The developmental pathway for human megakaryocytes remains unclear, and the definition of pure unipotent megakaryocyte progenitor is still controversial. Using single-cell transcriptome analysis, we have identified a cluster of cells within immature hematopoietic stem- and progenitor-cell populations that specifically expresses genes related to the megakaryocyte lineage. We used CD41 as a positive marker to identify these cells within the CD34CD38IL-3RαCD45RA common myeloid progenitor (CMP) population. These cells lacked erythroid and granulocyte-macrophage potential but exhibited robust differentiation into the megakaryocyte lineage at a high frequency, both in vivo and in vitro. The efficiency and expansion potential of these cells exceeded those of conventional bipotent megakaryocyte/erythrocyte progenitors. Accordingly, the CD41 CMP was defined as a unipotent megakaryocyte progenitor (MegP) that is likely to represent the major pathway for human megakaryopoiesis, independent of canonical megakaryocyte-erythroid lineage bifurcation. In the bone marrow of patients with essential thrombocythemia, the MegP population was significantly expanded in the context of a high burden of Janus kinase 2 mutations. Thus, the prospectively isolatable and functionally homogeneous human MegP will be useful for the elucidation of the mechanisms underlying normal and malignant human hematopoiesis.

Background/Aim: Early detection of gastrointestinal cancer may reduce mortality. Recently, Caenorhabditis elegans has been reported to be capable of differentiating patients with cancers from healthy persons by the smell of urine. This novel technique using C. elegans olfaction has been named as Nematode-NOSE (N-NOSE). Materials and Methods: We collected 180 urine samples from patients with gastrointestinal cancer and 76 samples from healthy subjects. N-NOSE test was performed using these samples and N-NOSE index was obtained. Quantification of the olfactory behavior of C. elegans was performed as established in past studies. By receiver operating characteristic (ROC) analysis, we examined the diagnostic capability of N-NOSE. Results: ROC analysis revealed that N-NOSE showed an area under the curve value of more than 0.80, even in early-stage cancers. Conclusion: C. elegans olfaction enabled the detection of gastrointestinal cancers from urine with high sensitivity, which can provide the basis for the development of N-NOSE as a gastrointestinal cancer screening test.

The technique used for cancer monitoring is essential for effective cancer therapy. Currently, several methods such as diagnostic imaging and biochemical markers have been used for cancer monitoring, but these are invasive and show low sensitivity. A previous study reported that Caenorhabditis elegans sensitively discriminated patients with cancer from healthy subjects, based on the smell of a urine sample. However, whether C. elegans olfaction can detect the removal of cancerous tumours remains unknown. This study was conducted to examine C. elegans olfactory behaviour to urine samples collected from 78 patients before and after surgery. The diagnostic ability of the technique termed Nematode-NOSE (N-NOSE) was evaluated by receiver operating characteristic (ROC) analysis. The ROC curve of N-NOSE was higher than those of classic tumour markers. Furthermore, we examined the change in C. elegans olfactory behaviour following exposure to preoperative and postoperative samples. The results suggest that a reduction in attraction indicates the removal of the cancerous tumour. This study may lead to the development of a noninvasive and highly sensitive tool for evaluating postoperative cancer patients.

The sensitivity of human gastric cancer tissue to 5-fluorouracil (5-FU) and its analogues l-(2-tetrahydrofuryl)-5-fluorouracil (FT), UFT and 1-hexylcarbamoyl-5-fluorouracil (HCFU) was determined, using the in vivo subrenal capsule (SRC) assay. The relative variation of tumor size (ΔTS/TS₀) was calculated as follows: ΔTS/TS₀ = (TS₆-TS₀/TS₀) x 100%, where TS₆ was the tumor size on day 6 and TS₀ on day 0. The chemosensitivity was considered to be positive when ΔTS/TS₀ in the treated group decreased to below -10%. For their cytotoxic effects, 5-FU analogues are converted to 5-FU and positive correlations were noted between the tumor sizes of 5-FU and its analogues (5-FU vs. FT, r = 0.737; 5-FU vs. UFT, r = 0.653; 5-FU vs. HCFU, r = 0.709), in gastric tissues from 22 patients. The means ± SD of tumor size were -8.5 ± 11.5% for 5-FU, -8.3 ± 16.0% for FT, -18.1 ± 15.8% for UFT and -13.7 ± 13.4% for HCFU. Decrease in tumor size was marked in case of exposure to UFT, compared with that to 5-FU (p < 0.001), FT (p < 0.001) and HCFU (p < 0.05). 18% were sensitive to UFT and resistant to 3 other drugs. Thus, UFT proved to be the most effective among 5-FU and its analogues for decreasing the size of gastric cancer tissues.

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