ObjectiveAt present, the most commonly used photosensitizers in photodynamic therapy are still chemical photosensitizers, such as porphyrin and methylene blue, in order to specifically target cellular tissues, and thus poison cells, chemical photosensitizers need to use antibody conjugation or a transgenically encoded tag with affinity for the modified photosensitizing ligand, e.g. FlAsH, ReAsh or Halo Tag. Gene-encoded photosensitizers can directly poison cells by targeting specific cell compartments or organelles. However, currently developed gene-encoded photosensitizers have low reactive oxygen species production and low cytotoxicity, so it is necessary to continue to develop and obtain photosensitizers with higher reactive oxygen species production for the treatment of microbial infections and tumors. MethodsIn this study, we developed a photosensitizer LovPSO2 based on the light-oxygen-voltage (LOV) structural domain of phototropin-1B-like from Oryza sativa japonica. LovPSO2 was expressed in E. coli BL21(DE3) and purified to obtain protein samples, the purified protein samples were added 3 µmol/L singlet oxygen probe of SOSG and 5 µmol/L superoxide anion probe of DHE after fixed to A₄₄₅=0.063±0.003, respectively, then measured every 2 min of singlet oxygen production for 10 min and every 1 min of superoxide anion production for 5 min under blue light irradiation at 445 nm, 70 µmol·m^-2·s^-1. ResultsThe results showed that LovPSO2 could produce a large amount of singlet oxygen under blue light irradiation at 445 nm, 70 µmol·m^-2·s^-1, and its singlet oxygen quantum yield was 0.61, but its superoxide anion yield was low, so in order to improve the superoxide anion yield of LovPSO2, a mutant with a relatively high superoxide anion yield was obtained by further development and design on its basis LovPRO2. The stability of proteins is crucial for research in drug development and drug delivery, among others. Temperature and light are the key factors affecting the production of reactive oxygen species (ROS) by photosensitive proteins and their stability, while the temperature in cell culture and mammals in vivo is about 37°C, and the temperature inside tumor cells is about 42-45°C. Therefore, we further analyzed the photostability of miniSOG, SOPP3, LovPSO2, and LovPRO2 and their thermostability at 37℃ and 45℃. The analysis of proteins thermostability showed that LovPSO2 and LovPRO2 had better thermostability at 37℃ and 45℃, respectively. Analysis of the photostability of the proteins showed that LovPRO2 had better photostability. In addition, to further determine the phototoxic effects of photosensitizers, LovPSO2 and LovPRO2 were expressed in E. coli BL21(DE3) and HeLa cells, respectively. The results showed that LovPSO2 and LovPRO2 had better phototoxicity to E. coli BL21(DE3) under blue light irradiation, and the cellular phototoxicity lethality was as high as 90% after 30 min of continuous light irradiation, but the phototoxicity was weaker in HeLa cells. The reason for this result may be that the intracellular environment exacerbated the photobleaching of FMN encapsulated by LovPSO2 and LovPRO2, respectively, which attenuated the damage of reactive oxygen species to animal cellular tissues, limiting its use as a mechanistic tool to study oxidative stress. ConclusionLovPSO2 and LovPRO2 can be used as antibacterial photosensitizers, which have broader application prospects in the food and medical fields.

