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PubMed2003

Fast volatile organic compound recovery from soil standards for analysis by thermal desorption gas chromatography.

The development of high-throughput environmental screening assays are needed to meet high-specification data quality objectives (DQOs) that require large numbers of samples to be taken and analysed rapidly. The acquisition and stabilisation of the sample is a key technical and operational challenge in analytical sequences associated with the determination of volatile organic compound (VOC) contamination of soils. Further the development of miniaturised and embedded analytical systems for environmental conditioning monitoring requires the development of new sampling techniques. A proof-of-concept study is described that shows how pressurised gas, in this case carbon dioxide, may be used to recover reversibly-bound VOCs from soil into an adsorbent sampler, and then analysed by thermal desorption-gas chromatography. The effects of the volume of the pressurised gas, the gas flow rate and the mass of the soil sample on the recovery efficiency and breakthrough from the adsorbent trap were investigated in a preliminary characterisation study. Two distinct approaches were identified. The first involved ventilation of the voids within the soil matrix to displace the soil-gas headspace, a rapid screening approach. The second involved a more prolonged purge of the matrix to strip reversibly bound species into the gas phase and hence pass them into the adsorbent trap, a purge and trap approach. The shortest possible sample processing time required to yield analytically useful responses was 5 s with the use of the headspace approach. In this case n-octane, benzene and toluene were recovered from conditioned spiked soil samples at concentrations in the range 42 to 1690 mg kg(-1). The limit of detection for the system was estimated to be no greater than 1.2 mg kg(-1). Using the purge and trap variant enabled recovery efficiencies greater than 93% to be achieved with liquid spikes of n-octane onto soil samples. These preliminary studies showed that a system based on this approach would need to balance recovery efficiency, time and analyte breakthrough from the adsorbent trap.

Chromatography, Gas↗
PubMed1987

An advanced cochlear echo technique suitable for infant screening.

An advanced cochlear echo test technique has been specially developed to tackle some specific problems associated with measurements from infants. The test procedure and data processing combination has greatly improved noise immunity and has given very reliable results on poorly co-operating children. Technical details are given and the results of a study of 105 ears from 55 children are presented. The potential of the advanced technique as a screening test is discussed.

Adolescent↗
PubMed1987

Endometrial cytohistology by the pistol-aspiration technique: clinical applicability.

The purpose of this study was to assess the value of the endometrial pistol-aspiration technique as an office procedure for diagnosing corpus uteri cancer in symptomatic and asymptomatic women. Review of 3000 pistol aspirations in symptomatic outpatient women from 1974-1981 confirms that this method, with its high specificity and sensitivity, can be used for such women as a preliminary diagnostic procedure, eliminating risks from anesthesia and curettage as well as the cost of hospitalization. Analysis of resident incident cases shows that 82% were localized to the uterus, and more than 85% of these women were already symptomatic. Older women represent particularly difficult problems, both technical (cervical stenosis) and in recruitment. Because the natural history of the precursor lesions of corpus uteri cancer are not yet well established, use of this method for systematic population screening of asymptomatic women is questionable.

Adult↗
PubMed1994

Response to venepuncture for monitoring in primary schools.

The feasibility and acceptability of collecting blood from children by venepuncture was assessed in a sample of 593 children from seven primary schools in Canterbury. Venepuncture is necessary to obtain blood for the measurement of haemoglobin, ferritin, and cholesterol in line with Department of Health surveys in England. Return of consent forms was 87%; 75% of parents in the total sample allowed their child to be tested. Response rates differed between schools. Only 4% of eligible children refused to participate at the time of testing. In 22 (3.7%) children a blood sample could not be obtained or the volume was insufficient for analysis. There was a significant difference in the failure rate between phlebotomists. Venepuncture in the school setting was technically feasible and acceptable. The reluctance of some groups in the community to participate may bias the sample.

Bloodletting↗
PubMed1997

[Serum screening of pregnant women reveals Down syndrome. Analysis of biochemical markers for earlier detection].

