A neglected normal anatomical structure in mammal: a study in bats and tree shrews / Una estructura anatómica normal desatendida en mamíferos: un estudio en murciélagos y musarañas arborícolas

SUMMARY: The myodural bridge is a dense connective tissue connecting muscles and ligaments to the spinal dura mater in the atlanto-occipital interspace. Some researchers believe that the myodural bridge may play a vital physiological role. It is possible, for instance, that the prevention of spinal dura mater infoldings might be involved in regulated cerebrospinal fluid circulation. For instance, it is possible to prevent spinal dura mater infoldings, regulating cerebrospinal circulation. Bats are nocturnal and the only mammals that can perform a genuine and sustained flight, whereas tree shrews are arboreal mammals that often climb to a high altitude of about 10,000 feet. Both animals have lifestyles that are different from other previously studied mammals. The study of these two animals will shed further light on the existence of the myodural bridge in mammals. Gross anatomical dissection was used to observe the connections between the deep muscles of the neck and the dura mater at the level of the atlanto-occipital interspace. The existing structures were analyzed using conventional and special histological staining techniques. The suboccipital regions in bats and tree shrews contained the rectus capitis dorsal major (RCDma), rectus capitis dorsal minor (RCDmi), oblique capitis anterior (OCA), and oblique capitis posterior (OCP). Dense connective tissue connects the RCDmi to the posterior atlanto-occipital membrane (PAOM) and the latter to the spinal dura mater. The myodural bridge in these mammals shares a similar structure to the myodural bridge in humans. Histological analyses confirmed that the connective fibers of the myodural bridge were primarily type I collagen fibers. In this study, it is supplemented by the existence of the myodural bridge in mammals. This further demonstrates that myodural bridge widely exists in the normal anatomy of mammals. This provides morphological support for a comparative anatomical study of the physiological function of the myodural bridge.

El puente miodural es un tejido conjuntivo denso que conecta los músculos y los ligamentos a la duramadre espinal en el espacio atlanto-occipital. Algunos investigadores creen que el puente miodural puede desempeñar un papel fisiológico vital. Es posible, por ejemplo, que la prevención de los pliegues de la duramadre espinal pueda estar involucrada en la circulación regulada del líquido cefalorraquídeo. En esta instancia, es posible prevenir los pliegues de la duramadre espinal, regulando la circulación cerebro espinal. Los murciélagos son animales nocturnos y los únicos mamíferos que pueden realizar un vuelo real y sostenido, mientras que las musarañas arborícolas son mamíferos arbóreos que a menudo ascienden a una gran altura de unos 10 000 pies. Ambos animales tienen estilos de vida diferentes a los de otros mamíferos previamente estudiados. El estudio de estos dos animales ofrecerá más información sobre la existencia del puente miodural en los mamíferos. Se realizó una disección anatómica macroscópica para observar las conexiones entre los músculos profundos del cuello y la duramadre a nivel del espacio atlanto-occipital. Las estructuras existentes se analizaron mediante técnicas de tinción histológica convencionales y especiales. Las regiones suboccipitales en murciélagos y musarañas arbóreas presentaban el músculo recto dorsal mayor de la cabeza (RCDma), el recto dorsal menor de la cabeza (RCDmi), el oblicuo anterior de la cabeza (OCA) y el oblicuo posterior de la cabeza (OCP). El tejido conjuntivo denso conecta el RCDmi con la membrana atlanto- occipital posterior (PAOM) y esta última con la duramadre espinal. El puente miodural en estos mamíferos comparte una estructura similar al puente miodural en humanos. Los análisis histológicos confirmaron que las fibras conectivas del puente miodural son principalmente fibras de colágeno tipo I. Esto demuestra además que el puente miodural existe ampliamente en la anatomía normal de los mamíferos. Esta investigación proporciona apoyo morfológico para un estudio anatómico comparativo de la función fisiológica del puente miodural.

