A Germinal Center Checkpoint of AIRE in B Cells Limits Antibody Diversification

In response to antigens, B cells undergo affinity maturation and class switching mediated by activation-induced cytidine deaminase (AID) in germinal centers (GCs) of secondary lymphoid organs, but uncontrolled AID activity can precipitate autoimmunity and cancer. The regulation of GC antibody diversification is of fundamental importance but not well understood. We found that autoimmune regulator (AIRE), the molecule essential for T cell tolerance, is expressed in GC B cells in a CD40-dependent manner, interacts with AID and negatively regulates antibody affinity maturation and class switching by inhibiting AID function. AIRE deficiency in B cells caused altered antibody repertoire, increased somatic hypermutations, elevated autoantibodies to T helper 17 effector cytokines and defective control of skin Candida albicans. These results define a GC B cell checkpoint of humoral immunity and illuminate new approaches of generating high-affinity neutralizing antibodies for immunotherapy.

Association of non-alcoholic fatty liver disease with total testosterone in non-overweight/obese men with type 2 diabetes mellitus

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is considered as both a vital risk factor and a consequence of type 2 diabetes mellitus (T2DM). Low total testosterone (TT) is common in men with T2DM, contributing to increased risks of metabolic diseases. This study aimed to investigate the association between TT levels and the prevalence of NAFLD in men with T2DM.

METHODS

In this cross-sectional study, 1005 men with T2DM were enrolled in National Metabolic Management Center (MMC) of First Affiliated Hospital of Wenzhou Medical University between January 2017 and August 2021. NAFLD was diagnosed using ultrasound as described by the Chinese Liver Disease Association. Overweight/obesity was defined as body mass index (BMI) ≥ 25 kg/m² according to WHO BMI classifications.

RESULTS

Individuals without NAFLD had higher serum TT levels than those with NAFLD. After adjustments for potential confounding factors, the top tertile was significantly associated with lower prevalence of NAFLD compared with the bottom tertile of TT level [odds ratio (OR) 0.303, 95% confidence interval (CI) 0.281-0.713; P < 0.001]. The association between TT with NAFLD in individuals with normal weight (OR 0.175, 95% CI 0.098-0.315; P < 0.001) was stronger than in individuals with overweight/obesity (OR 0.509, 95% CI 0.267-0.971; P = 0.040). There was a significant interaction of TT with overweight/obesity (P for interaction = 0.018 for NAFLD).

CONCLUSION

Higher serum TT was significantly associated with a lower prevalence of NAFLD in men with T2DM. We found that the relationship of TT and NAFLD was stronger in individuals with non-overweight/obesity.

[Expression and regulatory role of ultraconserved long non-coding RNA uc.77 in lung cancer]

Objective: To investigate the effect and molecular mechanism of ultra-conservative long non-coding RNA uc.77 in lung cancer. Methods: Lung cancer tissues and adjacent normal tissues were obtained from 61 patients with lung cancer who were diagnosed with lung cancer and underwent surgery from 2014 to 2016 in the General Hospital of the Southern Theater Command of the People's Liberation Army. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the uc.77 relative expressions in normal human bronchial epithelial cells 16HBE, lung cancer cell lines, and 61 pair lung cancer tissues. Uc.77 siRNA was transfected into lung cancer cells to interfere with the expression of uc.77, qRT-PCR was used to verify the interference effect, CCK8 method and clone formation experiment were used to detect cell proliferation ability, flow cytometry was used to detect apoptosis and cell cycle changes. H1299 cells transfected with uc.77 siRNA were injected into the subcutaneous right side of BALB/c nude mice to construct a tumor-bearing model for exploring the role of uc.77 on tumor growth. Western blot and qRT-PCR methods were used to detect the protein and mRNA expressions of p21. Results: The relative expression levels of uc.77 in lung cancer cell lines 95D, H1299, A549, H460, H446 and 16HBE-T were significantly higher than that of 16HBE cells (P<0.05). The uc.77 RNA expression levels of lung cancer tissues was significantly higher than that of the adjacent normal tissues (P<0.001). In addition, increased lncRNA uc.77 expression was significantly associated with big tumor size, lymph node metastasis and advanced TNM stage (P<0.05). After transfection with uc.77 siRNA, the expressions of uc.77 in H1299, 95-D and 16HBE-T cells were reduced (P<0.05), and the cell proliferation capacities were reduced at 48 hours and 72 hours (P<0.05). After transfection with uc.77 siRNA-1, the G(0)/G(1) phase cell ratio of H1299 siRNA-1 group [(71.86±3.46)%] was higher than those of H1299-control group [(47.62±5.48)%] and H1299 siRNA-NC group [(61.38±5.62)%, P<0.05], S phase cell ratio of H1299 siRNA-1 group [(14.99±3.61)%] was lower than those of H1299-control group [(34.95±7.05)%] and H1299 siRNA-NC group [(23.75±5.87)%, P<0.05], the apoptosis rate of H1299 siRNA-1 group [(4.90±1.80)%] was higher than those of H1299-control group [(3.30±0.80)%] and H1299 siRNA-NC group [(2.80±1.20)%, P<0.05], the colony formation rate of H1299 siRNA-1 group [(19.20±2.00)%] was lower than those of H1299 control group [(32.60±2.00)%] and H1299 siRNA-NC group [(34.40±1.00)%, P<0.05]. The results of the nude mice tumor formation experiment showed that the tumor volume of the H1299 siRNA-1 group was significantly lower than those of the H1299-control group and the H1299-negative control group (P<0.05), the average tumor weight of H1299 siRNA-1 group was significantly lower than those of H1299-control group and H1299-negative control group (P<0.05), tumor cell growth marker Ki-67 in the H1299 siRNA-1 group showed weak positive, and Ki-67 in the H1299-control group and H1299-negative control group showed positive. The result of qRT-PCR analysis showed that the mRNA expression level of p21 in H1299 siRNA-1 group (2.57±0.45) was higher than those in H1299 control group (1.00±0.00, P=0.001) and H1299 siRNA-NC group (1.52±0.37, P=0.009). The result of western blotting analysis also showed that the expression of p21 protein level in H1299 siRNA-1 group increased. Conclusions: The expression of ultraconserved long non-coding RNA uc.77 is elevated in lung cancer cell lines and lung cancer tissues. Silencing the expression of ultraconservative long noncoding RNA uc.77 can inhibit tumor growth, and blocking uc.77 expression may be a potential therapeutic target for lung cancer.

