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Affonso da Costa FD, Pinton R, Haggi Filho H, da Rosa GS, Abuchaim DC, Quintaneiro V, Milani R, Ito R, Gaspar R, Burger M, Sallum F, Faraco DL, Affonso da Costa IA. The Ross procedure: Is it the ideal operation for the young with aortic valve disease? Heart Surg Forum 2001; 1:116-24. [PMID: 11302116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
BACKGROUND Aortic valve prosthesis with adequate hemodynamic performance should allow more complete left ventricular mass regression and normalize left ventricular function. This possibly affects long-term prognosis after aortic valve replacement. OBJECTIVE Assessment of hemodynamic performance of pulmonary autograft in the aortic position and the regression of left ventricular mass after the Ross procedure. METHODS Between May 1995 and March 1996, 45 patients with mean age of 27.1 years underwent a Ross procedure. Doppler echocardiography and cardiac catheterization were performed on all patients before hospital discharge to evaluate the hemodynamic performance of auto- and homografts, as well as to evaluate left ventricular mass and function. Fourteen patients with follow-up longer than six months were submitted to dobutamine stress echocardiography to study the hemodynamic performance of auto- and homografts during exercise. RESULTS Hospital mortality was 6%. After a mean follow-up of 12.8 months (1-23 months) there was one late sudden death. No valve-related event was observed during this period. Immediate and late hemodynamic performance of the pulmonary autografts were normal with an average mean gradient of 1.8 +/- 0.6 mmHg and an average maximum instantaneous gradient of 2.9 +/- 0.9 mmHg. Valvular insufficiency was insignificant. Even during exercise, gradients did not increase significantly with an average mean gradient of 4.3 +/- 2.5 mmHg and an average maximum gradient of 10.4 +/- 6.1 mmHg. Homografts used for right ventricular reconstruction showed excellent immediate hemodynamic performance. However, at late follow-up an increase in flow speed was observed with an average to mean gradient of 10 +/- 7.1 mmHg at rest and 26 +/- 13.2 mmHg during exercise. Left ventricular mass index was normal at rest and during exercise in the majority of patients. CONCLUSION Given the normal hemodynamic function of pulmonary autografts, the reduction of ventricular mass and normalization of left ventricular function, in addition to the excellent late follow-up of the patients, the Ross procedure is considered the operation of choice for young patients requiring aortic valve replacement.
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Blumenfeld I, Gaspar R, Laufer D, Livne E. Enhancement of toluidine blue staining by transforming growth factor-beta, insulin-like growth factor and growth hormone in the temporomandibular joint of aged mice. Cells Tissues Organs 2000; 167:121-9. [PMID: 10971036 DOI: 10.1159/000016775] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Osteoarthritic lesions appear in the articular cartilage of the temporomandibular joint of mice aged 7 months and older. Reduced rate of proteoglycan (PG) synthesis leading to destruction of the articular cartilage was observed in this joint. The purpose of the present study was to test the ability of transforming growth factor-beta1 (TGF-beta1), insulin-like growth factor-1 (IGF-1) and growth hormone (GH) to induce PG synthesis in joint cartilage of aged animals and to compare it with the effect of interleukin-1alpha (IL-1alpha). Mandibular condyle explants from 18-month-old mice were cultured up to 72 h in serum-free medium, supplemented with IL-1alpha (TGF-beta1 (0.1-5.0 ng/ml), TGF-beta1 (1.0 ng/ml) + IGF-1 (2 ng/ml) or GH (10 ng/ml). The incorporation of (35)S-SO(4) into sulfated PG was tested. Cartilage samples were processed for histomorphometry using sections stained with 0.1% toluidine blue (TB), pH 1.8. Results indicated that in cultures supplemented (48 h) with either TGF-beta, TGF-beta + IGF-1 or with GH, an increased height and area of TB-positive staining as well as increased incorporation of (35)S-SO(4) into sulfated PG were observed. In contrast, the cytokine IL-1alpha exerted an inhibitory effect on TB staining and on (35)S-SO(4) incorporation. The present study demonstrated that in vitro supplementation of IL-1alpha to mandibular condyle cartilage reduced the height and area of TB staining and incorporation of (35)S-SO(4), whereas TGF-beta1, TGF-beta1 + IGF-1 or GH increased the height and area of TB staining and increased incorporation of (35)S-SO(4). The two parameters used to identify increased PG synthesis were shown to reveal similar results and were useful for studying the dynamic events taking place in cartilage destruction and repair in osteoarthritis.
