Biomedical subjects

C R Lee

Publications and source records attributed to C R Lee.

At least 19 recordsLinked to original sources

PubMed2004

Pallidal control of substantia nigra dopaminergic neuron firing pattern and its relation to extracellular neostriatal dopamine levels.

The firing patterns of dopaminergic neurons in vivo are strongly modulated by afferent input. The principal GABAergic inputs to the dopaminergic neurons of the substantia nigra originate from neurons of the neostriatum, globus pallidus and substantia nigra pars reticulata. It has previously been shown that the firing pattern of nigral dopaminergic neurons can be manipulated by pharmacologically induced excitation or inhibition of the globus pallidus with relatively little effect on firing rate. We used this technique to explore the relation between the firing pattern of dopaminergic neurons and extracellular dopamine levels in the neostriatum in vivo. Specifically, we tested whether an increase in burst firing in dopaminergic neurons produced by increased pallidal activity led to increased extracellular dopamine levels in the neostriatum. Single unit extracellular recording combined with simultaneous microdialysis was used to measure the firing rates and patterns of dopaminergic neurons and extracellular striatal dopamine levels, respectively, during bicuculline-induced excitation of the globus pallidus. Pallidal excitation resulted in a marked increase in burst firing in dopaminergic neurons along with only a slight increase in firing rate, but produced a significant elevation (approximately 45%) in neostriatal dopamine levels. These data suggest that afferent-induced burst firing in dopaminergic neurons leads to an increase in extracellular dopamine levels in the neostriatum when compared with less bursty patterns with similar overall firing rates.

Animals↗

PubMed2003

Biosynthetic response of passaged chondrocytes in a type II collagen scaffold to mechanical compression.

To investigate the potential utility of mechanical loading in articular cartilage tissue engineering, porous type II collagen scaffolds seeded with adult canine passaged chondrocytes were subjected to static and dynamic compressions of varying magnitudes (0-50% static strain) and durations (1-24 h), and at different times during culture (2-30 days postseeding). The effects of mechanical compression on the biosynthetic activity of the chondrocytes were evaluated by measuring the amount of (3)H-proline-labeled proteins and (35)S-sulfate-labeled proteoglycans that accumulated in the cell-scaffold construct and was released to the medium during the loading period. Similar to published results on loading of articular cartilage explants, static compression decreased protein and proteoglycan biosynthesis in a time- and dose-dependent manner (each p < 0.005), and selected dynamic compression protocols were able to increase rates of biosynthesis (p < 0.05). The main difference between the results seen for this tissue engineering system and cartilage explants was in the amount of newly synthesized matrix molecules that accumulated within the construct under dynamic loading, with less accumulating in the type II collagen scaffold. In summary, the general biosynthetic response of passaged chondrocytes in the porous type II collagen scaffolds is similar to that seen for chondrocytes in their native environment. Future work needs to be directed to modifications of the cell-seeded construct to allow for the capture of the newly synthesized matrix molecules by the scaffold.

Animals↗

PubMed2003

Effects of a cultured autologous chondrocyte-seeded type II collagen scaffold on the healing of a chondral defect in a canine model.

Using a previously established canine model for repair of articular cartilage defects, this study evaluated the 15-week healing of chondral defects (i.e., to the tidemark) implanted with an autologous articular chondrocyte-seeded type II collagen scaffold that had been cultured in vitro for four weeks prior to implantation. The amount and composition of the reparative tissue were compared to results from our prior studies using the same animal model in which the following groups were analyzed: defects implanted with autologous chondrocyte-seeded collagen scaffolds that had been cultured in vitro for approximately 12 h prior to implantation, defects implanted with autologous chondrocytes alone, and untreated defects. Chondrocytes, isolated from articular cartilage harvested from the left knee joint of six adult canines, were expanded in number in monolayer for three weeks, seeded into porous type II collagen scaffolds, cultured for an additional four weeks in vitro and then implanted into chondral defects in the trochlear groove of the right knee joints. The percentages of specific tissue types filling the defects were evaluated histomorphometrically and certain mechanical properties of the repair tissue were determined. The reparative tissue filled 88+/-6% (mean+/-SEM; range 70-100%) of the cross-sectional area of the original defect, with hyaline cartilage accounting for 42+/-10% (range 7-67%) of defect area. These values were greater than those reported previously for untreated defects and defects implanted with a type II collagen scaffold seeded with autologous chondrocytes within 12 h prior to implantation. Most striking, was the decreased amount of fibrous tissue filling the defects in the current study, 5+/-5% (range 0-26%) as compared to previous treatments. Despite this improvement, indentation testing of the repair tissue formed in this study revealed that the compressive stiffness of the repair tissue was well below (20-fold lower stiffness) that of native articular cartilage.

