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D K Meijer

Publications and source records attributed to D K Meijer.

At least 37 records · Page 2Linked to original sources
PubMed2000

The capability of isolated hepatocytes and liver slices of donor livers to predict graft function after liver transplantation.

AIMS/BACKGROUND: In liver transplantation, adequate function tests for donor livers and transplanted livers are of utmost importance to provide an objective basis for decision-making. Isolated hepatocyte and/or slice preparations from human donor liver tissue may be suitable to test the quality of the organ to be transplanted. METHODS: Surgical waste material remaining after reduced size or split liver transplantation in children was used to prepare slices and isolated hepatocytes. The viability of these preparations as well as drug transport and metabolism functions were determined and related to graft function in 32 liver recipients. RESULTS: The in vitro tests used in the present study apparently did not select non-viable livers. In vitro preparations of the primary non-function grafts which occurred in the investigated group showed normal viability, metabolic and uptake function. CONCLUSION: These results indicate that either the presently used viability tests are not sensitive enough to detect potential organ failure or that other factors besides the hepatocyte viability at the time of transplantation are of paramount importance to the graft function of the recipient, such as complications during and after transplantation or the viability of the non-parenchymal cells.

Adenosine Triphosphate↗
PubMed2000

Mrp2 is essential for estradiol-17beta(beta-D-glucuronide)-induced cholestasis in rats.

The present study evaluates the roles of the multidrug resistance-1 P-glycoprotein, Mdr1a/1b, the bile salt export pump (Bsep), and the multidrug resistance-associated protein-2 (Mrp2) in mediating cholestasis induced by estradiol-17beta(beta-D-glucuronide) (E(2)17G). Administration of ¿(3)HE(2)17G (18 nmol/g body weight) gave a similar degree of cholestasis and biliary excretion of E(2)17G-equivalents in wild-type and Mdr1a(-/-)/1b(-/-) mice. When expressed in Sf9 cells, Bsep-mediated adenosine triphosphate (ATP)-dependent transport of taurocholate (TC, 1 micromol/L) in membrane vesicles was 110% +/- 12.5% and 108% +/- 17.3% of control in the presence of 10 and 50 micromol/L E(2)17G, respectively, whereas in rat canalicular membrane, both E(2)17G and the choleretic estradiol-3-beta-D-glucuronide (E(2)3G) inhibited ATP-dependent transport of TC to the same extent. Infusion of ¿(3)HE(2)17G (24 micromol) did not induce cholestasis in Mrp2-deficient TR(-) rats whereas 2 micromol of ¿(3)HE(2)17G inhibited bile flow by 51% in control Wistar rats. The maximal biliary concentration of E(2)17G was 3.5 and 2.5 mmol/L in control and TR(-) rats, respectively. However, 2.2 mmol/L of E(2)17G in bile is associated with inhibition of bile flow in control rats. These data show that (1) Mdr1a/1b are not essential for E(2)17G-mediated cholestasis, (2) direct inhibition of Bsep-mediated bile acid transport is not the mechanism for E(2)17G cholestasis, and (3) accumulation of E(2)17G in bile alone is not sufficient to induce cholestasis. These data indicate that the process of Mrp2-mediated transport of high concentrations of E(2)17G is essential for its induction of cholestasis.

ATP-Binding Cassette Transporters↗
PubMed2000

CD3 directed bispecific antibodies induce increased lymphocyte-endothelial cell interactions in vitro.

