[Analysis on the household secondary attack rates of the SARS-CoV-2 Delta variant and the associated factors].

Objective: To evaluate the household secondary attack rates of the SARS-CoV-2 Delta variant and the associated factors. Methods: A COVID-19 outbreak caused by the Delta variant occurred in Nanjing in July 2021. A total of 235 cases with current addresses in Nanjing were reported from 171 households. The subjects in this study were selected from household close contact(s) of infected cases. The information on household index cases and their contacts were collected, and the household secondary attack rate (HSAR) and the risk factors were analyzed by the multi-factor logistic regression model. Results: A total of 234 cases of household close contacts and 64 household secondary cases were reported from 103 households, and the HSAR was 27.4% (64/234, 95%CI:22.0% to 33.4%). The proportions of household size for 2 to 3, 4 to 5, and 6 to 9 were 64.1% (66), 26.2% (27) and 9.7% (10), respectively. A total of 35 cases of household cluster outbreaks were reported (35/103, 34.0%). The number of the first case in the household (FCH) was 103 and males accounted for 27.2% (28 cases), with the median age (Q1, Q3) of 49 (9, 56). The number of household close contacts was 234 and males accounted for 59.0% (138 cases), with the median age (Q1, Q3) of 42 (20, 55) and the median exposure period (Q1, Q3) of 3 (1, 3) days. The multi-factor logistic regression model showed that the higher HSAR was observed in the FCH with the features of airport staff (OR=2.913, 95%CI:1.469-5.774), detection from home quarantine screening (OR=6.795, 95%CI:1.761-26.219) and detection from mass screening (OR=4.239, 95%CI:1.098-16.368). Meanwhile, higher HSAR was observed in cases with longer household exposure (OR=1.221, 95%CI:1.040-1.432), non-vaccination (OR=2.963, 95%CI:1.288-6.813) and incomplete vaccinations (OR=2.842, 95%CI:0.925-8.731). Conclusion: The generation interval of the Delta variant is shortened, and the ability of transmission within the household is enhanced. In the outbreak in Nanjing, the associated factors of HSAR are occupation, detection route, vaccination and exposure period.

Different amino acid supplementation patterns in low-protein diets on growth performance and nitrogen metabolism of goslings from 1 to 28 days of age.

The investigation aimed to explore the suitable amino acid (AA) supplementation pattern for goslings under low-protein diets. A total of 364 1-day-old male goslings were randomly divided into 4 experimental groups, with 7 pens containing 13 goslings each. The 4 groups were control (CP, 18.55%), LPM (CP, 15.55% + major AA), LPA (CP, 15.55% + all AA), and LPR (CP, 15.55% + AA content reduced proportionally to the control's CP). The corn-soybean meal diets are formulated according to the ideal AA model of goose and its nutritional requirements. The results indicated that the ADG and BW were the lowest, and the F: G was the highest in LPR (P < 0.05); the other three groups were not significantly different (P > 0.05). The ADFI and mortality were not different among all the groups (P > 0.05). Among the AA content in serum and breast muscle, lysine in serum significantly decreased compared with the control (P < 0.05). The UREA content was approximately 2-fold higher in the LPR group than in the LPM and LPA groups (P < 0.05). No difference in IgA, IgG, IgM, and IgE levels was observed among the groups (P > 0.05). The nitrogen excretion was decreased in LPM and LPA compared to the control and LPR (P < 0.05). Nitrogen deposition did not differ among groups (P > 0.05). Nitrogen utilization was highest in the LPA and LPM groups, followed by the control group and LPR (P < 0.05). In conclusion, the patterns of supplementation of major AA and all AA in low-protein diets (CP, 15.55%) had no adverse effect on the growth performance compared with the control (CP, 18.55%) of the goslings. Besides, the two patterns could decrease nitrogen excretion and increase nitrogen utilization. Furthermore, from the perspective of dietary cost and environmental protection, the pattern of supplementing major AA in a corn-soybean meal low-protein diet is suggested.

