Influence of timing and magnitude of arterial wave reflection on left ventricular relaxation

The influence of timing and magnitude of arterial wave reflection (WR) on afterload-dependent relaxation was evaluated in patients with a variety of heart diseases (group 1, age < 30 yr; group 2, age > 40 yr) and in dogs. While both femoral arteries were compressed (FC), WR returned just after the dicrotic notch (early diastole) in group 1 but before the dicrotic notch (late systole) in group 2. The time constant of the left ventricular pressure decay (tau) was shortened during FC in group 1, whereas it was prolonged in group 2. In dogs, a constriction of the thoracic aorta induced a late systolic augmentation of WR with a prolongation of tau (cf. group 2), whereas constriction of the lower abdominal aorta induced an early diastolic augmentation of WR with a shortening of tau (cf. group 1). With aortic constriction, coronary flow increased, and there was a close correlation between the peak change in backward aortic pressure and that in coronary flow regardless of the timing of WR. Thus the time at which WR returns during the cardiac cycle may have an important effect on left ventricular relaxation and coronary flow.

Effect of low-intensity warfarin therapy on left atrial thrombus resolution in patients with nonvalvular atrial fibrillation: a transesophageal echocardiographic study

The presence of left atrial thrombus (LAT) is associated with an increased risk of embolic stroke. However, it has yet to be established definitively whether low-intensity warfarin therapy (INR: 1.5-2.0) can prevent LAT formation in patients with nonvalvular atrial fibrillation (NVAF). The present study analyzed the clinical and transesophageal echocardiography (TEE) features of 123 such patients to identify risk factors for LAT formation and the efficacy of prophylactic low-intensity warfarin therapy. Left atrial thrombi were found in 35 patients (28%) in whom systemic hypertension (49% vs 23%; p<0.01) and ischemic heart disease (17% vs 3%; p<0.01) were more frequent. Left ventricular ejection fraction (54+/-14% vs 60+/-11%; p<0.05), left ventricular end-diastolic dimension (51+/-7 mm vs 48+/-5 mm; p<0.05), spontaneous echo contrast (2.2+/-0.7 vs 1.4+/-0.9; p<0.01), left atrial diameter (50+/-6 mm vs 43+/-7 mm; p<0.01), left atrial appendage blood velocity (22.3+/-8.7 cm/s vs 37.2+/-21.5 cm/s; p<0.01) and the incidence of left ventricular hypertrophy (37% vs 15%; p<0.01) were also significantly different between the groups. Fourteen patients received continuous warfarin therapy (target INR: 1.5-2.0) and on the follow-up TEE study the left atrial thrombus resolved in 10 (71%). There were no thromboembolic events or major hemorrhagic complications in these patients, so it was concluded that low-intensity warfarin therapy is efficacious in treating LAT formation in patients with NVAF.

Autologous bone marrow implantation induced angiogenesis and improved deteriorated exercise capacity in a rat ischemic hindlimb model

BACKGROUND

Bone marrow possesses endothelial progenitor cells that secrete several growth factors and can contribute to the formation of new capillaries. In the present study, we investigated the extent of angiogenesis induced by implantation of autologous bone marrow cells (BMCs) in a rat ischemic hindlimb model and studied whether the increased collateral vessels can improve deteriorated physical function.

MATERIALS AND METHODS

Ischemic hindlimb was created by ligation of the femoral artery and its branches in Dark Agouti (DA) rats. BMCs (1 x 10(7)) were injected percutaneously at six points into the gastrocnemius muscle. To assess angiogenesis, histologic evaluation and microangiography were performed at 2 weeks postligation. Severity of the ischemic insult was evaluated by measuring blood flow in the adductor and gastrocnemius muscles using nonradioactive colored microspheres and by determining the femoral arteriovenous oxygen difference (AVDO(2)) at 2 weeks postligation. Running time on a motor-driven treadmill was used to represent exercise capacity.

