[The Effect of Lipopolysaccharide-Induced Mouse B Cell Activation on Schistosoma japonicum Development].

OBJECTIVE: To investigate the effect of lipopolysaccharide (LPS)-induced B cell activation on the development of Schistosoma japonicum. METHODS: Eighteen BALB/c nude mice deficient in T cells and 23 BALB/c SCID mice deficient in T and B cells were used in this study. Each was infected with 30 ± 1 S. japonicum cercariae. The nude (n=9, NL group) and SCID (n=12, SL group) mice then received 2-3 (every two weeks) intraperitoneal injections with LPS (100 µg/mL, 0.2 mL for each mouse). The remaining nude(n=9, N group) and SCID (n=11, S group) mice received PBS injection as control. The mice were sacrificed on days 28 and 36 after infection (n=4/5, 4/5, 5/6, 6/6 for N, NL, S and SL groups, respectively), and adult worms were collected by hepatic portal vein perfusion. The collecting rate of the adult worms was calculated, the body-length measured, and pairs of worms recorded. The liver tissue was collected and digested with 5% KOH, and the number of eggs per gram of liver tissue was calculated. The levels of TGF-ß, IFN-γ and IL-10 in peripheral blood were evaluated. Spleen cell suspension was prepared for detecting the proportion of regulatory B cells (Bregs) in splenic lymphocytes. RESULTS: On day 28 after infection, the body-lengths of male worms in NL and N groups were (7.65±2.85) mm and (5.28±1.64) mm (P<0.01), and those of female worms were (9.64±1.99) mm and (7.49±1.63) mm (P<0.01), respectively. On day 36 after infection, the number of eggs per gram of liver tissue was significantly higher in the NL group than in the N group (1 088±297 vs 715±404, P<0.05), and significantly lower in the SL group than in the S group (217±33 vs 573±160, P<0.01). The proportions of CD(hi)CD5(+)CD19(+) Bregs in N group on days 28 and 36 after infection were (12.73±0.96)% and (37.15±3.04)% (P<0.05), respectively, with no significant difference with that of NL group. The serum levels of TGF-ß and IFN-y on day 28 after infection were significantly different between N and NL groups (TGF-ß, 101.75±46.72 vs 260.90±45.34 pg/mL; IFN-y, 7.91±1.62 vs 14.11±3.72 pg/mL, both P<0.01). Similarly, significant difference was found for the plasma level of IL-10 on day 36 after infection between the S and N groups (41.85±3.14 vs 66.25±4.16 pg/mL, P<0.01), and between the SL and NL groups (44.48±3.87 vs 72.22±17.76 pg/mL, P<0.01), but not between the LPS groups and the control groups. CONCLUSION: LPS can induce the release of cytokines (e.g. TGF-ß) from B cells of mice infected with S. japonium, to facilitate the early development of adult female and male worms.

Effect of cytotoxic T-lymphocyte-associated protein 4 on CD4(+)CD25(+) regulatory T cells in murine schistosomiasis japonica.

In a previous study we demonstrated that CD4(+)CD25(+) regulatory T cells (Tregs) contributed to the escape of Schistosoma japonicum (S. japonicum) from the host's immune responses. In this paper, we studied the effect of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) on CD4(+)CD25(+) Tregs in murine Schistosomiasis japonica and its corresponding role in the immune evasion of S. japonicum in mice. The results showed substantial reductions of worm burden and egg production in worm groups treated with anti-CD25 or anti-CTLA-4 monoclonal antibodies (mAb) compared to an infected but untreated control. The reduction effect was even enhanced in an experimental group co-treated with both mAbs. Compared to the control group, the percentage of CD4(+)CD25(+) Tregs was very much lower in the anti-CD25 mAb group as determined by FACS analyses and higher in the anti-CTLA-4 mAb group. ELISA analyses showed that both the anti-CTLA-4 mAb and the co-treated groups had higher levels of cytokines compared to the control group as well as larger egg granuloma sizes as determined by microscopical analyses of liver sections of infected mice. These results suggest that treatment with an anti-CTLA-4 mAb allows the host to clear S. japonicum, but at the cost of elevated pathological damage. The latter indicated a role of CTLA-4 in granuloma formation. Moreover, CD4(+)CD25(+) Tregs and CTLA-4 may exert synergistic effects during immune evasion processes by enhancing Th1-type immune response.

