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PubMedDate not supplied

[The monosynaptic connection: the modulating effect of opioid peptides on the plasticity of presynaptic neurons and identified synapses].

Study of opioid peptides (leucine-enkephalin and methionine-enkephalin) action on plastic properties of the system of monosynaptically connected neurones LPa7--LPa3, PPa3 and LPa8--LPa3, PPa3 was conducted in the snail brain. It has been shown that all three links in the system studied (presynaptic neurone, postsynaptic neurone and synapse) manifest one and the same type of plasticity--habituation to rhythmic stimulation. Enkephalins have a modulating action on plastic properties of the presynaptic neurone and synapse: they retard the habituation of the presynaptic neurone to intracellular stimulation and retard the development of habituation at synaptic level. However, changes in the character of postsynaptic response in the presence of enkephalins are not a direct consequence of their influence on plastic properties of the presynaptic neurone. Besides, enkephalines reduce the effectiveness of synaptic transmission in the given system: they reduce EPSP duration in the postsynaptic neurone.

Animals↗
PubMed2006

Brain-derived neurotrophic factor mechanisms and function in adult synaptic plasticity: new insights and implications for therapy.

Synaptic plasticity, the fiundamental ability of synapses to undergo experience-dependent changes in synaptic strength, is thought to underlie a range of long-term adaptive responses of the central nervous system. The inability to generate or maintain appropriate changes in synaptic connectivity and neuronal circuitry is likely to impair cognitive futnction associated with many neurological and psychiatric disorders. The success of intervening therapeutic approaches will depend on the ability to target key component mechanisms in the complex process of synaptic plasticity. Brain-derived neurotrophic factor (BDNF) has emerged as a major regulator of synaptic plasticity and a key target in disorders such as major depression and Alzheimner's disease. This review discusses findings that link BDNF mechanisms in synaptic plasticity to disease mechanisms and possible future therapies.

Alzheimer Disease↗
PubMed1991

[Regulation of plastic properties of electrically stimulated neuronal membrane by noradrenaline].

Noradrenaline perfused into washing solution has been considered for the peculiarities of its effect on plastic properties of electrically stimulated neuronal membrane in snails using a simple learning form--habituation to a rhythmical intracellular stimulus. It is shown that the direction of changes in electrical neuronal response under the effect of amine in concentrations from 1.10(-4) M to 1.10(-8) M towards electrical stimulation depends on peculiarities of the initial genotypical membrane to manifest plastic properties. Initially habituated neurons have shown their ability to restore both the induced and basal AP firing. In contrast to tris nonhabituating neurons have shown plasticity only after noradrenaline perfusion. A modulating significance of noradrenaline in the regulation of plastic properties of the neuronal electrically stimulated membrane is suggested.

Animals↗
PubMedDate not supplied

[The antimicrobial activity of desoxon-5 in the disinfection of plastics used in dental practice].

The disinfecting effect to the new preparation--desoxon-5 when decontaminating plastics, used in stomatology, plastic removable [correction of demountable] dentures and orthodontic, apparatus, infected by test microbes has been studied. One of the results of the work is the determination of desoxon-5 concentrations, causing the death of test microbes on the surface of plastic objects. It is proposed to include the use of desoxon-5 as an active decontaminating preparation into the number of means on looking after removable [correction of demountable] plastic dentures.

Dental Materials↗
PubMed1990

Plastic section immunohistochemistry in the diagnosis of hematopoietic and lymphoid neoplasms.

Plastic section immunohistochemistry is an important method in the multiparameter approach to the diagnosis of hematopoietic and lymphoid neoplasms. Morphologic, histochemical, and immunophenotypic data may be correlated even on small fragments of tissue by this technique. A variety of differentiation markers is detectable in plastic sections for the delineation of lymphocytic, histiocytic, and myeloid neoplasms, as well as Hodgkin's disease. Plastic section immunohistochemistry should also be useful in the diagnosis of epithelial and stromal neoplasms caused by enhanced antigen preservation in those neoplasms. For these reasons, we anticipate that the plastic section technique will have a wide variety of research and investigative applications.