RESULTS

The histologic evaluation and microangiogram showed that the implanted BMCs induce angiogenesis. Blood flow to the adductor muscle on the treated side in the bone marrow cell implantation (BMI) group was significantly restored to 77.3 +/- 19.3% of that of the normally perfused limb in comparison to that in control groups (P < 0.05). AVDO(2) in the BMI group significantly decreased when compared with AVDO(2) in control groups. Rats in the BMI group ran approximately 1.5 times longer than rats in control groups at 2 and 4 weeks postligation (P < 0.01).

CONCLUSIONS

Implantation of autologous BMCs induced angiogenesis and improved deteriorated exercise capacity in our rat ischemic hindlimb model.

Molecular cloning of rat transmembrane domain protein of 40 kDa regulated in adipocytes and its expression in H9c2 cells exposed to ischemic hypoxia and reoxygenation

We clone a 1230 bp complementary DNA encoding rat transmembrane domain protein of 40 kDa regulated in adipocytes (TPRA40), an orphan receptor, by reverse transcription-polymerase chain reaction using H9c2 cells derived from embryonic rat heart. The deduced amino acid sequence of rat TPRA40 consists of 369 amino acids and has a longer carboxyl terminus than that of the mouse protein. The level of TPRA40 mRNA decreases significantly throughout ischemic hypoxia and reoxygenation.

Up-regulation of inositol 1,4,5 trisphosphate receptor expression in atrial tissue in patients with chronic atrial fibrillation

OBJECTIVES

We examined whether patients with atrial fibrillation (AF) have alterations in atrial inositol 1,4,5 trisphosphate receptors (IP3 receptors).

BACKGROUND

Abnormal intracellular Ca2+ homeostasis occurs in chronic AF. The intracellular Ca2+ concentration is regulated by ryanodine and IP3 receptors. We recently reported alterations in ryanodine receptors in atrial tissue from patients in chronic AF.

METHODS

We analyzed IP3 receptor expression in the right atrial myocardium from 13 patients with mitral valvular disease (MVD) with AF (MVD/AF), five patients with MVD who had normal sinus rhythm (MVD/NSR) and eight control patients with NSR (tissue obtained during coronary artery bypass surgery). Hemodynamic and echocardiographic data were obtained preoperatively, and an immunohistochemical study was performed on atrial tissue.

RESULTS

The relative expression level of IP3 receptor protein was significantly greater in MVD/AF (0.75 +/- 0.26) than it was in MVD/NSR (0.42 +/- 0.13, p < 0.01), and both were significantly above control (0.14 +/- 0.08). The relative expression level of IP3 receptor messenger RNA was significantly greater in the MVD/AF group (0.028 +/- 0.008) than it was in the control group (0.015 +/- 0.004, p < 0.01), but patients with MVD/AF did not differ from patients with MVD/NSR (0.020 +/- 0.006). The relative expression levels of IP3 receptor protein and messenger RNA were higher in patients with left atrial dimension > or = 40 mm, pulmonary capillary wedge pressure > or = 10 mm Hg and right atrial pressure > or = 5 mm Hg. Inositol 1,4,5 trisphosphate receptors were over-expressed in the cytosol and at the nuclear envelope of atrial myocytes in MVD.

CONCLUSIONS

Since chronic mechanical overload of the atrial myocardium increased IP3 receptor expression, especially in patients with chronic AF, up-regulation of IP3 receptors may be important in modulating intracellular Ca2+ homeostasis and initiating or perpetuating AF.

Detection of fibrous cap in atherosclerotic plaque by intravascular ultrasound by use of color mapping of angle-dependent echo-intensity variation

BACKGROUND

The thickness of the fibrous cap is a major determinant in the vulnerability of atherosclerotic plaque to rupture. It has been demonstrated that intravascular ultrasound (IVUS) backscatter from fibrous tissue is strongly dependent on the ultrasound beam angle of incidence. This study investigated the feasibility of using a new IVUS color mapping technique representing the angle-dependent echo-intensity variation to determine the thickness of the fibrous cap in atherosclerotic plaque.

