TRimetazidine as an Agent to affeCt clopidogrEl Response: The TRACER Study.

INTRODUCTION: This prospective study aimed to determine whether trimetazidine (TMZ) alters the pharmacodynamic (PD) effects of clopidogrel. METHODS: Patients with stable coronary artery disease (SCAD) (n = 24) who were actively treated with dual antiplatelet therapy (DAPT) of aspirin 81 mg daily and clopidogrel 75 mg daily were recruited. Platelet function was measured with the VerifyNow P2Y12 assay (Accriva Diagnostics, San Diego, CA, USA) and assessed before the initiation of and after 14 days of treatment with TMZ. Results were compared using a paired t test. RESULTS: Almost 80% of the study population were of South Asian descent and had diabetes mellitus (DM). P2Y12 reaction units (PRUs) were higher in patients on TMZ (204 ± 56 compared with 174 ± 71 before TMZ, p = 0.005). The average increase in PRU score was 29 (95% confidence interval 8.8-49.7). Before TMZ, the proportion of patients with high on-treatment platelet reactivity (PRU > 208 units) was 25%, which increased to 42% for patients on TMZ. CONCLUSION: Higher platelet reactivity was seen in patients on TMZ, suggesting that TMZ attenuated the PD effects of clopidogrel in this study of a predominantly South Asian diabetic subpopulation. Alternative therapies should be considered and further research is warranted. TRIAL REGISTRATION: ClinicalTrials.gov number, NCT03603249.

Identifying Predictors of Prolonged Levothyroxine Dose Adjustment After Thyroidectomy.

BACKGROUND: Levothyroxine (LT4) is one of the most prescribed drugs in the United States; however, many patients started on LT4 after thyroidectomy suffer from symptoms of hyper- or hypo-thyroidism before achieving euthyroidism. This study aims to describe the time required for dose adjustment before achieving euthyroidism and identify predictors of prolonged dose adjustment (PDA+) after thyroidectomy. METHODS: This is a single institution retrospective cohort study of patients who achieved euthyroidism with LT4 therapy between 2008 and 2017 after total or completion thyroidectomy for benign disease. Patients who needed at least three dose adjustments (top quartile) were considered PDA+. Binomial logistic regression was used to identify predictors of PDA+. RESULTS: The 605 patients in this study achieved euthyroidism in a median of 116 d (standard deviation 124.9) and one dose adjustment (standard deviation 1.3). The 508 PDA- patients achieved euthyroidism in a median of 101 d and one dose adjustment. The 97 PDA+ patients achieved euthyroidism in a median of 271 d and three dose adjustments. Iron supplementation (odds ratio = 4.4, 95% confidence interval = 1.4-13.5, P = 0.010) and multivitamin with mineral supplementation (odds ratio = 2.4, 95% confidence interval = 1.3-4.3, P = 0.004) were independently associated with PDA+. Age, gender, preoperative thyroid disease, and comorbidities did not independently predict PDA+. CONCLUSIONS: After thyroidectomy, achieving euthyroidism can take nearly 4 mo. Iron and mineral supplementation are associated with PDA+. This information can inform the preoperative counseling of patients and suggests that this may expedite achieving euthyroidism.

Failure to Diagnose and Treat Hyperparathyroidism Among Patients with Hypercalcemia: Opportunities for Intervention at the Patient and Physician Level to Increase Surgical Referral.