Animals↗

PubMed2003

Modulation of the contractile and biosynthetic activity of chondrocytes seeded in collagen-glycosaminoglycan matrices.

Studies have demonstrated that articular chondrocytes can express the gene for alpha-smooth muscle actin (SMA) and can contract porous polymeric matrices employed for tissue engineering, thereby altering the pore structure and distorting the shape of the scaffold. The objectives of this study were to determine whether an agent known to disrupt microfilament organization in chondrocytes could reduce this contractility and to assess whether there was an association between the contractile behavior of chondrocytes and their biosynthetic activity. Staurosporine, an antibiotic known to inhibit protein kinase C and disrupt cytoskeletal structure, was used as the agent to modulate the chondrocytic phenotype and contractile and biosynthetic activity of serially passaged adult canine chondrocytes seeded in type 1 collagen-glycosaminoglycan scaffolds. Cells in monolayer culture treated with as little as 3 nM staurosporine for 4 days contained type II procollagen, whereas few cells in the untreated control cultures demonstrated type II procollagen synthesis. Treatment with staurosporine also led to a decrease in the amount of SMA synthesized by the cells. Consistent with this decreased expression of the contractile actin isoform, cells cultured in the collagen-glycosaminoglycan scaffolds and treated with 5 nM staurosporine contracted the scaffold significantly less than untreated cells (15% diameter contraction by treated cells, compared with more than 50% contraction by untreated cells). The staurosporine-treated cells were biosynthetically active, displaying higher rates of protein and glycosaminoglycan synthesis, as indicated by rates of incorporation of [(3)H]proline and [(35)S]sulfate, respectively, compared with untreated cells. The long-held notion that changes in cytoskeletal structure influence phenotypic characteristics of cultured chondrocytes may now be extended to relate expression of a specific muscle actin isoform to certain cell processes. Moreover, the finding that chondrocytes with a lower level of expression of SMA and reduced contractility display higher rates of biosynthesis warrants further study.

Actins↗

PubMed2002

Delivery of plasmid DNA to articular chondrocytes via novel collagen-glycosaminoglycan matrices.

