Norovirus diagnostics: options, applications and interpretations

Noroviruses are a frequent cause of both acute gastroenteritis and outbreaks of gastroenteritis. Infection is usually self-limiting although it has been associated with mortality in children in the developing world and in vulnerable groups such as immunodeficient or immunosuppressed and elderly patients elsewhere. Diagnostic tests may be useful in preventing or limiting the spread and duration of outbreaks, and are needed to define norovirus-associated morbidity and mortality. However, the interpretation of test results should take account of the limitations of the different tests currently available. Therefore, the clinical, immunological and molecular tests available for norovirus detection have been reviewed. Early recognition of cases (clinical diagnoses) together with confirmation by sensitive and specific laboratory tests may contribute to reducing the spread of norovirus within hospitals. Syndromic testing that includes multiple or multiplex assays for the detection of viral, bacterial and parasitic pathogens with the inclusion of control groups are likely to better define norovirus-associated morbidity and mortality in low- and middle-income countries.     

Radioimmunoassay and heat denaturation enzyme assay for the detection of Tay-sachs heterozygotes during pregnancy

Tay-Sachs disease results from a loss of activity of hexosaminidase A (HEXA) in body tissues and fluids. Heterozygotes for the disease are usually identified by their relatively low ratio of heat-labile HEX A to total hexosaminidase. During pregnancy an intermediate isoenzyme (HEX I) increases in activity in serum and obscures the heterozygote status. HEX I dose not increase in leucocytes, tears and other body tissues but because of technical difficulties in these assays we examined the feasibility of using a radioimmunoassay for HEX A. By univariate analysis, the heat denaturation assay gave a lower cost of misclassification for non-pregnant normals while RIA did so for pregnant normals. A combination of both tests led to reduced cost of misclassification compared to either alone. Bayesian analysis of bivariate gaussian density functions for heat denaturation and for radioimmunoassay of HEX isoenzymes was employed to calculate misclassification frequencies. Among the parameters examined, HEX A measured by RIA and % HEX A by heat-denaturation assay were the two having the best discriminatory power.     

Erythrocyte glutathione synthetase in 5-oxoprolinuria: kinetic studies of the mutant enzyme and detection of heterozygotes.

The primary metabolic defect in 5-oxoprolinuria is a generalized deficiency of glutathione synthetase. The activity of this enzyme was determined in cell-free extracts of erythrocytes from patients with 5-oxoprolinuria, their parents and a sibling as well as from normal control individuals. The following activities (pkat/mg of hemoglobin) for glutathione synthetase were obtained: homozygotes mean 0.10 (range 0.07-0.12), heterozygotes mean 3.1 (range 2.8-3.7) and control individuals mean 6.1 (range 5.4-6.7). These results indicate that 5-oxoprolinuria, i.e. the defective gluthione synthetase gene(s), is transmitted by autosomal recessive inheritance. Studies of the kinetics of the low remaining activity of erythrocyte glutathione synthetase in patients with 5-oxoprolinuria failed to reveal defective affinity for glycine, gamma-glutamyl-alpha-aminobutyrate, ATP and Mg2+ ions. Furthermore, the pH optimum, time curves and temperature dependence for the mutant enzyme activity did not significantly differ from the corresponding parameters observed with normal enzyme.     

Drug synergism: its detection and applications

Two drugs that produce overtly similar effects will sometimes produce exaggerated or diminished effects when used concurrently. A quantitative assessment is necessary to distinguish these cases from simply additive action. This distinction is based on the classic pharmacologic definition of additivity that, briefly stated, means that each constituent contributes to the effect in accord with its own potency. Accordingly, the relative potency of the agents, not necessarily constant at all effect levels, allows a calculation using dose pairs to determine the equivalent of either agent and the effect by using the equivalent in the dose-response relation of the reference compound. The calculation is aided by a popular graph (isobologram) that provides a visual assessment of the interaction but also requires independent statistical analysis. The latter can be accomplished from calculations that use the total dose in a fixed-ratio combination along with the calculated additive total dose for the same effect. Different methods may be used, and each is applicable to experiments in which a single drug is given at two different sites. When departures from additivity are found, whether in "two-drug" or "two-site" experiments, the information is useful in designing new experiments for illuminating mechanisms. Several examples, mainly from analgesic drug studies, illustrate this application. Even when a single drug (or site) is used, its introduction places it in potential contact with a myriad of chemicals already in the system, a fact that underscores the importance of this topic in other areas of biological investigation.     

