SEARCH · Search PubMed

Results for “PLASTICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources

PubMed2005

Decreased input-specific plasticity of the auditory cortex in mice lacking M1 muscarinic acetylcholine receptors.

Muscarinic acetylcholine receptors are extensively involved in cortical cognition and learning-induced or experience-dependent cortical plasticity. The most abundant muscarinic receptor subtype in the cerebral cortex is the M1 receptor, but little is known about its contribution to experience-dependent plasticity of the adult auditory cortex. We have examined the role of the M1 receptor in experience-dependent plasticity of the auditory cortex in mice lacking the M1 (chrm1) gene. We show here that electrical stimulation of the basal forebrain, a major source of cortical cholinergic inputs, facilitated the auditory responses of cortical neurons in both wild types and M1 mutants. The basal forebrain stimulation alone caused change in the best frequencies of cortical neurons that were significantly greater in M1 mutants. When animals received the paired stimuli of electrical stimulation of the basal forebrain and tone, the frequency tuning of cortical neurons systematically shifted toward the frequency of the paired tone in both wild types and M1 mutants. However, the shift range in M1 mutants was much smaller than that in wild-type mice. Our data suggest that the M1 receptor is important for the experience-dependent plasticity of the auditory cortex.

Adaptation, Physiological↗

PubMed1991

Potential application of shape memory plastic as elastic material in clinical orthodontics.

Polynorbornen, a shape memory plastic developed in Japan, has a glass transitional point of 35 degrees C. Once the environmental temperature exceeds the critical point, this plastic will begin to display an elastic property, then return to its original shape, if deformed. We examined whether the force generated during the elastic phase of polynorbornen could be used to displace human teeth. We found that the shape memory plastic wire of 1 mm in diameter stretched to two to three times of its original length at a temperature of 50 degrees C and a speed of 0.5 mm/sec would exert a relatively stable continuous light force of 119-156 g to move the teeth. This new material, compared with conventional elastic modules used in orthodontic therapy, exhibited a lesser degree of force degradation at a body temperature of 37 degrees C for a long period, and can be manufactured to near the tooth colour required. These advantages make feasible clinical application of the shape memory plastic in orthodontics.

Body Temperature↗

PubMedDate not supplied

Analysis of the neurotoxic plasticizer n-butylbenzenesulfonamide by gas chromatography combined with accurate mass selected ion monitoring.

The plasticizer, n-butylbenzenesulfonamide (NBBS), is reported to be neurotoxic when inoculated intracisternally or intraperitoneally into rabbits. Because NBBS is commonly used in the production of polyamide (nylon) plastics and is soluble in water, the disposal of NBBS-containing plastics in landfill sites could result in NBBS appearing in the leachate. Further, NBBS could also be leached from packaging into their contents. To allow us to examine the risks posed by NBBS in the environment, we have developed a quantitative assay for this compound. The assay employs a one-step extraction into dichloromethane followed by gas chromatography with accurate mass selected ion recording. The assay incorporates [13C6]NBBS as an internal standard to allow precise quantitation, and four separate ion chromatograms are recorded. NBBS was found in some Australian domestic solidwaste landfill leachate (from less than 0.3 to 94.6 ng/mL), but ground water in the vicinity of a landfill had only trace quantities of NBBS. NBBS was also quantitated in some bottled and cask wines, and levels varied from not detected to 2.17 ng/mL (n = 14). Additional studies are required to assess the public health risks associated with the use of NBBS as a plasticizer.

Gas Chromatography-Mass Spectrometry↗

PubMed2004

Olfactory loss in poly (acrylonitrile-butadiene-styrene) plastic injection-moulding workers.

BACKGROUND: Plastics manufacturing factories are the fifth largest category of factories in industrial estates in Taiwan. It is known that complex airborne compounds and pungent odours are emitted during plastic injection-moulding processes. Workers exposed to acrylonitrile-butadiene-styrene (ABS) thermal decomposition products (TDP) may have olfactory loss. AIMS: This study examined olfactory loss in injection-moulding workers exposed to ABS TDP. METHODS: The method recommended by the Connecticut Chemosensory Clinical Research Center (CCCRC) was used to test the olfactory function of subjects, including 1-butanol threshold and odour identification, both pre- and post-work. The study sample included 52 ABS plastic injection-moulding workers (exposed group), as well as 72 workers from other departments (reference group). RESULTS: The results revealed that the exposed group had lower olfactory function after work than the reference group. The decrease in olfactory function after 1 workday was statistically significant. The prevalence of abnormal olfactory function post-work in the exposed group was higher than in the reference group. CONCLUSIONS: The findings of this study implied the ABS plastic injection-moulding process may worsen olfactory function among workers. Notably, this effect decreased olfactory threshold scores, not odour identification scores.

