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PubMed2004

Storage of serum in plastic and glass containers may alter the serum concentration of polychlorinated biphenyls.

Valid exposure assessment and biomonitoring of toxicants rely on standardized specimen collection, handling, storage, and measurement. In a study designed to determine organochlorine concentrations in blood samples, we recruited participants from registered anglers in Michigan. After participants were interviewed, blood was collected from study subjects, either at home by a phlebotomist or in a commercial blood-draw station. The phlebotomists stored their samples in glass containers, but without our knowledge, the commercial laboratory transferred the specimens to plastic containers for freezing in its central facility. Samples were analyzed in the Analytical Chemistry Section Laboratory of the Michigan Department of Community Health. This laboratory also provided information on storage in glass (n = 28) versus plastic containers (n = 113). We conducted linear regression analyses to assess factors that may explain the concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), and polybrominated biphenyls (PBBs). Our results indicate that storage of serum in plastic containers altered the total concentrations of PCBs, in particular, the higher chlorinated PCBs (PCB-180 and PCB-199), but not DDE or PBBs. No other characteristics of the samples could explain the higher PCB values (0.75 micro g/L vs. 0.45 micro g/L; p = 0.025) of those stored in plastic containers. The proportion of PCB detects in both subsamples did not differ. Some preceding studies have provided information on whether specimens were stored in glass or plastic containers; however, a number of studies have not. We suggest the initiation of a new review process to determine whether these earlier reports were based on unbiased PCB determinations. We recommend standardizing specimen collection, handling, storage, and measurement, which is particularly necessary for newly emerging analytes.

Adult↗
PubMed2004

Comparison of samples obtained from 3.2% sodium citrate glass and two 3.2% sodium citrate plastic blood collection tubes used in coagulation testing.

We sought to compare coagulation test results obtained from patients using 2 plastic blood collection tubes and the traditional glass blood collection tube. Blood specimens were obtained from 241 patients in 3.2% buffered sodium citrate using standard glass tubes, in 3.2% buffered sodium citrate in plastic tubes, and in 3.2% sodium citrate "sandwich" tubes (plastic within plastic). All samples were obtained and processed contemporaneously and tested for prothrombin time (PT) and activated partial thromboplastin time (aPTT). Residual plasma was frozen at -70 degrees C for future testing, including fibrinogen, antithrombin, plasminogen, protein C and protein S (functional and antigenic), dilute Russell viper venom time (DRVVT), ristocetin cofactor, factor XIII, D dimer, anti-Xa activity, and prothrombin fragment. Although paired t test analysis revealed statistically significant differences (P < .05) between glass and plastic for PT, aPTT, fibrinogen, protein C (functional and antigenic), functional protein S, DRVVT and confirmation method, antithrombin, and factor XIII, these differences were not considered clinically significant.

Blood Coagulation Tests↗
PubMed2001

Use of glass capillaries avoids the time changes in high blood PO(2) observed with plastic syringes.

STUDY OBJECTIVES: In adults, arterial blood samples are usually drawn using plastic syringes. In contrast to glass syringes, plastic syringes let oxygen diffuse through their wall. This results in PO(2) changes during storage, especially when PO(2) is high. An alternative to glass syringes is the Microsampler (Roche Diagnostics; Schaffhausen, Switzerland), a commercially available device consisting of a heparinized glass capillary fitted with a 26-gauge needle and used to collect arterial blood in the same way as a plastic syringe fitted with a needle. DESIGN: We evaluated the performance of the Roche Microsampler for storing arterial blood in view of PO(2) measurement, comparatively with glass and plastic syringes. Five approximate initial PO(2) levels (650, 400, 200, 130, and 80 mm Hg) and two storage temperatures (ambient temperature and 4 degrees C) were studied. SETTINGS: Bench study. RESULTS: Plastic syringes allowed reliable measurement of PO(2) values when initial PO(2) was too low to ensure complete hemoglobin oxygen saturation, but were associated with time-dependent underestimation of PO(2) at higher initial PO(2) values. No such underestimation occurred with the Roche Microsampler stored at 4 degrees C for up to 1 h for all PO(2) levels studied. CONCLUSION: The Roche Microsamplers appeared to be reliable devices in preventing oxygen diffusion.

