HIV Infection in gastric epithelial cells.

Many chronic human immunodeficiency virus (HIV) patients suffer from gastric complaints, including gastric tuberculosis and coinfection of other pathogens. Recent work has demonstrated that a variety of nonimmune cells can act as viral reservoirs, even at the early stage of HIV infection. In this study, we detect HIV viral particles, proteins, and nucleic acids in gastric epithelial cells using clinical samples. These observations are further supported by a simian immunodeficiency virus-infected macaque model. Further, the number of HIV-infected gastric epithelial cells is positively associated with blood viral load, and is negatively correlated with CD4 lymphocyte cell counts. We also demonstrate that HIV infection is accompanied by severe inflammatory response in gastric mucosa. Additionally, HIV infection activates signal transducer and activator of transcription 3 and RelA, and enhances the production of interleukin 6 and tumor necrosis factor α in gastric epithelial cells. The present data suggest that the gastric epithelial cells are natural targets of HIV infection, and HIV infection in epithelial cells contributes to HIV-induced gastric mucosal inflammation.

Chinese yam yield is affected by soil nutrient levels and interactions among N, P, and K fertilizers.

Objective: The current fertilization methods for Chinese yam are uneconomic and unfriend to environment. A rational one is very important to achieve desired balance of high yield of Chinese yam, economic and friend to environment. Here, we studied the effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizers on the yield of 'Qinfeng' Chinese yam in shallow-groove directional cultivation. Methods: The experiments were conducted in Dehua County, Fujian Province, China using a "3414" optimal design. Overall, three fertilizer factors (N, P, and K) were evaluated at the following four levels: 0, no fertilizer; 1, 0.5-fold the typical rate; 2, typical fertilization rate; and 3, 1.5-fold the typical rate. There were 14 different fertilization treatments. Results: Treatment 6 (N2P2K2) produced the longest (75.6 cm) and thickest tubers (4.9 cm) with the highest tuber fresh weight (1311.9 g) and yield (41 015.9 kg/hm2), whereas, treatment 1 produced the shortest (65.6 cm) and thinnest tubers (3.9 cm) with the lowest fresh weight (953.4 g) and yield (28 532.8 kg/hm2) among the 14 fertilizer combinations. The experimental data could be fitted to single-variable quadratic and binary quadratic models but not to a ternary quadratic polynomial model. Appropriate N, P, and K fertilizer application rates increased Chinese yam yield. However, excessive fertilization lowered the yield. Chinese yam yield was significantly and strongly correlated with the amounts of N, P, and K fertilizer applied. Conclusion: Based on the single variable quadratic and binary quadratic models, we propose that the quantities of N, P, and K fertilizer used to grow 1 hm2 'Qinfeng' Chinese yam should be 360-388.3, 90-100.95, and 416.3-675 kg, respectively.

Structural interrogation of a trimeric prefusion RSV fusion protein vaccine candidate by a camelid nanobody.

In the past decade, camelid nanobodies have been developed for multiple applications, including immuno-imaging, cancer immunotherapy, and antiviral therapeutics. Despite the prevalence of these approaches, nanobodies have rarely been used to assess the potency of vaccine antigen candidates, which are primarily based on mAb binding approaches. In this work, we demonstrate that a nanobody-based ELISA method is suitable for characterization of a leading respiratory syncytial virus (RSV) vaccine candidate, RSVPreF3. This nanobody, F-VHH-L66, compares similarly with AM14, an antibody well-known to be specific for the prefusion form of the RSV surface fusion glycoprotein, RSV F. ELISA assays based on F-VHH-L66 were specific for the trimeric, prefusion form of RSV F, the antigen conformation that best generates neutralizing antibodies. Additionally, the F-VHH-L66-based ELISA proved accurate, linear, and stability-indicating. Statistical analysis of 65 independent F-VHH-L66-based ELISA experiments indicated assay performance similar to that of ELISA assays based on AM14. Moreover, the binding kinetics of F-VHH-L66 to RSVPreF3 are comparable to those of AM14 when measured by surface plasmon resonance (SPR). Finally, F-VHH-L66 neutralized RSV(A) with similar efficacy as AM14; this bioactivity data further supports its use as an alternative to AM14 for pre-fusion specific structural characterization of RSVPreF3.