Predictions of arrhythmic, heart failure and mortality outcomes in pericarditis using automatic electrocardiogram analysis: a retrospective cohort study

Funding Acknowledgements

Type of funding sources: None.

Introduction

 Pericarditis is a relatively rare disease with a global burden. Despite its strong association with adverse cardiovascular outcomes, identification of patients at risk of future heart failure or arrhythmic events is difficult. In the following study, automated electrocardiogram (ECG) variables were used to predict new onset ventricular tachycardia/fibrillation (VT/VF), atrial fibrillation (AF) and heart failure with reduced ejection fraction (HF) in an Asian cohort of pericarditis patients.

Purpose

Assessing the use of automated ECG parameters to predict prognosis in pericarditis patients.

Methods

Consecutive patients admitted to a single tertiary center in China, for a diagnosis of pericarditis between 1st January 2005 and 31st December 2019, were included. Patients with existing AF or HF were excluded. The follow-up period was until the 31st December 2020, or death. Cox regression was applied to identify significant predictors of the incident VT/VF, AF or HFrEF.

Results

A total of 874 patients were included. The cohort was 57% male and had a median age of 59 (IQR: 50-70) years old. During follow-up, 57 patients (6.5%), 156 (17.8%) and 168 (19.2%) suffered from VT/VF, AF and HF, respectively. Cox regression identified baseline VT/VF, terminal angle of the QRS vector in the transverse plane, mean QRS duration and mean QTc intervals as significant predictors of incident VT/VF events, with only the foremost maintaining significance in multivariate analysis. In contrast, baseline age, prior diagnoses of hypertension, malignancy and atrial flutter, initial angle and magnitude of the QRS vector in the transverse plane, P-wave and QRS axis in the frontal plane, ST segment axis in the frontal and horizontal planes, mean PT interval, mean PR segment duration and QTc intervals were all univariate predictors of incident AF, albeit only baseline age and initial angle of the QRS vector in the transverse plane retained significance after multivariate adjustment. As it pertains to new-onset HFrEF, several clinical and electrocardiographic parameters demonstrated an association in univariate analysis, with history of hypertension, history of sudden cardiac death (SCD), initial QRS angle in transverse plane, initial 40ms QRS complex axis, ST-segment axis in the horizontal plane, T-wave frontal axis and atrial rate all showcasing significant relationships in multivariate analysis.

Conclusions

AF and HFrEF are relatively common complications, whilst VT/VF occurs less frequently in the context of pericarditis. Different clinical and ECG predictors of these outcomes were identified. Future studies are still needed to evaluate their use for risk stratification in the clinical setting.

Immunology of the Uterine and Vaginal Mucosae

Along with the maintenance of symbiotic mutualism with commensal microbes and protection against invasive infections common to all mucosal barrier tissues, female reproductive tissues have additional, unique tasks that include dynamic cyclic cellular turnover in menstruation and immunological tolerance to genetically foreign fetal antigens in pregnancy. Here we review current knowledge on distinct features of the immune cells in female reproductive tissue with regard to antimicrobial host defense and adaptations to accommodate the fetus during pregnancy. Outstanding areas for future research to obtain new functional insights on this enigmatic mucosal barrier are also highlighted.

