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At least 1,657 records · Page 92Linked to original sources
PubMed2004

Ondansetron for the prevention of postoperative nausea and vomiting: which is the best dosage for aesthetic plastic surgery?

BACKGROUND: Ondansetron has been used widely in plastic surgery to prevent postoperative nausea and vomiting. A literature search showed controversial dosages of this drug, and because of its short half-life, its use only before anesthetic induction could have a limited effect. The purpose of this study was to assess the efficacy of intravenous (IV) ondansetron (4 mg) for aesthetic plastic surgery performed with the patient under general anesthesia and the prophylaxis of postoperative nausea and vomiting (PONV) in two situations: (a) only before anesthetic induction and (b) before anesthetic induction and immediately before extubation. METHODS: Of the 60 patients who had general anesthesia for aesthetic plastic surgery, 30 received 4 mg of IV ondansetron before anesthetic induction (control group) and 30 received 4 mg of IV ondansetron before anesthetic induction plus 4 mg IV immediately before extubation (experimental group). The PONV was recorded in the postanesthetic care unit and in the hospital room. RESULTS: The total occurrence of PONV (n = 60) was 6.7%. In the postanesthetic care unit, one patient in the experimental group (3.3%) manifested this symptom. In the hospital room, two patients in the control group (6.7%) and one patient in the experimental group (3.3%) manifested PONV. CONCLUSION: According to the findings, there was no statistical difference between the groups. However, the dosage used in the control group was effective and less expensive.

Adult↗
PubMedDate not supplied

British plastic surgeons who contributed to the Revue de Chirurgie Plastique and the Revue de Chirurgie Structive (1931-1938): "the Big Four" in their Speciality.

The Revue de Chirurgie Plastique and the Revue de Chirurgie Structive, Brussels (1931-1938), edited by Maurice Coelst, M.D. from Brussels, were the first, full-fledged medical publications devoted specifically to plastic, reconstructive, and aesthetic surgery. Publishing original articles by H.D. Gillies, P.T. Kilner, A.H. McIndoe, and R. Mowlem--the "Big Four" as they were known to both English and American plastic surgeons--the Revues drew attention to these four surgeons who were mainly responsible for developing the prestige of English plastic surgery in the early 1930s.

Belgium↗
PubMed1999

Mechanisms of experience-dependent plasticity in the auditory localization pathway of the barn owl.

Sound localization is a computational process that requires the central nervous system to measure various auditory cues and then associate particular cue values with appropriate locations in space. Behavioral experiments show that barn owls learn to associate values of cues with locations in space based on experience. The capacity for experience-driven changes in sound localization behavior is particularly great during a sensitive period that lasts until the approach of adulthood. Neurophysiological techniques have been used to determine underlying sites of plasticity in the auditory space-processing pathway. The external nucleus of the inferior colliculus (ICX), where a map of auditory space is synthesized, is a major site of plasticity. Experience during the sensitive period can cause large-scale, adaptive changes in the tuning of ICX neurons for sound localization cues. Large-scale physiological changes are accompanied by anatomical remodeling of afferent axons to the ICX. Changes in the tuning of ICX neurons for cue values involve two stages: (1) the instructed acquisition of neuronal responses to novel cue values and (2) the elimination of responses to inappropriate cue values. Newly acquired neuronal responses depend differentially on NMDA receptor currents for their expression. A model is presented that can account for this adaptive plasticity in terms of plausible cellular mechanisms.

Animals↗
PubMed2002

Dissociating ocular dominance column development and ocular dominance plasticity: a neurotrophic model.

Recent experimental data indicate that both neurotrophic factors (NTFs) and intracortical inhibitory circuitry are implicated in the development and plasticity of ocular dominance columns. We extend a neurotrophic model of developmental synaptic plasticity, which previously failed to account correctly for the differences between monocular deprivation and binocular deprivation, and show that the inclusion of lateral cortical inhibition is indeed necessary in understanding the effects of visual deprivation in the model. In particular, we argue that monocular deprivation causes a differential shift in the balance between inhibition and excitation in cortical columns, down-regulating NTFs in deprived-eye columns and up-regulating NTFs in undeprived-eye columns; during binocular deprivation, however, no such shift occurs. We thus postulate that the response to visual deprivation is at the level of the cortical circuit, while the mechanisms of afferent segregation are at the molecular or cellular level. Such a dissociation is supported by recent experimental work challenging the assumption that columnar organisation develops in an activity-dependent, competitive fashion. Our extended model also questions recent attempts to distinguish between heterosynaptic and homosynaptic models of synaptic plasticity.

Animals↗
PubMed2002

Spike-timing dependent synaptic plasticity: a phenomenological framework.

