[Development and validation of a prognostic prediction model for patients with stage Ⅰ to Ⅲ colon cancer incorporating high-risk pathological features]

Objective: To examine a predictive model that incorporating high risk pathological factors for the prognosis of stage Ⅰ to Ⅲ colon cancer. Methods: This study retrospectively collected clinicopathological information and survival outcomes of stage Ⅰ~Ⅲ colon cancer patients who underwent curative surgery in 7 tertiary hospitals in China from January 1, 2016 to December 31, 2017. A total of 1 650 patients were enrolled, aged (M(IQR)) 62 (18) years (range: 14 to 100). There were 963 males and 687 females. The median follow-up period was 51 months. The Cox proportional hazardous regression model was utilized to select high-risk pathological factors, establish the nomogram and scoring system. The Bootstrap resampling method was utilized for internal validation of the model, the concordance index (C-index) was used to assess discrimination and calibration curves were presented to assess model calibration. The Kaplan-Meier method was used to plot survival curves after risk grouping, and Cox regression was used to compare disease-free survival between subgroups. Results: Age (HR=1.020, 95%CI: 1.008 to 1.033, P=0.001), T stage (T3:HR=1.995,95%CI:1.062 to 3.750,P=0.032;T4:HR=4.196, 95%CI: 2.188 to 8.045, P<0.01), N stage (N1: HR=1.834, 95%CI: 1.307 to 2.574, P<0.01; N2: HR=3.970, 95%CI: 2.724 to 5.787, P<0.01) and number of lymph nodes examined (≥36: HR=0.438, 95%CI: 0.242 to 0.790, P=0.006) were independently associated with disease-free survival. The C-index of the scoring model (model 1) based on age, T stage, N stage, and dichotomous variables of the lymph nodes examined (<12 and ≥12) was 0.723, and the C-index of the scoring model (model 2) based on age, T stage, N stage, and multi-categorical variables of the lymph nodes examined (<12, 12 to <24, 24 to <36, and ≥36) was 0.726. A scoring system was established based on age, T stage, N stage, and multi-categorical variables of lymph nodes examined, the 3-year DFS of the low-risk (≤1), middle-risk (2 to 4) and high-risk (≥5) group were 96.3% (n=711), 89.0% (n=626) and 71.4% (n=313), respectively. Statistically significant difference was observed among groups (P<0.01). Conclusions: The number of lymph nodes examined was an independent prognostic factor for disease-free survival after curative surgery in patients with stage Ⅰ to Ⅲ colon cancer. Incorporating the number of lymph nodes examined as a multi-categorical variable into the T and N staging system could improve prognostic predictive validity.

[Analysis of prognosis and influencing factors of No. 253 lymph node metastasis in descending colon, sigmoid colon, and rectal cancer: a multicenter study]

Objectives: To analyze the influencing factors of No. 253 lymph node metastasis in descending colon cancer, sigmoid colon cancer, and rectal cancer, and to investigate the prognosis of No. 253 lymph node-positive patients by propensity score matching analysis. Methods: A retrospective analysis was performed on clinical data from patients with descending colon cancer, sigmoid colon cancer, rectosigmoid junction cancer, and rectal cancer who underwent surgery between January 2015 and December 2019 from the Cancer Hospital of the Chinese Academy of Medical Sciences, China-Japan Friendship Hospital, Peking Union Medical College Hospital, General Hospital of the Chinese People's Liberation Army, and Peking University Cancer Hospital. A total of 3 016 patients were included according to inclusion and exclusion criteria, comprising 1 848 males and 1 168 females, with 1 675 patients aged≥60 years and 1 341 patients aged<60 years. Clinical and pathological factors from single center data were subjected to univariate analysis to determine influencing factors of No. 253 lymph node metastasis, using a binary Logistic regression model. Based on the results of the multivariate analysis, a nomogram was constructed. External validation was performed using data from other multicenter sources, evaluating the effectiveness through the area under the receiver operating characteristic curve and the calibration curve. Using data from a single center, the No. 253 lymph node-positive group was matched with the negative group in a 1∶2 ratio (caliper value=0.05). Survival analysis was performed using the Kaplan-Meier method and Log-rank test. The Cox proportional hazards model was used to determine independent prognostic factors. Results: (1) The tumor diameter≥5 cm (OR=4.496,95%CI:1.344 to 15.035, P=0.015) T stage (T4 vs. T1: OR=11.284, 95%CI:7.122 to 15.646, P<0.01), N stage (N2 vs. N0: OR=60.554, 95%CI:7.813 to 469.055, P=0.043), tumor differentiation (moderate vs. well differentiated: OR=1.044, 95%CI:1.009 to 1.203, P=0.044; poor vs. well differentiated: OR=1.013, 95%CI:1.002 to 1.081, P=0.013), tumor location (sigmoid colon vs. descending colon: OR=9.307, 95%CI:2.236 to 38.740, P=0.002), pathological type (mucinous adenocarcinoma vs. adenocarcinoma: OR=79.923, 95%CI:15.113 to 422.654, P<0.01; signet ring cell carcinoma vs. adenocarcinoma: OR=27.309, 95%CI:4.191 to 177.944, P<0.01), and positive vascular invasion (OR=3.490, 95%CI:1.033 to 11.793, P=0.044) were independent influencing factors of No. 253 lymph node metastasis. (2) The area under the curve of the nomogram prediction model was 0.912 (95%CI: 0.869 to 0.955) for the training set and 0.921 (95%CI: 0.903 to 0.937) for the external validation set. The calibration curve demonstrated good consistency between the predicted outcomes and the actual observations. (3) After propensity score matching, the No. 253 lymph node-negative group did not reach the median overall survival time, while the positive group had a median overall survival of 20 months. The 1-, 3- and 5-year overall survival rates were 83.9%, 61.3% and 51.6% in the negative group, and 63.2%, 36.8% and 15.8% in the positive group, respectively. Multivariate Cox analysis revealed that the T4 stage (HR=3.067, 95%CI: 2.357 to 3.990, P<0.01), the N2 stage (HR=1.221, 95%CI: 0.979 to 1.523, P=0.043), and No. 253 lymph node positivity (HR=2.902, 95%CI:1.987 to 4.237, P<0.01) were independent adverse prognostic factors. Conclusions: Tumor diameter ≥5 cm, T4 stage, N2 stage, tumor location in the sigmoid colon, adverse pathological type, poor differentiation, and vascular invasion are influencing factors of No. 253 lymph node metastasis. No. 253 lymph node positivity indicates a poorer prognosis. Therefore, strict dissection for No. 253 lymph node should be performed for colorectal cancer patients with these high-risk factors.

