Change in minimum indexed left atrial volume predicts incident heart failure: the multi-ethnic study of atherosclerosis

Funding Acknowledgements

Type of funding sources: None.

Background and Purpose

Longitudinal change in the left atrium prior to the onset of heart failure has not been as well studied as left atrial (LA) dysfunction in pre-existing heart failure. This study used cardiac magnetic resonance (CMR) imaging to investigate the relationship between longitudinal change in LA volume and function and incident heart failure (HF), in a multi-ethnic population free of known cardiovascular disease at baseline.

Methods and Results

In the Multi-Ethnic Study of Atherosclerosis (MESA), 2470 participants (60±9 years, 47% males), free at baseline of clinically recognized cardiovascular disease, had LA volume, emptying fractions and peak longitudinal strain assessed with Multimodality Tissue Tracking (MTT; version 6.0 Toshiba, Japan) on CMR imaging at baseline (2000-02) and at follow-up 9.4±0.6 years later. Seventy three (3%) participants subsequently developed incident HF 7.1±2.1 years after the follow-up CMR exam. In cox regression models, an annualized change in all LA parameters were significantly associated with an increased risk of incident HF. An annual increase of 1ml/m2 in minimum indexed LA volumes (∆LAVimin) was most strongly associated with the risk of incident HF (Hazard Ratio(HR)=1.85, 95% confidence interval(CI) [1.49-2.29], P<0.001) and improved model reclassification and discrimination in predicting incident HF (c-statistic=0.80, 95%CI [0.75-0.86]; NRI=0.13, P=0.04; IDI=0.04, P=0.01; x2=6.52, P=0.69) adjusting for known risk factors (age, gender, systolic blood pressure, anti-hypertensive medication use, smoking status, diabetes mellitus, total cholesterol, previous atrial fibrillation) and baseline LA parameters.

Conclusion

In this multi-ethnic population free of clinical cardiovascular disease at baseline, ∆LAVimin was most strongly associated with, and incrementally predictive of incident HF, after adjusting for known risk factors and baseline LA measures.

Change in left atrial function and volume predicts heart failure with preserved and reduced ejection fraction: the multi-ethnic study of atherosclerosis

Aims

This study used cardiac magnetic resonance (CMR) imaging to investigate the relationship between longitudinal change in left atrial (LA) function and incident heart failure (HF), in a multi-ethnic population free of known cardiovascular disease at baseline.

Methods and results

In the Multi-Ethnic Study of Atherosclerosis (MESA), 2470 participants (60±9 years, 47% males), free at baseline of clinically recognized cardiovascular disease, had LA volume and function assessed with CMR imaging at baseline (2000–02) and 9.4±0.6 years later. Seventy three (3%) participants developed incident HF over 7.1±2.1 years; of these, 39 participants had preserved ejection fraction (HFpEF) and 34 participants had reduced ejection fraction (HFrEF). An annual decrease of 1-SD unit in peak LA strain (ΔLASmax) was most strongly associated with the risk of HFpEF (subdistribution HR=2.56, 95% confidence interval (CI) [1.34–4.90], P=0.004) and improved model reclassification and discrimination in predicting HFpEF (c-statistic=0.84, 95% CI [0.79–0.90]; NRI=0.34, P=0.01; IDI=0.02, P=0.02; x2=4.25, P=0.89) adjusting for event-specific risk factors and baseline LA parameters. An annual decrease of 1ml/m2 of pre-atrial LA volume index (ΔLAVipreA) was most strongly associated with the risk of HFrEF (subdistribution HR=1.88, 95% CI [1.44–2.45], P<0.001) and improved model reclassification and discrimination in predicting HFrEF (c-statistic=0.81, 95% CI (0.72–0.90); NRI=0.31, P=0.03; IDI=0.01, P=0.50; x2=15.4, P=0.08), adjusting for event-specific risk factors and baseline LA measures (Table 1).

Conclusion

In this multi-ethnic population free of clinical cardiovascular disease at baseline, ΔLASmax and ΔLAVipreA were associated with, and incrementally predictive of HFpEF and HFrEF respectively, after adjusting for event-specific risk factors and baseline LA measures.

Disclaimer

The views expressed in this abstract are those of the authors and do not necessarily represent the views of the National Heart, Lung, and Blood Institute; the National Institutes of Health; or the U.S. Department of Health and Human Services.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Heart, Lung and Blood InstituteNational Center for Advancing Translational Sciences

The safety of hepatectomy after transarterial radioembolization: Single institution experience and review of the literature

BACKGROUND AND OBJECTIVES

The liver is a frequent site of malignancy, both primary and metastatic. The treatment goal of patients with liver cancer may include transarterial radioembolization (TARE). There are limited reports on the safety of hepatectomy following TARE. Our study's purpose is to review patients who have received TARE followed by hepatectomy.

