Messenger RNAs (mRNAs) encode information in both their primary sequence and their higher order structure. The independent contributions of factors like codon usage and secondary structure to ...regulating protein expression are difficult to establish as they are often highly correlated in endogenous sequences. Here, we used 2 approaches, global inclusion of modified nucleotides and rational sequence design of exogenously delivered constructs, to understand the role of mRNA secondary structure independent from codon usage. Unexpectedly, highly expressed mRNAs contained a highly structured coding sequence (CDS). Modified nucleotides that stabilize mRNA secondary structure enabled high expression across a wide variety of primary sequences. Using a set of eGFP mRNAs with independently altered codon usage and CDS structure, we find that the structure of the CDS regulates protein expression through changes in functional mRNA half-life (i.e., mRNA being actively translated). This work highlights an underappreciated role of mRNA secondary structure in the regulation of mRNA stability.
If humans aim to sustainably coexist with wildlife, we must understand how our activity impacts the communication systems of urban animal populations. We know much about the effects of anthropogenic ...noise on bird song, but relatively little about how avian visual signals are affected by urbanization. Such an effect may occur if urbanization alters the food available to species with color based on carotenoids, which they must obtain from their diet. Over 3 years, we compared a comprehensive suite of visual signals in male and female Northern Cardinals (Cardinalis cardinalis) in a rural and an urban population. We predicted that urban birds would have enhanced carotenoid-based signals as they likely have access to more carotenoids from invasive plants that thrive in cities. We used reflectance spectrometry, digital image analyses. and avian visual models to quantify hue. saturation, and brightness of chest (male), underwing (female), and bill (male and female) signals. Compared to rural males, urban males had redder chest feathers in 1 year and redder bills in every year. Urban females had more saturated underwing color than rural females in every year. These color differences were sufficient to be distinguished by the avian visual system. Female bill color did not vary between sites. Interestingly, urban birds had significantly reduced mass-related body condition compared to rural birds. Thus, urban males and females can display enhanced carotenoid-based signals despite being in relatively poor condition. We suggest that urban birds have more access to carotenoids from invasive honeysuckle (Lonicera spp.) than rural birds. This color enhancement could affect the information content of the signals and the dynamics of the social and mating systems. These results stand in stark contrast to the predominant trend of decreased color in urban birds and highlight the complex and varied potential effects of urbanization on animal communication. Received 26 June 2022. Accepted 17 September 2022.
Short-term medical missions are common in medical educational settings and could possibly affect student learning. Little research has been conducted about the potential of these missions on ...students' transformative learning, in particular as it relates to empathy and multicultural awareness.
Eight podiatric medical students who participated in short-term medical missions in 2008 and 2009 completed an electronic survey to investigate the effect of their experience as it relates to their learning. The empathy and multicultural awareness impact of the mission experience was emphasized. Qualitative questions in the survey were coded, themed, and triangulated with the quantitative responses.
Six students (75%) "strongly agreed" that participating in the medical mission was a significant positive experience in their podiatric medical training. Six students felt that their experiences in serving these communities increased their personal awareness of multicultural/diversity needs in general. All of the students agreed that they will become better podiatric physicians because of their experiences in the medical missions. The qualitative data also indicate that the experience had an effect on the students' views of health care and increased empathy toward their patients.
Short-term medical missions could play a significant role in the transformative learning experience in podiatric medical education. This could affect the empathy and multicultural awareness of podiatric medical students. Further and more extensive evaluations of the potential impact of short-term medical missions in podiatric medical education should be explored because it could influence curriculum and global health in the field of podiatric medicine.
Transmetatarsal amputation (TMA) allows for maintenance of ambulatory function for patients with significant forefoot tissue loss. Effective revascularization is key to optimizing limb salvage for ...patients with chronic limb threatening ischemia (CLTI). We hypothesized that CLTI patients requiring TMA will have better healing and functional outcomes with open bypass than with endovascular revascularization.
Consecutive TMAs performed at three affiliated centers between 2008 and 2020 were retrospectively reviewed. The baseline characteristics, including WIfI (wound, ischemia, foot infection) stage, noninvasive vascular studies, healing, and ambulatory outcomes, were collected. Catheter-based angiographic images were evaluated using the GLASS (global limb anatomic staging system). The primary outcomes were TMA healing and community ambulation. The secondary outcomes were TMA that had healed at study end, any ambulatory function postoperatively, major amputation, and mortality. Descriptive statistics and univariate, multivariable, and Kaplan-Meier analyses were performed.
