until the surface snow and underlying ice cover on top of the peat layer had thawed completely. Methane emissions were almost absent in the presence of snow cover. At the very moment the surface ice cover thawed, a large CH(4) flush (>10mgCH(4)m(-2)h(-1)) was recorded, which was on the same order of magnitude as episodic ebullition previously observed in the high-summer. Gas bubbles trapped in the ice layer on top of the waterlogged peat were preliminarily analyzed for the volumetric percentage in the total ice volume and their gas species compositions. Results showed that the bubbles occupied about 3.2% volume and that the mixing ratio of CH(4) in the bubbles was about 20%. The abundance of the bubble-form CH(4) was sufficient to explain the observed episodic CH(4) release during the thaw. Results of this study show that CH(4) emissions during the thaw season have great temporal variability; emission occurs as an episodic release of bubble-form CH(4) stored in the frozen layer. The results also imply the possibility that gas-phase CH(4) plays an important role, not only during the growing season but also in cold-season CH(4) dynamics in northern peatlands.

Odorant evoked magnetic fields in humans.

We investigated the olfactory evoked magnetic fields (OEFs) in 14 normal subjects. Pulses of odorant air containing amyl acetate or phenethyl alcohol, and odorless air were administered to the subject through a nasal tube. A clear and consistent OEF component, 1M, was identified in all subjects, and a second component, 2M, was detected in seven subjects, but no consistent component was identified in response to the odorless air. The peak latencies of the 1M and 2M components were approximately 320 and 630 ms, respectively. The waveforms produced by the odorless air were subtracted from the waveforms produced by the odorant air to obtain the 'subtraction' waveform, which indicated the 1M and 2M component more clearly. Their equivalent current dipoles (ECDs) were estimated in the regions around the Sylvian fissure symmetrically in both hemispheres. Therefore, these areas are proposed to be involved in olfactory perception in humans.

Modifying effects of ethinylestradiol but not methoxychlor on N-ethyl-N-nitrosourea-induced uterine carcinogenesis in heterozygous p53-deficient CBA mice.

It is unknown whether endocrine-disrupting chemicals (EDCs) with estrogenic activities have any modifying effects on uterine carcinogenesis. In our previous study, we established a uterine-carcinogenesis model that is useful for detecting tumor-modifying effects of EDCs by the administration of N-ethyl-N-nitrosourea (ENU) to female heterozygous p53-deficient CBA mice [p53 (+/-) mice]. To investigate the effects of ethinylestradiol (EE) and methoxychlor (MXC) on development of ENU-induced uterine tumors, female p53 (+/-) mice and their wild-type littermates [p53 (+/+) mice] received an intraperitoneal injection of 120 mg/kg body weight (bw) of ENU, followed, in Group 1, by no further treatment; in Group 2, by a diet containing 1 ppm EE; in Group 3, by a diet containing 5 ppm EE for 4 weeks and 2.5 ppm EE thereafter; and in Group 4, by a diet containing 2000 ppm MXC for 26 weeks. Uterine proliferative lesions that were induced were composed of both endometrial-stromal and epithelial-cell types. Endometrial stromal sarcomas were induced in p53 (+/-) mice of Groups 1 to 4, and the incidence (87%) in Group 3 was significantly increased compared to Group 1 (47%). Atypical hyperplasias (clear-cell type) of the endometrial gland in p53 (+/-) mice were seen at incidences of 0, 14, 60, and 0% in Groups 1, 2, 3, and 4, respectively, while their incidence in p53 (+/+) mice was 0, 7, 53, and 0%, respectively, with a significant difference between Groups 1 and 3 in both cases. One p53 (+/-) mouse in Group 3 also had an adenocarcinoma consisting of clear cells, and the PCNA labeling indices of the clear-cell atypical hyperplasias, and this endometrial adenocarcinoma, were higher than those of glandular hyperplasias. The present study suggests that 2.5 ppm EE, but not MXC, exerts tumor-promoting effects on stromal and epithelial proliferative lesions of the uteri in p53 (+/-) mice initiated with ENU.

Binding and functional characterization of alpha1-adrenoceptor subtypes in the rat prostate.

