[The timing of pericardial drainage catheter removal and restart of the anticoagulation in patients suffered from perioperative pericardial tamponade during atrial fibrillation catheter ablation and uninterrupted dabigatran: Experiences from 20 cases]

Objective: To investigate the timing of pericardial drainage catheter removal and restart of the anticoagulation in patients with atrial fibrillation (AF) suffered from perioperative pericardial tamponade during atrial fibrillation catheter ablation and uninterrupted dabigatran. Methods: A total of 20 patients with pericardial tamponade, who underwent AF catheter ablation with uninterrupted dabigatran in Beijing Anzhen Hospital from January 2019 to August 2021, were included in this retrospective analysis. The clinical characteristics of enrolled patients, information of catheter ablation procedures, pericardial tamponade management, perioperative complications, the timing of pericardial drainage catheter removal and restart of anticoagulation were analyzed. Results: All patients underwent pericardiocentesis and pericardial effusion drainage was successful in all patients. The average drainage volume was (427.8±527.4) ml. Seven cases were treated with idarucizumab, of which 1 patient received surgical repair. The average timing of pericardial drainage catheter removal and restart of anticoagulation in 19 patients without surgical repair was (1.4±0.7) and (0.8±0.4) days, respectively. No new bleeding, embolism and death were reported during hospitalization and within 30 days following hospital discharge. Time of removal of pericardial drainage catheter, restart of anticoagulation and hospital stay were similar between patients treated with idarucizumab or not. Conclusion: It is safe and reasonable to remove pericardial drainage catheter and restart anticoagulation as soon as possible during catheter ablation of atrial fibrillation with uninterrupted dabigatran independent of the idarucizumab use or not in case of confirmed hemostasis.

[The relationship between fasting blood glucose level and thromboembolism events in patients with non-valvular atrial fibrillation]

Objective: To explore the relationship between fasting blood glucose level and thromboembolism events in patients with non-valvular atrial fibrillation (NVAF). Methods: This was an observational study based on data from a multicenter, prospective Chinese atrial fibrillation registry cohort, which included 18 703 consecutive patients with atrial fibrillation (AF) in 31 hospitals in Beijing from August 2011 to December 2018. Patients were divided into 5 groups according to status of comorbid diabetes and fasting glucose levels at admission: normal blood glucose (normal glucose group), pre-diabetes group, strict glycemic control group, average glycemic control group and poor glycemic control group. Patients were followed up by telephone or outpatient service every 6 months. The primary follow-up endpoint was thromboembolic events, including ischemic stroke and systemic embolism. The secondary endpoint was the composite endpoint of cardiovascular death and thromboembolic events. Kaplan-Meier survival analysis and multifactorial Cox regression were used to analyze the correlation between fasting glucose levels and endpoint events. Results: The age of 18 703 patients with NVAF was (63.8±12.0) years, and there were 11 503 (61.5%) male patients. There were 11 877 patients (63.5%) in normal blood glucose group, 2 023 patients (10.8%)in pre-diabetes group, 1 131 patients (6.0%) in strict glycemic control group, 811 patients in average glycemic control group and 2 861 patients(4.3%) in poor glycemic control group. Of the 4 803 diabetic patients, 1 131 patients (23.5%) achieved strict glycemic control, of whom 328 (29.0%) were hypoglycemic (fasting blood glucose level<4.4 mmol/L at admission). During a mean follow-up of (51±23) months (up to 82 months), thromboembolic events were reported in 984 patients (5.3%). The survival curve analysis of Kaplan Meier showed that the incidence rates of thromboembolic events in normal glucose group, pre-diabetes group, strict glycemic control group, average glycemic control group and poor glycemic control group were 1.10/100, 1.41/100, 2.09/100, 1.46/100 and 1.71/100 person-years, respectively (χ²=53.0, log-rank P<0.001). The incidence rates of composite endpoint events were 1.86/100, 2.17/100, 4.08/100, 2.58/100, 3.16/100 person-years (χ²=72.3, log-rank P<0.001). The incidence of thromboembolic events and composite endpoint events in the other four groups were higher than that in the normal blood glucose group (P<0.001). Multivariate Cox regression analysis showed that compared with normal glucose group, the risk of thromboembolism increased in pre-diabetes group(HR=1.23, 95%CI 1.00-1.51, P=0.049), strict glycemic control group(HR=1.32, 95%CI 1.06-1.65, P=0.013) and poor glycemic control group(HR=1.26, 95%CI 1.01-1.58, P=0.044). Conclusion: Both high or low fasting glucose may be an independent risk factor for thromboembolic events in patients with NVAF.

[Clinical analysis of 554 patients with colorectal diverticulosis]

Objective: Most patients with asymptomatic colorectal diverticulosis are easily overlooked. However, some of diverticulosis become diverticulitis, bleeding and even perforation, which cause extensive harm to patients. The purpose of this study is to analyze the incidence, clinical features, diagnosis and treatment of colorectal diverticulosis in order to improve the clinical understanding of diverticulosis and its related complications. Methods: A descriptive cohort study was carried out. Clinical data of 554 patients with colorectal diverticulosis confirmed by CT, colonoscopy, digestive tract radiography or operation in Peking University First Hospital from January 2009 to June 2019 were retrospectively analyzed. Patients with malignant tumors, autoimmune diseases, long term use of immunosuppressive drugs, chronic liver diseases and renal diseases, and mental disorders were excluded. The analysis parameters included gender, onset age, clinical symptoms, location of diverticulitis, treatment and prognosis. According to the criteria established by the World Society of Emergency Surgery (WSES), acute diverticulitis was divided into 5 stages based on the extension of the infectious process. Stage 0 was simple diverticulitis and stage 1-4 was complicated diverticulitis. Results: Among the 554 patients with colorectal diverticulosis, 358 (64.6%) were males, the median onset age was 63 years; 191 patients (34.5%) had various digestive symptoms, of whom 113 (20.4%) had chronic constipation and abdominal distension, 78 (14.1%) had chronic diarrhea and abdominal pain; the other 363 patients had no obvious abdominal symptoms. Four hundred and six patients were found by colonoscopy and 465 patients were found by CT. Twenty-five patients were diagnosed by lower gastrointestinal tract radiography and 3 were confirmed during operation. There were 339 patients with multiple diverticula (61.2%) and 215 patients with single diverticulum (38.8%). 76.5% (424/554) of diverticula were located in colon, 37.0% (205/554) in ascending colon, 21.3% (118/554) in multiple sites, and 2.2% (12/554) in rectum. The median diameter of diverticulum was 7 mm, and 78 cases (14.1%) was ≥30 mm. Forty-nine patients (8.8%) developed acute diverticulitis, including 13 patients with simple diverticulitis and 36 patients with complicated diverticulitis. Among 36 patients with complicated diverticulitis, 29 (80.6%) were males, 27 (75.0%) had recurrent abdominal pain and fever before onset; diverticula of 25 cases were located in sigmoid colon; 11 cases in ascending colon. Nine cases developed sigmoid colon perforation and 8 cases developed vesicocolonic fistula, and these 17 patients underwent surgical treatment. The other 19 cases with complicated diverticulitis developed gastrointestinal bleeding, of whom 18 cases were male, 11 cases were located in ascending colon; 13 cases were healed after conservative treatment, 4 cases received endoscopic hemostatic intervention, and 2 cases underwent surgery. Conclusions: Colorectal diverticulosis is more common in male patients, and CT and colonoscopy are main diagnostic methods. The symptoms of complicated colonic diverticulitis are related to the location of diverticulum. In addition to symptomatic treatment, surgical procedures are the most important treatments.

