Potential role of salivary lactic acid bacteria in pathogenesis of oral lichen planus.

BACKGROUND: Emerging evidence emphasized the role of oral microbiome in oral lichen planus (OLP). To date, no dominant pathogenic bacteria have been identified consistently. It is noteworthy that a decreased abundance of Streptococcus, a member of lactic acid bacteria (LAB) in OLP patients has been commonly reported, indicating its possible effect on OLP. This study aims to investigate the composition of LAB genera in OLP patients by high-throughput sequencing, and to explore the possible relationship between them. METHODS: We collected saliva samples from patients with OLP (n = 21) and healthy controls (n = 22) and performed 16 S rRNA gene high-throughput sequencing. In addition, the abundance of LAB genera was comprehensively analyzed and compared between OLP and HC group. To verify the expression of Lactococcus lactis, real time PCR was conducted in buccal mucosa swab from another 14 patients with OLP and 10 HC. Furthermore, the correlation was conducted between clinical severity of OLP and LAB. RESULTS: OLP and HC groups showed similar community richness and diversity. The members of LAB, Lactococcus and Lactococcus lactis significantly decreased in saliva of OLP cases and negatively associated with OLP severity. In addition, Lactococcus and Lactococcus lactis showed negative relationship with Fusobacterium and Aggregatibacter, which were considered as potential pathogens of OLP. Similarly, compared with healthy controls, the amount of Lactococcus lactis in mucosa lesion of OLP patients was significantly decreased. CONCLUSIONS: A lower amount of Lactococcus at genus level, Lactococcus lactis at species level was observed in OLP cases and associated with disease severity. Further studies to verify the relationship between LAB and OLP, as well as to explore the precise mechanism is needed.

Population pharmacokinetics of free and liposome-encapsulated mitoxantrone in patients with relapsed/refractory lymphoma or small cell lung cancer.

OBJECTIVE: This study is aimed at investigating the pharmacokinetic (PK) characteristics of pegylated liposomal mitoxantrone (PLM) in patients with relapsed/refractory lymphoma or small cell lung cancer (SCLC) by constructing population pharmacokinetic (popPK) models for both liposome-encapsulated mitoxantrone and free mitoxantrone. METHODS: A total of 23 patients with relapsed/refractory lymphoma and 42 patients with SCLC were included. A popPK model was simultaneously developed utilizing a non-linear mixed effects model (NONMEM) to explore the PK profiles of liposome-encapsulated mitoxantrone and free mitoxantrone. Clearance (CL) and distribution volume (V) were calculated, and covariate analysis was employed to evaluate the influence of patient disease type, demographic information, and biochemical indicators of liver and kidney function on PK parameters. RESULTS: The concentration-time profiles for both liposome-encapsulated mitoxantrone and free mitoxantrone were described by a one-compartment model. The release (Rel) of liposome-encapsulated mitoxantrone to free mitoxantrone was determined to be 0.0191 L/h, and the V of liposome-encapsulated mitoxantrone was 2.32 L. The apparent CL of free mitoxantrone was estimated at 1.66 L/h. The apparent V of free mitoxantrone was 35.8 L in patients with relapsed/refractory lymphoma and 22.2 L for patients with SCLC. In patients with relapsed/refractory lymphoma, lower maximum concentration (Cmax) and higher apparent V of free mitoxantrone were observed compared with patients with SCLC. CONCLUSION: The popPK characteristics of both liposome-encapsulated and free mitoxantrone in patients with relapsed/refractory lymphoma or SCLC were effectively described by a one-compartment model.

Efficacy and safety of mitoxantrone hydrochloride liposome injection in Chinese patients with advanced breast cancer: a randomized, open-label, active-controlled, single-center, phase II clinical trial.

