Association between evolocumab use and slow progression of aortic valve stenosis

No medications have been reported to inhibit the progression of aortic valve stenosis (AS). The present study aimed to investigate whether evolocumab use is related to the slow progression of AS evaluated by serial echocardiography. This was a retrospective observational study from 2017 to 2022 at Yokohama City University Medical Center. Patients aged ≥ 18 with moderate AS were included. Exclusion criteria were (1) mild AS; (2) severe AS defined by maximum aortic valve (AV) velocity ≥ 4.0 m/s; and/or (3) no data of annual follow-up echocardiography. The primary endpoint was the association between evolocumab use and annual changes in the maximum AV-velocity or peak AV-pressure gradient (PG). A total of 57 patients were enrolled: 9 patients treated with evolocumab (evolocumab group), and the other 48 patients assigned to a control group. During a median follow-up of 33 months, the cumulative incidence of AS events (a composite of all-cause death, AV intervention, or unplanned hospitalization for heart failure) was 11% in the evolocumab group and 58% in the control group (P = 0.012). Annual change of maximum AV-velocity or peak AV-PG from the baseline to the next year was 0.02 (- 0.18 to 0.22) m/s per year or 0.60 (- 4.20 to 6.44) mmHg per year in the evolocumab group, whereas it was 0.29 (0.04-0.59) m/s per year or 7.61 (1.46-16.48) mmHg per year in the control group (both P < 0.05). Evolocumab use was associated with slow progression of AS and a low incidence of AS events in patients with moderate AS.

Influence of Obstructive Apnea Index on Persistent Left Ventricular Dysfunction in Patients with ST-Segment Elevation Myocardial Infarction

Background: We retrospectively investigated the effects of the severity and classification of sleep-disordered breathing (SDB) on left ventricular (LV) function in patients with ST-segment elevation myocardial infarction (STEMI). Methods: A total of 115 patients with STEMIs underwent a sleep study using a multichannel frontopolar electroencephalography recording device (Sleep Profiler) one week after STEMI onset. We evaluated LV global longitudinal strain (LV-GLS) using two-dimensional echocardiography at one week and seven months. Patients were classified as no SDB (AHI < 5 events/h), obstructive SDB (over 50% of apnea events are obstructive), and central SDB (over 50% of apnea events are central). Due to the device's limitations in distinguishing obstructive from central hypopnea, SDB classification was based on apnea index percentages. Results: The obstructive apnea index (OAI) was significantly associated with LV-GLS at one week (r = 0.24, p = 0.027) and seven months (r = 0.21, p = 0.020). No such correlations were found for the central apnea index and SDB classification. Multivariable regression analysis showed that the OAI was independently associated with LV-GLS at one week (β = 0.24, p = 0.002) and seven months (β = 0.20, p = 0.008). Conclusions: OAI is associated with persistent LV dysfunction assessed by LV-GLS in STEMI.

Echocardiographic Findings of Malignant Lymphoma with Cardiac Involvement: A Single-center Retrospective Observational Study

Objective Although malignant lymphoma (ML) can occur in every organ, diagnosing cardiac involvement without cardiac manifestations is difficult. We therefore investigated the incidence of cardiac involvement in ML in our hospital and clarified the transthoracic echocardiography (TTE) findings of cardiac involvement. Methods Patients with ML referred to our hospital between January 2013 and December 2019 were retrospectively reviewed. Patients During the study period, 453 patients were identified. The mean age was 64.9 years old, and 54% of the patients were men. Results Diffuse large B-cell lymphoma (DLBCL) was the most common lymphoma, followed by follicular lymphoma. Of the 453 patients, 394 (87.0%) underwent TTE at the initial diagnosis or during the clinical course. The performance rates of TTE in DLBCL, Hodgkin lymphoma, and mantle cell lymphoma were above 90%. Cardiac involvement was detected in 6 (five with DLBCL and one with B-cell lymphoma) (1.5%) of the 394 patients who underwent TTE. The involved lesions of the heart varied, and five patients had pericardial effusion. Five patients had a preserved left ventricular ejection fraction. All patients were treated with chemotherapy, and some were treated with radiation and surgery. Conclusion Cardiac involvement was observed in six (1.5%) of the patients with ML who underwent TTE. B-cell lymphoma, especially DLBCL, is a common ML with cardiac involvement. Although five patients had pericardial effusion, the involved lesions of the heart were not uniform. TTE is a useful imaging modality to noninvasively and repeatedly evaluate the tumor characteristics, response to ML treatment, and cardiac function.

Clinical Usefulness of Echocardiographic Measurement of Proximal Aortic Diameter in Early Differentiation Between Type A Acute Aortic Dissection and ST-Segment-Elevation Myocardial Infarction

Background Contradictions between management modalities of type A acute aortic dissection (TAAAD) and ST-elevation-myocardial infarction (STEMI) may result in clinical catastrophe. Therefore, we aimed to explore which 2-dimensional echocardiography (2DE) findings are optimal for differentiating TAAAD from STEMI. Methods and Results This study included 340 patients with STEMI and 340 patients with TAAAD who underwent 2DE in the emergency department between 2012 and 2021. The proximal ascending aorta (PAA) diameter and other echocardiographic parameters were analyzed. PAA diameters were measured at 4 levels in the parasternal view: Valsalva, the sinotubular junction (STJ), the PAA at 1 cm above the STJ, and the PAA at 2 cm above the STJ. Receiver-operating characteristic curve analysis showed that Valsalva, STJ, PAA at 1 cm above the STJ, and PAA at 2 cm above the STJ were significant predictors of TAAAD (areas under the curve: 0.777, 0.924, 0.965, and 0.975, respectively; P<0.001) with the respective cutoff values of 39.4, 38.5, 39.8, and 41.2 mm. Multivariable analysis suggested that all 2DE parameters were significant predictors of TAAAD. Among the 2DE parameters examined, the incorporation of PAA at 2 cm above the STJ to clinical indicators exhibited the most significant diagnostic capability (C-statistics, 0.97; net reclassification improvement, 1.81; integrated discrimination improvement, 0.61). When only TAAAD with coronary malperfusion and STEMI were analyzed, the diagnostic utility of PAA at 1 cm above the STJ was evident (C-statistics, 0.99; net reclassification improvement, 1.79; integrated discrimination improvement, 0.67), with PAA at 2 cm above the STJ ranking second in diagnostic significance (C-statistics, 0.99; net reclassification improvement, 1.12; integrated discrimination improvement, 0.66). Conclusions PAA measurements were the most beneficial for diagnosing TAAAD in all 2DE findings and TAAAD from STEMI.