Specific PCR-based detection of Phomopsis heveicola the cause of leaf blight of Coffee (Coffea arabica L.) in China.

Coffee (Coffea arabica L.) is currently grown in many tropical and subtropical areas countries and is a major traded commodity for the developing world. Coffee leaf blight, caused by Phomopsis heveicola, is one of the most important fungal diseases dangerous to coffee crops in China. This study aimed to develop a PCR-based diagnostic method for detecting P. heveicola in planta. Specific primers (CPHF/CPHR) were designed based on sequence data of region of internal transcribed spacer (ITS1 and ITS4) of P. heveicola. The efficiency and specificity of CPHF/CPHR were established by PCR analysis of DNA from P. heveicola strains isolated from China and fungal isolates of other genera. A single amplification product of 318 bp was detected from DNA P. heveicola isolates. No amplification product was observed with any of the other fungal isolates tested. The specific primers designed and employed in PCR detected P. heveicola up to 3 pg from DNA isolated. This is the first report on the development of a species-specific PCR assay for identification and detection of P. heveicola. Thus, the PCR-based assay developed was very specific, rapid and sensitive tool for the detection of pathogen P. heveicola.

Effects of cottonseed meal on slaughter performance, meat quality, and meat chemical composition in Jiangnan White goslings.

Cottonseed meal (CSM), which is an unconventional protein material with abundant sources, high protein content, and a relatively cheap price, can be used in poultry diets. The aim of this study was to investigate the effects of CSM on slaughter performance, meat quality and meat chemical composition in Jiangnan White goslings. A total of 300 healthy 28-day-old male goslings were randomly divided into 5 treatments, with 6 pens containing 10 geese each. Five isonitrogenous and isocaloric experimental diets were formulated such that 0% (a corn-soybean meal basal diet, control), 25% (CSM25), 50% (CSM50), 75% (CSM75), and 100% (CSM100) protein from soybean meal was replaced with CSM (corresponding to 0, 6.73, 13.46, 20.18, and 26.91% CSM in the feed, respectively). On day 70, 1 goose from each pen (6 geese per treatment) was randomly selected and killed to measure the slaughter performance, meat quality, and the meat amino acid (AA) and fatty acid (FA) compositions. The results showed that dietary CSM did not affect the slaughter performance or meat quality of geese (P > 0.05). The fat content of breast muscle in the CSM100 group was higher than that in the control group (P < 0.05). A concentration of 13.46% or more dietary CSM increased the threonine content but decreased the cysteine content, and 20.18% dietary CSM also decreased the valine content (P < 0.05). Dietary CSM concentration had no effect on the content of total saturated FAs (SFAs, P > 0.05), but 20.18 and 26.91% dietary CSM increased the content of total monounsaturated FAs and decreased the content of total polyunsaturated FAs (PUFAs) and PUFA/SFA in the breast muscle of geese (P < 0.05). In conclusion, dietary CSM did not affect the slaughter performance or meat quality of geese, but the replacement of soybean meal with CSM in whole or high proportion altered the composition of AAs and FAs in breast muscle.

[Etiological analysis and establishment of a discriminant model for lower respiratory tract infections in hospitalized patients].

