Microbiota signatures associated with invasive Candida albicans infection in the gastrointestinal tract of immunodeficient mice

Candida albicans is a commensal microorganism in the human gut but occasionally causes invasive C. albicans infection (ICA), especially in immunocompromised individuals. Early initiation of antifungal therapy is associated with reduced mortality of ICA, but rapid diagnosis remains a challenge. The ICA-associated changes in the gut microbiota can be used as diagnostic and therapeutic targets but have been poorly investigated. In this study, we utilized an immunodeficient Rag2γc (Rag2-/-il2γc-/-) mouse model to investigate the gut microbiota alterations caused by C. albicans throughout its cycle, from its introduction into the gastrointestinal tract to invasion, in the absence of antibiotics. We observed a significant increase in the abundance of Firmicutes, particularly Lachnospiraceae and Ruminococcaceae, as well as a significant decrease in the abundance of Candidatus Arthromitus in mice exposed to either the wild-type SC5314 strain or the filamentation-defective mutant (cph1/cph1 efg1/efg1) HLC54 strain of C. albicans. However, only the SC5314-infected mice developed ICA. A linear discriminate analysis of the temporal changes in the gut bacterial composition revealed Bacteroides vulgatus as a discriminative biomarker associated with SC5314-infected mice with ICA. Additionally, a positive correlation between the B. vulgatus abundance and fungal load was found, and the negative correlation between the Candidatus Arthromitus abundance and fungal load after exposure to C. albicans suggested that C. albicans might affect the differentiation of intestinal Th17 cells. Our findings reveal the influence of pathogenic C. albicans on the gut microbiota and identify the abundance of B. vulgatus as a microbiota signature associated with ICA in an immunodeficient mouse model.

[Regional analysis of high risk factors of hypertensive disorders in pregnancy with organ or system impairment]

Objective: To explore the influencing factors of pregnancy-induced hypertensive disorders in pregnancy (HDP) with organ or system impairment in pregnant women, and to analyze and compare the differences of HDP subtypes in different regions of China. Methods: A total of 27 680 pregnant women with HDP with complete data from 161 hospitals in 24 provinces, autonomous regions and municipalities were retrospectively collected from January 1, 2018 to December 31, 2018. According to their clinical manifestations, they were divided into hypertension group [a total of 10 308 cases, including 8 250 cases of gestational hypertension (GH), 2 058 cases of chronic hypertension during pregnancy] and hypertension with organ or system impairment group [17 372 cases, including 14 590 cases of pre-eclampsia (PE), 137 cases of eclampsia, 2 645 cases of chronic hypertension with PE]. The subtype distribution of HDP in East China (6 136 cases), North China (4 821 cases), Central China (3 502 cases), South China (8 371 cases), Northeast China (1 456 cases), Southwest China (2 158 cases) and Northwest China (1 236 cases) were analyzed. By comparing the differences of HDP subtypes and related risk factors in different regions, regional analysis of the risk factors of HDP pregnant women with organ or system impairment was conducted. Results: (1) The proportions of HDP pregnant women with organ or system impairment in Northeast China (79.05%, 1 151/1 456), Central China (68.42%, 2 396/3 502) and Northwest China (69.34%, 857/1 236) were higher than the national average (62.76%, 17 372/27 680); the proportions in North China (59.18%, 2 853/4 821), East China (60.85%, 3 734/6 136) and South China (59.56%, 4 986/8 371) were lower than the national average, and the differences were statistically significant (all P<0.05). (2) Univariate analysis showed that the proportions of primiparas, non-Han, non-urban household registration, irregular prenatal examination and PE history in the hypertension with organ or system impairment group were higher than those in the hypertension group, and the differences were statistically significant (all P<0.05). Multivariate logistic regression analysis showed that primiparas, non-Han, non-urban household registration, irregular prenatal examination and PE history were independent risk factors for HDP pregnant women with organ or system impairment (all P<0.05). (3) Primipara: the rates of primipara in Northeast China, North China and Southwest China were higher than the national average level, while those in South China, Central China and Northwest China were lower than the national average level. Non-Han nationality: the rates of non-Han nationality in Northeast China, North China and Northwest China were higher than the national average, while those in East China, South China and Central China were lower than the national average. Non-urban household registration: the rates of non-urban household registration in Northeast China, North China, and Southwest China were lower than the national average, while those in East China, Central China were higher than the national average. Irregular prenatal examination: the rates of irregular prenatal examination in North China, South China and Southwest regions were lower than the national average level, while those in Northeast China, Central China and Northwest China were higher than the national average level. History of PE: the incidence rates of PE in Northeast China, North China, South China and Southwest China were lower than the national average level, while those in Central China and Northwest China were higher than the national average level. Conclusions: Primiparas, non-Han, non-urban household registration, irregular prenatal examination, and PE history are risk factors for HDP pregnant women with organ or system impairment. Patients in Northeast, Central and Northwest China have more risk factors, and are more likely to be accompanied by organ or system function damage. It is important to strengthen the management of pregnant women and reduce the occurrence of HDP.

[Cone-beam CT analysis of the correlation between incisor root resorption rate and tooth movement index in adult patients with fixed orthodontics appliance]

Objective: To analyze the correlation between the root resorption rate and tooth movement of the maxillary and mandibular incisors before and after orthodontic treatment in adult patients using cone-beam CT (CBCT), and to explore the related factors that affect the apical root resorption. Methods: In this retrospective study, 23 adult patients with classⅠor class Ⅱ division 1 malocclusion [2 males and 21 females, mean age (23.4±6.3) years, treatment time (2.1±0.7) years] who received orthodontic treatment with fixed appliance in Department of Oral & Cranio-Maxillofacial Surgery, Shanghai Ninth People's Hospital from January 2017 to June 2021 were enrolled. Full-column CBCT examination was performed before and after treatment. A three-dimensional model was established to observe and record the volume of the maxillary and mandibular central and lateral incisors before and after treatment. The change of the incisal edge, the angle of rotation of the incisal edge, and the direction of the long axis of the tooth were also measured. The root resorption in each tooth before and after treatment was compared, and the root resorption rate was calculated. Pearson correlation analysis was performed on the root absorption rate before and after treatment with age, treatment time and tooth movement. Results: After treatment, the tooth volume of the maxillary and mandibular central and lateral incisors decreased significantly (P<0.01). The root absorption volumes were (20.2±6.0) mm3 and (11.2±4.7) mm3 in maxillary central and lateral incisors, and (14.7±4.6) mm3 and (14.8±5.0) mm3 in mandibular central and lateral incisors, respectively. The root absorption rates were (9.49±1.75)% and (9.13±3.24)% in maxillary central and lateral incisors, and (8.56±3.43)% and (9.13±3.24)%, in mandibular central and lateral incisors, respectively (F=0.56, P=0.640). The root resorption rate of maxillary central incisors had a weak positive correlation with the change of sagittal distance of incisal edge (r=0.36, P=0.015). The root resorption rate of mandibular central incisors had a moderate positive correlation with the vertical movement distance (r=0.48, P=0.001). The root resorption rate of mandibular lateral incisors was weakly positively correlated with the vertical movement of incisal edge and the treatment time (r=0.35, P=0.016; r=0.34, P=0.021), and was moderately positively correlated wit the change of sagittal movement of incisal edge (r=0.44, P=0.002). Conclusions: During orthodontic treatment, both maxillary and mandibular incisors had a certain degree of root resorption, which was related to sagittal and vertical movement of the incisors and the time of orthodontic treatment.

