Role of insulin resistance in heart and skeletal muscle F-18 fluorodeoxyglucose uptake in patients with non-insulin-dependent diabetes mellitus

BACKGROUND

Altered heart and skeletal glucose usage has been reported in patients with non-insulin-dependent diabetes mellitus (NIDDM). Although elevations in plasma free fatty acid (FFA) concentrations have been implicated in reduced myocardial 18fluorine-fluoro-2-deoxy-D-glucose uptake (MFU), the specific role of whole-body insulin resistance in MFU in patients with NIDDM compared with skeletal muscle metabolism remains controversial.

PURPOSE

MFU and skeletal muscle 18fluorine-fluoro-2-deoxy-D-glucose uptake (SMFU) were compared with positron emission tomography and the whole-body glucose disposal rate (GDR) during hyperinsulinemic euglycemic clamping in 26 normotensive asymptomatic patients with NIDDM who were not taking medication. These factors were also compared in 12 age-matched control subjects to increase the knowledge of the influence of whole-body insulin resistance on MFU. In addition, independent factors for both SMFU and MFU were investigated.

RESULTS

GDR in control subjects (10.0 +/- 2.97 mg/min per kilogram) was significantly higher than in patients with NIDDM (4.05 +/- 2.37 mg/min per kilogram, P < .01). SMFU in patients with NIDDM (0.826 +/- 0.604 mg/min per 100 g) was significantly lower than that in control subjects (1.86 +/- 1.06 mg/min per 100 g, P < .01). MFU in patients with NIDDM (5.35 +/- 2.10 mg/min per 100 g) was also significantly lower than that of control subjects (7.05 +/- 1.66 mg/min per 100 g, P = .0182). SMFU significantly correlated with GDR (r = .727, P < .01) and FFA (r = -.52, P < .01) in patients with NIDDM. MFU also correlated with GDR (r = .778, P < .01) and FFA (r = -.72, P < .01) in patients with NIDDM. Multivariate stepwise regression analysis showed that GDR (F = 36.8) was independently related to MFU (r = .85, P < .01) whereas FFA was not (F = 1.763), where F is the value for statistical analysis of multivariate stepwise regression analysis.

CONCLUSION

Insulin resistance is the most essential factor for both heart and skeletal muscle FDG uptake in patients with NIDDM.

[Treatment of renal cell carcinoma extending into the right atrium with extra-corporeal circulation using high-grade hypothermia: a case report]

A 68-year-old woman underwent surgical treatment for renal cell carcinoma associated with tumor thrombus extending into the right atrium. Although the tumor thrombus reached the level of the right atrium, there were no other apparent metastases. Combination therapy with interferon alfa plus tegafur/uracil (UFT) was attempted with the expectation of reducing the tumor thrombus, but there was no change. Successful management was achieved with right radical nephrectomy, right auriculotomy, and partial cavectomy using cardiopulmonary bypass under high-grade hypothermia. After removal of the tumor and thrombus, blood loss was 13,900 ml during the patient's recovery. She had mild heart failure for about two weeks after the operation, but recovered. She was discharged on the 40th day after the operation. Proper preparation for blood transfusion is the key point of this operation.

Acid load during total parenteral nutrition: comparison of hydrochloric acid and acetic acid on plasma acid-base balance

The effects of hydrochloric acid and acetic acid on the plasma acid-base balance were investigated in four rabbits receiving parenteral nutrition. Hyperchloremic metabolic acidosis was observed only in the animals receiving total parenteral nutrition (TPN) whose pH was adjusted with hydrochloric acid. The observed acidosis was due to an excess of hydrogen ions with chloride ions as judged by the plasma-base excess and urinary net-acid excess and not by the infusion of solution having a high titratable acidity. The hydrogen ion released from the acetic acid added to TPN is consumed by the metabolism of the acetate ion and thus does not contribute to the net hydrogen-ion load. A reduction in the chloride load by using acetic acid to adjust the pH of the TPN solution when it is formulated can be safely achieved and prevents acidosis.

