Twenty-year follow-up of promising clinical studies reported in highly circulated newspapers: a meta-epidemiological study

OBJECTIVES

Researchers have identified cases in which newspaper stories have exaggerated the results of medical studies reported in original articles. Moreover, the exaggeration sometimes begins with journal articles. We examined what proportion of the studies quoted in newspaper stories were confirmed.

METHODS

We identified newspaper stories from 2000 that mentioned the effectiveness of certain treatments or preventions based on original studies from 40 main medical journals. We searched for subsequent studies until June 2022 with the same topic and stronger research design than each original study. The results of the original studies were verified by comparison with those of subsequent studies.

RESULTS

We identified 164 original articles from 1298 newspaper stories and randomly selected 100 of them. Four studies were not found to be effective in terms of the primary outcome, and 18 had no subsequent studies. Of the remaining studies, the proportion of confirmed studies was 68.6% (95% CI 58.1% to 77.5%). Among the 59 confirmed studies, 13 of 16 studies were considered to have been replicated in terms of effect size. However, the results of the remaining 43 studies were not comparable.

DISCUSSION

In the dichotomous judgement of effectiveness, about two-thirds of the results were nominally confirmed by subsequent studies. However, for most confirmed results, it was impossible to determine whether the effect sizes were stable.

CONCLUSIONS

Newspaper readers should be aware that some claims made by high-quality newspapers based on high-profile journal articles may be overturned by subsequent studies within the next 20 years.

Elevated admission urinary N-acetyl-β-D-glucosamidase level is associated with worse long-term clinical outcomes in patients with acute heart failure

Background:

The prognostic significance of urinary N-acetyl-β-D-glucosamidase in acute heart failure has not been fully elucidated. Accordingly, this study investigated whether urinary N-acetyl-β-D-glucosamidase could be associated with subsequent adverse events in acute heart failure patients.

Methods:

We studied 708 consecutive acute heart failure patients who had accessible N-acetyl-β-D-glucosamidase data on admission from the National Cerebral and Cardiovascular Center Acute Decompensated Heart Failure registry. We assessed the relationship between the admission N-acetyl-β-D-glucosamidase level and the combined endpoint of all-cause death and worsening heart failure. Worsening heart failure was defined as worsening symptoms and signs of heart failure requiring intensification of intravenous therapy such as diuretics, vasodilators and inotropes or initiation of mechanical support after stabilisation with initial treatment during hospitalisation, or readmission due to heart failure after discharge.

Results:

During a median follow-up period of 763 (interquartile range 431–1028) days, higher urinary N-acetyl-β-D-glucosamidase was significantly related to increased events of all-cause death and worsening heart failure. In addition, patients with higher urinary N-acetyl-β-D-glucosamidase and lower estimated glomerular filtration rate on admission had the worst clinical outcomes. In multivariable Cox regression, urinary N-acetyl-β-D-glucosamidase on admission was independently associated with adverse events (hazard ratio 1.19, 95% confidence interval 1.04–1.35) even after adjustment by covariates including the baseline estimated glomerular filtration rate.

Conclusions:

Higher urinary N-acetyl-β-D-glucosamidase level on admission was independently associated with worse clinical outcomes. Our findings indicate the potential value of assessing urinary N-acetyl-β-D-glucosamidase on admission for further risk stratification in patients with acute heart failure.

Prognostic value of base excess as indicator of acid-base balance in acute heart failure

BACKGROUND

Acid-base balance can change as a result of pulmonary oedema and low tissue perfusion in acute heart failure patients. However, its long-term prognostic significance remains to be clarified.

METHODS

We prospectively examined a cohort of 472 consecutive acute heart failure patients who underwent arterial blood gas analysis on admission between January 2013 and May 2016. Acidaemia, alkalaemia and normal range of base excess were defined as pH <7.38, >7.42 and -2 to 2 mEq/L, respectively. The primary outcome was all-cause death.

RESULTS

During a median follow-up period of 714 days, 101 patients died. Although there was no difference in mortality among patients with acidaemia, normal pH and alkalaemia (p = 0.92), patients with high base excess had the highest mortality compared with others. Multivariable Cox proportional hazard models revealed that high base excess was an independent determinant of mortality (hazard ratio 1.83, 95% confidence interval 1.08-3.13 (high versus normal base excess), hazard ratio 0.81, 95% confidence interval 0.47-1.41 (low versus normal base excess)), even after adjustment for significant prognostic covariates. Furthermore, regarding mortality stratified by base excess and carbon dioxide partial pressure (pCO₂), patients with high base excess (>2.1 mEq/L) and high pCO₂ (>40 mmHg) had the highest mortality compared with others.

