Deletion of yghZ in Escherichia coli promotes growth in presence of furfural with xylose as carbon source.

Thermo-acidic pretreatment of lignocellulosic biomass is required to make it amenable to microbial metabolism and results in generation of furfural due to breakdown of pentose sugars. Furfural is toxic to microbial metabolism and results in reduced microbial productivity and increased production costs. This study asks if deletion of yghZ gene which encodes a NADPH-dependent aldehyde reductase enzyme results in improved furfural tolerance in Escherichia coli host. The ∆yghZ strain-SSK201-was tested for tolerance to furfural in presence of 5% xylose as a carbon source in AM1 minimal medium. At 96 h and in presence of 1.0 g/L furfural, the culture harboring strain SSK201 displayed 4.5-fold higher biomass, 2-fold lower furfural concentration and 15.75-fold higher specific growth rate (µ) as compared to the parent strain SSK42. The furfural tolerance advantage of SSK201 was retained when the carbon source was switched to glucose in AM1 medium and was lost in rich LB medium. The findings have potential to be scaled up to a hydrolysate culture medium, which contains furan inhibitors and lack nutritionally rich components, under bioreactor cultivation and observe growth advantage of the ∆yghZ host. It harbors potential to generate robust industrial strains which can convert lignocellulosic carbon into metabolites of interest in a cost-efficient manner.

Mechanism of furfural toxicity and metabolic strategies to engineer tolerance in microbial strains.

Lignocellulosic biomass represents a carbon neutral cheap and versatile source of carbon which can be converted to biofuels. A pretreatment step is frequently used to make the lignocellulosic carbon bioavailable for microbial metabolism. Dilute acid pretreatment at high temperature and pressure is commonly utilized to efficiently solubilize the pentose fraction by hydrolyzing the hemicellulose fibers and the process results in formation of furans-furfural and 5-hydroxymethyl furfural-and other inhibitors which are detrimental to metabolism. The presence of inhibitors in the medium reduce productivity of microbial biocatalysts and result in increased production costs. Furfural is the key furan inhibitor which acts synergistically along with other inhibitors present in the hydrolysate. In this review, the mode of furfural toxicity on microbial metabolism and metabolic strategies to increase tolerance is discussed. Shared cellular targets between furfural and acetic acid are compared followed by discussing further strategies to engineer tolerance. Finally, the possibility to use furfural as a model inhibitor of dilute acid pretreated lignocellulosic hydrolysate is discussed. The furfural tolerant strains will harbor an efficient lignocellulosic carbon to pyruvate conversion mechanism in presence of stressors in the medium. The pyruvate can be channeled to any metabolite of interest by appropriate modulation of downstream pathway of interest. The aim of this review is to emphasize the use of hydrolysate as a carbon source for bioproduction of biofuels and other compounds of industrial importance.

Overexpression of Oxidoreductase YghA Confers Tolerance of Furfural in Ethanologenic Escherichia coli Strain SSK42.

Furfural is a common furan inhibitor formed due to dehydration of pentose sugars, like xylose, and acts as an inhibitor of microbial metabolism. Overexpression of NADH-specific FucO and deletion of NADPH-specific YqhD had been a successful strategy in the past in conferring tolerance against furfural in Escherichia coli, which highlights the importance of oxidoreductases in conferring tolerance against furfural. In a screen consisting of various oxidoreductases, dehydrogenases, and reductases, we identified the yghA gene as an overexpression target to confer tolerance against furfural. YghA preferably used NADH as a cofactor and had an apparent Km value of 0.03 mM against furfural. In the presence of 1 g liter-1 furfural and 10% xylose (wt/vol), yghA overexpression in an ethanologenic E. coli strain SSK42 resulted in an ethanol efficiency of ∼97%, with a 5.3-fold increase in ethanol titers compared to the control. YghA also exhibited activity against the less toxic inhibitor 5-hydroxymethyl furfural, which is formed due to dehydration of hexose sugars, and thus is a formidable target for overexpression in ethanologenic strain for fermentation of sugars in biomass hydrolysate. IMPORTANCE Lignocellulosic biomass represents an inexhaustible source of carbon for second-generation biofuels. Thermo-acidic pretreatment of biomass is performed to loosen the lignocellulosic fibers and make the carbon bioavailable for microbial metabolism. The pretreatment process also results in the formation of inhibitors that inhibit microbial metabolism and increase production costs. Furfural is a potent furan inhibitor that increases the toxicity of other inhibitors present in the hydrolysate. Thus, it is desirable to engineer furfural tolerance in E. coli for efficient fermentation of hydrolysate sugars.

[Environmental exposure chambers (EEC): A novel tool for pathophysiological and pharmaceutical research]. / Les chambres d'exposition environnementale (CEE) : un nouvel outil dans la recherche académique et industrielle.