Prognostic importance of glycemic variability on left ventricular reverse remodeling after the first episode of ST-segment elevation myocardial infarction

BACKGROUND

This study aimed to investigate the effect of glycemic variability (GV), determined using a continuous glucose monitoring system (CGMS), on left ventricular reverse remodeling (LVRR) after ST-segment elevation myocardial infarction (STEMI).

METHODS

A total of 201 consecutive patients with STEMI who underwent reperfusion therapy within 12 h of onset were enrolled. GV was measured using a CGMS and determined as the mean amplitude of glycemic excursion (MAGE). Left ventricular volumetric parameters were measured using cardiac magnetic resonance imaging (CMRI). LVRR was defined as an absolute decrease in the LV end-systolic volume index of > 10% from 1 week to 7 months after admission. Associations were also examined between GV and LVRR and between LVRR and the incidence of major adverse cardiovascular events (MACE; cardiovascular death, acute coronary syndrome recurrence, non-fatal stroke, and heart failure hospitalization).

RESULTS

The prevalence of LVRR was 28% (n = 57). The MAGE was independent predictor of LVRR (odds ratio [OR] 0.98, p = 0.002). Twenty patients experienced MACE during the follow-up period (median, 65 months). The incidence of MACE was lower in patients with LVRR than in those without (2% vs. 13%, p = 0.016).

CONCLUSION

Low GV, determined using a CGMS, was significantly associated with LVRR, which might lead to a good prognosis. Further studies are needed to validate the importance of GV in LVRR in patients with STEMI.

Mechanical dispersion combined with global longitudinal strain estimated by three dimensional speckle tracking in patients with ST elevation myocardial infarction

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LV mechanical dispersion is a measure of regional heterogeneity of myocardial contraction.

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LV mechanical dispersion has been reported as an important prognosticator in STEMI.

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3D speckle tracking enables us to precisely measure LV mechanical dispersion.

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LV mechanical dispersion by 3D speckle tracking can precisely predict prognosis.

Background

The role of left ventricular (LV) mechanical dispersion estimated after an ST elevation acute myocardial infarction (STEMI) remains unclear.

Methods

The study participants were 208 consecutive patients (152 men, age = 72 years) presenting with STEMI for the first time who underwent primary percutaneous coronary intervention (PCI) within 12 h of STEMI onset. Within 48 h of PCI (mean = 24 h), 2D and 3D speckle-tracking echocardiography were performed. The global longitudinal strain (GLS) was calculated using 3D (3D-GLS) and 2D (2D-GLS) speckle tracking. Mechanical dispersion was defined using the standard deviation (SD) of the time to regional peak longitudinal strain (LS) for all 16 segments for both 2D-STE and 3D-STE (2D-LS-SD, 3D-LS-SD). Infarct size was estimated by Tc99m-sestamibi as the total area of < 50% of the uptake area at 2 weeks. The patients were followed up for a longer period of time (median118months) and checked for major adverse cardiac events (MACE: cardiac death, heart failure).

Results

During follow-up, 55 patients experienced MACE. The cut-off values were determined using receiver operating characteristic curves. The multivariate analysis revealed that a 3D-LS-SD > 56.7 ms was a significant predictor of MACEs (hazard ratio = 1.991, 95% confidence interval 1.033–3.613, p = 0.03), but 2D-LS-SD > 58.1 ms was not an independent predictor of MACEs (hazard ratio = 1.577, 95% confidence interval 0.815–3.042, p = 0.1). Furthermore, the combination of 3D-GLS and 3D-LS-SD had accurate predictability for MACE, as shown by the Kaplan-Meier curves (log rank, χ² = 94.1, p < 0.0001).

Conclusions

LV mechanical dispersion besides 3D-GLS assessed by 3D-STE immediately after PCI can predict long-term prognosis.

Prognostic Significance of the Combination of Left Atrial Reservoir Strain and Global Longitudinal Strain Immediately After Onset of ST-Elevation Acute Myocardial Infarction

BACKGROUND

The role of left atrial (LA) function in the long-term prognosis of ST-elevation acute myocardial infarction (STEMI) is still unclear.Methods and Results: Percutaneous coronary intervention (PCI) was performed in 433 patients with the first episode of STEMI within 12 h of onset. The patients underwent echocardiography 24 h after admission. LA reservoir strain and other echocardiographic parameters were analyzed. Follow up was performed for up to 10 years (mean duration, 91 months). The primary endpoint was major adverse cardiovascular events (MACE): cardiac death or hospitalization due to heart failure (HF). MACE occurred in 90 patients (20%) during the follow-up period. Multivariate Cox hazard analyses showed LA reservoir strain, global longitudinal strain (GLS), age and maximum B-type natriuretic peptide (BNP) were the significant predictors of MACE. Kaplan-Meier curves demonstrated that LA reservoir strain <25.8% was a strong predictor (Log rank, χ²=76.7, P<0.0001). Net reclassification improvement (NRI) demonstrated that adding LA reservoir strain had significant incremental effect on the conventional parameters (NRI and 95% CI: 0.24 [0.11-0.44]) . When combined with GLS >-11.5%, the patients with LA reservoir strain <25.8% were found to be at extremely high risk for MACE (Log rank, χ²=126.3, P<0.0001).

CONCLUSIONS

LA reservoir strain immediately after STEMI onset was a significant predictor of poor prognosis in patients, especially when combined with GLS.

Clinical Usefulness of the Serial Examination of Three-Dimensional Global Longitudinal Strain After the Onset of ST-Elevation Acute Myocardial Infarction

BACKGROUND

Two-dimensional (2D) and three-dimensional (3D) speckle tracking echocardiography (STE) after ST-elevation acute myocardial infarction (STEMI) can predict the prognosis. This study investigated the clinical significance of a serial 3D-STE can predict the prognosis after onset of STEMI.Methods and Results:This study enrolled 272 patients (mean age, 65 years) with first-time STEMI treated with reperfusion therapy. At 24 h after admission, standard 2D echocardiography and 3D full-volume imaging were performed, and 2D-STE and 3D-STE were calculated. Within 1 year, 19 patients who experienced major adverse cardiac events (MACE; cardiac death, heart failure requiring hospitalization) were excluded. Among the 253 patients, 248 were examined with follow-up echocardiography. The patients were followed up for a median of 108 months (interquartile range: 96-129 months). The primary endpoint was the occurrence of a MACE; 45 patients experienced MACEs. Receiver operating characteristic curves and Cox hazard multivariate analysis showed that the 2D-global longitudinal strain (GLS) and 3D-GLS at 1-year indices were significant predictors of MACE. The Kaplan-Meier curve demonstrated that a 3D-GLS of >-13.1 was an independent predictor for MACE (log-rank χ²=165.5, P<0.0001). The deterioration of 3D-GLS at 1 year was a significant prognosticator (log-rank χ²=36.7, P<0.0001).

