[Situational analysis of periodontal disease burden for adults in China from 1990 to 2019 and its incidence trend prediction]

Objective: To analyze the burden and changing trends of periodontal disease in adults of the mainland of China from 1990 to 2019, and to predict the incidence trends of periodontal disease in the next 25 years, with a goal to provide a basis for reducing the burden of periodontal disease and formulating relevant prevention and treatment measures. Methods: Data on the incidence, prevalence, and disability adjusted life years (DALY) rate of periodontal disease among adults in the mainland of China from 1990 to 2019 were extracted from the global burden of disease study 2019 (GBD 2019) database. The estimated annual percent change (EAPC) was used to estimate the temporal trend of periodontal disease, and the age-period-cohort model (APC) was used to predict the age-standardized incidence of periodontal disease in Chinese adults from 2020 to 2044. Results: From 1990 to 2019, the incidence, prevalence, and DALY rate of adult periodontal disease in the mainland of China showed an increasing trend, with EAPCs of 0.3 (95%CI: 0.1-0.6), 0.5 (95%CI: 0.1-0.8), and 0.5 (95%CI: 0.1-0.8), respectively. The incidence and prevalence of periodontitis among the population aged 35-39 years old and 40-44 years old increased the most significantly, with EAPCs of 0.8 and 0.7, respectively, whereas the change in periodontal disease prevalence tended to be stable and the increase trend in prevalence was lower in the elderly group (EAPC=0.4). The incidence (EAPC=2.1), prevalence (EAPC=2.6) and DALY rate (EAPC=2.6) of periodontal disease in females increased more than those in males (EAPC=1.9, 2.4, and 2.4, respectively), of which the prevalence had exceeded that of males in 2019. The APC model predicted that the prevalence of periodontal disease in the period of 2020-2044 in China would still be on an upward trend, and the increase rate would be higher in females than in males. Conclusions: The burden of periodontal disease among adults in China had been increasing over the past 30 years, especially among young and middle-aged adults as well as females, and the incidence of periodontal disease will continue to increase over the next 25 years.

G-Quadruplex/Hemin-Mediated Polarity-Switchable and Photocurrent-Amplified System for Escherichia coli O157:H7 Detection

The contamination of food by pathogens is a serious problem in global food safety, and current methods of detection are costly, time-consuming, and cumbersome. Therefore, it is necessary to develop rapid, portable, and sensitive assays for foodborne pathogens. In addition, assays for foodborne pathogens must be resistant to interference resulting from the complex food matrix to prevent false positives and negatives. In this study, hemin and reduced graphene oxide-MoS2 sheets (GMS) were used to design a near-infrared (NIR)-responsive photoelectrochemical (PEC) aptasensor with target-induced photocurrent polarity switching based on a hairpin aptamer (Hp) with a G-quadruplex motif. A ready-to-use analytical device was developed by immobilizing GMS on the surface of a commercial screen-printed electrode, followed by the attachment of the aptamer. In the presence of Escherichia coli O157:H7, the binding sites of Hp with the G-quadruplex motif were opened and exposed to hemin, leading to the formation of a G-quadruplex/hemin DNAzyme. Crucially, after binding to hemin, the charge transfer pathway of GMS changes, resulting in a switch of the photocurrent polarity. Further, G-quadruplex/hemin DNAzyme enhanced the cathodic photocurrent, and the proposed sensor exhibited a wide linear range ((25.0-1.0) × 107 CFU/mL), a low limit of detection (2.0 CFU/mL), and good anti-interference performance. These findings expand the applications of NIR-responsive PEC materials and provide versatile PEC methods for detecting biological analytes, especially for food safety testing.

Widely targeted metabolomics reveals the effect of different raw materials and drying methods on the quality of instant tea

Introduction

Instant teas are particularly rich in tea polyphenols and caffeine and have great potential as food ingredients or additives to improve the quality of food and enhance their nutritional and commercial value.

Methods

To determine the relationships between raw material, drying method, and sensory and other quality attributes, instant teas were prepared from three tea varieties, namely black, green and jasmine tea, using two drying methods, namely spray-drying (SD) and freeze-drying (FD).

Results

Both the raw tea material and drying method influenced the quality of the finished instant teas. Black tea was quality stable under two drying, while green tea taste deteriorated much after SD. Jasmine tea must be produced from FD due to huge aroma deterioration after SD. FD produced instant tea with higher sensory quality, which was attributed to the lower processing temperature. Chemical compositional analysis and widely targeted metabolomics revealed that SD caused greater degradation of tea biochemical components. The flavonoids content changed markedly after drying, and metabolomics, combined with OPLS-DA, was able to differentiate the three varieties of tea. Instant tea preparations via SD often lost a large proportion of the original tea aroma compounds, but FD minimized the loss of floral and fruity aroma compounds. Changes in the tea flavonoids composition, especially during drying, contributed to the flavor development of instant tea.

Discussion

These results will provide an practicle method for high-quality instant tea production through choosing proper raw tea material and lowering down drying temperature with non-thermal technologies like FD.

[Maintenance of efficacy and its predictors after discontinuation of eltrombopag in adults with primary immune thrombocytopenia]

Objective: To determine the efficacy of eltrombopag for primary immune thrombocytopenia (ITP) in adults and the predictive factors for treatment-free response (TFR) . Methods: Clinical data of adults with ITP who received eltrombopag from June 14, 2013 to May 31, 2021 in the Hematology Department of Ruijin Hospital affiliated with Shanghai Jiao Tong University Medical College were retrospectively analyzed. The initial dose of eltrombopag was 25 mg/d, and the maximum dose was 75 mg/d; the dose was adjusted to maintain the platelet count to within 50-150×10(9)/L. Treatment was discontinued according either to the protocol, on the patient's wishes or doctor's judgment (prescription medication), or based on clinical trials. The efficacy of eltrombopag and factors for TFR among patients who achieved complete response and those who discontinued treatment were analyzed. Results: Overall, 106 patients with ITP (33 men and 73 women) were included in the study. The median age of patients was 50 (18-89) years. There were 2, 10, and 94 cases of newly diagnosed, persistent, and chronic ITP, respectively. The complete response rate was 44.3% (47/106), the response rate was 34.0% (36/106), and the overall response rate was 78.3% (83/106). Meanwhile, 83 patients who responded to treatment discontinued eltrombopag; of these, 81 patients were evaluated. Additionally, 17 patients (21.0%) achieved TFR. The median follow-up duration of patients who achieved TFR was 126 (30-170) weeks. The recurrence rate was 17.6% (3/17), and the relapse-free survival rate was 76.5%. The results of univariate analysis revealed that non-recurrence after discontinuation of other treatments for ITP (P=0.001), and platelet count and eltrombopag dose of ≥100×10(9)/L (P=0.007) and ≤25 mg/d (P=0.031), respectively, upon discontinuation of eltrombopag were predictors of TFR; these effects were attributed to prolonged effective duration of eltrombopag. Multivariate analysis showed that there was a correlation between non-recurrence and prolonged effective duration after discontinuation of other treatments for ITP (P=0.002) . Conclusion: Eltrombopag is effective for patients with ITP as it can result in TFR. Predictors for TFR include non-recurrence after discontinuation of concomitant ITP treatment, and platelet count and eltrombopag dose of ≥100 × 10(9)/L and ≤25 mg/d upon discontinuation of treatment, respectively.