BACKGROUND: Hyperparathyroidism is both underdiagnosed and undertreated, but the reasons for these deficiencies have not been described. The purpose of this study was to identify reasons for underdiagnosis and undertreatment of hyperparathyroidism that could be addressed by targeted interventions. MATERIALS AND METHODS: We identified 3,200 patients with hypercalcemia (serum calcium >10.5 mg/dL) who had parathyroid hormone (PTH) levels evaluated at our institution from 2011 to 2016. We randomly sampled 60 patients and divided them into three groups based on their PTH levels. Two independent reviewers examined clinical notes and diagnostic data to identify reasons for delayed diagnosis or referral for treatment. RESULTS: The mean age of the patients was 61 ± 16.5 years, 68% were women, and 55% were white. Fifty percent of patients had ≥1 elevated calcium that was missed by their primary care provider. Hypercalcemia was frequently attributed to causes other than hyperparathyroidism, including diuretics (12%), calcium supplements (12%), dehydration (5%), and renal dysfunction (3%). Even when calcium and PTH were both elevated, the diagnosis was missed or delayed in 40% of patients. For 7% of patients, a nonsurgeon stated that surgery offered no benefit; 22% of patients were offered medical treatment or observation, and 8% opted not to see a surgeon. Only 20% of patients were referred for surgical evaluation, and they waited a median of 16 months before seeing a surgeon. CONCLUSION: To address common causes for delayed diagnosis and treatment of hyperparathyroidism, we must improve systems for recognizing hypercalcemia and better educate patients and providers about the consequences of untreated disease. IMPLICATIONS FOR PRACTICE: This study identified reasons why patients experience delays in workup, diagnosis, and treatment of primary hyperparathyroidism. These data provide valuable information for developing interventions that increase rates of diagnosis and referral.

Minimally invasive follicular thyroid cancer: treat as a benign or malignant lesion?

BACKGROUND: Follicular thyroid cancer is the second most common thyroid cancer, accounting for 10%-15% of all cases. Follicular thyroid carcinomas (FTCs) can be classified into two subtypes: classic (C), which exhibit both vascular and capsular invasion and minimally invasive (MI), which only has limited capsular invasion. Both types, like most well-differentiated thyroid cancers, are traditionally treated the same: a completion thyroidectomy usually followed by radioiodine ablation. We hypothesize that MI-FTC may behave more like a benign follicular adenoma rather than C-FTC and may not require total thyroidectomy and radioiodine. METHODS: A prospective thyroid database was screened for patients with follicular cell tumors. Data on recurrence rates, disease-free survival, and requirement for follow-up surgery and/or radioiodine were compared. Disease-free survival was determined by the Kaplan-Meier method. Analysis of variance and chi-square test were used to evaluate other factors. RESULTS: In total, there were 419 benign adenomas (87%), 21 MI-FTCs (4.5%), and 41 C-FTCs (8.5%). Patients with adenomas were younger (P = 0.035) and were more likely to be female (P = 0.001). Importantly, the 16-y disease-free survival was 100% in the adenoma group, 100% in the MI-FTC group, and 36.6% in the C-FTC group (P < 0.0001). CONCLUSIONS: MI-FTCs behave similar to adenomas with 100% disease-free survival with up to 16 y of follow-up. These data suggest MI-FTCs could be potentially treated by thyroid lobectomy alone like follicular adenomas and perhaps should be classified as a distinct clinical entity.

Hypoparathyroidism after total thyroidectomy: incidence and resolution.

BACKGROUND: Parathyroid hormone (PTH) levels are often measured after thyroid surgery and are used to detect patients at risk for postoperative hypoparathyroidism. However, there is a lack of consensus in the literature about how to define the recovery of parathyroid gland function and when to classify hypoparathyroidism as permanent. The goals of this study were to determine the incidence of low postoperative PTH in total thyroidectomy patients and to monitor their time course to recovery of parathyroid gland function. METHODS: We identified 1054 consecutive patients who underwent a total or completion thyroidectomy from January, 2006-December, 2013. Low PTH was defined as a PTH measurement <10 pg/mL immediately after surgery. Patients were considered to be permanently hypoparathyroid if they had not recovered within 1 y. Recovery of parathyroid gland function was defined as PTH ≥10 pg/mL and no need for therapeutic calcium or activated vitamin D (calcitriol) supplementation to prevent hypocalcemic symptoms. RESULTS: Of 1054 total thyroidectomy patients, 189 (18%) had a postoperative PTH <10 pg/mL. Of those 189 patients, 132 (70%) showed resolution within 2 mo of surgery. Notably, 9 (5%) resolved between 6 and 12 mo. At 1 y, 20 (1.9%) were considered to have permanent hypoparathyroidism. Surprisingly, 50% of those patients had recovery of PTH levels yet still required supplementation to avoid symptoms. CONCLUSIONS: Most patients with a low postoperative PTH recover function quickly, but it can take up to 1 y for full resolution. Hypoparathyroidism needs to be defined not only by PTH levels but also by medication requirements.

