[Clinical features and prognostic analysis of testicular relapse in pediatric acute lymphoblastic leukemia]

Objective: To investigate the clinical features and prognosis of testicular relapse in pediatric acute lymphoblastic leukemia (ALL). Methods: Clinical data including the age, time from initial diagnosis to recurrence, relapse site, and therapeutic effect of 37 pediatric ALL with testicular relapse and treated in Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences between November 2011 and December 2022 were analyzed retrospectively. Patients were grouped according to different clinical data. Kaplan-Meier analysis was used to evaluate the overall survival (OS) rate and event free survival (EFS) rate for univariate analysis, and Cox proportional-hazards regression model was used to evaluate the influencing factors of OS rate and EFS rate for multivariate analysis. Results: The age at initial diagnosis of 37 pediatric testicular relapse patients was (5±3) years and the time from initial diagnosis to testicular recurrence was (37±15) months. The follow-up time was 43 (22, 56) months. Twenty-three patients (62%) were isolated testis relapse. The 5-year OS rate and EFS rate of the 37 relapsed children were (60±9) % and (50±9) % respectively. Univariate analysis showed that the 2-year EFS rate in the group of patients with time from initial diagnosis to testicular recurrence >28 months was significantly higher than those ≤28 months ((69±10)% vs. (11±11)%, P<0.05), 2-year EFS rate of the isolated testicular relapse group was significantly higher than combined relapse group ((66±11)% vs. (20±13) %, P<0.05), 2-year EFS rate of chimeric antigen receptor T (CAR-T) cell treatment after relapse group was significantly higher than without CAR-T cell treatment after relapse group ((78±10)% vs. (15±10)%, P<0.05). ETV6-RUNX1 was the most common genetic aberration in testicular relapsed ALL (38%, 14/37). The 4-year OS and EFS rate of patients with ETV6-RUNX1 positive were (80±13) % and (64±15) %, respectively. Multivariate analysis identified relapse occurred≤28 months after first diagnosis (HR=3.09, 95%CI 1.10-8.72), combined relapse (HR=4.26, 95%CI 1.34-13.52) and CAR-T cell therapy after relapse (HR=0.15,95%CI 0.05-0.51) were independent prognostic factors for 2-year EFS rate (all P<0.05). Conclusions: The outcome of testicular relapse in pediatric ALL was poor. They mainly occurred 3 years after initial diagnosis. ETV6-RUNX1 is the most common abnormal gene.Patients with ETV6-RUNX1 positive often have a favorable outcome. Early relapse and combined relapse indicate unfavorable prognosis, while CAR-T cell therapy could significantly improve the survival rate of children with testicular recurrence.

[Clinical and prognostic characteristics of pediatric acute myeloid leukemia with myelodysplasia-related changes under different diagnostic criteria]

Objective: To evaluate the clinical and prognostic differences in acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) children under different diagnostic criteria (World Health Organization (WHO) 2016 and WHO 2022 criteria). Methods: In this retrospective cohort study, clinical characteristics and prognosis information of 260 acute myeloid leukemia (AML) children admitted to Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences from August 2017 to August 2021 were analyzed retrospectively. According to WHO 2016 and WHO 2022 diagnostic criteria, patients were divided into AML-MRC group and non-AML-MRC group, the prognostic and genetic differences between two groups were compared respectively. Meanwhile, the characteristics of children with 8 MRC-related genes defined in WHO 2022 diagnostic criteria were described. Mann-Whitney U test, chi-square test were used for comparison between groups. Survival curve was plotted by Kaplan-Meier method, and comparison between groups was performed by Log-Rank method. Results: Among the 260 children, there were 148 males and 112 females. The follow-up time was 26 (16, 38) months. A total of 28 children (10.8%) were diagnosed with AML-MRC according to the WHO 2016 diagnostic criteria. Compared with non-AML-MRC children, the frequency of PTPN11, RUNX11, SH2B3, MPL and STAG2 mutations was higher in AML-MRC children (25.0% (7/28) vs. 4.3% (10/232), 14.3% (4/28) vs. 3.9% (9/232), 10.7% (3/28) vs. 2.2% (5/232), 10.7% (3/28) vs. 2.2% (5/232), 10.7% (3/28) vs. 0.9% (2/232), all P<0.05). The 2-year overall survival (OS) and events free survival (EFS) rate of 28 AML-MRC children under WHO 2016 diagnostic criteria were worse than those of 232 non-AML-MRC children ((62.1±10.8)% vs. (94.5±1.6)%, χ2=22.1,P<0.001;(48.0±10.6)% vs. (70.9±3.2)%, χ2=6.33,P=0.012). Twenty-seven children (10.4%) were eventually diagnosed with AML-MRC according to WHO 2022 criteria, their 2-year OS rate were worse than 233 non-AML-MRC children ((60.8±11.1)% vs. (94.5±1.6)%, χ2=24.49,P<0.001), and there was no statistically significant difference in EFS rate between two groups at 2 years ((55.1±10.8)% vs. (70.1±3.2)%, χ2=2.44, P=0.119). Conclusions: Compared with the 2022 WHO diagnostic criteria, the survival rates of children with AML-MRC under the 2016 WHO diagnostic criteria were worse than that of children without MRC.The new version of the AML-MRC diagnostic criteria emphasizes the importance of genes.

Whole Liver Radiotherapy for Multiple Liver Metastases in Thoracic Malignancies

PURPOSE/OBJECTIVE(S)

Liver metastases (LM) are common in advanced thoracic cancer patients with dismal oncological outcomes. Even in the modern era of novel systemic therapy, LM led to a 21% increased mortality risk compared with those without. Options for progressive multiple LM after systemic therapy are limited. Therefore, a different treatment modality is urgently needed to overcome such a predicament. Herein, we renovate the classical whole liver radiotherapy (WLRT) and evaluate its efficacy and safety in treating thoracic cancer patients with progressive multiple LM.

MATERIALS/METHODS

Patients with lung or thymic cancer who had multiple LM treated by WLRT between 2018 and 2022 were enrolled. Radiotherapy (RT) was delivered with a median dose of 24 Gy (range 8-25 Gy) in 8 fractions (range 1-16) at the discretion of treating physicians. Overall survival (OS) and cumulative incidence of intrahepatic progression were calculated from the completion of WLRT till death or progression by Kaplan-Meier and competing risk analyses, respectively.

RESULTS

Twenty-four patients were enrolled in this retrospective study. Eleven patients (46%) had lung adenocarcinoma, of which nine patients had oncogenic mutations. Six patients (25%) had small cell lung cancer (SCLC), four patients (17%) had thymic squamous cell carcinoma (SqCC), two patients (8%) had lung SqCC, and one patient (4%) had mixed histology. Eighteen patients (75%) were under systemic therapy treatment before the diagnosis of LM, and fifteen (63%) received LM biopsy. The median time from the diagnosis of LM to WLRT was 7.5 months (range, 0.5-33.9 months). Eleven patients (46%) had concurrent RT and systemic therapy. With a median follow-up of 3.1 months, the 3-, 6- and 12-month OS were 57%, 38%, and 15%, respectively. After adjusting death as a competing risk, the cumulative incidence of LM progression at 3, 6, and 12 months were 10%, 19%, and 44%, respectively. Within three months after the completion of RT, one patient (4%) had grade 5 radiation-induced liver disease (RILD), one patient (4%) had grade 4 abnormal liver function test (LFT), three patients (13%) had grade 3 abnormal LFT, and twelve patients (50%) had ≤ grade 2 abnormal LFT. The patient who had Gr.5 RILD expired 51 days after the completion of RT with 24 Gy in 8 fractions concurrently with topotecan. He had primary SCLC with viral hepatitis B. His LFT was around the normal upper limit before WLRT.

CONCLUSION

WLRT provided favorable intrahepatic control with acceptable radiation-related toxicities and could be considered a treatment option for patients with progressive LM under systemic therapy. Further investigation with a larger cohort is warranted to identify patients at a high risk of developing severe RILD.

Comparison of Hippocampal Volume Change after Whole-Brain Radiotherapy with and without Hippocampal Avoidance: A Post-Hoc Analysis of a Phase II Randomized Trial

PURPOSE/OBJECTIVE(S)

Hippocampal avoidance whole-brain radiotherapy (HA-WBRT) preserves verbal memory compared to conformal WBRT in the previously reported randomized phase II clinical trial. In the present study, we analyzed the changes in hippocampus volume between groups at longitudinal follow-up time points. We hypothesize better preservation of hippocampus volumes with time in the HA-WBRT group.

