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Effect of changing afterload and inotropic states on inner and outer ventricular wall thickening. Am. J. Physiol. 263 (Heart Circ. Physiol. 32): H109-H116, 1992.--To study the differing behaviors of the inner (IH) and outer halves (OH) of the left ventricular (LV) free wall during an increasing afterload and changing inotropic states, we determined the LV pressure (LVP) and transmural (TM) and OH wall thickness (WTTM and WTOH) by sonomicrometry in 11 anesthetized dogs. The percent systolic wall thickening (% delta WT) and the fractional contribution (FC) were calculated. At rest, % delta WT of TM, IH, and OH were 22 +/- 1 (mean +/- SE), 33 +/- 3, and 13 +/- 2 (P less than 0.01 vs. IH), respectively. The FC of IH and OH were 74 +/- 5 and 29 +/- 4% (P less than 0.01 vs. IH), respectively. During increasing afterload by aortic constriction (AC) without drugs, % delta WT in IH was reduced to 22 +/- 2%, associated with unchanged % delta WT in OH (12 +/- 3%), whereas the FC of IH and OH were not altered from resting values. During AC with dobutamine infusion (3 micrograms.kg-1.min-1), the % delta WT and FC in each layer were not reduced from resting values. On the other hand, during AC with propranolol (2 mg bolus iv), the reduction of % delta WT in IH was greater (from 29 +/- 4 to 15 +/- 6%, P less than 0.01) than that in OH (from 11 +/- 2 to 10 +/- 3%; P less than 0.01 vs. IH). The FC in the IH was decreased (56 +/- 16%) by AC with propranolol, so that the difference in FC between IH and OH became insignificant (FCOH 40 +/- 13%, P greater than 0.1 vs. FCIH).(ABSTRACT TRUNCATED AT 250 WORDS)

We studied the effects of hyperthyroidism on the relation between O2 consumption (Vo2) and the pressure-volume area (PVA) of the left ventricle (LV) in dogs. PVA is a measure of the total mechanical energy generated per beat of LV. Dogs were treated by daily intramuscular injection of 0.3 or 1.0 mg/kg L-thyroxine over 2-5 weeks. Hyperthyroid dogs had a 40 times higher serum T4, a 40% higher sinus heart rate, and a 35% higher LV Emax (an index of ventricular contractility) than euthyroid dogs. Hyperthyroid dog hearts had linear Vo2-PVA relations like euthyroid dog hearts. The regression line was Vo2 = A x PVA + B, where A was 2.30 (dimensionless) and B was 0.53 J/beat per 100 g LV. B was significantly increased with dobutamine and decreased with propranolol, whereas A was not significantly changed by them. These A and B values were comparable to euthyroid data. Hyperthyroidism did not significantly affect myosin Ca-ATPase activity and V3-type myosin predominance, but increased the speed of the force transient response to length perturbation by 20%-70%, suggesting similar increases in crossbridge cycling rate. We conclude that in spite of accelerated crossbridge cycling rate the Vo2-PVA relation was not altered by hyperthyroidism in dogs.

We studied whether an optimal Emax (contractility index) to minimize myocardial O2 consumption (MVo2) for a constant external work (EW) and, hence, maximize mechanical work efficiency exists as a nadir of MVo2 within the physiological range of Emax. MVo2 and Emax were measured in the left ventricles (LV) of 10 dogs. In each experiment, heart rate, cardiac output, and mean aortic pressure were kept constant by pacing, bypassing the right heart, and adjusting the inflation of an intra-aortic balloon, respectively, to maintain a constant EW. MVo2 was determined as the product of coronary arteriovenous O2 difference, and coronary blood flow drained from the right heart. Emax was obtained by an abrupt aortic occlusion method. We changed Emax over 1.4-16.1 mmHg.ml-1.100 g) by dobutamine, propranolol, and sodium pentobarbital. The obtained MVo2-Emax relationship showed that MVo2 correlated positively with Emax in 9 of the 10 dogs (correlation coefficients = 0.68-0.96). In one of the 9 dogs and the remaining dog, MVo2 slightly increased with decreases in Emax below 7-8 mmHg.ml-1.100 g. We conclude that the optimal Emax to minimize MVo2 for a constant EW does not generally exist as a nadir of MVo2 in the physiological range of Emax in dog hearts.