METHODS AND RESULTS

Nineteen formalin-fixed noncalcified human atherosclerotic plaques from necropsy were imaged in vitro with a 30-MHz IVUS catheter. The IVUS catheter was moved coaxially relative to the plaque. The images showing maximum and minimum echo intensity of the plaque surface were selected to calculate the angle-dependent echo-intensity variation. A colorized representation of the echo-intensity variation in the plaque was obtained from the 2 IVUS images. A clearly bordered area with large variation in echo intensity was revealed for each plaque surface in the colorized IVUS image. The thickness (x, mm) of this area correlated significantly with that of fibrous cap (y, mm) measured from histologically prepared sections as y=1.05x-0.01 (r=0.81, P:<0.0001). Bland-Altman analysis also supported the reliability of this method (mean difference, 0.00+/-0.10 mm).

CONCLUSIONS

This novel technique for color mapping the echo-intensity variation in IVUS provided an accurate representation of the thickness of the fibrous cap in atherosclerotic plaque. This method may be useful in assessing plaque vulnerability to rupture in atherosclerosis.

Atheromatous plaque in the distal aortic arch creating the potential for cerebral embolism during cardiopulmonary bypass

The present study evaluated the risk in cardiac patients of rupture of a plaque by a jet stream from the arch cannula. The entire thoracic aorta and cardiac function were routinely monitored by transesophageal echocardiography (TEE) in 88 adult patients who underwent coronary artery bypass surgery. The changes in the atheromatous plaque in the distal aortic arch were observed before and after cardiopulmonary bypass. Of the 88 patients, 13 were found to have preoperative atheromatous plaque at the distal aortic arch and 8 (61.5%) of them suffered plaque rupture caused by jet stream from the arch cannula. Only 1 patient experienced apparent embolic episodes manifesting as cerebral and left leg embolisms; the remaining 7 had no clinical embolic symptoms. In order to prevent atheroembolic events, attention should be paid not only to the ascending aorta, but also to the distal arch and in this regard TEE is useful for detecting atheromatous changes of the aorta.

Effects of in vivo gene transfer of fibroblast growth factor-2 on cardiac function and collateral vessel formation in the microembolized rabbit heart

The effects of gene transfer of the secreted form of fibroblast growth factor-2 (FGF-2) were tested using an adenovirus vector in the microembolized rabbit heart. Japanese white rabbits underwent an intracoronary injection of 25-microm microspheres followed by recombinant adenovirus vectors encoding a secreted form of FGF-2 (FGF group), LacZ (LacZ group), or saline (saline group). Left ventricular (LV) systolic function was serially assessed by echocardiography. Vascular density was measured at 14 days with Azan and CD31 staining. The development of collateral vessels was assessed by measuring myocardial blood flow before and after the occlusion of the left anterior descending coronary artery. Percent fractional shortening (%FS) decreased after the microembolization, and improved gradually for 14 days in the FGF group only (41+/-1% (FGF) vs 32+/-1% (LacZ), 31+/-1% (saline), p<0.01). The vascular density and myocardial collateral blood flow were significantly higher in the FGF group in comparison with other groups. Transcoronary arterial gene transfer of the secreted form of FGF-2 was beneficial for the recovery of LV systolic function and development of collateral vessels in the microembolized rabbit heart.

Heterogeneous expression of nonmuscle myosin heavy chain-B in mesangial cells of patients with Gitelman's syndrome

AIMS

It has been suggested that angiotensin II (Ang II) promotes hypertrophy and hyperplasia of mesangial cells. Nonmuscle myosin heavy chain-B (NMHC-B) and alpha-smooth muscle (SM) actin are considered to be molecular markers for phenotypic change ofproliferative mesangial cells. One of the clinical characteristics in Gitelman's syndrome (GS) is the elevation of plasma Ang II. However, little is known about the relation between Ang II and phenotypic change of mesangial cells in patients with GS. In this report, we examined the expression of NMHC-B and alpha-SM actin in mesangial cells of two GS patients.

MATERIALS AND METHODS

Plasma renin activity, and the concentrations of Ang II, 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), urinary kallikrein, and 6-keto-PGF1alpha were measured. Immunohistochemical staining of NMHC-B and alpha-SM actin in mesangial cells of GS patients was also performed.

