Selenazolidine: a selenium containing proline surrogate in peptide science

In the search for new peptide ligands containing selenium in their sequences, we investigated l-4-selenazolidine-carboxylic acid (selenazolidine, Sez) as a proline analog with the chalcogen atom in the γ-position of the ring. In contrast to proteinogenic selenocysteine (Sec) and selenomethionine (SeMet), the incorporation within a peptide sequence of such a non-natural amino acid has never been studied. There is thus a great interest in increasing the possibility of selenium insertion within peptides, especially for sequences that do not possess a sulfur containing amino acid (Cys or Met), by offering other selenated residues suitable for peptide synthesis protocols. Herein, we have evaluated selenazolidine in Boc/Bzl and Fmoc/tBu strategies through the synthesis of a model tripeptide, both in solution and on a solid support. Special attention was paid to the stability of the Sez residue in basic conditions. Thus, generic protocols have been optimized to synthesize Sez-containing peptides, through the use of an Fmoc-Xxx-Sez-OH dipeptide unit. As an example, a new analog of the vasopressin receptor-1A antagonist was prepared, in which Pro was replaced with Sez [3-(4-hydroxyphenyl)-propionyl-d-Tyr(Me)-Phe-Gln-Asn-Arg-Sez-Arg-NH2]. Both proline and such pseudo-proline containing peptides exhibited similar pharmacological properties and endopeptidase stabilities indicating that the presence of the selenium atom has minimal functional effects. Taking into account the straightforward handling of Sez as a dipeptide building block in a conventional Fmoc/tBu SPPS strategy, this result suggested a wide range of potential uses of the Sez amino acid in peptide chemistry, for instance as a viable proline surrogate as well as a selenium probe, complementary to Sec and SeMet, for NMR and mass spectrometry analytical purposes.

Exposure of the grass shrimp, Palaemonetes pugio, to antimicrobial compounds affects associated Vibrio bacterial density and development of antibiotic resistance

Antimicrobial compounds are widespread, emerging contaminants in the aquatic environment and may threaten ecosystem and human health. This study characterized effects of antimicrobial compounds common to human and veterinary medicine, aquaculture, and consumer personal care products [erythromycin (ERY), sulfamethoxazole (SMX), oxytetracycline (OTC), and triclosan (TCS)] in the grass shrimp Palaemonetes pugio. The effects of antimicrobial treatments on grass shrimp mortality and lipid peroxidation activity were measured. The effects of antimicrobial treatments on the bacterial community of the shrimp were then assessed by measuring Vibrio density and testing bacterial isolates for antibiotic resistance. TCS (0.33 mg/L) increased shrimp mortality by 37% and increased lipid peroxidation activity by 63%. A mixture of 0.33 mg/L TCS and 60 mg/L SMX caused a 47% increase in shrimp mortality and an 88% increase in lipid peroxidation activity. Exposure to SMX (30 mg/L or 60 mg/L) alone and to a mixture of SMX/ERY/OTC did not significantly affect shrimp survival or lipid peroxidation activity. Shrimp exposure to 0.33 mg/L TCS increased Vibrio density 350% as compared to the control whereas SMX, the SMX/TCS mixture, and the mixture of SMX/ERY/OTC decreased Vibrio density 78-94%. Increased Vibrio antibiotic resistance was observed for all shrimp antimicrobial treatments except for the mixture of SMX/ERY/OTC. Approximately 87% of grass shrimp Vibrio isolates displayed resistance to TCS in the control treatment suggesting a high level of TCS resistance in environmental Vibrio populations. The presence of TCS in coastal waters may preferentially increase the resistance and abundance of pathogenic bacteria. These results indicate the need for further study into the potential interactions between antimicrobials, aquatic organisms, and associated bacterial communities.

