Post-arrival screening for malaria in asymptomatic refugees using real-time PCR

Malaria is a significant health risk to refugee populations originating from endemic areas, but there is little consensus on screening and/or treatment approaches for malaria in this population. Furthermore, detection of malaria in semi-immune asymptomatic refugees is limited by the sensitivity of diagnostic tests used for screening. We determined the prevalence of malaria by microscopy and real-time polymerase chain reaction (PCR) in a consecutive population of 324 asymptomatic refugees examined in Edmonton, Canada, during 2009-2010. Although all thick and thin blood smear results were negative, 10 subjects (3.1%) tested PCR positive for Plasmodium DNA. Interestingly, 6 of 10 PCR positive subjects are at risk of malaria relapse by P. vivax or P. ovale infections. These results suggest that appropriate guidelines for malaria screening should consider the risk of relapsing infections, and they highlight the potential usefulness of real-time PCR in the diagnosis of asymptomatic malaria.     

嗜水气单胞菌实时荧光三重TaqMan PCR快速检测体系的建立

目的 建立针对嗜水气单胞菌的高灵敏、高特异的实时荧光三重TaqMan聚合酶链式反应（PCR）快速检测体系。方法 根据嗜水气单胞菌的16S rDNA、气溶素基因（aerA）和丝氨酸蛋白酶基因（ahp）的特异性序列设计引物及TaqMan探针,利用高通量实时荧光PCR检测平台探讨该检测体系的灵敏度;用29种其他肠道致病菌及院内感染中常见的致病菌评价该检测体系的特异性。 结果 实时荧光三重TaqMan PCR快速检测体系对嗜水气单胞菌重组质粒的检测灵敏度为1×102拷贝/反应体系;对嗜水气单胞菌基因组的检测灵敏度为5×10-2 pg/反应体系;该体系的特异性引物探针在检测29种其他肠道致病菌及院内感染中常见的致病菌时未出现假阳性,整个反应在2h内完成。 结论 本研究建立的实时荧光三重TaqMan PCR检测体系可作为嗜水气单胞菌灵敏、特异、快速的检测方法,并同时评价嗜水气单胞菌的致病潜力。     

Neonatal diagnosis of severe combined immunodeficiency leads to significantly improved survival outcome: the case for newborn screening

Severe combined immunodeficiency (SCID) carries a poor prognosis without definitive treatment by hematopoietic stem cell transplantation. The outcome for transplantation varies and is dependent on donor status and the condition of the child at the time of transplantation. Diagnosis at birth may allow for better protection of SCID babies from infection and improve transplantation outcome. In this comparative study conducted at the 2 designated SCID transplantation centers in the United Kingdom, we show that SCID babies diagnosed at birth because of a positive family history have a significantly improved outcome compared with the first presenting family member. The overall improved survival of more than 90% is related to a reduced rate of infection and significantly improved transplantation outcome irrespective of donor choice, conditioning regimen used, and underlying genetic diagnosis. Neonatal screening for SCID would significantly improve the outcome in this otherwise potentially devastating condition.     

Gastrointestinal diseases in primary immunodeficiency disorders

Gastrointestinal symptoms are common and often reveal primary immunodeficiency. Although they mimic gastrointestinal diseases observed in immunocompetent patients, there have diagnostic and therapeutic specificities that should be known for optimal management of these patients. This review describes the gastrointestinal diseases found in primary immunodeficiency and proposes some diagnostic and therapeutic strategies.     

Autoimmunity in human primary immunodeficiency diseases

Human primary immunodeficiency diseases are experiments of nature characterized by an increased susceptibility to infection. In many cases, they are also associated with troublesome and sometimes life-threatening autoimmune complications. In the past few years, great strides have been made in understanding the molecular basis of primary immunodeficiencies, and this had led to more focused and successful treatment. This review has 3 aims: (1) to highlight the variety of autoimmune phenomena associated with human primary immunodeficiency diseases; (2) to explore how primary immunodeficiencies predispose patients to autoimmune phenomena triggered by opportunistic infections; and (3) to consider the rationale for the current treatment strategies for autoimmune phenomena, specifically in relation to primary immunodeficiency diseases. Reviewing recent advances in our understanding of the small subgroup of patients with defined causes for their autoimmunity may lead to the development of more effective treatment strategies for idiopathic human autoimmune diseases.     

Rheumatologic manifestations of primary immunodeficiency diseases

In the last 5 years, several hundred articles have been published concerning the link between primary immunodeficiency disease (PID) and rheumatologic diseases. Although rheumatologic complications were originally thought to be at the opposite ends of the spectrum of immunopathologic manifestations, they are now all being considered secondary manifestations of a causative primary “immune derangement.” For the rheumatologist, it is important to be able to identify patients who may present with typical rheumatologic findings but who have an underlying PID. In a systematic manner, this overview addresses both the systemic and organ-based rheumatologic diseases which have known associations with primary immunodeficiencies, and explores how immunodeficiency may actually cause these clinical manifestations.     