[Analysis of incidence and risk factors for postoperative venous thromboembolism in patients with stageⅠ a non-small-cell lung cancer]

Objective: To analyze the incidence and risk factors for postoperative venous thromboembolism(VTE) in patients with stage Ⅰa non-small-cell lung cancer(NSCLC), so as to find evidence for further research of prophylactic anticoagulation. Methods: A total of 132 patients with stage Ⅰa NSCLC, 42 males and 90 females aged from 26 to 79 years with an average of (57±10) years, were retrospectively included in this study. All of them underwent surgical treatment at the Department of Thoracic Surgery of Beijing Chaoyang Hospital Affiliated with Capital Medical University from January 2017 to October 2020. A lower extremity venous ultrasound was performed before and after the operation. Participants were divided into VTE group (n=11) or non-VTE group (n=121) according to whether or not VTE occurred after operation. The surgical conditions, test indicators, imaging information, pathology information were compared between the two groups. Logistic regression analysis was performed to test the associations of VET with putative risks factors in which significant differences were observed. The independent risk factors of VET were determined by this way. Results: Postoperative VTE occurred in 11 cases (8.3%), including 10 cases (90.9%) of deep vein thrombosis (DVT) of lower limbs and 1 case (9.1%) of DVT complicated with pulmonary embolism (PE). The mean age of Patients in the VTE group was older than that in non-VTE Group ((65±9) years vs (57±10) years, P=0.009). On the fifth day after operation, patients in both groups had significantly higher D-dimer level compared with that before operation (3.18(1.55, 5.15) vs 1.54(1.09, 2.57); 2.66(1.17, 4.65) vs 1.34(0.78, 2.04))(both P<0.05). The value of neuron-specific enolase (NSE) and the number of lymph nodes removed during the operation in the VTE group were significantly higher than those in the non-VTE group ((21.54±12.37) vs (14.72±5.75); (19.7±8.2) vs (13.0±7.9)) (both P<0.05). There was no statistically significant difference in the approach of surgery, imaging features (tumor location, vascular cluster signs, etc.), and pathological information (pathological types, etc.) (all P>0.05). The logistic regression analysis showed that the number of lymph nodes removed during the operation was an independent risk factor related to the occurrence of VTE (OR=1.306, 95%CI:1.000-1.600,P<0.05). Conclusions: The incidence of postoperative VTE in patients with stage Ⅰa NSCLC is approximately 8.3%. The number of lymph nodes removed during the operation may be an independent risk factor for postoperative VTE in patients with stage Ⅰa NSCLC.

Discrimination of Chinese Baijiu grades based on colorimetric sensor arrays

In this study, a novel colorimetric sensor array based on chemo dyes including porphyrins and pH indicators were developed to analyse the volatile organic compounds of Chinese Baijiu with different grades. Ethyl acetate, ethyl butyrate and ethyl caproate appeared by significantly different concentration in different Baijiu grades measuring by gas chromatography and mass spectrometry and they were chosen as characteristic volatile organic components. The olfactory visualization system based on colorimetric sensor arrays was used to identify different Baijiu grades. The data were processed by building the principle components analysis, linear discriminant analysis and K-nearest neighbor classification models with the results of sensory evaluation and olfactory visualization system. This work presents a new-style colorimetric sensor using sensitive chemo dyes which has significant potential in quantitative analysis of volatile organic compounds, afterwards identifying different grades of Baijiu.

[Establishment and evaluation of acute diquat poisoning model in Wistar rats]

Objective: To establish the Wistar rat model of acute diquat poisoning and observe the pathological damage of main target organs. Methods: Thirty-six Wistar rats were randomly divided into six groups (n=6) , including one normal saline control group and five treatment groups which were separately given single-dose of intragastric administration at the doses of 46.2 mg/kg, 77.0 mg/kg, 115.5 mg/kg, 231.0 mg/kg and 346.5 mg/kg. The pathological changes of lung, liver and kidney were observed by hematoxylin and eosin (HE) and Masson staining. The optimal dose was determined according to the general situation and pathological changes. Thirty-six Wistar rats were randomly divided into five treatment groups and one normal saline control group. Treatment groups were given single-dose of intragastric administration according to the optimal dose. The rats were sacrificed at 1st, 3rd, 7th, 11th and 14th day after exposed, respectively. The activity of serum glutamic-pyruvic transaminase (ALT) and glutamic-oxalacetic transaminase (AST) were measured by chemical colorimetry. The pathological changes of lung, liver and kidney were observed by HE and Masson staining. Results: According to 14 d survival rate, the toxic symptoms and pathological changes, 115.50 mg/kg was determined the best dose. Given single-dose of intragastric administration at the doses of 115.50 mg/kg, it was found that the serum AST and ALT activity of rats on the first and third day of exposure was significant higher than those in control group. The results of pathological examination exhibited that in 115.50 mg/kg group, the pathological changes of lung, liver and kidney began to appear on the first day of exposure, the pathological changes were the most serious on the third day, and then gradually alleviated. On the 14th day, the alveolar septum was slightly widened, with inflammatory cell infiltration, local alveolar cavity became narrow, atrophy, peripheral alveolar compensation, bronchi and alveolar septum collagen fiber proliferation; The local renal tubular epithelial cells were enlarged and necrotic; the central vein surrounding hepatic cells showed vacuolar degeneration with punctate necrosis. Conclusion: The rat model of acute diquat poisoning can be successfully induced by single-dose of intragastric administration. The condition of wistar rats and the pathological damage of the main target organs could be observed during the whole course of 115.50 mg/kg administration.