PURPOSE: This trial aimed to evaluate the efficacy and safety of mitoxantrone hydrochloride liposome injection (Lipo-MIT) in advanced breast cancer (ABC). METHODS: In this randomized, open-label, active-controlled, single-center, phase II clinical trial, eligible patients were randomized in a ratio of 1:1 to receive Lipo-MIT or mitoxantrone hydrochloride injection (MIT) intravenously. The primary endpoint was objective response rate (ORR). The secondary endpoints were disease control rate (DCR), progression-free survival (PFS), and safety outcomes. RESULTS: Sixty patients were randomized to receive Lipo-MIT or MIT. The ORR was 13.3% (95% confidence interval (CI): 3.8-30.7%) for Lipo-MIT and 6.7% (95% CI: 0.8-22.1%) for MIT. The DCR was 50% (95% CI: 31.3-68.7%) with Lipo-MIT vs. 30% (95% CI: 14.7-49.4%) with MIT. The median PFS was 1.92 months (95% CI: 1.75-3.61) for Lipo-MIT and 1.85 months (95% CI: 1.75-2.02) for MIT. The most common toxicity was myelosuppression. Lipo-MIT resulted in an incidence of 86.7% of leukopenia and 80.0% of neutropenia, which was marginally superior to MIT (96.7% and 96.7%, respectively). Lipo-MIT showed a lower incidence of cardiovascular events (13.3% vs. 20.0%) and increased cardiac troponin T (3.3% vs. 36.7%); but higher incidence of anemia (76.7% vs. 46.7%), skin hyperpigmentation (66.7% vs. 3.3%), and fever (23.3% vs. 10.0%) than MIT. Conclusions The clinical benefit parameters of Lipo-MIT and MIT were comparable. Lipo-MIT provided a different toxicity profile, which might be associated with the altered distribution of the drug. Additional study is needed to elucidate the potential benefit of Lipo-MIT in ABC. CLINICAL TRIAL REGISTRATION: This study is registered with ClinicalTrials.gov (No. NCT02596373) on Nov 4, 2015.

Comparative study of indirect immunofluorescence, enzyme-linked immunosorbent assay, and the Tzanck smear test for the diagnosis of pemphigus.

BACKGROUND: Pemphigus is one of the potentially fatal autoimmune blistering diseases. An early and accurate diagnosis is important for prognosis and therapy. It may be difficult to diagnosis based on clinical grounds alone. Direct and indirect immunofluorescence, enzyme-linked immunosorbent assay, the Tzanck smear test, or histopathology are all available for the diagnosis of pemphigus. However, there are no generally accepted diagnostic criteria for the diagnosis of this condition at present. OBJECTIVE: To evaluate the diagnostic value of indirect immunofluorescence, enzyme-linked immunosorbent assay, and the Tzanck smear test for the diagnosis of pemphigus in dental clinics. METHODS: A single-center retrospective study was conducted, and the clinical data of 33 patients with pemphigus and 61 controls were collected and analyzed from the Department of Oral Medicine, Peking University School of Stomatology, during 2010-2014. The sensitivities and specificities of indirect immunofluorescence, enzyme-linked immunosorbent assay, and the Tzanck smear test were calculated and compared in two groups. RESULTS: Sensitivities for the Tzanck smear test, indirect immunofluorescence, and enzyme-linked immunosorbent assay were 96.7%, 84.8%, and 84.8%, respectively, whereas the specificities of these tests were 60%, 91.8%, and 96.7%, respectively. The serial tests for the Tzanck smear test and enzyme-linked immunosorbent assay showed 82% sensitivity and 98.7% specificity. CONCLUSIONS: The serial test for the Tzanck smear test and enzyme-linked immunosorbent assay may represent a simple, rapid, and reliable way to definitive diagnosis of pemphigus. It is recommended as a common test for the diagnosis of pemphigus in dental clinics.

Role of salivary anti-SSA/B antibodies for diagnosing primary Sjögren's syndrome.