METHODS

A retrospective study was performed on patients diagnosed with any liver cancer from 2013 to 2019 who underwent TARE followed by hepatectomy. Postoperative complications were prospectively collected. Descriptive statistics and the Kaplan-Meier test were used to assess survival outcomes.

RESULTS

Twelve patients were treated with a TARE followed by a hepatectomy (nine with ≥4 segments resected). Diagnoses included: six HCC, four cholangiocarcinoma, one metastatic neuroendocrine tumor, and one metastatic colorectal cancer. There were no 90-day post-hepatectomy mortalities and the overall morbidity was 66% (16% severe ≥MAGS 3). Hepatectomy-specific complications after hepatectomy included two (16%) bile leaks and no post-hepatectomy liver failures. The median recurrence free survival was 26 months. Overall survival at 1-year was 78% and at 3 years was 47%.

CONCLUSIONS

Our results support the safety of hepatectomy in select patients after TARE. Additional comparison to patients who receive hepatectomy as a first-line treatment for liver cancers should be investigated.

Leak-free million-fold DNA amplification with locked nucleic acid and targeted hybridization in one pot

An isothermal cascade reaction that exponentially amplifies pre-designed, single-stranded DNA as a sensor and signal amplifier module for DNA-based computing and molecular robotics was developed. Taking advantage of the finding that locked nucleic acid can suppress problematic ab initio DNA synthesis, up to million-fold amplification rates and concurrent hybridization were achieved at a physiological temperature in a single reactor. Although the effect of locked nucleic acid introduction to the templates was complicated, undesired leak DNA amplification was generally suppressed in the amplification reaction for distinct DNA sequences. The present reaction that senses one DNA as an input and generates a large amount of another DNA as an output, exhibiting a high correlation between the molecular concentration and the amplification time, is applicable for nucleic acid quantification.

298Change in respiratory muscle strength predicts clinical events in patients with chronic heart failure

Background

Respiratory muscle weakness, frequently observed in patients with chronic heart failure (CHF), has been documented as a predictor for poor prognosis. Several studies have reported that respiratory muscle training increases respiratory muscle strength and consequently improves exercise tolerance and quality of life in these patients. However, the relationship between the change in respiratory muscle strength and prognosis is still unclear.

Purpose

We aimed to investigate whether the change in respiratory muscle strength following cardiac rehabilitation predicts the incidence of clinical events in CHF patients.

Methods

We studied 348 patients with CHF who were hospitalized because of decompensated heart failure and received 5-month cardiac rehabilitation during hospitalization and after hospital discharge. Clinical characteristics including aetiology of heart failure, comorbidity conditions, medications, blood examination and echocardiographic variables were obtained from clinical records. We also measured maximal inspiratory pressure (PImax) as respiratory muscle strength at hospital discharge and 5 months later. The change of PImax (ΔPImax) between the 5-month observation period was examined. We followed up the patients after the observation period and investigated the incidence of all-cause mortality or all-cause unplanned readmission. In statistical analysis, patients were divided into two groups based on the median value of ΔPImax. We compared the event-free survival rate between the two groups using the Kaplan-Meier method with a log-rank test. We also performed the Cox proportional hazard model to clarify whether the ΔPImax was an independent predictor for the incidence of clinical events.

Results

Over a median follow-up of 1.6 years, 121 patients (34.8%) died or readmitted, and their rate of incidence was 21.7/100 person-years. The higher ΔPImax was associated significantly with a higher rate of event-free survival (Log-rank: 8.085, P=0.004, Figure 1). In univariate Cox proportional hazard model, ΔPImax was a significant predictor for the all-cause mortality/readmission (unadjusted hazard ratio for PImax increase of 10 cmH2O: 0.842, 95% CI: 0.763 - 0.931, P=0.001). Even after adjustment for clinical confounding factors including baseline PImax, ΔPImax remained significant and independent predictor for the all-cause mortality/readmission (adjusted hazard ratio for PImax increase of 10 cmH2O: 0.862, 95% CI: 0.763 - 0.974, P=0.017, Figure 2).

Conclusion

This study is the first to demonstrate that the change in respiratory muscle strength following cardiac rehabilitation independently predicts the incidence of clinical events in patients with CHF. The increase in PImax of 10 cmH2O was associated significantly with a 14% decrease in the rate of all-cause mortality or readmission.

Acknowledgement/Funding

JSPS KAKENHI JP16K16442

Comparison of Response and Outcomes of Drug-eluting Bead Chemoembolization (DEB-TACE) Versus Radioembolization (TARE) for Patients With Colorectal Cancer Liver Metastases

BACKGROUND

To compare outcomes for patients with colorectal cancer liver metastases (CRCLM) treated by drug-eluting bead chemoembolization (DEB-TACE) or radioembolization (TARE).

