Prediction for cardiac prognosis in patients with congestive heart failure by machine learning on dual-isotope myocardial semiconductor SPECT

Background

Dual-isotope (low doze 201TlCl and 123I-β-methyl-P-iodophenyl-pentadecanoic acid (BMIPP)) single photon emission computed tomography (SPECT) is utilized to estimate myocardial damage in patients with congestive heart failure (CHF). However, predictive model construction on the SPECT for cardiac death by machine learning was not studied.

Purpose

To elucidate predictive value of machine learning model on dual-isotope SPECT for CHF.

Methods

We enrolled consecutive 310 patients who admitted with CHF (77.1±3.1 years, 164 males). After initial treatment, they underwent electrocardiography gated SPECT and observed in median 507 days [IQR: 165, 1032]. Multivariate Cox regression analysis for cardiac death was performed, and predictive model was constructed by ROC curve analysis and machine learning (Random Forest and Deep Learning). The accuracies (= [True positive + True negative] / Total) of the prediction models were compared with ROC curve model.

Results

Thirty-six patients fell into cardiac death. Cox analysis showed Age, left ventricular ejection fraction (LVEF), summed rest score (SRS) of BMIPP, and mismatch score were significant predictors (Hazard ratio: 1.068, 0.970, 1.032, 1.092, P value: <0.001, 0.014, 0.002, <0.001, respectively). ROC curve analysis of them revealed the accuracy of the cut-off value was 0.479–0.773. Conversely, machine learning model demonstrated higher accuracy for cardiac death (Random Forest: 0.895, Deep Learning: 0.935). The top 4 feature importance of the random forest were LVEF (0.299), SRS BMIPP (0.263), Age (0.262), and mismatch score (0.160).

Conclusion

Machine learning model on SPECT was superior to conventional statistic model for predicting cardiac death in patients with CHF.

Funding Acknowledgement

Type of funding source: None

The comparison of the chronic-phase vascular healing between bioabsorbable and durable polymer drug eluting stent by using optical coherence tomography

Background

Bioabsorbable polymer drug eluting stents (BP-DESs) were designed to reduce a vascular inflammatory reaction compared to durable polymer drug eluting stents (DP-DESs). However, few studies have compared vascular responses to BP-DESs and DP-DESs.

Methods

We enrolled 88 consecutive patients with single culprit coronary artery lesions (31 lesions with acute coronary syndrome) undergoing a single stent-implantation. BP-DESs and DP-DESs were implanted in 50 (57%) and 38 patients (43%), respectively. All lesions underwent optical coherence tomography examination at chronic phase and intrastent OCT findings at the follow-up were evaluated in every 1-mm cross-sections (CSs).

Results

A total of 1887 CSs (BP-DES: 1096, DP-DES: 791) were analyzed. The median period of follow-up OCT was 293 (250–374) days. There were no differences in the patient, lesion, and initial clinical presentation of acute coronary syndrome (ACS). BP-DESs had significantly higher percent neointimal hyperplasia area, defined as neointimal hyperplasia area divided by stent area x 100 (18.4±9.0% vs. 16.1±9.9%, p<0.001), fewer malapposed struts (1.7% vs. 3.9%, p=0.005), fewer uncovered struts (3.6% vs. 5.8%, p=0.02) but higher frequency of superficial low intensity neointima (LIN) (7.7% vs. 3.4%, p<0.001). Multivariate logistic analysis showed that BP-DES (OR: 2.5, 95% CI: 1.49–4.08, p<0.001) and the initial clinical presentation of ACS (OR: 2.31, 95% CI: 1.47–3.62, p<0.001) are independent predictive factors for LIN.

Conclusion

BP-DESs showed homogenous neointimal growth and complete stent coverage quantitatively. Meanwhile, the significant relationships of BP-DES with LIN may suggest that the neointimal quality remains immature in BP-DESs in this period.

Funding Acknowledgement

Type of funding source: None

Optical coherence tomography findings in healed vulnerable plaques in patients with coronary artery disease

Background

Histopathological analysis or intracoronary image assessment of healed plaques (HPs) has been reported both in acute coronary syndrome (ACS) and stable angina pectoris (SAP) patients. However, background characteristics or lesion morphologies of HPs could not be fully clarified and their differences according to the clinical status remain undetermined.

Purpose

We sought to investigate the clinical and morphological characteristics and compare their differences among ACS and SAP patients in order to clarify the clinical significance in HPs lesions.