We studied whether there is an optimal heart rate (HR) that would minimize myocardial oxygen consumption (MVO2) per min for a constant minute cardiac work. We measured minute MVO2 (ml O2/min) of the left ventricle paced at increasing rates (100-200 beats/min) in 10 right-heart-bypassed dogs. In each experiment, cardiac output was kept constant with a constant-flow bypass pump, and mean aortic pressure was also kept constant by inflation or deflation of an intra-aortic balloon. Minute cardiac work was thus kept constant. Minute MVO2 was obtained as the product of mean coronary arteriovenous O2 difference and mean coronary blood flow drained from the collapsed right ventricle. Both left ventricular Emax (contractility index defined as the slope of the left ventricular end-systolic pressure-volume relation) and PVA (pressure-volume area as a measure of total mechanical energy of contraction) were obtained by an abrupt aortic occlusion method. The obtained-minute MVO2-HR relationship showed a good linear positive correlation (r = 0.824-0.995) in every heart. We accounted for this relationship by the changes in PVA and Emax that we had proposed as primary determinants of MVO2. We conclude that minute MVO2 for a constant minute cardiac work increased monotonically with increases in HR from 100 to 200 beats/min, being minimum at the lowest HR, and that this relation was ascribable to the HR-proportional increase in the MVO2 component for the excitation-contraction coupling.

The luminescence of Perylene Orange and LDS821 in poly(methyl methacrylate) (PMMA) following a 532 nm irradiation yielded information on photodegradation and energy transfer. The irradiation of the Perylene Orange/LDS821/PMMA films resulted in (i) a maximum in the Perylene Orange fluorescence photodegradation profile and (ii) an enhancement of the LDS821 fluorescence relative to the LDS821/PMMA films. These results are attributed to an energy transfer from the Perylene Orange to the LDS821 with an energy transfer rate constant of 5.1+/- 0.75 (2sigma) x 10(11) M(-1) s(-1) and a Förster critical radius of 65.7 A. Fluorescence half-quenching and time-resolved fluorescence measurements attributed energy transfer to the Förster energy transfer with minor contributions of radiative energy transfer.

Infection with HSV or EBV was studied by measuring serum antiviral antibody titers in adults with acute tonsillitis, and results were compared to light and electron microscopy findings of tonsil biopsy specimens. The clinical and laboratory features of acute tonsillitis caused by HSV or EBV were also studied. Subjiects were 42 patients with acute tonsillitis treated at the Department of Otorhinolaryngology at Tokyo Women's Medical University Daini Hospital between August 1997 and March 2000. They had failed to respond to antimicrobial agents prescribed by a physician, and had severe oropharyngeal mucosal lesions, liver dysfunction, skin eruptions, or cervical lymphadenopathy, with hospitalization required because of impaired food intake due to sore throat or deterioration in general condition. Subjects were 24 men (mean age: 30.8 years) and 18 women (mean age: 28.3 years) aged 16 to 78 years (mean: 29.8 years). A underwent, bacteriological and hematology tests and palatine tonsil biopsy specimens were obtained to examine tissue changes by light microscopy and electron microscopy due to detect HSV antigen by immunohistochemistry and EBV nucleic acids by EBV-encoded small nuclear RNA 1 and 2 (EBER) in situ hybridization (ISH). Among patients, the serum antiviral antibody profile indicated that 4 (9.5%) had acute tonsillitis due to primary HSV infection and 5 (11.9%) had acute tonsillitis due to primary EBV infection. The findings characteristic of acute tonsillitis due to primary HSV infection included stomatitis, skin eruptions, atypical lymphocytes, and liver dysfunction. Findings characteristic of acute tonsillitis due to primary EBV infection included petechiae of the soft palate, an increase of lymphocytes, atypical lymphocytes, and liver dysfunction. At the initial test, serum anti-HSV antibody was positive in 14 patients (33.3%), and more than half had no history of prior infection. Anti-EBNA antibody was positive in 32 (76.2%), and many had been infected previously. It should be noted that a decrease in positive HSV antibody means that acute tonsillitis due to primary HSV infection is not uncommon in adults and is expected to increase steadily. Light microscopy revealed histological changes in 2 patients. HSV antigen was positive in 2 (50%) with acute tonsillitis due to primary HSV infection, while EBER cells were positive in 5 (100%) with acute tonsillitis due to primary EBV infection, so special staining of the tissues was found to be useful. Electron microscopy failed to detect viral particles in ultrathin sections and no differences were seen in morphological changes or tissue damage between patients with positivity for HSV antigen and with EBER-positive cells. Detection of HSV antigen and EBV nucleic acids in pathological specimens from patients with acute tonsillitis requires careful judgment, but is considered useful for making an early diagnosis and for making a diagnosis in patients without an increase of the antiviral antibody titer and in those with reinfection or reactivation. Pathological examination (including special staining) and careful observation of clinical features may help to identify HSV or EBV infection and allow decisions to be made with regard to the therapeutic strategy and prevention of complications.

