• 主题
高级搜索  >
历史搜索 清空历史

您现在的位置：首页>美国卫生研究院文献>European Journal of Microbiology Immunology

期刊信息

  • 期刊名称：

    -

  • 刊频： Quarterly
  • NLM标题： Eur J Microbiol Immunol (Bp)
  • iso缩写： -
  • ISSN： -

年度选择

更多>>

  • 排序：
  • 显示：
  • 每页：
全选（0）
<8/15>
共290条结果
  • 1.

    【2hr】Prevalence of infection with Toxoplasma gondii inlandrace and mixed breed pigs slaughtered in Baja California Sur State,Mexico

    包量

    机译 弓形虫感染率在南下加利福尼亚州屠宰的地方品种和混种猪，墨西哥
    摘要：We performed a cross-sectional study to determine the seroprevalence of Toxoplasma gondii infection in 308 domestic pigs slaughtered in La Paz, Baja California Sur State, Mexico using the modified agglutination test (MAT, cut off 1:25). Forty (13%) of the 308 pigs were seropositive with MAT titers of 1:25 in 16, 1:50 in 5, 1:100 in 4, 1:200 in 5, 1:400 in 3, 1:800 in 3, 1:1600 in 2, and 1:3200 in 2. Multivariate analysis of pigs’ characteristics showed that seropositivity to T. gondii was negatively associated with mixed breed (OR = 0.02; 95% CI: 0.003–0.26; P = 0.001). Other variables including sex, type of raising, and municipality did not show an association with T. gondii seropositivity by multivariate analysis. The frequency of high antibody titers (≥1:400) was significantly higher (P < 0.001) in Landrace pigs than mixed breed pigs. The seroprevalence of T. gondii infection in pigs for slaughter in Baja California Sur State is low compared with seroprevalences reported in pigs in other Mexican states. Landrace pigs demonstrated higher seroprevalence rates and antibody levels than mixed breed pigs. This is the first report of T. gondii infection in pigsraised in a desert climate.
  • 2.

    【2hr】Identification of nasal colonization with β-lactamase-producingEnterobacteriaceae in patients, health care workers and students inMadagascar

    包量

    机译 产生β-内酰胺酶的鼻部定植的鉴定肠杆菌科患者，医护人员和学生马达加斯加
    摘要：This study assesses the nasal occurrence of β-lactamase-producing Enterobacteriaceae both in patients in a hospital department of infectious diseases at admission and in healthy Madagascan students and health care workers.Nasal swabs from 681 students, 824 health care workers, and 169 patients were obtained in Antananarivo, Madagascar, and transferred to Germany. Screening for β-lactamase (ESBL, ampC) producing Enterobacteriaceae was performed by cultural and molecular approaches, comprising Brilliance ESBL agar, E-testing, ABCD-testing, and commercial hyplex ESBL and SuperBug ID PCR.Regarding ESBL-positive strains and strains with resistance against at least three out of the four tested bactericidal antibiotic drugs, 0.3% (five out of 1541) of the students and health care workers group showed nasal colonization, whereas colonization was observed in 7.1% (12 out of 169) of the hospitalized patients at admission. No appreciably reduced detection rates after sample storage and intercontinental transport were observed. A considerable proportion of nasal colonization with cephalosporin-resistant Enterobacteriaceae was demonstrated in Madagascan hospital patients at admission, posing a risk of developing future endogenous infections. The nasal colonization of healthy individuals was negligible. Good storage and transport stability ofEnterobacteriaceae will allow for future studies even in areas difficult toaccess.
  • 3.

    【2hr】Detection of bacteriuria among human immunodeficiency virusseropositive individuals in Osogbo, south-western Nigeria

    包量

    机译 人类免疫缺陷病毒中细菌尿的检测尼日利亚西南部奥索博的血清反应阳性个体
    摘要：Human immunodeficiency virus-positive individuals are at increased risk of both asymptomatic and symptomatic urinary tract infections. The aim of this study was to determine the prevalence of asymptomatic bacteriuria (ASB) in HIV-positive individuals, its associated factors including any correlation with the CD4 count of the patient, and the antibiotic susceptibility pattern of the isolated organisms. Midstream urine and blood samples were collected from 242 consenting HIV-positive patients who were attending routine follow-up clinic during the six-month period of the study. Microscopy, culture, and antibiotic susceptibility testing of the samples were carried out following standard protocols, and CD4 counts were also determined. Fifty one (21.1%) of the 242 individuals had significant bacteriuria. The predominant organism was Klebsiella spp. (35%) followed by Escherichia coli (31%). Prevalence of bacteriuria was higher in the women. Low CD4 counts and young age were significantly associated with the presence of bacteriuria. ASB prevalence is high in this population and related to the CD4 count level.
  • 4.

