[Liver cancer treatment with mitochondrial homeostasis]

Systemic treatment, including molecular targeted therapy, immunotherapy, and chemotherapy, is an important means of achieving long-term survival in patients with intermediate-and advanced-stage liver cancer. However, some patients are insensitive to treatment and even develop drug resistance. Mitochondria are the center of cellular energy metabolism and, at the same time, are the priority targets for systemic therapy. Mitochondrial homeostasis plays an important role in the treatment of liver cancer. The relationship between the two advances is elucidated so as to provide better ideas for the clinical treatment of liver cancer.

[Research progress on the mechanism and response strategies of molecular targeted drug resistance in liver cancer]

Molecular targeted drugs are one of the treatments for hepatocellular carcinoma (HCC), the primary factor influencing their therapeutic efficacy is drug resistance. Diminished drug intake, greater efflux, improved DNA damage repair capacity, aberrant signal pathways, hypoxia, epithelial-mesenchymal cell transition, and the cellular autophagy system are summarized herein as aspects of the drug resistance mechanism. Simultaneously, effective strategies for addressing drug resistance are elaborated, providing ideas for better clinical treatment of HCC.

The bipolar charge plasma spectrometer (BCPS) based on the 2π-field-of-view double-channel electrostatic analyzer

In this paper, we propose a bipolar charge plasma spectrometer based on the double-channel electrostatic analyzer for simultaneously measuring thermal ions and electrons with a 2π hemispherical field-of-view. Both ions and electrons within the wide field-of-view enter the spectrometer, pass through the variable geometric factor channel, and are then separated by the double-channel electric fields. Two microchannel plates are accommodated at the exit of the analyzer for ion and electron detection. The main performance of the spectrometer has been obtained from on-ground calibration. With the electrostatic deflectors and the cylindrically symmetric structure, the spectrometer provides simultaneous measurements of thermal ion and electron velocity distributions with a shared field-of-view of 360° (azimuth angle) by 90° (elevation angle) and a broad energy range for both ions and electrons. The ion analyzer constant and the electron analyzer constant are 11.1 and 9.7, respectively. The detecting energy range of 33.3-44.4 keV for ions and 29.1-38.8 keV for electrons can be obtained by using the sweeping electrostatic analyzer voltage range of 3-4000 V. The ion and electron energy resolutions are 9.6% and 6.1%, respectively. The variable geometric factor function provides a large geometric factor adjusting range for both ion and electron measurements by two orders of magnitude, which fulfills the requirements of a large dynamic flux range for simultaneous measurements of space thermal plasma in the solar wind and magnetosphere.

STAT3/LINC00671 axis regulates papillary thyroid tumor growth and metastasis via LDHA-mediated glycolysis

Lactate dehydrogenase A (LDHA), a critical component of the glycolytic pathway, relates to the development of various cancers, including thyroid cancer. However, the regulatory mechanism of LDHA inhibition and the physiological significance of the LDHA inhibitors in papillary thyroid cancer (PTC) are unknown. Long non-coding RNA (lncRNA) plays a vital role in tumor growth and progression. Here, we identified a novel lncRNA LINC00671 negatively correlated with LDHA, downregulating LDHA expression and predicting good clinical outcome in thyroid cancer. Moreover, hypoxia inhibits LINC00671 expression and activates LDHA expression largely through transcriptional factor STAT3. STAT3/LINC00671/LDHA axis regulates thyroid cancer glycolysis, growth, and lung metastasis both in vitro and in vivo. In thyroid cancer patients, LINC00671 expression is negatively correlated with LDHA and STAT3 expression. Our work established STAT3/LINC00671/LDHA as a critical axis to regulate PTC growth and progression. Inhibition of LDHA or STAT3 or supplement of LINC00671 could be potential therapeutic strategies in thyroid cancer.

[Research on the influence of coronavirus infection on maternal and infant health]

COVID-19 spreads with strong infectivity and triggered a public health crisis, home and abroad. SARS-CoV-2 has high pathogenic homology with SARS-CoV and MERS-CoV, and the three coronaviruses all belong to the Betacoronavirus family. Due to pregnant women's physical and psychological vulnerability, they are the susceptible and high-risk groups during the epidemic. This article will review the reports on adverse effects of maternal and fetal health during the SARS and MERS and COVID-19 epidemics to provide evidence for the clinical management and prevention and control of pregnant cases in SARS-CoV-2 infection.

[Risk factors and clinical prognosis analysis of carbapenem-resistant Enterobacterales bacteria nosocomial infection]

Objective: To explore the risk factors for carbapenem-resistant Enterobacterales (CRE) infection and death. Methods: A case-control analysis of 482 inpatients in 18 secondary or tertiary hospitals in Beijing in 2018 was conducted. Patients infected by CRE were selected as the case group (n=247), and infected by carbapenem susceptible Enterobacterales (CSE) as the control group (n=235). The risk factors and clinical prognosis of CRE infection were analyzed by single factor analysis and multivariate logistic regression analysis. Results: CRE were resistant to most antimicrobials, but were highly sensitive to colistin and tigecycline, with sensitivity of 94.0% and 99.5%, respectively. Multivariate analysis showed that prior 30-day tracheal intubation (OR=2.607, 95%CI: 1.655-4.108, P<0.001), empirical treatment using third or fourth generation cephalosporins (OR=2.339, 95%CI: 1.438-3.803, P=0.001), carbapenems (OR=2.468, 95%CI: 1.610-3.782, P<0.001) and quinolones (OR=2.042, 95%CI: 1.268-3.289, P=0.003) were independent risk factors for CRE infection. Mechanical ventilation (OR=3.390, 95%CI: 1.454-7.904, P=0.005), heart failure (OR=4.679, 95%CI: 1.975-11.083, P<0.001), moderate or severe liver disease (OR=3.057, 95%CI: 1.061-8.806, P=0.038), prior 30-day quinolones exposure (OR=2.882, 95%CI: 1.241-6.691, P=0.014) and septic shock (OR=7.772, 95%CI: 3.505-17.233, P<0.001) were independent risk factors for death after CRE infection. Conclusions: Reducing the use of antimicrobials and invasive procedures such as prior 30-day tracheal intubation may reduce the probability of CRE infection. Grading the severity of the underlying disease in patients with CRE infection, as well as predicting and preventing the occurrence of septic shock will help reduce the risk of death.