Induction of high affinity monoclonal antibodies against SARS-CoV-2 variant infection using a DNA prime-protein boost strategy

BACKGROUND

Calls for the coronavirus to be treated as an endemic illness, such as the flu, are increasing. After achieving high coverage of COVID-19 vaccination, therapeutic drugs have become important for future SARS-CoV-2 variant outbreaks. Although many monoclonal antibodies have been approved for emergency use as treatments for SARS-CoV-2 infection, some monoclonal antibodies are not authorized for variant treatment. Broad-spectrum monoclonal antibodies are unmet medical needs.

METHODS

We used a DNA prime-protein boost approach to generate high-quality monoclonal antibodies. A standard ELISA was employed for the primary screen, and spike protein-human angiotensin-converting enzyme 2 blocking assays were used for the secondary screen. The top 5 blocking clones were selected for further characterization, including binding ability, neutralization potency, and epitope mapping. The therapeutic effects of the best monoclonal antibody against SARS-CoV-2 infection were evaluated in a hamster infection model.

RESULTS

Several monoclonal antibodies were selected that neutralize different SARS-CoV-2 variants of concern (VOCs). These VOCs include Alpha, Beta, Gamma, Delta, Kappa and Lambda variants. The high neutralizing antibody titers against the Beta variant would be important to treat Beta-like variants. Among these monoclonal antibodies, mAb-S5 displays the best potency in terms of binding affinity and neutralizing capacity. Importantly, mAb-S5 protects animals from SARS-CoV-2 challenge, including the Wuhan strain, D614G, Alpha and Delta variants, although mAb-S5 exhibits decreased neutralization potency against the Delta variant. Furthermore, the identified neutralizing epitopes of monoclonal antibodies are all located in the receptor-binding domain (RBD) of the spike protein but in different regions.

CONCLUSIONS

Our approach generates high-potency monoclonal antibodies against a broad spectrum of VOCs. Multiple monoclonal antibody combinations may be the best strategy to treat future SARS-CoV-2 variant outbreaks.

A formal [4 + 1] cycloaddition reaction of Baylis–Hillman bromides with sulfur ylides: facile access to α-alkenyl lactones

A formal [4 + 1] cycloaddition reaction of Baylis–Hillman adducts with sulfur ylides has been developed for the first time.

A rapid detection of tomato yellow leaf curl virus using recombinase polymerase amplification-lateral flow dipstick assay

Tomato yellow leaf curl disease which is caused by Tomato yellow leaf curl virus (TYLCV) is economically important and a widely spread tomato disease in China. Rapid and accurate detection methods are important in the control TYLCV. Here, a rapid method was developed to identify TYLCV on the basis of recombinase polymerase amplification (RPA) that can be visualized in 5 min using lateral flow dipsticks. The sensitivity and the specificity of this method were evaluated. This method can detect 0·5 pg DNA after 30 min at 37°C without any expensive instrumentation. In addition, it showed higher sensitivity than a PCR method when purified DNA was used. Moreover, the TYLCV was specifically detected, whereas other viruses infecting tomato produced negative results. The crude tomato extracts used in this assay has potential application in minimally equipped plant clinic laboratories. This method will facilitate the early and rapid detection of TYLCV for the timely application of control measures.

[Comparative analysis of high risk factors between early-onset pre-eclampsia and late-onset pre-eclampsia]

Objective: To explore the difference of high-risk factors between early-onset and late-onset pre-eclampsia, and to further understand high-risk factors of pre-eclampsia. Methods: Clinical data of pre-eclampsia pregnant women in 160 medical institutions in China in 2018 were retrospectively analyzed, including 8 031 cases of early-onset pre-eclampsia and 12 969 cases of late-onset pre-eclampsia. The proportion of high-risk factors, different body mass index (BMI) and age stratification between early-onset group and late-onset group were compared. Results: (1) Univariate analysis of high-risk factors: the proportions of high-risk factors in early-onset group and late-onset group were compared, and the differences were statistically significant (all P<0.05). Among them, the proportions of primipara and multiple pregnancy in early-onset group were lower than those in late-onset group, while the proportions of pregnant women with advanced age, irregular antenatal examination, obesity, family history of hypertension, pre-eclampsia, diabetes, kidney diseases, immune system diseases and assisted reproductive technology were higher than those in late-onset group. (2) Hierarchical analysis of BMI: the proportion of pregnant women with BMI≥24 kg/m² in early-onset group [48.2% (2 828/5 872) vs 45.5% (4 177/9 181), respectively; P=0.001] and the proportion of pregnant women with BMI ≥28 kg/m² in early-onset group [19.5% (1 143/5 872) vs 18.0% (1 656/9 181), respectively; P=0.028] were significantly higher than those in late-onset group. (3) Age stratification analysis: the proportion of pregnant women aged 35-39 years in the early-onset group [21.8% (1 748/8 023) vs 17.5% (2 110/12 068), respectively; P<0.01], the proportion of pregnant women 40-44 years old [6.8% (544/8 023) vs 5.4% (648/12 068), respectively; P<0.01], and the proportion of pregnant women ≥45 years old [0.7% (58/8 023) vs 0.5% (57/12 068), respectively; P=0.021] were significantly higher than those in the late-onset group. (4) Multivariate analysis: advanced age (≥35 years old), multiple pregnancy, irregular antenatal examination or transfer from other hospitals, family history of hypertension (including paternal, maternal and parental lines), previous history of pre-eclampsia, kidney diseases, immune system diseases (systemic lupus erythematosus, antiphospholipid antibody syndrome) and assisted reproductive technology pregnancy were the risk factors affecting the severity of pre-eclampsia (all P<0.05). Conclusion: Pregnant women with high risk factors such as age ≥35 years old, BMI ≥24 kg/m² before pregnancy, family history of hypertension, history of pre-eclampsia, chronic kidney diseases, immune diseases (mainly including systemic lupus erythematosus and antiphospholipid syndrome) and assisted reproductive technology are more likely to have early-onset pre-eclampsia.

