Anticancer treatment of endostatin gene therapy by targeting tumor neovasculature in C57/BL mice

Antiangiogenesis strategy has been widely recognized as a viable approach to fight cancer. Considering the high cost and inconvenience of protein therapy of endostatin (ES), which is a potent antiangiogenic protein, we attempted to explore the inhibitory effect of ES gene therapy on tumor growth and metastasis. In this experiment, Lewis lung carcinoma (LLC)-bearing C57/BL mice were used to evaluate the antitumor effect of ES gene therapy and its impairment of tumor neovasculature. The data showed that the ectopic ES in circulation expressed by intramuscular administration of formulated ES-encoding plasmid DNA significantly suppressed primary tumor growth and lung metastasis in LLC-bearing C57/BL mice. Hence, our results demonstrated the inhibitory effect of ES gene therapy on angiogenesis-dependent tumor growth and metastasis.

Structure of dental glass-ionomer cements by confocal fluorescence microscopy and stereomicroscopy

The microstructure of four cements, setting by different mechanisms (acid-base, dual cure, triple cure), was studied. The porosity of unpolymerized materials was detected by stereomicroscopy. After polymerization and storage in water or lactic acid solution, the porosity, filler distribution and gel layer, which was formed at the filler/matrix interface of polymerized materials, were examined by confocal laser microscopy. For this purpose, the specimens were treated with fluorescent dye solution before the test. The results showed that hydrolytic degradation (pH 7) mainly involved the resin matrix, and the acid erosion (pH 3.5) involved the gel layer too. As regards the filler, materials with different setting mechanism released the glass particles in different times. The loss of the filler particles occurred quicker in acid-base setting cements, and slower in triple-cured material.

Molecular dynamics study of aquaporin-1 water channel in a lipid bilayer

The aquaporin-1 water channel was modeled in a palmitoyl-oleoyl-phosphatidyl-choline lipid bilayer, by means of molecular dynamics simulations. Interaction of the protein with the membrane and inter-monomer interactions were analyzed. Structural features of the channel important for its biological function, including the Asn-Pro-Ala (NPA) motifs, and the diffusion of water molecules into the channels, were investigated. Simulations revealed the formation of single file water inside the channels for certain relative positions of the NPA motifs.

[Cloning and phylogenetic analysis of hepatitis-associated TT virus subgenome]

Polymerase chain reaction (PCR) was utilized for the DNA amplification from transfusion transmitted virus (TTV) positive serum samples. Five TTV DNA fragments, overlapped about 90% of the genome, were amplified by long template PCR for the generation of TTV subgenome. Recombinant plasmids were obtained by directly inserting PCR products into pT-Adv vector, and DNA sequence analyses showed they were TTV DNA fragments. By using specific restriction enzymes, five TTV DNA fragments were ligated into a TTV DNA subgenome clone and named as TTV021. TTV021 has been deposited in GenBank database with the accession number AF254410. The results of computer analyses showed that TTV021, 3472 nt long, contains two open reading frames (ORF1, 785 aa; ORF2, 146 aa). Identity alignments between TTV021 and other TTV isolates indicated several high conserved regions existed. Phylogenetic analysis of 356 nt from TTV021 suggested that the isolate has close evolutionary relationship with CHN1 (type 1a), but has far relation with other TTV isolates.

[In vitro cotransfer human multidrug resistance gene (mdr-1) and dihydrofolate reductase gene (DHFR) into human CD(34)(+) progenitor cells to broaden the spectrum of drug resistance]

OBJECTIVE

To explore the feasibility of cotransferring human mdr-1 gene and DHFR gene into human CD(34)(+) progenitor cells to broaden the spectrum of drug resistance and improve the tolerance of myelosuppression following combination chemotherapy.

METHODS

The recombinant retroviral vector pSF-DIM containing mdr-1 and DHFR (L22Y) gene was constructed by introducing IRES sequence into vector FMCF which enable highly efficient gene expression in early hematopoietic cells. The retrovirus titers were raised by repeated supernatant cross infection between the amphotropic and ectropic retroviral packaging cells. Human CD(34)(+) progenitor cells were transduced by supernatant infection. Expression of P-gp was detected by flow cytometry. Integration of the foreign drug resistance gene in CD(34)(+) cells was determined by PCR. Drug resistance was evaluated by CFU-GM assay.