Bispecific antibody (BsMAb) BIS-1 has been developed to redirect the cytolytic activity of cytotoxic T lymphocytes (CTL) to epithelial glycoprotein-2 (EGP-2) expressing tumour cells. Intravenous administration of BIS-1 F(ab')2 to carcinoma patients in a phase I/II clinical trial, caused immunomodulation as demonstrated by a rapid lymphopenia prior to a rise in plasma tumour necrosis factor-alpha and interferon-gamma levels. Yet, no lymphocyte accumulation in the tumour tissue and no anti-tumour effect could be observed. These data suggest a BsMAb-induced lymphocyte adhesion to blood vessel walls and/or generalized redistribution of the lymphocytes into tissues. In this study, we describe the effects of BIS-1 F(ab')2 binding to peripheral blood mononuclear cells (PBMC) on their capacity to interact with resting endothelial cells in vitro. Resting and pre-activated PBMC exhibited a significant increase in adhesive interaction with endothelial cells when preincubated with BIS-1 F(ab')2, followed by an increase in transendothelial migration (tem). Binding of BIS-1 F(ab')2 to PBMC affected the expression of a number of adhesion molecules involved in lymphocyte adhesion/migration. Furthermore, PBMC preincubated with BIS-1 F(ab')2 induced the expression of endothelial cell adhesion molecules E-selectin, VCAM-1 and ICAM-1 during adhesion/tem. These phenomena were related to the CD3 recognizing antibody fragment of the BsMAb and dependent on lymphocyte-endothelial cell contact. Possibly, in patients, the BIS-1 F(ab')2 infusion induced lymphopenia is a result of generalized activation of endothelial cells, leading to the formation of a temporary sink for lymphocytes. This process may distract the lymphocytes from homing to the tumour cells, and hence prevent the occurrence of BIS-1 F(ab')2 - CTL-mediated tumour cell lysis.

Antibodies, Bispecific↗
PubMed2000

Pharmacokinetics and in vivo gene transfer of plasmid DNA complexed with mannosylated poly(L-lysine) in mice.

To achieve mannose receptor-mediated, cell-specific, in vivo gene transfer by intravenous injection of plasmid DNA, mannosylated poly(L-lysine) (Man-PLL) was synthesized as a carrier molecule, and mixed with a plasmid DNA encoding chloramphenicol acetyltransferase (CAT) gene to form DNA/Man-PLL complex. The particle size and zeta potential of DNA/Man-PLL (prepared at 1:0.7 on a weight basis) were determined to be 220 nm and +12 mV, respectively. The pharmacokinetics of the DNA/Man-PLL complex was assessed in mice using 32P-labeled DNA ([32P]DNA). After intravenous injection of [32P]DNA/Man-PLL, the radioactivity in plasma fell rapidly and was recovered mainly in the liver nonparenchymal cells. The amount in the liver reached more than 80% of the dose. Radioactivity observed in kidney, lung, and spleen was very low compared to that in the liver. Then, the in vivo gene expression after intravenous injection of DNA/Man-PLL was examined by a CAT assay. Highest CAT activity was detected in the liver, but no activity was detected in the lung, kidney, and spleen. These results clearly indicate that a cell-specific gene delivery system can be developed by regulating the biodistribution of DNA/carrier complex through the control of its physicochemical properties.

Animals↗
PubMed2000

Structure-pharmacokinetics relationship of series of aminosteroidal neuromuscular blocking agents in the cat.

To obtain more insight in the relationship between physicochemical properties of neuromuscular blocking agents (NMBAs) and their pharmacokinetic characteristics, a series of 12 aminosteroidal NMBAs, supplemented with data on five related NMBAs from the literature, was investigated in anaesthetized cats. After i.v. bolus injection, plasma concentration decreased very rapidly, showing a biphasic pattern, with half-lives ranging from 0.4 to 1.4 min, and from 3 to 10 min, respectively. Clearance was in the range from 24 to 58 ml. min(-1). kg(-1). Compounds containing an acetyl-ester group at position 3 were partly metabolized to the 3-OH derivative. The urinary excretion of the parent drug and metabolites amounted to <10% for each of the compounds. The parent drugs were excreted in large amounts into bile, along with smaller amounts of 3-OH derivatives. The terminal half-life of the urinary and biliary excretion rate were markedly longer than the apparent terminal half-life in plasma, ranging from 11 to 40 min, and from 119 to 489 min in urine and bile, respectively. Lipophilicity of the NMBAs, expressed as the partition coefficient octanol/Krebs (log P), was found to be correlated positively with unbound plasma clearance and unbound initial plasma clearance, and negatively with plasma half-life, volume of distribution at steady state, and mean residence time. The increase of the unbound plasma clearance with increasing lipophilicity is counteracted by the concurrent increase in plasma protein binding.

