Added value of spectral computed tomography quantitative parameters for differentiating tuberculosis-associated fibrosing mediastinitis from endobronchial lung cancer: initial results

OBJECTIVE

The objective of this study was to explore the added value of spectral computed tomography (CT) parameters to conventional CT features for differentiating tuberculosis-associated fibrosing mediastinitis (TB-associated FM) from endobronchial lung cancer (EBLC).

METHODS

Chest spectral CT enhancement images from 109 patients with atelectasis were analyzed retrospectively. These patients were divided into two distinct categories: the TB-associated FM group (n = 77) and the EBLC group (n = 32), based on bronchoscopy and/or pathological findings. The selection of spectrum parameters was optimized with the least absolute shrinkage and selection operator regression analysis. The relationship between the spectrum parameters and conventional parameters was explored using Pearson's correlation. Multivariate logistic regression analysis was used to build spectrum model. The spectrum parameters in the spectrum model were replaced with their corresponding conventional parameters to build the conventional model. Diagnostic performances were evaluated using receiver operating characteristic curve analyses.

RESULTS

There was a moderate correlation between the parameters ㏒(L-AEFNIC) - ㏒(L-AEFC) (r= 0.419; p< 0.0001), ㏒(O-AEF40KeV) - ㏒(O-AEFC) (r= 0.475; p< 0.0001), [L-A-hydroxyapatite {HAP}(I)] - (L-U-CT) (r= 0.604; p< 0.0001), {arterial enhancement fraction (AEF) derived from normalized iodine concentration (NIC) of lymph node (L-AEFNIC), AEF derived from CT40KeV of bronchial obstruction (O-AEF40KeV), arterial-phase Hydroxyapatite (Iodine) concentration of lymph node [L-A-HAP(I)], AEF derived from conventional CT (AEFC), unenhanced CT value (U-CT)}. Spectrum model could improve diagnostic performances compared to conventional model (area under curve: 0.965 vs 0.916, p= 0.038).

CONCLUSION

There was a moderate correlation between spectrum parameters and conventional parameters. Integrating conventional CT features with spectrum parameters could further improve the ability in differentiating TB-associated FM from EBLC.

Exploration of a novel prognostic model based on nomogram in non-small cell lung cancer patients with distant organ metastasis: implications for immunotherapy

Background

Evidence for the effects of immunotherapy in non-small cell lung cancer (NSCLC) patients with distant organ metastasis is insufficient, and the predictive efficacy of established markers in tissue and blood is elusive. Our study aimed to determine the prognostic factors and develop a survival prognosis model for these patients.

Methods

A total of 100 advanced NSCLC patients with distant organ metastases, who received single or combination immune checkpoint inhibitors (ICIs) in Xijing Hospital between June 2018 and June 2021, were enrolled for retrospective analysis. The major clinicopathological parameters were collected, and associated survival outcomes were followed up by telephone or inpatient follow-up for nearly 3 years to assess prognoses. The survival prognosis model was established based on univariate and multivariate Cox regression analyses to determine the candidate prognostic factors.

Results

From the start of immunotherapy to the last follow-up, 77 patients progressed and 42 patients died, with a median follow-up of 18 months [95% confidence interval (CI): 15-19.9]. The median progression-free survival (PFS) and overall survival (OS) were 8 months (95% CI: 5.6-10.4) and 21 months (95% CI: 8.9-33.1), respectively. Multivariate Cox proportional hazards analysis showed Eastern Cooperative Oncology Group performance status (ECOG PS), body mass index (BMI), age-adjusted Charlson comorbidity index (ACCI), lactate dehydrogenase (LDH), and absolute neutrophil count (ANC) were correlated significantly with OS. Based on these five predictive factors, a nomogram and corresponding dynamic web page were constructed with a concordance index (C-index) of 0.81 and a 95% CI of 0.778-0.842. Additionally, the calibration plot and time-receiver operating characteristic (ROC) curve validated the precision of the model at 6-, 12-, and 18-month area under the curves (AUCs) reached 0.934, 0.829, and 0.846, respectively. According to the critical point of the model, patients were further divided into a high-risk total point score (TPS) >258, middle-risk (204< TPS ≤258), and low-risk group (TPS ≤204), and significant OS differences were observed among the three subgroups (median OS: 4.8 vs. 13.0 vs. 32.9 months).

Conclusions

A feasible and practical model based on clinical characteristics has been developed to predict the prognosis of NSCLC patients with distant organ metastasis undergoing immunotherapy.

Alterations of lower respiratory tract microbiome and short-chain fatty acids in different segments in lung cancer: a multiomics analysis

Introduction

The lower respiratory tract microbiome is widely studied to pinpoint microbial dysbiosis of diversity or abundance that is linked to a number of chronic respiratory illnesses. However, it is vital to clarify how the microbiome, through the release of microbial metabolites, impacts lung health and oncogenesis.

Methods

In order to discover the powerful correlations between microbial metabolites and disease, we collected, under electronic bronchoscopy examinations, samples of paired bronchoalveolar lavage fluids (BALFs) from tumor-burden lung segments and ipsilateral non-tumor sites from 28 lung cancer participants, further performing metagenomic sequencing, short-chain fatty acid (SCFA) metabolomics, and multiomics analysis to uncover the potential correlations of the microbiome and SCFAs in lung cancer.

Results

In comparison to BALFs from normal lung segments of the same participant, those from lung cancer burden lung segments had slightly decreased microbial diversity in the lower respiratory tract. With 18 differentially prevalent microbial species, including the well-known carcinogens Campylobacter jejuni and Nesseria polysaccharea, the relative species abundance in the lower respiratory tract microbiome did not significantly differ between the two groups. Additionally, a collection of commonly recognized probiotic metabolites called short-chain fatty acids showed little significance in either group independently but revealed a strong predictive value when using an integrated model by machine learning. Multiomics also discovered particular species related to SCFAs, showing a positive correlation with Brachyspira hydrosenteriae and a negative one with Pseudomonas at the genus level, despite limited detection in lower airways. Of note, these distinct microbiota and metabolites corresponded with clinical traits that still required confirmation.

Conclusions

Further analysis of metagenome functional capacity revealed that genes encoding environmental information processing and metabolism pathways were enriched in the lower respiratory tract metagenomes of lung cancer patients, further supporting the oncogenesis function of various microbial species by different metabolites. These findings point to a potent relationship between particular components of the integrated microbiota-metabolites network and lung cancer, with implications for screening and diagnosis in clinical settings.

