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Biomedical subjects

K Spencer

Publications and source records attributed to K Spencer.

At least 19 recordsLinked to original sources
PubMed1992

Dual Analyte immunoassay--a new approach to neural tube defect and Down's syndrome screening.

A microtiter plate based Dual Analyte enzyme-immunoassay method for the simultaneous measurement of alpha-fetoprotein (AFP) and Free-beta human chorionic gonadotrophin (hCG) was evaluated. This rapid assay, which has application in both Neural Tube Defect screening and Down's screening, shows good precision with between assay coefficients of variation between 5 and 7.5% for AFP and 3.7 to 5.8% for Free-beta(hCG). Correlation with single analyte procedures is good, with correlation coefficients being greater than 0.91 in both cases. Clinical discrimination in detecting both types of abnormalities is not compromised by this new simultaneous Dual Analyte assay. We conclude that the Dual Analyte approach, which combines analytes achieving the highest known detection efficiency, will bring about improvements in the efficiency of screening, reduce costs and improve report turnaround, all leading to better quality of patient care.

Chorionic Gonadotropin↗
PubMed1992

Free beta human choriogonadotropin in Down's syndrome screening: a multicentre study of its role compared with other biochemical markers.

To ascertain the value of maternal serum free beta-human choriogonadotropin subunit measurement in Down's syndrome screening and to compare its effectiveness when screening with a variety of biochemical markers, we have evaluated maternal serum free beta-human choriogonadotropin, total human choriogonadotropin, alpha-fetoprotein and unconjugated oestriol in a large multicentre study of over 2800 unaffected cases and 90 affected cases, the largest collection of Down's cases ever reported. Of all the markers identified to date, free beta-human choriogonadotropin is the marker of choice for use in Down's syndrome screening. When used in early gestation (14-16 weeks) in combination with alpha-fetoprotein and maternal age, it will allow the detection of 77% of Down's cases. A side-by-side comparison with the performance of total human choriogonadotropin shows the superior detection efficiency of free beta-human choriogonadotropin. Unconjugated oestriol adds nothing further to the detection rate compared with the use of alpha-fetoprotein and free beta-human choriogonadotropin alone, and its use results in a 1% increase in false positive rate. We conclude that unconjugated oestriol has no value in Down's screening. The superior detection rate obtained using free beta-human choriogonadotropin is a result of superior detection of Down's cases in women under 30 years old, where the free beta-human choriogonadotropin combination detects 100% more cases than does the total human choriogonadotropin combination.

Biomarkers↗
PubMed1992

The Americans With Disabilities Act of 1990 expands employment opportunities for persons with developmental disabilities.

The primary purpose of the ADA is the full inclusion of persons with disabilities within their communities. The ADA prohibits discrimination on the basis of disability in the areas of employment, transportation, public accommodations, telecommunications, and state and local government agencies. The person described in this report encountered some of this discrimination. He successfully obtained paid community-integrated employment only after overcoming major obstacles and barriers, the greatest being transportation. In our highly mobile society, reliable transportation is essential for the acquisition and maintenance of community-integrated employment. The participant was repeatedly denied access to public transportation on the basis of his disability. To help overcome this barrier, Transition Services had to provide needed transportation at great expense, which delayed opportunities for the participant to gain control of this aspect of his life. Enactment of the ADA makes it more difficult for public transportation agencies to deny services to persons with disabilities by claiming inconvenience or lack of accessible vehicles. When publicly funded transportation programs assume their full responsibility for transportation to the public, agencies like Transition Services can focus on individualized employment and training issues rather than on providing transportation. In the workplace, the employer's willingness to work cooperatively with the participant and the staff of Transition Services resulted in several low-cost and reasonable accommodations based on the participant's needs and abilities. A simple rearrangement of work space allowed the participant to perform his job while benefiting the other workers in the crowded restaurant kitchen.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1991

Evaluation of an assay of the free beta-subunit of choriogonadotropin and its potential value in screening for Down's syndrome.

In this study I investigated the analytical and clinical performance of the measurement of the free beta-subunit of choriogonadotropin (hCG) in normal pregnancies and in pregnancies affected by Down's syndrome. Free beta-hCG in maternal serum has been shown to be increased in Down's syndrome-affected pregnancies and is proportionally increased in more cases than is total hCG. This study confirms previous findings of low concentrations of unconjugated estriol and alpha-fetoprotein in maternal serum in Down's syndrome-affected pregnancies. Using a multivariate risk analysis of maternal age and concentrations of alpha-fetoprotein, unconjugated estriol, and hCG in maternal serum, I determined that, at a risk cutoff value of 1 in 300, 52% of Down's cases could be detected with total hCG in the calculation, compared with 66% with the free beta-hCG concentration. The false-positive rate was 5.9% in both cases. Therefore, free beta-hCG can be used effectively in a screening program for Down's syndrome; however, further studies are required to ascertain whether the measurement of free beta-hCG has any advantages over the use of total hCG for detecting Down's syndrome.

Analysis of Variance↗
PubMed1989

Effect of xylazine in heifers under thermoneutral or heat stress conditions.