Altered biliary epithelial cell and monocyte responses to lipopolysaccharide as a TLR ligand in patients with primary biliary cirrhosis.

OBJECTIVE: Lipopolysaccharide (LPS) is suspected to trigger primary biliary cirrhosis (PBC) in susceptible individuals, yet the precise mechanism of its effect in PBC remains largely unknown. The aim of this study was to investigate altered responses to LPS ligand for Toll-like receptors (TLRs) in pathogenesis of PBC in vivo and in vitro. MATERIAL AND METHODS: In vivo, we investigated levels of LPS and pro-inflammatory cytokines in sera and expression of LPS receptors in liver tissues from 162 patients with PBC, 325 patients with other liver diseases and 80 healthy controls. In vitro, altered responses to LPS on monocytes and cultured human biliary epithelial cells (BECs) from patients with PBC were determined. RESULTS: Significantly higher levels of LPS in patients with PBC were detected, compared with patients with other liver diseases and healthy controls. Immunohistochemically, expression of TLR4, CD14, CD68 and NF-κB was significantly enhanced in liver tissues from patients with PBC. Before LPS stimulation, we found significantly higher serum levels of tumor necrosis factor-α, interleukin (IL)-1ß, IL-6 and IL-8 in patients with PBC than those in healthy controls. After LPS stimulation, TLR4 expression and pro-inflammatory cytokine production in CD14-positive monocytes and cultured BEC from patients with PBC increased significantly. CONCLUSIONS: These results indicated that patients with PBC were prone to exhibit higher serum LPS level, hypersensitivity of monocytes and BEC to LPS, and enhanced production of pro-inflammatory cytokines. LPS altered expression of TLR4, CD14 and NF-κB on monocytes and BEC, which may be implicated in the pathogenesis and progression of PBC.

CD8+ T cells with high TGF­ß1 expression cause lymph node fibrosis following HIV infection.

Lymph node (LN) fibrosis resulting in cluster of differentiation (CD) 4+ T cell reduction following human immunodeficiency virus (HIV) infection is an important step in the pathogenesis of acquired immunodeficiency syndrome. The mechanisms mediating LN fibrosis following HIV infection have not been completely elucidated. In order to investigate the mechanism of LN fibrosis, the expression of transforming growth factor (TGF)­ß1 was determined in the LNs of HIV­infected individuals by immunohistochemistry and fluorescence­based flow cytometry. The effect of stimulated CD8+ T cells on collagen secretion by fibroblasts was detected using immunofluorescence staining and western blot analysis. The results demonstrated that the LNs of HIV­infected individuals exhibited a significantly increased proportion of CD8+ T cells with high TGF­ß1 expression. These CD8+ T cells demonstrated increased CD38 and programmed cell death protein 1 expression and decreased CD127 expression compared with the controls. CD8+ T cells from the LNs of non­HIV infected individuals expressed a high TGF­ß1 level following stimulation with phorbol­12­myristate 13­acetate. These CD8+T cells subsequently induced the secretion of a large amount of type I collagen in human lymphatic fibroblasts. The results of the present study indicated that CD8+ T cells with high TGF­ß1 expression served an important role in LN fibrosis following HIV infection.

Randomized double-blinded and controlled clinical trial on treatment of HIV/AIDS by Zhongyan-4.