Guidelines for implementation of population-based newborn screening for severe combined immunodeficiency

Severe combined immunodeficiency (SCID) is a Primary Immune Deficiency that is under consideration for population-based newborn screening (NBS) by many NBS programs, and has recently been recommended for inclusion in the US uniform panel of newborn screening conditions. A marker of SCID, the T cell receptor excision circle (TREC), is detectable in the newborn dried blood spot using a unique molecular assay as a primary screen. The New England Newborn Screening Program developed and validated a multiplex TREC assay in which both the TREC analyte and an internal control are acquired from a single punch and run in the same reaction. Massachusetts then implemented a statewide pilot SCID NBS program. The authors describe the rationale for a pilot SCID NBS program, a comprehensive strategy for successful implementation, the screening test algorithm, the screening follow-up algorithm and preliminary experience based on statewide screening in the first year. The Massachusetts experience demonstrates that SCID NBS is a program that can be implemented on a population basis with reasonable rates of false positives.     

实时均相PCR技术在肝病科研中的应用

一、技术背景近年发展起来的一种能集扩增与检测于一体的核酸扩增技术,即实时均相PCR技术(real-time homogeneous PCR)。可在单一闭管体系中对靶核酸进行扩增、检测和定量。不仅有传统PCR的优点,且不易受到交叉污染,已在微生物学、分子遗传学、肿瘤学和血液学等领域得到广泛的应用。现就其中的相关技术以及在肝脏病学中的应用作一介绍。     

Flow cytometry-based diagnosis of primary immunodeficiency diseases

Primary immunodeficiencies (PIDs) are a heterogeneous group of inherited diseases of the immune system. The definite diagnosis of PID is ascertained by genetic analysis; however, this takes time and is costly. Flow cytometry provides a rapid and highly sensitive tool for diagnosis of PIDs.Flow cytometry can evaluate specific cell populations and subpopulations, cell surface, intracellular and intranuclear proteins, biologic effects associated with specific immune defects, and certain functional immune characteristics, each being useful for the diagnosis and evaluation of PIDs. Flow cytometry effectively identifies major forms of PIDs, including severe combined immunodeficiency, X-linked agammaglobulinemia, hyper IgM syndromes, Wiskott-Aldrich syndrome, X-linked lymphoproliferative syndrome, familial hemophagocytic lymphohistiocytosis, autoimmune lymphoproliferative syndrome, IPEX syndrome, CTLA 4 haploinsufficiency and LRBA deficiency, IRAK4 and MyD88 deficiencies, Mendelian susceptibility to mycobacterial disease, chronic mucocuneous candidiasis, and chronic granulomatous disease. While genetic analysis is the definitive approach to establish specific diagnoses of PIDs, flow cytometry provides a tool to effectively evaluate patients with PIDs at relatively low cost.     

Thymic activity in severe combined immunodeficiency diseases.

Thymic function was evaluated by quantitation of circulating thymic factor in patients with several forms of severe infantile immunodeficiency diseases. Direct quantitation of thymic factor in serum of patients with severe combined immunodeficiency revealed heterogeneity of this syndrome by this parameter, as was also shown by study of susceptibility of the marrow cells to differentiation in vitro. Thymic factor was not detectable in one patient with severe combined immunodeficiency, but was present in normal or near-normal concentrations in three others. Circulating levels of this hormonal activity were also not detectable in a patient with DiGeorge athymic syndrome. Following marrow or fetal liver transplantation, which corrected the severe combined immunodeficiency thymic factor levels either increased slightly or did not change appreciably. Fetal thymic transplantation, which together with fetal liver transplantation corrected the immunodeficiency in one patient with severe combined immunodeficiency, was associated with increase of thymic factor to normal levels. Fetal thymus transplantation alone, which was employed to correct the immunodeficiency of DiGeorge athymic syndrome, caused an increase in thymic factor activity to normal or near normal levels in this patient.     

HLA non-identical T-cell-depleted bone marrow transplantation for primary immunodeficiency diseases

Background: Bone marrow transplantation (BMT) is usually the only procedure offering cure for children with life-threatening immune deficiency disorders, but compatible sibling donors are frequently unavailable. Aims and Methods: To examine the outcome of HLA non-identical T-cell-depleted BMT carried out between April 1985 and May 1992 in 11 patients with primary immunodeficiency diseases and to seek prognostic factors. Results: Eight patients achieved sustained engraftment, one after a second BMT. One further patient engrafted transiently, but rejected the graft five months later. Acute graft-versus-host disease (GVHD) grade II was seen in one and chronic GVHD was seen in three children. Seven patients survived beyond six months, six with donor T cell and five with donor B cell engraftment. At present, five patients (46%) are alive with immune reconstitution at a median follow-up of 14 months (range 6 to 78 months). The major factor associated with outcome was the presence of any infection within one week of BMT (p= 0.01). The presence of lung infection also tended to be a poor prognostic factor (p> = 0.06) but did not reach significance, presumably because of the small sample size. HLA non-identical (parental) T-cell depleted BMT plays an important role in the cure of children with immunodeficiencies who do not have an identical sibling donor. Survival can be further improved if the diagnosis of immunodeficiency disease is made early and BMT undertaken before significant infections occur. Conclusions: The availability of T-cell depleted haploidentical parental bone marrow transplant can be anticipated to improve outcome significantly for children with severe immunodeficiency, especially when diagnosed early.     