A total of 346 TMAs had been performed in 318 patients, 209 of whom had had peripheral artery disease (PAD). The median follow-up was 2.5 years. Patients with PAD had had significantly lower rates of healing compared with those without PAD (64% vs 77%; P = .007). Revascularization was performed in 185 limbs, with 102 treated endovascularly and 83 with open surgery. The patients who had undergone endovascular surgery were significantly less likely to have had the TMA healed at any point (55% vs 76%; P = .003) and less likely to have remained healed at study end (49% vs 66%; P = .02). Patients with GLASS stage 3 anatomy were significantly more likely to have healed after open surgery (75% vs 45%; P = .003). Long-term ambulation data were available for 72% of the revascularized patients. Endovascular surgery was associated with a lower likelihood of community ambulation after TMA (34% vs 57%; P = .002). On multivariable analysis, open surgery was significantly associated with TMA healing (odds ratio, 2.8; P = .007) and ambulation (odds ratio, 2.9; P = .001).
For patients with CLTI and significant tissue loss requiring TMA, an initial open approach to revascularization was associated with improved healing and higher rates of ambulation compared with endovascular interventions. The metabolic requirement for healing of a TMA in patients with CLTI might be better met by open revascularization.
Transplantation of retinal pigment epithelial (RPE) cells in the basal ganglia could provide a novel cell-based therapy for Parkinson's disease by providing a constant source of dopamine replacement ...via the melanin synthetic pathway enzyme tyrosinase. We now demonstrate that human RPE cells also produce a neurotrophic effect on primary cultures of rat striatal (enkephalinergic) and mesencephalic (dopaminergic) neurons. Differentiation of RPE cells to a pigmented monolayer using a Ca
++-switch protocol increased the potency of the neurotrophic effect on dopaminergic neurons. Conditioned medium derived from differentiated RPE cells increased neurite outgrowth in dopaminergic neurons by 125% compared to 25% for undifferentiated RPE cells. The neurotrophic effect was not due to tyrosinase activity. Differentiation of RPE cells doubled the production of pigment-derived epithelial factor (PEDF). However, PEDF accounted for only a portion of the neurotrophic effect as determined by depletion experiments and dose–response comparisons with purified PEDF, indicating that differentiation increased the production of other trophic factors as well. Conditioned medium from differentiated RPE cells also provided a neurotrophic effect on a subset of enkephalinergic striatal neurons increasing neurite outgrowth by 78%. Survival of enkephalinergic neurons in vitro was increased by RPE conditioned medium. In untreated cultures the number of enkephalinergic neurons declined 62% over a 2-week period compared to a 29% decline in RPE-treated cultures. These results indicate that transplantation RPE cells could potentially provide a dual benefit in Parkinson's disease producing both dopamine and neurotrophic support of the basal ganglia.
Heart failure is a debilitating condition in which the heart cannot meet the metabolic demands of the body. Chronic β-adrenergic (β-AR) stimulation causes pathological myocardial remodeling that ...leads to heart failure, in part, by promoting apoptosis of cardiac myocytes. Work from our laboratory has shown that β-AR stimulated apoptosis is dependent on reactive oxygen species (ROS), but the molecular targets by which ROS mediate apoptosis is not known. One target of ROS that may contribute to activating the apoptosis pathway is the sarco-endoplasmic reticulum ATPase (SERCA2). SERCA2 is responsible for moving the large majority of intracellular calcium in the cardiac myocyte. We have identified that SERCA2 can undergo oxidative post-translational modification (OPTM) of cysteine C674: Low ROS increase activity while high ROS decreases. Since SERCA is the primary calcium transporter and is located in close proximity of the mitochondria, it is possible SERCA activity may affect the level of calcium in mitochondria, which in excess is a known activator of the intrinsic mitochondrial apoptosis pathway. Progressive loss of myocardial cells in ischemia and heart failure likely contributes to the pathogenesis of cardiomyopathy. We hypothesized that oxidation of SERCA2 at C674 increases mitochondrial calcium, thereby activating the mitochondrial apoptosis pathway. To address this thesis, we used a novel redox-insensitive SERCA2 mutation in which C674 is replaced by serine (C674S) to determine the role of oxidative inhibition of SERCA in H2O2-stimulated apoptosis in vitro. We tested our hypothesis using adult rat ventricular myocytes (ARVM) that overexpress wild type or SERCA C674 and assessed intra-organelle calcium content, mitochondrial function and activation of the apoptosis pathway. To measure mitochondrial calcium, we optimized the use of an ultrasensitive genetically-encoded calcium indicator (GECI) targeted to the mitochondria which was expressed in ARVM via adenovirus infection. Redox-insensitive SERCA C674S expressing ARVM displayed less sensitivity to H2O2-stimulated mitochondrial calcium uptake which was confirmed by measuring calcium sensitive pyruvate dehydrogenase phosphorylation status. Furthermore, SERCA C674S ARVM were protected from H2O2 -mediated apoptosis, indicated by a reduction in cytochrome c release and annexin V staining. Lastly, H2O2 treatment decreased the cytosolic ATP/ADP ratio and depolarized the mitochondrial membrane potential, however this was independent of SERCA C674 oxidation. Taken together, these experiments elucidate a novel role for SERCA2 activity in cardiac myocytes and provide a potential therapeutic target for reducing cardiac myocyte apoptosis, potentially improving cardiac function during heart failure.
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