Comparison of severe and critical COVID-19 patients imported from Russia with and without influenza A infection in Heilongjiang Province: a retrospective study

Background

The rapid spread of coronavirus disease-19 (COVID-19) poses a global health emergency, and cases entering China from Russia are quite diverse. This study explored and compared the clinical characteristics and outcomes of severe and critically ill COVID-19 patients from Russia with and without influenza A infection, treated in a northern Chinese hospital (Russia imported patients).

Methods

A total of 32 severe and critically ill Russia-imported COVID-19 patients treated in the Heilongjiang Imported Severe and Critical COVID-19 Treatment Center from April 6 to May 11, 2020 were included, including 8 cases (group A) with and 24 cases (group B) without influenza A infection. The clinical characteristics of each group were compared, including prolonged hospital stay, duration of oxygen therapy, time from onset to a negative SARS-CoV-2 qRT-PCR RNA (T_neg) result, and duration of bacterial infection.

Results

The results showed that blood group, PaO₂/FiO₂, prothrombin time (PT), prothrombin activity (PTA), computed tomography (CT) score, hospital stay, duration of oxygenation therapy, T_neg, and duration of bacterial infection were statistically different between the two groups (P<0.05). Multivariant regression analysis showed that the Sequential Organ Failure Assessment (SOFA) score, C-reactive protein (CRP), and influenza A infection were factors influencing hospital stay; SOFA score, CRP, and CT score were factors influencing the duration of oxygenation therapy; PaO₂/FiO₂, platelet count (PLT), and CRP were factors influencing T_neg; and gender, SOFA score, and influenza A infection were factors influencing the duration of bacterial infection.

Conclusions

Influenza A infection is common in Russia-imported COVID-19 patients, which can prolong the hospital stay and duration of bacterial infection. Routinely screening and treating influenza A should be conducted early in such patients.

[Thirty years' changes of the strategy of lateral lymph node dissection in low rectal cancer: treatment experience and prognostic analysis of 289 cases in one single center]

Objective: The surgical indications, resection extent and management principle of lateral lymph node dissection (LLND) in lower rectal cancer have been controversial between Eastern and Western countries. This study aims to provide a theoretical basis for the rational implementation of LLND by reviewing the changes of LLND strategy over the past 30 years in a single-center, and analyzing prognostic factors for the survival outcomes of patients with lateral lymph node metastasis (LLNM). Methods: A retrospective observational study was performed. Clinical data of 289 patients with rectal cancer who received LLND at the Department of General Surgery of Peking University First Hospital from 1990 to 2019 were collected. Patients were divided into three groups based on decades. There were 89 cases in 1990-1999 group, 92 cases in the 2000-2009 group, and 108 cases in the 2010-2019 group. Data analyzed: (1) patient baseline data; (2) surgery and postoperative recovery; (3) lateral lymph node dissection; (4) postoperative survival and prognosis of patients with positive lateral lymph nodes. The surgical methods and pathological results of LLND were compared between groups, and the prognostic risk factors of patients with LLNM were analyzed. Results: A total of 289 patients underwent radical resection with LLND' accounting for 6.3% of the 4542 patients with rectal cancer during the same period in our hospital. Except decade-by-decade increase in tumors with distance from anal verge ≤ 7 cm, the proportion of ulcerated tumors, and the proportion of neoadjuvant radiochemotherapy, the differences in other baseline data were not statistically significant among 3 decade groups (all P>0.05). The proportion of LLND in the 3 groups decreased decade by decade [9.9% (89/898) vs. 8.0% (92/1154) vs. 4.3% (108/2490), χ(2)=40.159, P<0.001]. The proportion of laparoscopic surgery and unilateral LLND increased, while the mean operative time, intraoperative blood loss, surgical complications above grade III and postoperative hospital stay decreased decade by decade. These 289 patients completed a total of 483 lateral dissections, including 95 cases of the unilateral dissection and 194 cases of the bilateral dissection. The proportion of LLND in the 3 groups decreased decade by decade [9.9% (89/898) vs. 8.0% (92/1154) vs. 4.3% (108/2510), P<0.001]. The median number of dissected lymph nodes in the internal iliac artery and obturator regions increased (2 vs. 3 vs. 3, P<0.001), but those in the common iliac and external iliac regions decreased significantly (4 vs. 3 vs. 2, P=0.014). A total of 71 patients with LLNM were identified. The rate of LLNM in the 2010-2019 group was significantly higher than that in the previous two groups [37.0% (40/108) vs. 16.9% (15/89) vs. 17.4% (16/92), P=0.001]. The patients with LLNM showed a poorer overall survival (OS) and disease-free survival (DFS) compared with negative lateral lymph nodes (P<0.001). There were statistically significant differences in 5-year OS rate (30.9% vs. 27.2% vs. 0, P=0.028) and 5-year DFS rate (28.3% vs. 16.0% vs. 0, P=0.038) among patients with only internal iliac lymph node metastasis, patients with only obturator lymph node metastasis, and patients with external iliac or common iliac lymph node metastasis. Multivariate analysis of prognostic factors showed that external iliac or common iliac lymph node metastasis was an independent risk factor for OS (HR=1.649, 95%CI: 1.087-2.501) and DFS (HR=1.714, 95%CI: 1.173-2.504) in patients with LLNM (all P<0.05) . The OS and DFS were not significant different in patients with LLNM among 3 decade groups. Conclusions: In the past decade, the proportion of LLND in rectal cancer has decreased significantly. However, LLNM rate has been significantly increased due to preoperative imaging assessments focusing on suspicious LLNM without compromising the survival. Internal iliac artery and obturator lymph nodes can be regarded as regional lymph nodes with a satisfactory prognosis after LLND. For suspected external iliac or common iliac lymph node metastasis, the significance of LLND remains to be further evaluated.