Preventing postoperative hypocalcemia in patients with Graves disease: a prospective study.

BACKGROUND: Hypocalcemia occurs after total thyroidectomy (TT) for Graves disease via parathyroid injury and/or from increased bone turnover. Current management is to supplement calcium after surgery. This study evaluates the impact of preoperative calcium supplementation on hypocalcemia after Graves TT. METHODS: A prospective study of patients with Graves disease undergoing TT was performed. Patients with Graves disease managed over a 9-month period took 1 g of calcium carbonate (CC) three times a day for 2 weeks before TT. Those managed the previous year without supplementation served as historic controls. Age-, gender-, and thyroid weight-matched, non-Graves TT patients were procedure controls. Patient demographics, postoperative laboratory values, complaints, and medications were reviewed. Parathyroid hormone (PTH)-based postoperative protocols dictated postoperative CC and calcitriol use. RESULTS: Forty-five patients with Graves disease were treated with CC before TT, and 38 patients with Graves disease were not. Forty control subjects without Graves disease were identified. Age, gender, and thyroid weight were comparable. Preoperative calcium and PTH levels were equivalent. PTH values immediately after surgery, at postoperative day 1, and at 2-week follow-up were equivalent. Postoperative use of scheduled CC (p = 0.10) and calcitriol (p = 0.60) was similar. Postoperatively, patients with untreated Graves disease had lower serum calcium levels than pretreated patients with Graves disease or control subjects without Graves disease (8.3 mg/dL vs. 8.6 vs. 8.6, p = 0.05). Complaints of numbness and tingling were more common in nontreated Graves disease (26%) than in pretreated Graves disease (9%) or in control subjects without Graves disease (10%, p < 0.05). CONCLUSIONS: Calcium supplementation before TT for Graves disease significantly reduced biochemical and symptomatic postoperative hypocalcemia. Preoperative calcium supplementation is a simple treatment that can reduce symptoms of hypocalcemia after Graves TT.

Sparse and background-invariant coding of vocalizations in auditory scenes.

Vocal communicators such as humans and songbirds readily recognize individual vocalizations, even in distracting auditory environments. This perceptual ability is likely subserved by auditory neurons whose spiking responses to individual vocalizations are minimally affected by background sounds. However, auditory neurons that produce background-invariant responses to vocalizations in auditory scenes have not been found. Here, we describe a population of neurons in the zebra finch auditory cortex that represent vocalizations with a sparse code and that maintain their vocalization-like firing patterns in levels of background sound that permit behavioral recognition. These same neurons decrease or stop spiking in levels of background sound that preclude behavioral recognition. In contrast, upstream neurons represent vocalizations with dense and background-corrupted responses. We provide experimental evidence suggesting that sparse coding is mediated by feedforward suppression. Finally, we show through simulations that feedforward inhibition can transform a dense representation of vocalizations into a sparse and background-invariant representation.

Toxicological and pharmacokinetic properties of chemically modified siRNAs targeting p53 RNA following intravenous administration.

