Homing in wood ants, Formica japonica: use of the skyline panorama.

Homeward orientation was studied in wood ants Formica japonica that, while foraging, shuttled back and forth along a 7.9m route between the nest and a feeding site located on a wide terrace platform surrounded by a conspicuous landmark panorama. The return runs of the ants were amazingly straight, not only in the controls (starting at the feeding site) but also in ants displaced for various distances to the left and right of the feeding site. These courses, however, were oriented neither parallel to the predisplacement courses nor directly towards the nest. This result excludes the use of chemical cues and celestial compass cues. Furthermore, the nest itself, or some object close to it, could not have served as a beacon. The extensions of the homeward paths taken by ants that had been displaced to various release sites up to 11m sideways from the training route intersected at a point far (approximately 13m) behind the nest. This result suggests that the ants used distant landmarks seen by them in their frontal fields of view. To test this hypothesis, the distant landmark panorama was concealed by an opaque sheet mounted at right angles to the normal return route of the ants and extending up to different elevations. Shielding the lower part of the landmark panorama had no effect on the homeward paths. However, when the screen was mounted in such a way that the ants could only see the top skyline, represented by the upper edges of a line of trees, for part of their return run, it was only during these parts that their path was oriented in the homeward direction. When, during the course of displacement experiments, the ants were deprived of their familiar skyline panorama, they moved in their home direction only for an extremely short distance (0.1-0.4m rather than the usual 7.9m) and then started a systematic search programme. Hence, in the present context, skylight information is not used, at least not extensively. Instead, ants use the distant skyline as a navigational guidemark.

Plasma levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 are increased in the coronary circulation in patients with acute coronary syndrome.

BACKGROUND: Previous studies on atherectomy specimens from patients with acute coronary syndrome (ACS) implicated the role of proteolytic enzymes. We examined whether the plasma levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were increased in the coronary circulation in ACS. METHODS AND RESULTS: The plasma levels (nanograms per milliliter) of MMP-9 and TIMP-1 in the aorta (Ao) and great cardiac vein (GCV) were measured in 29 patients with ACS (20 with acute myocardial infarction [group 1] and 9 with unstable angina [group 2]), 17 with stable effort angina (group 3), and 20 control subjects (group 4). Group 1 patients had occlusion in the left anterior descending artery (LAD), and groups 2 and 3 patients had culprit lesion in the LAD. In group 1 blood samples were obtained at the time of direct coronary angioplasty done within 12 hours after the onset. The Ao level of either MMP-9 or TIMP-1 did not differ among the 4 groups. The GCV-Ao differences in MMP-9 and TIMP-1 were both significantly increased in groups 1 and 2 compared with those in group 4. Neither of them was different between groups 3 and 4. Neither the GCV-Ao difference in MMP-9 or TIMP-1 level was correlated with the maximal creatine kinase level in group 1. CONCLUSIONS: Increased plasma levels of MMP-9 and TIMP-1 were detected in the coronary circulation in ACS patients, suggesting a process of active plaque rupture in ACS.

Enhanced phospholipase C activity in the cultured skin fibroblast obtained from patients with coronary spastic angina: possible role for enhanced vasoconstrictor response.

OBJECTIVES: We measured phospholipase C (PLC) activity in the cultured skin fibroblasts obtained from patients with and without coronary spasm and examined its correlation with coronary artery vasomotility. BACKGROUND: Coronary artery vasomotility is enhanced in coronary spastic angina (CSA), but no information is available for the intracellular signaling. In spontaneously hypertensive rats, PLC activity in the skin fibroblasts has been shown to be enhanced. METHODS: Skin fibroblasts obtained from 24 patients with CSA-14 with organic coronary artery disease (CAD) and 12 control subjects--were cultured by the explant method. Activity of PLC was determined by incubating the membrane fraction with 3H-phosphatidyl inositol bisphosphate and by quantifying 3H-inositol trisphosphate. In patients with CSA and control subjects, the relations between PLC activity and coronary artery basal tone and constrictor response to intracoronary acetylcholine (ACh) were examined. RESULTS: Activity of PLC (pmol/protein [mg] per min) was 1.74+/-0.19 in patients with CSA; 0.90+/-0.12 in patients with CAD; and 0.65+/-0.07 in control subjects (p<0.001, patients with CSA vs. patients with CAD and control subjects; p = NS, patients with CAD vs. control subjects). According to the Lineweaver-Burk plot, Michaelis constant (micromol/liter) of PLC was 28+/-4 in patients with CSA; 49+/-14 in patients with CAD; and 56+/-10 in control subjects (p<0.05, patients with CSA vs. control subjects), whereas the maximal velocity was not different between the three groups. There were significant positive correlations between PLC activity and both basal tone (p = 0.0108) and response to ACh (p = 0.0053). Western blot analysis using membrane fraction demonstrated that 89% of PLC isoenzymes detected was of the delta1 isoform. CONCLUSIONS: Because the PLC activity measured was genetically defined and was positively correlated with coronary artery vasomotility, enhanced PLC activity may be involved in the pathogenesis of coronary spasm.

