Soluble CD4 effectively prevents excessive TLR activation of resident macrophages in the onset of sepsis

T lymphopenia, occurring in the early phase of sepsis in response to systemic inflammation, is commonly associated with morbidity and mortality of septic infections. We have previously shown that a sufficient number of T cells is required to constrain Toll-like receptors (TLRs) mediated hyperinflammation. However, the underlying mechanisms remains unsolved. Herein, we unveil that CD4⁺ T cells engage with MHC II of macrophages to downregulate TLR pro-inflammatory signaling. We show further that the direct contact between CD4 molecule of CD4⁺ T cells or the ectodomain of CD4 (soluble CD4, sCD4), and MHC II of resident macrophages is necessary and sufficient to prevent TLR4 overactivation in LPS and cecal ligation puncture (CLP) sepsis. sCD4 serum concentrations increase after the onset of LPS sepsis, suggesting its compensatory inhibitive effects on hyperinflammation. sCD4 engagement enables the cytoplasmic domain of MHC II to recruit and activate STING and SHP2, which inhibits IRAK1/Erk and TRAF6/NF-κB activation required for TLR4 inflammation. Furthermore, sCD4 subverts pro-inflammatory plasma membrane anchorage of TLR4 by disruption of MHC II-TLR4 raft domains that promotes MHC II endocytosis. Finally, sCD4/MHCII reversal signaling specifically interferes with TLR4 but not TNFR hyperinflammation, and independent of the inhibitive signaling of CD40 ligand of CD4⁺ cells on macrophages. Therefore, a sufficient amount of soluble CD4 protein can prevent excessive inflammatory activation of macrophages via alternation of MHC II-TLR signaling complex, that might benefit for a new paradigm of preventive treatment of sepsis.

[Analysis of efficacy and safety of a new endoscopic anastomosis clip in the treatment of defects after endoscopic full-thickness resection]

Objective: To investigate the efficacy and safety of a new endoscopic anastomosis clip in the treatment of defects after endoscopic full-thickness resection (EFTR). Methods: Retrospective cohort study. Fourteen patients [4 males and 10 females, aged (55.9±8.2) years (45-69 years)] with gastric submucosal tumors underwent EFTR at the First Affiliated Hospital of Soochow University were included from December 2018 to January 2021. Patients were divided into new anastomotic clamp group (n=6) and nylon ring combined with metal clips group (n=8). Preoperative endoscopic ultrasound examinations were required to all patients to evaluate the wound condition. The size of the defect, operation time required for wound closure, success rate of closure, postoperative gastric tube placement time, postoperative hospital stay, incidence of complications, preoperative and postoperative serological indexes were compared between the two groups. All patients were followed up after the operation, among which the general endoscopy was reviewed in the first month after the operation, and the telephone and questionnaire follow-up were used in the second, third, sixth month and one year after the operation to evaluate the therapeutic effect of the new endoscopic anastomosis clip and nylon rope combined with metal clip after the EFTR operation. Results: Both groups successfully completed EFTR and were successfully closed. There was no significant difference between the age, tumor diameter and defect diameter of the two groups (all P>0.05). Compared with the nylon ring combined with metal clip group, the operation time of the new anastomotic clip group was shortened [(5.0±1.8) minutes vs (35.6±10.2) minutes, P<0.001]. The operation time was shortened [(62.2±12.5) minutes vs (92.5±0.2) minutes, P=0.007]. Postoperative fasting time decreased [(2.8±0.8) days vs (4.9±1.1) days, P=0.002]. The hospital stay after operation was also shortened [(5.2±0.8) days vs (6.9±1.5) days, P=0.023]. The total intraoperative bleeding volume decreased [(20.00±5.48) ml vs (35.63±14.75) ml, P=0.031]. The patients in both groups received endoscopic examination 1 month after operation, and there was no delayed perforation and bleeding after operation. There was no obvious symptoms of discomfort. Conclusion: The new anastomotic clamp is suitable for the treatment of full-thickness gastric wall defects after EFTR, and shows advantages of shorter operation, less bleeding, and fewer postoperative complications.

[Experimental Study of Ginsenoside Rg1 Combined with Antibiotics in the Treatment of Acute Lung Injury in Mice with Sepsis]

Objective

To observe the effect of ginsenoside Rg1 on the acute lung injury of sepsis in combination with the antibiotic imipenem in a mouse model of sepsis that induced by cecal puncture.

Methods

C57BL/6 mice were used to establish the model of sepsis. The model mice were randomly divided into model group, imipenem group, ginsenoside Rg1 group, and ginsenoside Rg1+imipenem group, 10 mice in each group. Another 10 mice were set as control group. Sham operation was performed in the mice of control group. Each mice was intraperitoneally injected the corresponding drug in 2 h, 26 h and 50 h after surgery for three times. They were 2 h after surgery, 26 h after surgery and 50 h after surgery. 2 h after the last administration, the oxygenation index of the arterial blood was measured, the lung tissue was taken to measure lung wet/dry ratio (W/D), and HE staining was used to observe the lung inflammation. The ELISA kits were used to detect the levels of interleukin (IL)- 1β, IL-6, tumor necrosis factor (TNF)-α and nuclear factor-kappa B (NF-κB) inalveolar lavage fluid. Western blot and immunohistochemical staining were used to detect NF-κB p65 expression in lung tissues.

Results

The drug-administered groups significantly reduced the W/D of the lungs in the septic mice and increased the oxygenation index in the blood ( P<0.01), and decreased the inflammation in lung and the levels of IL-1β, IL-6, TNF-α and NF-κB in the alveolar lavage fluid ( P<0.01), and decreased the expression of NF-κB p65 in lung tissue ( P<0.01). When ginsenoside Rg1 was combined with imipenem, the above indicators were closer to the control group than that in the ginsenoside Rg1 and imipenem groups.

Conclusion

Rg1 can significantly inhibit lung inflammation in septic mice. It has a better therapeutic effect when combined with antibiotics.