OBJECTIVE: To assess the efficacy and safety of Zhongyan-4 (ZY-4, a Chinese herbal preparation worked out according to the therapeutic principle of supplementing qi, nourishing Yin, clearing heat and detoxication) in treating HIV/AIDS patients in the early or middle stage. METHODS: Adopted was randomized double-blinded and placebo-parallel-controlled method, with 72 HIV/AIDS patients randomly divided into the ZY-4 group (36 patients) treated with ZY-4 and the control group (36 patients) treated with placebo. The treatment course was six months. The index of CD(4)(+), CD(8)(+) counts, body weight, clinical symptom scoring were estimated at 4 time points (0, 1, 3 and 6 month in the course), and also the viral load before and after treatment. The whole course of observation was completed in 63 patients, 30 in the ZY-4 group and 33 in the control group. RESULTS: CD(4)(+) count in the ZY-4 group got elevated by 7.70 +/- 150.96/mm(3) on average, while that in the control group lowered by 27.33 +/- 85.28/mm(3). Fifteen out of the 30 patients in the ZY-4 group had their CD(4)(+) count increased, which was evidently much higher than that in the control group (8/33, P < 0.05), suggesting that the efficacy of ZY-4 is superior to that of placebo in elevating CD(4)(+) count. Moreover, ZY-4 showed actions in elevating CD(45)RA(+) and CD(8)(+) count, reducing HIV virus load, improving clinical symptom/sign and increasing body weight of patients. No obvious adverse reaction was found in the clinical trial. CONCLUSION: ZY-4 has an immunity-protective and/or rebuilding function in HIV/AIDS patients in the early and middle stage, and also shows effects in lowering viral load, increasing body weight and improving symptoms and signs to a certain degree.

Prognostic factors for severe acute respiratory syndrome: a clinical analysis of 165 cases.

This study analyzes single factors that affect the prognosis of severe acute respiratory syndrome (SARS) and establishes a prognosis model by multivariate analysis. We retrospectively analyzed the clinical features of SARS in 165 clinically confirmed severe cases. Both age and existence of other diseases before SARS were significantly correlated with prognosis (r=0.506 and r=0.457, respectively; P<.001). During the acute phase of SARS, lactate dehydrogenase level, degree of hypoxemia, respiratory rate, alpha -hydroxybutyric dehydrogenase level, creatine kinase isoenzyme-MB, platelet count, and number of involved lobes noted on chest radiographs, and so on, correlated markedly with the prognosis (r=0.257-0.788; P<.05). The multivariate prognosis regression model was associated with degree of hypoxemia and platelet count. The model was defined by the formula Py=1=es/(1+es), where S is [2.490 x degree of hypoxemia]-[0.050 x number of platelets], and it had a high sensitivity (91.67%), specificity (98.33%), and accuracy (96.42%). The model could be used to effectively judge the state of illness and the prognosis.

[Analysis of severe acute respiratory syndrome in Beijing].

OBJECTIVE: To study the clinical, laboratory, and radiologic features of 34 cases of severe acute respiratory syndrome (SARS) in Beijing. METHODS: All patients were admitted to the isolation wards. Their demographic, clinical, laboratory, and radiologic characteristics were analyzed. Univariate and multivariate analyses were performed. RESULTS: Eight patients came from a family, and 15 patients were medical staff. The mean age of patients was (33.4 +/- 13.4) years. The latent period varied from 2 to 14 days (median 4 days). The most common symptoms were fever (100%), palpitation (91.7%), myalgia (79.2%), headache (70.8%), diarrhea (73.9%) and cough (58.3%). The mean leucocyte count was (4.6 +/- 1.4) x 10(9)/L, and the mean lymphocyte ratio was 0.27 +/- 0.11. 68.4% of the patients had lymphopenia (absolute lymphocyte count < 1.3 x 10(9)/L). Other common findings included elevated levels of serum alanine aminotransferase, lactate dehydrogenase and erythrocyte sedimentation (76.2%, 28.6% and 47.8%, respectively), and decreased levels of serum iron and albumin (63.2% and 47.8%, respectively). Thirty-two cases had abnormal chest radiographs. In 2 cases in whom typical lung opacities could not be found on the initial plain chest radiographs, thoracic CT proved to be useful. Postmortem examination of 1 patient revealed marked edema with foci of hemorrhage and hyaline membrane formation in the lungs, hemorrhage necrosis and a obvious decline of cells in lymph glands. In a multivariate analysis (Stata 7.0), the independent predictor of an adverse outcome was advanced age (odds ratio per decade of life, 1.6; 95% CI, 1.08 to 2.63; P = 0.007). CONCLUSIONS: Fever, lymphopenia, low serum iron and chest radiograph are helpful to diagnose SARS early; age is the independent predictor of an outcome.

