Silencing of Odorant-Binding Protein Gene OBP3 Using RNA Interference Reduced Virus Transmission of Tomato Chlorosis Virus.

Tomato chlorosis virus (ToCV) is widespread, seriously impacting tomato production throughout the world. ToCV is semi-persistently transmitted by Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Currently, insect olfaction is being studied to develop novel pest control technologies to effectively control B. tabaci and whitefly-borne virus diseases. Despite current research efforts, no report has been published on the role of odorant-binding proteins (OBPs) in insect preference under the influence of plant virus. Our previous research showed that viruliferous B. tabaci preferred healthy plants at 48 h after virus acquisition. In this study, we determined the effect of OBPs on the host preference interactions of ToCV and whiteflies. Our results show that with the increase in acquisition time, the OBP gene expressions changed differently, and the OBP3 gene expression showed a trend of first rising and then falling, and reached the maximum at 48 h. These results indicate that OBP3 may participate in the host preference of viruliferous whiteflies to healthy plants. When the expression of the OBP3 gene was knocked down by an RNA interference (RNAi) technique, viruliferous Mediterranean (MED) showed no preference and the ToCV transmission rate was reduced by 83.3%. We conclude that OBP3 is involved in the detection of plant volatiles by viruliferous MED. Our results provide a theoretical basis and technical support for clarifying the transmission mechanism of ToCV by B. tabaci and could provide new avenues for controlling this plant virus and its vectors.

Arginine Vasopressin-Aquaporin-2 Pathway-Mediated Dehydration Effects of Electroacupuncture in Guinea Pig Model of AVP-Induced Eendolymphatic Hydrops.

OBJECTIVE: To investigate the effects of electroacupuncture (EA) on endolymphatic hydrops (EH) and the regulation of arginine vasopressin (AVP)-aquaporin-2 (AQP2) pathway in guinea pigs. METHODS: EH was induced in male guinea pigs by an intraperitoneal injection of AVP. For the treatment, EA was delivered to Baihui (GV 20) and Tinggong (SI 19) acupoints, once per day for 10 consecutive days. In histomorphological studies, cochlear hydrops degree was evaluated by hematoxylin-eosin (HE) staining, and then the ratio of scala media (SM) area to SM + scala vestibuli (SV) area (R value) was calculated. In mechanical studies, a comparison of plasma AVP (p-AVP) concentrations, cyclic adenosine monophosphate (cAMP) levels, vasopressin type 2 receptor (V2R) and AQP2 mRNA expressions in the cochlea were compared among groups. RESULTS: EA significantly reduced cochlear hydrops in guinea pigs (P=0.001). EA significantly attenuated the AVPinduced up-regulation of p-AVP concentrations (P=0.006), cochlear cAMP levels (P=0.003) and AQP2 mRNA expression (P=0.016), and up-regulated the expression of V2R mRNA (P=0.004) in the cochlea. CONCLUSIONS: The dehydrating effect of EA might be associated with its inhibition of AVP-AQP2 pathway activation.

Monitoring of malaria vectors at the China-Myanmar border while approaching malaria elimination.