Super-Resolution Track-Density Imaging Reveals Fine Anatomical Features in Tree Shrew Primary Visual Cortex and Hippocampus / 神经科学通报·英文版

Diffusion-weighted magnetic resonance imaging (dMRI) is widely used to study white and gray matter (GM) micro-organization and structural connectivity in the brain. Super-resolution track-density imaging (TDI) is an image reconstruction method for dMRI data, which is capable of providing spatial resolution beyond the acquired data, as well as novel and meaningful anatomical contrast that cannot be obtained with conventional reconstruction methods. TDI has been used to reveal anatomical features in human and animal brains. In this study, we used short track TDI (stTDI), a variation of TDI with enhanced contrast for GM structures, to reconstruct direction-encoded color maps of fixed tree shrew brain. The results were compared with those obtained with the traditional diffusion tensor imaging (DTI) method. We demonstrated that fine microstructures in the tree shrew brain, such as Baillarger bands in the primary visual cortex and the longitudinal component of the mossy fibers within the hippocampal CA3 subfield, were observable with stTDI, but not with DTI reconstructions from the same dMRI data. The possible mechanisms underlying the enhanced GM contrast are discussed.

Atlas of the Striatum and Globus Pallidus in the Tree Shrew: Comparison with Rat and Mouse / 神经科学通报·英文版

The striatum and globus pallidus are principal nuclei of the basal ganglia. Nissl- and acetylcholinesterase-stained sections of the tree shrew brain showed the neuroanatomical features of the caudate nucleus (Cd), internal capsule (ic), putamen (Pu), accumbens, internal globus pallidus, and external globus pallidus. The ic separated the dorsal striatum into the Cd and Pu in the tree shrew, but not in rats and mice. In addition, computer-based 3D images allowed a better understanding of the position and orientation of these structures. These data provided a large-scale atlas of the striatum and globus pallidus in the coronal, sagittal, and horizontal planes, the first detailed distribution of parvalbumin-immunoreactive cells in the tree shrew, and the differences in morphological characteristics and density of parvalbumin-immunoreactive neurons between tree shrew and rat. Our findings support the tree shrew as a potential model for human striatal disorders.

Receptor for Hepatitis B and D Virus / 대한내과학회지

Chronic hepatitis B affects 400 million people worldwide and is one of the leading causes of liver-related morbidity and mortality. All clinically available hepatitis B virus (HBV) drugs are nucleoside or nucleotide analogs that inhibit viral reverse transcriptase (RT) activity. Resistance to these HBV drugs has been widely reported, and is due to specific mutations in the viral RT domain. Therefore, the development of new, non-polymerase targeting anti-HBV agents is urgently needed. A potential drug target, the HBV receptor that mediates the viral entry process, has been recently identified using human primary hepatocytes, northern tree shrew (Tupaia belangeri) hepatocytes, and HepaRG cells. A transporter of bile acids, sodium taurocholate cotransporting polypeptide (NTCP), was identified as the receptor for HBV and hepatitis D virus, and the transport function of NTCP was correlated with HBV entry. Therefore, functional inhibitors of NTCP may inhibit HBV infection, and viral entry was blocked by several NTCP receptor-targeting compounds. The HBV receptor is an attractive target for development of entry inhibitors, and serves as a model for the mechanistic study of HBV entry and infection. This review will summarize the characteristics and clinical importance of NTCP, and will discuss the potential therapeutic use of NTCP inhibitors to prevent HBV entry.

Metabolomics and proteomics approaches to characterize and assess proteins of bear bile powder for hepatitis C virus / 中国天然药物

Metabolomics represents an emerging and powerful discipline that provides an accurate and dynamic picture of the phenotype of bio-systems through the study of potential metabolites that could be used as therapeutic targets and for the discovery of new drugs. Hepatitis C virus (HCV) is a leading cause of liver disease worldwide, and is a major burden on public health. It is hypothesized that an animal model of HCV infection would produce unique patterns of endogenous metabolites. Herein, a method for the construction of efficient networks is presented with regard to the proteins of bear bile powder (PBBP) that protect against HCV as a case study. Ultra-performance liquid chromatography, coupled with electrospray ionization/quadrupole-time-of-flight high definition mass spectrometry (UPLC-HDMS), coupled with pattern recognition methods and computational systems analysis were integrated to obtain comprehensive metabolomic profiling and pathways of the large biological data sets. Among the regulated pathways, 38 biomarkers were identified and two unique metabolic pathways were indicated to be differentially affected in HCV animals. The results provided a systematic view of the development and progression of HCV, and also could be used to analyze the therapeutic effects of PBBP, a widely used anti-HCV medicine. The results also showed that PBBP could provide satisfactory effects on HCV infection through partially regulating the perturbed pathway. The most promising use in the near future would be to clarify the pathways for the drugs and obtain biomarkers for these pathways to help guide testable predictions, provide insights into drug action mechanisms, and enable an increase in research productivity toward metabolomic drug discovery.

