Positive dT Research Articles

Influence of gravity wave temperature anomalies and their vertical gradients on cirrus clouds in the tropical tropopause layer – a satellite-based view

Abstract. Negative temperature perturbations (T′) from gravity waves are known to be favorable to tropical tropopause layer (TTL) clouds, and recent studies have further suggested a possible role of dT′/dz in facilitating TTL cloud formation and maintenance. With a focus on exploring the influence of dT′/dz on TTL clouds, this study utilizes radio occultation temperature retrievals and cloud layers from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) to understand how gravity wave perturbations modulate cloud occurrence in the tropics. Cloud populations were evaluated in four phases corresponding to positive or negative T′ and dT′/dz. We find that 55 % of TTL clouds are found where T′ and dT′/dz are both negative. Regions of frequent convection are associated with higher cloud populations in the warm phase T′>0. We show that the partitioning of cloud population among wave phases exhibits dependence on background relative humidity. In the phase where T′ and dT′/dz are both negative, the mean cloud effective radius is the smallest of all four phases, but the differences are small. It is shown that the strongest mean negative T′ anomaly is centered on the cloud top, resulting in positive dT′/dz above the cloud top and negative dT′/dz below. This negative T′ anomaly propagates downward with time, characteristic of upward propagating gravity waves. Negative (positive) T′ anomalies are associated with increased (decreased) probability of being occupied by clouds. The magnitude of T′ correlates with the increase or decrease in cloud occurrence, giving evidence that the wave amplitude influences the probability of cloud occurrence. While the decrease in cloud occurrence in the warm phase is centered on the altitude of T′ maxima, we show that the increase in cloud occurrence around T′ minima occurs below the minima in height, indicating that cloud formation or maintenance is facilitated mainly inside negative dT′/dz. Together with existing studies, our results suggest that the cold phase of gravity waves is favorable to TTL clouds mainly through the region where dT′/dz is negative.

Pressure dependence of glass transition in As2Te3 glass.

Amorphous solids prepared from their melt state exhibit glass transition phenomenon upon heating. Viscosity, specific heat, and thermal expansion coefficient of the amorphous solids show rapid changes at the glass transition temperature (Tg). Generally, application of high pressure increases the Tg and this increase (a positive dT(g)/dP) has been understood adequately with free volume and entropy models which are purely thermodynamic in origin. In this study, the electrical resistivity of semiconducting As(2)Te(3) glass at high pressures as a function of temperature has been measured in a Bridgman anvil apparatus. Electrical resistivity showed a pronounced change at Tg. The Tg estimated from the slope change in the resistivity-temperature plot shows a decreasing trend (negative dT(g)/dP). The dT(g)/dP was found to be -2.36 °C/kbar for a linear fit and -2.99 °C/kbar for a polynomial fit in the pressure range 1 bar to 9 kbar. Chalcogenide glasses like Se, As(2)Se(3), and As(30)Se(30)Te(40) show a positive dT(g)/dP which is very well understood in terms of the thermodynamic models. The negative dT(g)/dP (which is generally uncommon in liquids) observed for As(2)Te(3) glass is against the predictions of the thermodynamic models. The Adam-Gibbs model of viscosity suggests a direct relationship between the isothermal pressure derivative of viscosity and the relaxational expansion coefficient. When the sign of the thermal expansion coefficient is negative, dT(g)/dP = Δk/Δα will be less than zero, which can result in a negative dT(g)/dP. In general, chalcogenides rich in tellurium show a negative thermal expansion coefficient (NTE) in the supercooled and stable liquid states. Hence, the negative dT(g)/dP observed in this study can be understood on the basis of the Adams-Gibbs model. An electronic model proposed by deNeufville and Rockstad finds a linear relation between Tg and the optical band gap (Eg) for covalent semiconducting glasses when they are grouped according to their average coordination number. The electrical band gap (ΔE) of As(2)Te(3) glass decreases with pressure. The optical and electrical band gaps are related as Eg = 2ΔE; thus, a negative dT(g)/dP is expected when As(2)Te(3) glass is subjected to high pressures. In this sense, As(2)Te(3) is a unique glass where its variation of Tg with pressure can be understood by both electronic and thermodynamic models.