Taxonomic and functional shifts in the beech rhizosphere microbiome across a natural soil toposequence

It has been rarely questioned as to whether the enrichment of specific bacterial taxa found in the rhizosphere of a given plant species changes with different soil types under field conditions and under similar climatic conditions. Understanding tree microbiome interactions is essential because, in contrast to annual plants, tree species require decades to grow and strongly depend on the nutritive resources of the soil. In this context, we tested using a natural toposequence the hypothesis that beech trees select specific taxa and functions in their rhizosphere based on the soil conditions and their nutritive requirements. Our 16S rRNA gene pyrosequencing analyses revealed that the soil type determines the taxa colonizing the beech rhizosphere. A rhizosphere effect was observed in each soil type, but a stronger effect was observed in the nutrient-poor soils. Although the communities varied significantly across the toposequence, we identified a core beech rhizosphere microbiome. Functionally, GeoChip analyses showed a functional redundancy across the toposequence, with genes related to nutrient cycling and to the bacterial immune system being significantly enriched in the rhizosphere. Altogether, the data suggest that, regardless of the soil conditions, trees enrich variable bacterial communities to maintain the functions necessary for their nutrition.

Role of carboxylic acid groups in the reduction of nitric oxide by carbon at low temperature, as exemplified by graphene oxide

Graphene oxide (GO) was utilized to investigate the role of carboxylic acid groups in the reduction of nitric oxide (NO) for the first time. As a result, GO with sufficient carboxylic acid groups reduced 45% of NO at 100 °C. However, GO without these oxygen-containing groups barely reduced NO (lower than 5%) under the same conditions. After reduction of NO, the carboxylic acid group content on GO decreased from 8.32 to 5.22 mmol g^-1. Simultaneously, the anhydride group content increased from 0.14 to 0.28 mmol g^-1. FTIR spectroscopy also indicated that the carboxylic acid groups transformed into anhydride and lactone groups. Moreover, both transient kinetics and TG-MS studies demonstrated that reactive intermediates formed during the reaction between NO and GO at 100 °C. Based on these results, it was proposed that the carboxylic acid groups participated in NO reduction by consumption and regeneration. This mechanism explains why carbon is usually an effective reductant and catalyst support for NO removal at low temperature.

[Effect of hydrogen peroxide on the lateral line hair cell regeneration of zebrafish]

Objective:To investigate effect of hydrogen peroxide (H₂O₂) in the lateral line hair cell growth and regeneration after damage on zebrafish. Method:Select 5 dpf zebrafish, each group of 10, randomly divided into A control group: the system of water culture. B H₂O₂ group: 10 μmol/L, 20 μmol/L H₂O₂ solution to replace three times a day. C neomycin group: treatment with system water after 1 h culture by 200 μmol/L neomycin. D neomycin + H₂O₂ group: 20 μmol/L H₂O₂ solution to replace three times a day after 200 μmol/L neomycin treatment for 1 h. E cisplatin group: treatment with system water after 3 h culture by 1 000 μmol/L cisplatin. F cisplatin + H₂O₂ group: 20 μmol/L H₂O₂ solution to replace three times a day after 1 000 μmol/L cisplatin treatment for 3 h. Each group in H₂O₂ treatment for 0 h, 24 h, 48 h was marked their hair cells by immunofluorescence method and count the P1, P7, P8 neuromasts under the fluorescence microscope. Repeat 3 times. Result:The number of hair cells on P1, P7, P8 three neuramasts among 5 to 7 dpf zebrafish were 9.364±0.901(n=11),9.645±0.598(n=15),9.922±0.862(n=13), no obvious difference (P>0.05); 10μmol/L, 20μmol/L H₂O₂ treated zebrafish for 48 h, the numbers were 11.540±0.741,11.905±0.607,compaired with the control group(10.841±0.389), P<0.05; neomycin+ H₂O₂ 48 h and neomycin 48 h respectively were 10.600±0.689,8.767±0.603, P<0.01; cisplatin+ H₂O₂ 48 h and cisplatin 48 h were 5.967±1.086,5.633±1.548, P>0.05. Conclusion:20 μmol/L H₂O₂ promotes the development of lateral line hair cells of zebrafish; H₂O₂ promotes the regeneration of the lateral line hair cells after injury of neomycin, but not cisplatin.

[The roles of serum free light chain ratio in the diagnosis and prognosis of newly diagnosed multiple myeloma]

目的

分析血清游离轻链（sFLC）κ/λ比率（sFLCR）在初诊多发性骨髓瘤（MM）患者诊断和预后中的作用。

方法

回顾性分析2012年9月至2015年7月收治的82例初诊MM患者的临床资料，采用血清蛋白电泳（SPE）和免疫固定电泳（IFE）法检测血清单克隆蛋白（M蛋白）的表达，采用免疫比浊法检测sFLCκ、λ的表达水平，分析初诊时sFLCR在MM患者诊断和预后中的作用。