Objective: To analyze the pathogens of lower respiratory tract infection(LRTI) including bacterial, viral and mixed infection, and to establish a discriminant model based on clinical features in order to predict the pathogens. Methods: A total of 243 hospitalized patients with lower respiratory tract infections were enrolled in Fujian Provincial Hospital from April 2012 to September 2015. The clinical data and airway (sputum and/or bronchoalveolar lavage) samples were collected. Microbes were identified by traditional culture (for bacteria), loop-mediated isothermal amplification(LAMP) and gene sequencing (for bacteria and atypical pathogen), or Real-time quantitative polymerase chain reaction (Real-time PCR)for viruses. Finally, a discriminant model was established by using the discriminant analysis methods to help to predict bacterial, viral and mixed infections. Results: Pathogens were detected in 53.9% (131/243) of the 243 cases.Bacteria accounted for 23.5%(57/243, of which 17 cases with the virus, 1 case with Mycoplasma pneumoniae and virus), mainly Pseudomonas Aeruginosa and Klebsiella Pneumonia. Atypical pathogens for 4.9% (12/243, of which 3 cases with the virus, 1 case of bacteria and viruses), all were mycoplasma pneumonia. Viruses for 34.6% (84/243, of which 17 cases of bacteria, 3 cases with Mycoplasma pneumoniae, 1 case with Mycoplasma pneumoniae and bacteria) of the cases, mainly Influenza A virus and Human Cytomegalovirus, and other virus like adenovirus, human parainfluenza virus, respiratory syncytial virus, human metapneumovirus, human boca virus were also detected fewly. Seven parameters including mental status, using antibiotics prior to admission, complications, abnormal breath sounds, neutrophil alkaline phosphatase (NAP) score, pneumonia severity index (PSI) score and CRUB-65 score were enrolled after univariate analysis, and discriminant analysis was used to establish the discriminant model by applying the identified pathogens as the dependent variable. The total positive predictive value was 64.7%(77/119), with 66.7% for bacterial infection, 78.0% for viral infection and 33.3% for the mixed infection. Conclusions: The mostly detected pathogens were Pseudomonas aeruginosa, atypitcal pathogens, Klebsiella pneumoniae, influenza A virus and human cytomegalovirus in hospitalized patients with LRTI in this hospital. The discriminant diagnostic model established by clinical features may contribute to predict the pathogens of LRTI.

Identification of lipopeptides produced by Bacillus subtilis Czk1 isolated from the aerial roots of rubber trees.

We obtained a strain of Bacillus subtilis, which we named Czk1, from the aerial roots of rubber trees. This bacterial isolate exhibits strong antagonistic activity against Ganoderma pseudoferreum, Phellinus noxius, Helicobasidium compactum, Rigidoporus lignosus, Sphaerostilbe repens, and Colletotrichum gloeosporioides. Our earlier research has shown that the antagonistic activity of a fermentation supernatant Czk1 isolate produces a complex mixture of lipopeptides. In this study, we used methanol to extract crude lipopeptides, purified them using a Sephadex G-25 column, cloned the lipopeptide genes, and analyzed purified fractions by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) to identify the lipopeptides from B. subtilis strain Czk1. The cloned lipopeptide genes included those that encode the enzymes lpa, ituD, sfp, and fenB. The crude lipopeptides were purified and found in five fractions. Further analysis revealed that five fractions of the purified composition contained members of the surfactin, iturin, fengycin, and bacillomycin families of antibiotics. This suggests that these lipopeptides from strain Czk1 have potential as plant disease biocontrol agents.

[Expression of eosinophils and IL-33 levels in peripheral blood of patients with allergic rhinitis].

Objective:To investigate the relationship between the count of eosinophils(EOS) in peripheral blood and the serum levels of IL-33, and to discuss the relations among serum levels of IL-33, the count of EOS, visual analog scale (VAS) in different groups.Method:According to different treatments, the patients are divided into three groups: the untreated allergic rhinitis (AR) group (group A), the AR group who had been treated subcutaneous imunotherapy (SCIT) for at least a year (group B) and the AR complicated with allergic asthma group who had been treated subcutaneous imunotherapy (SCIT) for at least a year (gourp C). All subjects were conducted blood cell analysis, and EOS were counted. The serum levels of IL-33 were measured by enzyme linked immune (ELISA), and the obtained date were analysed by GraphPad.Prism 5.0 and SPSS 22.0.AR patients were asked to fill out VAS and were assessed nasal symptoms.Result:The serum levels of IL-33 in the group A were higher than that in other subjects (P<0.05).The serum levels of IL-33 in the group B showed no significant difference between the group B and the group C (P> 0.05).The serum levels of IL-33 in the group B were higher than that in the control group (P<0.05).The serum levels of IL-33 in the group C were higher than that in the control group (P<0.05).The count of EOS in the group A were higher than that in other subjects, and there is no difference between with each other (P> 0.05).The VAS in the group A were higher than that in the group B (P<0.05) and there is no significant difference between the group A and the group C (P<0.05).There is no difference between the group B and the group C(P<0.05).After at least one-year SCIT, the symptoms of AR patients were obviously relieved, such as consciously rhinobyon, rhinorrhea, sneezing and so on. Spearman test showed the serum levels of IL-33 in the AR patients has a weak correlation with the count of eosinophils (P> 0.05, r=0.287).Conclusion:SCIT is an effective treatment for AR patients. role on AR, which can alleviate the symptoms of patients, also can reduce the levels of IL-33 and the count of EOS in peripheral blood.