Second trimester maternal serum screening for fetal Down's syndrome (DS), using the AFP (alpha-fetoprotein), hCG (human chorionic gonadotrophin) and uE3 (unconjugated oestriol) triple test, is as well documented procedure associated with a DS-detection rate of about 70 per cent, for an amniocentesis rate of about 7 per cent. The triple test is relatively little used in the Nordic countries, though its wider use would result in more efficient diagnosis of DS and various fetal malformtions. The maternal age indication currently used leaves gravidae under 35 years of age without prenatal diagnostics, although it is in just this age group that the majority (70 per cent) of cases of fetal DS occur. In Denmark, where 12 per cent of gravidae undergo invasive diagnostic procedures, the proportion of induced abortions due to the procedures is far too high, in relation to the DS detection rates obtained. Maternal serum screening yields a much better ratio between the risk of abortion after amniocentesis and the likelihood of DS detection than does maternal age alone. Maternal serum screening at 7-14 weeks of gestation, using pregnancy-associated plasma protein A and free hCG beta subunit concentrations, will become available within the next few years, thus reducing the incidence of some of the psychological and technical problems associated with second trimester screening, especially that of third trimester abortion. Irrespective of whether it is performed in the first or the second trimester, maternal serum screening will be the cornerstone of prenatal DS diagnosis in the future.

Biomarkers↗
PubMed2006

Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography-atmospheric pressure ionisation mass spectrometry.

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006.

Aflatoxins↗
PubMed1991

Assessment of screening for cancer.

Screening has a relevant role in and is likely to become an increasingly important instrument for cancer control in the near future. This overview summarizes some of the available evidence on the issue. Some of the opinions are well established. The apparent absence of consensus on other issues should be critically evaluated, too, because the evidence on some procedures is substantially more convincing than that on others. High costs, low compliance, poor curability, and substantial false positive rates, in a disease as relatively rare as cancer, often counterbalance in practice the theoretical benefits of diagnostic anticipation. In screening as well as in treatment for cancer, it is unlikely that major technical breakthroughs will occur in the near future. The evaluation of whether the benefits likely to be achieved by the screening program outweigh its disadvantages by a sufficient margin, therefore, should rely on large and carefully planned controlled studies.

Evaluation Studies as Topic↗
PubMed2003

A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy.

AIMS: To compare the respective performances of digital retinal imaging, fundus photography and slit-lamp biomicroscopy performed by trained optometrists, in screening for diabetic retinopathy. To assess the potential contribution of automated digital image analysis to a screening programme. METHODS: A group of 586 patients recruited from a diabetic clinic underwent three or four mydriatic screening methods for retinal examination. The respective performances of digital imaging (n=586; graded manually), colour slides (n=586; graded manually), and slit-lamp examination by specially trained optometrists (n=485), were evaluated against a reference standard of slit-lamp biomicroscopy by ophthalmologists with a special interest in medical retina. The performance of automated grading of the digital images by computer was also assessed. RESULTS: Slit-lamp examination by optometrists for referable diabetic retinopathy achieved a sensitivity of 73% (52-88) and a specificity of 90% (87-93). Using two-field imaging, manual grading of red-free digital images achieved a sensitivity of 93% (82-98) and a specificity of 87% (84-90), and for colour slides, a sensitivity of 96% (87-100) and a specificity of 89% (86-91). Almost identical results were achieved for both methods with single macular field imaging. Digital imaging had a lower technical failure rate (4.4% of patients) than colour slide photography (11.9%). Applying an automated grading protocol to the digital images detected any retinopathy, with a sensitivity of 83% (77-89) and a specificity of 71% (66-75) and diabetic macular oedema with a sensitivity of 76% (53-92) and a specificity of 85% (82-88). CONCLUSIONS: Both manual grading methods produced similar results whether using a one- or two-field protocol. Technical failures rates, and hence need for recall, were lower with digital imaging. One-field grading of fundus photographs appeared to be as effective as two-field. The optometrists achieved the lowest sensitivities but reported no technical failures. Automated grading of retinal images can improve efficiency of resource utilization in diabetic retinopathy screening.

