In vitro and in vivo therapeutics of ß-thujaplicin on LPS-induced inflammation in macrophages and septic shock in mice.

ß-thujaplicin, an active constituent from Chamaecyparis obtusa, has been shown to have acaricidal and antimicrobial effects. Very few studies have focused on the potential of the anti-inflammatory effect of ß-thujaplicin. Moreover, its capability of inhibiting inflammatory mediators e.g. TNF-a gene transcription, nitric oxide (NO) and prostaglandin E2, remains unknown. Besides those molecular mechanisms behind the anti-inflammatory effect of ß-thujaplicin, solid proof of its effectiveness in vivo has not yet been studied. In our study, in vitro effects of ß thujaplicin were verified on RAW 264.7 macrophages which were stimulated by LPS. Indomethacin was used as a positive control. The inducible NO production after stimulation was measured by Griess reagent. PGE2, IL-6 and TNF-α were measured by ELISA methods. Protein expressions of iNOS, COX2, and NF-κB were evaluated by Western blotting. Septic ICR mice were administered 20 mg/kg of LPS and then the mortality rate was monitored. Within the concentration range which was devoid of cytotoxicty, ß-thujaplicin exhibited a clear dose-dependent inhibition on LPS-induced NO production. Furthermore, ß-thujaplicin inhibited LPS-induced PGE2, IL-6, and TNF-α production as well as iNOS, COX2, and NF- κB protein expression more substantially potent than indomethacin. In agreement with the in vitro study, ß-thujaplicin was shown to be effective in vivo for inhibiting LPS-induced NO and TNF-α production and a significant decrease in mortality rate of mice suffering from septic shock was observed. This study demonstrates the potential of ß-thujaplicin in treatment of inflammation and sepsis. These effects occur through an efficient blockage of TNF-α and iNOS production. ß-thujaplicin efficacy is comparable to that of indomethacin thus it can be a substitution but bear less depletion of PGE2, making this compound very promising in clinical applications. ß-thujaplicin, an active constituent from Chamaecyparis obtusa, has been shown to have acaricidal and antimicrobial effects. Very few studies have focused on the potential of the anti-inflammatory effect of ß-thujaplicin. Moreover, its capability of inhibiting inflammatory mediators e.g. TNF-alpha gene transcription, nitric oxide (NO) and prostaglandin E2, remains unknown. Besides those molecular mechanisms behind the anti-inflammatory effect of ß-thujaplicin, solid proof of its effectiveness in vivo has not yet been studied. In our study, in vitro effects of ß-thujaplicin were verified on RAW 264.7 macrophages which were stimulated by LPS. Indomethacin was used as a positive control. The inducible NO production after stimulation was measured by Griess reagent. PGE2, IL-6 and TNF-alpha were measured by ELISA methods. Protein expressions of iNOS, COX2, and NF-kB were evaluated by Western blotting. Septic ICR mice were administered 20 mg/kg of LPS and then the mortality rate was monitored. Within the concentration range which was devoid of cytotoxicty, ß-thujaplicin exhibited a clear dose-dependent inhibition on LPS-induced NO production. Furthermore, ß-thujaplicin inhibited LPS-induced PGE2, IL-6, and TNF-alpha production as well as iNOS, COX2, and NF-kB protein expression more substantially potent than indomethacin. In agreement with the in vitro study, ß-thujaplicin was shown to be effective in vivo for inhibiting LPS-induced NO and TNF-alpha production and a significant decrease in mortality rate of mice suffering from septic shock was observed. This study demonstrates the potential of ß-thujaplicin in treatment of inflammation and sepsis. These effects occur through an efficient blockage of TNF-alpha and iNOS production. ß-thujaplicin efficacy is comparable to that of indomethacin thus it can be a substitution but bear less depletion of PGE2, making this compound very promising in clinical applications.

Blending of polyethylenimine with a cationic polyurethane greatly enhances both DNA delivery efficacy and reduces the overall cytotoxicity.

