A red blood cell-derived bionic microrobot capable of hierarchically adapting to five critical stages in systemic drug delivery.

The tumour-targeting efficiency of systemically delivered chemodrugs largely dictates the therapeutic outcome of anticancer treatment. Major challenges lie in the complexity of diverse biological barriers that drug delivery systems must hierarchically overcome to reach their cellular/subcellular targets. Herein, an "all-in-one" red blood cell (RBC)-derived microrobot that can hierarchically adapt to five critical stages during systemic drug delivery, that is, circulation, accumulation, release, extravasation, and penetration, is developed. The microrobots behave like natural RBCs in blood circulation, due to their almost identical surface properties, but can be magnetically manipulated to accumulate at regions of interest such as tumours. Next, the microrobots are "immolated" under laser irradiation to release their therapeutic cargoes and, by generating heat, to enhance drug extravasation through vascular barriers. As a coloaded agent, pirfenidone (PFD) can inhibit the formation of extracellular matrix and increase the penetration depth of chemodrugs in the solid tumour. It is demonstrated that this system effectively suppresses both primary and metastatic tumours in mouse models without evident side effects, and may represent a new class of intelligent biomimicking robots for biomedical applications.

Hyperbaric oxygen enhances tumor penetration and accumulation of engineered bacteria for synergistic photothermal immunotherapy.

Bacteria-mediated cancer therapeutic strategies have attracted increasing interest due to their intrinsic tumor tropism. However, bacteria-based drugs face several challenges including the large size of bacteria and dense extracellular matrix, limiting their intratumoral delivery efficiency. In this study, we find that hyperbaric oxygen (HBO), a noninvasive therapeutic method, can effectively deplete the dense extracellular matrix and thus enhance the bacterial accumulation within tumors. Inspired by this finding, we modify Escherichia coli Nissle 1917 (EcN) with cypate molecules to yield EcN-cypate for photothermal therapy, which can subsequently induce immunogenic cell death (ICD). Importantly, HBO treatment significantly increases the intratumoral accumulation of EcN-cypate and facilitates the intratumoral infiltration of immune cells to realize desirable tumor eradication through photothermal therapy and ICD-induced immunotherapy. Our work provides a facile and noninvasive strategy to enhance the intratumoral delivery efficiency of natural/engineered bacteria, and may promote the clinical translation of bacteria-mediated synergistic cancer therapy.

A ferroptosis-reinforced nanocatalyst enhances chemodynamic therapy through dual H2O2 production and oxidative stress amplification.

The existence of a delicate redox balance in tumors usually leads to cancer treatment failure. Breaking redox homeostasis by amplifying oxidative stress and reducing glutathione (GSH) can accelerate cancer cell death. Herein, we construct a ferroptosis-reinforced nanocatalyst (denoted as HBGL) to amplify intracellular oxidative stress via dual H2O2 production-assisted chemodynamic therapy (CDT). Specifically, a long-circulating liposome is employed to deliver hemin (a natural iron-containing substrate for Fenton reaction and ferroptosis), ß-lapachone (a DNA topoisomerase inhibitor with H2O2 generation capacity for chemotherapy), and glucose oxidase (which can consume glucose for starvation therapy and generate H2O2). HBGL can achieve rapid, continuous, and massive H2O2 and •OH production and GSH depletion in cancer cells, resulting in increased intracellular oxidative stress. Additionally, hemin can reinforce the ferroptosis-inducing ability of HBGL, which is reflected in the downregulation of glutathione peroxidase-4 and the accumulation of lipid peroxide. Notably, HBGL can disrupt endo/lysosomes and impair mitochondrial function in cancer cells. HBGL exhibits effective tumor-killing ability without eliciting obvious side effects, indicating its clinical translation potential for synergistic starvation therapy, chemotherapy, ferroptosis therapy, and CDT. Overall, this nanocatalytic liposome may be a promising candidate for achieving potentiated cancer treatment.