Blood Specimen Collection↗
PubMed2002

Do apoptotic mechanisms regulate synaptic plasticity and growth-cone motility?

Signals between neurons are transduced primarily by receptors, and second messenger and kinase cascades, located in pre- and postsynaptic terminals. Such synaptic signaling pathways include those activated by neurotransmitters, cytokines, neurotrophic factors, and cell-adhesion molecules. Many of these signaling systems are also localized in the growth cones of axons and dendrites, where they control pathfinding and synaptogenesis during development. Although it has been known for decades that such signaling pathways can affect the survival of neurons, by promoting or preventing a form of programmed cell death known as apoptosis, we have discovered that apoptotic biochemical cascades can exert local actions on the functions and structural dynamics of growth cones and synapses. In this article, we provide a brief background on apoptotic biochemical cascades, and present examples of studies in this laboratory that have identified novel apoptotic and anti-apoptotic signaling mechanisms that are activated and act locally in synapses, growth cones, and dendrites to modify their structure and function. Apoptotic synaptic cascades that may play roles in neuronal plasticity include activation of caspases that can cleave certain types of ionotropic glutamate-receptor subunits and thereby modify synaptic plasticity. Caspases may also cleave cytoskeletal protein substrates in growth cones of developing neurons and may thereby regulate neurite outgrowth. Par-4 and the tumor-suppressor protein p53 are pro-apoptotic proteins that may also function in synaptic and developmental plasticity. Examples of anti-apoptotic signals that regulate the plasticity of growth cones and synapses include neurotrophic factor-activated kinase cascades, calcium-mediated actin depolymerization, and activation of the transcription factor NF-kappaB. The emerging data strongly suggest that many of the signaling mechanisms that control apoptosis are also involved in regulating the structural and functional plasticity of neuronal circuits under physiological conditions.

Animals↗
PubMed2006

Learning-induced plasticity in deep cerebellar nucleus.

Evidence that cerebellar learning involves more than one site of plasticity comes from, in part, pavlovian eyelid conditioning, where disconnecting the cerebellar cortex abolishes one component of learning, response timing, but spares the expression of abnormally timed short-latency responses (SLRs). Here, we provide evidence that SLRs unmasked by cerebellar cortex lesions are mediated by an associative form of learning-induced plasticity in the anterior interpositus nucleus (AIN) of the cerebellum. We used pharmacological inactivation and/or electrical microstimulation of various sites afferent and efferent to the AIN to systematically eliminate alternative candidate sites of plasticity upstream or downstream from this structure. Collectively, the results suggest that cerebellar learning is mediated in part by plasticity in target nuclei downstream of the cerebellar cortex. These data demonstrate an instance in which an aspect of associative learning, SLRs, can be used as an index of plasticity at a specific site in the brain.

Animals↗
PubMed2005

Critical role of calcitonin gene-related peptide 1 receptors in the amygdala in synaptic plasticity and pain behavior.