Leukaemia inhibitory factor is required for normal inflammatory responses to injury in the peripheral and central nervous systems in vivo and is chemotactic for macrophages in vitro

The cytokine leukaemia inhibitory factor (LIF) is up-regulated in glial cells after injury to the peripheral and central nervous systems. In addition, LIF is required for the changes in neuropeptide expression that normally occur when the axons of sympathetic and sensory neurons are transected. We investigated whether LIF is also necessary for the initial inflammatory response that follows mechanical injury to the sciatic nerve and cerebral cortex of adult mice. We find that inflammatory cell infiltration into crushed sciatic nerve is significantly slower in LIF knock-out (KO) mice compared with wild-type (WT) mice. Similarly, the microglial and astroglial responses to surgical injury of the cortex are significantly slower in LIF KO mice compared with WT mice. Consistent with these in vivo results, LIF is chemotactic for peritoneal macrophages in a microchamber culture assay. Thus, LIF is a key regulator of neural injury in vivo, where it is produced by glia and can act directly on neurons, glia and inflammatory cells. We also find that the initial inflammatory response to cortical injury is diminished in interleukin (IL)-6 KO mice. Surprisingly, however, the inflammatory response in LIF-IL-6 double KO mice is very similar to that of the single KO mice, suggesting that these cytokines may act in series rather than in parallel in this response.

Myocardial tactile stiffness during acute reduction of coronary blood flow

BACKGROUND

Evaluation of regional myocardial contractile function is of clinical importance. We have developed a new tactile sensor system for accurate measurement of myocardial stiffness in situ. We found that the myocardial stiffness measured by this sensor, which we call tactile stiffness, can be a very useful index for accurate quantification of regional myocardial function. In this study, we used a coronary stenosis model to investigate regional myocardial tactile stiffness under conditions of reduced coronary blood flow.

METHODS

The myocardial tactile stiffness, coronary blood flow, and ventricular pressure and volume, of five open chest mongrel dogs weighing 15 to 17 kg, were measured. After measuring the baseline myocardial stiffness, coronary arterial stenosis was induced with a balloon occluder.

RESULTS

Reducing the coronary flow to 50% and 25% of the baseline level reduced the end-systolic tactile stiffness significantly from 2.20+/-0.16 g/mm2 to 2.05+/-0.20 g/mm2 (p<0.05) and from 2.21+/-0.16 g/mm2 to 1.96+/-0.18 g/mm2 (p<0.01), respectively. Reducing the flow, to 50% and 25%, increased the end-diastolic stiffness significantly from 1.29+/-0.15 g/mm2 to 1.39+/-0.14 g/mm2 (p<0.01) and from 1.30+/-0.16 g/mm2 to 1.46+/-0.14 g/mm2 (p<0.05), respectively.

CONCLUSIONS

We consider that the regional myocardial tactile stiffness will be a useful index sensitive enough to detect changes in regional contractile function under conditions of reduced coronary blood flow.

Actin-myosin interaction

Recent advances in the study of muscle physiology was made possible by the application of novel experimental techniques including in vitro motility assay, molecular biology, and X-ray crystallography. A similar approach was successfully applied in studying the properties of cardiac actin-myosin interaction. Implication in clinical cardiology is also reviewed.

Improvement of impaired myocardial vasodilatation due to diffuse coronary atherosclerosis in hypercholesterolemics after lipid-lowering therapy

BACKGROUND

Diminished myocardial vasodilatation (MVD) in hypercholesterolemics without overt coronary stenosis has been reported. However, whether the diminished MVD of angiographically normal coronary arteries in hypercholesterolemics can be reversed after lipid-lowering therapy is not known.