PATIENTS AND METHODS

A single-center retrospective review was carried out on 202 patients with CRCLM, treated by DEB-TACE (n=47) or TARE (n=155) patients. Propensity-matching yielded 44 pairs. Paired statistical analysis was performed on matched pair demographics, treatment response, and survival.

RESULTS

Patients treated with DEB-TACE had worse extra-hepatic metastasis (68.1 vs. 47.7%, p=0.014) and ≥10 liver lesions (42.2 vs. 68.8%, p=0.001). Matched patients treated with DEB-TACE had a trend towards worse toxicity (27% vs. 9.1% (p=0.057). Index DEB-TACE treatment was not a prognostic factor for overall survival (hazard ratio=0.94, 95% confidence intervaI=0.54-1.65; p=0.83).

CONCLUSION

In the matched CRCLM cohort, there was a trend towards worse toxicity post-DEB-TACE treatment, but it was not an independent prognostic factor for survival.

Radiofrequency Ablation vs. Cryoablation for Localized Hepatocellular Carcinoma: A Propensity-matched Population Study

BACKGROUND/AIM

To compare overall survival (OS) and liver cancer-specific survival (LCSS) of Surveillance, Epidemiology and End Results (SEER) hepatocellular carcinoma (HCC) database patients treated with cryoablation (cryo) or radiofrequency ablation (RFA).

MATERIALS AND METHODS

This was a retrospective review of Stage I or II HCC patients from the SEER database treated with cryo and RFA from 2004-2013. Kaplan-Meier and Cox regressions were performed on pooled and propensity-matched cohort.

RESULTS

Out of 3,239 patients, RFA showed a significant survival advantage over cryo in liver cancer specific survival (LCSS) (HR=1.634 p=0.0004). A total of 91 propensity-matched pairs had similar OS (HR=1.006 p=0.9768), but no difference in LCSS was observed between the groups [HR=1.412 (95%CI=0.933-2.137) p=0.1023]. Survival Cox models did not reveal treatment type as an independent prognostic factor.

CONCLUSION

Propensity-matched cohort showed no significant difference in terms of OS and LCSS was found for patients treated with either cryo or RFA for localized HCC.

SEER study of ablation versus partial nephrectomy in cT1A renal cell carcinoma

Aim: Compare ablation versus partial nephrectomy (PN) in T1A renal cell carcinoma (RCC) treatment, using the SEER database. Methods: Patients with diagnosed T1A RCC from 2004 to 2013 were identified. Propensity matching paired subjects with similar background variables. Kaplan–Meier and Cox proportional hazards regression were performed before and after matching. Results: Cohort included 4592 patients (809 ablation, 3783 PN). PN compared with ablation group had significantly increased overall survival (OS; 93.6% vs 81.9% 5-year survival; p < 0.0001) and cancer-specific survival (CSS; p < 0.0001). After matching (1222 pairs), PN group had significantly increased OS (91.0% vs 86.3% 5-year survival; p = 0.0457) but similar CSS (p = 0.4023). Conclusion: Ablation offers similar CSS but lower OS as PN for T1A RCC in this SEER database.

Prognostic usefulness of arm circumference and nutritional screening tools in older patients with cardiovascular disease

BACKGROUND AND AIM

Arm circumference (AC) and nutritional screening tools have been shown to have prognostic capability in patients with cardiovascular disease (CVD). This study aimed to compare the prognostic predictive capabilities of AC and nutritional screening tools in older patients with CVD.

METHODS AND RESULTS

The study population consisted of 949 admitted patients ≥60 years old with CVD. Patients underwent AC measurement and nutritional screening before hospital discharge. We used the controlling nutritional status index (CONUT), the geriatric nutritional risk index (GNRI), and the prognostic nutritional index (PNI) as nutritional screening tools. The end point of the study was all-cause mortality. The mean age of the study population was 72.3 ± 7.2 years, and 68.2% of the patients were male. A total of 130 deaths occurred over a median follow-up period of 2.2 years (interquartile range, 1.1-3.8 years). After adjusting for other prognostic factors, AC (hazard ratio [HR]: 0.59; p < 0.001), CONUT (HR: 0.82; p = 0.016), GNRI (HR: 0.77; p = 0.040), and PNI (HR: 0.80; p = 0.014) were significant predictors of mortality. However, adding AC to the multivariate-adjusted model (0.739 vs. 0.714, respectively; p = 0.037), but not CONUT, GNRI, or PNI (0.724, 0.717, and 0.723 vs. 0.714; p = 0.072, p = 0.306, and p = 0.127, respectively), significantly increased the area under the curve on receiver operating characteristic curve.