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Gaspar R. [European drugs: Europe faces the future]. JOURNAL DE PHARMACIE DE BELGIQUE 2000; 55:69-73. [PMID: 10925546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Ardekian L, Gaspar R, Peled M, Brener B, Laufer D. Does low-dose aspirin therapy complicate oral surgical procedures? J Am Dent Assoc 2000; 131:331-5. [PMID: 10715924 DOI: 10.14219/jada.archive.2000.0176] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The fear of uncontrolled bleeding often prompts medical practitioners to stop aspirin intake for seven to 10 days before any surgical procedure. The authors initiated this study to evaluate the effect of aspirin on bleeding in patients undergoing oral surgery. METHODS The study group consisted of 39 patients who were scheduled to undergo dental extractions. All patients were receiving 100 milligrams of aspirin daily on a regular basis. The authors randomly divided the patients into two groups: those who stopped the aspirin therapy before the procedure and those who continued the aspirin therapy. One hour before the procedures, all patients underwent a bleeding time test. In addition, the amount of bleeding during the procedure was measured. RESULTS The mean (+/- standard deviation) bleeding time was 1.8 +/- 0.47 minutes for patients who stopped aspirin therapy one week before the procedure. For patients who continued aspirin therapy, the bleeding time was 3.1 +/- 0.65 minutes. The difference was statistically significant (P = .004). However, both groups were within the normal bleeding time range, and in both groups, a local hemostatic method was sufficient to control bleeding. No episodes of uncontrolled intraoperative or postoperative bleeding were noted. CONCLUSION Low-dose aspirin therapy should not be stopped before oral surgery. Local hemostasis is sufficient to control bleeding. CLINICAL IMPLICATIONS Patients receiving aspirin therapy to prevent blood clot formation may be subject to emboli formation if the treatment is stopped. The results of this study show that aspirin therapy should be continued throughout oral surgical procedures. Local measures are sufficient to control any bleeding during surgery.
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Simões S, Slepushkin V, Pires P, Gaspar R, Pedroso de Lima MC, Düzgüneş N. Human serum albumin enhances DNA transfection by lipoplexes and confers resistance to inhibition by serum. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1463:459-69. [PMID: 10675522 DOI: 10.1016/s0005-2736(99)00238-2] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cationic liposome-DNA complexes ('lipoplexes') are used as gene delivery vehicles and may overcome some of the limitations of viral vectors for gene therapy applications. The interaction of highly positively charged lipoplexes with biological macromolecules in blood and tissues is one of the drawbacks of this system. We examined whether coating cationic liposomes with human serum albumin (HSA) could generate complexes that maintained transfection activity. The association of HSA with liposomes composed of 1, 2-dioleoyl-3-(trimethylammonium) propane and dioleoylphosphatidylethanolamine, and subsequent complexation with the plasmid pCMVluc greatly increased luciferase expression in epithelial and lymphocytic cell lines above that obtained with plain lipoplexes. The percentage of cells transfected also increased by an order of magnitude. The zeta potential of the ternary complexes was lower than that of the lipoplexes. Transfection activity by HSA-lipoplexes was not inhibited by up to 30% serum. The combined use of HSA and a pH-sensitive peptide resulted in significant gene expression in human primary macrophages. HSA-lipoplexes mediated significantly higher gene expression than plain lipoplexes or naked DNA in the lungs and spleen of mice. Our results indicate that negatively charged HSA-lipoplexes can facilitate efficient transfection of cultured cells, and that they may overcome some of the problems associated with the use of highly positively charged complexes for gene delivery in vivo.
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Simões S, Slepushkin V, Gaspar R, Pedroso de Lima MC, Düzgünes N. Successful transfection of lymphocytes by ternary lipoplexes. Biosci Rep 1999; 19:601-9. [PMID: 10841276 DOI: 10.1023/a:1020275114185] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transgene expression in lymphoid cells may be useful for modulating immune responses in, and gene therapy of, cancer and AIDS. Although cationic liposome-DNA complexes (lipoplexes) present advantages over viral vectors, they have low transfection efficiency, unfavorable features for intravenous administration, and lack of target cell specificity. The use of a targeting ligand (transferrin), or an endosome-disrupting peptide, in ternary complexes with liposomes and a luciferase plasmid, significantly promoted transgene expression in several T- and B-lymphocytic cell lines. The highest levels of luciferase activity were obtained at a lipid/DNA (+/-) charge ratio of 1/1, where the ternary complexes were net negatively charged. The use of such negatively charged ternary complexes may alleviate some of the drawbacks of highly positively charged plain lipoplexes for gene delivery.