RESULTS

Both cases of GS showed normal glomerular function, few histological abnormalities, and higher than normal plasma concentrations of renin and Ang II. Furthermore, one case showed a high urinary concentration of kallikrein and the expression of both NMHC-B and alpha-SM actin in mesangial cells. The other case showed a high urinary concentration of 6-keto-PGF1alpha but not kallikrein and without the expression of NMHC-B and alpha-SM actin.

CONCLUSION

Not only plasma kinin-kallikrein and prostaglandins, but the renal expression of NMHC-B and alpha-SM actin may be variable in different patients with GS.

[Complete cytogenetic response obtained with unrelated donor lymphocyte infusion for relapse of chronic myeloid leukemia in blastic crisis after allogeneic bone marrow transplantation]

A 35-year-old man with chronic myeloid leukemia (CML) in blastic crisis (BC) received an allogeneic bone marrow transplant from an unrelated donor in October 1998 after three cycles of chemotherapy. BC relapse developed on day 349 after transplantation. After one cycle of chemotherapy and treatment with interferon, the patient received donor lymphocyte infusion (DLI), and this resulted in a complete cytogenetic response 21 days later. Grade III acute graft-versus-host disease developed on day 25 after DLI, but this was resolved after administration of prednisolone. Disease relapse occurred at extramedullary sites on day 162 after DLI, and the patient died of sepsis after receiving chemotherapy. This case illustrates that unrelated DLI can induce remission successfully in patients with relapse of CML in BC through a graft-versus-leukemia effect.

Enhancement of Rho/Rho-kinase system in regulation of vascular smooth muscle contraction in tachycardia-induced heart failure

OBJECTIVE

The Rho/Rho-kinase system regulates Ca(2+) sensitivity in vascular smooth muscle. A new drug, Y-27632, specifically inhibits Rho-kinase and hence decreases the phosphorylation of myosin light chain, thus reducing contraction. Here, we compare the effects of Y-27632 and nifedipine on the vasoconstrictor response of the femoral artery in heart failure.

METHODS

Heart failure (HF) was produced by chronic rapid RV pacing (250 bpm, 28 days, six dogs). Indo1-AM was loaded into endothelium-denuded femoral artery segments for measuring intracellular [Ca(2+)]. Tension and changes in intracellular [Ca(2+)] [the change in the ratio (418 nm/468 nm) of Indo1 fluorescence (F(ratio))] were simultaneously measured in Krebs-Ringer solution.

RESULTS

In HF: (i) norepinephrine (10 microM) produced greater tension (784+/-52 g/cm(2)) than in control (502+/-64 g/cm(2)) despite a similar increase in F(ratio), indicating increased Ca(2+) sensitivity in vascular smooth muscle; (ii) nifedipine attenuated this enhanced response by only a maximum of 27% at 1 micromol/l with a 56% reduction in F(ratio); (iii) Y-27632 attenuated it by a maximum of 80% at 100 micromol/l without a significant change in F(ratio); (iv) RhoA protein and mRNA expression levels in the femoral artery were up-regulated by +110% and +56%, respectively, while those of Rho-kinase were unchanged.

CONCLUSIONS

The Ca(2+)-sensitizing mechanism involving the Rho/Rho-kinase system may be deeply involved in the enhanced arterial vasoconstriction seen in HF. Since Y-27632 attenuated this response in small arteries, it shows potential as a novel, potent vasodilator for the treatment of HF.

Severe cardiac toxicity in hematological stem cell transplantation: predictive value of reduced left ventricular ejection fraction

