Collective dipole effects in ionic transport under electric fields.

In the context of ionic transport in solids, the variation of a migration barrier height under electric fields is traditionally assumed to be equal to the classical electric work of a point charge that carries the transport charge. However, how reliable is this phenomenological model and how does it fare with respect to Modern Theory of Polarization? In this work, we show that such a classical picture does not hold in general as collective dipole effects may be critical. Such effects are unraveled by an appropriate polarization decomposition and by an expression that we derive, which defines the equivalent polarization-work charge. The equivalent polarization-work charge is not equal neither to the transported charge, nor to the Born effective charge of the migrating atom alone, but it is defined by the total polarization change at the transition state. Our findings are illustrated by oxygen charged defects in MgO and in SiO2.

[Unilateral pigmentary retinopathy : about 2 cases]. / Le cas clinique du mois. Rétinopathie pigmentaire unilatérale.

We present the case of two patients in whom unilateral retinal involvement with pigmentary lesions on the fundus examination was observed. Apart from the unilateral nature of the lesions, a diagnosis of retinitis pigmentosa could have been made in view of the morphological and functional aspects of the retina. However, in these two clinical cases, an association between retinal lesions and Bartonella in one case, and pre-existing multiple sclerosis in the other case, has been proposed with a final diagnosis of unilateral pigmentary retinopathy. Nevertheless, a sufficiently long period of patient follow-up is necessary to rule out delayed onset in the unaffected eye, suggesting an asymmetrical bilateral retinitis pigmentosa.

Nous présentons le cas de deux patientes chez qui une atteinte rétinienne unilatérale comportant des lésions pigmentaires à l'examen du fond de l'œil a été observée. Malgré le caractère unilatéral des lésions, un diagnostic de rétinite pigmentaire d'origine génétique aurait pu être évoqué au vu des aspects morphologiques et fonctionnels de la rétine. Cependant, une origine infectieuse (infection à Bartonella) a pu être proposée pour un cas, alors que, pour l'autre cas, une atteinte inflammatoire secondaire à une sclérose en plaques a été retenue. Pour cette raison, le diagnostic final est celui d'une rétinopathie pigmentaire unilatérale. Néanmoins, un suivi à long terme est obligatoire de façon à écarter une apparition retardée des lésions dans l'œil indemne, ce qui pourrait indiquer la présence d'une rétinite pigmentaire bilatérale asymétrique.

Antibiotic resistance genes are abundant and diverse in raw sewage used for urban agriculture in Africa and associated with urban population density.

A comparative study was conducted to (1) assess the potential of raw sewage used for urban agriculture to disseminate bacterial resistance in two cities of different size in Cameroon (Central Africa) and (2) compare the outcome with data obtained in Burkina Faso (West Africa). In each city, raw sewage samples were sampled from open-air canals in three neighbourhoods. After DNA extraction, the microbial population structure and function, presence of pathogens, antibiotic resistance genes and Enterobacteriaceae plasmids replicons were analysed using whole genome shotgun sequencing and bioinformatics. Forty-three pathogen-specific virulenc e factor genes were detected in the sewage. Eighteen different incompatibility groups of Enterobacteriaceae plasmid replicon types (ColE, A/C, B/O/K/Z, FIA, FIB, FIC, FII, H, I, N, P, Q, R, T, U, W, X, and Y) implicated in the spread of drug-resistance genes were present in the sewage samples. One hundred thirty-six antibiotic resistance genes commonly associated with MDR plasmid carriage were identified in both cities. Enterobacteriaceae plasmid replicons and ARGs found in Burkina Faso wastewaters were also present in Cameroon waters. The abundance of Enterobacteriaceae, plasmid replicons and antibiotic resistance genes was greater in Yaounde, the city with the greater population. In conclusion, the clinically relevant environmental resistome found in raw sewage used for urban agriculture is common in West and Central Africa. The size of the city impacts on the abundance of drug-resistant genes in the raw sewage while ESBL gene abundance is related to the prevalence of Enterobacteriaceae along with plasmid Enterobacteriaceae abundance associated to faecal pollution.

Wastewater used for urban agriculture in West Africa as a reservoir for antibacterial resistance dissemination.