METHODS AND RESULTS

A total of 27 hypercholesterolemics and 16 age-matched controls were studied. All patients had >1 normal coronary artery, and those segments that were perfused by anatomically normal coronary arteries were studied. Myocardial blood flow (MBF) was measured during dipyridamole loading and at baseline using positron emission tomography and 13N-ammonia, after which MVD was calculated before and after lipid-lowering therapy. Total cholesterol was significantly higher in hypercholesterolemics (263+/-33.8) than in controls (195+/-16.6), and it normalized after lipid-lowering therapy (197+/-19.9). Baseline MBF (ml. min-1. 100 g-1) was comparable among hypercholesterolemics (both before and after therapy) and controls. MBF during dipyridamole loading was significantly lower in hypercholesterolemics before therapy (189+/-75.4) than in controls (299+/-162, P<0.01). However, MBF during dipyridamole loading significantly increased after therapy (226+/-84.7; P<0.01). MVD significantly improved after therapy in hypercholesterolemics (2.77+/-1.35 after treatment [P<0.05] versus 2. 02+/-0.68 before treatment [P<0.01]), but it remained significantly higher in controls (3.69+/-1.13, P<0.01). There was a significant relationship between the percent change of total cholesterol and the percent change of MVD before and after lipid-lowering therapy (r=-0. 61, P<0.05).

CONCLUSIONS

Diminished MVD of anatomically normal coronary arteries in hypercholesterolemics can be reversed after lipid-lowering therapy.

Insulin action on heart and skeletal muscle FDG uptake in patients with hypertriglyceridemia

Abnormal heart and skeletal muscle 18F-fluorodeoxyglucose (FDG) uptake in patients with insulin resistance has been demonstrated. Although the existence of whole-body insulin resistance has been reported in hypertriglyceridemics, its specific role in heart and skeletal muscle FDG uptake in hypertriglyceridemics has not been clarified.

METHODS

We compared heart and skeletal muscle FDG uptake using PET and the whole-body glucose disposal rate (GDR) during insulin clamping in 17 hypertriglyceridemics and 12 age-matched control subjects to increase our knowledge of whole-body insulin resistance and its relationship to heart and skeletal muscle FDG uptake in hypertriglyceridemics.

RESULTS

GDR was significantly reduced in hypertriglyceridemics compared with control subjects (4.50 +/- 1.37 mg/min/kg versus 10.0 +/- 2.97 mg/min/kg, P = 0.00001), as were the skeletal muscle FDG Ki = (k1 x k3)/(k2 + k3) (SFKi: 0.007 +/- 0.003 mL/min/g versus 0.018 +/- 0.01 mL/min/g, P = 0.0001) and skeletal muscle FDG uptake ([SMFU] 0.725 +/- 0.282 mg/min/100 g versus 1.86 +/- 1.06 mg/min/100 g, P = 0.00023). However, myocardial FDG Ki (MFKi) tended to be reduced in hypertriglyceridemics compared with that in control subjects (0.062 +/- 0.017 mL/min/g versus 0.068 +/- 0.015 mL/min/g), but the difference was statistically insignificant (P = 0.3532). Moreover, myocardial FDG uptake (MFU) in hypertriglyceridemics (6.47 +/- 1.72 mg/min/100 g) tended to be reduced compared with that in control subjects (6.97 +/- 1.73 mg/min/100 g), but the difference was statistically insignificant (P = 0.4485). GDR was significantly correlated with SFKi (r = 0.69, P = 0.0022), SMFU (r = 0.612, P = 0.009), MFKi (r = 0.57, P = 0.0174) and MFU (r = 0.505, P = 0.0385) in hypertriglyceridemics.

CONCLUSION

Both heart and skeletal muscle glucose utilization were related to insulin resistance in hypertriglyceridemics. However, the less severe reduction in MFU (compared with SMFU) suggests that myocardium may have a mechanism to oppose insulin resistance in hypertriglyceridemics.