Acrylic Resins↗

PubMed1982

Clinical correlates of neural plasticity.

The purpose of this article is to relate the concepts of mammalian nervous system plasticity to clinical practice. The clinical relevance of Dr. Bishop's four-part review of prenatal and postnatal maturation, function-induced plasticity, and nervous system regeneration is discussed. The scope of this paper is limited to the relationship between plasticity and 1) the pathogenesis of congenital malformations, 2) skill acquisition in the infant, and 3) functional recovery and treatment. Limitations in current clinical evidence for functional recovery are examined, and research questions that must be answered are presented. Clinical evidence of functional recovery coupled with current concepts of neural plasticity will provide information to determine the efficacy of treatment intervention for the neurologically handicapped. It is hoped that this discussion will encourage clinicians to renew their efforts to accurately document the clinical course of recovery and the treatment methods used to achieve this recovery and to report their findings.

Anencephaly↗

PubMed1985

Neural plasticity in schizophrenia.

No current biological hypothesis can assimilate the genetic, environmental, and clinical features of schizophrenia. If, as some authors contend, environmental factors have important effects on the course of schizophrenia, then a fruitful research concern may be the adaptation of neuronal circuitry to environmental changes. The plasticity of neuronal connections has been studied by subjecting animals to neurosurgical lesions, brain electro-stimulation, and a variety of rearing environments. The present article approaches the schizophrenia research literature from a theoretical perspective which takes into account the plasticity of neuronal connections. In a speculative manner, it demonstrates how neural plasticity concepts can be invoked to explain the following seemingly disparate features of schizophrenia: the pharmacological support for the dopamine hypothesis, the delayed onset and offset of neuroleptic antipsychotic action, genetic and environmental influences in schizophrenia, the regional alterations in brain structure and function seen in chronic schizophrenic patients, and the various types of behavioral symptoms exhibited by schizophrenic patients. In view of the explanatory potential of neural plasticity concepts, a research program that focuses on these concepts seems warranted.

Animals↗

PubMed1996

Asphyxial suicides using plastic bags.

Fifty-three suicides using plastic bags were identified in a review of cases within the jurisdiction of the King County Medical Examiner's Office, Seattle, Washington from 1984 to 1993. We found that this method was used at a greater frequency by individuals older than 50 in comparison with other methods. The most commonly identified stressor leading to the suicide in this population was failing health. The use of this method as a means of "self deliverance," as advocated by the Hemlock Society, could be inferred in only a small minority of cases where terminal illnesses were identified. This method may be preferred by those older than 50 years because of the ready availability of plastic bags and the relative nonviolence of the death. Analysis of the autopsy findings showed no specific features for this method of suicide. In particular, petechiae, which are often considered a marker of asphyxia, were present in only a small minority of cases (3%). Furthermore, the scene investigation rarely revealed specific features, other than the plastic bag in place. Thus, if the plastic bag were removed after death, the cause and manner of death would be obscure.

Adolescent↗

PubMed2000

Plastic bag asphyxia in southeast Scotland.

Death resulting from plastic bag asphyxia has been recognized for >40 years, but relatively little is known about either its epidemiology or its pathophysiology. Over 15 years (1984-1998), 30 deaths were attributed to plastic bag asphyxia among the 14,560 autopsies performed in the Forensic Medicine Unit in Edinburgh. These 30 deaths involved 20 male and 10 female subjects, with an age range of 13 to 81 years. Eleven had some alcohol measurable in the blood, with four having levels >80 mg/dl. Only one individual appeared to have ingested a drug overdose, but inhaled substances within the plastic bag may have contributed to death in five cases. The absence of childhood accidental deaths may reflect successful preventive measures. The 3 accidental deaths involved adults (including 2 who died of autoerotic asphyxia), and the remaining deaths were 27 suicides. Of those who committed suicide, most (59%) had chronic psychiatric illness rather than chronic debilitating or terminal physical illness. In contrast with reports from the United States, publicity associated with "self-deliverance" did not result in an increased number of deaths from plastic bag asphyxia (4 deaths in this series). Analysis of the circumstances of all the deaths revealed them to be difficult to predict and hence prevent.

Accidents↗

PubMed1978

Plastic surgery in the twentieth century.

Plastic surgical operations are among the oldest and have been developed increasingly from ancient times down to the present. However, the age of medical specialization did not begin until the latter part of the nineteenth century, and the specialty of plastic surgery is largely a child of the twentieth century. Most of the operations we do today have been created by plastic surgeons with the past 50 years, but were made possible only by the rapid developments in other surgical specialties and in all of medicine and science. The relationship with other specialties has been an interdependent one, and this is likely to be the pattern of the future. Plastic surgery, bridging the anatomical specialties as it does, must continue to draw bits of information here and there from them and to synthesize these into major contributions of great benefit to all. The specialty will grow in direct proportion to the success of the innovators within it in fulfilling their crucial role.