Correlation of pericoronary adipose tissue CT attenuation values of plaques and periplaques with plaque characteristics

AIM

To investigate the relationship between different plaque characteristics and pericoronary adipose tissue (PCAT) computed tomography (CT) attenuation values for plaques and periplaques.

MATERIALS AND METHODS

The data from 188 eligible patients with stable coronary heart disease (280 lesions) who underwent coronary CT angiography between March 2021 and November 2021 were collected retrospectively. All PCAT CT attenuation values of plaques and periplaques (the area within 5 and 10 mm proximal and distal to the plaque) were calculated, and multiple linear regression was used to assess their correlation with different plaque characteristics.

RESULTS

PCAT CT attenuation of plaques and periplaques was higher in non-calcified plaques (-73.38 ± 10.41 HU, -76.77 ± 10.86 HU, 79.33 ± 11.13 HU, -75.67 ± 11.24 HU, -78.63 ± 12.09 HU) and mixed plaques (-76.83 ± 8.11 HU, -79 [-85, -68.5] HU, -78.55 ± 11 HU, -78.76 ± 9.9 HU, -78.79 ± 11.06 HU) than in calcified plaques (-86.96 ± 10 HU, -84 [-92, -76] HU, -84.14 ± 11.08 HU, -84.91 ± 11.41 HU, -84.59 ± 11.69 HU; all p<0.05) and higher in distal segment plaques than in proximal segment plaques (all p<0.05). Plaque PCAT CT attenuation was lower in plaques with minimal stenosis than in plaques with mild or moderate stenosis (p<0.05). The significant determinants of PCAT CT attenuation values of plaques and periplaques were non-calcified plaques, mixed plaques, and plaques located in the distal segment (all p<0.05).

CONCLUSIONS

PCAT CT attenuation values in both plaques and periplaques were related to plaque type and location.

[Establishment and validation of a nomogram for predicting prognosis of gastric neuroendocrine neoplasms based on data from 490 cases in a single center]

OBJECTIVE

To develop and validate a nomogram for predicting outcomes of patients with gastric neuroendocrine neoplasms (G-NENs).

METHODS

We retrospectively collected the clinical data from 490 patients with the diagnosis of G-NEN at our medical center from 2000 to 2021. Log-rank test was used to analyze the overall survival (OS) of the patients. The independent risk factors affecting the prognosis of G-NEN were identified by Cox regression analysis to construct the prognostic nomogram, whose performance was evaluated using the C-index, receiver-operating characteristic (ROC) curve, area under the ROC curve (AUC), calibration curve, DCA, and AUDC.

RESULTS

Among the 490 G-NEN patients (mean age of 58.6±10.92 years, including 346 male and 144 female patients), 130 (26.5%) had NET G1, 54 (11.0%) had NET G2, 206 (42.0%) had NEC, and 100 (20.5%) had MiNEN. None of the patients had NET G3. The numbers of patients in stage Ⅰ-Ⅳ were 222 (45.3%), 75 (15.3%), 130 (26.5%), and 63 (12.9%), respectively. Univariate and multivariate analyses identified age, pathological grade, tumor location, depth of invasion, lymph node metastasis, distant metastasis, and F-NLR as independent risk factors affecting the survival of the patients (P < 0.05). The C-index of the prognostic nomogram was 0.829 (95% CI: 0.800-0.858), and its AUC for predicting 1-, 3- and 5-year OS were 0.883, 0.895 and 0.944, respectively. The calibration curve confirmed a good consistency between the model prediction results and the actual observations. For predicting 1-year, 3-year and 5-year OS, the TNM staging system and the nomogram had AUC of 0.033 vs 0.0218, 0.191 vs 0.148, and 0.248 vs 0.197, respectively, suggesting higher net benefit and better clinical utility of the nomogram.

CONCLUSION

The prognostic nomogram established in this study has good predictive performance and clinical value to facilitate prognostic evaluation of individual patients with G-NEN.

The debatable role of immune checkpoint blockade therapy in lung adenocarcinoma-oriented liver metastatic malignant lesions

BACKGROUND

The use of anti-PD-1 or PD-L1 inhibitors in combination with other anti-cancer agents was a priority for treating advanced non-small cell lung cancer (NSCLC) patients with considerable PD-L1 expression. However, studies seldom show the progression of liver metastases after using immune checkpoint inhibitors (ICIs).

METHODS

Data were obtained from the Department of Pulmonary and Critical Care of Medicine, the First Affiliated Hospital of the Air Force Military Medical University. In the present study, we analyzed five non-small cell lung cancer (NSCLC) patients who had liver metastases after they were treated with pembrolizumab between 2019 and 2021. All of them had both stable primary lesions and liver progression with pembrolizumab intervention. Blood laboratory tests and imaging examinations were performed regularly during the treatment to assess the tumor responses of patients.

RESULTS

All patients displayed reduction or stability in the initial lesions as a result, but they also experienced the emergence of metastatic liver locations, which were regularly detected throughout immunotherapy. Additionally, the appearance of liver metastasis weakened their liver function gradually with the escalation of carcinoembryonic antigen, regarded as a predictor for evaluating the progression of tumors. These individuals were highly distinctive with hyper-progressive diseases associated with immunotherapy. We drew individualized intervention schemes for metastatic lesions in each patient and found that their life expectancy shared no significance given the restricting subjected population.

CONCLUSIONS

Our study indicated a clinical phenomenon after using immune checkpoint inhibitors and presented a necessity for implementing large scales clinical studies to manage NSCLC-oriented liver metastasis.

Development of Diagnosis Model for Early Lung Nodules Based on a Seven Autoantibodies Panel and Imaging Features

Background

There is increasing incidence of pulmonary nodules due to the promotion and popularization of low-dose computed tomography (LDCT) screening for potential populations with suspected lung cancer. However, a high rate of false-positive and concern of radiation-related cancer risk of repeated CT scanning remains a major obstacle to its wide application. Here, we aimed to investigate the clinical value of a non-invasive and simple test, named the seven autoantibodies (7-AABs) assay (P53, PGP9.5, SOX2, GAGE7, GUB4-5, MAGEA1, and CAGE), in distinguishing malignant pulmonary diseases from benign ones in routine clinical practice, and construct a neural network diagnostic model with the development of machine learning methods.