UNLABELLED: The diagnosis of primary Sjögren's syndrome (pSS) is complex, and the saliva test is a potential method to improve the existing diagnostic criteria. OBJECTIVE: To estimate the diagnostic accuracy of salivary anti-SSA/B antibodies in primary Sjögren's syndrome (pSS), and to analyze their correlations with clinical and laboratory profiles. STUDY DESIGN: This study enrolled 100 pSS patients and 140 non-pSS controls, including 40 rheumatoid arthritis (RA) patients, 40 systemic lupus erythematosus (SLE) patients, and 60 healthy controls. Unstimulated whole saliva and stimulated parotid saliva samples were collected from the subjects. Salivary anti-SSA/B antibodies were measured using an enzyme-linked immunosorbent assay (ELISA). Clinical and laboratory data were retrieved from the medical records. RESULTS: In the pSS group, the sensitivity of anti-SSA and anti-SSB antibodies in whole saliva was 49% and 29%, respectively, and the specificity was 87.5% and 95%. The sensitivity of anti-SSA and anti-SSB antibodies in parotid saliva was 32% and 8%, respectively, and the specificity was 95.52% and 97.86%, respectively. In the pSS group, the diagnostic accuracy of anti-SSA/B antibodies in whole saliva was significantly higher than in parotid saliva (p<0.05), but was significantly lower than in serum (p<0.05). The salivary flow rate in the pSS group positive for whole salivary anti-SSA was significantly lower than in the negative group (p<0.05). The prevalence of rheumatoid factor and antinuclear factor were significantly higher in salivary SSB-positive pSS patients than in SSB-negative patients (p<0.05). CONCLUSIONS: Compared to parotid saliva, whole saliva is a more suitable diagnostic fluid. Using salivary anti-SSA/B antibodies as a single test item is insufficient given the relatively low sensitivity. Further studies should investigate the possibility of combining tests for different salivary autoantibodies as a method for diagnosing pSS.

[Repeated injection of mitoxantrone containing thermosensitive liposomes in rat induced ABC phenomenon].

To investigate whether accelerated blood clearance (ABC) phenomenon could be induced after repeated injection of mitoxantrone thermosensitive liposomes, LC-MS/MS and enzyme linked immunosorbent assay (ELISA) were used to measure the concentration of mitoxantrone and the anti-polyethylene glycol (PEG) IgM levels in rat plasma, separately. The drug was rapidly cleared away after the second administration. The anti-PEG IgM was detected after the first dose which was neutralized quickly after the second dose. It is proved that repeated administration of mitoxantrone thermosensitive liposomes in rat caused the ABC phenomenon.

[Novel cationic liposome loading siRNA inhibits the expression of hepatitis B virus HBx gene].

In order to solve the problem of selection and in vivo delivery problem in siRNA treatment, hepatitis B virus (HBV) HBx gene which could be targeted by siRNA was studied. The siRNA expression plasmid which specific inhibits HBx expression was obtained by in vitro selection via a dual-luciferase plasmid including HBx-Fluc fusion protein expression domain. The selected siRNA expression plasmid was then encapsulated in PEG-modified cationic liposome, which was devoted into pharmacodynamic studies at both cellular and animal level. The results illustrated that the cationic liposome which encapsulated siRNA expression plasmid could effectively inhibit HBx gene expression both in vitro and in vivo.

A preparation method for mRNA-LNPs with improved properties.

The properties of mRNA lipid nanoparticles (mRNA-LNPs), including size, empty particles, morphology, storage stability, and transfection potency, are critically dependent on the preparation methods. Here, a Two-step tangential-flow filtration (TFF) method was successfully employed to improve the properties of mRNA-LNPs during the preparation process. This method involves an additional ethanol removal step prior to the particle fusion process. Notably, this innovative approach has yielded mRNA-LNPs with larger particles, a reduced proportion of empty LNPs, optimized storage stability (at least 6 months at 2-8 °C), improved in vitro transfection efficiency, and minimized distribution in the heart and blood in vivo. In summary, this study represents the implementation of the innovative Two-step TFF method in the preparation of mRNA-LNPs. Our findings indicate substantial enhancements in the properties of our mRNA-LNPs, specifically with regard to the percentage of empty LNPs, stability, transfection efficiency, and in vivo distribution. These improvements have the potential to optimize their industrial applicability and expand their clinical use.

Sulfosalicylate mediates improved vinorelbine loading into LUVs and antineoplastic effects.