CONCLUSIONS

High base excess, but not low base excess, on admission was associated with long-term mortality in acute heart failure patients, indicating the importance of evaluating acid-base balance on admission by base excess for stratifying the risk of mortality in patients with acute heart failure.

Identification of malignant early repolarization pattern by late QRS activity in high-resolution magnetocardiography

Background

The early repolarization pattern (ERP) in electrocardiography (ECG) has been considered as a risk for ventricular fibrillation (VF), but effective methods for identification of malignant ERP are still required. We investigated whether high spatiotemporal resolution 64‐channel magnetocardiography (MCG) would enable distinction between benign and malignant ERPs.

Methods

Among all 2,636 subjects who received MCG in our facility, we identified 116 subjects (43 ± 18 years old, 54% male) with inferior and/or lateral ERP in ECG and without structural heart disease, including 13 survivors of VF (ERP‐VF(+)) and 103 with no history of VF (ERP‐VF(−)). We measured the following MCG parameters in a time‐domain waveform of relative current magnitude: (a) QRS duration (MCG‐QRSD), (b) root‐mean‐square of the last 40 ms (MCG‐RMS40), and (c) low amplitude (<10% of maximal) signal duration (MCG‐LAS).

Results

Compared to ERP‐VF(−), ERP‐VF(+) subjects presented a significantly longer MCG‐QRS (108 ± 24 vs. 91 ± 23 ms, p = .02) and lower MCG‐RMS40 (0.10 ± 0.08 vs. 0.25 ± 0.20, p = .01) but no difference in MCG‐LAS (38 ± 22 vs. 29 ± 23 ms, p = .17). MCG‐QRSD and MCG‐RMS40 showed significantly larger area under the ROC curve compared to J‐peak amplitude in ECG (0.72 and 0.71 vs. 0.50; p = .04 and 0.03). The sensitivity, specificity, and odds ratio for identifying VF(+) based on MCG‐QRSD ≥ 100 ms and MCG‐RMS40 ≤ 0.24 were 69%, 74%, and 6.33 (95% CI, 1.80–22.3), and 92%, 48%, and 10.9 (95% CI, 1.37–86.8), respectively.

Conclusion

Magnetocardiography is an effective tool to distinguish malignant and benign ERPs.

Evidence-Based Utilization of Prognostic Prediction Models in Cardiovascular Medicine

Prediction models are combinations of predictors to assess the risks of specific endpoints such as the presence or prognosis of a disease. Many novel predictors have been developed, modelling techniques have been evolving, and prediction models are currently abundant in the medical literature, especially in cardiovascular medicine, but evidence is still lacking regarding how to use them. Recent methodological advances in systematic reviews and meta-analysis have enabled systematic evaluation of prediction model studies and quantitative analysis to identify determinants of model performance. Knowing what is critical to model performance, under what circumstances model performance remains adequate, and when a model might require further adjustment and improvement will facilitate effective utilization of prediction models and will enhance diagnostic and prognostic accuracy in clinical practice. In this review article, we provide a current methodological overview of the attempts to implement evidence-based utilization of prognostic prediction models for all potential model users, including patients and their families, health-care providers, administrators, researchers, guideline developers and policy makers.

A comprehensive validation of very early rule-out strategies for non-ST-segment elevation myocardial infarction in emergency departments: protocol for a multicentre prospective cohort study

INTRODUCTION

Recent advances in troponin sensitivity enabled early and accurate judgement of ruling-out myocardial infarction, especially non-ST elevation myocardial infarction (NSTEMI) in emergency departments (EDs) with development of various prediction-rules and high-sensitive-troponin-based strategies (hs-troponin). Reliance on clinical impression, however, is still common, and it remains unknown which of these strategies is superior. Therefore, our objective in this prospective cohort study is to comprehensively validate the diagnostic accuracy of clinical impression-based strategies, prediction-rules and hs-troponin-based strategies for ruling-out NSTEMIs.