Sensory quality evaluation for appearance of needle-shaped green tea based on computer vision and nonlinear tools

Tea is one of the three greatest beverages in the world. In China, green tea has the largest consumption, and needle-shaped green tea, such as Maofeng tea and Sparrow Tongue tea, accounts for more than 40% of green tea (Zhu et al., 2017). The appearance of green tea is one of the important indexes during the evaluation of green tea quality. Especially in market transactions, the price of tea is usually determined by its appearance (Zhou et al., 2012). Human sensory evaluation is usually conducted by experts, and is also easily affected by various factors such as light, experience, psychological and visual factors. In the meantime, people may distinguish the slight differences between similar colors or textures, but the specific levels of the tea are hard to determine (Chen et al., 2008). As human description of color and texture is qualitative, it is hard to evaluate the sensory quality accurately, in a standard manner, and objectively. Color is an important visual property of a computer image (Xie et al., 2014; Khulal et al., 2016); texture is a visual performance of image grayscale and color changing with spatial positions, which can be used to describe the roughness and directivity of the surface of an object (Sanaeifar et al., 2016). There are already researchers who have used computer visual image technologies to identify the varieties, levels, and origins of tea (Chen et al., 2008; Xie et al., 2014; Zhu et al., 2017). Most of their research targets are crush, tear, and curl (CTC) red (green) broken tea, curly green tea (Bilochun tea), and flat-typed green tea (West Lake Dragon-well green tea) as the information sources. However, the target of the above research is to establish a qualitative evaluation method on tea quality (Fu et al., 2013). There is little literature on the sensory evaluation of the appearance quality of needle-shaped green tea, especially research on a quantitative evaluation model (Zhou et al., 2012; Zhu et al., 2017).

[Effect of three kinds of modelling of mandible on the finite element analysis of implant]

Objective: To investigate the effect of three types of material homogeneities(isotropy, transverse isotropy, and orthotropy) of mandible on the finite element analysis of implant. Methods: Three-dimensional model of complete mandible containing an implant was constructed and analyzed with isotropic, transversely isotropic, and orthotropic models, respectively. Results: The effective stress, tensile stress, and compressive stress of cortical bone of the orthogonal model were 1.2, 1.2, and 1.1 times larger than that of the isotropic model. The effective stress, tensile stress, and compressive stress of cancellous bone of the orthogonal model were 1.6, 2.6, and 3.3 times larger than that of the isotropic model. The effective strain, tensile strain, and compressive strain of cortical bone of the transversely isotropic model were 1.1, 1.0, and 1.1 times larger than that of the isotropic model. The effective strain, tensile strain, and compressive strain of cortical bone of the orthogonal model were 2.2, 1.8, and 1.7 times larger than that of the isotropic model. The stress and strain of cancellous bone increased when the material homogeneity changed from isotropy to transverse isotropy and to orthotropy. Moreover, in term of stress and strain distribution, the orthotropic modelling of mandible was most uniform followed by the transverse isotropy and the isotropy. Conclusions: In the finite element analysis of implant system, the orthotropic property of the mandible can not be neglected.

Clinical significance of microRNA-34a in esophageal squamous cell carcinoma

MicroRNA-34a (miR-34a) has been found to be downregulated in esophageal squamous cell carcinoma (ESCC) tissues compared with that in normal tissues (P < 0.05), and miR-34a overexpression increased apoptosis and decreased clonogenic formation. However, the clinical significance and prognostic value of miR-34a in ESCC has not yet been investigated. In total, 111 patients with ESCC diagnosed and treated at the Department of Thoracic Surgery of Fujian Provincial Hospital between March 2008 and February 2014 were included in this retrospective study. Quantitative real-time PCR was performed to detect expression levels of miR-34a. The associations between miR-34a expression and clinicopathological features were analyzed using χ(2) tests. For analysis of survival data, Kaplan-Meier curves were constructed, and the log-rank test was performed. The expression levels of miR-34a in ESCC tissues were significantly decreased (P < 0.01), compared with those in adjacent normal esophageal tissues. Low miR-34a expression in ESCC tissues was significantly associated with tumor differentiation (P = 0.013), lymph node status (P = 0.038), and advanced clinical stage (P < 0.001). The Kaplan-Meier analysis and log-rank test revealed that low miR-34a levels had a significant impact on overall survival of patients with ESCC (P = 0.006). Multivariate analyses showed that the expression of miR-34a was an independent prognostic factor for ESCC (P = 0.018). Our findings indicate that there is reduced expression of miR-34a in human ESCC tissues and suggest a crucial role for miR-34a downregulation in ESCC progression and prognosis.

Mutation analysis of PVRL1 in patients with non-syndromic cleft of the lip and/or palate in Guangdong

Non-syndromic cleft of the lip and/or palate (NSCLP) is a very common birth defect; the poliovirus receptor-like 1 gene (PVRL1) has been identified as a genetic risk factor for NSCLP in patients from Norway, the Philippines, and South America. Given the considerable variation in allele frequencies across these geographical regions, this study explored the relationship between NSCLP and mutations of PVRL1 in patients from Guangdong, China. We recruited 171 NSCLP patients and 100 volunteers, and divided our samples into 2 groups: a sequencing group and a mass spectrometry group. In the sequencing group, we screened for mutations in exons 2 and 5 of PVRL1 by polymerase chain reaction and direct sequencing in 71 NSCLP patients and 100 volunteers. In the mass spectrometry group, we screened for amino acid mutations in α-spliced transcript codons 112, 131, and 395, and in the β-spliced transcript codon 1082 using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis in 100 NSCLP patients and 100 volunteers. No mutations were detected in either PVRL1 exons 2 or 5 in the 71 NSCLP patients and 100 volunteers, nor did we find mutations of α-spliced transcript codons 112, 131, 395 and the β-spliced transcript codon 1082 in any of the 100 NSCLP patients and 100 volunteers. Thus, mutations in exons 2 and 5 of PVRL1, and T334A, A391T, G1183A in the α-spliced transcript, and G1082T in the β-spliced transcript do not participate in the development of NSCLP in patients from Guangdong.

Sevoflurane promotes the expansion of glioma stem cells through activation of hypoxia-inducible factors in vitro

BACKGROUND

Growing evidences indicate that inhalational anaesthetics can enhance the growth and malignant potential of tumour cells and may affect tumour recurrence after surgery. Tumour stem cells play a vital role in tumour recurrence. This study investigates the effect of sevoflurane on glioma stem cells (GSCs) in vitro and the underlying molecular mechanisms in this process.