RESULT

Integration of the two foreign drug resistance genes was detected in the CD(34)(+) cells after pSF-DIM transduction. Compared with the untransduced group, the expression of P-gp elevated by 10.98% after gene transduction and the CFU-GM yields were significantly increased at 48 nmol/L of MTX and 10 ng/ml or 12 ng/ml of taxol (P < 0.05).

CONCLUSION

The retroviral vector pSF-DIM can mediate mdr-1 and DHFR gene integration and co-expression in human hematopoietic progenitor cells so as to broaden the spectrum of drug resistance.

[Apoptosis-related genes cloned by improved subtractive hybridization]

OBJECTIVE

To clone apoptosis-related genes induced by all-trans retinoic acid (ATRA) from human breast cancer cell line MCF-7, and to analyze the association between the cloned genes and apoptosis.

METHODS

An apoptotic cell model of MCF-7 cells was constructed with ATRA induction. The apoptosis-related genes were cloned by improved PCR-based subtractive hybridization.

RESULTS

Twelve differentially expressed clones were screened out. After exclusion of false positive clones by reverse dot blotting, 5 clones containing fragments of 0.5-1.5 kb were sequenced. The results of sequencing were compared with BLAST. A novel gene, named apmcf-1, coding for 47 amino acids was identified. This gene was accepted by GenBank, (Accession number: AF141882). The result of reverse dot blotting showed that it was related to apoptosis. The other 4 genes were already known. Three of them were related to apoptosis as previously reported. Two of them, hsp-90 and rb-L3, had little information about their relationship with apoptosis.

CONCLUSION

ATRA-induced tumor cell apoptosis is a complex process with multiple genes involved.

cDNA transfection of amino-terminal fragment of urokinase efficiently inhibits cancer cell invasion and metastasis

Focusing of urokinase-type plasminogen activator (uPA) to the cell surface via binding to its specific receptor (uPAR, CD87) is critical for tumor invasion and metastasis. Consequently, the inhibition of uPA-uPAR interaction on the cell surface might be a promising anti-invasion and anti-metastasis strategy. We examined the effects of cDNA transfection of the human uPA amino-terminal fragment (ATF) on invasion and metastasis of cancer cells. First, a highly metastatic human lung giant-cell carcinoma cell line (PG), used as the target cell for evaluation of this effect, was demonstrated to express both uPA and uPAR. Then, ATF, which contains an intact uPAR binding site but is catalytically inactive, was designed as an antagonist of uPA-uPAR interaction and was transfected into PG cells. [(3)H]-Thymidine incorporation and cell growth curves indicated that expressed ATF did not affect the proliferation of transfected cells. However, analysis by scanning electron microscopy revealed that ATF changed the host cells from the typical invasive phenotype to a noninvasive one. Correspondingly, the modified Boyden chamber test in vitro showed that ATF expression significantly decreased the invasive capacity of transfected cells. Furthermore, in the spontaneous metastasis model, it was confirmed in vivo that expressed ATF remarkably inhibited lung metastasis of implanted ATF-transfected PG cells. In summary, autocrine ATF could act as an antagonist of uPA-uPAR interaction, and ATF cDNA transfection could efficiently inhibit the invasion and metastasis of the cancer cells. Inhibition of uPA-uPAR interaction on the cell surface might be a promising anti-invasion and anti-metastasis strategy.

[Experimental study of anti-metastasis effect of urokinase amino-terminal fragment gene on human breast cancer cells]

OBJECTIVE

To explore the suppressive effects of urokinase amino-terminal fragment (ATF) gene on metastatic potential of human breast cancer cell line MCF-7.

METHODS

A pcDNA3-ATF plasmid containing ATF cDNA under CMV promotor/enhancer control was constructed and transfected into MCF-7 cells by lipofectin. The expression of of uPA/uPAR and ATF in MCF-7 cells were analyzed by RT-PCR and Western blot. The effect of ATF expression on invasiveness in vitro, tumorigenesis and metastasis in vivo of MCF-7 cell was investigated.

RESULTS

MCF-7 cells displayed an overexpression of uPA/uPAR. Expression of ATF was detected after ATF gene-transfection. The invasive capacity of ATF gene-transfected MCF-7 cells was decreased significantly. Although the tumorigenesis was not affected, the in vivo metastasis of ATF gene-transfected MCF-7 cells was remarkably inhibited.