Airborne allergic diseases (allergic asthma, rhinitis and conjunctivitis) have reached epidemic proportions and are a great burden for both society and individuals. Therefore we need to better understand the physiopathological mechanisms and to increase clinical research in these diseases. However, traditional outpatient studies are difficult and have number of limitations, in particular the variability of allergen exposure. Yet allergen provocation tests, especially bronchial challenges in asthma, are excellent tools to measure the efficiency of anti-allergic therapies. Environmental exposure chambers (EEC) allow the performance of controlled allergen provocation tests on a large scale with remarkable sensitivity, specificity and reproducibility. Moreover, they allow a precise collection of allergic symptoms, making them interesting tools for patho-physiological and clinical studies. During the last thirty years, they have assisted the study of anti-allergic therapies and provided data on their pharmacodynamic characteristics, particularly in allergic rhinitis. However, there are still no EEC tests centered on asthma. The EEC of Strasbourg (ALYATEC®) was developed to fulfill two objectives: to allow standardized allergenic and non-allergenic exposures with better control of the parameters than in other EEC and to offer a place to study asthma and anti-asthmatic therapies safely.

Graphene oxide-zinc oxide nanocomposite as channel layer for field effect transistors: effect of ZnO loading on field effect transport.

The effects of ZnO on graphene oxide (GO)-ZnO nanocomposites are investigated to tune the conductivity in GO under field effect regime. Zinc oxides with different concentrations from 5 wt % to 25 wt % are used in a GO matrix to increase the conductivity in the composite. Six sets of field effect transistors with pristine GO and GO-ZnO as the channel layer at varying ZnO concentrations were fabricated. From the transfer characteristics, it is observed that GO exhibited an insulating behavior and the transistors with low ZnO (5 wt %) concentration initially showed p-type conductivity that changes to n-type with increases in ZnO loading. This n-type dominance in conductivity is a consequence of the transfer of electrons from ZnO to the GO matrix. From X-ray photoelectron spectroscopic measurements, it is observed that the progressive reduction in the C-OH oxygen group took place with increases in ZnO loading. Thus, from insulating GO to p- and then n-type, conductivity in GO could be achieved with reduction in the C-OH oxygen group by photocatalytic reduction of GO with varying degrees of ZnO. The restoration of sp(2) electron network in the GO matrix with the anchoring of ZnO nanostructures was observed from Raman spectra. From UV-visible spectra, the band gap in pristine GO was found to be 3.98 eV and reduced to 2.8 eV with increase in ZnO attachment.

Thin-film transistors with a graphene oxide nanocomposite channel.

Graphene oxide (GO) and graphene oxide-zinc oxide nanocomposites (GO-ZnO) were used as channel materials on SiO(2)/Si to fabricate thin-film transistors (TFT) with an aluminum source and drain. Pure GO-based TFT showed poor field-effect characteristics. However, GO-ZnO-nanocomposite-based TFT showed better field-effect performance because of the anchoring of ZnO nanostructures in the GO matrix, which causes a partial reduction in GO as is found from X-ray photoelectron spectroscopic data. The field-effect mobility of charge carriers at a drain voltage of 1 V was found to be 1.94 cm(2)/(V s). The transport of charge carriers in GO-ZnO was explained by a fluctuation-induced tunneling mechanism.

Male form of persistent Mullerian duct syndrome type I (hernia uteri inguinalis) presenting as an obstructed inguinal hernia: a case report.

INTRODUCTION: Persistent Mullerian duct syndrome is a rare form of male pseudo-hermaphroditism characterized by the presence of Mullerian duct structures in an otherwise phenotypically, as well as genotypically, normal man; only a few cases have been reported in the worldwide literature. We report the case of a 30-year-old man with unilateral cryptorchidism on the right side and a left-sided obstructed inguinal hernia containing a uterus and fallopian tube (that is, hernia uteri inguinalis; type I male form of persistent Mullerian duct syndrome) coincidentally detected during an operation for an obstructed left inguinal hernia. CASE PRESENTATION: A 30-year-old South Indian man was admitted to our facility with a left-sided obstructed inguinal hernia of one day's duration. He had a 12-year history of inguinal swelling and an absence of the right testis since birth. Our patient had well developed masculine features. Local physical examination revealed a left-sided obstructed inguinal hernia with an absence of the right testis in the scrotum. Exploration of the inguinal canal revealed an indirect inguinal hernia containing omentum, the left corner of the uterus and a left fallopian tube. Extension of the incision revealed a well formed uterus, cervix and upper part of the vagina attached to the prostate by a thick fibrosed band. Total excision of the uterus, bilateral fallopian tubes and right testis was performed. A biopsy was taken from the left testis. The operation was completed by left inguinal herniorraphy. Histopathological examination of the hernial contents was consistent with that of a uterus and fallopian tubes without ovaries. Both testes were atrophied, with complete arrest of spermatogenesis. Post-operative karyotype analyses were negative for 46,XY and Barr bodies on buccal smear. A semen examination revealed azoospermia with a low serum testosterone level. CONCLUSIONS: In cases of unilateral or bilateral cryptorchidism associated with inguinal hernia, as in our patient's case, the possibility of persistent Mullerian duct syndrome should be kept in mind in order to prevent further complications such as infertility and malignant change. Hernia uteri inguinalis is the type I male form of persistent Mullerian duct syndrome, characterized by one descended testis and herniation of the ipsilateral corner of the uterus and fallopian tube into the inguinal canal.

