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At least 1,639 records · Page 91Linked to original sources
PubMed1994

Developmental changes in the brain-stem serotonergic nuclei of teleost fish and neural plasticity.

1. During early ontogeny, the serotonergic neurons in the brain stem of the three-spined stickleback shows a temporal and spatial developmental pattern that closely resembles that of amniotes. 2. However, in the adult fish, only the midline nuclei of the rostral group (dorsal and median raphe nuclei) and the dorsal lateral tegmental nucleus are consistently serotonin-immunoreactive (5-HTir), whereas the groups of the upper and lower rhombencephalon (raphe pontis, raphe magnus, and raphe pallidus/obscurus nuclei) are variable and, when present, contain relatively small numbers of 5-HTir neurons. 3. Using specific antisera against tryptophan 5-hydroxylase and aromatic L-amino acid decarboxylase, we have shown that the lateral B9 group and the groups of the upper and lower rhombencephalon are consistently present in adult sticklebacks. The results are discussed in relation to other known instances of neurotransmitter plasticity or transient neurotransmitter expression in teleost fish. 4. While there are several instances of transient expression of neurotransmitter markers by discrete neuronal populations, there is so far no evidence of changes from one neurotransmitter phenotype to another in the brain of teleost fish. However, there are indications of plasticity of expression of catecholamines and indoleamines, and their respective synthesizing enzymes, as reflected in age-dependent changes and variation between individuals of different physiological status. 5. As the brain grows continuously in teleost fish, and new neurons are added from proliferative regions, synaptic connections may be expected to undergo remodeling in all brain regions throughout life. Thus, the teleostean brain may be considered a suitable model for experimental studies of different aspects of neural plasticity.

Animals↗
PubMedDate not supplied

Influence of leukotrienes B4 and C4, 12-hydroxyeicosatetraenoic acid, and erythro epimers of hepoxilin B3 on the plasticity of cholinoreceptors of neurons of the common snail.

The influences of a number of acyclic eicosanoids which are formed from arachidonic acid under the influence of 5- and 12-lipoxygenases on the plasticity of cholinoreceptors of neurons of the common snail, which was assessed on the basis of the degree of frequency depression of the amplitude of the inward current induced by local application of acetylcholine to the soma, were investigated in identified RPa3 and LPa3 neurons of the common snail using the method of bielectrode recording of the potential on the membrane. The plasticity of the cholinoreceptors was enhanced by leukotrienes B4 and C4, and was not altered by 12(S)-hydroxy-(5Z, 8Z, 10E, 14Z)-eicosatetraenoic acid, or by the threo and erythro epimers of hepoxilin B3. An inference is drawn regarding the regulation of the plasticity of cholinoreceptors by leukotrienes B4 and C4, which are formed under the influence of 5-lipoxygenase. One of these pathways includes inositol-1,4,5-triphosphate-dependent mobilization of deposited Ca2+.

Acetylcholine↗
PubMedDate not supplied

Effects of changes in dynamic equilibrium in microtubule and microfilament systems on the plastic responses of neurons.

Studies were carried out on the effects of disruption and stabilization of microtubules and microfilaments on the formation of neuronal plastic responses in isolated nerve cells of the mollusk Lymnaea stagnalis. Disruption of these cytoskeletal elements prevented the development of neuronal plastic responses. Microtubule stabilization produced a dynamic relationship between the development and retention of neuronal plastic responses and series of stimuli. Stabilization of microfilaments blocked the development but promoted the retention of these neuronal responses.

Actin Cytoskeleton↗
PubMedDate not supplied

Gauze vs. plastic for peripheral intravenous dressings: testing a new technology.

The authors conducted a randomized, prospective, controlled trial of three different dressings for peripheral intravenous catheters in 301 acutely ill medical inpatients. Catheters were dressed with dry clean gauze or one of two brands of transparent plastic. The gauze dressings remained in place significantly longer (47 hours median) than either Uniflex (39 hours) of Tegaderm (32 hours) transparent plastic dressings (p = 0.026). Catheters were removed for complications (inflammation, mechanical failure, or infiltration) in 35% of the gauze group, compared with 58% of the Uniflex group and 48% of the Tegaderm group (p = 0.015). Not only were inflamed venipuncture sites seen less often with gauze, inflammation occurred later (p = 0.002) and with lesser severity. Dry gauze dressings resulted in longer catheter life, lower complication rates, and less expense than transparent plastic dressings for peripheral intravenous catheters.