METHODS

Cultured GSCs were exposed to clinically relevant concentrations and durations of sevoflurane exposure. Cell proliferation and self-renewal capacity were determined. Expression of the stem cell marker CD133, vascular endothelial growth factor (VEGF), hypoxia-inducible factors (HIFs), and phosphorylated Akt, which is a protein kinase invoved in multiple cellular processes, were measured using western blotting. Small interfering RNAs and an Akt inhibitor were used to investigate specific pathways.

RESULTS

Compared with controls, cells exposed to 2% sevoflurane for 6 h induced a larger number of proliferated cells (31.2±7.6% vs 19.0±5.8%; P<0.01). Levels of CD133, VEGF, HIF-1α, HIF-2α, and p-Akt were up-regulated by sevoflurane in a time- and concentration-dependent manner. Small interfering RNA against HIFs decreased the percentage of proliferating GSCs after sevoflurane exposure and pre-treatment of cells with an Akt inhibitor abrogated the expression of HIFs induced by sevoflurane.

CONCLUSIONS

Sevoflurane can promote the expansion of human GSCs through HIFs in vitro. Inhaled anaesthetics may enhance tumour growth through tumour stem cells.

Quantative trait loci of seed traits for soybean in multiple environments

Seed length and seed width are an important factor to the soybean yield. So the quantitative trait loci (QTL) location for seed length and seed width could assistant the breeding of soybean. In this study, the QTL underlying seed length and seed width were studied. A recombinant inbred line population of soybeans derived from a cross between the American semi-draft cultivars Charleston and Dongnong 594 were used in 7 environments. The quantitative trait loci underlying seed length, seed width, and seed length/seed width were analyzed by the method of composite interval mapping. Then, the epistatic effects and the QTL-environment (QE) interaction effects were also analyzed. Some valuable QTL sites found had great effect to the seed trait. Results showed that 7 QTLs underlying seed length were identified mainly on linkage groups D1a, C2, B1, A1, G, and A2. For the seed width, 7 QTLs were identified on linkage groups D1a and O. Two QTLs of seed length/seed width were identified on linkage groups D1b and C2. No QE interaction was found for QTLs of seed length and seed width in 7 environments. QTLs of seed length/seed width on linkage groups A1 and I had a QE interaction in 7 environments. Seven pairs of QTLs were identified that affected additive x additive epistatic effect of seed length, seed width, and seed length/seed width, which occurred among 8 linkage groups. These results supply a good foundation for molecular assistant breeding for soybean seed trait.

Ultrastructural identification of interstitial cells of Cajal in hen oviduct

The interstitial cells of Cajal (ICC) are widely believed to be neuroeffector cells of smooth muscle activity in all tubular organs, including the oviduct. The avian oviduct involves the secretion, sheathing, and transportation of a large-sized egg, but there is no information available on ICC in this special organ. We have demonstrated the presence of ICC in different segments throughout the oviduct in the laying hen and provided details on their ultrastructure by transmission electron microscopy technique, for the first time. The observed ICC appeared bipolar and multipolar cells of different shapes, with varying nuclear morphologies, a thin rim of electron-dense cytoplasm, and an infrequent basal lamina. They showed moniliform primary processes with one or 2 secondary or terminal processes. We found ICC near smooth muscle cells, nerve fibers, and the epithelia, where they make specialized contacts in the form of close membrane associations or gap-like junctions and peg-and-socket-like junctions. Intricate labyrinthine-type networking contacts were also present in ICC processes. Moreover, we report for the first time, that ICC in avian oviduct make interdigitating contacts with the epithelium. Cytoplasmic organelles identified in ICC include numerous well-developed mitochondria, abundant rough endoplasmic reticulum, and dispersed intermediate filaments. Many caveolae and vesicles were also present. Golgi bodies and centrioles were rare. Fibroblasts, on the other hand, were distinct cells with larger cytoplasmic area, more rough endoplasmic reticulum, and less mitochondrial content. No basal lamina, intermediate filaments, or caveolae were present in fibroblasts. Their processes were shorter and showed no contacts with smooth muscle cells or nerves. We conclude that these ICC might also have a key role in the regulatory mechanisms of motility and transportation in the hen oviduct, as already proved in mammalian oviduct. Such role of ICC might also be responsible for the function of the muscular infundibulum, where the fertilization takes place, and that moves to surround the released ovum, failure of which results in the internal laying.

[Measurement of chlorophyll content and distribution in tea plant's leaf using hyperspectral imaging technique]

Chlorophyll content and distribution in plant's leaves is an important index in estimation of plant nutrition information. In the present work, chlorophyll content and distribution in tea plant's leaves were measured by hyperspectral imaging technique. First, hyperspectral image data were captured from tea plant's leaves; then seven kinds of algorithms were used to extract the characteristic parameters from hyperspectral image; finally, seven fitted models were developed using the characteristics vectors and the reference measurements of chlorophyll contents respectively. Experimental results showed that the MSAVI2 model is superior to other models, and the results of the MSAVI2 model was achieved as follows: R = 0.843 3 and RMSE = 9.918 in the calibration set; R = 0.832 3 and RMSE = 8.601 in the prediction set. Finally, the chlorophyll content of each pixel in image was estimated by the fitted model, and the distribution of chlorophyll content in the tea plant's leaf was described by pseudo-color map. This study sufficiently demonstrated that the chlorophyll content and distribution in tea leaf can be measured by hyperspectral imaging technique.