The alpha1-adrenoceptor subtypes of rat prostate were characterized in binding and functional experiments. In binding experiments, [3H]tamsulosin bound to a single class of binding sites with an affinity (pKD) of 10.79+/-0.04 and Bmax of 87+/-2 fmol mg(-1) protein. This binding was inhibited by prazosin, 2-(2,6-dimethoxy-phenoxyethyl)-aminomethyl-1,4-benzodioxane hydrochloride (WB4101), 5-methylurapidil, alpha-ethyl-3,4,5,-trimethoxy-alpha-(3-((2-(2-methoxyphenoxy)ethyl)-amin o)-propyl)benzeneacetonitrile fumarate (HV723) and oxymetazoline with high efficacy, resulting in a good correlation with the binding characteristics of cloned alpha1a but not alpha1b and alpha1d-adrenoceptor subtypes. In functional studies, noradrenaline and oxymetazoline produced concentration-dependent contractions. These contractions were antagonized by tamsulosin, prazosin, WB4101 and 5-methylurapidil with an efficacy lower than that exhibited by these agents for inhibition of [3H]tamsulosin binding. The relationship between receptor occupancy and contractile amplitude revealed the presence of receptor reserve for noradrenaline, but the contraction induced by oxymetazoline was not in parallel with receptor occupation and developed after predicted receptor saturation. From these results, it is suggested that alpha1A-adrenoceptors are the dominant subtype in the rat prostate which can be detected with [3H]tamsulosin, but that the functional subtype mediating adrenergic contractions has the characteristics of the alpha1L-adrenoceptor subtype, having a lower affinity for prazosin and some other drugs than the alpha1A-adrenoceptor subtype.

Peripheral nerve conduction recorded by a micro gradiometer system (micro-SQUID) in humans.

We developed a new multi (twelve) -channel gradiometer system with the smallest and highest quality superconducting quantum interference device (micro-SQUID). A very small distance (3.80 mm) between the sensor coils and the skin provides quite high spatial resolution. The actual whole image of the sensory nerve action fields (NAF) of the human median nerve at the wrist were successfully recorded following digital nerve stimulation by using the micro-SQUID. The NAF showed the biphasic waveform at each of the 12 channels, and the isomagnetic field map clearly showed the moving quadrupole pattern. The quadrupole comprised a dipole for depolarization followed by another dipole with the opposite direction for repolarization. The polarized length of the nerve obtained by reconstructing the magnetic field maps was approximately 17 cm, and the magnetic field complex moved along the nerve from the distal to the proximal part of the wrist at 58.7 m/s.

Glutamate N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists administered into the brain stem depress the renal sympathetic reflex discharges evoked by single shock of somatic afferents in anesthetized rats.

The involvement of glutamate receptors in the central transmission of somatosympathetic reflexes was studied by examining, in anesthetized rats, the effects of MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, and CNQX, a non-NMDA receptor antagonist, on two reflex components, the A- and C-reflexes evoked in the left sympathetic renal nerve by a single shock to the left tibial nerve. The A-reflex elicited by myelinated A fiber stimulation and the C-reflex elicited by unmyelinated C fiber stimulation were depressed, in a dose-dependent manner, following administration of either MK-801 or CNQX into the cisterna magna (i.c.m.). Intrathecal (i.t.) administration of MK-801 did not have any effect on either A- or C-reflexes, while i.t. administration of CNQX had a slight effect on the A-reflex (significantly on the A-reflex only when treated with the highest dose of 100 ng) and the C-reflex. These results indicate that both NMDA and non-NMDA receptors, stimulated by glutamate released possibly as a neurotransmitter, are involved in the central transmission pathways of somatosympathetic reflexes at the level of the brain stem, but not the spinal cord.

Degradation kinetics of (+/-)-4'-ethyl-2-methyl-3-(1-pyrrolidinyl)propiophenone hydrochloride (HY-770) and structure-stability relationship among its analogues in aqueous solution.