[Epidemiologic features, clinical diagnosis and therapy of first cluster of patients with severe acute respiratory syndrome in Beijing area].

OBJECTIVE: Investigate the features of outbreak epidemic, clinical disease progression of the first SARS cases in Beijing and evaluate the efficacy of therapeutic regimen. METHODS: Twenty-nine patients (11 men and 18 women, 20 - 74 years old age range) were diagnosed with infectious SARS and admitted in our hospital from the March 5th to April 14th, 2003 in this study. The data of clinical presentation and disease progression of all the patients including index subject as the infectious SARS resource patient, her family infected members and 21 health care workers were abstracted. RESULTS: The first SARA outbreak in Beijing was characterized with the cluster feature of resource patient family members and health care providers. The incubation period ranged from 2 to 14 days. All the patients had a fever (temperature > 38 degrees C for over 24 hours) and other manifestations as reported before. Serial chest radiographs showed progressive pathologic air-space disease. Twenty patients showed the severe syndrome with various time ranged from 1 day to 14 days. Two patients died of progressive acute respiratory distress disease. The histologic analysis of one death patient showed diffuse alveolar damage in the two lungs. Twenty-six patients receiving the combined therapy including use of corticosteroid, antiviral ribavirin agents after the onset of symptoms and showed they had an acute self-limited disease course. The oldest patient (74 year old, male) received the healthy convalescent plasma infusion (50 ml) from recovered SARS subject and completely recovered within 21 days, having a shorter disease course. CONCLUSION: SARS is a kind of new self-limited and acute infectious disease. Early diagnosis, early isolation, early antiviral therapy for patients and efficient prevention for health care providers are urgently recommended. In particular, a combinational therapy of use of antiviral agents, preventive antibacterial antibiotics and pulsed dosage of corticosteroid can efficiently raise the clinical recovery rate and decrease mortality of SARS patients.

Prevalence, virology and antiviral drugs susceptibility of hepatitis B virus rtN238H polymerase mutation from 1865 Chinese patients with chronic hepatitis B.

Amino acid substitutions at positions rtN238T/D of the hepatitis B virus (HBV) polymerase have been reported as potential mutations associated with adefovir (ADV) resistance. In this study, we characterized the prevalence of the rtN238H mutation and determined the susceptibility to LAM and ADV using phenotypic analyzes in vitro. One thousand eight hundred and sixty-five HBsAg-positive patients with chronic HBV (CHB) infection were included in this study. HBV genotypes and reverse transcriptase (RT) mutations were determined by direct sequencing. Replication-competent HBV constructs containing the naturally occurring rtN238H mutation were generated and replication capacity and susceptibility to LAM and ADV in transiently transfected hepatoma cell lines were determined. Among 1865 enrolled HBV infected patients, 8.8% (165/1865) showed mutations in the rtN238 locus (143 males/22 females, 91 treatment-naive, 42 ADV-treated, 16 LAM-treated and 16 ADV+LAM-treated), namely 86% rtN238H (142/165), 5.5% rtN238S (9/165), 5.5% rtN238T (9/165) and 3% rtN238D (5/165). Among the rtN238H mutant strains, there were no significant differences between ADV- or/and LAM- treated patients and treated-naive patients (42% vs. 58%). Compared with wild-type HBV, this mutant displayed an equivalent susceptibility to LAM or ADV in phenotypic assays. Importantly, we found that the incidence rate of rtN238H was higher in HBV genotype B infected patients than HBV genotype C subsets (80.3% vs. 19.7%), even without exogenous selection pressures. As rtN238H did neither impair the viral replication efficiency nor susceptibility to LAM or ADV in vitro, rtN238H likely represents background polymorphisms rather than resistance mutations with clinical implications. The incidence of rtN238H may be associated with HBV genotype.