Methods

We enrolled consecutive 201 patients with 213 native coronary artery lesions (139 lesions with SAP, 42 ST elevation-ACS (STE-ACS) and 32 non-ST elevation ACS (NSTE-ACS) undergoing pre-intervention optical coherence tomography (OCT). HPs was defined as layered phenotype on OCT. Clinical and angiography characteristics and lesion morphologies on OCT were assessed.

Results

HPs were observed in 110 lesions (51.6%) and their prevalence were not different according to the clinical status (SAP:55.1%, STE-ACS:38.1%, NSTE-ACS:56.3%, p=0.14). Lesions with HPs had higher frequencies of angiography-eccentric lesions (62.7% vs. 35.9%, p<0.001) and OCT-macrophages (65.5% vs. 43.1%, p<0.001), and greater OCT-lumen area stenosis (%-AS) (77.1±10.2% vs. 73.6±10.6%, p=0.01) than those without HPs. Of lesions with HPs, OCT-thin-cap fibroatheroma (SAP 14.4%, STE-AC43.8%, NSTE-ACS 16.7%, p=0.03), plaque rupture (5.3%; 37.5%; 11.1%, p<0.001) and thrombus (6.6%, 75.0%, 22.2%, p=0.007) were more frequently observed in STE-ACS than in SAP patients, whereas OCT-microvessels were more frequent in SAP than in ACS patients (19.7%, 0.0%, 0.0%, p=0.02). Other OCT findings such as macrophages, cholesterol crystal, multiple layered phenotype, and %-AS were not significantly different according to the clinical status. Multivariate logistic regression analysis identified the angiography-eccentric lesions (odds ratio (OR): 2.97, 95% confidence intervals (CI): 1.68–5.25, p<0.001) and OCT macrophages (OR 2.41, 95% CI 1.36–4.27, p=0.003) as independent related factors for the existence of HPs.

Conclusions

The present study showed that HPs lesions had eccentric and large plaque burden, and persistent plaque inflammations regardless of clinical status, which might lead to future coronary events.

Funding Acknowledgement

Type of funding source: None

Optical coherence tomography and coronary angioscopy assessment of healed vulnerable plaque components in patients with coronary artery lesions undergoing elective percutaneous coronary intervention

Background

Many vulnerable plaques would progress without clinical events and might result in healed plaques (HPs). Histopathological or intracoronary image assessment of HPs has been reported. However, the morphological characteristics of HPs remain unclear yet.

Purpose

We sought to assess the healed vulnerable plaque components in patients with coronary artery lesions using optical coherence tomography (OCT) and coronary angioscopy (CAS).

Methods

We enrolled 47 patients with 50 native coronary artery lesions with angiographical severe stenosis (>90% diameter-stenosis) and without severe calcification (36 lesions with stable angina pectoris (SAP) and 14 acute coronary syndrome (ACS)) undergoing pre-intervention OCT and CAS. HPs was defined as layered phenotype on OCT. Lesion morphologies and plaque characteristics in lesions with HPs were assessed using OCT and CAS images.

Results

HPs were observed in 27 lesions (54.0%) and their prevalence were similar among each clinical status (SAP 52.8%, ACS 57.1%, p=1.00). Lesions with HPs had higher prevalence of OCT-macrophage (88.0% vs. 52.0%, p=0.01), CAS-red thrombus (88.8% vs. 52.2%, p=0.004) and CAS-low grade-yellow plaque (grade 1) (55.6% vs. 21.7%, p=0.02) than those without. SAP lesions with HPs had higher prevalence of CAS-yellow plaque (35.3% vs. 5.9%, p=0.09) and OCT-thin-cap fibroatheroma (42.1% vs. 5.9%, p=0.04) than SAP without HPs. ACS lesions with HPs had less CAS-red thrombus (0.0% vs. 50.0%, p=0.03) and OCT-plaque rupture (12.5% vs. 66.7%, p=0.04) than ACS without HPs. Multivariate logistic regression analysis revealed that OCT-macrophages (odds ratio (OR): 6.65, 95%-confidence intervals: 1.07–41.5, p=0.043), CAS-red thrombus (OR 8.77, 95% CI 1.33–57.8, p=0.02), and low grade-yellow plaque (OR 13.05, 95% CI 1.97–86.5, p=0.008) were independently related with the existence of HPs lesions. Combination of these 3 factors showed a high predictive value of OCT-HPs lesions (90.9%).

