University of Puerto Rico, Medical Sciences Campus

About: University of Puerto Rico, Medical Sciences Campus is a education organization based out in San Juan, Puerto Rico, United States. It is known for research contribution in the topics: Population & Medicine. The organization has 1711 authors who have published 1496 publications receiving 27756 citations.

Solution Structure of the Tandem Acyl Carrier Protein Domains from a Polyunsaturated Fatty Acid Synthase Reveals Beads-on-a-String Configuration

Abstract: The polyunsaturated fatty acid (PUFA) synthases from deep-sea bacteria invariably contain multiple acyl carrier protein (ACP) domains in tandem. This conserved tandem arrangement has been implicated in both amplification of fatty acid production (additive effect) and in structural stabilization of the multidomain protein (synergistic effect). While the more accepted model is one in which domains act independently, recent reports suggest that ACP domains may form higher oligomers. Elucidating the three-dimensional structure of tandem arrangements may therefore give important insights into the functional relevance of these structures, and hence guide bioengineering strategies. In an effort to elucidate the three-dimensional structure of tandem repeats from deep-sea anaerobic bacteria, we have expressed and purified a fragment consisting of five tandem ACP domains from the PUFA synthase from Photobacterium profundum. Analysis of the tandem ACP fragment by analytical gel filtration chromatography showed a retention time suggestive of a multimeric protein. However, small angle X-ray scattering (SAXS) revealed that the multi-ACP fragment is an elongated monomer which does not form a globular unit. Stokes radii calculated from atomic monomeric SAXS models were comparable to those measured by analytical gel filtration chromatography, showing that in the gel filtration experiment, the molecular weight was overestimated due to the elongated protein shape. Thermal denaturation monitored by circular dichroism showed that unfolding of the tandem construct was not cooperative, and that the tandem arrangement did not stabilize the protein. Taken together, these data are consistent with an elongated beads-on-a-string arrangement of the tandem ACP domains in PUFA synthases, and speak against synergistic biocatalytic effects promoted by quaternary structuring. Thus, it is possible to envision bioengineering strategies which simply involve the artificial linking of multiple ACP domains for increasing the yield of fatty acids in bacterial cultures.

Cross-sectional associations of impaired glucose metabolism measures with bleeding on probing and periodontitis.

Abstract: Aim This study assessed the associations of pre-diabetes and insulin resistance with bleeding on probing (BOP) and periodontitis among adults. Materials and methods We included 1191 Hispanic adults aged 40–65 years, free of diabetes, enrolled in San Juan Overweight Adults Longitudinal Study. Pre-diabetes was defined as impaired fasting glucose (IFG), impaired glucose tolerance (IGT), or impaired glycated haemoglobin. Impaired one-hour plasma glucose (1hPG) was defined as levels >155 mg/dl. Insulin resistance was defined using the study population-specific 75th percentile (HOMA-IR ≥ 3.13). High BOP was defined as percentage of teeth with bleeding ≥30%. Periodontitis was defined according to the CDC/AAP definition. Results After multivariable adjustment for age, gender, education, smoking status, alcohol consumption, physical activity, obesity, HDL-C, and plaque index, pre-diabetes with and without 1hPG, IFG, impaired 1hPG, IGT, and HOMA-IR were significantly associated with high BOP; pre-diabetes, IFG, and impaired 1hPG were significantly associated with severe periodontitis. Most of these associations remained significant when the analyses were restricted to non-smokers. Conclusions This study suggests associations between pre-diabetes and insulin resistance with BOP and periodontitis. Given the high prevalence of impaired glucose metabolism and periodontitis, the assessment of the temporal sequence of these associations is of utmost importance.

Tamoxifen Administration Immediately or 24 Hours after Spinal Cord Injury Improves Locomotor Recovery and Reduces Secondary Damage in Female Rats.

Abstract: Spinal cord injury (SCI) is a condition with no available cure. The initial physical impact triggers a cascade of molecular and cellular events that generate a nonpermissive environment for cell survival and axonal regeneration. Spinal cord injured patients often arrive at the clinic hours after the initial insult. This indicates the need to study and develop treatments with a long therapeutic window of action and multiactive properties, which target the complex set of events that arise after the initial trauma. We provide evidence that tamoxifen (TAM), a drug approved by the Food and Drug Administration, exerts neuroprotective effects in an animal model when applied up-to 24 h after SCI. We hypothesized that continuous TAM administration will improve functional locomotor recovery by favoring myelin preservation and reducing secondary damage after SCI. Adult female Sprague-Dawley rats (∼230 g) received a moderate contusion to the thoracic (T9–T10) spinal cord, using the MASCIS impactor device. To...

