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Invasive pneumococcal disease in the Australian Capital Territory and Queanbeyan region: do high infant rates reflect more disease or better detection?

OBJECTIVE: To describe the epidemiology of invasive pneumococcal disease in the Australian Capital Territory (ACT) and Queanbeyan region prior to the introduction of conjugate pneumococcal vaccines. METHODOLOGY: Residents with sterile site isolates of Streptococcus pneumoniae from 1998 to 2000 were identified from a prospective bacteraemia surveillance project involving all ACT public hospitals, supplemented by retrospective laboratory-based detection of other sterile site isolates. RESULTS: Incidence of invasive pneumococcal disease was 15.2 cases per 105 per year, and 193.4 per 105 per year in infants under 2 years. Primary bacteraemia was significantly more common in infants and young children than in older subjects. Reduced penicillin susceptibility was observed in 9.6% of isolates, and no high-level penicillin resistance was observed. CONCLUSIONS: Infants in the ACT and Queanbeyan have a higher invasive pneumococcal disease incidence than similar populations worldwide. Better detection is the most likely explanation. This population would be ideal for studies of the 'real life' effectiveness of infant conjugate vaccination.

Adult↗

A context-sensitive approach to anonymizing spatial surveillance data: impact on outbreak detection.

OBJECTIVE: The use of spatially based methods and algorithms in epidemiology and surveillance presents privacy challenges for researchers and public health agencies. We describe a novel method for anonymizing individuals in public health data sets by transposing their spatial locations through a process informed by the underlying population density. Further, we measure the impact of the skew on detection of spatial clustering as measured by a spatial scanning statistic. DESIGN: Cases were emergency department (ED) visits for respiratory illness. Baseline ED visit data were injected with artificially created clusters ranging in magnitude, shape, and location. The geocoded locations were then transformed using a de-identification algorithm that accounts for the local underlying population density. MEASUREMENTS: A total of 12,600 separate weeks of case data with artificially created clusters were combined with control data and the impact on detection of spatial clustering identified by a spatial scan statistic was measured. RESULTS: The anonymization algorithm produced an expected skew of cases that resulted in high values of data set k-anonymity. De-identification that moves points an average distance of 0.25 km lowers the spatial cluster detection sensitivity by less than 4% and lowers the detection specificity less than 1%. CONCLUSION: A population-density-based Gaussian spatial blurring markedly decreases the ability to identify individuals in a data set while only slightly decreasing the performance of a standardly used outbreak detection tool. These findings suggest new approaches to anonymizing data for spatial epidemiology and surveillance.

Algorithms↗

Abdominal aortic aneurysm: the role of clinical examination and opportunistic detection.

OBJECTIVES: to investigate the method of discovery of abdominal aortic aneurysms (AAA) in a district general hospital setting. DESIGN: retrospective study. MATERIALS AND METHODS: we analysed 198 patients with an AAA who presented to our unit over a 3-year period. The method of initial diagnosis, size of the AAA and whether this was palpable, irrespective of the method of detection, were recorded. RESULTS: ninety-five (48%) were discovered clinically, 74 (37.4%) during a radiological investigation, and 29 (14.6%) at laparotomy. Of the 74 AAAs first detected radiologically, subsequent physical examination showed that 28 (37.8%) were in fact palpable and missed at presentation. The average size of those discovered clinically (6. 48+/-1.32 cm) was larger than those found radiologically (5.37+/-1. 44 cm, p<0.001) or at operation (5.43+/-1.48 cm, p=0.039). The average diameter of the palpable AAAs was also greater than that of the non-palpable AAAs (6.42+/-1.24 cm vs. 4.86+/-1.38 cm, p<0.001). CONCLUSIONS: opportunistic detection of a clinically unsuspected aneurysm during clinical examination or investigation for another reason is the most common way the diagnosis of an AAA is made. Almost half of the aneurysms were diagnosed clinically, but physical examination also missed more than a third of those detected radiologically. Despite technological advancement, clinical examination still plays a paramount role in the detection of AAAs. Larger AAAs are usually palpable and more likely to be detected on clinical examination.