The role of neuropeptides in synaptic plasticity is less well understood than that of classical transmitters such as glutamate. Here we report the importance of the G-protein-coupled calcitonin gene-related peptide (CGRP1) receptor as a critical link between amygdala plasticity and pain behavior. A key player in emotionality and affective disorders, the amygdala has been implicated in the well documented, but mechanistically unexplained, relationship between pain and affect. Our electrophysiological and pharmacological in vitro (patch-clamp recordings) and in vivo (extracellular single-unit recordings) data show that selective CGRP1 receptor antagonists (CGRP(8-37) and BIBN4096BS) in the amygdala reverse arthritis pain-related plasticity through a protein kinase A (PKA)-dependent postsynaptic mechanism that involves NMDA receptors. CGRP1 receptor antagonists inhibited synaptic plasticity in the laterocapsular division of the central nucleus of the amygdala (CeLC) in brain slices from arthritic rats compared with normal controls. The effects were accompanied by decreased neuronal excitability and reduced amplitude, but not frequency, of miniature EPSCs; paired-pulse facilitation was unaffected. The antagonist effects were occluded by a PKA inhibitor. CGRP1 receptor blockade also directly inhibited NMDA-evoked, but not AMPA-evoked, membrane currents. Together, these data suggest a postsynaptic site of action. At the systems level, the antagonists reversed the sensitization of nociceptive CeLC neurons in anesthetized rats in the arthritis pain model. Importantly, CGRP1 receptor blockade in the CeLC inhibited spinal (hindlimb withdrawal reflexes) and supraspinal pain behavior of awake arthritic rats, including affective responses such as ultrasonic vocalizations. This study provides direct evidence for the critical dependence of pain behavior on CGRP1-mediated amygdala plasticity.

Amygdala↗
PubMed2004

Postsynaptic density 95 controls AMPA receptor incorporation during long-term potentiation and experience-driven synaptic plasticity.

The regulated delivery of AMPA-type glutamate receptors (AMPARs) to synapses is an important mechanism underlying synaptic plasticity. Here, we ask whether the synaptic scaffolding protein PSD-95 (postsynaptic density 95) participates in AMPAR incorporation during two forms of synaptic plasticity. In hippocampal slice cultures, the expression of PSD-95-green fluorescent protein (PSD-95-GFP) increases AMPAR currents by selectively delivering glutamate receptor 1 (GluR1)-containing receptors to synapses, thus mimicking long-term potentiation (LTP). Mutational analysis shows that the N terminal of PSD-95 including the first two PDZ [PSD-95/Discs large (Dlg)/zona occludens-1 (ZO-1)] domains is necessary and sufficient to mediate this effect. Further supporting a role in synaptic plasticity, wild-type PSD-95 occludes LTP and dominant negative forms block LTP. Moreover, we demonstrate that PSD-95 also participates in AMPAR delivery during experience-driven plasticity in vivo. In the barrel cortex from experience-deprived animals, the expression of PSD-95-GFP selectively increases AMPAR currents, mimicking experience-driven plasticity. In nondeprived animals, PSD-95-GFP produces no additional potentiation, indicating common mechanisms between PSD-95-mediated potentiation and experience-driven synaptic strengthening. A dominant negative form of PSD-95 blocks experience-driven potentiation of synapses. Pharmacological analysis in slice cultures reveals that PSD-95 acts downstream of other signaling pathways involved in LTP. We conclude that PSD-95 controls activity-dependent AMPAR incorporation at synapses via PDZ interactions not only during LTP in vitro but also during experience-driven synaptic strengthening by natural stimuli in vivo.

Animals↗
PubMed2004

Learning modifies subsequent induction of long-term potentiation-like and long-term depression-like plasticity in human motor cortex.

Learning may alter rapidly the output organization of adult motor cortex. It is a long-held hypothesis that modification of synaptic strength along cortical horizontal connections through long-term potentiation (LTP) and long-term depression (LTD) forms one important mechanism for learning-induced cortical plasticity. Strong evidence in favor of this hypothesis was provided for rat primary motor cortex (M1) by showing that motor learning reduced subsequent LTP but increased LTD. Whether a similar relationship exists in humans is unknown. Here, we induced LTP-like and LTD-like plasticity in the intact human M1 by an established paired associative stimulation (PAS) protocol. PAS consisted of 200 pairs of electrical stimulation of the right median nerve, followed by focal transcranial magnetic stimulation of the hand area of the left M1 at an interval equaling the individual N20 latency of the median nerve somatosensory-evoked cortical potential (PAS(N20)) or N20-5 msec (PAS(N20-5)). PAS(N20) induced reproducibly a LTP-like long-lasting (>30 min) increase in motor-evoked potentials from the left M1 to a thumb abductor muscle of the right hand, whereas PAS(N20-5) induced a LTD-like decrease. Repeated fastest possible thumb abduction movements resulted in learning, defined by an increase in maximum peak acceleration of the practiced movements, and prevented subsequent PAS(N20)-induced LTP-like plasticity but enhanced subsequent PAS(N20-5)-induced LTD-like plasticity. The same number of repeated slow thumb abduction movements did not result in learning and had no effects on PAS-induced plasticity. Findings support the view that learning in human M1 occurs through LTP-like mechanisms.

