Evaluation of large airway specimens obtained by transbronchial lung cryobiopsy in diffuse parenchymal lung diseases

Background

The difference in diagnostic yield between surgical lung biopsy and transbronchial lung cryobiopsy (TBLC) in diffuse parenchymal lung diseases (DPLD) has been reported to be due to differences in the rate of interpathologist agreement, specimen size, and specimen adequacy. In TBLC, the specimens containing large airway components are generally believed as inadequate specimens for histological evaluation, but the detailed characteristics of TBLC specimens including the large airway and the impact on histological diagnostic rates of DPLD have not been investigated.

Methods

We retrospectively reviewed the specimen characteristics of patients with DPLD who underwent TBLC.

Results

Between February 2018 and January 2020, 74 patients and 177 specimens were included. There were 85 (48.0%) large airway specimens (LAS) that contained bronchial gland or bronchial cartilage. The ideal specimen ratio was significantly lower in the LAS-positive group than that in the LAS-negative group (5.8% vs. 45.6%), and the proportion of bronchioles, alveoli, and perilobular area were similarly lower in the LAS-positive group. The presence of traction bronchiectasis and diaphragm overlap sign on high-resolution computed tomography (HRCT) were also significantly higher in the LAS-positive group than those in the LAS-negative group. We observed a statistically significant trend in histological diagnostic yield (40.7% in LAS positive group; 60.8% in LAS positive and negative group; 91.6% in LAS negative group) (Cochran-Armitage trend test).

Conclusion

LAS is a specimen often collected in TBLC and contains a low percentage of bronchioles, alveoli, and perilobular area. Since the histological diagnostic yield tends to be higher in cases that do not contain LAS, it may be important to determine the biopsy site that reduces the frequency of LAS collection by referring to the HRCT findings in TBLC.

Prognostic differences between atrial functional mitral regurgitation and ventricular functional mitral regurgitation

Introduction

Atrial functional mitral regurgitation (A-FMR) has been under-recognized until recently as a cause of FMR, and the prognostic difference between A-FMR and ventricular FMR (V-FMR) has not been fully elucidated. As there has been different mechanisms of FMR suggested in A-FMR and V-FMR, we hypothesized that prognosis and prognostic predictors of A-FMR may differ from those of V-FMR.

Purpose

To investigate the prognosis and prognostic predictors of A-FMR in comparison with V-FMR.

Methods

Among 1312 consecutive patients with grade 3+ (moderate to severe) or 4+ (severe) MR, 378 consecutive FMR patients were identified by excluding patients with degenerative MR, previous cardiac surgery, or concomitant aortic valve disease and/or mitral stenosis. FMR with ejection fraction (EF) <40% or FMR due to regional wall motion abnormalities with leaflet tethering were classified as V-FMR (N=288), and FMR due to left atrial (LA) and/or annular dilatation with preserved or mid-range EF (≥40%) were classified as A-FMR (N=90). All-cause death and heart failure hospitalization were analyzed as cardiovascular (CV) events in this study. Surgical or percutaneous mitral valve intervention without CV events was handled as not reaching an endpoint and these cases were censored.

Results

A-FMR were significantly older (76 [69–82] vs. 70 [58–77] years), higher rates of female (64 vs. 35%) and atrial fibrillation (88 vs. 42%), and lower B-type natriuretic peptide (BNP) values (169 [101–318] vs. 447 [213–952] pg/ml) compared to V-FMR (all P<0.05). On echocardiography, LV end-diastolic and end-systolic dimensions (52 [48–57] vs. 64 [58–72] mm, 34 [31–37] vs. 55 [48–64] mm), respectively) were smaller, and EF (55 [50–60] vs. 28 [19–35] %) and LA volume (99 [73–137] vs. 73 [57–91] ml/m2) were larger in A-FMR (all P<0.05). Effective regurgitant orifice area (32 [26–40] vs. 31 [24–45] mm2) and regurgitant volume (50±15 vs. 52±16 ml) were similar (both n.s.). During a median follow up of 1407 days, 206 (54%) patients developed CV events. Kaplan-Meier analysis revealed that V-FMR had a significantly higher rates of CV events compared to A-FMR (Figure) with adjusted hazard ratio (HR) of 1.762 [1.168–2.660], P=0.007 after adjusted for variables including age, sex, New York Heart Association functional class, previous heart failure hospitalization, estimated glomerular filtration rate (eGFR) and BNP. Further, stepwise multivariate analysis showed that independent prognostic predictors of A-FMR were LA volume and eGFR, while those for V-FMR were LA volume, age, and LV end-systolic dimension.

Conclusions

A-FMR had relatively better prognosis compared to V-FMR, and there were different prognostic predictors between A-FMR and V-FMR. Our results suggest that different treatment strategies need to be considered between A-FMR and V-FMR.

The Kaplan-Meier life table

Funding Acknowledgement

Type of funding source: None

Recurrences of disease activity in patients with cardiac sarcoidosis under corticosteroid therapy: prevalence, clinical background and prognosis

Background

Corticosteroid therapy (CTx) has been widely accepted as first-line therapy for cardiac sarcoidosis (CS), but there are very limited data regarding recurrence of disease activity of CS. We retrospectively investigated the prevalence, patient characteristics and prognostic significance in patients with recurrences of CS.

Methods

We identified 102 consecutive patients who were clinically diagnosed CS (admission: 2012 and 2019) and whose disease activity was diminished clinically at least once. Recurrence of CS was defined as detection of increased uptake of 18F-fluoro-2-deoxyglucose or gallium-67 in the follow-up examination. Composite adverse events (events) were defined as all-cause of death or hospitalization for heart failure. Echocardiographic and laboratory data before initiation of CTx were obtained.

Results

During the follow-up term (median: 4.9 years), the recurrences of CS occurred in 28 patients at 30 months (median) after the initiation of CTx. In patients with recurrence, left ventricular (LV) ejection fraction before initiation of CTx was lower than in those without recurrences (median: 31% vs. 39%, p<0.05). After the detection of CS recurrences, 17 patients were treated with only increases of PSL and remaining 11 patients were treated with adding other immunosuppressive therapies to CTx. The univariate analysis demonstrated that there were no parameters in echocardiographic and laboratory examinations to predict the recurrences of CS. The results of univariate analysis for event occurrences (n=12) are shown in the Table. Additionally, the Kaplan-Meier analysis showed that there were no differences in event free survival rate in the patients with and without CS recurrences (Figure).