CONCLUSION

Suppression of invasiveness and metastasis of ATF-transfected MCF-7 cells is perhaps due to a competitive inhibition of interaction with endogenous uPA/uPAR.

[Study on the epidemiological feature and control measure for rabies from 1990 to 2000 in Jiangsu province]

OBJECTIVE

To analyze the epidemiological feature of rabies and explore the risk factors in Jiangsu for the control of rabies.

METHODS

Data on rabies in Jiangsu from Jan. 1990 to Sep. 2000, and on case studies as well as surveillance from 1998 to 2000, were collected. Circular distribution statistics and Chi-square test were used.

RESULTS

The number of rabies had been decreasing since 1990 yearly, but increased in the last two years. The new cases of rabies tended to focus in the area of Nantong, Yanchen and Taizhou city. There were about 80% of cases in the above areas. Dogs were the main hosts (93.22%). Ninety-four point nine two percent of the persons were affected through dog bites with major wounded part as thoracic limbs (46.27%). Rates of severe bites, being wounded close to the central nervous system and more than 1 wound per cases were significantly higher than that in the population under surveillance. The antibody conversion rate was 86.28% after immunization in the surveillance population. The immunization rate was 58.20% among dogs.

CONCLUSION

Severe deep bites, wounded part close to the central nervous system and more than 1 wound per case were the risk factors in patients with rabies. Maltreatment and low immunization rate were important risk factors as well.

[Homogeneity study on the Streptococcus suis isolated from human and swine]

OBJECTIVE

To identify S. suis and to evaluate the homogeneity of isolates of S. suis from human and swine.

METHODS

Culture, morphology, API biochemical tests and serum coagulate tests were used. All the 7 strains of streptococcus were confirmed to be S. suis serotype 2. Two strains and 1 strain were isolated from blood and cerebrospinal fluid (CSF) of patients, respectively, while the other 4 strains were obtained from the infected swine or their corpses. Seven strains of S. suis serotype 2 and reference strain SS2 were analyzed by randomly amplified polymorphic DNA analysis with six primers and Rep PCR with four primers and thalli fatty acid profile analysis. Cluster and principal compound analysis of results were performed with RAPD, Phylip and Treeview software.

RESULTS

By analysis on RAPD patterns, a close relationship among 7 strains of S. suis serotype 2 and reference strain SS2 was discovered. Human-born strains and swine-born strains exhibit similar RAPD patterns. There was a same clonal relationship between strains originated from the blood and CFS of the patients. These results were confirmed by thalli fatty acid profile to have genotypic and phenotypic identity.

CONCLUSION

Homogeneity exists among the 7 strains and reference strain SS2.

[Cloning of mouse endostatin and primary analysis on its biological activity]

The mouse endostatin cDNA was cloned by the total RNA of Chinese Kunming mouse liver as template with RT-PCR. The results of sequencing showed one base pair difference. The ctg was replaced by gtg(L22545 in GenBank) at position 278 base pair, causing the encoded amino acid from reported Val to Leu in this experiment. This new endostatin cDNA was registered in GenBank with an accession number of AF257775. The recombinant eukaryotic expression plasmid pSecTag2-ES was then constructed and transfected into COS-7 cells for transient expression. The results of testing by Western blotting showed an expression fragment in supernatants of pSecTag2-ES transfected COS-7 cells at 48 and 72 hours of transfection. Cultured HUVECs were used to detect the biological effect of supernatants in pSecTag2-ES transfected COS-7 after 48 hours of transfection. 3H incorporation assay showed an obvious inhibition of endothelial cell prolifetation. The results demonstrated primary that the cloned endostatin cDNA had biological activity.

Improved PCR-based subtractive hybridization strategy for cloning differentially expressed genes

An improved PCR-based subtractive hybridization strategy was used to clone apoptosis-related genes induced by all-trans retinoic acid (ATRA) from human promyelocytic leukemia cell line HL-60 cells. The protocol used the cap-finder method, long-distance PCR, streptavidin magnetic bead-mediated subtraction and spin column chromatography. Twenty-seven clones related to apoptosis were identified by reverse dot blot assay. Seventeen were known genes, of which seven have been reported to be apoptosis related. The remaining 10 were unknown genes, five of which were sequenced and named apr-1 to apr-5. apr-1, apr-2, apr-3 and TNF were reidentified by reverse dot blot, and it is suggested that they might be related to apoptosis. The results suggest that this strategy might be efficient for large-scale cloning of differentially expressed genes in target cells.