Three blending methods were introduced to combine a biodegradable cationic- polyurethane (PUg3) and polyethylenimine (PEI) together with DNA by different mixing sequences. Results of gel electrophoresis assays and particle size measurements show that complexes prepared by method 1 and 3 bear an ability to condense DNA into small nanoparticles. On the contrary, the use of method 2 in making complexes produces significantly large particles because of the weaker interaction with DNA and lack of DNA condensation. Moreover, cell proliferation assays show that no cytotoxicity of the DNA/blended-polymers complexes (exhibited by method 1) was found and due to a result of the outer coating of PUg3, reducing cytotoxic PEI exposure outside the complexes. With a new technique in pharmaceutics, the complexes prepared for DNA delivery by mixing of PEI and PUg3 with DNA in a sequence (method 1) could achieve an even better transfection efficiency (reaching 40% higher) than using PEI alone as well as reduce the cytotoxicity substantially. In conclusion, a new class of complexes (non-viral combo-system) made by a skillful blending sequence (method 1) has been designed and demonstrated to obtain the beneficial properties from two useful and individual polymers for gene delivery. This method can be used in greatly improving the transfection efficiency of polymer-based gene vectors. The blended polymers with DNA also have a better biocompatibility and no cytotoxicity, which are the requirements and critical points for great success in performing gene therapy in vivo.

Beneficial effects of Chlorella-11 peptide on blocking LPS-induced macrophage activation and alleviating thermal injury-induced inflammation in rats.

Chlorella possesses various remarkable biological activities. One component, Val-Glu-Cys-Tyr-Gly-Pro-Asn-Arg-Pro-Gln-Phe (Chlorella-11 peptide) was found to be able to suppress LPS-induced NO production and inflammation. However, the molecular mechanism behind these findings and the consistency between in vitro and in vivo data have not been investigated. LPS-activated RAW 264.7 macrophages were used to study in vitro molecular anti-inflammatory effects of Chlorella-11 peptide. After activation, NO production and the expression of iNOS and NF-kappaB proteins as well as iNOS mRNA were measured using Griess colorimetric assay, Western blotting and RT-PCR, respectively. Alterations in PGE2 and TNF-alpha contents were also monitored by ELISA. For in vivo studies, thermal injury Wistar rats were used and inflammatory indications e.g. serum malondialdehyde (MDA), TNF-alpha levels and skin erythema were evaluated 48 h after injury implementation. In vitro results showed that Chlorella-11 peptide produced a dose- and time-dependent inhibition on NO production. The effective inhibition could remain for at least 6 h after LPS activation. It was also found that the expression of LPS-induced iNOS mRNA, iNOS and NF-kappaB proteins were diminished by the peptide treatment. Concurrently, the levels on TNF-alpha and PGE2 production after LPS activation were also inhibited. These findings are in agreement with the in vivo data that animal serum MDA and TNF-alpha levels and skin erythema in rats were considerably reduced compared to the control group (saline-treated). The significance of this study sheds light on the effectiveness of Chlorella-11 peptide in preventing inflammation progression in vitro and in vivo and its potential for clinical applications.

Study of undifferentiated spondyloarthropathy among first-degree relatives of ankylosing spondylitis probands.

OBJECTIVE: To estimate in a Chinese population the prevalence of undifferentiated spondyloarthropathy (USpA) among first-degree relatives (FDRs) of ankylosing spondylitis (AS) probands, and to compare the clinical features of familial USpA with those of sporadic USpA. METHODS: The FDRs of two separate cohorts of consecutive AS probands were evaluated for the prevalence of USpA, using the Modified New York criteria and the European Spondylitis Study Group criteria for AS and SpA, respectively. Sporadic USpA and FDRs of non-SpA rheumatic patient probands served as separate controls. RESULTS: Among the 301 FDRs of 102 AS probands, 7.0% were USpA. This was 1000 times higher than the 147 FDRs of 40 non-SpA probands (P = 0.00230). Within the AS families, USpA was less male-dominated than AS (33.3 vs 72.5%) (P = 0.006). The only feature distinguishing familial from sporadic USpA was that the percentages of HLA B27 were 100 and 50%, respectively (P<0.001). CONCLUSION: USpA and AS coexist in the same Chinese families, both being predisposed by HLA B27. In these families, a female gender favours the development of USpA rather than AS. A significant subset of sporadic USpA (HLA B27-negative group) has a different genetic predisposition compared with familial USpA.

Polymorphism of HLA-B27 in Taiwanese Chinese.

Heterogeneity of HLA-B27 is represented by a family of 24 closely related alleles/subtypes. Frequency and disease association of these alleles with spondyloarthropathies differ among ethnic groups. Accurate investigation of frequencies of alleles is often hindered by the size and demographic region of sample tested. With an ever-increasing number of B27 alleles being discovered, it is becoming imperative to establish disease association of each individual alleles and its biological importance. In a large number of normal healthy Taiwanese Chinese individuals (75,777) tested nationally, over a period of five years, in a single immunogenetics centre, we found additional B27 subtypes not revealed in a previous Taiwanese Chinese population study. The subtypes found in Taiwanese Chinese and the frequencies of each of the subtypes are reported.