In this paper a phenomenological model of spike-timing dependent synaptic plasticity (STDP) is developed that is based on a Volterra series-like expansion. Synaptic weight changes as a function of the relative timing of pre- and postsynaptic spikes are described by integral kernels that can easily be inferred from experimental data. The resulting weight dynamics can be stated in terms of statistical properties of pre- and postsynaptic spike trains. Generalizations to neurons that fire two different types of action potentials, such as cerebellar Purkinje cells where synaptic plasticity depends on correlations in two distinct presynaptic fibers, are discussed. We show that synaptic plasticity, together with strictly local bounds for the weights, can result in synaptic competition that is required for any form of pattern formation. This is illustrated by a concrete example where a single neuron equipped with STDP can selectively strengthen those synapses with presynaptic neurons that reliably deliver precisely timed spikes at the expense of other synapses which transmit spikes with a broad temporal distribution. Such a mechanism may be of vital importance for any neuronal system where information is coded in the timing of individual action potentials.

Action Potentials↗
PubMed2006

A biophysical basis for the inter-spike interaction of spike-timing-dependent plasticity.

Although spike-timing-dependent plasticity (STDP) is well characterized when pre- and postsynaptic spikes are paired with a given time lag, how this generalizes for more complex spike-trains is unclear. Recent experiments demonstrate that contributions to synaptic plasticity from different spike pairs within a spike train do not add linearly. In the visual cortex conditioning with spike triplets shows that the effect of the first spike pair dominates over the second. Using a previously proposed calcium-dependent plasticity model, we show that short-term synaptic dynamics and interaction between successive back-propagating action potentials (BPAP) may jointly account for the nonlinearities observed. Paired-pulse depression and attenuation of BPAPs are incorporated into the model through the use-dependent depletion of pre- and postsynaptic resources, respectively. Simulations suggest that these processes may play critical roles in determining how STDP operates in the context of natural spike-trains.

Action Potentials↗
PubMed2002

Intestinal perforation in a parastomal hernia by a migrated plastic biliary stent.

Organ perforation is a well-described complication of plastic biliary stent placement [1, 2, 3, 4, 5, 6, 7, 8, 9, 10][1-10]. Most commonly, a stent will cause duodenal perforation while still in the area of the biliary system. This often occurs in the setting of a periampullary diverticulum. Less frequently, a perforation occurs as a result of stent migration into the distal lumenal gastrointestinal tract. These cases have involved a migrated stent impacting at the level of the ileum or a sigmoid colon diverticulum. A plastic biliary stent causing perforation inside an incarcerated small bowel hernia sac has been reported [10]. We describe the first reported case of a plastic biliary stent causing perforation inside a parastomal hernia.

Aged↗
PubMed1998

Tissue thermal damage caused by bipolar forceps can be reduced with a combination of plastic and metal.

BACKGROUND: We created a new 5-mm bipolar forceps. Thermo-insulating plastic was used for the creation of the jaws, while the metal conductor is buried deep inside the plastic. METHODS: A porcine model was used in experimental testing against a standard metallic 5-mm bipolar forceps at three different wattage settings (20, 40, 60 W). Histological sections were evaluated by a pathologist who was blind to the wattage and instrument tested. RESULTS: The new instrument was shown to cause statistically significant reduced thermal damage. In addition, its lateral thermal diffusion is superior to standard bipolar forceps. CONCLUSIONS: Thermo-insulating plastics can reduce thermal damage to tissue during electrosurgery.

Animals↗
PubMed2006

Effect of surfactants on plasticizer biodegradation by Bacillus subtilis ATCC 6633.

The biodegradation of plasticizers has been previously shown to result in the accumulation of metabolites that are more toxic than the initial compound. The present work shows that the pattern of degradation of di-2-ethylhexyl adipate by Bacillus subtilis can be significantly altered by the presence of biosurfactants, such as surfactin, or synthetic surfactants, such as Pluronic L122. In particular, this work confirms that the monoester, mono-2-ethylhexyl adipate, is a metabolite in the breakdown of the plasticizer. This metabolite was proposed but not observed in earlier studies. Toxicity measurements showed it to be significantly more toxic than the plasticizer. Thus, the effect of the surfactants was to significantly increase the accumulation of one or both of the two most toxic metabolites; i.e., the monoester and 2-ethylhexanol. It was proposed that the most likely cause of the effect of the surfactants was the sequestering of these two metabolites into mixed micelles, resulting in their reduced availability for further degradation.

Adipates↗
PubMed2005

Inactivation of C/EBP transcription factors specifically affects the synaptic plasticity of a common snail neuron.

