[Screening for asymptomatic atrial fibrillation in elder community populations in Dalian: a single center study].

Objective: We aimed to determine the epidemiological characteristics of asymptomatic AF in elder community population (≥65 years old) to analyze the detection rate of different screening methods. Methods: The study was a prospective cohort study. The elder (≥65 years old) residents who voluntarily participated in free physical examination in Dalian community were selected. The participants were randomly divided into screening group (including intensive screening group and single screening group) and control group. The control group received interrogation, medical history collection and routine 12-lead electrocardiogram (ECG) examination. Screening group received an additional single-lead ambulatory ECG equipment worn for 5-7 days. Intensive screening group received two equal-length wearings in 2020 and 2021 respectively, while one screening group only wore once in 2020. Results: Finally 3 340 residents ((70.7±5.0) years old) which consisted of 1 488 males (44.55%) were enrolled. There were 1 945 residents in screening group, including 859 in intensive screening group and 1 086 in one-time screening group. The control group included 1 395 people. Detection rate of asymptomatic AF was significantly higher in screening group than control group (79(4.06%) vs. 24(1.72%), P<0.001). Higher detection rate was found in screening group than control group in AF risk factors (1 or 2-3) subgroups and CHA2DS2-VASc score (2-3 or≥4) subgroups (P<0.05). Additionally, no difference was found between intensive screening group and single screening group (42(4.89%) vs. 37(3.41%), P=0.100). Intensive screening increased detection rate (7(6.93%) vs. 1(0.58%), P=0.009) only in residents those with low thrombosis risk (CHA2DS2-VaSc<2). Conclusions: Screening in elderly (≥65 years old) can significantly improve the detection rate of asymptomatic AF by wearing single lead dynamic ECG device. The rate increased significantly with the increase of risk factors associated with AF by single screening. In addition, repeat screening of the same method may only improve detection rates in the group with low risk thrombotic scores and non-combination of AF risk factors.Screening methods that are appropriate for different populations may require further exploration.

Effect of Body Weight and Obesity on Esophageal Function.

The incidence of obesity in the population is gradually increasing. Obesity can cause a variety of complications in the digestive system such as gastroesophageal reflux disease, and impacts the integrity of the esophageal mucosal barrier and esophageal motility. However, not many studies have focused on the effect of varying degrees of obesity on the esophagus. A total of 611 participants were included in this study. We divided them into three groups according to their body mass index (BMI): the normal weight group, the overweight group, and the obesity group. We performed a retrospective comparison between groups based on indicators from high resolution esophageal manometry (HREM) and 24-hour pH impedance monitoring, and did a correlation analysis on multiple indicators such as esophageal mucosal barrier, esophageal motility, and acid reflux. The mean nocturnal baseline impedance (MNBI) in the overweight and obesity groups was lower than that in the normal group. The MNBI of the subjects in Z5-Z6 channels in the overweight group was significantly lower than that in the normal group. With respect to Z3-Z6 channels, MNBI values in the obesity group were significantly lower than those in the normal group. 'The acid exposure time (AET), the DeMeester scores (DMS) and 24-hour total reflux episodes was significantly higher in the obesity group than those in the normal and overweight groups. The upper esophageal sphincter (UES) residual pressure, and intrabolus pressure (IBP) in the overweight and obesity groups were significantly higher than those in the normal group. In addition, lower esophageal sphincter (LES) resting pressure, and esophagogastric junction contractile integral (EGJ-CI) in the obesity group were significantly higher than those in the normal group. We found that increase in body weight affected the integrity of esophageal mucosa, and different degrees of increase associated with different degrees and different aspects of changes in esophageal motility.

[Expression of METTL14 in epithelial ovarian cancer and the effect on cell proliferation, invasion and migration of A2780 and SKOV3 cells].