Neonatal screening for haemoglobin variants using filter paper-dried blood specimens

Summary Neonatal screening for haemoglobinopathies utilizing cord blood samples is well established, although it has a high miss rate and has the inherent problem of possible misdiagnosis from maternal contamination of the sample. The use of dried Guthrie card samples which are taken at six days of age avoids these problems and has the advantage of using an established system of sample collection. Controversy exists as to the method of choice for analysis of dried samples, this study of 2406 samples found that Iso-electric focusing (IEF) analysis of dried specimens gives excellent correlation when compared with cellulose acetate/citrate agar electrophoresis of liquid cord blood samples. The IEF results were clear and relatively simple to interpret even when the samples had been stored at room temperature for 4 weeks. The commercial enzyme linked immunosorbent assay (ELISA) screening test JOSHUA reliably determines the presence or absence of haemoglobin S in dried specimens. It could therefore be used as a relatively cheap and simple method for the confirmation of sickle cell trait in neonatal screening programmes based on dried specimens.     

Cutaneous manifestations of primary immunodeficiency diseases in children

Primary immunodeficiency diseases (PIDs) are rare but include severe conditions found predominantly in children, Most PIDs have cutaneous manifestations that may be important as early diagnostic features. The purpose of this study was to determine the frequency and nature of cutaneous alterations associated with PIDs. This article is a cross-sectional study at the department of allergy and clinical immunology of children's medical center conducted between December 5, 2001 and April 20, 2002. The subjects included pediatric patients with a diagnosis of PID and dermatological diagnoses were made by a dermatologist. Two hundred and ten patients were studied They consisted of 68 cases of humoral deficiency, 22 cases of cellular and combined deficiencies, 57 cases of phagocytic defects and 63 cases of other PIDs. In 67 cases (31.8%) the cutaneous alterations preceded and were the basis for clinical immunological diagnosis. Overall cutaneous alterations were infections in 99 cases and eczematous dermatitis in 27 cases. Our findings support the results of other studies that most PIDs have cutaneous features which being their typical aspects are highly suggestive for the diagnosis of PIDs.     

Determination of RHD zygosity using real-time quantitative PCR

At present RHD incompatibility is still an obstetric problem despite prophylactic treatment. A very welcome recent technical advance has now made it possible to determine the foetal RHD status in a non-invasive risk-free manner using cell free foetal DNA in maternal plasma. In some cases, however, where there is a high risk that the foetus may be affected by HDN (haemolytic disease of the newborn), it may be of interest to determine whether the father is hetero- or homozygous for the RHD gene, since in the former instance there is only a 50% chance that the pregnancy is affected. It has recently been shown that quantitative PCR assays, in particular real-time Taqman PCR, can be used to determine the RHD gene dosage, and also to determine foetal aneuploidies. We demonstrate that the same real-time Taqman PCR assay we had previously developed for non-invasive analysis of the foetal RHD gene and the foetal Y chromosome from maternal plasma can be used to determine the paternal RHD genotype.     

实时荧光定量PCR技术检测肺炎衣原体的诊断价值

目的探讨实时荧光定量PCR技术检测肺炎衣原体的诊断价值。方法对呼吸道感染的186例患者的痰液分别采用实时荧光定量PCR技术和基因测序检测,以评价实时荧光定量PCR技术检测肺炎衣原体感染的准确性。结果实时荧光定量PCR检测肺炎衣原体的灵敏度为100.0%,特异度为93.1%,阳性预期值为80.8%,阴性预期值为100.0%,准确率为94.6%。结论实时荧光定量PCR技术检测肺炎衣原体具有较高的可靠性,适用于临床快速诊断肺炎衣原体感染的相关疾病。     

Neonatal screening for haemoglobin variants using filter paper-dried blood specimens.

Neonatal screening for haemoglobinopathies utilizing cord blood samples is well established, although it has a high miss rate and has the inherent problem of possible misdiagnosis from maternal contamination of the sample. The use of dried Guthrie card samples which are taken at six days of age avoids these problems and has the advantage of using an established system of sample collection. Controversy exists as to the method of choice for analysis of dried samples, this study of 2406 samples found that Iso-electric focusing (IEF) analysis of dried specimens gives excellent correlation when compared with cellulose acetate/citrate agar electrophoresis of liquid cord blood samples. The IEF results were clear and relatively simple to interpret even when the samples had been stored at room temperature for 4 weeks. The commercial enzyme linked immunosorbent assay (ELISA) screening test JOSHUA reliably determines the presence or absence of haemoglobin S in dried specimens. It could therefore be used as a relatively cheap and simple method for the confirmation of sickle cell trait in neonatal screening programmes based on dried specimens.