Cloning and characterization of a bone morphogenetic protein homologue of Schistosoma japonicum.

Bone morphogenetic proteins (BMPs) are known to play an important role in the regulation of cell proliferation, survival, differentiation and apoptosis in many vertebrates and invertebrates through the TGF-ß signaling pathway. Although the TGF-ß signaling pathway exists in schistosomes, BMP homologue, a ligand of TGF-ß in Schistosoma japonicum, has not yet been identified. In this study, a BMP homologue of S. japonicum was cloned and characterized. The full length SjBMP cDNA is 3,020 bp and encodes 928 amino acids, which include a TGF-ß superfamily conserved domain at the C-terminus. BLAST analysis showed that, SjBMP has 68%, 51% and 43% homology with BMP from Schistosoma mansoni, Schmidtea mediterranea and Dugesia japonica at the amino acid level, respectively. According to data from real-time PCR, SjBMP was expressed in lung-stage schistosomula, 21-day liver-stage schistosomula, 50-day adult worms (the male and female), and eggs. The PCR data also indicated that, there was a ≈ 27- and ≈ 37-fold increase of SjBMP transcripts in the lung-stage schistosomula and eggs, respectively, and that there was relatively more SjBMP transcript in the adult male worm than in the adult female, in which the hepatic schistosomula was set as the calibrator for calculation. In situ hybridization based on FITC-labeled specific antisense oligonucleotide probes showed that SjBMP mRNA localized to the ovary of female worms and the integument and epithelium of female and male worms. After treatment with double-stranded RNA (dsRNA) at a concentration of 8 × 10(-2) µg/ml, which was added to the culture medium every other day for a week, the level of SjBMP mRNA in the cultured adult mixed-sex S. japonicum decreased at a range of ≈ 25-98% within 7 days compared with the level of SjBMP mRNA in the blank control group. On the 2nd day, the number of eggs produced per pair of worms decreased 28.7%, and the percent of normal eggs also decreased (12.7% vs. 4.3%) in the SjBMP dsRNA-treated group when compared with the eggs laid by the blank control group. No difference was detected between the two groups on the 7th day of treatment, because the eggs of the untreated worms were also mostly abnormal, similar to the eggs laid by the treated group. In addition, no significant difference in the morphological structure of the adult worms was observed. Thus, the preliminary in vitro experiment indicated that SjBMP may be involved in the oviposition behavior of S. japonicum, and further studies based on the recombinant virus vector-induced steady knockdown of SjBMP or in vivo experiments are required for more in-depth investigation.

The new national integrated strategy emphasizing infection sources control for schistosomiasis control in China has made remarkable achievements.

Schistosomiasis japonica remains one important public health concern that cause great loss of humans' health and social-economic development in the Peoples' Republic of China. At the end of 1990s and the beginning of 2000s, there were still about 0.8 million patients and nearly 85 million people living in the epidemic areas around China. We undertook full analysis of the epidemiological data of schistosomiasis taken from the report of schistosomiasis status in People's Republic of China from 1999 to 2010 for effectiveness assessment of China's new strategy for schistosomiasis control nationwide after its implementation since the beginning the 21st century. The schistosomiasis-endemic uncontrolled counties or towns decreased in number from 1,149 in 2002 to 643 in 2010 at a rate of 44%. The number of schistosomiasis patients decreased from nearly 800,000 to less than 326,000 in 2010 at a decrease rate of more than 50%. The number of acute schistosomiasis patients also decreased significantly, and only 43 cases were reported in 2010. The infection rates of cattle in the endemic uncontrolled provinces decreased greatly though the number of cattle and the actual snail habitat areas remained large with no obvious decline. The schistosome infection rates of human and cattle both decreased significantly by more than 64% and 75%. However, most of the uncontrolled schistosomiasis-endemic areas, schistosomiasis patients, and acute cases are generally located in the four provinces (Hunan, Hubei, Jiangxi, and Anhui) of the lake regions in the middle and lower reach of the Yangtze River, and the egg-positive rates in diagnosed human in endemic Hunan and Hubei remained higher than 10%. Therefore, the new strategy of schistosomiasis control via integrated measures emphasizing infection source control is scientific and successful around China, though it is essential to explore an effective and sustainable strategy for schistosomiasis control in the tough lake and marshland regions of China. The four provinces (Hunan, Hubei, Jiangxi, and Anhui) of the lake regions in China are the main battlefield of China's schistosomiasis control in the present and future.