Conclusion

This study showed that the recurrences of disease activity were observed in a substantial number of patients with CS even under the CTx. All patients received intensification of CTx or additional immunosuppressive therapy, and LV systolic function, rather than the recurrence itself, was associated with clinical outcomes in this study.

Kaplan-Meier analysis for events

Funding Acknowledgement

Type of funding source: None

Autoimmune pulmonary alveolar proteinosis developed during immunosuppressive treatment in polymyositis with interstitial lung disease: a case report

Background

Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of surfactant proteins within the alveolar spaces. Autoimmune PAP (APAP) caused by elevated levels of GM-CSF autoantibodies (GM-Ab) is very rarely associated with systemic autoimmune disease. Here we report a case of APAP manifested during immunosuppressive treatment for polymyositis with interstitial lung disease.

Case presentation

A 52-year-old woman treated at our hospital because of polymyositis with interstitial pneumonia had maintained remission by immunosuppressive treatment for 15 years. She had progressive dyspnea subsequently over several months with her chest CT showing ground-glass opacities (GGO) in bilateral geographic distribution. Her bronchoalveolar lavage fluid with cloudy appearance revealed medium-sized foamy macrophages and PAS-positive amorphous eosinophilic materials by cytological examination. We diagnosed her as APAP due to an increased serum GM-CSF autoantibody level. Attenuating immunosuppression failed to lead GGO improvement, but whole lung lavage (WLL) was effective in her condition.

Conclusions

PAP should be considered as one of the differential diseases when the newly interstitial shadow was observed during immunosuppressive treatment. WLL should be regarded as the treatment option for APAP concurred in connective tissue disease (CTD).

Swelling of Doubly Magic ^{48}Ca Core in Ca Isotopes beyond N=28

Interaction cross sections for ^{42-51}Ca on a carbon target at 280  MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number N=28. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and mean field calculations point out that this anomalous enhancement of the nuclear size beyond N=28 results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare ^{48}Ca core in Ca isotopes beyond N=28.

P914 Changes of echocardiographic parameters in primary mitral regurgitation and determinants of symptom: an assessment from the Asian valve registry data

[Background]Clinicians often have a difficulty in determining the presence of mitral regurgitation (MR)-relatedsymptoms because of subjectivity.However, there are few actual measurement data for echocardiographic left ventricular (LV) and left atrial (LA) size related to the severity of MR and the relationship between MR-related symptoms and these echocardiographic parameters.

[Purpose] The purpose of this study was to clarify actual values for echocardiographic parameters related to severity of MR and determinant factors of MR-related symptoms.

[Methods] Among patients enrolled in the Asian Valve Registry, we investigated 778 consecutive patients with primary MR showing sinus rhythm. Symptoms were determined by NYHA (≤ II or ≥ III).

[Results]MR severity was mild in 106, moderate in 285, and severe in 387 patients. LA volume index, LV end-diastolic diameter, and LV mass index increased with increasing MR grade [LA volume index: 47.9 (mild), 56.2 (moderate), and 64.9 ml/m2(severe) (p < 0.001), LV end-diastolic diameter: 51.2, 54.5, 58.1 mm (p < 0.001), and LV mass index: 101, 109, 123 g/m2(p < 0.001)]. Regarding moderate and severe MR, 70 patients (10.4%) were symptomatic. Table shows multivariable analysis for being symptomatic in moderate and severe MR patients. LV mass index (p = 0.040), ejection fraction (p < 0.001), female gender (p = 0.004), and heart rate (p = 0.007) were independent factors for MR-related symptoms.

[Conclusions] LV and LA parameters on echocardiography worsened as MR severity progressed. Larger LV mass index and lower ejection fraction were independent determinant factors for MR-related symptoms. We should also pay attention to LV hypertrophy in patients with primary MR.

Determinant factors for mitral regurgita Model 1 Model 2 OR (95% CI) P-value OR (95% CI) P-value Age, per 1-y increment 1.03 (1.00-1.05) 0.035 1.02 (0.99-1.05) 0.053 Sex (female) 2.23 (1.20-4.16) 0.011 2.28 (1.31-3.98) 0.004 Hear rate, per 1 bpm increment 1.03 (1.00-1.05) 0.025 1.03 (1.01-1.05) 0.007 LVDs index, per 1 mm increment 0.99 (0.90-1.09) 0.90 EF, per 1% increment 0.95 (0.92-0.99) 0.019 0.96 (0.93-0.98) <0.001 LV mass index, per 10 g/m2increment 1.12 (1.01-1.25) 0.033 1.09 (1.005-1.18) 0.040 LA volume index, per 10 mL/m2increment 0.96 (0.90-1.03) 0.23 E wave, per 1cm/s increment 1.81 (0.70-4.66) 0.23 TR pressure gradient >40 mmHg 2.11 (0.97-4.57) 0.057 Hypertention 1.40 (0.75-2.63) 0.29

P1742 Occurrence of right ventricle dysfunction in patients with Brugada syndrome: a follow-up study by echocardiography and electrophysiological examination

Background

Brugada syndrome (BrS) has been characterized by no apparent structural abnormalities in both ventricles, but, recently, the presence of subtle right ventricular (RV) structural abnormalities in patients with BrS has been reported.

Purpose

The aim of this study was to evaluate the occurrence of RV dysfunction in patients with BrS and their characteristics.

Methods

We enrolled 49 consecutive patients (54 ± 11 years old) diagnosed with Brs and underwent echocardiography from 2017 to 2018. The echocardiographic parameters and electrophysiological examinations were evaluated including RV size and function such as RV outflow and inflow tract diameter, TAPSE, S’, and FAC. Abnormality threshold for parameters of RV dysfunction is defined as followed: a TAPSE of <17 mm, an S’ of <9.5 cm, and an FAC of <35%.

Results

Among 49 patients, one patient showed a TAPSE of <17 mm, 5 patients an S’ of <9.5 cm, and 10 patients an FAC of <35%. Evaluating characteristics of Brs patients with RV dysfunction, all patients were divided into 2 groups by the value of RV FAC; 39 patients showing FAC >35% (group A), 10 patients FAC ≤35% (group B). The comparison of each parameter between 2 groups is shown in Table. TAPSE and S’ in group B were lower than in group A. RV inflow tract diameter in group B was larger than in group A, although there was no differences in RV out tract diameter. There were no significant differences in left ventricular parameters, and grade of tricuspid regurgitation. QRS duration prolonged and the rate of ICD implantation was higher in group B than in group A. Moreover, all patients in group B showed RV wall motion abnormalities and the distribution was as followed: diffuse (n = 2), RV mid (n = 2), RV apex (n = 6).