MATERIALS/METHODS

In this post-hoc analysis of a single institution, single-blind, randomized phase II trial, patients with brain metastases were randomized to receive either HA-WBRT or conformal WBRT with 30 Gy in 10 fractions. Patients received gadolinium contrast-enhanced MRI every three months or when clinically indicated after WBRT until progression. Only patients with at least one follow-up MRI were included. The MRI was used to assess baseline intracranial volume, hippocampal volume, the ratio of the total hippocampus to total intracranial volume (HT%), and the ratio of the left (HL%) or right (HR%) hippocampus to total intracranial volume. The volumes were automatically calculated by volBrain, an online MRI brain volumetry system. We used linear mixed models with fixed and random effects to compare the changes of repeated measures of the hippocampus volumes over time between the two groups.

RESULTS

Among 70 randomized patients, 51 (25 in the HA-WBRT group and 26 in the WBRT group) were included in the present analysis. There were no significant differences between the two groups in the baseline demographics, HT%, HR%, and HL%. The median follow-up time was 13.9 months (range 2.1-31.8 months), and more than 60% of patients had at least one year of follow-up. Linear mixed model analyses showed a more significant decrease of HT% over time in the WBRT arm (regression coefficient β = -0.002, p = 0.001) compared to the HA-WBRT arm (regression coefficient, β = -0.001, p = 0.254), with a significant group by time interaction (F-value = 4.27, p = 0.050). The HL% was stable over time in the HA-WBRT arm (β = 0.0001, p = 0.769) while it decreased in the WBRT arm (β = -0.001, p = 0.003), with a significant group by time interaction (F-value = 6.51, p = 0.015). In contrast, the HR% decreased over time in both groups (HA-WBRT: regression coefficient β = -0.001, p = 0.006; WBRT: regression coefficient β = -0.001, p < 0.001) without significant group by time interaction (F-value = 0.20, p = 0.662).

CONCLUSION

HA-WBRT better preserves total hippocampus volume with time compared to WBRT, with the main effect contributed by preserving the left hippocampus volume. Further research is warranted to establish the relationship between hippocampus volume perpetuation and cognitive function preservation. The future goal is to investigate whether left-side unilateral HA-WBRT provides similar neurocognitive function preservation compared to standard bilateral HA-WBRT.

[Genomics of next generation sequencing in pediatric B-acute lymphoblastic leukemia and its impact on minimal residual disease]

Objective: To describe the gene mutation profile of newly diagnosed pediatric B-acute lymphoblastic leukemia (B-ALL) and analyze its effect on minimal residual disease (MRD). Methods: A total of 506 newly diagnosed B-ALL children treated in Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences from September 2018 to July 2021 were enrolled in this retrospective cohort study. The enrolled children were divided into MRD ≥1.00% group and <1.00% group according to MRD results on the 19th day since chemotherapy, and MRD ≥0.01% group and <0.01% group according to MRD results on the 46th day. Clinical characteristics and gene mutations of two groups were compared. Comparisons between groups were performed with chi-square test or Fisher's exact test. Independent risk factors of MRD results on the 19th day and the 46th day were analyzed by Logistic regression model. Results: Among all 506 patients, there were 318 males and 188 females. On the 19th day, there were 114 patients in the MRD ≥1.00% group and 392 patients in the MRD <1.00% group. On the 46th day, there were 76 patients in the MRD ≥0.01% group and 430 patients in the MRD <0.01% group. A total of 187 gene mutations were detected in 487 (96.2%) of 506 children. The most common gene mutations were signal transduction-related KRAS gene mutations in 111 cases (22.8%) and NRAS gene mutations in 99 cases (20.3%). Multivariate analysis showed that PTPN11 (OR=1.92, 95%CI 1.00-3.63), KMT2A (OR=3.51, 95%CI 1.07-11.50) gene mutations and TEL-AML1 (OR=0.48, 95%CI 0.27-0.87), BCR-ABL1 (OR=0.27, 95%CI 0.08-0.92) fusion genes and age >10 years (OR=1.91, 95%CI 1.12-3.24) were independent influencing factors for MRD ≥1.00% on the 19th day. BCORL1 (OR=2.96, 95%CI 1.18-7.44), JAK2 (OR=2.99, 95%CI 1.07-8.42) and JAK3 (OR=4.83, 95%CI 1.50-15.60) gene mutations and TEL-AML1 (OR=0.43, 95%CI 0.21-0.87) fusion gene were independent influencing factors for MRD ≥0.01% on the 46th day. Conclusions: Children with B-ALL are prone to genetic mutations, with abnormalities in the RAS signaling pathway being the most common. Signal transduction related PTPN11, JAK2 and JAK3 gene mutations, epigenetic related KMT2A gene mutation and transcription factor related BCORL1 gene mutation are independent risk factors for MRD.

[Demographic characteristics and associated influencing factors in treated patients with chronic hepatitis B with hypoviremia : a single-center retrospective cross-sectional study]

Objective: To investigate the demographic characteristics and clinical influencing factors which associates with the occurrence probability of persistent or intermittent hypoviremia (LLV) in patients with chronic hepatitis B (CHB) treated with nucleos(t)ide analogues (NAs). Methods: A single-center retrospective analysis was performed on patients with CHB who received outpatient NAs therapy for≥48 ± 2 weeks. According to the serum hepatitis B virus (HBV) DNA load at 48±2 weeks treatment, the study groups were divided into LLV (HBV DNA < 20 IU/ml and < 2 000 IU/ml) and MVR group (sustained virological response, HBV DNA < 20 IU/ml). Demographic characteristics and clinical data at the start of NAs treatment (considered as baseline) were retrospectively collected for both patient groups. The differences in the reduction of HBV DNA load during treatment was compared between the two groups. Correlation and multivariate analysis were further conducted to analyze the associated factors influencing the LLV occurrence. Statistical analysis was performed using the independent samples t-test, c2 test, Spearman analysis, multivariate logistic regression analysis, or area under the receiver operating characteristic curve. Results: A total of 509 cases were enrolled, with 189 and 320 in the LLV and MVR groups, respectively. Compared to patients with MVR group at baseline: (1) the demographics characteristics of patients showed that LLV group was younger in age (39.1 years, P = 0.027), had a stronger family history (60.3%, P = 0.001), 61.9% received ETV treatment, and higher proportion of compensated cirrhosis (20.6%, P = 0.025) at baseline; (2) the serum virological characteristics of patients showed that LLV group had higher HBV DNA load, qHBsAg level, qHBeAg level, HBeAg positive rate, and the proportion of genotype C HBV infection but decreased HBV DNA during treatment (P < 0.001) at baseline; (3) the biochemical characteristics of patients showed that LLV group had lower serum ALT levels (P = 0.007) at baseline; (4) the noninvasive fibrosis markers of patients showed that LLV group were characterized by high aspartate aminotransferase platelet ratio index (APRI) (P = 0.02) and FIB-4 (P = 0.027) at baseline. HBV DNA, qHBsAg and qHBeAg were positively correlated with LLV occurrence (r = 0.559, 0.344, 0.435, respectively), while age and HBV DNA reduction were negatively correlated (r = -0.098, -0.876, respectively). Logistic regression analysis showed that ETV treatment history, high HBV DNA load at baseline, high qHBsAg level, high qHBeAg level, HBeAg positive, low ALT and HBV DNA level were independent risk factors for patients with CHB who developed LLV with NAs treatment. Multivariate prediction model had a good predictive value for LLV occurrence [AUC 0.922 (95%CI: 0.897 ~ 0.946)]. Conclusion: In this study, 37.1% of CHB patients treated with first-line NAs has LLV. The formation of LLV is influenced by various factors. HBeAg positivity, genotype C HBV infection, high baseline HBV DNA load, high qHBsAg level, high qHBeAg level, high APRI or FIB-4 value, low baseline ALT level, reduced HBV DNA during treatment, concomitant family history, metabolic liver disease history, and age < 40 years old are potential risk factors for developing LLV in patients with CHB during the therapeutic process.