CONCLUSIONS

The deterioration of 3D-GLS measured by STE at 1 year after the onset of STEMI is the strongest predictor of long-term prognosis.

Clinical usefulness of left ventricular outflow tract velocity time integral for heart failure with reduced ejection fraction with rapid atrial fibrillation during landiolol treatment

BACKGROUND

Landiolol enables us to treat the patients with rapid atrial fibrillation (AF) with acute decompensated heart failure (ADHF) efficiently. We sought to determine the role of echocardiography in predicting the prognosis.

METHODS

Among 314 patients, a total 115 ADHF patients with reduced ejection fraction and rapid AF were enrolled. They received landiolol treatment to decrease the heart rate (HR) to <110 bpm and change HR (ΔHR) of >20% within 24 h. The dose of landiolol was increased every 2 h; then, we performed echocardiography repeatedly, at baseline, 2 h, and 24h. We followed the patients after discharge for 180 days, and checked cardiac death and HF hospitalization as major adverse cardiac events (MACE).

RESULTS

During initial hospitalization, 5 patients (4%) died. During 180 days after discharge, 19 (16%) out of 115 patients experienced MACE (2 cardiac death, 17 HF rehospitalization, 5 in-hospital death). Multivariate analysis showed that the change in left ventricular outflow tract-velocity time integral (LVOT-VTI) at 2 h was the most significant predictor for MACE (hazard ratio =1.21, 95% confidence interval: 1.10-1.83, p=0.0001). Kaplan-Meier curves demonstrated the patients with deteriorated LVOT-VTI at minimum dose landiolol suggested the high-risk patients for MACE (χ²=30.9, p<0.0001).

CONCLUSIONS

During landiolol treatment, the patients with deteriorated LVOT-VTI predicted the poor prognosis. We may detect the high-risk patients by two-point echocardiography. UMIN000020084. Registered 1 November 2013 - prospective study https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&language=J&recptno=R000023203.

Impact of red blood cell distribution width and mean platelet volume in patients with ST-segment elevation myocardial infarction

The complete blood cell count is one of the most frequently ordered laboratory tests, and many parameters, including red blood cell distribution width (RDW) and mean platelet volume (MPV), are available. The purpose of this study was to investigate the usefulness of the combination of RDW and MPV in patients with ST-segment elevation myocardial infarction (STEMI). Patients with STEMI who underwent primary percutaneous coronary intervention were retrospectively enrolled (n = 229). The association between RDW as well as MPV and cardiovascular events was investigated. The median age was 67 years, and males made up 85% of the sample. Median RDW was 13.6%, and median MPV was 8.2 fL. During a median follow-up period of 528 days (IQR 331.5-920.5), 41 patients died or experienced major adverse cardiac and cerebrovascular events (MACCEs). Patients with RDW ≧ 13.7% had more deaths or MACCEs with marginal significance (p = 0.0799). Patients with MPV ≧ 8.3 fL had significantly more deaths or MACCEs (p = 0.0283). Patients with RDW ≧ 13.7% and MPV ≧ 8.3 fL had significantly more deaths or MACCEs (p = 0.0185). MPV was significantly associated with death or adverse events in patients with STEMI who were treated with primary PCI. RDW had only a weak association with death or adverse events. The results of the combination of MPV and RDW were similar to those of MPV.

Clinical Significance of Late Diastolic Tissue Doppler Velocity at 24 Hours or 14 Days After Onset of ST-Elevation Acute Myocardial Infarction

Background: The significance of late diastolic velocity (a') obtained by tissue Doppler imaging (TDI), which reveals atrial function, in ST-elevation myocardial infarction (STEMI) remains unclear. This study evaluated the association of TDI parameters determined either immediately or 2 weeks after percutaneous coronary intervention (PCI) with long-term outcomes. Methods and Results: In all, 740 patients with first-time STEMI underwent immediate PCI (i.e., within 12 h of onset). Echocardiography was performed in 307 patients 2 weeks after onset (Group A; mean age 64 years, 249 males), in 277 patients immediately after PCI (Group B; mean age 65 years, 229 males), and in 156 patients twice (i.e., immediately and 2 weeks after PCI; Group C; mean age 65 years, 135 males). Patients were followed-up for up to 10 years (mean 81 months). The primary endpoints were cardiac death or heart failure hospitalization. Major adverse cardiovascular events (MACE) occurred in 143 patients (19%) during the follow-up period. Both univariate and multivariate Cox hazard analyses were used to determine predictors of MACE. At 24 h and 2 weeks after STEMI onset, a' and E/e' were the strongest predictors of MACE, respectively. Conclusions: TDI parameters have different implications depending on the timing of echocardiography after a first-time STEMI. Based on the results of this study, atrial dysfunction measured by TDI 24 h after STEMI onset may indicate a poor prognosis.

Global Strain Measured by Three-Dimensional Speckle Tracking Echocardiography Is a Useful Predictor for 10-Year Prognosis After a First ST-Elevation Acute Myocardial Infarction

BACKGROUND

Three-dimensional (3D) speckle tracking echocardiography (STE) after ST-elevation acute myocardial infarction (STEMI) is associated with left ventricular (LV) remodeling and 1-year prognosis. This study investigated the clinical significance of 3D-STE in predicting the long-term prognosis of patients with STEMI.Methods and Results:A total of 270 patients (mean age 64.6 years) with first-time STEMI treated with reperfusion therapy were enrolled. At 24 h after admission, standard 2D echocardiography and 3D full-volume imaging were performed, and 2D-STE and 3D-STE were calculated. Patients were followed up for a median of 119 months (interquartile range: 96-129 months). The primary endpoint was occurrence of a major adverse cardiac event (MACE: cardiac death, heart failure with hospitalization), and 64 patients experienced MACEs. Receiver operating characteristic curves and Cox hazard multivariate analysis showed that the 3D-STE indices were stronger predictors of MACE compared with those of 2D-STE. Additionally, 3D-global longitudinal strain (GLS) was the strongest predictor for MACE followed by 3D-global circumferential strain (GCS). The Kaplan-Meier curve demonstrated that 3D-GLS >-11.0 was an independent predictor for MACE (log-rank χ²=132.2, P<0.0001). When combined with 3D-GCS >-18.3, patients with higher values of 3D-GLS and 3D-GCS were found to be at extremely high risk for MACE.

CONCLUSIONS

Global strain measured by 3D-STE immediately after the onset of STEMI is a clinically significant predictor of 10-year prognosis.

