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J J Hogan

Publications and source records attributed to J J Hogan.

7 recordsLinked to original sources
PubMed1998

Tumor expression studies indicate that HEM-1 is unlikely to be the active factor in oncogenic osteomalacia.

HEM-1 was isolated as a putative factor responsible for oncogenic osteomalacia by Kumar et al. (Proc Assoc Am Phys 107:296-305; 1995). The cDNA was identified on the basis of PTH-like immunoreactivity; however, no studies have been reported of the expression of HEM-1 mRNA in oncogenic osteomalacia tumors. In this study, expression of HEM-1 mRNA was investigated in two oncogenic osteomalacia tumors and in a series of normal tissues. An HEM-1 PCR product was amplified from a cDNA library from one of the tumors, with six base changes identified, as compared with the published sequence. No expression was detected, however, in the oncogenic osteomalacia tumors either by Northern blot analysis or by reverse transcriptase PCR. This indicates that, although a region of HEM-1 sequence is present in the tumor cell cDNA library, any HEM-1 expression must be at very low levels. It is unlikely, therefore, that the HEM-1 product is the active factor responsible for oncogenic osteomalacia. In the normal tissues examined, human placenta, fibroblasts, parathyroid gland, liver, fetal bone, and rat kidney cortex, HEM-1 mRNA was not detected, suggesting that it does not have a physiological role in these tissues.

Adenocarcinoma↗
PubMed1994

Platelet bacterial contamination and the use of a chemiluminescence-linked universal bacterial ribosomal RNA gene probe.

BACKGROUND: Currently, the maximum outdate for platelets is 5 days, because of the increasing chance of bacterial growth over time. Various methods for rapid detection of bacterial contamination of blood components have been described, with mixed results and no general acceptance. A recently described, molecular biologic approach for the detection of bacterial contamination involves a chemiluminescence-linked universal DNA bacterial probe to a highly conserved bacterial region of ribosomal RNA (rRNA). STUDY DESIGN AND METHODS: A multicenter trial of a chemiluminescence-linked universal bacterial rRNA probe for the detection of bacterial contamination in platelet concentrates is described. At each of five sites, platelet concentrates (no older than 1 day from date of phlebotomy) were inoculated in triplicate with isolates of four bacterial species (Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus epidermidis, and Staphylococcus aureus) to a final concentration of 10 to 50 colony-forming units (CFUs) per mL and in triplicate to a final concentration of 1000 CFUs per mL. At one site, an additional 6 platelet concentrates were inoculated with sterile saline to serve as controls. Inoculated units were then subjected periodically to quantitative cultures and probe analyses. A total of 126 platelet concentrates were studied over a period of 7 days (120 inoculated with bacteria and 6 with sterile saline). RESULTS: This assay was, in some cases, able to detect S. aureus bacterial contamination in the range of 100 to 1000 CFUs per mL; the majority of samples (B. cereus, P. aeruginosa, S. aureus, and S. epidermidis) with contamination exceeding 10(4) CFUs per mL; and all samples with contamination of 2.1 x 10(5) CFUs per mL or greater. Increasing the sample size from the recommended 0.4 mL to 1.0 mL resulted in an unacceptable loss of specificity (83.3%). CONCLUSION: The routine use of this assay would be expected to result in a decreased risk of septic platelet transfusion reactions and could lead to a lengthening of the current 5 day storage period for platelets. Further, the pooling of random-donor platelet concentrates before storage instead of immediately before transfusion may be possible if this rRNA probe is employed to detect bacteria in the pool.

Bacillus cereus↗
PubMed1984

Probing the conformation of 18S rRNA in yeast 40S ribosomal subunits with kethoxal.

