Statistical and bioanalytical considerations for establishing a depletion criterion for specificity testing during immunogenicity assessment of a biotherapeutic

Immunogenicity assessment of fully human monoclonal antibody-based biotherapeutics requires sensitive and specific ligand binding assays. One of the components of specificity is the depletion of signal by a relevant biotherapeutic that is commonly based on an arbitrary depletion criterion of inhibition of the original response or reduction of the signal below the screening assay cut point (ACP). Hence, there is a need to develop a statistically derived physiologically relevant specificity criterion. We illustrate an optimization approach to determine the concentration of biotherapeutic required for the specificity evaluation. Naïve donor sample sets with and without circulating drug and antitherapeutic/drug antibody (ADA) were prepared. Next, a depletion cut point (DCP) using naïve and ADA-containing donor sets with the optimized biotherapeutic concentration was evaluated. A statistically derived design of experiment was used to establish a validated DCP. A reliable DCP requires naïve (no ADA) donors treated only with an optimized concentration of biotherapeutic. The additional DCPs generated using two distinct concentrations of ADA-spiked sample sets led to a physiologically irrelevant criterion that was not necessarily representative of real-time samples. This increased the risk of false positives or negatives. In this study, well-defined bioanalytical and statistical methods were employed to validate a DCP to confirm the presence of biotherapeutic specific ADA in human serum samples. A physiologically relevant and effective strategy to confirm specificity in immune reactive samples, especially those that are close to the ACP, is proposed through this study.

Somatometric measurements, and clinical chemistry and hematology parameters in Tibetan macaque (Macaca thibetana)

BACKGROUND

Limited physiological data for Tibetan macaques are available at present. This study will provide more rationale for evaluating this species.

METHODS

Thirty-seven Tibetan macaques (15 males and 22 females) were used in this study. Somatometric measurements, clinical chemistry and hematology parameters, insulin, and C-peptide were analyzed.

RESULTS

Females had higher values of waist and waist hip ratio (WHR) than males in somatometric measurements. There were no significant differences between the two genders in hematology. Significant differences between males and females were only found for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in biochemistry testing. In addition, females had higher fasting insulin and C-peptide than males. There was a strongly positive correlation between age and some somatometric parameters.

CONCLUSIONS

These physiological data will provide veterinarians and researchers with baseline values to evaluate experimental results using Tibetan macaques.

Structural and physiological characterization during wheat pericarp development

The cytological and physiological features of developing wheat pericarp were clearly characterized in this report. Our results may be helpful to articulate the functions of pericarp during the seed development. Although wheat pericarp has been well studied, knowledge of the sequence of events in the process of pericarp development is incomplete. In the present study, the structural development process of wheat (Triticum aestivum L.) pericarp was investigated in detail using resin microtomy and microscopy. Chlorophyll contents, and photosynthetic and respiratory rates, in pericarp were determined using spectrophotometer and an oxygen electrode, respectively. Mineral nutrient contents were also determined using scanning electron microscopy. The main results are as follows: (1) based on the structures and physiological characteristics observed, the developmental process of pericarp was divided into four stages, growth, formation, extinction and maturation stages, pericarp exhibited specific features at each stage. (2) Pericarp development differed in different parts, or varieties, of wheat. The dorsal pericarp had fewer starch grains and slower rates of apoptosis than the abdominal mesocarp. The cross cells in dorsal pericarp had an irregular outline. When compared with soft wheat cv. Yangmai 11, mesocarp cells in hard wheat cv. Xumai 30 had more starch grains, larger cell size and longer development duration. (3) The chlorophyll content, photosynthesis rate and respiratory rate in pericarp increased gradually, reaching a maximum about 16 days after anthesis, and later decreased continually. The photosynthetic rate in pericarp was lower than the respiration rate. (4) The contents of mineral elements in pericarp, such as calcium, zinc, iron and potassium were higher than those in the inner endosperm. The data indicate that wheat pericarp has many functions, e.g. protection, photosynthesis, mineral accumulation, synthesis and degradation of starch.

A tuberculosis outbreak among senior high school students in China in 2011

OBJECTIVE

An outbreak of pulmonary tuberculosis (PTB) occurred in students attending Licai Training School, Gujiao City, China, in early 2011. The epidemic characteristics and possible contributory factors relating to the spread of this outbreak of PTB were studied in a field investigation and are reported here.

METHODS

Cases were detected by PTB symptom screening, tuberculin skin testing (TST), chest X-radiography, and examination of sputum smears and cultures for all students, school staff and close family contacts of patients with PTB.

RESULTS

Of the 287 students attending the school, 45 (15.7%) were diagnosed with PTB and two (0.7%) had a positive smear. No PTB was found among staff and close family contacts. Prevalence was high in Science Class 27 and the two floors of the dormitory building where the smear-positive TB patients studied and lived. The frequency of strong TST positivity was also high in Science Class 27 and among close contacts living in the same dormitories as the PTB patients.