Impact of Sequence Non-Identities on Recombination within the <i>pil</i> System of <i>Neisseria gonorrhoeae</i>

Neisseria gonorrhoeae engages in extensive intra-cellular gene conversion between the PilE-expression locus (pilE) and the transcriptionally-silent pil gene copies (pilS). In silico analyses were applied to investigate the extent of sequence heterogeneity between the various pilS gene copies. Analysis of synonymous and non-synonymous substitutions between the different pilS genes indicated that relatively few amino acid changes would occur due to nucleotide polymorphisms towards the 5’ end of the pilS genes whereas more frequent amino acid substitutions would be incorporated within the “hypervariable” region. The lack of non-synonymous substitutions at the 5’ end of the genes was found to be under selective pressure as indicated by a positive DT score utilizing the Tajima test. The presence or absence of mismatch repair appeared to only impact recombination when non-identical DNAs recombined via the DNA transformation route, where small pil sequence heterogeneities were sufficient to terminate recombination tracts, with these sequence constraints being relieved in cells carrying a mutS mutation. Therefore, the data indicate that the effect of sequence heterogeneity on recombination within the pil system appears to depend upon the context with which the non-identical DNAs recombine.

Pressure dependence of the superconducting transition temperature of the filled skutterudite YFe4P12

We have studied the pressure dependence of the superconducting transition temperature T-c of the filled skutterudite YFe4P12 under various quasihydrostatic pressures up to 8 GPa. DC magnetization measurements up to 1.2 GPa in a piston-cylinder cell yields a linear increase of T-c with a positive coefficient dT(c)/dP = 1 K/GPa. Resistivity measurements up to 8 GPa in a cubic anvil apparatus show that Tc increases to 9.3 K at 8 GPa, but the slope decreases gradually with increasing pressure. Besides the previously reported LaFe4P12, YFe4P12 becomes the second filled skutterudite superconductor that exhibits a positive pressure coefficient dT(c)/dP in a broad pressure range. The observed large dT(c)/dP > 0 of YFe4P12 can be rationalized by our band-structure calculations that show an enhancement of density of states at Fermi energy and the Hopfield parameter under pressure at least up to 8 GPa. On the other hand, similar calculations predict a dT(c)/dP < 0 for YRu4P12.

HIGH SPECTRAL RESOLUTION MEASUREMENT OF THE SUNYAEV–ZEL'DOVICH EFFECT NULL WITH Z-Spec

The Sunyaev-Zel'dovich (SZ) effect spectrum crosses through a null where dT_CMB = 0 near nu_0 = 217 GHz. In a cluster of galaxies, nu_0 can be shifted from the canonical thermal SZ effect value by corrections to the SZ effect scattering due to the properties of the inter-cluster medium. We have measured the SZ effect in the hot galaxy cluster RX J1347.5-1145 with Z-Spec, an R ~ 300 grating spectrometer sensitive between 185 and 305 GHz. These data comprise a high spectral resolution measurement around the null of the SZ effect and clearly exhibit the transition from negative to positive dT_CMB over the Z-Spec band. The SZ null position is measured to be nu_0 = 225.8 \pm 2.5 (stat.) \pm 1.2 (sys.) GHz, which differs from the canonical null frequency by 3.0 sigma and is evidence for modifications to the canonical thermal SZ effect shape. Assuming the measured shift in nu_0 is due only to relativistic corrections to the SZ spectrum, we place the limit T_e = 17.1 \pm 5.3 keV from the zero-point measurement alone. By simulating the response of the instrument to the sky, we are able to generate likelihood functions in {y_0, T_e, v_pec} space. For v_pec = 0 km/s, we measure the best fitting SZ model to be y_0 = 4.6 (+0.6, -0.9) x 10^-4, T_e,0 = 15.2 (+12,-7.4) keV. When v_pec is allowed to vary, a most probable value of v_pec = +450 \pm 810 km/s is found.

Perturbative Study of Strong Coupling Correction in Superfluid 3He in Aerogel

The AB transition curve of superfluid 3He in aerogel often shows a positive slope dT AB(P)/dP>0 over the measured pressures P, contrary to that of the bulk liquid. Bearing this behavior in mind suggestive of a unexpectedly strong reduction of the strong coupling (SC) correction due to the aerogel, we examine impurity effects on the SC contributions to the quartic term of the Ginzburg-Landau (GL) functional. Our analysis perturbative both in the repulsive interaction and the impurity scattering suggests that, in agreement with experimental data, the impurity scattering weakens the relative stability of the ABM state to the BW state and notably reduces the SC correction for the ABM phase.