Fascia- vs vessel-oriented lateral lymph node dissection for rectal cancer: Short-term outcomes and prognosis in a single-center experience

BACKGROUND

For the management of lateral lymph node (LLN) metastasis in patients with rectal cancer, selective LLN dissection (LLND) is gradually being accepted by Chinese scholars. Theoretically, fascia-oriented LLND allows radical tumor resection and protects of organ function. However, there is a lack of studies comparing the efficacy of fascia-oriented and traditional vessel-oriented LLND. Through a preliminary study with a small sample size, we found that fascia-oriented LLND was associated with a lower incidence of postoperative urinary and male sexual dysfunction and a higher number of examined LLNs. In this study, we increased the sample size and refined the postoperative functional outcomes.

AIM

To compare the effects of fascia- and vessel-oriented LLND regarding short-term outcomes and prognosis.

METHODS

We conducted a retrospective cohort study on data from 196 patients with rectal cancer who underwent total mesorectal excision and LLND from July 2014 to August 2021. The short-term outcomes included perioperative outcomes and postoperative functional outcomes. The prognosis was measured based on overall survival (OS) and progression-free survival (PFS).

RESULTS

A total of 105 patients were included in the final analysis and were divided into fascia- and vessel-oriented groups that included 41 and 64 patients, respectively. Regarding the short-term outcomes, the median number of examined LLNs was significantly higher in the fascia-oriented group than in the vessel-oriented group. There were no significant differences in the other short-term outcomes. The incidence of postoperative urinary and male sexual dysfunction was significantly lower in the fascia-oriented group than in the vessel-oriented group. In addition, there was no significant difference in the incidence of postoperative lower limb dysfunction between the two groups. In terms of prognosis, there was no significant difference in PFS or OS between the two groups.

CONCLUSION

It is safe and feasible to perform fascia-oriented LLND. Compared with vessel-oriented LLND, fascia-oriented LLND allows the examination of more LLNs and may better protect postoperative urinary function and male sexual function.

The safety and prognosis of radical surgery in colorectal cancer patients over 80 years old

OBJECTIVE

The purpose of this study was to assess the safety and feasibility of radical surgery and to investigate prognostic factors influencing in colorectal cancer (CRC) patients over the age of 80.

METHODS

Between January 2010 and December 2020, 372 elderly CRC patients who underwent curative resection at the National Cancer Center were enrolled in the study. Preoperative clinical characteristics, perioperative outcomes, and postoperative pathological features were all collected.

RESULTS

A total of 372 elderly patients with colorectal cancer were included in the study, including 226 (60.8%) men and 146 (39.2%) women. A total of 219 (58.9%) patients had a BMI < 24 kg/m², and 153 (41.1%) patients had a BMI ≥ 24 kg/m². The mean operation time and intraoperative blood loss were 152.3 ± 58.1 min and 67.6 ± 35.4 ml, respectively. The incidence of overall postoperative complications was 28.2% (105/372), and the incidence of grade 3-4 complications was 14.7% (55/372). In the multivariable Cox regression analysis, BMI ≥ 24 kg/m² (HR, 2.30, 95% CI, 1.27-4.17; P = 0.006) and N1-N2 stage (HR: 2.97; 95% CI, 1.48-5.97; P = 0.002) correlated with worse CSS.

CONCLUSION

The findings of this study showed that radical resection for CRC is safe and feasible for patients over the age of 80. After radical resection, BMI and N stage were independent prognostic factors for elderly CRC patients.

HAMP as a Prognostic Biomarker for Colorectal Cancer Based on Tumor Microenvironment Analysis

Colorectal cancer (CRC) is the most common digestive tumor in the world and has a high mortality rate. The development and treatment of CRC are related to the immune microenvironment, but immune response-related prognostic biomarkers are lacking. In this study, we used The Cancer Genome Atlas (TCGA) to explore the tumor microenvironment (TME) and weighted gene coexpression network analysis (WGCNA) to identify significant prognostic genes. We also identified differentially expressed genes in the TCGA data and explored immune-related genes and transcription factors (TFs). Then, we built a TF regulatory network and performed a comprehensive prognostic analysis of an lncRNA-associated competitive endogenous RNA network (ceRNA network) to build a prognostic model. CCR8 and HAMP were identified both in the WGCNA key module and as immune-related genes. HAMP had good prognostic value for CRC and was highly expressed in CRC tissues and had a negative correlation with CD4⁺ T cells and M0 macrophages based on immunohistochemistry and immunofluorescence staining of clinical specimens.We found that HAMP had high prognostic and therapeutic target value for CRC and was associated with liver metastasis. These analysis results revealed that HAMP may be a candidate immune-related prognostic biomarker for CRC.

Reduced serum high-density lipoprotein cholesterol levels and aberrantly expressed cholesterol metabolism genes in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a common malignant tumor of the gastrointestinal tract. Lipid metabolism, as an important part of material and energy circulation, is well known to play a crucial role in CRC.

AIM

To explore the relationship between serum lipids and CRC development and identify aberrantly expressed cholesterol metabolism genes in CRC.

METHODS

We retrospectively collected 843 patients who had confirmed CRC and received surgical resection from 2013 to 2015 at the Cancer Hospital of the Chinese Academy of Medical Sciences as our research subjects. The levels of serum total cholesterol (TC), triglycerides, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), LDL-C/HDL-C and clinical features were collected and statistically analyzed by SPSS. Then, we used the data from Oncomine to screen the differentially expressed genes (DEGs) of the cholesterol metabolism pathway in CRC and used Gene Expression Profiling Interactive Analysis to confirm the candidate DEGs. PrognoScan was used to analyze the prognostic value of the DEGs, and Search Tool for the Retrieval of Interacting Genes was used to construct the protein–protein interaction network of DEGs.

