A two-age-classes dengue transmission model

In this paper, we discuss a two-age-classes dengue transmission model with vaccination. The reason to divide the human population into two age classes is for practical purpose, as vaccination is usually concentrated in one age class. We assume that a constant rate of individuals in the child-class is vaccinated. We analyze a threshold number which is equivalent to the basic reproduction number. If there is an undeliberate vaccination to infectious children, which worsens their condition as the time span of being infectious increases, then paradoxically, vaccination can be counter productive. The paradox, stating that vaccination makes the basic reproduction number even bigger, can occur if the worsening effect is greater than a certain threshold, a function of the human demographic and epidemiological parameters, which is independent of the level of vaccination. However, if the worsening effect is to increase virulence so that one will develop symptoms, then the vaccination is always productive. In both situations, screening should take place before vaccination. In general, the presence of class division has obscured the known rule of thumb for vaccination.     

一类具饱和传染力和常数输入的SIRS脉冲接种模型研究

利用Floquet乘子理论,研究了一类具饱和传染力和常数输入的SIRS脉冲接种模型,得到了无病周期解全局渐近稳定和系统持久的充分条件.     

急性心肌梗死患者冠状动脉病变严重性与脉压和脉压指数的关系

目的:探讨急性心肌梗死(AMI)患者冠状动脉病变严重程度与脉压和脉压指数的关系.方法:对185例AMI患者进行冠状动脉造影术,冠状动脉病变严重程度用冠状动脉病变支数和Gensini积分来表示,并测定收缩压(SBP)和舒张压(DBP)并计算脉压(PP)及脉压指数(PPI).结果:与脉压＜65mmHg的患者相比,脉压≥65mmHg的患者冠状动脉3支血管病变的患病率和Gensini积分显著增高(P＜0.01).与PPI＜0.500的患者相比,PPI≥0.500的患者冠状动脉3支血管病变的患病率和Gensini积分亦显著增高(P＜0.01).结论:PP和PPI与AMI患者冠状动脉病变程度密切相关,在临床上具有指导作用.     

Brucellosis in India — a review

Brucellosis is an important re-emerging zoonosis with a worldwide distribution. It is still an uncontrolled serious public health problem in many developing countries including India. Brucellosis in India is yet a very common but often neglected disease. Currently, Brucella melitensis accounts for most recorded cases globally with cattle emerging as a important reservoir with the few cases of B. suis. Isolated cases of non-terrestrial brucellosis and continuing transmission from wild animals have raised important epidemiological issues. Routine serological surveillance along with high clinical suspicion and screening of family members of index cases would be essential in delineating the real magnitude of human brucellosis in endemic countries. Increased business and leisure travel to endemic countries have led to diagnostic challenge in non-endemic areas. Laboratory testing is indispensable for diagnosis. Advances in newer rapid, sensitive, and specific testing methodologies and alternate treatment strategies are urgently needed. A safe and effective vaccine in human is not yet available. Prevention is dependent upon increasing public awareness through health education programmes and safe livestock practices. Active co-operation between health and veterinary services should be promoted. This review collates world literature and its impact to the discovery, isolation and diagnosis and epidemiology along with the control measures adapted in the Indian scenario.     

Role of various growth media on shinorine (mycosporine-like amino acid) concentration and photosynthetic yield in <Emphasis Type="Italic">Anabaena variabilis</Emphasis> PCC 7937

The induction of shinorine (mycosporine-like amino acid (MAA)) in Anabaena variabilis PCC 7937 was studied in various culture media (BGA⁻, BGA⁺, BG11 and Allen and Arnon’s). The objective was to select the most appropriate medium that can support the highest induction of MAAs and can be used for industrial production of these UV protective substances from cyanobacteria. Also, in vivo photosynthetic activity was measured under shinorine inducing conditions in all media. The shinorine content and photosynthetic activity (yield) were highest (2948.73 ± 61.13 nmol/g dry wt and 0.47 ± 0.01, respectively) in BG11 medium in comparison to others after 72 h of UV radiation. After the same duration of irradiation shinorine content was 1076.08 ± 21.77, 1320.07 ± 98.19 and 554.64 ± 16.47 nmol/g dry wt in BGA⁻, BGA⁺, and Allen and Arnon’s media, respectively. Thus, BG11 medium can be used for mass production of MAAs from cyanobacteria.     

Optimum storage conditions for product of transiently expressed epitopes of <Emphasis Type="Italic">Human papillomavirus</Emphasis> using <Emphasis Type="Italic">Potato virus X</Emphasis>-based vector

We describe the optimized storage conditions of recombinant Potato virus A coat protein (ACP) carrying two different epitopes from Human papillomavirus type 16 (HPV-16). Epitope derived from minor capsid protein L2 was expressed as N-terminal fusion with ACP while an epitope derived from E7 oncoprotein was fused to its C-termini. The construct was cloned into Potato X potexvirus (PVX) based vector and transiently expressed in plants using Agrobacterium tumefaciens mediated inoculation. The effect of storage conditions on the serological activity of L2ACPE7 was studied by ELISA using IgG anti PVX, PVA and L2. Purified L2ACPE7 stored freeze-dried (at −20 °C), frozen at various temperatures (−20 °C, −70 °C) and at +4 °C were tested. Purified L2ACPE7 was most stable as lyophilized material stored at −20 °C. Our study demonstrates suitable way for the storage of plant material containing foreign viral epitopes for the purposes of edible vaccination.     