The sensitivity of artesunate against Schistosoma japonicum decreased after 10 years of use in China?

Artesuante (AS) is a good chemoprophylactic drug for preventing against schistosome infection, but Hua et al. recently reported that the sensitivity of AS against Schistosoma japonicum decreased after 10 years of use in China. There are at least three problems, to our knowledge, making the finding suspicious or inconclusive in that report. In consideration of it as the first report about the emergence of potential artemisinin derivative-resistant S. japonicum to date and the possible severe influences of the emergence of AS-resistant S. japonicum on the future choice of chemoprophylactic drugs for preventing against S. japonicum infections in China, we write this comment and call for some more rigorous and convincing trials to confirm this finding further.

Artemisinin: the gifts from traditional Chinese medicine not only for malaria control but also for schistosomiasis control.

The 2011 Lasker~DeBakey Clinical Medical Research Award honors the Chinese scientist Tu Youyou who discovered artemisinin and its utility for treating malaria. A therapy based on artemisinin has saved millions of lives across the globe, especially in the developing world. Meanwhile, artemisinin and its derivatives, especially for artemether and artesunate, are showing promising preventive efficacies as high as 65-97% administrated with multiple doses at 6 mg/kg body weight by 1- or 2-week intervals for preventing schistosomiasis japonica during epidemic seasons used in China for more than one decade. So, we would like to say, to our excitement, artemisinin and its derivatives are the gifts from traditional Chinese medicine not only for malaria control but also for schistosomiasis control.

What is the role of health education in the integrated strategy to control transmission of Schistosoma japonicum in China?

In 2009, Wang et al.'s field trial published in the New England Journal of Medicine, reported that a comprehensive strategy aiming to reduce the roles of humans and cattle as sources of Schistosoma japonicum infection in snails was implemented and proved effective and promising in dramatically reducing the percentage of infected humans and snails, which had been extended to other endemic provinces in China afterwards. This implies that the integrated schistosomiasis-control strategies of interventions including political will, financial support and residents' participation to control human and bovine sources of S. japonicum infection in snails may direct to successfully interrupt the parasitic transmission and to ultimately eliminate schistosomiasis. Confusingly, however, the role of health education, which is a critical part of the integrated strategy and should play an active role in schistosomiasis control, was not reflected. We wish the authors to provide the readers a better and clearer statement of the role of health education as part of the integrated control strategy and so we write this comment.

[An easy way to purify the inclusion body protein with high purity from prokaryotic expression cells].

To clone partial ORF of SjBMP and to construct the recombinant SjBMP-pET-28a(+) plasmids, and then to transform them into the competent cells E. coli BL21 (DE3), finally a positive clone was used to be induced by IPTG. The bacterial aggregates with target protein expressed as inclusion bodies were purified by the methods of Ni(2+)-NTA affinity purification under denaturation condition and SDS-PAGE gel extraction. The purified protein was used to immune rabbits and make antiserum against the SjBMP, and the antiserum were then used to identify the rSjBMP by Western blotting. The target protein obtained by Ni(2+)-NTA Agarose affinity purification was not pure with unspecific proteins, but the protein further purified by SDS-PAGE gel extraction and the dialysis bag horizontal electrophoresis was quite pure, and the recovery rate was more than 11.0%. Meanwhile, Western blotting was used to identify the recombinant SjBMP protein by antiserum, only a specific single strip appeared, which suggested the protein purified by this method kept its antigenicity, and could be used for common immunological studies. Therefore, the SDS-PAGE gel extraction combining with electroosmosis and dialysis recycling are good and easy to purify the inclusion body proteins.