Expression of epidermal fatty acid-binding protein in cross-species hepatocellular carcinoma / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To evaluate the utility of the cross-species screening strategy for investigating key molecule(s) involved in onset and progression of hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>HCC-related molecule data from our previous studies and in the literature were collected to establish a cross-species dataset. Tissue samples of HCC, non-HCC surrounding liver (para-HCC), and normal liver that were collected from humans, tree shrews and rats. The genes reported to have the most differential expression in HCC were verified by analyzing the mRNA and protein levels by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively.</p><p><b>RESULTS</b>The cross-species dataset of HCC-related molecules included four genes: epidermal fatty acid-binding protein (E-FABP), liver (L)-FABP, tyrosine a-ketoglutarate transaminase (TKT), and cytokeratin (CK8). In humans, E-FABP mRNA expression was significantly higher (P less than 0.05) in HCC (0.87+/-0.14 vs. para-HCC: 0.64+/-0.12 and normal liver: 0.67+/-0.07; F=20.910). Similar results were obtained in tree shrew (HCC: 0.87 +/- 0.25 vs. para-HCC: 0.73 +/- 0.19 and normal liver: 0.68+/-0.19; F=3.807) and rat (HCC: 0.97+/-0.22 vs. para-HCC: 0.78+/-0.16 and normal liver: 0.80 +/- 0.13; F=4.482). The Western blotting analyses revealed a similar statistically significant trend.</p><p><b>CONCLUSION</b>The cross-species screening strategy for tumor genes may represent a feasible and convenient process of identifying key molecule(s) for human HCC. E-FABP may be a particularly crucial molecule for hepatocarcinogenesis.</p>

Primary culture and purification of cerebral astrocyte of tree shrew / 生理学报

The aim of this study is to establish a method to culture and purify cerebral astrocyte of tree shrew (Tupaia belangeri), a kind of new laboratorial animal which is a relative of primates. Newborn tree shrews were used in this experiment. The cortex of cerebrum was isolated and placed in 4°C for 20 min to injure neurons. The cortical tissue was disaggregated by trypsin digestion. Differential attachment method was used to remove fibroblasts. The mixed culture was rinsed by trypsin (0.005%) solution to remove neurons. Upon reaching 70% confluence, the culture was subjected to static trypsin digestion until a white slice film exfoliated from the bottom of culture bottle. This film, i.e. astrocyte layer, was taken out and cultured, and the third passage was identified by immunocytochemical staining and immunofluorescence with anti-glial fibrillary acidic protein (GFAP) antibody. The result showed the purity of tree shrew astrocytes was more than 98%. Thus the method to culture highly purified astrocyte of tree shrew was successfully established, which would contribute to further study in central nervous system physiology and diseases in this new laboratorial animal.

Long-term observation of hepatitis B virus (HBV) replication in new-born tree shrews inoculated with HBV / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To observe the hepatitis B virus (HBV) replication in the tree shrews that were inoculated with HBV at neonatal period.</p><p><b>METHODS</b>Six new-born tree shrews were inoculated with human HBV positive serum. Blood samples and liver biopsies were collected at different time points after inoculation. The HBV infection markers were tested by nested polymerase chain reaction (nPCR), fluorescence quantitative polymerase chain reaction (FQ-PCR), Southern blot, ELISA and immunohistochemistry staining. The liver tissues were observed under electron and light microscope.</p><p><b>RESULTS</b>48 weeks after inoculation, HBV DNA and HBV cccDNA were detected in the serum and liver samples of three animals (number 1, 2 and 6) by nPCR. The copy-numbers of HBV DNA detected by FQ-PCR in their serum and liver samples were 103 and-104/ml respectively,and the total DNA in 1microg liver tissue was 107-108. Southern blot indicated that HBV replication intermediates such as HBV cccDNA and HBV ssDNA was detectable in liver tissues. HBsAg was detected by ELISA, and immunohistochemical staining showed a gradual increase of HBsAg-positive liver cells. High copy number of HBV DNA and suspected HBV EM particles could be detected in the liver samples from one of the three animals that have survived more than 2 years after inoculation. The other three animals showed low HBV DNA copy number, and the rest of the signs of HBV infection were negative or transiently positive.</p><p><b>CONCLUSIONS</b>Neonatal tree shrews can be infected with human HBV. HBV can replicate inside the liver cells of tree shrew.</p>