Hydrogel-Based Growth Factor Delivery Platforms: Strategies and Recent Advances.

Growth factors play a crucial role in regulating a broad variety of biological processes and are regarded as powerful therapeutic agents in tissue engineering and regenerative medicine in the past decades. However, their application is limited by their short half-lives and potential side effects in physiological environments. Hydrogels are identified as having the promising potential to prolong the half-lives of growth factors and mitigate their adverse effects by restricting them within the matrix to reduce their rapid proteolysis, burst release, and unwanted diffusion. This review discusses recent progress in the development of growth factor-containing hydrogels for various biomedical applications, including wound healing, brain tissue repair, cartilage and bone regeneration, and spinal cord injury repair. In addition, the review introduces strategies for optimizing growth factor release including affinity-based delivery, carrier-assisted delivery, stimuli-responsive delivery, spatial structure-based delivery, and cellular system-based delivery. Finally, the review presents current limitations and future research directions for growth factor-delivering hydrogels.

Analysis on the status quo of the awareness rate of core knowledge of cancer prevention and treatment and its influencing factors among residents in Liaoning Province in 2021 / 中华预防医学杂志

Objective: To analyze the status quo of the knowledge and related factors of cancer prevention and treatment among residents in Liaoning Province in 2021. Methods: From August to November 2021, through network sampling method, 17 474 permanent residents aged 15-69 years in Liaoning Province were surveyed. The WeChat public account was used to collect information such as demographic characteristics and core knowledge of cancer prevention and treatment. The Chi-square test was used to compare the difference of the level of the cancer prevention and treatment knowledge among different groups. The multivariate logistic regression model was used to analyze the related factors. Results: Among the 17 474 subjects, 43.1% (7 528) were male and 58.7% (10 262) were urban residents. The overall awareness rate was 72.3%, and the awareness rate of cancer cognition, prevention, early diagnosis and treatment, cancer management and rehabilitation were 71.4%, 67.6%, 72.7%, 83.4% and 63.5%, respectively. The multivariate logistic regression model showed that the residents who were man (OR: 0.850, 95%CI: 0.781-0.925), in rural areas (OR: 0.753, 95%CI: 0.694-0.817), 55-59 years old (OR: 0.851, 95%CI: 0.751-0.963), quitters (OR: 0.721, 95%CI: 0.640-0.813) and smoker (OR: 0.724, 95%CI: 0.654-0.801) had lower awareness rates, while the residents who were 35-54 years old (OR: 1.312, 95%CI: 1.202-1.432), with an educational level of junior high school/senior high school/college degree or above (OR: 1.834-5.130, 95%CI: 1.575-6.047), technical personnel (OR: 1.592, 95%CI: 1.367-1.854), civil servant/institution staff (OR: 1.282, 95%CI: 1.094-1.503), enterprise/business/service staff (OR: 1.218, 95%CI: 1.071-1.385), retired (OR: 1.324, 95%CI: 1.114-1.573) and with family history of cancer (OR: 1.369, 95%CI: 1.266-1.481) had higher awareness rates. Conclusion: The level of the awareness of core knowledge of cancer prevention and treatment among residents in Liaoning Province has met the requirements of the Healthy China Action. Region, gender, education level, age, family history of cancer and smoking are relevant factors.

Repeated transcranial acupuncture combined with electroacupuncture for flat descending sudden deafness: a randomized controlled trial / 中国针灸