Survival analysis in gastric cancer patients of the Colombian coffee zone at the Oncologos del Occidente clinic during 2014

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Background: The risk of death for gastric cancer in Colombia is lightly higher for 2013 compared to 1998. Even though Risaralda has an irregular pattern for the risk of death, it was also higher compared to 1998, for these reasons the survival analysis was made with the information of gastric cancer patients treated in Oncólogos del Occidente clinic during 2014. Methods: A cohort study was made whose exposure is the treatment of gastric cancer. The time variable is the interval between the first medical appointment and the final control, interview or date of death, and the outcome makes reference to a death attributable to cancer gastric or surviving. The source of the cases were the clinical histories found in SAHICO data base, of the patients attended in the clinic Oncólogos del Occidente, to make univariate and bivariate analysis using Stata software. Results: There were 173 patients, from which 69.9% were male; the age group with highest incidence was 60 to 69 years old group (32.2%); 21.38% of the patients had family members with gastric cancer and 53.1% were diagnosed during advanced stages (III-IV). As far as the survival analysis, it was 207 days long, lessen if the patient only receives palliative treatment (122 days long) and increasing if surgery, chemotherapy and radiotherapy were done (252 days long). Conclusions: In a national and international level, the epidemiological data correlates with the findings in this study; with respect to the diagnosis, in Colombia, it is made during advanced stages, meanwhile in developed countries the diagnosis is made during earlier stages because of the screening tests. The oncological surgery increased the patient’s survival, also for the patients who underwent surgery when they received chemotherapy or radiotherapy.

Sensitivity and specificity of signs and symptoms to determine the risk of death associated with gastric cancer patients

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Background: Risaralda (Colombia) has an irregular pattern in the risk of death for gastric cancer; for these reasons, the survival analysis was made with the information of gastric cancer patients treated in Oncólogos del Occidente clinic during 2014. Methods: A cross-sectional study was done with oncologic patients in order to evaluate the replicability of a binary list of signs and symptoms of gastric cancer, also its corresponding principal component factors for the proper identification of their dimensions. A sum of the set of signs and symptoms was done. This total sum of signs and symptoms was used to identify the sensitivity and specificity of each of cut-off related to the patient’s death condition. This evaluation was established by the ROC (Receiver Operating Characteristic) methodology, which is a graphic representation of the sensitivity in front of the specificity for a classifying binary system that may vary the threshold of rejection. The analysis was done in Stata. Results: There were 173 patients, of whom 69.9% were males; the group with the highest incidence was the 60-69 years old group (32%); These patients referred 5 signs and symptoms that conformed the list from which every single item behaved as a binary variable. Cronbach’s alpha was 0.62 and the analysis of principal components factors defined only one dimension. The ROC curve established a sensitivity of 65% and a specificity of 72% for the determination of the risk of death with a score equal or higher to 4 in the sum of the list of signs and symptoms. Adding the gender, the sensitivity increased to 66%. In the ≥ 80 years old group the sensitivity was 70.9%, meanwhile the group of ≥ 40 years old the sensitivity was 93%. Conclusions: The list of signs and symptoms could be a diagnostic technology relevant for unspecific clinical but has an important high frequency in Colombia for gastric cancer patients. The sensitivity was very variable according to the age range, being more sensible and specific for the patients of the ≥ 40 years old group.