Conclusions

HPs lesions showed the lower lesion vulnerability than common ACS lesions but had more intraplaque inflammatory condition compared with common SAP lesions. Combined CAS and OCT examination might be useful to clarify the plaque components of HPs lesions in vivo, leading to help us understand the clinical significance of HPs.

Funding Acknowledgement

Type of funding source: None

Differences of ST level at J-point on 12-lead electrocardiography can distinguish takotsubo syndrome and acute anterior myocardial infarction

Background

Qualitative difference of ST elevation/depression on 12-leads electrocardiography (ECG) at onset was reported in patients with Takotsubo syndrome (TTS) and acute anterior myocardial infarction (ant AMI). However, quantitative difference of those was not elucidated.

Purpose

To investigate differences of ST level at J point on ECG between TTS and ant AMI by automated calculating system.

Methods

We firstly enrolled consecutive 40 patients of TTS, and among 500 ant AMI patients, one to two random matching was done by their age and gender. Finally, 40+80 patients (74.5±11.2 years, 87 females) were enrolled. ECG at onset of both group was measured by automated system (ECAPs12c: Nihon-Koden).

Results

ST level of TTS at J-point in I/II/V4–6 lead was significantly elevated comparing to that of ant AMI. Conversely, Conversely, significant ST depression in aVR and no ST elevation in V1 of TTS was observed in TTS. Logistic regression analysis revealed that ST elevation in I lead and no ST elevation in V1 lead showed high odds ratio and low P value.

Conclusion

Automated measured ST level at J-point was a powerful tool to distinguish TTS and ant AMI at onset.

Funding Acknowledgement

Type of funding source: None

Diagnostic performance of 18-leads electrocardiography to distinguish takotsubo syndrome and acute anterior myocardial infarction

Background

Electrocardiographic (ECG) features on acute phase of Takotsubo syndrome (TTS) is recognized to mimic that of acute anterior myocardial infarction (ant AMI). However, the difference of synthesized 18-leads ECG of both diseases was not elucidated.

Purpose

To elucidate diagnostic performance of 18-leads ECG to distinguish TTS and acute anterior AMI.

Methods

We firstly enrolled consecutive 40 patients of TTS, and among 500 ant AMI patients, one to two matching was done by their age and gender. Finally, 40+80 patients (74.5±11.2 years, 87 females) were enrolled, and ECG at onset of both group was estimated. Because of multicollinearity, all significant differences were compared by machine learning (Random Forest method).

Results

Prevalence of Q wave had no difference. Conversely, ST depression in TTS and ST elevation in ant AMI were significant differences in V7–9 leads. T-wave polarity of V3R-V9 leads were significantly different (flat T-wave in TTS and positive in ant AMI). Machine learning revealed T wave polarity in V7 lead had the highest feature importance.

Conclusion

18-leads ECG at onset had powerful diagnostic performance to distinguish the two diseases.

Funding Acknowledgement

Type of funding source: None

P5643Simple 12-leads electrocardiography can predict cardiac death in patients with complete left bundle branch block

Background

Patients with complete left bundle branch block (CLBBB) generally fall in two categories: CLBBB with good prognosis and poor prognosis. However, a simple electrocardiography (ECG) was considered impossible to predict the two categories.

Purpose

To elucidate the possibility of 12-leads ECG for predicting cardiac prognosis in patients with CLBBB

Methods

To estimate myocardial damage and left ventricular function, the ECG was performed with semiconductor SPECT simultaneously. Among consecutive 5864 patients who underwent ECG gated SPECT, finally 103 sinus-rhythm patients were enrolled. The observed period of them was median 632 days, and primary endpoint was set as cardiac death.

Results

Eight patients fell into cardiac death. Cox univariate analysis showed ventricular activation time (VAT: duration from onset of Q wave to peak of R wave) in V1 lead, T wave amplitude in aVR (aVR T-amp), and multiple fragmented QRS (At least 2 fQRS in LV anterior/inferior/lateral wall), and left ventricular ejection fraction, standard deviation of phase analysis (Phase SD), and summed rest score were significant predictors. After optimization of all significant continuous predictors by ROC curve analysis, all the significant predictors were analyzed by multivariate Cox analysis (stepwise regression). VAT in V1 (Hazard ratio: 4.594, P=0.034), aVR T-amp ≥-85microV (HR: 11.11, P=0.029), and Phase SD≥48.7 (HR6.047, P=0.035) were independent predictors. Kaplan-Meyer curve analysis demonstrated VAT V1≥70 and aVR T amp≥-85 showed the worst prognosis (P=0.008).