A study was performed to assess the effect of xylazine HCl (0.1 mg/kg of body weight, IV) in heifers maintained at thermoneutrality (18 C, 42% humidity) or under heat stress (33 C, 63% humidity) conditions. Xylazine caused 50 and 70% decreases in serum insulin concentrations in the thermoneutral and heat-stressed heifers, respectively. Xylazine-induced hypoinsulinemia was associated with hyperglycemia. In the thermoneutral group, serum glucose concentrations increased from a basal concentration of 75 mg/dl to 150 mg/dl after 15 minutes. In the heat stress group, the serum glucose concentration increased from 65 mg/dl to 105 mg/dl. Hyperglycemia peaked at 2 hours and remained high for 6 hours after xylazine administration. Heat-stressed heifers took a longer time (107 minutes) to stand than did heifers under thermoneutral conditions (41 minutes). The time to regain sensation to pain was significantly prolonged in heat-stressed heifers. Xylazine had no effect on body temperature and respiration rate in heifers under the thermoneutral condition, whereas it markedly induced hyperthermia and suppressed respiration rate in the heat-stressed heifers. Furthermore, the pulse rate was slightly decreased in thermoneutral heifers and was markedly decreased in the heat-stressed heifers.

Animals↗
PubMed1988

Neurone specific enolase in amniotic fluid: a potential marker of anencephaly.

Normal values for neurone specific enolase in amniotic fluid have been found to follow a non gaussian distribution with a 1-99 centile range of 1.10-4.32 micrograms/L. Neurone specific enolase levels have been shown to be raised in the amniotic fluid of pregnancies complicated by anencephaly, although not those complicated by open spina bifida. Neurone specific enolase measured by radioimmunoassay is capable of totally discriminating between normal pregnancies and those complicated by anencephaly. The study demonstrates the possible value of investigating other neuronal proteins which may find value as adjuncts to amniotic fluid Alpha fetoprotein levels in the prenatal diagnosis of Neural Tube Defects.

Amniotic Fluid↗
PubMed1988

Antenatal diagnosis of neural tube defects using a coated bead immunoassay for acetylcholinesterase in amniotic fluid.

The development and validation of a coated bead immunoassay for amniotic fluid acetylcholinesterase is outlined. The assay has good precision (between assay CV of 6.8% within the normal range), and is linear up to 250 arbitrary units/L. The clinical validity of this assay has been assessed using a panel of amniotic fluid samples from normal and abnormal pregnancies. At an assay cut off level of 200 arbitrary units/L, all cases of neural tube defect-affected pregnancies were identified and the number of false positives was very small. False positives resulted from severe blood staining of the amniotic fluid. Since the monoclonal antibody used recognises red cell membrane acetylcholinesterase and the stored amniotic fluids had been frozen and thawed a number of times, the extent of this problem needs to be further assessed using freshly collected samples. The performance of this assay was found to be superior to the differential inhibitor colorimetric method and close to that of the electrophoretic procedure. The quantitative nature of the assay and the independence from operator technique makes it a useful adjunct to the measurement of amniotic fluid AFP in the prenatal diagnosis of neural tube defects.

Acetylcholinesterase↗
PubMed1985

Screening for Down's syndrome using serum alpha fetoprotein: a retrospective study indicating caution.

A report was made on the outcome of a four year retrospective study in 27 064 pregnancies, of the clinical efficiency, sensitivity, and specificity of a screening programme for Down's syndrome based on reported strategies related to the measurement of maternal serum alpha fetoprotein. This study identified 27 pregnancies affected by Down's syndrome with a median multiple of the median maternal serum alpha fetoprotein concentration of 0.82. This figure is considerably higher than that obtained from previous reports on this subject. With an age related multiple of the median maternal serum alpha fetoprotein strategy, 30.8% of Down's affected pregnancies were identified as well as 11.6% of unaffected pregnancies. Perhaps a United Kingdom collaborative study should begin to investigate the reasons for such wide population variance in the reports for the median multiple of the median for Down's affected pregnancies. Until such studies are carried out, screening for Down's syndrome based on low maternal serum alpha fetoprotein concentration is premature.

Adult↗
PubMed1979

Kinetic immunoturbidimetry: the measurement of pregnancy specific beta 1 glycoprotein.

The extension of kinetic immunoturbidimetry to the measurement of low concentration proteins has been described using the protein pregnancy-specific beta 1 glycoprotein. The technique has a precision superior to that of all other methods currently available. The assay is rapid, cheap and compares well with other published methods. The assay further emphasises the usefulness of the technique of kinetic immunoturbidimetry.

Female↗
PubMed1979

Kinetic immunoturbidimetry: the estimation of albumin.

The applicability of commercially available antisera for use in kinetic immunoturbidimetry has been studied using the protein albumin as a simple model. The sensitivity of the kinetic immunoturbidimetric approach has been found to be comparable to published data for nephelometric systems, being able to detect concentrations of protein as low as 1 mg/l. The technique has shown to be as precise as most dye binding techniques for the measurement of albumin, producing a within batch C.V. of 1.0% and a between batch C.V. of 1.5%. The technique was found to be comparable to another immunological technique (RID). The fast assay time (30--60 sec), cost and good precision makes this the method of choice for routine albumin measurement. The extreme sensitivity of the technique of kinetic immunoturbidimetry makes the technique applicable to the estimation of a wide range of proteins in blood, urine and CSF.

Coloring Agents↗