Catheters, Indwelling↗
PubMedDate not supplied

Chemical plasticity of visual cortical neurons in integrative organization of feeding behavior in cats.

The P.K. Anokhin conception of organization of systemic behavior was used to study the discharge activity and chemical plasticity of cortical neurons in a goal-directed behavior. Chemical sensitivity of neurons in the visual cortex of instrumentally conditioned cats was studied during successive stages of food procuring and consuming. The results showed that definite stages of this integrated behavioral act are characterized by differences in the chemical sensitivity of visual neurons to neurotransmitters. The largest number of neurons resistant to neurotransmitters was found among cells that did not respond at successive stages of goal-directed behavior. The iontophoretic delivery of cycloheximide and lyzilvasopressine altered the discharge activity of individual cortical neurons at different stages of stereotyped instrumental conditioned acts. This suggests that the integrative organization of the feeding behavior is determined by chemical plasticity of the brain's visual cortical neurons and is dependent upon the processes of protein synthesis. According to the functional system theory (Anokhin, 1974) each brain neuron is included, by various degrees of freedom, in the stages of systemic organization that underlie the goal-directed behavior. Thanks to the plastic reorganization of brain units, each stage is directed toward the achievement of useful adaptive results for the organism during interaction with different environmental factors (Adrianov, 1993; Fadeev, 1988). It may be proposed that the reorganization of discharges of brain neurons that occurs at different stages of activity is due to changes in their chemical capacities. In concordance with such a hypothesis, the purpose of the present investigation was to study the chemical sensitivity of single visual cortical neurons to neurotransmitters at different stages of systemic organization of feeding behavior. The influence of protein synthesis inhibitors on the sensitivity of cortical neurons was also investigated.

Acetylcholine↗
PubMed1982

Morphological and proliferative characteristics of human breast tumor cells cultured on plastic and in collagen matrix.

Collagen, a major component of the extracellular matrix, is important in maintaining the in vivo characteristics of epidermal cells in vitro. In the present study, the morphological and proliferative characteristics of two human mammary epithelial cell lines (T-47D and MCF-7) cultured in cowhide collagen (Vitrogen 100) were studied. When grown in collagen, the tumor cells displayed a spherical shape and formed multilayered, tumorlike aggregates; desmosomes were observed between cells. In contrast, both cell lines grew as monolayers on plastic substratum; cells were characteristically flat and polygonal. When grown in collagen matrix, the human breast cancer cells became more dependent on serum for growth: cells proliferated in the presence of 10% fetal bovine serum (FBS) but failed to grow in 1% serum. On the other hand, these cells proliferated rapidly in 1% serum when they were grown on plastic. Even in 10% serum the doubling time of cells cultured in collagen was longer than that of cells maintained on plastic. In addition, cells cultured in collagen proliferated rapidly in a serum-free medium containing insulin, epidermal growth factor (EGF), estrogen, and transferrin. The collagen gel system may be useful for characterizing physiologically important trophic factors that regulate the proliferation and other functions of human breast tumor cells.

Breast Neoplasms↗
PubMed1998

Regulation of neuronal plasticity in the central nervous system by phosphorylation and dephosphorylation.

Neuronal plasticity can be defined as adaptive changes in structure and function of the nervous system, an obvious example of which is the capacity to remember and learn. Long-term potentiation and long-term depression are the experimental models of memory in the central nervous system (CNS), and have been frequently utilized for the analysis of the molecular mechanisms of memory formation. Extensive studies have demonstrated that various kinases and phosphatases regulate neuronal plasticity by phosphorylating and dephosphorylating proteins essential to the basic processes of adaptive changes in the CNS. These proteins include receptors, ion channels, synaptic vesicle proteins, and nuclear proteins. Multifunctional kinases (cAMP-dependent protein kinase, Ca2+/phospholipid-dependent protein kinase, and Ca2+/calmodulin-dependent protein kinases) and phosphatases (calcineurin, protein phosphatases 1, and 2A) that specifically modulate the phosphorylation status of neuronal-signaling proteins have been shown to be required for neuronal plasticity. In general, kinases are involved in upregulation of the activity of target substrates, and phosphatases downregulate them. Although this rule is applicable in most of the cases studied, there are also a number of exceptions. A variety of regulation mechanisms via phosphorylation and dephosphorylation mediated by multiple kinases and phosphatases are discussed.