Genome-wide DNA methylation and RNA expression profiles identified RIPK3 as a differentially methylated gene in Chlamydia pneumoniae infection lung carcinoma patients in China

Aim: To explore the relationship between Chlamydia pneumonia (Cpn) infection and lung cancer using integrative methylome and transcriptome analyses. Methods: Twelve primary lung cancer patients who were positive for Cpn and twelve patients who were negative were selected for demographic, clinicopathological, and lifestyle matching. Genomic DNA and RNA were extracted and DNA methylation and mRNA levels were detected using the Infinium Human Methylation 450 Beadchip array and mRNA + lncRNA Human Gene Expression Microarray. We identified differentially expressed methylation and genes profiles. Results: Integrative analysis revealed an inverse correlation between differentially expressed genes and DNA methylation. Cpn-related lung cancer methylated genes (target genes) were introduced into the gene ontology and KEGG, PID, BioCarta, Reactome, BioCyc and PANTHER enrichment analyses using a q-value cutoff of 0.05 to identify potentially functional methylation of abnormal genes associated with Cpn infection. Gene sets enrichment analysis was evaluated according to MsigDB. Levels of differentially expressed methylated sites were quantitatively verified. The promoter methylation sites of 62 genes were inversely related to expression levels. According to the quantitative analysis of DNA methylation, the methylation level of the RIPK3 promoter region was significantly different between Cpn-positive cancerous and adjacent tissues, but not between Cpn-negative cancerous and adjacent tissues. Conclusion:  Hypomethylation of the RIPK3 promoter region increases RIPK3 expression, leading to regulated programmed necrosis and activation of NF-κB transcription factors, which may contribute to the development and progression of Cpn-related lung cancer.

[Association between polymorphism in notch signaling pathway and lung cancer risk]

Objective: To analyze the relationship between single nucleotide polymorphisms (SNP) of Notch signaling pathway and susceptibility to lung cancer. Methods: The present study was a hospital-based case-control study. All 1 121 patients of lung cancer diagnosed by histopathology three hospitals in Fujian and Nanjing were selected as cases from January 2006 to December 2012. At the same time, 1 121 healthy population from other departments of the hospital to visit patients or community, excluding those with tumor, chronic disease, and immediate family members of lung cancer, were enrolled in control group. A uniform questionnaire was used to collect general information. Matrix-assisted laster desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was used to identify the polymorphisms of 9 SNP (Notch3 rs3815188, Notch4 rs915894, Notch4 rs520692, DLL1 rs1033583, JAG1 rs8708, JAG2 rs9972231, HEY1 rs1046472, HEY2 rs3734637, HES2 rs11364) in 1 121 lung cancer patients and 1 121 healthy controls. The association between SNP and lung cancer was analyzed by χ(2) and logistic regression model. Results: The average age of cases and controls was (58.70±10.73) and (58.98±10.85) years old. The OR for genotype AC carriers of HEY1 rs1046472 was 0.80 (95%CI: 0.66-0.97) when comparing with genotype CC. The OR for genotype AC+AA carriers of HEY1 rs1046472 was 0.81 (95% CI: 0.67-0.98) when comparing with genotype CC. The OR for genotype AC carriers of HEY2 rs3734637 was 0.82 (95%CI: 0.67-0.99) when comparing with genotype AA. In the stratified analysis, Notch3 rs3815188, DLL1 rs1033583, JAG1 rs8708, JAG2 rs9972231, HEY1 rs1046472, HEY2 rs3734637, HES2 rs11364 were associatied with the risk of lung cancer, P were 0.041, 0.030, 0.043, 0.003, 0.004, 0.026 and 0.038, respectively.The interactions analysis done by logistic regression model showed JAG1 rs8708 and family history, JAG2 rs9972231 and BMI had interaction in the study, OR were 2.07 (95% CI:1.21-3.52) and 1.73 (95% CI:1.21-2.47), respectively. Conclusion: Notch3 rs3815188, DLL1 rs1033583, JAG1 rs8708, JAG2 rs9972231, HEY1 rs1046472, HEY2 rs3734637 and HES2 rs11364 were significantly associated with susceptibility to lung cancer.

[Clinical application of Acutegastrointestinal injury grading system assocaited with clinical severity outcome in critically ill patients: a multi-center prospective, observational study]

Objective: To investigate the feasibility of utilizing the current acute gastrointestinal injury(AGI) grading system, and explore the association of severity of AGI grade with clinical outcome in critically ill patients. Methods: The adult patients from 14 general ICUs in Zhejiang Province with an expected admission to ICU for at least 24 h were recruited, and all clinical, laboratory, and survival data were prospectively collected. The AGI grade was daily assessed based on GIsymptoms, feeding details and organ dysfunctionon the first week of admission to ICU.The intra-abdominal pressures(IAP) was measured using AbViser device. Results: Of 550 patients enrolled, mean values for age and APACHE Ⅱ score were (64.9±17.2) years and (19.5±7.4), respectively. 456 patients(82.9%) took mechanical ventilation, and 470 patients were identified for AGI. The distribution of AGI grade on the frist day of ICU admission were 50.6%(Ⅰ grade, n=238), 34.2%(Ⅱ grade, n=161), 12.4%(Ⅲ grade, n=58) and 2.8%(Ⅳ, n=13), respectively, while the distribution of the global AGI grade based on the 7-day AGI assessment of ICU admission were 24.5%(Ⅰ grade, n=115), 49.4%(Ⅱ grade, n=232), 20.6%(Ⅲ grade, n=97) and 5.5%(Ⅳ, n=26), respectively. 28- and 60-day mortality rate was 29.3%(n=161) and 32.5%(n=179), respectively. The patients with AGI had a higher 28-(31.1% vs 18.8%, P=0.025) and 60-day survival rate(34.7% vs 20.0%, P=0.01) than those with non-AGI, and also there were positive correlations between AGI grade and 28- and 60-day mortality(P<0.001). Univariate Cox regression analysis showed that age, the source of medicial admission, diabetes mellitus, coronary heart disease, the use of vasoactive drugs, serum creatinine and lactate, mechanical ventilation, APACHE Ⅱ score, the AGI grade in the first day of ICU admission and feeding intolerance within the first week of ICU stay were significantly(P≤0.02) associated with mortality. In multivariate analysis including all these variables, the source of medical admission(χ(2)=4.34, P=0.04), diabete mellitus(χ(2)=3.96, P=0.05), the use of vasoactive drugs(χ(2)=6.55, P=0.01), serum lactate(χ(2)=4.73, P=0.03), the global AGI grade in the 7-day of ICU admission(χ(2)=7.10, P=0.008), and APACHE Ⅱ score(χ(2)=12.1, P<0.001) remained independent predictors for 60-day mortality.In the further subgroup analysis including 402 patients with 7-day survival, the feeding intolerance within the first week of ICU stay could provide independent and incremental prognostic value of 60-day mortality wtih increased χ(2)value of Cox regression model(χ(2)=52.2 vs 41.9, P=0.007) . Conclusion: The AGI grading system is useful for identifying the severity of gastrointestinal dysfunction, and could be used as a strong predictor of impaired outcome. The results provide evidence to support that feeding intolerance within 7 days of admission to ICU was an independent determinant of mortality.

Dietary patterns, BCMO1 polymorphisms, and primary lung cancer risk in a Han Chinese population: a case-control study in Southeast China

BACKGROUND

We investigated whether BCMO1 variants and dietary patterns are associated with lung cancer risk.