Malignant proliferating trichilemmal cyst of the scalp: histological aspects and nosology.

BACKGROUND: Malignant proliferating trichilemmal cyst is a rare tumour usually located on the scalp of elderly women. About 40 cases of malignant proliferating trichilemmal tumour have been documented. CASE REPORT: We report a case of a malignant proliferating trichilemmal cyst of the scalp in a 57-year-old woman. On the vertex she had a voluminous vegetated and multinodular tumour measuring 7 x 5 cm with spontaneous and abundant bleeding, and another lesion of the scalp corresponding to a trichilemmal cyst. Based on histopathological findings, the case was diagnosed as malignant proliferating trichilemmal cyst. CONCLUSION: Diagnostic, clinicoprognostic and histological features of this tumour are discussed. Treatment is not yet standardized given its rarity.

[Pediatric mandibular ameloblastic fibro-odontoma]. / Fibrome odonto-améloblastique de l'enfant.

INTRODUCTION: Ameloblastic fibro-odontoma (AFO) is a very rare mixed odontogenic tumor (2% of all odontogenic tumors). It is considered as a non-extensive non-aggressive tumor but recurrence and malignant transformation remain possible. We report a voluminous AFO in a child. CASE REPORT: A 7-year-old boy presented with a right mandibular and facial swelling. The panoramic radiograph and CT scan revealed a voluminous unilocular radiolucent lesion (10 cm) with an impacted tooth that involved the ramus area and the angle of the right mandible. Enucleation and curettage was performed with a good outcome. There was no recurrence at ten months. DISCUSSION: This case is exceptional because of the young patient's age, the large tumor diameter, and the good outcome after ten months. This tumor occurs more often in the posterior region of the mandible and is frequently seen in the first two decades of life. The diagnosis is made on radio-clinical data and may be confirmed by histology. A surgical treatment with complete tumor removal is recommended to prevent recurrence.

Rectal leiomyosarcoma: report on two cases and a practical approach to differential diagnosis.

Rectal leiomyosarcoma is an uncommon malignancy. Herein, we describe the clinicopathological features and biological behaviour of these tumours, and provide a practical approach to differential diagnosis, particularly with gastrointestinal stromal tumours (GIST). We report two cases in elderly men. In the first, the lesion was 2 cm from the anal sphincter, while it was located in the rectal ampulla in the second case. Histologically, both tumours were characterized by pleiomorphic, large spindle cells, presenting numerous mitoses and marked nuclear atypia. Immunohistochemical analysis showed that tumour cells coexpressed both actin and desmin, whereas CD117 and S100 protein were negative. The final diagnosis was leiomyosarcoma. One of the patients died of pulmonary metastasis within six months. The second patient had bone metastasis, but was lost to follow up. This report underlines the potential diagnostic problems raised by rectal leiomyosarcoma and emphasizes the role of immunohistochemistry in achieving correct diagnosis, which has important clinical, therapeutic and prognostic consequences.

[Cecal perforation in a kidney transplant patient: disseminated histoplasmosis]. / Perforation caecale chez un transplanté rénal.

Disseminated histoplasmosis is a fungal infection caused by Histoplasma capsulatum. It often involves immunodeficient patients and can occur in two forms, i.e., the large- and small-celled variants. The purpose of this report is to describe a case of disseminated histoplasmosis with cutaneous and digestive involvement observed four years after kidney transplantation in a man from Senegal. The patient developed severe sepsis secondary to colonic perforation. Outcome was fatal due to delayed diagnosis and extent of disease.

WITHDRAWN: Ultrasonic characterization of formation damage.

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No evidence of the APC D1822V missense variant's pathogenicity in Tunisian patients with sporadic colorectal cancer.