Our primary objective was to fabricate a porous gene-supplemented collagen-glycosaminoglycan (GSCG) matrix for sustained delivery (over a period of several weeks) of plasmid DNA to articular chondrocytes when implanted into cartilage lesions. The specific aims of this in vitro study were to determine the release kinetics profiles of plasmid DNA from the GSCG matrices, and to determine the ability of the released plasmid DNA to transfect adult canine articular chondrocytes. In particular, we evaluated the effects of two variables, cross-linking treatment and the pH at which the DNA was incorporated into the matrices, on the amount of the plasmid DNA that remained bound to the GSCG matrices after passive (nonenzymatic) leaching and on the expression of a reporter gene in articular chondrocytes grown in the GSCG matrices. Collagen-glycosaminoglycan matrices were synthesized without cross-linking, and by three cross-linking treatments: dehydrothermal (DHT) treatment, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) treatment, and exposure to ultraviolet (UV) radiation. The plasmid DNA was incorporated into the collagen-glycosaminoglycan matrices in solutions at pH 2.5 or 7.5. Transmission electron microscopy studies revealed plasmid DNA bound to the walls of the porous GSCG matrices. In general, the GSCG matrices fabricated at pH 2.5 retained a larger fraction of the initial DNA load after 28 days of incubation in Tris-EDTA buffer. The passive, solvent-mediated release of the plasmid DNA from the GSCG matrices showed a biphasic pattern consisting of a faster, early release rate over the initial 8 hr of leaching followed by a slower, late release rate that was relatively constant over the subsequent 28 days of leaching. Electrophoretic analyses revealed that the plasmid DNA released from the GSCG matrices fabricated at pH 2.5 had been linearized and/or degraded; whereas the plasmid DNA leached from the GSCG matrices prepared with a DNA solution at pH 7.5 was primarily supercoiled and linear. Plasmid DNA released from all GSCG matrix formulations was able to generate luciferase reporter gene expression in monolayer-cultured chondrocytes transfected with the aid of a commercial lipid reagent, and in chondrocytes cultured in the GSCG matrices without the aid of a supplemental transfection reagent. Luciferase expression in chondrocyte-seeded GSCG constructs was evident throughout the culture period (28 days), with the EDC and UV cross-linked matrices prepared at pH 7.5 providing the highest transgene expression levels. We conclude that released plasmid DNA continually transfected canine articular chondrocytes seeded into GSCG matrices in vitro for a 4-week period as evidenced by luciferase reporter gene expression. Thus, GSCG matrices can be fabricated to provide sustained release of plasmid DNA carrying a potential therapeutic gene.

Animals↗

PubMed2002

Dopamine transporter density is decreased in parkinsonian patients with a history of manganese exposure: what does it mean?

Manganese (Mn) exposure can cause parkinsonism. Pathological changes occur mostly in the pallidum and striatum. Two patients with a long history of occupational Mn exposure presented with Mn-induced parkinsonism. In one patient, magnetic resonance imaging (MRI) showed findings consistent with Mn exposure, and Mn concentration was increased in the blood and urine. However, this patient's clinical features were typical of idiopathic Parkinson disease (PD). Previous pathological and positron emission tomography studies indicate that striatal dopamine transporter density is normal in Mn-induced parkinsonism, whereas it is decreased in PD. Therefore, we performed [(123)I]-(1r)-2 beta-carboxymethoxy-3beta-(4-iodophenyl)tropane ([(123)I]-beta-CIT) single-photon emission computed tomography. Severe reduction of striatal beta-CIT binding was indicated, which is consistent with PD. We propose three interpretations: (1) the patients have PD, and Mn exposure is incidental; (2) Mn induces selective degeneration of presynaptic dopaminergic nerve terminals, thereby causing parkinsonism; or (3) Mn exposure acts as a risk of PD in these patients. Our results and careful review of previous studies indicate that the axiom that Mn causes parkinsonism by pallidal lesion may be over-simplified; Mn exposure and parkinsonism may be more complex than previously thought. Further studies are required to elucidate the relationship between Mn and various forms of parkinsonism.

Causality↗

PubMed2001

The effects of cross-linking of collagen-glycosaminoglycan scaffolds on compressive stiffness, chondrocyte-mediated contraction, proliferation and biosynthesis.

