Frequency of polymorphisms in the CYP2C9, VKORC1, and CYP4F2 genes related to the metabolism of Warfarin in healthy donors from Cali, Colombia.

Alleles in the VKORC1, CYP2C9, and CYP4F2 genes can influence Warfarin dose requirement. We aimed to determine the frequency of the polymorphisms in these genes in healthy individuals from Cali, Colombia. Observational study where total blood was collected from 107 healthy donors who attended a higher educational institution in Cali, Colombia. Sanger sequencing of exons 2, 3, 5, and 7 of the CYP2C9 gene; the common promoter region of CYP (rs12777823); exon 11 of CPY4F2 and the polymorphism c.-1639G > A in the VKORC1 gene promoter was performed. CYP2C9*2, CYP2C9*3, CYP2C9*8, CYP2C9*9, CYP2C9*11, CYP4F2*3, rs12777823, and VKORC1*2 were detected. The latter had the highest frequency with 80 (74.8%) participants in a heterozygous or homozygous state. The least frequent allele was CYP2C9*11 with only 1 carrier. Combined haplotypes (VKORC1 *1/*2 or *2/*2 and CYP2C9 *1/*2 or *2/*2) were identified in 14 (13.7%) subjects. Both frequencies found in the VKORC1 and CYP2C9 alleles were similar to the ones reported for Latin Americans of European and Native American Ancestry. VKORC1*2 allele, the main genetic contributor to Warfarin dosing requirement, was the variant with the highest frequency (74.8% subjects, with a frequency of the alternative allele (A) of 50%). Our findings provide researchers with a greater insight regarding the frequency of common polymorphisms that affect anticoagulation treatment in the Cali (Colombia) population.

New Amino Naphthoquinone Derivatives as Anti-Trypanosoma cruzi Agents Targeting Trypanothione Reductase.

To develop novel chemotherapeutic alternatives for the treatment of Chagas disease, in this study, a set of new amino naphthoquinone derivatives were synthesised and evaluated in vitro on the epimastigote and trypomastigote forms of Trypanosoma cruzi strains (NINOA and INC-5) and on J774 murine macrophages. The design of the new naphthoquinone derivatives considered the incorporation of nitrogenous fragments with different substitution patterns present in compounds with activity on T. cruzi, and, thus, 19 compounds were synthesised in a simple manner. Compounds 2e and 7j showed the lowest IC50 values (0.43 µM against both strains for 2e and 0.19 µM and 0.92 µM for 7j). Likewise, 7j was more potent than the reference drug, benznidazole, and was more selective on epimastigotes. To postulate a possible mechanism of action, molecular docking studies were performed on T. cruzi trypanothione reductase (TcTR), specifically at a site in the dimer interface, which is a binding site for this type of naphthoquinone. Interestingly, 7j was one of the compounds that showed the best interaction profile on the enzyme; therefore, 7j was evaluated on TR, which behaved as a non-competitive inhibitor. Finally, 7j was predicted to have a good pharmacokinetic profile for oral administration. Thus, the naphthoquinone nucleus should be considered in the search for new trypanocidal agents based on our hit 7j.

NaTrxh is an essential protein for pollen rejection in Nicotiana by increasing S-RNase activity.

In self-incompatible Solanaceae, the pistil protein S-RNase contributes to S-specific pollen rejection in conspecific crosses, as well as to rejecting pollen from foreign species or whole clades. However, S-RNase alone is not sufficient for either type of pollen rejection. We describe a thioredoxin (Trx) type h from Nicotiana alata, NaTrxh, which interacts with and reduces S-RNase in vitro. Here, we show that expressing a redox-inactive mutant, NaTrxhSS , suppresses both S-specific pollen rejection and rejection of pollen from Nicotiana plumbaginifolia. Biochemical experiments provide evidence that NaTrxh specifically reduces the Cys155 -Cys185 disulphide bond of SC10 -Rnase, resulting in a significant increase of its ribonuclease activity. This reduction and increase in S-RNase activity by NaTrxh helps to explain why S-RNase alone could be insufficient for pollen rejection.

Selection of Functional Quorum Sensing Systems by Lysogenic Bacteriophages in Pseudomonas aeruginosa.

