选择性κ阿片激动剂K-Ⅱ与U-50488的药理作用比较

K-Ⅱ系k阿片激动剂U-50488的同类物。通过部分离体和整体实验比较了K-Ⅱ与U-50488的药理作用。实验发现,K-Ⅱ抑制电刺激兔输精管收缩的IC₅₀值为0.42 nmol/L,U-50488为26.5 nmol/L;K-Ⅱ抑制小鼠运动功能(横筛法)的ED₅₀值为1.7 mg/g,U-50488为15.3 mg/kg;K-Ⅱ的小鼠LD₅₀值为152.5 mg/kg,U-50488为118.4 mg/g;K-Ⅱ明显降低小鼠自发活动的作用比U-50488强5倍。结果表明,K-Ⅱ是一个药理作用较U-50488强的k受体激动剂。     

A RANDOMISED,DOUBLE-BLIND,PARALLEL-GROUP COMPARISON OF VENLAFAXINE AND DOTHIEPIN IN GERIATRIC PATIENTS WITH MAJOR DEPRESSION

This randomised, double-blind study conducted at nine sites in the UK and the Netherlands compared the safety and antidepressant efficacy of venlafaxine and dothiepin. Ninety-two geriatric patients (aged 64-87 years) with major depression were randomly assigned to receive either venlafaxine or dothiepin for up to 43 days. The dose of venlafaxine or dothiepin was titrated up to a maximum of 150 mg per day for the first 15 days, and thereafter could range from 50 to 150 mg per day. Adjusted mean scores on the MADRS and the HAM-D decreased significantly (p 0.05) from baseline to the end of the study in both groups. A response to therapy was observed in 60% of patients in the venlafaxine group and 53% of patients in the dothiepin group on the MADRS, and in 60% of patients in both groups on the HAM-D. Suicidal ideation scores on the MADRS were significantly (p=0.042) lower in the venlafaxine group at week 6. Treatment-emergent study events were the primary reason for withdrawal in only 7% of venlafaxine-treated patients and 8% of dothiepin-treated patients. The results confirm the efficacy and tolerability of venlafaxine for treating major depression in the elderly.     

Infusible platelet membrane microvesicles: a potential transfusion substitute for platelets

BACKGROUND: Several substitutes for intact, viable platelets have been used for transfusion, both to people and in animal models, with varied success. Infusible platelet membrane (IPM) is prepared from human platelets. IPM retains the glycoprotein (GP)lb receptor and has platelet factor 3 activity (procoagulant activity). However, factor V, serotonin, a cytoplasmic marker enzyme (purine nucleotide phosphorylase), GPIIb/IIIa complex, and HLA class I and II antigens are all absent in IPM. STUDY DESIGN AND METHODS: IPM is prepared from outdated platelets. The platelets were disrupted by freezing and thawing; they were washed and heated to inactivate possible viral contaminants, and then the sonicated membrane microvesicle fraction was separated and lyophilized. The hemostatic activity of IPM was measured by its ability to reduce the prolonged bleeding time in thrombocytopenic rabbits. RESULTS: Administration of IPM at a dose of 2 mg per kg results in a substantial reduction in the bleeding time. In a series of 23 experiments, a median preinjection bleeding time of 15 minutes was reduced to 6 minutes within 4 hours after IPM administration. Administration of IPM did show a mild enhancement in the thrombogenicity index, as measured in the Wessler rabbit model. This enhancement is, however, not significant, as a thrombogenicity index value of up to 0.6 is clinically acceptable. CONCLUSION: IPM may have clinical potential as a substitute for platelets in the treatment of bleeding due to thrombocytopenia.     

Adjuvant therapy for locally advanced renal cell cancer: A systematic review with meta-analysis

Background  

Many adjuvant trials have been undertaken in an attempt to reduce the risk of recurrence among patients who undergo surgical resection for locally advanced renal cancer. However, no clear benefit has been identified to date. This systematic review was conducted to examine the exact role of adjuvant therapy in renal cancer setting.     

Effects of L-histidine depletion and L-tyrosine/L-phenylalanine depletion on sensory and motor processes in healthy volunteers

Background and purpose:

Animal studies show that histamine plays a role in cognitive functioning and that histamine H₃-receptor antagonists, which increase histaminergic function through presynaptic receptors, improve cognitive performance in models of clinical cognitive deficits. In order to test such new drugs in humans, a model for cognitive impairments induced by low histaminergic functions would be useful. Studies with histamine H₁-receptor antagonists have shown limitations as a model. Here we evaluated whether depletion of L-histidine, the precursor of histamine, was effective in altering measures associated with histamine in humans and the behavioural and electrophysiological (event-related-potentials) effects.

Experimental approach:

Seventeen healthy volunteers completed a three-way, double-blind, crossover study with L-histidine depletion, L-tyrosine/L-phenylalanine depletion (active control) and placebo as treatments. Interactions with task manipulations in a choice reaction time task were studied. Task demands were increased using visual stimulus degradation and increased response complexity. In addition, subjective and objective measures of sedation and critical tracking task performance were assessed.

