Site-specific mutagenesis of the catalytic subunit of cholera toxin: substituting lysine for arginine 7 causes loss of activity.

Cholera and pertussis toxins each contain a subunit with ADP-ribosyltransferase activity, sharing a region of nearly identical amino acid sequence near the NH2 terminus. Previous investigations have shown that substitution of a lysine residue for Arg-9 in the catalytic A subunit of pertussis toxin substantially eliminates its enzyme activity. We now report that substitution of lysine for the position-equivalent Arg-7 of cholera toxin subunit A leads to a similar loss of catalytic activity. This result suggests a correlation of function with structure between the sequence-related cholera and pertussis toxin A subunits and may contribute to the design of a vaccine containing an enzymatically inert analog of cholera toxin.     

15The effect of Lower Esophageal Sphincter (LES) electrical stimulation on LES pressure

Background: Electrical stimulation (ES) of the stomach has been shown to modulate LESP. Electrical stimulation, using neural high frequency stimulation (NGES) can induce contractions of the smooth muscle of the gut. The purpose of this study was to determine if electrical stimulation of the LES can affect LESP. Methods: Four female hound dogs, weight: 20–25 kg, underwent an esophagostomy that allowed the introduction of a sleeve manometry catheter into the esophagus. They were also implanted with a pair of electrodes along the longitudinal axis of the LES. After 3 weeks of recovery, they underwent esophageal manometry recording during control and ES, performed randomly on separate days, using 4 different stimulations: 1‐Low frequency: freq: 6 cycles/min, pulse: 350 milisec, amp: 5 mAmp; 2 High‐frequency: freq: 50 Hz, pulse: 1 milisec, amp: 5 mAmp; 3‐ NGES: freq: 50 Hz, pulse:20 milisec, amp:10 volts; 4‐ High‐frequency, circular: freq: 20 Hz, pulse:1 milisec, amp:5 mAmp. All recordings were performed 1 hour after consumption of 3 ounces of canned dog food, to prevent fluctuations in LESP and under mild sedation (acepromazine 0.5 mg kg^­1). Tests consisted, during ES days, of 3 periods of 20 minutes each: control , stimulation and post stimulation. The effect of NGES was also tested under anesthesia and following administration of L‐NAME 50 mg kg^­1 IV. and also atropine 0.05 mg kg^­1 IV. Analysis: area under the curve (AUC) and pressure were compared among the 3 periods. Data shown as mean ± SD, ANOVA and t‐test, p < 0.05. Results: Sustained increase in LESP was observed during low frequency stimulation, 32.1 ± 12.8 vs. 42.4 ± 18.0 vs. 50.1 ± 23.6, control vs. stimulation vs. post stimulation respectively, p = 0.013. AUC also significantly increased during and after stimulation, 39,320.3 ± 15,722 vs. 51,294 ± 21,826 vs. 59,823.6 ± 28,198.4 mmHgxsec, control vs. stimulation vs. post stimulation respectively, p = 0.01. There was no significant change with other types of ES. NGES induced an initial rise in LESP followed within few seconds by relaxation with slow resumption of pressure over a 1 minute period. L‐NAME increased LESP and augmented the initial rise in LESP following NGES but markedly diminished or abolished the relaxation phase. Atropine lowered LESP and abolished the initial rise in LESP induced by NGES. Conclusions: Low frequency ES of the LES increases LESP in conscious dogs. NGES has dual effect on LESP: an initial stimulation, cholinergically mediated, followed by relaxation mediated by nitric oxide.     

Safety trial with the 5HT1B/1D agonist avitriptan (BMS-180048) in patients with migraine who have experienced pressure, tightness, and/or pain in the chest, neck, and/or throat following sumatriptan

We investigate whether symptoms of pressure, tightness, and/or pain in the chest, neck, and/or throat after administration of the 5HT_1B/1D agonist avitriptan were associated with objective impairment of the myocardial function on 12-lead electrocardiogram (ECG), continuous ECG (Holter) monitoring, and echocardiography. Migraine sufferers who in two-thirds of alt attacks treated with sumatriptan had experienced chest/throat/neck symptoms were chosen for study. Baseline measures included vital signs, a 12-lead ECG and an echocardiogram. Patients ( n =51) who had no clinically significant abnormality at baseline received a high dose (150 mg) of avitriptan orally outside of a migraine attack. If pressure, tightness, and/or pain in the chest, neck, and/or throat occurred, an ECG was obtained, and a repeat echocardiogram was done while the symptoms were present in order to monitor for impairment of myocardial function. If symptoms of these types did not occur within 60 min after administration of the study drug, a second echocardiogram was obtained. Forty-five patients (88%) reported at least one adverse event and 23 (45%) experienced pressure, tightness, and/or pain in the chest, neck, and/or throat after administration of avitriptan. No clinically significant myocardial abnormalities were observed in any patient, even in those who had experienced the targeted symptoms. No other serious adverse event occurred. We concluded that the typical 5HT_1B/1D agonist-induced chest/throat/neck symptoms are most unlikely to be of cardiovascular origin.     

Efficacy of confrontational counselling for smoking cessation in smokers with previously undiagnosed mild to moderate airflow limitation: study protocol of a randomized controlled trial

Background  

The use of spirometry for early detection of chronic obstructive pulmonary disease (COPD) is still an issue of debate, particularly because of a lack of convincing evidence that spirometry has an added positive effect on smoking cessation. We hypothesise that early detection of COPD and confrontation with spirometry for smoking cessation may be effective when applying an approach we have termed "confrontational counselling"; a patient-centred approach which involves specific communication skills and elements of cognitive therapy. An important aspect is to confront the smoker with his/her airflow limitation during the counselling sessions. The primary objective of this study is to test the efficacy of confrontational counselling in comparison to regular health education and promotion for smoking cessation delivered by specialized respiratory nurses in current smokers with previously undiagnosed mild to moderate airflow limitation.     