Adolescent↗
PubMedDate not supplied

[Lipiodol UltraFluid in the imaging diagnosis of hepatocarcinoma with cirrhosis].

Fifty patients with HCC associated with hepatic cirrhosis underwent intra-arterial injection of Lipiodol UltraFluid (LUF) during diagnostic DSA of liver parenchyma, 42 of them for a complete chemotherapeutic treatment, 8 for an isolated diagnostic control. LUF is known to be specifically captured by HCC neoplastic tissue, with long-term persistence in the lesion if injected in the arterial hepatic tree; this is not the case with other focal hepatic masses. Therefore LUF opacification can be used to demonstrate small daughter tumors not shown by CT or US in cases with evidence of HCC, or to diagnosis HCC in clinically positive patients with no evidence of tumor at non-invasive screening. In our series of patients, accumulation of LUF in the HCC was observed in 100% of the cases, with no false negatives. Two false positives (4%) were observed, due to CT being performed too early (it should be performed not sooner than 10 days after the injection). Overall DSA accuracy was 78%, with 22% false negatives. In 14% of the cases DSA was positive for HCC in patients with aspecific noninvasive screening. CT, performed 10 days after LUF injection, demonstrated HCC daughter tumors not depicted by US, conventional CT, and angiography, in 34% of the cases, and in 9% of the patients only CT/LUF was able to show HCC in clinically positive cases with no evidence of tumor on other imaging techniques. Specificity, sensitivity and over-all accuracy were thus 100% in our series; LUF was well tolerated by the patients, and no technical complications were observed. In our opinion, the diagnostic DSA and CT/LUF is justified only for the typification of suspected focal nodules unsuitable for biopsy: in other instances, especially in case of HCC with positive biopsy/clinical findings and focal nodular mass, the technique should be directly employed as a therapeutic approach, with the injection of lipiodolized agents to treat both primary and daughter nodules after surgery in operable patients, and to begin chemoembolization treatment in patients with intrahepatic polyfocal diffusion. DSA and LUF are therefore of primary importance in the diagnosis and therapeutic flow-chart of HCC associated with hepatic cirrhosis.

Angiotensin II↗
PubMed1987

Xeromammography.

Early detection of breast malignancy can insure more effective treatment and a more likely cure. The early detection of cancer of the breast has become the most vital factor in determining successful treatment, arresting the malignancy before it spreads to other organs. Women do not die from breast cancer--it is the cancer's invasion throughout the body and its affect on vital organ systems which ultimately kills the patient. It is, therefore, understandable why the earliest possible detection offers any woman the most favorable prognosis. Evaluation of the female breast using xeromammography techniques provides us with the technical capability of detecting breast cancer at the earliest and, in the majority of women, the most favorable stage. Using today's reduced dose techniques, any proposed risk, hypothetical or real, becomes insignificant.

Aged↗
PubMed1978

[Screening for neonatal hypothyroidism? Results of an international questionnaire study (author's transl)].

Questionnaires were sent to 23 centres in ten countries. Results indicate that, for ethical, scientific, clinical and socio-economic reasons, screening for neonatal hypothyroidism should be undertaken. Pilot studies are no longer required. Distribution of the birth-rate in the various lands of the German Federal Republic suggest that, assuming appropriate technical and staffing provision, ten centres with a sample rate of 200/day would be sufficient for full screening. Because of special features in quality control of radioimmunochemical methods, a uniform manner of setting up the necessary laboratories is essential.

Congenital Hypothyroidism↗
PubMed1982

So-called interval cancers of the breast. Pathologic and radiologic analysis of sixty-four cases.