A New Echocardiographic Index for Assessing Left Ventricular Function and Mechanism of Mitral Regurgitation and Its Relation to Other Echocardiographic Indices

Mitral regurgitation (MR) is a progressive disease of the mitral valve, which can be primary or functional. The assessment of left ventricular function in MR is still troublesome. In this study, we evaluated the validity of a new parameter, total dt, in patients with MR. Forty patients with severe MR constituted the study group. According to the transesophageal echocardiographic evaluation, the patients were dichotomized into two groups: (1) Primary MR; n = 21, (2) Functional MR; n = 19. The total dt was defined as the sum of time intervals from 1 msto 3 ms (positive dt) and from 3 ms to 1 ms (negative dt) on the CW Doppler recording of MR jet. It was compared to other indices of left ventricular function and left ventricular geometry, including ejection fraction, fractional shortening, myocardial performance index, coaptation distance, left ventricular volume and diameter, sphericity index, and parameters of diastolic function. The total dt correlated with myocardial performance index, coaptation distance, and sphericity index. It could differentiate between primary and functional MR with an area under curve of 0.878, followed by myocardial performance index with 0.860. The total dt > 104 ms was 79% sensitive and 81% specific for discrimination. The total dt is useful for assessing left ventricular function and also for differentiating primary MR from functional MR.

Quantitative detection of Streptococcus mutans in the dental plaque of Japanese preschool children by real-time PCR

To detect quantitatively the total bacteria and Streptococcus mutans in dental plaque by real-time PCR with prbac, Sm and GTF-B primers, and to compare their presence with the prevalence of dental caries in Japanese preschool children. Human dental plaque samples were collected from the labial surfaces of the upper primary central incisors of 107 children. The dental status was recorded as dft by WHO caries diagnostic criteria. Positive dt and dft scores by the Sm or GTF-B primer were significantly higher than negative scores (P < 0.01). The proportions of Strep. mutans to the total bacteria from sound, and sound and/or filled upper primary incisors were significantly lower than those from decayed or filled, and decayed incisors, respectively (P < 0.01). The ratios of Strep. mutans to total bacteria in plaque detected by real-time PCR with Sm and GTF-B primers were closely associated with the prevalence of dental caries in Japanese preschool children. These assays may be useful for the assessment of an individual's risk of dental caries.

Volume Changes during Melting and Heating of Zinc and Cadmium Tellurides

The method of penetrating γ-radiation is used to investigate the temperature dependence of the density of condensed phases of zinc and cadmium tellurides in the vicinity of the melting point and to determine volume changes during transition from the solid to liquid state. The density of zinc telluride in the liquid phase is investigated for the first time. It is demonstrated that, during melting, the density of both investigated compounds decreases and continues to decrease linearly on heating in the liquid state. It is noted that, in accordance with Regel's classification, zinc and cadmium tellurides melt down by the semiconductor–semiconductor pattern. The volume changes of the investigated compounds during melting are analyzed using the Clausius–Clapeyron equation. The pressure coefficients of the melting temperature of these compounds are estimated, and it is noted that they are positive (dT / dp > 0). The thermal expansion of zinc and cadmium tellurides in the solid and liquid phases is analyzed; the equation of Sirota is used to calculate the characteristic Debye temperatures from which the mean-square dynamic displacements of atoms from the equilibrium position in the structure of condensed phases are determined at the melting point of the investigated compounds.

Superconductivity and charge redistribution under high pressure in the underdoped La 1.916Sr 0.084CuO 4

Unusual pressure-induced broadening of superconducting transition was observed in La 1.916Sr 0.084CuO 4 without excess oxygen by ac resistance measurement (acR) and mutual inductance measurement (acM). Above ∼ 9kbar, a negative dT c/dP determined by acM and a positive dT c/dP determined by acR are observed, while below ∼ 9 kbar, both dT c/dP are positive in sign and identical in magnitude. This suggests the occurrence of the intralayer charge redistribution induced by pressure.