Aged↗

Preclinical models for human pre-embryo biopsy and genetic diagnosis. II. Polymerase chain reaction amplification of deoxyribonucleic acid from single lymphoblasts and blastomeres with mutation detection.

OBJECTIVE: To demonstrate the use of the polymerase chain reaction in the amplification of deoxyribonucleic acid (DNA) from single human lymphoblasts and mouse blastomeres. Amplified target genes for diagnosis of sickle cell anemia and Tay-Sachs are shown. Similarly, the sparce fur mouse model for ornithine transcarbamylase deficiency was used as an X-linked system for demonstration of mutation detection after biopsy of a single blastomere. A new diagnostic method for the detection of the ornithine transcarbamylase mutation using the restriction enzyme Mse I is presented. Accuracy and reproducibility were assured. DESIGN: Polymerase chain reaction proficiency test for amplification from single cells was studied. Also, accuracy of mutation detection systems was demonstrated. SETTING: Laboratories of The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School. PATIENTS, PARTICIPANTS: We used the sparse fur mouse model and human blood cells. INTERVENTIONS: Pre-embryo biopsy, polymerase chain reaction amplification, and mutation detection were performed. MAIN OUTCOME MEASURES: Accuracy and reproducibility of DNA amplification without contamination, as well as efficient diagnostic analysis, from both single somatic and embryonic cells were shown. RESULTS: DNA amplification from single cells was uniformly rapid (6 to 10 hours) reproducible (n = 220) and accurate (n = 52). CONCLUSIONS: Our findings support the feasibility of clinical application for pre-embryo biopsy and genetic diagnosis of specific heritable diseases.

Amino Acid Sequence↗

Biochemical analysis of cultured chorionic villi for the prenatal diagnosis of peroxisomal disorders: biochemical thresholds and molecular sensitivity for maternal cell contamination detection.

OBJECTIVES: The prenatal diagnosis of peroxisomal disorders is most often performed by biochemical analysis of cultured chorionic villus sample (CVS) or amniocytes. We aimed to (a) highlight the risk of maternal cell contamination (MCC) in biochemical prenatal diagnosis, (b) establish the threshold of these biochemical assays to MCC, and (c) document the sensitivity of PCR based genotyping of microsatellites for the detection of MCC in prenatal diagnosis of inborn errors by biochemical analysis. METHODS: The threshold of each biochemical assay was assessed by co-cultivating fibroblasts from known affected and normal individuals. Genotypes for three polymorphic loci were determined by PCR and GeneScan analysis. The sensitivity of the molecular test was determined by DNA mixing experiments and isolation of DNA from co-cultivated fibroblasts. RESULTS: MCC was detected in 2.5% of at risk CVS cultures (n = 79). Co-cultivation of defective and normal fibroblasts demonstrated that the peroxisomal biochemical assays were accurate at 25% contamination. Very low level DNA or cell contamination (1-5%) was detectable by genotyping, but an allele did not yield a definitive peak based on morphology until approximately 10% contamination. Furthermore, we demonstrated that other inborn errors of metabolism might be more susceptible to diagnostic error by low level MCC. CONCLUSION: The sensitivity of the microsatellite analysis (> or =10%) is well within the threshold of peroxisomal biochemical assays. Although peroxisomal biochemical assays would not be predicted to introduce a false positive or negative result if MCC <10% were present but not recognised by molecular analysis, the same may not be true for other inborn errors of metabolism.

Cell Culture Techniques↗

Objective response detection technique in frequency-domain for reflecting changes in MLAEP.

