Amperometric biosensors based on biotinylated single-walled carbon nanotubes

One challenging goal for the development of biosensors is the conception of three dimensional biostructures on electrode surfaces. In this context, single-walled carbon nanotube coatings (SWCNTs), functionalized by biotin groups, were investigated to develop 3D conductive nanostructures allowing a post-functionalization by biological macromolecules. This specific anchoring of biomolecules was carried via the affinity interactions using the avidin-biotin system. For this purpose, a biotinylated pyrene was specially synthesized to develop a non-covalent functionalization based on pi-interactions between pyrene and the nanotube sidewall. SWCNT coatings were also biotinylated via electropolymerization of biotin-pyrrole derivatives at 0.95 V in CH3CN electrolyte. The resulting biotinylated SWCNTs were modified by an avidin protein via affinity interactions and characterized with scanning electron microscopy. The biofunctionalization by a biotinylated glucose oxidase (GOX) was performed by successive incubation in avidin and GOX aqueous solutions via avidin bridges. The efficiency of the enzyme anchoring was examined through the electro-enzymatic activity of the modified electrodes towards the detection of glucose at 0.7 V versus SCE. The glucose sensitivity and maximum current density were 1.6 mAM(-1) cm(-2) and 131 microAcm(-2) respectively for pyrene biotin-SWCNT electrode and 2.5 mAM(-1) cm(-2) and 178 microAcm(-2) respectively for the poly(pyrrole biotin)-SWCNT.

Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia

BACKGROUND AND PURPOSE

There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries.

EXPERIMENTAL APPROACH

Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1.

KEY RESULTS

HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO.

CONCLUSIONS AND IMPLICATIONS

Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.

Genetic diversity of grapevine accessions from Iran, Russia and USA using microsatellite markers

To discover marker information content and differentiation among grapevine accessions from Iran, USA and Russia, nine microsatellite markers were used. A total of 75 alleles were detected, giving a mean of 8.3 alleles per 9 loci. The total number of alleles per locus varied between 6 to 11 and the polymorphism information content ranged from 0.65 to 0.88, indicating that these loci were highly informative. A positive correlation (r = 0.870) was observed between the number of alleles and the level of polymorphism. Two SSRs loci including SSrVrZAG47 and VVMD27 were found to be probably synonymous. Gene diversities were high in all populations with values ranging from 0.709 to 0.784. In all populations, the mean number (averaged over loci) of heterozygous individuals was higher than expected. PCO analysis could not be so clearly differentiated accessions from Iran and Russia. The pattern of clustering of the Vitis vinifera populations was according to their geographic distribution. It is suggested that accessions could possibly be assigned to their regions of origin according to their genotypes.

Constitutive c-Met phosphorylation mediates growth in the absence of EGFR kinase activity in breast cancer cells dependent on EGFR expression for growth

