18F-fluoro-deoxy-glucose focal uptake in very small pulmonary nodules: fact or artifact? Case reports

ABSTRACT: BACKGROUND: F-fluoro-deoxy-glucose (18F-FDG) positron emission tomography integrated/combined with computed tomography (PET-CT) provides the best diagnostic results in the metabolic characterization of undetermined solid pulmonary nodules. The diagnostic performance of 18F-FDG is similar for nodules measuring at least 1 cm and for larger masses, but few data exist for nodules smaller than 1 cm. CASE PRESENTATION: We report five cases of oncologic patients showing focal lung 18F-FDG uptake on PET-CT in nodules smaller than 1 cm. We also discuss the most common causes of 18F-FDG false-positive and false-negative results in the pulmonary parenchyma. In patient 1, contrast-enhanced CT performed 10 days before PET-CT did not show any abnormality in the site of uptake; in patient 2, high-resolution CT performed 1 month after PET showed a bronchiole filled with dense material interpreted as a mucoid impaction; in patient 3, contrast-enhanced CT performed 15 days before PET-CT did not identify any nodules; in patients 4 and 5, contrast-enhanced CT revealed a nodule smaller than 1 cm which could not be characterized. The 18F-FDG uptake at follow-up confirmed the malignant nature of pulmonary nodules smaller than 1 cm which were undetectable, misinterpreted, not recognized or undetermined at contrast-enhanced CT. CONCLUSION: In all five oncologic patients, 18F-FDG was able to metabolically characterize as malignant those nodules smaller than 1 cm, underlining that: 18F-FDG uptake is not only a function of tumor size but it is strongly related to the tumor biology; functional alterations may precede morphologic abnormalities. In the oncologic population, especially in higher-risk patients, PET can be performed even when the nodules are smaller than 1 cm, because it might give an earlier characterization and, sometimes, could guide in the identification of alterations missed on CT

Predicting protein-protein binding sites in membrane proteins

<p>Abstract</p> <p>Background</p> <p>Many integral membrane proteins, like their non-membrane counterparts, form either transient or permanent multi-subunit complexes in order to carry out their biochemical function. Computational methods that provide structural details of these interactions are needed since, despite their importance, relatively few structures of membrane protein complexes are available.</p> <p>Results</p> <p>We present a method for predicting which residues are in protein-protein binding sites within the transmembrane regions of membrane proteins. The method uses a Random Forest classifier trained on residue type distributions and evolutionary conservation for individual surface residues, followed by spatial averaging of the residue scores. The prediction accuracy achieved for membrane proteins is comparable to that for non-membrane proteins. Also, like previous results for non-membrane proteins, the accuracy is significantly higher for residues distant from the binding site boundary. Furthermore, a predictor trained on non-membrane proteins was found to yield poor accuracy on membrane proteins, as expected from the different distribution of surface residue types between the two classes of proteins. Thus, although the same procedure can be used to predict binding sites in membrane and non-membrane proteins, separate predictors trained on each class of proteins are required. Finally, the contribution of each residue property to the overall prediction accuracy is analyzed and prediction examples are discussed.</p> <p>Conclusion</p> <p>Given a membrane protein structure and a multiple alignment of related sequences, the presented method gives a prioritized list of which surface residues participate in intramembrane protein-protein interactions. The method has potential applications in guiding the experimental verification of membrane protein interactions, structure-based drug discovery, and also in constraining the search space for computational methods, such as protein docking or threading, that predict membrane protein complex structures.</p

Increased toxicity of methamphetamine in morphine-dependent mice

. The effect of methamphetamine on morphine-dependent mice was investigated by calculating the LD50 (i.p.), measuring motor activity, anorectic actions, and body temperature. 2. Methamphetamine was more toxic in morphine-dependent mice (LD50 = 20.6 mg/kg) than in normal mice (LD50 = 43.2 mg/kg). 3. Methamphetamine-induced locomotor activity was greater in morphinized than in nonmorphinized mice at doses of 2.5 and 5 mg/kg i.p. 4. Methamphetamine also increased the body temperature of morphinized mice more than that of normal mice (P < 0.05). 5. These findings suggest that methamphetamine is more toxic in morphine-dependent than in nondependent mice

Abstract B2-13: AU-rich expression in invasive ductal breast cancer: A systems biology approach in post-transcriptional regulation