Animals↗
PubMed2001

Comparison of plastic prostheses and self-expandable metallic stents in the treatment of malignant esophageal stenosis.

OBJECTIVE: We compared the efficacy of plastic prostheses and self-expandable metallic stents in the treatment of malignant esophageal stenosis and/or fistula. SUBJECTS AND METHODS: Subjects were 31 patients with esophageal cancer, 4 with esophagotracheal fistula, and 1 with esophageal stenosis. A plastic prosthesis was inserted in 15 patients (group A) and a self-expandable metallic stent in 21 patients (group B). We evaluated food ingestion improvement, effectiveness, complications, mean survival, food ingestion duration, the percentage of food ingestion capability in total survival time, and inhospital mortality. RESULTS: No differences were seen in food intake improvement or in the effectiveness between groups, whereas fatal complications were higher in Group A. No significant differences were seen in mean survival, food ingestion duration, percentage of food ingestion capability, or inhospital mortality between groups. CONCLUSION: We concluded that a self-expandable metallic stent was safer than a plastic prosthesis because of fewer serious complications such as bleeding, and recommended the use of metallic stents in the treatment of malignant esophageal stenosis and/or fistula.

Aged↗
PubMed2003

Biodegradable plastics from renewable sources.

Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).

Bacteria↗
PubMed1991

Structural plasticity of synapses in Alzheimer's disease.

Plasticity of the synaptic contact zone was previously observed following loss of synapses in the cerebral cortex of normal aging humans. The present study was undertaken to determine if there was quantitative evidence of synapse loss and synapse plasticity in the inferior temporal, superior parietal, parieto-occipital, and superior frontal cortical regions in Alzheimer's disease (AD), and how such changes related to the neurofibrillary tangles and amyloid plaques. The results showed that age at autopsy did not correlate with the numbers of synapses, plaques, or tangles. However, the numbers of synapses strongly reflected the pathology of AD; in all four brain regions, there were fewer synapses as the numbers of plaques and tangles increased. In the inferior temporal and superior parietal cortices, the loss of synapses was accompanied by an increase in the synaptic contact length. The results suggest that, in some cerebral cortical brain regions, synapses are capable of plasticity changes, even when the pathology of AD and loss of synapses are severe.

Age Factors↗
PubMed2000

The role of mammalian ionotropic receptors in synaptic plasticity: LTP, LTD and epilepsy.

Synaptic plasticity is the foremost candidate mechanism to explain the rapid acquisition of memories. In the mammalian brain, the NMDA subclass of glutamate receptors plays a central role in the induction of several forms of use-dependent plasticity. The finding that modifications in synaptic strength are largely expressed by receptors of the AMPA subclass has focused attention on molecular mechanisms that affect their function and targeting. Receptor plasticity has also been reported in pathological situations, notably in animal and human forms of epilepsy. Which of these changes are causally implicated in the generation of seizures, and which may be compensatory or neuroprotective adaptations, has not been fully resolved.

Animals↗
PubMed2004

Issues surrounding sleep-dependent memory consolidation and plasticity.

There is a growing body of evidence in support of sleep-dependent memory consolidation and plasticity. However, there are also examples of memory development and plasticity in the absence of sleep, casting doubt on an exclusive sleep-dependent memory hypothesis. As a result, polarized stances have arisen within the field. Here we reflect on these findings, and explore how they maybe reconcilable in a unified approach to understanding the roles of wake, sleep and specific sleep stages in successful memory processing and brain plasticity.

Animals↗
PubMed2005

[Regenerative medicine and plastic surgery].