Quorum sensing (QS) in Pseudomonas aeruginosa coordinates the expression of virulence factors, some of which are used as public goods. Since their production is a cooperative behavior, it is susceptible to social cheating in which non-cooperative QS deficient mutants use the resources without investing in their production. Nevertheless, functional QS systems are abundant; hence, mechanisms regulating the amount of cheating should exist. Evidence that demonstrates a tight relationship between QS and the susceptibility of bacteria against the attack of lytic phages is increasing; nevertheless, the relationship between temperate phages and QS has been much less explored. Therefore, in this work, we studied the effects of having a functional QS system on the susceptibility to temperate bacteriophages and how this affects the bacterial and phage dynamics. We find that both experimentally and using mathematical models, that the lysogenic bacteriophages D3112 and JBD30 select QS-proficient P. aeruginosa phenotypes as compared to the QS-deficient mutants during competition experiments with mixed strain populations in vitro and in vivo in Galleria mellonella, in spite of the fact that both phages replicate better in the wild-type background. We show that this phenomenon restricts social cheating, and we propose that temperate phages may constitute an important selective pressure toward the conservation of bacterial QS.

Repurposing the anticancer drug mitomycin C for the treatment of persistent Acinetobacter baumannii infections.

Acinetobacter baumannii is an emergent opportunistic bacterial pathogen responsible for recalcitrant infections owing to its high intrinsic tolerance to most antibiotics; therefore, suitable strategies to treat these infections are needed. One plausible approach is the repurposing of drugs that are already in use. Among them, anticancer drugs may be especially useful due their cytotoxic activities and ample similarities between bacterial infections and growing tumours. In this work, the effectiveness of four anticancer drugs on the growth of A. baumannii ATTC BAA-747 was evaluated, including the antimetabolite 5-fluorouracil and three DNA crosslinkers, namely cisplatin, mitomycin C (MMC) and merphalan. MMC was the most effective drug, having a minimum inhibitory concentration for 50% of growth in Luria-Bertani medium at ca. 7 µg/mL and completely inhibiting growth at 25 µg/mL. Hence, MMC was tested against a panel of 21 clinical isolates, including 18 multidrug-resistant (MDR) isolates, 3 of which were sensitive only to colistin. The minimum inhibitory concentrations and minimum bactericidal concentrations of MMC in all tested strains were found to be similar to those of A. baumannii ATCC BAA-747, and MMC also effectively killed stationary-phase, persister and biofilm cells. Moreover, MMC was able to increase survival of the insect larvae Galleria mellonella against an otherwise lethal A. baumannii infection from 0% to ≥53% for the antibiotic-sensitive A. baumannii ATCC BAA-747 strain and the MDR strains A560 and A578. Therefore, MMC is highly effective at killing the emergent opportunistic pathogen A. baumannii.

Alda-1 modulates the kinetic properties of mitochondrial aldehyde dehydrogenase (ALDH2).

Mitochondrial aldehyde dehydrogenase (ALDH2) has been proposed as a key enzyme in cardioprotection during ischemia-reperfusion processes. This proposal led to the search for activators of ALDH2 with the aim to develop cardioprotective drugs. Alda-1 was the first activator of ALDH2 identified and its cardioprotective effect has been extensively proven in vivo; however, the mechanism of activation is not fully understood. A crystallographic study showed that Alda-1 binds to the entrance of the aldehyde-binding site; therefore, Alda-1 should in essence be an inhibitor. In the present study, kinetic experiments were performed to characterize the effect of Alda-1 on the properties of ALDH2 (kinetic parameters, determination of the rate-limiting step, reactivity of the catalytic cysteine) and on the kinetic mechanism (type of kinetics, sequence of substrates entering, and products release). The results showed that Alda-1 dramatically modifies the properties of ALDH2, the Km for NAD+ decreased by 2.4-fold, and the catalytic efficiency increased 4.4-fold; however, the Km for the aldehyde increased 8.6-fold, thus, diminishing the catalytic efficiency. The alterations in these parameters resulted in a complex behavior, where Alda-1 acts as inhibitor at low concentrations of aldehyde and as an activator at high concentrations. Additionally, the binding of Alda-1 to ALDH2 made the deacylation less limiting and diminished the pKa of the catalytic cysteine. Finally, NADH inhibition patterns indicated that Alda-1 induced a change in the sequence of substrates entry and products release, in agreement with the proposal of both substrates entering ALDH2 by the NAD+ entrance site.

Tamoxifen, an anticancer drug, is an activator of human aldehyde dehydrogenase 1A1.

The modulation of aldehyde dehydrogenase (ALDH) activity has been suggested as a promising option for the prevention or treatment of many diseases. To date, only few activating compounds of ALDHs have been described. In this regard, N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide has been used to protect the heart against ischemia/reperfusion damage. In the search for new modulating ALDH molecules, the binding capability of different compounds to the active site of human aldehyde dehydrogenase class 1A1 (ALDH1A1) was analyzed by molecular docking, and their ability to modulate the activity of the enzyme was tested. Surprisingly, tamoxifen, an estrogen receptor antagonist used for breast cancer treatment, increased the activity and decreased the Km for NAD(+) by about twofold in ALDH1A1. No drug effect on human ALDH2 or ALDH3A1 was attained, showing that tamoxifen was specific for ALDH1A1. Protection against thermal denaturation and competition with daidzin suggested that tamoxifen binds to the aldehyde site of ALDH1A1, resembling the interaction of N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide with ALDH2. Further kinetic analysis indicated that tamoxifen activation may be related to an increase in the Kd for NADH, favoring a more rapid release of the coenzyme, which is the rate-limiting step of the reaction for this isozyme. Therefore, tamoxifen might improve the antioxidant response, which is compromised in some diseases.