State of art metagenomics were used to investigate the microbial population, antibiotic resistance genes and plasmids of medical interest in wastewater used for urban agriculture in Ouagadougou (Burkina Faso). Wastewater samples were collected from three canals near agricultural fields in three neighbourhoods. Assessment of microbial population diversity revealed different microbial patterns among the different samples. Sequencing reads from the wastewaters revealed different functional specializations of microbial communities, with the predominance of carbohydrates and proteins metabolism functions. Eleven pathogen-specific and 56 orthologous virulence factor genes were detected in the wastewater samples. These virulence factors are usually found in human pathogens that cause gastroenteritis and/or diarrhoea. A wide range of antibiotic resistance genes was identified; 81 are transmissible by mobile genetic elements. These included seven different extended spectrum ß-lactamase genes encoding synthesis of four enzyme families, including two metallo-ß-lactamases (blaAIM-1 and blaGES-21). Ten different incompatibility groups of Enterobacteriaceae plasmid replicons (ColE, FIB, FIC, FII, P, Q, R, U, Y, and A/C), and 30 plasmid replicon types from Gram-positive bacteria. All are implicated in the wide distribution of antibiotic resistance genes. We conclude that wastewater used for urban agriculture in the city represents a high risk for spreading bacteria and antimicrobial resistance among humans and animals.

[Posterior scleritis]. / La sclérite postérieure : cas clinique.

Posterior scleritis, a severe and painful inflammation of the sclera, is an often misdiagnosed pathology due to its clinical polymorphism. An accurate diagnosis is however needed in order to propose an appropriate treatment of the ophthalmologic symptoms and to exclude an associated systemic inflammatory or auto-immune pathology.

La sclérite postérieure est une inflammation sévère et douloureuse localisée au niveau de la sclère. Cette pathologie méconnue est souvent sous-diagnostiquée en raison de son polymorphisme clinique. Il est néanmoins important de la reconnaître de façon à proposer un traitement adéquat des symptômes oculaires et de rechercher les différentes pathologies systémiques inflammatoires ou auto-immunes pouvant lui être associées.

The role of the local chemical environment of Ag on the resistive switching mechanism of conductive bridging random access memories.

Conductive bridging random access memories (CBRAMs) are one of the most promising emerging technologies for the next generation of non-volatile memory. However, the lack of understanding of the switching mechanism at the nanoscale level prevents successful transfer to industry. In this paper, Ag/GeSx/W CBRAM devices are analyzed using depth selective X-ray Absorption Spectroscopy before and after switching. The study of the local environment around Ag atoms in such devices reveals that Ag is in two very distinct environments with short Ag-S bonds due to Ag dissolved in the GeSx matrix, and longer Ag-Ag bonds related to an Ag metallic phase. These experiments allow the conclusion that the switching process involves the formation of metallic Ag nano-filaments initiated at the Ag electrode. All these experimental features are well supported by ab initio molecular dynamics simulations showing that Ag favorably bonds to S atoms, and permit the proposal of a model at the microscopic level that can explain the instability of the conductive state in these Ag-GeSx CBRAM devices. Finally, the principle of the nondestructive method described here can be extended to other types of resistive memory concepts.

Magnetic resonance imaging-guided core needle breast biopsies resulting in high-risk histopathologic findings: upstage frequency and lesion characteristics.

UNLABELLED: Analysis of magnetic resonance imaging-guided breast biopsies yielding high-risk histopathologic features at a single institution found an overall upstage rate to malignancy of 14% at surgical excision. All upstaged lesions were associated with atypical ductal hyperplasia. Flat epithelial atypia and atypical lobular hyperplasia alone or with lobular carcinoma in situ were not associated with an upstage to malignancy. INTRODUCTION: The purpose of the present study w as to determine the malignancy upstage rates and imaging features of high-risk histopathologic findings resulting from magnetic resonance imaging (MRI)-guided core needle breast biopsies. These features include atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), flat epithelial atypia (FEA), and lobular carcinoma in situ (LCIS). MATERIALS AND METHODS: A retrospective medical record review was performed on all MRI-guided core needle breast biopsies at a single institution from June 1, 2007 to December 1, 2013 to select biopsies yielding high-risk histopathologic findings. The patient demographics, MRI lesion characteristics, and histopathologic features at biopsy and surgical excision were analyzed. RESULTS: A total of 257 MRI-guided biopsies had been performed, and 50 yielded high-risk histopathologic features (19%). Biopsy site and surgical excision site correlation was confirmed in 29 of 50 cases. Four of 29 lesions (14%) were upstaged: 1 case to invasive ductal carcinoma and 3 cases to ductal carcinoma in situ. ADH alone had an overall upstage rate of 7% (1 of 14), mixed ADH/ALH a rate of 75% (3 of 4), ALH alone or with LCIS a rate of 0% (0 of 7), and FEA a rate of 0% (0 of 4). Only mixed ADH/ALH had a statistically significant upstage rate to malignancy compared with the other high-risk histopathologic subtypes combined. No specific imaging characteristics on MRI were associated with an upstage to malignancy on the statistical analysis. CONCLUSION: MRI-guided breast biopsies yielding high-risk histopathologic features were associated with an overall upstage to malignancy rate of 14% at surgical excision. All upstaged lesions were associated with ADH. FEA and ALH alone or with LCIS were not associated with an upstage to malignancy.

