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Objective. To investigate a high prevalence of systemic sclerosis (SSc; scleroderma) in a well-defined population of 21,255 Choctaw Indians residing in 8 southeastern Oklahoma counties who were "users" of Indian Health Services.Methods. A case-control study of 12 SSc cases and 48 matched non-SSc controls (4 per case) was conducted to investigate potential occupational, residential, and infectious exposures, as well as genetic factors which might predispose to SSc. HLA class I1 alleles were determined by DNA oligotyping, and class I and 111 alleles were defined serologically.Results. The prevalence of SSc in full-blooded Choctaws was at least 8/1,704, or 469/100,000 (95% confidence interval 195% CI] 203-930) over the 4-year interval 1990-1994 and was significantly higher than that among non-full-blooded Choctaws (6/19,551, or 31/100,000) (P = 0.00001, odds ratio [OR] = 15.4, 95% CI 4.9-49.8). The overall prevalence of SSc in Oklahoma Choctaws (66/100,000) also was significantly higher than that in other Native Americans in Oklahoma (9.5/100,000) (P = OR = 6.95, 95% CI Supported by granls from the Sclerodcrma Federation/ United Sclerodcrma Foundation, and the RGK Foundation.

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Developing sea turtle embryos only successfully hatch within a relatively narrow temperature range, rendering this immobile life stage vulnerable to the vagaries of climate change. To accurately predict the potential impact of climate change on sea turtle egg mortality, we need to fully understand the thermal tolerance of developing embryos. We reviewed the literature on this topic, and found that published studies interpret the primary literature and subsequent reviews very differently. Based on early literature reviews, the maximum thermal tolerance of sea turtle embryos is frequently cited as either 33 or 35°C. In many sea turtle populations, however, nest temperatures often exceed 35°C by up to several degrees (usually just prior to hatchling emergence) and eggs still hatch successfully. Mean incubation temperatures up to 35°C generally produce hatchlings, although leatherback and olive ridley turtle embryos may be less tolerant of high incubation temperatures than green and loggerhead turtle embryos. Sea turtle embryos are likely to be more sensitive to the duration of time spent at potentially stressful temperatures than to the temperature alone. To complicate matters, developing embryos may change their thermal tolerance as they grow. Overall, we are only beginning to understand how exposure to high temperatures experienced in the field influences embryonic development and hatchling production. This knowledge gap is hampering our ability to predict the impacts of climate change on sea turtle populations, and future work should focus on understanding how temperature and other climatic variables influence embryonic development and, thus, crucial population attributes such as hatchling production.

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Objective. To investigate the effect of ethnicity on clinical and serologic expression in patients with systemic sclerosis (SSc) and anti-DNA topoisomerase I (anti-topo I) antibody.Methods. Clinical and serologic features, as well as HLA class II allele frequencies, were compared among 47 North American white, 15 North American black, 43 Japanese, and 12 Choctaw Native American SSc patients with anti-topo I antibody.Results. The frequency of progressive pulmonary interstitial fibrosis was lower, and cumulative survival rates were better in white compared with black and Japanese patients. Sera of white and black patients frequently recognized the portion adjacent to the carboxyl terminus of topo I, sera of Japanese patients preferentially recognized the portion adjacent to the amino terminus of topo I, and sera of Choctaw patients recognized both portions of topo I. Anti-RNA polymerase II and anti-SSA/Ro antibodies were present together with anti-topo I antibody more frequently in sera of Japanese patients than in sera of white patients. The HLA-DRB1 alleles associated with anti-topo I antibody differed; i.e., DRB1*1101-*1104 in whites and blacks, DRB1*1502 in Japanese, and DRB1*1602 in Choctaws.Multivariate analysis showed that ethnic background was an independent determinant affecting development of severe lung disease as well as survival.Conclusion. Clinical and serologic features in SSc patients were strongly influenced by ethnic background. The variability of disease expression in the 4 ethnic groups suggests that multiple factors linked to ethnicity, including genetic and environmental factors, modulate clinical manifestations, disease course, and autoantibody status in SSc.

A method is presented for obtaining information about the unresolved filamentary structure of solar magnetic fields. A comparison is made of pairs of Mount Wilson magnetograph recordings made in the two spectral lines Fel 5250/~ and FeI 5233/~ obtained on 26 different days. Due to line weakenings and saturation in the magnetic filaments, the apparent field strengths measured in the 5250/~ line are too low, while the 5233 Ik line is expected to give essentially correct results. From a comparison between the apparent field strengths and fluxes and their center to limb variations, we draw the following tentative conclusions: (a) More than 90 % of the total flux seen with a 17 by 17 arc sec magnetograph aperture is channeled through narrow filaments with very high field strengths in plages and at the boundaries of supergranular cells. (b) An upper limit for the interfilamentary field strength integrated over the same aperture seems to be about 3 G. (c) The field lines in a filament are confined in a very small region in the photosphere but spread out very rapidly higher up in the atmosphere. (d) All earlier Mount Wilson magnetograph data should be multiplied by a factor that is about 1.8 at the center of the disk and decreased toward the limb in order to give the correct value of the longitudinal magnetic field averaged over the scanning aperture.