Within a population-based breast cancer screening programs, 209 cancers were detected by regular mammographic screening. Additionally, 66 cancers were discovered between two consecutive screenings after one, two, or three negative screening examinations (interval cancers). The study group consisted of 25,920 women who have been participating since 1975 in a breast cancer screening program in Nijmegen, the Netherlands. In this program, single view mammography (lateromedial projection) was administered as the sole screening examination every two years. Physical examination was not part of the screening program. All previous histologic and radiologic material from 64 of those "interval" patients was available and was reviewed. In 19 of the 64 patients, direct or indirect signs of tumor were seen on the previous screening mammogram on review (observers error). In four cases the site of the tumor lay outside the imaging field (technical error). In 41 cases, no signs of tumor could be seen on the mammograms even on review. By calculated tumor doubling times, 20 of these 41 cases were probably too small to be detected at the last screening ("real" interval cancers). However, 21 cases were probably large enough but were somehow masked from radiologic detection. The mean reasons for this "masking" proved to be: 1) dense breast, 2) poorly outlined tumor mass of diffuse infiltrative type, mainly invasive lobular carcinomas, and 3) intraductal localization. The authors suggest that women with dense breasts be screened more frequently, using more views and modalities and with broader criteria for advising surgical biopsy. They also note that in general the two-year interval between screenings is probably longer than the optimal interval.

Aged↗
PubMed2003

Serological and proteomic evaluation of antibody responses in the identification of tumor antigens in renal cell carcinoma.

Renal cell carcinoma (RCC) is relatively resistant to conventional chemotherapy and radiotherapy. However, reports of spontaneous regression along with promising results in clinical trials suggest that immunotherapuetic strategies may be of clinical benefit. Few RCC related antigens have been identified to date, and the technical difficulty and time constraints of current antigen identification techniques preclude the screening of large numbers of patients. A comparatively rapid strategy has been used to identify components of tumors that elicit an antibody response in the patient - the serological and proteomic evaluation of antibody responses (SPEAR) approach. This combines two-dimensional polyarylamide gel electrophoresis of tumor and normal kidney samples with immunoblotting using autologous patient sera and protein identification by mass spectrometry. Using the SPEAR approach to screen RCC patients for naturally occurring antitumor antibody responses, a number of candidate immunogens have been identified in patients with high-grade disease and their relative expression levels in tumor tissue compared to normal tissue have been studied. These proteins include annexins I and IV, thymidine phosphorylase (TP), carbonic anhydrase I, Mn-superoxide dismutase and major vault protein (MVP). Downstream analysis of the tissue expression of some of these proteins shows that MVP is up-regulated in 2/4 of RCC tumors but is also expressed in normal kidney whereas TP is up-regulated in 100% (11/11) of RCC cases examined with no or minimal expression in normal kidney, indicating a potential use as a therapeutic target.

Annexins↗
PubMed1999

TSH assay using dried blood samples: a screening method for congenital hypothyroidism.

Capillary blood samples from three hundred healthy, full-term newborn within 48 and 120 hours of delivery, were collected on filter paper for analysis of thyroid-stimulating hormone (TSH). Blood was collected by pricking the heel of the newborn and spotted and dried on filter paper cards. The samples were analysed by immunoradiometric assay (IRMA) to determine the TSH level. Some fifteen percent of a total 1928 deliveries at two hospitals during a period of one year were included in the study. Male:female ratio was 1.1:1. There was no maternal history of thyroid disease. None of the babies had any clinical feature of hypothyroidism. On analysis, TSH level ranged from 0.6-19.3 microU/ml with a mean (SD) of 7.19 (4.21) microU/ml. TSH assay from dried filter paper blood spot is technically possible and is a cost-effective and reliable method for a screening programme. This is the first time in Bangladesh that this method has been successfully carried out.

Bangladesh↗
PubMed1993

[Reappraisal of the clinical usefulness of transabdominal ultrasonography for advanced colon cancer--a study of tumor detection].