Envelope analysis of the airflow signal to improve polysomnographic assessment of sleep disordered breathing.

STUDY OBJECTIVES: Given the detailed respiratory waveform signal provided by the nasal cannula in polysomnographic (PSG) studies, to quantify sleep breathing disturbances by extracting a continuous variable based on the coefficient of variation of the envelope of that signal. DESIGN: Application of an algorithm for envelope analysis to standard nasal cannula signal from actual polysomnographic studies. SETTING: PSG recordings from a sleep disorders center were analyzed by an algorithm developed on the Igor scientific data analysis software. PATIENTS OR PARTICIPANTS: Recordings representative of different degrees of sleep disordered breathing (SDB) severity or illustrative of the covariation between breathing and particularly relevant factors and variables. INTERVENTIONS: The method calculated the coefficient of variation of the envelope for each 30-second epoch. The normalized version of that coefficient was defined as the respiratory disturbance variable (RDV). The method outcome was the all-night set of RDV values represented as a time series. MEASUREMENTS AND RESULTS: RDV quantitatively reflected departure from normal sinusoidal breathing at each epoch, providing an intensity scale for disordered breathing. RDV dynamics configured itself in recognizable patterns for the airflow limitation (e.g., in UARS) and the apnea/hypopnea regimes. RDV reliably highlighted clinically meaningful associations with staging, body position, oximetry, or CPAP titration. CONCLUSIONS: Respiratory disturbance variable can assess sleep breathing disturbances as a gradual phenomenon while providing a comprehensible and detailed representation of its dynamics. It may thus improve clinical diagnosis and provide a revealing descriptive tool for mechanistic sleep disordered breathing modeling. Respiratory disturbance variable may contribute to attaining simplified screening methodologies, novel diagnostic criteria, and insightful research tools.

Recurrent parathyroid carcinoma appearing as FDG negative but MIBI positive.

A 44-year-old woman with recurrent parathyroid carcinoma (PTC) presents with moderately elevated parathyroid hormone and ionized calcium levels. Dual-phase Tc-MIBI SPECT study of the neck and chest demonstrated 2 new foci in keeping with neoplastic seeding. A restaging whole-body F-FDG PET/CT showed no evidence of FDG uptake in the region of the MIBI-positive foci or any evidence of distant metastases. The role of F-FDG PET/CT for imaging PTC is still somewhat limited because of the rarity of this disease. We present a case highlighting a potential pitfall for FDG PET in detecting PTC.

Gastric neuroendocrine carcinoma staged and followed with (18)F-FDG PET/CT--a report of 3 cases.

Gastric neuroendocrine carcinomas (NEC) are very rare, aggressive tumors of the stomach that are distinct from the more benign neuroendocrine tumors, sometimes referred to as "gastric carcinoids." We present 3 cases of gastric NEC representing various histological subtypes that were successfully staged and followed with F-FDG PET/CT, impacting therapeutic management in each case.

Spectrum of malignant renal and urinary bladder tumors on 18F-FDG PET/CT: a pictorial essay.

A wide variety of malignant renal and urinary bladder diseases can be detected on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas was to demonstrate that the spectrum of renal and urinary bladder malignancy that can be evaluated with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the variety of urological tumor types that can be detected on PET/CT and some of the patterns of (18)F-FDG uptake that can be observed in these cases.

Spectrum of gastric malignancy on 18F-FDG PET/CT: a pictorial essay.

A wide variety of malignant gastric diseases can be detected, staged, and followed on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific and some can be seen in certain benign gastric diseases, the aim of this atlas was to demonstrate that the wide histological spectrum of gastric tumors that can be evaluated, staged, and followed with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the utility of PET/CT in these tumors and the imaging characteristics and patterns of (18)F-FDG uptake that can be demonstrated in these cases.