[Effects of interpregnancy interval on pregnancy outcomes of subsequent pregnancy: a multicenter retrospective study]

Objective: To explore the effects of interpregnancy interval (IPI) on pregnancy outcomes of subsequent pregnancy. Methods: A multicenter retrospective study was conducted in 21 hospitals in China. Information of age, height, pre-pregnancy weight, IPI, history of diseases, complications of pregnancy, gestational age of delivery, delivery mode, and pregnancy outcomes of the participants were collected by consulting medical records of pregnant women who had two consecutive deliveries in the same hospital during 2011 to 2018. The participants were divided into 4 groups according to IPI:<18 months, 18-23 months, 24-59 months and ≥60 months. According to the WHO's recommendation, with the IPI of 24-59 months group as a reference, to the effects of IPI on pregnancy outcomes of subsequent pregnancy were analyzed. Stratified analysis was further carried out based on age, history of gestational diabetes mellitus (GDM), macrosomia, and premature delivery, to explore the differences in the effects of IPI on pregnancy outcomes among women with different characteristics. Results: A total of 8 026 women were included in this study. There were 423, 623, 5 512 and 1 468 participants in <18 months group, 18-23 months group, 24-59 months group and ≥60 months group, respectively. (1) The age, pre-pregnancy body mass index (BMI), history of cesarean section, GDM, gestational hypertension and cesarean section delivery rate of <18 months group, 18-23 months group, 24-59 months group and ≥60 months group were gradually increased, and the differences were statistically significant (P<0.05). (2) After adjusting for potential confounding factors, compared with women in the IPI of 24-59 months group, the risk of premature delivery, premature rupture of membranes, and oligohydramnios were increased by 42% (OR=1.42, 95%CI: 1.07-1.88, P=0.015), 46% (OR=1.46, 95%CI: 1.13-1.88, P=0.004), and 64% (OR=1.64, 95%CI: 1.13-2.38, P=0.009) respectively for women in the IPI≥60 months group. No effects of IPI on other pregnancy outcomes were found in this study (P>0.05). (3) After stratified by age and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of oligohydramnios for women with advanced age (OR=2.87, 95%CI: 1.41-5.83, P=0.004); and <18 months could increase the risk of premature rupture of membranes for women under the age of 35 (OR=1.59, 95%CI: 1.04-2.43, P=0.032). Both the risk of premature rupture of membranes (OR=1.58, 95%CI: 1.18-2.13, P=0.002) and premature delivery (OR=1.52, 95%CI: 1.07-2.17, P=0.020) were significantly increased in the IPI≥60 months group. After stratified by history of GDM and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would lead to an increased risk of postpartum hemorrhage for women with a history of GDM (OR=5.34, 95%CI: 1.45-19.70, P=0.012) and an increased risk of premature rupture of membranes for women without a history of GDM (OR=1.44, 95%CI: 1.10-1.90, P=0.009). After stratified by history of macrosomia and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months could increase the proportion of cesarean section for women with a history of macrosomia (OR=4.11, 95%CI: 1.18-14.27, P=0.026) and the risk of premature rupture of membranes for women without a history of macrosomia (OR=1.46, 95%CI: 1.12-1.89, P=0.005). After stratified by history of premature delivery and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of premature rupture of membranes for women without a history of premature delivery (OR=1.47, 95%CI: 1.13-1.92, P=0.004). Conclusions: Both IPI≥60 months and <18 months would increase the risk of adverse pregnancy outcomes in the subsequent pregnancy. Healthcare education and consultation should be conducted for women of reproductive age to maintain an appropriate IPI when they plan to pregnant again, to reduce the risk of adverse pregnancy outcomes in the subsequent pregnancy.

Candida albicans Colonizes and Disseminates to the Gastrointestinal Tract in the Presence of the Microbiota in a Severe Combined Immunodeficient Mouse Model

Candida albicans is the leading cause of candidemia or other invasive candidiasis. Gastrointestinal colonization has been considered as the primary source of candidemia. However, few established mouse models that mimic this infection route are available. In the present study, we established a mouse model of disseminated candidiasis developed through the translocation of Candida from the gut. In this study, we developed a novel C. albicans GI colonization and dissemination animal model by using severe combined immunodeficient Rag2^–/–IL2γc^–/– (Rag2γc) mice, which lack functional T, B, NK cells, and IL2γc-dependent signaling. Rag2γc mice were highly susceptible to C. albicans gastrointestinal infection even in the presence of the gut microbiota. Within 4 weeks post infection, Rag2γc mice showed dose-dependent weight loss and disseminated candidiasis in more than 58% (7/12) of moribund mice. Histological analysis demonstrated abundant hyphae penetrating the mucosa, with significant neutrophilic infiltration in mice infected with wild-type C. albicans but not a filamentation-defective mutant. In moribund Rag2γc mice, the necrotic lesions and disrupted epithelial cells were associated with C. albicans hyphae. Notably, removal of the gut microbiota by antibiotics exacerbated the severity of fungal infection in Rag2γc mice, as demonstrated by elevated fungal burdens and accelerated weight loss and death. Furthermore, higher fungal burden and IL-1β expression were prominently noted in the stomach of Rag2γc mice. In fact, a significant increase in circulating proinflammatory cytokines, including IL-6, TNF-α, and IL-10, indicative of a septic response, was evident in infected Rag2γc mice. Additionally, Rag2γc mice exhibited significantly lower levels of IL-22 but not IFN-γ or IL-17A than wild-type B6 mice, suggesting that IL-22 plays a role in C. albicans gastrointestinal infection. Collectively, our analysis of the Rag2γc mouse model revealed features of C. albicans gastrointestinal colonization and dissemination without the interference from antibiotics or chemotherapeutic agents, thus offering a new investigative tool for delineating the pathogenesis of C. albicans and its cross-talk with the gut microbiota.