[Identification of egg freshness using near infrared spectroscopy and one class support vector machine algorithm]

Near infrared (NIR) spectroscopy combined with pattern recognition was attempted to discriminate the freshness of eggs. The algorithm of one-class support vector machine (OC-SVM) was employed to solve the classification problem due to imbalanced number of training samples. In this work, 86 samples of eggs (71 samples of fresh eggs and 15 samples of unfresh eggs) were surveyed by Fourier transform NIR spectroscopy. Firstly, original spectra of eggs in the wave-number range of 10 000-4 000 cm(-1) were acquired. And then, principal component analysis (PCA) was employed to extract useful information from original spectral data, and the number of PCs was optimized. Finally, OC-SVM was performed to calibrate discrimination model, and the optimal PCs were used as the input eigenvectors of model. In order to obtain a good performance, the regularization parameter v and parameter sigma of the kernel function in OC-SVM model were optimized in building model. The optimal OC-SVM model was obtained with nu = 0.5 and sigma2 = 20.3. Experimental result shows that OC-SVM got better performance than conventional two-class SVM model under the same condition. The OC-SVM model was achieved with identification rates of 80 for both fresh eggs and unfresh eggs in the independent prediction set. The identification rates of fresh eggs were 100% in two-class SVM model. However, when the two-class SVM model was used to discriminate the unfresh eggs of, the identification rates were 0% in the independent prediction set. Compared with conventional two-class SVM model, the OC-SVM model showed its superior performance in discrimination of minority unfresh eggs samples. This work shows that it is feasible to identify egg freshness using NIR spectroscopy, and OC-SVM is an excellent choice in solving the problem of imbalanced number of samples in training set.

[Study of simplification of prediction model for kiwifruit firmness using near infrared spectroscopy]

To simplify the prediction model of kiwifruit firmness, SNV was used to preprocess the near infrared (NIR) spectra (1 000-2 500 nm)of kiwifruit. PLS model simplification by optimizing spectral intervals and decreasing the number of factors through net analyte preprocessing (NAP)was carried out. Results showed that the performance of NAP/PLS model is the best. It was achieved with 5 factors in five wavenumber ranges(5 189-5 370, 4 549-4 620, 6 049-6 230, 6 999-7 730, and 6 249-6 614 cm(-1)). The optimal model was achieved with R2 = 0.819 41 and RMSECV = 0.701 77 in the calibration set and R2 = 0.780 67 and RMSEP = 0.882 71 in the prediction set. This indicates that the model not only may efficiently simplify PLS model, but also may improve precision and predictive ability.

Rituximab in combination with CHOP chemotherapy for the treatment of diffuse large B cell lymphoma in Chinese patients

The objective of this study is to evaluate the long-term efficacy and safety of rituximab combined with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in Chinese patients with newly diagnosed diffuse large B cell lymphoma (DLBCL). The study comprised a retrospective analysis of patients treated at a single center. Patients received four to six infusions of rituximab (375 mg/m(2) per dose) on day 1 of each cycle of CHOP chemotherapy. CHOP was initiated on day 3 of each cycle; cycles were repeated at 21-day intervals. A total of 82 patients with a median age of 45 years (range 18-76 years) was included. The overall response (OR) and complete response (CR) rates were 90.2 and 70.7%, respectively. The estimated 5-year progression-free survival (PFS) and overall survival (OS) rates were 56.4 +/- 8.3% and 74.1 +/- 7.4%, respectively. Patients with International Prognostic Index (IPI) scores < or = 2 had significantly higher OR, CR, PFS, and OS rates (p = 0.01, p = 0.02, p = 0.01, p < 0.001, respectively) compared with patients with IPI scores >2. The hematologic toxicity was mild. Five patients with a history of chronic hepatitis B experienced a reactivation of viral hepatitis. The rituximab-CHOP combination was effective and well tolerated in Chinese patients with newly diagnosed DLBCL.

[Study on the identification of tea using near infrared reflectance spectroscopy]

A rapid tea identification method by near infrared spectroscopy coupled with pattern recognition based on principal components analysis and Mahalanobis' distance technique was proposed. Four famous brand teas in China were studied, including Longjing tea, Biluochun tea, Maofeng tea and Tieguanyin tea in the experiment. In the spectral region between 6 500 and 5 300 cm(-1), through preprocessing method of MSC (multiplicative scatter comection), the prediction model was built. The result showed that the model was the best with 8 principal component factors. The rates of identification in calibration set samples and prediction set samples were 98.75% and 95%, respectively. A new idea about quick and precise identification of tea was offered.

Nitrogen response efficiency increased monotonically with decreasing soil resource availability: a case study from a semiarid grassland in northern China

The concept of nutrient use efficiency is central to understanding ecosystem functioning because it is the step in which plants can influence the return of nutrients to the soil pool and the quality of the litter. Theory suggests that nutrient efficiency increases unimodally with declining soil resources, but this has not been tested empirically for N and water in grassland ecosystems, where plant growth in these ecosystems is generally thought to be limited by soil N and moisture. In this paper, we tested the N uptake and the N use efficiency (NUE) of two Stipa species (S. grandis and S. krylovii) from 20 sites in the Inner Mongolia grassland by measuring the N content of net primary productivity (NPP). NUE is defined as the total net primary production per unit N absorbed. We further distinguished NUE from N response efficiency (NRE; production per unit N available). We found that NPP increased with soil N and water availability. Efficiency of whole-plant N use, uptake, and response increased monotonically with decreasing soil N and water, being higher on infertile (dry) habitats than on fertile (wet) habitats. We further considered NUE as the product of the N productivity (NP the rate of biomass increase per unit N in the plant) and the mean residence time (MRT; the ratio between the average N pool and the annual N uptake or loss). The NP and NUE of S. grandis growing usually in dry and N-poor habitats exceeded those of S. krylovii abundant in wet and N-rich habitats. NUE differed among sites, and was often affected by the evolutionary trade-off between NP and MRT, where plants and communities had adapted in a way to maximize either NP or MRT, but not both concurrently. Soil N availability and moisture influenced the community-level N uptake efficiency and ultimately the NRE, though the response to N was dependent on the plant community examined. These results show that soil N and water had exerted a great impact on the N efficiency in Stipa species. The intraspecific differences in N efficiency within both Stipa species along soil resource availability gradient may explain the differences in plant productivity on various soils, which will be conducive to our general understanding of the N cycling and vegetation dynamics in northern Chinese grasslands.

Hepatitis B vaccination among Vietnamese-American children in a Boston community clinic

PURPOSE

This manuscript describes one community health center s efforts to provide catch-up immunization for hepatitis B for Vietnamese Americans aged 7 to 17.

METHODS

A chart review of 151 Vietnamese-American children seen at the health center was conducted in Spring, 2001. Letters were sent to notify parents of their children's immunization status. One month later, the investigators attempted to contact the parents by phone. The interviews were done to conduct a survey about hepatitis B virus (HBV), and to encourage parents whose children needed further follow-up to do so.