Cardiac complications in noncardiac surgery: Value of dobutamine stress echocardiography versus dipyridamole thallium imaging

The objective of this study was to determine the relative value of dobutamine stress echocardiography (DSE) and dipyridamole thallium imaging (DT) in the preoperative assessment of cardiovascular risk before noncardiac surgery. Prospectively DSE was performed in patients who had undergone DT as a part of their preoperative evaluation. A large urban veterans' affairs medical center. Thirty-seven patients undergoing major noncardiac surgery were assessed for complications during a 1-month follow-up period. Both DSE and DT were performed before surgery. The medium interval between the two tests were 15.5 days. Left ventricular wall motion was assessed at baseline and peak dobutamine dose in a standard fashion. Wall motion was scored and indexed using a 16-segment model. A positive DSE was defined as failure of augmentation, new or worsening of baseline wall motion abnormalities in two or more contiguous segments. Myocardial perfusion studies after DT were performed according to conventional method. A positive DT was defined as a reversible perfusion defect, increased lung uptake, and/or transient left ventricular dilatation. Complications were defined as myocardial infarction or cardiac death occurring as a result of the operation, or need for revascularization before surgery. DSE was positive in 19 patients, whereas DT was positive in 25 patients. Fourteen patients had both an abnormal DSE and DT. Five patients had major postoperative cardiac complications: fetal myocardial infarction (1); fatal cardiac arrest (1); and severe coronary artery disease necessitating coronary artery bypass surgery (2) or percutaneous transluminal coronary angioplasty (1). DSE was positive in all 5 (100%), whereas DT was positive in 4 of 5 (80%) patients with complications. The sensitivity for each test was comparable: for DSE it was 100% (95% C.I. 56% to 100%) and for DT 80% (37% to 96%). Specificity for DSE (60%, 43%-74%) was somewhat higher than DT (38%, 24% to 54%), although this did not reach statistical significance (p = 0.06). The ability of DSE to predict major cardiac complications related to noncardiac surgery appears to be similar to DT and may be used as an alternative to DT imaging in the preoperative risk assessment of patients undergoing noncardiac surgery.

High-pressure studies on superconducting Ba 1−xK xBiO 3 single crystal

We report the effects of hydrostatic pressure on the normal state resistivity and critical superconducting temperature T c of a Ba 1−xK xBiO 3 single crystal. We found that conductivity and Tc increase under pressure. The positive initial slope dT c/dP is equal to 3.8×10 −2K/kbar. For P>62; 15kbar both conductivity and T c saturate. The positive dT c/dP derivative is surprisingly opposite to what is observed on BaBi xPb 1−xO 3 and it can be compared to that measured on cuprate superconductors.

Acute haemodynamic effects of dopexamine in patients with coronary arterial disease

We assessed the acute haemodynamic effects of dopexamine 1 μg/kg/min and 3 μg/kg/min in 21 patients with coronary arterial disease following routine catheterisation. Patients were aged 38 to 72 years and left ventricular ejection fraction ranged from 23 to 79%. Dopexamine was well tolerated in all patients except one in whom transient ventricular arrhythmias occurred with 3 μg/kg/min. No patient developed angina. Dopexamine increased cardiac index (2.6 ± 0.4 to 3.2 ± 0.1 ( P < 0.001) and 4.0 ± 1.0 l/min/m 2 ( P < 0.001), control to 1 μg/kg/min and 3 μg/kg/min, respectively) and decreased systemic vascular resistance index (3356 ± 1506 to 2318 ± 809 ( P < 0.001) and 2252 ± 1973 dyne · sec · cm −5/m 2 ( P < 0.001)), but did not affect systemic arterial, pulmonary arterial or right atrial pressure. Maximum positive dP dt was increased (1294 ± 324 to 1597 ± 505 ( P < 0.001) and 2199 ± 819 mmHg/sec ( P < 0.001)) as was left ventricular stroke work index (44 ± 20 to 51 ± 21 ( P < 0.05) and 56 ± 27 g · m/m 2 ( P < 0.001) control to 1 μg/kg/min and 3 μg/kg/min, respectively). Left ventricular end diastolic pressure fell with 3 μg/kg/min from 19.8 ± 6.9 to 12.4 ± 4.6 mmHg ( P < 0.05) in patients with preserved left ventricular ejection fraction (> 50%, n = 6), but not in those with impaired left ventricular ejection fraction (< 50%, n = 15), otherwise the effects in these two subgroups were similar. We conclude that dopexamine has both inotropic and vasodilator properties. Despite increasing left ventricular stroke work index and contractility it is well tolerated by patients with ischaemic heart disease, and would therefore be useful in the treatment of acute cardiac failure in this group of patients.

