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Biomedical subjects

D J Brock

Publications and source records attributed to D J Brock.

At least 127 records · Page 7Linked to original sources
PubMed1986

Monoclonal antibodies to cystic fibrosis antigen.

A series of monoclonal antibodies has been prepared against a granulocyte antigen previously shown to be present in the serum of individuals homozygous or heterozygous for the cystic fibrosis (CF) gene. The specificity of the monoclonals was established by their ability to remove the antigen (CF antigen) from serum. The monoclonals defined at least two epitope regions on CF antigen, thus permitting the establishment of a two-site sandwich enzyme-linked immunosorbent assay (ELISA). Using the ELISA significant differences in levels of CF antigen were demonstrated in serum samples from CF homozygotes, CF heterozygotes and normal controls.

Antibodies, Monoclonal↗
PubMed1986

A monoclonal antibody assay technique for plasma and red cell acetylcholinesterase activity in Alzheimer's disease.

Acetylcholinesterases (AChE) in human plasma and red cells have been considered as possible markers for Alzheimer's disease. Findings however vary widely and no significant pattern has emerged. The present study has used a new technique for AChE assay based on a monoclonal antibody raised against red cell AChE. This allows AChE isoenzymes to be measured directly in the presence of non-specific cholinesterases without the need for inhibitors. AChE activity in plasma and red cells was assayed in Alzheimer's disease, multi-infarct dementia, Huntington's and alcoholic Korsakoff syndrome, and the results compared both between groups and with normal controls. No significant differences in either red cell or plasma enzyme activity were found by any of these comparisons. Our findings do not suggest that in the dementias peripheral AChE activity reflects altered central cholinergic function, nor that it is likely to prove a useful marker for Alzheimer's disease.

Acetylcholinesterase↗
PubMed1985

A monoclonal antibody-based immunoassay for human lactoferrin.

Monoclonal antibodies against human lactoferrin define at least 3 and possibly as many as 6 different epitopes. A sandwich enzyme-linked immunoassay, using monoclonals against different epitopes, has been optimised for the measurement of serum lactoferrin. In 35 samples from healthy adults the mean lactoferrin content of serum from blood clotted overnight was 0.54 +/- 0.26 micrograms/ml.

Adult↗
PubMed1985

First trimester diagnosis of hypophosphatasia with a monoclonal antibody to the liver/bone/kidney isoenzyme of alkaline phosphatase.

Prenatal diagnosis of hypophosphatasia was made by alkaline phosphatase (ALP) assay on a chorionic villus sample taken in the first trimester. Monoclonal antibodies against the liver/bone/kidney (LBK) and placental isoenzymes of ALP were used, and the bound isoenzymes were quantified by an amplification system. Very low activities of the LBK isoenzyme indicated an affected fetus. Diagnosis was confirmed by ultrasound scan at 15 weeks' gestation, and by ALP measurement in amniotic fluid supernatant and fetal serum.

Adult↗
PubMed1985

Prospective prenatal diagnosis of cystic fibrosis.

An immunoassay based on monoclonal antibodies with specificity for the three major isoenzymes of alkaline phosphatase (ALP) has been used in second-trimester prenatal diagnosis of cystic fibrosis (CF). 140 pregnancies with a 1-in-4 risk of CF were assessed prospectively, and outcomes are reported for 100 of these. In 9 cases the diagnosis could not be confirmed or excluded, in 65 cases the infant was normal, and in 15 the infant had CF. In the remaining 11 cases, in which the pregnancy was terminated, the diagnosis of CF was confirmed in the abortus by measurement of albumin and protease levels in meconium scraped from the fetal ileum. Of the 26 cases of CF in the prospective series, 23 (88%) had values of intestinal ALP below half the median value for the corresponding week of gestation. Among those with normal outcomes 3 of 65 (4.6%) were below half-median. When prospective and retrospective data are summed the sensitivity of the test was 91% (39 of 43) and the false-positive rate 6% (5 of 81). This is probably an acceptable form of prenatal diagnosis of CF for the high-risk mother.

Amniotic Fluid↗
PubMed1985

Prenatal diagnosis of neural-tube defects with a monoclonal antibody specific for acetylcholinesterase.

An immunoassay for acetylcholinesterase (AChE), based on a monoclonal antibody (AE-2), gave the following results when applied to a panel of amniotic fluids: (a) among 651 samples with normal outcome and normal alphafetoprotein (AFP) values there were 2 (0.31%) false positives; (b) of 9 samples with normal outcome and raised AFP values 1 had a raised AChE titre; (c) all 48 samples from anencephaly cases had raised AChE values; (d) among 49 samples from open spina bifida cases (2 of which had normal AFP values), 48 had raised AChE titres. It is suggested that a monoclonal-antibody-based immunoassay may displace polyacrylamide gel electrophoretic analysis of AChE as a complementary test to AFP in prenatal diagnosis of neural-tube defects, since it is a quantitative test largely independent of operator skill and experience.