Animals↗
PubMed1999

Resistance of the human immunodeficiency virus to the inhibitory action of negatively charged albumins on virus binding to CD4.

Negatively charged albumins (NCAs) have been identified as potent inhibitors of HIV-1 replication in vitro. Time of addition studies suggest that succinylated and aconitylated human serum albumin (Suc-HSA and Aco-HSA) act at an early stage of the virus life cycle, and surface plasmon resonance (BIAcore) experiments have confirmed a direct interaction of NCAs with HIV-1 gp120. Resistance to Suc-HSA and Aco-HSA was analyzed by characterizing HIV-1 variants that were selected in cell culture after serial passage of the NL4-3 strain in the presence of the compounds. After 24 passages (126 days) we isolated variants that were resistant to Suc-HSA (>27-fold) and Aco-HSA (37-fold), as compared with the wild-type NL4-3 virus. The binding of the NCA-resistant HIV strains to CD4+ MT-4 cells could no longer be inhibited by either Suc- or Aco-HSA. The emergence of mutations in the envelope gp120 of the resistant virus paralleled the emergence of the resistant phenotype. The Suc-HSA-resistant strain was 100-fold cross-resistant to the G quartet-containing oligonucleotide AR177 (Zintevir, an HIV-binding inhibitor), and partially cross-resistant to dextran sulfate, but remained sensitive to the bicyclam AMD3100 and the chemokine SDF-1alpha, which block HIV replication by interaction with the chemokine receptor CXCR4. Furthermore, neither Suc-HSA nor Aco-HSA inhibited the binding of monoclonal antibodies 12G5 and 2D7 (directed to CXCR4 and CCR5, respectively) in SUPT-1 cells or THP-1 cells. These results confirm that NCAs bind primarily to gp120 and do not interact directly with the HIV chemokine receptor but block the binding of the virus particles (through gp120) with CD4+ cells.

Aconitic Acid↗
PubMed1999

Homing of negatively charged albumins to the lymphatic system: general implications for drug targeting to peripheral tissues and viral reservoirs.

The present study shows the lymphatic distribution of the negatively charged anti-HIV-1 agents succinylated or aconytilated human serum albumins (HSAs) in rats. Quantitation of blood and lymphatic concentrations of these proteins was performed through fluorescence detection of the fluorescein isothiocyanate (FITC)-labeled proteins. At several time points after i.v. injection, samples were taken from the cannulated thoracic duct and the carotid artery. Distribution of the negatively charged albumins (NCAs) to lymph was much more rapid than that of albumin itself and was dependent on the total net negative charge added to the protein: the half-life times of lymphatic equilibration were 15, 30, and 120 min for FITC-labeled aconytilated HSA, FITC-labeled succinylated HSA, and FITC-labeled HSA, respectively. Lymph to blood concentration ratios of the studied compounds obtained at steady state approached unity. In addition, the fluorescence in both body fluids was shown to represent unchanged labeled proteins. It was therefore inferred that the NCAs efficiently passed the endothelial barrier from blood to the interstitial compartment. Subsequently, we studied whether a specialized process was involved in the endothelial passage of the NCAs to the lymph. The following observations supported such a mechanism: a) preinjection of the scavenger receptor blockers polyinosinic- and formaldehyde-treated HSA reduced the transport from blood to the lymphatic compartment of FITC-labeled aconytilated HSA by more than 90%; b) the rate of lymphatic distribution was largely reduced when the body temperature of the rat was lowered to 28 degrees; and c) pre-administration of chloroquine resulted in a significant reduction in the lymphatic distribution of the NCAs. These data collectively indicate that a scavenger receptor-mediated process is involved in the transendothelial transport of NCAs. In situ localization in lymph nodes of the rat showed that FITC-labeled aconytilated and succinylated HSA are mainly present in the germinal center and parafollicular zones. The efficient distribution of these anionized proteins to the lymphatic system is of particular interest for HIV therapy, taking into account that replication of HIV mainly takes place in the lymphoid system. The observation that macromolecules, through charge modification, can extravasate through a receptor-mediated transcytotic process is potentially of major importance for the delivery of drugs with macromolecular carriers to cells not directly in contact with the blood.