    【2hr】Chemokine levels and parasite- and allergen-specific antibodyresponses in children and adults with severe or uncomplicated Plasmodiumfalciparum malaria

    包量

    机译 趋化因子水平以及寄生虫和过敏原特异性抗体严重或不伴疟原虫的儿童和成人的反应恶性疟
    摘要：Chemokine and antibody response profiles were investigated in children and adults with severe or uncomplicated Plasmodium falciparum malaria; the aim was to reveal which profiles are associated with severe disease, as often seen in nonimmune children, or with mild and uncomplicated disease, as seen in semi-immune adults. Blood samples were obtained from children under 5 years of age as well as adults with falciparum malaria. Classification of malaria was performed according to parasite densities and hemoglobin concentrations. Plasma levels of chemokines (IL-8, IP-10, MCP-4, TARC, PARC, MIP-1δ, eotaxins) were quantified, and antibody responses (IgE, IgG1, and IgG4) to P. falciparum, Entamoeba histolytica-specific antigen, and mite allergen extracts were determined. In children with severe malaria proinflammatory, IL-8, IP10, MIP-1δ, and LARC were at highly elevated levels, suggesting an association with severe disease. In contrast, the Th2-type chemokines TARC, PARC, and eotaxin-2 attained in children the same levels as in adults suggesting the evolution of immune regulatory components. In children with severe malaria, an elevated IgG1 and IgE reactivity to mite allergens and intestinal protozoan parasites was observed. In conclusion, exacerbatedproinflammatory chemokines together with IgE responses to mite allergens orE. histolytica-specific antigen extract were observed inchildren with severe falciparum malaria.
  • 5.

    【2hr】Molecular diagnosis of sepsis: New aspects and recentdevelopments

    包量

    机译 败血症的分子诊断：新方面和最新进展事态发展
    摘要：By shortening the time to pathogen identification and allowing for detection of organisms missed by blood culture, new molecular methods may provide clinical benefits for the management of patients with sepsis. While a number of reviews on the diagnosis of sepsis have recently been published we here present up-to-date new developments including multiplex PCR, mass spectrometry and array techniques. We focus on those techniques that are commercially available and for which clinical studies have been performed and published.
  • 6.

    【2hr】Human adenovirus: Viral pathogen with increasingimportance

    包量

    机译 人腺病毒：病毒病原体增多重要性
    • 作者：B. Ghebremedhin
    • 刊名：European Journal of Microbiology Immunology
    • 2014年第1期
    摘要：The aim of this review is to describe the biology of human adenovirus (HAdV), the clinical and epidemiological characteristics of adenoviral epidemic keratoconjunctivitis and to present a practical update on its diagnosis, treatment, and prophylaxis. There are two well-defined adenoviral keratoconjunctivitis clinical syndromes: epidemic keratoconjunctivitis (EKC) and pharyngoconjunctival fever (PCF), which are caused by different HAdV serotypes. The exact incidence of adenoviral conjunctivitis is still poorly known. However, cases are more frequent during warmer months. The virus is endemic in the general population, and frequently causes severe disease in immunocompromised patients, especially the pediatric patients. Contagion is possible through direct contact or fomites, and the virus is extremely resistant to different physical and chemical agents. The clinical signs or symptoms of conjunctival infection are similar to any other conjunctivitis, with a higher incidence of pseudomembranes. In the cornea, adenoviral infection may lead to keratitis nummularis. Diagnosis is mainly clinical, but its etiology can be confirmed using cell cultures, antigen detection, polymerase chain reaction or immunochromatography. Multiple treatments have been tried for this disease, butnone of them seem to be completely effective. Prevention is the most reliableand recommended strategy to control this contagious infection.
  • 7.