This study aims to investigate the molecular mechanism by which naringin alleviates cerebral ischemia/reperfusion(CI/R) injury through DRP1/LRRK2/MCU signaling axis. A total of 60 SD rats were randomly divided into the sham group, the model group, the sodium Danshensu group, and low-, medium-, and high-dose(50, 100, and 200 mg·kg~(-1)) naringin groups, with 10 rats in each group. Except for the sham group, a transient middle cerebral artery occlusion/reperfusion(tMCAO/R) model was established in SD rats using the suture method. Longa 5-point scale was used to assess neurological deficits. 2,3,5-Triphenyl tetrazolium chloride(TTC) staining was used to detect the volume percentage of cerebral infarction in rats. Hematoxylin-eosin(HE) staining and Nissl staining were employed to assess neuronal structural alterations and the number of Nissl bodies in cortex, respectively. Western blot was used to determine the protein expression levels of B-cell lymphoma-2 gene(Bcl-2), Bcl-2-associated X protein(Bax), cleaved cysteine-aspartate protease-3(cleaved caspase-3), mitochondrial calcium uniporter(MCU), microtubule-associated protein 1 light chain 3(LC3), and P62. Mitochondrial structure and autophagy in cortical neurons were observed by transmission electron microscopy. Immunofluorescence assay was used to quantify the fluorescence intensities of MCU and mitochondrial calcium ion, as well as the co-localization of dynamin-related protein 1(DRP1) with leucine-rich repeat kinase 2(LRRK2) and translocase of outer mitochondrial membrane 20(TOMM20) with LC3 in cortical mitochondria. The results showed that compared with the model group, naringin significantly decreased the volume percentage of cerebral infarction and neurological deficit score in tMCAO/R rats, alleviated the structural damage and Nissl body loss of cortical neurons in tMCAO/R rats, inhibited autophagosomes in cortical neurons, and increased the average diameter of cortical mitochondria. The Western blot results showed that compared to the sham group, the model group exhibited increased levels of cleaved caspase-3, Bax, MCU, and the LC3Ⅱ/LC3Ⅰ ratio in the cortex and reduced protein levels of Bcl-2 and P62. However, naringin down-regulated the protein expression of cleaved caspase-3, Bax, MCU and the ratio of LC3Ⅱ/LC3Ⅰ ratio and up-regulated the expression of Bcl-2 and P62 proteins in cortical area. In addition, immunofluorescence analysis showed that compared with the model group, naringin and positive drug treatments significantly decreased the fluorescence intensities of MCU and mitochondrial calcium ion. Meanwhile, the co-localization of DRP1 with LRRK2 and TOMM20 with LC3 in cortical mitochondria was also decreased significantly after the intervention. These findings suggest that naringin can alleviate cortical neuronal damage in tMCAO/R rats by inhibiting DRP1/LRRK2/MCU-mediated mitochondrial fragmentation and the resultant excessive mitophagy.
Animals ; Rats, Sprague-Dawley ; Reperfusion Injury/genetics* ; Flavanones/administration & dosage* ; Rats ; Dynamins/genetics* ; Male ; Brain Ischemia/genetics* ; Protein Serine-Threonine Kinases/genetics* ; Signal Transduction/drug effects* ; Humans ; Drugs, Chinese Herbal/administration & dosage*

Antibody-drug conjugates (ADCs) are antitumor drugs composed of monoclonal antibodies and cytotoxic payload covalently coupled by a linker. Currently, 15 ADCs have been clinically approved worldwide. More than 100 clinical trials at different phases are underway to investigate the newly developed ADCs. ADCs represent one of the fastest growing classes of targeted antitumor drugs in oncology drug development. It takes advantage of the specific targeting of tumor-specific antigen by antibodies to deliver cytotoxic chemotherapeutic drugs precisely to tumor cells, thereby producing promising antitumor efficacy and favorable adverse effect profiles. However, emergence of drug resistance has severely hindered the clinical efficacy of ADCs. In this review, we introduce the structure and mechanism of ADCs, describe the development of ADCs, summarized the latest research about the mechanisms of ADC resistance, discussed the strategies to overcome ADCs resistance, and predicted biomarkers for treatment response to ADC, aiming to contribute to the development of ADCs in the future.