Europe↗

PubMed1988

Combined plastic and gynecological surgical procedures.

The purpose of the present study was to determine the extent to which the planned combination of one of several major plastic and gynecological surgical procedures may alter patient morbidity and postoperative hospitalization when compared with similar procedures carried out separately. A review of 10 consecutive years of operative procedures produced 63 patients who underwent combined gynecological and plastic surgical procedures. Thirty-three of the combined-surgery patients could be suitably matched with 2 control patients each to compare complications and length of hospital stay. The requirement for transfusion was significantly greater (p = 0.01) in the combined-surgery versus the paired-control groups. No other complications, however, were increased in the combined-surgery patients. There was a significant reduction (p = 0.005) in hospital stay of 1.92 postoperative days for two groups of combined-surgery patients versus the control groups. In all combined-surgery patients, patient response was favorable. Recommendations on preoperative planning and intraoperative and postoperative management are discussed. There is a perception in the surgical community that combining procedures unacceptably increases morbidity. For the past 12 years plastic and gynecological surgeons in our institution have offered combined procedures to our patients, with positive results and favorable patient response. A search of recent medical literature demonstrated several references to the planned combination of plastic and gynecological or general surgical procedures [2, 4, 5]. However, the only study with matched control patients dealt exclusively with abdominoplasty in association with one of five major gynecological procedures.

Blood Transfusion↗

PubMed1976

The plastic surgical adhesive drape: an evaluation of its efficacy as a microbial barrier.

A microbial evaluation was made of adhesive plastic surgical drapes and cloth surgical drapes. These studies were done both during surgery and in the laboratory. The plastic drape does not allow bacterial penetration, lateral migration does not occur, skin bacteria do not multiply under the drape within the time periods studied and the patient drapes are held in place with their use. When wet, cloth drapes showed profuse bacterial penetration. Dry cloth showed less bacterial penetration as compared to wet cloth. Lateral migration under cloth drapes was not possible to assess due to a high level of penetration. The surface of cloth showed a higher level of bacterial contamination during the surgical procedures. Deep wound cultures collected just prior to closing showed 60% contamination when cloth was used compared to 6% when plastic was employed. The micro-organisms recovered from the various sites sampled were identified. Finally, in addition to the positive aseptic benefits afforded by plastic adhesive drapes, aesthetic features such as a more delineated operative field and elimination of towel clips make this product a useful adjunct to the surgeon's armamentarium.

Air Microbiology↗

PubMed2001

Muscarinic dependence of nucleus basalis induced conditioned receptive field plasticity.

Receptive field (RF) plasticity in primary auditory cortex of adult animals, specifically selective increased response to a tonal conditioned stimulus (CS) relative to other frequencies, can be induced both by behavioral conditioning and by pairing a tone with stimulation of the nucleus basalis (NB). This study determined whether cortical muscarinic receptors are necessary for NB-induced RF plasticity. Single units in layers II-IV were studied in Urethane anesthetized adult rats. The cortex was perfused with saline or saline+atropine sulfate. Conditioning, 30 trials of pairing a tone with NB stimulation, produced a significant CS-specific response increase (n=8). Local atropine blocked NB-induced RF plasticity, actually resulting in CS-specific response decrease (n=6). Therefore, NB-induced RF plasticity requires engagement of muscarinic receptors in auditory cortex.

Acetylcholine↗

PubMed1997

Cellular and molecular bases of memory: synaptic and neuronal plasticity.

Discoveries made during the past decade have greatly improved our understanding of how the nervous system functions. This review article examines the relation between memory and the cellular mechanisms of neuronal and synaptic plasticity in the central nervous system. Evidence indicating that activity-dependent short- and long-term changes in strength of synaptic transmission are important for memory processes is examined. Focus is placed on one model of synaptic plasticity called long-term potentiation, and its similarities with memory processes are illustrated. Recent studies show that the regulation of synaptic strength is bidirectional (e.g., synaptic potentiation or depression). Mechanisms involving intracellular signaling pathways that regulate synaptic strength are described, and the specific roles of calcium, protein kinases, protein phosphatases, and retrograde messengers are emphasized. Evidence suggests that changes in synaptic ultrastructure, dendritic ultrastructure, and neuronal gene expression may also contribute to mechanisms of synaptic plasticity. Also discussed are recent findings about postsynaptic mechanisms that regulate short-term synaptic facilitation and neuronal burst-pattern activity, as well as evidence about the subcellular location (presynaptic or postsynaptic) of mechanisms involved in long-term synaptic plasticity.