The healing of articular cartilage defects may be improved by the use of implantable three-dimensional matrices. The present study investigated the effects of four cross-linking methods on the compressive stiffness of collagen-glycosaminoglycan (CG) matrices and the interaction between adult canine articular chondrocytes and the matrix: dehydrothermal treatment (DHT), ultraviolet irradiation (UV), glutaraldehyde treatment (GTA), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC). The degree and kinetics of chondrocyte-mediated contraction, chondrocyte proliferation, and protein and glycosaminoglycan synthesis were evaluated over a four-week period in vitro. Cell-mediated contraction of the matrices varied with cross-linking: the most compliant DHT and UV matrices contracted the most (60% reduction in matrix diameter) and stiffest EDAC matrices contracted the least (30% reduction in matrix diameter). All cross-linking protocols permitted cell proliferation and matrix synthesis as measured by DNA content and radiolabeled sulfate and proline incorporation, respectively. During the first week in culture, a lower level of proliferation was seen in the GTA matrices but over the four-week culture period, the GTA and EDAC matrices provided for the greatest cell proliferation. On day 2, there was a significantly lower rate of 3H-proline incorporation in the GTA matrices (p<0.003) although at later time points, the EDAC and GTA matrices exhibited the highest levels of matrix synthesis. With regard to cartilage-specific matrix molecule synthesis, immunohistochemistry revealed a greater amount of type II collagen in DHT and UV matrices at the early time points. These findings serve as a foundation for future studies of tissue engineering of articular cartilage and the association of chondrocyte contraction and the processes of mitosis and biosynthesis.

Animals↗

PubMed2001

Colonoscopic findings in intestinal Behçet's disease.

The aims of this study were to investigate the clinical and colonoscopic characteristics of patients with intestinal Behçet's disease and to compare the findings of typical and atypical intestinal Behçet's disease. Ninety-four patients diagnosed as having intestinal Behçet's disease were included. Of these, we considered 42 patients as having complete or incomplete type; these fulfilled the international criteria as "typical," and the other 52 patients were classified as having "atypical" intestinal Behçet's disease. Abdominal pain was the most common symptom (92%), followed by diarrhea and gastrointestinal bleeding. All of the 22 patients with a history of surgery had ulcers at the anastomotic site. Most of the patients, who had never been operated on, had lesions in the ileocecal area (96%). Sixty-three patients (67%) had a single ulcer. Many (76%) of the ulcers were larger than 1 cm, and the mean size of the ulcers was 2.9 cm. Most (99%) of the ulcers were round/oval or geographic in shape. Usually ulcers were deep (62%), and their margins discrete (80%). There was no difference in the endoscopic findings of typical and atypical intestinal Behçet's disease. Typical colonoscopic findings in intestinal Behçet's disease were single or a few deep ulcers with discrete margins in the ileocecal area or anastomotic site. Endoscopic characteristics of patients with intestinal involvement in the case of "suspect" or "possible" type of Behçet's disease that lack the systemic manifestations of Behçet's disease were in accord with those in "complete" or "incomplete" types of Behçet's disease, who fulfill the International Study Group for Behçet's Disease criteria.

Adolescent↗

PubMed2001

Difficulties in anticoagulation management during coadministration of warfarin and rifampin.

The clinical significance of rifampin's induction of warfarin metabolism is well documented, but no published studies or case reports have quantified this interaction with respect to the international normalized ratio (INR). A patient receiving concomitant rifampin and warfarin to treat a mycobacterial infection and intraventricular thrombus, respectively, underwent routine INR testing at a pharmacist-managed anticoagulation clinic to assess his anticoagulation regimen. A 233% increase in warfarin dosage over 4 months proved insufficient to attain a therapeutic INR during long-term rifampin therapy More aggressive titration of the warfarin dosage was needed. In addition, a gradual 70% reduction in warfarin dosage over 4-5 weeks was necessary to maintain a therapeutic INR after rifampin discontinuation, demonstrating the clinically significant offset of this drug interaction. Extensive changes in warfarin dosage are required to attain and maintain a therapeutic INR during the initiation, maintenance, and discontinuation of rifampin.

Antibiotics, Antitubercular↗

PubMed2000

Artefact formation in the determination of residual solvents according to a method of the European Pharmacopeia.