The mid-latency auditory evoked potential (MLAEP) occurs within the interval 10-100ms post-stimulus and exhibits morphological changes due to coma, general anaesthesia and neurological and psychiatric diseases. This work evaluates an objective response detection technique in the frequency domain, the magnitude squared coherence (kappa(2)(f)), in reflecting MLAEPs changes in amplitude and latencies. Both simulation and EEG data were used in this investigation. The EEG during auditory stimulation in 10 volunteers under propofol-induced anaesthesia was acquired. Based on the null hypothesis of non-existing response, critical values have been derived in order to detect the auditory response. The alternative hypothesis was used to infer about maximal-response frequencies as well as to derive confidence intervals for the estimated values of kappa(2)(f) during anaesthesia. Changes in both simulated and real MLAEPs could be tracked by kappa(2)(f), even for low SNR. High degree of cortical activation occurred predominantly between 30 and 90Hz. This finding could be related to the sensory-originated phase-locked oscillation in the gamma band (30-70Hz). Hence, for applications where changes on MLAEPs should be assessed, the use of kappa(2)(f) as an objective statistical response detection technique is worth to be applied.

Algorithms↗

Nephrotoxicity of organic solvents: biomarkers for early detection.

OBJECTIVES: Evidence for a relationship between chronic kidney diseases or progression of already existing diseases (glomerulonephritides) and occupational solvent exposure has been found in case reports, in case-control studies and also in cross-sectional studies. An analysis of the available literature was performed with respect to markers measured in cross-sectional studies that might be useful for an early detection of solvent-induced effects on the kidney. METHODS: The relevant cross-sectional studies were evaluated and the following markers were analyzed with respect to their suitability as biomarker for renal damage: total protein, albumin, transferrin, IgG, beta(2)-microglobulin, retinol-binding protein, N-acetyl-beta-D: -glucosaminidase, alanine aminopeptidase, beta-galactosidase, beta-glucuronidase, leucin aminopeptidase, alkaline phosphatase, lysozyme, Tamm-Horsfall protein and laminin fragments in urine as well as E-selectin, laminin and anti-laminin antibodies and anti-glomerular basement membrane antibodies in serum. RESULTS: An increased albumin excretion was observed more frequently in groups of workers exposed to various solvents (like toluene, styrene, aliphatic/aromatic hydrocarbon mixtures, tetrachloroethene, mixtures of chlorinated hydrocarbons) than in controls. No clear pattern emerged for the other markers. CONCLUSIONS: The determination of albumin excretion in the urine appears to be a useful parameter for monitoring solvent-exposed workers.

Biomarkers↗

Detection and quantification of 5-hydroxyoxindole in mammalian sera and tissues by high performance liquid chromatography with multi-electrode electrochemical detection.

OBJECTIVE: Since 5-hydroxyoxindole structurally related indole metabolites play different roles in some hepatic and neurologic disorders we found necessary to develop an assay to further investigate the physiologic relevance of this compound. METHODS: We have designed a convenient assay to determine 5-hydroxyoxindole in serum using solid phase extraction and a highly selective High Performance Liquid Chromatography system with multi-Electro Chemical Detection (HPLC-ECD). RESULTS: We have identified and quantified 5-hydroxyoxindole in various mammalian species. Its distribution in tissues showed that the molecule is also present in brain, liver, kidney and spleen, but not in skeletal muscle. CONCLUSIONS: 5-hydroxyoxindole is an endogenous tryptophan metabolite present in circulating blood and in some tissues at the nmol level, its determination using HPLC-ECD will be useful for elucidating the role of this molecule in normal and disease conditions.

Animals↗

Determination of ciprofloxacin concentrations in human serum and urine by HPLC with ultraviolet and fluorescence detection.

OBJECTIVE: To develop a simple and sensitive high performance liquid chromatography method for the determination of ciprofloxacin concentrations in human serum and urine. METHOD: Serum proteins were removed by ultrafiltration through a filtering device after the addition of a displacing reagent. Urine samples were diluted with mobile phase prior to injection. Separation was achieved with a C18 reverse-phase column and using ultraviolet (UVD) and fluorescence detection (FD) for serum samples and UVD for urine samples. RESULTS: The quantitation limits of the assay were 20 ng/ml (FD) and 100 ng/ml (UVD) in serum and 1 microg/ml in urine. The assay was successfully applied to a pharmacokinetic study of ciprofloxacin in healthy volunteers. CONCLUSION: The method presented for ciprofloxacin assay in human serum and urine requires less sample clean up and is more sensitive than those reported in the literature.