RESULTS

The serum HDL-C level in CRC patients was significantly correlated with tumor size, and patients whose tumor size was more than 5 cm had a lower serum HDL-C level (1.18 ± 0.41 mmol/L vs 1.25 ± 0.35 mmol/L, P < 0.01) than their counterparts. In addition, TC/HDL (4.19 ± 1.33 vs 3.93 ± 1.26, P < 0.01) and LDL-C/HDL-C (2.83 ± 1.10 vs 2.61 ± 0.96, P < 0.01) were higher in patients with larger tumors. The levels of HDL-C (P < 0.05), TC/HDL-C (P < 0.01) and LDL-C/HDL-C (P < 0.05) varied in different stages of CRC patients, and the differences were significant. We screened 14 differentially expressed genes (DEGs) of the cholesterol metabolism pathway in CRC and confirmed that lipoprotein receptor-related protein 8 (LRP8), PCSK9, low-density lipoprotein receptor (LDLR), MBTPS2 and FDXR are upregulated, while ABCA1 and OSBPL1A are downregulated in cancer tissue. Higher expression of LDLR (HR = 3.12, 95%CI: 1.77-5.49, P < 0.001), ABCA1 (HR = 1.66, 95%CI: 1.11-2.48, P = 0.012) and OSBPL1A (HR = 1.38, 95%CI: 1.01-1.89, P = 0.041) all yielded significantly poorer DFS outcomes. Higher expression of FDXR (HR = 0.7, 95%CI: 0.47-1.05, P = 0.002) was correlated with longer DFS. LDLR, ABCA1, OSBPL1A and FDXR were involved in many important cellular function pathways.

CONCLUSION

Serum HDL-C levels are associated with tumor size and stage in CRC patients. LRP8, PCSK9, LDLR, MBTPS2 and FDXR are upregulated, while ABCA1 and OSBPL1A are downregulated in CRC. Among them, LDLR, ABCA1, OSBPL1A and FDXR were valuable prognostic factors of DFS and were involved in important cellular function pathways.

[Comparison on efficacy between fascia-oriented versus vascular-oriented lateral lymph node dissection in patients with rectal cancer]

Objective: To compare the postoperative function, the short-term and long-term outcomes between fascia-oriented and vascular-oriented lateral lymph node dissection (LLND) in patients with rectal cancer. Methods: A retrospective cohort study was performed. Clinical data of patients who received total mesorectal excision (TME) with LLND at National Cancer Center, Cancer Hospital of Chinese Academy of Medical Science from January 2014 to December 2019 were retrospectively collected. Inclusion criteria were as follows: (1) rectal cancer was pathologically diagnosed, and the lower margin was below the peritoneal reflection. (2) resectable advanced rectal cancer with suspected lateral lymph node metastasis was evaluated based on rectal MRI assessment. (3) preoperative MRI showed lateral lymph node short diameter ≥5 mm and/or lymph node morphology (spike, blur, irregular) as well as heterogenous signal intensity. Lymph node shrinkage was less than 60% after receiving neoadjuvant therapy based on the reassessment of rectal MRI. (4) TME+LLND surgery was performed synchronously. Exclusion criteria were as follows: (1) previous history of pelvic surgery; (2) preoperative cystitis, urethritis, moderate and severe prostatic hyperplasia and other diseases resulting in abnormal urination function; (3) preoperative sexual dysfunction or loss of function; (4) patients receiving LLND due to lateral recurrence after TME; (5) distant metastasis of the tumor at initial diagnosis; (6) Incomplete collection of clinical data. A total of 73 consecutive patients were enrolled in this study. Based on the surgical approaches in performing LLND, patients were divided into fascia-oriented group (n=30) and vascular-oriented group (n=43). There were no significant differences in baseline data between the two groups (all P>0.05). The main outcome indicators of this study were the incidence of postoperative urinary and male sexual dysfunction, the efficacy, the number of lateral lymph nodes harvested and the detection rate of positive lymph nodes. Overall survival (OS) rates and progression free survival (PFS) rates were calculated by the Kaplan-Meier method and compared by log-rank test. Results: All patients in both groups completed surgery successfully. There were no significant differences in operation time, intraoperative blood loss, postoperative complications, and the length of hospital stay between the two groups (all P>0.05). In the whole group, the incidence of postoperative urinary dysfunction and male sexual dysfunction was 43.8% (32/73) and 62.5% (25/40), respectively. The median number of lateral lymph nodes harvested was 8.0(4.0,11.0) with a positive rate of 20.5%(15/73). Compared to the vascular-oriented group, the fascia-oriented group demonstrated a decreased rate of urinary dysfunction [26.7% (8/30) vs. 55.8% (24/43), χ(2)=6.098, P=0.014], lower rate of sexual dysfunction in males [6/15 vs. 76% (19/25), χ(2)=5.184, P=0.023], more harvested lateral lymph nodes [M (P25, P75): 9.5 (6.8, 15.3) vs. 6.0 (3.0, 9.0), Z=-2.849, P=0.004]. There was no significant difference in the positvie rate of lateral lymph nodes between the two groups [20% (6/30) versus 20.9% (9/43), χ(2)=0.009, P=0.923]. Three(4.1%) patients were lost during a median follow-up of 34 (1-66) months. The 3-year PFS and OS of the whole cohort were 69.5% and 88.3%, respectively. No significant difference in 3-year PFS rates (79.6% vs. 62.0%, P=0.172) and 3-year OS rates (91.2% vs. 85.9%, P=0.333) were observed between the fascia-oriented group and the vascular-oriented group (both P>0.05). Conclusion: Fascia-oriented LLND is associated with lower risk of postoperative urinary and male sexual dysfunction in patients with rectal carcinoma, and harvest of more lymph nodes, but no significant advantage in long-term survival.

Development and Validation of a Nomogram and a Comprehensive Prognostic Analysis of an LncRNA-Associated Competitive Endogenous RNA Network Based on Immune-Related Genes for Locally Advanced Rectal Cancer With Neoadjuvant Therapy

Colorectal cancer (CRC) is a common digestive tract tumor worldwide. In recent years, neoadjuvant chemoradiotherapy (CRT) has been the most comprehensive treatment for locally advanced rectal cancer (LARC). In this study, we explored immune infiltration in rectal cancer (RC) and identified immune-related differentially expressed genes (IRDEGs). Then, we identified response markers in datasets in GEO databases by principal component analysis (PCA). We also utilized three GEO datasets to identify the up- and downregulated response-related genes simultaneously and then identified genes shared between the PCA markers and three GEO datasets. Based on the hub IRDEGs, we identified target mRNAs and constructed a ceRNA network. Based on the ceRNA network, we explored prognostic biomarkers to develop a prognostic model for RC through Cox regression. We utilized the specimen to validate the expression of the two biomarkers. We also utilized LASSO regression to screen hub IRDEGs and built a nomogram to predict the response of LARC patients to CRT. All of the results show that the nomogram and prognostic model offer good prognostic value and that the ceRNA network can effectively highlight the regulatory relationship. hsa-mir-107 and WDFY3-AS2 may be prognostic biomarkers for RC.

