Clinical research is about asking and answering questions. Before solutions relevant to clinical problems can be sought, clinicians must frame questions in ways that are answerable using the methods ...of clinical research. Different types of questions are best answered using specific study designs. Each design has inherent strengths and limitations. In this review article, we provide an approach to asking answerable clinical research questions, review the major study designs, describe their strengths and weaknesses, and link the study designs to their intended purposes.
The circadian clock coordinates daily oscillations of essential physiological and behavioral processes. Conversely, aberrant clocks with damped amplitude and/or abnormal period have been associated ...with chronic diseases and aging. To search for small molecules that perturb or enhance circadian rhythms, we conducted a high-throughput screen of approximately 200,000 synthetic compounds using Per2::lucSV reporter fibroblast cells and validated 11 independent classes of molecules with Bmal1:luciferase reporter cells as well as with suprachiasmatic nucleus and peripheral tissue explants. Four compounds were found to lengthen the period in both central and peripheral clocks, including three compounds that inhibited casein kinase Iε in vitro and a unique benzodiazepine derivative acting through a non-GABAA receptor target. In addition, two compounds acutely induced Per2::lucSV reporter bioluminescence, delayed the rhythm, and increased intracellular cAMP levels, but caused rhythm damping. Importantly, five compounds shortened the period of peripheral clocks; among them, four compounds also enhanced the amplitude of central and/or peripheral reporter rhythms. Taken together, these studies highlight diverse activities of drug-like small molecules in manipulating the central and peripheral clocks. These small molecules constitute a toolbox for probing clock regulatory mechanisms and may provide putative lead compounds for treatment of clock-associated diseases.
Electroluminescence from quantum dots (QDs) is a suitable photon source for futuristic displays offering hyper‐realistic images with free‐form factors. Accordingly, a nondestructive and scalable ...process capable of rendering multicolored QD patterns on a scale of several micrometers needs to be established. Here, nondestructive direct photopatterning for heavy‐metal‐free QDs is reported using branched light‐driven ligand crosslinkers (LiXers) containing multiple azide units. The branched LiXers effectively interlock QD films via photo‐crosslinking native aliphatic QD surface ligands without compromising the intrinsic optoelectronic properties of QDs. Using branched LiXers with six sterically engineered azide units, RGB QD patterns are achieved on the micrometer scale. The photo‐crosslinking process does not affect the photoluminescence and electroluminescence characteristics of QDs and extends the device lifetime. This nondestructive method can be readily adapted to industrial processes and make an immediate impact on display technologies, as it uses widely available photolithography facilities and high‐quality heavy‐metal‐free QDs with aliphatic ligands.
Nondestructive direct photopatterning for heavy‐metal‐free quantum dots is presented by using branched light‐driven ligand crosslinkers containing multiple azide units. The branched crosslinkers effectively interlock quantum dot films without compromising the intrinsic photoluminescence and electroluminescence properties of quantum dots. This nondestructive method can be directly adapted to photolithography facilities widely available in industry.
BK virus infection is a significant complication of modern immunosuppression used in kidney transplantation. Viral reactivation occurs first in the urine (BK viruria) and is associated with a high ...risk of transplant failure. There are currently no therapies to prevent or treat BK virus infection. Quinolone antibiotics have antiviral properties against BK virus but efficacy at preventing this infection has not been shown in prospective controlled studies.
To determine if levofloxacin can prevent BK viruria in kidney transplant recipients.
Double-blind, placebo-controlled randomized trial involving 154 patients who received a living or deceased donor kidney-only transplant in 7 Canadian transplant centers between December 2011 and June 2013.
Participants were randomly assigned to receive a 3-month course of levofloxacin (500 mg/d; n = 76) or placebo (n = 78) starting within 5 days after transplantation.
The primary outcome was time to occurrence of BK viruria (detected using quantitative real-time polymerase chain reaction) within the first year after transplantation. Secondary outcomes included BK viremia, peak viral load, rejection, and patient and allograft survival.
The mean follow-up time was 46.5 weeks in the levofloxacin group and 46.3 weeks in the placebo group (27 patients had follow-up terminated before the end of the planned follow-up period or development of viruria because the trial was stopped early owing to lack of funding). BK viruria occurred in 22 patients (29%) in the levofloxacin group and in 26 patients (33.3%) in the placebo group (hazard ratio, 0.91; 95% CI, 0.51-1.63; P = .58). There was no significant difference between the 2 groups in regard to any of the secondary end points. There was an increased risk of resistant infection among isolates usually sensitive to quinolones in the levofloxacin group vs placebo (14/24 58.3% vs 15/45 33.3%, respectively; risk ratio, 1.75; 95% CI, 1.01-2.98) as well as a nonsignificant increased risk of suspected tendinitis (6/76 7.9% vs 1/78 1.3%; risk ratio, 6.16; 95% CI, 0.76-49.95).