[Analysis of bloodstream infections in children with acute myeloid leukemia during induction chemotherapies]

Objective: To explore the clinical features of bloodstream infections (BSI) in children with acute myeloid leukemia (AML) during the first induction chemotherapy. Methods: The clinical data, pathogen of BSI, antibiotic susceptibility in vitro, complications and prognosis of 204 newly diagnosed AML children admitted to Blood Diseases Hospital, Chinese Academy of Medical Sciences from August 2009 to December 2015 were analyzed retrospectively. χ² test was used for the comparison between groups and Logistic regression was used for BSI risk factor analysis. Results: Among 204 patients, 116 were males and 88 were females. The age was 8 (ranged from 1 to 14) years. Among them, 170 patients received MAE chemotherapies (etoposide, mitoxantrone and cytarabine) and 25 received IAE chemotherapies (etoposide, idarubicin and cytarabine). The other 9 patients used granulocyte colony stimulating factor (G-CSF)-priming regimen (aclacinomycin or homoharringtonine, cytarabine and G-CSF) for induction treatments. A total of 28 patients experienced BSI and the incidence rate was 13.7% (28/204), 26 of them developed BSI once and 2 patients developed twice. Gram-positive bacteria were predominant pathogens accounting for 53.3% (16/30) while gram-negative bacteria accounting for 40.0% (12/30) and fungal accounted for 6.7% (2/30). The most common detected pathogens were Coagulase negative Staphylococcus (CoNS, 26.7% (8/30)), followed by Streptococcus spp. (13.3% (4/30)) and Escherichia coli (13.3% (4/30)). Among Gram-negative bacteria (GNB), 3 cases showed carbapenem resistance and 2 cases were Stenotrophomonas maltophilia. BSI-related mortality was 28.6% (8/28). Infections caused by drug-resistant GNB or fungi resulted in 6 fatal cases. The incidence rate of BSI in group with severe neutropenia was higher than in group without it (16.6% (25/151) vs. 5.7% (3/53), χ²=3.933, P=0.047). Multivariable analysis showed severe neutropenia at the onset of fever was independent risk factor of BSI (OR=4.258,95%CI 1.097-16.524,P=0.036). Conclusions: During the first induction chemotherapy courses, Gram-positive bacteria cause most of the BSI. Drug-resistant bacteria related infection often result in fatal outcomes. Severe neutropenia is a significant risk factor.

[Analysis of the pathogenic characteristics of fungal bloodstream infection in severe burn patients]

Objective: To retrospectively analyze the diagnosis time, pathogen distribution, and drug resistance of fungal bloodstream infection in severe burn patients. Methods: Blood samples were collected from 55 severe burn patients with fungal bloodstream infection (including 46 males and 9 females, aged 42 (1, 78) years) admitted to the intensive care unit of the Institute of Burn Research of the First Affiliated Hospital of Army Medical University (the Third Military Medical University) from July 2011 to May 2019 for retrospective analysis. Microbial monitoring system was used to cultivate pathogens, API yeast identification kit and Candida chromogenic medium were used to identify pathogens, and Kirby-Bauer paper disk diffusion method was used to detect drug resistance of fungi to fluconazole, amphotericin B, itraconazole, ketoconazole, and voriconazole. The positive rate of blood fungal culture, mortality rate, distribution of local fungal proliferation sites, the diagnosis time distribution of fungal bloodstream infection, the distribution of fungal species, resistance to commonly-used antifungal drugs, and the use of antibiotics were assessed. The WHONET 5.6 software was applied to analyze the distribution and drug resistance of fungi. Results: (1) Totally 4 839 blood samples were collected during the 9 years, and 122 strains of fungi were isolated, with positive rate of 2.52%. The mortality rate was 14.55% (8 patients) in 55 patients. Catheter fungal proliferation ranked the first among 30 cases of local fungal proliferation. (2) The diagnosis time of fungal bloodstream infection mainly distributed in ≤1 week of hospitalization [32.73% (18/55)]. (3) Among the 55 strains of fungi detected, the detection rate of Candida parapsilosis ranked the first (21.82%, 12 strains), Candida glabrata was the second (18.18%, 10 strains), and Candida tropicalis was tied with Candida albicans in the third place (14.55%, 8 strains). All the detected fungi were sensitive to amphotericin B, and the resistance rates to voriconazole, fluconazole, itraconazole, and ketoconazole were between 4.5% and 9.1%. (4) Droad-spectrum antibiotics were used in all the 55 patients, ≥3 kinds of antibiotics were used in 44 patients, and 37 patients used antibacterial drugs ≥7 days. Conclusions: The diagnosis time of fungal bloodstream infection in the 55 severe burn patients was mainly within 1 week of hospitalization. Candida parapsilosis is the most commonly detected fungal species. Catheter fungal proliferation occurs most commonly among the 30 patients with local fungal proliferation. All the detected fungi were sensitive to amphotericin B, with low drug resistance to voriconazole, fluconazole, itraconazole, and ketoconazole. Broad-spectrum antibiotics were overused in the severe burn patients with fungal bloodstream infection.

Effects of sodium butyrate on intestinal health and gut microbiota composition during intestinal inflammation progression in broilers

Butyric acid is a beneficial feed additive used in animal production, including poultry production. However, there are few reports on butyric acid as a prophylactic treatment against intestinal inflammation in broilers. The current study explored the effect of sodium butyrate (SB) as a prophylactic treatment on the intestinal health and gut microbiota of broilers with intestinal inflammation induced by dextran sulfate sodium (DSS) by monitoring changes in intestinal histopathology, gut leakiness indicators, inflammatory cytokines, and gut microbiota composition. Sodium butyrate supplementation prior to DSS administration significantly reduced the lesion scores of intestinal bleeding (P < 0.05) and increased villus height and the total mucosa of the ileum (P < 0.05). Regardless of intestinal inflammation, supplementation with SB at 300 mg/kg significantly decreased the levels of D (-)-lactate (P < 0.05), interleukin-6, and interleukin-1β (P < 0.05) but increased the level of interleukin-10 (P < 0.05). The SB treatment did not affect the alpha diversity of intestinal microbiota during intestinal inflammation progression but altered their composition, and the microbial community structure of treated broilers was similar to that of control broilers. Taken together, our results reveal the importance of SB in improving intestinal development, inducing an anti-inflammatory effect during intestinal inflammation progression, and modulating the microbial community in broilers. Sodium butyrate seems to be optimized for anti-inflammatory effects at higher doses (300 mg/kg SB).

[Heterogeneity and clonal evolution in pediatric ETV6-RUNX1(+) acute lymphoblastic leukemia by quantitative multigene fluorescence in situ hybridization]

目的

研究儿童ETV6-RUNX1阳性急性淋巴细胞白血病（ALL）中肿瘤细胞的异质性及克隆演化情况，探讨克隆演化与预后的相关性。

方法

应用单细胞定量多基因荧光原位杂交（QM-FISH）技术对2006年2月至2011年6月收治的48例ETV6-RUNX1阳性ALL患儿的骨髓标本进行多个基因拷贝数变异的检测，并进行克隆演化分析。将4例复发患儿初诊与复发时的情况进行比较。

结果

在48例行QM-FISH检测的患儿中，初诊时为1个克隆的有34例（70.8%），2个克隆的有9例（18.8%），≥3个克隆的有5例（10.4%）。患儿的肿瘤细胞存在异质性，各亚克隆之间呈线性或树枝状演化。白血病细胞的亚克隆数与患者预后无相关性（5年总生存率：P=0.469；5年无病生存率：P=0.116）。复发克隆可能与初诊时克隆一致，也可能为新出现克隆。复发克隆为新出现克隆的患儿再次缓解时间短，预后更差。

结论

ETV6-RUNX1阳性ALL患儿肿瘤细胞存在异质性及克隆演化情况。QM-FISH有助于研究白血病细胞的克隆演化，复发克隆为新出现克隆的患儿可能预后更差。

Astrocyte-Secreted Chordin-like 1 Drives Synapse Maturation and Limits Plasticity by Increasing Synaptic GluA2 AMPA Receptors

In the developing brain, immature synapses contain calcium-permeable AMPA glutamate receptors (AMPARs) that are subsequently replaced with GluA2-containing calcium-impermeable AMPARs as synapses stabilize and mature. Here, we show that this essential switch in AMPARs and neuronal synapse maturation is regulated by astrocytes. Using biochemical fractionation of astrocyte-secreted proteins and mass spectrometry, we identified that astrocyte-secreted chordin-like 1 (Chrdl1) is necessary and sufficient to induce mature GluA2-containing synapses to form. This function of Chrdl1 is independent of its role as an antagonist of bone morphogenetic proteins (BMPs). Chrdl1 expression is restricted to cortical astrocytes in vivo, peaking at the time of the AMPAR switch. Chrdl1 knockout (KO) mice display reduced synaptic GluA2 AMPARs, altered kinetics of synaptic events, and enhanced remodeling in an in vivo plasticity assay. Studies have shown that humans with mutations in Chrdl1 display enhanced learning. Thus astrocytes, via the release of Chrdl1, promote GluA2-dependent synapse maturation and thereby limit synaptic plasticity.