Eighty patients receiving hematological stem cell transplantation (HCT) with a preparative regimen consisting of total body irradiation (12.5 Gy), cyclophosphamide (4000 or 4500 mg/m2), and thiotepa (400 mg/m2) were evaluated for the development of cardiac toxicity. Patients in whom the pretransplant cumulative dose of anthracycline was more than or equal to 300 mg/m2 showed a lower left ventricular ejection fraction (EF) before HCT compared to patients with less than 300 mg/m2 (0.61 +/- 0.09 vs 0.67 +/- 0.06, P = 0.0010). Patients who had undergone more than or equal to six courses of chemotherapy showed a decreased EF before HCT compared to those after less than six courses (0.67 +/- 0.05 vs 0.63 +/- 0.09, P = 0.03). Three of seven patients (43%) whose pretransplant EF had been less than or equal to 0.55 developed severe cardiac toxicity, characterized by congestive heart failure (CHF) compared with none of 83 patients (0%) whose pretransplant EF had been more than 0.55 (P = 0.00026). Of the three patients who developed severe cardiac toxicity, two were given more than 300 mg/m2 of cumulative anthracycline and underwent 23 courses and six courses of chemotherapy, while the other patient received only two courses of chemotherapy with a total dose of 139 mg/m2 of anthracycline. These results indicate that an increased cumulative dose of anthracycline and number of chemotherapy treatments are correlated with a decrease of the EF and that the EF before HCT is useful for predicting the risk of cardiac complications for recipients who have received chemotherapy.

Expression and anticoagulant function of the endothelial cell protein C receptor (EPCR) in cancer cell lines

Induction of procoagulant factors in malignant cells is considered to be the major cause of coagulation disorders in cancer. Thrombomodulin (TM), a negative regulator of coagulation was also found to be expressed in cancer cells. We report here evidence for another anticoagulant, the endothelial cell protein C receptor (EPCR), in cancer cells. EPCR was detected in several cell lines derived from various types of cancer. Significant levels of protein C (PC) activation were detected only with cell lines expressed both EPCR and TM. Anti-EPCR monoclonal antibodies (mAbs) specifically inhibited the activation. Thus, EPCR function appears to be important for PC activation by cancer cells. In addition, we detected EPCR expression in tumor cells from breast cancer patients, with an extremely high frequency. EPCR function may contribute to progression or pathogenesis of some types of cancer, and may explain the complexity of coagulopathy in cancer patients.

Predominant inner-half wall thickening of left ventricle is attenuated in dilated cardiomyopathy: an application of tissue Doppler tracking technique

The importance of the inner half (IH) of the left ventricular (LV) wall has been reported in hearts that contract normally. However, it is difficult to verify this fact in an in vivo human heart with clinical echocardiography. By using a recently developed tissue Doppler tracking technique, we could assess the systolic wall thickening of the IH and outer half (OH) of the LV wall in 11 normal and 7 dilated cardiomyopathic hearts. Percent wall thickening and the fractional contribution of the IH and OH to the transmural wall thickening were calculated. In healthy subjects, percent wall thickening of the IH, OH, and transmural wall of the left ventricle were 75.8% +/- 24.1%, 39.4% +/- 14.4% (P <.001 versus IH), and 57.6% +/- 17.6%, respectively. In patients with dilated cardiomyopathy, those values were 31.3% +/- 17.1%, 31.2% +/- 20.1% (not significant versus IH), and 31.2% +/- 16.5%, respectively. On the other hand, the fractional contributions of the IH and OH were 66.2% +/- 7.7% and 33.8% +/- 7.7% (P &lt.01 versus IH) in healthy subjects and 50.5% +/- 11.8% and 49.5% +/- 11.8% (not significant versus IH) in patients with dilated cardiomyopathy. Specifically, the IH contributed to the transmural wall thickening nearly twice as much as the OH did in healthy subjects, however, the predominance of IH contribution was attenuated in dilated cardiomyopathy. The tissue Doppler tracking technique is useful in assessing the IH and OH LV wall thickening separately in the clinical situation.