METHODS

Case-control study including 1166 lung cancer cases and 1179 frequency matched controls was conducted for three BCMO1 variants (rs6564851, rs12934922, and rs7501331) and four dietary patterns were investigated. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

The rs6564851, rs12934922, and rs7501331 were not found to be associated with lung cancer risk (P > 0.05). In multivariable-adjusted models, compared to the lowest quartile of the score on the "fruits and vegetables" pattern, the highest quintile was associated with a 78.4% decreased risk (OR _{Q4 vs. Q1} = 0.216; 95% CI, 0.164-0.284; P for trend < 0.001). Other patterns were not found the association. The "fruits and vegetables" pattern was associated with a reduced risk of lung cancer with all 3 SNPs irrespective of genotypes (all P for trend< 0.001). The association for the "Frugal" pattern was associated with increased risk of lung cancer among smokers (P for interaction = 0.005). The protective effects of the "cereals/wheat and meat" pattern was more evident for squamous cell carcinoma and other histological type.

CONCLUSIONS

We did not observe associations of BCMO1 variants and lung cancer. Diets rich in fruits and vegetables may be protective against lung cancer.

The association between human papillomavirus infection and lung cancer: a system review and meta-analysis

To estimate the global attributable fraction of human papillomavirus (HPV) in lung cancer, we provided updated information through a system review and meta-analysis. We did a literature search on PubMed, Ovid and Web of Science to identify case-control studies and cohort studies that detected HPV in lung carcinomas. We included studies that tested 30 or more cases and were published before Feb 28, 2017. We collected information about gender, smoking status, HPV detection methods, HPV types, materials and clinical features. If it was not possible to abstract the required information directly from the papers, we contacted the authors. A meta-analysis was performed to calculate the pooled effect sizes (OR/RR) with 95% confidence intervals (CI) including subgroup analysis and meta-regression to explore sources of heterogeneity, by Stata 13.0 software. 36 case-control studies, contributing data for 6,980 cases of lung cancer and 7,474 controls from 17 countries and one cohort study with 24,162 exposed and 1,026,986 unexposed from China were included. HPV infection was associated with cancer of lung, pooled OR was 3.64 (95% CI: 2.60–5.08), calculated with the random-effects model. Pooled OR for allogeneic case-control studies, self-matched case-control studies and nested case-control studies were 6.71 (95% CI: 4.07–11.07), 2.59 (95% CI: 1.43–4.69) and 0.92 (95% CI: 0.63–1.36), respectively. Pooled OR for HPV 16 and HPV 18 infection, were 3.14 (95% CI: 2.07–4.76) and 2.25 (95% CI: 1.49–3.40), respectively. We also found that HPV infection may be associated with squamous cell carcinoma, adenocarcinoma and small cell carcinoma. There is evidence that HPV infection, especially HPV 16 and HPV 18 infection, significantly increase the risk of lung cancer. Future research needs to focus attention toward whether an HPV vaccine can effectively reduce the incidence of lung cancer.

Phase I clinical study of personalized peptide vaccination combined with radiotherapy for advanced hepatocellular carcinoma

AIM

To assess the efficacy and safety of a new treatment modality, cellular immune therapy based on personalized peptide vaccination (PPV-DC-CTL) combined with radiotherapy, for treating advanced hepatocellular carcinoma (HCC).

METHODS

A total of nine patients with advanced HCC were enrolled. Multidisciplinary consultation confirmed that all the patients definitely had no opportunity of surgery, because four patients had multiple liver metastases (the number of liver lesions > 3), one patient had liver metastases and portal vein tumor thrombosis, one patient had lung and bone metastases, two patients had liver and lung metastases and one patient had liver metastasis and peritoneal metastasis. Patients with metastasis were treated with precise radiotherapy combined with PPV-DC-CTL.

RESULTS

Following radiotherapy and one to three cycles of PPV-DC-CTL treatment, AFP levels were significantly decreased in six patients and imaging assessment of the lesions showed a partial response (PR) in three patients and stable disease in the other three patients. The response rate was 33% and disease control rate was 66%. This regimen was found to be safe and well tolerated. None of the patients developed liver or kidney side effects. Only one patient developed grade II bone marrow suppression and the remaining patients had no significant hematological side effects.

CONCLUSION

Radiotherapy combined with PPV-DC-CTL provides a new therapeutic strategy for patients with advanced HCC, which is well tolerated, safe, feasible and effective.

[Effect of gender on the prognosis of patients with non-small cell lung cancer]

Objective: To analyze the effect of gender on the prognosis of patients with non-small cell lung cancer (NSCLC). Methods: Data of 1 195 patients with NSCLC were analyzed by Chi-square, Kaplan-Meier, log-rank tests and Cox regression models. Results: Women had a longer survival than men (median overall survival 31.64 versus 22.71 months, P<0.01) in the participants of this study. Differences seen in overall survival remained the similar, after stratified by age, pathologic types, clinical stage, sizes, pleural effusion and surgery of the patients, respectively. Data from the multivariate analysis revealed that factors as smoking, clinical stage, metastatic when diagnosis was made and surgery, but not gender, were independent prognostic factors for patients with NSCLC. After adjustment for potential confounders, we found that smoking was a major confounding factor, affecting the relationship between gender and prognosis of NSCLC. Conclusion: Gender did not seem an independent prognostic factor for NSCLC patients while the survival advantages of females might be attributed to the lower prevalence of smoking in this population.

MicroRNA-302d downregulates TGFBR2 expression and promotes hepatocellular carcinoma growth and invasion

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-associated mortality in China and the third leading cause worldwide. A number of microRNAs (miRNAs) have been implicated in cell cycle progression, growth, apoptosis, angiogenesis and metastasis in HCC. In the present study, reverse transcription-quantitative polymerase chain reaction analysis was used to detect the levels of miR-302d expression in the tissues of 30 patients with HCC. Cell cycle, growth, apoptosis and migration were analyzed using a cell counting kit, flow cytometry and a Transwell migration assay. Dual-luciferase reporter assays and western blotting were also used to analyze the expression levels of transforming growth factor beta type II receptor (TGFBR2) in HCC cells. The present study evaluated the role of miR-302d in the development and progression of HCC. Abnormally high expression of miR-302d was observed in 80% of HCC specimens. Moreover, patients with lower levels of miR-302d expression experienced a longer survival time than those with higher levels of miR-302d expression. It was demonstrated that miR-302d promoted HCC cell growth and migration, suppressed cell apoptosis and affected cell cycle distribution in vitro, and augmented tumorigenicity in vivo. Furthermore, TGFBR2, which is a tumor suppressor, was confirmed as a target of miR-302d in HCC cells. Dual-luciferase reporter assays indicated that TGFBR2 expression was negatively regulated by miR-302d. Taken together, the results of the present study suggest that miR-302d may serve as a valuable tool for predicting the prognosis of patients with HCC.