Clinical significance of late diastolic tissue doppler parameters after onset of STEMI: from the view point of the timing of the echocardipography

Background

The early transmitral flow velocity (E) divided by the early diastolic velocity of the mitral valve annulus (e') is referred to as the “E/e' ratio,” is useful even for ST elevation acute myocardial infarction (STEMI). However, the role of late diastolic velocity (a') which reveals the atrial function for STEMI is still unclear.

Objectives

We evaluated the clinical usefulness of tissue Doppler including atrial function for a first-time STEMI by long time follow up. Furthermore, we evaluated the meaning of each parameters by performing immediately after PCI or 2 weeks later.

Methods

We treated consecutive 571 first-time STEMI patients by immediate PCI within 12 hours after onset, and we examined 270 patients at immediately after PCI (GroupA, 65 years, 250 male) and 301 patients at 2 weeks after onset (GroupB, 64 years, 243 male). We examined trans mitral flow and TDI, then defined E/e' as LV filling pressure and A/a' as left atrial function. We followed them for a long time (&gt;5 years). The primary end point (PE) was cardiac death or re-admission for heart failure (HF).

Results

We followed the patients in Group A for 10 years, Group B for 5 years. PE occurred in 64 patients in GroupA during 10 years, and 45 patients in GroupB during 5 years. We analyzed the univariate and multivariate Cox hazard analyses and we compared e' and a', E/e' and A/a' (Table). In GroupA, a' and A/a' were the independent predictors, on the other hand neither a' nor A/a' were the predictors in GroupB. E/e' was an independent predictor both in GroupA and B.

Conclusion

TDI parameters have different meanings by the timing of echocardiography after onset of a first-time STEMI. These results demonstrated that atrial dysfunction immediately after onset of STEMI suggests the poor prognosis after STEMI.

Cox Hazard Proportional Analysis

Funding Acknowledgement

Type of funding source: None

Serial echocardiographical assessment for urgent control of rapid atrial fibrillation in acute heart failure

Objectives

Doppler echocardiography is a well-recognized technique for noninvasive evaluation; however, little is known about its efficacy in patients with rapid atrial fibrillation (AF) accompanied by acute decompensated heart failure (ADHF). The aim of this study was to explore the usefulness of serial echocardiographical assessment for rapid AF patients with ADHF.

Patients

A total of 110 ADHF patients with reduced ejection fraction (HFrEF) and rapid AF who were admitted to the CCU unit and received landiolol treatmentto decrease the heart rate (HR) to &lt;110 bpm and change HR (ΔHR) of &gt;20% within 24 hours were enrolled.

Interventions

Immediately after admission, the patients (n=110) received landiolol, and its dose was increased to the maximum; then, we repeatedly performed echocardiography. Among them, 39 patients were monitored using invasive right heart catheterization (RHC) simultaneously with echocardiography.

Measurements and main results

There were significant relationships between Doppler and RHC parameters through the landiolol treatment (Figure, baseline–max HR treatment). We observed for the major adverse events (MAE) during initial hospitalization, which included cardiac death, HF prolongation (required intravenous treatment at 30 days), and worsening renal function (WRF). MAE occurred in 44 patients, and logistic regression analyses showed that the mean left atrial pressure (mLAP)-Doppler (odds ratio = 1.132, 95% confidence interval [CI]: 1.05–1.23, p=0.0004) and stroke volume (SV)-Doppler (odds ratio = 0.93, 95% confidence interval [CI]: 0.89–0.97, p=0.001) at 24 hours were the significant predictors for MAE, and multivariate analysis showed that mLAP-Doppler was the strongest predictor (odds ratio = 1.16, 95% CI: 0.107–1.27, p=0.0005) (Table).

Conclusions

During the control of the rapid AF in HFrEF patients withADHF, echocardiography was useful to assess their hemodynamic condition, even at bedside.

Doppler for rapid AF of ADHF

Funding Acknowledgement

Type of funding source: None

Prognostic Significance of a Combination of QRS Score and E/e' Obtained 2 Weeks After the Onset of ST-Elevation Myocardial Infarction

BACKGROUND

The early mitral inflow velocity to mitral early diastolic velocity ratio (E/e') and electrocardiogram (ECG) determination of QRS score are useful for risk stratification in patients with ST-elevation myocardial infarction (STEMI).Methods and Results:In this study, 420 consecutive patients (357 male; mean [±SD] age 63.6±12.2 years) with first-time STEMI who successfully underwent primary percutaneous coronary intervention within 12 h of symptom onset were followed-up for 5 years (median follow-up 67 months). Echocardiography, ECG, and blood samples were obtained 2 weeks after onset. Infarct size was estimated by the QRS score after 2 weeks (QRS-2wks) and creatine phosphokinase-MB concentrations (peak and area under the curve). The primary endpoint was death from cardiac causes or rehospitalization for heart failure (HF). During follow-up, 21 patients died of cardiac causes and 62 had HF. Multivariate Cox proportional hazard analysis showed that mean E/e' (hazard ratio [HR] 1.152; 95% confidence interval [CI] 1.088-1.215; P<0.0001), QRS-2wks (HR 1.153; 95% CI 1.057-1.254; P<0.0001), and hypertension (HR 1.702; 95% CI 1.040-2.888; P=0.03) were independent predictors of the primary endpoint. Kaplan-Meier curve analysis showed that patients with QRS-2wks >4 and mean E/e' >14 were at an extremely high risk of cardiac death or HF (log rank, χ²=116.3, P<0.0001).

CONCLUSIONS

In patients with STEMI, a combination of QRS-2wks and mean E/e' was a simple but useful predictor of cardiac death and HF.

Impact of three-dimensional global longitudinal strain for patients with acute myocardial infarction

AIMS

In patients with ST-segment elevation myocardial infarction (STEMI), predicting left ventricular (LV) remodelling (LVR) and prognosis is important. We explored the clinical usefulness of three-dimensional (3D) speckle-tracking echocardiography to predict LVR and prognosis in STEMI.

METHODS AND RESULTS

The study group comprised 255 first STEMI patients (65 years; 210 men) treated with primary percutaneous coronary intervention between April 2008 and May 2012 at Yokohama City University Medical Center. Baseline global longitudinal strain (GLS) was measured with two-dimensional (2D) and 3D speckle-tracking echocardiography. Within 48 of admission, standard 2D echocardiography and 3D full-volume imaging were performed, and 2D-GLS and 3D-GLS were calculated. Infarct size was estimated by 99mTc-sestamibi single-photon emission computed tomography. Echocardiography was performed at 1 year repeatedly in 239 patients. The primary endpoint was LVR, defined as an increase of 20% of LV end-diastolic volume index and major adverse cardiac and cerebrovascular events (MACE: cardiac death, non-fatal MI, heart failure, and ischaemic stroke) at 1 year, and the secondary endpoint was cardiac death and heart failure. Patients were followed for 1 year; 64, 25, and 16 patients experienced LVR, MACE, and the secondary endpoint, respectively. Multivariate analysis revealed that 3D-GLS was the strongest predictor of LVR (odds ratio = 1.437, 95% CI: 1.047-2.257, P = 0.02), MACE (odds ratio = 1.443, 95% CI: 1.240-1.743, P = 0.0002), and the secondary end point (odds ratio = 1.596, 95% CI: 1.17-1.56, P < 0.0001). Receiver-operating characteristic curve analysis showed that 3D-GLS was superior to 2D-GLS in predicting LVR and 1-year prognosis.