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Simões S, Slepushkin V, Pires P, Gaspar R, de Lima MP, Düzgüneş N. Mechanisms of gene transfer mediated by lipoplexes associated with targeting ligands or pH-sensitive peptides. Gene Ther 1999; 6:1798-807. [PMID: 10602375 DOI: 10.1038/sj.gt.3301015] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Association of a targeting ligand such as transferrin, or an endosome disrupting peptide such as GALA, with cationic liposome-DNA complexes ('lipoplexes') results in a significant enhancement of transfection of several cell types (Simões S et al, Gene Therapy 1998; 5: 955-964). Although these strategies can overcome some of the barriers to gene delivery by lipoplexes, the mechanisms by which they actually enhance tranfection is not known. In studies designed to establish the targeting specificity of transferrin, we found that apo-transferrin enhances transfection to the same extent as transferrin, indicating that internalization of the lipoplexes is mostly independent of transferrin receptors. These observations were reinforced by results obtained from competitive inhibition studies either by preincubating the cells with an excess of free ligand or with various 'receptor-blocking' lipoplexes. Transfection of cells in the presence of drugs that interfere with the endocytotic pathway provided additional insights into the mechanisms of gene delivery by transferrin- or GALA-lipoplexes. Our results indicate that transferrin-lipoplexes deliver transgenes by endocytosis primarily via a non-receptor-mediated mechanism, and that acidification of the endosomes is partially involved in this process.
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Wilson B, Arnold H, Bearzi G, Fortuna CM, Gaspar R, Ingram S, Liret C, Pribanić S, Read AJ, Ridoux V, Schneider K, Urian KW, Wells RS, Wood C, Thompson PM, Hammond PS. Epidermal diseases in bottlenose dolphins: impacts of natural and anthropogenic factors. Proc Biol Sci 1999; 266:1077-83. [PMID: 10380684 PMCID: PMC1689944 DOI: 10.1098/rspb.1999.0746] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Experimental studies have highlighted the potential influence of contaminants on marine mammal immune function and anthropogenic contaminants are commonly believed to influence the development of diseases observed in the wild. However, estimates of the impact of contaminants on wild populations are constrained by uncertainty over natural variation in disease patterns under different environmental conditions. We used photographic techniques to compare levels of epidermal disease in ten coastal populations of bottlenose dolphins (Tursiops truncatus) exposed to a wide range of natural and anthropogenic conditions. Epidermal lesions were common in all populations (affecting > 60% of individuals), but both the prevalence and severity of 15 lesion categories varied between populations. No relationships were found between epidermal disease and contaminant levels across the four populations for which toxicological data were available. In contrast, there were highly significant linear relationships with oceanographic variables. In particular, populations from areas of low water temperature and low salinity exhibited higher lesion prevalence and severity. Such conditions may impact on epidermal integrity or produce more general physiological stress, potentially making animals more vulnerable to natural infections or anthropogenic factors. These results show that variations in natural environmental factors must be accounted for when investigating the importance of anthropogenic impacts on disease in wild marine mammals.