Objective: To study the expression of methyltransferase-like protein 14 (METTL14) in epithelial ovarian cancer and its clinical significance, and to explore the effect of METTL14 expression on the proliferation, invasion and migration of ovarian cancer cells. Methods: Immunohistochemistry (IHC) was used to detect METTL14 expression in tumor tissue samples, and analyze the relationships among METTL14 expression, clinicopathological factors, and prognosis in ovarian cancer. Lentiviral vectors and small interfering RNA (siRNA) were used to up-regulate and down-regulate the METTL14 expression in ovarian cancer cell lines A2780 and SKOV3, respectively. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to detect the N6-methyladenosine (m6A) content in ovarian cancer cells. Cell counting kit-8 (CCK-8), wound healing assay, and transwell assay were used to examine the function of METTL14 expression in the cells. Results: (1) The IHC score of METTL14 protein was 6.2±3.7 in 20 samples of ovarian cancer tissues and 3.3±2.5 in 15 samples of normal ovarian tissues, and the difference was statistically significant (t=-2.64, P=0.012). Among the patients who suffered from ovarian cancer, there were 69 cases with high expression of METTL14 protein (IHC score≥6), accounting for 57.0% (69/121), and the cases with low expression of METTL14 protein (IHC score<6) accounting for 43.0% (52/121). Compared with the patients with low expression of METTL14, the patients with high expression of METTL14 had later stages, higher rates of lymph node metastasis, abdominal metastasis, and more ascite amount. The differences were statistically significant (all P<0.05). The overall survival rate was significantly lower in patients with high METTL14 expression than the low expression (P=0.009). (2) LC-MS/MS data showed that the relative expression of m6A in A2780 and SKOV3 cells in the lentivirus (LV)-METTL14 group were 0.213±0.024 and 0.181±0.018, which were significantly higher than those in the LV-normal control (NC) group (0.109±0.022 and 0.128±0.020; all P<0.05). While the relative expression of m6A in A2780 and SKOV3 cells in the si-METTL14 group were 0.063±0.012 and 0.069±0.015, which were significantly lower than the expression in si-NC group of 0.108±0.014 and 0.121±0.014 (all P<0.05). CCK-8 assay showed that the absorbance values were significantly lower in the si-METTL14 group compared with the si-NC group at 36, 48, 60 hours (all P<0.05); while were significantly increased in the LV-METTL14 group compared with the LV-NC group at 48, 60 hours (all P<0.01). Scratch wound assays showed that the migration rate of the si-METTL14 group was lower than those of the si-NC group, while the LV-METTL14 group were higher than the LV-NC group by 24 hours, the differences were statistically significant (all P<0.01). Cell migration and invasion were detected by transwell migration and invasion assays. After cultivated for 24 hours, the invasion cell number and the migration cell number in the si-METTL14 group were less than those in the si-NC group. While the invasion cell number and the migration cell number in the LV-METTL14 group were more than those in the LV-NC group, respectively. The differences were statistically significant (all P<0.01). Conclusion: Patients with high METTL14 expression have a worse prognosis in ovarian cancer, which may increase the m6A modification of ovarian cancer cells and promote cells proliferation, invasion and migration.

[Feasibility of radiofrequency ablation for cancer patients with atrial fibrillation].