    【2hr】Development of anti-bovine IgA single chain variable fragment and itsapplication in diagnosis of foot-and-mouth disease

    包量

    机译 抗牛IgA单链可变片段的开发及其应用在口蹄疫诊断中的应用
    摘要：Recombinant antibody fragments like single chain variable fragments (scFvs) represent an attractive yet powerful alternative to immunoglobulins and hold great potential in the development of clinical diagnostic/therapeutic reagents. Structurally, scFvs are the smallest antibody fragments capable of retaining the antigen-binding capacity of whole antibodies and are composed of an immunoglobulin (Ig) variable light (VL) and variable heavy (VH) chain joined by a flexible polypeptide linker. In the present study, we constructed a scFv against bovine IgA from a hybridoma cell line IL-A71 that secretes a monoclonal antibody against bovine IgA using recombinant DNA technology. The scFv was expressed in Escherichia coli and purified using immobilized metal affinity chromatography (IMAC). The binding activity and specificity of the scFv was established by its non-reactivity toward other classes of immunoglobulins as determined by enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis. Kinetic measurement of the scFv indicated that the recombinant antibody fragment had an affinity in picomolar range toward purified IgA. Furthermore, the scFv was used to develop a sensitive ELISA for the detection of foot and mouth disease virus(FMDV) carrier animals.
  • 8.

    【2hr】Recombinant human antibody fragment against tetanus toxoid producedby phage display

    包量

    机译 产生抗破伤风类毒素的重组人抗体片段通过噬菌体展示
    摘要：Phage display technology is a powerful in vitro method for the identification of specific monoclonal antibodies (antibody fragments) to an antigenic target and allows the rapid generation and selection of high affinity, fully human antibodies directed toward any disease target appropriate for antibody therapy. In the present study, we exploited the phage display technology for the selection of an antigen binding fragment (Fabs) toward tetanus toxoid using human naïve phage antibody library constructed from peripheral blood lymphocytes of naïve human donors. The phages displaying Fab were subjected to three rounds of bio-panning with tetanus toxoid as antigen on a solid phase. The high affinity antibody fragments were expressed in HB2151 strain of Escherichia coli and purified by immobilized metal affinity chromatography. The binding activity and specificity of the antibody fragment was established by its reactivity toward tetanus toxoid and non-reactivity toward other related toxins as determined by enzyme-linked immunosorbent assay and immunoblot analysis. The selected Fab fragment forming the antigen-binding complexes with the toxoid in flocculation assay indicates that the Fab may have a potential neutralizing ability toward antigen.
  • 9.

    【2hr】Generation and characterization of neutralizing monoclonal antibodiesagainst baculo-expressed HPV 16 VLPs

    包量

    机译 中和单克隆抗体的产生和表征对抗杆状病毒表达的HPV 16 VLP
    摘要：Human papillomavirus (HPV) is the well-known second most cause of cervical cancer in women worldwide. According to the WHO survey, 70% of the total cervical cancers are associated with types HPV 16 and 18. Presently used prophylactic vaccine for HPV contains mainly capsid protein of L1 virus like particles (VLPs). Correct folding of VLPs and display of neutralizing epitopes are the major constraint for VLP-based vaccines. Further, monoclonal antibodies (mAbs) play a vital role in developing therapeutics and diagnostics. mAbs are also useful for the demonstration of VLP conformation, virus typing and product process assessment as well. In the present study, we have explored the usefulness of mAbs generated against sf-9 expressed HPV 16 VLPs demonstrated as type-specific and conformational dependent against HPV 16 VLPs by ELISA. High affinity and high pseudovirion neutralization titer of mAbs indicated their potential for the development of prophylactic vaccines for HPV. Also, the type-specific and conformational reactivity of the mAbs to HPV 16 VLPs in sf-9 cells by immunofluorescence assay proved their diagnostic potential.
  • 10.