CONCLUSIONS

Several avoidable factors likely to have enhanced disease transmission were identified and several recommendations are made to reduce the risk of future TB outbreaks in schools.

A spheroid-based 3-D culture model for pancreatic cancer drug testing, using the acid phosphatase assay

Current therapy for pancreatic cancer is multimodal, involving surgery and chemotherapy. However, development of pancreatic cancer therapies requires a thorough evaluation of drug efficacy in vitro before animal testing and subsequent clinical trials. Compared to two-dimensional culture of cell monolayer, three-dimensional (3-D) models more closely mimic native tissues, since the tumor microenvironment established in 3-D models often plays a significant role in cancer progression and cellular responses to the drugs. Accumulating evidence has highlighted the benefits of 3-D in vitro models of various cancers. In the present study, we have developed a spheroid-based, 3-D culture of pancreatic cancer cell lines MIAPaCa-2 and PANC-1 for pancreatic drug testing, using the acid phosphatase assay. Drug efficacy testing showed that spheroids had much higher drug resistance than monolayers. This model, which is characteristically reproducible and easy and offers rapid handling, is the preferred choice for filling the gap between monolayer cell cultures and in vivo models in the process of drug development and testing for pancreatic cancer.

The in vitro study of ursolic acid and oleanolic acid inhibiting cariogenic microorganisms as well as biofilm

OBJECTIVE

The aim of this study was to examine the effect of ursolic acid (UA) and oleanolic acid (OA), triterpenoid compounds that are isolated from many edible and medicinal plants, on cariogenic microorganisms and biofilms.

METHODS

A microtitre plate dilution assay was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of UA and OA against two Actinomyces spp. and four Streptococcus spp. The antibacterial activity of UA and OA was assessed by crystal violet staining, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).

RESULTS

UA and OA displayed differential antibacterial activities against the six tested bacteria, with UA showing greater antibacterial activity than OA. Furthermore, the two drugs had greater antibacterial activity against Actinomyces spp. than Streptococcus spp. UA and OA at 1/4 MIC can reduce bacterial biofilm formation, whereas higher UA concentrations displayed antibacterial activity against Actinomyces viscosus and Streptococcus mutans in mature biofilms. For instance, 2.0 mg ml(-1) UA was sufficient to kill an A. viscosus biofilm.

CONCLUSIONS

UA and OA inhibit the growth of cariogenic microorganisms, which suggests that UA and OA have considerable potential as antibacterial agents for dental caries prevention.

Observation of a charged charmoniumlike structure in e+ e- → π+ π- J/ψ at sqrt[s] = 4.26 GeV

We study the process ee+ e- → π+ π- J/ψ at a center-of-mass energy of 4.260 GeV using a 525  pb(-1) data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9±1.9±3.7)  pb, consistent with the production of the Y(4260). We observe a structure at around 3.9  GeV/c2 in the π(±)J/ψ mass spectrum, which we refer to as the Z(c)(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the π(±)J/ψ invariant mass spectrum, neglecting interference, results in a mass of (3899.0±3.6±4.9)  MeV/c2 and a width of (46±10±20)  MeV. Its production ratio is measured to be R = (σ(e+ e- → π(±)Z(c)(3900)(∓) → π+ π- J/ψ)/σ(e+ e- → π+ π- J/ψ)) = (21.5±3.3±7.5)%. In all measurements the first errors are statistical and the second are systematic.

Identification and characterization of the major histocompatibility complex class II DQB (MhcMath-DQB1) alleles in Tibetan macaques (Macaca thibetana)

Tibetan macaque (Macaca thibetana), an endangered primate species endemic to China, have been used as experimental animal model for various human diseases. Major histocompatibility complex (MHC) genes play a crucial role in the susceptibility and/or resistance to many human diseases, but little is known about Tibetan macaques. To gain an insight into the MHC background and to facilitate the experimental use of Tibetan macaques, the second exon of Mhc-DQB1 gene was sequenced in a cohort of wild Tibetan macaques living in the Sichuan province of China. A total of 23 MhcMath-DQB1 alleles were identified for the first time, illustrating a marked allelic polymorphism at the DQB1 locus for these macaques. Most of the sequences (74%) observed in this study belong to DQB1*06 (9 alleles) and DQB1*18 (8 alleles) lineages, and the rest (26%) belong to DQB1*15 (3 alleles) and DQB1*17 (3 alleles) lineages. The most frequent alleles detected among these macaques were MhcMath-DQB1*15:02:02 (17.9%), followed by Math-DQB1*06:06, 17:03 and 18:01, which were detected in 9 (16.1%) of the monkeys, respectively. Non-synonymous substitutions occurred at a significantly higher frequency than synonymous substitutions in the peptide-binding region, suggesting balancing selection for maintaining polymorphisms at the MHC class II DQB1 locus. Phylogenetic analyses confirms the trans-species model of evolution of the Mhc-DQB1 genes in non-human primates, and in particular, the extensive allele sharing is observed between Tibetan and other macaque species.