一氧化氮及在脑发育中的作用

一氧化氮(NO)是一种小分子气体,是生物体内第一个被证实的气体信息分子。自1988年Carthwaite首次提出在神经系统中的传导作用后,NO在神经系统中的作用越来越受到重视。NO具有脂溶性、在体内易扩散、半衰期短(只有数秒钟)等生物学特征。体内的NO是由一氧化氮合酶(NOS)以左旋精氨酸为底物催化生成。     

Effect of heterogeneous ventilation and nitric oxide production on exhaled nitric oxide profiles.

Elevated exhaled nitric oxide (NO) in the breath of asthmatic subjects is thought to be a noninvasive marker of lung inflammation. Asthma is also characterized by heterogeneous bronchoconstriction and inflammation, which impact the spatial distribution of ventilation in the lungs. Since exhaled NO arises from both airway and alveolar regions, and its level in exhaled breath depends strongly on flow, spatial heterogeneity in flow patterns and NO production may significantly affect the exhaled NO signal. To investigate the effect of these factors on exhaled NO profiles, we developed a multicompartment mathematical model of NO exchange using a trumpet-shaped central airway segment that bifurcates into two similarly shaped peripheral airway segments, each of which empties into an alveolar compartment. Heterogeneity in flow alone has only a minimal impact on the exhaled NO profile. In contrast, placing 70% of the total airway NO production in the central compartment or the distal poorly ventilated compartment can significantly increase (35%) or decrease (-10%) the plateau concentration, respectively. Reduced ventilation of the peripheral and acinar regions of the lungs with concomitant elevated NO production delays the rise of NO during exhalation, resulting in a positive phase III slope and reduced plateau concentration (-11%). These features compare favorably with experimentally observed profiles in exercise-induced asthma and cannot be simulated with single-path models. We conclude that variability in ventilation and NO production in asthmatic subjects impacts the shape of the exhaled NO profile and thus impacts the physiological interpretation.     

Effect of nitric oxide on catharanthine production and growth of Catharanthus roseus suspension cells

Sodium nitroprusside (SNP) was used as the donor of nitric oxide (NO) to investigate its effect on catharanthine synthesis and the growth of Catharanthus roseus suspension cells. The results showed that SNP at high concentrations (10.0 and 20.0 mmol/L) stimulated catharanthine formation of C. roseus cells, but inhibited growth of the cells. Low concentrations of SNP (0.1 and 0.5 mmol/L) enhanced the growth of C. roseus cells, but had no effect on catharanthine synthesis. The maximum total catharanthine production was achieved by the addition of 0.5 and 10.0 mmol/L SNP to the cultures at day 0 and day 10, respectively, being about threefold of the control. NO-induced catharanthine production of C. roseus cells was strongly suppressed by jasmonic acid (JA) biosynthesis inhibitor ibuprofen (IBU) and nordihydroguaiaretic (NDGA). The result suggests that the stimulatory role of NO on catharanthine production is partially JA-dependent.     

Seroprevalence of Chlamydophila pneumoniae in ischaemic heart disease

We investigated the presence of Chlamydophila pneumoniae antibodies in 125 patients with cardiovascular disease and in 128 controls. C. pneumoniae antibodies were measured by microimmunofluorescence assay. A significantly high prevalence of IgG C. pneumoniae antibodies at titre > or = 8 was found in patients (84%) in comparison to controls (47.6%). Considering as cut-off the IgG titre > or = 32, 52% of patients with coronaropathies and 18.75% of controls resulted positive (p < 0.0001). IgA C. pneumoniae antibodies were found in patients and controls without statistically significant differences. High C. pneumoniae antibodies (titre > or = 256) were found in 11% of patients with acute myocardial infarction (AMI) and in none of the controls. In patients, the percentage of IgG and IgA seropositivity increased with age and decreased in patients aged > 70 years. Only patients with AMI are at risk of having antibodies against C. pneumoniae (OR = 6.69). None of the known risk factors for cardiovascular disease was significantly associated with C. pneumoniae seropositivity IgG. This is the first report in our area on the possible association of C. pneumoniae IgG seropositivity and acute ischemic events.     