Primary Tumor Resection for Rectal Cancer With Unresectable Liver Metastases: A Chance to Cut Is a Chance for Improved Survival

Background: About half of the patients with rectal cancer will develop liver metastasis during the course of their illness. Unfortunately, a large proportion of these metastases are unresectable. Surgical resection of the primary tumor vs. palliative treatment in patients with unresectable synchronous liver metastases remains controversial.

Methods: Patients with rectal cancer with surgically unresectable liver metastases were identified from the Surveillance, Epidemiology, and End Results (SEER) database from January 1, 2010, to December 31, 2015. According to different treatment modalities, patients were divided into a primary tumor resection group and a non-resection group. Rates of primary tumor resection and survival were calculated for each year. Kaplan–Meier methods and Cox regression models were used to assess long-term survival. Multivariable logistic regression models were used to evaluate factors potentially associated with primary tumor resection.

Results: Among 1,957 patients, 494 (25.2%) had undergone primary tumor resection. Patients with primary tumor resection had significantly better 5-year survival rate (27.2 vs. 5.6%, P < 0.001) compared to the non-resection group. Chemoradiotherapy with primary site resection was associated with the longest mean and 5-year OS (44.7 months, 32.4%). The Cox regression analyses of the subgroup indicated that patients who underwent primary tumor resection had improved survival compared with those who did not undergo resection in all 25 subgroups. Factors associated with primary tumor resection were well or moderately differentiated tumor grade, undergoing radiation, and primary tumor size <5 cm.

Conclusions: The majority of patients with rectal cancer with unresectable liver metastases did not undergo primary tumor resection. Our results indicate that resection of the primary tumor appears to offer the greatest chance of survival. Prospective studies are needed to confirm these results.

Impact factors of lymph node retrieval on survival in locally advanced rectal cancer with neoadjuvant therapy

BACKGROUND

Conventional clinical guidelines recommend that at least 12 lymph nodes should be removed during radical rectal cancer surgery to achieve accurate staging. The current application of neoadjuvant therapy has changed the number of lymph node dissection.

AIM

To investigate factors affecting the number of lymph nodes dissected after neoadjuvant chemoradiotherapy in locally advanced rectal cancer and to evaluate the relationship of the total number of retrieved lymph nodes (TLN) with disease-free survival (DFS) and overall survival (OS).

METHODS

A total of 231 patients with locally advanced rectal cancer from 2015 to 2017 were included in this study. According to the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) tumor-node-metastasis (TNM) classification system and the NCCN guidelines for rectal cancer, the patients were divided into two groups: group A (TLN ≥ 12, n = 177) and group B (TLN < 12, n = 54). Factors influencing lymph node retrieval were analyzed by univariate and binary logistic regression analysis. DFS and OS were evaluated by Kaplan-Meier curves and Cox regression models.

RESULTS

The median number of lymph nodes dissected was 18 (range, 12-45) in group A and 8 (range, 2-11) in group B. The lymph node ratio (number of positive lymph nodes/total number of lymph nodes) (P = 0.039) and the interval between neoadjuvant therapy and radical surgery (P = 0.002) were independent factors of the TLN. However,TLN was not associated with sex, age, ASA score, clinical T or N stage, pathological T stage, tumor response grade (Dworak), downstaging, pathological complete response, radiotherapy dose, preoperative concurrent chemotherapy regimen, tumor distance from anal verge, multivisceral resection, preoperative carcinoembryonic antigen level, perineural invasion, intravascular tumor embolus or degree of differentiation. The pathological T stage (P < 0.001) and TLN (P < 0.001) were independent factors of DFS, and pathological T stage (P = 0.011) and perineural invasion (P = 0.002) were independent factors of OS. In addition, the risk of distant recurrence was greater for TLN < 12 (P = 0.009).

CONCLUSION

A shorter interval to surgery after neoadjuvant chemoradiotherapy for rectal cancer under indications may cause increased number of lymph nodes harvested. Tumor shrinkage and more extensive lymph node retrieval may lead to a more favorable prognosis.

Nomograms and risk score models for predicting survival in rectal cancer patients with neoadjuvant therapy

BACKGROUND

Colorectal cancer is a common digestive cancer worldwide. As a comprehensive treatment for locally advanced rectal cancer (LARC), neoadjuvant therapy (NT) has been increasingly used as the standard treatment for clinical stage II/III rectal cancer. However, few patients achieve a complete pathological response, and most patients require surgical resection and adjuvant therapy. Therefore, identifying risk factors and developing accurate models to predict the prognosis of LARC patients are of great clinical significance.

AIM

To establish effective prognostic nomograms and risk score prediction models to predict overall survival (OS) and disease-free survival (DFS) for LARC treated with NT.

METHODS

Nomograms and risk factor score prediction models were based on patients who received NT at the Cancer Hospital from 2015 to 2017. The least absolute shrinkage and selection operator regression model were utilized to screen for prognostic risk factors, which were validated by the Cox regression method. Assessment of the performance of the two prediction models was conducted using receiver operating characteristic curves, and that of the two nomograms was conducted by calculating the concordance index (C-index) and calibration curves. The results were validated in a cohort of 65 patients from 2015 to 2017.

RESULTS

Seven features were significantly associated with OS and were included in the OS prediction nomogram and prediction model: Vascular_tumors_bolt, cancer nodules, yN, body mass index, matchmouth distance from the edge, nerve aggression and postoperative carcinoembryonic antigen. The nomogram showed good predictive value for OS, with a C-index of 0.91 (95%CI: 0.85, 0.97) and good calibration. In the validation cohort, the C-index was 0.69 (95%CI: 0.53, 0.84). The risk factor prediction model showed good predictive value. The areas under the curve for 3- and 5-year survival were 0.811 and 0.782. The nomogram for predicting DFS included ypTNM and nerve aggression and showed good calibration and a C-index of 0.77 (95%CI: 0.69, 0.85). In the validation cohort, the C-index was 0.71 (95%CI: 0.61, 0.81). The prediction model for DFS also had good predictive value, with an AUC for 3-year survival of 0.784 and an AUC for 5-year survival of 0.754.

CONCLUSION

We established accurate nomograms and prediction models for predicting OS and DFS in patients with LARC after undergoing NT.