METHODS AND ANALYSIS

In total, 1500 consecutive adult patients with symptoms suggestive of acute coronary syndrome will be prospectively recruited from five EDs in two tertiary-level, two secondary-level community hospitals and one university hospital in Japan. The study has begun in July 2018, and recruitment period will be about 1 year. A board-certified emergency physician will complete standardised case report forms, and independently perform a clinical impression-based risk estimation of NSTEMI. Index strategies to be compared will include the clinical impression-based strategy; prediction rules and hs-troponin-based strategies for the following types of troponin (Roche Elecsys hs-troponin T; Abbott ARCHITECT hs-troponin I; Siemens ADVIA Centaur hs-troponin I; Siemens ADVIA Centaur sensitive-troponin I). The reference standard will be the composite of type 1 MI and cardiac death within 30 days after admission to the ED. Outcome measures will be negative predictive value, sensitivity and effectiveness, defined as the proportion of patients categorised as low risk for NSTEMI. We will also evaluate inter-rater reliability of the clinical impression-based risk estimation.

ETHICS AND DISSEMINATION

The study is approved by the Ethics Committees of the Kyoto University Graduate School and Faculty of Medicine and of the five hospitals where we will recruit patients. We will disseminate the study results through conference presentations and peer-reviewed journals.

Rationale and Design of Low-dose Administration of Carperitide for Acute Heart Failure (LASCAR-AHF)

BACKGROUNDS

Despite current therapies, acute heart failure (AHF) remains a major public health burden with high rates of in-hospital and post-discharge morbidity and mortality. Carperitide is a recombinantly produced intravenous formulation of human atrial natriuretic peptide that promotes vasodilation with increased salt and water excretion, which leads to reduction of cardiac filling pressures. A previous open-label randomized controlled study showed that carperitide improved long-term cardiovascular mortality and heart failure (HF) hospitalization for patients with AHF, when adding to standard therapy. However, the study was underpowered to detect a difference in mortality because of the small sample size.

METHODS

Low-dose Administration of Carperitide for Acute Heart Failure (LASCAR-AHF) is a multicenter, randomized, open-label, controlled study designed to evaluate the efficacy of intravenous carperitide in hospitalized patients with AHF. Patients hospitalized for AHF will be randomly assigned to receive either intravenous carperitide (0.02 μg/kg/min) in addition to standard treatment or matching standard treatment for 72 h. The primary end point is death or rehospitalization for HF within 2 years. A total of 260 patients will be enrolled between 2013 and 2018.

CONCLUSION

The design of LASCAR-AHF will provide data of whether carperitide reduces the risk of mortality and rehospitalization for HF in selected patients with AHF.

Elevated Plasma D-Dimer Level Is Associated With Short-Term Risk of Ischemic Stroke in Patients With Acute Heart Failure

BACKGROUND AND PURPOSE

The incidence of heart failure increases the subsequent risk of ischemic stroke, and its risk could be higher in the short-term period after an acute heart failure (AHF) event. However, its determinants remain to be clarified. Plasma D-dimer level reflects fibrin turnover and exhibits unique properties as a biomarker of thrombosis. The aim of this study is to investigate whether D-dimer level is a determinant of short-term incidence of ischemic stroke in patients with AHF.

METHODS

We examined 721 consecutive hospitalized AHF patients with plasma D-dimer level on admission from our prospective registry between January 2013 and May 2016. The study end points were incidence of ischemic stroke during hospitalization and at 30 days after admission.

RESULTS

Of the total participants (mean age, 76 years; male, 60%; atrial fibrillation, 54%; mean left ventricular ejection fraction, 38%), in-hospital ischemic stroke occurred in 18 patients (2.5%) during a median hospitalization period of 21 days, and 30-day ischemic stroke occurred in 16 patients (2.2%). Higher D-dimer level on admission was an independent determinant of subsequent risk of in-hospital ischemic stroke even after adjustment by CHA₂DS₂-VASc score (odds ratio, 2.29; 95% confidence interval, 1.46-3.60; P<0.001) or major confounders, including age, atrial fibrillation, and antithrombotic therapy (odds ratio, 2.31; 95% confidence interval, 1.43-3.74; P<0.001). Subgroup analyses showed consistent findings in patients without atrial fibrillation (odds ratio, 2.46; 95% confidence interval, 1.39-4.54; P=0.002) and those without antithrombotic therapy (odds ratio, 2.79; 95% confidence interval, 1.53-5.57; P<0.001). Similar results were obtained for 30-day ischemic stroke as an alternative outcome.

CONCLUSIONS

Elevated plasma D-dimer level on admission was significantly associated with increased incidence of ischemic stroke shortly after admission for AHF, suggesting a predictive role of D-dimer for short-term ischemic stroke events in patients with AHF.

CLINICAL TRIAL REGISTRATION

URL: https://www.umin.ac.jp/ctr/index.htm. Unique identifier: UMIN000017024.