Validation of aspirin response-related transcripts in patients with coronary artery disease and preliminary investigation on CMTM5 function

Aspirin is widely used in the prevention of cardiovascular diseases, but the antiplatelet responses vary from one patient to another. To validate aspirin response related transcripts and illustrate their roles in predicting cardiovascular events, we have quantified the relative expression of 14 transcripts previously identified as related to high on-aspirin platelet reactivity (HAPR) in 223 patients with coronary artery disease (CAD) on regular aspirin treatment. All patients were followed up regularly for cardiovascular events (CVE). The mean age of our enrolled population was 75.80±8.57years. HAPR patients showed no significant differences in terms of co-morbidities and combined drugs. Besides, the relative expression of HLA-DQA1 was significantly lower in low on-aspirin platelet reactivity (LAPR) patients, when compared with HAPR and high normal (HN) group (p=0.028). What's more, the number of arteries involved, HAPR status and the relative expression of CLU, CMTM5 and SPARC were independent risk factors for CVE during follow up (p<0.05). In addition, overexpression of CMTM5 attenuated endothelial cells (ECs) migration and proliferation, with significantly decreased phosphorylated-Akt levels, while its inhibition promoted these processes in vitro (p<0.05).Our study provides evidence that circulating transcripts might be potential biomarkers in predicting cardiovascular events. CMTM5 might exert anti-atherosclerotic effects via suppressing migration and proliferation in the vessel wall. Nevertheless, larger-scale and long-term studies are still needed.

1,1′-[1,4-Phenylenebis(methylene)]bis(2-methyl-1H-imidazol-3-ium) 2,4-dicarboxybenzene-1,5-dicarboxylate monohydrate

In the dication of the title compound, C₁₆H₂₀N₄²⁺·C₁₀H₄O₈²⁻·H₂O, the dihedral angles formed by mean planes of the imidazolium rings and the benzene ring are 69.05 (18) and 89.1 (2)°. In the crystal, the components are linked into a three-dimensional network by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds.

Bis(2-propyl-1H-imidazol-3-ium) bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6)cadmate(II)

The title salt, (C₆H₁₁N₂)₂[Cd(C₇H₃NO₄)₂], displays a discrete mononuclear structure, in which the central Cd^II atom is six-coordinated in a distorted octa­hedral coordination geometry by two N and four O atoms from two different pyridine-2,6-dicarboxyl­ate anions in an O²,N,O⁶-tridentate chelation mode. The crystal packing is stabilized by N—H⋯O hydrogen bonds and π–π inter­actions [centroid–centroid distance = 3.576 (5) Å].

1,4-Bis(1H-benzimidazol-1-yl)but-2-ene

In the pseudo-centrosymmetric mol­ecule of the title compound, C₁₈H₁₆N₄, two benzimidazole fragments form the dihedral angles of 83.49 (7) and 79.37 (7)°, with the mean plane of the linking butene chain. No classical inter­molecular inter­actions are observed. The porous crystal packing exhibits voids of 85 ų.

Poly[[(1,10-phenanthroline)(μ-l-tartrato)zinc] hexa-hydrate]

The title compouand {[Zn(C₄H₄O₆)(C₁₂H₈N₂)]·6H₂O}_n, has a linear chain structure parallel to [100] with Zn(C₄H₄O₆)(C₁₂H₈N₂) repeat units; the asymmetric unit consists of one Zn²⁺ cation, one l-tartrate dianion, one 1,10-phenanthroline and six free water mol­ecules. The Zn atom is in a distorted octa­hedral ZnN₂O₄ coordination environment. The crystal structure is stabilized by O—H⋯O hydrogen bonds and π–π stacking of the phenanthroline units [centroid–centroid distances in the range 3.552 (2)–3.625 (2)Å] occurs between the chains. The title compound is isotypic with the Cu and Mn analogues.

1,4-Bis[(1H-pyrazol-1-yl)meth-yl]benzene

In the title compound, C(14)H(14)N(4), the center of the phenyl-ene group is a crystallographic center of inversion. The compound is composed of three aromatic rings displaying a Z-like conformation. The dihedral angle between the pyrazole rings and the central phenyl ring is 83.84 (9)°.

Hexa-kis-(1-benzyl-1H-imidazole-κN)manganese(II) bis-(perchlorate)

In the title compound, [Mn(C₁₀H₁₀N₂)₆](ClO₄)₂, the Mn^II ion, located on an inversion center, is coordinated by six N atoms from three pairs of symmetry-related 1-benzyl-1H-imidazole ligands in a distorted octa­hedral geometry. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds link the complex cations and perchlorate anions.

3,3'-(p-Phenyl-enedimethyl-ene)di-1H-imidazol-1-ium bis-(4-nitro-benzoate)-4-nitro-benzoic acid (1/2)

The asymmetric unit of the title compound, C₁₄H₁₆N₄²⁺·2C₇H₄NO₄⁻·2C₇H₅NO₄, comprises one-half of the 3,3′-(p-phenyl­enedimethyl­ene)di-1H-imidazol-1-ium dication, which lies on an inversion centre, one 4-nitro­benzoate anion and one 4-nitro­benzoic acid mol­ecule. In the crystal, the components are linked into a two-dimensional network parallel to (110) by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds.

Single and joint toxicity of cypermethrin and copper on Chinese cabbage (Pakchoi) seeds

The single and joint effects of Cu(2+) and cypermethrin (CPM) on the seed germination and the elongation of root and shoot of Pakchoi were investigated. The results showed that in solution low concentrations of Cu(2+) could accelerate the germination rate of Pakchoi, whereas high concentrations of Cu(2+) could inhibit it. CPM could strongly inhibit the germination of Pakchoi in solution. However, in the joint toxicity effect, CPM reduced the phytotoxicity of Cu(2+) on the germination of Pakchoi seeds under solution conditions. In the single-factor experiments and joint effect tests of CPM and copper on the seedling growth, it was found that there were significant liner relationships between concentrations of pollutants and root elongation (P<0.05). Copper and CPM had synergic effects on root elongation of Pakchoi in solution cultivation test. However, in soil culture test, these synergistic effects were not significant (P<0.05). Meanwhile, the joint toxicity was more dependent on the effect of copper than that of CPM. The toxicity of the pollutants to seed germination, shoot and root elongation is in the following sequence: root elongation>shoot elongation>germination rate.

Effect of tetramethyl pyrazine on L-type calcium channel in rat ventricular myocytes

To elucidate possible ionic mechanisms of antimyocardial ischemia and antiarrythmia of tetramethyl pyrazine (TP), we studied L-type Ca2+ currents (I(Ca.L)) in adult rat ventricular myocytes using the whole-cell patch-clamp technique. The results showed: (i) under physiological conditions, 0.25 mmol/L TP decreased amplitude of I(Ca.L) to 60.6% and this inhibition was increased with increasing concentration of TP. ID50 was 0.20 mmol/L. (ii) The Ca2+-antagonistic effect of TP was voltage-dependent. A marked negative shift of the steady-state inactivation curve was observed with long (10 s) conditioning prepulses, but not with short (350 ms) ones. (iii) The time course of inhibition during TP treatment was increased with an increase in drug concentration, and recovery from TP-induced inactivation of I(Ca.L) was slower than in control cases. (iv) Tonic block and use-dependent block with TP treatment, which was induced by increasing the frequency of stimulation, occurred. We suggest that TP inhibits the I(Ca.L) mainly by binding to inactivated Ca2+ channels. The high affinity of TP for the inactivated state of I(Ca.L) may play an important role in developing therapies for pathological conditions.

Copper(II) complexes with N,N'-dialkyl-1,10-phenanthroline-2,9-dimethanamine: synthesis, characterization, DNA-binding thermodynamical and kinetic studies

Copper(II) complexes (Cu-L, L=N,N'-dialkyl-1,10-phenanthroline-2,9-dimethanamine) were synthesized and characterized by elemental analyses, IR spectra and conductance measurement. The interaction of the copper(II) complex with calf thymus DNA was studied by means of UV melting experiments, fluorescence spectra and circular dichroic spectra. Using ethidium bromide as a fluorescence probe, the binding mode of the complexes Cu-L with calf-thymus DNA was studied spectroscopically. The results indicate that the complexes Cu-L perhaps interact with calf-thymus DNA by both intercalative and covalent binding. Kinetics of binding of the cupric complexes to DNA was studied for the first time using ethidium bromide as a fluorescence probe with stopped-flow spectrophotometer under pseudo-first-order condition. The stronger binding of two steps in the process of the complexes Cu-L interacting with DNA was observed, and the probable interaction process was discussed in detail. The corresponding k(obs) and E(a) of binding to DNA (where k(obs) is the observed pseudo-first-order rate constant, E(a) is the observed energy of activation) were obtained.