[Etiology and molecular-epidemiological characteristics of viral meningo-encephalitis in Zhejiang province, 2002-2018]

Objective: To understand the pathogens and molecular-epidemiologic characteristics of viral meningo-encephalitis in Zhejiang province during 2002 to 2018. Methods: All the samples were collected from suspected patients admitted to the hospitals under the monitoring program. Of the total samples, 2 173 were cerebrospinal fluids while the other 455 were stool specimens. Cerebrospinal fluid (CSF) samples were subject to real-time qPCR for the detection of Human enterovirus (HEV), Mumps virus (MuV), Herpes simplex virus (HSV), Cytomegalovirus (CMV) and Japanese encephalitis virus (JEV). Stool sample were subject to real-time qPCR for HEV. ELISA was used to detect the IgM antibodies in CSF, in the 5 kinds of virus mentioned above. VP1 genes from all RNA-positive specimen were amplified, sequenced, for typing and for evolution analysis. Results: 871 (40.1%) of the 2 173 samples were detected as HEV nucleic acid positive during 2002 to 2018. 654 (38.1%) of the 1 718 CSF sample were HEV nucleic acid positive while 217 (47.7%) of the 455 stool sample were HEV nucleic acid positive. Among the total positive nucleic acid sample, 670 of them were VP1 sequence positive, including 5 HEV-A and 665 HEV-B. There were 23 HEV serotypes, including Coxsackievirus (CV) CVA4, CVA6, CVA9, CVA10, CVB1-5, Echovirus (EchoV; E) E3, E4, E6,E7, E9, E11, E14, E16, E18, E21, E25, E30, E33 and EV-71. The top three serotypes went to E30, E6 and CVB5. These three serotypes presented enhanced viral activity in every several years. 795 CSF samples were detected as virus nucleic acid positive, including 374 HEV, 6 MuV, 5 HSV and 5 CMV, from 2012 to 2015 and in 2018. 5 kinds of IgM antibodies were detected simultaneously in 368 CSF samples, including 2 HEV positive, 6 JEV positive and 1 MuV positive for 5 viruses, respectively. Except for EV-71, there were 517 EchoV and 152 CV viruses presented, with the ratio of 3.4∶1. These two kinds of viruses alternately changed for each predominant epidemic strains in every 3-5 years. Based on VP1, results from the phylogenetic tree showed that HEV from Zhejiang province clustered into HEV-A and HEV-B clades respectively. E30 developed both h and i sub-genotypes. Conclusions: HEV-B seemed the main pathogen for viral meningo-encephalitis in Zhejiang province. Ratio of positive detection on EchoV was significantly higher than that on CV. These two kinds of virus alternately presented changing tendency in every several years. Predominant epidemic strains E30, CVB5 and E6 were presenting enhanced viral activity, also in every several years. High correlation was found in both HEV viral activity from the surveillance sites and in time line of the viral meningo-encephalitis outbreaks.

[Non-activated Peroxymonosulfate-Induced Degradation of Sulfasalazine: Kinetics and Mechanism Investigations]

Sulfate-radical-based advanced oxidation technologies by activation of peroxymonosulfate (PMS) have been widely applied for decontamination of wastewater, although our knowledge on the direct oxidation of organic contaminants by PMS is still limited. In this study, the direct interaction between PMS and sulfasalazine (SSZ), a widely used antibiotic, was investigated systematically, including the reaction kinetics and transformation pathways. The results revealed that SSZ degradation obeyed a pseudo-first-order kinetic model and increasing initial PMS concentration or ionic strength could accelerate the degradation rates; alkaline conditions were beneficial to SSZ removal by PMS; and the presence of Cl^- markedly promoted SSZ decay. The degradation of SSZ by PMS was inhibited in surface water. By using liquid chromatography-mass spectrometry as well as reaction site identification, two different oxidation pathways were proposed, including hydroxylation and SO₂ extrusion. The findings obtained in this study could help to evaluate the feasibility of decontamination of sulfonamide antibiotics by non-activated PMS.

The prevention and augmentation of tetravalent recombinant measles-vectored dengue vaccine in dengue-2 infected AG129 mice

Dengue is an emerging mosquito-borne disease and the use of prophylactic vaccine is still limited. We have previously developed the tetravalent dengue vaccine (rMV-TDV) by a recombinant measles virus (MV) vector expressing envelope protein domain III (ED3). In this study, we used AG129 mice to evaluate the protective and/or pathogenic immune responses induced by rMV-TDV. Immunization of rMV-TDV has induced a significant neutralizing antibody response against all serotypes of DENV, as well as a significant CD4-dependent IFN-γ response biased to DENV-3, compared to the vector controls. After DENV-2 challenge, rMV-TDV-immunized mice showed a significant lower viremia and no increase of inflammatory cytokines comparing to the vector controls, which had a ~100 times higher viremia and a significant increase of IFN-γ and TNF-α 3 days after challenge. A robust DENV-2 specific IFN-γ response detected in rMV-TDV-immunized mice suggested that pre-existing DENV-3 biased T-cell responses didn’t cross-react to DENV-2 but an anamnestic DENV-2 specific T-cell response was recalled. Prior to the challenge, only DENV-3 specific IgG demonstrated a significant higher avidity than other serotypes, whose specific IgG avidity increased after DENV-2 challenge, particular in DENV-1 and -2. However, the passive transfer of rMV-TDV immunized sera plus splenocytes resulted in the higher viremia and the significant increase of inflammatory cytokines in AG129 recipient mice after DENV-2 challenge than the vector control donors did. It suggested that while the immunity by rMV-TDV waned, the potential risks for the severe disease increased. Our data shed the lights on the role of a balanced CD4 T-cell response in the prevention of severe dengue.

Immunodomination of Serotype-Specific CD4+ T-Cell Epitopes Contributed to the Biased Immune Responses Induced by a Tetravalent Measles-Vectored Dengue Vaccine

Dengue is an emerging mosquito-borne disease, and the use of prophylactic vaccines is still limited. We previously developed a tetravalent dengue vaccine (rMV-TDV) by a recombinant measles virus (MV) vector expressing envelope protein domain III (ED3). In this study, we used dengue-susceptible AG129 mice to evaluate the protective and/or pathogenic immune responses induced by rMV-TDV. Consistent with the previous study, rMV-TDV-immunized mice developed a significant neutralizing antibody response against all serotypes of DENV, as well as a significant IFN-γ response biased to DENV-3, compared to the vector controls. We further demonstrated that this DENV-3-specific IFN-γ response was dominated by one CD4⁺ T-cell epitope located in E_349-363. After DENV-2 challenge, rMV-TDV-immunized mice showed a significantly lower viremia and no inflammatory cytokine increase compared to the vector controls, which had an ~100 times higher viremia and a significant increase in IFN-γ and TNF-α. As a correlate of protection, a robust memory IFN-γ response specific to DENV-2 was boosted in rMV-TDV-immunized mice after challenge. This result suggested that pre-existing DENV-3-dominated T-cell responses did not cross-react, but a DENV-2-specific IFN-γ response, which was undetectable during immunization, was recalled. Interestingly, this recalled T-cell response recognized the epitope in the same position as the E_349-363 but in the DENV-2 serotype. This result suggested that immunodomination occurred in the CD4⁺ T-cell epitopes between dengue serotypes after rMV-TDV vaccination and resulted in a DENV-3-dominated CD4⁺ T-cell response. Although the significant increase in IgG against both DENV-2 and -3 suggested that cross-reactive antibody responses were boosted, the increased neutralizing antibodies and IgG avidity still remained DENV-2 specific, consistent with the serotype-specific T cell response post challenge. Our data reveal that immunodomination caused a biased T-cell response to one of the dengue serotypes after tetravalent dengue vaccination and highlight the roles of cross-reactive T cells in dengue protection.