Enhanced Capacitance of TiO2 Single Crystals Through Chemically Deposited Graphene Films.

Single-crystals of titanium oxide (TiO2) were wrapped in a graphene (G) film by chemical deposition. The morphology, composition and structure of the resulting composite were subsequently characterized by SEM, TEM, XRD and FT-IR analysis. The electrochemical properties of the composites were studied by cyclic voltammetry, which showed that the introduction of graphene enhances the electrode conductivity, thereby improving the supercapacitive behavior of TiO2. Galvanostatic charge-discharge tests demonstrated that a supercapacitor device fabricated from TiO2 crystals wrapped in graphene (G-TiO2) exhibits a good cycle life, with 94% stability even after 1000 cycles.

MoO2-CoO coupled with a macroporous carbon hybrid electrocatalyst for highly efficient oxygen evolution.

Cost-effective electrocatalysts for oxygen evolution reactions are attractive for energy conversion and storage processes. A high-performance oxygen evolution reaction (OER) electrocatalyst composed of 3D ordered microporous carbon and a MoO2 skeleton modified by cobalt oxide nanoparticles (MoO2-CoO-Carbon) is produced through a template method. This unique 3DOM structure finely combines the larger surface area of the 3D carbon skeleton and MoO2 as well as stablizes anchoring sites for CoO nanocrystals on the skeleton. The synergistic effect between the catalytic activity between MoO2 and CoO as well as the enhanced electron transport arising from the carbon skeleton contributed to superior electrocatalytic OER properties of MoO2-CoO-Carbon. The M200-C-Carbon hybrid with an overpotential as low as 0.24 V is among the best reported Mo-based OER catalysts. Moreover, the turnover frequency at an overpotential of 0.35 V is 6 times as high as that of commercial RuO2.

Assessment of sensitivity and virulence fitness costs of the AvrPik alleles from Magnaporthe oryzae to isoprothiolane.

The in vitro sensitivity of AvrPik allele isolates of Magnaporthe oryzae to isoprothiolane was examined and the virulence fitness costs of AvrPik allele isolates to isoprothiolane were assessed. Isoprothiolane was found to suppress the radial growth of AvrPik allele isolates at all concentrations (1, 5, 10, 15, and 20 µg/mL). Generally, a higher isoprothiolane concentration has a stronger inhibitory effect on mycelial growth in AvrPik allele isolates at 6 and 10 days after inoculation. The inhibitory effect of isoprothiolane also increased with treatment time. To determine whether a correlation existed between the in vitro sensitivity of AvrPik allele isolates and virulence, the half-maximal inhibitor concentration and 75% of the maximum inhibitor concentration were calculated for each mutation isolate and wild-type isolate. Based on these values and virulence, no significant correlation between the susceptibility of AvrPik allele isolates and virulence was detected. In summary, no fitness costs were associated with sensitivity of blast isolates carrying specific AvrPik alleles to different virulence.

Design of a highly sensitive ethanol sensor using a nano-coaxial p-Co3O4/n-TiO2 heterojunction synthesized at low temperature.