Liposomal vinorelbine formulation is desirable, as it might improve the therapeutic activity of vinorelbine. However, because of its lipophilic and membrane-permeable properties, vinorelbine is hard to be formulated into liposomes using conventional drug-loading technologies. To improve vinorelbine retention, ammonium salts of several anionic agents were employed to prepare liposomal vinorelbine formulations. It was found that 5-sulfosalicylate (5ssa) could form stable complexes with vinorelbine and stabilize entrapped vinorelbine. The resultant vesicles had an in vitro release t(1/2) of ~12.49 hours in NH(3)-containing media, which is longer than those of sulfate and phytate vesicles (~0.57 hours). The circulation half-life of vinorelbine after the injection of 5ssa vesicles into normal mice was ~13.01 hours, accounting for ~2-fold increase relative to that of sulfate vesicles. Improved drug retention correlated with enhanced antitumor efficacy. In the RM-1/c57 model, 5ssa vesicles were more efficacious than sulfate vesicles (P < 0.05). In RM-1/BDF1 and Lewis lung cancer/c57 models, antitumor efficacy was also considerably improved after vinorelbine encapsulation into 5ssa vesicles. For instance, in the RM/BDF1 model, liposomal vinorelbine was at least 4-fold more therapeutically active than free vinorelbine. Our results demonstrated that 5ssa could stabilize vinorelbine relative to other anions, resulting in the formulation with improved drug retention and efficacy. Improved vinorelbine retention might be associated with the formation of insoluble precipitate, which could be proved by precipitation study and decreased drug-release rate at a high D/L ratio.

Regulated bioanalysis of liposomal amphotericin B to support pharmacokinetic studies of liposomal drugs.

Background: Because of the delicate nature of liposomes, bioanalysis of free and liposomal-encapsulated drugs is among the most challenging assays to perform. Current regulatory guidance for bioanalysis is not sufficient to address the complexity of this particular formulation. Method & results: Three individual LC-MS/MS methods to quantify free amphotericin B (10-3000 ng/ml) and encapsulated amphotericin B (100-50,000 ng/ml) in pretreated human plasma and total amphotericin B (100-50,000 ng/ml) in human plasma were fully validated and applied to a bioequivalence study. The acceptance criteria and experimental design of additional validation tests using cross quality control were carefully deliberated a priori and included in the sample analysis as well. Discussion: Additional validation tests are necessary to demonstrate that the measured concentration of the intended component is accurate and free of interference from other coexisting components in the sample. These practices can be used as guidance for future liposomal drug method validation.

Increase of therapeutic activity of doxorubicin by long circulating liposomes in combination with curcumin.

In this study, doxorubicin (DOX)-loaded long circulating liposomes combined with curcumin (CUR) (DOX-CUR-LCLs) were successfully prepared as a novel formulation for cancer treatment. The particle size and distribution, zeta potential, drug loading capacity, and entrapment efficiency (EE) of the preparation were characterized. The in vitro anti-tumor activities of DOX-CUR-LCLs and DOX-LCLs against A549 cells were then evaluated and compared with that of free DOX. Cytotoxicity evaluation showed that DOX-CUR-LCLs had a significantly higher antitumor activity than other DOX preparations. These results suggest that novel DOX-CUR-LCLs, combination of DOX and CUR administered in long-circulating liposomes, could improve antitumor activity.

[Pharmacodynamics, pharmacokinetics and tissue distribution of liposomal mitoxantrone hydrochloride].

This study is to compare the pharmacodynamics, pharmacokinetics and tissue distribution of liposomal mitoxantrone (Mit-lipo) and free mitoxantrone (Mit-free). The antineoplastic effect of Mit-lipo was evaluated on PC-3 human xenograft tumor model after repeated intravenous injection at dose levels of 1, 2 and 4 mg x kg(-1). The pharmacokinetic study of Mit-lipo and Mit-free was performed on dogs following a single intravenous injection. The tissue distribution of Mit-lipo and Mit-free was observed on S-180 bearing mice after a single intravenous injection. (1) Pharmacodynamics: Mit-lipo dose-dependently inhibited PC-3 tumor growth at a dose ranging from 1 to 4 mg x kg(-1). The antitumor effect studies showed that Mit-lipo significantly improved the therapeutic effect in comparison with free drug. (2) Pharmacokinetics: in comparison with Mit-free, the AUC and t(1/2) values of Mit-lipo at the same dose level were higher than those of Mit-free in Beagle dogs. The results showed that Mit-lipo had long circulation characteristics. (3) Tissue distribution in S-180 bearing mice: compared to Mit-free, Mit-lipo preferentially accumulated into tumor zones instead of normal tissues. Tumor AUC in Mit-lipo treated animals was 8.7 fold higher than that in mice treated with the same dose of Mit-free. The Cmax values of Mit-lipo in heart, kidney, lung, spleen and intestinal tissue in Mit-lipo were 30.2%, 161.6%, 20.2%, 27.9% and 78.3% lower than those of Mit-free, respectively. The pharmacokinetics and tissue distribution of Mit-lipo changed obviously, thus increasing therapeutic effect and improving drug therapeutic index.