[Association between human papillomavirus infection and lung cancer]

Objective: To investigate the association between human papillomavirus (HPV) and lung cancer. Methods: We examined a series of 83 lung cancer patients with HPV DNA in both lung tumor specimens and adjacent normal specimens from Fujian province. Twenty-one of the most clinically relevant HPV types from the highly conserved L1 region of the viral genome were analyzed, using the PCR amplification and were followed by reverse hybridization with specific probes. Chi-square test of paired design was used to test the difference of HPV positive rates between lung cancer specimens and adjacent normal specimens. Chi-square test and Fisher's exact test were used to analyze the differences of HPV positive rate of tumor specimens on factors as gender, age, histological subtype, clinical stage, smoking status and alcohol consumption. Results: HPV was detected in 7 of the 83 tumor specimens and in 6 of the paired normal lung tissues. There was no significant correlation between HPV and lung cancer (P>0.999). Neither demographic characteristics nor clinical features were found with significant differences on HPV in lung cancer tissues (P>0.05). Conclusion: Our data showed that HPV was not significantly associated with the risk of lung cancer in Fujian province.

The protective role of oxymatrine on neuronal cell apoptosis in the hemorrhagic rat brain

ETHNOPHARMACOLOGICAL RELEVANCE

Oxymatrine is extracted from the traditional Chinese herb Sophora flavescens Ait, possesses anti-inflammatory, anti-oxidative and anti-apoptotic properties, and has been used for the treatment of chronic viral hepatitis and many other diseases.

AIMS OF THE STUDY

This study aimed to investigate the effects of oxymatrine on inflammatory response mediated by Toll-like receptor4 (TLR4) and nuclear factor kappa-B (NF-κB), oxidative injury induced by 12/15 lipoxygenase (12/15-LOX), phosphorylated p38 mitogen activated protein kinase (phosphor-p38 MAPK) and cytosolic phospholipase A2 (cPLA2), and neuronal cell apoptosis in rat brain with intracerebral hemorrhage (ICH).

MATERIALS AND METHODS

Wistar rats were treated intraperitoneally with 60 or 120mg/kg of oxymatrine daily for 5 days following ICH. The rats were sacrificed at hour 2, 6, 12, 24, 48, 72, and 120 after ICH. The gene expressions of TLR-4 and NF-κB, the levels of TNF-alpha, interleukin-1beta, interleukin-6, 12/15-LOX, phospho-p38 MAPK and cPLA2, and the number of apoptotic neuronal cells in rat brain were determined.

RESULTS

Oxymatrine at 120mg/kg significantly suppressed gene expressions of TLR-4 and NF-κB, decreased levels of TNF-alpha, interleukin-1beta and interleukin-6, inhibited synthesis of 12/15-LOX, phospho-p38 MAPK and cPLA2 protein, and mitigated apoptotic neuronal changes following ICH in rat.

CONCLUSION

Oxymatrine at 120mg/kg following ICH inhibits inflammatory responses, oxidative injury, and neuronal cell apoptosis in rats.

Role of autophagy in acute myeloid leukemia therapy

Despite its dual role in determining cell fate in a wide array of solid cancer cell lines, autophagy has been robustly shown to suppress or kill acute myeloid leukemia cells via degradation of the oncogenic fusion protein that drives leukemogenesis. However, autophagy also induces the demise of acute leukemia cells that do not express the known fusion protein, though the molecular mechanism remains elusive. Nevertheless, since it can induce cooperation with apoptosis and differentiation in response to autophagic signals, autophagy can be manipulated for a better therapy on acute myeloid leukemia.

High hospital occupancy is associated with increased risk for patients boarding in the emergency department

BACKGROUND

Boarding admitted patients in the emergency department due to high hospital occupancy is a worldwide problem. However, whether or not emergency department-boarded patients managed by emergency department providers subjects them to increased serious complications needs further clarification.

METHODS

A multivariate logistic regression analysis was used to examine the relationship of patient's age, sex, arrival hours, diagnostic category, triage category, daily emergency department visits, and daily hospital occupancy to the occurrence of serious complications within 24 hours for 20,276 emergency admissions in a 4-year period.

RESULTS

A vast majority of study days (86.5%) saw very high occupancy ≥90%. Serious complications incidence was 13.62 per 1000 patient days when hospital occupancy was ≤90%, and it increased significantly to 17.10 and 22.52 per 1000 patient days for occupancy at 90%-95% and ≥95%, respectively. In the multivariate analysis, significant risk factors for serious complications included daily occupancy ≥95% (adjusted odds ratio [OR] 1.73; 95% confidence interval [CI], 1.26-2.39), triage category (adjusted OR 0.20; 95% CI, 0.17-0.24), and specific diagnoses (injury and poisoning [adjusted OR 1.62; 95% CI, 1.22-2.84], respiratory [adjusted OR 2.48; 95% CI, 1.37-4.49], and circulatory [adjusted OR 3.24; 95% CI, 1.80-5.80]).

CONCLUSION

High hospital occupancy was associated with an increased incidence of serious complications within 24 hours for patients admitted but still boarded in the emergency department and managed by emergency department providers.

Ginkgolide B reduces neuronal cell apoptosis in the hemorrhagic rat brain: possible involvement of Toll-like receptor 4/nuclear factor-kappa B pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgolide B (GB) is one of the ginkgolides that have been isolated from leaves and root bark of the Chinese tree Ginkgo biloba L. (Ginkgoaceae), and is a specific and potent antagonist of platelet activating factor. There is a large body of data showing that GB possesses a markedly neuroprotective property against ischemia-induced impairment in vivo and in vitro. Recently it has been found that GB can inhibit the inflammation in the rat brain tissues with ischemia/reperfusion injury and in the astrocytes treated with lipopolysaccharide, as well as protect neurons against beta-amyloid 25-35 and ischemia-induced apoptosis. However, there have been few reports on the influence of GB on intracerebral hemorrhage (ICH). This study was to investigate the effects of intraperitoneal GB on neuronal cell apoptosis, inflammatory cytokines and Toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway after ICH.

MATERIALS AND METHODS

Wistar rats obtained an intraperitoneal injection of 5, 10 and 20mg/kg GB after ICH once a day till day 5. Rats were sacrificed by decapitation at hour 2, 6 and 12, as well as day 1, 2, 3 and 5 after ICH. Gene expressions of TLR-4 and NF-κB, concentrations of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and interleukin-6 (IL-6) as well as number of apoptotic neuronal cells in hemorrhagic rat brain tissues were determined.