CONCLUSIONS

AC, but not nutritional screening tools, plays a complementary role to preexisting prognostic factors for predicting prognosis in older patients with CVD.

Liver-dominant Breast Cancer Metastasis: A Comparative Outcomes Study of Chemoembolization Versus Radioembolization

AIM

To compare toxicity, response, and survival outcomes of patients with hepatic metastases from breast cancer who underwent transarterial chemoembolization (TACE) or radioembolization (TARE).

MATERIALS AND METHODS

A retrospective review was carried out of all patients who underwent TACE or TARE for liver-dominant breast cancer metastases between January 2006 and March 2016 at an academic medical center in the United States.

RESULTS

Seventeen patients in the TACE group and 30 patients in the TARE group received 32 TACE and 49 TARE treatments, respectively. Median follow-up was 9 months. Both groups had similar background variables. More all-grade adverse events were seen in the TACE group (71% vs. 44%; p=0.02). Median overall survival in the TACE group was 4.6 months compared to 12.9 months in the TARE group (p=0.2349). Treatment type was not an independent prognostic factor.

CONCLUSION

TARE is better tolerated than TACE for the treatment of liver-dominant breast cancer metastasis. There was a trend towards improved survival with TARE; however, it did not approach statistical significance. Larger studies are needed to validate these findings.

Survival comparison of hepatocellular carcinoma patients treated with radioembolization versus nonoperative/interventional treatment

AIM

To compare the overall survival (OS) and liver cancer-specific survival of advanced-stage hepatocellular carcinoma (HCC) patients who received transarterial radioembolization (TARE) with those who received nonoperative/interventional treatment (NOT).

MATERIALS & METHODS

A total of 12,520 HCC patients from the Surveillance, Epidemiology and End Results database were categorized by treatment with either radioembolization or NOT. Kaplan-Meier and multivariate Cox regression were conducted.

RESULTS

The TARE group had both a significantly longer median overall survival than the NOT group (TARE = 9 months; NOT = 2 months; p < 0.0001) and a significantly higher probability of liver cancer-specific survival (hazard ratio = 0.474).

CONCLUSION

TARE appears to provide a significant survival advantage over the NOT population in advanced HCC patients.

Thermal ablation versus surgical resection for localized hepatocellular carcinoma: a population study using the SEER database

AIM

To compare overall survival (OS) and liver cancer-specific survival (LCSS) in patients with localized hepatocellular carcinoma treated with surgical resection (SR) or thermal ablation (TA) using the Surveillance, Epidemiology and End Results database.

MATERIALS & METHODS

Kaplan-Meier, competing risk and Cox regression analyses were performed after identifying patients. Propensity score matching was then applied.

RESULTS

There was significantly better OS in the SR group and significantly lower probability of LCSS in the TA group. After matching, there was significantly longer OS in the SR group and a lower probability of LCSS in the TA group.

CONCLUSION

SR offered a significant survival benefit over TA for localized hepatocellular carcinoma.

Chemoembolization versus radioembolization for the treatment of unresectable intrahepatic cholangiocarcinoma in a single institution image-based efficacy and comparative toxicity

Aim

Compare radioembolization (Y90) and chemoembolization (CE) for the treatment of unresectable intrahepatic cholangiocarcinoma (UICC).

Materials & methods

Institutional Review Board-approved, retrospective search was performed. Forty patients with UICC were treated with either Y90 (n = 25, 39 treatments) or CE (n = 15, 35 treatments). Comparative analysis was performed using Student's t and fisher-exact tests. Multivariable-logistic regression was also performed.

Results

Median ages were 60 and 64 years for CE and Y90 groups, respectively (p = 0.798). Patient variables including age, Eastern Cooperative Oncology Group score, tumor burden, extra-hepatic disease, prior chemotherapy and prior surgery were similar between groups. Adverse events were similar in both groups (CE 20%, Y90 26%; p > 0.9). Overall response rate (CE 6%, Y90 4%; p > 0.9) and disease control rate (CE 46%, Y90 48%; p > 0.9) were statistically similar. Multilogistic regression did not identify any variables that correlated with disease control rate, including Eastern Cooperative Oncology Group score and tumor burden.

Conclusion

Our observation shows that CE and Y90 display similar toxicity and disease control in the treatment of UICC.

Foraging at the edge of chaos: internal clock versus external forcing

Activity rhythms in animal groups arise both from external changes in the environment, as well as from internal group dynamics. These cycles are reminiscent of physical and chemical systems with quasiperiodic and even chaotic behavior resulting from "autocatalytic" mechanisms. We use nonlinear differential equations to model how the coupling between the self-excitatory interactions of individuals and external forcing can produce four different types of activity rhythms: quasiperiodic, chaotic, phase locked, and displaying over or under shooting. At the transition between quasiperiodic and chaotic regimes, activity cycles are asymmetrical, with rapid activity increases and slower decreases and a phase shift between external forcing and activity. We find similar activity patterns in ant colonies in response to varying temperature during the day. Thus foraging ants operate in a region of quasiperiodicity close to a cascade of transitions leading to chaos. The model suggests that a wide range of temporal structures and irregularities seen in the activity of animal and human groups might be accounted for by the coupling between collectively generated internal clocks and external forcings.

