Druggability properties of a L309K mutation in the antibody CH2 domain.

In the early stages of antibody drug development, it is imperative to conduct a comprehensive assessment and enhancement of the druggability attributes of potential molecules by considering their fundamental physicochemical properties. This study specifically concentrates on the surface-exposed hydrophobic region of the candidate antibody aPDL1-WT and explores the effectiveness of the L309K mutation strategy. The resulting aPDL1-LK variant demonstrates a notable enhancement over the original antibody in addressing the issue of aggregation and formation of large molecular impurities under accelerated high-temperature conditions. The mutated molecule, aPDL1-LK, exhibits excellent physicochemical properties such as hydrophilicity, conformational stability, charge variant stability, post-translational modifications, and serum stability. In terms of biological function, aPDL1-LK maintains the same glycosylation pattern as the original antibody and shows no significant difference in affinity for antigen hPDL1 protein, CD16a-F158, CD64, CD32a-H131, and complement C1q, compared to aPDL1-WT. The L309K mutation results in an approximately twofold reduction in its affinity for CD16a-V158 and CD32a-R131. In vitro biological assays, including antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC), reveal that the L309K mutation may decrease CD16a-V158-mediated ADCC activity due to the mutation-induced decrease in ligand affinity, while not affect CD32a-R131-mediated ADCP activity. In conclusion, the L309K mutation offers a promising strategy to enhance the druggability properties of candidate antibodies.

The metabolism and hepatotoxicity of ginkgolic acid (17 : 1) in vitro.

Pharmacological activities and adverse side effects of ginkgolic acids (GAs), major components in extracts from the leaves and seed coats of Ginkgo biloba L, have been intensively studied. However, there are few reports on their hepatotoxicity. In the present study, the metabolism and hepatotoxicity of GA (17 : 1), one of the most abundant components of GAs, were investigated. Kinetic analysis indicated that human and rat liver microsomes shared similar metabolic characteristics of GA (17 : 1) in phase I and II metabolisms. The drug-metabolizing enzymes involved in GA (17 : 1) metabolism were human CYP1A2, CYP3A4, UGT1A6, UGT1A9, and UGT2B15, which were confirmed with an inhibition study of human liver microsomes and recombinant enzymes. The MTT assays indicated that the cytotoxicity of GA (17 : 1) in HepG2 cells occurred in a time- and dose-dependent manner. Further investigation showed that GA (17 : 1) had less cytotoxicity in primary rat hepatocytes than in HepG2 cells and that the toxicity was enhanced through CYP1A- and CYP3A-mediated metabolism.

Mechanism for ginkgolic acid (15 : 1)-induced MDCK cell necrosis: Mitochondria and lysosomes damages and cell cycle arrest.

Ginkgolic acids (GAs), primarily found in the leaves, nuts, and testa of ginkgo biloba, have been identified with suspected allergenic, genotoxic and cytotoxic properties. However, little information is available about GAs toxicity in kidneys and the underlying mechanism has not been thoroughly elucidated so far. Instead of GAs extract, the renal cytotoxicity of GA (15 : 1), which was isolated from the testa of Ginkgo biloba, was assessed in vitro by using MDCK cells. The action of GA (15 : 1) on cell viability was evaluated by the MTT and neutral red uptake assays. Compared with the control, the cytotoxicity of GA (15 : 1) on MDCK cells displayed a time- and dose-dependent manner, suggesting the cells mitochondria and lysosomes were damaged. It was confirmed that GA (15 : 1) resulted in the loss of cells mitochondrial trans-membrane potential (ΔΨm). In propidium iodide (PI) staining analysis, GA (15 : 1) induced cell cycle arrest at the G0/G1 and G2/M phases, influencing on the DNA synthesis and cell mitosis. Characteristics of necrotic cell death were observed in MDCK cells at the experimental conditions, as a result of DNA agarose gel electrophoresis and morphological observation of MDCK cells. In conclusion, these findings might provide useful information for a better understanding of the GA (15 : 1) induced renal toxicity.