[Association of thallium exposure during pregnancy with maternal blood pressure and hypertensive disorder complicating pregnancy]

Objective: To investigate the association of thallium exposure during pregnancy with pregnant blood pressure changing and hypertensive disorder complicating pregnancy(HDCP). Methods: A total of 3 240 pregnant women who had establish maternal health care manual in Ma'anshan Maternal and Child Health-Care Hospital and met the inclusion and exclusion criteria were included in this study between May 2013 and September 2014.We collected their general demographic characteristics and blood pressure through questionnaire and medical records. Meanwhile we measured serum thallium concentrations by experimental technology. We use multiple logistic regression to analyze the association between thallium exposure during pregnancy and HDCP. Mixed linear model were used to analyze the association between thallium concentration and maternal systolic blood pressure (SBP) or diastolic blood pressure(DBP) in different trimesters Results: The age of 3 240 pregnant woman was (26.61±3.64) years, and the detection rate of HDCP was 5.9%(191).The median (P₂₅, P₇₅) of thallium concentrations in first trimester, second trimester and third trimester were 62.96 (50.79, 77.04), 62.19 (50.87, 75.26), 48.84 (38.00, 66.00) ng/L, respectively. Multiple logistic regression results suggested after adjusting various confounding factors, the risk of HDCP in pregnant women with high concentrations of thallium (>77.04 ng/L) in the first trimester is 1.75 (95%CI:1.01-3.03) times higher than which with low concentrations(<50.82 ng/L). Mixed linear model results suggested there are positive correlation between thallium concentrations with maternal DBP in first trimester (β=1.12, 95%CI: 0.39-1.85). Conclusion: Exposure to high levels of thallium during first trimester may increase the risk of HDCP, and the exposure of thallium may be effective to DBP of pregnant.

Forensic Application of Plant Evidence

Abstract

With the increasingly obvious role of plant evidence in case detection, forensic botany, which provides clues and evidence in crime scene investigation by using botanical research method has attracted growing attention. The common experimental techniques used in forensic botany are morphological examination, physical and chemical examination, molecular genetic examination, and so on. This paper briefly expounds the advantages and disadvantages of different test methods, summarizes the problems that need to be paid attention to in the application of forensic botany by arranging the related literatures and cases of forensic botanical research, in order to provide reference for scene investigation of cases.

[Analysis of the clinical features and the risk factors of severe adenovirus pneumonia in children]

Objective: To analyze the clinical characteristics, risk factors for critical illness and death of severe adenovirus pneumonia in children, so as to provide clinical evidences for early diagnosis and reliable treatment. Methods: A total of 75 pediatric cases with severe adenovirus pneumonia admitted to Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January to October 2019 were studied. The clinical features, laboratory and imaging data, therapeutic approaches, efficacy of the treatments and prognosis were investigated retrospectively. Patients were divided into severe group and critical group. Chi square test and Mann-Whitney U rank sum test were used to analyze the data of the two groups. The risk factors for critical illness and death were analyzed by univariate and multivariate Logistic regression. Results: Among the 75 children, there were 52 males and 23 females, aged from 3 months to 8 years, including 30 of severe cases and 45 of critical case. The positive rate of adenovirus antigen in nasopharyngeal swab was 21% (15/72), and the positive rate of serum adenovirus IgM antibody was only 13% (10/75). However, the positive rate of adenovirus nucleic acid in nasopharyngeal swab was 75% (21/28). What is more, the positive rates of metagenomics next generation sequencing (mNGS) in plasma and bronchoalveolar lavage fluid were 92% (33/36) and 96% (54/56), respectively, of which 95% (63/66) were confirmed as adenovirus type 7. Relatively high dose of ribavirin and integrated therapeutic approaches (respiratory support, glucocorticoids, immunoglobulin and organ supportive therapies) were used. The recovery rate was 77% (58/75), the improvement rate was 8% (6/75) and the mortality rate was 15% (11/75). The proportion of children with the duration of fever longer than 3 days after ribavirin treatment in the critical group was significantly higher than that in the severe group(51% (18/35) vs. 8% (2/26), χ²=12.949, P<0.05). The risk factors for critical illness were younger than 4 years, longer duration of fever before and after admission to PICU, oxygenation index<300 mmHg (1 mm Hg=0.133 kPa), ferritin>1 000 μg/L, lactate dehydrogenase (LDH)>1 500 U/L, 5 lung lobes involvement, pleural effusion and (or) air leakage (all P<0.05). Among them, 5 lung lobes involvement was the independent risk factor for critical illness (adjusted OR=49.641, 95%CI 4.186-588.618, P=0.002). Risk factors for death included longer duration of fever after being admitted to PICU, oxygenation index<100 mmHg, ferritin>2 000 μg/L, interleukin (IL)-6>100 ng/L, LDH>1 500 U/L, pleural effusion and (or) air leakage (all P<0.05). Among them, IL-6>100 ng/L was the independent risk factor for the mortalities of critically ill children (adjusted OR=16.094, 95%CI 2.059-25.787, P=0.008). Conclusions: The mortality rate of severe pediatric adenovirus pneumonia caused by adenovirus type 7 is high. High positive rates of adenovirus nucleic acid in nasopharyngeal swabs and mNGS in plasma or bronchoalveolar lavage fluid contribute to early diagnosis, and mNGS can also be used for serotyping. Younger children under 4 years of age, persistent fever, extensive pulmonary lesions and significantly increased inflammatory cytokines such as IL-6 are warning indicators for critical illness and poor prognosis. Relatively high dose of ribavirin combined with integrated therapeutic approaches are beneficial for prognosis.

[Analysis of EGFR mutation and clinical features of lung cancer in Yunnan]