Albumins↗
PubMed1999

Mechanism of anti-HIV activity of succinylated human serum albumin.

In the present study, we described the interaction of succinylated human serum albumin (Suc-HSA), a negatively charged anti-HIV-1 active protein, with HIV-1 gp120 and in detail with the third variable domain of gp120 (V3 loop). To this end, different assay formats were tested in which gp120- and V3-related peptides were presented in various configurations in order to investigate the effect of the conformational structure of the V3 loop on the interaction with negatively charged albumins. When gp120 presented via a lectin was used, it was observed that Suc-HSA bound to native gp120. The binding site appeared to be located at or near the thrombin digestion site (GPGRAF sequence) in the V3 loop of gp120, since the cleavage of the loop resulted in decreased binding of Suc-HSA. In addition, Suc-HSA was able to protect the V3 region of gp120 from cleaving with thrombin. In contrast, significant binding of Suc-HSA to V3 loop or gp120 peptides was not observed when both were presented in a fluid phase system, suggesting the involvement of a monovalent-low affinity binding of Suc-HSA. Using overlapping peptides delineating the whole V3 loop immobilized to CNBr-Sepharose, we noticed that the interaction of the V3 loop with Suc-HSA was predominantly induced by electrostatic interactions between positively charged linearized peptide fragments and Suc-HSA and was positively influenced by the presence of hydrophobic amino in the V3 loop fragments as well. Moreover, the highest affinity site was located at sites near the GPGRAF sequence. These observations add to the evidence, collected earlier, that Suc-HSA interferes at the level of virus entry, independent of interaction with the CD4 receptor. Since the recently discovered chemokine receptors are negatively charged, we can hypothesize that Suc-HSA is able to prevent the positively charged V3 loop from interacting with these types of receptors, thereby inhibiting virus entry.

Amino Acid Sequence↗
PubMed1999

Charge modification of plasma and milk proteins results in antiviral active compounds.

Previous studies have shown that acylated plasma and milk proteins with increased negative charge, derived from various animal and human sources, are potent anti-HIV compounds. The antiviral effects seemed to correlate positively with the number of negative charges introduced into the various polypeptides: proteins with a high content of basic amino acids in which all of the available epsilonNH2 groups were anionized yielded the most potent anti-HIV compounds. It remained unclear however whether the total net negative charge of the various derivatized proteins, or rather the charge density on the protein backbone, is essential for the observed anti-HIV activity. Earlier studies have shown that acylated albumins preferentially block the process of HIV/cell fusion through binding to the HIV envelope proteins gp120 and gp41 as well as to the cell surface of the HIV target cells. Some of these polyanionic proteins have been shown to interfere also with the gp120-CD4 mediated virus/cell binding. The relative contribution of these effects to the anti-HIV activity may depend both on the total negative charge introduced as well as the hydrophobicity of the acylating reagent added to the particular proteins. In this study we show that the higher the charge density of the derivatized proteins, the more potent their HIV replication inhibiting effects are. In contrast, the addition of positive charge to the studied plasma and milk proteins through amination resulted in a reduced anti-HIV activity but a clearly increased anti-HCMV activity, with IC50 values in the low micromolar concentration range. Interestingly, native lactoferrin (Lf) was antivirally active against both HIV and HCMV. Acylation or amination of Lf increased the anti-HIV and anti-HCMV activity, respectively. The N-terminal portion of Lf appeared essential for its anti-HCMV effect: N-terminal deletion variants of human Lf were less active against HCMV. Circular dichroism of the modified proteins showed that the secondary structure of the tested proteins was only moderately influenced by acylation and/or covalent attachment of drugs, making these (derivatized) proteins useful candidates as antiviral agents and/or intrinsically active drug carriers. The relatively simple chemical derivatization as well as the abundant sources of blood plasma and milk proteins provides attractive opportunities for the preparation of potent and relatively cheap antiviral agents for systemic or local applications.