Our previous studies showed that the acquisition of nociceptive sensitization in common snails is accompanied by long-term facilitation of synaptic transmission in defensive behavior command neuron LP11, this being dependent on translation and transcription processes. The characteristics of the neurochemical mechanisms of plasticity in the different sensory inputs of this nerve cell were identified. The mechanisms of induction of synaptic facilitation of the responses of neuron LP11 to chemical sensory stimulation of the snail's head involved NMDA glutamate receptors, serotonin receptors, cAMP, and serotonin-modulated transcription-regulating protein SMP-69. The mechanisms of induction of synaptic facilitation of another sensory input of the neuron--from tactile receptors on the head - involved protein kinase C. The present study addresses the involvement of C/EBP transcription factors (CCAAT-enhancer-binding protein) in the processes of synapse-specific plasticity of neuron LP11 during the acquisition of sensitization in snails. C/EBP was inactivated using oligonucleotides specifically binding to these proteins. The results showed that acquisition of sensitization during intracellular administration of oligonucleotides led to the selective suppression of synaptic facilitation in the responses of neuron LP11 to chemical sensory stimulation of the snail's head. Synaptic facilitation in the responses to tactile stimulation of the head or foot developed as in neurons in control sensitized snails. It is suggested that C/EBP transcription factor is selectively involved in the mechanisms of synapse-specific plasticity of the sensory input of neuron LP11 from chemoreceptors on the head during the acquisition of sensitization in snails.

Action Potentials↗
PubMed2006

Use of surfactants as plasticizers in preparing solid dispersions of poorly soluble API: stability testing of selected solid dispersions.

PURPOSE: The purpose of the study is to evaluate the effect of surfactant-plasticizers on the physical stability of amorphous drug in polymer matrices formed by hot melt extrusion. METHOD: Solid dispersions of a poorly soluble drug were prepared using PVP-K30, Plasdone-S630, and HPMC-E5 as the polymeric carriers and surfactants as plasticizers. The solid dispersions were produced by hot melt extrusion at temperatures 10 degrees C above and below the glass transition temperature (Tg) of the carrier polymers using a 16 mm-Haake Extruder. The surfactants tested in this study included Tween-80 and Docusate Sodium. The particle size of the extrudate was reduced to have mean of 100-200 micron. The physical stability of the solid dispersions produced was monitored at 30 degrees C/60% for six-months and at 60 degrees C/85% for two-months in open HDPE bottles. Modulated differential scanning calorimetry, polarized light microscopy, powder X-ray diffraction and dissolution testing was performed to assess the physical stability of solid dispersions upon stress testing. RESULTS: The dispersions containing HPMC-E5 were observed especially to be susceptible to physical instability under an accelerated stress conditions (60 degrees C/85%RH) of the solid dispersion. About 6% conversion of amorphous drug to crystalline form was observed. Consequently, the system exhibits similar degree of re-crystallization upon addition of the surfactant. However, under 30 degrees C/60%RH condition, the otherwise amorphous Drug-HPMC-E5 system has been destabilized by the addition of the surfactant. This effect is much more reduced in the extruded solid dispersions where polymeric carriers such as Plasdone S-603 and PVP-K30 (in addition to surfactants) are present. Furthermore, the drug release from the solid dispersions was unaffected at the stress conditions reported above. CONCLUSIONS: Possible reasons for the enhanced stability of the dispersions are due to the surfactants ability to lower the viscosity of the melt, increase the API solubility and homogeneity in the carrier polymer. In contrast, while it is possible for the surfactants to destabilize the system by lowering the Tg and increasing the water uptake, the study confirms that this effect is minimal. By and large, the surfactants appear to be promising plasticizers to produce solid dispersions by hot melt extrusion, in so doing improving dissolution rate without compromising the physical stability of the systems.

Calorimetry, Differential Scanning↗
PubMed1989

Plastic surgery for cardiac valves: 15 years' experience.

We suggest that all patients with heart valve diseases should be considered for reconstructive plastic surgery, regardless of the numerous modern mechanical and biological prostheses available in a cardiac surgeon's arsenal. We have 15 years of experience, with 903 plastic surgical procedures with cardiopulmonary bypass for acquired mitral (636), aortic (51), and tricuspid (216) valve diseases. The 15-year survival rate for patients with mitral stenosis was 68% +/- 5%, and the 8-year survival rate for patients with mitral insufficiency was 81% +/- 3%. The 10-year survival rate for patients with mitral and tricuspid valve disease was 59% +/- 3% because of the initially grave condition of such patients. For the correction of acquired aortic valve disease we advocate a new type of operation: a method of stent plasty of the aortic root with two circular sutures placed on the level of the arch and fibrotic ring. In combination with gradual commissurotomy, parietal resection of leaflets and parocommissural plication are performed. This procedure is an effective method for the plastic reconstruction of the aortic valve, and it provides a good hemodynamic effect.