Characterization of T cell receptor beta chains of accumulating T cells in chronic ongoing myocarditis demonstrated by heterotopic cardiac transplantation in mice

Autoimmne mechanisms have been implicated in the pathogenesis of chronic ongoing mycarditis. An earlier study of murine chronic ongoing myocarditis reported that infiltrating T cells and macrophages were prominent in the normal donor heart, in a heterotopic cardiac transplantation model. It was demonstrated that myocarditis was transferred to a normal heart transplanted into a mouse with chronic myocarditis. The present study investigated an autoimmune link to the pathogenesis of chronic ongoing myocarditis by analyzing the T cell clonalities in the model. To characterize the accumulating T cells in the donor heart, the T cell receptor beta genes (TCRBG) were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) from mRNA in the donor hearts and accumulating TCRBG clonotypes were contrasted with those from recipient hearts. Inbred 3-week-old A/J mice were inoculated intraperitoneally with Coxsackievirus B3 (Nancy strain), 2 x 10(4) PFU, and housed for more than 60 days. Normal A/J mouse hearts were transplanted into the same strain of mice without myocarditis, as well as into the mice with chronic ongoing myocarditis. Both recipient and donor hearts were evaluated histologically 2 weeks after the transplantation. TCRBG were amplified by RT-PCR from mRNA of recipient and donor hearts and spleens. The specific accumulating TCRBG clonotypes were identified by their single strand conformation polymorphism. Multiple clonotypic accumulations occurred in the donor heart after cardiac transplantation. Distinct oligoclonal accumulation of TCR Vbeta1, 10, and 13 T cells was found in both recipient and donor hearts in 3 of 4 mice. Moreover, these clonotypes were not observed in spleen cells of the recipient mice. T specific cells expanding clonotypes of TCRBG are responsible for transferring myocarditis to the donor heart. An autoimmune response may, therefore, play a key role in the progression of chronic ongoing myocarditis.

[Sequential analysis of p210- and p190-bcr-abl by RT-PCR after allogeneic bone marrow transplantation for p210/p190-bcr-abl double positive acute lymphoblastic leukemia]

In patients with both p210-bcr-abl (p210) and p190-bcr-abl (p190)-positive acute lymphoblastic leukemia, the number of p190 transcripts is lower than that of p210 transcripts. It is speculated that the p190 transcript occurs as a consequence of alternative splicing or missplicing events in the BCR gene. Four patients with both p210- and p190-positive acute lymphoblastic leukemia were studied for expression of p210 and p190 by RT-PCR before and after allogeneic bone marrow transplantation. p190 negativity was documented in all four patients, followed by p210 negativity one to two months later in three patients. These results suggest that negativity for p190 indicates an ongoing decrease in the small number of residual leukemic cells. In one patient p190 appeared transiently in spite of prolonged negativity for p210 18 months after bone marrow transplantation. We conclude that analysis of p210 and p190 is useful for following up patients with both p210- and p190-positive acute lymphoblastic leukemia.

Eicosapentaenoic acid (EPA) induces Ca(2+)-independent activation and translocation of endothelial nitric oxide synthase and endothelium-dependent vasorelaxation

Eicosapentaenoic acid (EPA), but not its metabolites (docosapentaenoic acid and docosahexaenoic acid), stimulated nitric oxide (NO) production in endothelial cells in situ and induced endothelium-dependent relaxation of bovine coronary arteries precontracted with U46619. EPA induced a greater production of NO, but a much smaller and more transient elevation of intracellular Ca(2+) concentration ([Ca(2+)]i), than did a Ca(2+) ionophore (ionomycin). EPA stimulated NO production even in endothelial cells in situ loaded with a cytosolic Ca(2+) chelator 1,2-bis-o-aminophenoxythamine-N',N',N'-tetraacetic acid, which abolished the [Ca(2+)]i elevations induced by ATP and EPA. The EPA-induced vasorelaxation was inhibited by N(omega)-nitro-L-arginine methyl ester. Immunostaining analysis of endothelial NO synthase (eNOS) and caveolin-1 in cultured endothelial cells revealed eNOS to be colocalized with caveolin in the cell membrane at a resting state, while EPA stimulated the translocation of eNOS to the cytosol and its dissociation from caveolin, to an extent comparable to that of the eNOS translocation induced by a [Ca(2+)]i-elevating agonist (10 microM bradykinin). Thus, EPA induces Ca(2+)-independent activation and translocation of eNOS and endothelium-dependent vasorelaxation.

Improvement of afterload mismatch of left atrial booster pump function with positive inotropic agent

OBJECTIVES

The objective of this study was to examine the hypothesis that a positive inotropic agent improves left ventricular (LV) filling during left atrial (LA) contraction in the presence of markedly elevated LV filling pressure.

