Extracellular superoxide dismutase, a potential extracellular biomarker candidate for prolactinoma

AIM

To investigate whether the extracellular superoxide dismutase (EC-SOD) and manganese superoxide dismutase (Mn-SOD) level changes during prolactinoma (PRL) development.

METHODS

Surgical tissues from 37 female patients with PRL were tested for Mn-SOD and serum samples from such PRL patients were tested for EC-SOD level changes with Western Blot. The MnSOD level from blood cells was also investigated to show whether the Mn-SOD variation could locate tumorigenesis tissues.

RESULTS

According to the patients' age analysis, age 20-40 years is high risk for getting PRL. There is a positive relationship between the PRL severity and EC-SOD. The Mn-SOD level from surgical tissues, but not blood cells, also shows a corresponding positive relationship to PRL severity, which indicates that elevated Mn-SOD might only happen in PRL tumorigenesis tissues.

CONCLUSIONS

Extracellular superoxide dismutase is an extracellular protein and the serum EC-SOD could be a good candidate for the diagnoses of prolactinoma.

Study of HIV/AIDS-related knowledge among junior high-school students in Shanghai, China

The aim of this study was to assess the HIV/AIDS-related knowledge among junior high-school students in Shanghai, China, and the factors influencing this knowledge. A cross-sectional study was conducted in 20 middle schools of two districts by a cluster-stratified selection procedure in Shanghai, China. The 2432 sampled students, aged from 11.1 to 16.7 years, completed a self-administered questionnaire of HIV/AIDS prevention. The results showed that the overall correct rate of HIV/AIDS-related knowledge was 62%. Using multivariable logistic regression analysis, we found that the main factors influencing HIV/AIDS-related knowledge among junior high school students were the type of school (odds ratio [OR] = 1.641), age (OR = 1.727), whether the student was a single child in the family (OR = 1.389), whether the student had previous HIV/AIDS-related education experience (OR = 2.003) and whether the student had ever discussed HIV/AIDS with their parents (OR = 1.282). The results indicate that HIV/AIDS-related knowledge among Shanghai junior high school students is not high enough, and more attention needs to be paid to enhance HIV/AIDS-related knowledge, especially among younger students from common type schools without HIV/AIDS-related education experience. We encourage Chinese parents to get involved in their children's HIV/AIDS prevention education.

Phosphorylation of Mps1 by BRAFV600E prevents Mps1 degradation and contributes to chromosome instability in melanoma

Activating BRAF mutations that deregulate the mitogen-activated protein kinase (MAPK) pathway commonly occur in cancer. BRAF(V600E) induces centrosome amplification and spindle abnormalities that result in aneuploidy. We find modification of Mps1 is critical for contributing to centrosome amplification and chromosome instability induced by BRAF(V600E). Phosphorylation of Mps1 at residue S281 induced by BRAF(V600E) stabilizes Mps1 protein by preventing its ubiquitination by APC/C and subsequent degradation, allowing the non-degraded protein to accumulate at centrosomes. Cells in which endogenous Mps1 was replaced with a phospho-mimetic Mps1 mutant are viable but amplify centrosomes and missegregate chromosomes frequently. Importantly, analysis of tumor micro arrays revealed that phospho-MAPK and S281-phosphorylated Mps1 were highly correlated in human melanoma tissues, implying that MAPK contributes to defects in the degradation of Mps1 in situ. We propose that continuously activated BRAF(V600E) signaling may be a possible mechanism for the deregulation of Mps1 stability and kinase activity in human tumors, and that persistent phosphorylation of Mps1 through BRAF(V600E) signaling is a key event in disrupting the control of centrosome duplication and chromosome stability that may contribute to tumorigenesis. Our findings raise the possibility that targeting the oncogenic BRAF and S281-phosphorylated Mps1, especially when used in combination could potentially provide great therapeutic opportunities for cancer treatment.