Serological identification of a non-HLA antigen in Oriental populations.

In a routine HLA antibody screening cross-match test using the complement-mediated lymphocytotoxicity (LCT) assay, we discovered an antibody, in a transfused Caucasian woman, recognizing an Oriental restricted antigen that does not appear to be associated with the human leukocyte antigen (HLA) system. The distribution of this 'novel' antigen in Oriental populations and its frequency in the Taiwanese Chinese population are reported.

Effect of PSC 833 liposomes and Intralipid on the transport of epirubicin in Caco-2 cells and rat intestines.

Clinical applications of first-generation multidrug resistance (MDR) modulators, such as cyclosporin A (CsA) have been hampered because of their severe side effects in vivo. Recent investigations have led to the development of a more potent and less toxic modulator, PSC 833, which is a nonimmunosuppressive analogue of CsA. However, adverse pharmacokinetic interactions between anticancer drugs and PSC 833 have resulted in increased toxicity as compared to the individual toxicity. Our study evaluated the MDR reversing effect of PSC 833 in free, liposomal or Intralipid formulations on the uptake and transport of epirubicin in Caco-2 cells and everted gut sacs of rats. The results showed that PSC 833 in free or liposomal formulations significantly enhanced the intracellular accumulation of epirubicin in a dose-related manner in Caco-2 cells. The optimum in enhancement was observed at the concentration of 2 microM PSC 833. These formulations markedly increased the apical to basolateral absorption of epirubicin in Caco-2 cells and substantially improved the mucosal to serosal absorption of epirubicin in rat jejunum and ileum. PSC 833 in free, liposomal or Intralipid formulations all significantly reduced basolateral to apical efflux of epirubicin across Caco-2 monolayers. However, PSC 833 in liposomes showed greater enhancement than other formulations. In conclusion, PSC 833 and PSC 833 liposomes have the function as MDR reversing agents for the inhibition of intestinal P-glycoprotein. Liposomal preparations of PSC833 may provide a useful alternative dosage form for intravenous administration of PSC 833 to be combined with anticancer drugs to circumvent drug resistance in cancer chemotherapy.

Reversal of multidrug resistance to epirubicin by cyclosporin A in liposomes or intralipid.

Clinical applications of the first-generation multidrug resistance (MDR) modulators, such as cyclosporin A (CsA) have been hampered because of their severe side effects in vivo. In this study, we utilized liposomes and Intralipid to provide selective delivery of CsA to tumor cells as well as to circumvent toxicities associated with CsA by altering the pharmacodistribution properties of encapsulated CsA. The MDR reversing effect of CsA in free, liposomal or Intralipid formulations on the uptake and transport of epirubicin in Caco-2 cells and rat intestines was evaluated. The results showed that CsA in free or liposomal formulations significantly enhanced the intracellular accumulation of epirubicin in a dose-related fashion in Caco-2 cells, with the highest enhancement at 2 microM: These formulations substantially ameliorated the apical to basolateral absorption of epirubicin in Caco-2 cells and markedly increased mucosal to serosal absorption of epirubicin in rat jejunum and ileum. CsA in free, liposomal or Intralipid formulations all significantly reduced basolateral to apical efflux of epirubicin across Caco-2 monolayers. CsA encapsulated in liposomes showed greater enhancement than other formulations. In conclusion, liposomal preparations of CsA may circumvent MDR and have the advantage of diminishing side effects, thus providing a useful alternative dosage form for intravenous administration of CsA to be combined with cytotoxic agents for the treatment of resistant tumors.

Syntheses of chromium pentacarbonyl derivatives of arsenic(V) and antimony(V). contrasting chemical reactivity with organic halogen derivatives.

We have synthesized a new series of chromium-group 15 dihydride and hydride complexes [H(2)As(Cr(CO)(5))(2)](-) (1) and [HE(Cr(CO)(5))(3)](2)(-) (E = As, 2a; E = Sb, 2b), which represent the first examples of group 6 complexes containing E-H fragments. The contrasting chemical reactivity of 2a and 2b with organic halogen derivatives is demonstrated. The reaction of 2a with RBr (R = PhCH(2), HC triple bond CCH(2)) produces the RX addition products [(R)(Br)As(Cr(CO)(5))(2)](-) (R = PhCH(2), 3; R = C(3)H(3), 4), while the treatment of 2b with RX (RX = PhCH(2)Br or HC triple bond CCH(2)Br, CH(3)(CH(2))(5)C(O)Cl) forms the halo-substituted complexes [XSb(Cr(CO)(5))(3)](2-) (X = Br, 5; X = Cl, 6). Moreover, the dihaloantimony complexes [XX'Sb(Cr(CO)(5))(2)](-) can be obtained from the reaction of 2b with the appropriate organic halides. In this study, a series of organoarsenic and antimony chromium carbonyl complexes have been synthesized and structurally characterized and the role of the main group on the formation of the resultant complexes is also discussed.