Objective: To analyze the impact of cancer on the recurrence rate of atrial fibrillation (AF) after AF radiofrequency ablation and further evaluate the feasibility of radiofrequency ablation therapy in cancer patients with AF. Methods: This study was a single-center, retrospective study. Cancer patients with AF undergoing radiofrequency ablation for the first time in the First Affiliated Hospital of Dalian Medical University from May 30, 2008 to September 30, 2018 were included (cancer group). AF patients without cancer undergoing radiofrequency ablation for the first time during the same period served as non-cancer group. Clinical data including age, gender, past history, cancer and AF-related parameters, etc. were analyzed. Patients were followed up after radiofrequency ablation. The primary endpoints were AF recurrence or all-cause death. Kaplan-Meier survival analysis was used to analyze the effect of cancers on the recurrence after AF ablation. The multivariate cox regression analysis was further applied to correct for other confounding factors to analyze whether the impact of cancers on the recurrence of atrial fibrillation was statistically significant. Results: A total of 90 patients were enrolled, there were 30 patients in the cancer group (mean age (64.8±6.6) years, 16 (53.3%) males) and 60 patients in the non-cancer group (mean age (63.6±6.2) years, 32 (53.3%) males). Clinical data, such as age, gender, and cancer treatment, were similar between the two groups. During an average follow-up period of (328.7±110.2) days, there were 6 AF recurrences (recurrence rate 20.0%) in the cancer group, and 17 AF recurrences (recurrence rate 28.3%) in the control group. AF recurrence rate was similar between the two groups (P>0.05). During the follow-up period, there was no all-cause death in the two groups. Kaplan-Meier survival analysis showed that cancer was not related to AF recurrence after radiofrequency ablation (P = 0.383). After adjusting for other confounding factors, the multivariate Cox regression analysis showed that cancer was not an independent predictor of AF recurrence after radiofrequency ablation (HR=0.508, 95%CI: 0.192-1.342, P = 0.172). Conclusions: The combination of cancer has no impact on the recurrence of AF after radiofrequency ablation. For cancer patients with AF, radiofrequency ablation therapy can be considered as a feasible heart rhythm control treatment strategy.

[A case report of BCL11B mutation induced neurodevelopmental disorder and literature review].

Objective: To analyze the clinical , immunological and genetic features of a child with BCL11B mutation induced neurodevelopmental disorder. Methods: The clinical data and genetic test of a child with BCL11B mutation hospitalized in the Department of Rheumatology and Immunology in Children's Hospital of Chongqing Medical University in December 2018 were extracted and analyzed. The literature was searched with "BCL11B mutation" and "immunodeficiency 49" as key words in Chinese databases and Pubmed until January 2019 was reviewed. Results: A male patient aged 3 years and 11 months with facial dysmorphisms and delayed language and motor development was admitted due to neurodevelopmental retardation over two years. Laboratory tests showed normal human immunoglobulin (IgG 12.90 g/L, IgA 1.02 g/L, IgM 1.15 g/L, IgE 532 000 U/L), Trec (228) and proliferation of T and B cells. The lymphocyte subsets revealeda reduced percentage of B cells (0.108) but normal absolute numbers (0.574×10(-3)/L), and an increased percentage (0.828) as well as absolute numbers (4.415×10(-3)/L) of T cells. A heterozygous BCL11B mutation was detected by sanger sequencing, showing a de novo frameshift mutation c.1887_c.1893delCGGCGGG in exon 4. Two papers were found which were all in English, with total of 14 patients(13 patients with complete information). Thirteen mutations were reposed, including 7 frameshift, 2 nonsense, 2 missense, and 2 chromosomal rearrangements; Thirteen patients had heterozygous mutations. All patients had delayed language and motor development and facial dysplasia which were mainly hypertelorism, thin eyebrows and small palpebral fissures. Some patients had dental anomalies, ametropia and allergy, and a few were combined with immune impairment, but without overt signs of immunodeficiency. Only one patient had multisystem anomalies and profound immune deficiency. Conclusions: BCL11B is essential for development of the nervous and the immune system. In this study, the de novo mutation of BCL11B gene resulted in neurodevelopmental and immunological disorders.

Association of interleukin 22 gene polymorphisms and serum IL-22 level with risk of systemic lupus erythematosus in a Chinese population.

