Notes on Technic: Amyl Acetate as a Clearing agent for Refractory Plant Materials

Thin-layer chromatographic systems are described for the analysis of various preformed metal complex dyes (aluminon-chromium(III), carminic acid-aluminum, carminic acid-chromium(III), carminic acid-iron(III), oelestine blue-chromium(III), gallamine blue-chromium(III), gallocyanin-chromium(III), hematein-aluminum, hematein-chromium(III), purpurin-aluminum) and their parent dyes. Certain of there dyes have also been analysed by agar-gel electrophoresis or gel-filtration chromatography. The merits of the three analytical methods are discussed.     

Cedarwood Oil as a Clearing Agent with Acetic-Alcohol Fixatives

PC10 is a monoclonal antibody to proliferating cell nuclear antigen, a nuclear protein associated with the cell cycle. We have evaluated the effects of tissue fixation on PC10 immunoreactivity in sections of paraffin embedded rat tissues. Immunoreactivity was well preserved in tissues after fixation with alcohol-based solutions for 3–24 hr. Fewer PC10-positive cells were detectable in samples fixed with formaldehydecontaining solutions compared with samples fixed with alcohol for the same time. Loss of PC10 immunoreactivity in formaldehyde fixed tissues was progressive, and quantifiable as early as after 3 hr fixation. Consequently, alcohol-based fixatives are strongly recommended for any immunocytochemical prospective study using PC10 antibody. In contrast, loss of PC10-immunoreactivity is always predictable, but difficult to quantitate, using formaldehyde fixed specimens. This aspect should be considered when using PC10 antibody in retrospective studies with routinely-processed archival material.     

病毒治癌

病毒治疗癌症近来有新进展．分子生物学技术的发展,大大促进了病毒在寄主专一性、基因传递的定位性及溶解癌细胞方面的研究：选择适当的病毒种类,根据癌细胞特征性表面蛋白的特性修饰病毒的表面蛋白,使之对癌细胞具有更强的亲和性;去除病毒中原有的致病基因如癌基因,并根据靶细胞的特性针对性地改造有关病毒基因如插入适当的抗癌基因,可能构建成安全有效的工程病毒用于癌症治疗．病毒治癌除具有较强的特异性外,和其他基因治疗方法相比,还具有能利用寄主细胞进行自我复制、级联放大以克服初始剂量不足等特点．     

Embryonic stem-cell culture as a tool for developmental cell biology

The cell biology of the early processes of mammalian embryogenesis, such as germ-layer formation, has been technically challenging to study owing to the size and accessibility of mammalian embryos. Embryonic stem cells, which can generate the three germ layers in vitro, are useful for studying embryogenesis at the cellular level. So, how can the study of embryonic stem cells and their differentiation provide a deeper understanding of the cell biology of early development?     

Resveratrol as a Therapeutic Agent for Neurodegenerative Diseases

Excess production of reactive oxygen species in the brain has been implicated as a common underlying risk factor for the pathogenesis of a number of neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and stroke. In recent years, there is considerable interest concerning investigation of antioxidative and anti-inflammatory effects of phenolic compounds from different botanical sources. In this review, we first describe oxidative mechanisms associated with stroke, AD, and PD, and subsequently, we place emphasis on recent studies implicating neuroprotective effects of resveratrol, a polyphenolic compound derived from grapes and red wine. These studies show that the beneficial effects of resveratrol are not only limited to its antioxidant and anti-inflammatory action but also include activation of sirtuin 1 (SIRT1) and vitagenes, which can prevent the deleterious effects triggered by oxidative stress. In fact, SIRT1 activation by resveratrol is gaining importance in the development of innovative treatment strategies for stroke and other neurodegenerative disorders. The goal here is to provide a better understanding of the mode of action of resveratrol and its possible use as a potential therapeutic agent to ameliorate stroke damage as well as other age-related neurodegenerative disorders.     

Comparison of Resorufin Acetate andp-Nitrophenyl Acetate as Substrates for Chymotrypsin

Resorufin acetate is shown to be an attractive substrate to use with chymotrypsin since the absorbance of the product is several times more intense than that formed by the widely usedp-nitrophenyl acetate. Furthermore, under the right conditions, resorufin acetate allows convenient observation of the burst reaction by conventional spectrophotometry. The steady-statek_catvalues for chymotrypsin-catalyzed hydrolysis of resorufin acetate andp-nitrophenyl acetate are virtually the same, as expected for a rate-limiting deacylation step involving an identical intermediate from both substrates. Stopped-flow studies show that the maximal bursts of product from both substrates are again (in molar terms) about the same. When chymotrypsin is presented with a mixture of both substrates, the monitoring of reaction with resorufin acetate (at 571 nm) is not interfered with by simultaneous hydrolysis ofp-nitrophenyl acetate. Under these conditions,p-nitrophenyl acetate is shown to increase the burst rate constant for acylation of the enzyme by resorufin acetate, demonstrating unequivocally thatp-nitrophenyl acetate can bind to chymotrypsin elsewhere than in the active site.     

Vertebrates as a Bactericidal Agent

In Brazil, although a large number of animals are used in traditional medicine (at least 354 species), information about their biological activities is scarce. In this context, the objective of this study was to evaluate the bactericidal potential of zootherapeutic by-products from animals used in Brazilian traditional medicine and discuss the ecological and cultural consequences of such practices. The species analyzed were: Tupinambis merianae (skin), Iguana iguana (skin and body fat), Crotalus durissus (skin and body fat), Boa constrictor (skin), Euphractus sexcinctus (body fat) and Coendou prehensilis (quills). Experiments were performed with standard clinical strains of Escherichia coli (EC-ATCC10536) and Staphylococcus aureus (SA-ATCC 25923). For the microbiological assay, the zootherapeutics were evaluated using serial microdilutions. The results indicate that none of the samples possess inhibitory activity against standard bacterial strains. The in vitro ineffectiveness of the analyzed products demonstrate a necessity for new pharmacological research that encompass a large number of species of medicinal animals as well as highlight the importance of zootherapy in the context of plans for animal conservation.     

Dichloro-tetrafluoro-ethane as a Freezing Agent

Surgical skin planing is, in the hands of an experienced operator, a safe and highly effective procedure for treating a number of cutaneous defects, most notably pitted acne scars.The operation is facilitated by the use of a new instrument (jet-spray handpiece) which allows the operator to freeze the skin and plane it almost simultaneously, and by a new freezing agent, dichlorotetrafluoro-ethane, which adds to the safety by eliminating the old hazards of inflammability, explosion, and the toxic inhalation of ethyl chloride.The ability to sharply differentiate between keloid and hypertrophic scar is fundamental to surgical skin planing. A hypertrophic scar results from the removal or destruction of the cutaneous appendages (hair follicles, oil and sweat glands and ducts); whereas a keloid is an idiosyncratic response without regard to damage of the appendages.Properly performed surgical planing does not entirely remove these appendages and therefore healing occurs without scarring.