Glucose dilution can detect fluid redistribution following phentolamine infusion in dogs.

OBJECTIVE: We have recently reported that the initial distribution volume of glucose (IDVG) reliably measures the central extracellular fluid (ECF) volume in the presence of fluid gain or loss. However, it is not clear if IDVG consistently reflects central-ECF volume when redistribution of fluid occurs in the absence of fluid gain or loss. This study was designed to investigate changes in fluid volumes during phentolamine infusion in dogs. DESIGN: Prospective animal study. SETTING: Institutional animal research laboratory. SUBJECTS: Fourteen anesthetized and ventilated mongrel dogs. INTERVENTIONS: Anesthetized animals were mechanically ventilated and received infusions of normal saline (n = 7) or phentolamine (10 microg kg min) (n = 7). Plasma volume was estimated using the indocyanine green (ICG) dilution method (PV-ICG) and IDVG was calculated using a one-compartment model by simultaneous administration of ICG 0.5 mg/kg and glucose 100 mg/kg before, during, and after infusion of either drug. MEASUREMENTS AND RESULTS: PV-ICG during infusion was not different between groups. However, IDVG significantly decreased (P < 0.05) following phentolamine infusion when compared with normal saline infusion. CONCLUSION: Our results suggest that IDVG rather than PV-ICG consistently measures central extracellular fluid volume, even when redistribution of fluid occurs.

Enhanced reactivity of electron-deficient enynes in the palladium-catalyzed homo-benzannulation of conjugated enynes

We report the high reactivity of electron-deficient enynes in the homo-benzannulation of conjugated enynes in the presence of Pd(PPh3)4. The introduction of electron-withdrawing groups enabled us to carry out the benzannulation of 1-substituted enynes as well as 1,2- and 2,4-disubstituted enynes. Polysubstituted benzenes were prepared in a highly regioselective manner in good to excellent yields.

Optical scaling in conspecific Cataglyphis ants

This study examines the effects of body size variation on the optical properties of the compound eyes of visually guided desert ants belonging to the genus Cataglyphis. Although linear head size may vary by a factor of 2 within conspecific workers and most optical parameters change accordingly, the extent of the visual field remains constant. Comparative measurements carried out on workers of three species (C. albicans, C. bicolor and C. fortis) and on reproductive females and males of one species (C. bicolor) show that the form (size and shape) of the visual field is highly characteristic for each caste/species. A constant visual field is realised by reciprocal scaling rules for the number of ommatidia and the angular spacing of ommatidia. While larger ants have more ommatidia per compound eye, interommatidial angles are reduced accordingly, thus giving rise to a constant visual field. Among conspecific ant workers, the relationship between spatial visual acuity and eye size is similar to that found in interspecific comparisons and reflects optical constraints imposed on the design of the compound eye. Mapping of spatial visual directions onto the compound eye surface reveals a characteristic, inhomogeneous distribution of interommatidial spacing, particularly a foveal band with increased visual acuity in the vertical direction. This 'visual stretch' viewing the horizon is similar to that found in a variety of flying insects. Although, among conspecific workers, both the number of ommatidia and the interommatidial angles vary with varying head size, the overall pattern of interommatidial spacing is maintained so that corresponding positions on the compound eye of small and large individuals look in equivalent directions in space. These findings are in accordance with the observation that the shape of the compound eye surface, as expressed by the radius of curvature along cross sections, is similar in small and large ants.

[Are the first repetitive reentrant VPCs a trigger or an initiation of reentrant circuit for VPCs?: Evaluation by Holter ECG in patients with reentrant sustained ventricular tachycardia].