Cox Regression after Optimization by ROC Univariate Multivariate (Stepwise regression) HR 95% CI P HR 95% CI P VAT I ≥70 6.861 1.759–26.76 0.006 4.594 1.126–18.75 0.034 T amp in aVR ≥−85 27.34 3.458–216.2 0.002 11.11 1.274–96.85 0.029 Multiple fQRS 3.836 1.081–13.61 0.037 LVEF ≤37% 7.250 1.874–28.04 0.004 SD ≥48.7 17.30 3.671–81.57 <0.001 6.047 1.133–32.28 0.035 SRS≥17 4.178 1.206–14.48 0.024 SD: standard deviation of histogram by phase analysis of SPECT; SRS: summed rest score by myocardial perfusion analysis of SPECT.

Conclusion

Simple 12-leads ECG could predict the prognosis of patients with CLBBB.

Looking back on media reports on the nuclear accident

The accident at Fukushima Daiichi nuclear power plant in the wake of the Great East Japan Earthquake received considerable media coverage. However, a leaning towards sensationalism and a proclivity for denouncing those in power resulted in articles that were, in several instances, scientifically inaccurate, causing anxiety among disaster victims and delaying recovery efforts. Individuals working for the local media in Fukushima had the task of reporting the disaster while being victims of the disaster at the same time. Therefore, many individuals studied and deepened their knowledge about radiation and its effects, and were pained to see inaccurate media coverage of the disaster. Should they have been more forthright in opposing such false media coverage?

Living-donor liver transplantation in 126 patients with biliary atresia: single-center experience

OBJECTIVES

To describe our experience with 126 consecutive living-donor liver transplantation (LDLT) procedures performed because of biliary atresia and to evaluate the optimal timing of the operation.

PATIENTS AND METHODS

Between May 2001 and January 2010,126 patients with biliary atresia underwent 130 LDLT procedures. Mean (SD) patient age was 3.3 (4.2) years, and body weight was 13.8 (10.7) kg. Donors included 64 fathers, 63 mothers, and 3 other individuals. The left lateral segment was the most commonly used graft (75%). Patients were divided into 3 groups according to body weight: group 1, less than 8 kg (n = 40); group 2,8 to 20 kg (n = 63); and group 3, more than 20 kg (n = 23). Medical records were reviewed retrospectively. Follow up was 4.5 (2.7) years.

RESULTS

All group 3 donors underwent left lobectomy, and all group 1 donors underwent left lateral segmentectomy. No donors required a second operation or died. Comparison of the 3 groups demonstrated that recipient Pediatric End-Stage Liver Disease score in group 1 was highest, operative blood loss in group 2 was lowest (78 mL/kg), and operative time in group 3 was longest (1201 minutes). Hepatic artery complications occurred more frequently in group 1 (17.9%), and biliary stenosis (43.5%) and gastrointestinal perforation (8.7%) occurred more frequently in group 3. The overall patient survival rates at 1, 5, and 9 years was 98%, 97%, and 97%, respectively. Five-year patient survival rate in groups 1,2, and 3 were 92.5%, 100%, and 95.7%, respectively. Gastrointestinal perforation (n = 2) was the primary cause of death.

CONCLUSIONS

Living-donor liver transplantation is an effective treatment of biliary atresia, with good long-term outcome. It seems that the most suitable time to perform LDLT to treat biliary atresia is when the patient weighs 8 to 20 kg.

Current-voltage characteristics of high resistivity CdTe

Current-voltage characteristics of high resistivity CdTe, with consideration to Schottky barrier height at the contact and defect levels in the band gap were investigated by experimental and numerical simulation methods. From the electron injection investigation, the density of electron traps corresponded to the doped Cl concentration in the crystal. Numerical simulation of current-voltage characteristics was made based on Schockley Read Hall (SRH) statistics. In the low bias region, calculated characteristics were in fairly close agreement with the experimental results for Pt/CdTe/Pt diode. The electric field was not uniform along the biased direction and an almost neutral region was present in the vicinity of anode contact even when the bias was applied.