OBJECTIVES: Sporadic colorectal cancer is influenced by numerous single nucleotide polymorphisms (SNPs), each with minor effects on the cancer risk. This study seeks to determine whether there is any association of the I1307K, E1317Q and D1822V variants within the Adenomatous polyposis coli gene (APC) and risk to develop colorectal cancer in Tunisian population. METHODS: Direct sequencing was used to investigate three SNPs in the APC in 48 Tunisian sporadic colorectal cancer cases and 63 controls. RESULTS: There was no statistically significant association between the I1307K, E1317Q and D1822V variants investigated and colorectal cancer risk. CONCLUSION: The lack of association may show that these variants selected for this study are not involved in the colorectal carcinogenic process. Otherwise, the eventual biological effect is so little to go undetected, unless increasing the sample size.

Epidemiological study, immunohistochemistry and in situ hybridization studies of nasopharyngeal carcinomas: a Tunisian report.

Nasopharyngeal carcinomas (NPC) are a significant problem of public health in Tunisia. They are particular because of their characteristic geographic distribution. The aims of this study were, first, to appreciate the presence of Epstein-Barr virus (EBV) genome by immunohistochemistry (IHC) and in situ hybridization (ISH) and to compare their benefits to NPC diagnosis and, secondly, to verify the relation between NPC and factors bound to the food and environment conditions. Biopsies, recruited at the department of pathology of EPS Charles Nicolle at Tunis, were analyzed for EBV genome presence by ISH of EBV-encoded small RNA1 (EBER1). IHC was done with encoded nuclear antigen (EBNA1), latent membrane proteins (LMP1), and antigen BZ1 anti-Z EBV-replication activator (ZEBRA). An epidemiological study based upon the analysis of a detailed questionnaire submitted to patients (all from the north of Tunisia) and 60 witnesses was done. The statistic analysis was realised by SPSS Windows 11.5 Advanced Statistics. All samples were classified as Undifferentiated Carcinoma of Nasopharyngeal type (UCNT). We found a sex ratio of 2 with a bimodal repartition. ISH showed 96.6% positive samples. IHC revealed the EBV in 90% of cases and 66.7%, respectively, with EBNA1 and LMP1. The statistic analysis showed a meaningful relation (P<0.05, OR>3) between NPC and dietary factors (spices and piquant condiment), alcohol and the water quality.

Urothelial carcinoma with plasmocytoid component.

Plasmocytoid urothelial carcinoma is a rare subtype of tumour of the urinary bladder. Its clinical and histopathological features have not been well characterized. There are few reports of this type of tumour. We report a case of 65-year-old man who was operated in our department for bladder tumour. The pathological diagnosis was high-grade urothelial carcinoma with plasmocytoid component. The patient died shortly thereafter from liver and bone metastasis.

A benign cystic mass of the pancreas mimicking a malignant lesion.

Herein, we highlight the diagnostic challenges of cystic pancreatic tumours, and report a case of chronic pancreatitis caused by a cystic tumour, which consisted in a canal dilatation--and not a pseudocyst. The case thus demonstrates a rare association between a cystic form of chronic pancreatitis and adrenal adenoma. We report the case of a 46-year-old patient with no particular past medical history who presented with long lasting symptoms consisting in an abdominal pain and deterioration in general health. Imaging findings (ultrasound, CT-scan, MRI) showed a 3-cm cystic lesion of the tail of the pancreas associated with a 3-cm adrenal mass. Because of the suspicion of a malignant disease, surgical treatment was performed. Pathological findings consisted in fibrotic chronic pancreatitis with canal dilatation and an adrenal adenoma. Pancreatic cystic lesions are rare tumours. Despite of the multiplicity of imaging techniques, differential techniques lack sensitivity and specificity. Final diagnosis must be based on pathological features.

[Prognostic value of morphologic subdivision of papillary renal cell carcinoma and MUC1 expression]. / Intérêt pronostique du sous-typage morphologique des tumeurs tubulopapillaires du rein et expression de MUC1.

OBJECTIVE: The purpose of our study was to demonstrate the prognostic value of morphologic subdivision of papillary renal cell carcinoma and compare MUC1 expression in two types. MATERIALS AND METHODS: The present retrospective study included 30 cases of papillary renal cell carcinoma based on review of histology slides. The histologic type, Führman grade and stage pTNM were specified. Immunohistochemistry was performed in 22 cases using antibody MUC1. RESULTS: Patients were 23 men and seven women with a mean age of 59.6 years. Eleven tumors were type 1 and 19 were type 2. Type 2 tumors were significantly associated with a higher Führman grade (p = 0.0002). We showed a differential expression of MUC1, which is frequently expressed in the type 1. A local recurrence occurred in one case, lung metastasis in the second one and both tumors were type 2. The survival rate without recurrence and metastasis was 100 % in the type 1. It was 79 % at 12 months and 59 % at 24 months in the type 2. MUC1 expression was correlated with the outcome. CONCLUSION: Type 2 tumors are associated with a higher Führman grade than type 1 and MUC1 expression is more frequent in type 1 and correlated with outcome.