Differential Expression Analysis Revealing CLCA1 to Be a Prognostic and Diagnostic Biomarker for Colorectal Cancer

Colorectal cancer (CRC) is a common malignant tumor of the digestive tract and lacks specific diagnostic markers. In this study, we utilized 10 public datasets from the NCBI Gene Expression Omnibus (NCBI-GEO) database to identify a set of significantly differentially expressed genes (DEGs) between tumor and control samples and WGCNA (Weighted Gene Co-Expression Network Analysis) to construct gene co-expression networks incorporating the DEGs from The Cancer Genome Atlas (TCGA) and then identify genes shared between the GEO datasets and key modules. Then, these genes were screened via MCC to identify 20 hub genes. We utilized regression analyses to develop a prognostic model and utilized the random forest method to validate. All hub genes had good diagnostic value for CRC, but only CLCA1 was related to prognosis. Thus, we explored the potential biological value of CLCA1. The results of gene set enrichment analysis (GSEA) and immune infiltration analysis showed that CLCA1 was closely related to tumor metabolism and immune invasion of CRC. These analysis results revealed that CLCA1 may be a candidate diagnostic and prognostic biomarker for CRC.

Impact of interval between neoadjuvant chemoradiotherapy and surgery in rectal cancer patients

BACKGROUND

Epidemiologically, in China, locally advanced rectal cancer is a more common form of rectal cancer. Preoperative neoadjuvant concurrent chemoradiotherapy can effectively reduce the size of locally invasive tumors and improve disease-free survival (DFS) and pathologic response after surgery. At present, this modality has become the standard protocol for the treatment of locally advanced rectal cancer in many centers, but the optimal time for surgery after neoadjuvant therapy is still controversial.

AIM

To investigate the impact of time interval between neoadjuvant therapy and surgery on DFS and pathologic response in patients with locally advanced rectal cancer.

METHODS

A total of 231 patients who were classified as having clinical stage II or III advanced rectal cancer and underwent neoadjuvant chemoradiation followed by surgery at the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College from November 2014 to August 2017 were involved in this retrospective cohort study. The patients were divided into two groups based on the different time intervals between neoadjuvant therapy and surgery: 139 (60.2%) patients were in group A (≤ 9 wk), and 92 (39.2%) patients were in group B (> 9 wk). DFS and pathologic response were analyzed as the primary endpoints. The secondary endpoints were postoperative complications and sphincter preservation.

RESULTS

For the 231 patients included, surgery was performed at ≤ 9 wk in 139 (60.2%) patients and at > 9 wk in 92 (39.8%). The patients’ clinical characteristics, surgical results, and tumor outcomes were analyzed through univariate analysis combined with multivariate regression analysis. The overall pathologic complete response (pCR) rate was 27.2% (n = 25) in the longer time interval group (> 9 wk) and 10.8% (n = 15) in the shorter time interval group (≤ 9 wk, P = 0.001). The postoperative complications did not differ between the groups (group A, 5% vs group B, 5.4%; P = 0.894). Surgical procedures for sphincter preservation were performed in 113 (48.9%) patients, which were not significantly different between the groups (group A, 52.5% vs group B, 43.5%; P = 0.179). The pCR rate was an independent factor affected by time interval (P = 0.009; odds ratio [OR] = 2.668; 95%CI: 1.276-5.578). Kaplan-Meier analysis and Cox regression analysis showed that the longer time interval (> 9 wk) was a significant independent prognostic factor for DFS (P = 0.032; OR = 2.295; 95%CI: 1.074-4.905), but the time interval was not an independent prognostic factor for overall survival (P > 0.05).

CONCLUSION

A longer time interval to surgery after neoadjuvant therapy may improve the pCR rate and DFS but has little impact on postoperative complications and sphincter preservation.

Low ligation has a lower anastomotic leakage rate after rectal cancer surgery

BACKGROUND

For laparoscopic rectal cancer surgery, the inferior mesenteric artery (IMA) can be ligated at its origin from the aorta [high ligation (HL)] or distally to the origin of the left colic artery [low ligation (LL)]. Whether different ligation levels are related to different postoperative complications, operation time, and lymph node yield remains controversial. Therefore, we designed this study to determine the effects of different ligation levels in rectal cancer surgery.

AIM

To investigate the operative results following HL and LL of the IMA in rectal cancer patients.

METHODS

From January 2017 to July 2019, this retrospective cohort study collected information from 462 consecutive rectal cancer patients. According to the ligation level, 235 patients were assigned to the HL group while 227 patients were assigned to the LL group. Data regarding the clinical characteristics, surgical characteristics and complications, pathological outcomes and postoperative recovery were obtained and compared between the two groups. A multivariate logistic regression analysis was performed to evaluate the possible risk factors for anastomotic leakage (AL).

RESULTS

Compared to the HL group, the LL group had a significantly lower AL rate, with 6 (2.8%) cases in the LL group and 24 (11.0%) cases in the HL group (P = 0.001). The HL group also had a higher diverting stoma rate (16.5% vs 7.5%, P = 0.003). A multivariate logistic regression analysis was subsequently performed to adjust for the confounding factors and confirmed that HL (OR = 3.599; 95%CI: 1.374-9.425; P = 0.009), tumor located below the peritoneal reflection (OR = 2.751; 95%CI: 0.772-3.985; P = 0.031) and age (≥ 65 years) (OR = 2.494; 95%CI: 1.080-5.760; P = 0.032) were risk factors for AL. There were no differences in terms of patient demographics, pathological outcomes, lymph nodes harvested, blood loss, hospital stay and urinary function (P > 0.05).

CONCLUSION

In rectal cancer surgery, LL should be the preferred method, as it has a lower AL and diverting stoma rate.

Analysis of 72 patients with colorectal high-grade neuroendocrine neoplasms from three Chinese hospitals

BACKGROUND

Colorectal high-grade neuroendocrine neoplasms (HGNENs) are rare and constitute less than 1% of all colorectal malignancies. Based on their morphological differentiation and proliferation identity, these neoplasms present heterogeneous clinicopathologic features. Opinions regarding treatment strategies for and improvement of the clinical outcomes of these patients remain controversial.

AIM

To delineate the clinicopathologic features of and explore the prognostic factors for this rare malignancy.

METHODS

This observational study reviewed the data of 72 consecutive patients with colorectal HGNENs from three Chinese hospitals between 2000 and 2019. The clinicopathologic characteristics and follow-up data were carefully collected from their medical records, outpatient reexaminations, and telephone interviews. A survival analysis was conducted to evaluate their outcomes and to identify the prognostic factors for this disease.