BACKGROUND: Tengchong County was one of the counties located at the China-Myanmar border with high malaria incidence in the previous decades. As the pilot county for malaria elimination at the border area, Tengchong County is aiming to be the first county to achieve malaria elimination goal. A cross-sectional entomological survey was carried out to evaluate the feasibility of elimination approach and assess the receptivity of malaria reintroduction. METHODS: Light traps associated with live baits were used to investigate the abundance of adult mosquitoes in nine villages in Tengchong County. Light traps were set to collect adult mosquitoes in both human houses and cowsheds from dusk till dawn in each site. RESULTS: A total of 4948 adult Anopheles mosquitoes were collected from May to December in two villages. Of the mosquitoes were captured, 24.2% were in human houses and 75.8% in cowsheds. The peak of abundance occurred in July for An. sinensis and in September-October for An. minimus (s.l.) Ten Anopheles species were collected, the most prevalent being An. sinensis (50.3%), An. peditaeniatus (31.6%) and An. minimus (s.l.) (15.8%), contributing to 97.6% of the sample. Potential breeding sites were also investigated and a total of 407 larvae were collected, with An. sinensis (50.1%) and An. minimus (s.l.) (46.2%) as predominant species. Ponds and rice fields were the two preferred breeding sites for Anopheles mosquitoes; however, the difference between the number of adults and larvae captured suggest other breeding sites might exist. Both An. sinensis and An. minimus (s.l.) were found zoophilic with human blood index as 0.21 and 0.26, respectively. No Plasmodium positive Anopheles specimens were found by PCR among 4,000 trapped mosquitoes. CONCLUSIONS: Although no indigenous malaria cases have been reported in Tengchong County since 2013, there is still a risk from the presence of vectors in the context of human population movements from neighboring malaria endemic areas. The presence of An. sinensis, associated to rice fields, is particularly worrying. Sustained entomological surveillance is strongly suggested even after malaria elimination certification.

Complex Neural Network Models for Time-Varying Drazin Inverse.

Two complex Zhang neural network (ZNN) models for computing the Drazin inverse of arbitrary time-varying complex square matrix are presented. The design of these neural networks is based on corresponding matrix-valued error functions arising from the limit representations of the Drazin inverse. Two types of activation functions, appropriate for handling complex matrices, are exploited to develop each of these networks. Theoretical results of convergence analysis are presented to show the desirable properties of the proposed complex-valued ZNN models. Numerical results further demonstrate the effectiveness of the proposed models.

[Identification of mammalian blood meals in anopheline mosquitoes from four counties of Yunnan Province by multiple PCR].

From June to August 2012, the blood-sucking mosquitoes were captured around cattle-sheds and human houses in Yuanjiang County, Qiaojia County, Yongshan County, and Jinghong City of Yunan Province. Blood samples from mosquitoes were collected on filter paper. Multiplex PCR assay was used to detect the blood meal samples. Among the 145 mosquitoes captured, 123 were Anopheles sinensis (84.8%) and 22 A. minimus (15.2%). Among the blood samples, corresponding bands were amplified in 134 samples. The result showed that the blood meals were from pigs (n = 104), cows (n = 22), dogs (n = 4), human (n=2), cow and pig (n = 1), pig and human (n = 1). Human blood index of A. sinensis and A. minimus was 0.018 and 0.045, respectively.

[Investigation of prevalence of soil-transmitted nematode infections among Lahu Ethnic residents in Xiaojie Township, Jinghong City, Yunnan Province].

OBJECTIVE: To understand the prevalence of human intestinal parasite infections in Lahu Ethnic residents so as to provide the evidence for effective control. METHODS: The prevalence of soil-transmitted nematode infections in local people was determined by Kato-Katz technique and individual sanitary behaviors and habits were requested by a standardized questionnaire in 3 villages of Xiaojie Township, Jinghong City, Yunnan Province. The relationship between intestinal parasite infections and behavioral characteristics was analyzed. RESULTS: Of 289 subjects, 255 individuals were infected with soil-transmitted nematodes; the prevalence was 88.24%. Among the infected individuals, 210 were found infected with hookworm and the infection rate was 72.66%; 154 subjects were infected with Ascaris lumbricoides and the infection rate was 53.29%; 13 were infected with Trichuris trichura, and the infection rate was 4.50%; 16 were infected with other parasites and the infection rate was 5.54%. The percentages of people with light infection of hookworm, A. lumbricoides and T. trichura were 90.48%, 97.40% and 100%, respectively. CONCLUSIONS: There is high prevalence of soil-transmitted nematode infections in Lahu Ethnic residents in Jinghong City, but the infection intensity was generally low. The control and monitoring of soil-transmitted parasite infections should be strengthened in this area.

[Serological survey of Toxoplasma gondii infection in some areas of Pu' er City].