结果

初诊时82例患者中SPE法检测M蛋白阳性率为85.5%，IFE法检测M蛋白阳性率为93.9%，sFLC异常以及sFLCR异常者占96.3%。初诊时高比率组（sFLCR≥100或≤0.01，42例）与低比率组（0.01 <sFLCR<100，40例）患者40个月的总生存率分别为87％和61%，差异有统计学意义（P=0.034）。与低比率组患者比较，高比率组患者初诊时血肌酐值、浆细胞数、β₂微球蛋白增高，血红蛋白降低，肾功能不全及需要透析者、DS分期Ⅲ期B组者、ISS分期Ⅲ期者、FISH检查异常者、λ轻链异常者较多，κ轻链异常者较少（P值均<0.05）。两组患者经过3~4个疗程诱导治疗后，高比率组和低比率组患者的治疗有效率（非常好的部分缓解及其以上）差异有统计学意义（45.2％对72.5%，P=0.012）。初诊肾功能不全者（肌酐≥178 µmol/L, 14例）与肾功能正常者（68例）的2年总生存率差异无统计学意义（85.7％对91.2%，P=0.894）。

结论

初诊时sFLC的检测相对于SPE和IFE法检测M蛋白对诊断MM有更高的敏感性；初诊时sFLCR明显异常的患者可能具有更高的肿瘤负荷和更强的侵袭性，可提示患者预后不良；初诊时伴有肾功能不全的MM患者经积极治疗后可获得与肾功能正常患者同样的疗效。

Differential impact of adenosine nucleotides released by osteocytes on breast cancer growth and bone metastasis

Extracellular ATP has been shown to either inhibit or promote cancer growth and migration; however, the mechanism underlying this discrepancy remained elusive. Here we demonstrate the divergent roles of ATP and adenosine released by bone osteocytes on breast cancers. We showed that conditioned media (CM) collected from osteocytes treated with alendronate (AD), a bisphosphonate drug, inhibited the migration of human breast cancer MDA-MB-231 cells. Removal of the extracellular ATP by apyrase in CM abolished this effect, suggesting the involvement of ATP. ATP exerted its inhibitory effect through the activation of purinergic P2X receptor signaling in breast cancer cells evidenced by the attenuation of the inhibition by an antagonist, oxidized ATP, as well as knocking down P2X7 with small interfering RNA (siRNA), and the inhibition of migration by an agonist, BzATP. Intriguingly, ATP had a biphasic effect on breast cancer cells-lower dosage inhibited but higher dosage promoted its migration. The stimulatory effect on migration was blocked by an adenosine receptor antagonist, MRS1754, ARL67156, an ecto-ATPase inhibitor, and A2A receptor siRNA, suggesting that in contrast to ATP, adenosine, a metabolic product of ATP, promoted migration of breast cancer cells. Consistently, non-hydrolyzable ATP, ATPγS, only inhibited but did not promote cancer cell migration. ATP also had a similar inhibitory effect on the Py8119 mouse mammary carcinoma cells; however, adenosine had no effect owing to the absence of the A2A receptor. Consistently, ATPγS inhibited, whereas adenosine promoted anchorage-independent growth of MDA-MB-231 cells. Our in vivo xenograft study showed a significant delay of tumor growth with the treatment of ATPγS. Moreover, the extent of bone metastasis in a mouse intratibial model was significantly reduced with the treatment of ATPγS. Together, our results suggest the distinct roles of ATP and adenosine released by osteocytes and the activation of corresponding receptors P2X7 and A2A signaling on breast cancer cell growth, migration and bone metastasis.

Abstract P3-13-06: Osteocytic Connexin 43 Hemichannels in Prevention of Bone Metastasis

Bone metastases are major, potentially fatal complications in patients with advanced cancers including breast, prostate and lung cancers. The gap junction-forming protein connexin 43 (Cx43) has been known to inhibit primary tumor cell growth. In addition to gap junctions, Cx43 also forms halves of gap junctions known as hemichannels which allow communication between the intracellular and extracellular environments. Cx43 hemichannels in osteocytes have been shown to open when induced by mechanical stimulation as well as by treatment with alendronate (AD), an efficacious and commonly used bisphosphonate drug. The opening of hemichannels is known to release small molecules important for bone formation and remodeling. To confirm the opening of Cx43 hemichannels in the presence of AD, we measured uptake of ethidium bromide (EtBr) in MLO-Y4 cells after the addition of AD. As expected, an increase in Cx43 hemichannels EtBr uptake was observed after AD treatment. To elucidate the effect(s) of osteocyte Cx43 hemichannels on cancer cell growth and migration, we treated MLO-Y4 osteocytes with AD. Conditioned media (CM) was collected after treatment and were used to incubate with metastatic MDA-MB-231 breast cancer cells and PC3 prostate cancer cells. Cell migration was measured using wound healing and transwell migration assays, and cell proliferation was measured using the soft agarose anchorage-independent growth assay. The CM collected from MLO-Y4 osteocytes treated with AD reduced cancer cell migration and proliferation in a dose-dependent manner. However, direct treatment with AD had no effect on the cell migration or proliferation of the MDA-MB-231 cells. These data validated that the decrease in migration and proliferation was not a result of direct action by AD on the cancer cells. In order to elucidate the direct functional involvement of Cx43 hemichannels in cell migration, we treated the MLO-Y4 cells with Cx43 (E2) antibody, a specific antibody which blocks hemichannel activity but not gap junction channels formed by Cx43. The inhibitory effect of the CM on the migration and proliferation of MDA-MB-231 and PC3 cells was diminished. Interestingly, the inhibitory effects of osteocytes on cancer cell migration were not observed when using osteoblasts. Together, these results suggest the functional importance of osteocytic Cx43 hemichannels in attenuating cancer cell migration and growth.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-13-06.