OBJECTIVE@#To observe the clinical effect of repeated transcranial acupuncture combined with electroacupuncture on flat descending sudden deafness.@*METHODS@#A total of 80 patients with flat descending sudden deafness were randomly divided into an acupuncture and medication group (39 cases, 1 case dropped off) and a western medication group (39 cases, 1 case dropped off). Patients in the western medication group were treated with glucocorticoid + batroxobin + ginkgo leaf preparation. On the basis of the western medication group, patients in the acupuncture and medication group were treated with acupuncture at Baihui (GV 20), Ningshen, Yunting area, Mastoid 1 point, Mastoid 2 point, Fengchi (GB 20), Gongxue, Tinghui (GB 2), etc., repeated transcranial acupuncture was applied at Baihui (GV 20), Ningshen and Yunting area; Mastoid 1 point and Mastoid 2 point, Fengchi (GB 20) and Gongxue of the affected side were connected to the electroacupuncture instrument, continuous wave, 2 Hz in frequency. The needle was retained for 30 min, once a day, and rest for 1 d after 6 d of continuous treatment. All patients were treated for 3 weeks. The average hearing threshold, tinnitus handicap inventory (THI) score, dizziness handicap inventory (DHI) score and speech discrimination test score were compared between the two groups before and after treatment, and the clinical effect was evaluated.@*RESULTS@#After treatment, the average hearing threshold, THI and DHI scores of the two groups were lower than those before treatment (P<0.05), and above indexes in the acupuncture and medication group were lower than those in the western medication group (P<0.05). The speech discrimination test scores of the two groups were higher than those before treatment (P<0.05), and the score in the acupuncture and medication group was higher than that in the western medication group (P<0.05). The total effective rate was 87.2% (34/39) in the acupuncture and medication group, which was higher than 74.4% (29/39) in the western medication group (P<0.05).@*CONCLUSION@#Repeated transcranial acupuncture combined with electroacupuncture can improve the hearing level of patients with flat descending sudden deafness, relieve tinnitus and vertigo symptoms.

Sulfur-Doped Organosilica Nanodots as a Universal Sensor for Ultrafast Live/Dead Cell Discrimination.

Rapid and accurate differentiation between live and dead cells is highly desirable for the evaluation of cell viability. Here, we report the application of the orange-emitting sulfur-doped organosilica nanodots (S-OSiNDs) for ultrafast (30 s), ultrasensitive (1 µg/mL), and universal staining of the dead bacterial, fungal, and mammalian cells but not the live ones, which satisfies the requirements of a fluorescent probe that can specifically stain the dead cells. We further verify that the fluorescence distribution range of S-OSiNDs (which are distributed in cytoplasm and nucleus) is much larger than that of the commercial dead/fixed cell/tissue staining dye RedDot2 (which is distributed in the nucleus) in terms of dead mammalian cell staining, indicating that S-OSiNDs possess a better staining effect of dead cells than RedDot2. Overall, S-OSiNDs can be used as a robust fluorescent probe for ultrafast and accurate discrimination between dead and live cells at a single cell level, which may find a variety of applications in the biomedical field.

New Proposals for Application of Terahertz Imaging Technique in Chinese Medicine / 中国结合医学杂志

The rapid development of terahertz technology promotes the realization of various terahertz imaging systems. Terahertz technology features terahertz waves as good non-invasive illumination sources due to their high spectral resolution, penetration and safety. The terahertz imaging technique (TIT) has gradually been extended from the biomedical field to the field of Chinese medicine (CM), and it has become a powerful tool for seeking scientific evidence for CM theories with the use of modern science and technology. This paper reviews the current application of TITs in the field of CM research, and most importantly offers novel proposals for the application of TITs in CM research from the perspective of CM syndrome objectification and acupuncture research and cites existing reports as reference to the feasibility of these new proposals.

Physalin B reduces Aβ secretion through down-regulation of BACE1 expression by activating FoxO1 and inhibiting STAT3 phosphorylation / 中国天然药物

Physalin B (PB), one of the major active steroidal constituents of Solanaceae Physalis plants, has a wide variety of biological activities. We found that PB significantly down-regulated β-amyloid (Aβ) secretion in N2a/APPsw cells. However, the underlying mechanisms are not well understood. In the current study, we investigated the changes in key enzymes involved in β-amyloid precursor protein (APP) metabolism and other APP metabolites by treating N2a/APPsw cells with PB at different concentrations. The results indicated that PB reduced Aβ secretion, which was caused by down-regulation of β-secretase (BACE1) expression, as indicated at both the protein and mRNA levels. Further research revealed that PB regulated BACE1 expression by inducing the activation of forkhead box O1 (FoxO1) and inhibiting the phosphorylation of signal transducer and activator of transcription 3 (STAT3). In addition, the effect of PB on BACE1 expression and Aβ secretion was reversed by treatment with FoxO1 siRNA and STAT3 antagonist S3I-201. In conclusion, these data demonstrated that PB can effectively down-regulate the expression of BACE1 to reduce Aβsecretion by activating the expression of FoxO1 and inhibiting the phosphorylation of STAT3.