Conserved microbiota among young Heliconius butterfly species.

Abstract: Background Insects are the most diverse group of animals which have established intricate evolutionary interactions with bacteria. However, the importance of these interactions is still poorly understood. Few studies have focused on a closely related group of insect species, to test the similarities and differences between their microbiota. Heliconius butterflies are a charismatic recent insect radiation that evolved the unique ability to use pollen as a protein source, which affected life history traits and resulted in an elevated speciation rates. We hypothesize that different Heliconius butterflies sharing a similar trophic pollen niche, harbor a similar gut flora within species, population and sexes. Methods To test our hypothesis, we characterized the microbiota of 38 adult male and female butterflies representing six species of Heliconius butterflies and 2 populations of the same species. We sequenced the V4 region of the 16S rRNA gene with the Roche 454 system and analyzed the data with standard tools for microbiome analysis. Results Overall, we found a low microbial diversity with only 10 OTUs dominating across all individuals, mostly Proteobacteria and Firmicutes, which accounted for 99.5% of the bacterial reads. When rare reads were considered, we identified a total of 406 OTUs across our samples. We identified reads within Phyla Chlamydiae, found in 5 butterflies of four species. Interestingly, only three OTUs were shared among all 38 individuals (Bacillus, Enterococcus and Enterobacteriaceae). Altogether, the high individual variation overshadowed species and sex differences. Thus, bacterial communities were not structured randomly with 13% of beta-diversity explained by species, and 40 rare OTUs being significantly different across species. Finally, 13 OTUs, including the intercellular symbiont Spiroplasma, varied significantly in relative abundance between males and females. Discussion The Heliconius microbial communities in these 38 individuals show a low diversity with few differences in the rare microbes between females, males, species or populations. Indeed, Heliconius butterflies, similarly to other insects, are dominated by few OTUs, mainly from Proteobacteria and Firmicutes. The overall low microbial diversity observed contrasts with the high intra-species variation in microbiome composition. This could indicate that much of the microbiome maybe acquired from their surroundings. The significant differences between species and sexes were restricted to rare taxa, which could be important for microbial community stability under changing conditions as seen in other host-microbiome systems. The presence of symbionts like Spiroplasma or Chlamydiae, identified in this study for the first time in Heliconius, could play a vital role in their behavior and evolution by vertical transmission. Altogether, our study represents a step forward into the description of the microbial diversity in a charismatic group of closely related butterflies.

Shared decision making for stroke prevention in atrial fibrillation: study protocol for a randomized controlled trial

Abstract: Nonvalvular atrial fibrillation (AF) is a common ongoing health problem that places patients at risk of stroke. Whether and how a patient addresses this risk depends on each patient’s goals, context, and values. Consequently, leading cardiovascular societies recommend using shared decision making (SDM) to individualize antithrombotic treatment in patients with AF. The aim of this study is to assess the extent to which the Anticoagulation Choice conversation tool promotes high-quality SDM and influences anticoagulation uptake and adherence in patients with AF at risk of strokes. This study protocol describes a multicenter, encounter-level, randomized trial to assess the effect of using the Anticoagulation Choice conversation tool in the clinical encounter, compared to usual care. The participating centers include an academic hospital system, a suburban community group practice, and an urban safety net hospital, all in Minnesota, USA. Patients with ongoing nonvalvular AF at risk of strokes (CHA2DS2-VASc score ≥ 1 in men, or ≥ 2 in women) will be eligible for participation. We aim to include 999 patients and their clinicians. The primary outcome is the quality of SDM as perceived by participants, and as assessed by a post-encounter survey that ascertains (a) knowledge transfer, (b) concordance of the decision made, (c) quality of communication, and (d) satisfaction with the decision-making process. Recordings of encounters will be reviewed to assess the extent of patient involvement and how participants use the tool (fidelity). Anticoagulant use, choice of agent, and adherence will be drawn from patients’ medical and pharmacy records. Strokes and bleeding events will be drawn from patient records. This study will provide a valid and precise measure of the effect of the Anticoagulation Choice conversation tool on SDM quality and processes, and on the treatment choices and adherence to therapy among AF patients at risk of stroke. ClinicalTrials.gov, NCT02905032 . Registered on 9 September 2016.