Role of nitric oxide in tumor growth

This review article will analyze the role of nitric oxide in antiblastomous organism resistance, in particular some mechanisms of NO-mediated apoptosis in different cells and NO involvement in etiological mechanisms as well as tumor growth promotion. The possible mechanisms of nitric oxide dual effect are discussed. The data about NO as a mediator in different methods of cancer treatment are given. In conclusion, we have determined some principles of application of NO-modulating agents in cancer therapy.     

Functional analysis of the cytoskeleton protein MreB from Chlamydophila pneumoniae

In rod-shaped bacteria, the bacterial actin ortholog MreB is considered to organize the incorporation of cell wall precursors into the side-wall, whereas the tubulin homologue FtsZ is known to tether incorporation of cell wall building blocks at the developing septum. For intracellular bacteria, there is no need to compensate osmotic pressure by means of a cell wall, and peptidoglycan has not been reliably detected in Chlamydiaceae. Surprisingly, a nearly complete pathway for the biosynthesis of the cell wall building block lipid II has been found in the genomes of Chlamydiaceae. In a previous study, we discussed the hypothesis that conservation of lipid II biosynthesis in cell wall-lacking bacteria may reflect the intimate molecular linkage of cell wall biosynthesis and cell division and thus an essential role of the precursor in cell division. Here, we investigate why spherical-shaped chlamydiae harbor MreB which is almost exclusively found in elongated bacteria (i.e. rods, vibrios, spirilla) whereas they lack the otherwise essential division protein FtsZ. We demonstrate that chlamydial MreB polymerizes in vitro and that polymerization is not inhibited by the blocking agent A22. As observed for MreB from Bacillus subtilis, chlamydial MreB does not require ATP for polymerization but is capable of ATP hydrolysis in phosphate release assays. Co-pelleting and bacterial two-hybrid experiments indicate that MreB from Chlamydophila (Chlamydia) pneumoniae interacts with MurF, MraY and MurG, three key components in lipid II biosynthesis. In addition, MreB polymerization is improved in the presence of MurF. Our findings suggest that MreB is involved in tethering biosynthesis of lipid II and as such may be necessary for maintaining a functional divisome machinery in Chlamydiaceae.     

Serological study on Chlamydophila pneumoniae in patients with community-acquired pneumonia

This study aimed to evaluate the incidence of Chlamydophila pneumoniae antibodies in patients with community acquired pneumonia (CAP) by a new ELISA test (EIA CP-IgG, IgA, IgM--Eurospital, Trieste, Italy). From January 1999 to July 2001 141 patients with clinical signs of CAP were enrolled in sixteen Italian Hospitals. Specific IgM and IgG antibodies anti-C. pneumoniae in serum and IgA in both serum and sputum were detected. At a primary inspection (time T-0) serum and sputum samples were taken from 115/141 patients, whereas serum was collected from only 100/141 patients after 30 days (time T-30). At T-0 24/115 (20.8%) patients showed serological markers thus suggesting an acute C. pneumoniae infection. In 23/24 patients the overall serological pattern found at T-0 was confirmed at T-30. In 32/115 patients (27.8%) serological markers of C. pneumoniae past infection were found positive and were confirmed 30 days later. These data support the role of C. pneumoniae as an important aetiological agent of CAP throughout different geographic areas of Italy. The test was suitable for the laboratory diagnosis of C. pneumoniae infection. In particular, the presence of specific IgA anti- C. pneumoniae in both serum and sputum proved useful to define different stages and evolution of infection.     

