Biological nitrogen fixation in the long-term nitrogen-fertilized and unfertilized paddy fields, with special reference to diazotrophic iron-reducing bacteria.

Biological nitrogen fixation (BNF) is important to sustain nitrogen fertility of paddy soil and rice yield, while could be affected by nitrogen fertilization. Iron-reducing bacteria, Anaeromyxobacter and Geobacter, are newly found diazotrophic bacteria predominant in paddy soil. Experimental field of this study is a long-term (35 years) nitrogen fertilized (6.0 g N/m2/year) and unfertilized paddy field, where ca. 70% of rice yield was obtained yearly in nitrogen unfertilized plot (443 ± 37 g/m2) compared to fertilized plot (642 ± 64 g/m2). Effects of long-term nitrogen fertilization/unfertilization on soil properties related to BNF were investigated with special reference to diazotrophic iron-reducing bacteria. Soil chemical/biochemical properties, soil nitrogen-fixing activity, and community composition of diazotrophic bacteria were similar between nitrogen fertilized and unfertilized plot soils. In both plot soils, Anaeromyxobacter and Geobacter were the most predominant diazotrophs. Their nifD transcripts were detected at similar level, while those of other general diazotrophs were under detection limit. It was concluded that long-term use/unuse of nitrogen fertilizer in this field did not affect the predominance and nitrogen-fixing activity of diazotrophic iron-reducing bacteria, composition of other general diazotrophs, and the resulting soil nitrogen-fixing activity. BNF, primarily driven by diazotrophic iron-reducing bacteria, might significantly contribute to sustain soil nitrogen fertility and rice yield in both plot soils. Appropriate soil management to maintain BNF, including diazotrophic iron-reducing bacteria, will be important for sustainable soil nitrogen fertility and rice production.

Exercise echocardiography for a differential diagnosis in a patient with radiation-induced heart disease: A case report.

Advances in radiation therapy (RT) have dramatically improved the survival rates of patients with cancer, but radiation-induced heart disease (RIHD) has become an emerging problem, which is complex and multifaceted.A 65-year-old man with a medical history of chemoradiotherapy for esophageal cancer, who had multiple admissions for acute heart failure (AHF), was readmitted to our hospital. Transthoracic echocardiography at rest revealed left ventricular diastolic dysfunction, moderate aortic stenosis with mild aortic regurgitation, and mild mitral regurgitation (MR). A diagnosis of RIHD was obtained, however, the main cause of the AHF was not clearly understood. Exercise echocardiography (ExE) revealed an exacerbation of the MR and exercise-induced pulmonary hypertension (EIPH), and the severe dynamic MR was considered to be the main cause of the AHF. A transcatheter edge-to-edge repair (TEER) with a MitraClip (Abbott Vascular, Menlo Park, CA, USA) was performed, and the post-procedural ExE showed the mitigation of the dynamic MR and EIPH. He had no further heart failure admissions for more than one year.Our case showed that ExE may be useful in the management of patients with RIHD, and a TEER with a MitraClip may be an effective treatment for RT-related dynamic MR. Learning objective: Radiation therapy (RT) has improved the survival rates of patients with cancer, but which involves radiation-induced heart disease (RIHD). RIHD is complex and multifaceted, and RT-related valvular disease may be underestimated with transthoracic echocardiography at rest alone. Then exercise echocardiography may be useful in the management. It is important to perform an individualized approach including medical therapy, surgery, and percutaneous intervention by a heart team.

A Long-term Survival Case of Pulmonary Tumor Thrombotic Microangiopathy due to Gastric Cancer Confirmed by the Early Diagnosis based on a Transbronchial Lung Biopsy.

Pulmonary tumor thrombotic microangiopathy (PTTM) is an acute, progressive, and fatal disease. PTTM manifests as subacute respiratory failure with pulmonary hypertension, progressive right-sided heart failure, and sudden death. An antemortem diagnosis of PTTM is very difficult to obtain, and many patients die within several weeks. We herein report a case of PTTM diagnosed based on a transbronchial lung biopsy. In this case, we finally diagnosed PTTM due to gastric cancer because of its histological identity. The patient was administered chemotherapy, including angiogenesis inhibitors, against gastric cancer at an early age and survived for a long time.