Animals↗
PubMed1999

Albumin modified with mannose 6-phosphate: A potential carrier for selective delivery of antifibrotic drugs to rat and human hepatic stellate cells.

The hallmark of liver fibrosis is an increased extracellular matrix deposition, caused by an activation of hepatic stellate cells (HSC). Therefore, this cell type is an important target for pharmacotherapeutic intervention. Antifibrotic drugs are not efficiently taken up by HSC or may produce unwanted side-effects outside the liver. Cell-specific delivery can provide a solution to these problems, but a specific drug carrier for HSC has not been described until now. The mannose 6-phosphate/insulin-like growth factor II (M6P/IGF-II) receptor, which is expressed in particular upon HSC during fibrosis, may serve as a target-receptor for a potential carrier. The aim of the present study was to examine if human serum albumin (HSA) modified with mannose 6-phosphate (M6P) is taken up by HSC in fibrotic livers. A series of M6Px-modified albumins were synthetized: x = 2, 4, 10, and 28. Organ distribution studies were performed to determine total liver uptake. The hepatic uptake of M6Px-HSA increased with increasing M6P density. M6Px-HSA with a low degree of sugar loading (x = 2-10) remained in the plasma and accumulated for 9% +/- 0.5% or less in fibrotic rat livers. An increase in the molar ratio of M6P:HSA to 28:1 caused an increased liver accumulation to 59% +/- 9% of the administered dose. Furthermore, we determined quantitatively the in vivo intrahepatic distribution of M6Px-HSA using double-immunostaining techniques. An increased substitution of M6P was associated with an increased accumulation in HSC; 70% +/- 11% of the intrahepatic staining for M6P28-HSA was found in HSC. We also demonstrate that M6P-modified bovine serum albumin (BSA) accumulates in slices of normal and cirrhotic human livers. After incubation of this neoglycoprotein with human tissue, the protein is found in nonparenchymal liver cells. Because M6P-modified albumins are taken up by HSC in fibrotic livers, this neoglycoprotein can be applied as a selective drug carrier for HSC. This technology may create new opportunities for the pharmacological intervention of liver fibrosis.

Animals↗
PubMed1999

3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) induce hepatic expression of the phospholipid translocase mdr2 in rats.

BACKGROUND & AIMS: Biliary cholesterol secretion is coupled to that of phospholipids in a process controlled by mdr2 P-glycoprotein activity and bile salt secretion. Statins, the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, have been shown to affect hepatobiliary lipid secretion in rats. The aim of this study was to relate the effects of statins on bile formation to the expression of mdr2 and other hepatic adenosine triphosphate-dependent transport proteins involved in bile formation in rats. METHODS: Rats received simvastatin- or pravastatin-containing chow continuously for 5 days. In one group of rats, simvastatin treatment was withdrawn 9-12 hours before the end of the experiment to induce biliary cholesterol hypersecretion (rebound). Bile and liver tissue were collected for lipid analysis, and hepatic messenger RNA (mRNA) and protein levels were studied by reverse-transcription polymerase chain reaction, immunoblotting, and immunohistochemistry. RESULTS: Simvastatin feeding did not alter biliary bile salt secretion. Secretion of phospholipids and cholesterol was stimulated by 74% and 90%, respectively, in the simvastatin-continuous group and by 72% and 235%, respectively, in the rebound group compared with controls. mdr2 mRNA levels increased only in the continuous group. mdr2 protein levels increased in both simvastatin-fed groups. Induction was most pronounced in periportal hepatocytes. mdr1b mRNA levels were moderately increased in both simvastatin-fed groups. Levels of other hepatic transport proteins did not change. Similar results were obtained in pravastatin-fed rats. CONCLUSIONS: Statins increase expression of mdr2 and mdr1b in rats, revealing a novel effect of these commonly used drugs.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1999

Targeting of superoxide dismutase to the liver results in anti-inflammatory effects in rats with fibrotic livers.