[Design, screening and antibacterial activity evaluation of the novel antibacterial peptide KR-1]

OBJECTIVE

To design novel antimicrobial peptides with high activity and low toxicity and evaluate their effect against Streptococcus mutans and other oral bacteria for prevention and treatment of dental caries.

OBJECTIVE

We synthesized two antimicrobial peptides (KR-1 and KR-2) using Dhvar4 (a histatins5 mimic) as the template. The antimicrobial peptides with high activity and low toxicity were screened using minimal inhibitory concentration (MIC) test, hemolysis test, and CCK-8 assay. Streptococcus mutans biofilms cultured in 96-well plates were divided into experimental group (KR-1) and positive control group (CHX) and treated with concentration gradients (0.6×, 0.8×, 1× and 2× MICs) of KR-1 and CHX, respectively. Crystal violet staining was used for quantitative analysis of the changes of the biofilms after the treatments. The structural changes of the biofilms were observed with laser confocal microscopy after KR-1 treatment at 10 × MIC. The antimicrobial activity of KR-1 against oral Streptococcus was analyzed based on the time required for sterilization after KR-1 treatment.

OBJECTIVE

The MIC of KR-1 and KR-2 for S. mutans was 3.2 μmol/L and 12.8 μmol/L, respectively. Under the effective concentration, KR-1 and KR-2 resulted in hemolysis rates of 0.35% and 48.8% in rabbit red blood cells and lowered the survival rates of gingival fibroblasts to 88.7% and 21.94%, respectively. KR-1 treatment significantly reduced biofilm formation with a minimum biofilm inhibition concentration (MBIC₅₀) lower than 1.92 μmol/L, and showed an even stronger antimicrobial than CHX at the concentration of 2.56 μmol/L (P=0.001). Confocal laser scanning microscopy revealed that the biofilm structure became loosened after KR-1 treatment, which was capable of killing about 90% of the bacteria within 5 min.

OBJECTIVE

The antimicrobial peptide KR-1 has a stronger antibacterial activity and a low toxicity with a good inhibitory effect against S. mutans biofilm.

Acute right ventricular dysfunction in severe COVID-19 pneumonia

To investigate the right heart function in coronavirus disease 2019 (COVID-19) patients with acute respiratory distress syndrome (ARDS), a retrospective analysis of 49 COVID-19 patients with ARDS was performed. Patients were divided into severe group and critically-severe group according to the severity of illness. Age-matched healthy volunteers were recruited as a control group. The cardiac cavity diameters, tricuspid annular plane systolic excursion (TAPSE), tricuspid valve regurgitation pressure gradient biggest (TRPG), pulmonary arterial systolic pressure (PASP), maximum inferior vena cava diameter (IVCmax) and minimum diameter (IVCmin), and inferior vena cava collapse index (ICV-CI) were measured using echocardiography. We found that the TAPSE was significantly decreased in pneumonia patients compared to healthy subjects (P < 0.0001), and it was significantly lower in critically-severe patients (P = 0.0068). The TAPSE was less than 17 mm in three (8.6%) severe and five (35.7%) critically-severe patients. In addition, the TAPSE was significantly decreased in severe ARDS patients than in mild ARDS patients. The IVCmax and IVCmin were significantly increased in critically-severe patients compared to healthy subjects and severe patients (P < 0.01), whereas the ICV-CI was significantly decreased (P < 0.05). COVID-19 patients had significantly larger right atrium and ventricle than healthy controls (P < 0.01). The left ventricular ejection fraction (LVEF) in critically-severe patients was significantly lower than that in severe patients and healthy controls (P < 0.05). Right ventricular function was impaired in critically-severe COVID-19 patients. The assessment and protection of the right heart function in COVID-19 patients should be strengthened.

Quantitative trait loci (QTL) associated with resistance of rainbow trout Oncorhynchus mykiss against the parasitic ciliate Ichthyophthirius multifiliis

The parasitic ciliate Ichthyophthirius multifiliis has a low host specificity eliciting white spot disease (WSD) in a wide range of freshwater fishes worldwide. The parasite multiplies rapidly whereby the infection may reach problematic levels in a host population within a few days. The parasite targets both wild and cultured fish but the huge economic impact of the protozoan is associated with mortality, morbidity and treatment in aquacultural enterprises. We have investigated the potential for genetic selection of WSD-resistant strains of rainbow trout. Applying the DNA typing system Affymetrix® and characterizing the genome of the individual fish by use of 57,501 single nucleotide polymorphisms (SNP) and their location on the rainbow trout chromosomes, we have genetically characterized rainbow trout with different levels of natural resistance towards WSD. Quantitative trait loci (QTL) used for the selection of breeders with specific markers for resistance are reported. We found a significant association between resistance towards I. multifiliis infection and SNP markers located on the two specific rainbow trout chromosomes Omy 16 and Omy 17. Comparing the expression of immune-related genes in fish-with and without clinical signs-we recorded no significant difference. However, trout surviving the infection showed high expression levels of genes encoding IgT, T-cell receptor TCRβ, C3, cathelicidins 1 and 2 and SAA, suggesting these genes to be associated with protection.

Clinical characteristics of patients with COVID-19 presenting with gastrointestinal symptoms as initial symptoms: Retrospective case series

BACKGROUND

A large number of pneumonia cases due to coronavirus disease 2019 (COVID-19) have been first reported in China. Meanwhile, the virus is sweeping all around the world and has infected millions of people. Fever and pulmonary symptoms have been noticed as major and early signs of infection, whereas gastrointestinal symptoms were also observed in a significant portion of patients. The clinical investigation of disease onset was underestimated, especially due to the neglection of cases presenting with gastrointestinal symptoms.

AIM

To characterize the clinical features of coronavirus-infected patients with gastrointestinal symptoms as initial symptoms.

METHODS

This is a retrospective, single-center case series of the general consecutive hospitalized patients with confirmed COVID-19 at Wuhan Union Hospital from February 2, 2020 to February 13, 2020. According to their initial symptoms, these patients were classified into two groups. Patients in group one presented with pulmonary symptoms (PS) as initial symptoms, and group two presented with gastrointestinal symptoms (GS). Epidemiological, demographic, clinical, laboratory, and treatment data were collected for analysis.

RESULTS

Among the 50 patients recruited, no patient has been admitted to intensive care units, and no patient died during the study. The duration of hospitalization was longer in the GS group than in the PS group (12.13 ± 2.44 vs 10.00 ± 2.13, P < 0.01). All of the 50 patients exhibited decreased lymphocytes. However, lymphocytes in the GS group were significantly lower compared to those in the PS group (0.94 ± 0.06 vs 1.04 ± 0.15, P < 0.01). Procalcitonin and hs-CRP were both significantly higher in the GS group than in the PS group. Accordingly, the duration of viral shedding was significantly longer in the GS group compared to the PS group (10.22 ± 1.93 vs 8.15 ± 1.87, P < 0.01).