Abstract AU-Rich element (ARE)-dependent post-transcriptional regulation mechanisms are increasingly emerging as key regulators that are influencing our perception of aberrant gene expression in cancer. AREs are instability determinant sequences located in the 3' UTR of mRNAs and are fundamental to the maintenance of transient expression of gene products that regulate various cellular functions such as cell proliferation, apoptosis, inflammation and immunity. Here we used a systems biology approach to examine the patterns of ARE-containing gene expression that is perturbed in invasive ductal breast cancer (IDBC). Based on IDBC mRNA expression profiles obtained from The Cancer Genome Atlas (TCGA) database, we intersected 2396 over-expressed genes with the AU-rich element database (ARED) and found that 414 comprise IDBC upregulated ARE-containing genes. Functional classification using the gene ontology tool, DAVID, showed the highest enrichment of ARE-genes in IDBC in chromosome segregation (5-fold, p&amp;lt;0.001). AREs are recognized by RNA binding proteins such as tristetraprolin (TTP, ZFP36), that targets mRNAs for decay, and HuR (ELAVL1), an mRNA stabilizing protein. Abnormal expression patterns of both these proteins, i.e. TTP deficiency coupled with HuR overexpression, are found in many cancers leading to prolonged expression of factors contributing to the maintenance and progression of tumors. We examined the relationship between the IDBC ARE-genes, TTP and HuR expression and the TTP/HuR ratio by looking at their correlations (R-values) with each other. Results indicated that the upregulated ARE-genes have a greater tendency to correlate with low TTP and elevated HuR expression than non-ARE genes. Using clustering assessment, we derived an 11-gene cluster from the 414 that function in chromosome positioning and segregation and mitotic kinase activity. The genes are CDC6, CENPA, CENPA, KIF11, KIF18A, NCAPG, NEK2, NUF2, PBK, PRC1, and TOP2A and their mRNA expression correlates negatively with the TTP/HuR ratio, i.e. their mRNA expression increases as TTP is deficient and HuR is simultaneously elevated (r = -0.53 to -0.66). Examination of the mRNA expression patterns of the 11 genes in the invasive breast cancer cell line MDA-MB-231 compared to MCF-7 cells and normal-like mammary cell lines, MCF10A and MCF12A showed that all of these genes were increased in MDA-MB-231 cell line compared to MCF10A by at least 2-fold (p&amp;lt;0.001). Immunoprecipitation of TTP protein in MDA-MB-231 cells followed by examination of associated mRNAs showed that 7 of the 11 gene-products were significantly associated with TTP (greater than 2-fold, p&amp;lt;0.01) compared to the control suggesting post-transcriptional regulation by TTP. Moreover, reporter experiments confirmed the functionally of the AREs. Upon examining the METBRIC breast cancer database, a larger database, we found that not only do the 11 chromosomal segregation genes overexpress, they also tend to be upregulated simultaneously in the same patients indicating that they participate in common regulatory mechanisms. Furthermore, the 11-gene cluster also correlates negatively with the TTP/HuR ratio further alluding to TTP regulation. Kaplan Meier survival analysis demonstrated a higher likelihood (1.6 times) of death due to co-overexpression of the 11 genes compared with a lower-expressing cohort. The data presented here suggest novel regulatory mechanisms related to mitosis and cellular proliferation that might be targeted by the mRNA decay-promoting protein TTP. Moreover, TTP deficiency in IDBC may, at least in part, be responsible for the aberrantly prolonged expression of factors that actively participate in chromosomal segregation and in turn, lead to enhanced maintenance and progression of tumors. Citation Format: Norah A. Alsouhibani, Edward Hitti, Tala Bakheet, Khalid SA Khabar. AU-rich expression in invasive ductal breast cancer: A systems biology approach in post-transcriptional regulation. [abstract]. In: Proceedings of the AACR Special Conference on Computational and Systems Biology of Cancer; Feb 8-11 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 2):Abstract nr B2-13.</jats:p

Reversal of cisplatin-induced carnitine deficiency and energy starvation by propionyl-L-carnitine in rat kidney tissues