RESULTS

The administration of 10 and 20mg/kg GB could significantly suppress gene expressions of TLR-4 and NF-κB, lessen concentrations of TNF-α, IL-1β and IL-6 as well as reduce number of apoptotic neuronal cells in hemorrhagic rat brain tissues by Least-significant Difference test (P<0.05), but the administration of 5mg/kg GB not (P>0.05). However, a clear concentration-response relationship was not found.

CONCLUSIONS

GB may inhibit TLR4/NF-κB-dependent inflammatory responses, and furthermore lessen neuronal cell apoptosis after ICH, which may support the use of G. biloba extracts for the treatment of ICH.

[Protective effect of Xingnaojing and Xuesaitong injections on cerebral ischemic reperfusion injury in rats]

OBJECTIVE

To investigate the mechanism of protective effect of Xingnaojing and Xuesaitong injections on cerebral ischemic reperfusion injury in rats.

METHODS

The focal cerebral ischemia & reperfusion model was established by middle cerebral artery occlusion (MCAO). A total of 152 male SD rats were randomly assigned into 19 groups: sham operated group, Xingnaojing group, Xingnaojing plus Xuesaitong group and control group according to different reperfusion durations: 2, 4, 8, 24, 48, 72 h. Each group had 8 rats. Rats in Xingnaojing group received the ip injections of Xingnaojing (1 ml x 100 (-1) x d(-1)) until an onset of ischemia; Xingnaojing plus Xuesaitong group received the ip injections of Xingnaojing (1 ml x 100 g(-1) x d(-1)) and Xuesaitong (1 ml x 100 g(-1) x d(-1)) until an onset of ischemia; In the meantime, rats in control group received the same ip dose of saline. The levels of SOD and MDA were detected. The number of apoptotic neurons was detected by terminal-deoxynucleotidyl transferase medicated nick end labeling (TUNEL).

RESULTS

During ischemic reperfusion, the MDA content of brain homogenate increased while the SOD activity decreased (P < 0.05). Xingnaojing could significantly inhibit the increase of MDA after cerebral ischemic reperfusion (P < 0.05) and the decrease of SOD activity in rats. The changes of SOD and MDA were smaller in the Xingnaojing plus Xuesaitong group than those in the Xinnaojing group (P < 0.01). The number of apoptotic neurons in the Xingnaojing group was significantly lower than that in control group (P < 0.05). And the number of apoptotic neurons in the Xingnaojing plus Xuesaitong group was even lower than that in the Xingnaojing group(4,8 h: P < 0.05, 24, 48, 72 h: P < 0.01).

CONCLUSION

The Xingnaojing plus Xuesaitong injection has protective function after cerebral ischemic reperfusion.

Impact of invasive fungal infection on outcomes of severe sepsis: a multicenter matched cohort study in critically ill surgical patients

Introduction

Fungal infection is increasingly common in critical illness with severe sepsis, but the influence of invasive fungal infection (IFI) on severe sepsis is not well understood. The aim of this study was to investigate the impact that IFI has on the outcomes of critically ill surgical patients with severe sepsis in China by means of matched cohort analysis; we also evaluated the epidemiologic characteristics of IFI in this population.

Methods

Records for all admissions to 10 university hospital surgical intensive care units (ICUs) from December 2004 to November 2005 were reviewed. Patients who met criteria for severe sepsis were included. IFI was identified using established criteria based on microbiologic or histological evidence. A matched cohort study was conducted to analyze the relationship between IFI and outcomes of severe sepsis.

Results

A total of 318 patients with severe sepsis were enrolled during the study period, of whom 90 (28.3%) were identified as having IFI. A total of 100 strains of fungi (58% Candida albicans) were isolated from these patients. Independent risk factors for IFI in patients with severe sepsis included mechanical ventilation (>3 days), Acute Physiology and Chronic Health Evaluation score, coexisting infection with both Gram-positive and Gram-negative bacteria, and urethral catheterization (>3 days). Compared with the control cohort, IFI was associated with increased hospital mortality (P < 0.001), high hospital costs (P = 0.038), and prolonged stay in the ICU (P < 0.001) and hospital (P = 0.020).

Conclusion

IFI is frequent in patients with severe sepsis in surgical ICUs and is associated with excess risk for hospital mortality, longer ICU and hospital stays, and greater consumption of medical resources.

Effects and mechanisms of triacetylshikimic acid on platelet adhesion to neutrophils induced by thrombin and reperfusion after focal cerebral ischemia in rats

AIM

To investigate the effect of triacetylshikimic acid (TSA) on the platelet adhesion to neutrophils and P-selectin expression on activated platelet membrane induced by thrombin and reperfusion after focal cerebral ischemia.

METHODS

The platelet adhesion to neutrophils was evaluated by rosette assay, and P-selectin expression on platelet membrane was determined by flow cytometry.

RESULTS

TSA 10 - 1000 micromol/L markedly inhibited thrombin(0.4 kU/L)-induced platelet adhesion to neutrophils. The platelet adhesion to neutrophils induced by a 21-h reperfusion after middle cerebral artery occlusion for 3 h was also inhibited in a dose-dependent manner by TSA 50 - 200 mg/kg given by ig immediately and at 60 min again after the onset of cerebral ischemia. TSA was also shown to decrease the P-selectin expression on platelet surface induced by thrombin in washed platelet and by adenosine diphosphate (ADP) 5 micromol/L in whole blood.

CONCLUSION

Reperfusion after cerebral ischemia and thrombin induced platelet adhesion to neutrophils, which could be reduced by TSA probably due to its inhibition of P-selectin expression on activated platelets.

[Experimental study on protective effective of congsheng capsule in acute cerebral ischemia and improvement of cerebral blood flow and energy metabolism]

OBJECTIVE

To investigate the protective effect of Congsheng capsule (CSC) on acute cerebral ischemia in mice and rats.

METHODS

Cerebral ischemia model was established by adding FeCl3 to block the blood flow of unilateral middle cerebral artery (MCA) for 30 mins. Acute incomplete cerebral ischemia was induced by ligation of bilateral carotid arteries in rats. Bilateral carotid arteries of old mice were repeatedly ischemia and reperfusion combined with caudal bloodletting to build the cerebral ischemia model. The effect of CSC on neurologic symptom, cerebral infarction size, cerebral water content, cerebral blood flow and cerebral tissue energy metabolism were observed.

RESULTS

CSC 1, 3, 6 g/kg obviously reduce the size of cerebral infarction and cerebral water content, markedly improve the neurological symptoms and cerebral blood flow; 3, 6 g/kg significantly ameliorate the energy burden.

CONCLUSION

CSC has anti-cerebral ischemia function through increasing blood supply of cerebral tissue and improve the energy metabolism.

Antagonistic effects of shikimic acid against focal cerebral ischemia injury in rats subjected to middle cerebral artery thrombosis

AIM

To study the effects of shikimic acid (SA) on focal cerebral ischemic injury after middle cerebral artery thrombosis (MCAT).