Symmetry Breaking in Escaping Ants

The phenomenon of herding is a very general feature of the collective behavior of many species in panic conditions, including humans. It has been predicted theoretically that panic-induced herding in individuals confined to a room can produce a nonsymmetrical use of two identical exit doors. Here we demonstrate the existence of that phenomenon in experiments, using ants as a model of pedestrians. We show that ants confined to a cell with two symmetrically located exits use both exits in approximately equal proportions to abandon it in normal conditions but prefer one of the exits if panic is created by adding a repellent fluid. In addition, we are able to reproduce the observed escape dynamics in detail using a modification of a previous theoretical model that includes herding associated with a panic parameter as a central ingredient. Our experimental results, combined with theoretical models, suggest that some features of the collective behavior of humans and ants can be quite similar when escaping under panic.

Role of BLNK in oxidative stress signaling in B cells

BLNK (B cell linker protein) represents a central linker protein that bridges the B cell receptor-associated kinases with a multitude of signaling pathways. In this study, we have investigated the role of BLNK in oxidative stress signaling in B cells. H2O2 treatment of B cells induced a rapid tyrosine phosphorylation of BLNK in a H2O2 dose-dependent manner, which was inhibited in Syk-deficient DT40 cells. Calcium mobilization in BLNK-deficient as well as Syk-deficient and phospholipase C (PLC)-gamma2-deficient cells after H2O2 treatment was completely abolished. These were derived from decreased inositol 1,4,5-trisphosphate generation through PLC-gamma2 in BLNK-deficient cells. Moreover, viability of BLNK-deficient as well as PLC-gamma2-deficient cells after exposure to low doses of H2O2 was dramatically enhanced compared with that of the wild-type cells. Furthermore, c-Jun N-terminal kinase activation following high doses of H2O2 stimulation, but not low doses of H2O2 stimulation, was abrogated in BLNK-deficient as well as Syk-deficient cells. These findings have led to the suggestion that BLNK is required for coupling Syk to PLC-gamma2, thereby accelerating cell apoptosis in B cells exposed to low doses of H2O2.

Avalanches in one-dimensional piles with different types of bases

We perform a systematic experimental study of the influence of the type of base on the avalanche dynamics of slowly driven 1D ball piles. The control of base details allows us to explore a wide spectrum of pile structures and dynamics. The scaling properties of the observed avalanche distributions suggest that self-organized critical behavior is approached as the "base-induced" disorder at the pile profile increases.

Prospective study of mother-to-infant transmission of hepatitis C virus

BACKGROUND

Mother-to-infant transmission of hepatitis C virus (HCV) could become the main route of HCV infection in the future because there are no methods available to prevent vertical infection. The aim of this study was to determine the incidence of mother-to-infant transmission in infants born to mothers who tested positive for anti-HCV antibodies and to elucidate associated risk factors for transmission.

METHODS

Screening was conducted for 16,800 pregnant women with an anti-HCV antibodies test, and 154 mothers were positive. From the positive group 141 mothers were enrolled in the study and their 147 infants were followed from birth for serum alanine aminotransferase activity, anti-HCV antibodies and HCV RNA. HIV infection was tested in 73 of 141 mothers, all of whom were negative.

RESULTS

Thirty-three infants were dropped from the study because they were followed for <6 months or were not tested adequately. Of the 114 infants finally evaluated 9 (7.8%) had detectable HCV RNA. The transmission rate was not influenced by the mode of delivery [vaginal delivery, 8 of 90 vs. cesarean section, 1 of 24 (P = 0.396)] or by the type of feeding [9 of 98 for breast-fed infants vs. 0 of 16 for formula-fed infants (P = 0.243)]. All infected infants were born to mothers who had HCV viremia at the delivery (P = 0.040) and to those with a high viral load (P = 0.019).

CONCLUSIONS

Our prospective study showed that the transmission rate of mother-to-infant HCV infection was 7.8% in anti-HCV antibody-positive mothers. Risk was related to the presence of maternal HCV viremia at delivery and a high viral load in the mothers.