Abstract #4059

Breast cancers are not responsive to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) even though 30% of breast cancers overexpress the EGFR. We have observed that EGFR remains tyrosine phosphorylated in breast cancer cells that do not require EGFR kinase activity for growth, yet express high levels of EGFR. In one such cell line, SUM229, we found that this EGFR kinase-independent EGFR tyrosine phosphorylation encompasses all of the tyrosine phosphorylation sites of the EGFR for which antibodies are available, with the exception of tyrosine 1148. Using shRNA lentiviral constructs targeting EGFR, we also found that EGFR expression is required for the growth of the SUM229 cells, even though the kinase activity is not required. In addition, we found that this aberrant tyrosine phosphorylation and growth in the absence of EGFR kinase activity is mediated in part by c-Src and c-Met kinase activity. Interestingly, c-Met is constitutively phosphorylated in the SUM229 cells. This study describes the mechanism of c-Met constitutive activity and defines the Met-mediated signaling pathways to growth and survival in the absence of EGFR kinase activity. Specifically, through sequence analysis of mRNA from SUM229 cells, c-Met is not mutated, confirming the lack of identification of c-Met mutations in breast cancer. In addition, using publically available databases and our own immunoblotting experiments, c-Met is neither amplified nor overexpressed at the mRNA or protein level in the SUM229 cells. Similarly, ligand-mediated regulators of c-Met phosphorylation, including HGF, HGFAC, HAI-1, and HA1-2 are not overexpressed at the mRNA level and HGF protein expression and secretion are comparable to levels seen in breast cancer cells without c-Met constitutive phosphorylation. However, c-Met localization to the cell surface appears to be elevated in the SUM229 cells and c-Met co-immunoprecipitates with EGFR under these conditions. Taken together, these data suggest that c-Met and EGFR association at the cell surface may be mediating c-Met constitutive phosphorylation in the absence of EGFR kinase activity. With respect to the signaling pathways that mediate EGFR kinase-independent, yet c-Met kinase-dependent growth in SUM229 cells we have found that the phosphorylation of Akt, MAPK, p38MAPK, and JNK1/2 are unaffected by inhibition of both EGFR and c-Met kinase activities. Interestingly, the phosphorylation of Jak2, PLCg, and Gab1 are decreased when EGFR and c-Met kinases are inhibited. These data suggest that pathways signaling through Jak2, PLCg, and/or Gab1 may be mediating growth in the absence of EGFR kinase activity. In preliminary data, we know that these pathways do not involve PKC, Akt, or PI3-Kinase. Therefore, current investigations are focused on the STAT family of proteins as well as the Rho/Rac/Cdc42 mediated signaling pathways. Taken together, these data suggest that c-Met mediates a unique signaling pathway in SUM229 cells that stimulates both growth and survival in the absence of EGFR kinase activity.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4059.

Double aneuploidy (48,XXY,+21) of maternal origin in a child born to a 13-year-old mother: evaluation of the maternal folate metabolism

The occurrence of non-mosaic double trisomy is exceptional in newborns. In this paper, a 48,XXY,+21 child, the parental origin of the extra chromosomes and the evaluation of the maternal folate metabolism are presented. The infant was born to a 13-year-old mother and presented with the typical clinical features of Down syndrome (DS). The origin of the additional chromosomes was maternal and most likely resulted from errors during the first meiotic division. Molecular analysis of 12 genetic polymorphisms involved in the folate metabolism revealed that the mother is heterozygous for the MTHFR C677T and TC2 A67G polymorphisms, and homozygous for the mutant MTRR A66G polymorphism. The maternal homocysteine concentration was 4.7 miromol/L, a value close to the one considered as a risk factor for DS in our previous study. Plasma methylmalonic acid and serum folate concentrations were 0.17 micromol/L and 18.4 ng/mL, respectively. It is possible that the presence of allelic variants for the folate metabolism and Hey concentration might have favored errors in chromosomal disjunction during gametogenesis in this young mother. To our knowledge, this is the first patient with non-mosaic Down-Klinefelter born to a teenage mother, resulting from a rare fertilization event combining an abnormal 25,XX,+21 oocyte and a 23,Y spermatozoon.

A new fully-digital anthropomorphic and dynamic thorax/heart model

A numerical anthropomorphic model of the breathing thorax and the beating heart is presented. It includes the main thoracic/cardiac anatomical structures, the main vessel junctions as well as the structures' motion. Its main feature is that it is based on a Magnetic Resonance Imaging (MRI) examination performed on the same human subject within the same session from which both structural and motion information are retrieved. This confers to the model a very good consistency. This numerical model is virtually imaged by two simulators: a MRI simulator and a Positron Emission Tomography (PET) simulator. The overall resulting model (structure geometry & dynamics, images) is useful for the evaluation of cardiac image processing algorithms such as heart structure segmentation or multi-modality cardiac image registration.