Increased incidence of pertussis and parapertussis in HIV-1-positive adolescents vaccinated previously with whole-cell pertussis vaccine

We investigated 296 adolescents (11–18 years), who had been immunized previously with the three doses of DPT vaccines. 48 were diagnosed positive for HIV-1. Nasopharyngeal swabs were obtained from 296 adolescents who presented with persistent cough and nasopharyngeal secretions. Nasopharyngeal swabs (calcium alginate) specimens were collected by passing the swabs through the nares into the posterior nasopharynx and rotating the swabs for a few seconds. The swabs were plated for culture of Bordetella organisms in charcoal cephalexin blood agar (CCBA). The CCBA plates were incubated for 2–6 days at 35 °C in a humid aerobic atmosphere. The suspected, shiny (mercury-like) colonies were tested by slide agglutination with antisera to B. pertussis and B. parapertussis, and urease, oxidase activities were performed. Results indicate that out of 48 HIV-1-positive adolescents, 18 had positive cultures for Bordetella organisms (14, Bordetella pertussis, and 4, Bordetella parapertussis). Of 248 HIV-1-negative subjects, 3 had Bordetella organisms (2, Bordetella pertussis, 1, Bordetella bronchiseptica). One of the subjects, a boy, aged 14 years, with Bordetella bronchiseptica had a dog as pet, which was found to be infected. The results indicate that adolescents with HIV-1 infection, despite being vaccinated against pertussis have a higher rate of infection when exposed to pertussis bacteria than HIV-1-negative adolescents. This revised version was published online in August 2006 with corrections to the Cover Date.     

Oxidation of thiocyanate by iron(V) in alkaline medium

The oxidation of thiocyanate by iron(V) (Fe(V)) was studied as a function of pH in alkaline solutions by a premix pulse radiolysis technique. The rates decrease with an increase in pH. The rate law for the oxidation of SCN⁻ by Fe(V) was obtained as −d[Fe(V)]/dt = k₁₀{[H⁺]²/([H⁺]² + K₂[H⁺] + K₂K₃)}[Fe(V)][SCN⁻], where k₁₀ = 5.72 ± 0.19 × 10⁶ M⁻¹ s⁻¹, pK₂ = 7.2, and pK₃ = 10.1. The reaction precedes via a two-electron oxidation, which converts Fe(V) to Fe(III). Thiocyanate reacts approximately 10³× faster with iron(V) than does with iron(VI).     

Pulse ENDOR and density functional theory on the peridinin triplet state involved in the photo-protective mechanism in the peridinin-chlorophyll a-protein from Amphidinium carterae

The photoexcited triplet state of the carotenoid peridinin in the Peridinin-chlorophyll a-protein of the dinoflagellate Amphidinium carterae has been investigated by pulse EPR and pulse ENDOR spectroscopies at variable temperatures. This is the first time that the ENDOR spectra of a carotenoid triplet in a naturally occurring light-harvesting complex, populated by energy transfer from the chlorophyll a triplet state, have been reported. From the electron spin echo experiments we have obtained the information on the electron spin polarization dynamics and from Mims ENDOR experiments we have derived the triplet state hyperfine couplings of the α- and β-protons of the peridinin conjugated chain. Assignments of β-protons belonging to two different methyl groups, with a_iso = 7.0 MHz and a_iso = 10.6 MHz respectively, have been made by comparison with the values predicted from density functional theory. Calculations provide a complete picture of the triplet spin density on the peridinin molecule, showing that the triplet spins are delocalized over the whole π-conjugated system with an alternate pattern, which is lost in the central region of the polyene chain. The ENDOR investigation strongly supports the hypothesis of localization of the triplet state on one peridinin in each subcluster of the PCP complex, as proposed in [Di Valentin et al. Biochim. Biophys. Acta 1777 (2008) 186-195]. High spin density has been found specifically at the carbon atom at position 12 (see Fig. 1B), which for the peridinin involved in the photo-protective mechanism is in close contact with the water ligand to the chlorophyll a pigment. We suggest that this ligated water molecule, placed at the interface between the chlorophyll-peridinin pair, is functioning as a bridge in the triplet-triplet energy transfer between the two pigments.     

GABA能抑制调制大棕蝠下丘听神经元时间编码模式

大棕幅（Eptesicus fuscus）下丘神经元对重复率为10pps(pulse per second）、30pps的串声刺激均产生跟随反应,但对90pps串声刺激的跟随反应则不尽相同,微电泳bicuculline阻断GABA能抑制作用后,所记录的58个神经元中,有13个（22％）放电率及串声刺激反应模式无;45个（78％）神经元放电率有不同程度的增加。对10pps、30pps串声刺激仍能产生跟随反应,但对90pps串声刺激的跟随反应模式有多种变化。其中：17个（29％）神经元为放电率增加的跟随反应;9个（15％）神经元放电率增加,对前100ms的串刺激产生反应且放电密集,而对随后200ms的串刺激只产生少量的放电;15个（26％）神经元放电率增加,在前几十毫秒范围内有较多的放电反应,后续的反应很弱;4个（7％）神经元只对第一个声刺激产生反应,且放电率增加,随后放电急剧减少。结果提示中脑下丘神经元对听觉信息的时间编码可能具有更复杂的机理。