[Value of lenvatinib for the treatment of advanced hepatocellular carcinoma]

Objective: To observe the safety and efficacy of lenvatinib for the treatment of medium-advanced hepatocellular carcinoma. Methods: A total of 36 patients with medium-advanced hepatocellular carcinoma from the First Medical Center of the Chinese PLA General Hospital were retrospectively analyzed from January 2018 to May 2019. All patients had shown tumor progression after at least 2 sessions of TACE. The patients were consisted of 30 males and 6 females with age range of 35 to 76 (54±10) years. Patients received orally administered lenvatinib at a dose of 12 mg once daily for patients ≥ 60 kg and 8 mg once daily for patients<60 kg. According to modified RECIST criteria the tumor response, disease control rate, overall survival and progression free survival were evaluated once every 6-8 weeks. The adverse events were recorded. Results: No patient was in complete response, 2 cases (5.7%) in partial response, and 5 cases (14.3%) in stable disease, respectively. Disease control rate was 20.0% (7/35), the overall survival was 11.5 months, and the progression free survival was 5.3 months. The overall incidence of adverse events was 66.7% (24/36). The most frequent adverse events were hypertension, proteinuria, hand-foot skin reaction and abdominal distension. Conclusion: Lenvatinib can extend the overall survival in a percentage of medium-advanced hepatocellular carcinoma patients who were unresectable and refractory to TACE. Although the incidence of adverse events is high, most of them are mild and reversible.

[Progression of diagnosis and treatment in pediatric colorectal carcinoma]

Colorectal carcinoma (CRC) is the third most common malignancy in adults. Pediatric colorectal carcinoma (PCRC) is a rare non-embryonal tumor with a significantly lower incidence compared to adults. The clinical manifestations of PCRC are not typical, and pediatricians usually have no enough experience in diagnosis and treatment. Therefore, early diagnosis is extremely difficult, which would always lead to late clinical stages when diagnosis is made. At present, the pathogenesis of PCRC is still not clear, and many countries have started to carry out researches at the level of genes, molecules and cells. In both tumor primary tumors and distant metastases, PCRC has obvious difference in distribution from adults, and the proportion of pathological type of mucous adenocarcinoma (including the signet ring cell carcinoma) was significantly higher than that of adults. Although treated according to adult colorectal cancer guidelines, PCRC has been unable to achieve ideal efficacy with poor prognosis and lower long-term survival rate. The purpose of this paper is to summarize the epidemiological characteristics, pathogenesis, clinical symptoms, pathological types, treatment and prognosis of colorectal cancer in children by reviewing the latest literatures at home and abroad.

Transarterial embolisation with bleomycin and N-butyl-2-cyanoacrylate -Lipiodol mixture for symptomatic polycystic liver disease: preliminary experience

AIMS

To evaluate the therapeutic effect and safety of transarterial embolisation using a bleomycin-Lipiodol mixture and N-butyl-2-cyanoacrylate (NBCA)-Lipiodol mixture (BNL) for the treatment of polycystic liver disease (PLD).

MATERIALS AND METHODS

From June 2012 to July 2018, a total of consecutive 14 symptomatic patients (13 women and 1 man; mean age, 49.3±9.9 years) with PLD were referred and underwent transcatheter arterial embolisation (TAE) with BNL.

RESULTS

Technical success was achieved in all cases. PLD-related severe symptoms were improved remarkably in 13 of the treated patients. The mean maximum abdominal circumference decreased significantly from 100.6±9.4 to 94.9±9.1 cm (p<0.01). The total liver volume decreased significantly compared with pre-TAE in 13 patients at 6-12 months after TAE. It decreased from 9,776±2,219 to 8,303±2,009 cm³ (p<0.01). There were no major complications associated with the procedure.

CONCLUSION

TAE with the bleomycin-Lipiodol mixture and NBCA-Lipiodol mixture may be an effective method for treating symptomatic PLD patients, with improvement of symptoms and shrinkage of cyst volume.

[Transarterial chemoembolization with bleomycin treatment for moderate-advenced hepatocellular carcinoma]

Objective: To investigate the safety and efficacy of transarterial chemoembolization (TACE) using bleomycin for the treatment of medium-advanced hepatocellular carcinoma (HCC). Methods: Between December 2015 and December 2017, a total of 160 patients from the Chinese PLA General Hospital with moderate-advanced HCC whose diagnoses were confirmed by pathology or clinical imaging and were in accord with the Barcelona Clinic Liver Cancer (BCLC) staging criteria were prospectively analyzed.All patients had shown persistent viable tumor or tumor progression after at least 2 sessions of TACE.All patients included 135 males and 25 females , age 35-74 (57±8)years, were randomly divided into two groups, the treatment group: TACE procedures consisted of bleomycin+ pirarubicin+ oxaliplatin+ fluorouracil, the control group: pirarubicin+ oxaliplatin+ fluorouracil, and according to modified RECIST criteria the tumor response was evaluated once every 4-6 weeks, survival analysis was performed, overall survival and progression free survival were evaluated.the adverse events were recorded. Results: Response rate of the treatment group was 27.5%(22/80), the median progression free survival(mPFS)was 5.8 months, and the median overall survival (mOS) was 8.1 months.Response rate of the control group was 7.5%(6/80), mPFS of 2.9 months, and mOS of 4 months.The differences in mPFS and in mOS between the two groups were statistically significant (P=0.009, 0.002 respectively), and no serious adverse occurred. Conclusion: It is suggested that transarterial chemoembolization with bleomycin is safe and effective for medium-advenced HCC.

Coniella vitis sp. nov. Is the Common Pathogen of White Rot in Chinese Vineyards

Grape white rot is a common disease and causes considerable yield losses in many grape-growing regions when environmental conditions are favorable. We surveyed grape white rot in five provinces in China and collected 27 isolates from diseased grape tissues. Multigene phylogenetic analyses of the internal transcribed spacer region (ITS1-5.8S-ITS2), the 28S large subunit of nuclear ribosomal RNA (LSU), partial translation elongation factor 1-alpha gene (TEF 1-α), and partial histone 3 gene (HIS), coupled with genealogical concordance phylogenetic species recognition and morphological observations, revealed that Coniella vitis sp. nov. and C. diplodiella are the causal agents of grape white rot in China. Koch's postulates were performed on Vitis vinifera cv. Summer Black in a greenhouse. These results confirmed the pathogenicity on grapes, as symptoms were reproduced, and also indicated significant variations in the virulence among C. vitis isolates. This work provides evidence that C. vitis is the main pathogen of grape white rot in China and also provides an optimized multigene backbone for resolving Coniella species.