Improving effect of Ginkgolide B on mitochondrial respiration of ischemic neuron after cerebral thrombosis in tree shrewa / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>It has been known that platelet activating factor receptors (PAFR) may mediate many acute pathological responses and that PAFR antagonist Ginkgolide B (GB) possesses multiple effects, but the actions of GB on PAFR affinity and mitochondrial respiration in the ischemic neuron were unclear until now. This study explored the possible effects of GB on PAFR and the mitochondrial respiration of the neuron in the ischemic microenvironment.</p><p><b>METHODS</b>Thrombotic cerebral ischemia in tree shrews was induced by a photochemical reaction; changes in the regional cerebral blood flow (rCBF, using (99m)Tc tracer technique), the brain water content (specific gravimetric method), PAFR (3H-labelled PAF assay), the respiratory control rate (RCR), the phosphorus-oxygen (P/O) ratio of mitochondrial respiration (Clark oxygen electrode), mitochondrial permeability transition (MPT) pore, and the mitochondrial ultrastructure in the ischemic neurons were also observed. Data were compared between the two groups (the ischemia group vs the sham group, and the ischemia group vs the GB group).</p><p><b>RESULTS</b>There were high affinity and low affinity sites for PAFR on the tree threws' brain cell membranes. The varying-affinity PAFR binding sites, the respiration state III, the state IV, RCR, the P/O ratio of the mitochondria, and the rCBF all decreased markedly (respectively, P < 0.01 and P < 0.05), but the water content increased (P < 0.01) in the ischemia group after the application of cerebral thrombosis. In tree shrews treated with GB (5 mg/kg i.v.) 6 hours after photochemical reaction, their PAFR binding sites and respiratory state increased markedly. The rCBF gradually increased and the brain edema ameliorated (P < 0.01) at 24h after cerebral ischemia. There were significant differences between the ischemia group and sham group (P < 0.01). In GB treated isolated neurons' mitochondria, with or without cerebral ischemia, the energy metabolism of the mitochondria had not been changed.</p><p><b>CONCLUSIONS</b>The activation of the PAFR may play an important role in the inhibition of the mitochondrial respiration and the induction of neuronal damage after cerebral thrombosis; however, GB possesses neuroprotective effects by improving mitochondrial metabolism.</p>

The expression of peroxiredoxin II in hepatocellular carcinoma and its significance / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To evaluate the mRNA and protein expressions of peroxiredoxin II (PrxII) in hepatocellular carcinoma (HCC) and their significance.</p><p><b>METHODS</b>HCC was induced by aflatoxin B1 (AFB1) in 6 tree shrews (Tupaia belangeri chinensis). The expression levels of PrxII mRNA and protein were detected by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot on HCC tissues and on their surrounding liver tissues (para-HCC). Biopsied liver tissues were taken before the HCC induction (pre-HCC) from the same animals and from a group of blank controlled animals that served as controls. Liver biopsy specimens from 18 cases of human HCC and from 17 healthy human volunteers were studied using the same methods.</p><p><b>RESULTS</b>The mRNA and protein expressions of PrxII in tree shrew HCC tissues were significantly higher than those in para-HCC and pre-HCC tissues, and also higher than those in the liver tissues from the control animals (all P < 0.05). The expression levels of PrxII mRNA and protein in human HCC tissues were also significantly higher than those in their para-HCC tissues and in the human normal liver tissues (P < 0.05).</p><p><b>CONCLUSION</b>PrxII might play an important role in hepatocarcinogenesis and might be used as a molecular target for HCC prevention and treatment.</p>