The aim of this study was to investigate the association between the single-nucleotide polymorphisms (SNPs) of the interleukin 22 (IL-22) gene and systemic lupus erythematosus (SLE) in a Chinese population. Three IL-22 SNPs (rs2227485, rs2227513 and rs2227491) were genotyped using SNaPshot SNP genotyping assays and identified by sequencing in 314 SLE patients and 411 healthy controls. The IL-22 level of serum was assessed by enzyme-linked immunosorbent assay (ELISA) kits. Data were analysed by spss version 17.0 software. We found that rs2227513 was associated with an increased risk of SLE [AG versus AA: adjusted odds ratio (aOR) = 2·24, 95% confidence interval (CI) = 1·22-4·12, P = 0·010; G versus· A: adjusted OR = 2·18, 95% CI = 1·20-3·97, P = 0·011]. Further analysis in patients with SLE showed that the AG genotype and G allele were associated with an increased risk of renal disorder in SLE (G versus A: aOR = 3·09, 95% CI = 1·30-7·33, P = 0·011; AG versus· AA: aOR = 3·25, 95% CI = 1·35-7·85, P = 0·009). In addition, the concentration of IL-22 was significantly lower in the rs2227513 AG genotype compared with AA genotype (P = 0·028). These results suggest that rs2227513 polymorphism might contribute to SLE susceptibility, probably by decreasing the expression of IL-22.

Correlation of acetabular chondrocyte apoptosis with caspase-3 and Bcl-2 expression in developmental dislocations of the hip.

This study aimed to determine whether abnormal apoptosis is present in acetabular cartilage in early developmental dislocations of the hip (DDH), and if so, whether it is correlated with the expression of caspase-3 and Bcl-2. DDH was induced in 24 4-week-old New Zealand white rabbits. Acetabular cartilage specimens from the experimental and control groups were stained with hematoxylin and eosin (H&E). Animals from the experimental group developed acetabular dysplasia. Apoptotic chondrocytes were observed by ultrastructural electron microscopy and H&E. TUNEL assays revealed significantly greater acetabular chondrocyte apoptosis in the treated samples as compared to the control. Significantly higher caspase-3 expression and lower Bcl-2 expression were also measured in the DDH group compared with the control. We conclude that excessive apoptosis does occur in acetabular cartilage with DDH, and is positively correlated with high caspase-3 expression as well as low Bcl-2 expression.

Altered mean platelet volume in patients with polymyositis and its association with disease severity.

Polymyositis (PM) is an autoimmune disease characterized by chronic inflammation in skeletal muscle. Mean platelet volume (MPV), a marker in the assessment of systemic inflammation, is easily measured by automatic blood count equipment. However, to our knowledge, there are no data in the literature with respect to MPV levels in PM patients. Therefore, in this study we aimed to investigate MPV levels in patients with PM. This study included 92 newly diagnosed PM patients and 100 healthy individuals. MPV levels were found to be significantly lower compared with healthy controls (10.3±1.23 vs 11.5±0.74 fL, P<0.001). Interestingly, MPV was found to be positively correlated with manual muscle test (MMT) score and negatively correlated with erythrocyte sedimentation rate (ESR) in patients with PM (r=0.239, P=0.022; r=-0.268, P=0.010, respectively). In addition, MPV was significantly lower in active PM patients compared with inactive PM patients (9.9±1.39 vs 10.6±0.92 fL, P=0.010). MPV was independently associated with PM in multivariate regression analyses, when controlling for hemoglobin and ESR (OR=0.312, P=0.031, 95%CI=0.108 to 0.899). The ROC curve analysis for MPV in estimating PM patients resulted in an area under the curve of 0.800, with sensitivity of 75.0% and specificity of 67.4%. Our results suggest that MPV is inversely correlated with disease activity in patients with PM. MPV might be a useful tool for rapid assessment of disease severity in PM patients.

A potential clinical usefulness of measuring serum bilirubin levels in patients with polymyositis.