Tissue distribution of constitutive proteasomes, immunoproteasomes, and PA28 in rats

We investigated the expression of standard proteasomes, immunoproteasomes, and their regulators, PA28, and PA700, in rat tissues. Immunoproteasomes (with subunits LMP2, LMP7, and MECL1) were abundant in the spleen but almost absent in the brain. In contrast, standard proteasomes (with X, Y, and Z) were highly expressed in the brain but not in the spleen. Both proteasome types were present in the lung and the liver. PA700 subunits (p112, S5a, and p45) were found in all tissues. PA28alpha, PA28beta, and PA28gamma were also expressed in all tissues, except for the brain which contained very little PA28beta. The results did not depend on rat sex or age. The cleavage specificity for peptide substrates differed greatly between brain and spleen proteasomes. Hybrid proteasomes, containing both PA28alphabeta and PA700, were not present in the brain but in all other tissues examined.

Syk is required for the activation of Akt survival pathway in B cells exposed to oxidative stress

Syk has been demonstrated to play a crucial role in oxidative stress signaling in B cells. Here we report that Syk is required for the activation of the phosphatidylinositol (PI) 3-kinase-Akt survival pathway in B cells exposed to oxidative stress. Phosphorylation and activation of the serine-threonine kinase Akt were markedly increased in B cells treated with H(2)O(2). In Syk-deficient DT40 cells treated with low doses of H(2)O(2) (10-100 microm), Akt activation was considerably reduced. Pretreatment with wortmannin, a PI 3-kinase-specific inhibitor, completely blocked the Syk-dependent Akt activation. Following stimulation by low doses of H(2)O(2), a significant increase in PI 3-kinase activity was found in wild-type but not in Syk-deficient cells. These findings suggest that PI 3-kinase mediates Syk-dependent Akt activation pathway. Furthermore, viability of Syk-deficient cells, after exposure to H(2)O(2), was dramatically decreased and caspase-9 activity was greatly increased compared with that of the wild-type cells. These results suggest that Syk is essential for the Akt survival pathway in B cells and enhances cellular resistance to oxidative stress-induced apoptosis.

Distinctive functions of Syk N-terminal and C-terminal SH2 domains in the signaling cascade elicited by oxidative stress in B cells

Syk plays a crucial role in the transduction of oxidative stress signaling. In this paper, we investigated the roles of Src homology 2 (SH2) domains of Syk in oxidative stress signaling, using Syk-negative DT40 cells expressing the N- or C-terminal SH2 domain mutant [mSH2(N) or mSH2(C)] of Syk. Tyrosine phosphorylation of Syk in cells expressing mSH2(N) Syk after H(2)O(2) treatment was higher than that in cells expressing wild-type Syk or mSH2(C) Syk. The tyrosine phosphorylation of wild-type Syk and mSH2(C) Syk, but not that of mSH2(N), was sensitive to PP2, a specific inhibitor of Src-family protein-tyrosine kinase. In oxidative stress, the C-terminal SH2 domain of Syk was demonstrated to be required for induction of tyrosine phosphorylation of cellular proteins, phospholipase C (PLC)-gamma2 phosphorylation, inositol 1,4, 5-triphosphate (IP(3)) generation, Ca(2)(+) release from intracellular stores, and c-Jun N-terminal kinase activation. In contrast, in mSH2(N) Syk-expressing cells, tyrosine phosphorylation of intracellular proteins including PLC-gamma2 was markedly induced in oxidative stress. The enhanced phosphorylation of mSH2(N) Syk and PLC-gamma2, however, did not link to Ca(2)(+) mobilization from intracellular pools and IP(3) generation. Thus, the N- and C-terminal SH2 domains of Syk possess distinctive functions in oxidative stress signaling.

[Examination of soluble cell adhesion molecules in pregnancy induced hypertension]

This study was performed to determine whether or not the soluble-intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1) and endothelial leukocyte adhesion molecule-1 (sELAM-1) are sensitive markers of pregnancy induced hypertension (PIH). sICAM-1 concentrations were significantly higher (p < 0.05) in the mild PIH compared to non-pregnant women and normal pregnant groups. sVCAM-1 concentrations in the mild PIH group and the severe PIH group were significantly higher than the non-pregnant women group (p < 0.0001, p < 0.01, respectively) and the normal pregnant group (p < 0.0001, p < 0.0005, respectively). The concentrations of sELAM-1 in the mild PIH group were also significantly higher compared to normal pregnant group (p < 0.01). Our results suggest that soluble cell adhesion molecules may be useful markers detecting endothelial damage and dysfunction in patients with PIH.

Overtone Transitions of 12CO2 beyond the Venus Bands

Combination overtone transitions of 12CO2 much weaker than the Venus bands in the near infrared (11 700-14 200 cm-1) have been observed for the first time by using photoacoustic spectroscopy. A total of six bands from two Fermi polyad groups were recorded and both the band origins and relative intensities have been determined and compared with the calculated values. Through a comparison of the relative absorption cross sections within the same type of polyads, intensity shifts have been observed and will be discussed. Copyright 1999 Academic Press.