Conservation and variation in mitochondrial genomes of gastropods Oncomelania hupensis and Tricula hortensis, intermediate host snails of Schistosoma in China.

The complete mitochondrial genomes of intermediate host snails for Schistosoma in China were sequenced, including the sub-species Oncomelania hupensis hupensis in two types, and O. hupensis robertsoni, intermediate hosts for S. japonicum, and Tricula hortensis, the intermediate host of S. sinensium. Four genomes have completely the same gene order as in other caenogastropods, containing 13 protein-coding genes and 22 transfer RNAs. The gene size, start codon and termination codon are mostly the same for all protein-coding genes. However, pairwise sequence alignments revealed quite different degrees of variation. The ribbed-shelled O. hupensis hupensis and the smooth-shelled but with varix O. hupensis hupensis had a lower level of genetic distance (3.1% for protein-coding genes), but the coden usages differed obviously in the mitochondrial genomes of these two types of snails, implying that their genetic difference may be larger than previously recognized. The mean genetic distance between O. hupensis hupensis and O. hupensis robertsoni was 12% for protein-coding genes, indicating a higher degree of genetic difference. In consideration of the difference in morphology and distribution, we considered that O. hupensis hupensis and O. hupensis robertsoni can be considered as separate species. The ribbed-shelled O. hupensishupensis and smooth-shelled O. hupensis robertsoni were phylogenetically clustered together within a same clade, which was then clustered with T. hortensis, confirming their close relationship. However, species or sub-species in the Oncomelania from southeastern Asian countries should be included in future study in order to resolve the phylogenetic relationship and origination of all snails in the genus.

[Research progress on the antioxidant enzyme family in medical trematode].

Reactive oxygen species (ROS), generated in the metabolism process of aerobic organisms, can induce oxidative damages in the body. These organisms are all equipped with an excellent defense system to protect themselves and antioxidant enzymes play an important role in the system. Parasitic trematodes have to eliminate ROS not only from themselves but also from the immune system of their hosts. To better understand the structures and specialties of the antioxidant enzymes in trematodes is conducive to the study on reproductive physiology of trematode and on drug and vaccine development. This paper summarizes the research progress on the family of antioxidant enzymes in trematodes including glutathione peroxidase (GPx), superoxide dismutase (SOD) and peroxiredoxin (PRx) in the past decades.

[In vitro effect of 5-hydroxytryptamine on motility and length of Schistosoma japonicum primary sporocysts].

OBJECTIVE: To study in vitro the effect of 5-hydroxytryptamine (5-HT) on the motility and length of primary sporocysts of Schistosoma japonicum and select the optimal concentration and time of 5-HT. METHODS: Eggs of S. japonicum were harvested from livers of the infected mice 6-8 weeks after infection, which were then incubated with water. The miracidia were axenically cultured in 1/2 RPMI 1640 containing 10% calf serum and a moderate amount of antibiotics (100 U/ml penicillin G and 100 microg/ml streptomycin) for 48 hours. They became mother sporocysts and were divided into two groups. Parasites in the first group were treated by 5-HT under concentrations of 0, 0.1, 1, 10, 100 and 1000 micromol/L for 48 hours, respectively. Those parasites in the second group were treated by 5-HT of 10 micromol/L for 0.16, 6, 24 and 48 hours, respectively. The motility, length and succinic dehydrogenase (SDH) activity of the parasites were measured under Olympus microscope. RESULTS: Along with the increase of 5-HT concentration, the motility and length of the mother sporocysts all increased gradually. With the 5-HT concentration of 10 micromol/L, both of them reached a maximum value, being (65.6 +/- 1.5)% and (131.4 +/- 9.2) microm respectively. Meanwhile, along with the prolongation of treatment time, the motility and length also increased gradually. The motility reached a maximal value at 24 hours post-treatment. So did the length and SDH activity of the parasites at 48 hours post-treatment. CONCLUSION: 5-HT shows a significant effect on the motility and length of mother sporocysts of S. japonicum and its optimal concentration is 10 micromol/L under in vitro conditions.

Influence of enterococci on human sperm membrane in vitro.