Humans↗
PubMed1989

Down-regulation of norepinephrine sensitivity after induction of long-term neuronal plasticity (kindling) in the rat dentate gyrus.

Actions of norepinephrine (NE) in the dentate gyrus were examined before and after kindling-induced epilepsy, neuronal plasticity produced by daily high-frequency stimulation. NE, acting on beta 1-receptors, depolarized granule cells, increased input resistance, firing and influx of Ca2+ in response to repetitive stimulation, and elicited long-lasting potentiation of synaptic potentials. In addition, NE acting via alpha 1-receptors, attenuated Ca2+-dependent regenerative potentials. After kindling-induced plasticity, there were marked reductions in all these effects of NE on granule cells, changes likely to influence kindling-induced seizures, protecting against further enhancement of excitability once plasticity is in place.

Action Potentials↗
PubMed1996

Vanilloid receptor loss is independent of the messenger plasticity that follows systemic resiniferatoxin administration.

Resiniferatoxin (RTX) depletes vanilloid (capsaicin) receptors from lumbar dorsal root ganglia (DRG) of the rat. In addition, RTX causes changes in neuropeptide and nitric oxide synthase expression in lumbar DRG neurons, similar to those described following axotomy; this latter phenomenon is referred to as messenger plasticity. These findings suggested that vanilloid receptor loss may be part of the plasticity that follows RTX treatment. Here we show that vanilloid receptor expression, as detected by [3H]RTX autoradiography, is not changed in lumbar DRGs of axotomized rats, nor is it altered in a rat model (chronic constriction injury) of neuropathic pain. Thus, the in vivo expression of vanilloid receptors detected by specific [3H]RTX binding does not require the presence of intraaxonally transported trophic factors such as nerve growth factor. We conclude that messenger plasticity and vanilloid receptor loss are mediated by distinct mechanisms.

Animals↗
PubMed1981

Plastic surgery in a large hospital.

It may be debated whether the interaction between plastic surgery and other specialties is important enough to justify the presence of a department of plastic surgery in a large teaching hospital. To provide some data on which to base such discussion we have analysed the interaction at the Rigshospitalet in Copenhagen over a ten year period (1970-1980). In the plastic surgery department almost 10% of all the operations were on patients from the wards of ther departments. One tenth of these operations were combined operations carried out in collaboration with surgeons from other specialties. Otherwise intractable conditions may be cured by such combined activity and a properly organised "skin-grafting service" pays handsome dividends by shortening the healing time for ulcers within the hospital.

Child, Preschool↗
PubMed1986

The place of plastic surgery in the undergraduate surgical curriculum.

This paper reports the findings of a national survey of Medical Schools and Plastic Surgery Units. The survey has shown that plastic surgery is included in the undergraduate curriculum of 78% of the Medical Schools in the United Kingdom, and that this teaching load is shared by 77% of the Plastic Surgery Units in the United Kingdom. The results of a survey of medical students from the University of Oxford are also presented.

Curriculum↗
PubMed1990

A brief history of the development of plastic surgery in The Netherlands East-Indies from World War I until the independence of Indonesia (1914-1950).

This study of surgical operations published in the Medical Journal of the Netherlands East-Indies over the period 1914-1950, supplemented with a series of interviews with retired Dutch East-Indian surgeons and their relatives, shows a vivid interest in plastic surgery from World War I until the independence of Indonesia. One can conclude that plastic surgery was performed more frequently and on a larger scale than in Holland, due to a larger number of patients, specific tropical pathology and often a longer patient delay, requiring extensive reconstructive procedures. The East-Indian publications on plastic surgical topics outnumber the Dutch ones enormously.

History, 19th Century↗
PubMed1994

Outcome audit in plastic surgery: the Cambridge Classification.

Plastic Surgery Outcome Audit has until now been limited to studies of individual conditions. The Department of Plastic Surgery at Addenbrooke's Hospital, Cambridge, has developed an objective outcome classification applicable to all plastic surgery procedures. The four end-result categories--aesthetic appearance; physical function; tumour clearance; and surgical complications--are each graded in clear stages from 1 (excellent result) to 4 (result requiring re-operation) in a system which is easy to apply to every patient. The development and potential use of this classification are discussed. The Cambridge Classification is used in conjunction with diagnostic codes, which can be simple like the Logbook codes used by British Trainees or more complex, such as Read codes.

England↗