Direct effect of hypoglycemic sulphonylureas on the cardiovascular system of dogs

The effects of first generation sulphonylurea compounds carbutamide, gliclazide and tolbutamide as well as second generation compounds glibenclamide and glipizide on the cardiovascular system were investigated in dogs. Six dogs received each compound intravenously at cumulative dose levels of 74, 296, 1184 μmol/kg of carbutamide and tolbutamide, 0.4, 2.0, 10.0 μmol/kg of glibenclamide and glipizide, and 16, 48 and 144 μmol/kg of gliclazide. Mean arterial blood pressure, myocardial contractile force, cardiac output and heart rate were measured. The rate of change of myocardial contractile force development (positive dF dt ), as well as of myocardial relaxation (negative dF dt ) were measured. The first generation sulphonylureas were found, in dogs, to exert a positive inotropic effect in contrast to second generation compounds. The clinical importance of our findings may be in the potential for the malfunction of the cardiovascular system (based on cardiopathy, neuropathy, atherosclerosis, and obesity), developing in diabetes, to be further impaired by the first generation sulphonylureas. Therefore, second generation sulphonylureas should be preferred in the therapy of type 2 diabetics, if satisfactory metabolic control cannot be achieved by dietary management alone and sulphonylurea treatment becomes necessary.

Are ioxaglate and iopamidol equally safe and well tolerated in cardiac angiography? A randomized, double-blind clinical study

A randomized, double-blind, parallel-group study was performed in 50 patients undergoing left ventriculography and coronary arteriography to evaluate ECG changes and the effects on left ventricular function of a low-osmolar lonic contrast agent, ioxaglate, as compared with a low-osmolar nonionic contrast medium, iopamidol. Twenty-five patients received ioxaglate (group 1) and 25 patients received iopamidol (group 2). All patients underwent 48 hours of continuous ECG recording beginning 24 hours before the cardiac catheterization. Left ventricular systolic and end-diastolic pressure, peak positive dp dt , and dp/dt/P ratio were measured immediately before and after left ventriculography and 3 minutes later. Left ventricular systolic pressure did not change after injection of either contrast medium. Left ventricular and-diastolic pressure increased by 30% in group 1 ( p < 0.01) and by 22% in group 2 ( p < 0.01) immediately after left ventriculography. A further increase by 45% in group 1 ( p < 0.01) and by 24% in group 2 ( p < 0.01) was observed 3 minutes later. No differences were observed between values obtained in the two groups. Peak positive dp dt did not change immediately after injection of either contrast medium but decreased by 5% (not significant) in group 1 and by 7% ( p < 0.02) in group 2 three minutes after left ventriculography. There were no significant differences between the two groups. Analysis of continuous 48-hour ECGs showed that both ioxaglate and iopamidol induced a slight increase (by 8% and 7%, respectively; p < 0.05) in heart rate during injection with early and complete recovery. A significant increase in the frequency of ventricular premature complexes (total number/1000/hr) was observed in group 2 during the injection period and during the first hour after completion of contrast injection with respect to the extreme intervals ( p < 0.05). Furthermore, bigeminal rhythm, pairs, and R-on-T ventricular premature complexes increased by 24% in group 1 and by 636% in group 2 ( p < 0.02) during injection. PR interval, QRS width, corrected QT interval and ST segment did not change throughout the study. Thus results of our study show that despite simillar effects of ioxaglate and iopamidol on left ventricular function, the occurrence of potentially harmful ventricular arrhythmias is more frequent with iopamidol.