AIM: To study the influence of enterococci on human sperm membrane in vitro. METHODS: Ejaculated human sperm were artificially infected with beta-hemolytic or non-beta-hemolytic enterococci at the bacteria: sperm ratio of 50:1 at 37 degrees . Sperm membrane integrity was examined after incubation for 1, 3 and 5 h by hypoosmotic swelling (HOS) test and electron microscopy. RESULTS: Sperm infected with beta-hemolytic enterococci had lower HOS scores compared with non-beta-hemolytic strains or uninfected control (P < 0.01). The HOS test scores of sperm infected with beta-hemolytic enterococci increased in the presence of phosphatidylcholine, an inhibitor of hemolysin. Non-beta-hemolytic strains showed no significant difference in swelling rate, compared with the control group (P > 0.05). It was shown by electron microscopy that beta-hemolytic enterococci caused significant rupture of human sperm membrane. CONCLUSION: Beta-hemolytic enterococci caused human sperm membrane injury, and might be mediated by the hemolysin of enterococci.

[Primary culture of the cells from Oncomelania hupensis liver].

OBJECTIVE: To develop a method for primary culture of cells from Oncomelania hupensis liver, and to observe the distribution of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) in the cultured cells. METHODS: O. hupensis was anatomized to separate the liver. Livers were soaked in 0.2% benzalkonium bromide and washed by physiological saline containing antibiotics in turns. Cells from the liver were harvested by mechanical mulling and filtering. The isolated cells were then incubated with methods of the combination culture and standing suspension culture, respectively. The culture medium for the cells was a mixture of Medium 199 (50 ml), 0.3% lactoalbumin hydrolysate dissolved in a balanced salt solution (BBS, 30 ml), and fetal calf serum (FCS, 20 ml) containing a moderate amount of antibiotics (100 IU/ml penicillin, 100 microg/ml streptomycin and 50 microg/ml kanamycin) at pH 7.2-7.4 under the temperature of 26.5 degrees C. The cells were stained by using Giemsa and Pearson methods (for SDH and LDH respectively) to observe the shape of cultured cells and enzyme distribution in cells. The living and stained cells were microscopically observed. RESULTS: Under microscope, the attached cells incubated with method of the combination culture showed round, elliptic, triangular and irregular shapes, with more round and elliptic cells. The size was approximately (4-16) microm x (6-20) microm in average. The clustered cells with an unclear nucleus and abundant and lucid cytoplasm were smaller than diffused cells with a large, obvious nuclei and less cytoplasm. Degeneration was observed after culturing for 5-7 days. The cultured cells could be divided into two types based on the color shown after Giemsa staining. The first type cells showed blue cytoplasm and mauve nuclei while the second type cells were opposite. There were blue granules in different sizes and shade in the cytoplasm after SDH and LDH staining. It was difficult for the cells to attach the wall of the culture flask using method of the standing suspension culture. The shape of the cultured cells were almost round with unclear nuclei, and the size was about (4-6) microm x (6-8) microm in average. The cells incubated with the standing suspension method were found to be contaminated after culturing for 3 days. CONCLUSION: The combination culture method is suitable for primary culture of the cells from O. hupensis liver and the cells show activities of both SDH and LDH in cytoplasm.

A membrane-associated metalloprotease of Taenia solium metacestode structurally related to the FACE-1/Ste24p protease family.