Conclusions

BrS patients frequently showed RV dysfunction during follow-up, and it may be related to the prolongation of QRS duration. We should pay much attention to the occurrence of RV dysfunction in follow-up echocardiography.

Group A (FAC >35%) N = 39 Group B (FAC ≤35%) N = 10 p-value TAPSE, mm 22.9 ± 2.1 20.4 ± 2.6 0.009 S", cm/s 12.8 ± 2.0 11.1 ± 1.4 0.010 RV outflow tract, mm 29.7 ± 4.4 31.2 ± 5.0 0.49 RV mid inflow tract, mm 30.4 ± 2.9 33.8 ± 3.7 0.008 RV basal inflow tract, mm 38.5 ± 3.2 43.7 ± 4.0 0.001 QRS duration, ms 112.9 ± 12.9 136.3 ± 28.4 0.006 Late potential positive, n (%) 25 (64) 8 (80) 0.34 ICD implantation, n (%) 19 (68) 9 (90) 0.019

P1444 Occurrence and predictors of right ventricular dysfunction after pericardiocentesis

Background—The changes in cardiac function that occur after pericardiocentesis are unclear.Purpose—This study was performed to assess right ventricular (RV) and left ventricular (LV) function with echocardiography before and after pericardiocentesis.

Method and Results—In total, 19 consecutive patients who underwent pericardiocentesis for more than moderate pericardial effusion were prospectively enrolled from August 2015 to October 2017. Comprehensive transthoracic echocardiography was performed before, immediately after (within 3 hours), and 1 day after pericardiocentesis to investigate the changes in RV and LV function. RV dysfunction is defined as meeting three of the four criteria: a TAPSE of <17 mm, an S’ of <9.5 cm, an FAC of <35%, and an RV free wall longitudinal strain >−20%. The mean age of all patients was 72.6 ± 12.2 years. The changes of echocardiographic parameters related to RV function are shown in Table. After pericardiocentesis, RV inflow and outflow diameters increased and the parameters of RV function significantly decreased. These abnormal values or RV dysfunction remained at 1 day after pericardiocentesis. Conversely, no parameters of LV function parameters changed after pericardiocentesis. Of 19 patients, 13 patients showed RV dysfunction immediately after pericardiocentesis and 6 patients did not. RV free wall longitudinal strain before pericardiocentesis was higher in patients with post-procedural RV dysfunction (−18.9 ± 3.6%) than in those without (−28.4 ± 6.3%). ROC analysis revealed that a RV free wall longitudinal strain cut-off value of −23.0% had a sensitivity of 100% and a specificity of 83.3% for predicting the occurrence of RV dysfunction after pericardiocentesis (AUC = 0.910).

Conclusions—The occurrence of RV dysfunction after pericardiocentesis should be given more attention. Pre-existing RV dysfunction maybe related to the occurrence of RV dysfunction after pericardiocentesis.

Changes in RV function before and after Before Immediately after One day after P−value Basal right ventricular linear dimension (mm) 32.8 ± 5.0 37.1 ± 4.4† 33.6 ± 5.4 0.028 Mid-cavity right ventricular linear dimension (mm) 34.5 ± 4.6 38.8 ± 5.3† 37.0 ± 5.6 0.0504 Proximal right ventricular outflow diameter (mm) 30.2 ± 4.0 33.9 ± 3.5† 31.4 ± 3.9 0.014 TAPSE (mm) 20.0 ± 4.2 13.6 ± 4.3* 14.7 ± 3.9 <0.001 S" (cm/s) 12.6 ± 3.3 8.7 ± 2.4* 9.1 ± 2.4 <0.001 Fractional area change (%) 48.3 ± 5.9 37.8 ± 8.0* 40.0 ± 9.0 <0.001 Right ventricular free wall strain (%) −21.3 ± 6.3 −15.8 ± 6.7* −16.9 ± 5.2 0.036 Tricuspid regurgitation velocity peak (m/s) 2.41 ± 0.29 2.43 ± 0.25 2.34 ± 0.32 0.37

P5551Comparison of prognostic predictors of heart failure admission and progression to end-stage in hypertrophic cardiomyopathy

Background

Heart failure (HF) is a common complication within the clinical spectrum of hypertrophic cardiomyopathy (HCM). HCM-related HF is recognized to be multifactorial, including outflow obstruction, diastolic dysfunction, or progression to end-stage; however, prognostic predictors of HF events are not fully understood. We sought to investigate predictors for various HF outcomes in HCM.

Methods

We studied 289 consecutive HCM patients with EF≥50%. Patients with outflow obstruction (peak pressure gradient ≥30mmHg) were defined as obstructive HCM. HF events assessed in this study were 1) HF admission and 2) progression to end-stage (EF<50%).

Results

The mean age was 63±16 years, 53% male, EF 61±5%, NYHA class 1.8±0.7, and 39% obstructive. During a median follow up of 5.2 [3.7–7.0] years, 48 HF admission and 19 progression to end-stage were observed. Only 8/48 (17%) patients with HF admission had progressed to end-stage; while 11/19 (58%) patients with progression to end-stage remained free from HF admission. Univariate Cox regression hazard analysis showed different prognostic predictors between HF admission and progression to end-stage (Table). Multivariate Cox regression hazard analysis showed atrial fibrillation was an independent predictor of HF admission (adjusted HR 2.711 [1.094–7.389], P=0.031); while LV end-systolic dimension was an independent predictor of progression to end-stage (adjusted HR 1.114 [1.018–1.229], P=0.025).