Enhancement of nasal absorption of calcitonin loaded in liposomes.

Intranasal administration of calcitonin-containing liposomes in rabbits was investigated to evaluate the in vivo calcitonin absorption performance. Plasma calcitonin concentrations and calcium levels were measured and pharmacokinetic parameters were calculated. The bioavailability of calcitonin resulted from the intranasal delivery formulations demonstrated an order of calcitonin-containing positively charged liposomes > calcitonin-containing negatively charged liposomes > calcitonin solution. The significant enhancement of bioavailability of calcitonin for positively charged liposomes may be due to the charge interaction of positively charged liposomes with the negatively charged mucosa surface. Marked accumulation of positively charged liposomes was found on the negatively charged nasal mucosa surface. The retention of positively charged liposomes on the nasal mucosa resulted in an increase of residence time with high local concentration of calcitonin for increase of absorption.

Effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development.

BACKGROUND AND PURPOSE: Angiogenesis is regulated by various factors, including vascular endothelial growth factor (VEGF). Five isoforms of VEGF have been discovered: VEGF121, VEGF145, VEGF165, VEGF189, and VEGF206. The teleologic basis for the various VEGF isoforms remains unclear, but different VEGF isoforms may mediate distinct endothelial cell functions such as angiogenesis, vascular permeability, and differentiation. We sought to determine the effects of various VEGF isoforms on angiogenesis under ischemic conditions in rabbits. METHODS: The effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development in ischemic rabbit hindlimb muscles were investigated by using naked plasmids encoding VEGF121 or VEGF165 (pVEGF121 or pVEGF165), either individually or in combination. pCMV beta was used as the control plasmid. The femoral artery on one side of New Zealand White rabbits was ligated. Ten days later, the ischemic muscles received direct intramuscular injection of pVEGF121 (500 micrograms), pVEGF165 (500 micrograms), or pVEGF121 (250 micrograms) + pVEGF165 (250 micrograms) in experimental groups, while pCMV beta (500 micrograms) was used in the control group. Therapeutic effects were evaluated 30 days later by anatomic and physiologic analysis. RESULTS: Internal iliac angiography showed strong development of collateral circulation in all of the pVEGF-treated groups. In contrast, collateral arteries developed weakly in the control group. Combination treatment with both pVEGF121 and pVEGF165 did not result in additional improvement compared with pVEGF121 or pVEGF165 treatment alone (angiographic scores: pVEGF121 = 0.85 +/- 0.10; pVEGF165 = 0.81 +/- 0.11; pVEGF121 + pVEGF165 = 0.83 +/- 0.09; control = 0.53 +/- 0.09; p < 0.01). A favorable response in the development of circulation at the capillary level with pVEGF121 and/or pVEGF165 versus pCMV beta was also found. Blood pressure measurement and regional blood flow measurement using colored microspheres revealed similar results. CONCLUSIONS: Our results show that direct intramuscular injection of naked DNA encoding VEGF121 or VEGF165, individually or in combination, is an effective method for gene transfer in an animal model of ischemic limbs and results in augmented collateral vascular development and tissue perfusion.

Long term stability of poly((2-dimethylamino)ethyl methacrylate)-based gene delivery systems.

PURPOSE: To study the stability of polymer-plasmid complexes (polyplexes) both as an aqueous dispersion and in their lyophilized form. METHODS: The characteristics of the polyplexes (size, charge and transfection potential) were monitored at different temperatures. Moreover, we studied possible changes in the secondary and tertiary structure of the plasmid by agarose gel electrophoresis and by CD spectroscopy to gain insight into the mechanism of polyplex degradation. RESULTS: The polyplexes preserved almost their full transfection potential after aging in an aqueous solution of 20 mM Hepes (pH 7.4) containing 10% sucrose at 4 and 20 degrees C for 10 months. On the other hand, the polyplexes aged at 40 degrees C were rather unstable and lost their transfection capability with a half-life of around 2 months. During storage, conformational changes in the secondary and tertiary structure of DNA were observed. When naked plasmid DNA was aged at 40 degrees C as an aqueous solution and complexed with polymer just before the transfection experiment, a slower drop in its transfection capability was observed. The freeze-dried polyplexes using sucrose as lyoprotectant almost fully retained their transfection efficiency, even when aged at 40 degrees C for 10 months. CONCLUSIONS: This study provides information about polyplex stability in aqueous dispersions on storage and demonstrates that freeze-drying is an excellent method to ensure long term stability.