OBJECTIVE: To understand the status of Toxoplasma gondii infection in the population of Pu'er City, so as to provide the evidence for formulating the strategy of toxoplasmosis control. METHODS: The population from Jingdong, Jinggu, and Menglian counties in Pu' er City was surveyed; IgG of T. gondii in serum was detected by ELISA. RESULTS: Totally 906 resident serum samples were detected and the IgG positive rate was 24.2%. The positive rates were higher in the aged groups of 30-39 years and 60-69 years, and the difference among different aged groups was significant (Χ2 = 17.77, P < 0.01). There were no significant differences between different sexualities, and among different educational levels and living habits (P > 0.05). The positive rates were 26.6% (194/730), 15.5% (22/142), and 8.8% (3/34) in farmers, students and other occupations, respectively, and there was a significant difference among them (Χ2 = 12.51, P < 0.01). The positive rates were 23.3% (198/849)and 36.8% (21/57) in the farmers who had the habit of rearing pigs in pens and the farmers who had the habit of free ranging pigs, respectively, and there was a significant difference between them (Χ2 = 5.33, P < 0.05). CONCLUSION: The IgG positive rate of T. gondii is very high in Pu'er City, and therefore, the health education for toxoplasmosis control should be strengthened.

[Effect of aspirin plus clopidogrel therapy on aspirin resistance after off-pump coronary artery bypass surgery].

OBJECTIVE: To investigate the effect of the anti-platelet effect of aspirin plus clopidogrel on off-pump coronary artery bypass (OPCAB) grafting and the possible side effects of such therapy. METHODS: Sixty patients who underwent standard OPCAB were randomized immediately after surgery in two groups: the aspirin alone group of 30 patients who received aspirin (100 mg) daily; and the combination group of 30 patients who received clopidogrel (75 mg) plus aspirin (100 mg) daily. Platelet aggregation in response to arachidonic acid (PLAA) and adenosine diphosphate (PLADP) were measured at baseline (before surgery) and 1-6, 8, and 10 days after the medication. Postoperative bleeding and other perioperative parameters were compared between these two groups. RESULTS: There were no significant differences between the two groups in perioperative findings including average number of distal anastomosis, operative time, postoperative bleeding, ventilation time, and intensive care unit stay (all P>0.05). The proportion of patients with the PLAA above 20% value was significantly lower in the combination group than those in the aspirin alone group (32.1% vs 62.1%, P<0.05). PLAA of two groups one and two days after taking aspirin or plus clopidogrel were (24.2±31.9)% vs. (49.6±32.6)% and (13.8±27.2)% vs. (37.6±37.4)%, respectively (P<0.05). No obvious postoperative complication was noted in both groups. Multivariate analysis showed that clopidogrel administration was independently correlated with aspirin resistance (P=0.044, OR = 0.09;95% CI=0.07-0.48). CONCLUSION: Early combined use of aspirin plus clopidogrel after OPCAB can remarkably reduce OPCAB-related aspirin resistance and enjoy similar safety.

[Pollution characteristics and health risk assessment of atmospheric VOCs in the downtown area of Guangzhou, China].

The measurements of 31 kinds of VOCs in the ambient air of a site were carried out in the downtown of Guangzhou by online method from November 5, 2009 to November 9, 2009. The ambient level and composition characteristics, temporal variation characteristics, sources identification, and chemical reactivity of VOCs were studied, and the health risk of VOCs in the ambient air in the study area was assessed by using the international recognized health risk assessment method. Results showed that the mean and the range of the mass concentrations of 31 VOCs were 114.51 microg x m(-3) and 29.42-546.06 microg x m(-3), respectively. The mass concentrations of 31 VOCs, and those of alkanes, alkenes, and aromatics all showed a changing trend of higher in the morning and in the evening, and lower at noontime. Vehicular exhaust, gasoline and liquefied petroleum gas evaporates were the main sources of VOCs with the volatilization of paints and solvents being important emission sources. Toluene, trans-2-butene, m/p-xylene, i-butane, and 1,3,5-trimethylbenzene were the key reactive species among the 31 VOCs. Vehicular exhaust and gasoline evaporation were the main sources of VOCs leading to the formation of ozone. Health risk assessment showed that n-hexane, 1,3-butadiene, benzene, toluene, ethylbenzene, m/p-xylene and o-xylene had no appreciable risk of adverse non-cancer health effect on the exposed population, but 1, 3-butadiene and benzene had potential cancer risk. By comparing the corresponding data about health risk assessment of benzene compounds in some cities in China, it is concluded that benzene can impose relatively high cancer risk to the exposed populations in the ambient air of some cities in China. Therefore, strict countermeasures should be taken to further control the pollution of benzene in the ambient air of cities, and it is imperative to start the related studies and develop the atmospheric environmental health criteria and national ambient air quality standard for benzene in China.