Cox hazard analysis for predicting event HF admission Progression to end-stage HR (95% CI) P value HR (95% CI) P value Age, 1 year 1.042 (1.017–1.071) <0.001 1.002 (0.975–1.035) 0.89 Male sex 1.052 (0.595–1.882) 0.86 2.853 (1.034–10.02) 0.043 Atrial fibrillation 3.247 (1.809–6.608) <0.001 1.434 (0.570–3.559) 0.44 Non-obstructive 0.850 (0.481–1.531) 0.58 5.439 (1.558–34.30) 0.005 LV end-diastolic dimension, 1mm 1.027 (0.981–1.077) 0.25 1.120 (1.035–1.218) 0.005 LV end-systolic dimension, 1mm 1.059 (1.008–1.110) 0.023 1.167 (1.080–1.258) <0.001 EF, 1% 0.974 (0.926–1.032) 0.36 0.894 (0.825–0.980) 0.018 LA volume, 1ml/m2 1.012 (1.001–1.020) 0.044 1.006 (0.978–1.023) 0.64 Transmitral E wave, 1m/s 1.013 (1.002–1.024) 0.025 1.006 (0.987–1.023) 0.50 Transmitral DcT, 1msec 0.999 (0.995–1.003) 0.59 0.985 (0.974–0.994) <0.001 E/e', 1.0 1.062 (1.012–1.109) 0.015 1.089 (1.010–1.164) 0.027

Conclusions

Different prognostic predictors were found for HF admission and progression to end-stage, suggesting the difficulty and multifactorial nature of HCM-related HF.

P915Clinical characteristics, natural history and predictors of disease progression in patients with degenerative mitral stenosis

Background

Mitral annular calcification (MAC) is a common echocardiographic finding and an increasingly recognized cause of degenerative mitral stenosis (DMS). However, little is known about the natural history and predictors of disease progression of DMS, especially compared with rheumatic mitral stenosis (RMS).

Purpose

To compare the clinical characteristics and disease progression among patients with DMS and those with RMS, and to investigate the determinants of disease progression in DMS patients.

Methods

We retrospectively reviewed consecutive MS patients with a trans-mitral mean gradient ≥2 mmHg who underwent echocardiography at our institution between January 2014 and December 2017. We selected patients who had an initial and follow-up echocardiography with a ≥3-month interval and without prior and interim mitral valve intervention. DMS was defined as MS with MAC with normal or minimally reduced leaflet motion without tips restriction. RMS was defined as MS with tip restriction, thickening and restriction of leaflet mainly. We defined MAC severity as mild (focal), moderate (marked density >1/3 but <1/2 of the mitral annulus) and severe (marked density involving >1/2 of the mitral annulus) based on previous reports. We calculated disease progression from the annual increase rate of trans-mitral mean gradient. First, we compared the backgrounds and disease progression between DMS group and RMS group. Second, we investigated the predictors of disease progression in DMS group.

Results

We enrolled 111 patients (64 in DMS group and 47 in RMS group) with a mean follow-up period of 2.1 years. Patients in DMS group were significantly older (79±9 vs. 70±10 years; P<0.01), had higher prevalence of hypertension (P<0.01) and coronary artery disease (P=0.02), and had higher plasma BNP level (P<0.01) than those in RMS group. Baseline trans-mitral mean gradient was slightly lower in DMS group than in RMS group (3.9±1.9 vs. 4.7±1.8 mmHg; P=0.02). There were wide variations among individuals in progression rate (range: 0 to 3.5 mmHg/year in DMS group and 0 to 5.8 mmHg/year in RMS group, respectively), and the progression rate was comparable between DMS group and RMS group (0.49±0.79 vs. 0.61±1.37 mmHg/year; P=0.59). In DMS group, higher prevalence of dyslipidemia (P=0.01) and lower baseline trans-mitral mean gradient (P<0.01) were significantly associated with disease progression even after adjustment for age and sex. Unexpectedly, there was no significant difference in the disease progression regardless of the MAC severity among DMS group (Picture).

MAC severity and disease progression

Conclusions

Progression in DMS group is highly variable, but generally slow as that in RMS group. Initial mean gradient was inversely associated with disease progression in DMS group. Furthermore, baseline MAC severity did not correlate with the progression, suggesting the importance of follow-up echocardiography in spite of the MAC severity and initial mean gradient.

P767Survey of palliative sedation at the end-of-life in terminally ill heart failure patients - a five year experience in national cardiovascular center

Background

Palliative sedation is a therapeutic option when symptom relief is difficult to achieve at the end-of-life. However, little is known regarding palliative sedation in terminally ill heart failure (HF) patients.

Purpose

To survey the practice of palliative sedation in terminally ill HF patients at a tertiary referral cardiovascular center, and to investigate the efficacy and safety of sedative agents in HF patients.

Methods

We retrospectively reviewed consecutive patients who were referred to palliative care team at our institution between September 2013 and August 2018. Patients who were hospitalized for HF and died during hospitalization despite optimal medical therapy were selected and defined as terminally ill HF. We investigated the practice of palliative sedation in terminally ill HF patients and analysed the vital signs and sedation scale before starting sedative agents and about 1 hour afterward.

Results

Among 95 terminally ill HF patients, 37 were prescribed palliative sedation at the end-of-life (Picture). Of 37 patients (mean age: 70 years, median B-type natriuretic peptide: 1018 pg/ml, median creatinine: 3.0 mg/dl, intravenous inotrope: 81%), 25 were prescribed dexmedetomidine, and 12 were prescribed midazolam as first agent for sedation. Patient's backgrounds were comparable between the two groups. Richmond Agitation-Sedation Scale was significantly reduced (P<0.01), whereas blood pressure and heart rate were not altered after treatments in both groups. In midazolam group, significant decreases were noted regarding respiratory rate (P=0.01) and oxygen saturation (P=0.02); however, these parameters were not changed in dexmedetomidine group (Table).

Table 1. Vital signs and sedation scale Dexmedetomidine group (n=25) Midazolam group (n=12) Baseline After P value Baseline After P value Richmond Agitation-Sedation Scale 1 (0, 1) −1 (−2, 0) <0.01 1 (0, 1) −2 (−3, −1) <0.01 Vital signs   Systolic blood pressure (mmHg) 90±15 89±16 0.51 89±21 84±23 0.33   Diastolic blood pressure (mmHg) 52±13 54±11 0.34 60±14 56±23 0.48   Heart rate (beats per minute) 95±20 91±22 0.17 90±21 90±19 0.70   Respiratory rate (breaths per minute) 22±5 20±5 0.24 21±5 17±2 0.01   Oxygen saturation (%) 97±3 96±6 0.59 96±5 94±5 0.02

Picture. Study flowchart

Conclusions

Dexmedetomidine and midazolam were commonly used in real-word practice for HF patients at the end-of-life. Although impact on respiratory system differed by treatments, both agents could be prescribed effectively and safely in terminally ill HF patients.