In this paper, we describe the design, fabrication and gas-sensing tests of nano-coaxial p-Co3O4/n-TiO2 heterojunction. Specifically, uniform TiO2 nanotubular arrays have been assembled by anodization and used as templates for generation of the Co3O4 one-dimensional nanorods. The structure morphology and composition of as-prepared products have been characterized by SEM, XRD, TEM, and XPS. A possible growth mechanism governing the formation of such nano-coaxial heterojunctions is proposed. The TiO2 nanotube sensor shows a normal n-type response to reducing ethanol gas, whereas TiO2-Co3O4 exhibits p-type response with excellent sensing performances. This conversion of sensing behavior can be explained by the formation of p-n heterojunction structures. A possible sensing mechanism is also illustrated, which can provide theoretical guidance for the further development of advanced gas-sensitive materials with p-n heterojunction.

Characterization of self-organized TiO2 nanotubes on Ti-4Zr-22Nb-2Sn alloys and the application in drug delivery system.

In this study, the self-organized TiO(2) nanotubes grown by anodization of Ti-4Zr-22Nb-2Sn at different potentials, concentration of NH(4)F and anodization time was investigated. The morphology of nanotubes was observed by FE-SEM. The drug-loaded nanotubes were also fabricated in aqueous media containing minocycline hydrochloride. They were characterized by SEM, XPS and FT-IR. The results showed that the drug of minocycline hydrochloride (MH) was loaded in the nanotubes. The release effects were studied in phosphate buffer solution (PBS). The release rate of MH from TiO(2) nanotubes with shorter tube length in PBS was lower than the one of MH from longer nanotubes. The sustaining release time could last at least 150 h. Hence, it is a promising method to eliminate the harmful reactions by carrying drug in the tubes when the titanium alloys were used as biomedical implants.

Impaired dopaminergic neurotransmission and microtubule-associated protein tau alterations in human LRRK2 transgenic mice.

Mutations in the Leucine Rich Repeat Kinase 2 (LRRK2) gene, first described in 2004 have now emerged as the most important genetic finding in both autosomal dominant and sporadic Parkinson's disease (PD). While a formidable research effort has ensued since the initial gene discovery, little is known of either the normal or the pathological role of LRRK2. We have created lines of mice that express human wild-type (hWT) or G2019S Lrrk2 via bacterial artificial chromosome (BAC) transgenesis. In vivo analysis of the dopaminergic system revealed abnormal dopamine neurotransmission in both hWT and G2019S transgenic mice evidenced by a decrease in extra-cellular dopamine levels, which was detected without pharmacological manipulation. Immunopathological analysis revealed changes in localization and increased phosphorylation of microtubule binding protein tau in G2019S mice. Quantitative biochemical analysis confirmed the presence of differential phospho-tau species in G2019S mice but surprisingly, upon dephosphorylation the tau isoform banding pattern in G2019S mice remained altered. This suggests that other post-translational modifications of tau occur in G2019S mice. We hypothesize that Lrrk2 may impact on tau processing which subsequently leads to increased phosphorylation. Our models will be useful for further understanding of the mechanistic actions of LRRK2 and future therapeutic screening.

Estrogen receptor beta is involved in the anorectic action of estrogen.

OBJECTIVE: Estrogen has been implicated in feeding behavior and adiposity. This study was undertaken to elucidate the mechanism underlying the anti-obesity and anorectic action of estrogen and the role of estrogen receptor (ER) in the central nervous system. METHODS AND RESULTS: Ovariectomy in 8-week-old female Wistar rats induced hyperphagia along with an increase in body weight and abdominal fat accumulation compared to control sham-operated rats. These changes were fully reversed by subcutaneous replacement of estradiol and were abrogated by pair-feeding. Then, the effects of intracerebroventricular infusion of estradiol, alone or in combination with antisense oligodeoxynucleotides (ODN), for ER in ovariectomized rats were examined. The estradiol group showed 10-20% lower daily food intake, and after the 2-week infusion period a 14% reduction in body weight with a similar reduction in abdominal fat compared to the vehicle group. The inhibitory effect of estradiol on food intake and body weight was blocked by co-administration of ER-beta antisense ODN, whereas ER-alpha antisense ODN did not show any influence. CONCLUSION: These results indicate that ER-beta in the central nervous system is involved in the anorectic action of estrogen.