Short-term imaging follow-up of patients with concordant benign breast core needle biopsies: is it really worth it?

PURPOSE: Women with histologically proven concordant benign breast disease are often followed closely after biopsy for a period of two years, and they are considered to be at high-risk for cancer development. Our goal was to evaluate the utility of short-term (six-month) imaging follow-up and determine the incidence of breast cancer development in this population. METHODS: Retrospective review of concordant benign breast pathology was performed in 558 patients who underwent multimodality breast core biopsy. A total of 339 patients (60.7%) with 393 biopsies qualified for the study. The six-, 12-, and 24-month incidence rates of breast cancer development were estimated with 95% confidence intervals (CI), using the exact method binomial proportions. RESULTS: No cancer was detected in 285 of 339 patients (84.1%) returning for the six-month follow-up. No cancer was detected in 271 of 339 patients (79.9%) returning for the 12-month follow-up. Among 207 follow-up exams (61.1%) performed at 24 months, three patients were detected to have cancer in the ipsilateral breast (1.45% [95% CI, 0.30%-4.18%]) and two patients were detected to have cancer in the contralateral breast (0.97% [95% CI, 0.12%-3.45%]). Subsequent patient biopsy rate was 30 of 339 (8.85%, [95% CI, 6.05%-12.39%]). Three ipsilateral biopsies occurred as a sole result of the six-month follow-up of 285 patients (1.05%, [95% CI, 0.22%-3.05%]). CONCLUSION: Short-term imaging follow-up did not contribute to improved breast cancer detection, as all subsequent cancers were detected on annual mammography. Annual diagnostic mammography after benign breast biopsy may be sufficient.

Beyond mammography: new frontiers in breast cancer screening.

Breast cancer screening remains a subject of intense and, at times, passionate debate. Mammography has long been the mainstay of breast cancer detection and is the only screening test proven to reduce mortality. Although it remains the gold standard of breast cancer screening, there is increasing awareness of subpopulations of women for whom mammography has reduced sensitivity. Mammography also has undergone increased scrutiny for false positives and excessive biopsies, which increase radiation dose, cost, and patient anxiety. In response to these challenges, new technologies for breast cancer screening have been developed, including low-dose mammography, contrast-enhanced mammography, tomosynthesis, automated whole breast ultrasound, molecular imaging, and magnetic resonance imaging. Here we examine some of the current controversies and promising new technologies that may improve detection of breast cancer both in the general population and in high-risk groups, such as women with dense breasts. We propose that optimal breast cancer screening will ultimately require a personalized approach based on metrics of cancer risk with selective application of specific screening technologies best suited to the individual's age, risk, and breast density.

[Clinical case of the month. Acute post-traumatic panophthalmitis]. / Panophtalmie post-traumatique fulgurante.

Panophtalmitis is an intra-ocular and intra-orbital rare infection, but its consequences are often horrendous, with loss of both function and anatomy of the eye. The surgical approach and the antibiotherapy should be given as soon as possible, both by intra-vitreal and intra-venous injections. We report the case of a 49-year-old man who developed a Bacillus cereus panophtalmitis. A delay in the diagnosis lead to the loss of vision and the evisceration of the sick eye. Bacillus cereus panopthalmitis should be suspected in all cases of post-traumatic endophtalmitis with a soiled metallic foreign body, in patients with important local inflammatory signs as well as systemic signs. Vitrectomy, surgical extraction of the foreign body, intra-vitreal and systemic antibiotherapies should be given as soon as possible, even before the results of the bacteriological analysis.

Sudden sensorineural hearing loss: when ophthalmology meets otolaryngology.