PRINCIPAL FINDINGS

Chart review revealed that 2% (n=3) of the patients were chronically infected with HBV, and 28% (n=42) were known to be already immune due to prior exposure. Thirteen patients had either moved or were obtaining care elsewhere. Of those needing vaccination (n=93), 76 (82%) completed the series of three vaccines. Of the remaining 17 patients needing further follow-up, 9 were vaccinated in the community clinic, for a 91% vaccination rate (85 of 93). For this survey, a 63% survey response rate was achieved among the patients' parents (55 of 88 eligible households). Of parents reporting that their children had a hepatitis B vaccination (HepB), study investigators were unable to confirm 25% by chart review. Although letters were sent regarding their children's HBV status, only 71% reported having heard of HBV, and 60% reported having heard of HepB vaccine. The children's receipt the HepB vaccine was not significantly associated with the parents' having heard of HBV or HepB vaccination, the parents' length of time in the United States, their health insurance status, or their level of education.

CONCLUSIONS

These findings suggest that parents need more education about HBV, and that the information they provide about their children's vaccination status may not be reliable.

Fluoroscopic study of tumor motion due to breathing: facilitating precise radiation therapy for lung cancer patients

Target motion due to breathing is one of the major obstacles in dose escalation of radiation therapy to some tumors in the thoracoabdominal region. The development of beam gating or target motion tracking techniques provides a possibility to reduce normal tissue volume in a treatment field. Tumor motion monitoring in those techniques plays a crucial role, but has not yet been adequately explored. This paper reports our preliminary investigation on breath introduced tumor motion. Tumor locations and motion properties were determined from digitized fluoroscopic videos acquired during patient simulation. Image distortion due to irregularities in the imaging chain, such as the pincushion distortion, was corrected with a polynomial unwarping method. Temporal Fourier transformation of the fluoroscopic video was introduced to convert the motion information over time to a static view of a motion field, in which regions with different motion ranges can be directly measured. Patient breathing patterns vary from patient to patient and so does the kinematic behavior of individual tumors. In order to evaluate the feasibility for tracking internal target motion with nonionizing-radiation techniques, motion patterns between internal targets and external radio opaque markers placed on patient's chest during fluoroscopic video acquisition were compared. For some patients, significant motion phase discrepancies between an internal target and an external marker have been observed. Quantitative measurements are reported. These results will be useful in the design of a motion tracking or gated radiotherapy system.

Deficient long-term memory and long-lasting long-term potentiation in mice with a targeted deletion of neurotrophin-4 gene

We examined the learning and memory of neurotrophin-4 (NT4)-/- mice by using fear conditioning. In both cue and context conditioning, we found significant deficits in the NT4 mutants at 2 and 24 h after training but not at 30 min. Hippocampal slices from the mutant mice showed normal basal synaptic transmission, short-term plasticity, and decremental long-term potentiation (LTP) at the Schaffer collateral-CA1 synapses. These findings, together with the normal short-term memory, suggest that the hippocampal development of NT4-/- mice is largely unaffected. However, consistent with the long-term memory defects, the long-lasting LTP at the same synapses was attenuated significantly in the mutant mice. Our results suggest that NT4 plays a physiological role essential for hippocampus- and amygdala-dependent long-term memory and hippocampal long-lasting LTP and that NT4 may be useful in the therapy of acquired disorders of learning and memory.

Impairment of hippocampal long-term potentiation by Alzheimer amyloid beta-peptides

Although it is generally believed that amyloid beta (Abeta) peptides contribute to the pathogenesis of Alzheimer's disease, the precise role of these peptides in the development of memory loss of Alzheimer's disease, has not been fully understood. The present study examined the effect of several synthetic Abeta peptides on long-term potentiation (LTP), a cellular model of learning and memory, in rat hippocampal slices. Brief perfusion of slices with low concentrations (200 nM or 1 microM) of Abeta(1-42), Abeta(1-40) or their active fragment Abeta(25--35) significantly inhibited LTP induction without affecting the basal synaptic transmission and posttetanic potentiation in the dentate medial perforant path. A similar effect of Abeta(25-35) was also observed in the Schaffer collateral-CA1 pathway. When comparing actions of several Abeta variants derived from Abeta(25-35), the N-terminal sequence of Abeta(25-35) was found necessary for inhibiting LTP. In addition, Abeta variants lacking neurotoxic action and aggregating property were also able to block LTP, suggesting that this effect was neurotoxicity independent. Our findings demonstrated that subneurotoxic concentrations of Abeta peptides could strongly suppress long-term synaptic plasticity in the hippocampus. Such an effect might underlie the memory deficits seen in Alzheimer's disease before neuronal cell loss.

[Application of sartorius muscle in the quadricepsplasty]

OBJECTIVE

Extension stiffness of knee joint is always treated by the quadricepsplasty, but the main deficiency of this method is that patient feels weakness of lower limb and easily kneels down. The aim of this article is to explore the method to resolve the complications after quadricepsplasty.

METHODS

Since 1978 to 1997, on the basis of traditional procedures of quadricepsplasty, sartorius muscle was used to reinforce the extension of knee joint. The lower 2/3 of sartorius muscle was fully dissociated only with its insertion intact. A tendon-periosteal-bone flap, about 2 cm in width, was managed on the anterior surface of patella, with its pedicle on the medial edge of patella. The tendon-periosteal-bone flap was used to fix the dissociated sartorious into patella to reinforce the extension of knee joint. The very lower part of sartorius was mainly aponeurosis, with the help of an aponeurosis bundle of iliotibial tract, it was fixed into the insertion of patellar ligament, through a bony tunnel chiseled adjacent to the insertion of patellar ligament. By now the movement of knee joint extension was strengthened by the transferred sartorius muscle. Postoperatively, every patient was required to extend and flex knee joint actively and/or passively. Altogether 12 patients were treated, 9 of them were followed up with an average of 14 months.

RESULTS

The average movement was increased from 15 degrees to 102 degrees, and the average myodynamia was improved from grade II to grade IV.

CONCLUSION

Traditional quadricepsplasty co-operated with transfer of sartorius muscle can strengthen the myodynamia of knee joint extension. It is simple method and can really achieve good function.