Induction of nuclear orphan receptor NGFI-B gene and apoptosis in rat vascular smooth muscle cells treated with pyrrolidinedithiocarbamate.

NGFI-B is one of the orphan nuclear receptors, and its gene is implicated in the apoptosis of T cells. The aim of this study was to investigate the expression and the role of NGFI-B in vascular smooth muscle cells (VSMCs). Pyrrolidinedithiocarbamate (PDTC) is a modulator of an oxidative state and is reported to induce apoptosis only when the density of VSMCs is low. Under low VSMC density (10 000 cells/cm(2)), addition of PDTC (0.1 to 10 micromol/L) caused apoptosis of VSMCs, which was confirmed by Hoechst 33258 staining under fluorescence microscopy. At low VSMC density, expression of NGFI-B mRNA was induced 1 hour after the addition of PDTC, peaking at 6 hours, and persisted for up to 12 hours. The protein level of NGFI-B was increased 4 hours after PDTC addition and persisted for up to 12 hours. Under low VSMC density, PDTC-induced expression of NGFI-B mRNA was correlated with the magnitude of apoptosis, which was quantified by enzyme immunoassay for histone-associated DNA fragments. In contrast, when the density of VSMCs was high (50 000 cells/cm(2)), PDTC did not induce apoptosis, and the expression of NGFI-B was only transient. This transient expression pattern was also seen when VSMCs were treated with phorbol ester, calcium ionophore, hydrogen peroxide, or angiotensin II, even at low cell density. We next investigated whether the NGFI-B gene may act as a transcription factor under treatment with PDTC by measuring the promoter activity of luciferase reporter plasmids that contained typical NGFI-B-responsive elements. The PDTC-induced transcriptional activity of NGFI-B was 2-fold higher at low cell density than at high cell density. These data demonstrate that NGFI-B can be induced in VSMCs and suggest that NGFI-B may play a role in PDTC-induced VSMC apoptosis.

Production, purification, and characterization of an intracellular aflatoxin-detoxifizyme from Armillariella tabescens (E-20).

Some Armillariella tabescens (E-20) multienzymes have previously been reported to present detoxifying activities against aflatoxins. In this paper, we describe the isolation purification of an intracellular enzyme, named aflatoxin-detoxifizyme, which exhibited detoxification activity on aflatoxin B(1) (AFB(1)). This aflatoxin-detoxifizyme exhibited a specific activity of 7.09 nmol min/mg at pH 6.0 and 28 degrees C. The apparent molecular mass was 51.8 kDa as determined by SDS-PAGE. The isoelectric point was estimated to be 5.4 and optimum activity for the enzyme was found at pH 6.8 and 35 degrees C. The activity of the purified enzyme was confirmed by Ames test.

Estrogen prevents oxidative stress-induced endothelial cell apoptosis in rats.

BACKGROUND: Estrogen replacement attenuates the increased risk of cardiovascular disease in postmenopausal women. Recent studies using an in vitro culture system have shown that estrogen inhibits endothelial cell (EC) apoptosis. The in vivo relevance of this finding, however, is not defined. To do so, we have developed a rat vascular injury model in which EC apoptosis induced by hydrogen peroxide plays a role. METHODS AND RESULTS: Intracarotid arterial administration of 0.01 mmol/L hydrogen peroxide for 5 minutes evoked EC apoptosis after 6 to 24 hours, determined by nuclear staining with Hoechst 33342, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, and electron microscopy. Apoptosis was associated with EC loss and was followed by EC regeneration at 72 hours and neointima formation at 1 to 2 weeks. Estradiol replacement in ovariectomized female Wistar rats decreased the rate of apoptotic ECs by approximately 50%, assayed by nuclear morphology of en face specimens, resulting in increased remaining ECs and decreased neointima formation. Progesterone did not influence the effects of estradiol on EC apoptosis. CONCLUSIONS: These results provide new insight into the cardioprotective action of estrogen as well as a paradigm of the response-to-injury hypothesis.