Abstract PD09-08: Obesity in Long-Term Disease Free Survivors of Invasive Breast Cancer

Background: As the number of breast cancer survivors increases due to improvements in screening and treatment for breast cancer, there is a particular interest in identifying lifestyle factors associated with long-term survival. Obesity may be one of the modifiable risk factors that can play a role in the outcome of breast cancer patients however studies shown controversial results. Besides, little is known about the role of obesity in long-term survivors. The objective of this study is to examine the role of obesity in breast cancer patients who remained disease free at least 5 years after diagnosis.

Methods: We reviewed the medical records of all women with invasive breast cancer diagnosed at LSUHSC between 1980 and 2005. The patients with stage IV breast cancer at diagnosis were excluded from the analysis. For this study we selected patients whom were disease free at least five years after the breast cancer diagnosis. We classified our patients by body mass index (BMI) at the time of breast cancer diagnosis into: normal weight (BMI <25 kg/m2), overweight (BMI 25-29 kg/m2), and obese (BMI >30 kg/m2). Data on demographics clinical characteristics, tumor characteristic, breast cancer therapy, and relapse were analyzed within BMI classes. Results: A total of 967 patients were diagnosed with invasive breast cancer between 1980 and 2005. Out of those 49% were African American, 29% were overweight, and 49% were obese. From this population 597 (62%) patients were disease free more than 5y: 217 (49%) obese, 113 (26%) overweight, 112 (25%) normal weight. Obese breast cancer survivors in comparison to overweight and normal weight survivors were more likely to: be African American (61%, P<0.01), received Medicaid coverage (14.2%, p=0.05) and to have lower rates of mastectomy (p=0.017). There was not difference in tumor characteristics (ER status, Nodal status, Tumor size) and adjuvant treatment (chemotherapy, radiotherapy and hormonal therapy) between obese and non-obese patients. One hundred and ten patients (19%) developed a recurrence 5 years after diagnosis (48 obese and 33 overweight): 65 local (48 obese and 33 overweight) and 45 systemic (21 obese and 10 overweight).

Discussion: Our study has some limitations typical of retrospective studies and the generalization of the results may be limited. Our analysis suggests that in long-term disease free survivors obesity and race might be associated. To further clarify the role of obesity in long-term breast cancer survivors prospective studies with long term follow up are warranted.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD09-08.

Abstract P6-09-07: Obesity; Not Associated with Risk of Second Malignancy in Early Stage Breast Cancer

Introduction: Early diagnosis and effective local and systemic therapy has reduced the risk of relapse and death from breast cancer; thus, patients are living longer but experience an increased risk for the development of a second malignancy (SM). Risk factors for SM may be genetic, related to environmental or behavioral factors or to breast cancer treatments such as radiotherapy, chemotherapy or hormone therapy. Controversy exists over the role of obesity and breast cancer outcomes, and there is little information on long term survivors. LSUHSC Shreveport provides care for a predominantly indigent population with high rates of obesity. This allows us to study the role of obesity and risk of SM after breast cancer diagnosis. In this study, we sought to determine the incidence and risk factors for SM in women after treatment for early stage breast cancer. Methods: We performed a retrospective analysis of all patients treated for invasive breast cancer from 1980 through 2006 at LSUHSC Shreveport. Patients with stage IV at diagnosis were excluded. Second malignancy was defined as a new diagnosis of primary malignancy at least three months after initial breast cancer diagnosis. We reviewed the demographics, smoking status, BMI at diagnosis of breast cancer, tumor characteristics, breast cancer treatments (surgery, radiotherapy, chemotherapy and hormonal therapy) and site and date of second malignancies. Descriptive statisticswere performed to characterize the group of patients who developed a SM and Cox proportional hazard regression model was used to estimate the relative risk of development of SM.