Soil-transmitted helminth infections and physical fitness in school-aged Bulang children in southwest China: results from a cross-sectional survey.

BACKGROUND: Chronic soil-transmitted helminth (STH) infections have been associated with reduced physical fitness, but available evidence is limited. The aim of this cross-sectional survey was to assess the feasibility of measuring children's physical fitness and to relate it to STH infections. Our study was carried out among school-aged children of the Bulang ethnic group in rural southwest People's Republic of China (P.R. China). Standardized, quality-controlled methods were employed to determine STH infections (Kato-Katz technique), haemoglobin levels, anthropometry (body weight and height) and physical fitness (20-m shuttle run test). RESULTS: A compliance of 87% suggested good acceptance of the methods used. Among 69 children with complete data records, infection prevalence of Trichuris trichiura, Ascaris lumbricoides and hookworm were 81%, 44% and 6%, respectively. The maximum volume of oxygen that can be utilized within 1 min during exhaustive exercise (VO2 max estimate) of T. trichiura-infected children was 1.94 ml kg⁻¹ min⁻¹ lower than that of their non-infected counterparts (P = 0.005). Until exhaustion, T. trichiura-infected children had completed 6.14 20-m laps less (P = 0.004). Additionally, the mean VO2 max estimate of stunted children was lowered by 1.63 ml kg⁻¹ min⁻¹ (P = 0.002) and they completed 5.32 20-m laps less (P = 0.001) compared to children of normal stature. No significant association between stunting and infection with any STH species could be established. CONCLUSIONS: Implementation of physical fitness tests in rural, resource-constraint settings is feasible. The physical fitness of children who are stunted or infected with STHs, particularly T. trichiura, is significantly impaired. We have launched a larger study and will determine the dynamics of school-aged children's physical fitness over a 7-month period after administration of anthelminthic drugs.

[Surveillance of soil-transmitted nematode infections in Menghai County, Yunnan Province from 2006 to 2009].

In the national monitoring point, Menghai County, Yunnan Province, the total prevalence rate of soil-transmitted nematode infections was 88.12%, of which the rates of Ascaris lumbricoides, Trichuris trichiura, hookworm and cestode infections were 69.70%, 59.79%, 36.79%, and 1.30% respectively from 2006 to 2009. The infection intensities were slight. The Ascaris lumbricoides infection rate in soil of vegetable garden was 44.5%. In conclusion, the infection rate of soil-transmitted nematodes is high in the monitoring point.

[An investigation on malaria vectors in western part of China-Myanmar border].