Adult↗
PubMed2006

Visual experience regulates metabotropic glutamate receptor-mediated plasticity of AMPA receptor synaptic transmission by homer1a induction.

Brief metabotropic glutamate receptor (mGluR) activation leads to plasticity of AMPA receptor (AMPAR) synaptic transmission. To test whether mGluR-mediated plasticity of AMPAR transmission is influenced by recent neuronal activity, we manipulated visual activity in Xenopus laevis tadpoles in vivo. We compared mGluR-mediated plasticity of AMPAR transmission in optic tectal cells of tadpoles with low levels of previous synaptic activity (overnight in the dark) to transmission in neurons from animals after 4 h of constant visual stimulation. mGluR-mediated plasticity of AMPA transmission was significantly decreased in neurons with recent activity. We tested the role of the activity-regulated mGluR scaffolding protein Homer1a in modulating mGluR-mediated changes in AMPAR transmission. We found that, by changing the ratios of Homer 1a to Homer 1b in vivo, by either induction of endogenous Homer1a by visual activity or ectopic expression of Homer1a or Homer1b, we could change the direction of mGluR-mediated plasticity. This is the first evidence that mGluR-mediated changes in AMPA transmission can be regulated by Homer proteins in response to physiologically relevant stimuli.

Animals↗
PubMed2002

[The airborne 1,3-butadiene concentrations in rubber and plastic processing plants].

Environment pollution by 1,3-butadiene had considerably increased in Japan. The main cause of the pollution is the automotive exhaust gas, and leaks from factories, smoking, and burning of rubber and plastic products are considered to be minor sources. The object of this study was to determine the contamination levels of airborne 1,3-butadiene in factories processing rubber and plastics containing 1,3-butadiene. The concentrations of airborne 1,3-butadiene were measured in 21 plants (10 rubber processing plants and 11 plastics processing plants) in Osaka. 1,3-Butadiene in air was collected for 10 minutes with a charcoal tube and a portable small pump adjusted to a 250 ml/min flow rate. In each plant, indoor air samples at five points and an outdoor air sample at one point outside the plant were collected. The samples were subjected to gas chromatography/mass spectrometry after thermal desorption from the charcoal. The concentrations of airborne 1,3-butadiene in the rubber processing plants and the plastics processing plants were 0.14-2.20 micrograms/m3 (geometric mean: 0.48 microgram/m3) and 0.23-4.51 micrograms/m3 (geometric mean: 0.80 microgram/m3), respectively. In all plants examined, indoor 1,3-butadiene concentrations were higher than the outdoor concentrations around the plants. Therefore, 1,3-butadiene was considered to arise from the processing of rubber or plastics, but the indoor 1,3-butadiene concentrations were much lower than the PEL-TWA (1 ppm = 2.21 mg/m3) of OSHA and the TLV-TWA (2 ppm) of ACGIH. The concentrations in the plants with closed room conditions without ventilation were higher than the concentrations in the other plants. It was suggested that ventilation affected the 1,3-butadiene concentration in the plants.

Air Pollutants, Occupational↗
PubMed2002

Beyond easy answers: the plastic surgeon and prenatal diagnosis.