Results: Of the 1214 patients analyzed, 118 (9.72%) patients developed a SM: 54% (n=64) breast cancer, 12.7% (n=15) gynecologic cancer, 8.5% (n=10) GI malignancy, 6.8% (n= 8) lung cancer, 6.8% (n=8) hematologic malignancy and 11% (n=13) various miscellaneous cancers. The median time for the development of SM was 7.6 years. The risk for development of SM increased with longer follow up: the risk at 5 years after breast cancer diagnosis was 2.3%, at 10 years was 10% and at 20 years was 30%. Patients with SM in comparison with patients without it were more likely to be obese (57%, p=0.05) and to have received radiotherapy (60%, p=0.01). No differences were observed with age at diagnosis, race, smoking status, use of chemotherapy, ER status, or use of hormone therapy. In a multivariate analysis using the Cox regression model, after adjusting for race, age, smoking status, use of chemotherapy and ER status, radiotherapy was a significant predictor of SM (HR=2.8, p=0.01). Obesity was not associated with an increased risk of SM (HR=0.91, p=0.82). Conclusions: Our study has some limitations typical of retrospective studies and the generalization of the results may be limited. We found that obesity at diagnosis of breast cancer did not adversely affect the rate of SM while radiotherapy represents a significant risk factor. Further studies are needed to define the role of lifestyle and cancer treatments on develop of SM in patients with early stage breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-09-07.

Anti-acrolein treatment improves behavioral outcome and alleviates myelin damage in experimental autoimmune encephalomyelitis mouse

Oxidative stress is considered a major contributor in the pathology of multiple sclerosis (MS). Acrolein, a highly reactive aldehyde byproduct of lipid peroxidation, is thought to perpetuate oxidative stress. In this study, we aimed to determine the role of acrolein in an animal model of MS, experimental autoimmune encephalomyelitis (EAE) mice. We have demonstrated a significant elevation of acrolein protein adduct levels in EAE mouse spinal cord. Hydralazine, a known acrolein scavenger, significantly improved behavioral outcomes and lessened myelin damage in spinal cord. We postulate that acrolein is an important pathological factor and likely a novel therapeutic target in MS.

Evaluation of a school-based HIV/AIDS peer-led prevention programme: the first intervention trial for children of migrant workers in China

The effectiveness of a peer-led education intervention in HIV/AIDS prevention was assessed in the Chinese children of migrant workers. A prospective study was conducted in 12 junior high schools for migrant children. Among the intervention group, a peer-education-based HIV/AIDS prevention was implemented for three months. The results during the baseline survey indicated that the level of knowledge on HIV/AIDS was lower in children of migrant workers. After three months of peer-led intervention, compared with the control group, students in the intervention group positively increased their HIV/AIDS-related knowledge, modified their attitude and improved their protection self-efficacy. Compared with attitude, intervention was more effective in the improvement of knowledge and protection self-efficacy, especially knowledge. The findings suggest that peer-led education was an effective method in improving knowledge, attitude and protection self-efficacy in Chinese children of migrant workers. Heightened concerns targeting the group students were particularly necessary, given their lower level of related knowledge and vulnerability to HIV infection.

HIV/AIDS education effects on behaviour among senior high school students in a medium-sized city in China

Few studies have examined the long-term effects of peer-led HIV prevention in Chinese adolescents. A two-year follow-up study was conducted among senior high school students in a medium-sized city of Fujian Province, from 1 March 2006 to 30 April 2008. In all, 3068 students from 14 schools were invited in March 2006, and 893 students in five schools were followed up. Data were collected at baseline, right after intervention (one month later) and two years later by a self-administered questionnaire. In the intervention group, the average knowledge score including reproductive health and HIV/AIDS/sexually transmitted diseases rose from 4.30 to 7.06 one month later (P < 0.01) and to 7.08 two years later (P < 0.01). There was no significant difference between the average knowledge score after one month and two years (P > 0.05). Sustained increases were found in the attitude scores towards people living with HIV/AIDS (PLWH) and intention of condom use after intervention. The study indicates that peer-led HIV prevention education succeeds in improving and sustaining HIV/AIDS-related knowledge and some behaviour intentions. Future research should focus on strategies to sustain long-term behaviour change.

Pretreatment with calcitonin gene-related peptide attenuates hepatic ischemia/reperfusion injury in rats

OBJECTIVE

Oxygen free radicals and apoptosis play important roles in liver ischemia/reperfusion (I/R) injury. We sought to investigate the protective effect of calcitonin gene-related peptide (CGRP) to attenuate liver I/R injury due to oxygen free radicals and apoptosis.