Characteristics of orofacial operant test for orofacial pain sensitivity caused by occlusal interference in rats / 北京大学学报(医学版)

OBJECTIVE@#To compare the orofacial pain sensitivity with operant test and mechanical hyperalgesia with von Frey filaments of two orofacial pain models (EOI: experimental occlusal interference; pIONX: partial infraorbital nerve transection). To investigate the operant and evoked characteristics of EOI-rats.@*METHODS@#The orofacial operant behaviors were tested by Ugo Basile Orofacial Stimulation Test System. The mechanical thresholds of vibrissal pads were tested by von Frey filaments. Male Sprague-Dawley rats were randomly divided into eight groups: von Frey group: sham-EOI, EOI, sham-pIONX, pIONX (sham: sham-operated group); operant test group: sham-EOI, EOI, sham-pIONX, pIONX (sham: sham-operated group). The mechanical thresholds and orofacial operant behaviors were tested on pre-operation and post-operation days l, 3, 7, 10, 14 and 21.@*RESULTS@#In pIONX of von Frey group, the mechanical withdrawal threshold decreased from days 1 to 21 (P<0.05), peaking from days 7 to 10, and lasted until the end of the experiment. There was no significant difference between the bilateral sides. In pIONX of operant test group, the total contact time decreased from days 10 to 21 (P<0.05), peaking from days 10 to 14, and lasted until the end of the experiment. In EOI of von Frey group, the mechanical withdrawal threshold decreased from days 3 to 21 (P<0.05), peaking on day 7, and lasted until the end of the experiment. There was no significant difference between the bilateral sides. In EOI of operant test group, the total contact time decreased from days 1 to 21 (P<0.05), peaking from days 7 to 10, and lasting until the end of experiment.@*CONCLUSION@#Orofacial operant test is a stable method to evaluate orofacial pain behaviors, which could discriminate the feature of neuropathic and EOI orofacial pain. In these two animal models, both of the operant behaviors and the mechanical hyperalgesia exhibited different time courses. Orofacial operant test provides a novel method for evaluating the orofacial pain sensitivity and studying the orofacial pain mechanism thoroughly.

Correlation between intestinal flora imbalance and anastomotic leakage after operation for middle to low rectal cancer / 中国实用外科杂志

OBJECTIVE: To analyze the risk factors and relationship between intestinal flora imbalance and anastomotic leakage after laparoscopic rectal cancer lower anterior resection(LAR)in patients with middle-low rectal cancer.METHODS: Clinical data of 155 patients with mid to low rectal cancer who underwent laparoscopic lower anterior resection at Peking Union Medical College Hospital from November 2016 to April 2019 were retrospectively analyzed.Postoperative intestinal flora imbalance and anastomotic leakage were evaluated,and statistical results were gained.RESULTS: Of the 155 patients,34(21.9%)patients had postoperative intestinal flora imbalance. Twenty patients of anastomotic leakage after operation(12.9%)were discovered,and 18 patients(11.6%)had both anastomotic leakage and intestinal flora imbalance. Univariate and multivariate logic regression analysis showed that intestinal flora imbalance(χ~2=25.674,OR=90.398,P0.05).CONCLUSION: The early diagnosis of postoperative intestinal floraimbalance in rectal cancer patients depends more on clinical experience. Intestinal floraimbalance,the enlargement of tumor diameterare risk factors for anastomotic leakage,and protective enterostomy would reduce the incidence of anastomotic leakage.