BACKGROUND

In patients with old myocardial infarction (MI), an increase in the operational LV chamber stiffness reduces LV filling during the LA contraction, resulting from an "afterload mismatch" of the LA booster pump function.

METHODS

We investigated the effect of dobutamine infusion (3 microg/kg/min) on the LA pump function in the presence of elevated LV filling pressure induced by aortic constriction (Aoc) during acute MI in 10 dogs. Transmitral flow velocity was determined by transesophageal echocardiography, LV pressure by a micromanometer and LV volume by a conductance catheter. We measured the early (E) and late (A) diastolic peak transmitral flow velocities (cm/s) and LV chamber stiffness (deltaP/deltaV: mm Hg/ml; where deltaP is developed pressure and deltaV is the absolute filling volume during LA contraction).

RESULTS

When the deltaP/deltaV was increased by Aoc during MI (from 1.1 +/- 0.8 to 3.1 +/- 2.6 mm Hg/ml, p < 0.01), A decreased significantly (from 30 +/- 5 to 22 +/- 8 cm/s, p < 0.01), and the ratio of E to A increased (from 1.0 +/- 0.3 to 1.4 +/- 0.8, p < 0.05) compared with MI without Aoc, showing the pseudonormal transmitral flow pattern, the so called "LA afterload mismatch." Dobutamine under this condition significantly reduced the deltaP/deltaV (to 1.7 +/- 1.2 mm Hg/ml, p < 0.05), resulting in an increase in A (to 31 +/- 8 cm/s, p < 0.01) and a decrease in E/A (to 1.0 +/- 0.3, p < 0.05), and the transmitral flow became a prolonged relaxation pattern as in MI without Aoc in all dogs. There was an inverse correlation between the deltaP/deltaV and the time-velocity integral of A (r = -0.70, p < 0.01).

CONCLUSIONS

Dobutamine improved the afterload mismatch of the LA booster pump function. This effect may have been due to the reduction in LV operational chamber stiffness, resulting in an increase in the LA forward ejection into the LV.

Antagonist of pituitary adenylate cyclase activating polypeptide suppresses prolactin secretion without changing the activity of dopamine neurons in lactating rats

Pituitary adenylate cyclase activating polypeptide (PACAP) is a relatively new neuropeptide, and it has a potent stimulatory effect on adenylate cyclase activity in rat pituitary cells. However, the role of PACAP in the physiological control of prolactin (PRL) secretion is still unclear. In the present study, we investigated the physiological significance of endogenous PACAP on PRL secretion in lactating rats. On lactation days 7-8, pups were separated from their mother rats for 5 h before the onset of suckling and PACAP6-38 (16 microg), a receptor antagonist, was injected through the lateral ventricle cannula just after the removal of pups. The effects of PACAP6-38 on PRL and oxytocin secretion, and on the activity of tyrosine hydroxylase (TH), were examined after the onset of suckling. Administration of PACAP6-38 inhibited PRL levels in response to suckling, but it did not affect the activity of TH, as measured by DOPA accumulation at 15 min after administration of NSD 1015 (25.0 mg/kg), an L-aromatic amino acid decarboxylase inhibitor, or the plasma concentrations of oxytocin in lactating rats. Injection of alpha-methyl-p-tyrosine (alpha-MT; 50 mg/kg), an inhibitor of dopamine synthesis, increased PRL levels, and suckling caused a further increase in the plasma concentrations of PRL. An injection of PACAP6-38 (i.c.v.) also inhibited the PRL response to suckling under dopamine depletion. These results suggest that endogenous PACAP acts as a neurotransmitter or neuromodulator within the hypothalamus and plays an important role for PRL secretion in lactating rats. Endogenous PACAP may regulate PRL secretion, possibly mediated by PRL-releasing factors such as vasoactive intestinal polypeptide or vasopressin.