OBJECTIVE: To reveal the distribution and composition of malaria-transmitting vectors on the western part of China-Myanmar border. METHODS: An entomological survey of malaria vectors was carried out in six villages of Yingjiang County and Xidong County on China-Myanmar border between August and September, 2008. Mosquitoes in human dwellings and cattle sheds were collected by overnight trapping with ovitrap light. The mosquitoes were firstly identified morphologically, and then Anopheles minimus A and C, An. aconitus, and An. jeyporiensis were identified by using multiplex PCR. Some mosquitoes were selected to extract the total genomic DNA, and detect sporozoites by nested PCR. RESULTS: A total of 4571 mosquitoes were captured with 54.32% (2483/4571) of anopheline mosquitoes. There was significant difference in Anopheles species composition in human dwellings and cattle sheda The main species in human dwellings were An. kochi, An. minimus, and An. sinensis, while the principal species in cattle sheds consist of An. kochi (223), An. annularis (184), An. vagus (131), and An jeyporiensis (129). Furthermore, the composition in human dwellings of villages with and without cattle was significantly different. An. minimus (260) and An. kochi (49) werethe most important species in villages with cattle, whereas An. kochi (481) and An. sinensis (124) were the key species in villages without cattle. A total of 1075 mosquitoes were examined for sporozoites and 9 mosquitoes were found to be infected. Only three species, Le. An. minimus (7/408), An aconiaus (1/125) and An. pseudowillmori (1/101) were infected with malaria parasite. All sporozoites were identified as Plasmodium falcipoarum by sequencing, the target fragment was 204 bp. CONCLUSION: The species composition of mosquitoes is complex in the study sites on the western part of China-Myanmar border, and An. minimus is the major malaria vector. Additionally, An. aconitus and An.pseudowillmori are also confirmed as potential malaria vector in this area.

[Clinical value of intracoronary ST-segment shift in diagnosis of early myocardial injury during percutaneous coronary intervention].

OBJECTIVE: To evaluate the role of intracoronary electrocardiogram (IcECG) in examining early myocardial injury during percutaneous coronary intervention (PCI). METHODS: Eight-six patients who had undergone elective PCI for their coronary heart disease were enrolled in the study. The IcECG both at baseline and after procedure were recorded with an incoronary guidewire and the serum levels of cardiac troponin T (cTnT) and creatine kinase-myoglobin were measured at baseline and 8 and 24 hours after intervention. Myocardial damage was defined as serum levels of cTnT increase above the upper normal value after intervention. Cardiac events after intervention was followed up. RESULTS: Of all these 86 patients with normal serum levels of cardiac markers before the procedure, significant shift at ST-segment in IcECG during PCI was observed in 30 patients (35%, abnormal group) and no shift in the remaining 56 patients (65%, control group). All the procedures were successful. Serum levels of cTnT and creatine kinase-myoglobin were significantly higher in abnormal group than in control group after intervention (P < 0.01). The intracoronary ST-segment shift had a sensitivity of 77% and a specificity of 94% in predicting myocardial injury, with positive and negative predictive values of 90% and 86%, respectively. More cardiac events were observed in abnormal group than those in control group at a 4-week follow-up after intervention (P < 0.05) and major coronary event-free survival was significantly lower in those with post-procedural ST-segment shift in the IcECG (P < 0.05). CONCLUSION: IcECG may be a useful method for predicting myocardial injuries during PCI.

Anopheles pseudowillmori is the predominant malaria vector in Motuo County, Tibet Autonomous Region.

BACKGROUND: Malaria is endemic in Linzhi Prefecture in the Tibet Autonomous Region (TAR), but the vector for malaria transmission had never been identified. METHODS: Adult Anopheles spp. were collected in Motuo County, Linzhi Prefecture on the Sino-Indian border in July and August, 2007. Multiplex PCR was adopted for species identification, and a nested PCR approach was used to detect sporozoites in the salivary glands of the mosquitoes. RESULTS: 3,675 mosquitoes of the Anopheles maculatus group were collected and processed for species identification. Among them, 3,602 (98.0%) were Anopheles pseudowillmori and 73 (2.0%) were Anopheles willmori. The Plasmodium vivax SSUrDNA fragment was amplified in two of 360 pooled An. pseudowillmori samples. CONCLUSION: The local An. maculatus group comprises the species An. pseudowillmori and An. willmori. Anopheles pseudowillmori is considered the sole malaria vector in Motuo County in Linzhi Prefecture.

Extensive multiparasitism in a village of Yunnan province, People's Republic of China, revealed by a suite of diagnostic methods.