Effect of DNA topology on the transfection efficiency of poly((2-dimethylamino)ethyl methacrylate)-plasmid complexes.

In this paper the effect of the topology of plasmid DNA (supercoiled, open-circular and linear) on its binding characteristics with the polymeric transfectant poly((2-dimethylamino)ethyl methacrylate) was studied. The formed polyplexes were also evaluated for their transfection properties in vitro in two different cell lines. Anion-exchange chromatography was used for the separation of supercoiled and open-circular plasmid from a plasmid stock solution. Linear plasmids were prepared by endonucleases that cleaved the plasmid either in the promoter region or in a region not specific for expression (ampicillin resistance region). Plasmid DNA was also heat-denatured for 6 h at 70 degrees C, resulting in DNA mainly in the open-circular and oligomeric forms. The transfection of two different cell lines was dependent on the topology of the DNA in the order supercoiled>open-circular approximately heat-denatured>linear DNA prepared by cleaving in the nonspecific region>linear DNA prepared by cleaving in the promoter region. No differences in the size of the complexes or in the quenching of the DNA-intercalating fluorophore acridine orange were found as function of the topology. However, circular dichroism spectroscopy revealed differences between the topological plasmid species, both in the free form and in the presence of excess of cationic polymer.

The effect of formulation parameters on the size of poly-((2-dimethylamino)ethyl methacrylate)-plasmid complexes.

The aim of this study was to gain insight into the formulation parameters affecting the size of poly((2-dimethylamino)ethyl methacrylate)-plasmid complexes (polyplexes). Experimental designs were applied to screen and optimize several variables, which may influence the complex size. In a screening design, it was demonstrated that at a fixed concentration of plasmid (40 micrograms/ml) after incubation with polymer, the size of the resulting polyplexes was highly dependent on the polymer/plasmid ratio as well as on the pH, viscosity (i.e. sucrose concentration) and ionic strength of the aqueous solution. However, the temperature, PEG 600 (up to 5% (v/v)) and Tween 80 (up to 0.2%) had a marginal effect on the size of the polyplexes. In an optimization design, the effect of the pH, polymer/plasmid ratio and Tween on the size of the polymer/plasmid complexes prepared at relatively high concentration of plasmid (50-200 micrograms/ml) was evaluated. Based on the results of the optimization design, a mathematical model was derived, which describes the relationship between the size of the polyplexes and the different formulation parameters. This model shows that even at high plasmid concentration (200 micrograms/ml), small sized polyplexes were formed at low pH and ionic strength, especially when the solution contains 20% (w/v) sucrose. This concentrated polyplex dispersion (polymer/plasmid ratio > 3/1 (w/w), 200 micrograms plasmid/ml) can be diluted down to 5 micrograms/ml plasmid without significant changes in particle size and transfection potential. At lower ratios, a growth in particle size was observed upon dilution of the complexes, which might also explain the low transfection efficiency of these polyplexes in vitro.

Stabilization of polymer-based gene delivery systems.

To preserve the size and transfection potential of polymer-plasmid complexes. Freeze-drying and freeze-thawing were used for stabilization of these complexes. The concentration of the sugars is an important factor affecting both the size and transfection capability of the complexes after freeze-drying and freeze-thawing. However, the type of lyoprotectant (sugar) used is of minor importance. It is also shown that when damage to polymer-plasmid complexes occurs, it results from the drying process but is not due to the freezing step.

2-(Dimethylamino)ethyl methacrylate based (co)polymers as gene transfer agents.

