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D Bessis

Publications and source records attributed to D Bessis.

At least 19 recordsLinked to original sources
PubMed2001

On the uniqueness of the surface sources of evoked potentials.

The uniqueness of a surface density of sources localized inside a spatial region R and producing a given electric potential distribution in its boundary B0 is revisited. The situation in which R is filled with various subregions, each one having a definite constant value for the electric conductivity is considered. It is argued that the knowledge of the potential in all B0 fully determines the surface-located sources for a general class of surfaces supporting them and also a wide type of those sources. The class of surfaces can be defined as a union of an arbitrary but finite number of open or closed surfaces. The only restriction upon them is that no one of the closed surfaces contains inside it another (nesting) of the closed or open ones. The types of sources are surface charge densities and double layer (dipolar) densities for the open surfaces and more restrictively, only surface charge densities for the closed ones. A two-dimensional analytically solvable example illustrating the drastic appearance of uniqueness after arbitrarily small holes are opened in nested surfaces is discussed.

Journal Article↗
PubMed2001

Exchange forces in dispersion relations investigated using circuit relations.

We propose a novel method to compute in an exact manner the left-hand cut discontinuity of the electron-atom partial wave scattering amplitude in the complex energy plane within the static exchange approximation. Zero energy dispersion relations for electron-hydrogen scattering are computed numerically for illustration.

Journal Article↗
PubMed2001

HFE mutations and transferrin receptor polymorphism analysis in porphyria cutanea tarda: a prospective study of 36 cases from southern France.

BACKGROUND: Porphyria cutanea tarda (PCT) is associated in most cases with iron overload, which may participate in decreased activity of uroporphyrinogen decarboxylase in the liver. The aetiology of this iron overload remains unknown; however, it has been demonstrated that mutations of HFE, the genetic haemochromatosis gene, might be present in a significant proportion of Anglo-Saxon and Italian patients. Furthermore, transferrin receptor polymorphism may influence the affinity of this receptor to its ligand with a subsequent increase of cellular iron absorption and storage. OBJECTIVES: To evaluate the incidence and spectrum of HFE mutations and the relative frequency of the two main alleles of transferrin receptor in patients with PCT originating from southern France, and to evaluate the relationship of these genetic data with iron status, and with hepatitis B and C and human immunodeficiency virus (HIV) infections. METHODS: Thirty-six consecutive patients with either sporadic or familial PCT were prospectively included between 1997 and 2000. Search for the presence of the three main mutations of the HFE gene and identification of the transferrin receptor alleles were performed using polymerase chain reaction followed by enzymatic digestion. Iron parameters and viral status for hepatitis B and C viruses and HIV were determined. RESULTS: Seven patients (19%) showed heterozygous C282Y mutation, but no C282Y homozygote was present; five patients (14%) carried homozygous H63D mutation, while eight (22%) were heterozygous for this mutation. One patient was heterozygous for the S65C mutation (3%). Iron parameters demonstrated overload in all patients, without a clear difference between patients with and without deleterious mutations of the HFE gene. Infection by hepatitis C virus was documented in 20 patients (56%), and was significantly less frequent in patients with deleterious HFE mutations. The profile of transferrin receptor alleles in PCT patients did not show significant variation compared with the general population. CONCLUSIONS: This study confirms the high frequency of HFE mutations in patients with PCT and supports the hypothesis that HFE gene abnormalities might play a significant part in the PCT pathomechanism, probably through iron overload; by contrast, transferrin receptor polymorphisms do not appear to play a significant part in iron overload in PCT.

Adult↗
PubMed1999

EMLA cream as a topical anesthetic for the repeated mechanical debridement of venous leg ulcers: a double-blind, placebo-controlled study.

BACKGROUND: A granulating surface is important for skin grafting and healing of leg ulcers. Mechanical debridement to remove necrotic tissue often must be stopped before completion because of pain. OBJECTIVE: Our purpose was to assess the effect of EMLA cream on the number of debridements required to obtain a clean ulcer and on pain during debridement and to determine its safety after repeated doses. METHODS: In this randomized double-blind, placebo-controlled study, 69 patients with venous leg ulcers received cream before debridement until a clean ulcer was obtained (or a maximum of 15 debridements). RESULTS: EMLA decreased the median number of debridements required for a clean ulcer (EMLA 11.5, placebo >15; P = .019) and decreased pain by 50% (P = .003). Plasma levels of lidocaine, prilocaine, and their main metabolites were low without any apparent accumulation. CONCLUSION: EMLA produces effective pain relief for the debridement of leg ulcers and shortens the time to a clean ulcer.

Administration, Cutaneous↗
PubMed1998

[Pheochromocytoma manifesting as toe necrosis].

BACKGROUND: Cutaneous manifestations of pheochromocytoma other than sweating, and facial pallor during paroxysmal episodes of hypertension are exceptional. CASE REPORT: We observed partial necrosis of the fourth toes which revealed pheochromocytoma. DISCUSSIONS: Signs of peripheral vascular disease are uncommon during the course of pheochromocytoma. Only four cases have been reported in the literature. Occurrence of distal necrosis in combination with hypertension and palpable pulses is suggestive of pheochromocytoma requiring assay of urinary catecholamines. The pathogenic mechanisms of necrosis would be vasospasm of cutaneous vessels due to excessive plasmatic catecholamine levels and thrombocytosis as an aggravating factor.

Adrenal Gland Neoplasms↗
PubMed1998

[Seborrheic keratosis erupting in a tattoo].

INTRODUCTION: Decorative tattoos have been associated with inflammatory reactions and transmission of infectious diseases. Cutaneous tumors have rarely been reported. CASE REPORT: We report the case of a 26-year-old man who presented eruptive seborrheic keratoses strictly localized on the area of a decorative tattoo. No other lesion was present anywhere else on the cutaneous surface. Three years later the lesions remained stable. COMMENTS: To our knowledge, this is the first report of eruptive seborrhelc keratoses on a tattoo. In our observation, the role of human papillomavirus contamination during tattoo procedure is discussed.

Adult↗
PubMed1996

Granulomatous mycosis fungoides presenting as sarcoidosis.

This report describes the case of a woman who developed cutaneous granulomatous infiltration during childhood that was initially considered to be sarcoidosis and, after 27 years of evolution, was determined to be caused by granulomatous mycosis fungoides transforming to Ki-1-positive anaplastic large-cell lymphoma of T-cell type. We discuss the differential diagnosis, especially granulomatous slack skin and the interest of immunohistochemical and genotypic studies in this case.

Adult↗