Intestinal multiparasitism, the accuracy of different diagnostic techniques, and the influence of sampling effort were studied among 215 individuals in a Bulang village, Yunnan province, People's Republic of China. Behavioral, demographic, and socioeconomic data were obtained by questionnaire. Multiple stool specimens were examined by the Kato-Katz, Koga agar plate, Baermann, and ether-concentration methods. Eight helminth and 7 protozoa species were diagnosed. The prevalence of each of the 3 main soil-transmitted helminths (Ascaris lumbricoides, hookworm, and Trichuris trichiura) exceeded 85%. Blastocystis hominis was the most prevalent intestinal protozoan (20.0%). Over 80% of the individuals harbored 3 or more intestinal parasites concurrently. The infection intensities were predominantly light for hookworm and T. trichiura but moderate for A. lumbricoides. Examination of 3 instead of 1 stool specimen increased the sensitivity of helminth diagnosis, most notably for hookworm. Intestinal multiparasitism is rampant in this rural part of Yunnan province and calls for control measures.

[Species identification of Anopheles maculatus complex in malaria endemic area Motuo County, Tibet].

OBJECTIVE: To identify the species of Anopheles maculatus complex in malaria endemic area Motuo County, Linzhi Prefecture, Tibet Autonomous Region. METHODS: 5190 adult mosquitoes were morphologically identified as An. maculatus complex, and 575 were randomly selected to extract DNA by phenol-chloroform method. According to the rDNA ITS2 variations of An. maculatus s. s., An. willmori, An. pseudowillmori, An. sawadwongporni and An. dravidicus, 5 pairs of specific primers were designed for PCR identification on the species of An. maculatus complex. The PCR products were sequenced in double directions, and homology searches were done over the Web using the program Blast. 22 ITS2 sequence of An. maculatus complex from GenBank was adopted to construct phylogenetic tree with UPGMA method by MEGA (3.1) software. RESULTS: 575 DNA samples were extracted. Among which, 11 were amplified 231 bp An. willlmori fragment (1.9%) and 564 were amplified 119 bp An. pseudowillmori fragment (98.1%). PCR identification, Web homology blast and phylogenetic tree showed same results. CONCLUSION: The predominant anopheline mosquitoes in Motuo County is An. pseudowillmori.

[Investigation on malaria transmission vectors in Motuo County, Tibet Autonomous Region].

OBJECTIVE: To investigate the malaria transmission vectors in Motuo County of Linzhi Prefecture, Tibet. METHODS: Three natural villages with higher malaria incidence rate in Motuo County were selected for the study in July and August, 2007. The anopheline mosquitoes were collected by overnight/semi-overnight trapping indoor and outdoor with human and cattle baits, overnight trapping with ovitrap lights in human dwellings and cowsheds, and by searching in human dwellings in the early morning. The mosquitoes collected were identified morphologically, and the group proportion, density, man-biting rate, blood preference, habits and multiparous ratios were observed. Mosquito larvae breeding place was surveyed, and species of the larvae were identified. RESULTS: A total of 5345 anopheline mosquitoes were captured with 94.71% (5 062/5 345) of An. pseudowillmori, 2.39% (128/5 345) of An. willmori and 2.90% (155/5 345) of An. peditaeniatus. The average density of An. pseudowillmori observed through semi-overnight trapping was 17/per person indoor and 105/per person outdoor. The average man-biting rate of An. pseudowillmori through overnight trapping was 15.80/per person (79/5) indoor and 326.22/per person (1468/4.5) outdoor. The ratio of blood preference to human and cattle through overnight trapping outdoor were 30.51% (714/2340) and 69.49% (1626/2340), and 32.02% (57/178) and 67.98% (121/178) through overnight trapping with ovitrap lights respectively. It suggested that An. pseudowillmori feeding both of the human and cattle blood but preferred to cattle blood. Totally 7 An. pseudowillmori mosquitoes were found in the human dwellings in the early morning, and none of them has digested the engorged blood. The Anopheles larvae were only found in the rice field where 106 larvae were collected, including 62 An. pseudowillmori larvae, An. willmori larvae, and 44 An. peditaeniatus larvae. CONCLUSION: An. pseudowillmori seems qualified as the vector biological perspectives for the local malaria transmission.