Method 2 of the procedure for the identification and assay of residual solvents, of the European Pharmacopeia 3rd edition 1999 addendum, leads to artefactual formation of N-chlorodimethylamine when the hydrochlorides of basic compounds are examined. This is due to degradation of the dissolution solvent N,N-dimethylformamide under the prescribed conditions. N-Chlorodimethylamine has been detected during analysis of several hydrochloride salts of nitrogen bases including drug substances. Artefact formation did not occur consistently with all the compounds examined, but with diltiazem hydrochloride it was observed in the majority of experiments. The discovery that the alkylating reagent N,N-dimethylaminoethyl chloride (DMC) used in the synthesis of diltiazem gives apparently high yields of N-chlorodimethylamine was cause for concern. However, it has been confirmed that production batches of diltiazem hydrochloride contain <1 ppm of this synthetic intermediate. The formation of N-chlorodimethylamine in the presence of the drug substance is probably due to a reaction between dimethylformamide and HCl, that would be released as a result of hydrolysis by residual water of the O-acetyl function of diltiazem. In view of these findings, the compendial general method should be reviewed. It may be necessary to adopt a different approach to the drafting of methods for volatile impurities, since most of the operating conditions are in practice specific to the substance being examined.

Calcium Channel Blockers↗

PubMed2000

Effects of harvest and selected cartilage repair procedures on the physical and biochemical properties of articular cartilage in the canine knee.

This study utilizes a canine model to quantify changes in articular cartilage 15-18 weeks after a knee joint is subjected to surgical treatment of isolated chondral defects. Clinical and experimental treatment of articular cartilage defects may include implantation of matrix materials or cells, or both. Three cartilage repair methods were evaluated: microfracture, microfracture and implantation of a type-II collagen matrix, and implantation of an autologous chondrocyte-seeded collagen matrix. The properties of articular cartilage in other knee joints subjected to harvest of articular cartilage from the trochlear ridge (to obtain cells for the cell-seeded procedure) were also evaluated. Physical properties (thickness, equilibrium compressive modulus, dynamic compressive stiffness, and streaming potential) and biochemical composition (hydration, glycosaminoglycan content, and DNA content) of the cartilage from sites distant to the surgical treatment were compared with values measured for site-matched controls in untreated knee joints. No significant differences were seen in joints subjected to any of the three cartilage repair procedures. However, a number of changes were induced by the harvest operation. The largest changes (displaying up to 3-fold increases) were seen in dynamic stiffness and streaming potential of patellar groove cartilage from joints subjected to the harvest procedure. Whether the changes reported will lead to osteoarthritic degeneration is unknown, but this study provides evidence that the harvest procedure associated with autologous cell transplantation for treatment of chondral defects may result in changes in the articular cartilage in the joint.

Animals↗

PubMed2000

Determination of N,N-dimethylaminoethyl chloride and the dimethylaziridinium ion at sub-ppm levels in diltiazem hydrochloride by LC-MS with electrospray ionisation.

An LC-MS method is described for the determination of the synthetic reagent N,N-dimethylaminoethyl chloride (DMC) in the drug substance diltiazem hydrochloride, for which the permissible limit is not more than 1 ppm (microgram g-1). The N,N-dimethylaziridinium ion (DMA), the reactive intermediate formed by cyclisation of DMC, is also detected. A column switching arrangement is used: diltiazem hydrochloride is trapped on a reversed-phase HPLC column, and the polar analytes are separated by ion exchange chromatography. Ionisation is effected by positive-ion electrospray, and the quadrupole filter mass spectrometer is operated in the selected ion recording mode. The detection limit (peak height-to-baseline noise ratio = 3) for DMC varies from day to day in the range < 0.05 to 0.1 ppm. The response for DMC is linear (r > 0.999) over the concentration range 0.2-10 ppm, and the repeatability is better than 7% (relative standard deviation) at 1.0 ppm. Concentrations of DMC in diltiazem hydrochloride from the manufacturing facility under study ranged from undetectable to about 0.07 ppm. An indirect TLC method has been published for the determination of DMC in mepyramine maleate, but it lacks the necessary sensitivity and specificity. The LC-MS method presented is direct, straightforward and suitable for routine use.

Alkylating Agents↗

PubMed2000

Articular cartilage chondrocytes in type I and type II collagen-GAG matrices exhibit contractile behavior in vitro.