PDZ domain protein GIPC interacts with the cytoplasmic tail of melanosomal membrane protein gp75 (tyrosinase-related protein-1)

Tyrosinase and tyrosinase-related proteins (TRPs) are a family of melanosomal membrane proteins involved in mammalian pigmentation. Whereas the melanogenic functions of TRPs are localized in their amino-terminal domains that reside within the lumen of melanosomes, the sorting and targeting of these proteins to melanosomes is mediated by signals in their cytoplasmic domains. To identify proteins that interact with the cytoplasmic tail of gp75 (TRP-1), the most abundant melanosomal membrane protein, we performed yeast two-hybrid screening of a melanocyte cDNA library. Here, we show that the cytoplasmic domain of gp75 interacts with a PDZ domain-containing protein. The gp75-interacting protein is identical to GIPC, an RGS (regulator of G protein signaling)/GAIP-interacting protein, and to SEMCAP-1, a transmembrane semaphorin-binding protein. Carboxyl-terminal amino acid residues, Ser-Val-Val, of gp75 are necessary and sufficient for interaction of gp75 with the single PDZ domain in GIPC. Although endogenous and transfected GIPCs bind efficiently to transiently expressed gp75, only a small amount of GIPC is found associated with gp75 at steady state. Using a strategy to selectively synchronize the biosynthesis of endogenous gp75, we demonstrate that only newly synthesized gp75 associates with GIPC, primarily in the juxtanuclear Golgi region. Our data suggest that GIPC/SEMCAP-1 plays a role in biosynthetic sorting of proteins, specifically gp75, to melanosomes.

Calcium-activated potassium current in single Novikoff cell

The electrophysiological properties of the hemichannels of the gap junction in a single Novikoff cell was studied using patch-clamp whole-cell recording techniques. During the experiments, a transient outward current (peak current, Ip) was found to be evoked by the increment of depolarized pulses. Ip was voltage-dependent and could be inhibited partly by CsCl and tetraethylammonium (TEA), but was blocked completely by quinidine. When the intracellular free Ca2+ concentration ([Ca2+]i) was increased, the amplitude of Ip was enhanced. Adding 10 mmol/l EGTA in the pipette solution, Ip disappeared. When the cells were bathed in symmetrical high-K+ solution, Ip also completely disappeared. These results suggest that Ip is a calcium-activated potassium current, although it cannot be blocked by apamin.

Synthesis, characterization and cytotoxicity of lanthanum(III) complexes with novel 1,10-phenanthroline-2,9-bis-alpha-amino acid conjugates

Eight lanthanum(III) complexes with novel 1,10-phenanthroline-2,9-bis-alpha-amino acid conjugates were synthesized and characterized by elemental analyses, IR, MS, 1H-NMR, thermal analysis and conductance measurement. All lanthanum(III) complexes and the corresponding soluble ligand in water have been assayed for antitumor activity in vitro against HL-60 (human leukocytoma) cells, HCT-8 (human coloadenocarcinoma) cells, BGC-823 (human stomach carcinoma) cells, BeL-7402 (human liver carcinoma) cells and KB (human nasopharyngeal carcinoma) cells. The results show that several complexes have relative activity against different cell lines. In particular, the complexes La(L2) and La(L5) show relatively high activity against the BeL-7402 cell line. Moreover, they are slightly more effective than cisplatin. DNA binding studies indicate that the complex La(L2) possibly interacts with calf thymus DNA by both intercalative and covalent binding.

The impact of overall treatment time on outcomes in radiation therapy for non-small cell lung cancer

PURPOSE

A retrospective study was carried out to evaluate the impact of overall treatment time (OTT) on the results of radiation therapy for non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

From Jan. 1990 to Dec. 1996, 256 patients with stages I-IIIb NSCLC entered this analysis. All patients received definitive radiotherapy. Biologically effective dose (BED) was used to standardize the irradiation effects. The correlation between OTT and local progression-free survival was analyzed by linear-regression and Cox proportional hazard models. The prognostic variables for survival and distant metastasis were also briefly studied.

RESULTS

OTT had been shortened in 64 patients because of an accelerated hyperfractioned irradiation, while OTT was prolonged i n 114 patients due to interruptions of irradiation courses. The main ca uses of interruption were machine breakdown or delayed preparations of c errobend block for boost fields (55%), holidays (11%) and treatment toxi city and side effects (34%). Patients tre ated with prolonged OTT (> 45 days) had significant poorer local progression-free survival than whom with OTT of </=45 days, 1, 3 and 5 year actuarial local progression-free survivals being 49, 17 and 15% for the former, and 74, 35 and 25% for the latter, respectively (P<0.001). BED-T that contained the factor of OTT correlated directly to local controls, which implied that BED-T represented radiobiological effects accurately, in other words, OTT had played a role in determining the radiobiological effects. Linear-regression on 103 cases treated with BED of 80-85 Gy(10) showed that 3 year local progression-free survival decreased by 9% per week with prolongation of OTT, or vice versa it increased by 9% per week with shortening OTT in an OTT range of 30-76 days. Cox multivariate analyses confirmed that OTT was an independent prognostic factor for local controls.

CONCLUSION

OTT may have played an important role in determining local controls in radiotherapy for NSCLC. One should always keep in mind to make the OTT as short as possible, provided the patients can tolerate it, and to reduce irradiation interruptions for whatever reasons to a minimum.

Impaired production of IL-12 in systemic lupus erythematosus. III: deficient IL-12 p40 gene expression and cross-regulation of IL-12, IL-10 and IFN-gamma gene expression

Interleukin 12 (IL-12) is a heterodimer comprising p35 and p40 subunits which are encoded and regulated separately. The authors previously demonstrated deficient IL-12 production in SLE which correlates negatively with disease activity. The present study was designed to determine whether deficiency of IL-12 and excess production of IL-10 and IL-6 in systemic lupus erythematosus (SLE) are due to aberrant regulation at the gene level. Using semiquantitative RT-PCR assay, it was shown that constitutive expression of IL-12 p35 gene is somewhat impaired in SLE compared with controls and that IL-12 p40 mRNA, which was present at low levels in controls, was undetectable in unstimulated SLE peripheral blood mononuclear cells (PBMC). Gene expression of IL-12 p35 and p40 was significantly increased in response to SAC, with significantly lower SAC-induced expression of p40 in SLE patients than controls. SAC-stimulated IL-12 p35 and p40 mRNAs were significantly augmented by interferon gamma (IFN-gamma). Exogenous IL-12 or IFN-gamma significantly inhibited IL-10 gene expression, without affecting IL-6 mRNA or other proinflammatory cytokine mRNA levels. These observations were further confirmed by studies of protein production at the single cell level using ELISPOT assay. Downregulation of IL-12 p40 expression appears to be the cause of IL12 p70 deficiency in SLE. If this defect could be repaired, normalization of IL-12 and IFN-gamma production should reduce excessive IL-10 and prevent pathology.

Effects of TPA on dye transfer and dye leakage in fibroblasts transfected with a connexin 43 mutation at ser368

In order to investigate the site of active phosphorylation under treatment with TPA, both wild type (WT) fibroblasts and fibroblasts from Cx43-knockout mice transfected with Cx43 mutated at ser368 were used to study the effects of TPA on dye leakage and gap junction assembly. Results showed that in control conditions with or without EGTA, no significant differences in dye leakage were observed between these two kinds of cells. However, under TPA treatment, non-leakage cases in the mutant cells were much less than those in WT cells. In the two types of reaggregated cells, there was a marked difference in the capacity for dye transfer. Dye transfer in WT cells was 4-fold stronger than in mutant cells. While under TPA treatment, the difference between WT and mutant cells was diminished suggesting that ser368 was probably the most important phosphorylation site under treatment with TPA.