OBJECTIVE: Accumulated data have indicated that bilirubin has antiinflammatory, antioxidative, and immunosuppressive properties. Polymyositis (PM) belongs to an autoimmune disease characterized by chronic inflammation in skeletal muscle. Until now, to the best of our knowledge, there are no literature investigating bilirubin levels in patients with PM. Therefore, the aim of this investigation was to assess a relationship between bilirubin and PM. PATIENTS AND METHODS: Our study included newly diagnosed 77 patients with PM who were admitted to the Affiliated Hospital of Youjiang Medical University for Nationalities (Guangxi, China) and 108 healthy subjects as controls. Clinical characteristics and laboratory parameters of patients were analyzed, retrospectively. RESULTS: The serum concentrations of total bilirubin (TB), conjugate bilirubin (CB), unconjugated bilirubin (UCB) were significantly lower in patients with PM than healthy controls. Serum concentrations of TB were negatively correlated with erythrocyte sedimentation rate (ESR), creatine kinase (CK) and lactic dehydrogenase (LDH) in patients with PM (r=-0.494, p<0.001; r=-0.274, p=0.017; r=-0.282, p=0.014), and serum concentrations of UCB were negatively correlated with ESR and CK in PM patients (r=-0.424, p<0.001; r=-0.234, p=0.041). Both serum TB and UBC concentrations were positively correlated with manual muscle test (MMT) score in patients with PM (r=0.328, p=0.004; r=0.333, p=0.004). In multiple linear regression analysis, serum UBC levels were independently associated with MMT score (r=0.239, p=0.003). CONCLUSIONS: We observed significantly lower serum concentrations of TB, CB and UCB in patients with PM, and suggested a potential association between serum concentrations of UBC and disease activity in PM patients.

[Association of RTN4 gene rs2864052 and rs6545468 with the susceptibility of nasopharyngeal carcinoma in Guangxi Zhuang population].

Objective:To study the relationship of the polymorphism of RTN4 gene rs2864052 and rs6545468 and haplotype with the susceptibility of nasopharyngeal carcinoma in Guangxi Zhuang population. Method:The polymorphism of Nogo gene (rs2864052,rs6545468) and haplotype were analyzed using the method of single-base extension PCR and DNA sequencing in 282 cases of nasopharyngeal carcinoma (NPC) and 199 healthy persons (control group) in Guangxi Zhuang Autonomous Region. Result:There were no differences between the NPC's patients and controls in the genotype and allele frequencies of RTN4 gene rs2864052 site,or rs6545468 site. The frequency of AG haplotype in the NPC's patients was significantly lower than in the controls(P=0.004, OR=0.14,95%CI=0.31-0.68). Conclusion:The haplotype AG of RTN4 gene rs2864052 and rs6545468 sites may reduce the risk of nasopharyngeal carcinoma in Guangxi Zhuang population.

Altered mean platelet volume in patients with polymyositis and its association with disease severity

Polymyositis (PM) is an autoimmune disease characterized by chronic inflammation in skeletal muscle. Mean platelet volume (MPV), a marker in the assessment of systemic inflammation, is easily measured by automatic blood count equipment. However, to our knowledge, there are no data in the literature with respect to MPV levels in PM patients. Therefore, in this study we aimed to investigate MPV levels in patients with PM. This study included 92 newly diagnosed PM patients and 100 healthy individuals. MPV levels were found to be significantly lower compared with healthy controls (10.3±1.23 vs 11.5±0.74 fL, P<0.001). Interestingly, MPV was found to be positively correlated with manual muscle test (MMT) score and negatively correlated with erythrocyte sedimentation rate (ESR) in patients with PM (r=0.239, P=0.022; r=−0.268, P=0.010, respectively). In addition, MPV was significantly lower in active PM patients compared with inactive PM patients (9.9±1.39 vs 10.6±0.92 fL, P=0.010). MPV was independently associated with PM in multivariate regression analyses, when controlling for hemoglobin and ESR (OR=0.312, P=0.031, 95%CI=0.108 to 0.899). The ROC curve analysis for MPV in estimating PM patients resulted in an area under the curve of 0.800, with sensitivity of 75.0% and specificity of 67.4%. Our results suggest that MPV is inversely correlated with disease activity in patients with PM. MPV might be a useful tool for rapid assessment of disease severity in PM patients.