Natural healing of articular cartilage defects generally does not occur, and untreated lesions may predispose the joint to osteoarthritis. To promote healing of cartilage defects, many researchers are turning toward a tissue engineering approach involving cultured cells and/or porous, resorbable matrices. This study investigated the contractile behavior of cultured canine chondrocytes seeded in a porous collagen-glycosaminoglycan (GAG) scaffold. Chondrocytes isolated from the knee joints of adult canines and expanded in monolayer culture were seeded into porous collagen-GAG scaffolds. Scaffolds were of two different compositions, with the predominant collagen being either type I or type II collagen, and of varying pore diameters. Over the 4-week culture period, the seeded cells contracted all of the type I and type II collagen-based matrices, despite a wide range of stiffness (145 +/- 23 Pa, for the type I scaffold, to 732 +/- 35 Pa, for the type II material). Pore diameter (25-85 microm, type I; and 53-257 microm, type II) did not affect cell-mediated contraction. Immunohistochemical staining revealed the presence of alpha-smooth muscle actin, an isoform responsible for contraction of smooth muscle cells and myofibroblasts, in the cytoplasm of the seeded cells and in chondrocytes in normal adult canine articular cartilage.

Animals↗

PubMed2000

Mechanisms involved in the antiplatelet activity of Staphylococcus aureus lipoteichoic acid in human platelets.

In this study, gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose-dependently (0.1-1.0 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists. LTA also dose-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. LTA (0.5 and 1.0 microg/ml) also significantly inhibited thromboxane A2 formation stimulated by collagen in human platelets. Moreover, LTA (0.1-1.0 microg/ml) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatrience. Rapid phosphorylation of a platelet protein of Mr. 47,000 (P47), a marker of protein kinase C activation, was triggered by PDBu (30 nM). This phosphorylation was markedly inhibited by LTA (0.5 and 1.0 microg/ml) within a 10-min incubation period. These results indicate that the antiplatelet activity of LTA may be involved in the following pathways: LTA's effects may initially be due to induction of conformational changes in the platelet membrane, leading to a change in the activity of phospholipase C, and subsequent inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca+2 mobilization and phosphorylation of P47 protein. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in gram-positive septicemic and endotoxemic patients.

Calcium Signaling↗

PubMed1999

Comparison of the relative activities of alpha-tocopherol and PMC on platelet aggregation and antioxidative activity.

In this study, PMC (2,2,5,7,8-pentamethyl-6-hydroxychromane), a potent antioxidant derived from alpha-tocopherol, dose-dependently inhibited agonist-induced platelet aggregation in human platelet-rich plasma. PMC is over 5-10 times more potent than alpha-tocopherol in inhibiting human platelet aggregation. Moreover, PMC (25-350 microM) dose-dependently reduced the relative fluorescence intensity of platelet membrane tagged with diphenylhexatriene (DPH). PMC is about 6-times more potent than alpha-tocopherol on this effect. Furthermore, antioxidative activity of PMC was investigated using two in vitro models. PMC inhibited non-enzymatic iron-induced lipid peroxidation in rat brain homogenates with an IC50 value of 0.21+/-0.05 microM. It was more potent than alpha-tocopherol or other classical antioxidants. PMC also scavenged the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The concentration of PMC resulting in a decrease of 0.20 in the absorbance of DPPH was about 12.1+/-3.6 microM, was comparable in potency to alpha-tocopherol, butylated hydroxytoluence and Trolox. The antiplatelet activity of PMC may possibly be due initially to an increase in fluidity of the platelet membrane followed by inhibition of platelet aggregation. Our results indicate that PMC is a potentially effective antioxidant and antiaggregating agent, and could be helpful the design of compounds with more clinical effectiveness.

Animals↗

PubMed1999

The antiplatelet activity of PMC, a potent alpha-tocopherol analogue, is mediated through inhibition of cyclo-oxygenase.