BACKGROUND/AIMS: The rapid clearance from plasma and the limited uptake of superoxide dismutase (SOD) in the liver hampers the effectiveness of this enzyme in liver diseases. We therefore compared the pharmacokinetics and in vivo efficacy of SOD with two modified forms of this protein: SOD coupled to the copolymer DIVEMA and mannosylated-SOD. METHODS: Reactive oxygen scavenging activity of SOD conjugates was tested in livers of bile duct ligated rats. Intrahepatic production of reactive oxygen species (ROS) and neutrophil infiltration were studied immunohistochemically and related to the organ and cellular distribution of radiolabeled SOD conjugates. RESULTS: Native SOD was rapidly cleared from the circulation and accumulated in renal tubuli. The enzyme had no effect on the intrahepatic ROS production. Covalent attachment of SOD to DIVEMA yielded a polyanionic conjugate with a prolonged elimination half-life compared to native SOD. In contrast to native SOD, DIVEMA-SOD was taken up by the liver via scavenger receptors. Mannosylation of SOD (Man-SOD) resulted in a conjugate that was rapidly cleared from the blood. This Man-SOD was taken up by non-parenchymal liver cells. The pharmacokinetics of SOD and its derivatives were similar in normal and bile duct ligated rats. Efficacy studies with Man-SOD revealed only a slight decrease in intrahepatic ROS production. However, DIVEMA-SOD exhibited a potent inhibitory effect on ROS production in the liver. Nearly complete ROS-scavenging activity was observed in the portal areas. CONCLUSIONS: Considering the prolonged half-life, the increased delivery of SOD to the target cells, and the concomitant increased effectiveness, application of DIVEMA-SOD seems a promising new approach to attenuate intrahepatic inflammatory processes.

Animals↗
PubMed1999

Molecular mechanisms of the adsorption of a model protein (human serum albumin) on poly(methylidene malonate 2.1.2) nanoparticles.

PURPOSE: To understand the molecular mechanisms involved in protein-methylidene malonate 2.1.2 polymer interactions. METHODS: To assess the importance of electrostatic forces in polymer-protein interactions use was made of HSA and its derivatives, which were anionized by succinylation and aconitylation. Surface plasmon resonance measurements, using the three HSA molecules as immobilized ligands and polymer nanoparticles as analytes in the liquid phase, allowed the determination of initial kinetic constants and affinity constants at equilibrium at two different temperatures. RESULTS: Saturation of binding for the three proteins occurred at approximately 900 protein molecules/nanoparticle. The apparent affinity decreased with increasing electronegativity of the proteins. Surface plasmon resonance measurement of proteins, covalently linked to the chip matrix, showed a high affinity for the nanoparticles (K(A) approximately 10(10) M(-1) and confirmed the moderate decrease of affinity with increasing electronegativity of the modified albumins. Measurements at 25 and 37 degrees C showed no significant increase in the albumin-nanoparticle interactions. Dissociation of the proteins from the nanoparticles could only be realized with chaotropic salt solutions. CONCLUSIONS: These results suggest the molecular forces initiating the protein-nanoparticle interactions are mainly of electrostatic nature followed by stabilization by hydrophobic forces. The high affinity confirms the nanoparticles as excellent carriers for protein delivery.

Aconitic Acid↗
PubMed1999

Plasma lactoferrin levels are decreased in end-stage AIDS patients.