Molecular Engineering and Design of Semiconducting Polymer Dots with Narrow-Band, Near-Infrared Emission for in Vivo Biological Imaging

This article describes the design and synthesis of donor-bridge-acceptor-based semiconducting polymer dots (Pdots) that exhibit narrow-band emissions, ultrahigh brightness, and large Stokes shifts in the near-infrared (NIR) region. We systematically investigated the effect of π-bridges on the fluorescence quantum yields of the donor-bridge-acceptor-based Pdots. The Pdots could be excited by a 488 or 532 nm laser and have a high fluorescence quantum yield of 33% with a Stokes shift of more than 200 nm. The emission full width at half-maximum of the Pdots can be as narrow as 29 nm, about 2.5 times narrower than that of inorganic quantum dots at the same emission wavelength region. The average per-particle brightness of the Pdots is at least 3 times larger than that of the commercially available quantum dots. The excellent biocompatibility of these Pdots was demonstrated in vivo, and their specific cellular labeling capability was also approved by different cell lines. By taking advantage of the durable brightness and remarkable stability of these NIR fluorescent Pdots, we performed in vivo microangiography imaging on living zebrafish embryos and long-term tumor monitoring on mice. We anticipate these donor-bridge-acceptor-based NIR-fluorescent Pdots with narrow-band emissions to find broad use in a variety of multiplexed biological applications.

[Study of coenzyme Q10 in the liver of preeclampsia pregnant rats]

OBJECTIVE

To investigate the protective effect of coenzyme Q10 (CoQ10) in the liver of preeclampsiapregnant rats and the potential etiology.

METHODS

Fifty pregnant SD rats were equally divided into the normal pregnant (NP) group (n=10) and the preeclampsia (PE) group (n=40) randomly. The PE rats (n=40) were equally divided into four groups randomly, distilled water (DW) group, CoQ10 group, CoQ10 combined magnesium(CM) group and magnesium (Mg) group were established by treating the preeclampsia rats on day 15 to 21 of gestation with different measures. As for all the 50 rats, systolic blood pressure (SBP) of rat tail was detected on day 10, 15 and 21 of gestation respectively, 24 hours proteinuria analysis were detected on day 10, 15 and 21 of gestation respectively, levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) in blood andsuperoxide dismutase (SOD), glutathione peroxidase (GSH-PX), malondialdehyde (MDA), caspase-3, Bcl-2 and Bax protein expression in liver tissue were detected by western blot assay on day 21 of gestation.

RESULTS

(1) SBP and 24 hours proteinuria analysis: there was no statistic difference among all the five groups on day 10 of gestation (P>0.05). Whereas, SBP and 24 hours proteinuria analysis were significantly higher in CoQ10 group, CoQ10 combined CM group, CM group and DW group than that in NP group on day 15, 21 of gestation (P<0.05). And SBP and 24 hours proteinuria analysis were significantly lower in CoQ10 group, CoQ10 combined CM group and CM group than that in DW group on day 21 of gestation (P<0.05). (2) Liver function: among CoQ10 group, CoQ10 combined CM group, CM group, DW group and NP group, serum levels of ALT were respectively (52±7) , (34±9) , (49±10) , (70±19) , (30±7) U/L; and serum levels of AST were respectively (169±25) , (84±11) , (159±20) , (281±26) and (78±18) U/L. ALT and AST serum levels were significantly higher in CoQ10 group, CM group and DW group than that in NP group (P<0.05). ALT and AST serum levels were significant lower in CoQ10 combined CM group than those in CoQ10 group, CM group and DW group, respectively (P<0.05). ALT and AST serum levels were significant lower in CoQ10 group and CM group than that in DW group, respectively (P<0.05). (3) SOD, GSH-PX, MDA, caspase-3, Bcl-2 and Bax expression in liver tissue of rats: SOD expression was significant higher in CoQ10 group, CoQ10 combined CM group than thoes in CM group, DW group and NP group (P<0.05) ; SOD expression was significant lower in CM group, DW grouo than thoes in NP group (P<0.05) ; and SOD expression was significant higher in CM group than that in DW group (P<0.05) . Compared with CoQ10 group, CoQ10 combined CM group, CW group and DW group respectively, the GSH-PX and Bcl-2 protein expressions were significant higher in NP group (P<0.05) , while MDA, caspase-3 and Bax protein expressions were significant lower in NP group (P<0.05) ; compared with CoQ10 group, CoQ10 combined CM group and CW group respectively, the GSH-PX and Bcl-2 protein expressions were significant lower in DW group (P<0.05) , while MDA, caspase-3 and Bax protein expressions were significant higher in DW group (P<0.05) .

CONCLUSIONS

Oxidative stress and apoptosis levles were upregulated in PE pregnant liver tissues. CoQ10 could effectively protect the liver by improving the liver functions and decreasing the apoptosis of liver cells in PE pregnant rats, and markedly decrease the oxidative stress and apoptosis in the livers. The protective roles of CoQ10 in liver might through its function of anti-oxidative stress and inhibiting cell apoptosis by regulating the balance of Bcl-2/Bax.

Designed nucleus penetrating thymine-capped dendrimers: a potential vehicle for intramuscular gene transfection

A nucleus penetrating vehicle is indispensible when seeking to deliver plasmid DNA for gene transfection. In this study, dendrimers with terminal thymine groups were synthesized to meet this objective. Through modifications of the hydrophilic and neutral thymine moieties on hyperbranched peripheries, these dendrimers can achieve biosafety, efficient endosomal escape ability, cytosolic accessibility, and eventually, nuclear entry for the purposes of gene transfection. After optimization of the thymine coverages, better gene expression can only be achieved while replacing ∼50% of the amine groups of a dendrimer with thymine moieties. Presumably, a specific dendrimer comprising thymine and primary amines might possess a synergistic effect to promote pDNA condensation via the cooperation of electrostatic interaction and hydrogen bonding. In comparison, a dendrimer entirely capped by thymine can lose external amines, decreasing pDNA complexity and stability, which would cause poor gene transfection. The utility of specific thymine-capped dendrimers in vivo level was demonstrated to successfully and efficiently deliver plasmid DNA at a low complex ratio into mouse muscle by intramuscular injection. Upon the easy accessibility of intramuscular administration, the capability of thymine-capped dendrimers might be potentially used in immunotherapeutic gene transfection in the future.