A new sensitive method for assay of histidase in human skin and detection of heterozygotes for histidinemia.

A new sensitive method was developed for assay of histidase in the stratum corneum of human skin with [14C] histidine as substrate. With this method histidase could be detected using less than 1 mg of stratum corneum. Skin histidase was markedly reduced in seven infants with histidinemia. The enzyme activities in thirteen parents of the patients were about 50% of the normal values, and even the highest values in the parents did not overlap the lowest normal values. Thus heterozygotes in the autosomal recessive form of histidinemia can be distinguished from normal persons by their skin histidase activity measured by this sensitive assay method.     

Glucose-6 phosphate dehydrogenase deficiency: an easy and sensitive quantitative assay for the detection of female heterozygotes in red blood cells

Different methods for the quantitative determination of glucose-6-phosphate dehydrogenase (G-6-PD) were compared and one of them found to be highly precise. Maleimide inactivation of 6-phosphogluconate dehydrogenase (PGD) was investigated. It was shown that this inactivation is time-dependent and causes loss of assay precision. The most precise method was adapted to lysates of red blood cells from females, known to be heterozygote for G-6-PD deficiency and from non-deficient males and females. Heterozygote gene carriers were detected at a rate of 97.0%.     

PCR methodology and applications for the detection of human fungal pathogens

Introduction: Polymerase chain reaction (PCR) has emerged as a promising technology for the rapid and reliable detection and identification of medical mycoses. Recent technological advancements – including microarray, multiplex PCR with magnetic resonance, and beacon probes – have mitigated the technical difficulties of performing nucleic amplification in fungi, thereby improving the sensitivity and specificity of PCR-based assays. In this paper, we examine current applications of PCR in the diagnosis of human fungal infections and look ahead to emerging techniques that may play a larger role in molecular diagnostics in the future.

Areas covered: This review includes a brief overview of the advantages and disadvantages of PCR using various clinical specimens, manual versus automated DNA extraction procedures, panfungal versus specific targets, and spectrum of pathogens detected. This is followed by a brief synopsis of species-specific PCR approaches and a more in-depth look at the obstacles to widespread implementation.

Expert commentary: The review concludes with a short perspective for the next five years, including the hurdles to standardization and validation, as well as the role of PCR coupled with electrospray-ionization mass spectrometry (PCR/ESI-MS) or nuclear magnetic resonance for the diagnosis of medical mycoses.     

胸腺移植的方法和应用

目的:回顾胸腺移植的方法和应用,展望胸腺移植的发展。资料来源:应用计算机检索Pubmed数据库1968-01/2005-10相关胸腺移植方面的文章,检索词为“thymus,transplantation”,限定文章语言种类为English;计算机检索CNKI1990-01/2005-10相关胸腺移植方面的文章,限定文章语言种类为中文。资料选择:对资料的摘要进行阅读初审,纳入标准:①有关胸腺移植的各种方法的原理及实施方案。②胸腺移植的临床应用和动物实验。排除标准:综述文献、重复研究、Meta分析类文章。资料提炼:共纳入符合标准的文章20篇,多为胸腺移植的临床应用和动物实验方面的文章。资料综合:自1968年胸腺移植被用于治疗DiGeorge综合征以来,它已经被很多学者应用于临床和基础医学研究中。胸腺移植的方法很多,主要包括胸腺细胞移植、胸腺组织块移植、带血管的胸腺移植和胸腺与其他脏器联合移植等。胸腺移植最初被用来治疗免疫性疾病,随后其对各种恶性肿瘤的治疗作用也得到证实。近年来,胸腺移植对器官移植耐受的诱导作用引起人们的重视,有关这方面的研究已取得很多进展。结论:随着基因工程技术和免疫学研究的不断前进,胸腺移植将会更好地服务于基础和临床研究。     