Ischemia-reperfusion injury in an aortic dissection patient.

Aortic dissection is a life-threatening emergency. Well-established risk factors include systemic hypertension, hereditary connective tissue diseases (Marfan syndrome and Ehlers-Danlos syndrome), coarctation of the aorta, bicuspid aortic valve, aortitis, and arch hypoplasia. Ischemia of the viscera, the kidneys, the spinal cord, or the lower extremities due to malperfusion constitutes life-threatening complications that have to be considered in the treatment strategy.We report a rare case of symptomatic ischemia of the lower extremities due to aortic dissection. This case demonstrates that the treating physician needs to be vigilant for ischemia reperfusion injuries such as osteofascial compartment syndrome and acute renal failure in aortic dissection.

Decoupling free-carriers contributions from oxygen-vacancy and cation-substitution in extrinsic conducting oxides.

The intrinsic oxygen-vacancies and the extrinsic dopants are two major fundamental free-carrier sources for the extrinsic conducting oxides, such as Sn-doped In(2)O(3). Yet, the individual contributions of the above two free-carrier sources to the total carrier concentrations have never been unraveled. A carrier-concentration separation model is derived in this work, which can define the individual contributions to the total carrier concentration from the intrinsic oxygen-vacancies and the extrinsic dopants, separately. The individual contributions obtained from the present carrier-concentration separation model are verified by the two-state trapping model, photoluminescence, and positron annihilation lifetime (PAL) spectroscopy. In addition, the oxygen-vacancy formation energy of the Sn:In(2)O(3) thin film is determined to be 0.25 eV by PAL spectroscopy.

Fate of nonylphenol polyethoxylates and their metabolites in four Beijing wastewater treatment plants.

Four Beijing wastewater treatment plants (WWTPs) were selected to investigate behaviours of nonylphenol polyethoxylates and their metabolites in different wastewater treatment processes. The results showed that the total concentrations of nonylphenolic compounds in the influents of the four WWTPs ranged from 0.115 to 0.347 mumol/L, as well as their removal efficiencies ranging from 75.7% to 90.8%. Both influent concentrations and removal efficiencies of nonylphenol polyethoxylates were correlated to seasons as follows: higher in the summer than in the winter, and influent concentrations were lower during the rain weather. The analysis revealed that 21.8-47.6% of nonylphenol polyethoxylates and their metabolites entering WWTPs were released via effluents and excess sludge, leaving a great part of them for biodegradation. Nonylphenol and short-chain nonylphenol polyethoxylates were disposed to the environment mainly via sewage sludge, while carboxylated nonylphenol polyethoxylates were the most abundant group of nonylphenol polyethoxylates in effluents.

Genetic variation in transforming growth factor-beta1 gene associated with increased risk of esophageal squamous cell carcinoma.

The genetic alterations leading to esophageal squamous cell carcinoma (ESCC) are gradually being discovered. A wide variety of genes have been associated with ESCC development as well as tumor progression. Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine; it promotes tumor growth and metastasis in later stages of of cancer development. Variations in the DNA sequence in the TGF-beta1 gene may lead to altered TGF-beta1 production and/or activity, and so this can modulate an individual's susceptibility to ESCC. To test this hypothesis, we investigated the association of the TGF-beta1 gene -509 C/T and 869 T/C (Leu10Pro) polymorphisms and their haplotypes with the risk of ESCC. 247 patients with ESCC and 260 age- and sex-matched controls were studied using a polymerase chain reaction-restriction fragment length polymorphism. There were significant differences in the genotype and allele distribution of 869 T/C polymorphism of the TGF-beta1 gene among cases and controls. The 869 TC and CC genotypes were associated with a significantly increased risk of ESCC as compared with the 869 TT genotypes [odds ratio (OR) = 1.882, 95% confidence interval (CI) 1.212-2.923, P = 0.005 and OR = 2.099, 95% CI 1.288-3.421, P = 0.003, respectively]. Consistent with the results of the genotyping analyses, the -509 T/869 C haplotype was associated with a significantly increased risk of ESCC as compared with the -509 C/869 T haplotype (OR = 1.463; 95% CI 1.120-1.912; P = 0.005). This study shows for the first time that TGF-beta1 gene 869 T/C polymorphism may contribute to a genetic risk factor for ESCC in a Chinese population.