Platelet-dependent serum factor that stimulates the proliferation of epidermal cells in vitro

Agglutinated platelets are known to release a factor that stimulates the growth of arterial smooth muscle cells or dermal fibroblasts. The present study was designed to see the effect of this platelet factor on epidermal cells. The growth of cultured epidermal cells and dermal fibroblasts obtained from guinea pig ear skin was observed using 10% platelet-rich serum or platelet-poor serum in the culture medium. These sera were prepared from fresh human blood according to the method described by Ross. The cell growth was checked by counting the number of cells in culture or by the uptake of labeled thymidine by the cells. The platelet-rich serum significantly stimulated the growth of epidermal cells as well as fibroblasts as compared with the platelet-poor serum. This implies that platelet factor released after injury to cutaneous vessels in trauma or inflammation plays an important role in initiating proliferation of epidermal cells and dermal fibroblasts.

Evaluation of Selected Cucurbitaceous Vegetables for Resistance to Zucchini yellow mosaic virus

Zucchini yellow mosaic virus (ZYMV) causes considerable losses of cucurbitaceous vegetables grown nearly all over the world; indeed, the commonly planted cultivars are highly susceptible to ZYMV. In all, 3 cultivars of American and 8 of European summer squash (Cucurbita pepo), and 6 Japanese and 21 European cucumber lines (Cucumis sativus), including both slicing and pickling species, were selected for the evaluation of their resistance to the most virulent Czech strain, ZYMV-H (GenBank accession number DQ144054). Butternut squash (Cucurbita moschata) 'Menina 15', Chinese slicing cucumber 'Taichung Mou Gua-1' (TMG-1), and watermelon (Citrullus lanatus) accession PI 595203 were included in the experiment, because they were reported to be resistant to ZYMV. The tested plants were mechanically inoculated by ZYMV-H and their resistance was assessed through a comparison of the relative virus protein concentrations and visual symptoms. Butternut squash Menina 15, Chinese slicing cucumber TMG-1, Japanese slicing cucumber breeds 'G22' and 'A192-18', and watermelon PI 595203 were evaluated as immune: the virus concentration in their leaves was zero, as verified by polymerase chain reaction. American summer squash 'Cougar' and Japanese slicing cucumber breeds 'A202-18', 'R10', and 'S93-18' were clearly resistant, because the virus multiplied at a low rate in these plants. The remaining tested cultivars were tolerant or susceptible to ZYMV.

Effects of rain on energy metabolism while running in a cold environment

Environmental factors tend to influence the performance of individuals who exercise for extended periods. The present study aimed to determine energy metabolism while running in cold, wet conditions using a climatic chamber that can precisely simulate rainy conditions. 7 healthy men (age, 23.3±2.9 (SD) y; height, 168.6±7.5 cm; weight, 65.9±8.1 kg; V. O2max, 52.0±5.7 mL·kg - 1·min - 1) ran on a treadmill at 70% ˙VO2max intensity for 30 min in a climatic chamber at an ambient temperature of 5°C in the presence (RAIN) or absence (CON) of 40 mm/h of precipitation. Expired air, esophageal temperature, heart rate, mean skin temperature, rating of perceived exertion and blood samples were measured. Esophageal temperature and mean skin temperature were significantly lower (P<0.05) in RAIN than in CON all. Minute ventilation, oxygen consumption and levels of plasma lactate and norepinephrine were significantly higher (P<0.05) in RAIN than in CON. In conclusion, the higher oxygen consumption and plasma lactate in RAIN indicated that energy demand increases when running in cold conditions.

Exercise training attenuates lipectomy-induced impaired glucose tolerance in rats

OBJECTIVE

Since visceral adipose tissue (VAT) may account for impaired peripheral and hepatic insulin sensitivity (IS), it has been hypothesized that the partial removal of VAT could result in improved insulin action, while the re-growth of the excised tissue and/or compensatory growth of non-excised depots seems to occur. Thus, it was aimed to investigate whether or not VAT removal and exercise affect IS.

METHODS

Male Wistar rats were fed a high-fat diet and subsequently assigned randomly to one of four groups: 1. exercised plus lipectomized (EL), 2. exercised plus sham-lipectomized (ES), 3. sedentary plus lipectomized (CL), 4. sedentary plus sham-lipectomized (CS). After lipectomy, EL and ES animals underwent a 7-consecutive-day training period. Body weight, food intake, basal metabolic rate, fasting glucose, and glucose tolerance were assessed before and after the interventions. Fasting insulin and the HOMA index, body fat mass, and the expression of pro-inflammatory genes were assessed after the interventions.

RESULTS

EL group showed greater insulin sensitivity compared to all other groups. EL and ES groups showed lower fasting insulin levels when compared to CL and CS groups, respectively. The EL group showed improved IS when compared to the remaining groups. The CL group showed impaired glucose tolerance and increased TNF-alpha gene expression. Body weight and fat mass did not differ among the groups. PPAR gamma gene expression was increased in the EL and ES groups.

CONCLUSIONS

These results showed that short-term swimming training improved insulin sensitivity, but failed to prevent fat regain in lipectomized animals. Lipectomy induced impaired glucose tolerance, which is probably related to increased TNF-alpha gene expression. It is possible that a high-fat diet might be implicated in faster regain of adipose tissue after lipectomy. Our results also show that short-term exercise associated with lipectomy could improve insulin sensitivity.

Association study of vascular endothelial growth factor gene polymorphisms in endometrial carcinomas in a Japanese population

OBJECTIVE

Vascular endothelial growth factor (VEGF) is one of the most potent endothelial cell mitogens and plays a critical role in angiogenesis of endometrial carcinomas. Several studies have demonstrated positive associations between VEGF gene polymorphisms and several carcinomas. In this study we investigated whether VEGF gene polymorphisms are associated with endometrial carcinomas in a Japanese population.

METHODS

The allele frequencies and genotype distributions of VEGF -460 C/T, +405 G/C, and +936 C/T polymorphisms were examined in 105 endometrial carcinomas and 179 controls using PCR-RFLP analysis. An association of these polymorphisms with three-year disease-free survival was evaluated using the Kaplan-Meier method.

