Left ventricular mass relates to average systolic blood pressure, but not loss of circadian blood pressure in stable hemodialysis patients: an ambulatory 48-hour blood pressure study.

Although left ventricular hypertrophy (LVH) is a common complication which contributes substantially to high cardiovascular mortality and morbidity in end-stage renal failure, whether changes in blood pressure and alterations of circadian variation of blood pressure occur between the hemodialysis (HD) day and the interdialytic day, and if so, whether they influence the left ventricular mass (LVM) remain unknown. Thirty-five consecutive stable patients who had had a hematocrit value greater than 25% for the previous 6 months, who had been on the same antihypertensive drugs during this period, and who underwent HD 3 times a week were included. Echocardiograms were recorded after HD and then ambulatory blood pressure monitoring was recorded every hour for 48 h. The mean interdialytic body weight gain was less than 5% of dry weight. Patients with LVH had a higher average systolic blood pressure (SBP) at predialysis, postdialysis, on the HD day and on the interdialytic day than those without LVH despite the higher antihypertensive therapy rate. The majority of patients with LVH showed concentric hypertrophy and higher plasma natriuretic peptide levels. Irrespective of the presence of LVH, the average blood pressure value did not change between the HD day and the interdialytic day, and a loss of circadian blood pressure variation was observed on both the HD and interdialytic days. Univariate analysis revealed that LVM was significantly correlated with the average SBP at predialysis, postdialysis, on the HD day, on the interdialytic day and over 48 h (r= 0.48, r=0.61, r=0.67, r=0.67, r=0.73, respectively; all p<0.05). Multiple regression analysis revealed that 48-h SBP was independently associated with the LVM index. These results suggest that neither the loss of circadian blood pressure variation nor the changes of blood pressure between the HD and interdialytic days was of major etiologic importance in the development of LVH, and that the absolute value of the 48-hour average SBP may be an important risk factor for concentric LVH in stable HD patients.

Supermolecular structure of the enteropathogenic Escherichia coli type III secretion system and its direct interaction with the EspA-sheath-like structure.

Enteropathogenic Escherichia coli (EPEC) secretes several Esp proteins via the type III secretion system (secreton). EspA, EspB, and EspD are required for translocation of the effector proteins into host cells, in which EspB and EspD are thought to form a pore in the host membrane. Recent study has shown that EspA forms a filamentous structure that assembles as a physical bridge between bacteria and host cell surfaces, which then functions as a conduit for the translocation of bacterial effectors into host cells. To investigate the supermolecular structure of the type III secreton in EPEC, we partially purified it from the bacteria membrane and observed it via transmission electron microscopy. The EPEC type III secreton was composed of a basal body and a needle part and was similar to those of Salmonella and Shigella, except for a sheath-like structure at the tip of the needle. The length of sheath-like structures varied; it extended more than 600 nm and was 10 times longer than the Shigella needle part. The putative major needle component, EscF, was required for both secretion of Esp proteins and needle complex formation. Interestingly, elongation of the sheath-like structure was observed under constitutive expression of EspA but not of EscF. Furthermore, the transmission electron microscopy view with immunogold labeled anti-EspA antibodies clearly showed that EspA is a component of the sheath-like structure. This study revealed, to our knowledge for the first time, the supermolecular structure of the EPEC type III secreton and its direct association with the EspA-sheath-like structure.

[Clinical significance of plasma atrial and brain natriuretic peptide levels during hemodialysis in hemodialysis patients with old myocardial infarction].