血管内皮生长因子与一氧化氮

血管内皮生长因子（ＶＥＧＦ）是内皮细胞特异性促有丝分裂原,具有促进内皮细胞增生、迁移及增加血管通透性的作用,其强大的促进新血管形成的作用使其在梗塞性血管病的基因治疗中发挥巨大作用。但其作用机制仍不清楚。研究表明ＶＥＧＦ与一氧化氮９ＮＯ）间存在密切关系,ＮＯ是ＶＥＧＦ发挥许多重要生理作用过程中必不可少的因素。探讨ＶＥＧＦ与ＮＯ的关系有助于进一步阐明ＶＥＧＦ的作用机制。     

Detection of Mycoplasma pneumoniae and Chlamydophila pneumoniae in patients with community acquired pneumonia

A total of 292 patients with pneumonia confirmed by clinical, roentgenological and laboratory methods, admitted to the hospital from closed communities during the one year period, were examined. The sputa of patients with pneumonia in the acute stage were studied in the polymerase chain reaction (PCR). The predominence of M. pneumoniae and C. pneumoniae causualties in autumn and winter period was established. The monitoring of atypical infective agents with the use of the PCR techniques gives evidence for conclusion on their ever growing role in the etiological structure of community acquired pneumonia in groups of closely interacting young people.     

Effects of nitric oxide and nitrogen dioxide on bacterial growth

The effects of low concentrations of nitric oxide (NO) and nitrogen dioxide (NO2) on actively dividing cultures of Staphylococcus aureus, Micrococcus luteus, Micrococcus roseus, Serratia marcescens, Bacillus subtilis, Bacillus circulans, Bacillus megaterium, and Bacillus cereus were studied. Fresh cultures of each organism were incubated for 24 h at 25 degrees C on both nutrient agar and mineral salts glucose agar plates under atmospheres containing various low concentrations of NO in air (0 to 1.9 ppm [0 to 2.0 micrograms/g of air]), NO2 in air (0 to 5.5 ppm [0 to 8.8 micrograms/g of air]), or NO and NO2 in air. Bacteria grown under air only were used as controls. After incubation, the colonies that developed on the plates were counted. None of the bacteria tested was affected by NO or NO2 at the indicated concentrations while growing on nutrient agar. Serratia marcescens, B. circulans, B. subtilis, B. megaterium, and B. cereus grown on mineral salts glucose agar were not significantly affected by NO or NO2. Low concentrations (0 to 1.9 ppm) of NO were bacteriostatic to log-phase cultures of M. roseus, M. luteus, and Staphylococcus aureus grown on mineral salts glucose agar. Bacteriostatic activity over a 24-h interval was maximal at an initial NO concentration of 1 ppm. Appreciable amounts of NO2 were produced in 24 h at initial NO concentrations greater than 1 ppm. These results suggest that NO2 may reduce the bacteriostatic activity of NO. Low concentrations (0 to 5.5 ppm) of NO2 in air did not affect any of the bacteria tested. At these low concentrations, NO affected bacterial growth, although NO2, NO2-, and NO3- did not. In addition, it was determined that the bacteriostatic activity observed in this study was not due to an increase in the acidity of the medium.     

Characterization of a hypervariable region in the genome of Chlamydophila pneumoniae

Chlamydophila pneumoniae displays surprisingly little genomic variation, as seen by comparisons of the published genomes from three different isolates and sequencing of four different genes from different isolates. We have in the present study, however, demonstrated genomic variation between 10 C. pneumoniae isolates in the 11690-bp region between the two outer membrane protein genes pmp1 and pmp2. This region of the C. pneumoniae CWL-029 isolate contains seven C. pneumoniae-specific open reading frames (hb1-7, encoding hydrophobic beta-sheet-containing proteins). We identified additionally 12 open reading frames in the C. pneumoniae CWL-029 genome encoding hypothetical proteins with similarity to the seven hypothetical Hb-proteins. Compared to other isolates, genomic variation is seen to cause frame-shifting of three of the 19 hb-open reading frames, which are proposed to be three full-length genes and eight frame-shifted pseudogenes. The hypothetical proteins encoded by these proposed genes contain an N-terminally located highly hydrophobic stretch of 50-60 residues. A similar motif is found in all identified Chlamydia inclusion membrane proteins and therefore the Hb-proteins are candidate inclusion proteins.     