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Pires P, Simões S, Nir S, Gaspar R, Düzgünes N, Pedroso de Lima MC. Interaction of cationic liposomes and their DNA complexes with monocytic leukemia cells. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1418:71-84. [PMID: 10209212 DOI: 10.1016/s0005-2736(99)00023-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cationic liposomes complexed with DNA have been used extensively as non-viral vectors for the intracellular delivery of reporter or therapeutic genes in culture and in vivo. We examined the relationship between the characteristics of the lipoplexes, their mode of interaction with monocytic THP-1 cells and their ability to transfect these cells. We determined the size and zeta potential of cationic liposomes (composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and its mixtures with neutral lipids), and lipoplexes at different (+/-) charge ratios. As the (+/-) charge ratio of the lipoplexes decreased to (1/1), a significant reduction in zeta potential and an increase in size was observed. The increase in size resulted from fusion between liposomes promoted by DNA, as demonstrated by a lipid mixing assay, and from aggregation of the complexes. Interaction of liposomes and lipoplexes with THP-1 cells was assessed by monitoring lipid mixing ('fusion') as well as binding and cell association. While no lipid mixing was observed with the 1/2 (+/-) lipid/DNA complexes, lipoplexes with higher (+/-) charge ratios underwent significant fusion in conjunction with extensive cell binding. Liposome binding to cells was dependent on the positive charge of the liposomes, and their fusion could be modulated by the co-lipid. DOTAP/phosphatidylethanolamine (1:1) liposomes fused with THP-1 cells, unlike DOTAP/phosphatidylcholine (1:1) liposomes, although both liposome types bound to the cells to a similar extent. The use of inhibitors of endocytosis indicated that fusion of the cationic liposomes with cells occurred mainly at the plasma membrane level. The presence of serum increased the size of the cationic liposomes, but not that of the lipoplexes. Low concentrations of serum (3%) completely inhibited the fusion of cationic liposomes with cells, while inhibiting binding by only 20%. Our results suggest that binding of cationic liposomes and lipoplexes to cells is governed primarily by electrostatic interactions, whereas their fusion is regulated by the lipid composition and sterically favorable interactions with cell surface molecules. In addition our results indicate no correlation between fusion of the lipoplexes with the plasma membrane and the levels of transfection.
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Simões S, Slepushkin V, Pretzer E, Dazin P, Gaspar R, Pedroso de Lima MC, Düzgüneş N. Transfection of human macrophages by lipoplexes via the combined use of transferrin and pH-sensitive peptides. J Leukoc Biol 1999; 65:270-9. [PMID: 10088611 DOI: 10.1002/jlb.65.2.270] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The crucial function of macrophages in a variety of biological processes and pathologies render these cells important targets for gene therapeutic interventions. Commonly used synthetic gene delivery vectors have not been successful in transfecting these non-dividing cells. A combination strategy involving cationic liposomes to condense and carry DNA, transferrin to facilitate cellular uptake, and the pH-sensitive peptide GALA to promote endosome destabilization, resulted in significant expression of a luciferase gene. Transfection of macrophages was dependent on the degree of differentiation of the cells. The quaternary complexes of cationic liposomes, DNA, transferrin, and GALA exhibited a net negative charge, which may obviate a limitation of cationic synthetic vectors in vivo. The lack of cytotoxicity and the expected lack of immunogenicity of these complexes may render them useful for gene delivery to macrophages in vivo.
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Gaspar R, Ardekian L, Brenner B, Peled M, Laufer D. [Ambulatory oral procedures in patients on low-dose aspirin]. HAREFUAH 1999; 136:108-10, 175. [PMID: 10914173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Discontinuation of long-term, low-dose aspirin prior to ambulatory oral surgical procedures was assessed in a blind, controlled prospective study. 50 patients on low-dose aspirin who needed dental extractions, periodontal surgery, or other ambulatory oral surgery were randomly divided into test and control groups. The control patients stopped taking aspirin a week before operation, but in the test group aspirin was continued. Before, during and after surgery bleeding time was tested. Although bleeding time was significantly longer when aspirin was continued, in both groups it was within normal limits. Intraoperative hemorrhage was more frequent in those taking aspirin. Hemostasis control posed no problem and there were no postoperative complications in either group. It is concluded that discontinuing low-dose aspirin prior to elective oral surgery is not justified.