[Studies on human streptococcal infectious syndrome caused by infected pigs]

OBJECTIVES

To demonstrate the clinical manifestations of S. suis infectious syndrome; to study the characteristics of causative organism and its source.

METHODS

25 cases of unknown causes of food poisoning were identified in the central area of Jiangsu province, China in July 1998. Biological specimens was collected in some patients, and the causative organism was isolated using a number of different culture medium. Isolated organisms were identified by serum antibody tests, API biochemical tests, drug sensitivity tests and animal model experiments. The human born strains and the pig born strains were compared by RAPD technique. Epidemiological methods were applied to trace the source of causative organisms.

RESULTS

Cases were clinically categorized into two types: Streptococcal toxic shock syndrome (STSS) and streptococcal meningitis syndrome (SMS). Three strains of streptococci were isolated respectively from the blood and cerebrospinal fluid of 6 cases. All these 6 strains were confirmed to be S. suis type 2 by culture characteristics, morphology, biochemical characteristics, serum antibody tests and fatty acid profile analysis. Animal model experiment showed that these strains were sensitive to rabbits and pigs, but not to rats. RAPD fingerprint test revealed an identity between human born and pig born strains.

CONCLUSIONS

The aetiological agent of these human cases was S. suis type 2. Human cases were contracted by direct contact with the infected pigs or the corpse of infected pigs.

[The expression and mechanism study of BMP in pleomorphic adenoma]

OBJECTIVE

One important pathological character of pleomorphic adenomas is that there is chorndriod component in the epithelial tumors. It is well known that bone morphogenetic protein (BMPs) plays important roles in the morphogenesis of hard tissue by inducing mesenchymal cells to differentiate into osteoblasts and chondroblasts in vivo. So we examined the expression of BMP and BMP2 mRNA in pleomorphic adenomas to study the pathological mechanism of chorndriod tissue formation.

METHODS

Using ABC immunohistochemistry method, 6 specimens of pleomorphic adenomas were examined with BMP antibody. Reverse transcriptase-polymerase chain reaction (RT-PCR) methods were developed for detecting BMP2 mRNA expression with special primers used to amplify the BMP2 cDNA mature domain fragment. The total RNA was extracted from frozen 6 specimens of pleomorphic adenoma and then reversed to cDNA by reverse transcription using AMV reverse transcriptase. PCR conditions were 94 degrees C for 20 seconds, 60 degrees C for 30 seconds, and 72 degrees C for 1 minute, 40 cycles, followed by extension for 30 minute at 72 degrees C. The reaction products were analyzed by electrophoresis.

RESULTS

BMP expression could be found in all of the specimens of pleomorphic adenoma examined by immunohistochemistry method. BMP2 RT-PCR product was detected in only 5 specimens that showed BMP2 mRNA existed in 5 specimens.

CONCLUSION

These results may be helpful to study the mechanism of pleomorphic adenoma. It is speculated that BMP secreted by tumor cells may play important roles in origin of osteoid tissue in pleomorphic adenoma by inducing neoplastic myoepithelial cells to differentiate to chondrocytes.

[Prospective study on the correlation factors of fetal macrosomia]

The increase of body weight in pregnancy women, 50 g oral glucose challenge test (50 g GCT), pregnant women and umbilicus vein blood insulin (INS), growth hormone (GH), glucose and neonate weight were measured in 110 pregnant women and their neonates were measured to explore the correlation factors of fetal macrosomia. The incidence of macrosomia was higher in pregnant women whose increased weight > or = 15 kg than those < 15 kg. 50 g GCT plasma glucose showed positive correlation with neonatal weight. Which was higher in the group of the fetal macrosomia than of the normal neonates. The results suggest that both the increasing weight of the pregnant women and the 50 g GCT are related parameters to predict fetal macrosomia. To prevent fetal macrosomia the diet should be limited in those who have had a high increasing body weight in pregnancy and appropriate intervention is required to those whose 50 g GCT are positive.

[The inhibition of prourokinase gene transfer on deposition of platelets on rabbit carotid artery intima]

OBJECTIVE

To observe the expression of pro-urokinase (proUK) gene in rabbit carotid artery transfected with replication-deficient adenovirus vector containing proUK gene (Ad/prouk) and the deposition of platelet on the same injured vessel.