胸腺移植的方法和应用

目的：回顾胸腺移植的方法和应用，展望胸腺移植的发展。 资料来源：应用计算机检索Pubmed数据库1968—01／2005—10相关胸腺移植方面的文章，检索词为“thymus，transplantation”，限定文章语言种类为English；计算机检索CNKI 1990-01／2005—10相关胸腺移植方面的文章，限定文章语言种类为中文。 资料选择：对资料的摘要进行阅读初审，纳入标准：①有关胸腺移植的各种方法的原理及实施方案。②胸腺移植的临床应用和动物实验。排除标准：综述文献、重复研究、Meta分析类文章。 资料提炼：共纳入符合标准的文章20篇，多为胸腺移植的临床应用和动物实验方面的文章。 资料综合：自1968年胸腺移植被用于治疗DiGeorge综合征以来，它已经被很多学者应用于临床和基础医学研究中。胸腺移植的方法很多，主要包括胸腺细胞移植、胸腺组织块移植、带血管的胸腺移植和胸腺与其他脏器联合移植等。胸腺移植最初被用来治疗免疫性疾病，随后其对各种恶性肿瘤的治疗作用也得到证实。近年来，胸腺移植对器官移植耐受的诱导作用引起人们的重视，有关这方面的研究已取得很多进展。 结论：随着基因工程技术和免疫学研究的不断前进：胸腺移植将会更好地服务于基础和临床研究。     

Subclinical disease detection: advanced imaging applications

Coronary events are the leading cause of death in the United States, and sudden coronary death is often the first presenting symptom. Because there is such a large population at risk for coronary events and because many of these patients go undetected before presenting with a significant cardiovascular event or sudden death, there is great interest in better detection and characterization of subclinical disease before it causes morbidity and mortality. This chapter will focus on promising imaging-based methods for the evaluation of subclinical cardiovascular disease. Several imaging methods that are most likely to be useful for future screening and intervention studies for characterizing risk among asymptomatic persons will be presented.     

Urinary lipid profiling for the identification of fabry hemizygotes and heterozygotes

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder resulting from a deficiency of the lysosomal hydrolase, alpha-galactosidase, for which enzyme replacement therapy is now available. In this study, we aimed to identify Fabry heterozygotes not only for genetic counseling of families but because it is becoming increasingly obvious that many heterozygous (carrier) females are symptomatic and should be considered for treatment. METHODS: We measured 29 individual lipid species, including ceramide, glucosylceramide, lactosylceramide, and ceramide trihexoside, in urine samples from Fabry hemizygotes and heterozygotes and from control individuals by electrospray ionization tandem mass spectrometry. Individual analyte species and analyte ratios were analyzed for their ability to differentiate the control and patient groups. RESULTS: The Fabry hemizygotes had increased concentrations of the substrate for the deficient enzyme, ceramide trihexoside, as well as lactosylceramide and ceramide, along with decreased concentrations of both glucosylceramide and sphingomyelin. Ratios of these analytes improved differentiation between the control and Fabry groups, with the Fabry heterozygotes generally falling between the Fabry hemizygotes and the control group. CONCLUSIONS: These lipid profiles hold particular promise for the identification of Fabry individuals, may aid in the prediction of phenotype, and are potentially useful for the monitoring of therapy in patients receiving enzyme replacement.     

六种分枝杆菌培养方法的对照

目的观察痰液离心沉淀法接种于酸罗氏培养基培养分支杆菌的阳性率与其他5种方法的对比. 方法对146例结核病人的痰标本分别作涂片、Bactec 法检测和 2% NaOH 碱处理后,吸取标本管内上清液体、中部液体、自沉淀液体和离心沉淀法后的标本接种于酸罗氏培养基.结果离心沉淀法阳性率最高为39.7%,Bactec 法阳性率为35.6%,中部液体阳性率为30.8%,自沉淀液体和涂片阳性率为30.1%,上清液体阳性率为28.8%.结论离心沉淀法接种于酸罗氏培养基阳性率优于其他五种方法.