We studied the efficiencies from oxygen consumption (VO2) to external mechanical work (EW), from VO2 to the systolic pressure-volume area (PVA), and from PVA to EW, and the effects of cardiac output and contractility index (Emax) on these efficiencies in the left ventricle of open-chest, right-heart-bypassed dogs. PVA is an intermediate form of energy between VO2 and EW. PVA, EW, and Emax were determined by an abrupt occlusion of the ascending aorta. The right-heart bypass allowed us to collect all coronary venous return for VO2 measurement. The EW/VO2 efficiency ranged between 4 and 21%, the PVA/VO2 efficiency ranged between 5 and 27%, and the EW/PVA efficiency ranged between 60 and 95%. At a given Emax, EW/PVA efficiency was independent of cardiac output, but PVA/VO2 and EW/VO2 efficiencies increased with cardiac output. An increase in Emax by dobutamine increased EW/PVA efficiency, but decreased PVA/VO2 and EW/VO2 efficiencies. We could theoretically account for these changes in EW/PVA, PVA/VO2, and EW/VO2 efficiencies of the in situ heart by the VO2-PVA relation and its dependence on Emax that we had observed.

収縮性の変化が心臓の酸素消費量に及ぼす影響は古くて新しい問題である. 我々は, この問題に新しい概念-収縮期圧容積面積 (PVA)-を用いて挑戦している. PVAは, 圧容積図面中の特定の面積であるが, 収縮によって発生する心臓の総機械的エネルギーを表すと考えられる. イヌ心臓を用いての実験では, 収縮性が一定なら, PVAは酸素消費量と直線的に良く相関した. 収縮性を高めると, この関係は酸素消費量を増すように平衡移動した. それは主として興奮収縮連関のための酸素消費量の増加による. この際, PVAに依存する酸素消費量は常にPVAの変化に比例することから, 収縮機構そのもののエネルギー効率は不変と考えられる.

In an effort to learn more about succinate-1, 4-14C metabolism in the connective tissue cell, metabolic alteration in the L-929 fibroblast cell was studied at various culture stages.Newly-synthesized organic acids measured by chromatographic elution each day were by average: malic acid (22%), fumaric acid (11%), lactic acid (7%), citric acid (5%), pyruvic acid (4%) and substance A (23%). Total organic acid production increased almost 2-fold by the 8 th day of culture. Moreover, the ratio of newly-synthesized macromolecules to those incorporating succinate-1, 4-14C continued to increase after the cell population became a monolayer at the fourth day.This study shows that succinate-1, 4-14C turnover is extensive and rapid with L-929 cell proliferation. As cultured cell sampled are often taken when the monolayer stage is reached, the study inculudes a comparison of biological composition in culture medium with and without cells. Measurement of protein, uronic acid and hydroxyproline showed increases of 26%, 14% and 47%, respectively, in the culture medium with cells.