OBJECTIVE: To analyze the clinical characteristics of elderly patients with sepsis, identify the key factors affecting their clinical outcomes, construct a death risk assessment scale for elderly patients with sepsis, and evaluate its predictive value. METHODS: A retrospective case-control study was conducted. The clinical data of sepsis patients admitted to intensive care unit (ICU) of the First Affiliated Hospital of Wenzhou Medical University from September 2021 to September 2023 were collected, including basic information, clinical characteristics, and clinical outcomes. The patients were divided into non-elderly group (age ≥ 65 years old) and elderly group (age < 65 years old) based on age. Additionally, the elderly patients were divided into survival group and death group based on their 30-day survival status. The clinical characteristics of elderly patients with sepsis were analyzed. Univariate and multivariate Logistic regression analyses were used to screen the independent risk factors for 30-day death in elderly patients with sepsis, and the regression equation was constructed. The regression equation was simplified, and the death risk assessment scale was established. The predictive value of different scores for the prognosis of elderly patients with sepsis was compared. RESULTS: (1) A total of 833 patients with sepsis were finally enrolled, including 485 in the elderly group and 348 in the non-elderly group. Compared with the non-elderly group, the elderly group showed significantly lower counts of lymphocyte, T cell, CD8⁺ T cell, and the ratio of T cells and CD8⁺ T cells [lymphocyte count (×10⁹/L): 0.71 (0.43, 1.06) vs. 0.83 (0.53, 1.26), T cell count (cells/μL): 394.0 (216.0, 648.0) vs. 490.5 (270.5, 793.0), CD8⁺ T cell count (cells/μL): 126.0 (62.0, 223.5) vs. 180.0 (101.0, 312.0), T cell ratio: 0.60 (0.48, 0.70) vs. 0.64 (0.51, 0.75), CD8⁺ T cell ratio: 0.19 (0.13, 0.28) vs. 0.24 (0.16, 0.34), all P < 0.01], higher natural killer cell (NK cell) count, acute physiology and chronic health evaluation II (APACHE II) score, ratio of invasive mechanical ventilation (IMV) during hospitalization, and 30-day mortality [NK cell count (cells/μL): 112.0 (61.0, 187.5) vs. 95.0 (53.0, 151.0), APACHE II score: 16.00 (12.00, 21.00) vs. 13.00 (8.00, 17.00), IMV ratio: 40.6% (197/485) vs. 31.9% (111/348), 30-day mortality: 28.9% (140/485) vs. 19.5% (68/348), all P < 0.05], and longer length of ICU stay [days: 5.5 (3.0, 10.0) vs. 5.0 (3.0, 8.0), P < 0.05]. There were no statistically significant differences in the levels of inflammatory markers such as C-reactive protein (CRP), procalcitonin (PCT), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukins (IL-2, IL-4, IL-6, IL-10) between the two groups. (2) In 485 elderly patients with sepsis, 345 survived in 30 days, and 140 died with the 30-day mortality of 28.9%. Compared with the survival group, the patients in the death group were older, and had lower body mass index (BMI), white blood cell count (WBC), PCT, platelet count (PLT) and higher IL-6, IL-10, N-terminal pro-brain natriuretic peptide (NT-proBNP), total bilirubin (TBil), blood lactic acid (Lac), and ratio of in-hospital IMV and continuous renal replacement therapy (CRRT). Multivariate Logistic regression analysis indicated that BMI [odds ratio (OR) = 0.783, 95% confidence interval (95%CI) was 0.678-0.905, P = 0.001], IL-6 (OR = 1.073, 95%CI was 1.004-1.146, P = 0.036), TBil (OR = 1.009, 95%CI was 1.000-1.018, P = 0.045), Lac (OR = 1.211, 95%CI was 1.072-1.367, P = 0.002), and IMV during hospitalization (OR = 6.181, 95%CI was 2.214-17.256, P = 0.001) were independent risk factors for 30-day death in elderly patients with sepsis, and the regression equation was constructed (Logit P = 1.012-0.244×BMI+0.070×IL-6+0.009×TBil+0.190×Lac+1.822×IMV). The regression equation was simplified to construct a death risk assessment scale, namely BITLI score. Receiver operator characteristic curve (ROC curve) analysis showed that the area under the ROC curve (AUC) of BITLI score for predicting death risk was 0.852 (95%CI was 0.769-0.935), and it was higher than APACHE II score (AUC = 0.714, 95%CI was 0.623-0.805) and sequential organ failure assessment (SOFA) score (AUC = 0.685, 95%CI was 0.578-0.793). The determined cut-off value of BITLI score was 1.50, while achieving a sensitivity of 83.3% and specificity of 74.0%. CONCLUSIONS Elderly patients with sepsis often have reduced lymphocyte counts, severe conditions, and poor prognosis. BMI, IL-6, TBil, Lac, and IMV during hospitalization were independent risk factors for 30-day death in elderly patients with sepsis. The BITLI score constructed based above risk factors is more precise and reliable than traditional APACHE II and SOFA scores in predicting the outcomes of elderly patients with sepsis.