Yeast 40S ribosomal subunits have been reacted with kethoxal to probe the conformation of 18S rRNA. Over 130 oligonucleotides were isolated by diagonal electrophoresis and sequenced, allowing identification of 48 kethoxal-reactive sites in the 18S rRNA chain. These results generally support a secondary structure model for 18S rRNA derived from comparative sequence analysis. Significant reactivity at positions 1436 and 1439, in a region shown to be base paired by comparative analysis, lends support to the earlier suggestion [Chapman, N.M., & Noller, H.F. (1977) J. Mol. Biol 109, 131-149] that part of the 3'-major domain of 16S-like rRNAs may undergo a biologically significant conformational rearrangement. Modification of positions in 18S rRNA analogous to those previously found for Escherichia coli 16S rRNA argues for extensive structural homology between 30S and 40S ribosomal subunits, particularly in regions thought to be directly involved in translation.

Aldehydes↗
PubMed1984

Probing the conformation of 26S rRNA in yeast 60S ribosomal subunits with kethoxal.

The conformation and accessibility of 26S rRNA in yeast 60S ribosomal subunits were probed with kethoxal. Oligonucleotides originating from reactive sites were isolated by diagonal electrophoresis and sequenced. From over 70 oligonucleotide sequences, 26 kethoxal-reactive sites could be placed in the 26S rRNA sequence. These are in close agreement with a proposed secondary structure model for the RNA that is based on comparative sequence analysis. At least seven kethoxal-reactive sites in yeast 26S rRNA are in positions that are exactly homologous to reactive positions in E. coli 23S rRNA; each of these sites has previously been implicated in some aspect of ribosomal function.

Aldehydes↗
PubMed1980

Secondary structure model for bacterial 16S ribosomal RNA: phylogenetic, enzymatic and chemical evidence.

We have derived a secondary structure model for 16S ribosomal RNA on the basis of comparative sequence analysis, chemical modification studies and nuclease susceptibility data. Nucleotide sequences of the E. coli and B. brevis 16S rRNA chains, and of RNAse T1 oligomer catalogs from 16S rRNAs of over 100 species of eubacteria were used for phylogenetic comparison. Chemical modification of G by glyoxal, A by m-chloroperbenzoic acid and C by bisulfite in naked 16S rRNA, and G by kethoxal in active and inactive 30S ribosomal subunits was taken as an indication of single stranded structure. Further support for the structure was obtained from susceptibility to RNases A and T1. These three approaches are in excellent agreement. The structure contains fifty helical elements organized into four major domains, in which 46 percent of the nucleotides of 16S rRNA are involved in base pairing. Phylogenetic comparison shows that highly conserved sequences are found principally in unpaired regions of the molecule. No knots are created by the structure.

Bacillus↗
PubMed1978

Altered topography of 16S RNA in the inactive form of Escherichia coli 30S ribosomal subunits.

We have studied the topography of 16S RNA in the inactive form of the 30S ribosomal subunit (Ginsburg, I., et al. (1973) J. Mol. Biol. 79, 481), using the guanine-specific reagent kethoxal. Oligonucleotides surrounding reactive guanine residues were isolated and quantitated by means of diagonal electrophoresis and sequenced. Comparison of these results with experiments on active or reactivated subunits reveals the following: (1) Most of the sites which are reactive in active 30S subunits are much more reactive (average 13-fold) in inactive subunits. Upon reactivation, these sites return to a less reactive state. Thus, a reversible increase in accessibility of specific 16S RNA sites parallels the reversible loss of protein synthesis activity of 30S subunits. (2) The number of kethoxal-reactive sites in inactive subunits is about twice that of active subunits. The nucleotide sequences and locations of the additional accessible sites in inactive subunits have been determined. (3) Sites that can be located in the 16S RNA sequence are distributed throughout the RNA chain in inactive subunits, in contrast to the clustering observed in active subunits. (4) The sites of kethoxal substitution are single stranded. Yet, of the 30 sites that can be located, 23 were predicted to be base paired in the proposed secondary structure model for 16S RNA (Ehresmann, C., et al. (1975), Nucleic Acids Res. 2, 265).

Base Sequence↗