PMC, a potent alpha-tocopherol derivative, dose-dependently (5-25 microM) inhibited the ATP-release reaction and platelet aggregation in washed human platelets stimulated by agonists (collagen and ADP). PMC also dose-dependently inhibited the intracellular Ca2+ mobilization, whereas it did not inhibit phosphoinositide breakdown in human platelets stimulated by collagen. PMC (10 and 25 microM) significantly inhibited collagen-stimulated thromboxane A2 (TxA2) formation in human platelets. On the other hand, PMC (25 and 100 microM) did not increase the formation of cyclic AMP or cyclic GMP in platelets. Moreover, PMC (25, 100, and 200 microM) did not affect the thromboxane synthetase activity of aspirin-treated platelet microsomes. PMC (10 and 25 microM) markedly inhibited the exogenous arachidonic acid (100 microM)-induced prostaglandin E2 (PGE2) formation in the presence of imidazole (600 microM) in washed human platelets, indicating that PMC inhibits cyclo-oxygenase activity. We conclude that PMC may exert its anti-platelet aggregation activity by inhibiting cyclooxygenase activity, which leads to reduced prostaglandin formation; this, in turn, is followed by a reduction of TxA2 formation, and finally inhibition of [Ca2+]i mobilization and ATP-release.

Antioxidants↗

PubMed1999

Evaluation of exposure to ethylene glycol monoethyl ether acetates and their possible haematological effects on shipyard painters.

OBJECTIVES: To evaluate exposure to mixed solvents containing ethylene glycol monoethyl ether acetate (EGEEA) in shipyard painters, to determine if EGEEA is toxic to the bone marrow. METHODS: An industrial hygiene survey was performed to identify exposure to EGEEA of two groups of shipyard painters, a low exposure group (n = 30) and a high exposure group (n = 27). Urinary ethoxyacetic acid and methyl hippuric acid as well as haemoglobin, packed cell volume, red cell indices, total and differential white blood cell counts (WBCs), and platelet count for the shipyard painters and the control subjects were measured. RESULTS: The mean (range) exposure concentration (ppm) to EGEEA in the high and low exposure groups were 3.03 (not detectable to 18.27), 1.76 (not detectable to 8.12), respectively. The concentrations of methyl hippuric acid and ethoxyacetic acid in the high exposure group were significantly higher than those in the control group. The mean WBCs in the high exposure group were significantly lower than in the control group, and a significant proportion, six (11%) of the 57 painters, were leucopenic; none of the controls were affected. CONCLUSION: The high rate of possible haematological effects among shipyard painters and a hygienic evaluation of their working environment in the present study suggests that EGEEA might be toxic to bone marrow.

Adult↗

PubMed1998

In vivo gene transfer methods in the bladder without viral vectors.

OBJECTIVE: To examine three in vivo gene transfer methods, without viral vectors, for use in bladder cancer. MATERIALS AND METHODS: Three methods were selected: (i) haemagglutinating virus of Japan (HVJ)-liposomes possessing membrane fusion activity were intraluminally injected into rat bladders; (ii) using a particle gun, rabbit bladder mucosa was bombarded with DNA-coated gold microcarriers; (iii) electrotransfection was also assessed in rabbit bladder by pulsed direct currents (0.15-0.2 A, 50 ms, repeated eight times) generated between needle electrodes after the submucosal injection of DNA solution. The beta-galactosidase gene and chloramphenicol acetyl-transferase gene were used as marker genes to detect gene transfer. RESULTS: HVJ liposomes efficiently transfected superficial layers of urothelium, with a peak of expression on day 5. The particle gun produced a heterogeneous but efficient transfection in deeper layers of the urothelium. By electrotransfection, both submucosal interstitial cells and urothelium were transfected. No major complications occurred with these three methods. CONCLUSION: HVJ-liposomes are potentially useful for treating carcinoma in situ. With further refinement, the last two methods may be suitable for adjuvant therapy in treating localized bladder tumours.

Animals↗