Objective: To analyze the EGFR mutation profile of lung cancer patients in Yunnan, and to provide evidence for clinical personalized treatment. Methods: Demographic and clinical data of 2 967 lung cancer patients undergoing EGFR identification were collected and analyzed from January 2014 to August 2019 in Yunnan Cancer Hospital. Results: The proportion of EGFR mutation in 2 967 patients with lung cancer was 46.2%. Univariate analysis showed that the proportion of EGFR mutation in women was higher than that in men (P<0.001) and displayed a downward trend with age (P=0.03). The mutation rate of ethnic minorities was higher than Han (P=0.012). Mutation rate in patients without smoking history was higher than those with smoking history (P<0.001), and patients without drinking history was higher than patients with drinking history (P<0.001). Mutation rate in patients without family history of lung cancer was higher than those with family history (P=0.008). The mutation rate of adenocarcinoma was higher than other pathological types (P<0.001). The mutation rate was different among stages, and it was higher in early patients than that in advanced patients (P<0.001). The mutation rate of tissue specimens was higher than those of cytology and peripheral blood samples (P<0.001). The mutation rate of Xuanwei area was lower than that in non-Xuanwei area (P<0.001). Multivariate analysis showed that gender (P<0.001), age (P=0.036), smoking history (P<0.001), pathological type (P<0.001), specimen type (P<0.001), and whether or not Xuanwei area (P<0.001) were the independent factors of EGFR mutation.The EGFR mutation was more common in female, non-smokers, adenocarcinoma, non-Xuanwei area, tissue specimen and young lung cancer patients.The mutation types of EGFR in 1 370 cases mainly included 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area was L858R, while in non-Xuanwei area was 19-Del.The mutation rates of G719X, G719X+ L861Q, G719X+ S768I, and S768I in Xuanwei were higher while the mutation rates of 19-Del, L858R, and 20-ins were lower than non-Xuanwei area (P<0.05). The 19-Del mutation rate of ethnic minorities is higher than that of Han (P<0.001). The combined mutation rate of G719X, L861Q in Han was higher than that of ethnic minorities (P=0.005). Conclusions: The EGFR mutation rate in lung cancer patients in Yunnan is similar to Asian and Chinese, and higher in female, non-smokers, adenocarcinomas, young and non-Xuanwei area patients. The most common types of EGFR mutation in Yunnan are 19-Del and L858R. The predominant mutation of EGFR in Xuanwei area is L858R, while in non-Xuanwei area is 19-Del. The mutation rates of G719X, G719X+ L861Q, G719X+ S768I and S768I are higher in Xuanwei patients than those in non-Xuanwei patients. The combined mutation rate of G719X and L861Q in Han nationality is higher than that of ethnic minorities.

[Analysis on epidemic situation and spatiotemporal changes of COVID-19 in Anhui]

We used the epidemic data of COVID-19 published on the official website of the municipal health commissions in Anhui province to map the spatiotemporal changes of confirmed cases, fit the epidemic situation by the population growth curve at different stages and analyze the epidemic situation in Anhui Province. It was found that the cumulative incidence of COVID-19 was 156/100 000 by February 18, 2020 and the trend of COVID-19 epidemic declined after February 7 with a change from J-shaped curve to S-shaped curve. As the reporting time of cases might be 3-5 days later than the actual onset time, the number of new cases in Anhui province actually began to decline around February 2 to February 4, 2020.

[Adverse maternal and infant health effects caused by thallium exposure during pregnancy]

Thallium is a highly toxic heavy metal. The adverse maternal and infant health effects caused by thallium exposure during pregnancy have also attracted more and more scholars' attention. This study focused on the sources of thallium exposure and its influencing factors, the association between thallium exposure during pregnancy and pregnancy complications and adverse birth outcomes in newborns, the effects of thallium exposure during pregnancy on children's growth and development after birth. In terms of potential mechanisms, the related research progress was reviewed in this study, which could provide a new basis for further research on the harm, prevention and control of thallium exposure during pregnancy.

Chronic active EBV infection associated with NK cell lymphoma and hemophagocytic lymphohistiocytosis in a 27-year-old woman: A case report

RATIONALE

Chronic active Epstein-Barr virus infection (CAEBV) is a common infectious disease that often affects multiple organs or systems. However, it is liable to be neglected and misdiagnosed owing to its insidious onset, lack of specific findings in the early phase, and a general lack of awareness among clinicians. PATIENT CONCERNS:: a 27-year-old woman case has been described who was initially misdiagnosed as drug-induced liver injury due to onset presentation of mild splenomegaly, recurrent liver dysfunction, and disputable pathological evidence of liver biopsy.

DIAGNOSES

CAEBV complicated with natural killer (NK) cell lymphoma and hemophagocytic lymphohistiocytosis (HLH) was diagnosed by in situ hybridization of liver tissue section with EBV-encoded RNA -1 probe and flow cytometry of bone marrow.

INTERVENTIONS

After admission, the patient received symptomatic treatment and antiviral therapy (combination of acyclovir and foscarnet sodium) as well as adjuvant treatment (thymosin alpha 1 and methylprednisolone); later, the patient received etoposide and dexamethasone for diagnosis of EBV associated HLH. Subsequently, the disease progressed to NK cell lymphoma and the patient received the revised EPOCH chemotherapy regimen [etoposide (100 mg/d, d1-5), dexamethasone (7.5 mg/d, d1-5; 5 mg/d, d6-14), cyclophosphamide (0.8 g/d, d1-2), and pegaspargase (3750 u/d, tid, d1-2)].

OUTCOMES

Although the patient received a series of therapies and other comprehensive measures, finally she died of gastrointestinal hemorrhage and multiple organ failure.

LESSONS

Liver is one of the main target organs of EBV infection. In the clinical setting of unexplained fever and liver injury, it is necessary to be aware of CAEBV, as well as its fatal complication such as EBV associated NK cell lymphoma and HLH.

[A preliminary study on the outcome of lower-risk myelodysplastic syndrome by low-dose decitabine]

目的

评价小剂量地西他滨治疗较低危骨髓增生异常综合征（MDS）患者的初步疗效及安全性，探讨MDS相关基因突变的临床意义。

方法

纳入浙江省4所医院收治的62例较低危MDS患者，治疗分2组，地西他滨组（地西他滨12 mg·m⁻²·d⁻¹，连续5 d）和支持治疗组，检测与MDS预后相关的15项基因突变情况。比较两组患者的总体有效率（ORR）和无进展生存（PFS）时间，分析其与基因突变的相关性。

结果

62例患者中，可评估患者51例，其中地西他滨组24例，支持治疗组27例。与支持治疗组相比，地西他滨组的ORR（66.7%对29.6%，χ²=6.996，P=0.008）和中位PFS时间显著改善（未达到对13.7个月，P=0.037）。51例患者中20例（39.2%）检测到基因突变阳性，其中4例患者单纯SF3B1阳性，均在支持治疗组。与基因突变阴性患者相比，16例基因突变阳性（除单纯SF3B1阳性）患者中位PFS时间显著缩短（9.2个月对18.5个月，P=0.008），其中地西他滨组8例患者中6例有效，支持治疗组无一例（0/8）有效。地西他滨治疗期间主要不良反应为3~4级粒细胞减少（45.8%），3~4级感染发生率为33.3%（8/24）。

结论

该研究小系列患者的初步结果表明应用小剂量地西他滨治疗较低危MDS患者可能有效，对于基因突变患者也可获益，且患者耐受，值得临床试验进一步明确其临床意义。

Identification of Magnolia wufengensis (Magnoliaceae) cultivars using phenotypic traits, SSR and SRAP markers: insights into breeding and conservation