Hyaluronan (HA) is one of the major extracellular matrix components in cartilage. In addition to the biomechanical functions, HA has various important roles in the differentiation of chondrocytes. The purpose of this study was to clarify the nature of HA synthesis during chondrocyte differentiation. Growth plate chondrocytes were isolated from rabbit ribs and cultured in chondrocyte differentiation medium. The amount of HA and HA synthase (HAS) mRNA levels were analyzed for each stage of chondrocyte differentiation by means of high-performance liquid chromatography (HPLC) and real-time PCR, respectively. The distribution of HA in cultured chondrocytes was observed by histochemical staining. The amount of HA, ranging widely in size, was increased substantially during the hypertrophic stage. The expression levels of HAS2 and HAS3 mRNAs were low during the matrix-forming stage. HAS2 mRNA level was substantially enhanced at the pre-hypertrophic stage, whereas HAS3 mRNA level exhibited a slight increase. HAS1 mRNA was not detected. The intensity of HA staining was high around the hypertrophic chondrocytes. These results suggest that HA metabolism in chondrocyte differentiation is regulated by the selective expression of HASs, and HAS2 and the related large size-HA may have a certain association with the hypertrophic changes of chondrocytes

Cardiac contraction requires a continuous oxygen supply via the coronary circulation. The oxygen demand of the heart per unit mass under physiological conditions is high, around 8 ml/min/100g, comparable to that of active skeletal muscle. Cardiac oxygen demand varies widely depending on cardiohemodynamic, neural (sympathetic and vagal), and humoral (endocrinological and pharmacological) conditions (Gibbs, 1978). When, as in normal, coronary oxygen supply (= coronary flow × arterial oxygen content × maximum oxygen extraction fraction) exceeds cardiac oxygen demand, cardiac contractions can continue without being restricted by the supply. However, when the coronary oxygen supply is limited abnormally, the heart cannot maintain normal contractions and the cardiac contractile state is depressed (Weber et al., 1980). In fact, an acute decrease in coronary perfusion decreases cardiac contraction immediately. For a better understanding of the balance between cardiac oxygen supply and demand, factors determining the cardiac oxygen demand must be fully elucidated. The cardiac oxygen demand of ongoing contractions can be quantified by cardiac oxygen consumption (Vo2) under aerobic conditions, i.e., non-ischemic (Weber et al., 1980). In this sense, we can use cardiac oxygen demand and Vo2 interchangeably under conditions of sufficient coronary oxygen supply. However, the value for cardiac oxygen demand expressed as Vo2 of the ongoing contraction under decreased coronary perfusion conditions may be smaller than that obtained from the heart with a sufficient coronary oxygen supply (Weber et al., 1980).

In recent years, our research has been directed to the relation between cardiac dynamics and energetics. We have utilized myocardial oxygen consumption (MVO2) as the energy input to the heart. Since MVO2 is obtained as the product of coronary blood flow (CBF) and arteriovenous oxygen content difference (AVD), both the behavior of coronary vascular tone and the oxygen extraction capability of the myocardium may affect MVO2 and consequently cardiac performance. In general, myocardial oxygen extraction rate is about 75% (Goodale and Hackel, 1953), and the heart is working nearly at its maximum capability of oxygen extraction even in the resting state. Several reports showed relative constancy of coronary venous oxygen content and AVD independent of changes in MVO2 (Gerola, et al., 1959; Katz and Feinberg, 1958; Feigl, 1983). Therefore, the coronary arterial reserve to increase blood supply is especially important when oxygen demand increases by physical exercise, etc. It was also well documented that CBF closely correlates with MVO2 with typical correlation coefficients from 0.8 to 0.9 (Belloni, 1979).

Although the pressure-rate product (double product; DP) is generally recognized as a good index of myocardial oxygen consumption (VO2), catecholamines are reported to change the VO2-DP relationship. However, the separate influences of chronotropism and inotropism on the VO2-DP relation have not been studied. Therefore, we examined these influences in anesthetized open-chest dogs by cardiac pacing and dobutamine infusion. We observed two different VO2-DP lines under the separate chronotropic and inotropic changes. We interpreted such VO2-DP relations by the concept of the pressure-volume area (PVA). PVA is a measure of total mechanical energy for ventricular contraction and is a specific area in the ventricular pressure-volume (P-V) diagram circumscribed by the end-systolic and end-diastolic P-V relation curves and the systolic segment of the P-V trajectory. The empirical VO2-PVA relation that had been obtained in our previous studies reasonably simulated the dissociation of DP from VO2 under separate changes in chronotropism and inotropism.