The utility of Xenon-133 liver scan in the diagnosis and management of nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is an important and common condition affecting approximately 20% of the general population. Given the limitation of radiological investigations, diagnosis often requires a liver biopsy. OBJECTIVE: To compare Xenon-133 (Xe-133) liver scanning with ultrasonography in the diagnosis of NAFLD. METHODS: From January 2003 to February 2007, 258 consecutive patients with suspected NAFLD underwent Xe-133 liver scanning at Royal Victoria Hospital (Montreal, Quebec). Of these, 43 patients underwent ultrasonography and liver biopsy for the evaluation of NAFLD. Patients with other liver diseases and significant alcohol consumption were excluded. Two nuclear medicine physicians assessed liver Xe-133 uptake and measured the grade of steatosis using a standardized protocol. The degree of steatosis was determined from biopsy specimens assessed by two hepatopathologists. RESULTS: NAFLD was identified by liver biopsy in 35 of 43 patients (81.4%). Xe-133 scan demonstrated 94.3% sensitivity (95% CI 81.4% to 98.4%) and 87.5% specificity (95% CI 52.9% to 99.4%) for the presence of NAFLD. The positive and negative predictive values for detection of steatosis by Xe-133 scan were 97.1% (95% CI 85.1% to 99.8%) and 77.8% (95% CI 45.3% to 93.7%), respectively. The positive and negative likelihood ratios were 7.54 (95% CI 1.20 to 47.26) and 0.07 (95% CI 0.02 to 0.26), respectively. Two patients with NAFLD (5.7%) who had a negative Xe-133 scan result had histologically mild steatosis (<10%). The grade of steatosis on liver biopsy was highly correlated with the results of the Xe-133 scan (r=0.87; P<0.001). The sensitivity and specificity of ultrasound in diagnosing steatosis were 62.9% and 75%, respectively. CONCLUSION: Xe-133 liver scan proved to be a safe, reliable, noninvasive method for diagnosing and quantifying hepatic steatosis, and was superior to ultrasound.

Spectrum of malignant pleural and pericardial disease on FDG PET/CT.

OBJECTIVE: The purpose of this article is to illustrate a wide spectrum of malignant primary and secondary pleural and pericardial diseases imaged with (18)F-FDG PET/CT. CONCLUSION: A wide variety of malignant pleural and pericardial diseases can be detected, staged, and monitored by FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas is to show that the spectrum of pleural and pericardial disease that can be evaluated with PET/CT is much broader than current literature would suggest. PET/CT readers and oncologists should be aware of the wide variety of malignancies that can affect the pleura and pericardium and some of the patterns of FDG uptake that can be observed in these cases.

Giant Cell Tumor Pulmonary Metastases Mimic Primary Malignant Pulmonary Nodules on (18)F-FDG PET/CT.

A 59-year-old man with a 30-year history of multiple recurrences of a giant cell tumor (GCT) of the left knee was referred for an (18)F-FDG PET/CT to evaluate a solitary pulmonary nodule. The nodule was mildly FDG-avid, raising suspicion of malignancy. It was excised and histologically proven to be a GCT pulmonary metastasis. A follow-up PET/CT done 2 years later revealed a new, larger lung mass that was more intensely FDG-avid, but of the same histology. This rare report highlights a pitfall in the evaluation of solitary pulmonary lesions by (18)F-FDG PET/CT in patients with GCT of the bone.

Extramedullary gastric relapse of acute lymphoblastic leukemia following allogeneic stem cell transplant: staging with F-18 FDG PET/CT.

A 26-year-old man with a prior history of acute leukemia that was treated with a stem cell transplant (SCT) was referred for an F-18 FDG PET/CT to assess suspicious new gastric mucosal lesions. The lesions were FDG-avid and were histologically proven to be acute lymphoblastic leukemia (ALL). Extramedullary relapse of ALL after SCT is very rare, with only 60 cases reported in the literature, and the role of F-18 FDG PET/CT in monitoring for ALL relapse following SCT has not been previously investigated. This rare case report highlights the use of F-18 FDG PET/CT in staging gastric relapse of ALL following SCT.

Incidental papillary thyroid carcinoma in a patient presenting with Graves' hyperthyroidism and concomitant obstructive sequestered intrathoracic multinodular goiter.

A previously healthy 27-year-old woman presented with a thyroid goiter, symptoms of thyrotoxicosis, and mild respiratory obstruction. The serum thyroid stimulating hormone (TSH) was suppressed, serum T4 was elevated, and 24-hour radioiodine uptake was elevated at 59%. Thyroid scintigraphy showed intense uptake in an enlarged gland, with a cold nodule on the right, and a large isolated mass in the mediastinum, with very mild uptake. Total thyroidectomy and excision of the mediastinal mass revealed multiple pathologies: Graves disease in the thyroid gland with an incidental papillary thyroid carcinoma, and a benign sequestered intrathoracic multinodular goiter. Thyroid carcinoma can develop in a gland affected by Graves disease, however, the presence of concomitant sequestered intrathoracic thyroid tissue unaffected by Graves disease is highly unusual and has not been previously described. We present the scintigraphic findings, and several theories that could help explain these findings.