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We possess rather little detailed information on the lives of the first inhabitants of Puerto Rico-the so-called "Archaic" or "Pre-Arawak" people-despite more than a century of archeological research. This is particularly true bioarchaeologically, as fewer than twenty burials of the several millennia of the Archaic Age have been recovered, let alone analyzed in any detail. Here, we present the results of archeological, osteological, radiometric, and isotopic analysis of five individuals from the Ortiz site in Cabo Rojo, southwestern Puerto Rico. Study of these previously unpublished remains, which represent a 20-25% increase in the sample size of remains attributed to the period, provides many critical insights into earliest Puerto Rican lifeways, including aspects of mortuary practice, paleodiet, and possibly even social organization. A review of their burial treatment finds a mostly standardized set of mortuary practices, a noteworthy finding given the site's potential millennium-long use as a mortuary space and the possibly distinct place(s) of origin of the individuals interred there. Although osteological analysis was limited by poor preservation, we were able to reconstruct aspects of the demography that indicate the presence of both male and female adults. Stable isotope analysis revealed dietary differences from later Ceramic Age individuals, while dental pathology indicated heavy masticatory wear attributable to diet and/or non-masticatory function. Perhaps most crucially, direct AMS dating of the remains confirms these as the oldest burials yet recovered from the island, providing us both with a glimpse into the lives of some of the island's first inhabitants, and with tantalizing clues to the existence of a different degree of cultural "complexity" than is often ascribed to these earliest peoples. The existence of what radiocarbon dates suggest may be a persistent formal cemetery space at the Ortiz site has potentially significant implications concerning the territoriality, mobility, and social organization of the earliest peoples of southwestern Puerto Rico., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Pestle et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

We describe, for the first time the use of hydrogel-forming microneedle (MN) arrays for minimally-invasive extraction and quantification of drug substances and glucose from skin in vitro and in vivo. MN prepared from aqueous blends of hydrolysed poly(methyl-vinylether-co-maleic anhydride) (11.1% w/w) and poly(ethyleneglycol) 10,000 daltons (5.6% w/w) and crosslinked by esterification swelled upon skin insertion by uptake of fluid. Post-removal, theophylline and caffeine were extracted from MN and determined using HPLC, with glucose quantified using a proprietary kit. In vitro studies using excised neonatal porcine skin bathed on the underside by physiologically-relevant analyte concentrations showed rapid (5 min) analyte uptake. For example, mean concentrations of 0.16 μg/mL and 0.85 μg/mL, respectively, were detected for the lowest (5 μg/mL) and highest (35 μg/mL) Franz cell concentrations of theophylline after 5 min insertion. A mean concentration of 0.10 μg/mL was obtained by extraction of MN inserted for 5 min into skin bathed with 5 μg/mL caffeine, while the mean concentration obtained by extraction of MN inserted into skin bathed with 15 μg/mL caffeine was 0.33 μg/mL. The mean detected glucose concentration after 5 min insertion into skin bathed with 4 mmol/L was 19.46 nmol/L. The highest theophylline concentration detected following extraction from a hydrogel-forming MN inserted for 1 h into the skin of a rat dosed orally with 10 mg/kg was of 0.363 μg/mL, whilst a maximum concentration of 0.063 μg/mL was detected following extraction from a MN inserted for 1 h into the skin of a rat dosed with 5 mg/kg theophylline. In human volunteers, the highest mean concentration of caffeine detected using MN was 91.31 μg/mL over the period from 1 to 2 h post-consumption of 100 mg Proplus® tablets. The highest mean blood glucose level was 7.89 nmol/L detected 1 h following ingestion of 75 g of glucose, while the highest mean glucose concentration extracted from MN was 4.29 nmol/L, detected after 3 hours skin insertion in human volunteers. Whilst not directly correlated, concentrations extracted from MN were clearly indicative of trends in blood in both rats and human volunteers. This work strongly illustrates the potential of hydrogel-forming MN in minimally-invasive patient monitoring and diagnosis. Further studies are now ongoing to reduce clinical insertion times and develop mathematical algorithms enabling determination of blood levels directly from MN measurements.