Action Potentials↗

PubMed2000

Magnetoencephalographic studies of functional organization and plasticity of the human auditory cortex.

Magnetoencephalography has proven to be a powerful noninvasive tool for investigating the functional organization of the human auditory cortex and its plastic changes. The first part of this review summarizes some recent experiments on the tonotopic organization, which can be observed not only in the slow auditory evoked fields, but also in the middle-latency and the steady-state fields. In the second part of this review, recent studies on plasticity of the auditory cortex are outlined. These studies showed that the cortical representation of tones may change within hours after a reversible "functional deafferentation" (short-term plasticity) and that early musical training leads to an expansion in the cortical representation of complex harmonic sounds (long-term plasticity).

Acoustic Stimulation↗

PubMed1994

Molecular psychiatry. Adaptations of receptor-coupled signal transduction pathways underlying stress- and drug-induced neural plasticity.

Advances in molecular biology and neuroscience are leading to new opportunities for elucidation of the pathophysiology of psychiatric disorders and the long-term actions of psychotropic drugs. The actions of first messengers, including neurotransmitters, neuropeptides, and neurotrophins, on neuronal function can now be viewed in terms of their regulation of complex intracellular signal transduction pathways. These pathways mediate most actions of first messengers, including fast mediatory (e.g., cell firing), short-term modulatory (e.g., neuronal metabolism, receptor sensitivity, neurotransmitter sensitivity), and long-term modulatory (e.g., gene expression). Moreover, it is becoming increasingly evident that adaptations of receptor-coupled intracellular pathways, referred to here as neural plasticity, mediate the long-term actions of psychotropic drug treatments. In addition, an inability to mount the appropriate adaptive responses to environmental stressors could contribute to the pathophysiology of psychiatric disorders. The following provides a brief overview of receptor-coupled intracellular signal transduction pathways in brain and general mechanisms of neural plasticity. Specific examples of neural plasticity in response to stress, antidepressant treatments, and drugs of abuse are discussed in greater detail. Continued elucidation of the intracellular signal transduction pathways which govern neuronal function and the mechanisms that mediate neural plasticity will provide the basis for the development of more effective and fast-acting therapeutic agents, as well as identification of the abnormalities underlying psychiatric disorders.

Antidepressive Agents↗

PubMed1996

Pediatric craniocerebral wounds from plastic bullets: prognostic implications, course, and outcome.

OBJECTIVE: To review our experience with craniocerebral injuries caused by plastic bullets, and to delineate prognostic factors for outcome. DESIGN: Retrospective case series of 29 patients presenting with plastic bullet-induced craniocerebral lesions. SETTING: Pediatric intensive care department of a tertiary care center. MEASUREMENTS AND MAIN RESULTS: Outcome was poor in 10 patients, good in 11, and two and six patients were moderately and severely disabled, respectively. Statistical analysis showed prognostic significance of the admission Glasgow Coma Scale score, computed tomographic findings of intraventricular hemorrhage and midline shift, and metabolic studies including hypokalemia and hyperglycemia. CONCLUSIONS: Plastic bullet-induced craniocerebral injuries carry a lower morbidity and mortality rate compared with other gunshot wounds. However, plastic bullets do incur a significant risk of injury. Their use should be carefully regulated.

Adolescent↗

PubMed1999

Plastic bullet injuries in Northern Ireland: experiences during a week of civil disturbance.

BACKGROUND: Plastic bullets were introduced to Northern Ireland for riot-control purposes in 1973. Their use has been controversial, with a number of fatalities. In the week beginning July 7, 1996, some 8,000 plastic bullets were fired during widespread rioting. METHODS: Details of injuries attributed to plastic bullets were obtained retrospectively from patient notes for the period July 8 to 14, 1996, in six hospitals. A total of 172 injuries in 155 patients were recorded. RESULTS: Nineteen percent of injuries were to the face/head/neck, 20% were to the chest or abdomen, and 61% were to the limbs. Abbreviated Injury Scale scores ranged from I to 3. Forty-two patients were admitted for hospitalization, three to intensive care units. No fatalities occurred. CONCLUSION: Plastic bullet impact to the abdomen or above may cause life-threatening injuries. Below this site, major trauma is unlikely.

Abbreviated Injury Scale↗

PubMed1998

Research priorities and concerns of plastic surgical nurses.

The advancement of nursing knowledge to improve clinical plastic surgical nursing practice was identified as a priority for the American Society of Plastic and Reconstructive Surgical Nurses (ASPRSN). The purpose of this investigation was to determine the specific research priorities and perspectives of practicing plastic surgical nurses. In addition, nurses were asked to rank their current concerns for the future of plastic surgical nursing.

Attitude of Health Personnel↗