Regenerative medicine recently evolved as a new medical field that includes tissue engineering, cell/system biology, nanotechnology, pharmacology, stem-cell biology, and bioengineering. Regenerative medicine targets new forms of therapy to promote and support the intrinsic, autologous, regenerative potential of human biological systems. All fields of surgery have profited from these developments, and spectacular experimental results and clinical benefits have been obtained. Plastic surgery has shown interest in regenerative medicine due to its focus on reconstructive surgery. Early on, several interdisciplinary experimental working groups were founded including plastic surgery. This overview takes a closer look at common experimental and clinical results of regenerative medicine and plastic surgery.

Animals↗
PubMed2001

Long-term effects of neonatal MK-801 treatment on spatial learning and cortical plasticity in adult rats.

RATIONALE AND OBJECTIVES: The long-term effects of neonatal treatment with MK-801 on spatial learning and cortical plasticity were investigated in adult rats. METHODS: Rat pups were injected twice daily with MK-801 (0.1 mg/kg) on postnatal days 7-19, participated in water maze testing between postnatal days 90 and 102, and were then studied electrophysiologically. RESULTS: Treatment with MK-801 in such a low dose resulted in a very slight impairment of performance in the water maze task, but not in the visual cue response. Besides the slight learning impairment, the electrophysiological study revealed a reduction in the capacity for plasticity in the primary motor cortex of the treated animals, which was pronounced in the controls. CONCLUSION: The study demonstrates that even a slight impairment in learning and memory function may be accompanied by a cortical plasticity deficiency that is detectable electrophysiologically.

Animals↗
PubMed2001

Short-term plasticity of extrinsic excitatory inputs to neocortical layer 1.

Previous studies have shown that different pyramidal cell inputs vary in the short-term plasticity expressed when they are subjected to repetition of use. Here, we describe short-term plasticity at synapses that mediate long-range input to neocortical layer 1 and compare it with that which normally occurs in the hippocampal Schaffer collateral pathway, which also involves projection by remote inputs onto apical dendrites. We isolated tangential inputs to layer 1 in neocortical slices, stimulated these with brief 40-Hz trains, and examined postsynaptic responses by recording extracellularly from layer 1 in somatosensory, prefrontal, and visual neocortex, and intracellularly from visually identified pyramidal cell somata in layer 2/3 in somatosensory and prefrontal neocortex. Train response amplitudes were characterized by calculating paired-pulse ratios, fifth-versus-first amplitude ratios (5th/1st ratios), and a center-of-mass index "M". As expected, the hippocampal train responses facilitated strongly. In contrast, layer-1 responses displayed strong synaptic depression in all regions examined. This depression was reflected in 5th/lst ratios and M scores, but not paired-pulse ratios because it did not consistently begin until the third responses in trains. It persisted unchanged in the presence of partially blocking levels of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), but was converted to strong facilitation when slices were bathed in low-Ca++ media. Intracellularly, we observed response-train depression very similar to that recorded extracellularly. These findings show that long-range inputs to neocortical layer 1 display short-term plasticity markedly different from that which normally occurs at hippocampal Schaffer collateral synapses, but similar to that which has been described previously for excitatory inputs to pyramidal cells in deeper neocortical layers.

Afferent Pathways↗
PubMed1999

Comparative study of the neuronal plasticity along the neuraxis of the vibrissal sensory system of adult rat following unilateral infraorbital nerve damage and subsequent regeneration.