OBJECTIVES: Sudden sensorineural hearing loss is a perplexing entity in otology. Susac's syndrome (also called retinocochleocerebral vasculopathy) is a rare disorder that consists of microangiopathy of the brain, retina, and inner ear, and usually affects women in young adulthood. We describe the clinical aspects, radiographic findings, and management of one such case. CASE REPORT: A 30-year-old woman was admitted to the hospital because of sudden onset of bilateral deafness and headache. During her hospitalization, she developed discrete right hemiparesis and hypoesthesia. RESULTS: Magnetic resonance imaging revealed multiple signal hyperintensities and atrophy of the corpus callosum. The differential diagnosis was a myelinating condition, such as multiple sclerosis or acute demyelinating encephalomyelitis. CONCLUSION: Retinal fluorescein angiography helped the diagnosis of Susac's syndrome.

Clinical and imaging surveillance following breast cancer diagnosis.

Breast cancer is the most common malignancy affecting women worldwide. Women have a 1 in 8 lifetime risk of breast cancer. Breast conservation therapy (BCT) is the most common method of definitive treatment. Patients who previously have had to undergo mastectomy may be now eligible for BCT or a multitude of options for reconstruction, either immediate or delayed. Surveillance imaging after a breast cancer diagnosis is important because there is an increased risk of recurrence developing in patients, and early detection has been shown to improve survival. There is currently no consensus on a protocol for imaging the postoperative breast. In patients who have undergone mastectomy, detection of recurrence has mostly been via clinical symptoms and physical exam, often at a later stage. New imaging modalities, such as magnetic resonance imaging (MRI), ultrasound (US), and positron emission mammography (PEM) are changing the way we image the postsurgical breast. MRI, coupled with physical exam and mammography, approaches 100% sensitivity and high specificity for the identification of recurrent disease. We present a review of major academic institutions' imaging protocols and discuss the advantages of including MRI in traditional mammographic and clinical exams.

Retinitis pigmentosa and bronchiectasis: a case report on a rare association suggestive of a common underlying primary ciliary dyskinesia (PCD).

We describe a case of retinitis pigmentosa, associated with bronchiectasis, as the first sign of primary ciliary dyskinesia (PCD). Only a few cases were described in the literature and the association of both diseases is not obvious at first sight, although a common ciliary dysfunction of both respiratory epithelium and photoreceptors of the retina seems to be the common factor. It is important to recognize the association and to question patients with retinitis pigmentosa about their respiratory functions, because an early diagnosis of PCD can prevent recurrent infections and development of bronchiectasis with daily physiotherapy.

[Clinical case of the month. A case of von Hippel-Lindau disease]. / Le cas clinique du mois. A propos d'un cas de maladie de von Hippel-Lindau.

von Hippel-Lindau disease is an inherited multisystemic familial cancer syndrome caused by mutations of the VHL gene. The spectrum of clinical manifestations is broad and includes central nervous system hemangioblastomas and visual benign and malignant tumors. The various manifestations can be demonstrated by means of different imaging techniques such as magnetic resonance imaging, computed tomography, and fluorescein retinal hemangiography. A systematic approach must be followed for repeated screening in patients at risk, since many lesions in VHL disease are treatable.

[Bilateral optic atrophy in a drug addict]. / Atrophie papillaire bilatérale chez un patient héroïnomane.

Bilateral optic neuropathy in a young man is suggestive of hereditary or toxic damage. We describe the case of a 38-year-old man with bilateral optic neuropathy. His best corrected visual acuity was light perception OD and 20/125 OS. The patient's history revealed an addiction to heroin. Three drugs - heroin, quinine, and cocaine - were considered as a possible cause, which is discussed further. We suggest that the condition reported here may be attributed to the use of heroin. This underlines the importance of meticulous history taking in diagnosing a young man with bilateral loss of vision.

Comparison of 3 protocols for treatment after induction of remission in dogs with lymphoma.