A combination of phenotypic characterization and molecular markers may provide reliable information on new plant varieties and elucidate the conservation status of rare species. Five newly developed Magnolia wufengensis cultivars, an endangered plant species endemic to Hubei Province, China, possess more distinctive phenotypes than common Magnolia cultivars. With reference to a wild species population of M. wufengensis and a population of Magnolia denudata, morphological traits of flower organs, simple sequence repeat (SSR), and sequence-related amplified polymorphism (SRAP) markers were used. In the morphological study, six traits of floral organs were investigated and their relationships were analyzed between cultivars. In the genetic study, 9 SSR primer pairs and 10 SRAP primer combinations were screened. The five cultivars maintained a high level of genetic diversity. Genetic diversity of each M. wufengensis cultivar was much lower than that of the wild population, but was slightly higher than that of the M. denudata population. Analysis of molecular variance (AMOVA) revealed that genetic variation among populations was 20% (SRAP) and 30% (SSR), which showed a high degree of genetic differentiation among populations of the five cultivars. The dendrograms illustrated a clear separation between M. wufengensis populations and outer species, and identified two major groups among cultivars. Correlation analysis indicated a good fit between the two marker systems, but a relatively low fit between morphological and genetic traits (SRAP: r = 0.60, SSR: r = 0.52). These findings provide reliable references for the application of these molecular markers in the breeding and conservation of M. wufengensis.

[A comparative study of diagnostic efficacy of different diagnostic/ classification criteria in Takayasu arteritis]

OBJECTIVE

This study aimed to analyze and evaluate the diagnostic efficacy of Ishikawa's, the modified Ishikawa's criteria, 1990 American College of Rheumatology (ACR ) classification criteria and the diagnostic model based on Chinese population in Chinese TA patients.

METHODS

One hundred and forty-nine patients with Takayasu arteritis and 126 patients with other vascular disorders which involved aorta or its branches were recruited in this study.All the patients were admitted to the Department of rheumatism and Immunology clinic or inpatient department of Zhongshan Hospital affiliated to Fudan University from January 1(st), 2008 to June 31(st), 2015.General characteristics, clinical manifestations, laboratory results and imaging data of all the patients were collected.Sensitivity, specificity, accuracy and area under receiver operating characteristics (ROC) curve of different criteria were analyzed.

RESULTS

Sensitivity, specificity, accuracy and area under ROC curve of Chinese diagnostic model were 90.60%, 80.95%, 86.18%, and 85.80%, respectively, while those of Ishikawa criteria were 34.23%, 99.21%, 64.00%, and 66.70%, respectively.These four indicators of the modified Ishikawa criteria were 84.13%, 79.87%, 81.82%, and 82.00%, respectively and that of ACR criteria were 83.89%, 83.33%, 83.64%, and 83.60%, respectively.No significant difference was found between any two of Chinese diagnostic model, the modified Ishikawa criteria and ACR criteria in all the indicators.Sensitivity of Chinese diagnostic model was highest, while specificity of Ishikawa criteria was the highest.Among these four criteria, the diagnostic efficacy of Chinese model was the best and that of Ishikawa criteria was the worst.

CONCLUSION

Chinese diagnostic model, which is based on Chinese population and adopts advanced imaging modality, has better diagnostic efficacy.

Characteristics of synonymous codon usage bias in the beginning region of West Nile virus

Adaptation in the overall codon usage pattern of West Nile virus (WNV) to that of two hosts was estimated based on the synonymous codon usage value (RSCU). Synonymous codon usage biases for the beginning coding sequence of this virus were also analyzed by calculating the usage fluctuation for each synonymous codon along the target region (the first 270 codon sites of the whole coding sequence of WNV). Adaptation of WNV to Anopheles gambiae regarding the overall codon usage revealed a mixture of synonymous codon usage patterns between this virus and its vector. Regarding the adaptation of WNV to its dead-end host and codon usage, although a mixture of overall codon usage patterns exists, the number of codons with reversed tendency codon usage is lower than that between the virus and its vector. In addition, some codons with low RSCU values for this virus are highly selected in the beginning translation region of WNV, while codons with low RSCU values in this region tend to pair with tRNAs present in low abundance in the host, suggesting that highly selected codons in a specific region in the beginning region of WNV are, to some degree, influenced by the corresponding low tRNA abundance of hosts to regulate the translation speed of the WNV polyprotein.

Combination of IFNγ and chemotherapeutic agents increase TRAIL sensitivity of neuroblastoma cell lines

OBJECTIVE

Aim of the study was to further evaluate the role of caspase 8 and death receptors (DR) in the TRAIL-induced apoptosis of neuroblastoma (NB) cell lines.

METHODS

Caspase 8 mRNA expression was monitored by RT-PCR. Caspase 8, DR5 and DR4 protein expression were monitored by Western blot analysis. The effects of IFNγ, TRAIL, IFNγ+TRAIL, caspase 8 inhibitor+TRAIL and IFNγ+chemotherapeutic agents+TRAIL on the growth and apoptosis of NB cells were detected with MTT and flow cytometry. The relative caspase 8 activity was measured with colorimetric assay.

RESULTS

Caspase 8 expression was induced by IFNγ in the NB cell line SKNDZ. TRAIL alone did not induce apoptosis compared with controls but a combination of IFNγ+TRAIL and IFNγ+chemotherapeutic agents+TRAIL significantly induced cell apoptosis in SY5Y cells. Etoposide and doxorubicin induced DR5 but not DR4 in NB cell lines. SKNDZ cells expressing caspase 8 after treatment with IFNγ were still resistant to TRAIL but sensitive to TRAIL after the induction of DR5.

CONCLUSIONS

Sensitization of NB cells to TRAIL may be mediated by the upregulation of caspase 8 with IFNγ and DR5 with chemotherapeutic agents. This suggests that caspase 8 and death receptors play a very important role in TRAIL-induced apoptosis of NB cells and a combination of IFNγ, TRAIL and chemotherapeutic agents may be a new and interesting anticancer treatment strategy for NB.