We report the toxicological and pharmacokinetic properties of the synthetic, small interfering RNA I5NP following intravenous administration in rodents and nonhuman primates. I5NP is designed to act via the RNA interference (RNAi) pathway to temporarily inhibit expression of the pro-apoptotic protein p53 and is being developed to protect cells from acute ischemia/reperfusion injuries such as acute kidney injury that can occur during major cardiac surgery and delayed graft function that can occur following renal transplantation. Following intravenous administration, I5NP was very rapidly cleared from plasma was distributed predominantly to the kidney, with very low levels in liver and other tissues. Doses of 800 mg/kg I5NP in rodents, and 1,000 mg/kg I5NP in nonhuman primates, were required to elicit adverse effects, which in the monkey were isolated to direct effects on the blood that included a sub-clinical activation of complement and slightly increased clotting times. In the rat, no additional adverse effects were observed with a rat analogue of I5NP, indicating that the effects likely represent class effects of synthetic RNA duplexes rather than toxicity related to the intended pharmacologic activity of I5NP. Taken together, these data support clinical testing of intravenous administration of I5NP for the preservation of renal function following acute ischemia/reperfusion injury.

Pharmacokinetic modeling of the high-dose bolus regimen of tirofiban in patients with severe renal impairment.

For the treatment of patients with acute coronary syndromes in the catheterization laboratory, a high-dose bolus (HDB) regimen of tirofiban (25 µg/kg bolus, followed by an infusion of 0.15 µg/kg/min) leads to a consistent and rapid inhibition of platelet aggregation during the first hour after initiation of therapy. The objective of the present study was to use pharmacokinetic modeling to identify an appropriate dosage of tirofiban that would produce a plasma concentration-time profile in patients with severe renal impairment (creatinine clearance<30 ml/min) as similar as possible to that of the HDB regimen in patients with normal renal function. For patients with severe renal impairment, previous recommendations have been to reduce the dosage by 50%. Pharmacokinetic modeling was performed with the following sets of data: the plasma concentrations of tirofiban from patients with normal renal function who were treated with the HDB regimen of tirofiban and the plasma concentrations of tirofiban from patients with severe renal impairment who were treated with a 0.1 µg/kg/min infusion of tirofiban for 1 h. In conclusion, for patients with severe renal impairment, a 25 µg/kg bolus, followed by a 0.10 µg/kg/min maintenance infusion of tirofiban produced a plasma concentration-time profile similar to that observed with the HDB regimen of tirofiban in patients with normal renal function.

Rivaroxaban in patients with a recent acute coronary syndrome.

BACKGROUND: Acute coronary syndromes arise from coronary atherosclerosis with superimposed thrombosis. Since factor Xa plays a central role in thrombosis, the inhibition of factor Xa with low-dose rivaroxaban might improve cardiovascular outcomes in patients with a recent acute coronary syndrome. METHODS: In this double-blind, placebo-controlled trial, we randomly assigned 15,526 patients with a recent acute coronary syndrome to receive twice-daily doses of either 2.5 mg or 5 mg of rivaroxaban or placebo for a mean of 13 months and up to 31 months. The primary efficacy end point was a composite of death from cardiovascular causes, myocardial infarction, or stroke. RESULTS: Rivaroxaban significantly reduced the primary efficacy end point, as compared with placebo, with respective rates of 8.9% and 10.7% (hazard ratio in the rivaroxaban group, 0.84; 95% confidence interval [CI], 0.74 to 0.96; P=0.008), with significant improvement for both the twice-daily 2.5-mg dose (9.1% vs. 10.7%, P=0.02) and the twice-daily 5-mg dose (8.8% vs. 10.7%, P=0.03). The twice-daily 2.5-mg dose of rivaroxaban reduced the rates of death from cardiovascular causes (2.7% vs. 4.1%, P=0.002) and from any cause (2.9% vs. 4.5%, P=0.002), a survival benefit that was not seen with the twice-daily 5-mg dose. As compared with placebo, rivaroxaban increased the rates of major bleeding not related to coronary-artery bypass grafting (2.1% vs. 0.6%, P<0.001) and intracranial hemorrhage (0.6% vs. 0.2%, P=0.009), without a significant increase in fatal bleeding (0.3% vs. 0.2%, P=0.66) or other adverse events. The twice-daily 2.5-mg dose resulted in fewer fatal bleeding events than the twice-daily 5-mg dose (0.1% vs. 0.4%, P=0.04). CONCLUSIONS: In patients with a recent acute coronary syndrome, rivaroxaban reduced the risk of the composite end point of death from cardiovascular causes, myocardial infarction, or stroke. Rivaroxaban increased the risk of major bleeding and intracranial hemorrhage but not the risk of fatal bleeding. (Funded by Johnson & Johnson and Bayer Healthcare; ATLAS ACS 2-TIMI 51 ClinicalTrials.gov number, NCT00809965.).