Humans ; Sepsis/mortality* ; Aged ; Retrospective Studies ; Risk Assessment ; Case-Control Studies ; Prognosis ; Male ; Female ; Intensive Care Units ; Risk Factors ; Aged, 80 and over ; Logistic Models ; Middle Aged

Objective To develop a predictive model for postoperative mortality risk in patients with acute aortic dissection(AAD)using the Extreme Gradient Boosting(XGBoost)algorithm combined with Shapley Additive Explanation(SHAP),and to establish a prediction website to serve as a diagnostic and therapeutic support platform for clinicians and patients.Methods A retrospective cohort study design was adopted.Data from 782 AAD patients who underwent surgical treatment at the Fourth Hospital of Hebei Medical University from January 2013 to December 2023 were collected,including basic information and initial serum biomarker test results.Patients were randomly divided into training and test sets at a 7:3 ratio.An external validation set consisting of 313 AAD patients admitted to the Second Hospital of Hebei Medical University from January 2020 to December 2023 was also established for further model validation.Variables were screened using LASSO regression,and an XGBoost machine learning model was constructed and interpreted using SHAP.The predictive performance of the model was evaluated using receiver operating characteristic(ROC)curve analysis.Using the Shiny package,the XGBoost model was deployed to shinyapps.io to create a prediction website for postoperative mortality risk in AAD patients.One patient was selected by simple random sampling from the test set and the external validation set respectively for the prediction example on the Shiny webpage.Results The XGBoost model demonstrated high predictive performance for postoperative mortality in AAD patients,with area under the ROC curve(AUC)values of 0.928(95%CI 0.901-0.956)in the training set,0.919(95%CI 0.891-0.949)in the test set,and 0.941(95%CI 0.915-0.967)in the external validation set.SHAP values indicated the following order of variable importance in the model(from highest to lowest):"lactate dehydrogenase""blood chlorine""multiple organ injury""carbon dioxide combining power""prothrombin time""α-hydroxybutyric acid""creatine kinase isoenzyme""Stanford classification""combined use of bedside blood purification""gender""acute kidney injury""gastrointestinal bleeding""brain injury"and"shock".A risk prediction website for adverse postoperative outcomes in AAD patients was developed using XGBoost-SHAP method(https://dun-dunxiaolu.shinyapps.io/document/)and validated with examples.One randomly selected patient from each of the test and external validation sets was applied:the predicted mortality risk value for patient 1(who died postoperatively)was 0.9539,and that for patient 2(who survived postoperatively)was 0.0206.Conclusions The XGBoost-SHAP model demonstrates high accuracy in predicting postoperative mortality risk for AAD patients.The online prediction tool established based on this model enhances the identification efficiency of high-risk postoperative mortality patients.

Objective:To investigate the impact of age,various hormonal levels,and biochemical markers on penile cavernous body vascular function in patients with erectile dysfunction(ED).Me-thods:A retrospective analysis of clinical data from male patients with ED who underwent color duplex Doppler ultrasonography(CDDU)and intracavernosal injection test(ICI)at the Reproductive Medicine Center of Peking University Third Hospital from January 2020 to August 2023.Data were managed and processed using SPSS 29.0,and a multivariable Logistic regression analysis was conducted.Results:A total of 700 ED patients were included,with 380 showing negative ICI results and 320 positive.In the study,84 patients had a peak systolic velocity(PSV)＜25 cm/s,while 616 had PSV ≥ 25 cm/s;202 patients had end-diastolic velocity(EDV)＞5 cm/s,and 498 had EDV ≤5 cm/s.264 patients had ab-normal PSV and/or EDV results,and 436 had normal results for both.Patients with vascular ED had sig-nificantly lower estrogen levels(t=-3.546,P＜0.001),lower testosterone levels(t=-2.089,P=0.037),and a higher rate of hyperglycemia(x2=12.772,P=0.002)compared with those with non-vascular ED.The patients with arterial ED were older(t=3.953,P＜0.001),had a higher rate of hyperglycemia(x2=9.518,P=0.009),and a higher estrogen/testosterone ratio(t=2.330,P=0.020)compared with those with non-arterial ED.The patients with mixed arteriovenous ED had higher age(t=3.567,P＜0.001),lower testosterone levels(t=-2.288,P=0.022),a higher rate of hyperglycemia(x2=12.877,P=0.002),and a larger estrogen/testosterone ratio(t=2.096,P=0.037)compared with those with normal findings.Multifactorial Logistic regression analysis indicated that higher levels of estrogen were a protective factor for vascular ED(OR=1.009,95％CI:1.004-1.014),and glucose 7.0 mmol/L was a risk factor(OR=0.381,95％CI:0.219-0.661).Older age was a risk factor for arte-rial ED(OR=0.960,95％CI:0.938-0.982).Additionally,older age(OR=0.976,95％CI:0.958-0.993)and glucose levels of 5.6-6.9 mmol/L(OR=0.591,95％CI:0.399-0.876)were also risk fac-tors for mixed arterio-venous ED.Conclusion:Hyperglycemia and aging may impair penile cavernous body vascular function,while higher levels of estrogen may have a protective effect on it.

