A structured erythropoiesis model with nonlinear cell maturation velocity and hormone decay rate

We develop a quasilinear structured model that describes the regulation of erythropoiesis, the process in which red blood cells are developed. In our model, the maturation velocity of precursor cells is assumed to be a function of the erythropoietin hormone, and the decay rate of this hormone is assumed to be a function of the number of precursor cells, unlike other models which assume these parameters to be constants. Existence-uniqueness results are established and convergence of a finite difference approximation to the unique solution of the model is obtained. The finite difference scheme is then used to investigate the effects of these nonlinear parameters on the model dynamics. Our results show that a velocity of precursor cells maturation rate which is an increasing function of the hormone level and a decay rate of the hormone which is an increasing function of the number of precursor cells have a stabilizing effect on the dynamics of the model. While assuming that one parameter is a function and letting the other be a constant stabilizes the oscillations in the mature cells level, the effect is more significant when both parameters are taken to be functions. A study of robustness with respect to the forms of these functions and parameter sensitivity is also carried out.     

Genome Sequences of a Novel HIV-1 CRF53_01B Identified in Malaysia

A novel HIV-1 genotype designated CRF53_01B was recently characterized from three epidemiologically unrelated persons in Malaysia. Here we announced three recently isolated full-length genomes of CRF53_01B, which is likely to be phylogenetically linked to CRF33_01B, circulating widely in Southeast Asia. The genome sequences may contribute to HIV-1 molecular surveillance and future vaccine development in the region.     

Comparison of cytotoxic activities betweenin vitro and field grown plants ofTyphonium flagelliforme (Lodd.) blume

Anin vitro cytotoxicity screening of theTyphonium flagelliforme extracts indicated high cytotoxicity effect on human lung carcinoma NCl-H23 cells and human mammary gland carcinoma T-47D cells, but the extracts were not active on human liver carcinoma HepG2 cells. NCl-H23 cells were more susceptible toT. flagelliforme extracts than T-47D cells. EDP₅₀ values of the hexane fractions of the mature plant and thein vitro plantlet ofT. flagelliforme on NCl-H23 cells were less than 2 μg/mL Extract from the mature plant was relatively more cytotoxic than the one fromin vitro plantlet except for the hexane fraction. The chloroform and butanol fraction of the mature plant had higher cytotoxicity effect than the fraction fromin vitro plantlet on NCl-H23 cells. All the 3 fractions (hexane, chloroform, and butanol) of the mature plant exhibited higher cytotoxicity effects on human mammary gland carcinoma T-47D cells than the 3 fractions ofin vitro plantlet. However, the human liver carcinoma cells were resistant toT. flagelliforme extracts except for higher concentration of hexane fractions of both the mature and thein vitro plants and the chloroform fraction of the mature plant. Micropropagated plantlets ofT. flagelliforme could hence be used as herbal materials for the treatment of human lung and breast cancers.     

Variation of 423G>T in the Agouti Gene Exon 4 in Indigenous Chinese Goat Breeds

The Agouti gene plays an important role in pigment synthesis in domestic animals. A transversion of 423G>T recognized by BanII was found after a fragment (178 bp) of the goat Agouti gene exon 4 was amplified and sequenced. To investigate its genetic effect and diversity, 677 individuals from 12 indigenous Chinese goat breeds and one imported goat breed from South Africa (Boer goat) were analyzed by PCR-RFLP. Two alleles, T and G, and three genotypes, TT, TG, and GG, were detected. Allele T had a higher frequency in most goat breeds and, combined with the coat color phenotype, is believed to be responsible for the black phenotype or to be linked with the causative site in the goat. The results also indicate that the 423G>T transversion showed lower genetic diversity in goat breeds with black coat color in China. Genetic differentiation among the 13 goat populations was 0.2023. The clustering of populations based on the 423G>T site was basically consistent with the variation of coat color.     

Simultaneous determination of six penicillins in cows'' raw milk by a multiresidue high-performance liquid chromatographic method

A high-performance liquid chromatographic method based on C₁₈ solid-phase extraction and ultraviolet detection at 323 nm of analytes derivatized with benzoic anhydride and 1,2,4-triazole mercuric chloride solution was developed for the simultaneous determination of amoxicillin, penicillin G (benzylpenicillin), ampicillin, oxacillin, cloxacillin and dicloxacillin residues in raw milk. The detection limit of the method was 1.3 μg/l for penicillin G; 1.4 μg/l for amoxicillin, oxacillin and cloxacillin, 1.5 μg/l for ampicillin and 2.7 μg/l for dicloxacillin. The mean recovery was 95–102% for amoxicillin, penicillin G and ampicillin, 92–98% for oxacillin and cloxacillin and 87–94% for dicloxacillin, measured by using an internal standard. The relative repeatability standard deviation was 4–9% on level 4–15 μg/l, respectively, 2–7% on level 30–40 μg/l.     

Evolutionary History of HIV-1 Subtype B and CRF01_AE Transmission Clusters among Men Who Have Sex with Men (MSM) in Kuala Lumpur,Malaysia

HIV-1 epidemics among men who have sex with men (MSM) continue to expand in developed and developing countries. Although HIV infection in MSM is amongst the highest of the key affected populations in many countries in Southeast Asia, comprehensive molecular epidemiological study of HIV-1 among MSM remains inadequate in the region including in Malaysia. Here, we reported the phylodynamic profiles of HIV-1 genotypes circulating among MSM population in Kuala Lumpur, Malaysia. A total of n = 459 newly-diagnosed treatment-naïve consenting subjects were recruited between March 2006 and August 2012, of whom 87 (18.9%) were self-reported MSM. Transmitted drug resistance mutations were absent in these isolates. Cumulatively, phylogenetic reconstructions of the pro-rt gene (HXB2∶2253–3275) showed that HIV-1 subtype B and CRF01_AE were predominant and contributed to approximately 80% of the total HIV-1 infection among MSM. In addition to numerous unique transmission lineages within these genotypes, twelve monophyletic transmission clusters of different sizes (2–7 MSM sequences, supported by posterior probability value of 1) were identified in Malaysia. Bayesian coalescent analysis estimated that the divergence times for these clusters were mainly dated between 1995 and 2005 with four major transmission clusters radiating at least 12 years ago suggesting that active spread of multiple sub-epidemic clusters occurred during this period. The changes in effective population size of subtype B showed an exponential growth within 5 years between 1988 and 1993, while CRF01_AE lineage exhibited similar expansion between 1993 and 2003. Our study provides the first insight of the phylodynamic profile of HIV-1 subtype B and CRF01_AE circulating among MSM population in Kuala Lumpur, Malaysia, unravelling the importance of understanding transmission behaviours as well as evolutionary history of HIV-1 in assessing the risk of outbreak or epidemic expansion.     

中华眼镜蛇咬伤致局部组织损伤三种疗法的临床疗效观察

目的对中华眼镜蛇咬伤致局部组织损伤的各种治疗方法进行疗效优劣比较,找出最佳治疗方法。方法总结我院569例中华眼镜蛇咬伤致局部组织损伤的各种治疗方法。结果治疗方法从优到劣依次是：抗蛇毒血清局部注射-糜蛋白酶局部注射-蛇伤药酒外敷-坏死组织早期切除-局部烧灼法-局部组织切开冲洗。结论中华眼镜蛇伤致局部组织损伤的治疗方法应首选抗蛇毒血清局部注射和糜蛋白酶局部注射,其次选用蛇伤药酒外敷。