OBJECTIVES: The plasma levels of atrial natriuretic peptide(ANP) and brain natriuretic peptide(BNP) are useful to evaluate left ventricular function in patients with old myocardial infarction(OMI). This echocardiographic study examined the clinical importance of the measurement of ANP and BNP in patients with OMI undergoing hemodialysis. METHODS: ANP and BNP levels were measured before and after hemodialysis in 36 patients with OMI and 42 patients without ischemic heart disease as controls(control group). Echocardiography was performed after hemodialysis. The patients with OMI were classified into two groups according to left ventricular percentage fractional shortening(% FS): Normal(OMI-N) group with %FS > or = 30%(n = 19) and low (OMI-L) group with %FS < 30%(n = 17). RESULTS: The ANP, BNP levels and BNP/ANP ratio before and after hemodialysis were significantly higher in the OMI-L group than in the other groups. BNP level was significantly inversely correlated with %FS(r = -0.60, p < 0.05) and correlated with E wave and E/A, in mitral inflow only in the OMI-L group. The decrease in BNP level during hemodialysis was significantly greater in the OMI-L group than in the other groups, but not in ANP level. CONCLUSIONS: These findings suggest that ANP and BNP levels are increased in patients with left ventricular dysfunction undergoing hemodialysis compared to those with normal left ventricular function. ANP level is convenient for decision of suitable dry weight. In contrast, BNP level that correlated inversely with impairment of left ventricular function is a more sensitive index of left ventricular function than ANP in patients with OMI undergoing hemodialysis.

Shigella invasion of macrophage requires the insertion of IpaC into the host plasma membrane. Functional analysis of IpaC.

Shigella infects residential macrophages via the M cell entry, after which the pathogen induces macrophage cell death. The bacterial strategy of macrophage infection, however, remains largely speculative. Wild type Shigella flexneri (YSH6000) invaded macrophages more efficiently than the noninvasive mutants, where YSH6000 induced large scale lamellipodial extension including ruffle formation around the bacteria. When macrophages were infected with the noninvasive ipaC mutant, the invasiveness and induction of membrane extension were dramatically reduced as compared with that of YSH6000. J774 macrophages infected with YSH6000 showed tyrosine phosphorylation of several proteins including paxillin and c-Cbl, and this pattern was distinctive from those stimulated by Salmonella typhimurium or phorbol ester. Upon addition of IpaC into the external medium of macrophages, membrane extensions were rapidly induced, and this promoted uptake of Escherichia coli. The exogenously added IpaC was found to be integrated into the host cell membrane as detected by immunostaining. The IpaC domain required for the induction of membrane extension from J774 was narrowed down within the region of residues 117-169, which contains a putative membrane-spanning sequence. Our data indicate that Shigella directs its own entry into macrophages, and the IpaC domain which is required for the association with its host membrane is crucial.

[Analysis of factors influencing left ventricular mass and diastolic function in normotensive men].

OBJECTIVES: Increase in left ventricular weight is an important risk factor for the incidence of cardiovascular diseases, and reduction in diastolic function of the left ventricle is an early marker for cardiac dysfunction. Factors related to the left ventricular mass and diastolic function were analyzed in middle-aged normotensive men. METHODS: The subjects were 126 normotensive men aged 49 +/- 1 years who were hospitalized for health-checkup. In addition to physical examination and routine laboratory tests, echocardiography including the pulse-Doppler method was performed and urinary electrolyte excretions, plasma angiotensin II, plasma noradrenaline and the angiotensin converting enzyme genotype were examined. RESULTS: Left ventricular mass index was positively correlated with mean blood pressure (r = 0.249, p < 0.006) and body mass index (r = 0.279, p < 0.002). With regard to the index of left ventricular diastolic dysfunction, the late to early peak transmitral flow velocity ratio (A/E) was positively correlated with age (r = 0.465, p < 0.001) and urinary sodium excretion (r = 0.240, p < 0.007). Neither left ventricular mass index or A/E was affected by the angiotensin converting enzyme genotype and was not significantly correlated with plasma angiotensin II or noradrenaline. CONCLUSIONS: Increase in left ventricular mass is influenced by blood pressure and obesity, whereas reduction in left ventricular diastolic function is affected by greater age and salt intake.

Plasma brain natriuretic peptide levels in chronic hemodialysis patients: influence of coronary artery disease.