RESULTS

According to the latest recommendations for the classification and nomenclature of colorectal HGNENs, 61 (84.7%) patients in our cohort had poorly differentiated neoplasms, which were categorized as high-grade neuroendocrine carcinomas (HGNECs), and the remaining 11 (15.3%) patients had well differentiated neoplasms, which were categorized as high-grade neuroendocrine tumors (HGNETs). Most of the neoplasms (63.9%) were located at the rectum. More than half of the patients (51.4%) presented with distant metastasis at the date of diagnosis. All patients were followed for a median duration of 15.5 mo. In the entire cohort, the median survival time was 31 mo, and the 3-year and 5-year survival rates were 44.3% and 36.3%, respectively. Both the univariate and multivariate analyses demonstrated that increasing age, HGNEC type, and distant metastasis were risk factors for poor clinical outcomes.

CONCLUSION

Colorectal HGNENs are rare and aggressive malignancies with poor clinical outcomes. However, patients with younger age, good morphological differentiation, and without metastatic disease can have a relatively favorable prognosis.

Intraoperative intraperitoneal chemotherapy increases the incidence of anastomotic leakage after anterior resection of rectal tumors

BACKGROUND

Intraoperative intraperitoneal chemotherapy is an emerging treatment modality for locally advanced rectal neoplasms. However, its impacts on postoperative complications remain unknown. Anastomotic leakage (AL) is one of the most common and serious complications associated with the anterior resection of rectal tumors. Therefore, we designed this study to determine the effects of intraoperative intraperitoneal chemotherapy on AL.

AIM

To investigate whether intraoperative intraperitoneal chemotherapy increases the incidence of AL after the anterior resection of rectal neoplasms.

METHODS

This retrospective cohort study collected information from 477 consecutive patients who underwent an anterior resection of rectal carcinoma using the double stapling technique at our institution from September 2016 to September 2017. Based on the administration of intraoperative intraperitoneal chemotherapy or not, the patients were divided into a chemotherapy group (171 cases with intraperitoneal implantation of chemotherapy agents during the operation) or a control group (306 cases without intraoperative intraperitoneal chemotherapy). Clinicopathologic features, intraoperative treatment, and postoperative complications were recorded and analyzed to determine the effects of intraoperative intraperitoneal chemotherapy on the incidence of AL. The clinical outcomes of the two groups were also compared through survival analysis.

RESULTS

The univariate analysis showed a significantly higher incidence of AL in the patients who received intraoperative intraperitoneal chemotherapy, with 13 (7.6%) cases in the chemotherapy group and 5 (1.6%) cases in the control group (P = 0.001). As for the severity of AL, the AL patients who underwent intraoperative intraperitoneal chemotherapy tended to be more severe cases, and 12 (92.3%) out of 13 AL patients in the chemotherapy group and 2 (40.0%) out of 5 AL patients in the control group required a secondary operation (P = 0.044). A multivariate analysis was subsequently performed to adjust for the confounding factors and also showed that intraoperative intraperitoneal chemotherapy increased the incidence of AL (odds ratio = 5.386; 95%CI: 1.808-16.042; P = 0.002). However, the survival analysis demonstrated that intraoperative intraperitoneal chemotherapy could also improve the disease-free survival rates for patients with locally advanced rectal cancer.

CONCLUSION

Intraoperative intraperitoneal chemotherapy can improve the prognosis of patients with locally advanced rectal carcinoma, but it also increases the risk of AL following the anterior resection of rectal neoplasms.

EGFP Expression Controlled by GFAP Promoter in Mesenchymal Cells: An Efficient Tool for Glial Lineage Selection and Transplantation

In order to demonstrate a new method to label and select enough glial cells from induced MSCs to provide cells for cell therapy, MSCs were induced with Beta-mercaptoethanol followed by retinoic acid, forskolin, basic-FGF, PDGF and heregulin. Induced MSCs were transfected with reconstructed vector pGFAP-EGFP by inserting GFAP promotor into pEGFP-N3 to substitute CMV promotor. Living cells against G418 were enriched and checked by flowcytometry. EGFP expressing cells were sorted and used for transplantation in vivo. Immunoelectronmicroscopy was accomplished using anti-EGFP to relocalize the transplanted cells. Almost all MSCs took on phenotypes of glial cells after induction, expressing S100 and GFAP. The EGFP expression rate of survived MSCs against G418 was 82.74%. Glial cells expressing EGFP accumulated mainly around the damaged nerve fibers. MSCs were relocalized by immunoelectronmicroscopy and remyelination was observed. EGFP expression controlled by GFAP promoter in mesenchymal cells was an efficient tool for glial lineage selection and transplantation. Induced MSCs can promote nerve regeneration by participating remyelination.

Study on the adoption of Schwann cell phenotype by bone marrow stromal cells in vitro and in vivo

OBJECTIVE

To explore the possibilities of bone marrow stromal cells (MSCs) to adopt Schwann cell phenotype in vitro and in vivo in SD rats.

METHODS

MSCs were obtained from tibia and femur bone marrow and cultured in culture flasks. Beta-mercaptoethanol followed by retinoic acid, forskolin, basic-FGF, PDGF and heregulin were added to induce differentiation of MSCs'. Schwann cell markers, p75, S-100 and GFAP were used to discriminate induced properties of MSCs' by immunofluorescent staining. PKH-67-labelled MSCs were transplanted into the mechanically injured rat sciatic nerve, and laser confocal microscopy was performed to localize the PKH67 labelled MSCs in the injured sciatic nerve two weeks after the operation. Fluorescence PKH67 attenuation rule was evaluated by flow cytometry in vitro.

RESULTS

MSCs changed morphologically into cells resembling primary cultured Schwann cells after their induction in vitro. In vivo, a large number of MSCs were cumulated within the layer of epineurium around the injured nerve and expressed Schwann cell markers, p75, S-100, and GFAP.

CONCLUSION

MSCs are able to support nerve fiber regeneration and re-myelination by taking on Schwann cell function, and can be potentially used as possible substitutable cells for artificial nerve conduits to promote nerve regeneration.

Purification of native myosin filaments from muscle

Analysis of the structure and function of native thick (myosin-containing) filaments of muscle has been hampered in the past by the difficulty of obtaining a pure preparation. We have developed a simple method for purifying native myosin filaments from muscle filament suspensions. The method involves severing thin (actin-containing) filaments into short segments using a Ca(2+)-insensitive fragment of gelsolin, followed by differential centrifugation to purify the thick filaments. By gel electrophoresis, the purified thick filaments show myosin heavy and light chains together with nonmyosin thick filament components. Contamination with actin is below 3.5%. Electron microscopy demonstrates intact thick filaments, with helical cross-bridge order preserved, and essentially complete removal of thin filaments. The method has been developed for striated muscles but can also be used in a modified form to remove contaminating thin filaments from native smooth muscle myofibrils. Such preparations should be useful for thick filament structural and biochemical studies.