RESULTS

No significant differences in the allele frequencies and genotype distributions of VEGF -460 C/T (p = 0.54, 0.90), +405 G/C (p = 0.31, 0.17), and +936 C/T polymorphisms (p = 0.46, 0.24) were observed between endometrial carcinoma patients and controls. There were no significant differences in the frequencies of haplotype -460 T/+405 C between patients and controls. Futhermore, VEGF -460 C/T, +405 G/C, and +936 C/T polymorphisms were not associated with three-year disease-free survival of endometrial carcinoma patients.

CONCLUSIONS

Although limited by sample size, our study did not demonstrated any evidence that VEGF -460 C/T, +405 G/C, and +936 C/T polymorphisms are associated with an increased risk of endometrial carcinomas in Japanese women.

Three-dimensional analysis of pulp chambers in maxillary second deciduous molars

OBJECTIVE

The purpose of this study was to clarify the positional relationship between the crown contour and the pulp chamber using micro-CT system for restorations of maxillary second deciduous molar.

METHODS

Five maxillary second deciduous molar teeth each from the deciduous dentition and the mixed dentition periods were used. The positional relationship between the crown contour and pulp chamber was three-dimensionally observed by micro-CT. In addition, the thickness of the dentin at each of the pulp horns and the volume ratio of the pulp chamber against the whole crown were measured.

RESULTS

In relationship to the crown contour and the pulp chamber, the pulp horn of the mesiobuccal cusp showed greatest protrusion and eminent swelling of its mesial wall in both the deciduous dentition and the mixed dentition periods. Furthermore, the pulp chamber was shifted to the mesial side. The volume ratio of the pulp chamber to the whole crown, the ratio in the mixed dentition period showed to be significantly smaller than in the deciduous dentition period. The dentin thickness at the mesiobuccal pulp horn was the thinest.

CONCLUSIONS

These results suggest that in preparation of cavities in maxillary second deciduous molars, care is necessary not to expose of the mesiobuccal pulp horn. Especially, the mesial wall of the mesiobuccal pulp horn should be noted.

An Advanced Engine Control System Using Combustion Pressure Sensors

While investigating high-efficiency responsive driveability accompanied by low exhaust emissions, a new concept in engine control has been developed. The method is based on the direct monitoring and controlling of combustion conditions in engines, using a newly developed combustion pressure sensor. Fibre-optic technology is adapted to this sensor to produce a high noise immunity and a simple structure that facilitates applications in automotive engines. A sensing method to obtain information on engine output, knocking or detonation and the combustion temperature from the signal of the combustion pressure sensor has been proposed. A control system for the engine and powertrain control using this sensing method has been put forth to provide a remarkable improvement in engine and powertrain characteristics.

Expression of prolactin-releasing peptide and prolactin in the euryhaline mudskippers (Periophthalmus modestus): prolactin-releasing peptide as a primary regulator of prolactin

Prolactin (PRL)-releasing peptide (PrRP) is a strong candidate stimulator of pituitary PRL transcription and secretion in teleosts. However, the role in control of extrapituitary PRL expression is unclear even in mammals. To study the possible presence of PrRP-PRL axes not only in the brain-pituitary but also in peripheral organs, the expression patterns of PrRP, PRL and growth hormone (GH) were characterized in amphibious euryhaline mudskippers (Periophthalmus modestus). PrRP mRNA is abundantly expressed not only in the brain but also in the liver, gut and ovary, while less abundant expression was also detected in the skin and kidney. Corresponding to the distribution of PrRP mRNA, PRL mRNA was also detectable in these organs. During adaptation to different environments, the changes in mRNA levels of PrRP paralleled those in PRL in the brain-pituitary, liver and gut in an organ-specific manner. Brain PrRP mRNA and the pituitary PRL mRNA increased under freshwater and terrestrial conditions (P < 0.05); expression of PrRP and PRL in the gut of freshwater fish was higher (P < 0.05) than those in sea-water fish although there were no changes in fish kept out of water; no significant change was seen in the liver. Expressions of GH were not correlated with PrRP. In the gut, PrRP and PRL appear to be co-localized in the mucosal layer, especially in the mucous cells. Thus, PrRP may also be a local modulator of extrapituitary PRL expression and the PrRP-PRL axes in various organs may play an organ-specific role during environmental adaptation.

Todarepsin, a new cathepsin D from hepatopancreas of Japanese common squid (Todarodes pacificus)

An intracellular aspartic proteinase obtained from the hepatopancreas (liver) of Japanese common squid (Todarodes pacificus) was purified to homogeneity. The molecular mass of the enzyme was 36,500 Da on SDS-PAGE, and the isoelectric point was 8.29 by isoelectric focusing. The enzyme activity was optimal at pH 3.5, pH 2.2 and pH 3.0 for the substrates acid-denatured hemoglobin, acid-denatured casein, and MOCAc-GKPILFFRLK(Dnp)-D-R-NH2, respectively. Enzyme activity decreased rapidly at 50 degrees C. The Km and kcat values of the enzyme were estimated to be 3.2 mM and 46 s(-1) with MOCAc-GKPILFFRLK(Dnp)-D-R-NH2, and 1.7 mM and 1.1 s(-1) with MOCAc-SEVNLDAEFRK(Dnp)RR-NH2. The enzyme activity was strongly inhibited by pepstatin A, but only partially inhibited by DAN and EPNP. The Ki values for pepstatin A, DAN and EPNP were 0.5 nM, 0.5 mM and 0.2 mM, respectively. A cDNA encoding the enzyme was cloned by RT-PCR and subjected to nucleotide sequencing. The entire open reading frame was 1179 bp and coded for a protein of 392 amino acid residues. The mature enzyme consisted of 334 amino acids. The deduced amino acid sequence of the enzyme showed a high degree of identity to the sequences of cathepsins D found in various species.

NMR solution structure of the L 9.1a region of Tetrahymena group I intron

The solution structure of 20 mer RNA contained of the loop 9.1a region of Tetrahymena group I intron was studied by NMR. This RNA oligomer has hairpin and duplex structures at high concentration (1 mM) of the sample even at low NaCl concentration (5 mM). In the hairpin structure, GC base pairs by the loop-loop interaction are formed. As study of NOESY measurements, and by the compared with the sequence, this loop region is presumed to interact with the loop 5c.