Lycodine type alkaloids from Lycopodiastrum casuarinoides with cytotoxic and cholinesterase inhibitory activities.

A chemical investigation on the 70% EtOH extract of the aerial parts of Lycopodiastrum casuarinoides led to the isolation of six novel lycodine type alkaloids, lycocasuarines A-F (1-6). The structures of the isolated compounds were established based on 1D and 2D (1H1H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated alkaloids were tested in vitro for cytotoxic potentials against seven malignant melanoma cell lines as well as acetylcholinesterase (AChE) and butyrocholinesterase (BuChE) inhibitory activities. As a result, alkaloids 1 and 3 exhibited significant cytotoxic activities against all the tested tumor cell lines with IC50 values <10 µM and the inhibitory activities for AchE (0.94 ±â€¯0.15 and 0.24 ±â€¯0.03 µM, respectively) and BuchE (1.82 ±â€¯0.12 and 7.31 ±â€¯0.42 µM, respectively).

Hypoxia amplifies lipopolysaccharide-induced IL-1β expression in macrophages / 基础医学与临床

Objective To investigate the effect of hypoxia on the expression of IL-1βin macrophages.Methods RAW264.7 cells were treated with normoxia(21%O2),hypoxia(2%O2), normoxia(21%O2)plus LPS and hypoxia(2%O2)plus LPS.RT-qPCR was used to detect the mRNA expression of Vegf,Nlrp3 and Il1b.Western blot was used to detect the protein expression of HIF-1α,NLRP3,caspase-1,cleaved caspase-1,Pro-IL-1βand IL-1β.The peritoneal macrophages of Vhlfl/fl/Apoe-/-mice and VhlΔMac/Apoe-/-mice were treated with or without LPS.RT-qPCR was used to detect the mRNA expression of Vhl,Nlrp3,Il1b and Il6.Results Compared with nor-moxia, hypoxia significantly increased mRNA of Vegf, Nlrp3 and Il1b in RAW264.7(P<0.01).Hypoxia increased mRNA and protein of NLRP 3 and IL-1βin RAW264.7 induced with LPS comparing with normoxia(P<0.01).Hypoxia had no effects on the activation of caspase-1 and the subsequent maturation of Pro-IL-1βinduced with LPS in RAW264.7.Compared with Vhlfl/fl/Apoe-/-peritoneal macrophages,VhlΔMac/Apoe-/-peritoneal macro-phages showed significantly increased mRNA levels of Nlrp3,Il1b and Il6 induced with LPS(P<0.05).Conclu-sions Hypoxia amplifies lipopolysaccharide-induced IL-1βexpression in macrophages.

Rutin attenuates isoflurane-induced neuroapoptosis via modulating JNK and p38 MAPK pathways in the hippocampi of neonatal rats.

An increasing number of infants and children undergo surgery and are exposed to anesthesia as a part of medical care each year. Isoflurane is a commonly used anesthetic in the pediatric population. However, previous studies have reported widespread isoflurane-induced neuroapoptosis and cognitive impairments in neonatal animal models, raising concerns over the administration of isoflurane in the pediatric population. The current study investigated the effects of rutin, a flavonoid, on isoflurane-induced neuroapoptosis in a neonatal rodent model. Groups of neonatal rat pups were administered rutin at doses of 10, 20 or 40 mg/kg body weight from postnatal day 1 (P1) to P15. On P7, pups were exposed to 0.75% isoflurane for 6 h. Rat pups in the control groups did not receive rutin, and did not receive anesthesia in one group. Neuroapoptosis following isoflurane exposure was determined by TUNEL assay. The expression levels of cleaved caspase-3, apoptotic pathway proteins [Bcl2-associated agonist of cell death (Bad), phospho-Bad, Bax, B-cell lymphoma 2 (Bcl-2) and Bcl-xL and mitogen-activated protein kinases (MAPK)] signalling pathway proteins [c-Jun N-terminal kinase (JNK), phospho-JNK, extracellular-signal-regulated kinase 1/2 (ERK1/2), phosphoERK1/2, p38, phospho-p38 and phospho-c-Jun], were determined by western blot analysis. The Morris water maze test was used to assess the learning and memory of pups on P30 and P31. The present study found that rutin at the tested doses of 10, 20 and 40 mg significantly reduced (P<0.05) the isoflurane-induced elevation in apoptotic cell count. The expression levels of caspase-3, Bad, Bax and MAPK proteins, which were increased following isoflurane treatment, were rescued by rutin treatment. Furthermore, rutin prevented the increase in Bcl-xL, Bcl-2 and phospho-Bad expression following isoflurane treatment, and enhanced the memory of the rats. Rutin provided neuroprotection against isoflurane-induced neuronal apoptosis and improved the learning and memory of rats by effectively regulating the expression levels of proteins in the MAPK pathway.

