Global dynamics of an immunosuppressive infection model with stage structure.

In this paper, we propose an immunosuppressive infection model incorporating natural mortality of immune cells during the time lag needed for the expansion of immune cells. Starting from a stage structure model for the immune cells with various ages, we use the method of characteristic lines to derive a delay differential equation for the population of mature immune cells. Then, we use Lyapunov functional techniques to obtain the global dynamics of the model system. Specifically, we show that the virus dominant equilibrium is globally asymptotically stable when the delay is large. Next, we conduct local and global Hopf bifurcation analysis for the proposed model via Hopf bifurcation theory of delay differential equations. We choose the delay as a bifurcation parameter and examine the onset and termination of Hopf bifurcations of periodic solutions from the immune control equilibrium. We also prove that the model has only a finite number of Hopf bifurcation values, and the periodic solutions with specific oscillation frequencies occur only in bounded delay intervals. Under some technical conditions, we show that two global Hopf branches bifurcated from different Hopf bifurcation values may connect to each other and thus be bounded. However, unlike the global Hopf bifurcation results in the existing literature, the Hopf branches for our model system are not necessarily bounded, though the delay components are always bounded. Numerical simulation suggests that bounded and unbounded Hopf branches may co-exist in the bifurcation diagram. Moreover, we observe a new interesting phenomenon that a global Hopf branch may have uniformly bounded periodic solutions, bounded delays, but unbounded periods.

Viral infection dynamics in a spatial heterogeneous environment with cell-free and cell-to-cell transmissions.

In this paper, we investigate a diffusive viral infection model in a spatial heterogeneous environment with two types of infection mechanisms and distinct dispersal rates for the susceptible and infected target cells. After establishing well-posedness of the model system, we identify the basic reproduction number R0 and explore the properties of R0 when the dispersal rate for infected target cells varies from zero to infinity. Moreover, we demonstrate that the basic reproduction number is a threshold parameter: the infection and virus will be cleared out if R0 ≤ 1, while if R0 > 1, the infection will persist and the model system admits at least one positive (chronic infection) steady state. For the special case when all model parameters are spatial homogeneous, this chronic infection steady state is unique and globally asymptotically stable.

Mitochondrial DNA variations in tongue squamous cell carcinoma.

Tongue squamous cell carcinoma (TSCC) is the most common type of oral carcinoma. Mitochondrial DNA (mtDNA) is a circular DNA molecule of 16,569 bp, which functionally encompasses a regulatory non-coding region (D-loop) and 37 encoding genes that correspond to 13 subunits of respiratory chain complexes (I, III, IV and V), 22 transfer RNAs and 2 ribosomal (r)RNAs. Recently, mtDNA has been implicated as a mutation hotspot in various tumors. However, to our knowledge mtDNA alteration in TSCC has not been investigated to date. In the present study, the mitochondrial genomes of tongue carcinoma, adjacent non-cancerous tissue and peripheral blood samples from 8 patients with TSCC were sequenced and aligned with the revised Cambridge Reference Sequence. Overall, only one synonymous mutation, which mapped to the NADH:ubiquinone oxidoreductase core subunit 5 gene, was observed in the tongue carcinoma sample from a single patient. A further 21 polymorphisms were identified, including six in the non-coding region (D-loop), five in Complex I, three in Complex III, two in Complex IV, two in Complex V and three in rRNA. In addition, mitochondrial microsatellite instability (mtMSI) was detected in 2/8 tongue carcinoma samples, and localized in the D310 region. These variations, particularly the polymorphisms and mtMSI, imply that the mitochondrial genome may be a hotspot of genome alteration in tongue cancer. Further investigation is expected to reveal the role of mtDNA alteration in TSCC development, as well as its clinical implications.

Maternal genetic backgrounds contribute to the genetic susceptibility of tongue cancer patients in Hunan, central of China.

Mitochondrial DNA (mtDNA) mutations played crucial roles on affecting the susceptibility to cancer. In this study, to investigate whether mitochondrial DNA mutations contributed to the genetic susceptibility of Chinese tongue cancer patients, mtDNA control regions of 105 Chinese tongue cancer patients were amplified and sequenced, the mutations were recorded by comparing with the revised Cambridge Reference Sequence (rCRS), which were attributed to certain mtDNA haplogroups based on the specific variations motif of each patients. The Miao Chinese group (a Chinese ethnic minority) from surrounding region has no essential difference with tongue cancer group, which was taken as the matched control group with principal component analysis by taking the haplogroups frequency of 105 tongue cancer individuals and 354 healthy individuals of eight groups from the similar geographic regions as input factors. This was supported by the smallest genetic distance between tongue cancer and Miao_2 groups. Further, the statistical analysis based on mtDNA variations of hypervariable sequence I (HVSI) indicated that 13 variations including 16,124, 16,148, 16,182C, 16,183C, 16,227, 16,266A, 16,249, 16,272, 16,291, 16,327, 16,335, 16,497, and 16,519 have significant differences between tongue cancer group and matched control group. Comparison of mtDNA haplogroups between tongue cancer and control groups indicated that mtDNA haplogroups C, F2*, and M10 have significant differences. It's worth noting that 16,327 and 16,291 was the defining variation of haplogroups C and F2*, respectively. Our results suggested that mitochondrial DNA may play a crucial role for the maternal genetic susceptibility of tongue cancer patients from Hunan, central of China.

c.464A>G variation in the GJB2 gene is detected in a Han Chinese family.

We report two heterozygous carriers of c.464A>G variation in the GJB2 gene in a Chinese pedigree. The proband with hearing loss most likely inherited the c.464A>G variation from his mother who also carries heterozygous c.79G>A variation and has normal hearing. The pathological significance of c.464A>G variation remains to be determined.

[Research on discrimination method of vinegar varieties and brands based on the content of inorganic elements].

Classification of brands and quality of food products is a very active area with the application of chemometric classification procedures. The content of inorganic elements such as Mg, K, Pb, Zn, Fe, Mn, Ca and Cu in 32 vinegar samples was determined by atomic absorption spectrophotometer. The similarity of Chencu and Baicu as well as different brands of vinegar samples of the same kind was calculated by vector similarity analysis. The characteristic discrimination of vinegar samples of four brands from Beijing, Jiangxi, Jiangsu and Shanxi was accomplished through cluster analysis and principal component analysis, and the classification of different kinds of vinegar samples (Chencu and Baicu) was performed as well. Vinegar samples were divided into two main groups by cluster analysis and principal component analysis. Each main group was discriminated according to different brands. The contents of inorganic elements in vinegar were good chemical descriptors for differentiation of their kinds and brands.