Cyclosporin A affects the bioavailability of ginkgolic acids via inhibition of P-gp and BCRP.

Ginkgolic acids (GAs) in natural product Ginkgobiloba L. are the pharmacological active but also toxic components. Two compounds, GA (C15:1) and GA (C17:1) are the most abundant GAs. In this study, several in vitro and in vivo models were applied to investigate transport mechanism of GAs. A rapid and sensitive LC-MS/MS method for the simultaneous determination of GA (C15:1) and GA (C17:1) was applied to analyze the biological specimens. The Papp(AP→BL) values of GA (C15:1) and GA (C17:1) were 1.66-2.13×10(-)(6)cm/s and 1.34-1.85×10(-)(6)cm/s determined using MDCK and MDCK-MDR1 cell monolayers, respectively. The Papp(BL→AP) were remarkably greater in the MDCK-MDR1 cell line, which were 6.77-11.2×10(-)(6)cm/s for GA (C15:1) and 4.73-5.15×10(-)(6)cm/s for GA (C17:1). Similar results were obtained in LLC-PK1 and LLC-PK1-BCRP cell monolayers. The net efflux ratio of GA (C15:1) and GA (C17:1) in both cell models was greater than 2 and markedly reduced by the presence of Cyclosporin A (CsA) or GF120918, inhibitors of P-gp and BCRP, suggesting that GAs are P-gp and BCRP substrates. The results from a rat bioavailability study also showed that co-administrating CsA intravenously (20mg/kg) could significantly increase GA (C15:1) and GA (C17:1) AUC0-t by 1.46-fold and 1.53-fold and brain concentration levels of 1.43-fold and 1.51-fold, respectively, due to the inhibition of P-gp and BCRP efflux transporters by CsA.

[Establishment of reverse-phase high-performance liquid chromatography with chiral reagent derivatization for separation of fexofenadine enantiomers].

OBJECTIVE: To establish a precolumn chiral derivatization method for determination of fexofenadine enantiomers, a chiral substrate of OATP1B1, in cellular model. METHODS: R-(+)-phenylethyl isocyanate was selected as chiral derivatization reagent, which was reacted with fexofenadine to form carbamate derivatives. Enantiomers were identified by LC/MS and separated by RP-HPLC. RESULTS: Under the experimental conditions, the fexofenadine enantiomers were separated completely. The standard curve was linear over the concentration range of 25-100 ng/ml (R(2)=0.9992, 0.9989). Accuracy was 101.1% and 98.3%, intra-precision was 2.4% and 3.1%, inter-precision was 3.1% and 4.0% for D1 and D2, respectively. CONCLUSION: The method established is sensitive and accurate for determination of fexofenadine enantiomers in cells.

[Prevalence of occult hepatitis B virus infection and its phylogenetic features among mother-teenager pairs].

OBJECTIVE: Prevalence of occult hepatitis B virus (HBV) infection (OBI) was investigated in a paired mother-teenager population and HBV S gene variation including overt and occult HBV, was determined. METHODS: A follow-up study based on an initial survey of 135 mother-teenager pairs was carried out through collection of questionnaires and blood samples HBsAg were detected by ELISA method, viral load by PCR amplification and HBV S gene by phylogenetic analysis. RESULTS: 102 pairs of subjects were followed-up. Blood samples from 94 mothers and 101 children were collected. OBI prevalence in mothers was 10.0% (6/60), significantly higher than 2.0% (2/101) in teenagers. Medians of viral load were 399.9 IU/ml and 247.6 IU/ml in overt and occult HBV strains, but without significant difference. 1 occult HBV strain belonged to genotype B with serotype adw while the other 7 were genotype C with serotype adr. 15 of the overt HBV strains belonged to genotype B with serotype adw and the other 8 were genotype C with serotype adr. Proportions of genotype-C strains were significantly higher in occult HBV strains than in overt HBV strains. CONCLUSION: OBI was seen in teenage-mother population.