To evaluate whether the first repetitive reentrant VPCs are a trigger or an initiation of a reentrant circuit for VPCs, we studied Holter ECGs in 13 patients with sustained ventricular tachycardia, the morphology of reentrant VPCs, the relationship between the coupling interval (N-V) and the first ventricular cycle length (V-V), and the relationship of the coupling interval (N-V) between single VPC and repetitive VPCs. In 7 patients who showed episodes of repetitive VPCs more than twice on one recording of Holter ECG, most of VPCs in the first and second beats were the same in shape (1195 out of 1466 episodes, 82%). No obvious relationship between the coupling interval (N-V) and the first ventricular cycle length (V-V) was found in 5 patients, whereas a weak inverse relationship (r = 0.32) was found in one patient, and a weak positive relationship (r = 0.38) was found in another patient. In addition, the coupling interval in repetitive VPCs was longer than that in single VPCs in 4 out of 7 patients. These results imply that, in most cases, the first VPC is the expression of initiation of a reentrant circuit for repetitive reentrant VPCs developing spontaneously.

[Evaluation of myocardial oxygen extraction dynamics in syndrome X by continuous measurement of coronary sinus oxygen saturation and its relation to clinical features].

We investigated the relation of myocardial oxygen extraction dynamics to pathophysiology and clinical features in syndrome X. In patients with syndrome X who underwent cardiac catheterization, coronary sinus oxygen saturation (n = 21) during rapid atrial pacing loading was continuously measured using a fiberoptic catheter system, and global and regional left ventricular function (n = 14) was evaluated before and immediately after pacing loading. Results were as follows: 1) In 5 of 21 patients with syndrome X, coronary sinus oxygen saturation during pacing loading fell less than 5% below the baseline without any impairments of global and regional left ventricular function. 2) In 16 patients with syndrome X, coronary sinus oxygen saturation during the pacing loading continuously fell over 5% below the baseline accompanied by impairment of both global and regional left ventricular function. The decrease in regional wall motion of the left ventricle was mainly observed in the apical area. These findings imply that changes in myocardial oxygen extraction dynamics in syndrome X during rapid atrial pacing may show the extent of a patchy area where myocardial oxygen demand-supply imbalance occurs due to coronary microcirculatory disturbances.

[Continuous monitoring of coronary venous oxygen saturation during PTCA and its relation to electrocardiographic ST changes].

The purpose of this study was to investigate change in coronary venous oxygen saturation (CSO2-Sat) during percutaneous transluminal coronary angioplasty (PTCA) and to compare the results with those of standard 12-lead ECGs (s-ECG) and epicardial ECG induced using an intracoronary guidewire (ic-ECG). CSO2-Sat was measured continuously in 10 patients undergoing PTCA; 5 patients with lesions in the left anterior descending coronary artery (LAD), one with lesions in the left circumflex artery (LCX), and 4 with right coronary artery (RCA) lesions. The results were as follows: 1. In all 6 patients with stenotic lesions in the left coronary artery, CSO2-Sat decreased by 5 to 22% immediately after balloon inflation. Significant changes in ic-ECG (ST deviation > or = 0.1 mV) were observed in 5 of the 6 patients, while significant changes in s-ECG (ST deviation > or = 0.1 mV) were observed in only 3 of the 6 patients. The s-ECG did not seem to be sensitive enough to represent myocardial ischemia in the LCX. 2. The interval from the balloon inflation to the significant change was shorter for CSO2-Sat than for the ECGs in 4 of the 5 patients with LAD lesions, except Case 4. The recovery time of CSO2-Sat to the basal level on balloon deflation was longer than the recovery times of ic-ECG and s-ECG. 3. There was no significant change in the CSO2-Sat in 3 of the 4 patients undergoing PTCA for RCA lesions, while significant changes were observed in the ic-ECG and s-ECG in all 4 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Inverse relationship between coronary flow velocity and myocardial oxygen extraction during intracoronary infusion of papaverine].

The relationship between coronary blood flow velocity (CBFV) and myocardial oxygen extraction (O2-Ext) was investigated during rapid changes of CBFV after intracoronary papaverine infusion. In 6 patients without stenosis of the left anterior descending artery (LAD), one with hypertrophic cardiomyopathy, 2 with syndrome X and 3 with effort angina pectoris, simultaneous measurements of CBFV using the Doppler catheter system and coronary venous oxygen saturation using the fiberoptic catheter system were continuously performed before and during intracoronary infusion of papaverine. When O2-Ext was related to CBFV in every cardiac cycle, there was a good, inverse linear relationship, both in the increase (r = 0.81 +/- 0.24) and decrease (r = 0.93 +/- 0.04) phases of CBFV. The increase in cross-sectional area of segment 6 in the LAD as observed on orthogonal coronary angiograms was 6.0 +/- 2.0%. These results imply that the increase in CBFV during intracoronary papaverine infusion seems parallel to that of coronary blood flow, and that papaverine induces no significant change in myocardial oxygen consumption. Myocardial oxygen extraction in response to changes in coronary flow is regulated readily to meet the myocardial oxygen demand.