MATERIALS AND METHODS

Harvested rat livers were perfused via the portal vein with 60 mL of 4 degrees C histidine-tryptophan-ketoglutarate (HTK) solution alone in the control group, or with the same solution containing CGRP (3 microg/10 g body weight) in the experimental group. After 24 hours of cold storage, hepatic enzyme leakage, portal venous pressure, oxygen consumption, total adenine nucleotides (TAN), bile production, lipoperoxide (LPO) release, apoptosis, and histochemical changes were evaluated upon 45 minutes of isolated reperfusion.

RESULTS

Compared with control livers, CGRP-treated organs showed significantly decreased alanine aminotransferase (ALT) and glutamate-lactate dehydrogenase (GLDH) leakage and portal venous pressure (2.0 +/- 0.3 vs 4.0 +/- 0.4 mmHg; P < .01), with significantly increased bile production (8.56 +/- 0.76 vs 3.34 +/- 0.68 microL/g/45 min; P < .01), oxygen consumption (5.14 +/- 0.4 vs 2.57 +/- 0.2 microL/g/min; P < .01), and total adenine nucleotides (TAN) (11.1 +/- 0.71 vs 7.02 +/- 0.53 micromol/g; P < .01) upon reperfusion as signs of recovered viability. We observed infrequent positive terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling (TUNEL) staining, especially in sinusoidal lining cells (SLC). The percentage of TUNEL-positive cells in the CGRP group was significantly decreased compared with the control group: (4.1 +/- 0.67 vs 8.0 +/- 1.27; P < .05). Perfusate levels of low molecular weight (LMW) histone-associated DNA fragments (0.36 +/- 0.04 vs 0.53 +/- 0.06 AU; P < .05) were also decreased, coupled with strong 5'-nucleotidase (5'-NT) and LDH activity staining concentrated on the endothelial cells. LPO release in the perfusate was largely decreased: (0.12 +/- 0.02 vs 0.36 +/- 0.04 nmoL/g, P < .01).

CONCLUSION

CGRP ameliorated liver I/R injury due to reactive oxygen species and apoptosis.

HIV/AIDS-related knowledge, sources and perceived need among senior high school students: a cross-sectional study in China

This study aimed to assess HIV/AIDS-related knowledge, sources and perceived need among senior high school students in China. A total of 2668 senior high school students aged 15.17–23.42 years participated in the survey. A self-administered questionnaire was used to collect information on HIV/sexually transmitted infection-related knowledge, sources and perceived information need. The results showed that levels of HIV/AIDS knowledge were distributed as follows: low for 6.8%, moderate for 29.6% and high for 63.7%. The most important information sources were, in rank order, TV/photographic recording (72.1%), school heath education curriculum (51.8%) and reading materials (45.7%). About half of the students, 46.3%, confirmed a need for more information and 87.8% of the sampled senior high school students communicated with others if he/she had problems related to HIV/AIDS. Strengthening and improving information sources, particularly its accuracy and comprehensiveness, would help in ensuring that adolescents obtained the HIV/AIDS health information they needed.

Survey on the function, structure and operation of hospital ethics committees in Shanghai

OBJECTIVE

The objectives of this study are to understand the current functions, structure and operation of hospital ethics committees (HECs) in Shanghai and to facilitate their improvement.

METHODS

(1) A questionnaire survey, (2) interviews with secretaries and (3) on-site document reviews of HECs in Shanghai were used in the study, which surveyed 33 hospitals.

RESULTS

In Shanghai, 57.56% of the surveyed hospitals established HECs from 1998 to 2005. Most HECs used bioethical review of research involving human subjects as well as bioethical review or consultation regarding medical care services and administrative decision- making. Of the surveyed HECs, 14.3% did not provide any formal bioethical training to the HECs' members and many HECs had no standard operating procedures. Some HECs had no clear definition of what was "conflict of interest" that should be considered by the HECs, while 44.4% of the HECs did not perform continuing review.