The pharmacokinetics of C-glycosyl flavones of Hawthorn leaf flavonoids in rat after single dose oral administration

Hawthorn leaf flavonoids (HLF) are used in the treatment of cardiovascular diseases. Various potential pharmacodynamic effects have been observed for vitexin-4''-O-glucoside (VOG) and vitexin-2''-O-rhamnoside (VOR) which are the main constituents of HLF. The aim of this study was to investigate the pharmacokinetics of VOG and VOR when a single dose of HLF was administrated orally. The levels of VOG and VOR in plasma, tissues (heart, liver, spleen, lung, kidney and brain), bile, urine and feces were measured by HPLC-UV. The results showed that VOG and VOR have the similar pharmacokinetics. Both of them were absorbed quickly into plasma with maximal plasma concentrations of VOG and VOR being reached within 0.75 h. The mean elimination half-life (t(1/2)) of VOG and VOR were 2.53 h and 2.32 h, respectively. High levels of tissue distribution of VOG and VOR were observed in liver and kidney. No VOG and VOR were detected in brain tissue. There was no long-term accumulation of VOG and VOR in rat tissues examined. The total recovery of the dose in 24 hours was 64.91% (0.70% in urine; 64.21% in feces) for VOG and 89.01% (0.72% in urine; 88.29% in feces) for VOR. The cumulative VOG and VOR excreted in bile represented 0.58% and 13.38% of the doses, respectively. VOG and VOR in HLF were not efficiently absorbed in the rodent gastrointestinal tract.

Association of ACE, ACE2 and UTS2 polymorphisms with essential hypertension in Han and Dongxiang populations from north-western China

To assess the significance of polymorphisms of the genes for angiotensin-converting enzyme (ACE), angiotensin-converting enzyme 2 (ACE2) and urotensin II (UTS2) as risk factors for essential hypertension in two populations from north-western China, we enrolled 198 patients with essential hypertension and 131 healthy controls from the Han population and 120 patients with essential hypertension and 102 healthy controls from the Dongxiang population. Polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism were used to analyse gene polymorphisms. The results provided evidence that genetic variants of UTS2 and ACE2 may play a role in the development of essential hypertension in these populations. Polymorphisms of ACE were not associated with essential hypertension in either population. This is the first report showing that the S89N single-nucleotide polymorphism of the UTS2 gene is associated with essential hypertension.

Abnormal bone architecture and biomechanical properties with near-lifetime treatment of rats with PTH

Skeletal effects are described for near-lifetime treatment of young, female rats with recombinant human PTH (1-34) (PTH). Rats (5-8 wk of age) were administered 0, 5, 30, or 75 microg/kg x d sc PTH for up to 2 yr, as part of an oncogenicity evaluation, which is required by regulatory agencies for potential chronic therapies. Proliferative lesions were observed in the skeleton as described in Vahle et al. (1 ); in this paper, we describe the quantitative bone data for this study. In the appendicular skeleton, PTH stimulated trabecular and endocortical mineral apposition to the near exclusion of marrow spaces at 5 microg/kg, with some periosteal apposition at 30 microg/kg, followed by considerable periosteal apposition and altered geometry at 75 microg/kg. Increased bone mass was observed for all treatment groups that substantially exceeded normal levels attained by vehicle controls and exceeded skeletal efficacy reported previously for similar doses in shorter-term studies. Dose-dependent increases in osteocalcin levels and a linear increase in wet weight of femora were observed for the entire treatment duration, suggesting nearly continuous PTH stimulation of osteoblasts and skeletal growth throughout life. Histology showed many osteocytes and prominent osteoblasts, but a conspicuous absence of osteoclasts. Morphometry showed a lack of distinction between trabecular and cortical bone. Biomechanics of vehicle controls showed that optimal mechanical integrity for the normal skeleton is observed at about 11 months of age. PTH greatly strengthened and stiffened vertebra and femora; however, the midshaft showed reduced toughness and increased brittleness with treatment, which was not the case for vertebra. Related studies of 6 and 9 months duration showed that the optimal duration for PTH skeletal efficacy was about 6 months in rats, based on toughness, strength, ultimate displacement, and architecture, especially for cortical bone. Therefore, treatment duration is an under appreciated aspect of PTH pharmacology; and PTH skeletal effects are a complex function of dose and duration. Comparative analyses showed that short-term treatment (6 months or less) is more advantageous than near-lifetime treatment, because PTH stimulates skeletal growth throughout life, resulting in abnormal architecture and untoward biomechanical properties in rats.

[Relationship between alpha-ENaC gene Thr663Ala polymorphism and ischemic stroke]

OBJECTIVE

To determine the relationship between Thr663Ala polymorphism in amiloride-sensitive epithelial sodium channel alpha-subunit (alpha-ENaC) gene and ischemic stroke in Chinese population.

METHODS

Two hundred and ninety-four patients with cerebral infarction and 280 controls without stroke were screened by polymerase chain reaction (PCR) and corresponding Thr663Ala polymorphism probe hybridization.

RESULTS

Thr663Ala polymorphism was in agreement with Hardy-Weinberg equilibrium. Both the carriers proportion (70.75%) and the frequency (48.64%) of 663Ala allele in patients were more prevalent than that in controls (62.86% and 40.89%) (P < 0.05). The presence of at least one 663Ala allele conferred an odds ratio for stroke of 1.429 (95%CI: 1.009-2.025), and the proportion of attributable risk of population (PAR%) was 11.63%.

CONCLUSION

Thr 663Ala polymorphism of alpha-ENaC gene may be a genetic risk of ischemic stroke in Chinese population.

[Structural elucidation of a new perylenequinone]

AIM

To study the chemical constituents from the mycelia of Hypomyces sp.

METHODS

Silica gel column chromatography was employed for the isolation and purification. The structure of compound 1 was elucidated on the basis of spectral analysis.

RESULTS AND CONCLUSION

A new perylenequinone, named hypomycin B 1, was isolated from the mycelia of Hypomyces sp.

[Morphometric study on the effects of estrone on bone in vitro]

AIM

To study the effects of estrone on the bone resorption and bone formation in vitro.

METHODS

Long bones from 16-day-old female mouse fetuses were cultured in BGJb medium for 48 h. The bones were harvested, then bones length and length of their diaphyses were measured under stereo microscope. The histomorphormetric analyses on midlongitudinal sections of bones were performed. The numbers of osteoclasts and hypertrophic chondrocytes were observed under biological microscope.

RESULTS

Compared with control, there were significant increase in bones length and length of their diaphyses after treated with 10(-7) mol/L estrone. Under this condition, decreased osteoclasts and increased hypertrophic chondrocytes were observed, too.

CONCLUSION

Estrone stimulates bone formation and inhibites bone resorption in vitro.

The amygdala: site of genomic and nongenomic arousal of aldosterone-induced sodium intake

BACKGROUND.: Mineralocorticoids act on the brain to influence sodium intake, and they do so via intracellular type I receptors and possibly also via a direct membrane action, as they do in the kidney. One brain area implicated by lesion studies investigating the regulation of sodium appetite aroused by adrenal steroids is the amygdala.

