Microliter viscometry using a bright-field microscope: η-DDM.

The rheological properties of a medium can be inferred from the Brownian motion of colloidal tracer particles using the microrheology procedure. The tracer motion can be characterized by the mean-squared displacement (MSD). It can be calculated from the intermediate scattering function determined by Differential Dynamic Microscopy (DDM). Here we show that DDM together with the empirical Cox-Merz rule is particularly suited to measure the steady-shear viscosity, i.e. the viscosity towards zero frequency, due to its ability to provide reliable information on long time and length scales and hence small frequencies. This method, η-DDM, is tested and illustrated using three different systems: Newtonian fluids (glycerol-water mixtures), colloidal suspensions (protein samples) and a viscoelastic polymer solution (aqueous poly(ethylene oxide) solution). These tests show that common lab equipment, namely a bright-field optical microscope, can be used as a convenient and reliable microliter viscometer. Because η-DDM requires much smaller sample volumes than classical rheometry, only a few microliters, it is particularly useful for biological and soft matter systems.

Soft matter dynamics: A versatile microgravity platform to study dynamics in soft matter.

We describe an experiment container with light scattering and imaging diagnostics for experiments on soft matter aboard the International Space Station (ISS). The suite of measurement capabilities can be used to study different materials in exchangeable sample cell units. The currently available sample cell units and future possibilities for foams, granular media, and emulsions are presented in addition to an overview of the design and the diagnostics of the experiment container. First results from measurements performed on ground and during the commissioning aboard the ISS highlight the capabilities of the experiment container to study the different materials.

[The value of allergy survey in a retrospective series of 40 patients with burning-mouth syndrome (stomatodynia)]. / Stomatodynies: intérêt de l'enquête allergologique dans une série rétrospective de 40 malades.

BACKGROUND: By definition, stomatodynia or burning-mouth syndrome involves oral pain with no causes being found on history taking or examination. An allergic origin is often suspected by doctors and patients alike. In this study, we attempted to assess the value of epicutaneous tests in demonstrating allergic causes for patients presenting stomatodynia. PATIENTS AND METHODS: This was a single-centre retrospective study of patients undergoing epicutaneous tests between 1996 and 2003 to screen for allergic causes of mouth pain not accounted for by any abnormalities seen during examination performed at consultations for mouth disease. RESULTS: Forty patients were included (11 male, 29 female; mean age: 58 years), and 39 were excluded. Sixteen patients presented at least one positive test, with a total of 35 positive tests in all. In decreasing order of frequency, the causes were metals, mercury derivatives (nickel salts: n=5; chrome salts: n=3; palladium salts: n=2; phenylmercuric acetate: n=2; thiomersal: n=2; cobalt salts: n=1; gold salts: n=1; mercury: n=1) and resins (acrylates: n=4). The relevance of these test results was considered probable in three cases and possible in five cases, associated with the existence of metals or resins in patients' mouths. The Peru balm test was positive in four cases but was not relevant. Tests for personal products were negative in all cases, with the exception of one case of resin from a prosthesis and one case of tixocortol pivalate. COMMENTS: Type I stomatodynia (daily occurrence with gradually increase in discomfort throughout the day) and type II stomatodynia (permanent) are not normally attributable to allergies. However, for type III stomatodynia (non-permanent, with acute episodes followed by remission), an allergy survey guided by questioning may be undertaken to determine the cause, primarily prostheses or diet. The relevance of positive test results must be interpreted with caution in view of the incidence of positive epicutaneous tests for metals and Peru balm among the general population studied.

[Necrobiotic xanthogranuloma without monoclonal gammopathy and with a rapidly fatal outcome]. / Xanthogranulome nécrobiotique sans gammapathie monoclonale d'évolution rapidement fatale.

BACKGROUND: Necrobiotic xanthogranuloma is an extremely rare form of histiocytosis that presents clinically as yellowish infiltrated plaques or nodules. Ocular involvement is seen in over 80% of cases. Histopathology reveals numerous xanthomous histiocytes and collagen necrobiosis. Benign monoclonal gammopathy associated with myeloma is found in 80% of patients, but the course is normally long, with 100% survival at 10 years. CASE REPORT: A 76-year-old man presented skin lesions that subsequently became ulcerated. The clinical appearance and histopathological examination resulted in diagnosis of necrobiotic xanthogranuloma. No monoclonal gammopathy or myeloma was seen. The disease was marked by sensitivity to corticosteroids with failure of other therapies (cyclophosphamide, alpha interferon), onset ofcorticosteroid dependency, iatrogenic Cushing's syndrome and diabetes, which were in part responsible for the infectious complications and subsequent death of the patient. DISCUSSION: Necrobiotic xanthogranuloma is difficult to treat, even in the absence of myeloma or monoclonal gammopathy. Corticosteroids are probably the most efficacious treatment, but can give rise to multiple complications, resulting in this particular case in death of the patient.

[Agranular CD4+ CD56+ CD123+ hematodermic neoplasm (blastic NK-cell lymphoma) revealed by cutaneous localization: 2 cases]. / Localisations cutanées révélatrices d'une hématodermie CD4+ CD56+ CD123+: 2 cas.

BACKGROUND: Agranular CD4+ CD56+ hematodermic neoplasm (blastic NK-cell lymphoma) has been recently described. The skin is often the first organ involved. OBSERVATIONS: Two old men of respectively 70 and 77 years consulted for infiltrated cutaneous lesions. Preliminary histological examination of cutaneous biopsy taken in both patients showed a malignant proliferation suggesting a cutaneous lymphoma, and the patients were referred. Histological examination of new biopsies showed a very similar proliferation in the 2 cases of monotonous medium-sized mononuclear cells without expression of the common antigens CD3 and CD20 and the expression of CD4, CD56, and CD123. No rearrangement of the T-cell receptor gene or the immunoglobulin heavy chain gene were evidenced. No extracutaneous involvement was initially detected in the first patient. Thrombocytopenia associated with the abnormal presence of 15 p. 100 of circulating CD4+ CD56+ cells was initially found in the second patient. The first patient was treated with chemotherapy, with complete remission. A cutaneous relapse promptly occurred, followed by bone and cerebral localizations. The patient died one year after the diagnosis of the disease, in spite of intensification of the treatment. Treatment is still ongoing in the second patient. COMMENTS: The histological presentation of these two patients was very similar with an unusual phenotype of tumor cells expressing CD4, CD56, CD123, but not expressing CD3 and CD20. Some cases have been published under the "term of blastic NK lymphoma" which is the actual term for the disease in the WHO classification. However, the tumor cells derive from the dendritic plasmacytoid cells, also called type 2 dendritic cells, and perhaps from a common precursor to lymphocyte T and dendritic plasmacytoid cells. In spite of complete cutaneous response in the 2 cases presented, as in other reports, extra-cutaneous involvement occurs quickly. Overall survival is usually poor since nearly all the patients died in less than 3 years. This justifies attempting aggressive protocols, with bone marrow allograft in the younger patients.