The kinetics and pathways for degradation of (+/-)-4'-ethyl-2-methyl-3-(1-pyrrolidinyl)propiophenone hydrochloride (HY-770; 1), a newly developed muscle-relaxing agent, and its analogues were studied in aqueous solution at 50 degrees C, ionic strength 0.5 M, and pH 8.0-12.0. Compound 1 and its four analogues followed pseudo-first-order degradation kinetics at constant pH and temperature. From the analysis of the pH degradation-rate profiles, it is evident that specific hydroxide ion-catalyzed degradations of ionized and un-ionized species occur for 1 and its structural analogue, 3'-fluoro-2-methyl-3-(1-pyrrolidinyl)propiophenone hydrochloride (HN-961; 5). The hydroxide ion-catalyzed degradation of the ionized species was found to be 100 times faster than that of the un-ionized species and to be the major process at pH less than 9.0. On the contrary, 1 was extremely stable in 0.5 M HCl at 50 degrees C, suggesting that the hydronium ion-catalyzed degradation and the spontaneous degradation of the ionized species is negligible. The Arrhenius plot for the degradation of 1 at 35-50 degrees C and pH 9.0 showed that the apparent energy of activation was 22.0 kcal/mol. The degradation rates of the five structural analogues were significantly dependent on the electron withdrawing effect of the benzene substituents of the molecule.

Serum protein binding of lomefloxacin, a new antimicrobial agent, and its related quinolones.

The serum protein binding of lomefloxacin (LFLX), a new quinolone (pyridonecarboxylic acid), and its related analogues was studied by an ultrafiltration technique. The extent of binding of quinolones was independent of the concentration of quinolones below 100 micrograms/mL in rat serum; but, above this concentration, the binding decreased with increased drug concentration in the case of nalidixic acid and analogue 3. The extent of binding in rat serum differed widely among the quinolones examined [i.e., from 15% (norfloxacin) to 84% (nalidixic acid) at concentrations of 0.4-10.0 micrograms/mL]. Lomefloxacin was bound to serum proteins to the extent of 28.1, 20.1, and 20.6% in the sera of rats, dogs, and humans, respectively. The binding of nalidixic acid with rat serum albumin, which was very similar to that in rat serum, was concentration dependent. Some quinolone derivatives with a piperazinyl group or a relatively large-sized substituent at the 7-position exhibited a percentage unbound of approximately 70-80%, while some derivatives with small-sized substituents gave a low percentage unbound of 20-30%. This suggests that there is a steric effect of the substituents at the 7-position of quinolones on their binding characteristics with serum proteins. The results of the present study indicate that quinolones bind mainly with albumin among serum proteins and that the remarkable difference of the extent of binding of quinolone analogues is related to the size of the substituent at the 7-position of the molecule, possibly due to its steric effect.

Physicochemical properties of calcium polycarbophil, a water-absorbing polymer.

The physicochemical properties of calcium polycarbophil were examined. Calcium polycarbophil was decalcified rapidly under acidic conditions, affording polycarbophil. Polycarbophil absorbed about 10 times its own weight of water under acidic conditions, but the swelling ratio markedly increased at above pH 4.0 and reached 70 times the initial weight under neutral conditions. The swelling of polycarbophil was not affected by non-ionic osmolarity, but was affected by ionic strength, showing a decrease with increase of ionic strength. Monovalent metal ions such as sodium and potassium ions in gastrointestinal fluid did not reduce the equilibrium swelling of polycarbophil, but divalent ions such as calcium and magnesium ions did. However, calcium ion only slightly reduced the equilibrium swelling under sodium-rich conditions. The viscosity (as an indicator of fluidity) of polycarbophil was larger than that of CMC-Na at every shear rate and polymer content examined.

[Examples of pitfalls in statistical analysis--5: Analysis of a multiple factor model].

When we analyze the effects of multiple factors, it is inadequate to repeat simple comparisons of the groups divided by a factor. The reasons for this are twofold, i.e., the total error rate of the study grows higher in proportion to the number of comparisons, and we cannot evaluate the relationships between the factors. It is reasonable in such a situation to use multivariate analyses which are developed to analyze multiple factor models, by changing the analytic point of view. In this article, I present an example to illustrate several types of mistakes which occur when we simply compare the two groups divided by one factor for other multiple factors, and explain the evaluation with correlation analysis and factor analysis.