[Frequency, distribution of CD4+, CD8+ T cells and expression of CD38 in gastric mucosa of HIV infections].

OBJECTIVE: To investigate the frequencies and distribution of CD4+ T cells and CD8+ T cells as well as the changes of immune activation in gastric mucosa of HIV-infected individuals. METHODS: 42 HIV-infected individuals were recruited into this investigation, and 36 patients had definite diagnosis of clinical stage. Biopsy of gastric mucosal tissues was performed by fiberoptic gastroscope including 10 normal people as a control group. Then, immunohistochemistry was used to detect expression of CD4, CD8 and CD38 in gastric mucosa, and the distinctions among three groups were analyzed with LEICA Qwin image analysis system. RESULTS: (1) Compared with asymptomatic HIV carriers and control group, CD4 T cells remarkably decreased in the gastric mucosa of AIDS patients (P < 0.01). In gastric mucosa of asymptomatic HIV carriers, there were still some CD4+ T cells in lymphoid follicles and stroma where CD4+ T cells were unevenly distributed, the frequency of CD4+ T cells was not significantly different between asymptomatic HIV carriers and control group (P > 0.05); (2) Phenomenon of CD8+ T cells infiltrating mucosal epithelium and gland was general in HIV-infected individuals. CD8+ T cells took on local excessive hyperplasia in gastric mucosa of some individuals. As compared with control group, CD8+ T cells markedly increased in gastric mucosa of infected individuals (P < 0.01), but the distinction of asymptomatic HIV carriers and AIDS patients was not significant (P > 0.05); (3) CD38-expressing cells mainly distributed over gastric mucosal surface to superficial layer(1/3-2/3 layer) of HIV-infected individuals, and was more intensive than control group (P < or = 0.01), but there was not noticeable difference between asymptomatic HIV carriers and AIDS patients (P > 0.05). CONCLUSION: The frequencies and distribution of gastric mucosal CD4+ T cells of HIV-infected individuals were closely correlated with progression of disease. Disfunction of mucosal immune system which was resulted from HIV infection and injury of CD4+ T cells could be an important cause of CD8+ T cells increasing and CD38-expressing enhancement.

[Primary application of identification-aided system for diagnosis and differential diagnosis of emerging infectious diseases].

OBJECTIVE: To verify the rate of diagnostic fitting between the clinic and the indentification-aided for diagnosis and differential diagnosis system, for emerging infections diseases (EID) established. METHODS: 314 cases of 49 kinds of contagious diseases diagnosed and another 186 patients with fever who not diagnosed were tested by the system. RESULTS: Preliminary verification was made in 314 cases diagnosed which classified to 49 kinds of contagious diseases of infectious diseases and the results showed that the coincidence rate of clinical diagnosis and first diagnosis of this system was 61.9%; the suggestive rate of first three diagnoses was 78.1%, and that of first five diagnoses was 86.6%. The diagnosis of another 186 patients with fever were diagnosed by the system and the results showed that the coincidence rate of clinical diagnosis and first diagnosis was 59.7%; the suggestive rate of first three diagnoses was 77.9%, and that of first five diagnoses was 85.4%. CONCLUSIONS: The system can accurately suggest impossible diagnosis and differential diagnosis, and be useful for our medical work.

Kinetic and crystallographic analysis of active site mutants of Escherichia coli gamma-aminobutyrate aminotransferase.