NMR solution structure of the 2.1 loop of Tetrahymena group I intron

The solution structure of 17 mer RNA contained of the 2.1 loop region of Tetrahymena group I intron was studied by NMR. This RNA oligomer forms a hairpin structure at low NaCl concentration (5 mM). In the hairpin structure, the bases from C1 to A8 are sequentially stacked, and one GC base pair is formed in the loop. By the addition of RNA oligomer GCAA compensatory to UUGC in the loop, the imino proton signals of one AU and one GC base pairs are observed. Therefore, tetramer GCAA interacts with the loop of the hairpin structure. The 2.1 loop region is presumed to interact with the 9.1a loop.

Accumulation of heavy metals in Caspian seals (Phoca caspica)

Concentrations of heavy metals (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Co, and Hg) were determined in the muscle, liver, and kidney of 42 Caspian seals and fishes collected from the Caspian Sea in 1993. Higher Mn and lower Fe and Cu concentrations were found in the liver in comparison with other marine pinnipeds. Lower Cu concentrations in the liver appear to be a common feature in small seals belonging to subgenus Pusa, which include ringed, Baikal, and Caspian seals. However, low Fe and high Mn in livers were specific to Caspian seal. Concentrations of toxic metals such as Hg and Cd were relatively low. Pinniped species can be divided into two groups, based on accumulations of Cd or Hg in the liver. Interestingly, it was found that Cd-accumulating groups feed on invertebrates, whereas the preferred diet of Hg accumulators is fish. Caspian seals seemed to belong to the Hg-accumulating group.Cd and Hg concentrations in the liver and kidney of young animals increased with age. Mercury concentrations in adult animals increased with age continuously, whereas Cd concentrations in adult animals decreased. This trend might be due to preferential feeding habits and shift in ratio of Hg and Cd in the diet ( i.e., invertebrates to fish).

Eccrine poromas in a patient with mycosis fungoides treated with electron beam therapy

We describe a 72-year-old man with mycosis fungoides (MF) followed up at our hospital for more than 20 years, who has developed 14 eccrine poromas (EPs) in the past 12 years. Twelve of these tumours were ascertained as EP histopathologically without any findings of malignancy and the other two were clinically diagnosed and are not yet resected. To our knowledge, this is the first case report of MF complicated with multiple EPs. In our patient, all EPs arose in skin areas previously irradiated with an electron beam for the treatment of MF, suggesting that electron beam irradiation might have an effect on the development of EPs.

CRMP-2 induces axons in cultured hippocampal neurons

In cultured hippocampal neurons, one axon and several dendrites differentiate from a common immature process. Here we found that CRMP-2/TOAD-64/Ulip2/DRP-2 (refs. 2-4) level was higher in growing axons of cultured hippocampal neurons, that overexpression of CRMP-2 in the cells led to the formation of supernumerary axons and that expression of truncated CRMP-2 mutants suppressed the formation of primary axon in a dominant-negative manner. Thus, CRMP-2 seems to be critical in axon induction in hippocampal neurons, thereby establishing and maintaining neuronal polarity.

Exercise training and autonomic nervous system activity in obese individuals

PURPOSE

This study was designed to investigate the effects of 12 wk of exercise training on autonomic nervous system (ANS) in 18 obese middle-aged men (N = 9) and women (N = 9) (age: 41.6 +/- 1.2 yr; BMI: 27.3 +/- 0.4 kg x m(-2); %fat: 29.6 +/- 1.3%, mean +/- SE).

METHODS

Each subject participated in an aerobic exercise training at anaerobic threshold (AT), consisting of 30 min/session, 3 times/wk, for 12 consecutive weeks. The ANS activities were assessed by means of power spectral analysis of heart rate variability (HRV) at resting condition before, at 5 wk, and after the exercise program.

RESULTS

The exercise training resulted in a significant decrease in body mass, BMI, and % fat (P < 0.01) but not in lean body mass (P > 0.05) together with a significant increase in the AT VO2 (P < 0.01). Our power spectral data indicated that there were significant increases in the low-frequency component associated with the sympathovagal activity (0.03--0.15 Hz, 348.5 +/- 66.8 vs 694.7 +/- 91.5 ms(2), P < 0.01), the high-frequency vagal component (0.15--0.4 Hz, 146.3 +/- 30.4 vs 347.7 +/- 96.5 ms(2), P < 0.05), and the overall autonomic activity as evaluated by total power (0.03--0.4 Hz, 494.8 +/- 88.5 vs 1042.4 +/- 180.9 ms(2), P < 0.01) of HRV after the training.

CONCLUSIONS

Twelve weeks of exercise training has significantly improved both the sympathetic and parasympathetic nervous activities of the obese individuals with markedly reduced ANS activity, suggesting a possible reversal effect of human ANS functions. These favorable changes may also have an influence on the thermoregulatory control over the obesity.

Effects of photoperiod on pituitary gonadotropin levels in masu salmon

We examined the effects of photoperiod on pituitary levels of two types of gonadotropin (GTH), GTH I and GTH II, in masu salmon Oncorhynchus masou to study their mechanism of synthesis. In Experiment 1, the effects of long or short photoperiod combined with castration were examined using 8-month-old precocious males. Castration was carried out in early August and then the fish were reared under a short (8L16D) or long (16L8D) photoperiod for 60 days. In Experiment 2, the effects of photoperiod combined with testosterone treatment were examined using 12-month-old immature females. Silastic tubes containing testosterone (500 microg /fish) or vehicle were implanted intra-peritoneally in early October. Fish were reared under 16L8D for 60 days, and then half of the fish were transferred to 8L16D, while the remaining fish were kept under 16L8D until Day 90. In Experiment 1, GTH I contents were higher under 16L8D than under 8L16D in the castrated group on Day 30. Moreover, GTH I contents were higher in the castrated group than the control group under 16L8D on Day 30. GTH II contents increased with testicular maturation in the control groups, whereas they remained at low levels in the castrated groups regardless of photoperiodic treatment. In Experiment 2, GTH I contents did not change remarkably in all the groups, while GTH II contents were remarkably increased by testosterone treatment regardless of photoperiodic treatment. These results indicate that the synthesis of GTH I and GTH II are differently regulated by photoperiod and testosterone in masu salmon.