Glucose transporter gene expression in bovine mammary gland

Transport of glucose across the plasma membrane of mammary epithelial cells is believed to be a passive process of facilitated diffusion mediated by facilitative glucose transporter(s). This article presents three lines of evidence that indicate the expression of sodium/glucose cotransporter (SGLT1) in the mammary gland of lactating and nonlactating cows. First, transcripts of SGLT1 mRNA ranging in size from 1.5 to 5.2 kb were detected in polyadenylated RNA preparations of mammary glands of lactating and nonlactating cows. Second, SGLT1 cotransporter protein was also detected in plasma membrane preparations of mammary glands of lactating cows. Third, partial amino acid sequence deduced from the reverse transcriptase-PCR fragment of SGLT1 from bovine mammary glands was similar to the sequence reported for ovine SGLT1. We conclude that mammary gland expression of SGLT1 mRNA and protein suggests that an active glucose transport system may be involved in glucose transport and metabolism in the mammary gland of dairy cows. However, the physiological significance of the expression of SGLT1 in mammary gland remains unknown.

Glucose transporter gene expression in lactating bovine gastrointestinal tract

Absorption of glucose from the intestine and probably from various portions of the gastrointestinal tract (GIT) in lactating dairy cows can have profound implications because the availability of glucose, or glucose precursors, seems to be a limiting factor for milk synthesis. This article reports on the expression of the Na+/glucose cotransporter gene (SGLT1) in mucosal tissues from rumen, omasum, abomasum, duodenum, jejunum, ileum, and cecum of lactating cows. Sodium/glucose cotransporter mRNA transcripts were detected in polyadenylated RNA of all the GIT tissues examined and in total RNA from rumen, omasum, duodenum, jejunum, ileum, and cecum. The pattern of SGLT1 mRNA distribution in these tissues was different from that of the facilitative glucose transporter GLUT5. Sodium/glucose cotransporter protein was also detected in small intestinal membranes of lactating dairy cows. Sodium-dependent glucose uptake across small intestinal brush border membrane vesicles could be resolved into linear nonsaturable (diffusion) and saturable, carrier-mediated components. The diffusion constant of glucose from jejunal membrane vesicles was 18.3+/-2.1 pmol x mM(-1) x mg protein(-1) x s(-1). The saturable component of glucose uptake had a Vmax of 27.1+/-5.8 pmol x mg protein(-1) x s(-1) and a Km of .12+/-.05 mM. Similar transport kinetics were found in the duodenum, and they were less in the ileum. These data suggest that the GIT of lactating cows is capable of active transport of glucose from the lumen across the brush border membrane of the epithelial cells. In addition, the relatively high abundance of SGLT1 mRNA in the rumen, omasum, and cecum may imply new functional and nutritional roles for these tissues in the active transport of glucose.

Pharmacokinetics of a Chinese traditional medicine, danshensu (3,4-dihydroxyphenyllactic acid), in rabbits using high-performance liquid chromatography

An injectable solution of Danshen was prepared and its in vivo disposition was examined in rabbits. The presence of Danshensu, one of the active components of Danshen, in the obtained solution was confirmed by a simple high-performance liquid chromatographic (HPLC) method. The pharmacokinetics of Danshensu in rabbits was evaluated by the HPLC method for plasma Danshensu. The calibration curve for Danshensu was linear (r = 0.998) over the concentration range of 0.25-40.0 micrograms/ml. The intra-assay coefficients of variation (CVs) were 3.8, 3.1, and 3.1% at 1, 10, and 50 micrograms/ml, respectively, and the inter-assay CVs were 5.3, 5.3, and 2.9% at 1, 10, and 50 micrograms/ml, respectively. The analytical recovery of Danshensu in plasma averaged 95.2%. From the plasma concentration profile of Danshensu after its intravenous administration, the t1/2, mean residence time (MRT), Vdss, and Cltot were determined as 32 min, 48 min, 149 ml/kg, and 3.13 ml/min/kg, respectively.

Regulation of the gene expression of glucose transporter in liver and kidney of lactating cows by bovine growth hormone and bovine growth hormone-releasing factor

Our objective was to study the effects of recombinant bovine growth hormone and bovine growth hormone-releasing factor on gene expression of glucose transporters in the liver and kidney of lactating cows. Primiparous cows received 29 mg/d of bovine growth hormone or 12 mg/d of bovine growth hormone-releasing factor by continuous intravenous infusion or no treatment (control) from 118 to 181 d postpartum. Growth hormone or growth hormone-releasing factor did not influence the mRNA abundance of the liver-type glucose transporter in the liver or kidney. Similarly, neither growth hormone-releasing factor nor growth hormone altered the mRNA abundance of the erythrocyte-type or the intestinal-type glucose transporter in the kidney, but large individual differences were observed in the mRNA abundance of the intestinal-type glucose transporter in liver.

Localization and gene expression of glucose transporters in bovine mammary gland

Glucose uptake in the mammary gland is a rate-limiting step in milk synthesis. To study glucose transporters in the bovine mammary gland, the erythrocyte-type glucose transporter (GLUT1) and the insulin-responsive glucose transporter (GLUT4) proteins were assessed by Western blotting and immunohistochemical staining, using polyclonal antibodies against the C-terminal peptide of GLUT1 and GLUT4. Our results demonstrated that the bovine mammary gland expressed a relatively high level of GLUT1 protein, whereas GLUT4 protein was not detected in the mammary gland of either lactating or dry cows. The absence of GLUT4 may indicate that glucose transport is not regulated by insulin in the lactating and dry bovine mammary gland. The anti-GLUT1 antibody strongly stained the single layer of epithelial cells of mammary alveoli. The expression of GLUT1 mRNA was similar in the mammary gland of late lactation and non-lactating cows. However, a smaller molecular weight species (38 kDa) of GLUT1 protein was detected in the mammary gland of non-lactating cows where its abundance in crude membrane preparation was 80% higher than in lactating animals. There were no significant differences in GLUT1 mRNA in bovine mammary gland at 118 d and 181 d postpartum, however, GLUT1 protein expression tended to be greater at 118 d postpartum.