DISCUSSION

After the issues of related national regulations, more and more hospitals established HECs in Shanghai, but the functions of HECs need to be further developed and formal training on bioethics should be provided to HEC members. To assure the independence and good performance of HECs, the conflict of interest procedure, the standard operating procedures and bioethical review should be improved.

CONCLUSION

HECs in Shanghai had developed in the preceding 10 years and they played great roles in protecting the rights and welfare of human subjects and patients; some areas need improvement.

Evaluation of thymoquinone (TQ) as an antiproliferative, proapoptotic, and immunomodulatory agent in a non-small cell lung cancer cell (NSCLC) line

e14644

Background: NSCLC is the most common cause of cancer death worldwide. We performed in vitro testing of Thymoquinone (TQ), a derivative of black caraway seed against NSCLC cell line NCI-H460 Methods: Cells were grown in RPMI and were plated at a density of 5,000 cells per well in a 96 well plate and cell growth determined in the presence of 80 and 100μM of TQ dissolved in DMSO with appropriate solvent only as control. Cell proliferation was determined at 24, 48 and 72 hrs intervals using 3-(4,5-dimethyltiazol 2-yl)-2,5-diphenyltetraolium bromide (MTT) assay. Factorial analyses of variance (ANOVA) were used to determine the effect of TQ and control with the time. Student-Newman-Keuls test was used to determine statistical significance with P value <0.05 considered significant. Apoptosis was detected using Annexin V-FITC Aptosis Detection Kit analyzing the effects of TQ at 24 hrs after treatment by flow cytometry. The immunomodulatory effects of TQ were tested using RayBio Human Cytokine Antibody Array C series 200. NCI-H460 cells (50,000 cells per well in duplicate 6 well plates) were grown in serum free RPMI media. 24 hrs after treatment with TQ or DMSO media was collected and analyzed for expression of various cytokines. Results: The MTT assay showed that TQ at 80 and 100 μM significantly inhibited cell growth as compared to control and at 24 hrs for example, 100 μM TQ inhibited cell growth by 78%. Apoptosis occurred rapidly after treatment with TQ with 73.5% of cells being positive for expression of Annexin-V as detected by flow cytometry after 24 hrs of exposure to TQ as compared to 2.6% of controls. The cytokine array revealed that TQ significantly decreased expression of ENA-78(Epithelial neutrophil activating peptide), and GRO (Growth related oncogene).ENA-78 is correlated with vascularity and tumor growth in NSCLC tumor, whereas GRO is associated with neoangiogenesis. Conclusions: TQ is shown to be a powerful anti-proliferative, pro-apoptotic and anti- angiogenic agent in a NSCLC cell line.

No significant financial relationships to disclose.

Effect of insurance status and distance from treatment center on the overall survival of patients with non-small cell lung caner treated in an academic center

e17557

Background: A large proportion of patients withcancer treated in academic centers do not have insurance and they travel from far distances to get medical care. We have retrospectively analyzed the outcome of 230 patients with non small cell lung caner in our cancer center and evaluated the effect of insurance status and their distances from our center on overall survival. These patients have traveled from many different regional cities to our center since mid-1996 to November 2008. Methods: We have performed a multivariate analysis on 230 patients with all stages of non small cell lung cancer correcting for sex, race, age, comorbidity, stage of cancer, body mass index, histology, chemotherapy, performance status, smoking history, distance from our center and insurance status. The distance ranged from 0.4 to 343 miles with mean of 69 (standard deviation of 71) . Age ranged from 30 to 89 with a mean number of 57 (standard deviation of 10).Insurance status was divided into 3 categories of no insurance, medicaid and with insurance. Chi square test was used to compare the distribution of the stages of lung cancer patients with other categorial variables. The log rank test was used to compare the survival of different categorical variables and Cox proportional regression was used for multivariate analysis of overall survival. Results: There were no statistical significant differences on overall survival considering distance of travel or insurance status.(P value for distance was 0.505 and for insurance it was 0.648). Smokers and patients with a poor performance status (ECOG 3 and 4) had a statiatically significant worse overall survival. (P value for smoking was 0.0036 and p value for ECOG equal or above 4 was <0.0001). Conclusions: The results from our study indicate that travel distance and payer status do not effect overall survival in lung cancer patients at our center.