Method

A total of 933 patients with lung diseases and 744 with lung nodules were identified. The serum levels of the 7-AABs were tested by an enzyme-linked Immunosorbent assay (ELISA). The primary goal was to assess the sensitivity and specificity of the 7-AABs panel in the detection of lung cancer. ROC curves were used to estimate the diagnosis potential of the 7-AABs in different groups. Next, we constructed a machine learning model based on the 7-AABs and imaging features to evaluate the diagnostic efficacy in lung nodules.

Results

The serum levels of all 7-AABs in the malignant lung diseases group were significantly higher than that in the benign group. The sensitivity and specificity of the 7-AABs panel test were 60.7% and 81.5% in the whole group, and 59.7% and 81.1% in cases with early lung nodules. Comparing to the 7-AABs panel test alone, the neural network model improved the AUC from 0.748 to 0.96 in patients with pulmonary nodules.

Conclusion

The 7-AABs panel may be a promising method for early detection of lung cancer, and we constructed a new diagnostic model with better efficiency to distinguish malignant lung nodules from benign nodules which could be used in clinical practice.

The Clinical Prediction Value of the Ubiquitination Model Reflecting the Immune Traits in LUAD

Background

Increasing evidence shows that the ubiquitin–proteasome system has a crucial impact on lung adenocarcinoma. However, reliable prognostic signatures based on ubiquitination and immune traits have not yet been established.

Methods

Bioinformatics was performed to analyze the characteristic of ubiquitination in lung adenocarcinoma. Principal component analysis was employed to identify the difference between lung adenocarcinoma and adjacent tissue. The ubiquitin prognostic risk model was constructed by multivariate Cox regression and least absolute shrinkage and selection operator regression based on the public database The Cancer Genome Atlas, with evaluation of the time-dependent receiver operating characteristic curve. A variety of algorithms was used to analyze the immune traits of model stratification. Meanwhile, the drug response sensitivity for subgroups was predicted by the “pRRophetic” package based on the database of the Cancer Genome Project.

Results

The expression of ubiquitin genes was different in the tumor and in the adjacent tissue. The ubiquitin model was superior to the clinical indexes, and four validation datasets verified the prognostic effect. Additionally, the stratification of the model reflected distinct immune landscapes and mutation traits. The low-risk group was infiltrating plenty of immune cells and highly expressed major histocompatibility complex and immune genes, which illustrated that these patients could benefit from immune treatment. The high-risk group showed higher mutation and tumor mutation burden. Integrating the tumor mutation burden and the immune score revealed the patient’s discrepancy between survival and drug response. Finally, we discovered that the drug targeting ubiquitin and proteasome would be a beneficial prospective treatment for lung adenocarcinoma.

Conclusion

The ubiquitin trait could reflect the prognosis of lung adenocarcinoma, and it might shed light on the development of novel ubiquitin biomarkers and targeted therapy for lung adenocarcinoma.

Assessment of Financial Toxicity Among Patients With Advanced Lung Cancer in Western China

Background: Lung cancer is the leading source of cancer-caused disability-adjusted life years. Medical cost burden impacts the well-being of patients through reducing income, cutting daily expenses, curtailing leisure activities, and depleting exhausting savings. The COmprehensive Score for Financial Toxicity (COST) was created and validated by De Souza and colleagues. Our study intends to measure the financial burdens of cancer therapy and investigate the link between financial toxicity and health-related quality of life (HRQoL) in an advanced lung cancer population. Methods: Patients aged ≥ 18 years with confirmed stage III to IV lung cancer were eligible. The COST questionnaire verified by de Souza et al. was used to identify financial toxicity. Multivariable linear regression analysis with log transformation univariate analysis and Pearson correlations were used to perform the analysis. Results: The majority of the patients (90.8%, n = 138/152) had an annual income of $50,000 ($7,775). The cohort's insurance situation was as follows: 64.5% of the cohort had social insurance, 20.4% had commercial insurance, and 22.0% had both. Patients who were younger age (50-59, P < 0.001), employed but on sick leave, and had lower income reported increased levels of financial toxicity (P < 0.05). The risk factors for high financial toxicity: (i) younger age (50-59), (ii) <1 month of savings, and (iii) being employed but on sick leave. Increased financial toxicity is moderately correlated with a decrease in QoL. Conclusion: Poorer psychological status and specific demographics are linked to increased financial toxicity (lower COST). Financial toxicity has a modest relationship with HRQoL and may have a clear link with HRQoL measurements.

P–138 When is low quality really low? Should we transfer low-grade blastocysts?

Study question

What is the live birth rate after single, low-grade blastocyst (LGB) transfer?

Summary answer

The live birth rate for LGBs is 28%, ranging between 15–31% for the different inner cell mass (ICM) and trophectoderm (TE) subgroups of LGBs.

What is known already

Live birth rates following LGB transfer are varied and have been reported to be in the range of 5–39%. However, these estimates are inaccurate as studies investigating live birth rates following LGB transfer are inherently limited by sample size (n = 10–440 for LGB transfers) due to LGBs being ranked last for transfer. Further, these studies are heterogenous with varied LGB definitions and design. Collating LGB live birth data from multiple clinics is warranted to obtain sufficient numbers of LGB transfers to establish reliable live birth rates, and to allow for delineation of different LGB subgroups, including blastocyst age and female age.

Study design, size, duration

We performed a multicentre, multinational retrospective cohort study in 9 IVF centres in China and New Zealand from 2012 to 2019. We studied the outcome of 6966 single blastocyst transfer cycles on days 5–7 (fresh and frozen) according to blastocyst grade, including 875 transfers from LGBs (&lt;3bb, this being the threshold typically applied to LGB studies). Blastocysts with expansion stage 1 or 2 (early blastocysts) were excluded.

Participants/materials, setting, methods

The main outcome measured was live birth rate. Blastocysts were grouped according to quality grade: good-grade blastocysts (GGBs; n = 3849, aa, ab and ba), moderate-grade blastocysts (MGBs; n = 2242, bb) and LGBs (n = 875, ac, ca, bc, cb and cc) and live birth rates compared using the Pearson Chi-squared test. A logistic regression analysis explored the relationship between blastocyst grade and live birth after adjustment for the confounders: clinic, female age, expansion stage, and blastocyst age.