A noninvasive biochemical testing method for early detection and monitoring the condition of cardiac complications in hemodialysis (HD) patients would be useful and might lead to improved survival. The aim of this study is to clarify the pathophysiological significance of plasma brain natriuretic peptide (BNP) levels in HD patients with and without coronary artery disease (CAD). We measured plasma atrial natriuretic peptide (ANP) and BNP levels on Monday, Wednesday, and Friday before and after HD in 28 consecutive patients who underwent HD three times weekly. In addition, we measured plasma ANP and BNP levels in 21 HD patients with CAD and 27 HD patients without CAD and studied the relationships between BNP levels and cardiac function and clinical variables. Plasma ANP levels significantly decreased after HD on Monday, Wednesday, and Friday, and predialysis plasma ANP levels on Monday were significantly greater than those on other days. Plasma BNP levels did not change after HD on Monday; however, they significantly decreased after HD on Wednesday and FRIDAY: Predialysis plasma BNP levels on Monday were greater than those on other days, and postdialysis plasma BNP levels on Monday were greater than predialysis plasma BNP levels on WEDNESDAY: Plasma BNP levels in HD patients with CAD were significantly greater than those in HD patients without CAD and significantly correlated with left ventricular (LV) ejection fraction (r = -0.69), end-diastolic volume index (r = 0.59), and end-systolic volume index (r = 0.84) determined by left ventriculography. Conversely, plasma BNP levels in HD patients without CAD significantly correlated with LV mass index (r = 0.54) determined by echocardiography and mean systolic blood pressure (r = 0.72) determined by 48-hour ambulatory blood pressure monitoring. These results suggest the following: (1) plasma BNP levels before and after HD in chronic HD patients directly correlate with the degree of body fluid retention, and the day of the week on which the sample is obtained should be considered for its evaluation; (2) plasma BNP levels reflect LV function in HD patients with CAD; and (3) plasma BNP levels reflect LV mass and blood pressure in HD patients without CAD.

[Mid-ventricular obstructive hypertrophic cardiomyopathy associated with an apical aneurysm and sustained ventricular tachycardia: a case report].

A 60-year-old woman presented with mid-ventricular obstructive hypertrophic cardiomyopathy associated with an apical aneurysm and sustained ventricular tachycardia. She was admitted because of drug refractory ventricular tachycardia. She had been treated with several antiarrhythmic agents, including amiodarone, but symptomatic episodes had continued. Echocardiography, magnetic resonance imaging, and left ventriculography showed mid-ventricular obstructive hypertrophic cardiomyopathy with an apical aneurysm. Electrophysiological study easily reproduced sustained pleomorphic ventricular tachycardia, polymorphic ventricular tachycardia, and ventricular fibrillation. The patient underwent implantation of a cardioverter-defibrillator. The relationship between mid-ventricular hypertrophic cardiomyopathy and apical aneurysm is unknown, but mid-ventricular hypertrophic cardiomyopathy is one of the causes of severe ventricular arrhythmias and sudden death.

Supramolecular structure of the Shigella type III secretion machinery: the needle part is changeable in length and essential for delivery of effectors.

We investigated the supramolecular structure of the SHIGELLA: type III secretion machinery including its major components. Our results indicated that the machinery was composed of needle and basal parts with respective lengths of 45.4 +/- 3.3 and 31.6 +/- 0.3 nm, and contained MxiD, MxiG, MxiJ and MxiH. spa47, encoding a putative F(1)-type ATPase, was required for the secretion of effector proteins via the type III system and was involved in the formation of the needle. The spa47 mutant produced a defective, needle-less type III structure, which contained MxiD, MxiG and MxiJ but not MxiH. The mxiH mutant produced a defective type III structure lacking the needle and failed to secrete effector proteins. Upon overexpression of MxiH in the mxiH mutant, the bacteria produced type III structures with protruding dramatically long needles, and showed a remarkable increase in invasiveness. Our results suggest that MxiH is the major needle component of the type III machinery and is essential for delivery of the effector proteins, and that the level of MxiH affects the length of the needle.

[Changes in the extent of mitral regurgitation during hemodialysis: color Doppler echocardiographic study].