Cardiovascular effects of intracoronary atrial natriuretic peptide administration in man

An intracoronary drug infusion protocol was employed to assess the hemodynamic effects of synthetic atrial natriuretic peptide in normal subjects and to evaluate its actions on epicardial coronary artery dimensions. Increasing concentrations of synthetic atrial natriuretic peptide (1.75 to 84 μg/min) were infused at a constant rate directly into the left coronary artery in eight patients with normal left ventricular function and left coronary artery angiograms. Steady-state hemodynamic parameters and high-fidelity left ventricular pressure were recorded at each dose and indexes of left ventricular contractile and diastolic function were calculated. Coronary angiograms obtained at baseline and the highest dose of atrial natriuretic peptide were compared by quantitative image analysis techniques. At the highest dose administered, atrial natriuretic peptide decreased mean pulmonary artery pressure (−36%, p < 0.01), pulmonary capillary wedge pressure (−80%, p < 0.01), left ventricular end-diastolic pressure (−58%, p < 0.01), left ventricular end-systolic pressure (−11%, p < 0.01), mean arterial pressure (−8%, p < 0.05), and pulmonary vascular resistance (−18%, p < 0.05). Cardiac output and systemic vascular resistance were unchanged, and heart rate and peak positive dP dt increased. Peak negative dP dt and the time constant of early diastolic relaxation calculated by the logarithmic method both fell at the highest dose of atrial natriuretic peptide, although the time constants calculated by other less load-sensitive methods were unchanged. Doses of intracoronary atrial peptide that did not alter left ventricular load had no effect on indexes of left ventricular systolic or diastolic function despite a presumably high intramyocardial concentration of the agent. Epicardial coronary artery diameter and calculated cross-sectional area were measured in 40 segments of the left anterior descending and left circumflex coronary arteries in eight subjects before and after atrial peptide administration. Mean coronary diameter increased 27%, from 2.05 ± 0.19 to 2.61 ± 0.21 mm ( p = 0.0001), in the left anterior descending artery and increased 26%, from 2.11 ± 0.16 to 2.65 ± 0.18 mm ( p = 0.0001), in the left circumflex artery; cross-sectional area increased an average of 54 ± 11% ( p < 0.001). There were no side effects related to atrial peptide administration. These results indicate that in normal subjects atrial natriuretic peptide lowers blood pressure without direct myocardial effects and dilates epicardial coronary arteries.

Usefulness of the dipyridamole-Doppler test for diagnosis of coronary artery disease

Two-dimensional and Doppler echocardiographic studies and a hemodynamic investigation were performed during dipyridamole testing in 42 subjects (13 control subjects and 29 patients with coronary artery disease [CAD]), to evaluate the ability of dipyridamole Doppler echocardiography in identifying patients with ischemic left ventricular dysfunction. In the control group, after dipyridamole infusion, Doppler-derived parameters increased significantly from baseline (p < 0.001). In patients with CAD, peak flow velocity, flow velocity integral and stroke volume failed to increase after dipyridamole infusion (0.89 ± 0.21 to 0.85 ± 0.18 m/s, difference not significant; 14 ± 3 to 12 ± 4 cm, difference not significant, and 56 ± 13 to 50 ± 14 ml/ beat, p < 0.05, respectively). Heart rate, rate pressure product, systemic vascular resistance and mean right atrial pressure had similar variations in the 2 groups. Changes in the 3 Doppler-derived parameters are closely related to the variations of peak positive dP dt , stroke volume (thermodilution) and left ventricular end-diastolic pressure and are closely related to the coronary angiography jeopardy score and to the appearance of wall motion abnormalities. Thus, by combining Doppler and 2-dimensional echocardiography, dipyridamole-induced myocardial ischemia may be detected in a high percentage of CAD patients, providing a sensitive tool for identifying patients with high-risk coronary artery anatomy.