CONCLUSION

3D-GLS obtained immediately after STEMI is independently associated with LVR and 1-year prognosis.

Impact of flow-mediated dilatation and coronary calcification in providing complementary information on the severity of coronary artery disease

BACKGROUND AND AIMS

Endothelial dysfunction and coronary artery calcification (CAC) may represent two distinct and separate processes in the development of coronary atherosclerosis. However, the interaction between these factors in determining the development of coronary artery disease (CAD) is uncertain.

METHODS

Brachial artery flow-mediated dilatation (FMD) was measured by high-resolution ultrasound before coronary angiography, in 156 patients undergoing coronary CT angiography on suspicion of CAD (M/F 100/56, age 67 ± 11yrs). CAC score was measured with the Agatston method.

RESULTS

The discriminative performance of FMD and CAC score in predicting the presence of type C lesion, multivessel disease, and high SYNTAX score (>22) was determined by ROC curve analysis. The optimal cutoff values for type C lesion were FMD ≤3.70% (AUC 0.663, p = 0.037) and log(CACscore+1)≥ 6.452 (AUC 0.735, p = 0.006). The combination of these cutoff values identified the lesion with the highest predictive accuracy of 82%. In addition, the optimal cutoff values for multivessel disease were FMD ≤5.40% (AUC 0.689, p = 0.001) and log(CACscore+1)≥ 5.914 (AUC 0.731, p = 0.001), while those for high SYNTAX score were FMD ≤4.10% (AUC 0.664, p = 0.020) and log(CACscore+1) ≥6.693 (AUC 0.817, p = 0.001). The combined measurement of each cutoff value identified multivessel disease and high SYNTAX score with predictive accuracy of 77% and 83%, respectively, which were significantly higher than each parameter alone, with the exception of the predictive accuracy of log(CACscore+1) for high SYNTAX score (p = 0.083).

CONCLUSIONS

Endothelial dysfunction and CAC may provide complementary information in predicting the extent and severity of coronary artery disease.

Clinical application of radial magnetic resonance imaging for evaluation of rotator cuff tear

BACKGROUND

Magnetic resonance imaging is useful for evaluating the rotator cuff, but some tendinous insertions cannot be assessed using oblique sagittal, oblique coronal, and axial magnetic resonance (MR) images because of the presence of the partial volume effect.

HYPOTHESIS

The purpose of this study was to determine whether radial-slice MR images could reveal normal rotator cuff insertions and rotator cuff tears more clearly than conventional MR images.

PATIENTS AND METHODS

The study included 18 subjects with normal rotator cuffs and 30 with rotator cuff tears. MR images of rotator cuff insertions sliced into radial, oblique coronal, and axial sections were obtained. The extent to which normal rotator cuff insertions and rotator cuff tears were visualized in each of the three MR images was evaluated.

RESULTS

The top to posterior portions of the rotator cuff insertions from 0° to 120° could be visualized in the radial MR images. In comparison, the posterior portions of the rotator cuff insertions could not be visualized around 45° in both the oblique coronal and axial MR images.

DISCUSSION

These findings demonstrate that radial MR images are superior to the oblique coronal and axial MR images regarding their ability to accurately visualize rotator cuff insertions. Radial MR images also revealed greater detail around 45° in the posterior area of the rotator cuff tears than the oblique coronal and axial MR images. Radial MR images are particularly useful for visualizing clinically important posterosuperior rotator cuff tears.

LEVEL OF EVIDENCE

Level III - Diagnostic study.

Structural changes in dermal collagen and oxidative stress levels in the skin of Japanese overweight males

OBJECTIVE

It has been reported that obese people have poorly organized dermal collagen structure because of the degradation of collagen fibers, which is caused by an increase in oxidative stress levels associated with the hypertrophy of subcutaneous adipose cells. However, it is unclear whether an increase in oxidative stress levels caused by the accumulation of subcutaneous adipose tissue and a change in the dermal structure also occur in overweight and obese Japanese people. The objectives of this study are to identify structural changes that occur in the dermis and to measure the levels of oxidative stress in Japanese overweight males.

METHODS

The overweight group included 43 Japanese male volunteers aged between 25 and 64 years and with a body mass index (BMI) of ≥25 and <30. The control group included 47 male volunteers aged between 22 and 64 years and with BMI of <25. The 20-MHz Dermascan C® ultrasound scanner with software for image analyses was used. Echogenicity of the upper and lower dermis was measured. The mRNA expression level of heme oxygenase-1 (HMOX1) in hair follicles was quantitatively analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) and was used as a marker of oxidative stress. Ultrasonographic imaging and collection of hair follicles were performed at the same site on the thigh, abdomen, and upper arm.

RESULTS

The HMOX1 mRNA expression level in the abdomen and thigh was significantly lower in the overweight group than in the control group. Moreover, the echogenicity of the upper dermis of the abdomen and the lower dermis of the abdomen and thigh was significantly lower in the overweight group than in the control group.

CONCLUSION

We detected an increase in oxidative stress levels and a decrease in the density of dermal collagen at the same site on the thigh, abdomen, and upper arm of Japanese overweight males. These findings suggest the fragility of the dermis of Japanese overweight males, which might have been caused by the accumulation of subcutaneous adipose tissue.

Characteristic features of the acetabular labrum in healthy children

Radial magnetic resonance images of the acetabular labrum were obtained on 40 hips of healthy children. There were no right-left or male-female differences. In children aged 11 years or younger, the labrum on the antero-superior weightbearing portion was triangular in shape, and there was an insular-shaped or linear high-intensity area inside; on the mid-superior portion, the labrum appeared as a regular triangular, low-intensity area; and on the postero-superior portion, it was flat. In children aged 12 and 13 years, the shape of the labrum in each portion was similar to that of the younger children, but the high signal intensity area on the antero-superior portion appeared less frequently. The size of the labrum relative to the femoral head was greater in younger children.