The antimicrobial protein lactoferrin (Lf) is present in plasma and in mucosal secretions. Using ELISA we analysed plasma and saliva of HIV-infected patients, patients with AIDS, and healthy controls for the presence of secreted Lf. The plasma Lf levels of AIDS patients (classification C3) were significantly lower (p < 0.001) as compared to asymptomatic and symptomatic HIV infected patients, or controls. In addition, plasma Lf levels closely correlated with neutrophilic granulocyte counts in the HIV-infected patients. Thus, basal plasma Lf levels are likely the result of Lf release by neutrophilic granulocytes. The Candida titres present in the oral cavity were determined in a part of the HIV-infected patient group. As it appeared, the presence of this opportunistic pathogen always coincided with low levels of salivary Lf levels. We conclude that Lf, as part of the nonspecific immune system, might play an important role in the first line of defense against opportunistic microbial infections in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1999

Synergistic fungistatic effects of lactoferrin in combination with antifungal drugs against clinical Candida isolates.

Because of the rising incidence of failures in the treatment of oropharyngeal candidosis in the case of severely immunosuppressed patients (mostly human immunodeficiency virus [HIV]-infected patients), there is need for the development of new, more effective agents and/or compounds that support the activity of the common antifungal agents. Since lactoferrin is one of the nonspecific host defense factors present in saliva that exhibit antifungal activity, we studied the antifungal effects of human, bovine, and iron-depleted lactoferrin in combination with fluconazole, amphotericin B, and 5-fluorocytosine in vitro against clinical isolates of Candida species. Distinct antifungal activities of lactoferrin were observed against clinical isolates of Candida. The MICs generally were determined to be in the range of 0.5 to 100 mg. ml(-1). Interestingly, in the combination experiments we observed pronounced cooperative activity against the growth of Candida by using lactoferrin and the three antifungals tested. Only in a limited concentration range was minor antagonism detected. The use of lactoferrin and fluconazole appeared to be the most successful combination. Significant reductions in the minimal effective concentrations of fluconazole were found when it was combined with a relatively low lactoferrin concentration (1 mg/ml). Such combinations still resulted in complete growth inhibition, while synergy of up to 50% against several Candida species was observed. It is concluded that the combined use of lactoferrin and antifungals against severe infections with Candida is an attractive therapeutic option. Since fluconazole-resistant Candida species have frequently been reported, especially in HIV-infected patients, the addition of lactoferrin to the existing fluconazole therapy could postpone the occurrence of species resistance against fluconazole. Clinical studies to further elucidate the potential utility of this combination therapy have been initiated.

Amphotericin B↗
PubMed1999

Anti-HIV-1 activity of combinations and covalent conjugates of negatively charged human serum albumins (NCAs) and AZT.

Negatively charged albumins (NCAs, with the prototypes Suc-HSA and Aco-HSA), modified proteins with a potent anti-HIV-1 activity in the nanomolar concentration range, were studied for several aspects of their antiviral mechanism. In addition we investigated the antiviral activity of combinations and covalent conjugates of these NCAs and the reverse transcriptase inhibitor AZT. Addition of NCAs to HIV-1-infected target cells in time-of-addition experiments could be delayed for 30 min after infection before significant loss of activity occurred. Syncytium formation of HIV-infected and uninfected T-cells was inhibited by the NCAs at concentrations of 1-4 microg/ml. The gp120-mediated virus/cell binding, however, was only inhibited by the NCAs at a 10-fold higher concentrations. The combined data are compatible with a preferential influence on virus/cell fusion. A subsynergistic activity against HIV-1 was observed with the non-covalent mixture of Aco-HSA and AZT. When AZT was covalently coupled to the NCAs, and added one hour after infection of the target cells, the anti-HIV-1 activity of NCA-AZTMP was diminished by only 2-6-fold, while this was diminished at least 120-fold for the NCAs. Furthermore the addition of NCA-AZTMP could be delayed up to at least 3 h after infection without loss of antiviral activity. It is concluded that AZT that was coupled to the NCAs significantly contributes to the overall antiviral activity of the conjugates leading to complementary effects. These results highlight the potential of using NCA-AZTMP as dual-targeting preparations against HIV-1 in which both the carrier and the coupled drug contribute to the therapeutic efficacy acting at a different level in the replication cycle.

Aconitic Acid↗