Acetylcholinesterase↗
PubMed1984

Quantitative estimation of the density ratios of cholinesterase bands in human amniotic fluids.

Quantitative densitometry has been used to measure cholinesterase bands in amniotic fluids after polyacrylamide gel electrophoresis. The ratio of acetylcholinesterase (AChE) to pseudocholinesterase ( PChE ) could be used both for diagnosis and for differential diagnosis of fetal abnormalities. Normal amniotic fluids had AChe/ PChE density ratios of zero, while neural tube defect fluids were all above 0.15. Ventral wall defect samples had ratios below 0.15, as did false positives due to contamination with human fetal serum. In samples which had been accidentally contaminated with fetal calf serum, density ratios were above 0.15. Similar results were obtained with both slab gel and rod gel electrophoresis.

Acetylcholinesterase↗
PubMed1984

A screening assay for monoclonal antibodies based on the availability of a polyclonal antiserum.

A double-sandwich enzyme-linked immunospecific assay (ELISA) has been developed for screening hybridoma clones for monoclonal antibodies against human alpha-fetoprotein (AFP). The assay uses commercial polyclonal antiserum to bind alpha-fetoprotein from biological fluids, and the complex then binds the specific monoclonal antibodies in hybridoma culture supernatants. The sandwich is completed with commercial peroxidase-linked anti-mouse immunoglobulin. In exploring the variables of this system, it was found that the quality of the polyclonal anti-alpha-fetoprotein antiserum was the most critical factor. The assay functioned with as little as 10 ng alpha-fetoprotein from cord serum or amniotic fluid. A variety of commercial peroxidase-linked second antibodies was satisfactory, and both IgG and IgA class monoclonals were detected. Comparison of the ELISA with a standard radioimmunoassay showed the former to perform very adequately as a general hybridoma screening assay.

Antibodies, Monoclonal↗
PubMed1984

Prenatal diagnosis of cystic fibrosis by assay of amniotic fluid microvillar enzymes.

Activities of the microvillar enzymes gamma-glutamyltranspeptidase (GGTP), aminopeptidase M (APM), phosphodiesterase and maltase have been examined in second-trimester amniotic fluid as possible aids to the early prenatal diagnosis of cystic fibrosis (CF). The two peptidases, GGTP and APM, gave best results. If the fifth percentile of the normal range is used as an action line, the sensitivity of a positive test (low GGTP value) is 78% and the predictability 84%. At the tenth percentile the sensitivity is 100% and the predictability 77%. These approximate figures apply only to pregnancies where there has been a previous affected child. Until the primary protein defect in CF is discovered, this may prove an acceptable form of prenatal diagnosis to the high-risk mother.

Aminopeptidases↗
PubMed1984

Immunoreactive trypsin and the prenatal diagnosis of cystic fibrosis.

Immunoreactive trypsin (IRT) was measured by radioimmunoassay in a series of amniotic fluids obtained at between 15 and 19 weeks from pregnancies with a 1-in-4 risk of fetal cystic fibrosis. IRT concentrations were significantly depressed in nine affected pregnancies, but the degree of overlap with the normal range was too great for this to be useful in early prenatal diagnosis. Furthermore, in one fetus, presumed to have cystic fibrosis, the fetal plasma IRT concentration was within the normal range.

Amniotic Fluid↗
PubMed1984

Approaches to the production of monoclonal antibodies specific for concanavalin A binding and non-binding forms of alphafetoprotein.

Attempts have been made to make monoclonal antibodies which would react preferentially with either the concanavalin A (con A) binding or non-binding from of human alphafetoprotein (AFP). Mice were immunised with con A non-binding AFP in a variety of schedules, and their spleens used in four separate fusions. Despite identification of 467 hybridomas secreting anti-AFP antibodies, no monoclonals could be found with consistent or reproducible specificity for either con A binding or non-binding AFP. Ten of the hybridomas were grown as ascitic tumours. The resulting ascitic fluids defined 4 discrete epitopes on the AFP molecule. There was no apparent difference in the binding of a particular monoclonal antibody to its target epitope in the con A binding and non-binding forms of AFP. This finding is discussed in the light of current knowledge of the molecular structure of the carbohydrate chains of con A binding and non-binding forms of AFP.

Antibodies, Monoclonal↗