Effectiveness and safety of patient initiated single-dose versus continuous low-dose antibiotic prophylaxis for recurrent urinary tract infections in postmenopausal women: a randomized controlled study

This study evaluated patient-initiated single-dose antibiotic prophylaxis and continuous long-term low-dose daily antibiotic use for the prevention of recurrent urinary tract infections (UTI) in 68 postmenopausal women. The women were randomized to take a low-dose antibiotic each night (continuous group, n = 37) or a single-dose antibiotic each time they experienced conditions predisposing to UTI (intermittent group, n = 31). During the 12-month study, 1.4 and 1.9 UTIs/patient developed in the continuous and the intermittent groups, respectively, which was significantly lower than the incidence of UTIs in the previous 12 months in these patients (4.7 and 5.1 UTIs/patient, respectively). The incidence of gastro intestinal adverse events was significantly lower in the intermittent group compared with the continuous group (9.1% versus 30.0%). In conclusion, patient-initiated single-dose intermittent antibiotic prophylaxis was as effective as low-dose daily antibiotic prophylaxis in the treatment of recurrent UTIs in post menopausal women and was associated with fewer gastrointestinal adverse events.

[Epidemic situation analysis of Japanese encephalitis in 2005.]

BACKGROUND

To investigate the epidemic situation of Japanese encephalitis (JE) in three provinces, Guizhou, Sichuan, and Hubei in 2005.

METHODS

Information about epidemic situation of JE, mosquitoes specimens were collected and titers of JE virus in hosts in the above three surveillance sites were determined.

RESULTS

The reported cases of JE in Guizhou, Sichuan, and Hubei province accounted for 40.7% of total cases in 2005 in China. The numbers of cases in Guizhou and Sichuan ranked at the first two in China, morbidity exceeded 1/100,000, which was higher than average level in China. Zero to 10 years old children accounted for 90% in reported cases. Most of the cases were children lived at home. Almost all JE cases were presented from June to September, but most cases were reported between July and August. Investigaton of the density of vector showed that the dominant mosquitoes were Culex, especially the Culex tritaeniorhynchus.

CONCLUSION

The epidemic status of JE was similar among the three provinces and the whole country. The number of JEV cases in Guizhou and Sichuan were the highest in China.

Confidence intervals of similarity values determined for cloned SSU rRNA genes from environmental samples

The goal of this research was to investigate the influence of the error rate of sequence determination on the differentiation of cloned SSU rRNA gene sequences for assessment of community structure. SSU rRNA cloned sequences from groundwater samples that represent different bacterial divisions were sequenced multiple times with the same sequencing primer. From comparison of sequence alignments with unedited data, confidence intervals were obtained from both a 'double binomial' model of sequence comparison and by non-parametric methods. The results indicated that similarity values below 0.9946 are likely derived from dissimilar sequences at a confidence level of 0.95, and not sequencing errors. The results confirmed that screening by direct sequence determination could be reliably used to differentiate at the species level. However, given sequencing errors comparable to those seen in this study, sequences with similarities above 0.9946 should be treated as the same sequence if a 95% confidence is desired.

Laser desorption mass spectrometry for microbial DNA analysis

Recently, we demonstrated that a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS) can be used to determine the molecular weight of polymerase chain reaction (PCR) products of intact 16S rRNA regions and to profile their restriction digests. This is the first time that MALDI-TOF MS with ultraviolet (UV) photoionization has been used to analyze a PCR product of approximately 1600 nucleotides in length.

Interaction of 3,4-dienoyl-CoA thioesters with medium chain acyl-CoA dehydrogenase: stereochemistry of inactivation of a flavoenzyme

The medium chain acyl-CoA dehydrogenase is rapidly inhibited by racemic 3,4-dienoyl-CoA derivatives with a stoichiometry of two molecules of racemate per enzyme flavin. Synthesis of R- and S-3,4-decadienoyl-CoA shows that the R-enantiomer is a potent, stoichiometric, inhibitor of the enzyme. alpha-Proton abstraction yields an enolate to oxidized flavin charge-transfer intermediate prior to adduct formation. The crystal structure of the reduced, inactive enzyme shows a single covalent bond linking the C-4 carbon of the 2,4-dienoyl-CoA moiety and the N5 locus of reduced flavin. The kinetics of reversal of adduct formation by release of the conjugated 2,4-diene were evaluated as a function of both acyl chain length and truncation of the CoA moiety. The adduct is most stable with medium chain length allenic inhibitors. However, the adducts with R-3,4-decadienoyl-pantetheine and -N-acetylcysteamine are some 9- and >100-fold more kinetically stable than the full-length CoA thioester. Crystal structures of these reduced enzyme species, determined to 2.4 A, suggest that the placement of H-bonds to the inhibitor carbonyl oxygen and the positioning of the catalytic base are important determinants of adduct stability. The S-3,4-decadienoyl-CoA is not a significant inhibitor of the medium chain dehydrogenase and does not form a detectable flavin adduct. However, the S-isomer is rapidly isomerized to the trans-trans-2,4-conjugated diene. Protein modeling studies suggest that the S-enantiomer cannot approach close enough to the isoalloxazine ring to form a flavin adduct, but can be facilely reprotonated by the catalytic base. These studies show that truncation of CoA thioesters may allow the design of unexpectedly potent lipophilic inhibitors of fatty acid oxidation.