Impact of iron deficiency on long-term clinical outcomes of hospitalized patients with heart failure

BACKGROUND

Iron deficiency (ID) is commonly observed in chronic heart failure (HF) patients and is associated with worse clinical outcomes. While ID is frequent finding in hospitalized heart failure (HHF), its impact on long-term outcome in HHF patients remains unclear.

METHODS

We evaluated iron status at discharge in 578 HHF patients. Absolute ID was defined as serum ferritin <100 μg/L, and functional ID (FID) was defined as serum ferritin of 100-299 μg/L with transferrin saturation <20%. The primary outcome of interest was the composite of all-cause mortality and HF admission at one year.

RESULTS

Among the study population, 185 had absolute ID, 88 had FID and 305 had no evidence of ID. At one-year post-discharge, 64 patients had died and 112 had been readmitted with HF. Patients with absolute ID had more adverse events than those with FID or no ID (p = 0.021). In multivariate Cox regression analyses, absolute ID was significantly associated with increased risk of adverse events at one year (HR 1.50, 95% CI 1.02-2.21, p = 0.040) compared with the remaining patients. Sensitivity analysis revealed that its prognostic effect did not differ across anemic status, or between HF with reduced and preserved ejection fraction (p for interaction = 0.17, 0.68, respectively).

CONCLUSION

Absolute ID, but not FID, at discharge was associated with increased risk of one-year mortality or HF admission in patients with HHF. Further studies are required to evaluate the role of repleting iron stores and its impact on clinical outcomes in patients with HHF.

Usefulness of the Direct and/or Total Bilirubin to Predict Adverse Outcomes in Patients With Acute Decompensated Heart Failure

Abnormal liver function test results are often observed in acute decompensated heart failure (ADHF). However, the prognostic value of bilirubin fractionation has not been elucidated. The prognostic value of direct bilirubin (DB), in comparison with total bilirubin (TB), was examined in 556 consecutive patients with ADHF. Patients with elevated DB showed mostly similar patient characteristics including signs of elevated right-sided pressure (frequent hepatomegaly, jugular venous distention, dilated inferior vena cava, and elevated gamma-glutamyltransferase) and decreased cardiac output (cold extremities, decreased pulse pressure, and lower blood pressure) and other parameters of heart failure (HF) severity (increased plasma renin activity, decreased sodium, total cholesterol, and ejection fraction) to elevated TB; however, only patients with elevated DB showed a significant difference in the frequency of HF history and alkaline phosphatase value. Kaplan-Meier analysis showed that patients with elevated DB had a significantly higher rate of the composite end point of all-cause mortality or HF readmission (p = 0.021) compared with those with normal DB, whereas patients with elevated TB did not show a statistically significant difference compared with those with normal TB (NS). A multivariate Cox hazards model showed that DB was an independent predictor of adverse events (adjusted hazard ratio 1.052, 95% confidence interval 1.001 to 1.099, p = 0.034), whereas TB was not (adjusted hazard ratio 1.017, 95% confidence interval 0.985 to 1.046, p = 0.27). Adding DB to existing prognostic variables resulted in higher C-statistics than adding TB (C-statistics: 0.670 to 0.675, 0.670 to 0.674, respectively). In conclusion, elevated DB in ADHF was an independent prognostic predictor that was superior to TB. DB may be useful for further risk stratification in ADHF.

Prognostic value of malnutrition assessed by Controlling Nutritional Status score for long-term mortality in patients with acute heart failure

BACKGROUND

The prognostic value of nutritional status is poorly understood and evidence-based nutritional assessment indices are required in acute heart failure (AHF). We investigated the prognostic value of malnutrition assessed by the Controlling Nutritional Status (CONUT) score (range 0-12, higher=worse, consisting of serum albumin, cholesterol and lymphocytes) in AHF patients.

METHODS

The CONUT score was measured on admission in 635 consecutive AHF patients. The primary outcome was all-cause death.

RESULTS

Median CONUT score was 3 (interquartile range 2 to 5). During the median follow-up of 324days, CONUT score was independently associated with death (HR 1.26, 95% CI 1.11-1.42, P<0.001) after adjustment for confounders in a multivariate Cox model. The CONUT score demonstrated the best C-statistic for predicting death (0.71) among other common nutritional markers in HF. Furthermore, addition of the CONUT score to an established risk prediction model from the Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure study significantly increased the C-statistic from 0.75 to 0.77 (P=0.02). The net reclassification improvement afforded by CONUT score was 21% for all-cause death, 27% for survival and 49% overall (P<0.001).