Pharmacological analysis of etoposide in elderly patients with lung cancer

To analyze the pharmacological characteristics of etoposide in elderly patients, we conducted a Phase I trial of a 14-day administration of oral etoposide on 12 chemotherapy-naive patients, ages 75 years or older, with lung cancer. The pharmacological profiles of etoposide in elderly patients were compared with those of younger patients in our previous studies (H. Minami et al., J. Clin. Oncol., 11: 1602-1608, 1993; H. Minami et al., J. Clin. Oncol., 13: 191-199, 1995; Y. Ando et al., Jpn. J. Cancer Res., 87: 200-205, 1996). The sigmoid Emax model and logistic regression model were used for pharmacodynamic analysis. The maximum tolerated dose for elderly patients was 75 mg/body/day. The apparent oral clearance in elderly patients was 37+/-10 (mean +/- SD) ml/min, which was not different from that in younger patients (44+/-12 ml/min). The area under the concentration-versus-time curve of etoposide over the treatment period (total AUC) that produced a 50% decrease in absolute neutrophil counts was significantly different between elderly and younger patients, 14.3+/-2.5 and 21.6+/-2.7 mg x min/ml, respectively (P = 0.048). The incidence of grade 3 or 4 neutropenia at total AUC of 30 mg x min/ml (corresponding to a plasma concentration of 1.5 microg/ml for 14 days) was 81% in elderly patients but only 48% in younger patients. Although there was no pharmacokinetic difference between elderly and younger patients, equivalent exposure to etoposide resulted in severer myelosuppression in elderly patients. These findings suggest that prolonged etoposide administration with plasma concentration maintained at 1-2 microg/ml may cause severe myelotoxicity in elderly patients.

Kinetics of oxygen uptake at onset of exercise related to cardiac output, but not to arteriovenous oxygen difference in patients with chronic heart failure

Patients with chronic heart failure performed exercise tests to evaluate the relation of kinetics of oxygen uptake to cardiac output and arteriovenous oxygen difference at the onset of exercise. The kinetics of oxygen uptake are primarily determined by cardiac output; these kinetics are useful in evaluating exercise intolerance and cardiac output response during exercise.

The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene promoter activity is decreased in response to severe left ventricular pressure-overload hypertrophy in rat hearts

The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) pump plays a key role in the contraction-relaxation cycle of the myocardium by controlling the intracellular Ca2+ concentration. SERCA2 protein and mRNA expression levels, as well as, SR Ca2+ uptake function are depressed in hypertrophied and failing myocardium. At this time, the molecular mechanisms regulating SERCA2 gene transcription during hypertrophy and heart failure are not completely understood, especially in vivo. Direct gene transfer into adult cardiac tissue has recently been shown to be a useful technique to study in vivo gene regulation. In this study, SERCA2 promoter-luciferase (Luc) reporter constructs of various lengths were injected into the beating left ventricular apex of adult rats (groups = compensated hypertrophy, heart failure, and controls) and the expression level was analysed. Our SERCA2 promoter analyses revealed three positive regulatory regions between -1810 bp and -1110 bp, -658 bp and -284 bp, and -267 bp and -72 bp and a negative regulatory region between -1110 bp and -658 bp, important for in vivo expression in rat hearts. SERCA2 promoter activity was also assessed in rat hearts with compensated pressure-overload hypertrophy (induced by the DOCA-salt treatment) and heart failure (induced by severe ascending aortic constriction). In the DOCA-salt-induced hypertrophy model, SERCA2 promoter activity was similar to that of sham controls. In contrast, severe constriction of the ascending aorta decreased the expression of the -1810 Luc and -1110 Luc constructs by 92.8% and 64.3%, respectively. This study suggests that only severe pressure-overload hypertrophy produces a significant decrease in SERCA2 promoter activity, and the promoter region extending to -1810 bp is sufficient for the down regulation of SERCA2 gene expression.

Prognostic factors for short-term survival in patients with stage IV non-small cell lung cancer

Prognostic factors which can forecast short-term survival in patients with stage IV non-small cell lung cancer have not been well evaluated. Characteristics of such factors may be different from those for overall survival, and would be an important eligibility criterion for clinical trials of chemotherapy. We retrospectively analyzed the data of 158 patients with stage IV non-small cell lung cancer whose performance status was 0, 1 or 2. Univariate and multivariate logistic regression models revealed demographic variables which significantly correlated with the survival at 8 or 12 weeks. The univariate model showed the following significant variables: T factor, N factor, number of organs with metastases, grade of performance status, weight loss within 6 months, evidence of metastasis either at bone or lymph node, and lactate dehydrogenase level. The subsequent multivariate model demonstrated that both grade of performance status under 2 and number of metastasized organs less than 3 are important factors for 8- or 12-week survival. The survival rate in patients meeting the two criteria (grade of performance status under 2 and number of metastasized organs less than 3) and in those meeting only one of them was 93% versus 80% at 8 weeks (P = 0.030) and 88% versus 62% at 12 weeks (P < 0.001), respectively. Grade of performance status and number of organs with metastases appear to be important prognostic factors for short-term survival in patients with stage IV non-small cell lung cancer.