Corticosterone impairs cultured hippocampal neurons and facilitates Ca2+ influx through voltage-dependent Ca2+ channel

AIM

To investigate the effect of corticosterone (Cor) on the viability of cultured hippocampal neurons as well as voltage-dependent Ca2+ channel (VDCC) on the membrane of the hippocampal neurons.

METHODS

The primary cultured hippocampal neurons were prepared and the viability of hippocampal neurons was determined by MTT assays. Inward Ca2+ currents of VDCC on the membrane of the hippocampal neurons were measured with the whole-cell patch-clamp technique.

RESULTS

Treatment with Cor concentration-dependently reduced the survival of hippocampal neurons. The IC50 of Cor was 3.2 mumol.L-1. Neurons from cerebral cortex were affected only by high concentrations of Cor (10 mumol.L-1 and 0.1 mmol.L-1) with the IC50, 85 mumol.L-1, 20 times larger than the former. Whole-cell patch-clamp experiment showed that Cor (1 mumol.L(-1)-0.1 mmol.L-1) sprayed to the surface of the hippocampal neurons instantly facilitated Ca2+ influx through VDCC with the maximal elevation of 53%, 191%, and 84% above the baseline respectively and this effect was shown to be concentration-independent. In addition, changing the membrane potentials from -40 mV to -10 mV did not affect the facilitating effect of Cor on the Ca2+ influx, indicating that Cor-induced Ca2+ influx was membrane potential-independent.

CONCLUSION

Cor markedly facilitated Ca2+ influx into the hippocampal neurons, which may be one of the important mechanisms underlying the neurotoxicity of Cor to hippocampus.

Rapid extraction and high-performance liquid chromatographic determination of parthenolide in feverfew (Tanacetum parthenium)

A rapid and sensitive method for quantifying parthenolide in feverfew herb (Tanacetum parthenium) was developed that is significantly faster than those reported in the literature. The extraction system consisted of acetonitrile/water (90:10, v/v) in a bottle with stirring for 30 min. Both Soxhlet and bottle-stirring extractions were studied. Samples were analyzed using high-performance liquid chromatography with a Cosmosil C18-AR column (150 x 4.6 mm, 5 microm, 120 A). The mobile phase consisted of acetonitrile/water (55:45, v/v) with a flow rate of 1.5 mL/min and UV detection at 210 nm. Analysis time was 6 min, with a detection limit of 0.10 ng on column. The calibration curve was linear over a range of 0.160-850 microg/mL parthenolide with R(2) = 0.9999. Replicate tests indicated good reproducibility of the method with an RSD% = 0.88 (n = 10). Spike recovery of parthenolide was found to be 99.3% with an RSD% = 1.6 (n = 6).

Artificial pigs in space: using artificial intelligence and artificial life techniques to design animal housing

Computer simulations have been used by us since the early 1970s to gain an understanding of the spacing and movement patterns of confined animals. The work has progressed from the early stages, in which we used randomly positioned points, to current investigations of animats (computer-simulated animals), which show low levels of learning via artificial neural networks. We have determined that 1) pens of equal floor area but of different shape result in different spatial and movement patterns for randomly positioned and moving animats; 2) when group size increases under constant density, freedom of movement approaches an asymptote at approximately six animats; 3) matching the number of animats with the number of corners results in optimal freedom of movement for small groups of animats; and 4) perimeter positioning occurs in groups of animats that maximize their distance to first- and second-nearest neighbors. Recently, we developed animats that move, compete for social dominance, and are motivated to obtain resources (food, resting sites, etc.). We are currently developing an animat that learns its behavior from the spatial and movement data collected on live pigs. The animat model is then used to pretest pen designs, followed by new pig spatial data fed into the animat model, resulting in a new pen design to be tested, and the steps are repeated. We believe that methodologies from artificial-life and artificial intelligence can contribute to the understanding of basic animal behavior principles, as well as to the solving of problems in production agriculture in areas such as animal housing design.

Comparison of the exposure characteristics of soft-x-ray film SIOFM-5FW with Kodak 101-05 and Ilford Q-plates

In identical exposure and processing conditions, we compare the exposure characteristics of soft-x-ray film, SIOFM-5FW, with Kodak101-05 and Ilford Q-plates in the soft-x-ray and extreme UV region below 100 nm, using D-19 and Phenisol developers. The experimental results show that for radiation greater than 10 nm, the response of SIOFM-5FW lies between the Kodak101-05 and the Ilford Q-plates but is closer to the former. For radiation of less than 10 nm, the SIOFM-5FW is more sensitive than the Kodak101-05 plate, with a higher saturated optical density, a higher dynamic range, and an obvious carbon K absorption edge structure in the spectra obtained. The effects of the two developers used on the exposure characteristics are discussed.

