Biomedical subjects

E M Nicholls

Publications and source records attributed to E M Nicholls.

12 recordsLinked to original sources

PubMed1992

A sensitive method for the detection of poly-A tails of mRNA using a biotin-labelled heteropolymer of dT:rA.

We have developed a highly sensitive non-radioactive in situ hybridization technique that enables us to study the production of mRNAs in tissues. As part of the validation procedure of our methods, we examined various methods of detecting poly-A RNA tails of mRNA. We have used three types of biotin-labelled probes complementary to poly-A sequences: a 25-mer poly-dT oligonucleotide, a polymer of dT, and a heteropolymer of dT:rA. All the probes had the same specificity of reactivity but the heteropolymer of dT:rA gave the strongest signals as visualized histochemically by the use of alkaline phosphatase as the detection enzyme. All the probes tested for poly-A detection showed reactivity. The poly-dT oligonucleotide showed a strength of signal comparable to published results. The biotinylated polymer of dT gave a stronger signal than that of the oligonucleotide, and the heteropolymer was the strongest of all. The strong signal seen with the heteropolymer probe is due to probe complexing during hybridization, in which additional binding between sense and antisense strands of the probe (i.e. poly-rA and poly-dT) amplifies the number of biotin molecules at the hybridization site; this strategy has been exploited by us as a means of visualizing low copy numbers of specific mRNAs.

Bone Marrow↗

PubMed1988

The development of action lines in an Australian maternal serum alphafetoprotein screening service for neural tube defects.

A retrospective study covering the period from January 1, 1980 up to June 30, 1982 was conducted, producing the first definitive normal range for maternal serum alphafetoprotein from the Royal North Shore Hospital in Sydney. The normal range established is based on and applicable to the pregnant women tested at this NSW laboratory. Maternal serum alphafetoprotein levels had been determined by radioimmunoassay for 3,182 pregnancies between 13 and 20 weeks' gestation. Five anencephalics and 2 open spina bifidas were noted in the study. Only one of these abnormalities (spina bifida) was associated with maternal serum alphafetoprotein levels within the normal range, the remainder all having elevated levels. Low false positive and false negative rates of 1.16% and 0.03% respectively were obtained in this study.

Female↗

PubMed1988

Ultrastructure of Campylobacter jejuni in gamma-irradiated mouse jejunum.

This paper describes the ultrastructure of intracellular elongated, transitional and coccoid forms of Campylobacter jejuni, in irradiated mouse jejunum infected both in vitro and in vivo and in cultured human skin fibroblasts. Jejunum of irradiated mouse incubated for 1 hour under conditions favorable to the organisms showed minimal tissue degeneration. The intracellular organisms in this material were free cytoplasmic forms showing inner membrane degeneration, loss of cytoplasmic granules, and absence of flagella. The diameter of the coccoids was up to four times that of the elongated forms, as in plate cultures. Intracellular organisms were not found in challenged unirradiated controls, indicating that irradiation of mouse cells may be required for intracellular infection with human strains of C jejuni. In contrast, challenged human fibroblasts contained typical elongated organisms in cytoplasmic vacuoles. These findings are discussed with reference to Campylobacter strain, host resistance, and "natural" animal and human Campylobacter infections.

Animals↗

PubMed1986

The buffy coat leukoagglutination (BCLA) test.

The clumping of leukocytes in the buffy coat of whole blood is a new approach to the leukoagglutination technique. Not only is this procedure simpler, it produces consistent replicates and the results are reproducible. One of its features is the lack of cell manipulation. Buffy coat leukoagglutination (BCLA) can be induced by the addition of a variety of antigens, lectins or allogeneic sera to small samples of whole blood. It is an indicator of both cell-mediated immune responses and humoral anti-leukocyte activity. The occurrence of two morphologically distinct types of clumping also reflects this duality of the test. There is some evidence that BCLA may be a model for in vivo events.

Cell Count↗

PubMed1979

The evolution of an immune system.

A model for the molecular evolution of an imune system is presented. It suggests how a system of cell surface-fixed antigen receptors, called FR, to be thought of as "primitive" but still functional antibodies, could evolve into the "modern" labile T cell and antibody system, the receptors for which may be called CER (clonal expansion receptors). Perhaps the most significant insight to be gained from the theory concerns the conclusion that the immune system of an embryo may be primed by the interaction between two types of cells with complementary surface specificities. In the first type of cell the interacting molecule is an FR molecule coded by a gene of the Major Histocompatibility Complex (MHC) which has undergone a somatic mutation; in the second type it is a CER molecule also coded by a gene which has undergone a recent somatic mutation. It is believed that this insight eliminates some of the problems experienced in understanding generation of diversity, and renders unnecessary some of the more complex hypotheses about immune networks. The mechanism of action of immune response genes is easily explained by the theory.

Adaptation, Physiological↗

PubMed1977