CONCLUSION

Malnutrition assessed by the CONUT score on admission was an independent determinant of long-term death in AHF, and its prognostic value outweighed that of other nutritional indices. Moreover, addition of the score to the existing risk prediction model significantly increased the predictive ability for death, indicating beneficial clinical application of the CONUT score in AHF patients.

Circulating Omega-6, But Not Omega-3 Polyunsaturated Fatty Acids, Are Associated with Clinical Outcomes in Patients with Acute Decompensated Heart Failure

Background

Circulating polyunsaturated fatty acid (PUFA) levels are associated with clinical outcomes in cardiovascular diseases including coronary artery disease and chronic heart failure (HF). However, their clinical implications in acute decompensated HF (ADHF) remain unclear. The aim of this study was to investigate the clinical roles of circulating PUFAs in patients with ADHF.

Methods

Circulating levels of PUFAs, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA) and dihomo-gamma linoleic acid (DGLA), were measured on admission in 685 consecutive ADHF patients. Adverse events were defined as all-cause death and worsening HF.

Results

During a median follow-up period of 560 days, 262 (38.2%) patients had adverse events. Although patients with adverse events had lower n-6 PUFA (AA + DGLA) level than those without, n-3 PUFA (EPA + DHA) level was comparable between the groups. Kaplan-Meier analyses showed that lower n-6 PUFA level on admission was significantly associated with the composite of all-cause death and worsening HF, all-cause death, cardiovascular death and worsening HF (p < 0.001, p = 0.005, p = 0.021, p = 0.019, respectively). In a multivariate Cox model, lower n-6 PUFA level was independently associated with increased risk of adverse events (HR 0.996, 95% CI: 0.993–0.999, p = 0.027).

Conclusions

Lower n-6 but not n-3 PUFA level on admission was significantly related to worse clinical outcomes in ADHF patients. Measurement of circulating n-6 PUFA levels on admission might provide information for identifying high risk ADHF patients.

Prognostic significance of endogenous erythropoietin in long-term outcome of patients with acute decompensated heart failure

AIMS

Although previous reports suggest that an elevated endogenous erythropoietin (EPO) level is associated with worse clinical outcomes in chronic heart failure (HF) patients, the prognostic implication of EPO in patients with acute decompensated HF (ADHF) and underlying mechanisms of the high EPO level in severe HF patients who have a poor prognosis remain unclear.

METHODS AND RESULTS

We examined 539 consecutive ADHF patients with EPO measurement on admission from our registry. During a median follow-up period of 329 days, a higher EPO level on admission was independently associated with worse clinical outcomes [hazard ratio (HR) 1.25, 95% confidence interval (CI) 1.06-1.48, P = 0.008], and haemoglobin level was the strongest determinant of EPO level (P < 0.001), whereas estimated glomerular filtration rate (eGFR) was not significant in multivariate regression analysis. In the anaemic subgroup of 318 patients, a higher EPO level than expected on the basis of their haemoglobin level was related to increased adverse events (HR 1.63, 95% CI 1.05-2.49, P = 0.028). Moreover, estimated plasma volume excess rate was positively associated with EPO level (P = 0.003), and anaemic patients with a higher than expected EPO level tended to have a higher estimated plasma volume excess rate and plasma lactate level, and lower systemic oxygen saturation level with the preservation of the reticulocyte production index than those with a lower than expected EPO level.

CONCLUSION

A high EPO level predicts long-term worse clinical outcomes in ADHF patients, independent of anaemia and impaired renal function. Anaemia and hypoxia due to severe congestion may synergistically contribute to a high EPO level in high-risk HF patients.

Dipeptidyl peptidase-4 inhibitors attenuate endothelial function as evaluated by flow-mediated vasodilatation in type 2 diabetic patients

BACKGROUND

Endothelial dysfunction is an independent predictor for cardiovascular events in patients with type 2 diabetes (T2DM). Glucagon like peptide-1 (GLP-1) reportedly exerts vasodilatory actions, and inhibitors of dipeptidyl peptidase-4 (DPP-4), an enzyme-degrading GLP-1, are widely used to treat T2DM. We therefore hypothesized that DPP-4 inhibitors (DPP-4Is) improve endothelial function in T2DM patients and performed 2 prospective, randomized crossover trials to compare the DPP-4I sitagliptin and an α-glucosidase inhibitor, voglibose (in study 1) and the DPP-4Is sitagliptin and alogliptin (in study 2).