Phospholipase activity in Cryptococcus neoformans: a new virulence factor?

Fifty isolates of Cryptococcus neoformans were examined for extracellular phospholipase production after inoculation onto egg yolk agar; 49 produced a pericolonial precipitate indicative of phospholipase activity. Phospholipase B (PLB), lysophospholipase, and lysophospholipase-transacylase activities were identified by radiometric analysis in supernatants from 4 clinical isolates. The ratio of colony diameter to colony plus precipitate on agar (Pz) correlated with PLB activity. Phospholipase production was similar in 12 environmental and 13 clinical isolates of C. neoformans var. gattii. Environmental strains of C. neoformans var. neoformans (n = 8) produced more phospholipase at 72 h than did 17 clinical isolates (mean Pz, 0.57 vs. 0.72; P < .01); however, Pz values were similar at 96 h. Quantitation of cryptococci in the lungs and brains of BALB/c mice inoculated intravenously with 4 strains expressing high, intermediate, or low phospholipase activity revealed a correlation between phospholipase activity and virulence. Phospholipases secreted by C. neoformans may be implicated in virulence.

Succession and convergence of biofilm communities in fixed-film reactors treating aromatic hydrocarbons in groundwater

Community composition, succession, and performance were compared in three fluidized bed reactors (FBR) operated to test preemptive colonization and the influence of toluene compared with a mixture of benzene, toluene, and p-xylene (BTX) as feeds. One reactor was inoculated with toluene-degrading strains Pseudomonas putida PaW1, Burkholderia cepacia G4, and B. pickettii PKO1. PaW1 outcompeted the other two strains. When groundwater strains were allowed to challenge the steady-state biofilm developed by inoculated strains, they readily displaced the inoculated strains and further reduced the toluene effluent concentration from 0.140 to 0.063 mg/liter for 98% removal. Amplified ribosomal DNA restriction analysis (ARDRA) of reactor community DNA showed a succession of populations to a pattern that was stable for at least 4 months of operation. Parallel reactors fed toluene and BTX but inoculated directly from groundwater had the same treatment performance and the same ARDRA profiles as each other and as the seeded reactor once the groundwater community took over. Convergence and stability of populations were confirmed by genotype analysis of 120 isolates taken from all reactors and at several times. Ninety percent of the isolates were of 4 of the 12 genotypes found, and their ARDRA patterns accounted for most of the community ARDRA patterns. Estimates of the maximum specific growth rates (mu max), half-saturation constants (K(m)), and maximum substrate utilization rates (Vmax) of the 12 genotypes isolated revealed a rather high diversity of toluene use kinetics even though the toluene in the feed was constant. The climax populations, however, generally showed kinetic parameters indicative of greater competitiveness than the inocula. rRNA sequence analysis of three codominant strains showed them to be members of the alpha, beta, and gamma subdivisions of the Proteobacteria. Two were similar to Comamonas and Pseudomonas putida, but the member of the alpha group was somewhat distant from any organism in the rRNA database. The convergence of communities to the same composition from three different starting conditions and their constancy over several months suggests that a rather stable community was selected.

Slopes of distortion-product otoacoustic emission growth curves corrected for noise-floor levels

Distortion-product otoacoustic emission (DPE) input/output (I/O) curves were measured at 2f1-f2 frequencies with spectral-averaging and time-averaging procedures from ten normal-hearing ears. Stimuli were equal-level f1 and f2 primary tones with f2/f1 ratios of 1.2 and f2 frequencies at 1200, 2400, and 4800 Hz. Time-averaging procedures lowered noise-floor (NF) levels, compared to spectral averaging, so DPEs could be elicited by stimuli as low as 18 dB SPL in some ears. DPEs were corrected for power summation with NF levels and the resulting DPE I/O curves were fit with sixth-order polynomials. Slopes of fitted I/O curves were specified by the first derivative as a function of the level of the primary tones. Slopes of uncorrected spectrally averaged DPE I/O curves were strongly influenced by the NF level. Slopes of NF-corrected spectrally averaged DPE I/O curves were more representative of the true slope, specified as the slope of the corresponding time-averaged DPE I/O curve well above its NF. True DPE I/O slopes decreased with level from a mean slope near 1.0 dB/dB at 30 dB SPL and below for all three f2 frequencies. Nonmonotonicities in I/O curves were not seen at very low stimulus levels. At moderate stimulus levels and above, nonmonotonicities in individual DPE I/O curves reduced the slopes of individual I/O curves and reduced the average slopea cross ears.