Severe asthma exacerbation: role of acute Chlamydophila pneumoniae and Mycoplasma pneumoniae infection

Background

Chlamydophila pneumoniae and Mycoplasma pneumoniae are associated with acute exacerbation of bronchial asthma (AEBA). The aim of this study was to evaluate the correlation between these acute bacterial infections and the severity of AEBA.

Methods

We prospectively analysed consecutive patients admitted to the Emergency Department with acute asthma exacerbation. In every patient peak expiratory flow (PEF) measurement was performed on admission, and spirometry during follow-up. Serology for Chlamydophila and Mycoplasma pneumoniae was performed on admission and after 4–8 weeks.

Results

Fifty-eight patients completed the study. Acute atypical infections (AAI) was observed in 22/58 cases; we found single acute C. pneumoniae in 19 cases, single acute M. pneumoniae in 2 cases, and double acute infection in one case. Functional impairment on admission was greater in patients with AAI than in patients without AAI (PEF 205 ± 104 L/min vs 276 ± 117 p = 0.02) and persisted until visit 2 (FEV1% 76.30 ± 24.54 vs FEV1% 92.91 ± 13.89, p = 0.002). Moreover, the proportion of patients who presented with severe AEBA was significantly greater in the group with AAI than in the group without AAI (15/22 vs 12/36, p = 0.01; OR 4.29, 95% CI 1.38–13.32).

Conclusion

Our data suggest an association between acute atypical infection and a more severe AEBA.     

Structural analyses of the lipopolysaccharides from Chlamydophila psittaci strain 6BC and Chlamydophila pneumoniae strain Kajaani 6.

Lipopolysaccharides (LPSs) of Chlamydophila psittaci 6BC and Chlamydophila pneumoniae Kajaani 6 contain 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo), GlcN, organic bound phosphate, and fatty acids in the molar ratios of approximately 3:2:2.2:4.8 and approximately 2.9:2:2.1:4.9, respectively. The LPSs were immunoreactive with a monoclonal antibody against a family-specific epitope of chlamydial LPS. This finding, together with methylation analyses of both LPSs and MALDI-TOF MS experiments on de-O-, and de-O,N-acylated LPSs, indicate the presence of a Kdo trisaccharide proximal to lipid A having a structure alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo, which appears to be the main component of the core region in the native chlamydial LPSs. In the de-O-acylated LPSs from Chl. psittaci 6BC and Chl. pneumoniae Kajaani 6, two major molecular species are present that differ in distribution of amide-bound hydroxy fatty acids over both GlcN. It appears that either two (R)-3-hydroxy-18-methylicosanoic acids or one (R)-3-hydroxy-18-methylicosanoic acid and one (R)-3-hydroxyicosanoic acid are attached to the GlcN residues. In contrast, the de-O-acylated LPS of Chl. psittaci PK 5082 contains one major molecular species that has two (R)-3-hydroxyicosanoic acid residues attached to two GlcN residues.     

Effect of airways constriction on exhaled nitric oxide.