Direct quantitation of free, encapsulated, total doxorubicin and doxorubicinol in stabilized frozen human plasma to support a BE study of liposomal doxorubicin.

Regulatory guidance requires the quantification of encapsulated and free doxorubicin for a liposomal doxorubicin injection bioequivalence study. Due to the instability of liposome formulations in plasma samples, the release of free drug from the liposomal encapsulated doxorubicin during sample handling would result in elevation of measured free doxorubicin concentration. To prevent the potential release of free drug, stabilizer reagents and procedures were successfully developed and validated to adequately stabilize liposomal drugs in plasma samples during sample collection, storage and extraction. Three LC-MS/MS methods were developed and fully validated for direct quantitation of free, encapsulated and total doxorubicin concentrations in human plasma according to relevant regulatory guidance: Method 1: Quantitation of free doxorubicin and doxorubicinol at a linear range of 1-400 ng/mL and 0.5-10 ng/mL, respectively, from stabilizer treated plasma samples using solid phase extraction (SPE); Method 2: Quantitation of encapsulated doxorubicin at a linear range of 50-50,000 ng/mL from the stabilizer treated plasma sample using SPE followed by PPE extraction method; Method 3: Quantitation of total concentration of doxorubicin from untreated plasma samples at a linear range of 50-50,000 ng/mL using PPE. All three methods were successfully used to support a bioequivalence study between Caelyx® and Duomeisu® (Doxorubicin Hydrochloride Liposomal injection, generic doxorubicin formulation produced by CSPC). Incurred sample reanalysis (ISR) passing rate for total doxorubicin, free doxorubicin/doxorubicinol, and encapsulated doxorubicin methods were 100 %, 84.7 %/100 %, and 98.5 %, respectively. The measured total doxorubicin concentrations matched the sum of free and encapsulated doxorubicin concentrations.

Flexible CoFeB/Silk Films for Biocompatible RF/Microwave Applications.

Aiming to realize the integration of signal processing with the human body, wearable and implantable radio frequency (RF)/microwave devices are rapidly developed. However, the insufficiency in skin commonality and biocompatibility brings up challenges in making such devices. In this study, an ultra-flexible and biocompatible CoFeB/silk film is developed potentially for on-skin and implantable RF/microwave applications. Moreover, the CoFeB/silk films present controllable dissolvability in aqueous solutions and exhibit great potentials in applications for environmentally friendly disposable devices. A strain-tunable bandstop filter based on the CoFeB/silk film was fabricated, which exhibited a large frequency tunability of 3 GHz and ability in monitoring the finger-joints' motions. This concept and method of combining ferromagnetic materials with the biocompatible substrate offers a novel pathway for wearable/implantable applications.

Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis.

The concept of critical concentration (CC) is central to understanding the behavior of microtubules (MTs) and other cytoskeletal polymers. Traditionally, these polymers are understood to have one CC, measured in multiple ways and assumed to be the subunit concentration necessary for polymer assembly. However, this framework does not incorporate dynamic instability (DI), and there is work indicating that MTs have two CCs. We use our previously established simulations to confirm that MTs have (at least) two experimentally relevant CCs and to clarify the behavior of individuals and populations relative to the CCs. At free subunit concentrations above the lower CC (CCElongation), growth phases of individual filaments can occur transiently; above the higher CC (CCNetAssembly), the population's polymer mass will increase persistently. Our results demonstrate that most experimental CC measurements correspond to CCNetAssembly, meaning that "typical" DI occurs below the concentration traditionally considered necessary for polymer assembly. We report that [free tubulin] at steady state does not equal CCNetAssembly, but instead approaches CCNetAssembly asymptotically as [total tubulin] increases, and depends on the number of stable MT nucleation sites. We show that the degree of separation between CCElongation and CCNetAssembly depends on the rate of nucleotide hydrolysis. This clarified framework helps explain and unify many experimental observations.

[Entamoeba gingivalis infection among college students in Tangshan].