Genetically engineered mutant of the cyanobacterium Synechococcus PCC 7942 defective in nitrate transport

Nitrate-grown cells of Synechococcus PCC 7942 (Anacystis nidulans R2) contain a 45-kDa protein as a major protein in the cytoplasmic membrane but ammonium-grown cells lack it. A mutant (M45) was constructed by inactivating the gene encoding the 45-kDa protein. M45 did not grow under low concentrations of nitrate but high concentrations of nitrate could support its growth, with the optimal concentration being 40-70 mM. The growth rate of M45 was as high as that of the wild-type cells when ammonium was the nitrogen source. The 45-kDa protein was absent in M45 irrespective of the growth conditions. The activities of nitrate and nitrite reductases were higher in M45 than in wild type. The rate of nitrate-dependent O(2) evolution in wild type measured in the presence of L-methionine D,L-sulfoximine and D,L-glyceraldehyde showed saturation kinetics with respect to nitrate concentration in the external medium. The nitrate concentration required to produce half the maximal rate was 1 muM. In M45, the rate of nitrate-dependent O(2) evolution was nearly zero at nitrate concentrations <1 mM and was linearly increased as the concentration increased. The presumed absence of nitrate transport in M45 demonstrated by these results suggested that the 45-kDa protein is a nitrate transporter.

Quantitative analysis of propionibacterial DNA in bronchoalveolar lavage cells from patients with sarcoidosis

BACKGROUND AND AIM OF THE WORK

The causes of sarcoidosis are still unknown. Propionibacterial subspieces are thought to be one of the most likely sources of antigens. Here we attempted to measure the amount of propionibacterial DNA in bronchoalveolar lavage (BAL) cell samples from patients with sarcoidosis and other pulmonary diseases.

METHODS

We examined BAL cells from 42 patients with sarcoidosis and 30 controls. Using quantitative polymerase chain reaction (PCR) for 16S rRNA of Propionibacterium acnes (P. acnes) and Propionibacterium granulosum (P. granulosum), we measured the amount of propionibacterial DNA in 500 ng of total DNA extracted from BAL cells from patients with sarcoidosis or other lung diseases. The correlation between clinical findings and the results of quantitative PCR were analyzed.

RESULTS

The mean level of P. acnes DNA from patients with sarcoidosis was 59.9 genomes per 500 ng of total DNA, which was significantly higher than that in controls (20.7 genomes, p<0.000l). The mean level of P. granulosum DNA from patients with sarcoidosis was 1.2 genomes, which was similar to that in controls (1.0 +/-1.6 genomes, p=0.52). The number of genomes of P. acnes in BAL cells was correlated with the serum angiotensin-converting enzyme (ACE) level and the percentage of macrophages in BAL fluid from patients with sarcoidosis.

CONCLUSIONS

The amount of P. acnes DNA in BAL cells from patients with sarcoidosis was significantly higher than that in BAL cells from patients with other pulmonary diseases. P. acnes may be involved in the pathogenesis of sarcoidosis.

Molecular epidemiology of Mycobacterium tuberculosis in an urban area in Japan, 2002-2006

SETTING

Shinjuku City, Tokyo, Japan.

OBJECTIVE

To evaluate the status of transmission of Mycobacterium tuberculosis in Shinjuku City to allocate resources efficiently and effectively for a successful tuberculosis (TB) control programme.

DESIGN

Observational descriptive study combining the genotype data of M. tuberculosis with TB patient profiles.

RESULTS

The genotype clustering rate was significantly higher in males (adjusted odds ratio [aOR] 1.94, 95%CI 1.04-3.65, P = 0.038), patients aged <40 years (aOR 2.09, 95%CI 1.17-3.71, P = 0.012) and the homeless (aOR 2.72, 95%CI 1.42-5.20, P = 0.002), and was lower for the foreign-born (aOR 0.21, 95%CI 0.06-0.76, P = 0.017). Among 45 genotype clusters containing 152 TB patients, 26 clusters containing 102 patients (67.1%) were composed of a mix of homeless and non-homeless patients. One of the mixed clusters included an 8-month-old infant born in Japan.

CONCLUSION

The study revealed that M. tuberculosis transmission occurred more frequently among the homeless than in non-homeless persons. However, transmission by casual contact between the homeless and the general population was also shown to occur.

Seasonality in various forms of tuberculosis

SETTING

Newly notified cases of tuberculosis (TB) for 5 years (1998 and 2000-2003) in Japan.

OBJECTIVE

To study the seasonality of notification for various forms of TB.

DESIGN

Descriptive analyses of newly notified cases by month of the year. Seasonal variations were compared among various forms of TB.

RESULTS

In almost all the forms of TB examined, the numbers of newly notified TB cases were the lowest from November to January. For childhood and pleural TB, the numbers of cases of TB were highest from March to May (spring) and from April to June (spring to early summer), respectively. For sputum smear-positive pulmonary tuberculosis (PTB) in the young, the number of cases was also highest from March to May. For lymph node TB (except mediastinal) and sputum smear-positive PTB in the elderly (aged > or =50 years), the numbers of cases were highest from May to July (late spring to summer) and from June to August (summer), respectively.