Hepatitis B virus surface antigen (HBsAg)-positive and HBsAg-negative hepatitis B virus infection among mother-teenager pairs 13 years after neonatal hepatitis B virus vaccination.

It is unclear whether a mother who is negative for hepatitis B virus surface antigen (HBsAg) but positive for hepatitis B virus (HBV) is at potential risk for mother-to-child transmission of HBV. This study, using a paired mother-teenager population, aimed to assess whether maternal HBsAg-negative HBV infection ((hn)HBI) is a significant source of child HBV infection (HBI). A follow-up study with blood collection has been conducted on the 93 mother-teenager pairs from the initial 135 pregnant woman-newborn pairs 13 years after neonatal HBV vaccination. Serological and viral markers of HBV have been tested, and phylogenetic analysis of HBV isolates has been done. The HBI prevalence was 1.9% (1 (hn)HBI/53) for teenage children of non-HBI mothers, compared with 16.7% (1 (hn)HBI/6) for those of (hn)HBI mothers and 2.9% (1 HBsAg-positive HBV infection [(hp)HBI]/34) for those of (hp)HBI mothers. Similar viral sequences have been found in one pair of whom both the mother and teenager have had (hn)HBI. In comparison with the (hp)HBI cases, those with (hn)HBI had a lower level of HBV load and a higher proportion of genotype-C strains, which were accompanied by differentiated mutations (Q129R, K141E, and Y161N) of the "a" determinant of the HBV surface gene. Our findings suggest that mother-to-teenager transmission of (hn)HBI can occur among those in the neonatal HBV vaccination program.

In vitro degradation of three-dimensional chitosan/apatite composite rods prepared via in situ precipitation.

Three-dimensional (3D) compact rods with multilayer structure made from chitosan (CHI) and apatite (Ap) have been prepared. The cytocompatibility assay revealed that the CHI/Ap composite could promote cell proliferation. In vitro degradation behaviors of the rods have been systematically investigated for up to 6 weeks in phosphate buffer saline (PBS) solution at 37°C. The properties of the composite rods were measured by means of weight loss, swelling ratio, and the changes in mechanical properties, etc. The pH of the PBS solution during the first 2 weeks of degradation was also detected. Results showed that the medium of CHI/Ap composite rods exhibited more stable pH change compared with that of CHI rods. Weight loss as well as the changes in mechanical properties happened more often to CHI rods than CHI/Ap rods. The presence of Ap could effectively reduce the degradation rate of the composite rods. All the results suggested that the composite rods could keep the initial shapes and mechanical properties longer than the pure CHI rods.

Fabrication of chitosan/hydroxylapatite composite rods with a layer-by-layer structure for fracture fixation.

A composite rod for fracture fixation using chitosan (CHI)/hydroxylapatite (HA) was prepared by means of in situ precipitation, which had a layer-by-layer structure, good mechanical properties, and cell compatibilities. The CHI/HA composite rods were precipitated from the chitosan solution with calcium and phosphorus precursors, followed by treatment with a tripolyphosphate-trisodium phosphate solution (pH >13) to crosslink the CHI and to hydrolyze the calcium phosphates to nanocrystalline HA. The results of FTIR, XRD, and TEM measurements confirmed that HA had been formed within the CHI matrix. The effects of the CHI/HA ratios (20/0, 20/1, 20/2, 20/4, and 20/5, w/w) on the mechanical properties were investigated. At the CHI/HA ratio of 20/4 (w/w), the bending strength and modulus of the rods were 133 MPa and 6.8 GPa, respectively. Pre-osteoblast MC3T3-E1 cells were cultured in an extract of the CHI/HA rods (20/4, w/w) to study the cell compatibilities of the composite. The observations indicated that the CHI/HA composite could promote the growth of MC3T3-E1 cells better than the composite without HA (p < 0.05). Furthermore, the co-cultivation of the cells and the CHI/HA composite showed that cells fully spread on the surface of the composite with an obvious cytoskeleton organization, which also revealed that the CHI/HA composite had a good biocompatibility.