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de Lima MC, Simões S, Pires P, Gaspar R, Slepushkin V, Düzgüneş N. Gene delivery mediated by cationic liposomes: from biophysical aspects to enhancement of transfection. Mol Membr Biol 1999; 16:103-9. [PMID: 10332744 DOI: 10.1080/096876899294823] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Cationic liposomes complexed with DNA have been used extensively as non-viral vectors for the intracellular delivery of reporter or therapeutic genes in culture and in vivo. However, the relationship between the features of the lipid-DNA complexes ('lipoplexes') and their mode of interaction with cells, the efficiency of gene transfer and gene expression remain to be clarified. To gain insights into these aspects, the size and zeta potential of cationic liposomes (composed of 1,2-dioleoyl-3- (trimethylammonium) propane (DOTAP) and its mixture with phosphatidylethanolamine (PE)), and their complexes with DNA at different (+/-) charge ratios were determined. A lipid mixing assay was used to assess the interaction of liposomes and lipoplexes with monocytic leukaemia cells. The use of inhibitors of endocytosis indicated that fusion of the cationic liposomes with cells occurred mainly at the plasma membrane level. However, very limited transfection of these cells was achieved using the above complexes. It is possible that the topology of the cationic liposome-DNA complexes does not allow the entry of DNA into cells through a fusion process at the plasma membrane. In an attempt to enhance transfection mediated by lipoplexes composed of DOTAP and its equimolar mixture with dioleoylphosphatidylethanolamine (DOPE) two different strategies were explored: (i) association of a targeting ligand (transferrin) to the complexes to promote their internalization, presumably by receptor-mediated endocytosis; and (ii) association of synthetic fusogenic peptides (GALA or the influenza haemagglutinin N-terminal peptide HA-2) to the complexes to promote endosomal destabilization and release of the genetic material into the cytoplasm. These strategies were effective in enhancing transfection in a large variety of cells, including epithelial and lymphoid cell lines, as well as human macrophages, especially with the use of optimized lipid/DNA (+/-) charge ratios. Besides leading to high levels of transfection, the ternary complexes of cationic liposomes, DNA, and protein or peptide, have the advantages of being active in the presence of serum and being non-toxic. Moreover, such ternary complexes present a net negative charge and, thus, are likely to alleviate the problems associated with the use of highly positively charged complexes in vivo, such as avid complexation with serum proteins. Overall, the results indicate that these complexes, and their future derivatives, may constitute viable alternatives to viral vectors for gene delivery in vivo.
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Gaspar R, Nagy A. X alpha method with theoretically determined parameter α- exchange parameters α and ionisation energies of multiply charged ions. ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/20/15/012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ardekian L, Manor R, Gaspar R, Laufer D. Central granular cell odontogenic tumor: case report and review of literature. J Oral Maxillofac Surg 1998; 56:1343-5. [PMID: 9820223 DOI: 10.1016/s0278-2391(98)90619-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Simões S, Slepushkin V, Gaspar R, de Lima MC, Düzgüneş N. Gene delivery by negatively charged ternary complexes of DNA, cationic liposomes and transferrin or fusigenic peptides. Gene Ther 1998; 5:955-64. [PMID: 9813667 DOI: 10.1038/sj.gt.3300674] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Potential problems with the use of viral vectors for gene therapy necessitate the development of efficient nonviral vectors. The association of transferrin, or the pH-sensitive peptide GALA, with cationic liposomes composed of 1,2-dioleoyl-3-(trimethylammonium) propane and its equimolar mixture with dioleoylphosphatidylethanolamine, under conditions where the liposome/DNA complex is negatively charged, drastically increased luciferase expression from pCMVluc. The percentage of cells transfected, measured by beta-galactosidase expression, was also increased by about 10-fold. The zeta potential of the ternary complexes was lower than that of the liposome/DNA complexes. Transfection activity of positively charged complexes was also enhanced by association with transferrin, GALA or the influenza hemagglutinin N terminal peptide HA-2, but to a smaller extent compared with the negatively charged complexes. The enhancement of gene delivery by transferrin or GALA was not affected significantly by the presence of serum and did not cause significant cytotoxicity. Our results indicate that negatively charged ternary complexes of cationic liposomes, DNA and transferrin, or fusigenic peptides, can facilitate efficient transfection of cultured cells, and that they may alleviate the drawbacks of the use of highly positively charged complexes for gene delivery in vivo.
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Gaspar R, Brenner B, Ardekian L, Peled M, Laufer D. Use of tranexamic acid mouthwash to prevent postoperative bleeding in oral surgery patients on oral anticoagulant medication. QUINTESSENCE INTERNATIONAL (BERLIN, GERMANY : 1985) 1997; 28:375-9. [PMID: 9477900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The clinical hemostatic effect of tranexamic acid mouthwash after oral surgery was evaluated in 47 patients receiving oral anticoagulant therapy. Surgery was performed after the anticoagulant medication was reduced in 15 patients (control group) and with no change in anticoagulant therapy in 32 patients (test group). The only statistical difference between the two treatment groups at baseline was the level of anticoagulation, which was significantly higher in the test group. There was no significant difference between the two treatment groups in the incidence of bleeding after oral surgery. The results indicated that a combination of local antifibrinolytic therapy and a local hemostatic agent is effective in preventing postoperative bleeding after oral surgery in patients treated with anticoagulants.