Main results and the role of chance

The live birth rates for GGBs, MGBs and LGBs were 45%, 36% and 28% respectively (p &lt; 0.0001). Within the LGB group, the highest live birth rates were for grade c TE (30%) and the lowest were for grade c ICM (19%). The lowest combined grade (cc) maintained a 15% live birth rate (n = 7/48). After accounting for confounding factors, including female age and blastocyst characteristics, the odds of live birth were 2.33 (95% CI = 1.88–2.89) for GGBs compared to LGBs and 1.56 (95% CI = 1.28–1.92) for MGBs compared to LGBs following fresh and frozen blastocyst transfers (p &lt; 0.0001, odds ratios confirmed in exclusively frozen blastocyst transfer cycles). When stratified by individual ICM and TE grade, the odds of live birth according to ICM grade were 1.31 (a versus b; 95% CI = 1.15–1.48), 2.82 (a versus c; 95% CI = 1.91–4.18) and 2.16 (b versus c; 95% CI = 1.48–3.16; all p &lt; 0.0001). The odds of live birth according to TE grade were 1.33 (a versus b; 95% CI = 1.17–1.50, p &lt; 0.0001), 1.85 (a versus c; 95% CI = 1.45–2.34, p &lt; 0.0001) and 1.39 (b versus c; 95% CI = 1.12–1.73, p = 0.0024).

Limitations, reasons for caution

Despite the large multicentre design of the study, analyses of transfers occurring within the smallest subsets of the LGB group were limited by sample size. The study was not randomised and had a retrospective character.

Wider implications of the findings: LGBs maintain satisfactory live birth rates (averaging 28%) in the general IVF population. Even those in the lowest grading tier maintain modest live birth rates (15%; cc). It is recommended that LGBs not be universally discarded, and instead considered for subsequent frozen embryo transfer to maximize cumulative live birth rates.

Trial registration number

Not applicable

[Holistic view of surgery based on membrane anatomy for gastrointestinal tumor]

The mesentery is a continuous unity and the operation of digestive carcinoma is the process of mesenteric resection. This paper attempts to simplify the formation process of all kinds of fusion fascia in the process of digestive tract embryogenesis, and to illuminate the continuity of fusion fascia with a holistic concept. This is helpful for beginners to reversely dissect the fusion fascia and maintain the correct surgical plane during operation, and to achieve the purpose of complete mesenteric resection.

PHB2 promotes tumorigenesis via RACK1 in non-small cell lung cancer

Background: Lung cancer has the highest mortality rate among cancers worldwide, with non-small cell lung cancer (NSCLC) the most common type. Increasing evidence shows that PHB2 is highly expressed in other cancer types; however, the effects of PHB2 in NSCLC are currently poorly understood.

Method: PHB2 expression and its clinical relevance in NSCLC tumor tissues were analyzed using a tissue microarray. The biological role of PHB2 in NSCLC was investigated in vitro and in vivo using immunohistochemistry and immunofluorescence staining, gene expression knockdown and overexpression, cell proliferation assay, flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, wound healing assay, Transwell assay, western blot analysis, qRT-PCR, coimmunoprecipitation, and mass spectrometry analysis.

Results: Our major finding is that PHB2 facilitates tumorigenesis in NSCLC by interacting with and stabilizing RACK1, which further induces activation of downstream tumor-promoting effectors. PHB2 was found to be overexpressed in NSCLC tumor tissues, and its expression was correlated with clinicopathological features. Furthermore, PHB2 overexpression promoted proliferation, migration, and invasion, whereas PHB2 knockdown enhanced apoptosis in NSCLC cells. The stimulating effect of PHB2 on tumorigenesis was also verified in vivo. In addition, PHB2 interacted with RACK1 and increased its expression through posttranslational modification, which further induced activation of the Akt and FAK pathways.

Conclusions: Our results reveal the effects of PHB2 on tumorigenesis and its regulation of RACK1 and RACK1-associated proteins and downstream signaling in NSCLC. We believe that the crosstalk between PHB2 and RACK1 provides us with a great opportunity to design and develop novel therapeutic strategies for NSCLC.

Long-term decomposed straw return positively affects the soil microbial community

AIMS

In order to understand the response of soil microbial communities to the long-term of decomposed straw return, the modifications of soil microbial community structure and composition induced by more than 10 years of fresh and decomposed straw return was investigated and the key environmental factors were analysed.

METHODS AND RESULTS

Phospholipid fatty acid analysis and high-through sequencing technique were applied to analyse the structure and composition of the soil microbial communities. Compared with fresh straw, returning decomposed straw increased the relative abundance of bacteria and fungi by 1·9 and 7·7% at a rate of ~3750 kg ha^-1 , and increased by 23·1 and 5·7%, at a rate of ~7500 kg ha^-1 respectively. The relative abundance of the bacteria related to soil nitrification increased, but the ones related to soil denitrification decreased with decomposed straw return, which led to higher total nitrogen contents in soils. Moreover, returning decomposed straw reduced pathogenic fungal populations (genus of Alternara), which had significantly positive correlation with soil electric conductivity. It indicated that the long-term of decomposed straw return might have lower risk of soil-borne disease mainly for the reasonable soil salinity.

CONCLUSIONS

Long-term of decomposed straw return could provide suitable nutrient and salinity for healthier development of soil microbial community, both in abundance and structure, compared with fresh straw return.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of the study helps to better understand how the microbial community modifications induced by decomposed straw return benefit on soil health. The obtained key factors impacting soil microbial community variations is meaningful in soil health management under conditions of straw return.

Effect of local scrotal heating on the expression of tight junction-associated molecule Occludin in boar testes

The aim of this study was to determine whether local scrotal heating (42°C, for 1 hr) had an effect on the expression of tight junction (TJ)-associated molecule Occludin in boar testes. Adult boars (Landrace, n = 6) were used and randomly divided into two groups (n = 3 each). Three boars were given local scrotal exposure to 42°C for approximately 1 h with a home-made electric blanket of controlled temperature as local scrotal heating group, the other three boars received no heat treatment and were left at standard room temperature as control group. After 6 hr, all boars were castrated and the testes were harvested. qRT-PCR, Western blotting and immunohistochemistry were used to explore the expression and localization of Occludin. qRT-PCR and Western blotting showed that the protein and mRNA levels of Occludin significantly decreased in local scrotal heating group as compared to the control. Furthermore, immunoreactivity staining of Occludin was localized at the sites of the blood-testis barrier (BTB) and formed an almost consecutive and strong immunoreactivity strand in the control, while Occludin was limited to Sertoli cells (SCs) and no obvious immunoreactivity strand was present in local scrotal heating group. These data indicated that local scrotal heating decreased the expression of TJ-associated molecule Occludin, which may be involved in heat-induced spermatogenesis damage.