    【2hr】Spinal cord pathology in chronic experimental Toxoplasmagondii infection

    包量

    机译 慢性实验弓形虫的脊髓病理弓形虫感染
    摘要：Infection with the protozoan Toxoplasma (T.) gondii causes chronic infection of the central nervous system and can lead to life-threatening encephalomyelitis in immunocompromised patients. While infection with T. gondii has long time been considered asymptomatic in immunocompetent hosts, this view is challenged by recent reports describing links between seropositivity and behavioral alterations.However, past and current researches are mainly focused on the brain during Toxoplasma encephalitis, neglecting the spinal cord as a key structure conveying brain signals into motion. Therefore, our study aimed to fill the gap and describes the spinal cord pathology in an experimental murine model of toxoplasmosis.In the spinal cord, we found distinct histopathological changes, inflammatory foci and T. gondii cysts similar to the brain. Furthermore, the recruitment of immune cells from the periphery was detected. Moreover, resident microglia as well as recruited monocytes displayed an increased MHC classes I and II expression. Additionally, the expression of pro- and anti-inflammatory cytokines was enhanced in the brain as well as in the spinal cord. In summary, the pathology observed in the spinal cord was similar to the previously described changes in the brain during the infection.This study provides the first detailed description of histopathological andimmunological alterations due to experimental T. gondii inducedmyelitis in mice. Thus, our comparison raises awareness of the importance of thespinal cord in chronic T. gondii infection.
  • 11.

    【2hr】High seroprevalence of Toxoplasma gondii infectionin inmates: A case control study in Durango City, Mexico

    包量

    机译 弓形虫感染的高血清阳性率囚犯中的情况：墨西哥杜兰戈市的病例对照研究
    摘要：PurposeThe seroprevalence of infection with the parasite Toxoplasma gondii and the association with risk factors has not been determined in inmates. Through a case-control study, 166 inmates from a state correctional facility in Durango City, Mexico and 166 age- and gender-matched non-incarcerated subjects were examined for the presence of anti-T. gondii IgG and IgM antibodies using enzyme-linked immunoassays.
  • 12.

    【2hr】Congenital IL-12R1β receptor deficiency and thrombophilia in a girlhomozygous for an IL12RB1 mutation and compound heterozygousfor MTFHR mutations: A case report and literaturereview

    包量

    机译 一个女孩的先天性IL-12R1β受体缺乏和血栓形成IL12RB1突变纯合子和复合杂合子用于MTFHR突变：病例报告和文献评论
    摘要：Interleukin-12 (IL-12) plays an important role in the production of interferon gamma from T cells and natural killer cells and is essential for protection against intra-macrophagic pathogens such as Mycobacterium and Salmonella. Here, we describe a 16-year-old girl with homozygous mutation in exon 12 of the IL12RB1 gene, which causes complete IL-12Rβ1 deficiency in association with heterozygous mutation (C677T and A1298C) in the methylenetetrahydrofolate reductase gene. She presented with disseminated Mycobacterium tuberculosis complex infection, retroperitoneal fungal abscess and also thrombosis in the superior mesenteric–portal vein junction. This is the first case report of a primary immunodeficiency associated with a genetically determined venous thrombosis.
  • 13.

    【2hr】Erratum

    包量

    机译 勘误表
    摘要：
  • 14.

    【2hr】Differential control of immune cell homeostasis by Foxp3+regulatory T cells in murine peripheral lymph nodes and spleen

    包量

    机译 Foxp3 +对免疫细胞稳态的差异控制鼠外周淋巴结和脾脏中的调节性T细胞
    摘要：Foxp3+ regulatory T cells (Tregs) hamper efficient immune responses to tumors and chronic infections. Therefore, depletion of Foxp3+ Tregs has been proposed as therapeutic option to boost immune responses and to improve vaccinations. Although Treg-mediated control of T cell homeostasis is well established, Foxp3+ Treg interaction with other immune cell subsets is only incompletely understood. Thus, the present study aimed at examining dynamic effects of experimental Foxp3+ Treg depletion on a broad range of immune cell subsets, including B cells, natural killer cells, and myeloid cells. Striking differences were observed when peripheral lymph nodes (LN) and spleen were compared. B cells, for example, showed a massive and long-lasting accumulation only in LN but not in spleen of transiently Treg-depleted mice. In contrast, monocyte-derived dendritic cells, which are potent inducers of T cell responses, also accumulated selectively, but only transiently in LN, suggesting that this cell population is under very strict control of Foxp3+ Tregs. In summary, the observations described here provide insights into the dynamics of immune cells after selective depletion of Foxp3+ Tregs. This will allow a better prediction of the impactof Treg ablation in translational studies that aim at boosting immune responsesand vaccinations.
  • 15.