METHODS

Ad/proUK (Ad/proUK, 3 x 10(10) pfu/ml) was injected into the right carotid artery locally. Wild type adenovirus (Ad) was locally injected into the left carotid artery as self-control. The expression of proUK gene was investigated by immunohistochemistry assay. After injury of the gene-transfected vessel by electric stimulation, the deposition of (111) In-labeled platelet was quantitatively observed. The thrombosis was observed with HE-stained vessel section.

RESULTS

There were lots of proUK granules in the endothelium of Ad/proUK gene-transfected vessel. The differences in (111) In-platelets deposition per gram dry weight vessel segment were significant between Ad/proUK and Ad transfected control vessels [(4.60 +/- 0.93) x 10(7)/g vs control (27.95 +/- 4.93) x 10(7)/g, P < 0.01)]. The HE-stained vessel section showed that there were only small thrombi in proUK gene-transfected vessel but massive thrombi almost blocked up the whole vessel in control vessel.

CONCLUSION

The proUK gene-transfected vessel can obviously inhibit (111) In-labeled platelet deposition on injured vessel and thus thrombosis.

Blood flow distribution in sorbent beds: analysis of a new sorbent device for hemoperfusion

A new polymer-based sorbent cartridge has been recently developed for enhancing middle molecule removal during hemodialysis. The cartridge (Betasorb, Renaltech, New York, USA) has been designed to be placed in series with the dialyzer in the blood circuit. It is therefore important to evaluate the distribution of flow into the blood compartment of the device in order to assess if the surface of the sorbent is utilized to the best. For this purpose, a special imaging technique was utilized. Cartridges were analyzed during a simulated in vitro circulation at 250 and 350 ml/min of blood flow and 25% and 40% hematocrit. Cartridges were placed in vertical position and a cross longitudinal section 1 cm thick was analyzed in sequence by a helical scanner. Dye was injected into the arterial inlet and the progressive distribution was evaluated by sequential densitometrical measures carried out automatically by the machine. The sequential images analyzed by the scanner demonstrated excellent distribution of the flow in the blood compartment with minimal difference between the central and the peripheral regions of the compartment. In particular the following flow velocity pattern could be observed under the different experimental conditions tested. We may conclude that the cartridge design is adequate and no channelling effects could be detected in the blood compartment. The flow distribution is slightly affected by changes in flow rate and hematocrit showing an optimal utilization of the available surface for molecule adsorption.

[Effects of local vibration on the levels of plasma endothelin and nitric oxide in rabbits]

In order to explore the effects of local vibration on plasma endothelin(ET) and nitric oxide (NO) and the relations with vibration-induced vascular impairment(VVI), plasma ET and NO levels of rabbits were measured after exposure to different vibration power and different exposure period. The results showed an increasing tendency in plasma ET levels, and a decreasing tendency in plasma NO levels in experiment groups, while lasting vibration exposure and enhancing vibration power. It suggested that local vibration could result in the increasing of plasma ET level and decreasing of plasma NO level, which might be one of the mechanisms of vibration-induced vascular impairment.

Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis

Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis.

BACKGROUND

Commonly used bioimpedance analysis (BIA) is insensitive to changes in peritoneal fluid volume. The purpose of this study was to show, to our knowledge for the first time, that a new segmental approach accurately measures extracellular fluid changes during peritoneal dialysis (PD).

METHODS

Fourteen stable PD patients were studied during a standard exchange with fluids of known conductivity. Bioimpedance was continuously measured in the arm, trunk, and leg and from wrist to ankle. Volume changes were calculated using both a newly developed sum of segmental BIA (SBIA) and current wrist-to-ankle BIA (WBIA) and were compared with actual volume changes measured gravimetrically.

RESULTS

When 2.19 +/- 0.48 L were removed from the peritoneal cavity during draining, 95.2 +/- 13.8% of this volume was detected by SBIA compared with only 12.5 +/- 24. 3% detected by WBIA. When 2.11 +/- 0.20 L of fresh dialysate was infused into the peritoneal cavity during filling, 91.1 +/- 19.6% of this volume was detected by SBIA compared with only 8.8 +/- 21.1% detected by WBIA.

CONCLUSION

The good agreement between measured and calculated data using SBIA was due to: (a) improved placement of electrodes, (b) estimation of trunk extracellular volume based on a new algorithm, and (c) consideration of changes in dialysate conductivity. Correct estimation of fluid volume in the trunk is a prerequisite for applications in which direct analysis of fluid changes cannot be performed such as with peritoneal equilibration tests and continuous flow PD.