Gene transfer from a bacterium injected into an aquifer to an indigenous bacterium

Two novel 3-chlorobenzoate-degrading bacteria were previously isolated from an aquifer in which no such bacteria could be enriched prior to the introduction of the 3-chlorobenzoate-degrading strain, Pseudomonas sp. B13. To understand the origin of 3-chlorobenzoate-degrading genes in the two novel isolates, the 16S ribosomal RNA, clcD (dienelactone hydrolase) and clcA (chlorocatechol oxygenase) genes from these bacteria were amplified and sequenced. The partial 16S rRNA gene sequences and REP-PCR patterns showed that these two novel isolates were identical but differed from strain B13. Phylogenetic analyses revealed that the novel isolates were closely related to Alcaligenes eutrophus in the beta subclass of the Proteobacteria, whereas strain B13 was related to Pseudomonas aeruginosa and P. mendocina in the gamma subclass of the Proteobacteria. In contrast, the clcD and clcA gene sequences were identical on strain B13 and these two isolates, indicating that the 3-chlorobenzoate-degrading genes were transferred from strain B13 to these isolates. What cannot be established is when this transfer occurred.

Genotoxicity of heated cooking oil vapors

Epidemiological studies of lung cancer in Chinese women indicated that factors other than cigarette smoking are related to lung cancer risk. A case-control study suggested that indoor air pollution, particularly from cooking oil emissions, may be involved. Condensates of volatile emissions from rapeseed and soybean cooking oils were prepared and found to be genotoxic in short-term tests including the Salmonella mutation assay, SV50 forward-mutation assay, and sister-chromatid exchange assay, as well as the micronucleus assay in mouse bone marrow. In contrast, condensates from rapeseed oil with butylated hydroxyanisole or hydrogenated rapeseed oil were not mutagenic, implicating oxidation products as the cause for mutagenicity. Peanut oil and lard condensates were not mutagenic in any assay. The association of exposure to Chinese rapeseed cooking-oil emissions and lung-cancer risk may be related to the mutagenic component of these condensates.

Stigmatic grazing-incidence flat-field grating spectrograph

A stigmatic grazing-incidence flat-field grating spectrograph was developed. The spectrograph consisted of a variable line-spacing concave grating and a grazing-incidence collecting optics composed of a cylindrical mirror and a spherical mirror. Using this spectrograph, we have obtained soft x-ray spectra of line-focused laser plasmas with good spatial resolution along the normal of the target surface over the entire wavelength range covered by the spectrograph.

[Clinical and experimental studies of yiqi huoxue principles in treating ulcerative colitis]

Yiqi Huoxue principle (YH) was applied to treat 30 cases of ulcerative colitis while Yiqi Jianpi ( ) and Qingre Qushi ( ) principle (YJQQ), which had been proved its therapeutic effect, was used as the control therapy. The herbal medicines were taken by oral and enema. The course of treatment was 6 weeks. The length, wet and dry weights of thrombus, the platelet adherence and the r, k, Ma, M values of thrombelastogram were measured before and after medications. Before medication, the value mentioned above were all abnormal in both YH and YJQQ group. After medication, with alleviation of the symptoms and signs of the colitis, all these values trend gradually to normal levels (P less than 0.01). The rat models of ulcerative colitis were made by immunological and local stimulation methods. The models were divided into three groups: YH(I), YJQQ(II) and water group(III). Three weeks after medication, the results showed that the lesion degree of the colon, the length and weight both wet and dry thrombus were remarkably lower in group I than those in group III. It was also showed that there was a positive correlation between the lesion degree of colon and the dry weight of thrombus (r = 0.7941, P less than 0.01). It suggested that the therapeutic effects of YH was similar to those of YJQQ in treating ulcerative colitis.

Inactivation of two-electron reduced medium chain acyl-CoA dehydrogenase by 2-octynoyl-CoA

The acetylenic thioester, 2-octynoyl-CoA, inactivates medium chain acyl-CoA dehydrogenase from pig kidney by two distinct pathways depending on the redox state of the FAD prosthetic group. Inactivation of the oxidized dehydrogenase occurs with labeling of an active site glutamate residue and elimination of CoASH. Incubation of the reduced dehydrogenase with 2-octynoyl-CoA rapidly forms a kinetically stable dihydroflavin species which is resistant to reoxidation using trans-2-octenoyl-CoA, molecular oxygen, or electron transferring flavoprotein. The reduced enzyme derivative shows extensive bleaching at 446 nm with shoulders at 320 and 380 nm. Denaturation of the reduced derivative in 80% methanol yields a mixture of products which was characterized by HPLC, by uv/vis, and by radiolabeling experiments. Approximately 20% of the flavin is recovered as oxidized FAD, about 40% is retained covalently attached to the protein, and the remainder is distributed between several species eluting after FAD on reverse-phase HPLC. The spectrum of one of these species ressembles that of a N(5)-C(4a) dihydroflavin adduct. These data suggest that a primary reduced flavin species undergoes various rearrangements during release from the protein. The possibility that the inactive modified enzyme represents a covalent adduct between 2-octynoyl-CoA and reduced flavin is discussed. Analogous experiments using enzyme substituted with 1,5-dihydro-5-deaza-FAD show rapid and quantitative reoxidation of the flavin by 0.5 eq of 2-octynoyl-CoA.