Regional and global biventricular function during dipyridamole stress testing

This study assesses the relation between regional ventricular performance (using 2-dimensional echocardiography) and global systolic and diastolic indexes of biventricular myocardial function (using hemodynamic monitoring) during dipyridamole stress testing. Simultaneous 2-dimensional echocardiographic and biventricular hemodynamic monitoring during dipyridamole infusion (0.56 mg/kg over 4 minutes) was performed in 19 patients. All patients had a normal resting function. Eleven of the 19 patients had a positive echocardiography test (new wall motion dyssynergy with dipyridamole) and they formed group 1. Eight patients had a negative echocardiography test (group 2). During baseline conditions, no significant differences were found in the 2 groups: rate pressure product ( 107 ± 16 vs 108 ± 13 mm Hg × beats/min × 1 100 ), positive left ventricular (LV) dP dt (1,950 ± 473 vs 2,262 ± 430 mm Hg/s), negative LV dP dt (−2,069 ± 620 vs −2,205 ± 245), LV end-diastolic pressure (8.2 ± 4.4 vs 9.6 ± 4.0 mm Hg), right ventricular positive dP dt (368 ± 133 vs 400 ± 190 mm Hg/s) and negative dP dt (−281 ± 89 vs −383 ± 147). At peak dipyridamole, the 2 groups were different for LV end-diastolic pressure (20 ±10 vs 8 ± 5 mm Hg, p < 0.01), LV positive dP dt (2,100 ± 688 vs 3,013 ± 851 mm Hg/s, p < 0.01) and negative dP dt (−1,868 ± 518 vs −2,564 ± 272, p < 0.01). At peak ischemia, LV positive dP dt increased slightly, but not significantly, while negative dP dt decreased significantly (p < 0.01) in comparison with resting values. In the absence of ischemia, the effect of dipyridamole on LV function consists of an increase in peak positive and negative LV dP dt . Alterations in regional myocardial performance and global LV diastolic function provide more sensitive indexes of dipyridamole-induced ischemia than global systolic function.

Salmonella paratyphi B d-tartrate positif (var. java): Lysotypie de 1200 souches isolées en France (1975–1985)

The 1200 d-tartrate positive (dt+) strains of S. paratyphi B, isolated in France during the period 1975-1985, were studied with the aid of the Felix and Callow phage-typing system and the results were compared with those of the study of 1945 d-tartrate negative (dt-) strains of S. paratyphi B examined by means of the same phage-typing method. 2359 dt+ and dt- strains were typable and could be assigned to 25 recognized phage-types. A great variation in the number of strains of each biovar was observed in some phage-types. The proportion of dt+ strains was very high (more than 80%) in four of the most frequent phage-types: 1 var. 3 (87.5%), 1 var. 4 (88.1%), Battersea (90.4%), Worksop (100%); but this proportion was low or very low in eight other frequent phage-types: 1 (29%), BAOR (21.1%), 3aI var. 1 (6.1%), Beccles (5.1%), 3aI var. 4 (4.8%), Dundee (4.7%), 3aI (2.7%), Taunton (2.1%). No recognized phage-type found in France can be considered to be specific of the variety java of S. paratyphi B, with the exception of the phage-type Workshop of all which 76 strains were dt+. On the other hand, 422 dt+ strains were atypical and 93 other were untypable by phages. Among 211 dt+ strains isolated from frozen foods imported from South East Asia, 81.3% were atypical. Six new atypical phage-types were defined and proposed for inclusion into the phage-typing schema which is commonly used in epidemiological investigations on human and animal infections due to either of the two biovars of S. paratyphi B.

Recovery of systolic and diastolic left ventricular function after a 60-second coronary arterial occlusion during percutaneous transluminal coronary angioplasty for angina pectoris

Recovery of global and regional systolic and global diastolic left ventricular (LV) function was examined after 60 seconds of coronary arterial occlusion in 9 men without myocardial infarction undergoing elective percutaneous transluminal coronary angioplasty. Hemodynamic and electrocardiographic recordings and a simultaneous digital subtraction LV angiogram in the 30 ° right anterior oblique view were performed before coronary occlusion, after 60 seconds of the first 2 occlusions and at 20, 40, 60 and 90 seconds of reperfusion. Diastolic pressure-volume relations paired the digital volumes to corresponding high-fidelity analog pressures. Similar and significant depression of global ejection fraction, percent radial shortening in the jeopardized region, maximal positive dP dt and significant elevation of LV end-diastolic pressure and ST segments occurred with each 60-second coronary occlusion. All of these variables except LV end-diastolic pressure returned to control levels within 40 seconds of reperfusion. Significant elevation of the diastolic pressure-volume relation occurred with each coronary occlusion and progressively diminished to control values with 60 seconds of reperfusion. No statistically significant difference in any measurement occurred between the 2 occlusions and reperfusions at any point. This study shows that similar and significant depression and time course of recovery of global and regional systolic and global diastolic LV function accompanied each 60-second coronary occlusion with recovery of systolic function preceding recovery of diastolic function.