    【2hr】Accurate detection of Campylobacter spp. antigens byimmunochromatography and enzyme immunoassay in routine microbiologicallaboratory

    包量

    机译 准确检测弯曲杆菌属。抗原常规微生物学中的免疫层析和酶免疫测定实验室
    摘要：Campylobacter spp. are fastidious microorganisms, and their detection by culture depends on the freshness of the stool sample and the skills of the laboratory staff. To improve laboratory diagnosis, assays for the detection of specific antigens have been developed. Here, we evaluated two assays for the detection of Campylobacter spp.-specific antigens, i.e., one immunochromatographic test and one enzyme-linked immunosorbent assay (EIA), in 38 frozen Campylobacter spp.-positive specimens and prospectively in 533 fresh stool samples with a conventional enzyme immunoassay (EIA) and culture.Both assays were positive for 36 samples with Campylobacter jejuni and one with Campylobacter coli among 38 Campylobacter spp.-positive frozen samples. One Campylobacter lari-positive sample was identified by the immunochromatographic assay (ICA) only. In a prospective study performed within the course of routine microbiology, both assays were positive for 24/25 C. jejuni culture-positive samples (positive percent agreement, 96.0% [95% CI: 78.9–100%]). ICA and EIA also were positive for 14 and 10 culture-negative samples, respectively (negative percent agreement: ICA,97.2% [95% CI: 95.4–98.4%]; EIA, 98.0% [95% CI: 96.4–99.0%]). In conclusion, thehigh agreement between both antigen-detection assays and culture indicates thatboth assays may be initially performed followed by culture only upon a positivetest result.
  • 16.

    【2hr】Evaluation of an autoclave resistant anatomic nose model for thetesting of nasal swabs

    包量

    机译 耐高压灭菌解剖鼻子模型的评价。鼻拭子测试
    摘要：A nose model that allows for the comparison of different modes of sample acquisition as well as of nasal swab systems concerning their suitability to detect defined quantities of intranasal microorganisms, and further for training procedures of medical staff, was evaluated.Based on an imprint of a human nose, a model made of a silicone elastomer was formed. Autoclave stability was assessed. Using an inoculation suspension containing Staphylococcus aureus and Staphylococcus epidermidis, the model was compared with standardized glass plate inoculations. Effects of inoculation time, mode of sampling, and sample storage time were assessed.The model was stable to 20 autoclaving cycles. There were no differences regarding the optimum coverage from the nose and from glass plates. Optimum sampling time was 1 h after inoculation. Storage time after sampling was of minor relevance for the recovery. Rotating the swab around its own axis while circling the nasal cavity resulted in best sampling results.The suitability of the assessed nose model for the comparison of sampling strategies and systems was confirmed. Without disadvantages in comparison with sampling from standardized glass plates, the model allows for the assessment of a correct sampling technique due to its anatomically correct shape.
  • 17.

    【2hr】Assessment of the genotype MTBDRplus assay for rifampin and isoniazidresistance detection on sputum samples in Cote d’Ivoire

    包量

    机译 基因型MTBDRplus检测利福平和异烟肼的评估科特迪瓦痰液样本的耐药性检测
    摘要：We conducted an evaluation study on the GenoType MTBDRplus assay’s ability to detect mutations conferring resistance to rifampin and isoniazid directly from sputum taken from 120 smear positive pulmonary patients from tuberculosis (TB) centers in Cote d’Ivoire.The sputum was decontaminated by N-acetyl-l-cysteine (NALC) and comparatively analyzed with the MTBDRplus assay version 2.0 and the mycobacterial growth indicator tube (MGIT) 960 automated drug susceptibility testing (MGIT-DST). The Gene­Xpert Mycobacterium tuberculosis (MTB)/rifampicin (RIF) assay was performed for 21 sputa with absence of hybridization for at least one rpoB wild-type probes. Four and seven, respectively, discordant and concordant results were also analyzed.The mutations in the rpoB gene were 21 (17.5%), 20 (16.7%), 7 (5.8%), and 10 (8.3%), respectively, for D516V, H526Y, H526D, and S531L. S315T mutation in katG gene associated or not with mutation in promoter of inhA was detected in 76 (63.3%) of the sputum. Compared to MGIT-DST, the sensitivity and specificity of the MTBDRplus for rifampin resistance detection were 100% (75–100%) and 73.2% (61.3–84%), respectively. For isoniazid resistance detection, the sensitivity and specificity were, respectively, 95% (90–‌99) and 95.1% (88.5–100%).Interpretation of 16 sputa without hybridization of rpoBwild-type probe 8 compared to those obtained with MGIT-DST and GeneXpert MTB/RIFwas discordant and concordant, respectively, for 11 and 5.
  • 18.