OBJECTIVE: To explore how plastic surgeons handle the issue of prenatal diagnosis of cleft lip and palate. DESIGN: Mail survey. PARTICIPANTS: The plastic surgeon listed as team contact in the team directory of the American Cleft Palate-Craniofacial Association was identified. In cases in which a plastic surgeon was not listed as a team contact, the first plastic surgeon listed as a team member was identified. A total of 211 surgeons were contacted. INTERVENTION: Each surgeon was mailed a survey asking for his/her experience in prenatal diagnosis for cleft conditions. Ethical issues concerning the surgeon's personal beliefs about abortion and the potential influence of the surgeon's presentation of information were explored. RESULTS: A 50% response rate was obtained. Eighty-five percent of respondents were experienced in prenatal counseling; 92% offer consults on a routine basis. Ninety-six percent indicated they did so because they felt it was helpful to families. Treatment (98%), appearance of clefts (96%), cleft etiology (94%), and associated problems (40%) were discussed most commonly. Termination was rarely discussed (5%). Of those who had not met with a family, 82% said they had never been asked to do so. Most respondents felt families sought consultation for information and rarely sought consultation to decide on abortion. The majority felt their personal beliefs about abortion did not influence their willingness to meet with parents. The majority of surgeons in both groups felt it was ethical to give an opinion on pregnancy termination if asked (55% of experienced surgeons, 44% of inexperienced surgeons); however, a significantly larger number of the surgeons who had not met with a family were unsure of their opinion. CONCLUSIONS: Prenatal counseling of parents of a fetus with cleft lip/palate is common among plastic surgeons. There is uniformity in the information discussed. There is no agreement among surgeons about the ethical issues of pregnancy termination and the surgeon's role in that discussion.

Abortion, Induced↗
PubMed1993

Pain and discomfort levels in patients during root surface debridement with sonic metal or plastic inserts.

The study was designed to evaluate whether root surface debridement with a sonic scaler plastic insert would cause less pain and discomfort to patients than an ordinary, probe-shaped metal sonic insert. One quadrant in each of 23 patients was debrided with each insert. Blood pressure, mean arterial pressure, and heart rate were monitored before, during, and immediately after each treatment. Pain was also evaluated on a visual analogue scale (VAS) after each treatment, as well as 2 weeks later following pain-provoking stimuli. Blood pressure, mean arterial pressure, and heart rate did not reveal any differences between quadrants treated with plastic or metal inserts. Heart rate had a weak, positive association with treatment time. The VAS gave a higher pain score for the plastic (30.8) than for the metal insert (24.4), but this difference was not statistically significant (P = 0.055). Following pain-provoking stimuli at the 2-week follow-up visit, quadrants debrided with the metal insert (31.3) scored significantly lower (less pain) (P < 0.01) on the VAS than quadrants treated with the plastic insert (30.7). It is concluded that the sonic metal insert caused less pain and discomfort to the patients due to its superior accessibility and water spray cooling. The significant difference between metal and plastic tip debrided quadrants at the follow-up visit was probably caused by the smearing effect of the metal insert with partial closure of the dentin tubule orifices.

Adult↗
PubMed2002

[Identification of unknown substances in polyvinyl chloride gloves containing non-phthalate plasticizers].

The use of polyvinyl chloride gloves containing di(2-ethylhexyl) phthalate for food contact applications is restricted. In their place, polyvinyl chloride gloves containing non-phthalate plasticizers (PVC-NP) have been introduced. They contained unknown substances, so they were studied by GC/MS, HR-MS and NMR. The chemical structures of the unknown substances were confirmed to be diethylene glycol dibenzoate, triethylene glycol dibenzoate, dipropylene glycol dibenzoate, and alkylsulfonic acid phenyl ester, which are plasticizers. Including di-isononyl adipate, the contents of the plasticizers were 37.5-48.9% in the PVC-NP gloves, and their migration levels were 1,010-1,390 ppm into n-heptane. These are very high levels. These plasticizers are not widely used for food contact polyvinyl chloride throughout the world, and they have also not been registered as self-standards by Japanese manufacturers. Careful consideration will be necessary for the selection of a suitable plasticizer substitute.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

The effectiveness of triclosan-incorporated plastic against bacteria on beef surfaces.