Bombelli's valgus-extension osteotomy for osteoarthritis due to acetabular dysplasia: results at 10 to 14 years

Severe osteoarthritis due to acetabular dysplasia (n = 17) was treated with valgus-extension osteotomy, and the patients' clinical outcomes 10-14 years after operation were evaluated according to clinical factors (Japanese Orthopaedic Association hip score; JOA score) and by roentgenography. The mean JOA score 10 years or later had improved by 22 points compared with the preoperative score. On roentgenography, joints which had preoperative roof osteophyte had better postoperative formation of roof osteophyte. The JOA score was higher in the 12 joints which had osteophyte 5 mm or longer than in those joints with osteophyte that was 5 mm or shorter. Postoperative joint space widening occurred in 15 joints (88.2%) 3-6 months postoperatively, and it reached the maximum at 3-5 years. In patients who had a large bone cyst in the femoral head preoperatively, the cyst collapsed, and deformation of femoral head occurred after operation, but remodeling of the joint surface occurred naturally and the congruity improved. In the 6 joints in which the preoperative acetabular head index was less than 60% and the acetabular angle was larger than 30 degrees, the JOA score at 10 years or later was lower than that of the other joints. Based on these findings, valgus-extension osteotomy was evaluated as a useful surgical method for advanced or terminal osteoarthritis in young or middle-aged patients. Predictive factors for long-term prognosis would be the preoperative length of roof osteophyte, joint space widening, and the degree of femoral head covering.

Histological findings of bone marrow edema pattern on MRI in osteonecrosis of the femoral head

Sequential magnetic resonance imaging (MRI) was performed on a 38-year-old woman with systemic lupus erythematosus who had received corticosteroid and had developed non-traumatic osteonecrosis of the femoral head. The initial MR finding was a band lesion on the T1-weighted image, which had been present before the onset of symptoms. At the onset of symptoms, a diffuse bone marrow edema pattern, with a low signal intensity on T1 and high signal intensity on T2-weighted images, was noted around the band lesion, extending to the femoral neck. Histopathologically, this region was found to consist of serous exudate, focal interstitial hemorrhage, and mild fibrosis, without any evidence of extension of osteonecrosis. It should be noted that extension of a low signal intensity area on MRI after the onset of hip pain may not be the result of the extension of osteonecrosis, but may represent concomitant edema due to collapse.

Susceptibility to acyclovir of herpes simplex virus isolates obtained between 1977 and 1996 in Japan

The susceptibility of genital herpes to acyclovir (ACV) in immunocompetent women was examined, as was the frequency of ACV-resistant viruses by analyzing 56 clinical isolates in Japan between 1977 and 1996. The mean susceptibilities of herpes simplex virus (HSV) type 1 and type 2 were 0.13+/-0.74 and 0.42+/-0.14 microg/ml, respectively, assessed by the 50% inhibitory concentration of plaque formation. The susceptibility to ACV of clinical isolates did not changed since 1977, and also that of nine pairs of HSV-1 and HSV-2 isolates was not affected by ACV treatment. In order to characterize the change in the virus population, the quantitation of the ACV-resistant virus in 10(4) plaque forming units (PFU) of clinical isolates was adopted. The mean frequencies of ACV-resistant viruses per 10(4) PFU for all strains of HSV-1 and HSV-2 were 0.31+/-0.41 and 9.74+/-14.83, respectively, and were not influenced by ACV treatment. Additionally, the phenotypes of ACV-resistance were not influenced by ACV treatment, and more than 90% of ACV-resistant viruses were found to be thymidine kinase-deficient. This study characterized clinical isolates with respect to ACV susceptibility as a population and the quantitative and qualitative characterization of ACV-resistant virus in the virus population of clinical isolates was also studied. The susceptibility of isolates from genital lesions, the frequency of ACV-resistant viruses, and also the phenotypic characterization of ACV-resistant viruses was maintained between 1977 and 1996, even after the introduction of ACV treatment for genital herpes in Japan.

Physiological profile of middle-aged and older climbers who ascended Gasherbrum II, an 8035-m Himalayan peak

BACKGROUND

The purpose of this study was to investigate the physiological characteristics of a group of middle-aged and older Japanese climbers who ascended Gasherbrum II, an 8035-m peak in the Karakoram Range of the Himalayas.

METHODS

Body composition, cardiac structure, and respiratory gas exchange during exercise were estimated in eight climbers with differing levels of experience (seven men and one woman, aged 54 to 63 years) 6 months before their expedition.

RESULTS

Using supplementary O2, the four experienced climbers ascended beyond Camp 4 (7400 m) without showing any health problems and were able to attempt the summit. In contrast, the others, who had minimal experience at extreme altitude, suffered from altitude sickness on the way to Camp 4. Body mass index values were relatively high, but their low percentage of body fat (14.9%-21.4%) was indicative of the climbers' substantial lean body weight. Cardiac structures were generally normal, although three experienced male climbers had borderline hypertension and eccentric hypertrophy of the left ventricle. Peak VO2 ranged from 30.9 to 45.6 ml/kg/min, and no significant relationship between fitness level and the success or failure of the ascent was evident.

CONCLUSIONS

Even sexagenarians are capable of safely climbing 8000-m peaks with supplementary O2. An exceptionally high fitness level, as is seen in elite older athletes, does not appear to be required. What is essential, however, is moderate fitness, good health, and extensive experience.

Radial magnetic resonance imaging and pathological findings of acetabular labrum in dysplastic hips

Radial MRI findings and pathological changes were comparatively examined in the acetabular labrum of 11 hips of 11 patients, who underwent total hip arthroplasty for osteoarthritis due to acetabular dysplasia. Diffuse high signal pattern on the radial MR images corresponded to histological degeneration of the labrum. High signal pattern which was equivalent to the synovial fluid, showed an intralabral tear. In the obscure areas of MR images, severe impairment of the labrum such as rupture, detachment, and displacement were found.

Acetabular labrum in hip dysplasia evaluated by radial magnetic resonance imaging

OBJECTIVE

To numerically express morphologic conditions and signal intensity in the acetabular labrum of the weight-bearing portion of hip joints in patients with hip dysplasia.

METHODS

Using a radial magnetic resonance imaging (MRI) technique, where the planes are set radially centered on the midpoint of acetabulum, and which depicts the entire acetabular rim and acetabular labrum, we investigated 60 hip joints of 35 patients with hip dysplasia.

RESULTS

The acetabular labrum was larger in dysplastic hips than in normal hips, and the size increased in the posterosuperior portion. All patients had portions with signal intensity changes within the labrum and had impairment on the labrum. When osteoarthrosis due to hip dysplasia was observed, signal intensity changes increased. The changes of intensity varied among the portions observed, and were stronger in the anterosuperior portions than in the superior and posterosuperior portions.