Antigens, Surface↗
PubMedDate not supplied

Plastic-embedded semi-thin sections of fine needle aspiration biopsies with dibasic staining. Diagnostic and didactic applications.

The diagnostic and didactic utility of plastic-embedded semi-thin sections of fine needle aspiration biopsies is presented using a case-study approach. The Spurr epoxy semi-thin sections were stained with a newly developed sequential basic fuchsin-methylene blue stain, which gives hematoxylin-and-eosin-like staining and simultaneously substitutes for a wide variety of special stains. The informational content of the sections can approach that of electron microscopy. The use of a direct off-the-slide "pop-off" technique in preparing the plastic-embedded sections allows for a direct comparison between similar groups of cells embedded in plastic and present on the routine aspiration slides; retrospective analysis can discern subtle, previously unrecognized morphologic features in the alcohol-fixed, Papanicolaou-stained slides. The limitations of this comparative approach, however, become manifest when the effects of alcohol fixation on cells are directly compared in plastic and at the ultrastructural level to aldehyde fixation.

Adenoma↗
PubMed1989

Comparative bond strengths of plastic teeth to microwave-curing, heat-curing and 4-META containing denture base resins.

Bond strength of hardened plastic teeth or acrylic resin teeth to microwave-curing, conventional heat-curing and 4-META-containing denture base resins were comparatively investigated in this study. Effects of grinding and monomer coating of the tooth ridge lap were also studied. Bond strength of plastic denture teeth to microwave-curing denture base resin was slightly higher than the other two resins. With all denture base resins used, an increased bond strength was obtained with hardened plastic teeth by treatment of tooth ridge lap but not with acrylic resin teeth. However, scattering of the bond strength was reduced by treatment of tooth ridge lap in acrylic resin teeth specimens. With hardened plastic teeth specimens, fracture in the base resin was increased by monomer coating. With acrylic resin teeth specimens, no specific fracture patterns were demonstrated by treatment of tooth ridge lap. Fracture occurred mostly in the acrylic resin teeth. These results suggest that bond strength of both denture teeth to microwave-curing or 4-META-containing denture base resin was increased or solidified by grinding or monomer coating of tooth ridge lap.

Acrylic Resins↗
PubMed1989

Localization of cytomegalovirus DNA in plastic-embedded sections by in situ hybridization. A methodologic study.

The use of in situ hybridization for the identification of specific nucleic acid sequences in tissue sections has the potential for broad application in pathology. Although this technique has been successfully applied to routine paraffin sections, there have been few studies of the application of in situ hybridization to plastic-embedded tissue sections. The authors adapted techniques developed for paraffin sections to take advantage of the potential for improved morphology and more precise localization inherent in the plastic sections. A commercially available biotinylated DNA probe specific for the cytomegalovirus to develop a practical method for detection of nucleic acid sequences in plastic-embedded tissues was used. Using plastic sections, cytomegalovirus DNA sequences could readily be identified with precise localization of the virus and superb histology.

Biotin↗
PubMed1988

Drug sorption to glass and plastics.

The general properties of glass and plastics, the main packaging materials for pharmaceutical products, are described. The use of plastic materials in medicine and pharmaceutical packaging has increased considerably in the last decade, but research on drug/plastics interactions has to a certain extent lagged behind. This review draws together much of the current information on drug/plastic interactions, discussing mechanisms of drug-binding to plastic materials and highlighting potential problems arising from the use of plastic containers, or use of cellulose ester filters for clarification or sterilisation of drug solutions.

Absorption↗
PubMedDate not supplied

Gas chromatographic-mass spectrometric determination of adipate-based polymeric plasticizers in foods.

A method for the quantitative determination of adipate-based polymeric plasticizers in foods is described. The procedure involves extraction from the food and transmethylation of the polymeric plasticizer to form dimethyladipate (DMA). The derivative is cleaned up by size-exclusion chromatography and determined by capillary gas chromatography-mass spectrometry with selected ion monitoring. The use of a deuterated internal standard at the extraction stage enables quantitation by stable isotope dilution. A detection limit of 0.1 mg/kg of the polymeric plasticizer in foods and a relative standard deviation of 4% have been achieved routinely. The method has been applied successfully to the analysis of cheese, sandwiches, meat, biscuits, and cake that have been in contact with polymeric plasticized poly(vinyl chloride) films.