The CaaX proteases are intimately involved in the post-translational modification of prenylated proteins and play a critical role in the activation/stabilization of membrane-bound or secreted molecules constituting the CAAX protein family. In this study, we have isolated a full-length cDNA putatively encoding a type I CaaX protease of the Taenia solium metacestode (TsM), which an agent causative of human neurocysticercosis. The cDNA, designated TsSte24p, comprised 1,505 bp and coded for an open reading frame of 472 amino acids with predicted Mr 54.5 kDa. This monoexonic TsSte24p gene existed as a single copy within the TsM genome and constantly expressed in the parasite from metacestode to adult stages. The TsSte24p exhibited the typical CaaX protease topology, including seven transmembrane domains and a metalloprotease segment with a zinc-binding motif. It shared a significant degree of sequence identity with the type I CaaX proteases such as Saccharomyces cerevisiae Ste24p and Caenorhabditis elegans CeFACE-1. A comparative phylogenetic analysis demonstrated that this protein family is tightly conserved across taxa, from bacteria to mammals. The bacterially expressed recombinant TsSte24p showed proteolytic activity, with an optimal pH of 7.5. The enzyme activity was significantly inhibited by EDTA. Its activity was increased in the presence of low concentrations of the Zn2+(0.001-0.01 mM); but was reversibly down-regulated at high doses (over 0.1 mM). The native TsSte24p appeared to function as a homodimer, the subunits of which were linked to each other via covalent disulfide bond. The protein was localized in the bladder wall and scolex with differential patterns of distribution. Our results indicated that TsSte24p is a zinc-dependent metalloprotease, which belongs to the FACE-1/Ste24p protease family.

[Proteomics and its application in parasitology].

Proteomics is an important high throughout method in modern life science. In this paper, the definition, background and methods used in proteomics were introduced, and the last part was focused on its application in parasitology.

[Effect of chronic Toxoplasma infection on the spatial learning and memory capability in mice].

OBJECTIVE: To investigate the effect of chronic infection of Toxoplasma gondii on the spatial learning and memory capability in mice. METHODS: Toxoplasma tachyzoites (RH strain) were reanimated at 37 degrees C after 15 days' storage at -20 degrees C, and injected intraperitoneally to mice of the experimental group each with 7.7 x 10(5). Normal saline was given to the control group, 0.5 ml per mouse. Two months later, all mice were tested in the Morris Water Maze. Smears of the mice brain homogenate and pathological sections were examined. RESULTS: (1) The density of cysts in the brain homogenate was 15/HP, and there was no evident pathological change in the hippocampus and adjacent areas of mice in the brain in the experimental mice. (2) Latency to platform, cumulative distance to the platform, total distance traveled in both experimental and control groups decreased significantly with the increase of training days (P < 0.01). The latency and cumulative distance in experimental group were significantly longer than that of the control group (P < 0.01). (3) The searching strategy of mice in the experimental group was significantly different from that of the control group. CONCLUSION: Toxoplasma tachyzoites can induce chronic infection in mice and the infection can damage at some extent the spatial learning and memory capability of mice.

Transmission control of schistosomiasis japonica: implementation and evaluation of different snail control interventions.

The great progress made in the control of schistosomiasis japonica in China is to some extent explained by successful intermediate host snail control, in particular with environmental management commencing some 50 years ago. By 1995, interruption of Schistosoma japonicum transmission had been achieved in five of the 12 schistosome-endemic provinces while endemic areas in the remaining provinces had been reduced significantly, and snail habitats had decreased by 74%. In this paper, we review the role and approaches towards control and give an account of compounds toxic to snails. Mid- and long-term national plans for schistosomiasis control are discussed, including integrated snail control approaches as an important measure. It is anticipated that implementation of these plans will accelerate snail control, which in turn will consolidate and mutually reinforce other control measures, most notably praziquantel-based chemotherapy. The ultimate aim is to eliminate schistosomiasis as a public health problem in China.

Ultrastructural observation of spermatozoa and fertilization in Schistosoma japonicum.

The ultrastructure of the sperm and the process of fertilization are described in Schistosoma japonicum. The sperm of S. japonicum has an elongated head and a single tail. The head measures 6.2 x 1.4 microm in average size. No acrosome is present. A mass of mitochondria locates in front of the nucleus. A layer of about 100-120 peripheral microtubules is parallel with the long axis of the head under plasma membrane. The nucleus is dense with some electron-lucent patches. The tail is a single flagellum with unique axoneme, which originates from a centriole. The structure of axoneme includes two types: 9 x 2 + <> in the main part of the flagellum, and 9 x 2 + 0 near the end of the flagellum. The sperm ultrastructure of S. japonicum is similar to that of other schistosomes, apart from the fact that two types of configuration coexisted in the same axoneme, and there is no striated root found in S. japonicum. The sperm differs distinctly from other Digenea. The aberrant ultrastructure of S. japonicum reflects that its evolution is far away from other genera in Digenea. Fertilization occurs at the posterior part of oviduct, in which region the oviduct wall lacks lamellae. Some cortical granules (CG) fuse with plasma membrane, and discharge their content on the surface of the fertilized ovum. The other CGs break down or degenerate in the cytoplasm. By the secondary mature division, the secondary oocyte finally divides to form a female pronucleus. During this period a male pronucleus also forms. The female and male pronucleus approach each other, come into contact in the central region and finally fuse to form a zygote. The function of CGs is discussed.