A novel semiconductor compatible path for nano-graphene synthesis using CBr4 precursor and Ga catalyst

We propose a novel semiconductor compatible path for nano-graphene synthesis using precursors containing C-Br bonding and liquid catalyst. The unique combination of CBr4 as precursor and Ga as catalyst leads to efficient C precipitation at a synthesis temperature of 200 °C or lower. The non-wetting nature of liquid Ga on tested substrates limits nano-scale graphene to form on Ga droplets and substrate surfaces at low synthesis temperatures of T ≤ 450 °C and at droplet/substrate interfaces by C diffusion via droplet edges when T ≥ 400 °C. Good quality interface nano-graphene is demonstrated and the quality can be further improved by optimization of synthesis conditions and proper selection of substrate type and orientation. The proposed method provides a scalable and transfer-free route to synthesize graphene/semiconductor heterostructures, graphene quantum dots as well as patterned graphene nano-structures at a medium temperature range of 400-700 °C suitable for most important elementary and compound semiconductors.

Caged Pt nanoclusters exhibiting corrodibility to exert tumor-inside activation for anticancer chemotherapeutics

We report on caged Pt nanoclusters that are able to exert tumor-inside activation for anticancer chemotherapeutics and to minimize systemic toxicity. By shrinking the Pt size to 1 nm, it possesses corrodibility for dissolution in weakly acidic organelles to release toxic Pt ions. The therapeutic effect in exerting tumor-inside activation is confirmed in vivo by post-modifying a pH-cleavable PEG corona and mixing it with a tumor-homing peptide for tumour suppression.

Differential pharmacological actions of methadone and buprenorphine in human embryonic kidney 293 cells coexpressing human μ-opioid and opioid receptor-like 1 receptors

Methadone and buprenorphine are used in maintenance therapy for heroin addicts. In this study, we compared their effects on adenylate cyclase (AC) activity in human embryonic kidney (HEK) 293 cells stably overexpressing human μ-opioid receptor (MOR) and nociceptin/opioid receptor-like 1 receptor (ORL1) simultaneously. After acute exposure, methadone inhibited AC activity; however, buprenorphine induced compromised AC inhibition. When naloxone was introduced after 30 min incubation with methadone, the AC activity was enhanced. This was not observed in the case of buprenorphine. Enhancement of the AC activity was more significant when the incubation lasted for 4 h, and prolonged exposure to buprenorphine elevated the AC activity as well. The removal of methadone and buprenorphine by washing also obtained similar AC superactivation as that revealed by naloxone challenge. The study demonstrated that methadone and buprenorphine exert initially different yet eventually convergent adaptive changes of AC activity in cells coexpressing human MOR and ORL1 receptors.

The clinicopathological behaviour and surgical treatment of abdominal Castleman's disease

INTRODUCTION

Castleman's disease, a rare atypical lymphoproliferative disorder of the lymphoid tissue with unknown cause, remains a diagnostic challenge. This study was conducted to analyse the clinicopathological behaviour and reasonable surgical treatment for patients with abdominal Castleman's disease.

METHODS

The medical records of seven patients with abdominal Castleman's disease were reviewed.

RESULTS

The patients comprised two men and five women, and their median age was 42.3 (range 29-53) years. The main clinical manifestation was an abdominal mass or an enlargement of the retroperitoneal lymph node. Other clinical manifestations included anaemia, loss of body weight and hypoalbuminaemia. The mean size of the tumour was 5.5 (range 4.0-8.0) cm. Postoperatively, all the patients were diagnosed with a hyaline vascular type of the disease, and had localised manifestations of the disease. All seven patients underwent complete surgical resection, two of whom also received adjuvant irregular chemotherapy (CHOP) and steroids postoperatively. All the patients survived, with no evidence of recurrence. One patient had survived for more than two years, four patients for more than three years, and two patients for more than five years.

CONCLUSION

Abdominal Castleman's disease is difficult to diagnose preoperatively, and surgical excision remains the treatment of choice, especially for localised disease.

Enhancement of tolerance development to morphine in rats prenatally exposed to morphine, methadone, and buprenorphine

Background

Abuse of addictive substances is a serious problem that has a significant impact on areas such as health, the economy, and public safety. Heroin use among young women of reproductive age has drawn much attention around the world. However, there is a lack of information on effects of prenatal exposure to opioids on their offspring. In this study, an animal model was established to study effects of prenatal exposure to opioids on offspring.

Methods

Female pregnant Sprague-Dawley rats were sub-grouped to receive (1) vehicle, (2) 2-4 mg/kg morphine (1 mg/kg increment per week), (3) 7 mg/kg methadone, and (4) 3 mg/kg buprenorphine, subcutaneously, once or twice a day from E3 to E20. The experiments were conducted on animals 8-12 weeks old and with body weight between 250 and 350 g.

Results

Results showed that prenatal exposure to buprenorphine caused higher mortality than other tested substance groups. Although we observed a significantly lower increase in body weight in all of the opioid-administered dams, the birth weight of the offspring was not altered in all treated groups. Moreover, no obvious behavioral abnormality or body-weight difference was noted during the growing period (8-12 weeks) in all offspring. When the male offspring received morphine injection twice a day for 4 days, the prenatally opioid-exposed rats more quickly developed a tolerance to morphine (as shown by the tail-flick tests), most notably the prenatally buprenorphine-exposed offspring. However, the tolerance development to methadone or buprenorphine was not different in offspring exposed prenatally to methadone or buprenorphine, respectively, when compared with that of the vehicle controlled group. Similar results were also obtained in the female animals.

Conclusions

Animals prenatally exposed to morphine, methadone, or buprenorphine developed tolerance to morphine faster than their controlled mates. In our animal model, prenatal exposure to buprenorphine also resulted in higher mortality and much less sensitivity to morphine-induced antinociception than prenatal exposure to morphine or methadone. This indicates that buprenorphine in higher doses may not be an ideal maintenance drug for treating pregnant women. This study provides a reference in selecting doses for clinical usage in treating pregnant heroin addicts.

Rapid detection of H5 avian influenza virus by TaqMan-MGB real-time RT-PCR

Aims:  Real‐time reverse transcription‐polymerase chain reaction (RT‐PCR) assay based on a TaqMan‐minor groove binder (MGB) probe was developed for the rapid detection of avian influenza virus subtype H5.

Methods and Results:  Conserved regions in the haemagglutinin genes of avian influenza viruses subtype H5 served as targets for the primers and TaqMan‐MGB probe design. Concentrations of primers and probe were optimized to improve the sensitivity and specificity of the reactions. A plasmid containing the haemagglutinin gene was constructed and in vitro transcribed for a quantitative assay of copy numbers of the target gene. The results revealed that the optimal concentration of primers and probe was 640 and 480 nmol l⁻¹, respectively. The threshold of 100 copies of target molecules could be detected. The linear range for detection was determined as 10² to 10⁸ molecules in reaction.