[Application of IL-1 beta and 8 mRNA and some other indices in monitoring the activity of ulcerative colitis]

OBJECTIVE

To evaluate the monitoring action of the expression of IL-1 beta, IL-8 mRNA, myeloperoxidase (MPO) and superoxide dismutase (SOD) activity in the active ulcerative celitis (UC).

METHODS

Twenty active UC patients, 23 inactive UC patients; and 14 non-UC inflammation patients were selected. Twelve patients who complained of flatulence, abdominal pain and constipation receiving endoscopic examination were used as control. MPO and SOD activity, IL-1 beta and IL-8 mRNA expression (hybridization in situ) were determined on the endoscopic biopsy specimens of all patients. In 20 active UC patients, 14 patients received endoscopic examination and 4 indices detection were done once again after 2 months' treatment with prednisone and SASP.

RESULTS

Mucosal MPO activities of active UC patients, inactive UC patients, and non-UC inflammation patients are higher than those of control patients, (19.37 +/- 0.54, 11.59 +/- 1.41, and 12.97 +/- 0.49) U/g tissue vs (9.49 +/- 0.51) U/g tissue (P < 0.01). SOD activities are lower than that of control patients, (5.03 +/- 07,7. 7.66 +/- 0.79, and 6.98 +/- 0.61) U/mg protein vs (8.82 +/- 0.58) U/mg protein (P < 0.05). Mucosal MPO activity of active UC patients is also higher than that of inactive and non-UC inflammation patients (P < 0.01); while SOD activity is lower than them (P < 0.01). After 2 months' medical treatment, MPO activity of 14 active UC patients decreased, (12.61 +/- 0.74) U/g tissue vs (19.31 +/- 0.44) U/g tissue (P < 0.01), while SOD activity elevated (7.44 +/- 0.55) U/mg protein vs (5.10 +/- 1.05) U/mg protein (P < 0.05), compared with that of before treatment. Positive expression of IL-1 beta mRNA appeared in the epithelial and inflammatory cells of all active UC patients, 9 inactive UC patients, and 7 non-UC inflammation patients. While expression of IL-8 mRNA only appeared positively in all active UC patients. In 14 active UC patients, there were no detection of interleukin mRNA expression after 2 months' treatment.

CONCLUSIONS

Mucosal MPO, SOD, IL-1 beta, and IL-8 mRNA could be used as 4 indices monitoring the activity of UC. And IL-1 beta mRNA is also helpful to supervise early or late UC activity.

[Surveillance of hemorrhagic fever with renal syndrome and studies on its predictive indices in Jiangsu Province]

OBJECTIVE

To study its predictive significance of the direct use of surveillance data of hemorrhagic fever with renal syndrome (HFRS) collected in Jiangsu province, and find an indicator of choice for qualitative prediction.

METHODS

A correlation analysis between the HFRS incidence rate and surveillance data collected in the past 12 years since 1986 was applied.

RESULTS

There was significant relationship between HFRS incidence rate and indoor density of rattus norvegicus (Rn), proportions of mixed species of rats and Rn with HFRS virus, indices of mixed species of rats and Rn with virus in the spring Relationship between HFRS incidence rate and densities of outdoor mixed species of rats and Apodemus agrarius (Aa), and proportions of mixed species and Aa with virus was all significant in autumn and winter. And, there was significant relationship between HFRS incidence rate during the whole year and annual average density of rats, proportion of rats with virus, index of rats with virus. There was no significant relationship between HFRS incidence rate and human inapparent infection rate. The coefficients of correlation between HFRS incidence rate in the spring and indices of indoor mixed species of rats and Rn with virus were 0.8637 and 0.8295, respectively (P < 0.001). And, those between HFRS incidence rate and indices of outdoor mixed species of rats and Aa were 0.7089 and 0. 7258 in the autumn and winter, respectively (P < 0.01). The coefficients of correlation between HFRS incidence rate in the next spring and indices of outdoor mixed species and Aa with virus in the autumn were 0.7118 and 0.7113, respectively (P < 0.01). The coefficient of correlation between HFRS incidence rate during the whole year and annual average index of rats with virus was 0.9207 (P < 0.001).

CONCLUSION

The index of rats with virus was an indicator of choice for qualitative prediction of HFRS, and the density of rats may be the secondary choice.