[Examples of pitfalls in statistical analysis--6. Evaluation of data consisting of the elapsed time between two events].

In comparing two or more groups, we usually compare the values of averages and/or medians of the groups. We do this because the averages can be easily calculated from the raw data, and because we feel able, to some extent, to recognize the results from the values. However, since the comparison with the averages is only an evaluation of one aspect of the data, we have to keep in mind the risk of unreasonable analysis and erroneous results. Particularly in evaluating data consisting of the elapsed time between two events of interest, survival analysis is a suite of statistical analyses. In this article, I will show an example to illustrate the method used to compare the elapsed time between two groups using survival analysis.

[Examples of pitfalls in statistical analysis--1. Summarizing your data before statistical analysis].

When conducting studies, it is important to summarize the gathered data before beginning calculations for statistical analysis. If the methods used to summarize the data are inadequate for purposes of the analysis you want to perform, many misleading or unreasonable discussions that are normally avoidable arise. If there is any uncertainty in the way data are handled, for example, confusion as to whether comparison of mean (parametric analysis) or comparison of median (nonparametric analysis) is used, or whether the data are paired or unpaired, it is impossible to make good charts that show us the features of the data at a glance. In this article, I will address several frequently asked questions about summarizing data, and discuss making suitable charts by presenting a typical example.

[Examples of pitfalls in statistical analysis--4: What is a type II error?].

When assessing the results of statistical analysis, we have to consider two types of errors, i.e., type I errors, which present the risk of erroneously judging a true hypothesis to be false, and type II errors, which present the risk of erroneously judging a true hypothesis to be true. If we use only type I errors to detect the significances in statistical analysis, we can not avoid making the erroneous judgement that a true hypothesis is false. When the results of analysis are not significant, we have to calculate type II errors and discuss the probabilities of having missed the truth. In this article, I present an example to illustrate two types of errors which can occur in assessing the result of statistical analysis.

[Examples of pitfalls in statistical analysis--2. Parametric and nonparametric analyses].

When conducting statistical analysis, it is essential to use parametric and nonparametric analyses which properly accord with the attributions of data. What is often overlooked, however, is the need to select the most suitable method of spatistical analysis for the model of the studies. Parametric analysis certainly cannot be relied upon in all situations to yield the best resolutions, and even if we strictly distinguish between the use of parametric and that of nonparametric analyses, we still have done nothing to improve the resolutions themselves. In this article, I discuss several frequently asked questions by presenting an example in which I use parametric analysis on data that should be analyzed by nonparametric analysis.

[Examples of pitfalls in statistical analysis--3: Why do we need to use multiple comparison procedures?].

When comparing the means of more than three groups, we first have to carry out an analysis of variance (ANOVA) to confirm whether all of the means of each group are equal, and we then have to evaluate all possible pairwise comparisons with multiple comparison procedures. If we use only the unpaired t-test for all pairwise comparisons without ANOVA and multiple comparison procedures, we are more likely not only to erroneously conclude that two means in a pair are significantly different when actually they are not, but also to create a contradiction between pairs of means with large differences which are not considered significant, and pairs of means with small differences which are considered significant. In this article, I discuss two problems in comparing the means of multiple groups by presenting an example in which I apply unpaired t-test on data that should be analyzed by ANOVA and multiple comparison procedures.

[Anesthetic management of a patient with Alzheimer's disease].

We gave anesthesia to a 60-year-old female patient in stage III (end stage) of Alzheimer's disease for sigmoidectomy. She had myoclonus and parkinsonism and it was not possible to communicate with her verbally. After induction of anesthesia with thiopental, she had a catheter inserted into epidural space. Without endotracheal intubation, anesthesia was maintained with nitrous oxide, oxygen and isoflurane under spontaneous ventilation supplemented with mepivacaine from the epidural catheter. No muscle relaxant was used. Recovery from the anesthesia was uneventful. No complication was observed during anesthesia and postoperatively.

[Anesthetic management for MIDCAB using the target controlled infusion and the bispectral index].

