Collagen, a vital matrix protein for various tissue and functions in animals, is widely applied in biomaterials. In type Ⅰ collagen, missense mutations of glycine (Gly) in the Gly-Xaa-Yaa triplet of the triple helix are a major cause of osteogenesis imperfecta (OI). Clinical manifestations exhibit marked heterogeneity, spanning a broad disease spectrum from mild skeletal fragility (Type Ⅰ) to severe limb deformities (Type Ⅲ) and perinatal lethal forms (Type Ⅱ). This study utilized recombinant collagen as a model to further elucidate whether Gly→Ala/Val mutations at the N-terminus of the integrin-binding sequence GFPGER affect collagen structure and function, and to explore the underlying mechanisms by which missense mutations impact the biological function of collagen. By introducing Ala and Val substitutions at seven Gly positions N-terminal to the GFPGER sequence, we systematically assessed the effects of these amino acid replacements on the triple-helical structure, thermal stability, integrin-binding ability, and cell adhesion of recombinant collagen. All constructs formed a stable triple-helix structure, with slightly compromised thermal stability. Gly→Val substitutions increased the susceptibility of recombinant collagen to trypsin, which suggested local conformational perturbations in the triple helix. In addition, Gly→Val substitutions significantly reduced the integrin-binding affinity and decreased HT1080 cell adhesion, with the effects stronger than Gly→Ala substitutions. Compared with Gly→Ala substitutions, substitution of Gly with the larger residue Val had enhanced negative effects on the structure and function of recombinant collagen. These findings provide new insights into the molecular mechanisms of osteogenesis imperfecta and offer theoretical references and experimental foundations for the design of collagen sequences and the development of collagen-based biomaterials.
Recombinant Proteins/biosynthesis* ; Glycine/genetics* ; Humans ; Osteogenesis Imperfecta/genetics* ; Integrins/metabolism* ; Collagen/metabolism* ; Collagen Type I/metabolism* ; Amino Acid Substitution ; Mutation ; Mutation, Missense

OBJECTIVES: To investigate the clinical treatment outcomes and the changes of the outcomes over time in extremely preterm twins in Guangdong Province, China. METHODS: A retrospective analysis was performed for 269 pairs of extremely preterm twins with a gestational age of <28 weeks who were admitted to the department of neonatology in 26 grade A tertiary hospitals in Guangdong Province from January 2008 to December 2017. According to the admission time, they were divided into two groups: 2008-2012 and 2013-2017. Besides, each pair of twins was divided into the heavier infant and the lighter infant subgroups according to birth weight. The perinatal data of mothers and hospitalization data of neonates were collected. The survival rate of twins and the incidence rate of complications were compared between the 2008-2012 and 2013-2017 groups. RESULTS: Compared with the 2008-2012 group, the 2013-2017 group (both the heavier infant and lighter infant subgroups) had lower incidence rates of severe asphyxia and smaller head circumference at birth (P<0.05). The mortality rates of both of the twins, the heavier infant of the twins, and the lighter infant of the twins were lower in the 2013-2017 group compared with the 2008-2012 group (P<0.05). Compared with the 2008-2012 group, the 2013-2017 group (both the heavier infant and lighter infant subgroups) had lower incidence rates of pulmonary hemorrhage, patent ductus arteriosus (PDA), periventricular-intraventricular hemorrhage (P-IVH), and neonatal respiratory distress syndrome (NRDS) and a higher incidence rate of bronchopulmonary dysplasia (P<0.05). CONCLUSIONS There is a significant increase in the survival rate over time in extremely preterm twins with a gestational age of <28 weeks in the 26 grade A tertiary hospitals in Guangdong Province. The incidences of severe asphyxia, pulmonary hemorrhage, PDA, P-IVH, and NRDS decrease in both the heavier and lighter infants of the twins, but the incidence of bronchopulmonary dysplasia increases. With the improvement of diagnosis and treatment, the multidisciplinary collaboration between different fields of fetal medicine including prenatal diagnosis, obstetrics, and neonatology is needed in the future to jointly develop management strategies for twin pregnancy.
Bronchopulmonary Dysplasia/epidemiology* ; Female ; Gestational Age ; Humans ; Infant ; Infant, Extremely Premature ; Infant, Newborn ; Pregnancy ; Respiratory Distress Syndrome, Newborn/epidemiology* ; Retrospective Studies ; Treatment Outcome