A cDNA microarray study of the differential expression of genes in signal transduction pathway during hepatocarcinogenesis in tree shrews / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To study the differential expression of genes in signal transduction pathway (STP) during the hepatocarcinogenesis in tree shrews induced by AFB1 and/or HBV and to elucidate the molecular mechanism of hepatocellular carcinoma (HCC) development.</p><p><b>METHODS</b>Adult tree shrews were divided into three groups: Group A was fed AFB1 only, Group B was infected firstly with HBV then fed AFB1 as in Group A, Group C served as the normal control. Liver biopsies were obtained at the 30th, 60th and 90th week of the experiment or until HCC occurred and the animals were sacrificed. Tree shrew-specific cDNA microarray was applied for detecting the differential expression of corresponding genes in each group at different time points during the experiment, and real time RT PCR was applied to verify the results of the cDNA microarray.</p><p><b>RESULTS</b>Genes of IGF-II, C-rel, and NF-kappaB2 were differentially expressed between para-cancerous tissues and HCC tissues in both group A and group B, and the differential expression of bcl-2, cyclin A and CNTF was only seen in group B. Between the experimental groups A and B and the control group C, there were differential expressions of CNTF and cyclin A in the early 30th week and middle 60th week stage of hepatocarcinogenesis in tree shrews. Real time RT PCR results showed that the expression level of IGF-II and C-Rel in group A and of IGF-II in group B in HCC tissues were significantly lower than that in the adjacent non-cancerous tissues and in the biopsies taken at the 30th and 60th week of the experiment. Nevertheless, there were no significant differences between the para-cancerous tissues and the cancer tissues at the 30th and 60th week. These results were consistent with the cDNA microarray assay. The expression levels of C-Rel and CNTF in group B were not obviously altered in the para-cancerous tissues, HCC and at the 60th week, but they were significantly lower in these tissues than that in the tissues at the 30th week. In group A, the expression levels of CNTF in adjacent liver and HCC tissues were higher than that in para-cancerous lesions, but the difference did not reach a statistically significant level. In group C, the expression level of IGF-II, C-Rel and CNTF at different stages showed no significant differences, which was consistent with the cDNA microarray results.</p><p><b>CONCLUSIONS</b>To apply the tree shrew-specific cDNA microarray to detect the differential expression of genes related to signal transduction pathway during tree shrew hepatocarcinogenesis could be a valuable utility for further comprehending the mechanism of HCC. IGF-II, NF-kappaB2, C-rel, Bcl-2, and cyclin A. CNTF may be involved in the occurrence and progress of HCC in tree shrews.</p>

Seroprevalence of rickettsial infection in commensal rodents and shrews trapped in the Bangkok Metropolitan Area.

Murine typhus and scrub typhus are important human rickettsial diseases in Thailand. Small mammals, including many species of rodents and shrews, serve as the reservoir host of rickettsial diseases. Rickettsia typhi can be transmitted to humans by fleas causing murine typhus, while infection with Orientia tsutsugamushi causing scrub typhus in humans is transmitted by chiggers. The prevalence of rickettsial infection depends on the geographic area. The seroprevalence of antibody to R. typhi and O. tsutsugamushi was studied in commensal rodents and shrews trapped in markets in the Bangkok Metropolitan Area (BMA). R. typhi and O. tsutsugamushi antigen prepared in the yolk sac of embryonated eggs were used to determine the specific antibody in trapped animals' sera by using fluorescein isothiocyanate (FITC)-anti rat immunoglobulins as a second antibody. Antibody to R. typhi was found in 25 (5%) of 500 sera tested and no antibody to O. tsutsugamushi was detected. R. typhi antibody titer ranged from 40-1280 and was found in Rattus norvegicus (4.2%), Rattus rattus (0.4%), Rattus exulans (0.2%), and Mus musculus (0.2%) trapped in 8 of 47 markets in the BMA. R. typhi antibody was commonly found in R. norvegicus. The authors concluded that murine typhus is an important rickettsial disease and R. norvegicus is an important reservoir species of rodents found in markets of the BMA.

Cloning and characterization of cholesteryl ester transfer transfer protein isolated from the tree shrew / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To obtain the nucleotide sequence and deduced amino acid sequence of cholesteryl ester transfer protein (CETP) cDNA from the tree shrew (Tupaia glis).</p><p><b>METHODS</b>The cDNA sequence of the tree shrew CETP was obtained by utilizing the technique of switching mechanism at 5' end of RNA transcript (SMART) and rapid amplification of cDNA end (RACE) from the first strand of the cDNA. The amino acid sequence of CETP was deduced from the cDNA sequence and its primary and secondary structures were predicted.</p><p><b>RESULTS</b>The sequence of CETP cDNA from tree shrew (GenBank accession number AF334033) covers 1636 bp, including 178 bp at the 3' end of the untranslated region and a 1458 bp fragment in a coding region, which provides the complete sequence of mature tree shrew CETP, although not the initiator methionine. The first 24 bp encodes a partial signal peptide. The mature protein consists of 477 amino acids and is longer than the human version by one amino acid (Gly318). Comparing this amino acid sequence with those of other animals' CETPs, the identity between tree shrew and human and rabbit CETP is 88% and 82%, respectively. The protein is extremely hydrophobic as it contains many hydrophobic residues, especially at the C-terminal, consistent with its function in the transfer of neutral lipids. The amino acid residues concerning with binding and transferring neutral lipids are highly conserved. There is a deletion of an N-linked glycosylation site at Asn342 in the tree shrew CETP protein that may participate in the removal of peripheral cholesterol and cholesteryl ester by increasing its activity of transferring cholesteryl ester.</p><p><b>CONCLUSION</b>The possible glycosylation in the tree shrew CETP may be involved in the molecular mechanism of its insusceptibility to atherosclerosis.</p>