METHODS

Thrombosis was induced by FeCl3 in middle cerebral artery of rats. The influences of SA on neurologic deficit (ND), infarct size (IS), brain edema, and cerebral blood flow (CBF) in ischemic region were observed.

RESULTS

SA 25 and 50 mg.kg-1 i.p. for 3 d before MCAT attenuated ND, and reduced IS by 51% and 42%; and decreased brain water content from 80.7% to 79.8% and 79.9%; and increased CBF after ischemia from 50.2% of the preischemic level to 75.5% and 73.3%, respectively. In pathologic examination, there was much less thrombosis in MCA in the rat with the pretreatment by SA 25 mg.kg-1. The extent of brain ischemia was much less than that of control.

CONCLUSIONS

SA reduced focal cerebral ischemic injury induced by middle cerebral artery thrombosis.

Mutations of the S4-S5 linker alter activation properties of HERG potassium channels expressed in Xenopus oocytes

1. The structural basis for the activation gate of voltage-dependent K+ channels is not known, but indirect evidence has implicated the S4-S5 linker, the cytoplasmic region between the fourth and fifth transmembrane domains of the channel subunit. We have studied the effects of mutations in the S4-S5 linker of HERG (human ether-á-go-go-related gene), a human delayed rectifier K+ channel, in Xenopus oocytes. 2. Mutation of acidic residues (D540, E544) in the S4-S5 linker of HERG channels to neutral (Ala) or basic (Lys) residues accelerated the rate of channel deactivation. Most mutations greatly accelerated the rate of activation. However, E544K HERG channels activated more slowly than wild-type HERG channels. 3. Mutation of residues in the S4-S5 linker had little or no effect on fast inactivation, consistent with independence of HERG channel activation and inactivation 4. In response to large hyperpolarizations, D540K HERG channels can reopen into a state that is distinct from the normal depolarization-induced open state. It is proposed that substitution of a negatively charged Asp with the positively charged Lys disrupts a subunit interaction that normally stabilizes the channel in a closed state at negative transmembrane potentials. 5. The results indicate that the S4-S5 linker is a crucial component of the activation gate of HERG channels.

A mutation in the pore region of HERG K+ channels expressed in Xenopus oocytes reduces rectification by shifting the voltage dependence of inactivation

1. The effects of a mutation in the human ether-a-go-go-related gene (HERG) (Ser631 to Ala, S631A) on the voltage- and extracellular [K+] dependence of inactivation were studied in Xenopus oocytes using two microelectrode and single channel voltage-clamp techniques. 2. The voltage required for half-inactivation of S631A HERG was 102 mV more positive than for wild-type (WT)-HERG, resulting in reduced rectification of the steady-state current-voltage relationship. In contrast, the voltage dependence of channel activation was not altered by the S631A mutation. These findings indicate that inactivation of HERG channels is not linked to activation. 3. Rectification of whole-cell S631A HERG current was caused by a voltage-dependent reduction in open probability, and inward rectification of the current-voltage relationship of single channels. 4. Elevation of extracellular [K+] from 2 to 20 mM shifted the half-point for inactivation by +20 mV for WT-HERG, and +25 mV for S631A HERG. Thus, elevated [K+]o and the S631A mutation affect HERG inactivation by different mechanisms. 5. The S631A mutation altered the ion translocation rate of HERG channels. The single channel conductance (gamma) of S631A HERG was 20 pS between -40 and-100 mV, and 6.0 pS between +40 and +100 mV (120 mM extracellular K+). This compares to a gamma of 12.1 and 5.1 pS for WT-HERG channels under the same conditions.

Belladonna alkaloids-induced behavioral changes and amnesia on open-field and step-through in 18-, 28-, and 38-day-old mice

AIM

To study the age-related changes of atropine (Atr), scopolamine (Sco), anisodine (AT3), and anisodamine (Ani) on behaviors and memories.

METHODS

The behaviors and memories were measured with open-field test and step-through task. M-cholinergic receptors were determined by [3H] quinuclidinyl benzilate ([3H] QNB).

RESULTS

During acquisition session (d 1) the 18-, 28-, and 38-d-old mice pretreated with Atr, Sco, and AT3 (0.02, 0.2, 2, or 20 mg.kg-1, i.p.) in open-field test showed increase in walking counts by 26%-42%, but decrease in rearing, grooming, and defecating counts for 50%-92%, 67%-100%, and 75%-100%, respectively. On recall session (d 2) the walking and rearing behaviors in the 18- and 28-d-old mice receiving Atr, Sco, and AT3 on d 1 were higher than those in the mice receiving saline. But a lower grooming behavior on d 2 was found in the mice receiving the drugs on d 1. On d 1 Ani 20 mg.kg-1 reduced the rearing behavior by 50% in 18-d-old mice and defecation by 33%-36% in 18- and 28-d-old mice. All the 4 belladonna alkaloids increased the number of avoidance-response errors and decreased the retention latencies in step-through task. Bmax of [3H] QNB binding sites in frontal cortex and hippocampus regions in the 38-d-old mice increased 7% and 23% vs in the mice of 18 d of age, respectively.

CONCLUSION

1) The effects of the belladonna alkaloids on behaviors and memories in adult mice were weaker than those in young mice. 2) The belladonna alkaloids-induced amnesia on passive avoidance-response in step-through was more sensitive than behavioral changes and amnesia on open-field. 3) According to the lowest effective doses which insulted the behaviors or memories in young mice, Sco was about 10, 100, and 1000 times more potent than Atr, AT3, and Ani, respectively.

Characterization of the cooperative function of inhibitory sequences in Ets-1

DNA binding by the eukaryotic transcription factor Ets-1 is negatively regulated by an intramolecular mechanism. Quantitative binding assays compared the DNA-binding activities of native Ets-1, three deletion mutants, and three tryptic fragments. Ets-1 and activated Ets-1 polypeptides differed in DNA-binding affinity as much as 23-fold. Inhibition was mediated by two regions flanking the minimal DNA-binding domain. Both regions regulated affinity by enhancing dissociation of the protein-DNA complex. Three lines of evidence indicated that inhibition requires cooperative interaction between the two regions: first, the two inhibitory regions acted through a common mechanism; second, neither region functioned independently of the other; finally, mutation of the C-terminal inhibitory region altered the conformation of the N-terminal inhibitory region. In addition, partial proteolysis detected an identical altered conformation in the N-terminal inhibitory region of Ets-1 bound to DNA. This finding suggested that repression is transiently disrupted during DNA binding. These results provide evidence that the two inhibitory regions of Ets-1 are structurally, as well as functionally, coupled. In addition, conformational change is shown to be a critical component of the inhibition mechanism. A cooperative, allosteric model of autoinhibition is described. Autoinhibition of Ets-1 could be relieved by either protein partner(s) or posttranslational modifications.