[Freshwater fish freshness on-line detection method based on near-infrared spectroscopy].

In the present study, the near infrared spectrum of freshwater fish was used to detect the freshness on line, and the near infrared spectra on-line acquisition device was built to get the fish spectrum. In the process of spectrum acquisition, experiment samples move at a speed of 0.5 m · s(-1), the near-infrared diffuse reflection spectrum (900-2,500 nm) could be got for the next analyzing, and SVM was used to build on-line detection model. Sample set partitioning based on joint X-Y distances algo- rithm (SPXY) was used to divide sample set, there were 111 samples in calibration set (57 fresh samples and 54 bad samples), and 37 samples in test set (19 fresh samples and 18 bad samples). Seven spectral preprocessing methods were utilized to prepro- cess the spectrum, and the influences of different methods were compared. Model results indicated that first derivative (FD) with autoscale was the best preprocessing method, the model recognition rate of calibration set was 97.96%, and the recognition rate of test set was 95.92%. In order to improve the modeling speed, it is necessary to optimize the spectra variables. Therefore genetic algorithm (GA), successive projection algorithm (SPA) and competitive adaptive reweighed sampling (CARS) were adopted to select characteristic variables respectively. Finally CARS was proved to be the optimal variable selection method, 10 characteristic wavelengths were selected to develop SVM model, recognition rate of calibration set reached 100%, and recognition rate of test set was 93.88%. The research provided technical reference for freshwater fish freshness online detection.

In vivo migration of mesenchymal stem cells / 中国实验血液学杂志

Mesenchymal stem cells (MSC) have the capacities of low immunogenicity, multiple differentiation, hematopoietic supporting and immunoregulation. And due to their relative ease of availability and ex vivo expansion, the applications of MSC in the prevention and treatment of clinical disease have been rapidly expanded in the recent years. However, increasing investigations indicate that intravenously infused MSC widely distribute to various organs of the recipients. The two intended clinical goals of adoptive cellular therapy reached to the greatest efficiency. Therefore, the ideal candidate cells showed to have the capacity of site-specific relocation in vivo. In this review, the distribution characteristics of infused MSC and the recent research advances on the strategies to enhance targeted migration of MSCs are summarized.