[A case of congenital complete heart block in a mother with anti-52 kD SS-A/Ro antibodies]

We report a case of congenital complete heart block (CCHB). A 38-year-old woman was admitted our hospital because of fetal bradycardia at 21 weeks 3 days of gestational age. She had no symptom of collagen disease. On admission, laboratory data showed positive anti-nuclear antibodies, anti-SS-A/Ro antibodies and anti-52 kD SS-A/Ro antibodies. But anti-60 kD SS-A/Ro and anti-SS-B/La antibodies were negative. Consequently anti-52 kD SS-A/Ro antibodies positive woman had an infant with CCHB. The baby was equipped with pacemaker at the age of 2 months. This report suggests that anti-52 kD SS-A/Ro antibodies may play an important role in the development of CCHB.

CDNA cloning of p112, the largest regulatory subunit of the human 26s proteasome, and functional analysis of its yeast homologue, sen3p

The 26S proteasome is a large multisubunit protease complex, the largest regulatory subunit of which is a component named p112. Molecular cloning of cDNA encoding human p112 revealed a polypeptide predicted to have 953 amino acid residues and a molecular mass of 105,865. The human p112 gene was mapped to the q37.1-q37.2 region of chromosome 2. Computer analysis showed that p112 has strong similarity to the Saccharomyces cerevisiae Sen3p, which has been listed in a gene bank as a factor affecting tRNA splicing endonuclease. The SEN3 also was identified in a synthetic lethal screen with the nin1-1 mutant, a temperature-sensitive mutant of NIN1. NIN1 encodes p31, another regulatory subunit of the 26S proteasome, which is necessary for activation of Cdc28p kinase. Disruption of the SEN3 did not affect cell viability, but led to temperature-sensitive growth. The human p112 cDNA suppressed the growth defect at high temperature in a SEN3 disruptant, indicating that p112 is a functional homologue of the yeast Sen3p. Maintenance of SEN3 disruptant cells at the restrictive temperature resulted in a variety of cellular dysfunctions, including defects in proteolysis mediated by the ubiquitin pathway, in the N-end rule system, in the stress response upon cadmium exposure, and in nuclear protein transportation. The functional abnormality induced by SEN3 disruption differs considerably from various phenotypes shown by the nin1-1 mutation, suggesting that these two regulatory subunits of the 26S proteasome play distinct roles in the various processes mediated by the 26S proteasome.

Isolation and characterization of a novel perchloric acid-soluble protein inhibiting cell-free protein synthesis

We found a novel protein in the postmitochondria supernatant fraction of rat liver, which is soluble in 5% perchloric acid and strongly inhibits protein synthesis in a rabbit reticulocyte lysate system. The protein extracted from the supernatant fraction with 5% perchloric acid was purified by ammonium sulfate fractionation and CM-Sephadex chromatography. The protein was shown to consist of two identical subunits with a molecular mass of 14 kDa. By immunoscreening with the rabbit antisera against the protein, a cDNA encoding the protein was cloned and sequenced. The cDNA contained an open reading frame of 411 base pairs encoding a 136-amino acid protein with a molecular mass of 14,149 Da. The deduced amino acid sequence was completely identical with that constructed from all of the above peptides. Interestingly, the perchloric acid-soluble protein inhibited cell-free protein synthesis in the rabbit reticulocyte lysate system in a different manner from RNase A. The protein is likely to inhibit an initiation stage of cell-free protein synthesis. Among the rat tissues tested, the protein was located only in liver and kidney. These findings are the first report on a new inhibitor that may be involved in the regulation of protein synthesis in those tissues.

Molecular cloning of two types of cDNA encoding subunit RC6-I of rat proteasomes

A new subunit, named RC6-I, of the rat 20 S proteasome was purified and the partial amino acid sequences of several peptide fragments obtained by digestion with lysyl-endopeptidase were determined by Edman degradation. Amplification of cDNAs encoding RC6-I by the polymerase chain reaction (PCR) technique revealed two types of cDNA, tentatively designated as RC6-IL and RC6-IS in order of size. The nucleotide sequences of the two cDNAs are identical except that RC6-IL contains an insertion of 18 nucleotides in the coding region compared with RC6-IS. The polypeptide predicted from the open reading frame of RC6-IS cDNA consists of 248 amino acid residues with a calculated molecular weight of 27,783. These values are consistent with those obtained by protein chemical analyses. Computer-assisted homology analysis showed that RC6-I belongs to the alpha-type subfamily of the proteasome gene family, which shows similarity to the alpha-subunit of the archaebacterium Thermoplasma acidophilum proteasome, and that the 18 nucleotide insert, encoding six amino acid residues, VVASVS, appears to be unique to RC6-IL, because this motif has not been conserved in any other alpha-type subunit. By reverse transcription (RT)-PCR analysis, the mRNAs for both RC6-IL and RC6-IS were found in all the rat tissues examined. These results suggest that proteasomes are present as a heterogeneous population, possibly for acquisition of diversity of functions.