METHODS AND RESULTS

In study 1, 24 men with T2DM (46±5 years) were randomized to sitagliptin or voglibose for 6 weeks without washout periods. Surprisingly, sitagliptin significantly reduced flow-mediated vasodilatation (FMD; -51% compared with baseline, P<0.05) of the brachial artery despite improved diabetic status. In contrast, voglibose did not affect FMD. To confirm this result and determine whether it is a class effect, we conducted another trial (study 2) to compare sitagliptin and alogliptin in 42 T2DM patients (66±8 years) for 6 weeks with 4-week washout periods. Both DPP-4Is improved glycemic control but significantly attenuated FMD (7.2/4.3%, P<0.001, before/after sitagliptin; 7.0/4.8%, P<0.001, before/after alogliptin, respectively). Interestingly, FMD reduction was less evident in subjects who were on statins or whose LDL cholesterol levels were reduced by them, but this was not correlated with parameters including DPP-4 activity and GLP-1 levels or diabetic parameters.

CONCLUSIONS

Our 2 independent trials demonstrated that DPP-4 inhibition attenuated endothelial function as evaluated by FMD in T2DM patients. This unexpected unfavorable effect may be a class effect of DPP-4Is.

CLINICAL TRIAL REGISTRATION

URL: http://center.umin.ac.jp, Unique Identifiers: UMIN000005682 (sitagliptin versus voglibose) and UMIN000005681 (sitagliptin versus alogliptin).

Grafting neural stem cells improved the impaired spatial recognition in ischemic rats

To determine the possible therapeutic potential of neural stem cells (NSCs) introduced into the damaged central nervous system, we grafted adult hippocampus-derived NSCs into the hippocampus of rats with transient global ischemia. Transient four-vessel occlusion yielded 90-95% losses of pyramidal neurons in the hippocampal CA1 region. In this region, 1-3% of the grafted cells survived; and 3-9% of them expressed NeuN, a neuronal marker. Rats with more than 120 NeuN-positive cells showed partial improvement of impaired spatial learning in a water maze test. These results suggest that NSCs grafted in the ischemic brain are able to differentiate into neurons and to improve spatial recognition.

JNK activation is associated with intracellular beta-amyloid accumulation

c-Jun has been implicated in the pathogenesis of Alzheimer's disease (AD), but the upstream cascade leading to c-Jun activation in AD is not known. Activation of c-Jun N-terminal kinase (JNK) is obviously a candidate for the upstream event. We tested this possibility focusing on PS1-linked AD. First, we observed that JNK is actually activated in cerebral neurons of PS1-linked AD patients, using immunohistochemistry and Western blot analyses with anti-activated JNK antibodies. We analyzed the relationship between beta-amyloid (beta A) and JNK activation by using aged transgenic mice overexpressing mutant (M146L) PS1 and human AD brains. The mice showed no neuronal loss but a very few diffuse beta A deposits, corresponding to the early stage of PS1-linked AD brain. Some neurons were reactive for anti-beta A antibodies in the cerebral cortex. Interestingly, JNK activation was observed in neurons showing intracellular beta A immunoreactivity in transgenic mice. Association between intracellular beta A and JNK activation was confirmed in cortical neurons of sporadic and PS1-linked AD patients. Furthermore, introduction of beta A peptides into the primary culture cortical neurons induced JNK activation and cell death. Collectively, these results suggested that intracellular beta A accumulation might trigger JNK activation leading to neuronal death.

Haemopoietic biglycan produced by brain cells stimulates growth of microglial cells

We have recently found that soluble biglycan purified from rat thymic myoid cells had haemopoietic activity capable of inducing preferential growth and differentiation of monocytic lineage cells from various haemopoietic sources, including brain microglial cells. In the present study, to understand developmental mechanisms of microglial/monocytic cells in the brain, we have attempted to identify haemopoietic activity of the brain biglycan. The mRNA and the immunological epitope of biglycan were detected in the rat brain homogenates and several rat glial cell lines. Immunohistochemical study showed that several different types of brain cells produced biglycan. During development biglycan synthesis in the brain appeared to be increased. The brain haemopoietic biglycan was easily separated by DEAE-Sepharose chromatography from the macrophage colony stimulating factor (M-CSF) which was concomitantly produced from the brain cells. The brain haemopoietic biglycan, purified through immunoaffinity column, indeed stimulated growth of primarily cultured microglial cells. Taken together, these results suggest that the haemopoietic biglycan plays an important role in generating brain-specific circumstances for development of microglial/monocytic cells.