Different gene expression during hepatocarcinogenesis in tree shrew induced by aflatoxin B1 / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To understand the molecular mechanism and find out the responsible genes for liver cancer by exploring the regulation of gene expression during hepatocarcinogenesis in tree shrew induced by aflatoxin B1 (AFB1).</p><p><b>METHODS</b>The tissues from tree shrew of different stages during the pathogenesis and development of hepatocellular carcinoma (HCC), liver cancer tissue, para-cancerous tissues, pre-cancerous liver tissues, liver tissues of the same stage from normal controls and the liver tissues taken before AFB1-treatment were analyzed for gene expression by cDNA array.</p><p><b>RESULTS</b>Four patterns of gene expression were observed during AFB1-induced hepatocarcinogenesis. They were: genes up-regulated in HCC tissue and para-cancerous tissue, especially in HCC tissues; genes with similar expressing level in both HCC tissue and para-cancerous tissue, but higher than that in pre-cancerous tissue; genes down-regulated in HCC tissue; genes up-regulated before HCC appeared but down-regulated after HCC appeared.</p><p><b>CONCLUSION</b>Dynamic observation of gene expression will be beneficial to elucidate the mechanisms of AFB1- induced hepatocarcinogenesis and locate the responsible genes.</p>

Alteration of p53 gene during tree shrews' hepatocarcinogenesis / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To detect the expression and variation of p53 gene during tree shrews' hepatocarcinogenesis induced by hepatitis B virus (HBV) and aflatoxin B1 (AFB1).</p><p><b>METHODS</b>Tree shrews were divided into four groups: the tree shrews were infected with HBV and fed with AFB1 in group A, only infected with HBV in group B, fed with AFB1 alone in group C, and normal control in group D. All the tree shrews were performed liver biopsy every 15 weeks. The tissues of liver and tumor were detected by immunohistochemistry and molecular biotechnologies.</p><p><b>RESULTS</b>(1) The incidence of hepatocellular carcinoma (HCC) in group A (66.7%) was higher than that in Group B and C (30%). HCC appearance in group A was earlier than that in group C (120.0 weeks +/-16.6 weeks vs 153.3 weeks +/-5.8 weeks, t = 3.336, P<0.01). (2) Mutated p53 protein was not found before the 75th week of the experiment in each group. (3) At the 105th week, the expression rates of mutated p53 protein were 78.6%, 60% and 71.4% in group A, B and C respectively, which were much higher than that (10%) in group D (x2 > or = 5.03, P<0.05). An abnormal band of p53 gene was detected in both group A and C. (4) The mutation points of p53 gene in liver cancer of tree shrew were at codon 275, 78 and 13. The nucleotide sequence and amino acids sequence of tree shrew's wild-type p53 showed 91.7% and 93.4% homology with those of human p53 respectively.</p><p><b>CONCLUSIONS</b>There is a remarkable synergistic effect between HBV and AFB1 on HCC. Mutated p53 protein is expressed before HCC occurrence, which promotes the development and progress of HCC. HBV and AFB1 may synergistically induce p53 gene mutation.</p>

Serial pathologic changes in livers of Tree shrews and Macaca assamensises infected with human Hepatitis B virus / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To serially observe the pathologic changes in livers of tree shrews and macaca assamensises infected with HHBV.</p><p><b>METHODS</b>10 adult tree shrews and 28 macaca assamensises were inoculated with HBV rich human sera. The liver of the animals were regularly biopsied. The liver samples were examined histopathologically by HE staining. Some samples were stained for HBsAg by immunohistochemistry (IH), and HBV DNA by in situ hybridization (ISH).</p><p><b>RESULTS</b>HBsAg in 80% of tree shrews infected with HHBV can be detected by IH, HBV DNA in 50% of those can be found by ISH.The positive rates of HBsAg in macaca assamensises' livers were 25% by IH, none HBV DNA was detected.</p><p><b>CONCLUSION</b>The tree shrew model seems to be applicable for the research of human hepatitis B.</p>