Many determinants (indices or predictors) of myocardial oxygen consumption (VO2) have been proposed over recent decades [1, 2]. They include peak or mean ventricular pressure, myocardial systolic force, time integrals of pressure and force, contractile element work, dP/dt, Vmax, and their various combinations including Bretschneider’s total myocardial energy requirement Et [1] and the Rooke and Feigl pressure-work index [2]. Some of them are empirical and others are theoretical. However, we do not feel satisfied with them because their correlations with VO2 are not always good under a variety of loading, heart rate, and contractile conditions.

We assessed the accuracy of the intraventricular balloon method of left ventricular volume measurement with all chordae tendineae intact and then severed. The space between the endocardium and the balloon is the source of the volume measurement error. We assessed the volume errors at different intra-balloon pressures between 50 and 250 mmHg, using formalin fixed canine left ventricles. The volume error with all chordae tendineae intact was significantly greater than with all chordae tendineae severed at any balloon pressure. The difference of the volume errors under these two conditions amounted to 1.9-3.3 ml regardless of intra-balloon pressures. We visually confirmed that this difference predominantly originated from the space behind the tense chordae tendineae.

The relation between cardiac O2 consumption (VO2) and the total mechanical energy (TME) generated by contraction was studied under paired-pulse (PP) pacing and compared with that under single-pulse pacing at the same basic rate as PP pacing and at the double-pacing rate in ten excised cross-circulated canine left ventricles (LV). TME was assessed by the systolic pressure-volume (P-V) area (PVA) defined as the area bounded by the end-systolic and end-diastolic P-V curves and the systolic P-V trajectory. The VO2-PVA relation was linear under PP pacing as well as at control and double heart rates. PP pacing increased LV contractility index Emax from 6.3 +/- 3.3 (SD) to 18.0 +/- 8.6 mmHg/(ml/100 g) and elevated markedly the VO2-PVA relation by increasing the VO2-axis intercept (or PVA-independent VO2) from 0.62 +/- 0.11 to 1.13 +/- 0.35 J.beat-1.100 g-1. However, PP pacing did not change the slope of the VO2-PVA relation at 2.24 +/- 0.53 (dimensionless). The efficiency from PVA-dependent VO2 (total VO2-PVA-independent VO2) to PVA (=TME), calculated as the reciprocal of the slope of the VO2-PVA relation, was also constant at 47 +/- 11% regardless of PP pacing. These results are similar to previous results obtained by positive inotropic interventions with catecholamines and Ca2+. We conclude that PP pacing augments the PVA-independent VO2 for activation without affecting the efficiency of the contractile machinery to generate TME from the PVA-dependent VO2.

We studied the effect of a new positive inotropic agent, OPC-8212 (3,4-Dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)-quinolinon e), on the relation between left ventricular oxygen consumption (VO2) and pressure-volume area (PVA) in excised cross-circulated dog hearts. PVA represents the total mechanical energy generated by ventricular contraction. OPC-8212 increased the contractility index, Emax, by 59% +/- 36% from 7.6 +/- 4.3 to 11.1 +/- 4.6 mmHg/(ml/100 g LV [leftventricle]). OPC-8212 elevated the VO2-PVA relation without a significant change in its slope. Namely, OPC-8212 did not affect the mechanical efficiency of the contractile machinery from the PVA-dependent fraction of VO2 to PVA, but increased the PVA-independent fraction of VO2 which is related with non-mechanical processes of contraction. This effect suggested an increased energy expenditure for excitation-contraction coupling. These results associated with the enhanced contractile state by OPC-8212 were both qualitatively and quantitatively similar to those obtained with catecholamines and calcium in our previous study. This suggests that OPC-8212, catecholamines, and calcium have similar effects on intracellular Ca2+ concentration and enhanced ventricular contractility.