Analysis of lymphoproliferative cytokines produced by thymic myoid cells

Lymphoproliferative activities produced by cloned thymic myoid cell 871207B were analysed by immunological and biochemical methods. The lymphoproliferative activities were separated into two fractions by DEAE-Sepharose CL-6B chromatography: one is in the fraction passed through the column and the other in the fraction eluated from the column with a low concentration of NaCl. The eluated fraction induced the proliferation of interleukin-1 (IL-1)-dependent D10N4 M cells. This activity was abrogated by an anti-IL-1 alpha antibody, but not an anti-IL-1 beta antibody. Expression of IL-1 alpha mRNA was also detected in 871207B cells. The thymocyte proliferative activity found in the fraction passed through the DEAE-Sepharose column was further separated into three fractions by heparin-Sepharose column chromatography: (1) the fraction passed through the column, (2) the fraction weakly bound to the column, and (3) the fraction firmly bound to the heparin column. The fraction passed through the heparin column sustained the growth of IL-6-dependent MH60.BSF-2 cells. IL-6-specific mRNA was found in 871207B cells. The thymocyte proliferative activity of the fraction firmly bound to the heparin column was neutralized with an anti-IL-7 antibody. The biological activity of the fraction weakly bound to the column remained to be elucidated. These results suggest that thymic myoid cells produce IL-1 alpha, IL-6, IL-7 and unidentified lympho-stimulatory factors, all of which play significant roles in many steps of T-cell development in the thymus.

Transformations of Penicillium islandicum and Penicillium frequentans that produce anthraquinone-related compounds

Wild-type strains of Penicillium islandicum and Penicillium frequentans, which produce anthraquinone and related compounds, were transformed to benomyl and hygromycin B resistance. Plasmids pSV50 and pBT6, with benomyl-resistant beta-tublin genes, and plasmids pAN7-1 and pDH25, with a bacterial hygromycin phosphotransferase gene under the control of Aspergillus nidulans sequences, were used respectively. Transformation frequencies with these plasmids were 10-20 transformants per micrograms of DNA per 4-8 x 10(7) viable protoplasts. Integration of plasmid DNAs into chromosomal DNAs was confirmed by Southern-blot analysis. Copy numbers and sites of integration varied among transformants. The integrated plasmid DNAs conferring a drug-resistant phenotype were mitotically stable with or without selection. The demonstration of such transformation systems in the essential first step in the application of recombinant DNA technology to study the biosynthetic genes of anthraquinone and related compounds in P. islandicum and P. frequentans.

Immunological and biochemical characterization of biglycan-like haemopoietic factor

Immunological and biochemical characteristics of a 100,000 MW biglycan-like haemopoietic factor, purified from thymic myoid cells 871207B, were studied to distinguish them from macrophage colony-stimulating factor (M-CSF), which they resemble in activity and biochemical properties. Rabbit antibody raised against a synthetic peptide fragment (J-1) designed from amino acid sequences specific to the 100,000 MW factor responded to 871207B cells, the conditioned medium of 871207B, and capillary-like structures in the thymus, but not to M-CSF producer L-929 cells or the conditioned medium of L-929 cells. In contrast, M-CSF epitope was detected in L-929 cells and the conditioned medium cells but not in 871207B cells or the conditioned medium, even after enzymatic digestion of glycosaminoglycan chains. Treatment of the 100,000 MW factor with chondroitinase ABC and AC produced a 50,000 MW component. Digestion of this product with N-glycanase resulted in a 40,000 MW protein component. These results suggest that the 100,000 MW factor is a proteoglycan consisting of a core protein with an apparent molecular mass of 40,000 MW, a 50,000 MW chondroitin sulphate chain and 10,000 MW N-linked oligosaccharide chains. A small amount of a 40,000 MW monocytic cell growth activity was also found in the 871207B cell-conditioned medium. An enzymatically obtained 40,000 MW factor, the conditioned medium 40,000 MW factor, and the 100,000 MW factor were specifically eluated from an anti-J-1 IgG-immobilized affinity column with monocytic cell growth activity, suggesting that the biological activity resides in the 40,000 MW core protein. The 100,000 MW factor induced the proliferation and differentiation of monocytic lineage cells from a variety of sources, such as bone marrow cells, peritoneal exudated cells and brain microglia cells.

Action of a nuclease from rat nuclei on UV-irradiated DNA

An Mg(2+)-dependent nuclease was highly purified from rat-liver nuclei. The nuclease activity was enhanced in ultraviolet light (UV)-irradiated dsDNA, but not in unirradiated dsDNA. Irrespective of UV irradiation, ssDNA was readily cleaved by this enzyme. UV-irradiated plasmid DNA was incubated with this enzyme and subjected to the template primer activity assay with a Klenow polymerase. With increasing incubation time, the activity was enhanced in the circular-relaxed and linear forms, but not in the superhelical form. These results implied that this enzyme excises UV-damaged sites in dsDNA to form single strand gaps for repair synthesis.