The changes in the extent of mitral regurgitation (MR) during maintenance hemodialysis patients were studied in six patients with MR by color Doppler echocardiography. M-mode, two-dimensional and color Doppler echocardiography were performed before and every hour during hemodialysis. The severity of MR was evaluated by a semiquantitative grading system and maximal MR area. Hemodialysis removed 2.1 +/- 0.9/body fluid. Blood pressure and heart rate did not change systematically by hemodialysis. Left atrial, left ventricular end-diastolic and end-systolic dimensions were significantly decreased by hemodialysis (p < 0.05). Stroke volume and left ventricular wall stress were also significantly decreased (p < 0.01). MR area was significantly smaller at the end of hemodialysis compared to pre-hemodialysis (49.0 +/- 20.5 vs 171.0 +/- 49.2 mm2, p < 0.05). During hemodialysis, the extent of MR was continuously decreased. In two out of six patients, the MR jet disappeared. The extent of MR may depend on the fluid volume removed by hemodialysis because the MR area diminished more as more fluid was removed. No major disorders of the mitral complex were detected when the MR area was decreased rapidly to less than 60 mm2 in response to the removal of a small amount of fluid. The dry weight should be determined as the body weight when MR is as small as possible by color Doppler echocardiography.

New interpretation of systolic time intervals from active cross-bridge model.

Using an active cross-bridge model proposed by the authors, it has been established theoretically that cross-bridge activation rate (Ka) of the left ventricular myocardium, which might correspond to the rate of binding of Ca2+ with troponin C, is approximately expressed as a simple formula: Ka = 3/electromechanical systole (sec-1), although no definitive biological proof has yet been provided for the equation. One hundred eighteen patients without significant cardiac disease and 6 patients who had atrioventricular block with a permanent pacemaker were evaluated to determine the Ka value of the normal human left ventricular myocardium (test 1), and to examine the effect of changes in heart rate (test 2) as well as afterloading (test 3) or dobutamine infusion (test 4) on Ka. The pacing rate was increased from 50 to 110 beats/min at 20-beat increments in test 2. Arterial pressure was elevated by angiotensin II infusion in test 3, and 7 subjects received a continuous dobutamine infusion in test 4. The Ka value was found to be related to heart rate, to be increased by dobutamine infusion, and to be decreased by myocardial lengthening due to afterloading. Dependence of Ka on heart rate appeared to result from changes in myocardial length. The Ka value corrected for heart rate (Kac) had an average variation of only 4.6%, and was unrelated to age or myocardial length in individual subjects. Thus, the Kac value of normal human left ventricular myocardium appears to be nearly constant between individuals but to be increased by catecholamine infusion or myocardial shortening.

[The left ventricular force-length relationship in patients with heart failure].

A new contractility index (Ec) is proposed based on the slope of the left ventricular (LV) end-systolic force-length relationship. The Ec values of normal human hearts are relatively constant. The present study investigated the Ec values of 16 cases of heart failure in 11 patients with old myocardial infarction and 5 with dilated cardiomyopathy in NYHA functional class 1 to 3. The LV end-systolic pressure (Pes) and dimension (Des) were estimated simultaneously by intraarterial cannulation and LV echocardiography. The LV pressure decreased from 111 +/- 17 to 90 +/- 14 mmHg after intravenous infusion of nitroglycerin. The LV Fes-Des relationship was found to be nearly linear and the slope (Ec) and extrapolated dimension intercepts (Do) were obtained as 60 +/- 22 g/cm and 2.7 +/- 1.2 cm, respectively. The values of Ec and Do were both proportional to the baseline Des value. Our model predicts that the Ec value reflects intracellular peak Ca2+ concentrations ([Ca2+]) of the myocardium and/or myosin ATPase activity. The present results suggest that the working myocardium of a failing heart increases [Ca2+] and/or myosin ATPase activity to compensate for depressed LV pump function due to myocardial damage.

Slope of human left ventricular end-systolic force-length relation is independent of myocardial length.