The E. coli isozyme of gamma-aminobutyrate aminotransferase (GABA-AT) is a tetrameric pyridoxal phosphate-dependent enzyme that catalyzes transamination between primary amines and alpha-keto acids. The roles of the active site residues V241, E211, and I50 in the GABA-AT mechanism have been probed by site-directed mutagenesis. The beta-branched side chain of V241 facilitates formation of external aldimine intermediates with primary amine substrates, while E211 provides charge compensation of R398 selectively in the primary amine half-reaction and I50 forms a hydrophobic lid at the top of the substrate binding site. The structures of the I50Q, V241A, and E211S mutants were solved by X-ray crystallography to resolutions of 2.1, 2.5, and 2.52 A, respectively. The structure of GABA-AT is similar in overall fold and active site structure to that of dialkylglycine decarboxylase, which catalyzes both transamination and decarboxylation half-reactions in its normal catalytic cycle. Therefore, an attempt was made to convert GABA-AT into a decarboxylation-dependent aminotransferase similar to dialkylglycine decarboxylase by systematic mutation of E. coli GABA-AT active site residues. Two of the twelve mutants presented, E211S/I50G/C77K and E211S/I50H/V80D, have approximately 10-fold higher decarboxylation activities than the wild-type enzyme, and the E211S/I50H/V80D has formally changed the reaction specificity to that of a decarboxylase.

Longitudinal alteration of circulating dendritic cell subsets and its correlation with steroid treatment in patients with severe acute respiratory syndrome.

In this study, we found that 74 patients with severe acute respiratory syndrome (SARS) exhibited a rapid, dramatic decrease in numbers of circulating myeloid and plasmacytoid dendritic cells (mDCs and pDCs) during the first 2 weeks of illness (5.3- and 28.4-fold reductions for mDCs and pDCs compared with 25 healthy individuals, respectively), with slow return to normal cell numbers during convalescence (weeks 5-7 of illness on average). In addition, numbers of circulating CD4 and CD8 T cells exhibited milder reductions (2.1- and 1.8-fold at week 1) and earlier return to normal at a mean of weeks 3 and 4, respectively. A significant inverse correlation was found between numbers of DC and T-cell subsets and high-dose steroid treatment. Our novel findings thus suggest that the acute SARS-coronavirus infection probably contributes to the initial reduction of DC and T-cell subsets in blood, and that high-dose steroid administration may subsequently exacerbate and prolong low expression of the cell subsets. These findings will aid the framing of further studies of the immunopathogenesis of SARS.

A continuous-flow system for high-precision kinetics using small volumes.

A generally applicable continuous-flow kinetic analysis system that gives data of a precision high enough to measure small kinetic isotope effects for enzymatic and nonenzymatic reactions is described. It employs commercially available components that are readily assembled into an apparatus that is easy to use. It operates under laminar flow conditions, which requires that the time between the initiation of the reaction in the mixer and the observation be long enough that molecular diffusion can effect a symmetrization of the concentration profile that results from a thin plug of reagents introduced at the mixer. The analysis of a second-order irreversible reaction under pseudo-first-order conditions is presented. The Yersinia pestis protein tyrosine phosphatase catalyzed hydrolysis of p-nitrophenyl phosphate is characterized with the system, and a proton inventory on kcat is presented.

[Clinical studies on the short-course and efficient treatment of mumps meningitis].

OBJECTIVE: To investigate the short-course and efficient way to treat mumps meningitis. METHODS: Totally 155 cases of mumps meningitis treated by intrathecal injection with dexamethasone only once were enrolled as experimental group and 55 similar cases treated with the common therapy as control. RESULTS: The time for recoveries of temperature, headache, the pathologic reflexes and the total time of treatment were 32 hours, 15 hours, 12 hours and 3.1 days, respectively, while those of the control group were 58 hours, 24 hours, 32 hours, 6.5 days respectively. There was statistical difference between the two groups (P<0.01 or 0.05). CONCLUSIONS: Intrathecal injection with dexamethasone only once is efficient and safe in the treatment of mumps meningitis.

The boron-catalyzed polymerization of dimethylsulfoxonium methylide. A living polymethylene synthesis.