OBJECTIVE: To investigate the prevalence of Entamoeba gingivalis infection in college students in Tangshan, and analyze the relationship between the infection and human behaviors. METHODS: 551 students of grades 1-3 from six colleges in Tangshan received questionnairing, which covered the oral health state, teeth-brushing, xylitol gum-chewing, diet fondness, and smoking. Specimens were taken from the tooth surface of the lesion or fouling materials by using disinfected toothpicks and the smears were observed microscopically to examine Entamoeba gingivalis infection. RESULTS: The prevalence of Entamoeba gingivalis infection was 28.3% (156/551), 30.4% (55/181) and 24.6% in males and females (91/370) respectively (chi2=2.09, P>0.05). The prevalence in students with or without oral disorders was 41.2% (84/204) and 20.8% (72/347) respectively, with a significant statistical difference (chi2=26.41, P<0.01); it was 22.5% (53/236) and 32.7% (103/315) among students who cleaned their teeth regularly or irregularly (chi2=6.97, P<0.01); it was 18.3% (17/93) and 30.4% (139/458) among those usually with or without chewing xylitol gum (chi2=5.55, P<0.05). CONCLUSION: Entamoeba gingivalis infection is common in the college students in Tangshan and it has a close relation to the oral hygiene habits and the presence of oral disorders.

Rapid and mild fabrication of protein membrane coated capillary based on supramolecular assemble for chiral separation in capillary electrochromatography.

Exploration of the simple and stable coating methods is of great significance in capillary electrochromatography (CEC). In this work, a lysozyme assemble supramolecular membrane coated capillary column was developed for CEC chiral separation. Taking advantage of phase transformation of lysozyme, the coating process was achieved within 1.0 h thus to a large extent reduced the capillary preparation time and simplified the coating procedure. The successful fabrication of the supramolecular membrane coated capillary was verified by scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), fluorescence imaging, and electroosmotic flow (EOF). The separation capacity of the coated capillary was evaluated by analysis of different chiral analytes, including chiral amine drug and neurotransmitters, and good enantioseparation efficiency was achieved for the three pairs of enantiomers. For three consecutive runs, the relative standard deviations (RSD) for the migration time of the analytes for intra-day (n = 3), inter-day (n = 3) and column-to-column (n = 3) were in the range of 0.7-1.5%, 2.7-3.6%, and 4.5-5.8%, respectively. Additionally, the supramolecular membrane coated capillary column could run consecutively 100 times without observable change in the separation efficiency, proving the feasibility of the coating method based on the adhesion of the protein-based supramolecular membrane.

Polythiophene as a novel fiber coating for solid-phase microextraction.

The efficiency of polythiophene (PTh) was investigated as a new fiber for solid-phase microextraction (SPME). The PTh film was directly electrodeposited on the surface of a stainless steel wire in boron trifluoride diethyl etherate (BFEE) solution using cyclic voltammetry (CV) technique. PTh fibers were used for the extraction of some organochlorine pesticides (OCPs) from water samples. The extracted analytes were transferred to an injection port of gas chromatography using a laboratory-designed SPME device. The results obtained prove the ability of PTh material as a new fiber for sampling of organic compounds from water samples. This behavior is due most probably to the granulated surface of PTh film, which produces large surface areas. In this work, the optimum conditions for the preparation and conditioning of fibers and the extraction of analytes from water samples were obtained. In the optimum conditions, the limit of detection of the proposed method is 0.5-10 ng L(-1) for analysis of OCPs from aqueous samples, and the calibration graphs were linear in a concentration range of 10-10,000 ng L(-1) (R(2)>0.982) for most of organochlorine pesticides. Single fiber repeatability and fiber-to-fiber reproducibility were less than 12 and 18% (n=5), respectively. The PTh fiber was used to monitor the OCPs in real water samples, and the results compared favorably with the data determined by commercially available carbowax/divinylbenzene (CW/DVB) fiber.

Encapsulation of mitoxantrone into pegylated SUVs enhances its antineoplastic efficacy.