Tumour necrosis factor-alpha can modulate the phenotype of aortic smooth muscle cells

In culture, rabbit aortic smooth muscle cells (SMC) from an atheroma differed phenotypically from SMC from normal media (M-SMC) in their growth rate, secretion of SMC-derived growth factor (SDGF), and metabolism of acetylated low density lipoproteins (a-LDL). The factor responsible for this in vivo phenotypic change of SMC was investigated in vitro. After preincubation of M-SMC with 0.1-10 U ml-1 of tumour necrosis factor-alpha (TNF) for 1-3 days, the cells grew faster than control cells and secreted a substantial amount of SDGF. The population doubling time and secretion of SDGF were inversely correlated. Moreover, after preincubation with TNF, the SMC metabolized [125I]a-LDL, unlike control M-SMC. These findings show that TNF can modulate the phenotype of SMC and suggest that it is important in the pathogenesis of atherosclerosis.

Metalloproteinases and tissue inhibitor of metalloproteinases in mesothelial cells. Cellular differentiation influences expression

Mesothelial cells play a critical role in the remodeling process that follows serosal injury. Although mesothelial cells are known to synthesize a variety of extracellular matrix components including types I, III, and IV collagens, their potential to participate in matrix degradation has not been explored. We now report that human pleural and peritoneal mesothelial cells express interstitial collagenase, 72- and 92-kD gelatinases (type IV collagenases), and the counterregulatory tissue inhibitor of metalloproteinases (TIMP). Our initial characterization of the mesothelial cell metalloenzymes and TIMP has revealed: (a) they are likely identical to corresponding molecules secreted by other human cells; (b) they are secreted rather than stored in an intracellular pool; (c) a primary site of regulation occurs at a pretranslational level; (d) phorbol myristate acetate, via activation of protein kinase C, upregulates expression of collagenase, 92-kD gelatinase, and TIMP, but has no effect on expression of 72-kD gelatinase; and (e) lipopolysaccharide fails to upregulate the biosynthesis of either metalloproteinases or TIMP. Of particular interest is the observation that the state of cellular differentiation has a striking influence on the expression of metalloenzymes and TIMP, such that epitheloid cells display a more matrix-degradative phenotype (increased 92-kD gelatinase and decreased TIMP) than their fibroblastoid counterparts. We speculate that mesothelial cells directly participate in the extracellular matrix turnover that follows serosal injury via elaboration of metalloproteinases and TIMP. Additionally, the reactive cuboidal mesothelium which is characteristic of the early response to serosal injury may manifest a matrix-degenerative phenotype favoring normal repair rather than fibrosis.

[The effects of different lipoproteins on cholesterol metabolism in smooth muscle cells of rabbit aorta]

In the present experiment, M-SMC were cultured from rabbit aorta by an explant method and I-SMC cultured by the explant method from cannulated aortic intima of rabbits, and the effects of LDL, A-LDL, OX-LDL and HDL on the cholesterol metabolism in both types of cells were investigated by using 14C oleic acid as the source of cholesterol re-esteri fication in cells. The results showed that LDL enhanced cholesterol re-esterification in both types of cells and HDL had an opposite effect, A-LDL could increase CE synthesis only in I-SMC, while OX-LDL showed a complex effect on the level of CE in different cells by different concentration. The present experiment has studied the relationship between lipoprotein and cholesterol metabolism in SMC at the level of cell metabolism, and suggests that lipoproteins play a key role in AS.

Pulmonary epithelial cell urokinase-type plasminogen activator. Induction by interleukin-1 beta and tumor necrosis factor-alpha

Diffuse alveolar damage, presenting clinically as adult respiratory distress syndrome, is characterized initially by widespread intra-alveolar fibrin deposition. Alveolar epithelial cells play a central role in the subsequent repair process. We have recently shown that alveolar epithelial cells have the capacity to promote fibrinolysis (Marshall, B. C., Sageser, D. S., Rao, N. V., Emi, M., and Hoidal, J. R. (1990) J. Biol. Chem. 265, 8198-8204) and may therefore directly participate in the extensive remodeling that follows acute lung injury. Because the tissue repair process occurs in an acute inflammatory setting, we investigated the effects of inflammatory mediators on urokinase-type plasminogen activator (u-PA) expression by pulmonary epithelial cells. We found that interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) upregulated PA activity in A549 human pulmonary epithelial cells. Biosynthetic labeling and immunoprecipitation showed that both cytokines caused marked accumulation of newly synthesized u-PA. Northern blot analyses demonstrated that both IL-1 beta and TNF-alpha induced relatively rapid accumulation of u-PA mRNA which did not require de novo protein synthesis and was substantially inhibited by glucocorticoids. Nuclear run-off transcription studies showed that both cytokines caused rapid transcriptional activation of the u-PA gene. While the effects of IL-1 beta and TNF-alpha were qualitatively similar, some differences emerged. Most notably, TNF-alpha led to a more sustained accumulation of u-PA mRNA than did IL-1 beta. In contrast to their effects on u-PA expression, IL-1 beta and TNF-alpha had minimal effect on PA inhibitor-1 expression. These effects of IL-1 beta and TNF-alpha, mediators known to play a key role in acute lung injury and inflammation, may promote lysis of alveolar fibrin by alveolar epithelium, thereby aiding in restoration of normal lung architecture.

[Comparative studies on the febrifugal analgesic and anticonvulsive activities of water extracts from cultivated and wild Saposhnikovia divaricata]

In this paper, comparative studies on main pharmacological activities and toxilogical activities of water extracts from cultivated Saposhnikovia divaricata (SD) and wild SD in Qixia county of Shandong province were performed. The results showed that the febrifugal analgesic and anticonvulsived activities of water extracts from cultivated SD and wild SD were primary same. Estimative results of LD50 showed that order of toxicity were such as firstly direct cultivated SD, secondly cuttage SD and finally wild SD. Therefore it was recognized that cultivated SD completely can replaced wild one in medical use.

Reticulocytes II: Reexamination of the in vivo survival of stress reticulocytes

Very young reticulocytes are released into the circulation in response to the stress of anemia. These stress reticulocytes have shortened in vivo survival when transfused into normal recipients, and are generally considered to be abnormal because they have skipped a terminal cell division. We reevaluated one aspect of their abnormality: that of in vivo survival. Using methodology that accounted for all cells transfused, in vivo survival of both normal and stress reticulocytes was investigated in both normal and anemic recipients. The experiments demonstrate that: (1) survival of reticulocytes is normal only when normal reticulocytes are injected into nonanemic animals; (2) intrinsic properties of stress reticulocytes lead to their immediate removal from the circulation by normal recipients to a significantly greater extent than by anemic recipients; and (3) both stress and normal reticulocytes are removed at an accelerated rate over time by anemic recipients. Taken together, the data indicate that in the course of becoming anemic, an adaptation occurs that allows cells produced during anemia to circulate considerably longer in anemic animals than they could in normal nonanemic animals. Other studies disclosed that increased reticulocyte survival in anemic animals could not be attributed to reticuloendothelial overload, but is induced by adaptation of the spleen, decreasing its removal of stress reticulocytes.