[1] The seasonal changes in evapotranspiration over a hill evergreen forest in northern Thailand (18°48′N, 98°54′E), in the Asian monsoon region, were simulated using a multilayer model and the boundary conditions above the canopy. The simulation considered the uncertainty in the leaf area index (LAI) and physiological parameters for both photosynthesis and stomatal conductance models. The parameters were based on the estimated LAI and determined by referring to the measured net photosynthesis rate and stomatal conductance for a single leaf. The simulated cumulative evapotranspiration and rainfall interception agreed with the values obtained from the water budget within these uncertainties. The sensitivity of these limits to both evaporation and transpiration was also investigated. The simulated transpiration peaked in the late dry season. The latent heat flux obtained with the eddy correlation technique showed that the forest continued to transpire in the late dry season. The heat pulse velocities also showed a peak in water use by individual trees in the late dry season. These results counter the view that evapotranspiration declines in the dry season, as has been reported previously for an evergreen forest and other vegetation in Thailand. The transpiration peak was thought to depend on the reduced wetness of the canopy, and the consequent lack of evaporation from it, and on the fact that there was little decline in stomatal conductance, even in the driest conditions.

匂いは揮発性化合物の混合物である。動物は昆虫では触角、脊椎動物では嗅上皮にある嗅細胞で、周辺空気中に含まれる揮発性物質を検知し、その情報を脳に伝えてどの種類の物質がどのように混合しているかを計算することで、さまざまな匂い物質の混合物を単一の匂いとして認識する。近年、嗅細胞は発現する嗅覚受容体遺伝子の種類に応じて、嗅覚系1次中枢内の数十から数千ある糸球体から、1ないし2個に選択的に投射することが、昆虫と脊椎動物で示された。言い換えると、1次中枢内には嗅覚受容体遺伝子に対応した、匂い地図が形成されていることになる。しかし、1次中枢の匂い地図構造の活動パターンを脳の上位中枢がどのように読みとり、匂いを割り出すのかはまだ完全には明らかにされていない。 そこで本研究では、1次嗅覚中枢の情報が次のレベルの情報処理領域である2次嗅覚中枢にどのように伝わるのか、その神経回路を明らかにすることを試みた。そのためにショウジョウバエのGAL4エンハンサートラップ系統を用いて、昆虫の嗅覚系1次中枢にあたる触角葉から、2次中枢にあたるキノコ体と側角、さらにその他の従来未同定だった2次中枢に投射する神経細胞を標識し、それらの細胞が作る神経回路構造を解剖学的に明らかにした。 まず、1次中枢の触角葉に樹秋分技をもち、そこから上位中枢へ投射する経路として、既知の4経路に加えて新たに2経路を発見した。この結果、従来知られていたキノコ体と側角以外に、前大脳の後側部、中央上部、上側部などの脳領域が1次中枢からの嗅覚情報を直接受け取ることが明らかになった。 ゴルジ染色法などをもちいた従来の研究では、既知の4経路は同定はされていたものの、異なる経路の間で個々の神経の投射様式にどのような違いがあるかなどは調べられていなかった。