Genetic polymorphisms involved in folate metabolism and elevated plasma concentrations of homocysteine: maternal risk factors for Down syndrome in Brazil

The aim of the present study was to investigate the effect of polymorphisms C677T and A1298C in the methylenetetrahydrofolate reductase (MTHFR) gene, A2756G in methionine synthase reductase (MTR) gene and A80G in reduced folate carrier 1 (RFC1) gene, and plasma homocysteine (Hcy), on the maternal risk for Down syndrome (DS). Seventy-two DS mothers and 194 mothers who had no children with DS were evaluated. The investigation of the MTHFR C677T, MTR A2756G and RFC1 A80G polymorphisms was performed by polymerase chain reaction and enzyme digestion and the MTHFR A1298C polymorphism by allele-specific polymerase chain reaction. Hcy quantification was carried out by liquid chromatography-tandem mass spectrometry. The median number of polymorphic alleles for the four loci tested was greater in DS mothers compared to the control group, and the presence of three or more polymorphic alleles increased the risk for having a child with DS 1.74 times. Elevated maternal risk for DS was also observed when plasma Hcy concentration was higher than 4.99 micromol/L. In conclusion, the presence of three or more polymorphic alleles for MTHFR C677T, MTHFR A1298C, MTR A2756G, and RFC1 A80G, and plasma Hcy concentrations higher than 4.99 micromol/L are maternal risk factors for DS.

The MTR A2756G polymorphism is associated with an increase of plasma homocysteine concentration in Brazilian individuals with Down syndrome

Individuals with Down syndrome (DS) present decreased homocysteine (Hcy) concentration, reflecting a functional folate deficiency secondary to overexpression of the cystathionine ss-synthase gene. Since plasma Hcy may be influenced by genetic polymorphisms, we evaluated the influence of C677T and A1298C polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR), of A2756G polymorphism in the methionine synthase gene (MTR), and of A80G polymorphism in the reduced folate carrier 1 gene on Hcy concentrations in Brazilian DS patients. Fifty-six individuals with free trisomy 21 were included in the study. Plasma Hcy concentrations were measured by liquid chromatography_tandem mass spectrometry with linear regression coefficient r(2) = 0.9996, average recovery between 92.3 to 108.3% and quantification limits of 1.0 micromol/L. Hcy concentrations >15 micromol/L were considered to characterize hyperhomocystinemia. Genotyping for the polymorphisms was carried out by polymerase chain reaction followed by enzyme digestion and allele-specific polymerase chain reaction. The mean Hcy concentration was 5.2 +/- 3.3 micromol/L. There was no correlation between Hcy concentrations and age, gender or MTHFR C677T, A1298C and reduced folate carrier 1 A80G genotype. However, Hcy concentrations were significantly increased in the MTR 2756AG heterozygous genotype compared to the MTR 2756AA wild-type genotype. The present results suggest that the heterozygous genotype MTR 2756AG is associated with the increase in plasma Hcy concentrations in this group of Brazilian patients with DS.

Impact of chemoradiotherapy for locally advanced head and neck cancer on swallowing function

