Flat and tubular membrane systems for the reconstruction of hippocampal neuronal network

The selection of appropriate biomaterials that promote cellular adhesion and growth is particularly important for the in vitro reconstruction of neuronal network. This study focused on the development of new polymeric membranes in flat and tubular (hollow-fibre) configurations as novel biomaterials for neuronal outgrowth. Two membrane systems constituted by modified polyetheretherketone (PEEK-WC) and polyacrylonitrile (PAN) membranes were developed and used for the culture of hamster hippocampal neurons. We demonstrated that all investigated membranes supported the adhesion and growth of hippocampal neurons enhancing neuronal differentiation and neurite alignment. The differences in cell behaviours between cells cultured on flat and hollow-fibre (HF) membranes were highlighted by the quantitative analysis of neuronal marker fluorescence intensity, morphometric analysis, RT-PCR analysis and also by metabolic activity measurements. In particular, the PAN HF membranes showed ideal growth culture conditions, guaranteeing adequate levels of metabolic features. Primary hippocampal cells cultured on PAN HF membranes were able to recreate in vitro a 3D neural tissue-like structure that, mimicking the hippocampal tissue, could be used as a tool for the study of natural and pathological neurobiological events.     

In vivo human triceps surae and quadriceps femoris muscle function in a squat jump and counter movement jump

An optic fibre method was used to measure in humans in vivo Achilles (ATF) and patellar tendon forces (PTF) during submaximal squat jumps (SJ) and counter movement jumps (CMJ). Normal two-legged jumps on a force plate and one-legged jumps on a sledge apparatus were made by four volunteers. Kinetics, kinematics, and muscle activity from seven muscles were recorded. The loading patterns of the tendomuscular system differed among the jumping conditions, but were similar when the jumping height was varied. Peak PTF were greater than ATF in each condition. In contrast to earlier simulation studies it was observed that tendomuscular force could continue to increase during the shortening of muscle-tendon unit in CMJ. The concentric tendomuscular output was related to the force at the end of the stretching phase while the enhancement of the output in CMJ compared to SJ could not be explained by increases in muscle activity. The stretching phase in CMJ was characterised by little or no electromyogram activity. Therefore, the role of active stretch in creating beneficial conditions for the utilisation of elastic energy in muscle was only minor in these submaximal performances. The modelling, as used in the present study, showed, however, that tendon underwent a stretch-shortening cycle, thus having potential for elastic energy storage and utilisation. In general, the interaction between muscle and tendon components may be organised in a manner that takes advantage of the basic properties of muscle at given submaximal and variable activity levels of normal human locomotion. Accepted: 28 June 2000     

Dissociated sensory loss in diabetic autonomic neuropathy.

Aims: Clinical observation has led to the idea that there might be a distinctive form of selective sensory and autonomic neuropathy affecting patients with Type 1 diabetic mellitus with severe symptomatic autonomic neuropathy (Type 1-DAN) and this study was conducted to evaluate the presence of such a neuropathy in Type 1-DAN. METHODS: Nineteen Type 1 diabetic patients presenting for treatment of severe symptomatic autonomic neuropathy were examined (all had > or = 2 autonomic symptoms; age 39.3 +/- 10.2 years; duration of disease 25.6 +/- 10.5 years). For comparison, 19 Type 1 diabetic patients with neuropathic foot ulcers (age 44.5 +/- 6.6 years; duration of disease 26.7 +/- 9.2 years), 14 clinically uncomplicated Type 1 diabetic patients (age 39.9 +/- 5.6 years; duration of disease 22.9 +/- 9.3 years) and 16 non-diabetic healthy people as controls (age 39.3 +/- 10.7 years) were also examined. Results The large fibre modalities (light touch and vibration perception) were better preserved in the Type 1-DAN group than in the foot ulcer group. Thus, light touch sensation was normal in 11 out of 19 Type 1-DAN patients compared to only three out of 19 foot ulcer patients (P < 0.01), and vibration perception was 24.9 +/- 15.0 V and 40.5 +/- 7.9 V, respectively (P < 0.002) with some of the Type 1-DAN patients in the normal range. In contrast, the small fibre modalities, thermal perception and autonomic function, were grossly abnormal in both groups (hot thermal perception 14.1 +/- 2.5 degrees C and 12.6 +/- 3.7 degrees C; cold thermal perception 13.8 +/- 2.7 degrees C and 10.9 +/- 4. 7 degrees C; heart rate variation 2.9 +/- 1.5 beats/min and 4.8 +/- 4.0 beats/min, respectively). CONCLUSIONS: There is indeed a subgroup of Type 1 diabetic neuropathy patients who suffer from severe autonomic symptoms associated with a selective small fibre sensory and autonomic loss with relatively preserved large fibre sensory modalities.     