METHODS

To examine the mechanism by which mineralocorticoids act in the amygdala to arouse salt intake via a genomic and or membrane mode of action, rats were bilaterally fitted with cannulae directed to terminate in the amygdala. The genomic action of mineralocorticoids in arousing sodium intake was investigated by the administration of antisense oligodeoxynucleotides (ASDNs) against the mineralocorticoid receptor, and its effects on deoxycorticosterone (DOCA)-induced sodium intake over the course of several days was examined. The nongenomic action of mineralocorticoids on sodium intake was investigated by implantation into the amygdala of DOCA, aldosterone (ALDO), or their A-ring-reduced tetrahydro derivatives, 15 minutes prior to access to saline. Sodium intake was monitored immediately thereafter.

RESULTS

Treatment of rats in the amygdala with ASDN against the mineralocorticoid receptor inhibited DOCA-induced sodium intake, whereas ASDN against the glucocorticoid receptor or sense/scrambled sequences had no effect. DOCA and ALDO increased saline intake within 15 minutes after steroid application. Similarly, the application of A-ring-reduced 3beta,5beta tetrahydroaldosterone and 5 alpha-tetrahydrodeoxycorticosterone produced the same increases in sodium intake.

CONCLUSIONS

Together, the data imply that adrenal steroids, in addition to acting through classic cytosolic receptors, may also act on membrane receptor systems, producing rapid changes in behavior.

[A novel chiral selector in capillary electrophoresis--beta-cyclodextrin polymer]

Three chiral selectors CM-beta-CD, EP-beta-CD, beta-CD were studied for the enatio-separation of three drugs under optimum conditions respectively. The results demonstrate that the resolving power for the drugs is as follows CM-beta-CD > EP-beta-CD > beta-CD, with the exception of lobeline. This is due to the--CH2COOCH3 group of CM-beta-CD, which will change the combination and improve the recognition on guest molecules. Although EP-beta-CD is inferior to CM-beta-CD for the separation of chlorpheniramine and verapamil, it has excellent recognition on lobeline and it has not been reported previously. In most cases EP-beta-CD is superior to beta-CD. The explanations are: (1) EP-beta-CD has good solubility in water, which enables high concentrations to be used and consequently achieves excellant separation of racemic compounds, (2) the polymerization of beta-CD changes the properties of CD units and the process produces a more rigid and different conformation from CD, (3) we must attribute much merits to the cooperation or synergism of two, three or even more CD moieties of two polymers for inclusion. Complexation with analytes possesses more than one guest part in their structure.

Ovarian steroid regulation of angiotensin II-induced water intake in the rat

Spontaneous water intake as well as thirst elicited by ANG II has been shown to be influenced by the stage of the estrous cycle in the female rat. In these experiments, the contribution of each of the ovarian steroid hormones to the regulation of water intake was examined. Ovariectomized female rats were given replacement doses of estrogen, progesterone, or both, and their responsiveness to an intracerebroventricular injection of ANG II was tested. Forty-eight-hour treatment with estradiol benzoate attenuated ANG II-induced thirst by as much as 70% compared with control animals. The effect of estrogen on drinking was dose dependent and could be completely blocked with concurrent administration of the antiestrogen CI-628. In contrast, progesterone, given alone or after estrogen, did not significantly affect ANG II-induced water intake when animals were tested at 4 or 24 h after steroid administration. A central interaction between the peptide hormone ANG II and estrogen, involving a genomic mechanism, may underlie the cyclicity in water intake behavior observed in the rat.

Adrenal steroid regulation of neurotrophic factor expression in the rat hippocampus

Adrenal steroids and neurotrophic factors are important modulators of neuronal plasticity, function, and survival in the rat hippocampus. Adrenal steroids act through two receptor subtypes, the glucocorticoid receptor (GR) and the mineralocorticoid receptor, and activation of each receptor subtype has distinct biochemical and physiological consequences. Adrenal steroids may exert their effects on neuronal structure and function through the regulation of expression of neurotrophic and growth-associated factors. We have examined adrenal steroid regulation of the neurotrophins brain-derived neurotrophic factor, neurotrophin-3, and basic fibroblast growth factor, as well as the growth associated protein GAP-43, through activation of GR or mineralocorticoid receptor with selective agonists. Our findings indicated that in CA2 pyramidal cells, adrenalectomy resulted in decreases in the levels of basic fibroblast growth factor and neurotrophin-3 messenger RNA, which were prevented by activation of mineralocorticoid but not glucocorticoid receptors. Adrenalectomy-induced increases in GAP-43 and brain-derived neurotrophic factor messenger RNA levels could be blocked by activation of glucocorticoid receptors in CA1, but not in CA3, pyramidal cells. Thus the extent to which adrenal steroids regulate hippocampal neurotrophic and growth-associated factors, appears to be dependent both on the adrenal steroid receptor subtype activated and on the hippocampal subregion examined.

Regulation of glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acids by selective agonists in the rat hippocampus

Adrenal steroids can have prodigious effects on the structure, function, and survival of hippocampal neurons. In the rat hippocampus, the actions of adrenal steroids are mediated by two receptor types, the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR). Using in situ hybridization, we have examined the regulation of the messenger RNAs (mRNAs) encoding the glucocorticoid and mineralocorticoid receptors, by aldosterone, which acts selectively through MR, and by RU28362, which acts selectively through GR. Our results demonstrate that there is autoregulation of each receptor subtype, such that activation of GR regulates GR mRNA levels and MR activation regulates MR mRNA expression. In addition, there is evidence that aldosterone, acting through MR, can affect the expression of GR mRNA. The extent to which a specific agonist can produce a significant change in the expression of a particular steroid receptor mRNA varies between the different subfields of the hippocampus.

Mapping of RNA accessible sites for antisense experiments with oligonucleotide libraries

Antisense experiments are often complicated by the lack of reliable methods for selecting effective antisense sequences. Chimeric oligodeoxynucleotide (ODN) libraries and ribonuclease H (RNase H) were used to identify regions on the 1253 nucleotide angiotensin type-1 receptor (AT1) mRNA that are accessible to hybridization with antisense ODNs. Phosphorothioate antisense ODNs targeted against accessible sites reduced AT1 receptor levels by at least 50% in cell culture. ODNs to 4 sites produced a 70% to 80% reduction. In contrast, most sequences targeted between accessible sites were ineffective. When injected into the brains of rats, ODNs targeted to accessible sites reduced AT1 (by 65%) but not AT2 receptor levels. Additionally, AT1 receptor function as measured by agonist-induced water intake, was significantly attenuated in these rats. ODNs directed between accessible sites were ineffective at suppressing water intake. RNA mapping can be applied to any RNA target to facilitate selection of multiple, active antisense sequences for cell culture and in vivo experiments.