6054

Background: We examined the impact of chemoradiotherapy (CRT) on swallowing function in a group of patients treated for locally advanced head and neck cancer in an ongoing randomized phase II study with concurrent CRT, with or without Ethyol. Methods: Chemotherapy consisted of weekly carboplatin AUC 1.5 and paclitaxel at 45 /m2 for 4 weeks. Radiation was delivered using a 3 field technique with a concomitant boost schedule to a total dose of 72 Gy. Patients were randomized to receive or not receive daily subcutaneous Ethyol. Patients had video swallow studies at the start of radiation and 8, 12, 24 and 52 weeks post chemoradiotherapy. Dysphagia and weight loss were monitored. Video swallow study reports were collected and the incidence of penetration, aspiration, pharyngeal residue and upper esophageal narrowing analyzed. Results: Baseline data were available for 31 patients out of 43 enrolled. 29% of the patients penetrated, 6.4% aspirated and 29% had pharyngeal residue. Patients on both arms of the study had a steady decline in swallowing function from onset until 24 weeks post radiation. Penetration, aspiration and pharyngeal residue were consistently noted at all time points and improvements in deglutition were seen on the 52-week post radiation video swallow. Forty percent of the patients (17/43) had narrowing in the upper esophagus. On average, a third of the patients examined required dilations. The remaining patients with esophageal narrowing were able to advance their diet and have their feeding tubes removed without dilations. The average time from the end of the treatment to PEG removal was 219 days. Conclusion: Based on the video swallow studies that were conducted, patients had a gradual decline in swallowing function from initiation of CRT until 24 weeks post. Esophageal narrowing was common, often requiring dilation. Given that it takes 7 months on average for the feeding tubes to come out, we recommend that these patients undergo intensive swallowing therapy and continuous long term follow up and assessment at two and possibly three years post CRT. Study is ongoing.

No significant financial relationships to disclose.

Swallowing function after intensity modulated radiotherapy (IMRT) and chemotherapy for head and neck cancer

6046

Background: To evaluate the swallowing function of patients treated with intensity modulated radiation therapy (IMRT) + chemotherapy (CT) for HNSCC. Methods: Patients completing RT between 9/04 and 8/06 at the DFCI/BWH were evaluated with IRB approval. All patients had formal swallowing evaluation following the completion of therapy; patients with swallowing difficulty underwent video swallow and both stricture and aspiration were scored. Variables examined for correlation with swallowing pathology were: age, race, gender, smoking and alcohol history, primary site, LVI, PNI, RT intention (primary, postop) and use of induction CT. All variables were analyzed via two-sided t-test. Results: 96 patients were evaluated. Median follow-up 10 mos. 75% of the pts were given definitive RT and 25% received postop RT. 72% stage IV, 24% stage III. Primary sites: oropharynx-43, hypopharynx/larynx-17, oral cavity-13, nasopharynx-11, maxillary sinus-2 and unknown primary-10 pts. All pts received once daily IMRT. 9 pts received RT alone, 28 pts received sequential induction and concurrent (CT) and 59 pts received concurrent CT. 31 pts (32%) had some aspiration after therapy; 36 pts (37%) had evidence of a stricture following RT. All but 5 patients had percutaneous endoscopic gastrostomy placed prophylactically RT. Smoking history was the only significant factor found on univariate analysis to correlate with stricture (p=0.05) but not aspiration. Induction CT was not a significant factor in causing aspiration or stricture. 22 of the strictures (71%) resolved after dilation. RT doses to swallowing structures are under evaluation and will be presented. Conclusions: Aspiration and stricture are common side effects after radical treatment with IMRT and CT for HNSCC. Smoking has a significant negative impact on functional outcome.

No significant financial relationships to disclose.

CT assessment of anastomotic bowel leak

AIM

To evaluate the predictors of clinically important gastrointestinal anastomotic leaks using multidetector computed tomography (CT).

SUBJECTS AND METHODS

Ninety-nine patients, 73 with clinical suspicion of anastomotic bowel leak and 26 non-bowel surgery controls underwent CT to investigate postoperative sepsis. Fifty patients had undergone large bowel and 23 small bowel anastomoses. The time interval from surgery was 3-30 days (mean 10+/-5.9 SD) for the anastomotic group and 3-40 days (mean 14+/-11 SD) for the control group (p=0.3). Two radiologists blinded to the final results reviewed the CT examinations in consensus and recorded the presence of peri-anastomotic air, fluid or combination of the two; distant loculated fluid or combination of fluid and air; free air or fluid; and intestinal contrast leak. Final diagnosis of clinically important anastomotic leak (CIAL) was confirmed at surgery or by chart review of predetermined clinical and laboratory criteria.