Enhanced growth of megakaryocyte colonies in culture in the presence of heparin and fibroblast growth factor

Fibroblast growth factors (FGFs) are a family of mitogenic proteins that promote the division of most mesoderm- and neuroectoderm-derived cells. Interaction with heparin-like molecules appears to be critical for FGFs to exert their activity. We previously reported that FGF-1, FGF-2, and heparin are each capable of stimulating megakaryocytopoiesis in vitro and that heparin has a thrombopoietic effect when administered to patients with chronic immune thrombocytopenic purpura. The present study was designed to determine whether the combination of heparin and FGF results in a synergistic effect on murine megakaryocytopoiesis. In vitro, in both plasma clot and agar serum-free culture systems, FGF-1 and FGF-2 stimulated megakaryocyte colony formation in a dose-dependent fashion. Half-maximal effect of the two FGFs was observed at 1 ng/ml, and their effect was saturating at 20 ng/ml. The addition of heparin to cultures stimulated by FGF-1 or FGF-2 resulted in a 2-fold increase in the number of megakaryocyte colonies compared to the culture containing FGF alone. In the presence of heparin (5 IU/ml), FGF at 1 ng/ml exerted an almost maximal stimulating effect on megakaryocyte colony formation. When murine and human CD34+ cells were used as target cells, a similar interaction between FGF and heparin was observed. The combination of FGF and heparin induced a maximal growth of megakaryocyte colonies from CD34+ cells. These findings demonstrate the synergistic effect of heparin and FGF on megakaryocytopoiesis.

Subunity coordinate translation with Fourier transform to achieve efficient and quality three-dimensional medical image interpolation

A new approach to the interpolation of three-dimensional (3D) medical images is presented. Instead of going through the conventional interpolation scheme where the continuous function is first reconstructed from the discrete data set and then resampled, the interpolation is achieved with a subunity coordinate translation technique. The original image is first transformed into the spatial-frequency domain. The phase of the transform is then modified with n-1 linear phase terms in the axial direction to achieve n-1 subunity coordinate translations with a distance 1/n, where n is an interpolation ratio, following the phase shift theorem of Fourier transformation. All the translated images after inverse Fourier transformation are then interspersed in turn into the original image. Since windowing plays an important role in the process, different window functions have been studied and a proper recommendation is provided. The interpolation quality produced with the present method is as good as that with the sampling (sinc) function, while the efficiency, thanks to the fast Fourier transformation, is very much improved. The approach has been validated with both computed tomography (CT) and magnetic resonance (MR) images. The interpolations of 3D CT and MR images are demonstrated.

Physical training modifies the age-related decrease of GAP-43 and synaptophysin in the hippocampal formation in C57BL/6J mouse

We investigated the effect of a moderate amount of prolonged physical training initiated at 3 months of age on the expression of GAP-43 and synaptophysin in the hippocampal formation. C57BL/6J mice were divided into three groups which were trained (24 months old), sedentary (24 months old) and young (3 months old). From 3 months of age on, mice of trained group were treated with voluntary running wheel for 1 h each day (5 days per week) until 24 months of age (21 months running), whereas mice of sedentary group were put in immobilized wheels for the same time. Using immunohistochemistry and image analysis system, GAP-43 and synaptophysin were analysed quantitatively in the CA1, CA3 areas and the dentate gyrus of the hippocampal formation. As compared with young mice, the densities of GAP-43 and synaptophysin immunostaining showed a significant decrease in the hippocampal formation in sedentary group (P<0.01). After 21 months of running, the densities of GAP-43 and synaptophysin immunostaining significantly increased in the examined areas of the hippocampal formation in trained mice compared to their age-matched sedentary controls (P<0.05, 0.01). These results indicate that a moderate amount of prolonged physical training could modify the age-related decrease of the expression of GAP-43 and synaptophysin in the hippocampal formation, and that the increased expression of GAP-43 and synaptophysin might be associated with the anatomical sprouting and synaptogenesis.

Effect of physical training on the age-related changes of acetylcholinesterase-positive fibers in the hippocampal formation and parietal cortex in the C57BL/6J mouse

We investigated the effect of a moderate amount of prolonged physical training initiated at 3 months of age on the age-related changes of the hippocampal and cortical cholinergic fibers. A total of 80 male C57BL/6J mice were divided into five groups which were trained (including adult and old trained, AT and OT), sedentary (adult and old sedentary, AS and OS) and young (Y). From 3 months old, the mice of the trained groups were treated with a voluntary running wheel for 1 h each day, 5 days per week. AT had been trained up to 13-month-old whereas OT up to 24 months old. At the same time, the mice of the sedentary groups were put in immobilized wheels. We set the criterion for effective training in the trained mice such that the heart-to-body weight ratio should be at least 2 S.D. above the mean in the age-matched groups. Using AChE histochemistry and stereology, the AChE-positive fibers were analyzed quantitatively in the molecular layers in CA1, CA3 and the dentate gyrus of the hippocampal formation, and in III, V layers in the motor and somatosensory cortex. Comparison of Y, AS and OS (3, 13 and 24 months of age) showed minimum AChE-positive fiber density in the hippocampal formation and the cortex in OS (P < 0.01). After 10 and 21 months of running, the AChE-positive fibers in all regions examined in the trained groups were significantly increased compared to their age-matched controls (P < 0.05 or 0.01). In the hippocampal formation, the increase was about 17% in AT and 23% in OT, whereas, in the cortex, it was 13% in AT and 22% in OT. These results indicated that a moderate amount of prolonged physical training could modify the age-related loss of cholinergic fibers in the hippocampal formation and cortex, furthermore the modified loss of cholinergic fibers might be associated with the regeneration of hippocampal and cortical cholinergic fibers stimulated by chronic running.

Quantitative assessment of bone marrow hematopoiesis using parametric magnetic resonance imaging

Spatial maps of the percentage cellularity in pelvic bone marrow were calculated at a resolution of 15.6 mm3 from six volunteers and 10 patients treated for documented hematologic disease using a three-point Dixon MRI pulse sequence. The percentage cellularity calculation was aided by analyzing a two-dimensional feature space consisting of the apparent water fraction (Wa), and the T2 relaxation time of water (T2w). An extracellular water fraction was assigned to each voxel on the basis of a two-component T2w algorithm. In six cases, the method was compared to results obtained from core biopsies or aspirates of the posterior iliac crest. The results indicate that segmentation schemes that combine high-quality phase-contrast imaging with nuclear relaxation time measurements can potentially identify the true fractional marrow volume occupied by hematopoietic elements in a variety of clinical situations.

