Seasonal onset of systemic-onset juvenile rheumatoid arthritis.

OBJECTIVE: This study was undertaken to investigate the recent finding of a seasonal difference in the onset of systemic-onset juvenile rheumatoid arthritis (SoJRA). We hypothesized that a seasonal onset pattern might implicate on infectious agent as a cause of SoJRA. METHODS: The date of onset was collected from the records of all patients with SoJRA from 1980 to 1992 at presentation to pediatric rheumatology clinics across Canada. The onset pattern of SoJRA was then compared with incidence data on viral infections obtained for the same period. RESULTS: Across Canada the onset of SoJRA was constant across the seasons. However, in the Prairie region there was a statistically significant seasonal pattern, with peaks in autumn and early spring. We could find no evidence that viral incidence correlated with disease incidence either throughout Canada or in the Prairie region. CONCLUSIONS: If a seasonal infectious agent causes SoJRA, then it is likely only one of several causes and may act only in certain regions. Future studies should be carried out in those areas where SoJRA does have a seasonal onset pattern.

Potassium extrusion by the moderately halophilic and alkaliphilic methanogen methanolobus taylorii GS-16 and homeostasis of cytosolic pH.

Methanolobus taylorii GS-16, a moderately halophilic and alkaliphilic methanogen, grows over a wide pH range, from 6.8 to 9.0. Cells suspended in medium with a pH above 8.2 reversed their transmembrane pH gradient (delta pH), making their cytosol more acidic than the medium. The decreased energy in the proton motive force due to the reversed delta pH was partly compensated by an increased electric membrane potential (delta psi). The cytosolic acidification by M. taylorii at alkaline pH values was accompanied by K+ extrusion. The cytosolic K+ concentration was 110 mM in cells suspended at pH 8.7, but it was 320 mM in cells suspended at neutral pH values. High external K+ concentrations (210 mM or higher) inhibited the growth of M. taylorii at alkaline pH values, perhaps by preventing K+ extrusion. Cells suspended at pH 8.5 and 300 mM external K+ failed to acidify their cytosol. The key observation indicative of the involvement of K+ transport in cytosolic acidification was that valinomycin (0.8 microM), a K+ uniporter, inhibited the growth of M. taylorii only at alkaline pH values. Experiments with resting cells indicated that at alkaline pH values valinomycin uncoupled catabolic reactions from ATP synthesis. Thus, K+/H+ antiport activity was proposed to account for the K+ extrusion and the uncoupling effect of valinomycin at alkaline pH values. Such antiport activity was demonstrated by the sharp drop in pH of the bulk medium of the cell suspension upon the addition of 0.1 M KCl. The antiporter appeared to be active only at alkaline pH values, which was in accordance with a possible role in pH homeostasis by M. taylorii growing at alkaline pH values.

Disaggregation of Methanosarcina spp. and Growth as Single Cells at Elevated Osmolarity.

The effect of medium osmolarity on the morphology and growth of Methanosarcina barkeri, Methanosarcina thermophila, Methanosarcina mazei, Methanosarcina vacuolata, and Methanosarcina acetivorans was examined. Each strain was adapted for growth in NaCl concentrations ranging from 0.05 to 1.0 M. Methanosarcina spp. isolated from both marine and nonmarine sources exhibited similar growth characteristics at all NaCl concentrations tested, demonstrating that these species are capable of adapting to a similar range of medium osmolarities. Concomitant with the adaptation in 0.4 to 1.0 M NaCl, all strains disaggregated and grew as single cells rather than in the characteristic multicellular aggregates. Aggregated cells had a methanochondroitin outer layer, while disaggregated single cells lacked the outer layer but retained the protein S-layer adjacent to the cell membrane. Synthesis of glucuronic acid, a major component of methanochondroitin, was reduced 20-fold in the single-cell form of M. barkeri when compared with synthesis in aggregated cells. Strains with the methanochondroitin outer cell layer exhibited enhanced stability at low (<0.2 M NaCl) osmolarity and grew at higher temperatures. Disaggregated cells could be converted back to aggregated cells by gradually readapting cultures to lower NaCl (<0.2 M) and Mg (<0.005 M) concentrations. Disaggregated Methanosarcina spp. could also be colonized and replica plated with greater than 95% recovery rates on solidified agar basal medium that contained 0.4 to 0.6 M NaCl and either trimethylamine, methanol, or acetate as the substrate. The ability to disaggregate and grow Methanosarcina spp. as viable, detergent-sensitive, single cells on agar medium makes these species amenable to mutant selection and screening for genetic studies and enables cells to be gently lysed for the isolation of intact genetic material.

Acanthamoeba keratitis in Tennessee: a growing problem in patients wearing contact lenses.

All physicians evaluating a painful red eye in a contact lens wearer should consider the diagnosis of Acanthamoeba keratitis. Although it remains relatively rare, the incidence of this infection is on the rise. Clues to the correct diagnosis include a corneal abrasion that fails to heal appropriately, pain out of proportion to the clinical findings, and a history of poor contact lens hygiene. Prompt recognition and appropriate ophthalmologic intervention can improve the visual outcome for patients with this devastating corneal infection.

Effects of Hydrogen Pressure during Growth and Effects of Pregrowth with Hydrogen on Acetate Degradation by Methanosarcina Species.

Methanosarcina barkeri 227 and Methanosarcina mazei S-6 grew with acetate as the substrate; we found little effect of H(2) on the rate of aceticlastic growth in the presence of various H(2) pressures between 2 and 810 Pa. We used physical (H(2) addition or flushing the headspace to remove H(2)) and biological (H(2)-producing or -utilizing bacteria in cocultures) methods for controlling H(2) pressure in Methanosarcina cultures growing on acetate. Added H(2) (ca. 100 Pa) was removed rapidly (a few hours) by M. barkeri and slowly (within a day) by M. mazei. When the H(2) produced by the aceticlastic methanogens was removed by coculturing with an H(2)-using Desulfovibrio sp., the H(2) pressure was about 2.2 Pa. Under these conditions the stoichiometry of aceticlastic methanogenesis did not change. H(2)-grown inocula of M. barkeri grew with acetate as the sole catabolic substrate if the inoculum culture was transferred during logarithmic growth to acetate-containing medium or if the transfer was accomplished within 1 or 2 days after exhaustion of H(2). H(2)-grown cultures incubated for 4 or more days after exhaustion of H(2) were able to grow with H(2) but not with acetate as the sole catabolic substrate. Addition of small quantities of H(2) to acetate-containing medium permitted these cultures to initiate growth on acetate.

The risk of iridocyclitis in juvenile rheumatoid arthritis.

A retrospective study comparing 14 patients with juvenile rheumatoid arthritis (JRA) complicated by chronic iridocyclitis (Group I) with an equal number of JRA patients without this complication (Group II) was conducted to determine which factors might aid in the earlier diagnosis of chronic iridocyclitis. Eleven patients in Group I had oligoarticular disease compared to 5 in Group II. Antinuclear antibody was found in 13 patients in Group I compared to only 2 in Group II. Only one of nine patients tested in Group I for the histocompatibility antigen W-27 was positive. The patient with oligoarticular disease and a positive ANA test should be followed closely by the ophthalmologist for the development of chronic iridocyclitis.

The Battered Child-Family Physician's Role.

The physician's role in the management of the battered child is first one of diagnosis and protection before a child is seriously injured, followed by health and social assistance to the family. Our ultimate hope is to be able to anticipate such breakdowns in a parent or guardian before they lead to physical or emotional injury in a child. Close liaison between medical and social workers is essential.