No significant financial relationships to disclose.

Effectiveness of peer education in HIV/STD prevention at different types of senior high schools in Shanghai, People's Republic of China

The epidemic of HIV/AIDS greatly threatens Chinese youth. Our study was intended to examine the effectiveness of the peer education method in HIV/AIDS prevention in different types of senior high schools in Shanghai. A peer education intervention was conducted in 10 different types of senior high schools, including three key senior schools, four ordinary senior schools and three vocational schools in Shanghai for three months. A cohort of 1910 students was surveyed (n=976 intervention group, n=934 control group) through anonymous questionnaires, both pre- and postintervention. There were significant differences in the results among these different types of senior schools. Peer education is an efficient method of increasing the knowledge of AIDS/sexually transmitted diseases in senior school students. However, the contents and the schedule should be different between different types of schools, and students in vocational schools require more health education.

Long-term follow-up study on peer-led school-based HIV/AIDS prevention among youths in Shanghai

SUMMARY

The HIV/AIDS epidemic is a major problem around the world and an increasing percentage of new HIV cases is reported to be by sexual transmission. Many studies have been carried out in the field of peer education on HIV/AIDS among young people, however, few studies focused on the long-term effect of this education. To evaluate both the short- and long-term effects of the peer education programme, we conducted a follow-up study to evaluate the related knowledge, attitudes and behaviour intention to HIV/AIDS among senior high-school students in Shanghai, China. We selected 1950 students from 10 senior high schools in Shanghai, from whom 968 students were selected at random for the intervention group and 982 students for the control group. The same questionnaires were carried out before intervention, one month and one year later in both the groups. In the intervention group, the knowledge score of reproductive health, HIV/AIDS and sexually transmitted disease rose from 21.66 to 31.72 one month later (P < 0.001). After one year it was still 30.97, and there was no significant difference between one month and one year (P > 0.05). The behaviour intention to HIV/AIDS prevention, such as condom use during sexual intercourse also changed before and after the intervention. After both the one month and one-year follow-up intervention, we found that more students declared that they would use condoms during sexual intercourse when compared with the control group (P < 0.001). No change was seen in either knowledge or behaviour intention in the control group. These results showed that peer education on HIV/AIDS prevention among high-school students is both effective in promoting knowledge and in changing behaviour intention long term.

Obesity a significant risk factor for contralateral breast cancer ocurrence

Abstract #6097

Background: The health consequences of obesity are significant and it's effect on breast cancer outcomes are now being recognized. Several risk factors for contralateral breast cancer recurrence included age, lobular histology, genetic abnormalities and no prior adjuvant systemic therapy. This study's objective was to define the risk of contralateral breast cancer in obese patients following treatment for primary breast cancer.&#x2028; Methods: The electronic medical records of pts with histologically proven invasive breast cancer diagnosed between 1981 from 2006 were reviewed. Patients with Stage IV at diagnosis were excluded. Intrammamary breast cancer recurrence was defined as a new diagnosis of invasive or in-situ breast cancer at least 6 months after the diagnosis of primary invasive breast cancer, and it was classified as ipsilateral or contralateral breast cancer. Data on insurance, race, body mass index at diagnosis (BMI) and disease free interval (DFI) was analyzed. National Institutes of Health criteria was used to stratify pts as obese (BMI &gt;30 kg/m2). Differences in DFI were analyzed by BMI.&#x2028; Results: Of the 647 pts who were diagnosed with invasive breast cancer, 72 pts (11%) had intrammamary breast cancer recurrence, (28 ipsilateral and 44 contralateral). Pts with contralateral breast cancer in comparison with pts with ipsilateral breast cancer were more likely to be obese at diagnosis (64% vs 25%; p=0.001), to have a higher mean age at diagnosis (51 years vs 46 years; p=0.04) and to have primary breast cancer with ER positive status (67% vs 39%; p=0.05). In univariate analysis, obesity is a significant predictor of contralateral breast cancer. (HR =1.97; p=0.04). In multivariate analysis using Cox regression model, after adjusting for race, menopausal status, stage and SES, age at diagnosis and BMI remain statistically significant predictors for contralateral breast cancer (age at diagnosis: HR=1.09; p=0.006; BMI: HR=4.9; p=0.004).&#x2028; Conclusions: In this relatively small patient group, obesity represent a significant risk factor for contralateral breast cancer occurrence. Additional studies are needed to further define the impact of obesity in breast cancer outcomes.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6097.