[Effects of gastric mucosal blood flow (GMBF) on the role of adaptive cytoprotection of rat gastric mucosa]

By the use of hydrogen gas clearance technique, we have investigated the role of GMBF in the adaptive cytoprotection induced by intragastric perfusion with low concentration prior to high concentration of HCl plus ethanol. The results were as follows: (1) intragastric perfusion with low concentration prior to high concentration of HCl plus ethanol led to an adaptive cytoprotection, i.e., the gross and the deep damage were decreased by 47.09% and 44.57% respectively, as compared with those caused by high concentration of HCl plus ethanol alone; correspondingly, GMBF also showed an adaptive hyperemic response, i.e., GMBF was increased by 28.02% as compared with that due to high concentration alone; (2) close arterial infusion of vasopressin blocked the adaptive hyperemic response and abolished the adaptive cytoprotection; (3) intravenous indomethacin reduced the basal GMBF, and abolished both the adaptive hyperemic response and cytoprotection; furthermore, the gross and deep damage were aggravated compared with that caused by high concentration alone. The results showed that the adaptive hyperemic response of gastric mucosa was involved in the adaptive cytoprotection and suggested that the adaptive cytoprotection of endogenous prostaglandin might be partially related to the increase of GMBF.

Three-dimensional multimodality medical image registration using a parameter accumulation approach

A parameter accumulation method based on the Hough transformation is proposed to register three-dimensional (3-D) multimodality medical images. The estimation of registration parameters is decomposed into separate estimations of rotation, using directional vectors, and translation, using positional vectors. Similarly, the rotation parameters are decomposed into the rotation axis and angle, which are then estimated separately. This kind of decomposition reduces the parametric dimension and improves the computing efficiency which has been a major concern in implementing the Hough transformation. When 3-D rotation is involved, evaluating registration error is not straightforward. This paper introduces an equivalent error angle as a criterion to evaluate the performance of 3-D registration methods. Experimental results indicate that a least-squares fitting is superior to the parameter accumulation with data contaminated by additive noise only. When mismatched feature points (outliers) exist in the data set, however, the parameter accumulation approach is more accurate. The application of the proposed approach to the registration of 3-D PET and CT images is demonstrated.

[Effects of beta-endorphin on blood pressure and heart rate in rats]

The present work was undertake to investigate the mechanism of changes of blood pressure and heart rate induced by beta-endorphin (beta-End) after microinjection into the Nucleus Amygdaloideus Centralis (AC) of anaesthetized rats. The results were as follows: (1) beta-End (100, 250 pg/microliters) injected into AC decreased both blood pressure and heart rate. (2) Both these effects could be antagonized by naloxone and beta-End anti-serum. (3) The effects of beta-End could also be reversed by phentolamine and propranolol. The results showed that the cardiovascular effects on beta-End were mediated by opioid receptors and through the intervention of adrenergic neurons.

Effects of serotonin-receptor blockade on angioplasty-induced vasospasm in an atherosclerotic rabbit model

Vasospasm occurs both in patients and animal models after angioplasty and may be associated with early closure of the dilated vessel. To investigate the mechanism of angioplasty-induced vasospasm, the effect of serotonin-receptor blockade with two serotonin2 (S2) antagonists, LY53857 and sergolexole, was examined in rabbits with focal femoral artery atherosclerosis. In preliminary studies, local infusion of 1-100 micrograms serotonin caused significant femoral artery vasoconstriction (p less than 0.05) in both normal and atherosclerotic rabbits. There was no significant difference in the degree of vasoconstriction induced by equal doses of serotonin in normal and atherosclerotic animals. Infusion of 10 micrograms serotonin produced a 23 +/- 5% decrease in luminal diameter in atherosclerotic femoral arteries. This was blocked by pretreatment with both S2 inhibitors given separately in different animals before serotonin infusion (p less than 0.002). In contrast, LY53857 (sergolexole was not tested) had no significant effect on phenylephrine-induced vasoconstriction, confirming its specificity as an S2-receptor antagonist. Balloon angioplasty of atherosclerotic vessels caused a significant increase in vessel diameter at the angioplasty site (45% increase from baseline diameter, p less than 0.05). This was associated with significant luminal narrowing both proximal (21% reduction from baseline, p less than 0.05) and distal (17% reduction from baseline, p less than 0.03) to the angioplasty site. These proximal and distal changes are most likely due to vasospasm, as there was no histological evidence of thrombus or dissection at these sites to explain the luminal narrowing. Pretreatment of animals with 10 mg LY53857 or 20 mg sergolexole blocked the proximal vasospasm (2.6 +/- 0.4 before versus 2.2 +/- 0.1mm after angioplasty for LY53857, 2.1 +/- 0.4 before versus 2.1 +/- 0.4 mm after angioplasty for sergolexole; p = NS). Treatment with 20 mg LY53857 inhibited both proximal (2.3 +/- 0.1 before versus 2.2 +/- 0.2 mm after angioplasty, p = NS) and distal (1.7 +/- 0.1 before versus 1.6 +/- 0.2 mm after angioplasty, p = NS) vasospasm after angioplasty. Proximal (2.3 +/- 0.5 before versus 2.5 +/- 0.3 mm after) and distal (1.7 +/- 0.2 before versus 1.7 +/- 0.4 mm after) vasospasm was also prevented by pretreatment with 40 mg sergolexole.(ABSTRACT TRUNCATED AT 400 WORDS)

[Pharmacologic study of Curculigo orchioides Gaertn]

The experiments showed that ethanolic extract of Curculigo orchioides had adaptive effects, such as enhancing tolerance towards high temperature and hypoxia. It also had sedative, anticonvulsant and androgen-like effect. Besides, it increased the immunological activity of mice.

A simplified new method for the identification of arboviruses: virus detection using enzyme immunoassay on cultured cells

A simple new method is reported for the identification of arbovirus isolates and the titration of arboviruses. Horseradish peroxidase conjugated Staphylococcus aureus protein A was used for the indirect staining of virus antigens grown in an Aedes albopictus cell line, C6/36 cells. Thirty-five isolates from Culex tritaeniorhynchus mosquitoes were examined by this method and 20 of these were identified as Japanese encephalitis virus (JEV). These results were confirmed by immunofluorescent assay and plaque neutralization test. Comparative titration of JEV, Murray Valley encephalitis (MVE) and Kunjin viruses showed that this method was as sensitive as the chick embryo plaque assay. Specific enzymatic reactions on these virus-infected cells began to appear before day 3 and reached the end-point on day 5 post-infection of C6/36 cells, whereas the cytopathic effect (CPE) appeared about 2 days later than the positive enzymatic reactions. Fixation with 10% formalin for 0.5-8 h did not damage the positive reaction in infected cells and did not increase the background colour of uninfected cells.