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J Bacon

Publications and source records attributed to J Bacon.

13 recordsLinked to original sources
PubMed1991

A new qualitative variant of the RhE antigen revealed by heterogeneity among anti-E sera.

We have recently detected a new qualitative variant of the RhE antigen characterised by negative reactions with a minority of anti-E sera, and an inability of the relevant cells to completely absorb most, if not all, anti-E samples that we tested. In tube tests, using a two-stage enzyme technique, cells from the proposita (V.R.) were completely agglutinated by 8 out of 12 undiluted polyclonal sera, weakly agglutinated (2+ and 3+ reactions) by 2 sera, but not agglutinated by the 2 remaining sera. Cross-absorption tests using 1 non-reacting, 1 weakly reacting and 4 strongly reacting polyclonal anti-E sera showed that V.R.'s cells only slightly reduced their anti-E titres versus r"r cells, whilst completely removing their reactivity against her own cells. Absorptions with R2R2 cells abolished activity against both cell types. The cells of V.R. failed to absorb or elute anti-Ew, and had normal expression of c. Three monoclonal human anti-E reagents were tested by fluorescence flow cytometry; one reagent failed to react with the cells of V.R., a second bound as strongly with V.R.'s cells as with R1R2 controls while the third bound much more weakly with V.R. than with any other E+ sample. The variant of RhE in the V.R. family is therefore distinct from Ew, and lacks an epitope recognised by a major constituent of most anti-E sera. This epitope is unlikely to be ET, since all of 91 samples from E-positive Australian aborigines (many of which are expected to lack ET) were agglutinated by a serum that failed to react with V.R.'s cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗
PubMed1989

Human pepsinogen C (progastricsin) polymorphism: evidence for a single locus located at 6p21.1-pter.

A series of six clones containing the entire human pepsinogen C gene (PGC) was identified in a cosmid vector library by using cDNA and oligonucleotide probes. The 10.7-kb PGC gene includes nine exons and exhibits a high degree of sequence identity (60%) with the functionally related pepsinogen A genes. The predicted amino acid sequence was identical with the partial amino-terminal and carboxyl-terminal sequences of purified pepsinogen C. An informative restriction fragment length polymorphism was detected with several restriction enzymes and involved an insertion or deletion of 100 bp of intron sequence located between exons 7 and 8. Evidence that there is only a single PGC gene in humans is presented. The PGC gene and the prolactin gene were regionally localized to 6p21.1-pter by analysis of mouse X human somatic cell hybrids.

Amino Acid Sequence↗
PubMed1989

Further characterization of a bacteriophage recovered from an avian strain of Chlamydia psittaci.

The genome of a 22 nm icosahedral phage which infects some avian Chlamydia psittaci strains recovered from domestic ducks has been characterized as a ss circular DNA molecule of about 4850 bases. The replicative form of this genome was isolated from purified chlamydial organisms. A restriction endonuclease cleavage site map of the genome was constructed from dsDNA synthesized in vitro from ss phage DNA and EcoRI fragments were then cloned into pUC9. The phage genome was detected only by Southern blot hybridization in C. psittaci which was productively infected with phage; no evidence was found for the integration of phage DNA into the chlamydial chromosome. Three viral polypeptides, of approximate Mr values 75K, 30K and 16.5K were identified when phage was analysed by SDS-PAGE. This virus, which we have designated Chp 1, is either an aberrant member of the Microviridae or the first member of a new bacteriophage family.

Animals↗
PubMed1989

A family exhibiting the cis-AB genotype.

Studies on blood samples from a 30-year-old woman of Korean origin, her husband and children, showed the presence of the cis-AB genotype in the mother and one child. The cis-AB red cells showed abnormal reactions with both polyclonal and monoclonal anti-B reagents and an elevated level of H antigen. The serum contained weak anti-B that reacted with normal B antigen but not with that on cis-AB cells. Normal levels of A substance but reduced levels of B and H substances were present in the saliva. Conversely, the serum showed reduced A and normal B and H blood group transferase activity.

ABO Blood-Group System↗
PubMed1986

Developmental differences in part/whole identification.

At issue in the present research was whether or not preschoolers are able to simultaneously perceive multiple aspects of an object. This issue was examined in 2 experiments in which 3-5-year-olds were asked to describe part/whole pictures (e.g., a "house made of crayons"). Prior developmental research has suggested that preschoolers typically fail to name both part and whole aspects of such pictures. In the present study, parts and wholes ranged from relatively "simple" to relatively "difficult" for preschoolers to identify and label. The results showed that even 3-year-olds frequently named both part and whole aspects of our "simple" pictures but were significantly less likely to name both aspects of more "difficult" pictures. Overall, the results suggest that multiple-aspect perception is available as early as 3 years of age, and that preschoolers' failure in previous studies to explicitly identify both part and whole aspects of the same object may reflect failure in verbal or metacognitive skills rather than in children's ability to perceive multiple aspects of an object.

Child Development↗
PubMed1981

Controlled studies of intranasal immunotherapy for ragweed pollenosis.

During 1978 a double blind study compared the efficacy of preseasonal short ragweed (RW) extract intranasal immunotherapy with a histamine placebo; in 1979 more prolonged treatment with a larger dose of polymerized ragweed (PRW) was evaluated. In neither year did the placebo-treated patients show significantly more severe disease as assessed by daily symptom diaries, examination in season, comparison of overall symptom severity with previous years or changes in nasal challenge tests. Following treatment in 1979 there was a significantly greater amount of secretory IgA and IgG ragweed antibodies secreted by the nose of the PRW-treated group, but these titers did not correlate with clinical results.

Administration, Intranasal↗
PubMed1977

The detection of line segments.

Many simple cells of the visual cortex have long narrow receptive fields, which are strongly excited by lines oriented along their long axis. In the present psychophysical analysis, we assume that there are similar independent 'subunits' which contribute, by probability summation, to the detection of a line. If a line segment is shorter than the subunit length, then extending the line length will increase the sensitivity of all the subunits affected by the line, and a relatively large increase in visual sensitivity will occur, corresponding to this 'physiological summation' within subunits. However, for a line segment which is much longer than the subunit length, the main effect of extending line length is to stimulate more subunits, resulting in a relatively small increase in sensitivity owing to probability summation. Thus a study of sensitivity (reciprocal threshold) as a function of line length may be used to test the subunit model and to estimate the subunit length. Here we use a quantitative model to demonstrate that sensitivity/line length data may be well fitted, assuming independent subunits having a constant length of 8-6'--in good agreement with the length of Adrews' "ff" units.

Adult↗