Functional characterization of Dictyostelium discoideum mutant myosins equivalent to human familial hypertrophic cardiomyopathy

Familial hypertrophic cardiomyopathy (FHC) is caused by missence mutations in beta-myosin heavy chain or other various sarcomeric proteins. To elucidate the functional impact of FHC mutations in myosin heavy chain, we generated Dictyostelium discoideum myosin II mutants equivalent to human FHC mutations by site-directed mutagenesis, and characterized their molecular-basis motor function. The current mutants, i.e. R397Q, F506C, G575R, A699R, K703Q and K703W are equivalent to R403Q, F513C, G584R, G716R, R719Q and R719W FHC mutants respectively. We measured the molecular-basis force and the sliding velocity generated by these myosin mutants. The measurement revealed that the A699R, K703Q and K703W myosins exhibited the lowest level of force with their preserved actin-activated MgATPase activity. F506C mutant showed the least impairment of the motile and enzymatic activities. The motor function of R397Q and G575R myosins were classified as intermediate. These results suggest that ELC binding domain might be important for force production.

Distinct kinetic properties of cardiac myosin isoforms revealed by in vitro studies

To clarify the physiological significance of myosin isoform redistribution in cardiac adaptation process, we compared the kinetic property of the two cardiac myosin isoforms using in vitro motility assay techniques. Cardiac myosin isoforms V1 and V3 were obtained from ventricular muscle of young rats and hypothyroid rats respectively. On each of these myosin isoforms fixed on a glass coverslip, fluorescently labeled actin filaments were made to slide in the presence of ATP. To measure the force generated by actomyosin interaction, a small latex bead was attached to the barbed end of an actin filament and the bead was captured by the laser optical trap installed in a microscope. The force was determined from the distance between the bead and the trap positions under either auxotonic or isometric conditions. The time-averaged force generated by multiple cross-bridges did not differ significantly between the two isoforms. On the other hand, the unitary force measurement revealed the same level of amplitude but a longer duration for V3 isoform. The same level of time-averaged force is in agreement with not only our previous finding but the results of maximum force measurement in muscle preparations. The difference in kinetic characteristics of the two isoforms could account for the difference in economy of force development and the basis for cardiac adaptation mechanism.

Evanescent excitation microscopy. Its application to the study of single molecular process kinetics of actomyosin motor

Evanescent field was generated on the stage of an inverted microscope upon an incidence of 532 nm Nd-YAG laser beam on interface between aqueous solution and fused silica glass. Thick filaments isolated from Mytilus edulis were adsorbed to the glass surface and nanomolar concentration of adenosine triphosphate (ATP) labeled with rhodamine was allowed to interact with thick filaments. The fluorescence from the surface was observed by triple-view microscopy at video rate. There were many fluorescent spots at the interface, which we identified as individual fluorescent ATP molecules. We found that the fluorescence from those spots was polarized. Fluorescence intensity of individual spots fluctuated considerably. We interpret the latter observation as a result of change in the orientation of emission dipole of the fluorescent ATP analog.

Effect of inhaled nitric oxide on gas exchange in patients with congestive heart failure. A randomized, controlled trial

BACKGROUND

Conventional vasodilators increase ventilation-perfusion mismatch and do not improve gas exchange even though they reduce pulmonary hypertension. However, the effects of nitric oxide inhalation on ventilatory and gas exchange values in patients with congestive heart failure are not known.

OBJECTIVE

To investigate the effect of nitric oxide inhalation on gas exchange in patients with congestive heart failure.

DESIGN

Randomized, controlled trial.

SETTING

University hospital.

PATIENTS

16 patients with congestive heart failure (New York Heart Association class II or III).

INTERVENTIONS

Patients inhaled nitric oxide gas at graded concentrations (n = 8) or were given intravenous isosorbide dinitrate, 2.5 mg (n = 8).

