Biomedical subjects
Publications and source records attributed to J W Logan.
A multiple-quantum magic angle spinning (MQMAS) NMR experiment of quadrupolar nuclei is demonstrated, which uses two different multiple quantum coherences in t(1) to refocus the quadrupolar broadening. This experiment has the potential of achieving improved resolution over current techniques.
Raynaud's phenomenon, digital ischemia, antinuclear antibodies and anticardiolipin antibodies are uncommon features of malignancy. The association of all of these in a patient with malignancy has not previously been reported. We describe a 52 year old woman with non small-cell carcinoma of the lung who also had Raynaud's phenomenon, digital ischemia, anti-nuclear antibodies and anticardiolipin antibodies.
The transport of gases in porous materials is a crucial component of many important processes in science and technology. In the present work, we demonstrate how magnetic resonance microscopy with continuous flow laser-polarized noble gases makes it possible to "light up" and thereby visualize, with unprecedented sensitivity and resolution, the dynamics of gases in samples of silica aerogels and zeolite molecular sieve particles. The "polarization-weighted" images of gas transport in aerogel fragments are correlated to the diffusion coefficient of xenon obtained from NMR pulsed-field gradient experiments. The technique provides a unique means of studying the combined effects of flow and diffusion in systems with macroscopic dimensions and microscopic internal pore structure.
This study investigated whether methotrexate, by interrupting the methyl transfer function of folate, can induce genomic DNA hypomethylation in patients with inflammatory arthritis. Consecutive subjects with inflammatory arthritis (rheumatoid or psoriatic), who were taking methotrexate (n = 7) or other medications (n = 6), and control subjects, either healthy or with osteoarthritis and taking nonsteroidal anti-inflammatory agents only (n = 9) were recruited. The methylation status of genomic DNA from peripheral blood mononuclear cells was determined. Plasma levels of folate, B12, and pyridoxal-5'-phosphate (PLP), all of which are involved in biologic methylation, were also examined. The extent of genomic DNA methylation was lowest in subjects with inflammatory arthritis who were not taking methotrexate, highest in subjects with inflammatory arthritis who were taking methotrexate, and intermediate in control subjects (p < 0.05). Plasma levels of folate and B12 were similar among the three groups. The mean plasma PLP level in subjects with inflammatory arthritis was 33% lower than that in control subjects (p = 0.04). No significant correlation between genomic DNA methylation and folate, B12, and PLP levels was observed. These data do not support the hypothesis that methotrexate induces genomic DNA hypomethylation. However, these data indicate that inflammatory arthritis is associated with genomic DNA hypomethylation that is reversed with methotrexate. Future studies using a larger number of subjects are warranted to confirm these findings.
Borrelia burgdorferi, the causative agent of Lyme disease, is a potent inducer of interleukin-1 beta (IL-1 beta), a cytokine implicated in the pathogenesis of inflammatory arthritis. The balance between IL-1 and the IL-1 receptor antagonist (IL-1ra), a naturally occurring inhibitor of IL-1, might influence disease expression. To explore this possibility, we have done a retrospective study that compared the clinical course of Lyme arthritis in 83 patients with concentrations of IL-1 beta and IL-1ra in the patients' synovial fluid. Patients with high concentrations of IL-1ra and low concentrations of IL-1 beta had rapid resolution of attacks of arthritis, whereas patients with the reverse pattern of cytokine concentrations had long intervals to recovery. Thus, the balance between synovial fluid IL-1 beta and IL-1ra concentrations relates to the time to recovery from an episode of Lyme arthritis.
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The prevalence of Schistosomiasis and the distribution of the snail intermediate hosts on three adjoining irrigated estates in the lowveld of Swaziland was investigated. The prevalence rates of Schistosoma haematobium and S. mansoni among estate employees was lower than anticipated and there was a marked difference between the prevalence rates of S. mansoni between estates. The reasons for this and the influence of water supplies and agricultural practice on the prevalence of schistosomiasis are discussed.
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