RESULTS

The prevalence of CIAL in the group undergoing CT was 31.5% (23/73). The CT examinations with documented leak were performed 5-28 (mean; 11.4+/-6 SD) days after surgery. Nine patients required repeat operation, 10 percutaneous abscess drainage, two percutaneous drainage followed by surgery, and two prolonged antibiotic treatment and total parenteral nutrition (TPN). Of the CT features examined, only peri-anastomotic loculated fluid containing air was more frequently seen in the CIAL group as opposed to the no leak group (p=0.04). There was no intestinal contrast leakage in this cohort. Free air was present up to 9 days and loculated air up to 26 days without CIAL.

CONCLUSION

Most postoperative CT features overlap between patients with and without CIAL. The only feature seen statistically more frequently with CIAL is peri-anastomotic loculated fluid containing air.

Pilomatricome ou épithélioma calcifié de Malherbe : à propos d'une série de 89 cas chez l'enfant

The authors report an exclusive pediatric review of 89 pilomatricomas operated in 83 patients. This tumor, also known as calcifying epithelioma of Malherbe, is common in the pediatric population and occurs mainly on the head and neck region. It is a benign skin neoplasm usually misdiagnosed and yet the most common hair follicle tumor. The treatment is a surgical excision taking the overlying skin. Principal characteristics and clinical presentation of this tumor are discussed.

Combination of Angiotensin-Converting Enzyme and Methylenetetrahydrofolate Reductase Gene Polymorphisms as Determinant Risk Factors for Chronic Allograft Dysfunction

OBJECTIVE

The aim of this study was to investigate the frequency of gene angiotensin-converting enzyme insertion/deletion (ACE I/D) and methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) variants, as well as to evaluate the plasma homocysteine concentrations in 217 patients who underwent renal transplantation at least 12 months prior to define risk factors for chronic allograft dysfunction.

METHODS

The presence of the polymorphism ACE deletion was assessed by polymerase chain reaction (PCR) analysis. MTHFR polymorphisms were determined by PCR and restriction fragment length polymorphism (RFPL) techniques. The restriction enzymes were Hinf I and Mbo II for MTHFR variants C677T and A1298C, respectively. Plasma homocysteine concentrations were measured by liquid chromatography-tandem mass spectrometry (LS-MS/MS).

RESULTS

Hyperhomocysteinemias were more common in patients with chronic allograft dysfunction (P = .004). No statistically significant differences were observed between the allelic and genotypic distributions of MTHFR and ACE polymorphisms. An effective risk factor was found when the polymorphisms of the ACE and MTHFR genes and hyperhomocysteinemia were associated (odds ratio 2.51; 95% confidence interval 1.19-5.28). In conclusion, our study identified that the presence of hyperhomocysteinemia in combination with unfavorable genotypes contributes to an increased risk for development of chronic allograft dysfunction.

Gene expression changes in peripheral blood cells provide insight into the biological mechanisms associated with regimen-related toxicities in patients being treated for head and neck cancers

Patients treated with radiotherapy are prone to a constellation of local and systemic toxicities including mucositis, xerostomia, fatigue and anorexia. The biological complexities and similarities underlying the development of toxicities have recently been realized. Mucosal barrier injury is one of the best studied, and gene expression patterns, based on animal tissue samples, have added to its understanding. While investigations gene expression based on tissue samples was valuable, its use precludes more generalizable conclusions relative to common pathogenic mechanisms. Additionally, attempting to define the kinetics of changes in gene expression by sequential sampling is pragmatically unrealistic. Our objectives were: 1. to determine if changes in gene expression could be detected during toxicity development using PBM from patients receiving chemoradiation; 2. to characterize the relationship of expressed genes using graph theory and pathway analysis; and 3. to evaluate potential relationships between the expression of particular genes, canonical pathways, and functional networks in explaining the pathogenesis of regimen-related toxicities.