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) is a water-soluble cationic polymer, which is able to bind to DNA by electrostatic interactions. At a polymer/plasmid ratio above 2 (w/w) positively charged complexes were formed with a size around 0.2 microm. The transfection efficiency of polymer/plasmid complexes was evaluated in cell culture (COS-7 and OVCAR-3 cells) using a pCMV-lacZ plasmid, encoding for beta-galactosidase, as a reporter gene. The optimal transfection efficiency was found at a PDMAEMA/plasmid ratio of 3-5 (w/w). Under these conditions 3-6% of the cells were actually transfected. Like other cationic polymers, PDMAEMA is slightly cytotoxic. This activity was partially masked by complexing the polymer with DNA. A pronounced effect of the molecular weight of the polymer on the transfection efficiency was observed. An increasing molecular weight resulted in an increasing number of transfected cells. Dynamic light scattering experiments showed that high molecular weight polymers (Mw>300 kDa) were able to condense DNA effectively (particle size 0.15-0.20 microm). In contrast, when plasmid was incubated with low molecular weight PDMAEMA, large complexes were formed (size 0.5-1.0 microm). Copolymers of DMAEMA with methyl methacrylate (MMA), ethoxytriethylene glycol methacrylate (triEGMA) or N-vinyl-pyrrolidone (NVP) also acted as transfection agents. A copolymer with 20 mol % of MMA showed a reduced transfection efficiency and a substantial increased cytotoxicity compared with a homopolymer of the same molecular weight. A copolymer with triEGMA (48 mol %) showed both a reduced transfection efficiency and a reduced cytotoxicity, whereas a copolymer with NVP (54 mol %) showed an increased transfection efficiency and a decreased cytotoxicity as compared to a DMAEMA homopolymer.

Stabilization of gene delivery systems by freeze-drying.

Freeze-drying of three different forms of gene delivery systems was performed using a controlled two-step drying process and 10% sucrose as lyoprotectant. Complexes of pCMVL plasmid with transferrin-conjugated polyethylenimine, adenovirus-enhanced transferrinfection consisting of pCMVL/transferrin-polylysine complexes linked to inactivated adenovirus particles, and a recombinant, E1-defective adenovirus expressing a luciferase reporter gene were tested. Three weeks after freeze-drying the reagents were rehydrated with water and tested for transfection activity. Luciferase gene expression levels were retained at high levels in all three systems, in contrast to reagents stored in solution. The use of the lyoprotectant was essential. In the absence of sucrose the transfection activities dropped by a factor of 100-1000. The data suggest freeze-drying as a useful method for stabilization and storage of standardized batches of transfection agents.

Effect of size and serum proteins on transfection efficiency of poly ((2-dimethylamino)ethyl methacrylate)-plasmid nanoparticles.

PURPOSE: The aim of this study was to gain insight into the relation between the physical characteristics of particles formed by a plasmid and a synthetic cationic polymer (poly(2-dimethylamino)ethyl methacrylate, PDMAEMA) and their transfection efficiency. METHODS: The PDMAEMA-plasmid particles were characterized by dynamic light scattering (size) and electrophoretic mobility measurements (charge). The transfection efficiency was evaluated in cell culture (COS-7 cells) using a pCMV-lacZ plasmid coding for beta-galactosidase as a reporter gene. RESULTS: It was shown that the optimal transfection efficiency was found at a PDMAEMA-plasmid ratio of 3 (w/w), yielding stable and rather homogeneous particles (diameter 0.15 micron) with a narrow size distribution and a slightly positive charge. Particles prepared at lower weight ratios, showed a reduced transfection efficiency and were unstable in time as demonstrated by DLS measurements. Like other cationic polymers, PDMAEMA is slightly cytotoxic. This activity was partially masked by complexing the polymer with DNA. Interestingly, the transfection efficiency of the particles was not affected by the presence of serum proteins. CONCLUSIONS: PDMAEMA is an interesting vector for the design of in vivo and ex vivo gene transfection systems.

Terminal cardiac electrical activity in adults who die without apparent cardiac disease.

Prolonged electrocardiographic (Holter) recording was performed to analyze terminal electrical events in 23 hospitalized adults who died without apparent cardiac disease. Most patients showed a gradual slowing of heart rate with shifting of cardiac pacemaker downward from the sinus node or atria to the atrioventricular junction and ventricles, resulting in cardiac asystole. Dominant bradyarrhythmia was more common than ventricular tachyarrhythmia (83 vs 17%). Agonal ST-segment elevation was not uncommon (26%). These terminal electrical events became manifest from 1 to 450 minutes (mean 62) before cessation of cardiac electrical activity. Forty-eight percent of the patients continued to show deteriorating sinus or atrial activity up to the last moment. The mechanism of bradycardiac asystole in patients with no apparent cardiac disease may be attributed to generalized anoxic and toxic depression of the sinus node and subsidiary pacemakers, together with neurogenic suppression of these structures.