Human hepatitis B virus infection of tree shrews and Macaca assamensis in vivo / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To examine sensitivity of the tree shrews and Macaca assamensis to human hepatitis B virus (HHBV) by serologic methods.</p><p><b>METHODS</b>Totally 233 tree shrews and 28 Macaca assamensis were inoculated with human sera containing HBV. After inoculation, the sera were collected weekly from them and HBV markers were detected with HBV ditecting ELISA kits.</p><p><b>RESULTS</b>Ninety percent of the tree shrews developed acute infection, among them, 44.4 % persisted for over one year, 33.3% of them developed chronic infection persisted for 2 years and one month; the persistence of HBV in Macaca assamensis was much shorter.</p><p><b>CONCLUSION</b>These data clearly indicated that tree shrew may be used as an animal model for study of chronic HBV infection, whereas, Macaca assamensis, showed only a transient sensitivity to HHBV.</p>

Analysis of lecithin-cholesterol acyltransferase cDNA and protein sequence from tree shrew / 中国医学科学院学报

<p><b>OBJECTIVE</b>To acquire cDNA sequence of lecithin-cholesterol acyltransferase (LCAT) from tree shrew and analyze the sequence structure.</p><p><b>METHODS</b>The first strand cDNA was acquired by reverse transcription using mRNA from tree shrew liver as template. By the method of SMART RACE PCR, tree shrew LCAT cDNA was acquired and deduced its amino acids sequence. The sequence and structure of tree shrew LCAT cDNA and amino acid were analyzed and predicted by the molecular software.</p><p><b>RESULTS</b>Tree shrew LCAT cDNA is composed of 1,340 bp, including 2 bp 5' untranslated region (5' UTR), 1,320 bp open reading frame (ORF) which encodes protein precursor of 440 amino acids (24 amino acids signal peptide and 416 amino acids mature peptide), and 18 bp 3' untranslated region (3'UTR). The stop codon is TAA and there is a poly (A) signal sequence AATAAA and a 25 bp poly (A) tail. Tree shrew LCAT cDNA sequence has been accepted by GenBank as a new gene, accession number AF272861 and its homology with human and baboon was 90% and 89%, respectively.</p><p><b>CONCLUSION</b>The sequence of LCAT cDNA in tree shrew has high identity with that of human and other experimental animal species.</p>

Expression of p53 gene in hepatocellular carcinomas induced by aflatoxin B1 with or without human hepatitis B virus in tree shrews

Using tree shrew as an animal model, our previous studies have demonstrated synergistic effects of aflatoxin B-1 (AFB(1)) and human hepatitis B virus (HHBV) in the induction of hepatocellular carcinoma (HCC). In the present study, we have examined expression of p53 gene in HCCs induced by AFB(1) with or without HHBV infection in tree shrews. Avidin-biotin-peroxidase complex immunohistochemical method with human p53-CM1 polyclonal antibody has been used to detect p53 expression in serial sections of paraffin-embedded liver and HCC tissues. Five out of 9 animals with HCCs (55.6%) induced by AFB(1) with HHBV infection and 2/3 animals with HCCs (66.7%) induced by AFB(1) alone expressed the p53 protein. Out of 18 HCCs examined, expression of p53 protein was observed in 9/10 moderately and poorly differentiated HCCs (0/8). None of the well differentiated HCCs (0/8) expressed p53 (0%). Similarly, no p53 expression was observed in either non-tumorous or hyperplastic liver tissues or nodules. These results suggest that p53 expression associated with p53 mutation is a late event occurring probably during tumor progression in AFB(1) and HHBV induced hepatocarcinogenesis in the tree shrew. This report is the first example of an experimental animal model where combination of human HBV and AFB(1)-induced HCCs demonstrate p53 expression.

Digenetic trematodes from rats, squirrels and tree shrews in Malaysia.

Neodiplostomum (Conodiplostomum) Brachylaima, Ectosiphonus and Euparadistomum are reported for the first time from small mammals in Malaysia. New host and locality records are given for Echinostoma, Achillurbainia, Beaveria, Odeningotrema, Leipertrema, Athesmia, Skrjabinus and Zonorchis. Possible-life-cycles of the parasites are discussed in relation to the ecology and feeding habits of the hosts.