Vasorelaxant and hypotensive effects of tilisolol hydrochloride (N-696) in isolated rat thoracic aorta and pithed rats

Vasorelaxant and hypotensive effects of tilisolol hydrochloride (N-696) in isolated rat thoracic aorta and pithed rats were investigated. In rat thoracic aorta pre-contracted with KCl (20 mM), tilisolol (10(-5)-10(-3) M) produced concentration-related relaxation, but nadolol and atenolol did not significantly inhibit the responses to 20 mM KCl. The concentration-relaxation curve of tilisolol underwent rightward parallel shifts only to a limited extent in the presence of glibenclamide, a specific antagonist of K+ channel openers. Glibenclamide also shifted the concentration-relaxation curve of cromakalim to the right and in a parallel manner, whereas it did not change that of propranolol. In pithed rats, tilisolol (0.5-2.0 mg/kg, i.v.), but neither nadolol nor atenolol, caused a dose-dependent decrease in diastolic blood pressure and a slight increase in heart rate. Following treatment of the preparation with glibenclamide, the hypotensive effects of tilisolol and cromakalim were antagonized, while that of propranolol was not affected. These results suggest that the vasorelaxant and hypotensive actions of tilisolol involve an opening of K+ channels which can be inhibited by glibenclamide and may also involve additional relaxant mechanisms of action independent of K+ channel opening.

Bending of a highly repetitive component in rat nuclear DNA

A highly repetitive component in rat nuclear DNA was isolated by HindIII digestion and cloned. A 370-bp cloned component was highly AT-rich (68.3%) in about one third of the region from the 3'-terminus and showed an anomalously slow gel electrophoretic mobility (k-factor = 1.19). These results indicated that a sequence-directed bending of the helix axis occurs in the component. Accordingly, a subclone containing a tandem dimer of the component was isolated and subjected to a circular permutation analysis for exploring the bend center (1). In consequence, the center was shown to be present in the sequence ranging from position near 270 to the 3'-terminus and estimated to be located around position 340.

A nuclease from rat-liver nuclei with endo- and exonucleolytic activity

An Mg2(+)-dependent endonuclease endogenous to rat-liver nuclei had an exonuclease activity for single-stranded DNA, but not for duplex DNA. The activity was about twice as high in the 3'----5' direction as in the 5'----3' direction. The products by 3'----5' activity were mononucleotides alone. The 5'----3' activity released mononucleotides as main products and small amounts of di-, tri-, tetra- and oligonucleotides. Another major endonuclease endogenous to the nuclei, a Ca2+/Mg2(+)-dependent endonuclease, did not have such exonuclease activities.

Base sequences of highly repetitive components in nuclear DNAs from rat liver and rat-ascites hepatoma

A 370-bp highly repetitive component in each of the nuclear DNAs from rat liver (RL) and rat-ascites hepatoma (AH) was isolated by HindIII digestion and cloned in pUC9. Ten of the resulting clones were arbitrarily selected and sequenced. Heterogeneity of size was found in 7 of the RL clones (366-369 bp), but in only 2 of the AH clones (369 bp). The sequence homology was 64.6% among the RL clones; 80.3% among the AH clones. The base compositions were AT-rich, ranging from 61.1% to 64.7%. Many A and/or T runs consisting of 2-5 bases were interspersed throughout each sequence. The restriction sites reported previously, EcoRI, HaeIII, HindIII, HinfI and HphI sites, were confirmed in almost all of the clones. In the present experiment, 12 kinds of the sites were further found in both RL and AH clones.

Affinity of a DNA with highly repetitive sequence for nuclear proteins from rat liver

A nuclear scaffold fraction (designated P fraction elsewhere) comparable to a nuclear matrix was prepared from rat liver. This fraction was composed mainly of 45-49 kDa proteins and high-molecular-weight proteins (more than 90 kDa). In addition, a 370-bp repetitive sequence DNA fragment was derived predominantly from the EcoRI digest of the deproteinized P fraction. By an immunoblot affinity assay with the P fraction, the fragment was shown to have affinity for each of the 107- and 115-kDa proteins. Moreover, by a filter binding assay with a mixture of these proteins, the affinity level was estimated to be about 6 times as high in the native (double-stranded) fragment as in the denatured (single-stranded) fragment.