Correlations between clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in the cardiac Na+ channel

Aim:

We compared the clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in domain II (S5-S6) of human, hNa_v1.5, cardiac Na⁺ channels.

Methods:

Full clinical evaluation of pedigree members through three generations of a Chinese family combined with SCN5A sequencing from genomic DNA was compared with patch and voltage-clamp results from two independent expression systems.

Results:

The four mutation carriers showed bradycardia, and slowed sino-atrial, atrioventricular and intraventricular conduction. Two also showed sick sinus syndrome; two had ST elevation in leads V1 and V2. Unlike WT-hNa_v1.5, whole-cell patch-clamped HEK293 cells expressing R878C-hNa_v1.5 showed no detectable Na⁺ currents (i_Na), even with substitution of a similarly charged lysine residue. Voltage-clamped Xenopus oocytes injected with either 0.04 or 1.5 μg μL⁻¹ R878C-hNa_v1.5 cRNA similarly showed no i_Na, yet WT-hNa_v1.5 cRNA diluted to 0.0004–0.0008 ng μL⁻¹resulted in expression of detectable i_Na. i_Na was simply determined by the amount of injected WT-hNa_v1.5: doubling the dose of WT-hNa_v1.5 cRNA doubled i_Na. i_Na amplitudes and activation and inactivation characteristics were similar irrespective of whether WT-hNa_v1.5 cRNA was given alone or combined with equal doses of R878C-hNa_v1.5 cRNA therefore excluding dominant negative phenotypic effects. Na⁺ channel function in HEK293 cells transfected with R878C-hNa_v1.5 was not restored by exposure to mexiletine (200 μm) and lidocaine (100 μm). Fluorescence confocal microscopy using E3-Nav1.5 antibody demonstrated persistent membrane expression of both WT and R878C-hNa_v1.5. Modelling studies confirmed that such i_Na reductions reproduced the SSS phenotype.

Conclusion:

Clinical consequences of the novel R878C mutation correlate with results of physiological studies.

4-Aminopyridine derivatives enhance impulse conduction in guinea-pig spinal cord following traumatic injury

4-Aminopyridine (4-AP), a potassium channel blocker, is capable of restoring conduction in the injured spinal cord. However, the maximal tolerated level of 4-AP in humans is 100 times lower than the optimal dose in in vitro animal studies due to its substantially negative side effects. As an initial step toward the goal of identifying alternative potassium channel blockers with a similar ability of enhancing conduction and with fewer side effects, we have synthesized structurally distinct pyridine-based blockers. Using isolated guinea-pig spinal cord white matter and a double sucrose gap recording device, we have found three pyridine derivatives, N-(4-pyridyl)-methyl carbamate (100 microM), N-(4-pyridyl)-ethyl carbamate (100 microM), and N-(4-pyridyl)-tertbutyl (10 microM) can significantly enhance conduction in spinal cord white matter following stretch. Similar to 4-AP, the derivatives did not preferentially enhance conduction based on axonal caliber. Unlike 4-AP, the derivatives did not change the overall electrical responsiveness of axons to multiple stimuli, indicating the axons recruited by the derivatives conducted in a manner similar to healthy axons. These results demonstrate the ability of novel constructs to serve as an alternative to 4-AP for the purpose of reversing conduction deficits.