Impaired production of IL-12 in systemic lupus erythematosus. I. Excessive production of IL-10 suppresses production of IL-12 by monocytes

Interleukin 12 (IL-12) plays a crucial role in defensive immune responses, modulation of cytokine production and is involved in the pathogenesis of some autoimmune diseases. The authors investigated whether decreased in vitro production of IL-12 occurs in systemic lupus erythematosus (SLE), in which the cytokine secreting pattern is predominantly type 2. IL-12 production by SLE peripheral blood mononuclear cells (PBMC) was significantly impaired compared with normal PBMC, and this was not due to decreased numbers of monocytes. After depletion of non-adherent cells from PBMC, monocytes of SLE patients produced significantly less IL-12 than those of controls, but IL-12 levels in SLE and control non-adherent cells supernatants were not significantly different. Exogenous recombinant (r)IL-10 strongly inhibited IL-12 production by both SLE and normal PBMC and anti-IL-10 neutralizing antibody significantly reversed the IL-12 deficiency of SLE PBMC and SLE monocytes, while not affecting normal PBMC. Recombinant interferon gamma (rIFN-gamma) considerably enhanced IL-12 production in both SLE and normal PBMC, but it did not significantly reverse the inhibitory effect of rIL-10 on IL-12 production. IL-12 production was significantly lower in patients with active SLE than those in remission. These results suggest that SLE monocytes may be deficient in IL-12 production and that this is secondary to abnormal production of various cytokines, especially excessive production of IL-10.

Impaired production of IL-12 in system lupus erythematosus. II: IL-12 production in vitro is correlated negatively with serum IL-10, positively with serum IFN-gamma and negatively with disease activity in SLE

Interleukin 12 (IL-12) is a key cytokine in regulating type 1 or type 2 cytokine production and in determining the nature of immune responses. Our previous studies demonstrated that its production was significantly impaired in systemic lupus erythematosus (SLE) patients and this deficient IL-12 production was mainly mediated by excessive endogenous IL-10. The present study was designed to further reveal the relationships of in vitro IL-12 production with abnormalities of in vivo cytokine synthesis and disease activity in SLE. Experimental results showed that IL-12 production in vitro was inversely correlated with serum IL-10 level, anti-ds DNA antibody level and SLE disease activity index (DAI), but positively correlated with serum interferon gamma (IFN-gamma) level, with which serum IL-10 correlated negatively. Data also showed that serum IL-10 was significantly higher than that of controls and closely correlated with anti-ds DNA antibody level and SLEDAI. The study confirms that deficient IL-12 production in SLE patients is associated with in vivo abnormalities of cytokine production, especially with increased IL-10 production.

Inhibitory effects of 12-O-tetradecanoylphorbol-13-acetate on dye leakage from single Novikoff cells and on dye transfer between reaggregated cell pairs

The inhibitory effects of 12-O-tetradeconylphorbol-13-acetate (TPA) on the Lucifer Yellow leakage in single (nondissociated and dissociated) Novikoff cells in the presence of ethyleneglycotetraacetic acid (EGTA) and transfer between reaggregated cell pairs were investigated. Under treatment with TPA, single Novikoff cells showed inhibition of the dye leakage in the presence of EGTA, especially after 60-min treatment. There were only slight differences between nondissociated and dissociated cells in these experiments. The dye transfer in reaggregated cell pairs were significantly inhibited after 30-min treatment with TPA. In pretreatment with TPA during the recovery period of reaggregation the dye transfer in cell pairs was completely blocked. It was suggested that TPA blocks the assembly of gap junction, while it had no remarkable effect on gating mechanism of the hemichannels.

Hyperfractionated accelerated radiation therapy for non-small cell lung cancer: clinical phase I/II trial

PURPOSE

In an attempt to improve local control and survival of nonsmall cell lung cancer (NSCLC), hyperfractionated accelerated radiation therapy (HART) was carried out as a clinical phase I/II trial.

METHODS AND MATERIALS

HART was delivered by 1.1 Gy/fraction, three fractions per day with intervals of 4 h and five treatment days per week. The clinical tumors were irradiated to 74.3 Gy (72.6-75.9)/66-69 fx, 33 days (29-40) (not corrected for lung density), and the subclinical lesions, to 50.0 Gy (48.4-50.6)/44-46 fx, 33 days (29-40). Sixty-nine patients with NSCLC were enrolled in this study. Nine patients were withdrawn from the study during HART due to different reasons. Sixty patients formed the study for outcome analyses. They were 57 males and 3 females with median age of 61 years (21-77). There were 41 cases of squamous cell carcinoma, 15 cases of adenocarcinoma, and 4 cases of large cell carcinoma. Overall, favorable patients (KPS > or = 70, weight loss < 5% and Stages I, II, IIIa) accounted for 73% (44 of 60) of all patients. Forty-four patients (73%) received adjuvant chemotherapy (DDP + VP16) with median cycles of 1.8 before and/or after HART. In order to compare the outcome of HART with conventional irradiation, 50 NSCLC patients treated by conventional fractionated irradiation (CFI) during the same period were chosen as the basis to evaluate relative effects of HART. They derived from the control group of another clinical trial of hyperfractionated irradiation for NSCLC in the same department. They received median tumor dose of 63.9 Gy (62.8-65.0)/34 fx (32-36), 48 days (45-53).

RESULTS

1. Acute and late complications: (a) In HART, 87% of patients (52 cases) developed acute radiation esophagitis: Grade 1-2, 46 cases (77%) and Grade 3, 6 cases (10%), at 2.5 weeks (2-3.5 weeks) after HART began. Five patients with Grade 3 esophagitis had their HART interrupted for <7 days. In CFI, esophagitis was much less (44%,p < 0.05) with 38% of Grade 1-2 and 6% of Grade 3. (b) In HART, acute pulmonary symptoms (RTOG Grade 1-2) occurred in 17% (10 cases), and acute radiation pneumonitis (Grade 3), in 8% (5 cases), while in CFI, they were 24% and 2% (p > 0.05), respectively. Late lung fibrosis (RTOG Grade 1-2) appeared in 20% (12 cases), whereas 18% in CFI (p > 0.05). (c), No other severe acute or late complications have been observed so far in HART. 2. Immediate response. In HART, 20% of patients (12 cases) achieved CR, 60% (36 cases), PR and 20% (12 cases), NR or PD. In CFI, the above three percentages were 10, 28, and 62%, respectively (p < 0.001). 3. Follow-up. The 1-, 2-, and 3-year actuarial survivals were 72, 47, and 28% for HART, and 60, 18, and 6% for CFI, respectively (p < 0.001). Better local control was seen in HART than in CFI with 1-, 2-, and 3-year local control rates being 71, 44, 29%, and 60, 20, and 5%, respectively (p = 0.001). Distant metastases developed less in HART than in CFI. The 1-, 2-, and 3-year distant metastasis rates were 23, 36, and 50% in HART, but 30, 48, and 80% in CFI (p = 0.021).

CONCLUSION

1. HART could be tolerated by most of the favorable NSCLC patients. The predominant complication was acute esophagitis. No other severe acute or late complications have been observed so far. 2. HART resulted in better survivals and local controls, and less distant metastases than CFI.

The ionic mechanisms of early after depolarization in mouse ventricular myocytes: the role of IK1

The occurrence of early after depolarization (EAD) in single mouse ventricular myocytes was observed and its ionic mechanisms were studied using the patch clamp technique. Under treatment with perfusion of Tyrode's solution containing 3 mM KCl and 3 mM CsCl, 3/6 cases exhibited EAD, while with 3 mM KCl or 3 mM CsCl alone, EAD was not induced. The background steady-state current-voltage (I-V) curves of the myocytes showed no negative slope, i.e., the slope in the range of 50 mV positive to the reversal potential was virtually flat and stayed at a low current level. Under perfusion of 3 mM KCl and 3 mM CsCl, the outward current in the above region decreased nearly to 0: in the myocytes which exhibited EAD, a net inward current (crossover) was displayed in the same region, which was abolished by 10 microM TTX and 10 microM nifedipine. The results of whole-cell inward rectifier current I-V curves were similar to the above background steady-state I-V curves. In mouse ventricular myocytes, transient outward current was very strong with a peak current density of 63 +/- 19 pA/pF, whereas low K+ and Cs+ had no significant effect. 11/30 cases showed obvious delayed rectifier current, but the tail current recorded by envelope method was relatively weak (1.19 +/- 0.35 pA/pF) and insensitive to CsCl or changing of the KCl concentration. The results suggest that under treatment with low K+ and Cs+, the inhibition of inward rectifier current is the basis of the formation of second plateau, while Na and Ca currents contribute to the generation of triggered bursts.