CONCLUSION

Radial MRI numerically depicts morphologic conditions of acetabular labrum; the data were usable to evaluate the size difference in acetabular labrum due to hip dysplasia and the degree of impairment.

The conformation of alpha-(1-->4)-linked glucose oligomers from maltose to maltoheptaose and short-chain amylose in solution

The conformation of maltose-type oligomers in water and in dimethylsulfoxide (Me2SO) was studied using two-dimensional NMR spectra. In Me2SO all of the oligomers have a 1a-type conformation. In water, they tend to adopt the same conformation, but the oligomers are looser and more flexible than in Me2SO.

Radial MRI of the hip with moderate osteoarthritis

We carried out radial MRI in 30 hips with moderate osteoarthritis and in ten normal hips. On a scout view containing the entire acetabular rim, 12 vertical radial slices were set at 15° intervals. Different appearances were observed in different parts of the joint. In the weight-bearing portion, from 45° anterosuperior to 45° posterosuperior, ‘attenuation’ (n = 16) and ‘disappearance’ (n = 25) were observed as abnormalities of the labrum with ‘capsular stripping’ (n = 29) and ‘extraosseous high signal lesion’ (n = 27) as capsular abnormalities, seen more often in the anterosuperior portion. In all 12 planes there were osteophytes on the acetabular edge (n = 24), femoral head (n = 22) and/or at the central acetabulum (n = 6), a bone cyst on the acetabulum (n = 18) and/or the femoral head (n = 9), irregularity of the articular cartilage (n = 30), and an effusion (n = 28). Our findings indicate that radial MRI may be a useful non-invasive diagnostic method for demonstrating pathology in moderate osteoarthritis of the hip.

Radial MRI of the hip with moderate osteoarthritis

We carried out radial MRI in 30 hips with moderate osteoarthritis and in ten normal hips. On a scout view containing the entire acetabular rim, 12 vertical radial slices were set at 15 degrees intervals. Different appearances were observed in different parts of the joint. In the weight-bearing portion, from 45 degrees anterosuperior to 45 degrees posterosuperior, 'attenuation' (n = 16) and 'disappearance' (n = 25) were observed as abnormalities of the labrum with 'capsular stripping' (n = 29) and 'extraosseous high signal lesion' (n = 27) as capsular abnormalities, seen more often in the anterosuperior portion. In all 12 planes there were osteophytes on the acetabular edge (n = 24), femoral head (n = 22) and/or at the central acetabulum (n = 6), a bone cyst on the acetabulum (n = 18) and/or the femoral head (n = 9), irregularity of the articular cartilage (n = 30), and an effusion (n = 28). Our findings indicate that radial MRI may be a useful non-invasive diagnostic method for demonstrating pathology in moderate osteoarthritis of the hip.

In vitro maturation and ultrastructural observation of cryopreserved minke whale (Balaenoptera acutorostrata) follicular oocytes

Minke whale (Balaenoptera acutorostrata) follicular oocytes were cryopreserved by a slow-step freezing procedure using ethylene glycol. The morphologically viable proportion of postthawed minke whale follicular oocytes was 39.7%. The maturity of the animals (immature and mature whales) or the presence or absence of cumulus cells (CC) did not affect the proportion of morphologically viable oocytes. Postthawed oocytes were examined for nuclear status after in vitro maturation. The presence of CC (29.1%) significantly enhanced (P < 0.05) the proportion of oocytes at metaphase I/anaphase I/telophase I stages compared to results with the absence of CC (13.5%). A total of 4 of 194 postthawed oocytes matured to the second metaphase stage after culture for 5.5 days with or without CC. The cryopreserved immature oocytes obtained from immature and mature whales were processed to examine the ultrastructure by transmission electron microscopy. Varying ultrastructural damage to the cytoplasm was observed as a result of the cryopreservation procedures. These results show that 20-30% of cryopreserved minke whale follicular oocytes can resume meiosis in vitro, but damage induced by the freezing and thawing procedures was observed.

Radial-sequence magnetic resonance imaging in evaluation of acetabular labrum

We investigated the usefulness of a radial-sequence magnetic resonance imaging (MRI) technique in the visualization of the acetabular labrum, which surrounds the acetabulum. In 22 hip joints of 12 volunteers, T2-weighted images were obtained on 24 radial planes of the acetabular rim, set at 15 degrees -intervals, using the small tip angle gradient echo method. We examined 7 planes in the weight-bearing portion. The acetabular labrum in the weight-bearing portion was depicted in good contrast to the surrounding tissues. The shape of the labrum differed among individuals and also in the anterior and posterior portions of the labrum. The signal intensity of the labrum was low or partially moderate. There was a high signal intensity band on the base of the acetabular labrum in several portions, which should be carefully interpreted to avoid confusion with abnormality. We concluded that radial-sequence MRI could be a useful technique for evaluation of the condition of the acetabular labrum in the weight-bearing portion.

Effects of exercise training on the heart rate variability and QT dispersion of patients with acute myocardial infarction

Heart rate variability (HRV) reflects the autonomic tone of the heart, and QT dispersion reflects the regional inhomogeneity of ventricular repolarization. The purpose of the present study was to determine the effects of early exercise training on HRV and QT dispersion in patients with acute myocardial infarction (AMI). Forty patients (mean age: 59 years) with AMI were randomized to training rehabilitation (group Tr, n=20) or conventional rehabilitation (group C, n=20). Two weeks after AMI, group Tr underwent 10 min of exercise using a bicycle ergometer (80% of anaerobic threshold) twice a day. At the end of the second and fourth weeks, 12-lead and 24-h Holter ECGs were recorded. QT intervals were measured and corrected using Bazett's formula (QTc), and QTc dispersion (QTcd) was defined as the difference between maximum and minimum QTc. HRV was accessed by the high-frequency component (HF: 0.15-0.40 Hz) of the HRV power spectrum (parasympathetic activity) and the ratio of low frequency (0.04-0.15 Hz) to HF (L/H ratio: sympathetic activity). In group Tr, HF increased (82.5 to 131.1 ms2), the L/H ratio decreased (3.9 to 2.6), and QTcd decreased (77.2 to 57.2 ms). In group C, none of the indices changed. It was concluded that early exercise training improves sympathovagal balance and decreases QTcd, and may reduce the arrhythmogenic substrate following AMI.