BACKGROUND: The optimal treatment after inducing complete remission (CR) in dogs with lymphoma has not been established. HYPOTHESIS: After inducing CR with L-asparaginase, vincristine, cyclophosphamide, doxorubicin, prednisone (L-CHOP); consolidation with either half-body radiation therapy (HBRT); or lomustine (CCNU) and mechlorethamine, vincristine, procarbazine, prednisone (MOPP) would improve first remission duration compared with continuing a CHOP-based protocol for an additional 4 months. ANIMALS: Dogs with stage III-V lymphoma. METHODS: Prospective clinical trial in which dogs initially were treated with an 8-week induction protocol that consisted of L-CHOP. Dogs in CR after induction were then allocated to 1 of 2 consolidation arms. A chemotherapy consolidation arm consisted of 2 treatments with CCNU and 1 cycle of MOPP. A HBRT arm consisted of 2 sequential 8.0-Gy fractions to the cranial and caudal half-body separated by 30 days. Vincristine was given between fractions. Results of the consolidation arms also were compared with a historical group treated with the same 8-week induction protocol followed by CHOP therapy until week 24. RESULTS: Overall, 67% of the dogs were in CR after 8 weeks of induction chemotherapy and were compared. Fifty-two dogs were in the historical arm, 23 in the CCNU/MOPP arm, and 27 in the HBRT arm. No difference in first remission duration was found among groups. Median first remission duration for the historical, CCNU/MOPP, and HBRT arms were 307, 274, and 209 days, respectively (P = .28). Overall second CR rate was 82% and was not different among groups (all P > or = .58). Overall remission duration (P = .28) and survival time (P = .48) were not different among groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Consolidation with either CCNU/MOPP or HBRT showed no advantage over a standard CHOP-based protocol.

Sodium iodide I 131 treatment of dogs with nonresectable thyroid tumors: 39 cases (1990-2003).

OBJECTIVE: To determine outcome for dogs with nonresectable thyroid carcinomas treated with sodium iodide I 131 and identify factors associated with outcome. DESIGN: Retrospective case series. Animals-39 dogs. PROCEDURES: A definitive or presumptive diagnosis of thyroid tumor was made on the basis of cytologic or histologic examination, abnormal accumulation of sodium pertechnetate Tc 99m during scintigraphy, or both, and dogs were treated with sodium iodide I 131. Dogs with cervical thyroid tumors were evaluated 3 to 6 weeks after 131I therapy, and residual tumor was resected when feasible. RESULTS: Prior to 131I therapy, 32 dogs had a solitary mass and 7 had metastases; 21 were hyperthyroid, 16 were euthyroid, and 2 were hypothyroid. Median survival time for dogs with local or regional tumors (ie, stage II or III) was significantly longer (839 days) than median survival time for dogs with metastasis (366 days). Tumor site (cervical vs ectopic), dose of sodium iodide I 131, age, body weight, treatment (131I therapy alone vs 131I therapy followed by surgery), and serum T4 concentration prior to 131I therapy were not significantly associated with survival time. Three dogs died of radioiodine-associated myelosuppression within 3 months after treatment, but no specific factor associated with development of toxicosis was identified. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that 131I therapy may result in prolonged survival times in dogs with nonresectable thyroid tumors, regardless of serum thyroxine concentration prior to treatment. Dogs undergoing 131I therapy should be monitored for signs of bone marrow suppression.

[Circadian variations in intraocular pressure and their clinical implications]. / Variations nycthémérales de la pression intraoculaire et leurs implications cliniques.

Intraocular pressure follows a circadian rhythm like many of the body's parameters. These fluctuations in intraocular pressure were recently identified as a risk factor for visual field loss, in addition to intraocular pressure itself. Furthermore, the pressure curve seems to have a different profile in glaucomatous patients: the peak occurs later compared with normal subjects. Better knowledge of pressure fluctuations and their physiological mechanisms is essential for optimal management of glaucomatous patients not only to interpret the single ocular tension recordings, but also to use the available treatments rationally, both drugs and surgery. The authors review different studies that have contributed to the current knowledge on the circadian rhythm of intraocular pressure, aquous humor flow regulation, and the effects of topical hypotensive drugs on the pressure curve.

[Retinal vascular occlusions: diagnosis and management]. / Les occlusions vasculaires rétiniennes: diagnostic et prise en charge.

PURPOSE: The diagnosis of retinal venous and arterial occlusions is usually easily evoked on visual symptoms and ophthalmoscopic features. However, their management (etiologic explorations and treatment) has not been formally established and remains controversial. CURRENT KNOWLEDGE AND KEY POINTS: Some retinal vascular occlusions may result of loco-regional ocular causes. They more often occur in patients with cardiovascular pathologies or risk factors, or sometimes other systemic diseases that need to be recognized for a proper treatment. Therefore, a comprehensive management of patients with retinal vascular occlusions is necessary to correct associated diseases or predisposing abnormalities that could lead to local recurrences or systemic events. CONCLUSION: Along with a review of the literature, we suggest a practical approach for the management of retinal vascular occlusions, which requires a collaboration between the ophthalmologist and other physicians: general practitioner, cardiologist, internist... as appropriate according to each case.