CONCLUSION

COVID-19 patients presenting with gastrointestinal symptoms as initial symptoms need more days of viral shedding and hospitalization than the patients presenting with pulmonary symptoms.

[Evaluation of inferior mesenteric vessel and ureter by contrast-enhanced abdominal pelvic CT and its clinical influence on laparoscopic rectal surgery]

Objective: To assess the anatomic relationship of inferior mesenteric artery (IMA)/inferior mesenteric vein (IMV) with ureter by contrast-enhanced abdominal pelvic CT, in order to provide guidance for vascular management and ureteral protection in laparoscopic rectal surgery. Methods: A retrospective cohort study was conducted. Image data of contrast-enhanced abdominal pelvic CT at Department of Medical Radiography of Peking University First Hospital in November 2018 were enrolled. Exclusion criteria: (1) previous history of abdominal or pelvic surgery; (2) scoliosis deformities; (3) missing images; (4) minors; (5) inferior mesenteric vascular disease or tumor involvement resulting in suboptimal imaging; (6) poor image quality. Finally, contrast-enhanced abdominal pelvic CT data of 249 cases were collected, including 120 males and 129 females with mean age of (60.1±13.4) years. Multi-planar reconstruction (MPR) and maximum intensity projection (MIP) were used to evaluate the anatomic relationship of IMA/IMV with ureter. IMA root location, IMA length, branch types of IMA, distance between major branches, distance between IMA/IMV and ureter at the level of root of IMA, left colic artery (LCA) root, abdominal aortic bifurcation, and sacral promontory were measured and association between IMA/IMV and ureter site was summarized. Results: The distance from IMA root to the aortic bifurcation and sacral promontory was (42.0±8.5) mm and (101.8±14.0) mm, respectively. The length of IMA was (38.5±10.7) mm. The proportion of IMA roots locating at levels of the 2nd, 3rd, and 4th lumbar vertebra was 3.2% (8/249), 79.5% (198/249), and 17.3% (43/249), respectively. The higher the level of the lumbar vertebra, the longer the IMA [length of IMA originating from the 2nd, 3rd, 4th lumbar vertebra level: (42.4±10.9) mm, (39.5±10.4) mm, (33.0±10.9) mm, respectively; F=7.48, P<0.001]. In 111 cases (44.6%), LCA arose independently from IMA (type 1), and the distance between LCA and the first branch of sigmoid artery (SA) was (15.0±7.4) mm; in 56 cases (22.5%), LCA and SA had a common trunk (type 2), with a length of (11.0±8.5) mm; in 78 cases (31.3%), LCA branched with SA at the same point (type 3); LCA was absent in 4 cases (1.6%)(type 4). The length of IMA in LCA-deficient type 4 was (54.8±18.0) mm, which was longer than (38.2±10.5) mm in LCA-presence type (type 1, type 2 and type 3) and the difference was statistically significant (t=-3.11, P=0.002). The distance between the ureter and IMA was the longest at the level of IMA root [(35.7±8.1) mm], was the shortest at the level of the aortic bifurcation [(22.4±6.4) mm], and the distance between the ureter and IMA in different planes was significantly different (F=185.70, P<0.001). The distance between the ureter and IMV was the longest at the level of the sacral promontory [(21.1±9.0) mm], was the shortest at the level of LCA root [(12.0±5.7) mm], whose difference was also statistically significant (F=87.66, P<0.001). Conclusions: CT post-processing techniques including MPR and MIP can efficiently and accurately assess the branch types of IMA and anatomical relationship between IMA/IMV and ureter, and provide insights into laparoscopic rectal surgery for surgeons. IMA/IMV and ureter depart farthest at the level of IMA root. Artery first and plane second strategy in the middle approach of laparoscopic rectal surgery is considerable and feasible.

CX3CR1 participates in pulmonary angiogenesis in experimental hepatopulmonary syndrome mice through inhibiting AKT/ERK signaling pathway and regulating NO/NOS release

OBJECTIVE

Hepatopulmonary syndrome (HPS) is a kind of pulmonary microvascular disease and occurs in 15%-30% cirrhosis. This study aimed to investigate the effects of pulmonary CX3CR1 on angiogenesis and associated mechanisms in HPS animal models.

MATERIALS AND METHODS

CX3CR1GFP/GFP mice were constructed by replacing CX3CR1 with GFP. Common bile duct ligation (CBDL) mouse model was established with surgery. Release of nitric oxide (NO) was evaluated. Hematoxylin-eosin (HE) staining was employed to examine the inflammation of lung tissues. CD31 expression was detected with immunohistochemistry assay. Western blotting was used to evaluate the expression of CX3CL1, CX3CR1, phosphorylated-AKT (p-AKT), phosphorylated-ERK (p-ERK). Quantitative Real Time-PCR (qRT-PCR) assay was used to examine VEGF, PDGF, iNOS, eNOS, and HO-1 expression.

RESULTS

CX3CR1-deficiency (CX3CR1GFP/GFP-sham or CX3CR1GFP/GFP-CBDL mice) significantly reduced NO release compared to wide type (WT)-mice or WT-CBDL mice (p<0.05). CX3CR1-deficiency significantly alleviated inflammation compared to wide type (WT)-mice or WT-CBDL mice (p<0.05). CX3CR1-deficiency significantly reduced CD31 expression compared to WT-sham and WT-CBDL mice, respectively (p<0.05). CX3CR1 also participated in anti-angiogenesis efficacy of Bevacizumab. CX3CR1-deficiency significantly down-regulated the ratio of p-AKT/AKT and p-ERK/ERK and inhibited the secretion of VEGF and PDGF compared to WT-mice (p<0.05). CX3CR1-deficiency significantly reduced iNOS, eNOS, and HO-1 expression compared to WT-mice (p<0.05).

CONCLUSIONS

CX3CR1 deficiency reduced VEGF and PDGF production, inhibited p-AKT, and p-ERK activation and down-regulated iNOS, eNOS, and HO-1 expression. Therefore, CX3CR1 participates in pulmonary angiogenesis in the experimental HPS mice via inhibiting AKT/ERK signaling pathway and regulating NO/NOS release. These findings would provide a potential insight for clarifying the pathological mechanisms of HPS.