MRI evaluation of the inferior glenohumeral ligament. Comparison with arthroscopic findings in 81 shoulders

Arthroscopic Bankart repair, using staples, requires a thick and wide anterior band of the inferior glenohumeral ligament. We compared MRI and arthroscopic findings of the ligament in 81 shoulders with traumatic anterior glenohumeral instability. When fluid was present in the shoulder, sensitivity and specificity of the MRI evaluation for the presence of a thick and wide ligament were 82% and 100%, respectively. In shoulders without joint fluid, the condition of the ligament was evaluated according to the presence of a low- or moderate-signal triangle structure on the anterior margin of the glenoid cavity in the 3 MR images obtained from the inferior 2 cm of the glenoid. Sensitivity and specificity of the MRI evaluation in cases without fluid were 84% and 93%, respectively. The MR technique needs to be further improved to achieve better sensitivity for preoperative selection of shoulders suitable for Bankart repair with staples.

Subcellular distribution of 220 kDa antigen in the intercellular spaces of normal human epidermis

We generated a monoclonal antibody, 7C1, to an extract of pig snout skin used as antigen. The antigen for 7C1 was identified by immunoblotting as a 220 kDa epidermal protein. It was found immunologically to be distributed mainly in the intercellular spaces throughout the living cell layers of normal human epidermis, but its distribution changed in some keratinizing disorders. Study of the association of this protein with subcellular structures by immunoelectron microscopy of normal human skin revealed that it was localized in (1) lamellar granules, (2) intercellular spaces, especially in the lamellar structures derived from the lamellar granules, (3) small vesicles near the cell boundaries and (4) small vesicles in the Golgi apparatus. These results suggest that in humans the 220 kDa protein originates in the Golgi apparatus and is secreted via either the lamellar granules or the small secretory vesicles into the intercellular spaces of the epidermis, where it may be involved in the epidermal permeability barrier function and possibly in keratinizing differentiation.

Relationship between pulse sequences and signal intensity of joint fluid in the gradient-echo MR imaging

To depict the labrum and meniscus in terms of contrast to joint fluid by increasing its signal intensity, we examined in vitro and in a human subject the good imaging conditions of gradient-echo magnet resonance by using a 1.0 Tesla superconducting imager (Shimadzu). In our in vitro study, 3 types of joint fluid and physiological saline were imaged together with PVA gel (as the substitute for surrounding soft tissue), by using either the STAGE, SSFP, or STERF method, and with several TR's (repetition time); and mean signal intensity was obtained. In order to confirm the findings of the in vitro study, a human study was conducted: physiological saline was injected into a shoulder joint, and axial planes were depicted under the conditions equivalent to those of the in vitro study. With the STERF method, signal intensity of the fluid was high at any flip angle, but PVS gel and the surrounding soft tissues such as muscles were rarely depicted. With the STAGE and SSFP methods, depiction of the fluid, PVA gel, and the surrounding soft tissues were possible by setting an appropriate flip angle for TR: With the STAGE method (a spoiled gradient echo sequence), good imaging was possible by selecting small flip angle, regardless TR. Therefore, because of easiness in selecting conditions, the STAGE method is considered to be the best for diagnostic scanning.

Inhibitory action of acyclovir (ACV) and penciclovir (PCV) on plaque formation and partial cross-resistance of ACV-resistant varicella-zoster virus to PCV

Penciclovir has potent antiviral activity against varicella-zoster virus (VZV). We have characterized the inhibitory effects of penciclovir and acyclovir on the plaque formation of cell-free VZV and cross-resistance of acyclovir-resistant VZV to penciclovir. The apparent effective concentration for 50% plaque reduction (EC50) of penciclovir determined on the third day was significantly lower than that determined on the fourth or fifth day. The size of plaques was smaller in the presence of penciclovir than in the presence of acyclovir. The effective concentrations for 50% reduction of the number of infected cells per plaque were 1.40 and 5.00 micrograms/ml for penciclovir and acyclovir, respectively. Thus penciclovir suppressed spread of infection within developing plaques more efficiently than acyclovir. Five acyclovir-resistant VZV strains with altered DNA polymerase selected by acyclovir were examined for cross-resistance to penciclovir. They were 11- to 18-fold more resistant to ACV than the parent strain, but only 4- to 5-fold more resistant to PCV. Penciclovir-triphosphate carrying the 3'-hydroxyl group of 2'-deoxyribose might have better affinity to the altered viral DNA polymerase than acyclovir-triphosphate without the 3'-hydroxyl group.

Functional reconstitution of sphingomyelin synthase in Chinese hamster ovary cell membranes

Sphingomyelin synthase (phosphatidylcholine:ceramide phosphocholinetransferase) activity in the membranes of Chinese hamster ovary cells was found to be detectable with a fluorescent ceramide analog, containing a short acyl chain, as a substrate. We developed a method for the functional reconstitution of sphingomyelin synthase in detergent-treated membranes. Treatment of membranes with 1.5% octyl glucoside in the absence of exogenous phosphatidylcholine resulted in almost complete loss of sphingomyelin synthase activity, even after removal of the detergent by dialysis. In contrast, membranes treated with the detergent in the presence of exogenous phosphatidylcholine showed partial activity and, after dialysis of this mixture, enzyme activity was restored to almost the same level as the activity in dialyzed intact membranes. The effects of various lipids on enzyme activity in this reconstitution system suggested that L-alpha-phosphatidylcholine was the environmental lipid essential for the functional reconstitution of the enzyme. Furthermore, diacylglycerol was suggested to serve as an inhibitory regulator of sphingomyelin synthesis.

An operon containing the genes for cholesterol oxidase and a cytochrome P-450-like protein from a Streptomyces sp

The nucleotide sequence of the promoter region of the gene for cholesterol oxidase (choA) from Streptomyces sp. strain SA-COO was determined. We found an open reading frame (choP) that is located between a potential promoter sequence and the structural gene for the ChoA protein. Deletion analysis showed that the promoter region for choP is essential for expression of the choA gene. Mappings of S1 nuclease and primer extension of transcripts generated in vivo suggested that the synthesis of mRNA starts at a site 41 bases upstream from the ATG initiation codon of the choP gene. By Northern (RNA) blot analysis of the transcripts, we found a 2.9-kilobase transcript that is identical in size to the total sequence of the choP and choA genes. These results suggest that the two genes, choP and choA, are transcribed polycistronically under the control of the promoter that is upstream from the structural gene for choP. The choP gene encodes a protein of 381 amino acids with a calculated Mr of 41,668. The nucleotide sequence of the choP gene has a high degree of similarity to the sequence of the genes for cytochrome P-450s from humans and Pseudomonas species. A region of homology with the cytochrome P-450s from various organisms was identified in the choP protein and may represent a region associated with a binding site for heme iron. Analysis of the CO difference spectrum of an extract of Streptomyces lividans cells that carry a plasmid which includes the choP gene revealed a unique peak, characteristic of cytochrome P-450, which is identical to that obtained with the parent strain.