CONCLUSION

The seasonality of TB notification differs for the various forms of TB, which may reflect differences in the seasonality of clinical development of different types of TB disease such as primary, early and late post-primary TB.

Circadian function in patients with advanced non-small-cell lung cancer

This study aimed to evaluate whether patients with advanced non-small-cell lung cancer experience disrupted rest–activity daily rhythms, poor sleep quality, weakness, and maintain attributes that are linked to circadian function such as fatigue. This report describes the rest–activity patterns of 33 non-small-cell lung cancer patients who participated in a randomised clinical trial evaluating the benefits of melatonin. Data are reported on circadian function, health-related quality of life (QoL), subjective sleep quality, and anxiety/depression levels prior to randomisation and treatment. Actigraphy data, an objective measure of circadian function, demonstrated that patients' rest–activity circadian function differs significantly from control subjects. Our patients reported poor sleep quality and high levels of fatigue. Ferrans and Powers QoL Index instrument found a high level of dissatisfaction with health-related QoL. Data from the European Organization for Research and Treatment for Cancer reported poor capacity to fulfil the activities of daily living. Patients studied in the hospital during or near chemotherapy had significantly more abnormal circadian function than those studied in the ambulatory setting. Our data indicate that measurement of circadian sleep/activity dynamics should be accomplished in the outpatient/home setting for a minimum of 4–7 circadian cycles to assure that they are most representative of the patients' true condition. We conclude that the daily sleep/activity patterns of patients with advanced lung cancer are disturbed. These are accompanied by marked disruption of QoL and function. These data argue for investigating how much of this poor functioning and QoL are actually caused by this circadian disruption, and, whether behavioural, light-based, and or pharmacologic strategies to correct the circadian/sleep activity patterns can improve function and QoL.

Trends of delays in tuberculosis case finding in Japan and associated factors

SETTING

Nationwide tuberculosis (TB) registry in Japan, 1987-2002.

OBJECTIVE

To clarify the trends of patient's delay (PD), doctor's delay (DD) and total delay (TD), their relation and factors associated with the delays.

DESIGN

Longitudinal study on trends in delays. Among patients with symptomatic smear-positive pulmonary TB, those with long PD (> or =2 months), DD (> or =1 month) and TD (> or =3 months) were analysed.

RESULTS

Long PD rates increased until around 1997, whereas long DD rates decreased markedly from 1995 to 1999. Long TD rates increased until 1997, and decreased slightly thereafter. Men aged 30-59 years had higher rates of long PD, and the long PD rates increased through the 16-year observation period. Day labourers receiving or applying for welfare benefit had the highest rate of long TD, 46.5% during 1995-2002. Teachers and medical doctors showed the greatest increase in long TD rates through the period.

CONCLUSION

Long TD was influenced more by PD than DD, and showed an upward trend. However, the long TD rate has declined slightly owing to the recent reduction in long DD. The reduction in DD since 1995 occurred immediately after the introduction of new technology in bacteriological examinations.

Gene expression in the cyanobacterium Anabaena sp. PCC7120 under desiccation

The N2-fixing cyanobacterium Anabaena sp. PCC7120 showed an inherent capacity for desiccation tolerance. A DNA microarray covering almost the entire genome of Anabaena was used to determine the genome-wide gene expression under desiccation. RNA was extracted from cells at intervals starting from early to late desiccation. The pattern of gene expression in DNA fragments was categorized into seven types, which include four types of up-regulated and three types of down-regulated fragments. Validation of the data was carried out by RT-PCR on selected up-regulated DNA fragments and was consistent with the changes in mRNA levels. Our conclusions regarding desiccation tolerance for Anabaena sp. PCC7120 are as follows: (i) Genes for osmoprotectant metabolisms and the K+ transporting system are up-regulated from early to mid-desiccation; (ii) genes induced by osmotic, salt, and low-temperature stress are up-regulated under desiccation; (iii) genes for heat shock proteins are up-regulated after mid-desiccation; (iv) genes for photosynthesis and the nitrogen-transporting system are down-regulated during early desiccation; and (v) genes for RNA polymerase and ribosomal protein are down-regulated between the early and the middle phase of desiccation. Profiles of gene expression are discussed in relation to desiccation acclimation.