Consumers are attracted to the latest fashion trends and different looks. This drives the search for novel hair treatments. Some chemicals present in hair treatment products can penetrate the hair shaft. These materials can either nourish or injure the hair cortex. Different techniques have been used to investigate the mechanism of molecule penetration and the conditions under which penetration occurs. This article reviews the techniques applied for this purpose. Various microscopy techniques are used to capture clear and colourful images to determine the diffusion pathways and the exact location of the molecules under study. However, the laborious sample preparation often leads to sample destruction since cross-sectioning is often required. While various other techniques have been successfully used for investigating the penetration methods, most of these require different amounts of work to be put in for sample preparation and instrumentation. Several spectroscopic techniques have been used to study the penetration of the molecules because of the high levels of accuracy and the quick response time of these techniques. Moreover, the samples are not damaged during the investigation.
Les consommateurs sont attirés par les dernières tendances et les différents styles de la mode. Cela stimule la recherche pour de nouveaux traitements capillaires. Certains produits chimiques présents dans les produits de soins capillaires peuvent pénétrer la tige du cheveu. Ils peuvent tantôt nourrir, tantôt endommager le cortex pileux. Différentes techniques ont été utilisées pour étudier le mécanisme de pénétration des molécules et les conditions dans lesquelles cette pénétration a lieu. Cet article examine les techniques appliquées à cette fin. Diverses techniques de microscopie sont mises en œuvre pour capturer des images claires et colorées afin de déterminer les voies de diffusion et la localisation exacte des molécules à l’étude. Cependant, la préparation laborieuse des échantillons conduit fréquemment à la destruction des échantillons, car une coupe transversale est souvent exigée. Si plusieurs autres techniques ont été utilisées avec succès pour étudier les méthodes de pénétration, la plupart d’entre elles nécessitent différents niveaux d’activité à mettre en œuvre pour la préparation des échantillons et l’instrumentation. Plusieurs techniques spectroscopiques ont été utilisées pour étudier la pénétration des molécules en raison de leurs niveaux élevés de précision et de leur délai de réponse rapide. De plus, les échantillons ne sont pas endommagés pendant l’investigation.

Axoplasmically transported proteins synthesized in neuronal somata labeled by radioactively labeled amino acids (tritium), following local targeted injections for tracing of pathways in the central nervous system using autoradiography. Results from a number of neuronal systems, including: the rat olfactory bulb; cortico-thalamic projections in the mouse; commissural connections of the rat hippocampus; and retinal projections in the monkey and chick are documented. Pathway origins are clear, as the number and distribution of the labeled cells and the normal structure of the injection site is preserved. Light and electron microscopic autoradiography shows that proteins are transported, at two rates: rapid transport (>100mm/day) of fewer proteins accumulating in axon terminals; and, slow transport (1-5mm/day) of the bulk of labeled proteins distributed along the length of axons. Different survival times can be selected to evaluate terminal projection field(s) or pathways from origin to termination. The clarity of autoradiographic labeling of pathways and their terminations is comparable to other techniques (such as the Nauta-Gygax and the Fink-Heimer methods and the electron microscopy of terminal degeneration). Labeled amino acids do not label molecules in fibers of passage and there is no retrograde transport of labeled material from the axon terminals. The functional polarity of fiber pathways can be easily established. We summarize the merits of this technique is based upon an established physiological properties of neurons that are summarized in contrast to currently used techniques dependent upon pathological changes in neurons, axons, or axonal terminals.
This article considers a heavily cited Brain Research article that reported an extremely important turning point in the ability to demonstrate neuroanatomical pathways in the central nervous system. Using radioactive leucine microinjections into the brain, neurons synthesized proteins from this amino acid that were transported down their axons to the terminal synapses on the target neurons. Tracing the transport of the labeled protein by autoradiography permitted quantitative analysis of projections and pathways. As a result, pathway analysis was transformed from studying the degenerating processes of lesioned neurons to the study of intact pathways in non-manipulated brains. The classical protocol has since been widely applied and used to investigate countless brain circuits. This article is part of a Special Issue entitled SI:50th Anniversary Issue.