To investigate the effects of isovitexin Ⅳ on transient outward potassium current in rat ventricular myocytes. In this study, MTT assay was used to investigate the safe range of isovitexin. The results showed that the IC₅₀ of the drug was in the range of 10-30 μmol•L⁻¹, and the drug concentration of 1-3 μmol•L⁻¹ for the patch clamp test was within the safe range. In addition, the single ventricular myocytes were obtained by single-enzymatic hydrolysis through aortic retrograde perfusion. The transient outward potassium current (Ito) of rat ventricular myocytes was guided and measured by whole-cell patch-clamp technique and the changes of current characteristics were recorded after isovite was applied. When the concentration of IV was less than 0.1 μmol•L⁻¹, there was no significant effect on Ito. However, with the increase in the concentration of IV (≥0.3 μmol•L⁻¹), the peak of Ito was decreased gradually, from (32.32±2.9) pA/pF to （25.83±4.3） pA/pF, 1 μmol•L⁻¹ IV and (19.51±3.5) pA/pF, 3 μmol•L⁻¹ IV respectively, with an inhibition effect in a concentration-dependent manner. In the range of 1-3 μmol•L⁻¹, IV down-regulated the I-V curve of Ito significantly. The activation curve showed that IV can enable the maximum half activation potential (V1/2) to move to the positive direction, and the V1/2 was increased from (19.59±1.6) mV to (22.81±1.7) mV and (28.86±1.4) mV at concentration of 1, 3 μmol•L⁻¹, meanwhile the activation curve moved to the right. However, the maximum half inactivating potential (V1/2) of the steady-state inactivation curve of Ito was significantly decreased from (－51.43±0.99) mV to (－61.81±1.3) mV with concentration of 1 μmol•L⁻¹ and (－71.50±1.4) mV with concentration of 3 μmol•L⁻¹. The inactivation time constant of recovery from inactivation (τ) was up-regulated significantly from (94.89±0.73) ms to (118.5±1.5) ms and (162.4±1.4) ms at concentration of 1, 3 μmol•L⁻¹ respectively. Meanwhile IV could enable the inactivation recovery curve to move to the right, which suggested that it can prolong the recovery time from inactivation of the transient outward potassium channel. In conclusion, isovitexin had a high inhibitory effect on Ito in rat ventricular myocytes.

OBJECTIVETo compare oncologic adequacy of resection and long-term oncologic outcomes between laparoscopic-assisted surgery (LS) and open surgery (OS) in the treatment of rectal cancer.

METHODSLiterature searches of electronic databases (PubMed, Embase, Web of Science,and Cochrane Library) and manual searches up to June 30, 2010 were performed to identify RCTs comparing values of oncologic adequacy of resection, recurrence and survival following LS and OS. Fixed and random effects models were used.

RESULTSSix RCTs enrolling 1033 participants (LS group:577 cases, OS group:456 cases)were included in the meta-analysis. Number of lymph node harvested was similar(WMD=-0.38, 95%CI:-1.35-0.58, P=0.43). LS had a slightly higher circumference resection margin(CRM) positive rate with no statistical significance[7.94% vs. 5.37%; risk ratio(RR)=1.13; 95%CI:0.69-1.85, P=0.63]. There was no significant difference between the two groups in local recurrence (RR=0.55; 95%CI:0.22-1.40, P=0.21). The 3-year overall survival [Hazard ratio(HR)=0.76; 95%CI:0.54-1.07, P=0.11] and 3-year disease-free survival(HR=1.16; 95%CI:0.61-2.20, P=0.64) were not significantly different between the two groups.

CONCLUSIONCompared with open surgery, laparoscopic surgery of rectal carcinoma offers similar oncological clearance and long-term oncological outcomes.

Humans ; Laparoscopy ; Laparotomy ; Randomized Controlled Trials as Topic ; Rectal Neoplasms ; surgery ; Treatment Outcome

OBJECTIVETo investigate the impact of experimental varicocele (EV) on the ipsilateral testis in rats.

METHODSEV was induced by partial ligation of the left renal vein in male SD rats, the control rats subjected to sham operation, and the testes of the EV models and controls were extirpated 6, 12, and 18 weeks later. Johnson's score, ultrastructure of seminiferous tubules, intratesticular testosterone concentration (ITC) and germ cell apoptotic index (AI) of each left testis were evaluated.

RESULTSJohnson's scores were (6.92 +/- 0.52), (4.83 +/- 0.41) and (2.95 +/- 0.26), ITCswere (6.32 +/- 0.85), (5.17 +/- 0.76) and (4.11 +/- 0.69) and AIs were (5.32 +/- 1.23), (15.21 +/- 0.97) and (21.13 +/- 1.12) respectively in the 6 w , 12 w and 18 w EV groups, significantly lower than in the corresponding control groups, (9.56 +/- 0.35, 9.63 +/- 0.31, 9.39 +/- 0.46), (9.64 +/- 1.23, 9.38 +/- 0.69, 9.73 +/- 0.49) and (3.21 +/- 1.15, 3.43 +/- 1.21, 3.61 +/- 1. 15) (P < 0.05), the former two showing a gradual decline while the latter a significant elevation with the increasing duration of varicocele. The damage to the ultrastructure of seminiferous tubules was aggravated with the prolonging of varicocele.

CONCLUSIONEV can cause a progressive decline of ITC, dyszoospermia and increased AI of germ cells.

Animals ; Apoptosis ; Disease Models, Animal ; Infertility, Male ; Male ; Rats ; Rats, Sprague-Dawley ; Seminiferous Epithelium ; cytology ; ultrastructure ; Testis ; chemistry ; metabolism ; Testosterone ; metabolism ; Varicocele ; metabolism ; physiopathology