[Application of frailty index for comprehensive geriatric assessment in the elderly in China]

OBJECTIVE

To discuss the suitability of frailty index for comprehensive geriatric assessment(FI-CGA)in the elderly in China, and evaluate the application of FI-CGA in China.

METHODS

A comprehensive geriatric assessment was conducted among 118 old adults receiving health examination, and frailty index was calculated. Clinical frailty scale(CFS)was also used to evaluate the frail status of the old adults. The correlation between FI-CGA value and CFS level of the old adults was analyzed.

RESULTS

The mean value of FI-CGA was 0.19 ± 0.07, and the average level of CFS was 3.11 ± 1.46. Women had higher mean value of FI-CGA and higher CFS level than men(FI-CGA= 0.20 ± 0.02 for women, 0.19 ± 0.07 for men; CFS =3.40 ± 0.55 for women, 3.10 ± 1.48 for men), but the differences had no significance(t=0.270, 0.452, P=0.788, 0.652). The FI-CGA value and CFS level increased with age(F=10.437, 5.651, P=0.000, 0.001); and there was a positive correlation between FI-CGA value and CFS level(r=0.615, P=0.000).

CONCLUSION

FI-CGA is an effective model for the quantitative evaluation of the frail status of the elderly, and can be used in the clinical practice of geriatric medicine.

ZnRF3 induces apoptosis of gastric cancer cells by antagonizing Wnt and Hedgehog signaling

AIM

The aim of this paper was to investigate the function an importance of E3-ubiquitin ligase ZnRF3 in the progression of cancer cell growth.

METHODS

A total of 58 patients (44 males and 14 females) were enrolled in the study and their gastric tumors were removed surgically and were staged by the TNM approach. Among these patients, 43 patients died and 15 survived at the time of this study. The tumors and the paracancerous tissues were examined by immunohostochemistry for the expression of ZnRF3. We assessed the expression of ZnRF3 in gastric tumors and paracancerous tissues from our patients and related this to patient survival.

RESULTS

A large proportion of malignant cancers of the stomach are gastric adenocarcinoma type. In spite of many studies, the molecular basis for this cancer is still unclear. Deregulated cell proliferative signaling via Wnt/β-catenin and Hedgehog pathways is considered important in the pathogenesis of many cancers including the gastric cancer. Recent studies identified ZnRF3 protein, which is a E3-ubiquitin ligase and which is either deleted or mutated in cancers, to inhibit Wnt signaling. However, the significance of ZnRF3 in the control of gastric cancer and whether it also regulates Hedgehog signaling pathway, is not known. ZnRF3 expression was much higher in tumors from aged patients. Male patients showed higher mortality than the females. Mechanistic studies using normal gastric cells (GES1) and gastric cancer cells (MGC-803) infected with either AdZnRF3 or AdGFP viral vectors, revealed that ZnRF3 overexpression causes significantly more apoptosis and lowered proliferation of cancer cells. ZnRF3 overexpression led to greatly reduced levels of Lgr5, a component of Wnt signaling and also Gli1, a component of Hedgehog signaling. Thus, ZnRF3 negatively influences both the Wnt and Hedgehog proliferative pathways and probably this way it negatively regulates cancer progression. These results suggest the importance of normal ZnRF3 function in checking the progression of cancer cell growth and indicate that a lack of this protein can lead to poorer clinical outcomes for gastric cancer patients.

CONCLUSION

We observed a clear relationship between ZnRF3 expression in paracancerous tissue and tumor size.

The Effects of Epidural Anaesthesia and Analgesia on Natural Killer Cell Cytotoxicity and Cytokine Response in Patients with Epithelial Ovarian Cancer Undergoing Radical Resection

Objective:

Epidural anaesthesia appears to promote antitumourigenic activity in patients with malignant disease who are undergoing surgery. This study investigated immune function in women with epithelial ovarian cancer undergoing radical resection with either general anaesthesia alone or in combination with epidural anaesthesia.

Methods:

Patients ( n = 61) were randomized to receive either combined general/epidural anaesthesia (study group) or general anaesthesia alone (control group). Natural killer cell cytotoxicity (NKCC) and serum concentrations of four cytokines (interleukin [IL]-1β, -8 and -10 and interferon [IFN]-γ) were measured before anaesthesia ( Tpre) and 4h after skinincision ( T4 h) in both groups.

Results:

In both groups, concentrations of protumourigenic cytokines (IL-1β and IL-8) were significantly higher at T4 h than at Tpre, while concentrations of antitumourigenic cytokines (IL-10 and IFN-γ) and NKCC were significantly lower at T4 h. The study group had significantly higher NKCC, IL-10 and IFN-γ levels and lower IL-1β and IL-8 levels at TT h compared with the control group.

Conclusion:

Combined general/epidural anaesthesia appeared to promote antitumourigenic NKCC and cytokine responses.

Association of COX-2 expression with corresponding active and chronic inflammatory reactions in Barrett's metaplasia and progression to cancer

AIMS

Risk reduction for Barrett's cancer in individuals taking non-steroidal anti-inflammatory drugs has been reported. Cyclooxygenase (COX)-2, one of the inhibited enzymes, is putatively involved in Barrett's cancer pathogenesis. The aim of this study was to examine a possible association between COX-2 protein expression and the development and progression of the Barrett's metaplasia-dysplasia-carcinoma sequence and the type and degree of associated inflammatory reaction.

METHODS AND RESULTS

Squamous epithelium, metaplastic, low-grade, high-grade dysplastic lesions and tumour tissue of 49 resection specimens from patients with Barrett's adenocarcinoma were immunohistochemically analysed. Active and chronic inflammatory reactions were classified according to the Updated Sydney System. Within the Barrett's sequence, a significant progressive increase in COX-2 expression was identified (P < 0.0001). The most significant differences were detected between squamous epithelium and Barrett's metaplasia (P < 0.001) and from low- to high-grade dysplasia (P < 0.0001). Active and chronic inflammation were significantly different between squamous epithelium and Barrett's metaplasia (P < 0.0001), but not during further progression in the sequence.

CONCLUSIONS

Increasing COX-2 expression in Barrett's metaplasia is significantly associated with a change in the local inflammatory reaction, but not during further progression through dysplasia to cancer. This supports the potential of a chemoprevention strategy using COX-2 inhibitors independent of the extent and type of the inflammatory reaction in Barrett's oesophagus.

Patient characteristics and costs associated with dyslipidaemia and related conditions in HIV-infected patients: a retrospective cohort study

BACKGROUND

Metabolic abnormalities are common in HIV-infected individuals and, although multifactorial in origin, have been strongly associated with antiretroviral therapy.