Red wine polyphenols inhibit proliferation of vascular smooth muscle cells and downregulate expression of cyclin A gene.

BACKGROUND: Red wine polyphenols have been shown to contribute to the "French paradox" phenomenon, which consists of lower morbidity and mortality from coronary heart disease in the French population. Although vascular smooth muscle cell (VSMC) proliferation plays an important role in the progression of atherosclerotic lesions, the effects of red wine polyphenols on VSMC proliferation have not been elucidated. METHODS AND RESULTS: We extracted the total polyphenolic fraction from red wine (RW-PF) by column chromatography. Treatment with RW-PF showed a potent inhibitory effect on the proliferation and DNA synthesis of cultured rat aortic smooth muscle cells (RASMCs). In contrast, the inhibitory effect of RW-PF on the proliferation of bovine carotid endothelial cells was observed only at much higher concentrations. To elucidate the molecular mechanisms of this antiproliferative effect of RW-PF on RASMCs, we investigated the effects of RW-PF on cell cycle regulation. RW-PF downregulated the expression of cyclin A mRNA and cyclin A promoter activity. In addition, RW-PF decreased the binding of nuclear proteins to the activating transcription factor (ATF) site in the cyclin A promoter and downregulated the mRNA levels of transcription factors, cAMP-responsive element-binding protein (CREB), and ATF-1. CONCLUSIONS: These results suggest that the downregulation of cyclin A gene expression may contribute to the antiproliferative effect of red wine polyphenols on RASMCs through the inhibition of transcription factor expression.

[Determination of plasma homocysteine by high performance liquid chromatography with fluorescence detection].

This article report a highly sensitive method specific for the determination of homocysteine in plasma by high performance liquid chromatography with fluorescence detection. Half mL plasma with 100 microL 0.11 mol/L sodium borohydride in 50 mmol/L Tris-HCl (pH 9.0) was kept at 30 degrees C for 30 min, and then 0.5 mL 0.5 mol/L perchloric acid was added. After the mixture was kept at room temperature for 10 min and centrifuged at 15,000 r/min for 10 min, 0.5 mL aliquots of the supernatant solution was pipetted into another vial containing 0.1 mL 3 mmol/L Bromobimane in 1.0 mol/L Na2EDTA (pH 7.0) and 0.7 mL of 90 mmol/L ammonium bicarbonate buffer containing 1.43 mol/L Na2EDTA, pH 8.0. The content was mixed, kept at 37 degrees C for 30 min and centrifuged at 15,000 r/min for 10 min. Then 10 microL aliquots of the supernatant solution was injected into a high performance liquid chromatograph with fluorescence detector. The chromatographic conditions were as follows: an ODS column (4.6 mm i.d. x 150 mm, 5 microns), was eluted with a flow rate of 1.0 mL/min. The fluorescence detector was operated at lambda ex 365 nm and lambda em 475 nm. Mobile phase frompump A was 3% methanol containing 0.25% acetic acid. In gradient elution program the methanol from pump B was as follows: 0-8 min, 5%; 8-15 min, 5%-12%; 15-20 min, 12%; 20-30 min, 12%-20%; 30-32 min, 20%; 32-35 min, 20%-100%; 35-40 min, 100%; 40-43 min, 100%-5%; 43-45 min, 5%. The method proved to be linear in the range of 2.5-80.0 mumol/L with a regression coefficient of 0.9988. The minimum detection limit was 0.5 mumol/L, the recoveries were 94.0%-112.0%, and the RSD values were less than 5.6%.