Regulation of glucose transporter gene expression in mammary gland, muscle, and fat of lactating cows by administration of bovine growth hormone and bovine growth hormone-releasing factor

Primiparous cows received 29 mg of bovine growth hormone (bGH)/d, or 12 mg of bovine growth hormone-releasing factor (bGHRF)/d by continuous i.v. infusion, or no treatment (controls) from 118 to 181 d postpartum. Compared with controls, bGHRF and bGH did not influence the amount of erythrocyte-type glucose transporter (GLUT1) protein in the mammary gland; however, GLUT1 mRNA was increased (P < .01) by bGHRF, but not by bGH. The insulin-responsive glucose transporter (GLUT4) mRNA in skeletal muscle was decreased by 44% (P < .05) as a result of bGH treatment, but there was no significant effect of bGHRF. The GLUT4 mRNA was barely detectable in the omental fat of control cows and became undetectable in bGH-and bGHRF-treated cows. The results of the present study indicate that bGH and bGHRF may increase glucose availability to the mammary gland by regulating glucose transporter expression in skeletal muscle and omental fat. Our data also indicate that the galactopoietic action of bGHRF may not be mediated solely through GH.

Distribution of mammalian facilitative glucose transporter messenger RNA in bovine tissues

1. The complementary DNA for five human facilitative glucose transporters (GLUT1, GLUT2, GLUT3, GLUT4 and GLUT5) were used to determine the distribution of facilitative glucose transporter mRNA in bovine tissues by Northern blotting. Under high stringency hybridization conditions, a single 2.8 kb transcript of GLUT1 was seen in all bovine tissues examined except liver. Mammary gland had the highest abundance of GLUT1 mRNA. 2. Four GLUT2 transcripts of 6.3, 3.8, 2.2 and 1.6 kb were observed to be most abundant in liver, with lower abundance in kidney and duodenum. 3. Only a very low level of GLUT3 mRNA was detected in the mammary gland, skeletal muscle and duodenum. 4. Skeletal muscle contained the greatest abundance of GLUT4 mRNA, which was barely detectable in omental fat, kidney and mammary gland. 5. Transcripts of GLUT5 mRNA were detected in relatively high abundance in liver and kidney, and in lower abundance in the duodenum and mammary gland. 6. With the exception of the mammary gland, for which human data have not been reported, the distributions of GLUT1, 2 and 4 mRNA for the bovine tissues examined are similar to that reported for humans. On the other hand, the distributions of GLUT3 and 5 mRNA in the bovine differ from those reported for humans.

Accumulation of glutamate is regulated by calcium and protein kinase C in rat hippocampal slices exposed to ischemic states

There is now convincing evidence that excessive accumulation of the excitatory amino acid glutamate (Glu) in the extracellular space is toxic to neurons. However, the regulation of the release and uptake of Glu in producing this toxic concentration has not been adequately ascertained. The authors report that in hippocampal slices, the output of Glu significantly increased under in vitro ischemic states. Glu in the extracellular space increased fivefold. Since daurisoline, a drug that blocks N-type Ca2+ channels, or Ca(2+)-free solution potently and effectively lowered this stimulated output, it was hypothesized that the Glu output is mediated by Ca2+ influx in nerve terminals. When the slices were incubated for 30 minutes under ischemic state, daurisoline caused only small alterations in the postischemic accumulation of Glu. However, Glu accumulation was markedly attenuated by H-7, but not by calmidazolium, facilitated by PDB whereas 8-bromo-cAMP was without effect. It appears therefore that during a 30-minute ischemic insult, protein kinase C (PKC) was involved in the Glu accumulation of supernatant. A direct demonstration of this concept was obtained by showing significant increases in PKC activation in presynaptic nerve terminals (from 1.34 +/- 0.1 to 9.34 +/- 0.89 U) following 30 minutes of ischemia. DNQX, a non-NMDA receptor antagonist, potently reduced PKC activities and decreased extra Glu accumulation. Also observed was the inhibition of 1-[3H]-Glu uptake into synaptosomes by PDB. These results provide direct evidence that Ca2+ influx enhances Glu release, which in turn leads to inhibition of its reuptake, and is coupled with PKC activities in presynaptic nerve terminals.

Effects of Ca2+ antagonists on glutamate release and Ca2+ influx in the hippocampus with in vivo intracerebral microdialysis

1. The extracellular glutamate content and Ca2+ level in vivo in rat hippocampus were measured by brain microdialysis following administration of two depolarizing agents (veratridine, KCl) and quinolinic acid (Quin). 2. The two depolarizing agents increased the extracellular glutamate level (to between 280 and 320% basal) and decreased the extracellular Ca2+ content (to 48% of basal). However, Quin did not change the glutamate level but decreased the Ca2+ content. 3. The effects of Ca2+ antagonists on the changes of glutamate and Ca2+ level were evaluated in this experimental model. At a dose of 0.5 mg kg-1, i.v., nimodipine (L-type channel blocker) did not produce significant changes in the stimulated-glutamate release. A statistically significant inhibition of Ca2+ influx was observed at a dose of 0.05 mg kg-1. In contrast, in those animals receiving the N-type Ca2+ antagonist, daurisoline (0.1, 1 or 5 mg kg-1, i.v.), a potent attenuation of both glutamate release and Ca2+ influx was found. 4. We propose that the pharmacological properties of Ca2+ influx and of neurotransmitter release differ and that nimodipine-sensitive L-type channels may not be very common in nerve terminals but are localized in cell soma. Daurisoline-sensitive N-type channels in nerve terminals have a much greater influence on excitatory amino acid release.

Effects of nimodipine on l-glutamate-induced seizures and Ca2+ influx in hippocampus in freely moving rats

Seizure (EEG) was studied in rats unilaterally injected in the dorsal hippocampus with l-glutamate (Glu). Extracellular Ca2+ content [(Ca2+)e] in the injected area was assessed by brain microdialysis coupled to automatic atomic absorption spectrophotometry. In this experimental epileptic model, an inhibition of Glu-stimulated epileptic activity and a fall in (Ca2+)e by nimodipine (Nim, 100 micrograms.kg-1) were seen. The spike- and wave-burst frequency was reduced from 30 to 5 bursts.min-1 (P less than 0.01, n = 8). Nim 25 and 50 micrograms.kg-1, without anticonvulsant activity, did not prevent the drop in (Ca2+)e. These results indicate that Nim exerts an antiepileptic effect on Glu-induced epilepsy. The mechanisms may be involved in blocking Ca2+ influx into neurons.