Using tritium-labeled thymidine histoautoradiography, the AgNOR staining technique and Ki67-MIB-1 immunohistochemistry to study cell kinetics, prostate cancer can be subdivided into slowly, moderately and rapidly proliferating tumors. These are important supplementary methods and prerequisites for a grading as low, intermediate and high-grade in addition to classical histology and cytology. Cytometry of DNA can confirm the cell kinetics of prostate cancer by detection of a predominance of diploid or aneuploid cell nuclei but should only be evaluated together with histological investigations. All histology-based analyses of cell kinetics encompass the classical highly and poorly differentiated glandular and cribriform patterns as well as solid undifferentiated structures and the various subcategories. The malignancy grading of prostate cancer can result from the summation of histological grading and cell kinetic analyses, as long as the named investigations are included. The future perspectives of individualized therapy options, including active surveillance in early low-grade and also for high-grade prostate cancer and new antihormonal treatment in advanced disease, may increasingly rely on tissue biomarkers and advanced technologies for whole genome analysis including next generation sequencing.

In situ hybridization is a technique that is used to detect nucleotide sequences in cells, tissue sections, and even whole tissue. This method is based on the complementary binding of a nucleotide probe to a specific target sequence of DNA or RNA. These probes can be labeled with either radio-, fluorescent-, or antigen-labeled bases. Depending on the probe used, autoradiography, fluorescence microscopy, or immunohistochemistry, respectively, are used for visualization. In situ hybridization is extensively used in research, as well as clinical applications, especially for diagnostic purposes. This review discusses the basic technique of in situ hybridization. The standard in situ hybridization process is reviewed, and different types of in situ hybridization, their applications, and advantages and disadvantages are discussed.

BACKGROUND: The last two decades have brought many fundamental changes to the drug development process. One such change is the importance of preclinical pharmacokinetics, which has become an essential part of early drug discovery. Furthermore, bioanalytical methods have become more sensitive and the identification and quantitation of metabolites can now be carried out on limited amount of biological material. There has also been a change in regulatory expectations, which are now particularly focused on the safety of human metabolites.
METHODS: The focus of this paper is on some \'traditional\' in vivo ADME studies: excretion balance, metabolic profile and WBA in the toxicological species. These studies, performed with radiolabeled material, have a long history: and are a regular presence in submission dossiers. This paper reviews their value in the perspective of the contemporary drug development process.
CONCLUSIONS: These experiments may sometimes still be relevant to explain toxicological findings or for other special purposes but should not be considered required pieces of the registration dossiers. An appropriate investigation of samples coming from safety evaluation and human Phase I studies and the knowledge generated during the lead optimization phase provide, in most instances, all the DMPK information needed to take decisions in the drug development process.

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The role of melanin in nicotine uptake and metabolism has received little attention. Because nicotine has been shown to accumulate in tissues containing melanin, exploring links between melanin and nicotine may provide additional clues to understanding smoking behavior and disease effects. To examine the scientific literature on the relationship between melanin and nicotine, we conducted a PubMed search. We also searched online archives of internal tobacco industry documents. We retrieved and reviewed 82 published research papers related to melanin and nicotine or melanin and metabolism of other drugs, and 150 relevant internal tobacco industry documents. The published literature suggests that nicotine may accumulate in human tissues containing melanin and this retention may increase melanin synthesis. Existing research on the relationship between melanin and nicotine lacks an adequate consideration of this relationship\'s potential impact, if any, on nicotine metabolism, level of nicotine dependence, and ability to quit smoking. Differential accumulation of nicotine in melanin-containing tissues could have implications for individuals with high levels of melanin.

We present a review of galanin in the brain from a historical perspective of the development of \"chemoarchitectonics\" and \"brain cartography\" accomplished in the Histopharmacology Section at the National Institutes of Health. It was the mapping of potential brain neuroregulators that served as a springboard of ideas from which behavioral studies emanate. The integration of the known localization of neurotransmitter/neuromodulatory nerves (\"chemoarchitectonic maps\") and receptor binding sites with biochemical data derived from brain micropunches coupled with behavioral analysis at the level of discrete brain allows one to define the anatomical circuits which support behavioral changes and which ultimately will improve our understanding of mental disorders.

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