Adipates↗
PubMed1986

Plasticity in the hypothalamic magnocellular neurosecretory system.

Over the past decade or so, plasticity has emerged as an important, quantifiable property of the mammalian hypothalamic magnocellular neurosecretory system. This plasticity has turned out to be genuinely related to normal function in the sense that it is a set of responses to physiological stimulation rather than only the sequelae of insult or injury, and it is generally completely reversible. This latter property, of course, distinguishes it further from the plasticity observed after injury. Four features of this magnocellular system that have been shown to display predictable and reversible intercellular plasticity are reviewed: the relationships between neurons and their associated astrocytic glia at various levels (dendritic somatic and terminal) of the magnocellular elements; the extent of terminal and glial contact with the basement lamina in the neurohypophysis; the type and possible efficacy of synaptic input, and the extent of electrotonic coupling among the magnocellular neurons.

Animals↗
PubMed1987

Effects of instantaneous prestretching on force degradation characteristics of orthodontic plastic modules.

The object of this study was to investigate the effect of instantaneous prestretching on the force degradation behavior of three kinds of four-link plastic modules. A simple sliding apparatus was used to prestretch instantaneously the plastic modules to 100, 200 and 300% of their original length. After prestretching, specimens were tested at 20, 25 and 30 mm stretch distances. Force measurements were performed at the following occasions: before prestretching; at the end of prestretching; after 1, 4 and 24 hours; and after 1, 2 and 3 weeks. The following conclusions can be drawn from this investigation: The control specimens which had not been instantaneously prestretched exhibited considerable force loss over the three-week test period. Most of the force loss occurred rapidly during the first few hours, with a much lower subsequent force degradation rate. Instantaneous prestretching to a greater length resulted in a lower force value remaining at the end of prestretching. Instantaneous prestretching of the plastic modules is an efficient method to dissipate the high initial force level which is clinically undesirable. Prestretching of the modules around or slightly longer than the stretch distance could reduce the high initial force level and still maintain the same force level as the control groups. However, if the length of instantaneous prestretching of the four-link plastic module was much longer than the testing stretch distance which corresponds to the average distance from the first molar to the canine in the same quadrant, the prestretching would reduce both the high initial force value and the force value during the three-week test period, as compared with the control group.

Humans↗
PubMed1986

Image processing--principles and its future applications in reconstructive and aesthetic plastic surgery.

Although the great importance of the visual aspect to medical science, and plastic surgery in particular, is beyond doubt, the utilization of image systems for transmission, storage, and processing of images is not at all widespread. The main reason for this phenomenon is that owing to the high complexity of imaging-related equipment, in comparison with other means such as audio equipment (telephone, tape recorders, and so on), more complicated systems are required, including wider broadcasting channels, much larger storage capacities, and higher processing speeds than are available now. Except for extensive research and development activities in the universities, research institutes, and military organizations, the large potential of the artificial visual aspect is not commonly utilized. In the future, efficient utilization of image processing capabilities in the service of plastic surgery will be achieved by the emerging capabilities for many complicated procedures. These include huge image data base processing, automatic detection of pathologic cases by enhancement of details and recognition of patterns, accurate measurements of the changes and distortions in the processed images, prediction of results to allow planning of treatment, simulation, and training on computerized cases. The new capabilities also include visual control of robotic arms for complicated operations, better audio-visual communication between faraway clinics and medical centers via sophisticated teleconferencing systems--which will save traveling expenses and time and will enable the updating of medical information--and many more applications that will be developed when the basic equipment becomes an integrated part of the clinics and plastic surgery departments. Future image processing will enhance the visual aspect in the plastic surgeon's work and will enable the doctor to expand his or her professional capabilities.

Automation↗
PubMed1985

Stability of an analgesic-sedative combination in glass and plastic single-dose syringes.