    【2hr】X-linked severe combined immunodeficiency due to a novel mutationcomplicated with hemophagocytic lymphohistiocytosis and presented withinvagination: A case report

    包量

    机译 X连锁的新型突变导致的严重联合免疫缺陷并发吞噬性淋巴细胞组织细胞增生并表现为内陷：病例报告
    摘要：Severe combined immunodeficiency (SCID) is an inherited disease with profoundly defective T cells, B cells, and natural killer (NK) cells. X-linked SCID (X-SCID) is its most common form. In this report, we describe a 4-month-old male with X-SCID who presented invagination and also showed hemophagocytic lymphohistiocytosis (HLH). The patient was admitted to our hospital with fever, cough, vomiting, monoliasis, and hepatosplenomegaly in postoperative period at the age of 3 months. The laboratory finding revealed no detectable T cells and hypogammaglobulinemia despite normal B-cell counts. Diagnosis of X-SCID was established by DNA analysis of the interleukin (IL)-2 receptor gamma chain gene (IL2RG); namely, we detected the novel mutation in the splice-site of exon 5 (c.595-1G>T). The patient died due to infection at the age of 4 months. Also, this case is the first report that describes the patient with X-SCID with presented invagination.
  • 19.

    【2hr】Production of recombinant antibodies usingbacteriophages

    包量

    机译 使用生产重组抗体噬菌体
    摘要：Recombinant antibody fragments such as Fab, scFv, diabodies, triabodies, single domain antibodies and minibodies have recently emerged as potential alternatives to monoclonal antibodies, which can be engineered using phage display technology. These antibodies match the strengths of conventionally produced monoclonal antibodies and offer advantages for the development of immunodiagnostic kits and assays. These fragments not only retain the specificity of the whole monoclonal antibodies but also easy to express and produce in prokaryotic expression system. Further, these antibody fragments are genetically stable, less expensive, easy to modify in response to viral mutations and safer than monoclonal antibodies for use in diagnostic and therapeutic applications. This review describes the potential of antibody fragments generated using phage display and their use as diagnostic reagents.
  • 20.

    【2hr】Difficulties in species identification within the genusHaemophilus – A pilot study addressing a significantproblem for routine diagnostics

    包量

    机译 属内物种鉴定的困难嗜血杆菌–一项针对重要研究的初步研究常规诊断的问题
    摘要：Diagnostic misidentifications of commensalic Haemophilus haemolyticus as pathogenic Haemophilus influenzae are frequent. This pilot study evaluates whether isolations of H. haemolyticus are frequent enough in Germany to cause a relevant diagnostic problem, considering the fact that even H. influenzae is a mere colonizer in about 30% of isolations.In microbiological laboratories of two hospitals located in Northern and Southern Germany, the distribution of Haemophilus spp. was analyzed during a six-month-period. Site of infection, sex, and age of the patients was taken into consideration.A total of 77 Haemophilus spp. isolates was acquired and discriminated on species level, comprising: 48 H. influenzae, 25 Haemophilus parainfluenzae, 3 H. haemolyticus, and 1 Haemophilus parahaemolyticus. The proportion of H. haemolyticus was calculated to range between 1.2% and 16.2 % within the 95% confidence limits. Commensalic Haemophilus spp. were isolated from oropharynx-associated sites only. H. influenzae, in contrast, was detected in clinically relevant materials like lower respiratory materials and conjunctivaswabs.Altogether, there was a low proportion of clinical H.haemolyticus isolates. Accordingly, the problem of unnecessaryantibiotic therapies due to misidentifications of H.haemolyticus as H. influenzae is quantitativelynegligible compared with the risk of confusing H. influenzaecolonizations with infections.
题名 作者 来源 发表时间

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号