Triclosan is a nonionic, broad-spectrum, antimicrobial agent that has been incorporated into a variety of personal hygiene products, including hand soaps, deodorants, shower gels, mouthwashes, and toothpastes. In this study, plastic containing 1,500 ppm of triclosan was evaluated in plate overlay assays and meat experiments as a means of reducing populations of bacteria. Plate overlay assays indicated that the triclosan-incorporated plastic (TIP) inhibited the following organisms: Brochothrix thermosphacta ATCC 11509, Salmonella Typhimurium ATCC 14028, Staphylococcus aureus ATCC 12598, Bacillus subtilis ATCC 6051, Shigella flexneri ATCC 12022, Escherichia coli ATCC 25922, and several strains of E. coli O157:H7. In meat experiment 1, irradiated, lean beef surfaces inoculated with B. thermosphacta, Salmonella Typhimurium, E. coli O157:H7, or B. subtilis were covered with TIP, vacuum packaged, and stored for 24 h at 4 degrees C. Of the organisms tested, only populations of B. thermosphacta were slightly reduced. In meat experiment 2, prerigor beef surfaces were inoculated with E. coli O157: H7, Salmonella Typhimurium, or B. thermosphacta incubated at 4 degrees C for 24 h, wrapped in TIP or control plastic, vacuum packaged, and stored at 4 degrees C for up to 14 days. There was a slight reduction in the population of the organisms after initial application with TIP. However, bacterial populations following long-term, refrigerated (4 degrees C), vacuum-packaged storage up to 14 days were not statistically (P< or =0.05) or numerically different than controls. In meat experiment 3, even TIP-wrapped, vacuum-packaged beef samples that were temperature abused at 12 degrees C did not exhibit significant (P< or =0.05) or sustainable reductions after 14 days of 4 degrees C storage. Another study indicated that populations of E. coli O157:H7 or B. thermosphacta added directly to TIP were not affected after 2 h of refrigerated storage or that the antimicrobial activity could be extracted from the plastic. Additional experiments suggest that presence of fatty acids or adipose may diminish the antimicrobial activity of TIP on meat surfaces. This study demonstrates that while antimicrobial activity is detected against bacterial cultures in antimicrobial plate assays, plastic containing 1,500 ppm of triclosan does not effectively reduce bacterial populations on refrigerated, vacuum-packaged meat surfaces.

Animals↗
PubMed1999

Anatomical correlates of functional plasticity in mouse visual cortex.

Much of what is known about activity-dependent plasticity comes from studies of the primary visual cortex and its inputs in higher mammals, but the molecular bases remain largely unknown. Similar functional plasticity takes place during a critical period in the visual cortex of the mouse, an animal in which genetic experiments can readily be performed to investigate the underlying molecular and cellular events. The experiments of this paper were directed toward understanding whether anatomical changes accompany functional plasticity in the developing visual cortex of the mouse, as they do in higher mammals. In normal mice, transneuronal label after an eye injection clearly delineated the monocular and binocular zones of area 17. Intrinsic signal optical imaging also showed monocular and binocular zones of area 17 but revealed no finer organization of ocular dominance or orientation selectivity. In normal animals, single geniculocortical afferents serving the contralateral eye showed great heterogeneity and no clustering consistent with the presence of ocular dominance patches. Growth and elaboration of terminal arbor continues beyond postnatal day 40 (P40), after the peak of the critical period. After prolonged monocular deprivation (MD) from P20 to P60, transneuronal labeling showed that the projection serving the ipsilateral eye was severely affected, whereas the effect on the contralateral eye's pathway was inconsistent. Optical imaging also showed profound effects of deprivation, particularly in the ipsilateral pathway, and microelectrode studies confirmed continued functional plasticity past P40. Reconstruction of single afferents showed that MD from P20 to P40 promoted the growth of the open eye's geniculocortical connections without causing the closed eye's contralateral projection to shrink, whereas MD from P20 to P60 caused an arrest of growth of deprived arbors. Our findings reveal numerous similarities between mouse and higher mammals in development and plasticity, along with some differences. We discuss the factors that may be responsible for these differences.