Anti-Infective Agents↗

Increased nuchal translucency, hydrops fetalis or hygroma colli. A new test strategy for early fetal aneuploidy detection.

OBJECTIVES: Nuchal translucency measurement of 3 mm or more (> or = 95th centile for gestation age), hydrops fetalis or hygroma colli between the 11th and 14th weeks of gestation is associated with a higher risk of fetal Down syndrome and other aneuploidies. So far, chromosome preparation of chorionic villi samplings (CVS) after short-term (or direct) culture is the only valid, reliable and rapid method of choice for the early detection of chromosomal aberrations. However, because of the placental mosaicisms detected after short-term culture, CVS has to be confirmed by a second method. Moreover, short-term villi preparation does not always provide a sufficient quantity and quality of metaphases to enable cytogenetic analysis. Unfortunately, a predicative cytogenetic result will be available only after long-term cultivation (usually after 1-2 weeks). An alternative rapid method, inexpensive and suitable for diagnosing autosomal trisomies, is the quantitative fluorescence polymerase reaction (QF-PCR) using different polymorphic small tandem repeats (STRs) on CVS-DNA. Therefore, it was the aim of the study to evaluate whether a new CVS test strategy could be employed in early pregnancies at high risk after the rapid detection of fetal chromosomal abnormalities by QF-PCR for chromosomes 13, 18 or 21 and sexing in conjunction with short-term chromosome analysis. MATERIALS: Nineteen CVS were chosen for QF-PCR detection of trisomy 21, 18 or 13 after an increased nuchal translucency measurement (> or = 95th centile for gestation age), a hydrops fetalis or a hygroma colli. The amelogenin locus of chromosomes X and Y (AMXY) were used for sexing. The QF-PCR results were compared with routine karyotyping after short- and/or long-term cultivation of CVS cells. RESULTS: An informative result was demonstrated in all analysed specimens. Nine CVS were diagnosed as a QF-PCR trisomy either for chromosome 21, 18 and 13. The pathological samples also included 4 cases of mosaicism where the normal cell line was not identified by QF-PCR. In 1 additional case with a normal QF-PCR result, short-term CVS chromosome analysis showed a mosaic trisomy 13, whereas longterm CVS culture revealed a normal karyotype. The malformed aborted fetus showed no clinical signs of trisomy 13, confirming the normal results obtained by QF-PCR and long-term CVS chromosome analysis. One pregnancy with a Turner syndrome was not identified by molecular analysis. CONCLUSIONS: This study showed that all early pregnancies with a clinically relevant autosomal trisomy could be detected prenatally in routine practice by QF-PCR. The combined use of both rapid methods - QF-PCR and short-term chromosome analysis - optimise the results by minimising the possibility of false-positive or false-negative findings. We believe that after verification of a pathological result obtained by two independent methods (QF-PCR and short-term CVS chromosome analysis), long-term villi cultivation is no longer necessary. However, in all cases with discrepancies, especially in samples with mosaic findings at short-term CVS cultivation, further studies are still necessary.

Chorionic Villi Sampling↗

Immunoreactivity of recombinant squamous cell carcinoma antigen and leupin/SCCA-2: implications for tumor marker detection.