Extrusion of Contracaecum osculatum nematode larvae from the liver of cod (Gadus morhua)

Baltic cod livers have during recent years been found increasingly and heavily infected with third-stage larvae of Contracaecum osculatum. The infections are associated with an increasing population of grey seals which are final hosts for the parasite. Heavy worm burdens challenge utilization and safety of the fish liver products, and technological solutions for removal of worms are highly needed. We investigated the attachment of the worm larvae in liver tissue by use of histochemical techniques and found that the cod host encapsulates the worm larvae in layers of host cells (macrophages, fibroblasts) supported by enclosures of collagen and calcium. A series of incubation techniques, applying compounds targeting molecules in the capsule, were then tested for their effect to induce worm escape/release reactions. Full digestion solutions comprising pepsin, NaCl, HCl and water induced a fast escape of more than 60% of the worm larvae within 20 min and gave full release within 65 min but the liver tissue became highly dispersed. HCl alone, in concentrations of 48 and 72 mM, triggered a corresponding release of worm larvae with minor effect on liver integrity. A lower HCl concentration of 24 mM resulted in 80% release within 35 min. Water and physiological saline had no effect on worm release, and 1% pepsin in water elicited merely a weak escape reaction. In addition to the direct effect of acid on worm behaviour it is hypothesised that the acid effect on calcium carbonate in the encapsulation, with subsequent release of reaction products, may contribute to activation of C. osculatum larvae and induce escape reactions. Short-term pretreatment of infected cod liver and possibly other infected fish products, using low acid concentrations is suggested as part of a technological solution for worm clearance as low acid concentrations had limited macroscopic effect on liver integrity within 35 min.

Clinical application of intra-aortic balloon pump in patients with cardiogenic shock during the perioperative period of cardiac surgery

Intra-aortic balloon pumps (IABP) have saved many patients with cardiogenic shock during the perioperative period of cardiac surgery. However, the ideal insertion timing is controversial. In the present study, we aimed to optimize the insertion timing, in order to increase the survival rate of the patients. A total of 197 patients with cardiogenic shock during the perioperative period of cardiac surgery and implemented IABP from January 2011 to October 2015 were selected for the study. Patients were divided into five groups on the basis of application timing of IABP: 0–60, 61–120, 121–180, 181–240 and >240 min. The 30-day mortality, application rate of continuous renal replacement therapy (CRRT), duration of mechanical ventilation, duration of hospital stay and hospitalization charges were analyzed in the above groups. The risk factors related to mortality and the occurrence of IABP complications were also analyzed. The mortality in the 0–60, 61–120, 121–180, 181–240 and >240 min groups were 42.17, 36.6, 77.3, 72.7 and 79.3%, respectively. Earlier IABP insertion resulted in less patients receiving CRRT from acute renal failure and less daily hospitalization charges. However, the IABP application timing had no effect on indexes such as hospitalization duration, duration of mechanical ventilation and total hospitalization charges. Multifactor logistic regression analysis indicated that the independent risk factors of death in patients with cardiogenic shock during cardiac surgery were related to IABP support timing and vasoactive-inotropic score (VIS) before balloon insertion. In the first 120 min of cardiogenic shock during the perioperative period of cardiac surgery, IABP application decreased 30-day mortality. Mortality was related with VIS score of patients, which can be used to predict the prognosis of patients with cardiogenic shock.

Potential Interactions Between Genetic Polymorphisms of the Transforming Growth Factor-β Pathway and Environmental Factors in Abdominal Aortic Aneurysms

OBJECTIVE/BACKGROUND

Evidence has accumulated that multiple polymorphisms in the transforming growth factor (TGF)-β pathway and renin-angiotensin system play important roles in determining susceptibility to abdominal aortic aneurysm (AAA). Few studies have considered interactions between these gene polymorphisms and environmental factors. The aim of this study was to evaluate the contribution of single nucleotide polymorphisms (SNPs) and complex gene-environment interactions in AAA.

METHODS

Six SNPs located in TGFB, TGFBR1, TGFBR2 and AGTR1 were selected. Genotyping of blood samples and collection of lifestyle factors were performed in 155 unrelated participants with AAAs and 310 non-AAA controls. Unconditional logistic regression was performed to assess the effects of SNPs on the risk of AAA. Generalized multifactor dimensionality reduction (GMDR) was used to evaluate gene-gene and gene-environment interactions.

RESULTS

Participants carrying TGFB1 rs1800469 TT (odds ratio [OR] 1.83, 95% confidence interval [CI] 1.18-2.85) or AGTR1 rs12695895 TT (OR 4.21, 95% CI 1.41-12.53) genotypes had a higher risk of AAA than those with the common CC genotype. The gene-gene interaction of AGTR1 rs5182, TGFBR1 rs1626340, and TGFB1 rs1800469 was found to be the best model according to the results of the GMDR analysis (cross validation consistency [CVC]) 10/10; p = .010). Smoking, dyslipidemia, and rs1800469 together contributed to the risk of AAA, which demonstrated a potential and complex gene-environment interaction among the three variants that might affect AAA risk (CVC 6/10; p = .001).

CONCLUSION

In this study of the Chinese population, homozygosity of TGFB1 rs1800469-T and AGTR1 rs12695895-T might be associated with increased risk of AAA. The complex gene-gene and gene-environment interactions might contribute to the risk of AAA. As a small study, the preliminary results need extensive validation and replication in larger populations.

Prospective feasibility study on the use of multiband mucosectomy for endoscopic resection of early squamous neoplasia in the esophagus

BACKGROUND AND STUDY AIMS

Endoscopic resection for esophageal squamous high-grade intraepithelial neoplasia (HGIN) or intramucosal cancer (esophageal squamous cell carcinoma [ESCC]) with the endoscopic resection cap technique is technically difficult, and requires submucosal lifting and multiple snares for piecemeal resections. Multiband mucosectomy (MBM) is an easy-to-use endoscopic resection technique and may be the modality of choice in China, where ESCC is extremely prevalent. The aim of the current study was to prospectively evaluate MBM for piecemeal endoscopic resection of squamous neoplasia of the esophagus.

METHODS

Patients with HGIN/ESCC and no signs of submucosal invasion or metastatic disease were included in the study. Lesions were delineated using electrocoagulation and resected using the MBM technique. Endpoints were procedure time, endoscopic radicality, complications, histology of the endoscopic resection specimens, and absence of HGIN/ESCC at the endoscopic resection scar during follow-up.