Clinical research on the correlations between type 2 diabetes mellitus and renal clear cell carcinoma / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the relationship between renal clear cell carcinoma and type 2 diabetes mellitus (DM).</p><p><b>METHODS</b>Two hundreds and sixty-four patients with renal clear cell carcinoma and four hundred controls who suffered from non-urinary system, non-neoplastic or non-hormone-related disorders, were enrolled from January 2008 to December 2012. The incidence of diabetes between the 2 groups and the relationship between renal clear cell carcinoma and duration of diabetes were compared, moreover, renal clear cell carcinoma patients with DM were compared with patients without DM for their clinical features, laboratory examinations and histological characteristics.</p><p><b>RESULTS</b>The comparison of renal clear cell carcinoma group and control group: the incidence of DM in the two groups were 19.7% and 12.8% respectively, and the difference was significant (χ(2) = 5.86, P < 0.05, OR = 1.68). In the renal clear cell carcinoma group, the proportion of patients with DM diagnosed within 2-4 years was 4.92%, which were significant higher than those in the control group 1.70% (χ(2) = 5.49, P < 0.05, OR = 2.91). And men with diabetes had high occurrence risk 86% of renal clear cell carcinoma (OR = 1.86, 95%CI: 1.09-3.15). The comparison of diabetes patients subgroup and non-diabetic patients subgroup in renal clear cell carcinoma group: in respect of clinical features, greatest tumor diameter in the two subgroups were (4.9 ± 2.3) cm and (4.2 ± 2.1) cm respectively, and the difference was significant (t = 1.96, P < 0.05). However, there was no significant difference in terms of age, gender and cancer location between the two subgroups (P > 0.05). In respect of laboratory examinations, serum creatinine in the two subgroups were (72 ± 20) µmol/L and (65 ± 17) µmol/L, and the difference was significant (t = 2.34, P < 0.05); serum urea nitrogen in the 2 subgroups were (7.1 ± 2.1) mmol/L and (6.0 ± 1.5) mmol/L respectively, and the difference was significant too (t = 1.47, P < 0.05). In respect of histological characteristics, the proportion of well differentiated clear cell carcinoma were 80.8% and 81.1% respectively, and the difference was significant (χ(2) = 4.23, P < 0.05). The proportion of stage II were 25.0% and 27.8% respectively and the difference was significant (χ(2) = 4.08, P < 0.05).</p><p><b>CONCLUSIONS</b>DM is closely related with renal clear cell carcinoma and DM may be a possible risk factor for the tumor. And for elderly patients with diabetes who appear waist discomfort or hematuria, a careful examination of kidney is important to make early diagnosis, give timely treatment and improve survival prognosis.</p>

Comparative study on the stability of fish actomyosin and pork actomyosin.

Effects of temperature, pH and ionic strength on the stability of actomyosin (AM) from fish and pork were studied using UV spectra, solubility, turbidity, and sulfhydryl group content measurement for comparison. Pork AM exhibited higher stability to cold storage and heating than fish AM. The unfolding rate of AM increased with increasing temperature. Intense aggregation occurred over 30 °C for fish AM and 40 °C for pork AM. New disulfide bonds mainly formed over 40 °C for fish AM and 60 °C for pork AM. Pork AM exhibited the higher turbidity than fish AM in the range of 50-90 °C, suggesting the higher extent of aggregation of pork AM. Ionic strength mainly influenced solubility of AM, but there was no effect on cleavage and formation of disulfide bond. The lowest solubility of both AM was at pH 5.42. Additionally, fish AM was more sensitive to pH changes than pork AM.

Role of secondary structures in the gelation of porcine myosin at different pH values.

Secondary structures, gelation properties and their relationships in porcine myosin were studied by circular dichroism, dynamic rheological measurement and scanning electron microscopy. Gelling of porcine myosin involved a change in myosin conformation with protein-protein and protein-water interactions. The gelation properties were strongly pH and temperature dependent. Near the pI (pH 5.5 and 6.0), porcine myosin could spontaneously coagulate at 15°C resulting partially from the presence of more ß-sheets. Myosin at pH6.5-9.0 began to form a gel at temperatures greater than 38°C. Heating caused α-helices to partially turn into ß-sheets and random coils. Subsequently, myosin aggregated and formed a gel network. The gel strength decreased and the water-holding capacity (WHC) increased with increasing pH. Correlation analysis indicated that both the unfolding of α-helices and the formation of ß-sheets favored the gelation of porcine myosin. A high ß-sheet fraction prior to heating resulted in a low WHC of resultant gel. A compact and uniform gel was also obtained at pH6.5.

Moral problems of hymen repairment / 中国医学伦理学

This paper systematically stated the sexual moral problems of the repairment of ruptured hymen resulted form different reasons and the moral principles and requirements for the operator.