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Martins MB, Supico A, Simões SI, Gaspar R, Cruz ME. An analytical methodology to quantify the incorporation of enzymes in polyalkylcyanoacrylate nanoparticles based on size exclusion chromatography. J Pharm Biomed Anal 1997; 15:811-8. [PMID: 9172107 DOI: 10.1016/s0731-7085(96)01909-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The performances of different methods of quantification of protein (methods based on direct spectrophotometric and spectrofluorimetric analysis, chemical reactions and liquid chromatography) to quantify the amount of enzyme incorporated into polyalkylcyanoacrylate nanoparticles, were compared. A methodology based on size exclusion chromatography was selected. The performances of the analytical method to quantify the enzymes L-asparaginase and superoxide dismutase in different polymerization media of poly-isobutilcyanoacrylate, were evaluated. The quantification of superoxide dismutase in the presence of esterase, enzyme used to solubilize nanoparticles, was attempted. An adequate separation between enzyme and the other components of polymerization media was achieved, so the selectivity of the method is adequate to the quantification of an enzyme in polymerization medium, either before or after polymerization. Although lack of selectivity of the column to separate enzymes was observed. The retention time of L-asparaginase and superoxide dismutase in polymerization medium are, respectively, 7.4 and 7.5. Linear correlation between peak area and enzyme concentration were observed for both enzymes in the concentration range from 10 to 80 micrograms ml-1, either before or after polymerization and in different polymerization media. This SE-HPLC analytical methodology is adequate to determine the degree of incorporation of enzymes in polyalkylcyanoacrylate nanoparticles as evidenced by the linear responses of the chromatographic method, the reproductibility of repeated sample injections and the precision of the quantification of enzyme concentration.
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Cruz T, Gaspar R, Donato A, Lopes C. Interaction between polyalkylcyanoacrylate nanoparticles and peritoneal macrophages: MTT metabolism, NBT reduction, and NO production. Pharm Res 1997; 14:73-9. [PMID: 9034224 DOI: 10.1023/a:1012059501947] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE The nature of interactions between macrophages and drug carriers is of primordial importance either in the design of more effective therapeutic strategies for macrophage-associated pathogenesis or in establishing new approaches for pharmacological action avoiding macrophages. METHODS Polyalkylcyanoacrylate nanoparticles (PMCA, PECA, PBCA and PIBCA nanoparticles) were assayed for their toxicity on peritoneal resident and thioglycolate-elicited macrophages. Cellular viability was assessed by MTT tetrazolium salt assay, oxidative burst by NBT reduction and NO production by nitrite evaluation. RESULTS The nanoparticles tested led to cellular morphological modifications and induced toxicity in both types of macrophages in culture. The polyalkylcyanoacrylate nanoparticles uptake by peritoneal macrophages caused an increase in respiratory burst, as assessed by the NBT reduction assay, and induced the release of soluble toxic factors to the culture medium. The association of LPS with the PMCA nanoparticles significantly stimulated the production of nitric oxide (NO) by resident macrophages. In contrast, the association of PBCA nanoparticles with LPS does not increase the nitrite production as compared with LPS alone, which may be due to a different physico-chemical interaction between LPS and the two types of polymers. CONCLUSIONS In cultured mice peritoneal macrophages, nanoparticles of PACA induce the production of oxygen reactive products, which cause changes in the cell metabolism of both resident and elicited macrophages. PMCA nanoparticles in association with LPS significantly increase the expression of the inducible isoform of nitric oxide synthase, leading to the release of large amount of NO, which may be highly cytotoxic to the cultured cells in the presence of peroxide generated from the oxidative burst.