Dietary fibre and health: an overview

Summary Many studies have found that people on diets high in fibre have reduced risks of certain diseases such as cancers, coronary heart disease, obesity and possibly diabetes. Fibre is a collective term for a group of compounds, which differ in their chemical structure and physical properties and elicit a variety of physiological effects. Some health benefits linked to fibre consumption are well established (e.g. promoting a regular bowel habit) and others are becoming more firmly established. The effects of the various non‐digestible components are not always fully interchangeable, although there is considerable overlap, but they share an ability to pass undigested into the large bowel. This makes it important that fibre intake comes from a range of sources to ensure maximum health benefits. There are disagreements as to which plant‐derived compounds constitute ‘fibre’ and which analytical methodologies should be used to determine the fibre content of foods. This lack of a universal definition for these carbohydrates that resist digestion in the small intestine has led to complications in establishing and communicating consistent recommendations for the type and amounts of fibre components in the diet, as well as issues related to food labelling and health claims. Furthermore, current analytical methods may typically underestimate the fibre content of foods, using the definition advised by the European Food Safety Authority. Chemical nomenclature is necessary for a coherent and enforceable approach to the measurement of fibre (and related to this, product labelling), but reconciling chemical definitions for fibre with definitions that reflect physiological effects remains a major challenge. Progress in the application of the emerging evidence regarding dietary fibre and health is constrained by a need to resolve the definition and methodology issues. Most consumers are likely to be unaware of the more recent developments and the overlapping properties of different types of carbohydrate that resist digestion in the small intestine, and the particular sources of these carbohydrates. Long overdue is the translation of the growing knowledge about the physiological properties of carbohydrates, particularly non‐digestible carbohydrates, into clear and unambiguous public health messages. Many terms in common use stem from chemistry rather than physiology, and this makes derivation of health messages more difficult. Meanwhile in the UK, where the main sources of fibre are cereals and cereal products, followed by vegetables and potatoes, adults are not meeting the recommended 18 g of fibre per day (defined in the UK as non‐starch polysaccharide measured by the Englyst method). The recommended amount for the UK, established in 1991, is lower than elsewhere in the world and corresponds to about 24 g according to the method used by the Association of Official Analytical Chemists (the AOAC method). Reference values in other parts of the world are typically between 25 and 35 g (AOAC fibre). A diet rich in whole grains, pulses, fruit and vegetables will assist in meeting current fibre recommendations, but a growing number of other foods now contain carbohydrate‐derived ingredients that resist digestion.     

碳纤维电极循环伏安法检测维生素B6的条件选择

通过循环伏安法 ,研究了维生素B6(VB6)在不同的pH底液条件下在碳纤维电极上的氧化性质 ,得出了VB6的氧化峰电流与底液pH值的关系 ,确定了碳纤维电极伏安法检测VB6的最佳实验条件。     

血管内置入型人工肺的传质计算与in vitro模拟实验对比分析

本文对自制的血管内置入型人工肺 (IVOX)的性能以生理盐水为介质进行了invitro测试 ,并用Vaslef等人的半经验理论模型对实验测试结果进行了计算 ;结果表明自制的IVOX具有一定的氧合和排二氧化碳功能 ,Vaslef等人的半经验模型可方便有效的表达IVOX的传质效果。     

Factors influencing compliance with dietary advice: the Diet And Reinfarction Trial (DART)

Factors influencing compliance with dietary advice were investigated in the Diet and Reinfarcation Trial (DART). In terms of achieved intakes, smokers had a lower mean P/S ratio and fibre intake than non-smokers; manual workers had a lower mean fibre intake than non-manual workers; and obese men had a higher percentage of energy from fat and lower P/S ratio than non-obese men. However the effect of the advice (difference in intakes of those advised and thosen not advised) was similar in smokers and non-smokers and was similar in all social classes. The effect of fat advice was less among obese men than among non-obese men, probably as a result of weight-reducing advice given to all overweight men. Fat advice tended to have a greater effect among those who gave up smoking after their heart attack than among non-smokers and those who continued to smoke but the difference was not statistically significant. This suggests that advice on diet and smoking can be given simultaneously and still be effective.