MEASUREMENTS

Hemodynamic and ventilatory variables and blood gases were measured 5 minutes after inhalation of different doses of nitric oxide and 10 minutes after administration of isosorbide dinitrate.

RESULTS

Nitric oxide inhalation reduced the mean pulmonary arterial pressure in a dose-dependent manner without altering the mean arterial pressure or cardiac output. At a dose of 40 parts per million, nitric oxide inhalation increased PaO2 (change from baseline, 12.0 mm Hg [95% CI, 2.3 to 21.7 mm Hg]; P = 0.014) and decreased the alveolar-arterial difference in partial pressure of oxygen (change, -8.6 mm Hg [CI, -16.8 to -0.4 mm Hg]; P = 0.038) and the ventilatory equivalent for carbon dioxide output (change, -6.7 [CI, -10.3 to -3.1]; P < 0.001). Although isosorbide dinitrate similarly decreased pulmonary arterial pressure, it did not alter gas exchange or ventilatory variables.

CONCLUSIONS

Because nitric oxide inhalation improved gas exchange, it may be used as a supportive therapy when other conventional vasodilators worsen gas exchange.

Estimation of the area under the concentration-versus-time curve of carboplatin following irinotecan using a limited sampling model

OBJECTIVES

The aim of this study was to develop limited sampling models for estimating the area under the concentration-versus-time curve (AUC) of carboplatin.

METHODS

Based on pharmacokinetic analyses of 14 patients who received 300 mg x m2 of carboplatin over a 90-min infusion following irinotecan, we developed limited sampling models with stepwise multiple linear regression analysis. We validated these models to be unbiased and precise using pharmacokinetic data of a second group of 14 patients. We also compared the observed and the predicted AUC in the patients using Calvert's formula with the patients' renal function.

RESULTS

We developed the following models: AUC (mg x ml(-1) x min) = 0.784 x C4 + 1.30 (r2=0.930) and AUC=0.100 x C0.25 + 0.597 x C4 + 0.140 (r=0.992), where C0.25 and C4 denote unbound plasma concentrations (microg x ml(-1)) of carboplatin at 0.25 h and 4 h after the end of infusion, respectively. These models were validated to be unbiased and precise: a mean prediction error (MPE) with standard deviation (SD) = 2.41 (9.45)% and a root mean squared error (RMSE) = 9.42% for the one-sample model, and MPE with (SD) = 1.22 (5.56)% and RMSE = 5.49% for the two-sample model. We also calculated predicted AUC in the patients using Calvert's formula: MPE with (SD)= -5.87 (21.5)% and RMSE = 21.5%.

CONCLUSIONS

These estimations were, as expected, more accurate than the prediction using Calvert's formula based on patients' renal function. The result of this study confirmed the idea that the pharmacokinetic parameters derived from limited sampling models would be more suitable for pharmacokinetic analysis of carboplatin than those obtained using Calvert's formula.

UGT1A1 genotypes and glucuronidation of SN-38, the active metabolite of irinotecan

BACKGROUND

Irinotecan (CPT-11) is metabolized by esterase to form a SN-38, which is further conjugated by UGT1A1. Genetic polymorphism has been shown in a promoter region of UGT1A1 and is related to its activity. We investigated whether there might be an inter-individual difference in pharmacokinetics of SN-38 and its glucuronide, depending on the genotypes of UGT1A1.

PATIENTS AND METHODS

Nine male patients with lung cancer were treated with irinotecan (50 mg/m2) and carboplatin. Pharmacokinetic parameters were calculated with full sampling plasma data. Genotypes were determined by analyzing the sequence of TATA box of UGT1A1 of genomic DNA from the patients.

RESULTS

The genotyping analysis revealed one heterozygote (6/7) and one homozygote (7/7) for (TA)7TAA allele (UGT1A1*28). The remaining seven patients were homozygote for (TA)6TAA allele (6/6, wild type). The metabolic ratios (SN-38/SN-38 glucuronide) in the patient with 7/7 genotype were uncharacteristically higher than those in the patients with other genotypes (6/6 and 6/7). Biliary index was 6980 versus 2180 +/- 1110 (range 840-3730) in patients with 7/7 versus 6/6 genotypes, respectively.