OBJECTIVES: Squamous cell carcinoma antigen (SCCA) is a member of the serpin superfamily, and has been used as a serological tumor marker for cervical squamous cell carcinomas. We have identified a closely related serpin gene, leupin (SCCA-2), which may be the fraction previously thought to be the acidic isoform of SCCA. The purpose of this study is to isolate the individual recombinant proteins, to examine their reactivity with current immunological detection methods, and to use a gene-specific method to examine their expression in the uterine cervix. METHODS: We have expressed and purified recombinant forms of SCCA and leupin individually. The proteins were characterized with respect to their isoelecric points and their reactivity with the monoclonal antibody from the current tumor marker diagnostic immunoassay (IMx SCC). Reverse transcription polymerase chain reaction (RT-PCR) with gene-specific primers was used to examine expression of both genes. RESULTS: Isoelectric focusing shows that leupin is the more acidic antigen with a determined pI for recombinant leupin (rLeupin) of 6.01, with rSCCA having a pI of 6.17. The IMx SCC monoclonal antibody recognized both rSCCA and rLeupin in immunoassays and immunoblots and both genes are expressed in normal cervix and in cervical carcinoma tissue. CONCLUSIONS: The findings from this study suggest that all previous clinical studies examining SCCA expression have used methodology that detects two gene products. The confirmation that leupin or SCCA-2 is the more acidic protein and that its expression is significantly elevated in cervical cancer suggests that this gene product may be the more important tumor marker.

Antibodies, Monoclonal↗

[Determination of serum tryptophan by high performance liquid chromatography with fluorescence detection].

OBJECTIVE: To develop a rapid assay for determining tryptophan in human serum. METHODS: The serum sample was injected into the high performance liquid chromatography (HPLC) system after the precipitation of protein with perchloric acid, and was monitored with a fluorometric detector with wavelength settings of 254 nm for excitation and 313 nm for emission. The mobile phase is 20% acetonitrile. RESULTS: Good linearity was observed in 1.22-400 mumol.L-1 range for tryptophan. The detection limit was 0.1 mumol.L-1. The intra- and inter-assay coefficients of variation (CV) were 2.57% and 3.66%, respectively. The average recovery was 97.13%. The detection time of serum tryptophan was within 5 min. Phenyalanine, tyrosine, serotonin, and 5-hydroxyindoleacetic acid didn't interfere in the assay. CONCLUSION: This method is simple, rapid, sensitive, accurate, and suitable for clinical application.

Chromatography, High Pressure Liquid↗

Y-STR analysis for detection and objective confirmation of child sexual abuse.

We evaluated 26 child sexual assault cases for the incorporation of Y-STR screening in the routine detection and objective confirmation of sexual contact between the child victim and the perpetrator. Various samples, e.g. vaginal or anal swabs from patients aged 2-17 years old (25 females, 1 male), were collected 6-72 h after the incident. Due to the limited amounts of DNA in these samples, total DNA was extracted using a one-step procedure and screened with autosomal STRs to detect signs of a victim-assailant DNA mixture and with Y-STRs for assailant DNA. Autosomal STRs failed to give signs of victim-assailant DNA mixtures while Y-STRs were detected in 24 of the 26 cases corresponding to a success rate of 92.3%. With the possible presence of both male sperm and/or male epithelial cells in forensic evidence, Y-STR DNA markers were detected regardless of external ejaculation, microscopic detection of sperm and with post-coital intervals of up to 72 h. While only partial profiles were generated owing to low quantities of male DNA present, Y-STR screening results can serve as objective evidence of sexual contact in child sexual abuse cases involving victims who do not have any previous sexual history. This type of evidence can corroborate child victim testimony and spare the child victim from further trauma caused by prolonged forensic investigations and court proceedings. Alternatively, Y-STR screening can provide objective proof of non-involvement of an accused with the victim.

Adolescent↗

Early genetic sonogram for Down syndrome detection.