RESULTS

A total of 41 patients (26 male; mean age 61 years) underwent MBM; all lesions were visible with white light endoscopy (median length 5 cm, interquartile range [IQR] 4 - 6 cm; median circumferential extent 42 %, IQR 25 - 50 %). Median procedure time was 12 minutes (IQR 8 - 24 minutes). Median number of resections was 5 (IQR 3 - 6). Endoscopic complete resection was achieved in all lesions. There was one perforation, which was treated by application of clips. No other complications were observed. The worst histology was ESCC (n = 19), HGIN (n = 17), middle grade intraepithelial neoplasia (n = 4), and normal squamous epithelium (n = 1). Endoscopic follow-up at 3 months showed HGIN at the endoscopic resection scar in two patients, which was effectively treated endoscopically, and showed normal squamous epithelium in all patients at final follow-up (median 15 months, IQR 12 - 24 months).

CONCLUSION

This first prospective study on MBM for piecemeal endoscopic resection of early esophageal squamous neoplasia showed that MBM was effective for the complete removal of lesions with short procedure time, few complications, effective histological assessment of resected specimens, and durable treatment effect.

[Value of Gallium-67 scanning in differentiation of malignant and benign tumor in oral and maxillofacial area]

OBJECTIVE

To evaluate Gallium-67 scanning in differentiation of malignant and benign tumor in oral and maxillofacial region.

METHODS

41 patients with tumors in the oral and maxillofacial region were undergone Gallium-67 scanning. The results were correlated with the final pathologic diagnosis.

RESULTS

Twenty out of 21 patients who had malignant tumors showed positive Gallium-67 scanning images (95.23%); three of 20 patients who had benign tumors also demonstrated positive results (15.00%). There was a significant difference between these two groups (P < 0.001).

CONCLUSIONS

Gallium-67 scanning is a useful adjunct tool for differentiation of malignant and benign tumors in oral and maxillofacial region.

Fidelity of eucaryotic DNA polymerase delta holoenzyme from Schizosaccharomyces pombe

The fidelity of Schizosaccharomyces pombe DNA polymerase delta was measured in the presence or absence of its processivity subunits, proliferating cell nuclear antigen (PCNA) sliding clamp and replication factor C (RFC) clamp-loading complex, using a synthetic 30-mer primer/100-mer template. Synthesis by pol delta alone was distributive. Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP. "Passive" self-loading of PCNA onto DNA takes place in the absence of RFC, in an ATP-independent reaction, which was strongly inhibited by SSB. The nucleotide substitution error rate for pol delta holoenzyme (HE) (pol delta + PCNA + RFC) was 4.6 x 10(-4) for T.G mispairs, 5.3 x 10(-5) for G.G mispairs, and 4.5 x 10(-6) for A.G mispairs. The T.G misincorporation frequency for pol delta without the accessory proteins was unchanged. The fidelity of pol delta HE was between 1 and 2 orders of magnitude lower than that measured for the E. coli pol III HE at the same template position. This relatively low fidelity was caused by inefficient proofreading by the S. pombe polymerase-associated proofreading exonuclease. The S. pombe 3'-exonuclease activity was also extremely inefficient in excising primer-3'-terminal mismatches in the absence of dNTP substrates and in hydrolyzing single-stranded DNA. A comparison of pol delta HE with E. coli pol IIIalpha HE (lacking the proofreading exonuclease subunit) showed that both holoenzymes exhibit similar error rates for each mispair.

In vitro reconstitution of the Schizosaccharomyces pombe alternative excision repair pathway

Schizosaccharomyces pombe alternative excision repair has been shown genetically and biochemically to be involved in the repair of a wide variety of DNA lesions. AER is initiated by a damage-specific endonuclease (Uve1p) that recognizes UV-induced photoproducts, base mispairs, abasic sites, and platinum G-G diadducts and cleaves the DNA phosphodiester backbone 5' to a lesion. Several models exist that employ various mechanisms for damage removal based on the activities of Rad2p, a nuclease thought to be responsible for damage excision in AER. This study represents the first report of the biochemical reconstitution of the AER pathway. A base mispair-containing substrate is repaired in a reaction requiring S. pombe Uve1p, Rad2p, DNA polymerase delta, replication factor C, proliferating cell nuclear antigen, and T4 DNA ligase. Surprisingly, damage is removed exclusively by the 5' to 3' exonuclease activity of Rad2p and not its "flap endonuclease" activity and is absolutely dependent upon the presence of the 5'-phosphoryl moiety at the Uve1p cleavage site.

Structure and activity associated with multiple forms of Schizosaccharomyces pombe DNA polymerase delta

DNA polymerase delta (Pol delta) isolated from Schizosaccharomyces pombe (sp) consists of at least four subunits, Pol3, Cdc1, Cdc27, and Cdm1. We have reconstituted the four-subunit complex by simultaneously expressing these polypeptides in baculovirus-infected insect cells. The properties of the purified cloned spPol delta were identical to the native spPol delta isolated from S. pombe cells. In addition, we also isolated a three-subunit complex containing Pol3, Cdc1, and Cdm1. Both three- and four-subunit complexes required replication factor C and proliferating cell nuclear antigen for DNA replication. However, in the presence of low levels of polymerase complexes, the three-subunit complex was less efficient than the four-subunit complex in supporting DNA replication. The inefficient synthesis of DNA by the three-subunit complex can be remedied by the addition of Cdc27, the subunit missing in the three-subunit complex. Gel filtration analysis demonstrated that the three-subunit complex is a monomer of the heterotrimer (Pol3, Cdc1, and Cdm1) and that the four-subunit complex is a dimer of the heterotetramer (Pol3, Cdc1, Cdc27, and Cdm1), similar to the structure of native spPol delta. We have further shown that Cdc1 and Cdc27 interact to form a heterodimeric complex. Gel filtration studies indicate that the structure of this complex is dimeric. These observations suggest that the Cdc27 subunit may play an important role contributing to the dimerization of Pol delta.

Involvement of Shc and Cbl-PI 3-kinase in Lyn-dependent proliferative signaling pathways for G-CSF

Granulocyte colony-stimulating factor (G-CSF) is the major hematopoietic factor which controls the production and differentiation of granulocytes. The G-CSF receptor (G-CSFR) belongs to the superfamily of the cytokine receptors, which transduce signals via the activation of cytosolic protein tyrosine kinases (PTK). To determine the role of specific PTK in G-CSF signaling we expressed the human G-CSFR in cell lines derived from DT40 B cells, which lack either the Src-related Lyn or Syk. Wild-type (wt) and syk-deficient cells underwent increased DNA synthesis in response to G-CSF; lyn-deficient cells did not. The purpose of these studies is to identify Lyn's downstream effectors in mediating DNA synthesis. While G-CSF stimulated Ras activity in all cell lines, G-CSF failed to induce the tyrosine phosphorylation of Shc in lyn-deficient cells. G-CSF induced a statistically significant activation of Erk1/Erk2 Kinase or p90Rsk only in the wt cells. G-CSF induced the tyrosine phosphorylation of Cbl and increased activity of PI 3-kinase in wild-type and syk-deficient, but non in lyn-deficient, cells. Inhibition of Shc by over-expression of its SH2 or PTB domains or PI 3-kinase by either treatment with wortmannin or expression of the CblY731F mutant decreased G-CSF-induced DNA synthesis. Thus, the Lyn, Cbl-PI 3-kinase, and Shc/non-Ras-dependent pathways correlate with the ability of cells to respond to G-CSF with increased DNA synthesis.