Comparison of lucifer yellow leakage and cell-to-cell transfer following intracellular injection in normal and antisense Novikoff cells under treatment with low extracellular Ca2+

Single and paired control Novikoff and connexin 43 antisense-transfected Novikoff cells (antisense cells) were used to investigate the differences of intercellular dye transfer and leakage between these two types of cells. Lucifer Yellow was injected into cells by iontophoresis. There was no dye leakage in single cells of both types in Swims solution. The dye transfer from injected cell to recipient cell in the normal solution was different in the two types of cell pairs. The transfer was significantly suppressed in antisense cells; 46/84 cases were blocked vs. 1/84 in Novikoff cell pairs. Under EGTA treatment, the dye leakage in single antisense cells was suppressed showing an increase in the very slow rate of leakage (16/40 vs. 6/40), and the mean rate of leakage was also significantly low. This suggests that dye transfer and leakage are suppressed in antisense cells and demonstrates that connexin 43 plays an important part both in dye transfer in paired cells and dye leakage in single cells.

Properties and regulation of gap junctional hemichannels in the plasma membranes of cultured cells

During the assembly of gap junctions, a hemichannel in the plasma membrane of one cell is thought to align and dock with another in an apposed membrane to form a cell-to-cell channel. We report here on the existence and properties of nonjunctional, plasma membrane connexin43 (Cx43) hemichannels. The opening of the hemichannels was demonstrated by the cellular uptake of 5(6)-carboxyfluorescein from the culture medium when extracellular calcium levels were reduced. Dye uptake exhibited properties similar to those of gap junction channels. For example, using different dyes, the levels of uptake were correlated with molecular size: 5(6)-carboxyfluorescein (approximately 32%), 7-hydroxycoumarin-3-carboxylic acid (approximately 24%), fura-2 (approximately 11%), and fluorescein-dextran (approximately 0.4%). Octanol and heptanol also reduced dye uptake by approximately 50%. Detailed analysis of one clone of Novikoff cells transfected with a Cx43 antisense expression vector revealed a reduction in dye uptake levels according to uptake assays and a corresponding decrease in intercellular dye transfer rates in microinjection experiments. In addition, a more limited decrease in membrane resistance upon reduction of extracellular calcium was detected in electrophysiological studies of antisense transfectants, in contrast to control cells. Studies of dye uptake in HeLa cells also demonstrated a large increase following transfection with Cx43. Together these observations indicate that Cx43 is responsible for the hemichannel function in these cultured cells. Similar dye uptake results were obtained with normal rat kidney (NRK) cells, which express Cx43. Dye uptake can be dramatically inhibited by 12-O-tetradeconylphorbol-13-acetate-activated protein kinase C in these cell systems and by a temperature-sensitive tyrosine protein kinase, pp60v-src in LA25-NRK cells. We conclude that Cx43 hemichannels are found in the plasma membrane, where they are regulated by multiple signaling pathways, and likely represent an important stage in gap junction assembly.

Cancer risks among iron and steel workers in Anshan, China, Part II: Case-control studies of lung and stomach cancer

Nested case-control interview studies of lung cancer (610 incident cases), stomach cancer (292 incident cases), and 959 controls were conducted to follow up leads from a proportional mortality analysis of deaths among male workers in a large integrated iron-steel complex in Anshan, China. For lung cancer, after adjusting for the significant non-occupational risk factors (smoking, other pulmonary disease, family history of lung cancer, and low consumption of fruit or tea), risks were significantly elevated for those employed for 15 or more years in smelting and rolling (OR = 1.5, CI = 1.1-2.2), in the fire-resistant brick factory (OR = 2.9, CI = 1.4-5.9), in general loading (OR = 2.5, CI = 1.0-6.1), and as coke oven workers (OR = 3.4; CI = 1.4-8.5). For stomach cancer, after adjusting for consumption of pickled vegetables, prior gastric diseases, family history of stomach cancer, low intake of fruits and vegetables, and education, risks were significantly elevated for those employed for 15 or more years in ore sintering and transportation (OR = 2.1, CI = 1.0-4.4), in the fire-resistant brick factory (OR = 2.5, CI = 1.1-5.8), in general loading (OR = 3.2, CI = 1.2-8.9), as boilerworkers and cooks (OR = 2.6, CI = 1.2-5.6), and as coke oven workers (OR = 5.4, CI = 1.8-16.0). For both lung and stomach cancers, significant dose-response gradients were observed for exposure to total dust and benzo(a)pyrene, but not for specific chemical components of dust. Overall, long-term steel workers with exposure to workplace pollutants had a 40% increased risk of both lung and stomach cancers. These case-control studies confirm many of the occupational findings reported in the proportionate mortality analysis, and suggest avenues for further work to evaluate the carcinogenicity of individual components of dust.

Lifestyle, environmental pollution and lung cancer in cities of Liaoning in northeastern China

Several studies were conducted in cities of Liaoning Province, one of the areas of China with heavy concentrations of industry, to investigate the effects of life-style factors and environmental pollutants on lung cancer causation. A case-control study involving 1249 lung cancer patients and 1345 population-based controls was conducted in 1985-1988 in Shenyang, the capital of Liaoning. Cigarette smoking was found to be the principal cause of lung cancer in this population, accounting for 55% of the disease in males and 37% in females. There was also a significant increase in lung cancer risk associated with an overall index of indoor air pollution due to coal-burning emission. The population attributable risk (PAR) for indoor air pollution was 13% for males and 17% for females. Risks were significantly increased for workers in the non-ferrous smelter (odds ratio (OR) = 2.6, 95% CI, 1.3-5.1), chemical and drug manufacturing (OR = 3.0, 95% CI, 1.0-8.0), and the glass and pottery industry (OR = 1.6, 95% CI, 1.0-2.5). Studies in the Anshan Iron-Steel Complex showed a significant excess of lung cancer for workers exposed to a variety of dusts. A standardized proportional mortality ratio (SPMR) study of 8887 deaths during 1980-1989 among male workers of the complex indicated a 37% excess risk of lung cancer compared to residents of the city. A nested case-control study was then conducted in that complex. A total of 610 cases of lung cancer diagnosed during 1987-1993 and 959 randomly selected controls from 196 993 active and retired employees of the complex were interviewed. Historical monitoring records for dust and benzo(a)pyrene (B(a)P) were collected from 1956-1992 to calculate cumulative exposure for each person. Results suggested that risks were increased for all occupations in which there was exposure to dusts, with the highest risks seen among coke oven workers (OR = 3.5, 95% CI, 2.0-6.4) and fire-resistant brick makers (OR = 2.9, 95% CI, 1.9-4.4). Significant dose-response patterns between cumulative total dust, cumulative total B(a)P and lung cancer risk were observed. The findings suggest that smoking and environmental pollution combine to account for elevated rates of lung cancer in cities of northeastern China.

Role of inward and delayed rectifier currents in generation of early afterdepolarization in guinea pig ventricular myocytes under K(+)-free or low K+ superfusion

Early afterdepolarization (EAD) was studied in isolated ventricular myocytes of guinea pig heart. Under K(+)-free's treatment, most of the myocytes showed hyperpolarization in resting potential and the duration of action potential was prolonged, eventually leading to the appearance of EAD with the second plateau of -76 +/- 3 mV. TTX (10 microM) and verapamil (10 microM) or normal Tyrode's solution abolished the EAD. The background I-V curve showed inward rectifying with a crossover in the level of -80 to -30 mV and the reversal potential shifted from -80 to -120 mV when normal Tyrode's solution was changed to K(+)-free solution. The changes of I-V relationship of inward current IK) were similar to the background ones except without crossover. The delayed rectifier current (IK) was inhibited significantly under K(+)-free treatment. Low K+ (2.7 mM) superfusion was able to induce EAD in only a few cases (4/15). Adding Cs+ (5.0 mM) into low K+ solution, EAD was induced in almost every case. The background I-V curve was inhibited slightly under low K+ superfusion, but was inhibited significantly with a remarkable crossover under low K+ and Cs+ treatment. The changes of I-V curve IK1 under low K+ or low K+ and Cs+ treatment were similar to the changes of background ones. There were no significant changes in the IK under low K+ superfusion while a remarkable inhibition occurred under low K+ and Cs+ treatment. It was suggested that both IK1 and IK were involved in the induction of EAD under K(+)-free or Cs+ treatment in guinea pig ventricular myocytes.