METHODS

Using automated claims and clinical databases, combined with medical record data, we evaluated the burden of dyslipidaemia (DYS) and associated metabolic abnormalities among a cohort of 900 HIV-infected patients aged 18 years and older who received their care from a large multispecialty medical group between 1 January 1996 and 30 June 2002. A Cox proportional hazards model for DYS was developed. Resource use was compiled and subsequently costed with stratification to account for variable length of follow-up.

RESULTS

Mean follow-up time was 3.3 years. DYS was present in 54% of the cohort and 3.4% experienced a cardiovascular (CV) event. Both unadjusted and adjusted results found patients with dyslipidaemia and cardiovascular events significantly more likely to have received protease inhibitor (PI) treatment for longer periods of time. In the Cox proportional hazards model the following factors were significantly associated with an increased risk for DYS: older age, white race, PI use and male sex. Diagnoses of hypertension, hepatitis C virus infection, depression or opportunistic infections were all negatively associated with a DYS diagnosis. When controlled for length of follow up, patients with DYS (and no CV-related events) incurred greater median and mean total average costs than patients without DYS or CV-related events. For patients with more than 2 years of follow up, these total cost differences were statistically significant (P<0.05).

CONCLUSIONS

These findings indicate that DYS is common among patients with HIV infection and is associated with increased use of medical resources.

Recognition of Triple Helical Nucleic Acids by Aminoglycosides

Aminoglycosides, traditional RNA binders, were found to be a new class of triple helical nucleic acid-stabilizing ligands. Neomycin, of all the aminoglycosides, has shown the most significant effects in stabilizing DNA, RNA, and hybrid triple helices. When compared with minor groove binders or intercalators, neomycin excels at triple helical stabilization in most cases. Molecular modeling studies suggest that neomycin reaches into the larger Watson-Hoogsteen groove. The charge and shape complementarity are the key factors in neomycin-triplex recognition. By conjugating neomycin with intercalators such as BQQ (a potent triple helix intercalating agent designed by Hélène), we have progressed in developing more potent triple helix stabilizing ligands. The design of such dual or even triple recognition ligands opens a new paradigm for recognition of triple helix nucleic acids. The article herein presents studies of neomycin as the first molecule that can selectively stabilize nucleic acid triplex structures. These studies are supported by our recent discovery that neomycin prefers to bind to A-like conformations, of which triple helix structures are known to display some characteristics. These findings will contribute to the development of a new series of triplex-specific ligands, and may contribute to either antisense or antigene therapies.

Impaired class II transactivator expression in mice lacking interferon regulatory factor-2

Class II transactivator (CIITA) is required for both constitutive and inducible expression of MHC class II genes. IFN-gamma induced expression of CIITA in various cell types is directed by CIITA type IV promoter. The two transactivators, STAT1 and IRF-1, mediate the IFN-gamma activation of the type IV promoter by binding to the GAS and IRF-E of the promoter, respectively. In addition to IRF-1, IRF-2, another member of the IRF family, also activates the human CIITA type IV promoter, and IRF-2 cooperates with IRF-1 to activate the promoter in transient transfection assays. IRF-1 and IRF-2 can co-occupy the IRF-E of the human CIITA type IV promoter. To understand the effect of loss of IRF-2 on the endogenous CIITA expression, we assayed for CIITA expression in IRF-2 knock-out mice. Both basal and IFN-gamma induced CIITA expression were reduced in IRF-2 knock-out mice. At least half of the amount of inducible CIITA mRNA depends on IRF-2. The reduction of IFN-gamma induced CIITA mRNA in IRF-2 knock-out mice was due to the reduction of the type IV CIITA mRNA induction. The reduction of basal CIITA mRNA was apparently due to the reduction of CIITA mRNA originating from other promoters. These data indicate that IRF-2, like IRF-1, plays a critical role in the regulation of the endogenous CIITA gene. The implications in understanding the previously described phenotypes of IRF-2 defective mice are discussed.

Varying functions of specific major histocompatibility class II transactivator promoter III and IV elements in melanoma cell lines

Melanoma cells commonly express MHC class II molecules constitutively. This is a rare, or possibly unique, phenotype for a nonprofessional antigen-presenting cell, where MHC class II expression ordinarily occurs only after IFN-gamma treatment. Despite the fact that constitutive expression of MHC class II on melanoma cells has been observed for decades and that the regulation of the MHC class II genes is well understood for many different cell types, there is no data regarding the basis for constitutive MHC class II expression in melanoma cells. Here we report that MHC class II expression in melanoma cells can be traced to constitutive expression of the class II transactivator protein (CIITA), which mediates both IFN-gamma-inducible and -constitutive MHC class II expression in all other cell types. In addition, we determined that constitutive CIITA expression is the result of the activation of both the B cell-specific CIITA promoter III and the IFN-gamma-inducible CIITA promoter IV, the latter of which previously has never been known to function as a constitutive promoter in any cell type. The recently described B cell-related ARE-1 activity is important for promoter III activation in the melanoma cells. Constitutive promoter IV activation involves the IFN regulatory factor element (IRF-E), which binds members of the IRF family of proteins, although the major, IFN-gamma inducible member of this family, IRF-1, is not constitutively expressed in these cells. In cells with constitutively active promoter IV, the promoter IV IRF-E is most likely activated by IRF-2. The relevance of these results to the pathway of melanoma development is discussed.

Provider type and the receipt of general and diabetes-related preventive health services among patients with diabetes

OBJECTIVE

Using a measure of provider type that includes "shared care" to determine the contribution of provider type on receipt of general and diabetes-related preventive health services.

METHODS

Automated clinical and administrative data were used to identify adult patients with type 1 and 2 diabetes receiving care from a multispecialty, salaried group practice and enrolled in a large health maintenance organization between 3/97 and 2/98 (n = 10,991). Logistic regression models were fit using generalized estimating equation approaches to evaluate the contribution of provider type on service receipt.

MEASURES

Preventive service receipt included receipt of glycated hemoglobin and lipid testing, retinal examinations, pneumococcal vaccines, Papanicolaou (Pap) smears, and mammograms. Multivariable analyses adjusted for age, sex, race, marital status, household income, diabetes-related comorbidities and complications, prescription drug use, laboratory testing results, and frequency of medical care contact.