Primary structures of two homologous subunits of PA28, a gamma-interferon-inducible protein activator of the 20S proteasome

The primary structures of two proteins that comprise PA28, an activator of the 20S proteasome, have been determined by cDNA cloning and sequencing. These protein subunits, termed PA28 alpha and PA28 beta, are about 50% identical to one another and are highly conserved between rat and human. PA28 alpha and PA28 beta are homologous to a previously described protein, Ki antigen, whose function is unknown. PA28 alpha, but neither PA28 beta nor Ki antigen, contains a 'KEKE motif', which has been postulated to promote the binding of proteins having this structural feature. PA28 alpha and PA28 beta were coordinately regulated by gamma-interferon, which greatly induced mRNA levels of both proteins in cultured cells. The mRNA level of the Ki antigen also increased in response to gamma-interferon treatment, but the magnitude of the increase was less than that for the PA28s, and the effect was transient. These results demonstrate the existence of a new protein family, at least two of whose members are involved in proteasome activation. They also provide the basis for future structure/function studies of PA28 subunits and the determination of their relative physiological roles in the regulation of proteasome activity.

cDNA cloning of a new putative ATPase subunit p45 of the human 26S proteasome, a homolog of yeast transcriptional factor Sug1p

The nucleotide sequence of a cDNA that encodes a new regulatory subunit, named p45, of the 26S proteasome of human hepatoblastoma HepG2 cells has been determined. The polypeptide predicted from the open reading frame consists of 406 amino acid residues with a calculated molecular weight of 45770 and isoelectric point of 8.35. The sequences of several fragments of bovine p45, determined by protein chemical analyses, spanning 27% of the complete structure, were found to be in excellent accord with those deduced from the human cDNA sequence. Computer analysis showed that p45 belongs to a family of putative ATPases which includes regulatory components of 26S proteasomes. The overall structure of p45 was found to be homologous to that of yeast Sug1p, which has been identified as a transcriptional factor. It is closely similar, but not identical to the sequence reported for Trip1, a functional homolog of Sug1p in human tissues. These results are consistent with the possibility that Sug1-like proteins with distinct sequence function in transcription and protein degradation in human cells. However, the alternative hypothesis, that the same gene locus encodes both p45 and Trip1, cannot be excluded on the basis of such closely similar sequences. In either case, both proteins are likely to function equivalently well in either transcription or protein degradation.

Isolation and characterization of the HC8 subunit gene of the human proteasome

For study of the molecular basis of regulation of proteasome gene expression, we isolated the gene encoding the alpha-type HC8 subunit of the human proteasome. About 2.3 kb of the 5' flanking region of this gene was tested for promoter function by chloramphenicol acetyltransferase assay. This analysis revealed that CAAT and TATA boxes, but not a GC box, are essential for its promoter activity. These results differed from previous findings that the genes for the alpha-type HC3 and beta-type HC5 subunits of the human proteasome have a TATA-less promoter and that two or three GC boxes function as the promoter sequences (Tamura, T. et al. (1994) J. Mol. Biol. 244, 1117-1124). We mapped the HC8 gene at q23 on human chromosome 14, which differs from the chromosomal locations of nine other proteasomal subunit genes mapped so far.

Expression of GATA-binding transcription factors in rat hepatocytes

Recently, we demonstrated that a DNA-binding protein(s) is involved in transcriptional repression of the rat serine dehydratase gene in fetal liver. Here, we report that a GAT(A/T) motif is the target sequence for the DNA-binding protein. By screening a fetal liver cDNA library, we isolated a rat homolog of GATA-1. Rat GATA-1 expressed as a GST-fusion protein in E. coli bound to the GAT(A/T) motif in the serine dehydratase gene. Northern analysis show that GATA-1 and GATA-4 mRNAs are expressed in fetal hepatocytes.

cDNA cloning and interferon gamma down-regulation of proteasomal subunits X and Y

Proteasomes are the proteolytic complex responsible for major histocompatibility complex (MHC) class I-restricted antigen presentation. Interferon gamma treatment increases expression MHC-encoded LMP2 and LMP7 subunits of the proteasome and decreases expression of two proteasome subunits, named X and Y, which alters the proteolytic specificity of proteasomes. Molecular cloning of complementary DNAs encoding X and Y showed that their proteins are proteasomal subunits with high amino acid similarity to LMP7 and LMP2, respectively. Thus, interferon gamma may induce subunit replacements of X and Y by LMP7 and LMP2, respectively, producing proteasomes perhaps more appropriate for the immunological processing of endogenous antigens.