Occurrence of Strongyloides stercoralis in Yunnan Province, China, and comparison of diagnostic methods.

BACKGROUND: Strongyloides stercoralis is a neglected soil-transmitted helminth species, and there is a lack of parasitologic and epidemiologic data pertaining to this parasite in China and elsewhere. We studied the local occurrence of S. stercoralis in a village in Yunnan province, China, and comparatively assessed the performance of different diagnostic methods. METHODOLOGY/PRINCIPAL FINDINGS: Multiple stool samples from a random population sample were subjected to the Kato-Katz method, an ether-concentration technique, the Koga agar plate method, and the Baermann technique. Among 180 participants who submitted at least 2 stool samples, we found a S. stercoralis prevalence of 11.7%. Males had a significantly higher prevalence than females (18.3% versus 6.1%, p = 0.011), and infections were absent in individuals <15 years of age. Infections were only detected by the Baermann (highest sensitivity) and the Koga agar plate method, but neither with the Kato-Katz nor an ether-concentration technique. The examination of 3 stool samples rather than a single one resulted in the detection of 62% and 100% more infections when employing the Koga agar plate and the Baermann technique, respectively. The use of a mathematical model revealed a 'true' S. stercoralis prevalence in the current setting of up to 16.3%. CONCLUSIONS/SIGNIFICANCE: We conclude that S. stercoralis is endemic in the southern part of Yunnan province and that differential diagnosis and integrated control of intestinal helminth infections needs more pointed emphasis in rural China.

Molecular epidemiology of human Blastocystis in a village in Yunnan province, China.

The purpose of this study was to improve our understanding of the molecular epidemiology of human Blastocystis, focusing on 239 randomly selected individuals in a single village in Yunnan province, China. Emphasis was placed on the relative frequency of different Blastocystis subtypes and underlying risk factors. We used a cross-sectional study design, by employing a pre-tested questionnaire to obtain demographic data and behavioural risk factors, and collected faecal samples for culture and subsequent identification of Blastocystis. DNA was extracted from Blastocystis isolates and the subtypes were identified using 7 subtype-specific sequenced-tagged site (STS) primers. Overall, 78 faecal samples were Blastocystis culture-positive (32.6%, 95% confidence interval: 26.7-38.6%). The majority (n=73, 93.6%) were single infections with one of the known subtypes, whereas 2 isolates consisted of 2 concurrent subtypes. The remaining 3 isolates could not be identified with the currently known STS primers. Risk factors for a Blastocystis infection were drinking unboiled water, consumption of raw water plants and pig ownership. The consumption of raw water plants was positively associated with subtype 1 infections, and drinking unboiled water with subtype 3 infections. In conclusion, human Blastocystis was common in this village in southwest China, and different subtypes were associated with distinct transmission routes or sources of infection, and hence Blastocystis subtypes might be linked to specific environmental compartments.

[Study on photoluminescence spectra of Cd(1-x)Mn(x)Te/CdTe diluted semiconductor superlattices with high Mn compositions].

The electronic properties of Cd(1-x)Mn(x)Te/CdTe semiconductor superlattices (SLs) with high Mn concentrations (x up to 0.8) were studied by means of low and room temperature photoluminescence (PL). The samples were grown by MBE on GaAs substrates with CdTe buffers. PL allowed the investigation of the optical emission from the fundamental 11H excitonic transition, revealing the high quantum efficiency and quality of the SLs. The temperature dependence of the excitonic PL energy position and excitonic line-shape broadening were studied. An exciton-longitudinal optical phonon couple model can be used to explain the experimental results very well. Photoreflectance (PR) spectra were also performed in order to compare with the authors' photoluminescence results. The combined use of PL and PR allowed a full understanding of the electronic states and optical emission characteristics of the authors' SLs. The authors' results indicate that high quality Cd(1-x)Mn(x)Te/CdTe SLs with high Mn concentrations can be grown using MBE on GaAs substrates. The possibility to have magnetic semiconductor nanostructures opens the way to applications in the field of spintronics toward devices based on new concepts.