The dose-related plateau effect of surviving fraction in normal tissue during the ultra-high-dose-rate radiotherapy.

Objective.Ultra-high-dose-rate radiotherapy, referred to as FLASH therapy, has been demonstrated to reduce the damage of normal tissue as well as inhibiting tumor growth compared with conventional dose-rate radiotherapy. The transient hypoxia may be a vital explanation for sparing the normal tissue. The heterogeneity of oxygen distribution for different doses and dose rates in the different radiotherapy schemes are analyzed. With these results, the influence of doses and dose rates on cell survival are evaluated in this work.Approach.The two-dimensional reaction-diffusion equations are used to describe the heterogeneity of the oxygen distribution in capillaries and tissue. A modified linear quadratic model is employed to characterize the surviving fraction at different doses and dose rates.Main results.The reduction of the damage to the normal tissue can be observed if the doses exceeds a minimum dose threshold under the ultra-high-dose-rate radiation. Also, the surviving fraction exhibits the 'plateau effect' under the ultra-high dose rates radiation, which signifies that within a specific range of doses, the surviving fraction either exhibits minimal variation or increases with the dose. For a given dose, the surviving fraction increases with the dose rate until tending to a stable value, which means that the protection in normal tissue reaches saturation.Significance.The emergence of the 'plateau effect' allows delivering the higher doses while minimizing damage to normal tissue. It is necessary to develop appropriate program of doses and dose rates for different irradiated tissue to achieve more efficient protection.

Effects of storage duration of suspended red blood cells before intraoperative infusion on coagulation indexes, routine blood examination and immune function in patients with gastrointestinal tumors.

Objective: To investigate the effect of storage duration of suspended red blood cells (SRBC) before intraoperative infusion on coagulation indexes, routine blood examination and immune function in patients with gastrointestinal (GI) tumors. Methods: We divided clinical data of one hundred patients with GI tumors who underwent surgical treatment in our hospital into two different groups according to the storage duration of SRBC use for intraoperative infusion. The short-term group (n=50) had patients with SRBC storage durations shorter than two weeks, and the long-term group (n=50) had patients with storage durations longer than two weeks. We compared the coagulation, immune function, routine blood profile, electrolyte levels and adverse reactions assessment results between the two groups. Results: Compared with before transfusions, the levels of fibrinogen (FIB) and activated partial prothrombin time (APTT) after blood transfusions were higher than those before transfusion (P<0.05). The levels of hemoglobin (Hb) and hematocrit (HCT) in the two groups after blood transfusions were also higher than those before transfusion (P<0.05). However, the levels of CD4+ decreased and those of CD8+ increased in both groups after the blood transfusions. In addition, the levels of CD4+ and CD4+/CD8+ in the short-term group were higher than those of the long-term group (P<0.05) while the CD8+ levels were lower than that of the long-term group (P<0.05). After the blood transfusions, the potassium ion (K+) levels in the two groups increased, and those in the long-term group were higher than in the short-term group (P<0.05). The sodium ion (Na+) levels in the two groups increased after the transfusions, and the short-term group had higher levels than the long-term group (P<0.05). Finally, the incidence of adverse reactions in the short-term group (4.00%) was lower than that in the long-term group (18.00%) (P<0.05). Conclusion: Intraoperative infusion of SRBC with storage duration longer than two weeks increases the risk of perioperative adverse transfusion reactions, which implies that the storage duration of SRBC should be strictly controlled in clinical practice to reduce the risk of blood transfusion.

[Analysis of erythroid-specific blood group genes using un-mobilized peripheral stem cells cultured in vitro].

OBJECTIVE: To analyze specific expression of blood group genes using nucleated erythroid cells cultured from un-mobilized peripheral stem cells in vitro. METHODS: Hematopoietic stem cells(HSC) bearing the CD34 antigen were isolated from peripheral blood by centrifugation and magnetic beads sorting, followed by suspension culture in vitro. Cells were collected from medium on various stages and analyzed by immunofluorescence. The RNA transcription of RH and ABO blood group genes was analyzed using culture cells on day 12. RESULTS: A total of(3.19±0.13) ×10 (4) CD34+cells were isolated from about 50 mL peripheral blood with a recovery rate of 67.3%±2.7%. The cells amount in erythroid-lineage culture system on day 9 reached a plateau of a 237.1±15.5-fold amplification of the initial cell input. The stem cell-specific CD34 antigen was dropped off, while the erythroid-specific CD235a and CD240D antigens were increased in culture period. RHD/CE and ABO genes can be amplified using RNA extracted from culture cells on day 12, and genotypes of Rh and ABO systems by DNA sequencing were consistent with their serologic phenotypes. CONCLUSION: A method was established to analyze the gene expression of erythroid blood group derived from un-mobilized peripheral stem cells cultured in vitro. It can be used to study the expression of various erythroid-specific genes.

[A rare p phenotype caused by a 26-bp deletion in α 1,4-galactosyltransferase gene].

OBJECTIVE: To delineate serological features and genetic basis for a rare p phenotype of P1Pk blood group system found in a Chinese individual. METHODS: Serological assaying was carried out for a proband with unexpected antibody found in his serum using specific antibodies and panel cells. Coding regions and flanking introns of α 1,4-galactosyltransferase gene (A4GALT) associated with the p phenotype were screened with polymerase chain reaction and DNA sequencing. RESULTS: A rare p phenotype of the P1Pk blood group system has been identified with red blood cells from the proband, whose serum contained anti-Tja antibody which can agglutinate and hemolyze with other common red blood cells. Other members of the proband's family were all normal with P1 or P2 phenotype. DNA sequencing has identified in the proband a homozygous 26 bp deletion at position 972 to 997 of the A4GALT gene. The deletion has caused a shift of the reading frame, resulting in a variant polypeptide chain with additional 83 amino acid residues compared with the wild-type protein. Other family members were either heterozygous for above deletion or non-deleted. CONCLUSION: A 26 bp deletion at position 972 to 997 of the A4GALT gene has been identified in a Chinese individual with p phenotype.