Among kidney transplant recipients, a 3-month course of levofloxacin initiated early following transplantation did not prevent BK viruria. Levofloxacin was associated with an increased risk of adverse events such as bacterial resistance. These findings do not support the use of levofloxacin to prevent posttransplant BK virus infection.
clinicaltrials.gov Identifier: NCT01353339.
Warm ischemia time is a potentially modifiable insult to transplanted kidneys, but little is known about its effect on long-term outcomes. Here we conducted a study of United States kidney transplant ...recipients (years 2000–2013) to determine the association between warm ischemia time (the time from organ removal from cold storage to reperfusion with warm blood) and death/graft failure. Times under 10 minutes were potentially attributed to coding error. Therefore, the 10-to-under-20-minute interval was chosen as the reference group. The primary outcome was mortality and graft failure (return to chronic dialysis or preemptive retransplantation) adjusted for recipient, donor, immunologic, and surgical factors. The study included 131,677 patients with 35,901 events. Relative to the reference patients, times of 10 to under 20, 20 to under 30, 30 to under 40, 40 to under 50, 50 to under 60, and 60 and more minutes were associated with hazard ratios of 1.07 (95% confidence interval, 0.99–1.15), 1.13 (1.06–1.22), 1.17 (1.09–1.26), 1.20 (1.12–1.30), and 1.23 (1.15–1.33) for the composite event, respectively. Association between prolonged warm ischemia time and death/graft failure persisted after stratification by donor type (living vs. deceased donor) and delayed graft function status. Thus, warm ischemia time is associated with adverse long-term patient and graft survival after kidney transplantation. Identifying strategies to reduce warm ischemia time is an important consideration for future study.
Outcomes of kidney transplant recipients with increased body mass index (BMI) remain controversial. We studied the relationship between BMI and clinically relevant outcomes among kidney transplant ...recipients at a large center.
We performed an observational cohort study of all recipients of kidney transplants at our center from January 1, 2000 to December 31, 2010 to determine if increased BMI at transplantation is associated with adverse outcomes, including delayed graft function and biopsy-proven acute rejection (BPAR). Recipient BMI was categorized as <20, 20 to 24.9 (reference), 25 to 29.9, 30 to 34.9, and ≥35 kg/m. Potential confounders were included in logistic and Cox proportional hazards models.
A total of 1151 patients were studied. Recipient BMI of 30 to 34.9 and ≥35 kg/m were associated with an increased risk of delayed graft function (odds ratio 95% confidence interval CI, 1.92 1.16-3.19 and 4.49 2.24-9.00, respectively). BMI≥35 kg/m was also associated with an increased risk of BPAR (hazard ratio HR; 95% CI, 2.43 1.48-3.99), all-cause graft failure (HR 95% CI, 1.97 1.09-3.56), and death-censored graft failure (HR 95% CI, 2.43 1.07-5.51). Adjustment for acute rejection as a time-varying covariate significantly attenuated the association with graft failure endpoints. There was no significant relation between BMI and death with graft function.
Increased BMI at kidney transplantation is a predictor of adverse outcomes, including BPAR. The role of pretransplantation weight reduction in improving graft and patient outcomes requires further study.
The circadian clock is a self-sustaining oscillator that controls daily rhythms. For the proper circadian gene expression, dynamic changes in chromatin structure are important. Although chromatin ...modifiers have been shown to play a role in circadian gene expression, the in vivo role of circadian signal-modulated chromatin modifiers at an organism level remains to be elucidated. Here, we provide evidence that the lysine-specific demethylase 1 (LSD1) is phosphorylated by protein kinase Cα (PKCα) in a circadian manner and the phosphorylated LSD1 forms a complex with CLOCK:BMAL1 to facilitate E-box-mediated transcriptional activation. Knockin mice bearing phosphorylation-defective Lsd1SA/SA alleles exhibited altered circadian rhythms in locomotor behavior with attenuation of rhythmic expression of core clock genes and impaired phase resetting of circadian clock. These data demonstrate that LSD1 is a key component of the molecular circadian oscillator, which plays a pivotal role in rhythmicity and phase resetting of the circadian clock.
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•PKCα-dependent LSD1 phosphorylation oscillates in a circadian manner•Lsd1SA/SA knockin mice show a defect in circadian rhythmicity•Lsd1SA/SA knockin mice show impaired Per1 induction by photic stimuli•Lsd1SA/SA knockin mice show impaired behavioral adaptation to photic stimuli
The circadian clock is a self-sustaining oscillator that controls daily rhythms. Using a phosphorylation-defective knockin mouse model of LSD1 histone demethylase, Nam et al., shows LSD1 to be a key component of the molecular circadian oscillator, which plays a pivotal role in rhythmicity and phase resetting of the circadian clock.
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