Sulfur isotopes as a proxy for human diet and mobility from the preclassic through colonial periods in the Eastern Maya lowlands

Maya archaeologists have long been interested in understanding ancient diets because they provide information about broad-scale economic and societal transformations. Though paleodietary studies have primarily relied on stable carbon (δ13C) and nitrogen (δ15N) isotopic analyses of human bone collagen to document the types of food people consumed, stable sulfur (δ34S) isotope analysis can potentially provide valuable data to identify terrestrial, freshwater, or marine/coastal food sources, as well as determine human mobility and migration patterns. Here we assess applications of δ34S for investigating Maya diet and migration through stable isotope analyses of human bone collagen (δ13C, δ15N, and δ34S) from 114 individuals from 12 sites in the Eastern Maya lowlands, temporally spanning from the Late Preclassic (300 BCE-300 CE) through Colonial periods (1520-1800 CE). Results document a diet dominated by maize and other terrestrial resources, consistent with expectations for this inland region. Because δ34S values reflect local geology, our analyses also identified recent migrants to the Eastern lowlands who had non-local δ34S signatures. When combined with other indicators of mobility (e.g., strontium isotopes), sulfur isotopic data provide a powerful tool to investigate movement across a person's lifespan. This study represents the largest examination of archaeological human δ34S isotope values for the Maya lowlands and provides a foundation for novel insights into both subsistence practices and migration.

Urinary albumin excretion in patients with systemic lupus erythematosus without renal disease

OBJECTIVES

To investigate the prevalence of microalbuminuria, urinary albumin excretion (UAE) between 20-200 micrograms/min, in systemic lupus erythematosus (SLE) patients without clinical renal disease, and to discover if this could predict the development of renal disease.

METHODS

This study made six monthly measurements of UAE, creatinine clearance, serological and clinical data in 22 ambulatory women patients with SLE, without clinical renal disease, hypertension, diabetes or heart failure. The patients were followed up for a period of 18 months (four measurements). Age and sex matched healthy controls were used as a comparative group. UAE was measured by nephelometry in three timed overnight urine samples at each visit.

RESULTS

There were no significant differences in the creatinine clearance between the control group and the SLE patients. Creatinine clearance did not show significant changes throughout the study period. SLE patients had wide variations in the UAE rate compared with healthy controls. In five patients (5 of 22; 23%), on occasions, there was mild, transient increase in UAE reaching the level of microalbuminuria. During follow up, one patient with basal (4.67 micrograms/min) and six month (4.73 micrograms/min) normal UAE rate, was admitted with a nephrotic syndrome confirmed on biopsy examination to be proliferative lupus nephritis. Six months after beginning treatment with prednisone and cyclophosphamide her UAE rate returned to normal values (4.65 micrograms/min).

CONCLUSION

SLE patients without clinical renal disease may have microalbuminuria, although this does not seem to warrant any specific action.