[Characterization of outward current in mouse ventricular myocytes]

Depolarization-activated, calcium-independent outward currents (Iout) in enzymatically dispersed mouse ventricular myocytes were characterized by whole-cell recording technique. During brief depolarizations to potentials positive to -50 mV, outward K+ currents in these cells rise rapidly to a peak followed by a slower decay to an apparent plateau. The relative peak to plateau amplitudes in a single cell varied as a function of the holding potential (HP) from which the currents were evoked. Reversal potentials for the peak and plateau components were -64.3 +/- 3.9 mV and -53.3 +/- 2.9 mV, respectively (uncorrected for junction potentials). The outward current decay is well described by double exponential fits, whereas the time course of peak Iout decay following a 500 ms prepulse is best fitted by single exponential function, indicating the presence of two distinct components, IKf and IKs, of the outward currents in mouse ventricular cells. Application of 4-AP were accompanied by a marked attenuation of peak Iout and plateau Iout, indicating that both IKf and IKs display similar sensitivities to 4-AP. The steady state inactivation of IKf is found incomplete within the test potential range (-80 - +30 mV) owing probably to the fact that the APD of mouse myocardium is too short.

Comparison of early afterdepolarization induced by cesium chloride in mouse atrial and ventricular fibers

AIM

To study the similarities and the differences in the induction of early afterdepolarization (EAD) by CsCl, a blocker of potassium channels, between mouse atrial and ventricular fibers.

METHODS

Papillary muscle from left ventricle or a small piece of right atrium of Swiss Albino mouse was isolated. Transmembrane action potential (AP) and EAD were recorded using the conventional microelectrode method.

RESULTS

CsCl induced EAD directly in the mouse atrial and ventricular fibers on the basis of elongation of action potential duration (APD). In both preparations EAD appeared after 5-15 min exposure to CsCl and the take-off potentials (TOP) were in the same range (-30 to -60 mV). But the inducing concentration in ventricular fibers (3 mmol.L-1) was lower than that in atrial fibers (5 mmol.L-1), and most of the EAD induced in atrium belonged to the triggered burst type (6/9) which demonstrated the property of cycle length (CL)-dependence while the EAD occurred in ventricle mainly belonged to the second plateau type (14/17) which showed no definite relation with the CL.

CONCLUSION

Low concentration of CsCl induced EAD more easily in mouse ventricular fibers than in atrial fibers, and the types of EAD were also different from each other. These suggested that there might be some differences in potassium channels between mouse atrial and ventricular fibers.

Intracellular lucifer yellow leakage from Novikoff cells in the presence of ATP or low extracellular Ca: evidence for hemi-gap junction channels

Lucifer Yellow was microinjected into Novikoff hepatoma cells and leakage was investigated under treatment with ATP (5 mM) and EGTA (5 mM) in the culture medium. In control conditions, there was no leakage in single or paired cells, except a few cases which showed very slow leakage (defined as slope < -0.0007/sec). Slow leakage rate (slope > -0.0008 but < -0.009/sec) and quick leakage rate (slope > -0.01) of intracellular dye were not seen. Dye transfer between cell pairs after Lucifer Yellow was injected into one cell was divided into two groups: quick transfer rates (4 cases, slope = -0.151 +0.0032) and slow transfer rates (15 cases, slope = -0.041 +0.0018). Under ATP treatment the intracellular dye leakage was observed in single cells (16 of 31 cases) and in cell pairs (20 of 57 cases). Extracellular low Ca2+ (EGTA treatment) enhanced the dye leakage much more: 30 of 40 cases in single cells and 21 of 36 cases in cell pairs. The leakage rates of intracellular dye under these treatments were similar to the transfer rates of the dye between cell pairs with quick and slow rates. It is suggested that the dye leakage from Novikoff cells under treatment with ATP or low [Ca2+]o shares the same mechanism as dye transfer through gap junctions, suggesting that the hemichannels in the plasma membrane can be opened under certain conditions.

[Progress in the study of potassium channels in cardiomyocytes]

The application of molecular biology and the development of patch clamp techniques led to a dramatic progress in the study of diversified and complicated K+ channels in the cardiomyocytes. Molecular studies suggested that all K+ channels are composed of four subunits encoded by genes from a big K+ channel gene family. The mechanisms of K+ channel inactivation include N-, C- and P-types of inactivation. S5-S6 linker was postulated to form the pore of K+ channels by site-directed mutagenesis. Though the molecular structures among K+ channels are very close, a wide range of their functional properties has been observed. The channel conductances, the characterizations of activation, inactivation, rectification and external K+ sensitivity, the agonists, antagonists and modulators of eight K+ channels found in cardiomyocytes up to now are different with each other.

Characteristics of early afterdepolarization in mouse atrial fibers

Early afterdepolarization (EAD) in mouse atrial fibers was investigated under the treatment with aconitine, 3.0 mmol/L K+, quinidine, ryanodine or Bay k 8644. All of these EADs possessed the following common characteristics: all the parameters of EAD showed cycle length-dependence; take-off potential of the first triggered burst played an important role in the generation of the other parameters; hyperpolarization of the triggered brust enhanced the end of EAD; and the second plateau response might be used as an indicator of the capability of EAD generation of myocardiac cell. All those EADs were inhibited or abolished by nifedipine, tetrodotoxin or lidocaine. Potassium channel activators, lemakalim, thalium ion, acetyl-choline or high potassium could also inhibit or abolish the EADs. It is suggested that the EADs induced by different agents may base on a common mechanism: all currents contributing to the plateau phase of the action potential play an important role in the generation of EAD.

A reevaluation of the critical membrane potential of the effective refractory period in guinea pig ventricular fibres

The traditional critical membrane potential (CMP), -55(-)-60 mV, which corresponds to effective refractory period (ERP), was anew investigated in guinea pig ventricular muscle fibres. The electrical and contractile responses to the stimulus during repolarization of action potential (AP), particularly from +10 to -60 mV, were observed. One third of 35 tested cells displayed testing action potential (TAP) and local response at > or = -54 mV when they were stimulated by testing pulses in 37 degrees C normal Tyrode's solution. Potential level of TAP which occurred earliest was at -30 mV and that of local response which appeared earliest was at 0 mV during repolarization among 95 systematic tests. Most of the TAPs belonged to the slow response potential type. The ratio of TAP evoked at > or = -54 mV initial membrane potential (IMP) was as high as 86% when the experiment was carried out in 37 degrees C 1.5 mmol KC1/L Tyrode's solution. In view of distribution of IMPs of TAPs, the CMP of ERP in guinea pig ventricular muscle fibres was more positive than traditional CMP measured by Hoffman et al. in dog, sheep Purkinje fibres and had a quite changeable range. The CMP of every cell in ventricular muscle was not all the same, and their CMPs approximated to normal distribution. There was no sharp line separating ERP from relative refractory period in myocardium. Higher temperature and low [K]0 were the important factors elevating CMP of ERP.

Effects of pinacidil and acetylcholine on early afterdepolarization of atrial fibers in mouse heart

The effects of pinacidil and acetylcholine (Ach) on action potential (AP) and early afterdepolarization (EAD) were investigated in mouse atrial fibers. Under treatment with pinacidil the AP and EAD were affected only with the concentration of 8 x 10(-5) M, which inhibited EAD but did not affect AP except for only a minor reduction of action potential duration (APD). After withdrawal of pinacidil, the inhibitory effect of EAD was enhanced. Under treatment with Ach (2 x 10(-7) M), AP was not changed except the APD, which was significantly reduced, and the EAD was completely abolished. Withdrawal of Ach produced a rebound increase in APD and led to induction of EAD or promoted EAD to more extensive level such as appearance of long second plateau. Atropine (1 x 10(-7) M) abolished the rebound effect caused by withdrawal of Ach. The mechanism of EAD generation induced by removing Ach is discussed.

Generation of early afterdepolarization in mouse ventricular fibers at long cycle length

Early afterdepolarization (EAD) was studied in ventricular fibers of mouse heart. EAD could be occasionally induced under long cycle length of superfusion with Tyrode's solution (containing 3.0 or 5.0 mM KCl) at long cycle length. Three types of EAD were found: a second plateau with a prominence, a single triggered burst and a train of triggered bursts. Take-off potential of the first triggered burst or of the prominence varied from -40 to -60 mV. The triggered bursts in the third type often stopped at -35 to -45 mV level forming a very long second plateau before it completely repolarized. Changing abruptly from a long cycle length to a short one lead to a transient EAD induction. It is suggested that EAD in ventricular fiber in mouse heart shared the characteristics of that in atrial fibers, although it was very difficult to induce and was not very reproducible.