Reticulocytes. I. Isolation and in vitro maturation of synchronized populations

Studies of reticulocyte maturation have been limited by the inability to obtain pure populations of age-synchronized reticulocytes and by the absence of well-defined methods for the maturation of reticulocytes in vitro. Many of these problems were overcome using temporary suppression of erythropoiesis with thiamphenicol and phlebotomy resulting in a highly reproducible reticulocyte response, Percoll density gradient separation of cells yielding essentially pure populations of age-synchronized reticulocytes, and liquid culture techniques where cell lysis is minimal. The system allows reproducible study of well-defined cohorts of reticulocytes as they mature into erythrocytes. During in vitro maturation we serially monitored changes in reticulocyte count, glucose consumption, 125I-transferrin binding, fluorescein (FITC)-labeled transferrin binding, the activities of four erythrocyte enzymes (glucose-6-phosphate dehydrogenase, pyruvate kinase, phosphofructokinase, and lactate dehydrogenase) and the appearance of cells on scanning electron microscopy. These variables changed at different rates suggesting that multiple mechanisms underlie these maturational events. Transferrin binding and reticulocyte count decreased most rapidly and reached values near zero after three to four days in culture. The four enzyme activities decreased much more slowly, and only two reached pretreatment values after seven days in culture. In contrast to the findings of others, scanning electron microscopy suggested that cells do not assume the normal biconcave shape in this system. The methods described make it feasible to study the process of reticulocyte maturation in vitro. The data presented represent a first step in the study of the coordination and interrelationships of various maturational processes.

Photoaffinity labeling of beef liver monoamine oxidase-B by 4-fluoro-3-nitrophenyl azide

4-Fluoro-3-nitrophenyl azide (FNPA) competitively inhibited beef liver monoamine oxidase-B (MAO-B) in the dark (Ki = 2.8 microM). Upon irradiation in the presence of FNPA, a concentration-dependent photoinactivation of MAO-B was observed. The kinetic analysis showed that the photoinactivation of MAO-B resulted in a decrease in Vmax but no change in Km. This result suggests that an irreversible linkage may be formed between the enzyme and the photolyzed FNPA. When [3H]FNPA was photoirradiated with the purified MAO-B, a single radioactive band associated with MAO-B was observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The photo-dependent incorporation could be protected by phenylethylamine, the substrate for MAO-B, in a concentration-dependent manner. Complete tryptic-chymotryptic digestion of [3H]FNPA-labeled MAO-B resulted in three radioactive peaks on Sephadex G-25 column chromatography. With the same digestion and separation procedures, only one major radioactive peak was observed for the [3H]pargyline-labeled MAO-B, and its elution volume was different from that of [3H]FNPA-labeled peptides. These results suggest that, upon photolysis, FNPA may incorporate into a region in the active site of MAO-B which may be different from the pargyline binding site--the FAD prosthetic group of the enzyme.

Inhibition of monoamine oxidase by phenyl azides

We had previously shown that 4-fluoro-3-nitrophenyl azide (FNPA) is a competitive inhibitor of both types of monoamine oxidase (MAO) in the dark, but it is a preferential photoaffinity label for only the type B MAO (MAO-B). Recently we synthesized a number of arylazido compounds with structures related to FNPA and determined the effects of these compounds on the two types of MAO in rat brain cortex. We found that the fluoro group of FNPA was not required for the inhibition of MAO activities because neither the presence nor the position of the fluoro group affected its inhibition of MAO. On the other hand, both the nitro and the azido groups of FNPA were shown to be important for FNPA inactivation of two types of MAO. The inhibitory potency was significantly lower for compounds without either group. Furthermore, we found that all nitrophenyl azide isomers except 2-nitrophenyl azide were photodependent inhibitors of MAO-B. Under the same experimental conditions none of the compounds photoinactivated MAO-A. On the basis of these findings, mechanisms for FNPA inhibition of the two types of MAO are discussed.

4-Fluoro-3-nitrophenyl azide, a selective photoaffinity label for type B monoamine oxidase

The effects of 4-fluoro-3-nitrophenyl azide (FNPA) on types A and B monoamine oxidase in rat brain cortex were studied using serotonin and phenylethylamine as substrates respectively. FNPA competitively inhibited the oxidative deamination of both serotonin (Ki = 3 microM) and phenylethylamine (Ki = 0.78 microM) in the dark. Upon photoirradiation in the presence of FNPA, a photodependent inhibition of type B MAO activity resulted. This photodependent inhibition was apparently irreversible since there was no recovery of activity upon washing of the photolyzed FNPA-enzyme mixture. Additional evidence for the photoinduced covalent binding of FNPA to type B MAO is that non-competitive inhibition kinetics resulted after photolysis. The specificity of the photodependent incorporation of FNPA to type B MAO was shown by the protective effect of phenylethylamine and by decreased [3H]pargyline labeling after the enzyme was photolyzed with FNPA. Under the same experimental conditions, only minimal photodependent inhibition of type A MAO by FNPA was found. The observed difference in the efficiencies of the photodependent inactivation of the two types of MAO by FNPA suggests that there is a conformational or a structural difference in the active sites of the two types of MAO. The active site of type B MAO could be characterized by utilizing FNPA as a photoaffinity labeling probe.

Interaction of N-(2-nitro-4-azidophenyl)-serotonin with two types of monoamine oxidase in rat brain

The effects of N-(2-nitro-4-azidophenyl) serotonin (NAP-5-HT) on types A and B monoamine oxidase (MAO) in rat brain cortex were studied. In the dark this compound acted as a competitive inhibitor for both types A and B MAO (Ki values of 0.19 microM and 0.21 microM for types A and B MAO, respectively). Upon photolysis, NAP-5-HT became an irreversible inhibitor for only type B MAO. A 50% inhibition was obtained by irradiation of the enzyme in the presence of 35 nM NAP-5-HT. Furthermore the inhibition of type B MAO could be protected by including its substrate phenylethylamine during the irradiation. Under the same photolytic conditions photodependent inhibition of type A MAO by NAP-5-HT was not clearly observed. These results provide further evidence that there is a fundamental difference in the active site of the two types of MAO in brain. NAP-5-HT may be a useful photoaffinity probe for characterizing the active site of type B MAO.