The present study examined whether propionyl-L-carnitine (PLC) could prevent the development of cisplatin (CDDP)-induced acute renal failure in rats. 2. Forty adult male Wistar albino rats were divided into four groups. Rats in the first group were injected daily with normal saline (2.5 mL/kg, i.p.) for 10 consecutive days, whereas the second group received PLC (250 mg/kg, i.p.) for 10 consecutive days. Animals in the third group were injected daily with normal saline for 5 consecutive days before and after a single dose of CDDP (7 mg/kg, i.p.). Rats in the fourth group received a combination of PLC (250 mg/kg, i.p.) for 5 consecutive days before and after a single dose of CDDP (7 mg/kg, i.p.). On Day 6 following CDDP treatment, animals were killed and serum and kidneys were isolated for analysis. 3. Injection of CDDP resulted in a significant increase in serum creatinine, blood urea nitrogen (BUN), thiobarbituric acid-reactive substances (TBARS) and total nitrate/nitrite (NOx), as well as a significant decrease in reduced glutathione (GSH), total carnitine, ATP and ATP/ADP in kidney tissues. 4. Administration of PLC significantly attenuated the nephrotoxic effects of CDDP, manifested as normalization of the CDDP-induced increase in serum creatinine, BUN, TBARS and NOx and the CDDP-induced decrease in total carnitine, GSH, ATP and ATP/ADP in kidney tissues. 5. Histopathological examination of kidney tissues from CDDP-treated rats showed severe nephrotoxicity, in which 50-75% of glomeruli and renal tubules exhibited massive degenerative changes. Interestingly, administration of PLC to CDDP-treated rats resulted in a significant improvement in glomeruli and renal tubules, in which less than 25% of glomeruli and renal tubules exhibited focal necrosis. 6. Data from the present study suggest that PLC prevents the development of CDDP-induced acute renal injury by a mechanism related, at least in part, to the ability of PLC to increase intracellular carnitine content, with a consequent improvement in mitochondrial oxidative phosphorylation and energy production, as well as its ability to decrease oxidative stress. This will open new perspectives for the use of PLC in the treatment of renal diseases associated with or secondary to carnitine deficiency

Progression of diethylnitrosamine-induced hepatic carcinogenesis in carnitine-depleted rats

AIM: To investigate whether carnitine deficiency is a risk factor during the development of diethylnitrosamine (DENA)-induced hepatic carcinogenesis. METHODS: A total of 60 male Wistar albino rats were divided into six groups with 10 animals in each group. Rats in group I (control group) received a single intraperitoneal (i.p.) injection of normal saline. Animals in group 2 (carnitine-supplemented group) were given L-carnitine (200 mg/kg per day) in drinking water for 8 wk. Animals in group 3 (carnitine-depleted group) were given D-carnitine (200 mg/kg per day) and mildronate (200 mg/kg per day) in drinking water for 8 wk. Rats in group 4 (DENA group) were injected with a single dose of DENA (200 mg/kg, i.p.) and 2 wk later received a single dose of carbon tetrachloride (2 mL/kg) by gavage as 1:1 dilution in corn oil. Animals in group 5 (DENA-carnitine depleted group) received the same treatment as group 3 and group 4. Rats in group 6 (DENA-carnitine supplemented group) received the same treatment as group 2 and group 4.RESULTS: Administration of DENA resulted in a significant increase in alanine transaminase (ALT), gamma-glutamyl transferase (G-GT), alkaline phosphatase (ALP), total bilirubin, thiobarbituric acid reactive substances (TBARS) and total nitrate/ nitrite (NOx) and a significant decrease in reduced glutathione (GSH), glutathione peroxidase (GSHPx), catalase (CAT) and total carnitine content in liver tissues. In the carnitine-depleted rat model, DENA induced a dramatic increase in serum ALT, G-GT, ALP and total bilirubin, as well as a progressive reduction in total carnitine content in liver tissues. Interestingly, L-carnitine supplementation resulted in a complete reversal of the increase in liver enzymes, TBARS and NOx, and a decrease in total carnitine, GSH, GSHPx, and CAT induced by DENA, compared with the control values. Histopathological examination of liver tissues confirmed the biochemical data, where L-carnitine prevented DENA-induced hepatic carcinogenesis while D-carnitine-mildronate aggravated DENA-induced hepatic damage.CONCLUSION: Data from this study suggest for the first time that: (1) carnitine deficiency is a risk factor and should be viewed as a mechanism in DENA-induced hepatic carcinogenesis; (2) oxidative stress plays an important role but is not the only cause of DENA-induced hepatic carcinogenesis; and (3) long-term L-carnitine supplementation prevents the development of DENA-induced liver cancer. (C) 2009 The WIG Press and Baishideng. All rights reserved