The stability of a combination of chlorpromazine hydrochloride (6.25 mg/mL), hydroxyzine hydrochloride (12.5 mg/mL), and meperidine hydrochloride (25 mg/mL) in glass and plastic syringes was studied. Syringes (glass 1.5 mL, plastic 3.0 mL) containing the combination drug solution were stored at 4, 25, and 44 degrees C. At 0,7,30,60,90,180, and 366 days after preparation, samples were visually inspected and tested for pH. Drug concentrations were determined by gas chromatography. No significant changes in drug concentration were apparent in any of the samples stored at 4 degrees C or 25 degrees C. Samples in both glass and plastic syringes stored at 44 degrees C turned yellow by day 30 and continued to darken throughout the study period. At the concentrations tested, chlorpromazine hydrochloride, hydroxyzine hydrochloride, and meperidine hydrochloride combined in glass or plastic syringes are stable for 366 days when stored at 4 degrees C and 25 degrees C. Degradation occurs at higher temperatures.

Chlorpromazine↗
PubMed1975

Effect of copper and plastic intra-uterine devices on the fibrinolytic activity of the endometrium in the rat.

The effect of copper and plastic intrauterine devices (IUD) on the fibrinolytic activity of the endometrium was studied in the rat. A copper or a plastic device was placed in one of the uterine horns, while the other horn served as a control. Biopsy specimens were obtained from both horns and examined histochemically. The copper concentration was determined by atomic absorption spectroscopy. The fibrinolytic activity of the control horn was found to be localized to small vessels in the outer layer of the uterine wall, while that of the endometrium was low. Plastic as well as copper IUDs increased the fibrinolytic activity which, in contrast with what was seen in the controls, was localized to the endometrium. Compared with the effect of the plastic device, the increase in the fibrinolytic activity induced by the copper device was more widespread in the endometrial area and was accompanied by an increase in the concentration of copper. These findings might help to explain why the contraceptive effect of IUDs is more reliable when they are partly coated with copper.

Animals↗
PubMed1979

Five-year history of the American Society of Plastic and Reconstructive Surgeons, 1974--1978.

This report was intended to summarize the significant happenings in the American Society of Plastic and Reconstructive Surgeons, and its affiliates, from the end of the annual meeting in 1973 to the end of the 1978 annual meeting. It was decided to not include our sister organizations--the American Association of Plastic Surgeons, the American Society for Aesthetic Plastic Surgery, the American Society of Maxillofacial Surgeons--because their historians publish periodic reports about their activities. I am sure that the future reports of historians will record with pride the continued growth and development of plastic surgery, because the future of our specialty has never seemed brighter.

Humans↗
PubMed1977

Selection of plastic containers for pharmaceuticals.

With the awareness of the possibility of drug-plastic interaction, before substitution of a plastic container for glass, steps should be taken to ensure safety. This process is fraught with difficulties because of the complexity of plastic materials and even wider range of drug substances offered for sale in a variety of dosage forms. The selection of an appropriate container for pharmaceutical should be preceded by adequate testing to recognize the properties of the packaging material, and the stability, safety, and compatibility of the preparation packed in it. The same care and control used in the manufacture of a drug product should be used for the plastic packaging system.

Drug Contamination↗
PubMed1983

Staining plastic sections: a review of problems, explanations and possible solutions.

Many of the difficulties of staining plastic embedded tissues for light and electron microscopy derive from physical exclusion of hydrophilic staining reagents by hydrophobic embedding media. Structures which stain most intensely with hydrophilic reagents usually contain less hydrophobic plastic than do non-staining structures. Such incomplete infiltration is apparently caused by exclusion of viscous, hydrophobic monomers by physically dense and/or well hydrated tissue elements. In keeping with this, generalized staining of tissues embedded in hydrophobic media does occur when hydrophobic reagents are used. Staining of plastic-free structures with single hydrophilic reagents or with sequences of such reagents, is, however, largely rate-controlled. The surprising similarity of hydrophilic and hydrophobic plastic embedding media is discussed. Limits of this simple model are explored, with a consideration of the roles of fixative and of monomer-tissue reactions.

Histological Techniques↗