The aim of the present study was to examine the physiological consequences of a unilateral infraorbital nerve lesion and its regeneration at different levels of the somatosensory neuraxis. In animals whose right infraorbital nerve had been crushed, a large unresponsive area was found in the main brainstem trigeminal nucleus (Pr5). Responses evoked by ipsilateral vibrissal deflection in the middle of Pr5 reappeared only on days 22-35 after the nerve had been transected, whereas recovery from the nerve crush took only 7-9 days. However, no sign of short-term neuronal plasticity was observed in Pr5 after peripheral nerve injury. An enlargement of the receptive fields in two-thirds of the units and a lengthening in the delay of the evoked responses were observed as long-term plastic changes in Pr5 neurons after peripheral-nerve regeneration. In the ventral posteromedial nucleus of the thalamus (VPM) of partly denervated animals, however, only minutes or hours after the nerve crush, certain units were found to respond in some cases not only to the vibrissae, but also to mechanical stimulation of the face over the eye (two units), the nose (one unit), and the midline (one unit). Apart from the experiments involving incomplete denervation, the vibrissal representation areas of the VPM were unresponsive to stimulation of both the vibrissae and other parts of the face until nerve regeneration had occurred. In the somatosensory cortex, an infraorbital nerve crush immediately resulted in a large cortical area being unresponsive to vibrissal deflection. It was noteworthy, however, that shortly after the nerve crush, this large unresponsive whisker representation cortical area was invaded from the rostromedial direction by responses evoked by stimulation of the forepaw digits. In spite of the reappearance of vibrissa-evoked responses 7-10 days after the nerve crush, an expanded digital representation could still be observed 3 weeks after the nerve crush, resulting in an overlapping area of digital and vibrissal representations. The withdrawal of the expanded representation of forepaw digits was completed by 60 days after the nerve crush. The results obtained in Pr5, the VPM, and the cortex strongly suggest that the higher the station in the neuraxis, the greater the degree of plasticity after infraorbital nerve injury.

Animals↗
PubMed2004

Plastic surgery and psychomorphology: a new tool for improving communication between physician and dysmorphopathic patient and for perfecting appropriate patient selection.

The relationship between physician and patient is becoming more and more delicate and requires an appropriate amount of attention and balance; this holds true in all medical disciplines, particularly in the field of plastic surgery. In this research project, the author proposes the use of a psychomorphology evaluation, as well as, a psychomorpholinguistic approach, in the global evaluation of plastic surgery candidates. The aim of this project was to present a pilot study that evaluated plastic surgery patient/physician relationship satisfaction outcome using psychomorphology and psychomorpholinguistic evaluation methods. The research was performed by comparing, a sample group in which the psychomorphology evaluation method was used and a control group that was traditionally evaluated. All the patients in this study have been diagnosed and graded with the dysmorphopathy classification system. The evaluation of patient satisfaction was obtained using Huskisson's visual analogue scale and the SAT-P Satisfaction Profile. In the author's opinion this method has aided him in gathering more precise information and having a deeper comprehension of the patient's most profound psychological needs. This reduced the patient's inappropriate illusions and delusions, which lead to severe psychological problems in accepting themselves. In addition, this method also can help prevent patient dissatisfaction with surgical outcome, thus reducing medical-legal encounters. This is not a methodology for judging or categorizing a patient. It should not be confused with the traditional physiognomic analysis. It is a dynamic analysis that also integrates one's conflictual psychomorphological traits and by recognizing these, continually looks to arrive at a better comprehension for establishing a harmonious relationship between two people, in our situation, surgeon and patient.

Adult↗
PubMed2004

Risk of glove perforation in minor and major plastic surgery procedures.

BACKGROUND: Incidental needlestick injury with exposure of blood pathogens has a high incidence among health care workers. Because plastic surgeons make up an important risk group for this type of accident, this study sought to evaluate the incidence of glove perforation during minor and major plastic surgery procedures. METHODS: Evidence of glove perforation was evaluated for 390 gloves after 100 consecutive minor surgical procedures and for 710 gloves after 100 consecutive major surgeries using Maffuli's test. An index based on the number of first assistant's glove perforation and the surgical time was created to compare these accidents associated with both types of procedures. RESULTS: Glove perforations were found in four gloves (1.02%) after minor surgery and 76 gloves (21.40%) after major surgery. During minor surgeries, the assistant was more likely to have exposure than the surgeon. During major surgery, the surgeon experienced more glove perforations (59.21%) than the assistant (40.79%). The most common location of perforations was the palmar face of the left hand in both groups. The surgeons did not notice these perforations at any time. The duration of the minor procedures varied from 10 to 30 min (average, 17.55 min), whereas the time of major procedures ranged from 1 to 6 h (average, 186 min). There was no statistical significant difference in the perforation's index between minor and major procedures. CONCLUSIONS: The risk of perforation to the surgeon's glove during minor surgery is minimal. The frequency of perforation to the first assistant's glove is similar between minor and major plastic surgery procedures.

Brazil↗