While airway constriction has been shown to affect exhaled nitric oxide (NO), the mechanisms and location of constricted airways most likely to affect exhaled NO remain obscure. We studied the effects of histamine-induced airway constriction and ventilation heterogeneity on exhaled NO at 50 ml/s (Fe(NO,50)) and combined this with model simulations of Fe(NO,50) changes due to constriction of airways at various depths of the lung model. In 20 normal subjects, histamine induced a 26 +/- 15(SD)% Fe(NO,50) decrease, a 9 +/- 6% forced expiratory volume in 1 s (FEV(1)) decrease, a 19 +/- 9% mean forced midexpiratory flow between 25% and 75% forced vital capacity (FEF(25-75)) decrease, and a 94 +/- 119% increase in conductive ventilation heterogeneity. There was a significant correlation of Fe(NO,50) decrease with FEF(25-75) decrease (P = 0.006) but not with FEV(1) decrease or with increased ventilation heterogeneity. Simulations confirmed the negligible effect of ventilation heterogeneity on Fe(NO,50) and showed that the histamine-induced Fe(NO,50) decrease was due to constriction, with associated reduction in NO flux, of airways located proximal to generation 15. The model also indicated that the most marked effect of airways constriction on Fe(NO,50) is situated in generations 10-15 and that airway constriction beyond generation 15 markedly increases Fe(NO,50) due to interference with the NO backdiffusion effect. These mechanical factors should be considered when interpreting exhaled NO in lung disease.     

Multiple sclerosis: an infectious syndrome involving Chlamydophila pneumoniae

The concept of autoimmune myelinopathy as the primary pathology in multiple sclerosis (MS) is problematic. Vasculitis is seen in the MS brain, both within lesions and in adjacent normal-appearing white matter. The first observation in acute relapse is the sudden, orderly death of oligodendrocytes; inflammatory removal of unsupported myelin seems to be a secondary process. An alternative explanation for these findings is that oligodendrocyte infection might trigger an inflammatory response. Many pathogens, including Chlamydophila (Chlamydia) pneumoniae, have been associated with MS. MS might be an infectious syndrome in which C. pneumoniae has a role in a subset of patients. Mechanisms by which such a cryptic infection could engender relapsing-remitting and, ultimately, progressive disease patterns are discussed.     

Effect of endogenous nitric oxide on the nerve-muscle synapse function]

The nitric oxide (NO) precursor L-arginine was found to decrease the amplitude and the quantum content of the EPPs and to increase the amplitude of the AP third deflection in the frog neuromuscular junction of the m. cutaneous pectoris preparation. Inhibitor of the NO synthase NG-nitro-L-arginine methylester exerted opposite effects. The data obtained suggest that endogenous NO is produced in the neuromuscular synapse area and can modify the work of potassium ion channels.     

Effects of nitric oxide and nitrogen dioxide on bacterial growth.

The effects of low concentrations of nitric oxide (NO) and nitrogen dioxide (NO2) on actively dividing cultures of Staphylococcus aureus, Micrococcus luteus, Micrococcus roseus, Serratia marcescens, Bacillus subtilis, Bacillus circulans, Bacillus megaterium, and Bacillus cereus were studied. Fresh cultures of each organism were incubated for 24 h at 25 degrees C on both nutrient agar and mineral salts glucose agar plates under atmospheres containing various low concentrations of NO in air (0 to 1.9 ppm [0 to 2.0 micrograms/g of air]), NO2 in air (0 to 5.5 ppm [0 to 8.8 micrograms/g of air]), or NO and NO2 in air. Bacteria grown under air only were used as controls. After incubation, the colonies that developed on the plates were counted. None of the bacteria tested was affected by NO or NO2 at the indicated concentrations while growing on nutrient agar. Serratia marcescens, B. circulans, B. subtilis, B. megaterium, and B. cereus grown on mineral salts glucose agar were not significantly affected by NO or NO2. Low concentrations (0 to 1.9 ppm) of NO were bacteriostatic to log-phase cultures of M. roseus, M. luteus, and Staphylococcus aureus grown on mineral salts glucose agar. Bacteriostatic activity over a 24-h interval was maximal at an initial NO concentration of 1 ppm. Appreciable amounts of NO2 were produced in 24 h at initial NO concentrations greater than 1 ppm. These results suggest that NO2 may reduce the bacteriostatic activity of NO. Low concentrations (0 to 5.5 ppm) of NO2 in air did not affect any of the bacteria tested. At these low concentrations, NO affected bacterial growth, although NO2, NO2-, and NO3- did not. In addition, it was determined that the bacteriostatic activity observed in this study was not due to an increase in the acidity of the medium.