We report our experience in using the target controlled infusion (TCI) of propofol combined with the bispectral index (BIS) monitoring for anesthetic management of minimally invasive direct coronary artery bypass (MIDCAB) in a 43-year-old-male patient with angina pectoris. After premedication, the patient was connected to the monitor with electrodes for BIS monitor. Then, anesthesia was induced with fentanyl and propofol using TCI technique. When blood concentration of propofol reached 4 micrograms.ml-1, the trachea was intubated. Before starting the operation, we evaluated the relationship between blood concentration of propofol and the value of BIS, and the standard maintenance concentration of propofol was set at 3 micrograms.ml-1. When the concentration of propofol was 3 micrograms.ml-1, the value of BIS was about 60. Anesthesia was maintained with nitrous oxide and oxygen and continuous infusion of propofol using TCI technique. When necessary, we gave additional injection of fentanyl and vecuronium bromide. Furthermore, diltiazem was infused continuously for cardiac rate control, as well as infusion of nicorandil, nitroglycerine for prevention of coronary artery spasms, and prostaglandin. After the operation, the patient was alert in 8 minutes and we could extubate in 12 minutes. The use of TCI combined with BIS monitoring for maintenance of anesthesia for MIDCAB is useful and safe.

[Evaluation of emergence from total intravenous anesthesia with propofol for long neurosurgery].

In six neurosurgical patients we examined their emergence from more than six hours of total intravenous anesthesia with propofol and fentanyl. The anesthesia was maintained properly with total intravenous anesthesia with propofol and fentanyl without nitrous oxide. We calculated the estimated blood concentration of propofol from the anesthesia record using a three-compartment pharmacokinetic model. The patients were extubated after they had shown good awareness. The average time for extubation was 18 minutes after discontinuation of propofol infusion. The mean estimated concentration of propofol at the extubation was 1.36 micrograms.ml-1 (range: 1.1-1.5 micrograms.ml-1). The estimated emergence times in these cases, also calculated with the pharmacokinetic model, correlated significantly with the time from discontinuation of propofol infusion to the patients' awakening. It was concluded, first, that the estimated concentration of propofol at extubation after long anesthesia was similar to that measured in common cases, and second, that we could reduce the emergence time at the tail end of long-sustained neurosurgery by avoiding the delay in emergence.

[The duration of action of vecuronium is unchanged when administered with propofol].

We examined the difference in the duration of action of vecuronium injected through a venous line infused with propofol and the duration of vecuronium infused into another venous line without propofol, in order to investigate the interaction between vecuronium and propofol within the intravenous lines. The subjects of the study are 8 patients, (ASA grade 1 or 2, aged from 20 to 50 years, 6 males and 2 females), who had undergone elective operations under general anesthesia. The mean duration of action of vecuronium injected through the venous line infused with propofol was 32.3 +/- 9.0 (min), while that for vecuronium injected through the venous line without propofol was 32.1 +/- 8.6 (min). There was no significant difference in the duration of action of vecuronium between the two conditions. We conclude that since vecuronium can be injected through the venous lines infused with propofol without interaction, there is no need for an additional venous line without propofol when vecuronium is administered under propofol anesthesia.

[The effects of the fat component of propofol solution of ketogenesis during propofol anesthesia].

To examine the effects of the fat component in propofol solution on the fat metabolism during propofol anesthesia, we measured the urine ketone body (UKB) and blood concentrations of 3-hydroxybutyrate (3-OHBA) and glucose. The anesthesia was maintained with propofol, fentanyl, and vecuronium. Infusion fluid without glucose was used while we measured the concentration of 3-OHBA. UKB was detected only when the concentration of 3-OHBA was more than 400 mumol.ml-1. The blood concentration of 3-OHBA increased in proportion to the total amount of propofol solution, while UKB did not show any such relationship. Furthermore, the rate of increase of 3-OHBA was larger in the group whose concentration of 3-OHBA was higher than the normal range. The blood concentration of glucose ranged within the normal fasting level. There were no cases who needed special treatment for hyperketonemia in this study. We concluded that 3-OHBA was a more sensitive indicator of ketogenesis than UKB, and that ketogenesis was accelerated both by propofol anesthesia with the lipidemic solution of propofol and by fasting before surgery. The acceleration of ketogenesis was especially marked in the patients with hyperketonemia.