Ultrastructure of cultured cells from Schistosoma japonicum.

Ultrastructures and their dynamic changes of the cultured cells from Schistosoma japonicum were observed in the present experiments. Several types-including polygonal, round granular, deltaic fan-shaped and flagellated cells-were found in the cultures. The polygonal cells took a major ratio in the cultures from adult S. japonicum, while the majority from schistosomula was round granular cells. The ultrastuctures on the cell surface were different between the cells from adults and schistosomula. Some papilla-like tubercula, microvilli and pinocytotic vesicles were observed on the surface of adult cells, but none were found on schistosomula cells. However, more or less mitochondria, endoplasmic reticula, ribosomes and glycogen were observed in the cytoplasm of the cultured cells from both adults and schistosomula. Golgi complexes were rarely found. The nucleus was round, with round nucleolus inside and clear pores on the unit membrane. There was much lumpish heterochromatin located near to the nuclear membrane. Cells from different worm tissues had their own organelles. The germ cells, vitelline cells, flame cells, multinucleate subtegumental cells and nerve cells could be observed in the cultures from adults. The vitelline cells were the greatest in number and nerve cells were the least in number among them. Similarly, there were germ cells, sustentacular cells, flame cells, nerve cells, mast cells, muscle cells, multinucleate subtegumental cells, interstitial cells and penetration gland cells in the cultures from the schistomomula. In addition, a few division cells were also found. It indicated that the schistosomula cells had greater potential ability to proliferate than the adult cells in in vitro culture. Along with the prolongation of the culture time, degeneration of schistosomal cell occurred more and more. Generally, the electron density of cultures gradually got lower, the cristae of mitochondria blurred and disappeared and the mitochondria themselves swelled and finally vacuoled completely. Vitelline cells were most sensitive to the changes of the in vitro condition in all cultures. Their degeneration showed the following characteristics: (1) vitelline globules fused each other, the space between vitelline globules and the membrane surrounding them broadened gradually and vitelline globules were released and uncovered; (2) rough-surfaced endoplasmic reticula enlarged, vacuolated and the ribosomes dropped; and (3) the number and volume of lipid increased. The ultrastructural changes of most of the cultures from schistosomula had the following trends: (1) heterochromatin increased and euchromatin decreased gradually; and (2) endoplasmic reticula changed into short tubes and vacuoles and disappeared finally. The degenerative process of the cultures from S. japonicum consisted of necrosis according to the ultrastructural changes of the mitochondria, vitelline globules, chromatin and endoplasmic reticula within the cells. The changes of the above structures could be used to estimate whether the culture conditions were appropriate.

Cluster of acute hemorrhagic appendicitis among high school students in Wuhan, China.

BACKGROUND: Features of a cluster of acute appendicitis that occurred among a high school student population in China were investigated. METHODS: Epidemiologic data, medical records, and histologic slides of resected appendices were examined. RESULTS: During a period between April 10, 1997, and June 11, 1997, 11 cases occurred in a high school, with 10 cases among 290 students enrolled at the time. From the end of the initial cluster until June, 2000, 20 additional cases were encountered. Female cases (6.5%) are more frequent than male cases (1.9%). There was a clustering pattern. Many patients had a history of mutual contact before the onset of symptoms. Pathologically, the resected appendices exhibited diffuse or focal hemorrhages in the lamina propria or within hyperplastic lymphoid follicles, and infiltration by eosinophils and by lymphocytes. Appendical tissues were examined using immunohistochemistry, but no etiologic agent was identified. CONCLUSIONS: This cluster of acute appendicitis represented a special kind of appendicitis, with features of an infectious disease in epidemiology.