CONCLUSION

These results support the idea that the patient with 7/7 genotype has an impaired capacity for glucuronidation of SN-38.

Role of positron emission tomography using fluorine-18 fluoro-2-deoxyglucose in predicting improvement in left ventricular function in patients with idiopathic dilated cardiomyopathy

Improvement in left ventricular (LV) function in patients with idiopathic dilated cardiomyopathy (DCM) by medical treatment has been suggested. Thus, it is important to evaluate which patients will respond to medical therapy. Positron emission tomography (PET) with fluorine-18 fluoro-2-deoxyglucose (FDG) and cardiac catheterization were performed in 20 patients with DCM before the initiation of medical therapy. The regional myocardial glucose utilization rate (rMGU) was measured with FDG PET. Subjects were divided into two groups, group 1 (event-free patients, n=10) and group 2 (clinical cardiac events, n=10). Haemodynamic and PET parameters before the initiation of medication were compared between the two groups and between patients with and patients without improvement in LV function. Ejection fraction (EF) was significantly higher in group 1 (35.8%+/-9.0%) than in group 2 (24.8%+/-7.0%) and LV end-diastolic pressure (LVEDP) was significantly lower in group 1 (8.4+/-1.7 mmHg) than in group 2 (11.6+/-3.5 mmHg). Average rMGU (mg min-1 100 g-1) was similar in group 1 (11.2+/-2.5 mg min-1 100 g-1) and group 2 (11.2+/-2.9 mg min-1 100 g-1), while %CV of rMGU was significantly lower in group 1 (11.1%+/-6.3%) than in group 2 (29. 9%+/-13.9%, P<0.01). Furthermore, LV function normalized in seven patients in group 1. In these seven patients, EF (35.1%+/-10.9%), LVEDP (8.2+/-2.0 mmHg) and average rMGU (11.8+/-2.7 mg min-1 100 g-1) were comparable with those in patients without LV functional improvement (EF: 31.6%+/-9.1%; LVEDP: 10.7+/-3.3 mmHg; average rMGU: 10.8+/- 2.7 mg min-1 100 g-1). However,% CV of rMGU in patients with LV functional improvement (9.6%+/-5.6%) was significantly lower than in those without such improvement (26.3%+/-14.1%, P<0.01). %CV of rMGU <13.6% predicted prognosis with a sensitivity of 80%, a specificity of 100% and an accuracy of 90%. %CV of rMGU <13.6% also predicted improvement in LV function, with a sensitivity of 75%, a specificity of 92% and an accuracy of 85%. However, EF failed to predict improvement of LV function. In is concluded that homogeneous myocardial glucose utilization rate can predict both prognosis and improvement in LV function achieved by medical therapy in patients with DCM.

Comparison of unitary displacements and forces between 2 cardiac myosin isoforms by the optical trap technique: molecular basis for cardiac adaptation

To provide information on the mechanism of cardiac adaptation at the molecular level, we compared the unitary displacements and forces between the 2 rat cardiac myosin isoforms, V1 and V3. A fluorescently labeled actin filament, with a polystyrene bead attached, was caught by an optical trap and brought close to a glass surface sparsely coated with either of the 2 isoforms, so that the actin-myosin interaction took place in the presence of a low concentration of ATP (0.5 micromol/L). Discrete displacement events were recorded with a low trap stiffness (0.03 to 0.06 pN/nm). Frequency distribution of the amplitude of the displacements consisted of 2 gaussian curves with peaks at 9 to 10 and 18 to 20 nm for both V1 and V3, suggesting that 9 to 10 nm is the unitary displacement for both isoforms. The duration of the displacement events was longer for V3 than for V1. On the other hand, discrete force transients were recorded with a high trap stiffness (2.1 pN/nm), and their amplitude showed a broad distribution with mean values between 1 and 2 pN for V1 and V3. The durations of the force transients were also longer for V3 than for V1. These results indicate that both the unitary displacements and forces are similar in amplitude but different in duration between the 2 cardiac myosin isoforms, being consistent with the reports that the tension cost is higher in muscles consisting mainly of V1 than those consisting mainly of V3.