We have introduced a new contractility index (Ec), i.e., the slope of the left ventricular (LV) end-systolic force-length (Fes-Les) relation. To examine whether Ec was dependent on the LV wall myocardial length, 16 normal hearts of human subjects were evaluated to determine the LV end-systolic force-dimension (Fes-Des) and pressure-dimension (Pes-Des) relations (dimension denotes the distance between the LV septum and posterior wall). LV end-systolic pressures and dimensions were estimated simultaneously by intra-arterial cannulation and LV echocardiography. In seven subjects, the effect of a dobutamine infusion was also assessed. The Fes-Des relation was found to be nearly linear. Slopes and extrapolated dimension intercepts were obtained for the LV Fes-Des and Pes-Des relations [Ec, slope of LV Pes-Des relation (Es), and extrapolated dimension intercept of LV Fes-Des (Do), and of Pes-Des relation (D'o), respectively]. Es showed a hyperbolic relation to the baseline LV Des, whereas Ec was unrelated to it. The average variation for Ec (9.5%) was smaller than that for Es (22.5%). Dobutamine infusion increased Ec, Es, and D'o, whereas Do was not changed. Thus the assumption of linearity of the LV Fes-Les relation was found to be reasonable in normal human hearts. Do appears to provide a more accurate parameter than D'o for estimating the actual unstressed myocardial length, whereas Ec could possibly serve as an index of LV wall performance in the normal human heart that is independent of myocardial length and nearly constant between individuals.

[Deterioration of myocardial contractility induced by nitroglycerin infusion in a case of ischemic cardiomyopathy].

To evaluate left ventricular (LV) contractility in a 42-year-old woman with ischemic cardiomyopathy, the brachial arterial pressure and LV end-systolic dimension were simultaneously measured using arterial cannulation and LV echocardiography. Blood pressure progressively decreased with the intravenous infusion of nitroglycerin. When the infusion rate reached 4 micrograms/kg/min, the LV end-systolic dimension increased from 63 mm (control) to 66 mm in association with a decrease in blood pressure (from 137 to 120 mmHg) and heart rate (from 103 to 100 bpm). With the infusion of dobutamine (1.5 micrograms/kg/min), the blood pressure increased to 126 mmHg and the LV end-systolic dimension decreased to 57 mm. These findings suggest that nitroglycerin reduced LV myocardial contractility in this patient. Thus, during the intravenous administration of nitroglycerin (especially in patients with ischemic heart disease), the infusion rate should be carefully determined.

[Relationship between left ventricular diastolic behavior and the A wave ratio by the apexcardiogram: a study with echocardiography and pulsed Doppler echocardiography].

We investigated the relationship between parameters of left ventricular diastolic filling using pulsed Doppler echocardiography and the A wave ratio of apexcardiography (ACG), and then evaluate the characteristic features of diastolic behavior in hypertrophic hearts and in various cardiac diseases. The study population consisted of 68 patients and 25 normal subjects, and included 19 cases of chronic renal failure (CRF), 17 cases of ischemic heart disease (IHD), 16 cases of hypertension (HT), six cases of hypertrophic cardiomyopathy, two cases of aortic stenosis, two cases of arrhythmias, and six of other cardiac diseases. The A wave ratio of ACG was calculated as the ratio of A wave amplitude and total excursion [(A/E-O) x 100]. At the same time, the peak early filling velocity (R), the peak late filling velocity (A), the ratio of R to A (A/R), acceleration time (AT), and deceleration time (DT) were measured from the left ventricular inflow velocity pattern using pulsed Doppler echocardiography. The results were as follows: 1. There was a close positive correlation between the A wave ratio of ACG and the A/R of pulsed Doppler echocardiography. 2. In patients with left ventricular hypertrophy (LVH), both the A wave ratio and the A/R were significantly higher than those in normal subjects. And in LVH with asynergy, both the A wave ratio and the A/R were significantly higher than those in LVH without asynergy. 3. In CRF, IHD, and HT, both the A wave ration and the A/R were significantly higher than those in normal subjects, but there were no significant differences among these three disease entities.(ABSTRACT TRUNCATED AT 250 WORDS)