Autonomic Findings in Takotsubo Cardiomyopathy

Takotsubo cardiomyopathy (TC) often occurs after emotional or physical stress. Norepinephrine levels are unusually high in the acute phase, suggesting a hyperadrenergic mechanism. Comparatively little is known about parasympathetic function in patients with TC. We sought to characterize autonomic function at rest and in response to physical and emotional stimuli in 10 women with a confirmed history of TC and 10 age-matched healthy women. Sympathetic and parasympathetic activity was assessed at rest and during baroreflex stimulation (Valsalva maneuver and tilt testing), cognitive stimulation (Stroop test), and emotional stimulation (event recall, patients). Ambulatory blood pressure monitoring and measurement of brachial artery flow-mediated vasodilation were also performed. TC women (tested an average of 37 months after the event) had excessive pressor responses to cognitive stress (Stroop test: p <0.001 vs baseline and p = 0.03 vs controls) and emotional arousal (recall of TC event: p = 0.03 vs baseline). Pressor responses to hemodynamic stimuli were also amplified (Valsalva overshoot: p <0.05) and prolonged (duration: p <0.01) in the TC women compared with controls. Plasma catecholamine levels did not differ between TC women and controls. Indexes of parasympathetic (vagal) modulation of heart rate induced by respiration and cardiovagal baroreflex gain were significantly decreased in the TC women versus controls. In conclusion, even long after the initial episode, women with previous episode of TC have excessive sympathetic responsiveness and reduced parasympathetic modulation of heart rate. Impaired baroreflex control may therefore play a role in TC.

Imaging heterogeneity of peptide delivery and binding in solid tumors using SPECT imaging and MRI

Background

As model system, a solid-tumor patient-derived xenograft (PDX) model characterized by high peptide receptor expression and histological tissue homogeneity was used to study radiopeptide targeting. In this solid-tumor model, high tumor uptake of targeting peptides was expected. However, in vivo SPECT images showed substantial heterogeneous radioactivity accumulation despite homogenous receptor distribution in the tumor xenografts as assessed by in vitro autoradiography. We hypothesized that delivery of peptide to the tumor cells is dictated by adequate local tumor perfusion. To study this relationship, sequential SPECT/CT and MRI were performed to assess the role of vascular functionality in radiopeptide accumulation.

Methods

High-resolution SPECT and dynamic contrast-enhanced (DCE)-MRI were acquired in six mice bearing PC295 PDX tumors expressing the gastrin-releasing peptide (GRP) receptor. Two hours prior to SPECT imaging, animals received 25 MBq ¹¹¹In(DOTA-(βAla)2-JMV594) (25 pmol). Images were acquired using multipinhole SPECT/CT. Directly after SPECT imaging, MR images were acquired on a 7.0-T dedicated animal scanner. DCE-MR images were quantified using semi-quantitative and quantitative models. The DCE-MR and SPECT images were spatially aligned to compute the correlations between radioactivity and DCE-MRI-derived parameters over the tumor.

Results

Whereas histology, in vitro autoradiography, and multiple-weighted MRI scans all showed homogenous tissue characteristics, both SPECT and DCE-MRI showed heterogeneous distribution patterns throughout the tumor. The average Spearman’s correlation coefficient between SPECT and DCE-MRI ranged from 0.57 to 0.63 for the “exchange-related” DCE-MRI perfusion parameters.

Conclusions

A positive correlation was shown between exchange-related DCE-MRI perfusion parameters and the amount of radioactivity accumulated as measured by SPECT, demonstrating that vascular function was an important aspect of radiopeptide distribution in solid tumors. The combined use of SPECT and MRI added crucial information on the perfusion efficiency versus radiopeptide uptake in solid tumors and showed that functional tumor characteristics varied locally even when the tissue appeared homogenous on current standard assessment techniques.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-016-0160-4) contains supplementary material, which is available to authorized users.

Poly(ethylene) glycols and mechanochemistry for the preparation of bioactive 3,5-disubstituted hydantoins

Mechanochemistry was effective for the preparation of 3,5-disubstituted hydantoins from α-amino methyl esters, using either 1,1′-carbonyldiimidazole (CDI) or alkyl isocyanates.

Progressive retinal structure abnormalities in multiple system atrophy

BACKGROUND

Objective measures of disease progression that can be used as endpoints in clinical trials of MSA are necessary. We studied retinal thickness in patients with MSA and assessed changes over time to determine its usefulness as an imaging biomarker of disease progression.

METHODS

This was a cross-sectional study including 24 patients with MSA, 20 with PD, and 35 controls, followed by a longitudinal study of 13 MSA patients. Patients were evaluated with high-definition optical coherence tomography and the Unified Multiple System Atrophy Rating Scale. Evaluations were performed at baseline and at consecutive follow-up visits for up to 26 months.