そこで、同定された6経路のうち、キノコ体に投射する3経路と、側角に投射する4経路について、それぞれの2次中枢内部で投射神経の軸索終末がどのように分布するかを調べた。 その結果、異なる経路を通ってキノコ体や側角に投射する神経は、2次中枢内部でそれぞれ異なる領域に分布するわけではなく、大きな重なりを持っていた。また、1次中枢からの投射神経には、単一の糸球体に樹状分技を伸ばして情報を集める単一糸球体型と、多数の糸球体に樹状分枝を伸ばして情報を集める多糸球体型があるが、それぞれの経路にある単一糸球体型と多糸球体型の神経の終末は、2次中枢内においては完全には分離しないものの、非常に異なる分布パターンを示した。以上のように、1次中枢からいったん異なる経路に伝えられた刺激情報は2次中枢内の同じ領域に再び収斂するが、同じ経路に伝えられた単一糸球体型と多糸球体型投射神経の刺激情報は、収斂せずに2次中枢内の異なる領域に伝えられているという原則が判明した。 また、キノコ体の中に｢単一糸球体型投射を受ける部分｣と｢多糸球体型投射を受ける部分｣が別れて存在するのに対し、側角では異なる経路で伝えられた単一糸球体型と多糸球体型の投射神経の終末はそれぞれ合計すると側角全体をカバーしていた。従って側角ではキノコ体と異なり、「単一糸球体型投射を受ける部分｣と｢多糸球体型投射を受ける部分｣が、側角全体に重複して存在していた。 単一糸球体型投射神経は個々の糸球体の活動パターンを特異的に2次中枢に伝えることができる唯一の情報経路である。そこで、個々の糸球体の情報が2次中枢のどこへ伝えられるのかを知るため、投射神経の中の過半を占め、キノコ体と側角の2つの主要2次中枢の両方に投射する投射神経(innter antenno-cerebral tract、iACT投射神経)に関して、2次中枢間における投射様式の相違を調べた。 触角葉に存在する43個の糸球体のうち9個について詳しく調べたところ、これらは側角では、上部後方、下部前方、下部後方の3つの領域に収斂して投射する3つのグループに分類できることが分かった。同様にキノコ体では、中央部、中間部、辺縁部の同心円状の3層の領域に収斂して投射していた。側角の同じ領域に収斂投射する糸球体は、キノコ体でも同じ領域に収斂投射する。従って、投射神経の投射様式には2つの主要2次中枢の間に強い相関があり、糸球体ごとの軸索終末の分配は共通であった。そして1次中枢の糸球体は、iACT投射神経が側角とキノコ体のどの領域に投射するかによって、少なくとも3つのグループに分けられることが明らかになった。 このように2次中枢では、異なる糸球体グループの活動情報が2次中枢内の異なる領域に分離して伝えられている。そこで次に、この情報を2次中枢側の神経がどのように受け取るかを調べた。そのために、2次中枢のキノコ体神経細胞と側角神経細胞が、同定された3つの領域に対してどのように神経線維を伸ばしているかを解析した。 側角神経細胞は従来ほとんど調べられていなかったので、今回GML4エンハンサートラップ系統のスクリーニングによって、始めてその投射形態を明らかにした。その結果、側角神経は、1次中枢からの投射神経が規定する側角内の各領域に限局した投射が観察された。そして、側角内の異なる領域に投射する側角神経細胞は、それぞれ異なる脳内領域と側角とを連絡していた。つまり1次中枢の異なる糸球体グループから2次中枢の異なる領域に送られてきた嗅覚情報は、混合されずに分離したまま脳の別の領域へ送られて処理されるという可能性が強く示唆された。 一方キノコ体神経細胞には、キノコ体の異なる出力部位に投射する4つのグループが分類可能であるが、それぞれが1次中枢からの投射神経が規定する3つの同心円状の領域をまたがって、全体に投射していた。単一神経細胞レベルで解析しても、l領域に限局した投射をする細胞から、3領域に投射する細胞までが入り混じっていた。これらの多様な細胞集団が、同じ出力領域に軸索終末を収斂して形成している。すなわちキノコ体では、1次中枢の異なる糸球体グループから2次中枢の異なる領域に送られてきた嗅覚情報が、混合されて再び収斂するような回路構造があることが明らかになった。 キノコ体は嗅覚連合学習に必須であるが、学習や経験に依存しない嗅覚刺激応答ではキノコ体は不要であり、側角の機能だけで十分だと分かっている。今回の研究で、側角には領域ごとに限局した回路構造が存在するのに対し、キノコ体には各糸球体由来の刺激情報を統合しうる回路構造があるという大きな違いがあることが分かった。2つの主要2次中枢が担う機能の違いには、このような情報伝達様式の違いが関係している可能性が示唆された。

Thermodynamic parameters for subtilisin-catalyzed kinetic resolutions of secondary alcohols were determined, and a compensation effect between ΔΔH‡ and ΔΔS‡ was found. These data are explained in terms of the transition-state model.