[Correlations between redistribution areas observed on exercise thallium-201 myocardial SPECT images and the coronary collateral circulations in patients with myocardial infarction].

The significance of coronary collateral circulation for redistribution in the infarcted zone was evaluated in 16 patients with history of myocardial infarction and severe stenosis (> or = 90%) of the coronary artery. Redistribution areas were quantitatively measured using the redistribution ratios and redistribution indices on the infarction-redistribution map obtained by thallium-201 scintigraphy with single photon emission computed tomography. Coronary collateral findings were categorized in 4 classes according to the Rentrop's grading. There was good, positive linear correlation between the redistribution ratio (Y) and collateral grading (X) (Y = 0.21X + 0.10, r = 0.92, p < 0.01). The redistribution index (X) also correlated well with the collateral grading (Y) using a good, positive quadratic equation (Y = 0.32X2 + 0.24X + 0.04, r = 0.89, p < 0.01). These results suggest that the measurements of the redistribution areas in the ischemic zone in myocardial infarction correlated well with collateral perfusion. Collateral perfusion severer than Rentrop's grade 2 markedly reduces the severity of ischemia and increases redistribution areas.

Learning and discrimination of coloured papers in the walking blowfly, Lucilia cuprina.

A new training and testing paradigm for walking sheep blowflies, Lucilia cuprina, is described. A fly is trained by presenting it with a droplet of sugar solution on a patch of coloured paper. After having consumed the sugar droplet, the fly starts a systematic search. While searching, it is confronted with an array of colour marks consisting of four colours displayed on the test cardboard (Fig. 1). Colours used for training and test include blue, green, yellow, orange, red, white and black. Before training, naive flies are tested for their spontaneous colour preferences on the test array. Yellow is visited most frequently, green least frequently (Table 2). Spontaneous colour preferences do not simply depend on subjective brightness (Table 1). The flies trained to one of the colours prefer this colour significantly (Figs. 5 and 9-11). This behaviour reflects true learning rather than sensitisation (Figs. 6-7). The blue and yellow marks are learned easily and discriminated well (Figs. 5, 9, 11). White is also discriminated well, although the response frequencies are lower than to blue and yellow (Fig. 11). Green is discriminated from blue but weakly from yellow and orange (Figs. 5, 9, 10). Red is a stimulus as weak as black (Figs. 8, 9). These features of colour discrimination reflect the spectral loci of colours in the colour triangle (Fig. 14). The coloured papers seem to be discriminated mainly by the hue of colours, but brightness may also be used to discriminate colour stimuli (Fig.13).

Visual learning in walking blowflies, Lucilia cuprina.

The Australian sheep blowflies Lucilia cuprina were trained by presenting droplets of sugar solution on a light spot of blue (460 nm wavelength) or green (520 nm wavelength). During the test, the searching behaviour was elicited by sugar stimulation. Then, the flies were allowed to walk in the arena where four coloured spots (two blue and two green) with light intensities similar to the training light were exhibited. Visits at these coloured spots were recorded. The flies visited preferably the light spot of the colour to which they had been trained. Next, the flies were trained to a light spot of blue or green displayed in various intensities, and later tested to discriminate between these two colours displayed in fixed intensities. The flies preferred the trained colour over the untrained one irrespective of the intensity used during training. It was only at the lowest intensity that they showed random orientation. These results suggest that the flies can learn to visit a coloured spot, and that they can discriminate between colours on the basis of wavelength rather than intensity. Training caused the flies not only to increase the probability of visiting the trained colour, but also to extend the proboscis and to elicit a characteristic searching behaviour once they had reached the coloured spot.

Gas-chromatographic determination of environmental gases with the application of thermal desorption from charcoal disk.

Direct measurement of the gases adsorbed on charcoal disk was examined by the gas-chromatograph with thermal desorption devices to improve the inadequacies of the common passive monitor. Since the most satisfactory values were obtained by a preliminary experiment with toluene vapor, the experiments were done with concentrations of 20, 40 and 80 ppm, respectively to get a linear relationship between the mean adsorption per piece and the concentration of toluene. Adsorption on the charcoal disk, and its extraction by carbon disulfide without degeneration, are the necessary conditions for the measurement of gas concentration. Methanol was selected as typical from among the gases for which the common passive monitor is inapplicable. The experiment on methanol was carried out in a manner similar to that done on toluene. In conclusion, our method was found to be satisfactory for the analysis of toluene, and, if the conditions are appropriate, for methanol.