OBJECTIVE To study the effects of Phellodendron amurense polysaccharides （PAP） on improving gouty nephropathy （GN） in rats， and to investigate its mechanism primarily by interfering the p38 mitogen-activated protein kinase （p38 MAPK）/nuclear factor-κB（NF-κB）/tumor necrosis factor-α（TNF-α）. METHODS Sixty rats were randomly divided into normal group （water）， model group （water）， allopurinol group （positive control， 20 mg/kg）， PAP high-dose， medium-dose and low-dose groups （100， 50， 25 mg/kg， by raw material） after being stratified by body weight， with 10 rats in each group. Except for the normal group， the other groups were induced to construct GN model by giving 1 500 mg/kg potassium oxazinate and 100 mg/kg adenine intragastrically for 14 days. After modeling， the rats in each group were given relevant medicine/water intragastrically， once a day， for consecutive 28 days. After the last medication， the levels of biochemical parameters related to renal function [uric acid， creatinine （Cr）， blood urea nitrogen （BUN）， xanthine oxidase （XOD）] were detected in rats， and the histopathological changes in the rat kidney were observed. The protein expressions of monocyte chemoattractant protein-1（MCP-1），TNF-α and interleukin-6（IL-6） as well as the phosphorylation levels of p38 MAPK and NF-κB p65 protein were determined in renal tissue of rats. RESULTS Compared with the normal group， the model group suffered from the dilatation of renal tubules， structural damage to glomeruli， accompanied by inflammatory infiltration and fibrosis； the contents of uric acid， Cr， BUN and XOD， the protein expressions of MCP-1，TNF-α and IL-6 and the phosphorylation levels of p38 MAPK and NF-κB p65 protein were all increased significantly （P＜0.05 or P＜0.01）. Compared with the model group， the pathological symptoms of renal tissue in rats had been improved to varying degrees in different dose groups of PAP； the contents of uric acid， Cr， BUN and XOD， protein expressions of MCP-1， TNF-α and IL-6， the phosphorylation levels of p38 MAPK and NF-κB p65 protein in PAP high-dose and PAP medium-dose groups were all decreased significantly （P＜0.05 or P＜0.01）. CONCLUSIONS PAP exhibits an anti-GN effect， the mechanism of which may be associated with inhibiting the p38 MAPK/NF-κB/TNF-α signaling pathway.

ObjectiveTo explore the therapeutic mechanism of Faeces Bombycis on diabetic gastroparesis （DGP） rats based on phosphatidylinositol 3-kinase/protein kinase B/mammalian rapamycin target protein （PI3K/Akt/mTOR） signaling pathway. MethodDGP rat model was prepared by random selection of 15 out of 105 rats as blank group. The rats successfully constructed were randomly divided into model group， high-，medium- and low- dose groups （3.2， 1.6， 0.8 g·kg^-1） and moxapride group （1.5 mg·kg^-1）， with 12 rats in each group， and were given gavage for 4 weeks. The gastric emptying rate and random blood glucose were measured. The morphological changes of gastric antrum were observed by hematoxylin-eosin （HE） staining， and the expression of the c-Kit gene was analyzed by immunohistochemistry. The apoptosis of Cajal interstitial cells was observed by in situ end labeling （TUNEL） staining， and the protein expressions of PI3K， phosphorylation（p）-PI3K， Akt， p-Akt， mTOR， and p-mTOR were detected by Western blot. ResultCompared with the blank group， the gastric emptying rate of the model group decreased significantly （P<0.01）， and the glandular structure of the gastric antrum was destroyed. The expression of c-Kit decreased （P<0.01）， and the apoptosis of Cajal interstitial cells （ICC） increased. Compared with the model group， the gastric emptying rate in the high， middle， and low-dose groups of Faeces Bombycis extract and mosapride group increased significantly （P<0.01）. The glandular structure of the gastric antrum became closer， and the apoptosis of ICC decreased. The expression of c-Kit in the high dose group of Faeces Bombycis extract increased significantly. After Western blot testing， compared with the blank group， the protein expression of p-Akt/Akt， p-PI3K/PI3K， and p-mTOR/mTOR in the model group increased. Compared with the model group， the protein expression of p-Akt/Akt in the high dose group of Faeces Bombycis extract decreased （P<0.01）， and the protein expression of p-PI3K/PI3K decreased in