Large amounts of apicoplast nucleoid DNA and its segregation in Toxoplasma gondii

Apicoplasts (apicomplexan plastids) are nonphotosynthetic, secondary endosymbiotic plastids that are found in most apicomplexans. Although these organelles are essential for parasite survival, their functions, activities, and structures are not well understood. We examined the apicoplast nucleoid of Toxoplasma gondii from a morphological aspect by high-resolution epifluorescence microscopy and electron microscopy. We found unexpectedly large amounts of DNA in the nucleoid and the presence of several division-related structures. Initially, we identified the organellar nucleoids by staining with the DNA-specific dye 4',6-diamidino-2-phenylindole. A single nucleoid was observed per apicoplast, and the fluorescent spot representing the nucleoid was bright and spherical in contrast to the weak and filamentous spot representing the mitochondrial nucleoid. We also measured the DNA content of each apicoplast nucleoid by a video-intensified microscope photon-counting system and determined that the genomic copy number was at least 25, a figure over four times greater than that reported previously. Moreover, several groups of apicoplasts had significantly higher genomic copy numbers. The DNA molecules were accurately divided into two daughter apicoplasts just before nuclear division. In addition, we examined nucleoid segregation and the division apparatus using electron microscopy. However, we failed to observe nucleoid structures, suggesting that the apicoplasts are predominantly composed of nucleoid material. In addition, we observed "cap" structures at the termini of dividing apicoplasts, a possible plastid-dividing ring, and a microbody-like granule around the constriction. These structures may be involved in apicoplast division.

Gene disruption analysis of DppA isolated as a periplasmic molecular chaperone-like protein for folding of dimethyl sulfoxide reductase in Rhodobacter sphaeroides f. sp. denitrificans

The effect of inactivation of DppA, a dipeptide transport protein identified as a periplasmic molecular chaperone-like protein, on the formation of active dimethyl sulfoxide reductase (DMSOR) was examined in Rhodobacter sphaeroides f. sp. denitrificans. All of the dppA-disrupted mutants produced a normal level of native form of DMSOR and grew by DMSO respiration, indicating that the loss of DppA protein alone had no effect on the formation of active DMSOR. The periplasmic fraction of the dppA-disrupted mutant also had the activity to prevent aggregation of acid-unfolded DMSOR. Two proteins, DctP and BztA, were further identified as the proteins with the activity. Their activities, however, were much lower than that of DppA. These results suggest that several substrate binding proteins might be implicated in the folding of unfolded DMSOR in the periplasm.

Infective endocarditis with extensive calcified granulation of the mitral annulus and valve--a case report

Mitral annular calcification, a degenerative process usually seen in the elderly or in chronic renal failure, is rarely seen in an extensive form. A 69-year-old man with no history of renal failure, rheumatic fever, or heart disease had mitral valve vegetation and regurgitation, together with extensive mitral annuls and valve calcification, which may or may not have been secondary to the infective endocarditis.

Vasodilator responses of coronary conduit and resistance arteries to continuous nitroglycerin infusion in humans: a Doppler guide wire study

To examine the responses of coronary conduit and resistance arteries to the continuous i.v. administration of nitroglycerin in 15 patients with atypical chest pain, we measured coronary blood flow velocity in the left anterior descending coronary artery using a Doppler guide wire and the lumen diameter and cross-sectional area by quantitative coronary angiography. Systolic flow, diastolic flow, total coronary flow, and coronary vascular resistance were calculated. Stepwise increases in dose of nitroglycerin resulted in significant dose-dependent decrease in mean aortic pressure (p < 0.01) and increase in lumen diameter (p < 0.05). After nitroglycerin administration of 0.5 microg/kg/min, systolic flow decreased significantly by 89.9+/-15.7% (p < 0.01), and diastolic flow increased significantly by 74.2+/-37.1% (p < 0.05). Total coronary flow did not change significantly with the various doses of nitroglycerin. However, coronary vascular resistance decreased significantly at concentrations greater than 0.5 microg/kg/min nitroglycerin. Continuous nitroglycerin infusion did not reduce either diastolic or total coronary blood flow despite a significant reduction in coronary perfusion pressure. These results indicate that subendocardial blood flow might be maintained during continuous i.v. infusion of nitroglycerin within the clinical dose range.