Complex responses to culture conditions in Pseudomonas syringae pv. tomato DC3000 continuous cultures: the role of iron in cell growth and virulence factor induction.

The growth of a model plant pathogen, Pseudomonas syringae pv. tomato DC3000, was investigated using a chemostat culture system to examine environmentally regulated responses. Using minimal medium with iron as the limiting nutrient, four different types of responses were obtained in a customized continuous culture system: (1) stable steady state, (2) damped oscillation, (3) normal washout due to high dilution rates exceeding the maximum growth rate, and (4) washout at low dilution rates due to negative growth rates. The type of response was determined by a combination of initial cell mass and dilution rate. Stable steady states were obtained with dilution rates ranging from 0.059 to 0.086 h(-1) with an initial cell mass of less than 0.6 OD(600). Damped oscillations and negative growth rates are unusual observations for bacterial systems. We have observed these responses at values of initial cell mass of 0.9 OD(600) or higher, or at low dilution rates (<0.05 h(-1)) irrespectively of initial cell mass. This response suggests complex dynamics including the possibility of multiple steady states.Iron, which was reported earlier as a growth limiting nutrient in a widely used minimal medium, enhances both growth and virulence factor induction in iron-supplemented cultures compared to unsupplemented controls. Intracellular iron concentration is correlated to the early induction (6 h) of virulence factors in both batch and chemostat cultures. A reduction in aconitase activity (a TCA cycle enzyme) and ATP levels in iron-limited chemostat cultures was observed compared to iron-supplemented chemostat cultures, indicating that iron affects central metabolic pathways. We conclude that DC3000 cultures are particularly dependent on the environment and iron is likely a key nutrient in determining physiology.

Effect of iron concentration on the growth rate of Pseudomonas syringae and the expression of virulence factors in hrp-inducing minimal medium.

Although chemically defined media have been developed and widely used to study the expression of virulence factors in the model plant pathogen Pseudomonas syringae, it has been difficult to link specific medium components to the induction response. Using a chemostat system, we found that iron is the limiting nutrient for growth in the standard hrp-inducing minimal medium and plays an important role in inducing several virulence-related genes in Pseudomonas syringae pv. tomato DC3000. With various concentrations of iron oxalate, growth was found to follow Monod-type kinetics for low to moderate iron concentrations. Observable toxicity due to iron began at 400 microM Fe(3+). The kinetics of virulence factor gene induction can be expressed mathematically in terms of supplemented-iron concentration. We conclude that studies of induction of virulence-related genes in P. syringae should control iron levels carefully to reduce variations in the availability of this essential nutrient.

Streamlining the design of promising clinical trials: in-vitro testing of antithrombotic regimens and multiple agonists of platelet activation.