Trialkyl and aryl organoboranes catalyze the polymerization of dimethylsulfoxonium methylide (1). The product of the polymerization is a tris-polymethylene organoborane. Oxidation affords linear telechelic alpha-hydroxy polymethylene. The polymer molecular weight was found to be directly proportional to the stoichiometric ratio of ylide/borane, and polydispersities as low as 1.01-1.03 have been realized. Although oligomeric polymethylene has been the most frequent synthetic target of this method, polymeric star organoboranes with molecular weights of 1.5 million have been produced. The average turnover frequency at 120 degrees C in 1,2,4,5-tetrachlorobenzene/toluene is estimated at >6 x 10(6) g of polymethylene (mol boron)(-1) h(-1). The mechanism of the polyhomologation reaction involves initial formation of a zwitterionic organoborane.ylide complex which breaks down in a rate-limiting 1,2-alkyl group migration with concomitant expulsion of a molecule of DMSO. The reaction was found to be first order in the borane catalyst and zero order in ylide. DMSO does not interfere with the reaction. The temperature dependence of the reaction rate yielded the following activation energy parameters (toluene, DeltaH(++) = 23.2 kcal/mol, DeltaS(++) = 12.6 cal deg/mol, DeltaG(++) = 19.5 kcal/mol; THF, DeltaH(++) = 26.5 kcal/mol, DeltaS(++) = 21.5 cal deg/mol, DeltaG(++) = 20.1 kcal/mol).

Crystal structures of unbound and aminooxyacetate-bound Escherichia coli gamma-aminobutyrate aminotransferase.

The X-ray crystal structures of Escherichia coli gamma-aminobutyrate aminotransferase unbound and bound to the inhibitor aminooxyacetate are reported. The enzyme crystallizes from ammonium sulfate solutions in the P3(2)21 space group with a tetramer in the asymmetric unit. Diffraction data were collected to 2.4 A resolution for the unliganded enzyme and 1.9 A resolution for the aminooxyacetate complex. The overall structure of the enzyme is similar to those of other aminotransferase subgroup II enzymes. The ability of gamma-aminobutyrate aminotransferase to act on primary amine substrates (gamma-aminobutyrate) in the first half-reaction and alpha-amino acids in the second is proposed to be enabled by the presence of Glu211, whose side chain carboxylate alternates between interactions with Arg398 in the primary amine half-reaction and an alternative binding site in the alpha-amino acid half-reaction, in which Arg398 binds the substrate alpha-carboxylate. The specificity for a carboxylate group on the substrate side chain is due primarily to the presence of Arg141, but also requires substantial local main chain rearrangements relative to the structurally homologous enzyme dialkylglycine decarboxylase, which is specific for small alkyl side chains. No iron-sulfur cluster is found in the bacterial enzyme as was found in the pig enzyme [Storici, P., De Biase, D., Bossa, F., Bruno, S., Mozzarelli, A., Peneff, C., Silverman, R. B., and Schirmer, T. (2004) J. Biol. Chem. 279, 363-73.]. The binding of aminooxyacetate causes remarkably small changes in the active site structure, and no large domain movements are observed. Active site structure comparisons with pig gamma-aminobutyrate aminotransferase and dialkylglycine decarboxylase are discussed.

[Changes of blood cells in patients with severe acute respiratory syndrome].

OBJECTIVE: To investigate the changes of blood corpuscles of patients with severe acute respiratory syndrome (SARS) in Beijing. METHODS: Totally 43 patients (21 male and 22 female, 19-74 years old age range) diagnosed as of probable SARS were included in this study. Their corpuscles in the peripheral blood were tested every two days, and the results were analyzed. RESULTS: Patients with SARS were more likely to develop leukocytopenia, lymphopenia and thrombocytopenia in the early period of disease than those in control group. The situation, especially lymphopenia and thrombocytopenia, could not be reversed in patients who died. Persistent low counts of lymphocytes and platelets at presentation might be associated with adverse outcomes. CONCLUSION: Low counts of leukocytes, lymphocytes and platelets were common among patients in the early stage of SARS. Persistent Lymphopenia and thrombocytopenia may be associated with the prognosis.