OBJECTIVE: The purpose of this study was to determine the Down syndrome sensitivity of early genetic sonography (14-<16 weeks of gestation) and to compare its diagnostic accuracy with that later in the mid trimester (16-24 weeks of gestation). STUDY DESIGN: Nuchal thickness, humerus and femur lengths, hyperechoic bowel, hypoplastic fifth digit (clinodactyly), and any gross anatomic defects were measured or ascertained in singleton pregnancies that were undergoing genetic amniocentesis. Multiple stepwise logistic regression analysis was used to determine the significant sonographic markers for Down syndrome detection in each group. Multivariate gaussian algorithms that included maternal age were used to estimate patient-specific Down syndrome risk. Sensitivity and false- positive rates, receiver-operating characteristic curves, and area under the curves were calculated and compared for both groups. RESULTS: There were 1,727 pregnancies with 22 Down syndrome fetuses (1.27%) in the early group versus 3,914 pregnancies with 86 Down syndrome fetuses (2.2%) in the later group. The mean +/- SD ages were 15.5 +/- 0.4 weeks versus 17.6 +/- 1.4 weeks, respectively. Early genetic sonography (14-<16 weeks) had a 100% detection rate, with a 21.2% false-positive rate. The early versus later genetic sonography had an 81.8% versus 61.6% detection rate, respectively, at a fixed 4.8% false-positive rate. Early sonography had significantly higher diagnostic accuracy (area under the curve, 0.962 vs 0.871, respectively; P =.005). In fetuses at 14 to 15 weeks, the genetic sonography was also highly accurate, with 100% detection with a 21.9% false-positive rate. CONCLUSION: Early genetic sonography is highly sensitive and statistically superior to later ultrasonography for Down syndrome detection. Early midtrimester sonography achieved a diagnostic accuracy similar to that currently reported for first-trimester nuchal translucency.

Adult↗

Codeine and clinical impairment in samples in which morphine is not detected.

OBJECTIVE: Codeine metabolises partly to morphine by the liver enzyme CYP2D6, which is subject to genetic polymorphism. It has been suggested that analgesic effects of codeine are due to the morphine metabolite. Codeine effects other than analgesia have been less investigated in this regard, but it has been suggested that sedation, for example, might be independent of morphine formation. The aim of our study was to investigate the influence of codeine alone, without concomitant presence of morphine, on a clinical test for drunkenness (CTD) performed in relation to suspected drugged driving. METHODS: Cases with detected codeine but not morphine, nor any other drug above the limit of detection, were selected from the database of suspected drugged drivers at National Institute for Forensic Toxicology, Oslo, Norway. Codeine blood concentration in these samples was compared with the conclusions from the corresponding individual CTD. RESULTS: Of the 43 cases fulfilling the selection criteria, 23 were judged as "not impaired", and 20 as "impaired". Mean blood codeine concentration in the "not impaired" group was 143 ng/ml (95% CI 48-238, median 63 ng/ml). Mean concentration in the "impaired" group was 213 ng/ml (95% CI 146-279, median 159 ng/ml). There was a statistically significant concentration difference between the two groups. Codeine blood concentrations were further grouped as "moderate", "medium high" and "high". When adjusted for age, gender and chronic use, the odds ratios for being judged as impaired were 6 (95% CI 1-32, P=0.04) and 19 (95% CI 2-182, P=0.01) for the "medium high" group and the "high" group, respectively, relative to the "moderate" group. CONCLUSION: Codeine appeared to have some dose-dependent effect on the central nervous system that may lead to impairment as judged from a CTD, independent of measurable blood morphine concentrations. This supports the view that some codeine effects do not seem to be mediated by morphine.

Adult↗

Ethambutol resistance testing by mutation detection.

OBJECTIVE: To identify chromosomal mutations that confer resistance to ethambutol (EMB) in Mycobacterium tuberculosis. DESIGN: Drug-resistant (n = 235) and drug-susceptible (n = 117) M. tuberculosis isolates collected from the Western Cape in South Africa were subjected to embB gene analysis and the results were compared to phenotypic EMB testing. RESULTS: Genotypic analysis identified mutations at codon 306 of the embB gene in 20% (47/235) of the resistant isolates in comparison to only 1.7% (4/235) of those that were phenotypically resistant to EMB by the agar diffusion method. No gene mutations were detected in susceptible isolates. Phenotypic retesting in BACTEC demonstrated that the 47 genotypically resistant isolates were phenotypically resistant to EMB. This implies that 91.4% (43/47) of EMB resistance had been phenotypically missed by routine laboratory procedures. EMB resistance was closely linked to multidrug resistance (MDR); 87.2% (41/47) of the EMB-resistant isolates were resistant to both isoniazid and rifampicin. A newly developed one-step amplification refractory mutation system polymerase chain reaction (ARMS-PCR) method correctly detected the EMB-resistant genotype. CONCLUSION: Implementation of more accurate diagnosis of EMB resistance may enhance patient management in South Africa, as standardised treatment of MDR-TB with second-line drugs is currently dependent on the outcome of the EMB resistance test.