女性护理专业学生心理健康相关因素分析

目的:分析护理专业学生心理健康的影响因素。方法:于2005-12-01/15按整群抽样法抽取西安市高校在读的护理专业学生515名作为被调查对象。症状自评量表总分≥187为高分组,总分≤116为低分组。高分组与低分组配比的条件是均为女性,年龄相差不超过3岁。采用症状自评量表、简易应对方式问卷、自尊量表、护理专业学生相关状况调查表进行问卷调查。对调查变量进行单因素和多因素Logistic回归分析。结果:共发放问卷515份,其中2名学生生病未填写调查表,应答率为99.6%。调查中有效问卷共507份,有效率为98.8%。症状自评量表总分高分组与低分组学生各100名。①护理专业学生心理健康相关个人因素(计量变量)单因素分析结果:高分组积极应对、自尊水平得分明显低于低分组(20.47±5.02,22.15±6.02;25.91±3.60,30.96±3.25),差异有显著性意义(P<0.05,P<0.01)。高分组消极应对得分明显高于低分组(12.57±4.08,8.00±4.12),差异有显著性意义(P<0.01)。②护理专业学生心理健康相关个人因素(二分类变量)单因素分析结果表明,高分组与低分组比较差异有显著性的因素有独生子女、远离家人、孤独、学习压力大、担心拿不到学位、自我实现需要的满足、经常被人误会、受人歧视、失恋、有知心朋友、无处倾诉苦恼、睡眠型态紊乱、近1年来本人健康改变、适应新环境、经常参加体育活动、担心毕业分配、现有最担心的事情。③多因素分析显示,学习压力大(OR=10.017)、近1年来本人健康改变(OR=4.384)为护理专业学生心理健康状况不良的独立危险因素,而自我实现需要的满足(OR=0.037)、高水平自尊(OR=0.357)是保护因素。结论:护理专业学生心理健康状况与教育、成长、社会环境等多方面因素相关,其心理健康干预需考虑学生的个人因素有针对性地进行。     

Potent antiviral activity of north-methanocarbathymidine against Kaposi's sarcoma-associated herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV) infection is a prerequisite for the development of Kaposi's sarcoma (KS). Blocking lytic KSHV replication may hinder KS tumorigenesis. Here, we report potent in vitro anti-KSHV activity of 2'-exo-methanocarbathymidine [North-methanocarbathymidine (N-MCT)], a thymidine analog with a pseudosugar ring locked in the northern conformation, which has previously been shown to block the replication of herpes simplex virus types 1 and 2. N-MCT inhibited KSHV virion production in lytically induced KSHV-infected BCBL-1 cells with a substantially lower 50% inhibitory concentration (IC50) than those of cidofovir (CDV) and ganciclovir (GCV) (IC50, mean +/- standard deviation: 0.08 +/- 0.03, 0.42 +/- 0.07, and 0.96 +/- 0.49 microM for N-MCT, CDV, and GCV, respectively). The reduction in KSHV virion production was accompanied by a corresponding decrease in KSHV DNA levels in the N-MCT-treated BCBL-1 cells, indicating that the compound blocked lytic KSHV DNA replication. A time- and dose-dependent accumulation of N-MCT-triphosphate (TP) was demonstrated in lytically induced BCBL-1 cells, while uninfected cells showed virtually no accumulation. The levels of N-MCT-TP were significantly decreased in the presence of 5'-ethynylthymidine, a potent inhibitor of herpesvirus thymidine kinase, resulting in the abrogation of anti-KSHV activity of N-MCT. N-MCT-TP more effectively blocked in vitro DNA synthesis by KSHV DNA polymerase with an IC50 of 6.24 +/- 0.08 microM (mean +/- standard deviation) compared to CDV-diphosphate (14.70 +/-2.47 microM) or GCV-TP (24.59 +/- 5.60 microM). Taken together, N-MCT is a highly potent and target-specific anti-KSHV agent which inhibits lytic KSHV DNA synthesis through its triphosphate metabolite produced in KSHV-infected cells expressing a virally encoded thymidine kinase.     

Risk and protective factors for depressive symptoms among American Indian older adults: Adverse childhood experiences and social support

Objectives: Despite efforts to promote health equity, many American Indian and Alaska Native (AI/AN) populations, including older adults, experience elevated levels of depression. Although adverse childhood experiences (ACE) and social support are well-documented risk and protective factors for depression in the general population, little is known about AI/AN populations, especially older adults. The purpose of this study was to examine factors related to depression among a sample of AI older adults in the midwest.

Method: Data were collected using a self-administered survey completed by 233 AIs over the age of 50. The survey included standardized measures such as the Geriatric Depression Scale-Short Form, ACE Questionnaire, and the Multidimensional Scale of Perceived Social Support. Hierarchical multivariate regression analyses were conducted to evaluate the main hypotheses of the study.

Results: Two dimensions of ACE (i.e., childhood neglect, household dysfunction) were positively associated with depressive symptoms; social support was negatively associated with depressive symptoms. Perceived health and living alone were also significant predictors.

Conclusion: ACE may play a significant role in depression among AI/AN across the life course and into old age. Social support offers a promising mechanism to bolster resilience among AI/AN older adults.