Biology subjects

Ida, H.

Publications and source records attributed to Ida, H..

3 recordsLinked to original sources

bioRxiv2024

An allometric study of the contribution of prostrate stems to belowground development of juvenile Fagus crenata

Prostrate stems represent an important morphological component of Fagus crenata (Siebolds beech). This unique stem-bending growth strategy has led to the dominance of this tree species in regions with heavy snowfall along the Sea of Japan. We investigated the early-stage aboveground-belowground dynamics of F. crenata by applying allometric scaling theory to analyze morphological development in saplings (aged 3-20 years). Samples were collected from 25 trees in three forests in Nagano, central Japan. The scaling exponent (b) demonstrated an increase in the fraction of aboveground biomass (i.e., dry mass) in relation to the overall surface area (aboveground, b = 0.748; belowground, b = 0.626) and biomass (aboveground, b = 1.087; belowground, b = 0.983). These values are highly consistent with recent field observations by other researchers. Aboveground biomass growth was supported by the increasing role of prostrate stems in belowground development (b = 1.114). Despite its extension belowground, the growth properties of the prostrate stem may be identical to those of shoots, as both are directly influenced by nutrient sources above the germination point. Our findings highlight the significance of the prostrate stem in supporting beech survival in areas with heavy snowfall.

ecology↗

bioRxiv2022

DOTA chelation through click chemistry enables favorable biodistribution of 89Zr-radiolabeled antibodies: A comparison with DFO chelation

Currently, the DFO chelator is commonly used to conjugate monoclonal antibodies (mAbs) and 89Zr, whereas the DOTA chelator is commonly used to conjugate mAbs and alpha- and beta-emitting metal radionuclides. However, if the degradation of [89Zr]Zr-DFO-mAb is not negligible, the in vivo biodistribution of 89Zr might not reflect that of metal radionuclides conjugated with DOTA-mAb. We hypothesized that [89Zr]Zr-DOTA-mAb as a new imaging counterpart would accurately predict the biodistribution of therapeutic metal radionuclides delivered by DOTA-mAb. In this study, we prepared [89Zr]Zr-DOTA-trastuzumab for the first time by a two-step reaction using click chemistry and then investigated the differences in biodistribution profiles between two chelating approaches for 89Zr. MethodsWe prepared [89Zr]Zr-DOTA-trastuzumab from DOTA-tetrazine conjugates (DOTA-Tz) and transcyclooctene-trastuzumab conjugates (TCO-trastuzumab). We first radiolabeled DOTA-Tz with 89Zr in a reaction solution of MeOH and HEPES buffer and then used a click reaction to obtain [89Zr]Zr-DOTA-Tz/TCO-trastuzumab. We performed biodistribution studies and PET imaging with [89Zr]Zr-DOTA-trastuzumab in a mouse model of HER2-positive ovarian cancer, SKOV3 xenograft mice at 24, 72, and 144 hours post-injection and compared these data with those of [89Zr]Zr-DFO-trastuzumab. ResultsTCO-trastuzumab was radiolabeled with [89Zr]Zr-DOTA-Tz in the two-step reaction in good radiochemical yield (57.8 {+/-} 17.6%). HER2-positive tumors were clearly visualized with [89Zr]Zr-DOTA-trastuzumab in PET imaging studies. The temporal profile changes of 89Zr radioactivity in SKOV3 tumors and bone marrow were sufficiently different between [89Zr]Zr-DOTA-trastuzumab and [89Zr]Zr-DFO-trastuzumab (P < 0.05). Conclusion: [89Zr]Zr-DOTA-trastuzumab can be produced by the two-step radiolabeling reaction based on the Tz/TCO click reaction. Presumably, 89Zr released from DFO is not negligible. In contrast, [89Zr]Zr-DOTA-mAb would better predict the biodistribution of [177Lu]Lu- or [225Ac]Ac-DOTA-mAb than [89Zr]Zr-DFO-mAb, thus avoiding the use of different chelator for 89Zr at the expense of the click chemistry step. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/507067v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@d7256borg.highwire.dtl.DTLVardef@d9d3d5org.highwire.dtl.DTLVardef@e24d97org.highwire.dtl.DTLVardef@1541bf0_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

Radiolabeling of PSMA-617 with 89Zr: A Novel Use of DMSO for Radiochemical Yield Enhancement and Preliminary Small-Animal PET Results

IntroductionProstate-specific membrane antigen (PSMA)-targeted ligands, including PSMA-617, have been developed for theranostics of prostate cancer. 68Ga-PSMA-617 is the de facto standard of PSMA Positron Emission Tomography (PET) for imaging in prostate cancer patients prior to radioligand therapy (RLT) with 177Lu-PSMA-617. The dose-limiting toxicity for PSMA-RLT is damage to the kidney. PET scans using 68Ga-PSMA-617 have to be performed within a few hours of injection due to its short half-life (68 min). However, the presence of radioactivity in urine at the PET imaging timepoint hampers the dose optimization of 177Lu (half-life 6.6 d)-labeled PSMA-617. Thus, the long-lived positron emitter 89Zr (half-life 3.3 d) is suited for optimizing the doses of 177Lu-PSMA-617 because PET scans can be performed after excretion of radioactive urine. Although 89Zr has great potential for PET imaging, its inadequate incorporation into 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), limits its applications. Here, we report the radiolabeling of PSMA-617 with 89Zr and preliminary PET imaging studies using 89Zr-PSMA-617. MethodsDMSO and HEPES buffer were used to label PSMA-617 with 89Zr. The dissociation constant (Kd) of 89Zr-PSMA-617 was determined using a cell-binding assay. Delayed-PET scans using 89Zr-PSMA-617 were performed at 24 h (N = 5). Results89Zr-PSMA-617 was prepared with a radiochemical yield of 70 {+/-} 9%. The Kd value was 6.8 nM. In PET imaging, standardized uptake value (SUV) was highest in LNCaP tumors (SUVmax = 0.98 {+/-} 0.32), whereas it was low in kidney (SUVmax = 0.18 {+/-} 0.7). ConclusionThe preparation of 89Zr-PSMA-617 was achieved by using the DMSO and HEPES buffer. 89Zr-PSMA-617 visualize the PSMA positive LNCaP tumors without accumulation in bladder. Advances in knowledge and implications for patient careThe use of 89Zr-PSMA-617 to predict the radiation doses in normal tissues lead to safe and effective RLT with 177Lu-PSMA-617.

cancer biology↗