DESIGN

Microarray analysis was performed using PBM-derived cRNA obtained before and 2 weeks after the initiation of chemoradiation in five patients with head and neck cancer who developed documented regimen-related toxicities. We created a database of those genes newly expressed at 2 weeks and evaluated their potential significance relative to toxicity, by canonical pathway analysis, compilation of regional networks around focus genes, and development of a model globalizing the individual functional networks. There was strong concordance between known pathogenic mechanisms of toxicity and the genes, pathways, and networks developed by our data. A role was elicited for unsuspected genes in toxicity development. Our results support the concept that radiation induced toxicities have common underlying mechanisms and demonstrate the utility of PBM as an RNA source for genetic studies. This methodology could be broadly applicable to the study of regimen-related toxicities.

PET/CT imaging in patients with suspected recurrence of pancreatic cancer

14137

Background: The goal of the study was to review our clinical experience with 18F-FDG PET/CT in patients (pts) with suspected recurrence of pancreatic cancer. Methods: Nine pts (M/F=3/6, age 47–73y) with increasing levels of CA 19–9 and/or CEA during follow-up and negative or equivocal CT scan were included. Seven pts were asymptomatic and 2 pts had mild abdominal pain. Previous treatment included pancreaticoduodenectomy in 6 pts and distal pancreatectomy in 3 pts. Adjuvant chemoradiation was given to 5 pts as well. Tumor markers first increased 2 to 14 months after the operation. CT scan was done within one month in all pts, and found to be normal in 6 pts and equivocal in 3 pts. PET/CT was performed one months (5 pts), 2 months (2 pts) and 3 months (2 pts) later. However, the last 2 pts had a 2nd normal CT scan 1–2 months after the PET/CT. A final diagnosis of recurrence was confirmed by histopathology or by further clinical and radiologic follow up. Results: Of the 9 pts, 8 exhibited PET/CT findings consisted with recurrent cancer. Increased tracer uptakes with abnormal findings on CT were found in 5 pts with CT scan previously defined as normal ( 2 in tumor bed and 3 in distant sites, 1 liver, 1 liver and lymph nodes, 1 abdominal wall). PET/CT was also positive in 3 pts with equivocal CT findings (2 tumor bed, 1 liver with a new unsuspected positive site in tumor bed). Chemotherapy (followed by surgery in 1 pt and by radiation therapy in 1 pt, both with local recurrence) was instituted in 7 pts following PET/CT findings. One pt underwent resection of an isolated abdominal recurrence. After a median follow-up of 7 months (range, 4 -27 m) 4 pts had died of disease, 2 are alive with progressing disease, one has responded to treatment (PET/CT became normal) and one is undergoing ghemotherapy. One of the 9 pts had a false negative PET/CT test, as abdominal spread was later found by an additional CT scan, still with a 2nd negative PET/CT image. Conclusions: PET/CT is a useful tool for detecting recurrent pancreatic cancer, and can demonstrate recurrence site when CT is non-diagnostic. Its impact on clinical management and treatment results should be further evaluated.

No significant financial relationships to disclose.

[Complex polydactyly of the limbs: mirror foot. Report of two cases and review of literature]

Polydactyly is the most common congenital limb anomaly occurring both as an isolated defect or as part of a syndrome. However mirror foot is an exceptional abnormality (14 cases reported). The authors describe two sporadic cases of mirror foot. The first case presents a mirror polydactyly of the left foot, an hexadactyly of the right foot and a central polysyndactyly of both hands. The second case presents a mirror polydactyly of both feet. Mirror foot is a very rare defect. Both sporadic and familiar cases have been reported. This malformation can affect one or both feet. Some cases are associated with other congenital anomalies. The definition of mirror foot is warying according to the authors and the review of literature shows an important variability in the patterns of mirror polydactyly. Mirror duplication of hands and feet result of aberrant positioning of the zone of polarizing activity in relation to the apical ectodermal ridge during limb bud development. Different genes encoding limb pattern have been described.