RESULTS

Patients seeing an endocrinologist and primary care physician (PCP) were more likely than those seeing endocrinologists alone to receive glycated hemoglobin testing (OR, 1.42), lipid testing (OR, 1.72), mammograms (OR, 2.12), and Pap smears (OR, 2.36), and more likely than those seeing PCPs alone to receive glycated hemoglobin testing (OR, 1.79), lipid testing (OR, 1.54), retinal examinations (OR, 1.33), and mammograms (OR, 1.43). Compared with patients seeing PCPs only, patient's seeing endocrinologists only were more likely to receive retinal examinations (OR, 1.37) and less likely to receive Pap smears (OR, 0.46).

CONCLUSIONS

Care delivered by no one single provider type is associated with greater receipt of all recommended services. Instead, patients seeing both an endocrinologist and a PCP are most likely to receive recommended services.

Dystrophin disruption might be related to myocardial cell apoptosis caused by isoproterenol

Sarcolemma integrity is stabilized by the dystrophin-associated glycoprotein complex that connects actin and laminin-2 in contractile machinery and the extracellular matrix, respectively. Interruption of the connection by the primary gene defect or acquired pathological burden can cause cardiac failure. The purposes of the present study were to verify whether dystrophin is disrupted in acute myocardial injury after the isoproterenol overload (10 mg/kg) and to examine its relation to myocardial cell apoptosis in rats. This injury from 4-16 h at the subendocardium was accompanied by dystrophin disruption and dislocation from subsarcolemma to cytoplasm, which were confirmed by immunohistology and Western blotting. However, delta-sarcoglycan was thoroughly preserved in sarcolemma. The dystrophin degradation preceded the appearance of apoptotic cells and exactly coincided with the transferase-mediated dUTP-biotin nick end labeling-positive cardiomyocytes (TUNEL), as was verified by double-staining. These data suggest that beta-adrenergic stimulation induces dystrophin breakdown followed by apoptosis.

Purine catabolism in Escherichia coli and function of xanthine dehydrogenase in purine salvage

Escherichia coli is not known to utilize purines, other than adenine and adenosine, as nitrogen sources. We reinvestigated purine catabolism because a computer analysis suggested several potential sigma(54)-dependent promoters within a 23-gene cluster whose products have homology to purine catabolic enzymes. Our results did not provide conclusive evidence that the sigma(54)-dependent promoters are active. Nonetheless, our results suggest that some of the genes are metabolically significant. We found that even though several purines did not support growth as the sole nitrogen source, they did stimulate growth with aspartate as the nitrogen source. Cells produced (14)CO(2) from minimal medium containing [(14)C]adenine, which implies allantoin production. However, neither ammonia nor carbamoyl phosphate was produced, which implies that purine catabolism is incomplete and does not provide nitrogen during nitrogen-limited growth. We constructed strains with deletions of two genes whose products might catalyze the first reaction of purine catabolism. Deletion of one eliminated (14)CO(2) production from [(14)C]adenine, which implies that its product is necessary for xanthine dehydrogenase activity. We changed the name of this gene to xdhA. The xdhA mutant grew faster with aspartate as a nitrogen source. The mutant also exhibited sensitivity to adenine, which guanosine partially reversed. Adenine sensitivity has been previously associated with defective purine salvage resulting from impaired synthesis of guanine nucleotides from adenine. We propose that xanthine dehydrogenase contributes to this purine interconversion.

Interferon regulatory factor-2 point mutations in human pancreatic tumors

Interferon regulatory factor (IRF)-2, a member of the IRF family, is a transcription factor involved in the regulation of various interferon and virus-stimulated genes and other genes. For example, IRF-2 is an activator of the interferon (IFN)-gamma-inducible MHC class II transactivator (CIITA) type IV promoter. It cooperates with IRF-1 in the activation of the CIITA type IV promoter and can co-occupy the IRF-E of the promoter with IRF-1. In a previous study, we identified an inactivating point mutation in the DNA binding domain of IRF-2 expressed in a human pancreatic tumor cell line that does not express CIITA or MHC class II in response to IFN-gamma. To further assess the potential impact of IRF-2 mutations in tumorigenesis, we screened fresh pancreatic tumor explants and identified 2 IRF-2 point mutations in the 2 alleles of IRF-2 from a single tumor specimen. Both mutations occurred in the DNA binding domain of IRF-2. DNA binding assays demonstrated that the IRF-2 point mutations impaired IRF-2 DNA binding. The transactivation function of the mutant IRF-2s was similarly impaired. This is the first report of IRF-2 mutations in human tumor explants.

Apolipoprotein E is a genetic risk factor for fetal iodine deficiency disorder in China

Fetal iodine deficiency disorder (FIDD) is the principal form of endemic cretinism, and the most common cause of preventable mental deficiency in the world. However not everyone at risk develops FIDD and familial aggregation is common. This suggests that genetic factors may also be involved. The Apolipoprotein E (APOE) gene encodes for a lipoprotein that possesses a thyroid hormone binding domain, and APOE genotype may affect the efficiency with which thyroid hormone influences neuronal cell growth during the first and second trimesters of fetal development. We have compared ApoE genotypes in 91 FIDD cases with 154 local control subjects, recruited from three iodine deficiency areas in central China. We have also genotyped 42 FIDD family cases and 158 normal individuals from the families of local controls, and 375 population controls from Shanghai. APOE epsilon4 genotypes were significantly enriched in FIDD probands from each of the three iodine deficiency areas; the epsilon4 allele frequency was 16% vs 6% in controls. The same effect was also observed when we compared FIDD family cases with controls and control families. Our data suggest that in iodine-deficient areas, the APOE epsilon4 allele is a genetic risk factor for FIDD. The phenomenon may affect population selection and contribute to the low frequency of the epsilon4 allele in Chinese compared to Caucasian populations.

Co-occupancy of the interferon regulatory element of the class II transactivator (CIITA) type IV promoter by interferon regulatory factors 1 and 2

Class II transactivator (CIITA) activates the expression of major histocompatibility class II genes, which encode antigen-presenting molecules recognized by the T-cell receptor of CD4+ T cells. IFN-gamma induced CIITA transcription in many cell types is directed by the CIITA Type IV promoter. Here we report that the human CIITA Type IV promoter IRF-E binds IRF-1 and can be activated by exogenous expression of IRF-1. Surprisingly, the CIITA Type IV promoter IRF-E is also activated by IRF-2, another member of the IRF family that generally acts as a transcriptional repressor. In addition, we found that IRF-1 and IRF-2 synergistically activate the CIITA Type IV promoter. Electrophoretic mobility shift assays revealed that IRF-1 and IRF-2 can simultaneously occupy the IRF-E of the CIITA Type IV promoter, suggesting a novel mechanism for the role of these two proteins in promoter activation. Our results also indicate that IRF-1 and IRF-2 can cooperatively activate and co-occupy the IRF-E of the guanylate binding protein (GBP) promoter. Finally, CIITA induction by IFN-gamma does not occur in a pancreatic tumor cell line that expresses a mutated IRF-2, representing the first IRF-2 mutation identified in a human tumor cell line.