Mitoxantrone (MIT) was encapsulated into 60, 80 and 100nm pegylated hydrogenated soy phosphatidylcholine/cholesterol (HSPC/chol) vesicles using a transmembrane (NH(4))(2)SO(4) gradient. In-vitro release studies revealed that small-sized formulation had fast drug-release rate. Acute toxicity studies performed in c57 mice proved that all pegylated liposomal MIT (plm) formulations could be well-tolerated at a dose of 9mg/kg, significantly compared to severe toxicity induced by free mitoxantrone (f-M). In KM mice, plm60 was at least 2- to 3-fold less toxic than f-M. After intravenous injection, plm60 was slowly eliminated from plasma relative to f-M, resulting in about 6459-fold increase in AUC and its plasma kinetics exhibited dose dependence. In S-180 bearing KM mice, plm60 preferentially accumulated into tumor zone, with a approximately 12-fold increase in AUC and approximately 10-fold increase in C(max) Furthermore, the accumulation of plm60 in almost all normal tissues markedly decreased. The antitumor efficacy of plm60 was also considerably enhanced. In L1210 ascitic tumor model, plm60 was the most efficacious which led to a approximately 70% long-term survival, significantly compared to 16-33% survival rate in plm80, plm100 and f-M groups at the same dose level (4mg/kg). The antitumor efficacy of plm60 was more encouraging in L1210 liver metastasis model. At a dose of 6mg/kg, approximately 90% animals receiving plm60 treatment could survive 60 days; however, in f-M group at the same dose, all the mice died at approximately 14 days post inoculation. Similarly, plm60 could effectively inhibit the growth of RM-1 tumor in BDF1 mice, resulting in marked increase in tumor doubling time at different dose levels relative to f-M. The improved antineoplastic effects could be ascribed to its small vesicle size, which allowed more drug release after the accumulation into tumor zone. Theoretical considerations revealed that the reduction of vesicle size could increase the specific area of MIT/sulfate precipitate inside the vesicle and the release constant K, which is inversely proportional to vesicle volume (K=pA(m)k(2)k(2)(')/([H(+)](i)(2)V(i))).

Copper ion-mediated liposomal encapsulation of mitoxantrone: the role of anions in drug loading, retention and release.

Besides pH gradient, other transmembrane gradients such as metal ion gradient could be also employed to load drugs into liposomes. In pH gradient method, anions have an important role since they could form specific aggregates with drugs, and then affect drug release kinetics from vesicles. To explore the role of anions in metal ion gradient method, copper ion-mediated mitoxantrone (MIT) loading was investigated systematically. When empty liposomes exhibiting a transmembrane copper ion gradient (300 mM) were mixed with MIT in a molar ratio of 0.2:1, after 5 min incubation at 60 degrees C, >95% MIT could be loaded into vesicles and the encapsulation was stable, regardless of the kinds of anions and initial intraliposomal pH values. The encapsulation ratio decreased with increased MIT/lipid molar ratio. But even when the molar ratio increased to 0.4, >90% encapsulation could still be achieved. In the presence of nigericin and ammonium, the drug loading profiles were affected to different degree with respect to both drug loading rate and encapsulation ratio. Relative to CuSO(4)-containing systems, CuCl(2) mediated MIT loading was unstable. Both nigericin and ammonium could alter the absorption spectra of liposomal MITs loaded with CuSO(4) gradient. In vitro release studies were performed in glucose/histidine buffer and in 50% human plasma using a dialysis method. In both of release media, CuCl(2)-containing vesicles displayed rapid release kinetics in comparison with CuSO(4) systems; and during the experiment period, MIT was lost from the vesicles continuously. When the formulations were injected into BDF1 mice at a dose of 4 mg/kg, all the liposomal formulations exhibited enhanced blood circulation time, with half-life values of 6.8-7.2h, significantly compared to the rapid clearance of free-MIT. In L1210 ascitic model, CuCl(2) formulation was more therapeutically active than CuSO(4) formulation. At a dose of 6 mg/kg, the treatment with CuCl(2) formulation resulted in a median survival time of 21 days, considerably larger than that of CuSO(4) groups (15 days). Based on these data, it was concluded that during the drug loading process, a dynamic transmembrane pH gradient is generated and intraliposomal pH might affect the complexation manner in which Cu(2+) binds MIT. Owing to the presence of pH gradient, after the accumulation within vesicles, a part of MIT will be protonated and precipitated by sulfate. Accordingly, the aggregation status of MIT inside CuSO(4) system was more complicated than that in CuCl(2) vesicles. The difference in physical status of MIT aggregates affects not only the drug release rate, but also their therapeutic effects.