Antitubercular Agents↗

[Evaluation of prostate specific antigen (PSA) adjusted to transition zone in prostatic cancer detection].

OBJECTIVE: To investigate if PSA adjusted to transition zone (PSA-TZ) can be considered as a predictor parameter of cancer with better specificity or not than PSA, PSA density (PSAD) or PSA free/total ratio. MATERIAL AND METHODS: Data of 706 patients with sextant prostatic biopsies are analyzed in prospective way because of prostatic cancer suspicion. Range of PSA was between 4 to 20 ng/ml. Determination of PSA-TZ was calculated by dividing the PSA value by the volume of the transition zone of the prostate applying the ellipsoid formula and comparison of obtained results in detection of cancer was performed by ROC curves analysis for each one of PSA-related parameters. RESULTS: Of the total group of patients, in 199 cases (28.2%) prostatic cancer was detected. Analysis by ROC curves demonstrated than PSA-TZ and PSAD were better predictors of cancer than PSA free/total ratio and PSA (p < 0.0001). The cutoff value of PSA-TZ of 0.18 ng/ml/cc was considered as the best, obtaining a 95% sensitivity and a 27% specificity. For this sensitivity, PSA, PSAD and PSA free/total ratio only obtained 5, 9 and 16% specificity respectively. Areas under curve (AUC) obtained for PSA, PSA free/total ratio, PSAD and PSA-TZ were 0.539, 0.612, 0.694 and 0.722 respectively. CONCLUSIONS: PSA-TZ in the studied population was a parameter with better diagnostic specificity than PSA, PSAD and PSA free/total ratio for the same 95% sensitivity. This would justify its utility in clinical paractice reducing the number of unnecesary biopsies.

Aged↗

Evaluation of clinical application of gap-PCR as a routine method for alpha-thalassemia carrier detection.

OBJECTIVE: To evaluate the feasibility of using gap-PCR for routine screening of alpha-thalassemia in clinical laboratory. METHODS: A total of 382 clinical blood samples randomly collected from the population of Zhuhai city were screened for alpha-thalassemia determinants with hematological and gap-PCR method respectively in a double-blind manner. Parallel analysis with Southern blotting was performed to verify the genotyping results by PCR. RESULTS: Of the 382 samples tested, 3 common alpha-thalassemia genes with genotypes of --(SEA)/alpha alpha, -alpha(3.7)/alpha alpha and -alpha(4.2)/alpha alpha were detected in 21 (5.50%), 7 (1.83%) and 3 (0.79%) cases respectively by gap-PCR, including 7 cases with normal phenotype and 3 case of iron-deficiency anemia. The overall incidence of alpha-thalassemia was 8.12% in the population of Zhuhai city, as determined by gap-PCR, in total agreement with the results by Southern blotting. Only 21 of the 31 alpha-thalassemia cases were identified by hematological analysis (besides 2 cases with alpha-thalassemia phenotype undetermined), which had a false-negative rate of 32.3%. Seven silent alpha-thalassemia and 3 mild alpha-thalassemia cases failed to be detected by hematological analysis, resulting in a rate of 2.62% for failure of detection. CONCLUSION: Gap-PCR method is specific and feasible as a better alternative for alpha-thalassemia screening, especially advantageous in detecting silent carriers in comparison with hematological method.

DNA↗