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Martins M, Simões S, Supico A, Cruz M, Gaspar R. Enzyme-loaded PIBCA nanoparticles (SOD and l-ASNase): Optimization and characterization. Int J Pharm 1996. [DOI: 10.1016/0378-5173(96)04652-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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da Costa FD, da Costa IA, Poffo R, Abuchaim D, Gaspar R, Garcia L, Faraco DL. Myocardial revascularization with the radial artery: a clinical and angiographic study. Ann Thorac Surg 1996; 62:475-9; discussion 479-80. [PMID: 8694608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND It has been well documented that the use of the internal thoracic artery yields better long-term patency rates than saphenous vein grafts for coronary artery bypass grafting. This knowledge has prompted surgeons to use other arterial conduits such as the radial artery. METHODS Between April 1994 and January 1996, radial artery grafts were used in 83 patients (mean age, 54.6 years) undergoing myocardial revascularization. All patients received diltiazem, 80 mg orally three times daily. Angiographic studies were performed in the early post-operative period in 61 patients, and 6 to 19 months later in 12 patients. RESULTS There were four hospital deaths (4.8%), none of them due to cardiac causes. Perioperative myocardial infarction was observed in 3 patients, 1 related to a radial artery graft occlusion. Of 61 grafts studied early, 59 were patent (96.7%), but two grafts showed diffuse spasm. Twelve patients had a second angiogram after a mean interval of 8.7 months, and all grafts were patent. One patient who had a diffuse spasm at the early study had recurrent symptoms, and repeat angiogram showed further narrowing of the graft (string sign). CONCLUSIONS Our results suggest that with proper care, the radial artery may be used for coronary artery bypass grafting with good early results. Long-term follow-up and angiography studies will be needed to establish the merit of the radial artery as a graft for coronary artery operations.
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Panyi G, Gaspar R, Krasznai Z, ter Horst JJ, Ameloot M, Aszalos A, Steels P, Damjanovich S. Immunosuppressors inhibit voltage-gated potassium channels in human peripheral blood lymphocytes. Biochem Biophys Res Commun 1996; 221:254-8. [PMID: 8619842 DOI: 10.1006/bbrc.1996.0582] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effects of immunosuppressive agents on the potassium current of human peripheral blood lymphocytes have been studied using the whole-cell patch-clamp technique. Cyclosporin A (10 micrograms/ml), rapamycin (10 micrograms/ml) and FK-506 (2.5 micrograms/ml) reduced the peak K+ current by approximately 40, 30 and 40% of the control, respectively, without any change in the reversal potential of the current. The current inhibition was similar at all membrane potentials studied and was accompanied with an increase in the rate of K+ current inactivation. Membrane potential measurements in current-clamp showed a marked depolarization of the membrane (>10 mV) upon the addition of either immunosuppressor to the cells. Our findings revealed that the voltage-dependent potassium current in human peripheral blood lymphocytes is inhibited by Cyclosporin A and other immunosuppressors, resulting in a depolarized membrane potential.
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Goda K, Krasznai Z, Gaspar R, Lankelma J, Westerhoff HV, Damjanovich S, Szabó G. Reversal of multidrug resistance by valinomycin is overcome by CCCP. Biochem Biophys Res Commun 1996; 219:306-10. [PMID: 8604982 DOI: 10.1006/bbrc.1996.0228] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Reversal of P-glycoprotein-mediated multidrug resistance by valinomycin is overcome by the proton ionophore, CCCP. This effect, a complete suppression of the 5- to 10-fold valinomycin-induced reversal ("re-reversal"), exhibits a sharp extracellular potassium concentration ([K+(0)]) dependence. It is observed at [K+(0)] > 2-4 mM and not at [K+(0)] greater than or equal to 2 mM, in the case of the fluorescent substrates rhodamine 123 and daunorubicin. The fact that "re-reversal" is detected only for the combination of CCCP with valinomycin raises the possibility that a direct interaction between these ionophores may explain the phenomenon. We show spectroscopic evidence of such an interaction, with a [K+(0)]-dependence similar to that of the "re-reversal." These data suggest that the reversal of P-glycoprotein activity by valinomycin can be compromised by anionic compounds such as CCCP due to complex formation. More generally, molecular interactions involving P-glycoprotein substrates or reversing agents may significantly affect drug accumulation in multidrug resistant cells.