Key results:

Measures of sedation and critical tracking task performance were not affected by treatment. L-histidine depletion was effective and enlarged the effect of response complexity as measured with the response-locked lateralized readiness potential onset latency.

Conclusions and implications:

L-histidine depletion affected response- but not stimulus-related processes, in contrast to the effects of H₁-receptor antagonists which were previously found to affect primarily stimulus-related processes. L-histidine depletion is promising as a model for histamine-based cognitive impairment. However, these effects need to be confirmed by further studies.     

Altered neuronal excitability in cerebellar granule cells of mice lacking calretinin

Calcium-binding proteins such as calretinin are abundantly expressed in distinctive patterns in the CNS, but their physiological function remains poorly understood. Calretinin is expressed in cerebellar granule cells, which provide the major excitatory input to Purkinje cells through parallel fibers. Calretinin-deficient mice exhibit dramatic alterations in motor coordination and Purkinje cell firing recorded in vivo through unknown mechanisms. In the present study, we used patch-clamp recording techniques in acute slice preparation to investigate the effect of a null mutation of the calretinin gene on the intrinsic electroresponsiveness of cerebellar granule cells at a mature developmental stage. Calretinin-deficient granule cells exhibit faster action potentials and generate repetitive spike discharge showing an enhanced frequency increase with injected currents. These alterations disappear when 0.15 mm of the exogenous fast-calcium buffer BAPTA is infused in the cytosol to restore the calcium-buffering capacity. A proposed mathematical model demonstrates that the observed alterations of granule cell excitability can be explained by a decreased cytosolic calcium-buffering capacity resulting from the absence of calretinin. This result suggests that calcium-binding proteins modulate intrinsic neuronal excitability and may therefore play a role in information processing in the CNS.     

Knowledge,attitude and behaviour regarding dietary salt intake among medical students in Angola

High salt (sodium chloride) consumption is an important determinant of high blood pressure and cardiovascular risk. According to World Health Organisation (WHO) statistics, over 80% of cardiovascular disease (CVD) deaths take place in low-and middle-income countries, and elevated blood pressure levels were a major cause of these CVD deaths in those countries.1 Lifestyle factors such as unhealthy diet, physical inactivity, tobacco use and harmful use of alcohol have been considered the most important behavioural risk factors for heart disease and stroke.2Among dietary factors, high salt intake has been the most strongly associated with raised blood pressure and increased risk of stroke and CVD.3 Therefore dietary sodium restriction has been recommended as a non-pharmacological approach to blood pressure lowering,4-6 and for the prevention and control of non-communicable diseases at the population level.7,8Cumulative evidence has shown that even a modest reduction in salt intake was associated with blood pressure lowering and therefore with a significant reduction in incidence of cardiovascular events.9-12 Furthermore, data from the most recent systematic review and meta-analyses has shown the benefit of lowering sodium intake in apparently healthy adults and children,13 and in both hypertensive and normotensive individuals, irrespective of gender and ethnic group.9Since hypertension is associated with CVD worldwide, a public health intervention to reduce high blood pressure must target the role of lifestyle, particularly reduced sodium intake.7 Therefore, several countries have initiated strategies to reduce dietary salt intake in the general population by a combination of various procedures such as public education, food labelling, and collaboration with the food industry to reduce the salt content of processed food.14Among sub-Saharan African countries, only Nigeria and South Africa have developed dietary guidelines regarding salt intake.15 Recently, the South African government implemented important specific legislation towards decreasing salt intake in the population by reducing sodium content of processed foods by industries.16 Therefore, the current public health recommendation is that countries should launch national initiatives to reduce the over-consumption of salt as part of non-communicable disease prevention and healthy nutrition policies for limiting salt intake to less than 5 g/day for the general population including children.7 Despite of this guideline, however, high sodium intake remains prevalent around the world, with average daily salt intake varying from 5 to 18 g/day per person.17Although processed foods have been found to be the principal source of excessive dietary salt intake,18 sources of dietary sodium vary largely worldwide and may be influenced by cultural context and dietary habits of the population.19 In sub-Saharan African countries experiencing demographic and epidemiological transition, the rapid rise in prevalence of CVD (chiefly hypertension) has been attributed to lifestyle change, including high dietary sodium intake.20,21 However, consistent data from studies on risk factors are lacking for the majority of these countries.With regard to Angola, available data from a cross-sectional study reported a high prevalence of multiple cardiovascular risk factors, such as hypertension, sedentary lifestyle, electrocardiographic left ventricular hypertrophy,22 and high rate of the metabolic syndrome23 in an apparently healthy middle-aged population of university public employees living in urban and peri-urban areas.Determining the level of sodium intake in the population is crucial to establish intervention strategies and policy on reduction of sodium intake. For medical students in particular, it is very important to assess their awareness regarding dietary salt intake, since they are the future providers of healthcare information for the counselling of people about the need to reduce salt consumption. The aim of this study was to determine salt intake and to assess the knowledge, attitude and behaviour regarding dietary salt among medical students.