Interleukin-10 gene promoter polymorphisms and the risk of nasopharyngeal carcinoma.

Genetic factors are known to be important in the development of nasopharyngeal carcinoma (NPC). Interleukin-10 (IL-10) is an immunosuppressive cytokine which may facilitate development of cancer by supporting tumor escape from the immune response. Interindividual variations in IL-10 production were genetically contributed to polymorphisms within IL-10 promoter region. The aim of this study was to determine whether single nucleotide polymorphisms (SNPs) at positions -1082 (A/G), -819 (T/C) and -592 (A/C) in the IL-10 gene promoter were involved in predisposing an individual to NPC. One hundred and ninety-eight patients with NPC and 210 age- and sex-matched controls, genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism. There were significantly differences in the genotype and allele distribution of -1082 A/G polymorphism of the IL-10 gene among cases and controls. The -1082 AG and GG genotypes were associated with a significantly increased risk of NPC as compared with the -1082 AA genotypes. Haplotype analysis showed that the homozygosity of the GCC haplotype (defined by SNPs at positions -1082, -819 and -592) of IL-10 gene conveys the highest risk for NPC compared with the homozygosity for the ATA haplotype. This study shows for the first time an association between IL-10 gene promoter -1082 A/G polymorphism and its haplotype may contribute to genetic susceptibility to NPC in a Chinese population.

Adjustability of the circadian clock in the cockroaches: a comparative study of two closely related species, Blattella germanica and Blattella bisignata.

A single 2h light pulse (250 lux) was given at various times to phase shift the locomotor circadian rhythm of two species of closely related cockroaches, Blattella bisignata and Blatella germanica. The phase-response curve (PRC) of both species showed a similar pattern. Phase delays and advances were induced by light pulse during the early and late subjective night, respectively, while no clear phase shifting was elicited during the subjective day. However, the magnitude of the phase delay (1.89h +/- 0.66h) and advance (0.69h +/- 0.36h) of B. bisignata was significantly larger than that of B. germanica (0.78h +/- 0.38h and 0.35h +/- 0.18h, respectively). This result indicates the superior adjustability of the circadian clock in B. bisignata. The period-response curve (PdRC) was also constructed for both species. Although both species did not show great flexibility in circadian period changes, the phase shifts were significantly correlated with the period changes in the advance zone of B. bisignata (r = 0.72, P < .1). This allowed the circadian clock of B. bisignata to display better entrainability since the phase advance adjustment was significantly more difficult than that of phase delay. The results indicate the overall adjustability of the circadian clock of B. germanica is inferior to that of B. bisignata. The significance of this finding is discussed from an ecological perspective.

Fluorescence quenching of ethidium ion by porphyrin cations and quaternary ammonium surfactants in the presence of DNA.

Fluorescence quenching of free and DNA-bound ethidium bromide (EB) by a number of quaternary ammonium and other compounds was studied. For free EB or bound EB at lower DNA concentration the fluorescence quenching follows the Stern-Volmer equation and at higher DNA concentration follows an exponential model. At least at low quencher concentrations the quenching efficiency varies with DNA or NaCl concentrations and is about 100 times greater for bound than free EB. The quenching pathways may involve energy transfer and conformational loosening or distortion of the DNA helix in addition to possible electron transfer.