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73
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Gaspar R, Préat V, Opperdoes FR, Roland M. Macrophage activation by polymeric nanoparticles of polyalkylcyanoacrylates: activity against intracellular Leishmania donovani associated with hydrogen peroxide production. Pharm Res 1992; 9:782-7. [PMID: 1409361 DOI: 10.1023/a:1015807706530] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Nanoparticles of polyalkylcyanoacrylates (PACA) can be useful carrier for the targeting of antileishmanial drugs into macrophages and also possess significant antileishmanial activity by themselves. No significant difference in antileishmanial activity could be detected between nanoparticles of five PACAs with differing alkyl side chains, suggesting that the main degradation products of PACA are not involved in their antileishmanial action. The effect of polyisohexylcyanoacrylate (PIHCA) on the induction of the respiratory burst in a macrophage-like cell line (J774G8) was assessed in non-infected macrophages and in macrophages infected with amastigotes of Leishmania donovani infantum, by measuring nitroblue tetrazolium (NBT) reduction and hydrogen peroxide production. Phagocytosis of PIHCA nanoparticles led to a respiratory burst, which was more pronounced in infected than in uninfected macrophages. The production of reactive oxygen intermediates associated with the respiratory burst was inhibited by addition of superoxide dismutase and catalase to the cell suspensions. The addition of catalase to the culture medium together with PIHCA nanoparticles significantly reduced the antileishmanial activity of PIHCA. Moreover PIHCA nanoparticles did not induce interleukin-1 release by macrophages. It is suggested that the antileishmanial action of PIHCA and other PACA nanoparticles results from the activation of respiratory burst in macrophages.
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Gaspar R, Opperdoes FR, Préat V, Roland M. Drug targeting with polyalkylcyanoacrylate nanoparticles: in vitro activity of primaquine-loaded nanoparticles against intracellular Leishmania donovani. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1992; 86:41-9. [PMID: 1616394 DOI: 10.1080/00034983.1992.11812629] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The efficacy of primaquine-loaded polyisohexylcyanoacrylate (PIHCA) nanoparticles was evaluated using J774G8 macrophage-like cells infected with Leishmania donovani: as an in vitro model of visceral leishmaniasis. The in vitro antileishmanial activity of primaquine-loaded nanoparticles showed a 21-fold increase in ED50 compared with free primaquine. Although unloaded PIHCA nanoparticles also exhibited a significant anti-leishmanial effect, the loaded nanoparticles showed a synergistic effect compared with a mixture of unloaded nanoparticles and free primaquine at equivalent concentrations. Primaquine release and isohexanol production were evaluated in a lysosomal fraction; the correlation of both with protein concentration and the rapid drug release indicate the processes are associated with an enzymatic degradation. The results indicate that PIHCA and other polyalkylcyanoacrylates may be useful for targeting drugs at intracellular Leishmania, and that the unloaded carrier itself could be of interest in experimental chemotherapy of leishmaniasis.
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Gaspar R, Préat V, Roland M. Nanoparticles of polyisohexylcyanoaerylate (PIHCA) as carriers of primaquine: formulation, physico-chemical characterization and acute toxicity. Int J Pharm 1991. [DOI: 10.1016/0378-5173(91)90133-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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76
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Gaspar R, Andrew E. Phosphorus-31 magnetic relaxation of inorganic orthophosphate in solution. Chem Phys Lett 1990. [DOI: 10.1016/0009-2614(90)87110-d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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77
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Gaspar R, Brey W, Qiu A, Andrew E. Phosphorus-31 magnetic relaxation of adenosine 5′-monophosphate, adenosine 5′-diphosphate and adenosine 5′-triphosphate in solution. Chem Phys Lett 1989. [DOI: 10.1016/s0009-2614(89)87243-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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78
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Gaspar R, Andrew E, Bryant D, Cashell E. Dipolar relaxation and slow molecular motions in solid proteins. Chem Phys Lett 1982. [DOI: 10.1016/0009-2614(82)83516-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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79
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Andrew ER, Gaspar R, Venart W. Proton magnetic relaxation in solid poly(L-alanine), poly(L-leucine), poly(L-valine), and polyglycine. Biopolymers 1978. [DOI: 10.1002/bip.1978.360170808] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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80
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Andrew E, Gaspar R, Vennart W. Proton magnetic resonance investigation of solid polyamino acids. Chem Phys Lett 1976. [DOI: 10.1016/0009-2614(76)80275-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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81
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Gaspar R, Damjanovich S. Proton magnetic resonance studies on SH groups in glycogen phosphorylase b. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 315:191-4. [PMID: 4743902 DOI: 10.1016/0005-2744(73)90142-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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