Intracerebroventricular Administration of Mineralocorticoid Receptor Antisense Oligonucleotides Attenuates Salt Appetite in the Rat

The anterior ventral third ventricle (AV3V) region of the brain contains high concentrations of mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) that are important in the maintenance of body fluid and electrolyte balance as well as other physiological processes. Daily intracerebroventricular pulse injections of MR antisense oligonucleotides significantly suppressed deoxycorticosterone acetate (DOCA) induced salt appetite in a dose-related manner. Similar administration of GR antisense or scrambled/sense oligonucleotide into the third ventricle failed to inhibit salt appetite. Salt appetite aroused after adrenalectomy was not suppressed by MR antisense oligonucleotide treatments but was suppressed by an antisense oligonucleotide directed against the angiotensin II AT1 receptor subtype. Receptor binding analysis demonstrated that MR and GR oligonucleotide treatments each reduced their respective receptor subtypes. Finally, although GR antisense oligonucleotide treatment was ineffective in suppressing DOCA-induced salt appetite, this treatment did increase stress induced corticosterone release as well as delayed the recovery of corticosterone to basal levels after stress.

Effect of saponins of Panax notoginseng on synaptosomal 45Ca uptake

AIM

To explore the calcium uptake antagonism of saponins of Panax notoginseng (PNS).

METHODS

Synaptosomes were prepared from rat cerebral cortex by using differential Ficoll gradients. The effects of PNS on synaptosomal 45Ca uptake were measured in vitro or after acute treatment.

RESULTS

PNS 50-800 mg.L-1 produced a concentration-rated inhibition of Ca2+ uptake [IC50 = 111 (46-176) mg.L-1]. Both initial and maximal uptake were inhibited. Similar effect was obtained after acute PNS treatment with 200 mg.kg-1 i.p. The blocking effect of PNS was reversed by calcium in media.

CONCLUSION

PNS is a calcium channel blocker in neurons.

Intracerebral administration of mineralocorticoid receptor antisense oligonucleotides attenuate adrenal steroid-induced salt appetite in rats

The amygdala contains mineralocorticoid (MR) and glucocorticoid receptors (GR) involved in the arousal of salt appetite. In the present investigation, MR antisense oligonucleotides injected into the amygdala inhibited salt appetite induced by systemic desoxycorticosterone (DOCA) but not adrenalectomy (ADX). In contrast, GR antisense or scrambled oligonucleotides had no effect on stimulated salt intake. MR antisense oligomers also decreased MR but not GR in amygdala, whereas GR antisense oligomers decreased GR but not MR. Immunocytochemical labelling of the biotinylated MR antisense revealed that distribution of the oligomer was restricted to the injection site, with incorporation in neurons and neighboring glial cells. Together, these data demonstrate the utility of receptor antisense oligonucleotides for investigating the central actions of adrenal steroids and the role of amygdala in MR in DOCA-induced sodium intake.

Intracerebroventricular administration of angiotensin type 1 (AT1) receptor antisense oligonucleotides attenuate thirst in the rat

The central actions of the peptide hormone angiotensin II (AngII) are importantly involved in body fluid homeostasis. Included amongst these actions is a potent dipsogenic response that has been implicated in the thirst that develops during many forms of extracellular dehydration. The use of highly selective receptor antagonists has revealed that the Type 1 (AT1), and not the Type 2 (AT2), AngII receptor subtype mediates this drinking response. More recently, antisense oligonucleotides specific for the AT1 receptor have been developed and after intracerebroventricular (i.c.v.) administration, they significantly reduce the dipsogenic response elicited by a similar injection of AngII. In the present study AT1 antisense oligonucleotides were used to further investigate their effect on experimentally induced thirst in the rat. In addition, immunohistochemical analysis of biotin-labeled oligonucleotides was performed in order to correlate the behavioral effects of the oligonucleotides with their distribution in the brain. The results demonstrated that the antidipsogenic effects of the oligonucleotides were dose and time-dependent and were limited to those thirst challenges that involve activation of the renin-angiotensin system. Collectively, these results demonstrate the efficacy and behavioral specificity of these oligonucleotides, as well as their utility in investigating the physiological role of cerebral AngII receptor subpopulations in various models of thirst.

Immunohistochemical mapping of angiotensin type 2 (AT2) receptors in rat brain

Recently developed antisera selective for angiotensin Type 2 (AT2) receptors were used to localize AT2 receptors in rat brain by immunohistochemistry. While the results from these experiments were largely consistent with previous autoradiographic and radioligand binding analyses of AT2 receptor populations in brain, there were also some notable differences in the distribution of immunoreactivity. More specifically, in agreement with previous studies, AT2 antisera detected apparent receptor populations in the locus coeruleus and the bed nucleus of the accessory olfactory tract, whereas AT2 receptor-immunoreactivity in the cerebellum was primarily associated with the Purkinje cell layer and the deep cerebellar nuclei rather than the molecular layer as has been previously reported in autoradiographic studies. Other regions with prominent immune-staining included all subfields of the hippocampus, which had been previously reported to contain exclusively AT1 receptors. Limbic structures such as the amygdala, thalamic areas such as the rhomboid thalamic nucleus, the paraventricular thalamic nucleus, hypothalamic areas such as the paraventricular hypothalamic nucleus, and the supraoptic nucleus also exhibited prominent AT2-immunoreactivity. In the paraventricular hypothalamic nucleus, AT2 receptor staining appeared to be associated primarily with the magnocellular neurons. In all regions examined, AT2 receptor immunoreactivity was associated with the cytoplasm and cell membrane and was not localized within the nucleus. Collectively, these results confirm and extend the neuroanatomical resolution of previous autoradiographic studies as well as identify new AT2 receptor populations in rat brain.

Intracerebroventricular administration of AT1 receptor antisense oligonucleotides inhibits the behavioral actions of angiotensin II

Antisense oligonucleotides were developed to study the expression and function of angiotensin type 1 (AT1) receptors in cultured cells and brain. In both liver epithelial WB and neuroblastoma N1E-115 cells AT1 antisense oligomers substantially decreased AT1 receptor density, whereas angiotensin type 2 (AT2) receptors remained unchanged. Similarly, repeated intracerebroventricular injections of AT1 antisense oligomers in rats decreased AT1 receptor density in hypothalamic-thalamic-septal tissue, and AT2 receptors were unaffected. Intracerebroventricular antisense oligomers also attenuated drinking elicited by intracerebroventricular angiotensin II but not the cholinomimetic carbachol. Collectively, these results demonstrate that antisense oligonucleotides attenuate angiotensin receptor expression and function in behaving animals.