Afferent Pathways↗
PubMedDate not supplied

Health issues in plastics production and processing.

Plastic components are essential in countless applications. Plastics can be molded into virtually any shape or size and also formed into sheets, coatings, or laminates. Plastic materials may have equal strength, durability, and impact resistance as metals, yet they are often much lighter, a distinct advantage in the automobile industry. With different combinations of polymers and additives, the production of materials with unique properties and applications is seemingly limitless. Given the size and diversity of plastics-related employment, occupational health professionals are likely to be involved in assessing health issues related to plastic manufacturing and processing. As industrial and medical experience with these compounds has grown, so has the recognition of a variety of potential health hazards. Health professionals need to be familiar with the different sectors of this industry and the diverse materials and processes.

Humans↗
PubMed1999

Phthalic acid is the main metabolite of the plasticizer di(2-ethylhexyl) phthalate in peritoneal dialysis patients.

Di(2-ethylhexyl) phthalate (DEHP) is the most commonly used plasticizer in polyvinyl chloride (PVC) plastics, and is therefore a major constituent of continuous ambulatory peritoneal dialysis (CAPD) bags. Because DEHP is not chemically bound, it leaches out of the plastic matrix. Recently, we found that leukocyte function in vitro is impaired by a mixture of metabolites of DEHP. In the present study, we investigated the metabolism of DEHP in patients on CAPD. The study group consisted of 10 stable patients, on CAPD for at least 6 months, using a plasticizer-containing PVC PD system [ANDY Plus (Fresenius Medical Care, Bad Homburg, Germany)]. Effluent dialysate and urine samples were collected over 24 hours, and a 10 mL blood sample was drawn. Concentrations of DEHP and its metabolites mono(2-ethylhexyl) phthalate (MEHP), phthalic acid (PA), and 2-ethylhexanol (2-EH) were determined in urine, dialysate, and serum using gas chromatography/mass spectrometry. Additionally, the degree of glucuronidation of the phthalic acid esters in urine were determined. In serum, dialysate, and urine, PA was the predominant metabolite of DEHP (0.205 +/- 0.067 mg/L, 0.284 +/- 0.180 mg/L, and 1.34 +/- 1.00 mg/L, respectively), but concentrations of MEHP were low (0.0100 +/- 0.0056 mg/L, 0.022 +/- 0.008 mg/L, 0.011 +/- 0.0064 mg/L, respectively). Urinary MEHP was glucuronidated to approximately 15%. PA was 35% eliminated as a glucuronide. Unlike healthy subjects, PD patients do not eliminate DEHP mainly in the form of MEHP or MEHP metabolites. They further break these compounds down to PA. The fact that concentrations of PA in urine exceed by far the respective serum concentrations indicates that PA is secreted by the kidney. Further research on the toxicological aspects of plasticizers in uremic patients should take these findings into account.

Chromatography, Gas↗
PubMed2000

[Fifty years of plastic surgery in the Netherlands. II. Introduction].

Plastic surgery is a medical specialism that was born out of was surgery. The first famous Dutch plastic surgeon, Esser, operated in Austria and Hungary during World War I. Koch, trained in England during World War II, and companions founded the Dutch Society for Plastic Surgery on October 7th 1950. During the last 50 years plastic surgery has changed into a very divers specialism, which focuses on craniofacial, esthetic, and reconstructive surgery, micro- and hand surgery, trans-sexuality and surgery of congenital abnormalities, especially of the face and hands. Each plastic operation aims at improvement of form and/or function. There have been many developments in all the fields of interest; these will be highlighted in a short series of articles.

History, 20th Century↗