Stress fiber organization regulated by MLCK and Rho-kinase in cultured human fibroblasts

To understand the roles of Rho-kinase and myosin light chain kinase (MLCK) for the contraction and organization of stress fibers, we treated cultured human foreskin fibroblasts with several MLCK, Rho-kinase, or calmodulin inhibitors and analyzed F-actin organization in the cells. Some cells were transfected with green fluorescent protein (GFP)-labeled actin, and the effects of inhibitors were also studied in these living cells. The Rho-kinase inhibitors Y-27632 and HA1077 caused disassembly of stress fibers and focal adhesions in the central portion of the cell within 1 h. However, stress fibers located in the periphery of the cell were not severely affected by the Rho-kinase inhibitors. When these cells were washed with fresh medium, the central stress fibers and focal adhesions gradually reformed, and within 3 h the cells were completely recovered. ML-7 and KT5926 are specific MLCK inhibitors and caused disruption and/or shortening of peripheral stress fibers, leaving the central fibers relatively intact even though their number was reduced. The calmodulin inhibitors W-5 and W-7 gave essentially the same results as the MLCK inhibitors. The MLCK and calmodulin inhibitors, but not the Rho-kinase inhibitors, caused cells to lose the spread morphology, indicating that the peripheral fibers play a major role in keeping the flattened state of the cell. When stress fiber models were reactivated, the peripheral fibers contracted before the central fibers. Thus our study shows that there are at least two different stress fiber systems in the cell. The central stress fiber system is dependent more on the activity of Rho-kinase than on that of MLCK, while the peripheral stress fiber system depends on MLCK.

The involvement of sex steroid hormones in downstream and upstream migratory behavior of masu salmon

From May through July when masu salmon, Oncorhynchus masou, commence downstream migration under natural conditions, yearling precocious male masu salmon (resident form) showed higher GSI and plasma levels of testosterone (T) and 11-ketotestosterone (11-KT) in contrast to immature smolts (migratory form). From March through September coinciding with the upstream migration period, 2-year-old male and female adults also showed higher GSI and plasma levels of T, estradiol-17beta (E(2)) 11-KT, 17alpha-hydroxyprogesterone and 17alpha,20beta-dihydroxy-4-pregnene-3-one (DHP). In order to test the effects of steroid hormones on migratory behaviors, silascone tube capsules containing 500 microg of T, E(2), 11-KT, DHP, or a vehicle was implanted into smolts, castrated precocious males, or immature parr, and downstream and upstream behavior were observed in artificial raceways in spring and autumn. Downstream behavior of smolts was inhibited significantly by T, E(2) and 11-KT. Upstream behavior was stimulated by T and 11-KT in castrated precocious males and stimulated by T, E(2) and 11-KT in immature parr. These results indicate that T, E(2) and 11-KT are the factors regulating downstream and upstream migratory behavior. In particular, because of its changing patterns in plasma and significant effects, T, the common precursor hormone of E(2) (female) and 11-KT (male), is considered to play central roles in both types of behavior.

The effects of testosterone on upstream migratory behavior in masu salmon, Oncorhynchus masou

Effects of testosterone (T) on upstream migratory behavior in masu salmon, Oncorhynchus masou, were studied by use of artificial raceways. In Experiment 1, yearling precocious males castrated in August were implanted with a capsule of medical silicone tube containing 500 microg of T in September. Their upstream migration was recorded in an artificial raceway with castrated and sham-operated precocious males implanted with a capsule containing vehicle for 2 months. In Experiment 2, upstream migratory behavior of yearling immature parr implanted with a capsule containing T 500 microg or vehicle was observed from September through November. In Experiment 3, upstream migratory behavior of castrated, castrated + T 50 microg, castrated + T 500 microg, and sham-operated precocious males was observed from September through October. In Experiment 4, upstream migratory behavior of the control, T 50 microg-, T 500 microg-, and T 1000 microg-treated immature parr was observed from September through October. In each experiment, plasma and pituitary samples were taken from the fish that moved upstream and remained to measure levels of T, gonadotropin (GTH) II, thyroxine (T(4)), and triiodothyronine (T(3)) by radioimmunoassay. Administration of T caused increases in plasma T levels within the physiological range. In Experiment 1, the frequency of migration upstream was 0, 19.2, and 35.7% in the castrated, castrated + T 500 microg, and sham-operated groups, respectively. The frequency was higher in the castrated + T 500 microg and sham-operated groups than in the castrated group. In Experiment 2, the frequency was higher in T 500 microg-treated parr (22%) than in the control (2.6%). In Experiments 1 and 2, pituitary contents of GTH II in the T-treated groups and precocious males were higher than those in the castrated precocious males and immature parr. In Experiment 3, castrated + T 50 microg, castrated + T 500 microg, and sham-operated fish showed upstream migratory behavior, whereas castrated fish without T did not. In Experiment 4, the frequency was 5.7, 22.9, 17.1, and 28.6% in the control, T 50 microg-, T 500 microg-, and T 1000 microg-treated groups, respectively. In each experiment, plasma levels of T(4) in migrants were lower than those in nonmigrants, whereas plasma levels of T(3) did not show such changes. From these results, it is inferred that T is a factor influencing upstream migration in masu salmon.

Rho-kinase--mediated contraction of isolated stress fibers

It is widely accepted that actin filaments and the conventional double-headed myosin interact to generate force for many types of nonmuscle cell motility, and that this interaction occurs when the myosin regulatory light chain (MLC) is phosphorylated by MLC kinase (MLCK) together with calmodulin and Ca(2+). However, recent studies indicate that Rho-kinase is also involved in regulating the smooth muscle and nonmuscle cell contractility. We have recently isolated reactivatable stress fibers from cultured cells and established them as a model system for actomyosin-based contraction in nonmuscle cells. Here, using isolated stress fibers, we show that Rho-kinase mediates MLC phosphorylation and their contraction in the absence of Ca(2+). More rapid and extensive stress fiber contraction was induced by MLCK than was by Rho-kinase. When the activity of Rho-kinase but not MLCK was inhibited, cells not only lost their stress fibers and focal adhesions but also appeared to lose cytoplasmic tension. Our study suggests that actomyosin-based nonmuscle contractility is regulated by two kinase systems: the Ca(2+)-dependent MLCK and the Rho-kinase systems. We propose that Ca(2+) is used to generate rapid contraction, whereas Rho-kinase plays a major role in maintaining sustained contraction in cells.