Conclusions:  It took less than 3 h to complete the detection from viral RNA extraction, with good sensitivity and repeatability.

Significance and Impact of the Study:  Real‐time RT‐PCR assay with MGB probe was an effective means for quick and quantitative laboratory detection and monitoring of H5 avian influenza viruses.

Cellular neural network analysis for two-dimensional bioheat transfer equation

The cellular neural network (CNN) method is applied to solve the Pennes bioheat transfer equation, and its feasibility is demonstrated. Numerical solutions were obtained for a cellular neural network for a two-dimensional steady-state temperature field obtained from focused and unfocused ultrasound heat sources. Transient-state temperature fields were also studied and compared with experimental results obtained elsewhere. The cellular neural networks' key features of asynchronous parallel processing, continuous-time dynamics and local interaction enable real-time temperature field estimation for clinical hyperthermia.

The chromosomal effect of birchen dust as determined by the micronucleus test

In a wood processing factory, the measured air concentration of birchen dust was 1.26 +/- 0.41 mg/m3, and the micronucleus frequency of peripheral blood lymphocytes in 83 workers exposed to wood dust was 1.13 +/- 2.83/1000, which was significantly higher (P < 0.01) than that of control group (0.51 +/- 1.41/1000). The number of exposed workers with positive micronucleus test was 9.6%, which was higher than that of control group (4.5%), but the difference was not significant (P > 0.05). The micronucleus test in mice treated with water extracts of unsteamed and unbaked birchen dust showed that the micronucleus frequencies in all treated groups were significantly higher than that of control group (P < 0.01) and there was also a dose response correlation (r = 0.96, P < 0.0005). The results of steamed and baked birchen dust extracts were significantly lower than those of the unsteamed and unbaked ones at the same doses (P < 0.001). This suggests that when the birchen dust is steamed at the temperature of 100 degrees C for 24 h or baked at the temperature of 80 degrees C, its inducing effect in micronucleus test could be lowered.

Near continuous cardiac output by thermodilution

A new thermodilution method for frequent (near continuous) estimation of cardiac output, without manual injection of fluid into the blood, was tested. The method utilizes a pulmonary artery catheter equipped with a fluid filled heat exchanger. The technique is based on cyclic cooling of the blood in the right atrium and measurement of the temperature changes in the pulmonary artery. Using this technique, a new estimate of cardiac output can be obtained every 32 s. Cardiac output estimates, obtained for a running mean of three measurements with this method, were compared to the mean of three conventional thermodilution measurements. The measurements were obtained during short periods of stable respiration and circulation. In six pigs, we made 46 paired measurements of conventional thermodilution (TD) and near continuous (TDc) thermodilution. The cardiac output (COTD) ranged from 2.4-13.7 l/min (mean 5.4 l/min). The best linear fit through the paired data points was COTDc = -0.57 + 1.01 COTD. The mean difference between the methods was -0.50 l/min (S.D. = 0.39). The mean coefficient of variation of repeated measurements with the near continuous thermodilution was 3.6%. Considering changes of more than 0.25 l/min to be significant, all changes in cardiac output measured by conventional thermodilution were followed by the running mean of three near continuous thermodilution estimates. This study demonstrates the feasibility of the new method to monitor cardiac output, and to detect all changes greater than 0.25 l/min.

The limiting mobility of DNA sequencing fragments for both cross-linked and noncross-linked polymers in capillary electrophoresis: DNA sequencing at 1200 V cm-1

The mobility of DNA sequencing fragments was measured in Long-Ranger gels at an electric field ranging from 200 to 1200 V cm-1 and in noncross-linked polyacrylamide at electric fields ranging from 100 to 300 V cm-1. In both cases, N*, the fragment length that denotes the onset of biased reptation with orientation, is inversely proportional to electric field. The inverse dependence of N* is inconsistent with the original biased reptation model but is consistent with modern models of DNA migration. While separation speed increases dramatically with electric field, the number of bases determined in a separation decreases in proportion to field strength. We present a DNA sequencing run at an electric field of 1200 V cm-1. Roughly 200 bases of sequence are determined in 3.5 min.

Internal fluorescence labeling with fluorescent deoxynucleotides in two-label peak-height encoded DNA sequencing by capillary electrophoresis

Fluorescently labeled deoxynucleotides were used for internal labeling of DNA sequencing fragments generated in a two-color peak-height encoded protocol. Sequenase and a manganese-containing buffer were used to generate uniform peak heights. Tetramethyl rhodamine - dATP was used in a labeling step, followed by termination with ddATP and ddCTP in a 3:1 ratio. Fluorescein - dATP was used in a second reaction, followed by termination with ddGTP and ddTTP in a 3:1 ratio. The fragments were pooled and separated by capillary gel electrophoresis. The results were compared with peak-height encoded sequencing based on fluorescently labeled primers. The dye-labeled primers produced higher resolution separations for shorter fragments. However, dye-labeled primer fragments suffered from an earlier onset of biased reptation and produced shorter sequencing reads. Fragments from 50 to at least 500 bases in length could be sequenced with the internal labels.

Titanium-coated Dacron velour: a study of interfacial connective tissue formation

Polyethylene terephthalate in textile form (Dacron) has been used extensively as a surgical implant material for applications such as vascular grafts and percutaneous access devices. It is moderately histocompatible eliciting a chronic inflammatory reaction predominately in tissue which has grown into the pores of the fabric. Titanium implants on the other hand, induce only the slightest inflammatory response and connective tissue adhesion to the titanium oxide surface is excellent. It was, therefore, hypothesized that a titanium coating on Dacron fabric might improve its histocompatibility while leaving its desirable mechanical properties unaffected. To test this idea, Dacron velour specimens were coated with titanium by vacuum deposition and were implanted together with uncoated controls in rabbits subcutis. After various implantation times, the specimens were recovered and the associated tissue was examined histologically. Qualitative and semiquantitative analysis revealed that tissue ingrowth quantity and quality was highly variable, not only between test and control specimens, but also between animals and even between specimens within the same animal. This indicated that there may be a number of factors influencing tissue ingrowth that were not adequately controlled in this study. The titanium coating which was undoubtedly highly oxidized had a profound qualitative and quantitative effect on fibroblast activity (ground substance formation) and fibroblast adhesion to the Dacron fibers. The results obtained after these short-term implantation periods indicate that titanium coating affects the quality of the interfacing tissue and may actually improve long-term histocompatibility. Long-term studies will have to confirm these preliminary data.