RESULTS

MSA subjects had normal visual acuity and color discrimination. Compared to controls, retinal nerve fiber layer (P = 0.008 and P = 0.001) and ganglion cell complex (P = 0.013 and P = 0.001) thicknesses were reduced in MSA and PD. No significant differences between MSA and PD were found. Over time, in patients with MSA, there was a significant reduction of the retinal nerve fiber layer and ganglion cell complex thicknesses, with estimated annual average losses of 3.7 and 1.8 μm, respectively.

CONCLUSIONS

Visually asymptomatic MSA patients exhibit progressive reductions in the thickness of the retinal nerve fiber layer and, to a lesser extent, in the macular ganglion cell complex, which can be quantified by high-definition optical coherence tomography. Specific patterns of retinal nerve fiber damage could be a useful imaging biomarker of disease progression in future clinical trials.

Abstract CT230: A phase I first in human dose escalation trial of MNK-010 in subjects with advanced solid tumors

Background: Taxanes possess broad activity and are widely used for a variety of tumor types. Currently available formulations are associated with dose limiting myelosuppression, neurotoxicity, fluid retention and other toxicities. MNK-010, a liposomal prodrug formulation of docetaxel, is designed to act as a drug depot with the slow conversion and release of docetaxel resulting in a relatively lower Cmax, and enhanced systemic exposure (AUC) over a prolonged period of time. It is anticipated that this unique PK profile would improve efficacy with a better safety profile compared to docetaxel.

Design: This study is a dose escalation first in human (FIH) study in subjects with advanced solid malignancies who have failed conventional therapy. MNK-010 is administered IV every 21 days for four cycles. The primary objectives are to evaluate the safety and tolerability and determine the MTD and DLT of MNK-010. The secondary objectives are to characterize the PK profile of docetaxel, the liposomal components (DSPE-PEG[2000]) and docetaxel prodrug (MP-3528) and preliminary anti-tumor activity of MNK-010.Twelve dose levels are planned: 3, 6, 12, 24, 48, 80, 120, 160, 190, 225, 270, and 320 mg/m2 Dosing at 160 mg/m2 is underway. The recommended phase II dose will be administered to 20 patients with metastatic SCCHN to further evaluate the safety, PK profile, and preliminary antitumor activity of MNK-010.

Results: 25 subjects have received at least one dose of MNK-010 for a total of 106 cycles administered. Efficacy results include six stable diseases (SDs) in tumor types including thymic cancer, NSCLC, prostate, ovarian, cervical and gastroesophageal cancer. Safety data shows that MNK-010 is well tolerated at doses up to 120 mg/m2. The major drug related adverse events reported are nausea, vomiting and fatigue.

The Clearance (CL), volume of distribution (Vss), half-life (t1/2), peak level (Cmax) and extent of exposure (AUC) values are comparable between DSPE(PEG-2000) and MP-3528. The CL (∼ 0.026 L/h/m2) and Vss (∼ 1.6 L/m2) of MNK-010 are very low, with the mean t1/2 being about 60h. Cmax and AUC demonstrate dose proportionality and linearity for MP-3528, DSPE(PEG-2000) and docetaxel. The dose normalized Cmax of docetaxel released from MNK-010 is about nine-fold lower relative to a comparable dose of Taxotere.

Conclusion: MNK-010 is well tolerated up to doses of 120 mg/m2. Stable diseases have been observed in several tumor types.