Glucocorticoids facilitate mineralocorticoid-induced sodium intake in the rat

We confirm and extend the finding that glucocorticoids facilitate mineralocorticoid-induced sodium intake in the rat. First, we report that subcutaneous injections of dexamethasone (DEX) increase deoxycorticosterone-induced sodium intake. Second, we demonstrate that continuous intravenous infusions of either DEX or corticosterone or the TYPE II glucocorticoid receptor agonist RU28362 increases the sodium intake of aldosterone-treated rats. And third, we measured urine sodium loss and found that rats were in positive sodium balance while receiving aldosterone and the glucocorticoid agonist, suggesting that the increased intake of sodium was primary to renal sodium loss. When taken together with the fact that glucocorticoids can increase the TYPE I aldosterone-preferring receptor population in the brain, the results suggests a role for the glucocorticoid hormones in the arousal of sodium appetite in the rat.

[Effect of atrial natriuretic peptide on angiotensin II--and water deprivation-induced drinking behavior in rats]

Atrial natriuretic peptide (ANP) present in the brain has been reported to have profound effects on water and salt metabolism. This study was designed to observe the effect of intracerebroventricular (ICV) injection of ANP on drinking behavior of rats, induced by centrally administered angiotensin II (Ang II) and 24-hours water deprivation, by using a T-maze to measure the speed they ran in a runway for water rewards. In 24-hours water deprived rats ICV injection of ANP resulted in a significant decrease of either running speed or water intake. Drinking behavior induced by ICV injection of Ang II in normally hydrated rats was also significantly inhibited by a prior injection of ANP. These findings suggest that ANP in the brain plays an important role in the central control of drinking behavior.

[Effect of intracerebroventricular administration of atrial natriuretic polypeptide on unit discharges of rat paraventricular nucleus]

We have applied microelectrode technique to record 118 spontaneously firing units from the hypothalamus in rats. Detection of the recording sites showed that 84 were in the paraventricular nucleus (PVN) and 34 were near the PVN (near-PVN). After intracerebroventricular (i.c.v.) administration of atrial natriuretic polypeptide (ANP), 91% (P less than 0.005) of the PVN neurones and 71% (P greater than 0.05) of near-PVN neurones sensitive to ANP showed a significant decrease in spontaneously firing rate. After i.c.v. administration of hypertonic NaCl solution, 64.7% (P less than 0.005) of the PVN neurones and 61.1% (P greater than 0.05) of near-PVN neurones showed a significant increase in firing rate. The results indicate that i.c.v. administration of ANP profoundly inhibits the electrical activity of the PVN neurones, but hypertonic NaCl solution markedly stimulates the PVN neurones.

[Changes in vasoactive intestinal polypeptide levels in intestinal obstruction and the influence of da cheng qi decoction]

The role of vasoactive intestinal polypeptide (VIP) in small intestine obstructed rabbits and the therapeutic mechanism of Da Cheng Qi Decoction (DCQD) were studied. VIP concentrations of both blood and intestinal tissue were measured by specific radio-immunoassay in a rabbits' mechanical small intestinal obstruction model using fix of ileum to the right low abdominal wall, the influences of duodenal perfusion of DCQD on VIP levels were also investigated. 24 hours after ligating ileum, VIP of arterial plasma was elevated 7 fold, reaching 138.65 +/- 25.58 pmol/L, that of portal vein plasma was 4 times of the arterial value. VIP immunoactivity was detected in peritoneal fluid. VIP content of duodenal tissue in 16 intestine obstructed rabbits was 2 times high as that in 15 controls, whereas that of colonal tissue was inversed. DCQD caused a 50% decrease of elevated plasma VIP in experimental animals and a 65% increase in controls. The present work demonstrates that VIP might be released into the portal and peripheral circulation and mediate local and systemic pathophysiologic alterations accompanying small intestinal obstruction, such as hyperemia and edema of intestinal wall, accumulation of fluid in the lumen. VIP changes might account for the redistribution of blood flow in the obstructed segment of small intestine and the distal site of obstruction. DCQD has a therapeutic effect. The mechanism of dual modulate action of DCQD on VIP concentration is beyond our knowledge.

Neuroendocrinology of atrial natriuretic polypeptide in the brain

It has been demonstrated that atrial natriuretic polypeptide (ANP), or atriopeptin, is synthesized and stored not only in the cardiac atrial myocyte but also in the central nervous system, especially in the hypothalamus. ANP may play an important role in the regulation of fluid and electrolyte balance and blood pressure in the peripheral and central nervous systems. Some of the biological actions of ANP are opposite to those of angiotensin II and arginine vasopressin in the central nervous system. However, the mechanism of action of ANP remains, in a large part, to be defined.

Tryptophanyl-tRNA synthetase from Bacillus subtilis. Characterization and role of hydrophobicity in substrate recognition

The tryptophanyl-tRNA synthetase from Bacillus subtilis was purified to homogeneity and characterized. It has an alpha 2 subunit structure and a molecular weight of 77,000. Tryptophanyl-tRNA synthetase does not catalyze any significant proofreading. It activates tryptophan as well as the three fluorinated analogues, DL-4-fluoro-, DL-5-fluoro-, or DL-6-fluorotryptophan (4F-, 5F-, and 6F-Trp), in the ATP-pyrophosphate exchange reaction. In the aminoacylation reaction, the fluorotryptophans act as competitive inhibitors of Trp. Their relative activities follow the same order in both reactions: Trp greater than 4F-Trp greater than 6F-Trp greater than 5F-Trp. This order is the inverse of the order of relative hydrophobicities of these compounds, pointing to the importance of hydrophobic interactions in the selective recognition by tryptophanyl-tRNA synthetase among this group of substrates. To define the physical basis of the relative hydrophobicities, the crystallographic structure of 4F-Trp was determined and compared to that of trptophan. Charge distributions calculated for tryptophan and its different fluoroanalogues on the basis of molecular structures were supported by their carbon-13 NMR spectra. Correlations between charge distributions and relative hydrophobicities suggest that the polarity of the C-F bond represents an underlying factor determining the hydrophobicities of 4F-, 5F-, and 6F-Trp, thus relating tryptophanyl-tRNA synthetase selectivity toward tryptophan and its fluoroanalogues directly to their electronic configurations.