The C-terminal region of Schizosaccaromyces pombe proliferating cell nuclear antigen is essential for DNA polymerase activity

Proliferating cell nuclear antigen (PCNA), the processivity factor (sliding clamp) of DNA polymerases (Pols), plays essential roles in DNA metabolism. In this report, we examined the functional role of the C-terminal region of Schizosaccaromyces pombe PCNA both in vitro and in vivo. The deletion or Ala substitution of the last 9 aa (252-260A), as well as Ala replacement of only 4 aa (252-255A) at the C terminus, failed to substitute for the wild-type PCNA protein for cell growth in S. pombe. Two other PCNA mutant proteins, A251V and K253E, exhibited cold-sensitive phenotypes. Several yeast strains harboring mutations, including those at the acidic C-terminal region, showed elevated sensitivity to DNA damage. The ability of the mutant PCNA proteins to stimulate DNA synthesis by Poldelta and Polepsilon also was studied in vitro. The mutant proteins that did not support cell growth and a mutant protein containing a single amino acid substitution at position 252, where Pro is replaced by Ala, stimulated Poldelta and Polepsilon activities poorly. All mutant PCNA proteins, however, were assembled around DNA by the clamp loader, replication factor C, efficiently. Thus, the C-terminal region of PCNA is important for interactions with both Poldelta and Polepsilon and for cell survival after DNA damage. The C terminus of sliding clamps from other organisms has been shown to be important for clamp loading as well as polymerase interactions. The relationship between the conserved sequence in this region in different organisms is discussed.

A novel serological technique: polymerase chain reaction enhanced immunoassay. Application to enterovirus IgM diagnosis

The polymerase chain reaction (PCR) method is a sensitive, specific and rapid technique for virus detection. The principles of a PCR enhanced immunoassay (PIA) are described. The method combines solid phase serological techniques with the PCR, providing a versatile and sensitive method for antibody detection. By linking the antigenicity of virus particles with their content of nucleic acid, the method provides new possibilities for virus serology: for example, antibody specificity can be coupled to viral sequence in patients with chronic infections caused by highly variable viruses such as HIV and HCV. An application of the PIA technique is described for the detection of anti-enterovirus IgM. IgM is captured to anti-human IgM-coated microwell plates. The anti-enterovirus IgM is allowed to bind crude enterovirus antigen. Bound virus is heat denatured and the released RNA is used as a template for reverse transcription PCR (RT-PCR) amplification. Amplicons are detected by hybridisation to an affinity labelled probe in a microwell colorimetric assay. In a pilot study, 18 serum specimens from patients with enterovirus infections were examined. Using a mixture of ten crude enterovirus antigens, the frequency of IgM positivity was 6/18 (33%). Titres between 1/500 and 1/100,000 were recorded. Predominantly type-specific antibodies were detected. The results were compared with a procapsid enterovirus radioimmunoassay (RIA). After further optimisation, the PIA has the potential to be a clinically useful assay for the detection of antiviral antibodies.

Therapeutic targeting of Src-kinase Lyn in myeloid leukemic cell growth

Protein tyrosine kinases play a major role in promoting cell growth, and their activity in solid tumors is well established. Inhibitors of protein tyrosine kinases are now in advanced clinical trials for the treatment of breast and brain cancers. Because Src-related PTK have been shown to be activated in leukemic cell lines, we studied their activation in human myeloid leukemia. Blasts from the majority of patients with acute leukemia showed constitutive activity of the Src kinase Lyn. In contrast, no patient samples showed constitutive activation of Jak2. Genetic and pharmacologic targeting of Lyn was used to determine its contribution to leukemic cell growth. Antisense Lyn oligonucleotide treatment resulted in the inhibition of tritiated thymidine incorporation following GM-CSF stimulation of the factor-dependent line MO7e. The Src kinase inhibitor PD166285 inhibited the growth of human leukemic cell lines and leukemic blasts. When combined with doxorubicin, an additive effect on the inhibition of leukemic cell growth occurred. These studies demonstrate the importance of Src kinases in promoting leukemic cell growth and suggests that further development of agents which target Src kinases and their inclusion in multidrug regimens are warranted for novel therapies of myeloid leukemia.

[The value of diagnosis with technetium-99m sequential scintigraphy of parotid gland in Sjögren's syndrome]

OBJECTIVE

To explore the value of diagnosis with 99mTcO4- sequential scintigraphy of parotid gland in Sjögren's syndrome.

METHODS

Technetium-99m(99mTcO4-) sequential scintigraphy was used in 52 cases of Sjögren's syndrome.

RESULTS

The results were analysed quantitatively with activity curve by using ROI computer program. 46 cases (88.46%) were parotid swelling. The contour was clear in 28 cases (53.85%) and blurred in 18 cases (34.62%). The function of parotid was normal in 7 cases (13.46%), parotids with light damage in 15 cases (28.84%), parotids with middle damage in 17 cases (32.69%), and parotids with serious damage in 13 cases (25%). Most cases of damaged secretary function was present in the early phase, and a few cases of damaged absorption function was found in the following process.

CONCLUSION

99mTcO4- sequential scintigraphy of parotid gland is greatly valuable to diagnosis of Sjögren's syndrome.

Requirement of Src kinase Lyn for induction of DNA synthesis by granulocyte colony-stimulating factor

Treatment of cells with granulocyte colony-stimulating factor (G-CSF) leads to tyrosine phosphorylation of cellular proteins. G-CSF stimulates both the activation of protein tyrosine kinases Lyn, Jak1, and Jak2 and the association of these enzymes with the G-CSF receptor. Wild-type, lyn-deficient, and syk-deficient chicken B lymphocyte cell lines were transfected with the human G-CSF receptor, and stable transfectants were studied. G-CSF-dependent tyrosyl phosphorylation of Jak1 and Jak2 occurred in all three cell lines. Wild-type and syk-deficient transfectants responded to G-CSF in a dose-responsive fashion with increased thymidine incorporation, but none of the clones of lyn-deficient transfectants did. Ectopic expression of Lyn, but not that of c-Src, in the lyn-deficient cells restored their mitogenic responsiveness to G-CSF. Ectopic expression in wild-type cells of the kinase-inactive form of Lyn, but not of the kinase-inactive form of Jak2, inhibited thymidine incorporation in response to G-CSF. These studies show that the absence of Lyn results in the loss of mitogenic signaling in the G-CSF signaling pathway and that activation of Jak1 or Jak2 is not sufficient to cause mitogenesis.