Citation Format: Louise S. Rochon, Krishna Devarakonda, Jose Martinez, Kelly Williams, Erika P. Hamilton, Geoffrey Shapiro, Ammar Sukari. A phase I first in human dose escalation trial of MNK-010 in subjects with advanced solid tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT230. doi:10.1158/1538-7445.AM2015-CT230

Clinical Course of acute-on-chronic liver failure syndrome and effects on prognosis

Acute-on-chronic liver failure (ACLF) is characterized by acute decompensation (AD) of cirrhosis, organ failure(s), and high 28-day mortality. We investigated whether assessments of patients at specific time points predicted their need for liver transplantation (LT) or the potential futility of their care. We assessed clinical courses of 388 patients who had ACLF at enrollment, from February through September 2011, or during early (28-day) follow-up of the prospective multicenter European Chronic Liver Failure (CLIF) ACLF in Cirrhosis study. We assessed ACLF grades at different time points to define disease resolution, improvement, worsening, or steady or fluctuating course. ACLF resolved or improved in 49.2%, had a steady or fluctuating course in 30.4%, and worsened in 20.4%. The 28-day transplant-free mortality was low-to-moderate (6%-18%) in patients with nonsevere early course (final no ACLF or ACLF-1) and high-to-very high (42%-92%) in those with severe early course (final ACLF-2 or -3) independently of initial grades. Independent predictors of course severity were CLIF Consortium ACLF score (CLIF-C ACLFs) and presence of liver failure (total bilirubin ≥12 mg/dL) at ACLF diagnosis. Eighty-one percent had their final ACLF grade at 1 week, resulting in accurate prediction of short- (28-day) and mid-term (90-day) mortality by ACLF grade at 3-7 days. Among patients that underwent early LT, 75% survived for at least 1 year. Among patients with ≥4 organ failures, or CLIF-C ACLFs >64 at days 3-7 days, and did not undergo LT, mortality was 100% by 28 days.

CONCLUSIONS

Assessment of ACLF patients at 3-7 days of the syndrome provides a tool to define the emergency of LT and a rational basis for intensive care discontinuation owing to futility.

The Big Impact of Small Groups on College Drinking

College drinking is a problem with severe academic, health, and safety consequences. The underlying social processes that lead to increased drinking activity are not well understood. Social Norms Theory is an approach to analysis and intervention based on the notion that students' misperceptions about the drinking culture on campus lead to increases in alcohol use. In this paper we develop an agent-based simulation model, implemented in MATLAB, to examine college drinking. Students' drinking behaviors are governed by their identity (and how others perceive it) as well as peer influences, as they interact in small groups over the course of a drinking event. Our simulation results provide some insight into the potential effectiveness of interventions such as social norms marketing campaigns.

Orthostatic hypotension in Parkinson disease: how much you fall or how low you go?

Orthostatic hypotension (OH) is frequent in patients with Parkinson's disease (PD) and can occur with or without symptoms. Pharmacological treatments are effective, but often exacerbate supine hypertension. Guidelines exist for the diagnosis, but not for the treatment of OH. We examined the relationship between blood pressure (BP) and symptoms in a cohort of PD patients with the goal of identifying a hemodynamic target to guide treatment. We measured BP supine and upright (tilt or active standing) and identified the presence or absence of symptomatic OH by using a validated patient-reported outcome questionnaire in 210 patients with PD. We evaluated the usefulness of the 20/10 and 30/15 mmHg diagnostic criteria (systolic/diastolic) to identify symptomatic OH. Fifty percent of the PD patient cohort met criteria for the 20/10 fall and 30% for the 30/15 BP fall. Among the patients who met either OH criteria, the percentage of those with symptoms was small (33% of those with 20/10 and 44% of those with 30/15 mmHg; 16% and 13%, respectively, overall). Symptomatic OH was associated with an upright mean BP below 75 mmHg. A mean standing BP <75 mmHg had a sensitivity of 97% and a specificity of 98% for detecting symptomatic OH. Although the prevalence of OH in PD is high, not all patients have symptoms of organ hypoperfusion. A mean standing BP below 75 mmHg appears to be a useful benchmark when deciding whether the benefits of initiating pharmacological treatment of OH outweigh the risks of exacerbating supine hypertension.