Platelets are activated in vivo by multiple agonists; however, platelet function testing in vitro has been performed predominantly with only one or two agonists of platelet activation. Greater insight into anticipated effects of antithrombotic regimens should enhance the design of successful clinical trials. To test this concept, we assessed platelet activation induced by multiple agonists and two antithrombotic regimens, unfractionated heparin (UFH) and eptifibatide compared with bivalirudin and cangrelor. Blood samples from 10 patients with coronary artery disease were spiked with pharmacologic concentrations achieved in vivo of either UFH (1.2 U/ml) and eptifibatide (1.7 microg/ml), or with bivalirudin (8 microg/ml) and cangrelor (500 nmol/l). Platelet function was assessed with the use of flow cytometry. Agonists included thrombin (50 nmol/l), adenosine diphosphate (1 micromol/l), the collagen-mimetic convulxin (5 ng/ml), and platelet-activating factor (10 nmol/l). When platelet activation was identified by the surface expression of P-selectin in response to multiple agonists, the combination of bivalirudin and cangrelor suppressed activation more than UFH and eptifibatide. When platelet activation was identified by the activation of glycoprotein IIb-IIIa (PAC-1 binding), the combination of bivalirudin and cangrelor was more effective in suppressing activation in response to thrombin and adenosine diphosphate, whereas UFH and eptifibatide more effectively prevented binding of PAC-1 when platelets were activated with the collagen-mimetic convulxin. In conclusion, bivalirudin and cangrelor suppressed platelet activation in response to diverse agonists in vitro more than UFH and eptifibatide. These results and this approach to selection of promising interventions should be helpful in streamlining the design of clinical trials.

Global transcriptional responses of Pseudomonas syringae DC3000 to changes in iron bioavailability in vitro.

BACKGROUND: Pseudomonas syringae pv tomato DC3000 (DC3000) is a Gram-negative model plant pathogen that is found in a wide variety of environments. To survive in these diverse conditions it must sense and respond to various environmental cues. One micronutrient required for most forms of life is iron. Bioavailable iron has been shown to be an important global regulator for many bacteria where it not only regulates a wide variety of genes involved in general cell physiology but also virulence determinants. In this study we used microarrays to study differential gene regulation in DC3000 in response to changes in levels of cell-associated iron. RESULTS: DC3000 cultures were grown under highly controlled conditions and analyzed after the addition of iron citrate or sodium citrate to the media. In the cultures supplemented with iron, we found that cell-associated iron increased rapidly while culture densities were not significantly different over 4 hours when compared to cultures with sodium citrate added. Microarray analysis of samples taken from before and after the addition of either sodium citrate or iron citrate identified 386 differentially regulated genes with high statistical confidence. Differentially regulated genes were clustered based on expression patterns observed between comparison of samples taken at different time points and with different supplements. This analysis grouped genes associated with the same regulatory motifs and/or had similar putative or known function. CONCLUSION: This study shows iron is rapidly taken up from the medium by iron-depleted DC3000 cultures and that bioavailable iron is a global cue for the expression of iron transport, storage, and known virulence factors in DC3000. Furthermore approximately 34% of the differentially regulated genes are associated with one of four regulatory motifs for Fur, PvdS, HrpL, or RpoD.

Comparing an estimate of seabirds at risk to a mortality estimate from the November 2004 Terra Nova FPSO oil spill.

On 21 November 2004, about 1000 barrels of crude oil were accidentally released from the Terra Nova FPSO (floating production, storage and offloading) onto the Grand Banks, approximately 340 km east-southeast of St. John's, Newfoundland. We estimated the number of vulnerable seabirds (murres (Uria spp.) and dovekies (Alle alle)) at risk from this incident by multiplying observed densities of seabirds with the total area covered by the slick, estimated at 793 km(2). A mean density of 3.46 murres/km(2) and 1.07 dovekies/km(2) on the sea surface was recorded during vessel-based surveys on 28 and 29 November 2004, with a mean density of 6.90 murres/km(2) and 13.43 dovekies/km(2) combining those on the sea and in flight. We calculated a mean of 9858 murres and dovekies were at risk of being oiled, with estimates ranging from 3593 to 16,122 depending on what portion of birds in flight were assumed to be at risk. A mortality model based on spill volume was derived independently of the risk model, and estimated that 4688 (CI 95%: 1905-12,480) birds were killed during this incident. A low mortality estimate based strictly on spill volume would be expected for this incident, which occurred in an area of relatively high seabird densities. Given that the risk and mortality estimates are statistically indistinguishable, we estimate that on the order of 10,000 birds were killed by the Terra Nova spill.