DNA polymerase delta isolated from Schizosaccharomyces pombe contains five subunits

DNA polymerase delta (pol delta) plays an essential role in DNA replication, repair, and recombination. We have purified pol delta from Schizosaccharomyces pombe more than 10(3)-fold and demonstrated that the polymerase activity of purified S. pombe pol delta is completely dependent on proliferating cell nuclear antigen and replication factor C. SDS/PAGE analysis of the purified fraction indicated that the pol delta complex consists of five subunits that migrate with apparent molecular masses of 125, 55, 54, 42, and 22 kDa. Western blot analysis indicated that the 125, 55, and 54 kDa proteins are the large catalytic subunit (Pol3), Cdc1, and Cdc27, respectively. The identity of the other two subunits, p42 and p22, was determined following proteolytic digestion and sequence analysis of the resulting peptides. The peptide sequences derived from the p22 subunit indicated that this subunit is identical to Cdm1, previously identified as a multicopy suppressor of the temperature-sensitive cdc1-P13 mutant, whereas peptide sequences derived from the p42 subunit were identical to a previously uncharacterized ORF located on S. pombe chromosome 1.

Comparison of the effects of UV irradiation on 5-methyl-substituted and unsubstituted pyrimidines in alternating pyrimidine-purine sequences in DNA

We previously demonstrated the UV-induced formation of cytosine hydrate in DNA and its deamination product, uracil hydrate, via their release from the DNA backbone by the DNA glycosylase activity of Escherichia coli endonuclease III. Subsequently, endonuclease III-mediated release of thymine hydrate from UV-irradiated poly(dA-dT) was reported. Therefore, we asked whether 5-methylcytosine residues in DNA underwent photohydration and deamination to thymine hydrate in analogy to UV-induced deamination of cytosine. An alternating DNA copolymer containing 5-methylcytosine was irradiated with UVC and incubated with endonuclease III. No 5-methylcytosine hydrate was released. Instead, UV-induced nonenzymatic release of 5-methylcytosine occurred. Similarly, incubation of UV-irradiated poly(dA-dT) with endonuclease III did not release thymine hydrate; nonenzymatic release of thymine occurred. Nonenzymatic release of 5-methylpyrimidines was oxygen dependent, enhanced by ferric ion and inhibited by free radical scavengers. In contrast, photohydration of cytosine was oxygen independent, and only small amounts of cytosine were nonenzymatically released. Thus, 5-methylpyrimidine residues within alternating Pu-Py sequences in DNA do not undergo photohydration, but instead undergo cleavage of their N-glycosyl bonds yielding abasic (AP) sites. The inability to repair such AP sites may explain the UV sensitivity of E. coli xthnfo mutants, which lack AP endonuclease activity. We suggest that N-glycosyl bond cleavage is mediated by radical species formed via transfer of an electron from UV-excited triplet 5-methylpyrimidines to ground state oxygen and/or ferric ions.

Oxidative damage to 5-methylcytosine in DNA

Exposure of pyrimidines of DNA to ionizing radiation under aerobic conditions or oxidizing agents results in attack on the 5,6 double bond of the pyrimidine ring or on the exocyclic 5-methyl group. The primary product of oxidation of the 5,6 double bond of thymine is thymine glycol, while oxidation of the 5-methyl group yields 5-hydroxymethyluracil. Oxidation of the 5,6 double bond of cytosine yields cytosine glycol, which decomposes to 5-hydroxycytosine, 5-hydroxyuracil and uracil glycol, all of which are repaired in DNA by Escherichia coli endonuclease III. We now describe the products of oxidation of 5-methylcytosine in DNA. Poly(dG-[3H]dmC) was gamma-irradiated or oxidized with hydrogen peroxide in the presence of Fe3+ and ascorbic acid. The oxidized co-polymer was incubated with endonuclease III or 5-hydroxymethyluracil-DNA glycosylase, to determine whether repairable products were formed, or digested to 2'-deoxyribonucleosides, to determine the total complement of oxidative products. Oxidative attack on 5-methylcytosine resulted primarily in formation of thymine glycol. The radiogenic yield of thymine glycol in poly(dG-dmC) was the same as that in poly(dA-dT), demonstrating that 5-methylcytosine residues in DNA were equally susceptible to radiation-induced oxidation as were thymine residues.

Evidence that two zinc fingers in the methionine aminopeptidase from Saccharomyces cerevisiae are important for normal growth

Limited proteolysis of intact yeast methionine aminopeptidase (MAP1) with trypsin releases a 34 kDa fragment whose NH2-terminal sequence begins at Asp70, immediately following Lys69. These results suggest that yeast MAP may have a two-domain structure consisting of an NH2-terminal zinc finger domain and a C-terminal catalytic domain. To test this, a mutant MAP lacking residues 2-69 was generated, overexpressed, purified and analyzed. Metal ion analyses indicate that 1 mol of wild-type yeast MAP contains 2 mol of zinc ions and at least 1 mol of cobalt ion, whereas 1 mol of the truncated MAP lacking the putative zinc fingers contains only a trace amount of zinc ions but still contains one mole of cobalt ion. These results suggest that the two zinc ions observed in the native yeast MAP are located at the Cys/His rich region and the cobalt ion is located in the catalytic domain. The kcat and Km values of the purified truncated MAP are similar to those of the wild-type MAP when measured with peptide substrates in vitro and it appears to be as active as the wild-type MAP in vivo. However, the truncated MAP is significantly less effective in rescuing the slow growth phenotype of map mutant than the wild-type MAP. These findings suggest that the zinc fingers are essential for normal MAP function in vivo, even though the in vitro enzyme assays indicate that they are not involved in catalysis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Application of the time-resolved immunofluorometric assay in the detection of viruses]

Two systems of time-resolved immunofluorometric assay (TR-IFMA), i.e., LKB system detection of viruses. The viruses detected were mainly adenovirus, influenza virus, parainfluenza virus, respiratory syncytial virus rotavirus, hepatitis B virus, human immunodeficiency virus, rubella virus, etc. Compared with methods of ELISA and RIA, TR-IFMA has the merits of high sensitivity, specificity and consistency with clinical diagnosis. The low detection limit of virus antigen by TR-IFMA is between 10-100 pg. The application of dual-label TR-IFMA also showed good effect. TR-IFMA can also be used in the detection of viral nucleic acids. The target region detected may reach the level of pg.