We evaluated the detectability of colon cancer by using transabdominal ultrasonography (US). Fifty-three cases of proven advanced colon cancer were examined in this study. Screening by US was carried out in 27 of 53 cases and US was performed in all cases after the definite diagnosis. Lesions of the colon were examined by using a 3.5 MHz convex and 5 MHz or 7.5 MHz linear probe (Yokogawa RT-2800, RT-4600). Localized hypertrophy of the irregular wall of more than 10 mm or massive tumor without the normal layered structure was defined as colon cancer on US. The rate of detection by screening test was 52%. The detection rate by US after definite diagnosis was 75%. A high detection rate was obtained in cases with a tumor diameter of more than 4 cm. Eight of 13 cases which were not detected by the screening test were visualized by US after definite diagnosis. US examination is useful for the detection of certain extended lesions of colon cancer. With technical improvements of the examination method, it is considered that cancer in the gastrointestinal tract may be discovered early on screening tests using US.

Adult↗
PubMed1997

Randomized, controlled comparison of two forms of preparation for screening flexible sigmoidoscopy.

OBJECTIVE: There is a paucity of data regarding the optimal form of bowel preparation for flexible sigmoidoscopy. Most endoscopists recommend enemas. A simpler preparation that is easy, acceptable, and that reduces patient encounter time would be desirable, and might be cost-effective. Our objective in this study was to evaluate a simple oral form of preparation for screening flexible sigmoidoscopy. METHODS: In this randomized, single-blind, controlled trial, we compared two forms of preparation in consecutive male patients referred for screening flexible sigmoidoscopy. The oral preparation consisted of one bottle of magnesium citrate and two "Dulcolax" tablets on the evening before flexible sigmoidoscopy. This was compared with the standard form of preparation, namely, two Fleet's enemas given on arrival at the endoscopy suite. Thirty-seven patients received the oral preparation [mean age, 62.8 +/- 8.9 (SD) yr]; 33 received enemas (mean age, 65.2 +/- 7.3 yr). Endoscopists were blinded to the preparation. RESULTS: Mean time between arrival and starting flexible sigmoidoscopy was 36 +/- 22 (SD) min for patients on oral preparation, and 62 +/- 25 min for patients receiving enemas (p < 0.0001). Mean times performing flexible sigmoidoscopy were 10 +/- 3 min and 13 +/- 4 min, respectively (p = 0.004). Mean patient satisfaction score (range 0-13) was higher for patients given the oral preparation (11.4 +/- 1.8) than for patients receiving enemas (9.6 +/- 2.4) (p = 0.001). Fifteen patients randomized to receive the oral preparation had previous flexible sigmoidoscopy with an enema preparation; all preferred the oral form. Mean technical difficulty (range 1-10) was 3 +/- 2.2 for patients given the oral preparation and 4.9 +/- 3.1 for patients receiving the enema preparation (p = 0.01). Polyps were identified in 10/37 patients who received the oral preparation and in 3/33 patients who received enemas (p = 0.05). Quality of colon preparation was judged "good" in 29, "fair" in four, and "poor" in four, among the 37 patients given the oral form; corresponding values for 33 patients given enemas were 16, 10, and 7 (p = 0.03). CONCLUSION: Patient acceptance, encounter time, technical ease, and quality of colon preparation were significantly better with the oral form of colon preparation than with the standard Fleet enema preparation.

Administration, Oral↗
PubMed2005

Development and validation of the spaceflight cognitive assessment tool for windows (WinSCAT).

The Spaceflight Cognitive Assessment Tool for Windows (WinSCAT) was developed by an integrated product team as a tool to support medical operations at NASA Johnson Space Center and as way to monitor the neurocognitive status of space crews. It is based on 20 yr of experience in performance and cognitive testing within the U.S. Department of Defense. As a result, WinSCAT development has benefited from diverse efforts supporting its technical reliability and validation. The rationale, background, and development of WinSCAT are described, research supporting its use is summarized, and recommendations are made for its continued development.

Aerospace Medicine↗