the middle and low dose groups of Faeces Bombycis extract and mosapride group decreased （P<0.05， P<0.01）. The protein expression of p-mTOR/mTOR decreased in the low dose group of Faeces Bombycis extract （P<0.05）. In terms of random blood glucose， compared with the blank group， the random blood glucose in the model group increased significantly （P<0.01）， and compared with the model group， the random blood glucose in the high and middle dose groups of Faeces Bombycis extract decreased significantly （P<0.05）. Compared with mosapride group， the protein expression of p-Akt/Akt decreased in the high dose group of Faeces Bombycis extract （P<0.05）， and the protein expression of p-PI3K/PI3K increased in the high， middle， and low dose groups of Faeces Bombycis extract （P<0.05， P<0.01）. ConclusionFaeces Bombycis extract can increase gastric emptying rate， reduce ICC apoptosis， and lower random blood glucose in DGP rats. The high dose group of Faeces Bombycis extract has a significant effect on inhibiting ICC apoptosis， and its mechanism may be related to the regulation of the PI3K/Akt/mTOR signaling pathway.

Patients with severe trauma require an extremely timely treatment and transfusion plays an irreplaceable role in the emergency treatment of such patients. An increasing number of evidence-based medicinal evidences and clinical practices suggest that patients with severe traumatic bleeding benefit from early transfusion of low-titer group O whole blood or hemostatic resuscitation with red blood cells, plasma and platelet of a balanced ratio. However, the current domestic mode of blood supply cannot fully meet the requirements of timely and effective blood transfusion for emergency treatment of patients with severe trauma in clinical practice. In order to solve the key problems in blood supply and blood transfusion strategies for emergency treatment of severe trauma, Branch of Clinical Transfusion Medicine of Chinese Medical Association, Group for Trauma Emergency Care and Multiple Injuries of Trauma Branch of Chinese Medical Association, Young Scholar Group of Disaster Medicine Branch of Chinese Medical Association organized domestic experts of blood transfusion medicine and trauma treatment to jointly formulate Chinese expert consensus on blood support mode and blood transfusion strategies for emergency treatment of severe trauma patients ( version 2024). Based on the evidence-based medical evidence and Delphi method of expert consultation and voting, 10 recommendations were put forward from two aspects of blood support mode and transfusion strategies, aiming to provide a reference for transfusion resuscitation in the emergency treatment of severe trauma and further improve the success rate of treatment of patients with severe trauma.

Objective To explore the impact of pH value of the reaction system on the properties of bovine hemoglobin modified with aldehydeated polyethylene glycol(PEG-bHb).Methods PEG-bHb conjugates were synthesized under varying pH conditions(6.0,6.5,7.4 and 8.0)of the reaction system while consistent molar ratios,temperature,and reaction time were maintained.The structural and functional attributes of PEG-bHb were characterized.Results The proportion of methemoglobin decreased with an increase in pH.In a weakly acidic reaction environment,the PEG-bHb was found to be relatively highly modified.At pH 6.5,the average number of PEG chains attached to the bHb surface was 6.86±0.38.Selective PEG modification of the N-terminal α-NH2 groups was more pronounced under weakly acidic conditions.Specifically,at pH 6.5,the modification efficiency of the N-terminal α-NH2 groups of bHb by aldehyde-activated PEG reached 95.4％for the α-chains and 99.3％for the β-chains.The PEG modification influenced the heme region microenvi-ronment of bHb,with minimal structural impact observed at pH 6.5.After modification,the oxygen affinity of PEG-bHb was enhanced,the Hill coefficient was reduced,and there were significant increases in colloid osmotic pressure,viscosity,and particle size,all of which differed markedly from the unmodified bHb group(P＜0.001).Conclusion The synthesis of PEG-bHb under weakly acidic conditions can result in a high degree of selective modification of the N-terminal α-NH2 groups and an overall high degree of modification.