Finite-volume lattice Boltzmann schemes in two and three dimensions

Simple and practical finite-volume schemes for the lattice Boltzmann equation are derived in two and three dimensions through the application of modern finite-volume methods. The schemes use a finite-volume vortex-type formulation based on quadrilateral elements in two dimensions and trilinear hexahedral elements in three dimensions. It is shown that the schemes are applicable to domains with irregular boundaries of arbitrary shape in two and three dimensions.

Finite-volume lattice Boltzmann method

We present a finite-volume formulation for the lattice Boltzmann method (FVLBM) based on standard bilinear quadrilateral elements in two dimensions. The accuracy of this scheme is demonstrated by comparing the velocity field with the analytical solution of the Navier-Stokes equations for time dependent rotating Couette flow and Taylor vortex flow. To demonstrate the flexibility of the scheme, we have also simulated a modified rotating Couette flow, where the inner cylinder has an elliptical shape. The results agree with those obtained from the traditional marker-and-cell method. The FVLBM scheme is applicable to arbitrarily shaped two-dimensional regions, and thus the range of applicability of the lattice Boltzmann method has been significantly extended.

[Treatment of lingual angiocavernoma by selective arteriocatheterization with urea injection]

Selective arteriocatheterization with urea injection was administered to 36 cases of lingual angiocavernoma. There were 20 males and 16 females, ranging in age from 6 to 18 years with an average of 12 years. Two to five mililiters of 40% urea were injected once a day for 10-15 days as a course of treatment, 29 cases (80.6%) were cured in one course of treatment. The other 7 cases (19.4%) were cured in the 2nd course of treatment. The results suggest that selective arteriocatheterization with urea injection is a safe, convenient and effective technique in the treatment of ingual angiocavernoma.

Verapamil diminishes action potential changes during metabolic inhibition by blocking ATP-regulated potassium currents

Verapamil has beneficial effects on ischemic myocardium, including reduction in electrophysiological derangements, prevention of intracellular K+ loss, and preservation of high-energy phosphates, but the mechanisms underlying these actions are not clear. Recent studies have demonstrated a role of ATP-regulated K+ (KATP) current in action potential shortening and K+ loss during ischemia and metabolic inhibition. Therefore, we studied the effects of verapamil on KATP current in feline ventricular myocytes to test the hypothesis that the drug prevents ischemic electrophysiological disturbances by affecting the KATP channel. Membrane potentials and currents were recorded using standard patch-clamp techniques. During 15-minute superfusion with 1 mM CN-, action potential duration measured at 90% repolarization was reduced from 259 +/- 12 to 98 +/- 15 msec (62% reduction) in the absence of verapamil and from 266 +/- 11 to 183 +/- 16 msec (31% reduction) in the presence of 2 microM verapamil (p less than 0.01). In inside-out membrane patches, the KATP current, activated in the absence of ATP, was significantly suppressed by intracellular application of 2 microM verapamil, but the single-channel conductance was not changed. Verapamil did not change the mean open and closed times of the channel within bursts (e.g., the mean open time was 1.92 +/- 0.18 and 1.82 +/- 0.21 msec in the absence and presence of 2 microM verapamil, respectively), but it shortened the mean lifetime of bursts from 41.1 +/- 3.5 to 24.9 +/- 2.8 msec (p less than 0.01) and prolonged the closed time between bursts from 39.4 +/- 4.6 to 78.5 +/- 5.1 msec (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Early afterdepolarizations and triggered activity induced by cocaine. A possible mechanism of cocaine arrhythmogenesis

BACKGROUND

Cocaine may produce life-threatening cardiac arrhythmias, but it is not clear whether this is an indirect effect of coronary vasoconstriction and ischemia or a direct myocardial effect of the substance. Except for its effects on the Na+ current as a local anesthetic, little is known about the direct electrophysiological actions on cardiac cells. Therefore, we studied the effects of cocaine on action potentials and membrane currents in isolated feline ventricular myocytes to test the hypothesis that cocaine-induced arrhythmogenesis may be based on cellular and ionic mechanisms.

METHODS AND RESULTS

Action potentials and membrane currents were recorded using the patch clamp technique. Single cells were isolated from feline left ventricles by enzymatic digestion. Exposure to cocaine (10 or 50 microM) depressed the plateau phase of the action potential and prolonged action potential duration. Action potential duration measured at 90% repolarization (APD90) was increased from 280 +/- 12 msec to 325 +/- 17 msec (p less than 0.01) by 5-minute exposure to 10 mumol cocaine, when the cells were stimulated at 1 Hz. During exposure to 50 mumol cocaine, APD90 was markedly increased from 298 +/- 13 msec to 437 +/- 35 msec (p less than 0.01) in seven of 16 cells, and early afterdepolarizations (EADs) developed in these cells. The take-off potential and the amplitude of EADs were -28.3 +/- 2.3 mV and 16.8 +/- 1.2 mV, respectively. Triggered activity arising from EADs was induced in four of the seven cells. Addition of 1 nmol isoproterenol augmented EADs and induced sustained triggered activity, whereas they were suppressed by exposure to 2 microM verapamil. Whole-cell voltage clamp experiments revealed that cocaine (50 microM) reduced the peak L-type Ca2+ current from 1.03 +/- 0.13 nA to 0.79 +/- 0.11 nA (23% reduction, p less than 0.05). Cocaine also reduced the peak delayed rectifier K+ current from 362 +/- 51 pA to 113 +/- 32 pA (69% reduction, p less than 0.01). However, cocaine did not affect activation and inactivation kinetics of these channels. Cocaine had no effect on the inward rectifier K+ current.

CONCLUSIONS

We conclude that cocaine can prolong action potential duration and induce EADs and triggered activity by blocking the delayed rectifier K+ current, and that cocaine-induced abnormalities of repolarization, modulated by its inhibitory effects on catecholamine reuptake, may play a role in the potential of cocaine for induction of acute fatal arrhythmias.