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Biomedical subjects

M Laporte

Publications and source records attributed to M Laporte.

At least 37 records · Page 2Linked to original sources
PubMed2000

Melanoma screening: results of the first one-day campaign in Belgium ('melanoma Monday').

BACKGROUND: Although the incidence of melanoma is increasing and many informative campaigns have been organized. The general population is still little informed about this tumour. AIMS: To organize a media campaign, with more relevant information and the opportunity for free skin inspections. METHODS: A 'Task Force' organized a media campaign in April 1999 and convinced 65% of the Belgian dermatologists to give up 4 h of their time to do free skin examinations for skin cancer on Monday 26 April 1999; it was called 'Melanoma Monday'. RESULTS: A total 2767 patients were screened. We found 25 melanomas and suspected 59 basal cell carcinomas. In the following 4 weeks another 141 melanomas were found. These 166 melanomas found in one month represent 15-20% of the total number of melanomas per year in Belgium. SUMMARY: A media campaign with relevant information combined with screening opportunities can lead to the early detection of melanomas in a large number of patients and can continue to alert people at risk in the following weeks.

Adolescent↗
PubMed2000

Apoptosis in established and healing psoriasis.

BACKGROUND: Previous studies have described apoptosis in the stratum granulosum and in the stratum corneum, but not in the germinative compartment in normal skin. In psoriasis, an increased epidermal apoptosis has been observed in the differentiated compartment, suggesting that apoptosis has a key role in the pathogenesis of psoriasis, as a counteracting factor to the overproduction of cells. Little is known on apoptosis in the germinative compartment. METHODS: Apoptosis was studied on biopsies of normal skin, established lesions of psoriasis and PUVA-treated psoriasis using the transferase-mediated uridine nick end labelling method, which detects fragmented DNA, and electron microscopy. Counting of apoptotic cells was restricted to the germinative compartment as defined by Mib1 staining to evaluate the impact of cell loss on cell production and tissue architecture. RESULTS: The apoptotic index was 0.12% in normal epidermis, 0.035% in established psoriasis and 0.31% in regressive psoriasis. CONCLUSION: These results have three implications: (1) they show the physiological presence of apoptosis in the germinative compartment in normal epidermis; (2) they suggest that induction of apoptosis is involved in the regression of psoriatic hyperplasia after PUVA therapy; (3) the decrease of physiological apoptosis in the psoriatic lesion suggests that this phenomenon could play a role in the induction of psoriatic hyperplasia.

Apoptosis↗
PubMed1999

Sentinel lymph node mapping in the management of high risk malignant melanoma.

In patients with malignant melanoma, the selective biopsy of the first draining lymph node, so-called the sentinel lymph node, allows to identify, with a low morbidity, the patients with nodal metastasis that require radical lymphadenectomy and adjuvant systemic chemotherapy. Herein, we report our initial experience in sentinel lymph node biopsy in 16 patients with malignant melanoma. The sentinel lymph node was localised using preoperative lymphoscintigraphy and injection of dye blue. Intraoperatively, the dissection was guided with a gamma probe and by the recognition of the blue nodes. In the 16 cases the sentinel lymph node was localised. In 50% of the cases, multiple sentinel nodes were demonstrated at lymphoscintigraphy and found during surgery. A limited postoperative morbidity was observed in three cases. Three patients presented nodal metastasis and underwent further radical lymphadenectomy. We conclude that sentinel lymph node mapping is a feasible and reproductive procedure. The preoperative lymphoscintigraphy is essential to identify multiple sentinel nodes and guide surgical dissection. The impact of this approach on the overall survival of patients with high-risk melanoma has still to be demonstrated in studies with a long follow-up.

Adult↗
PubMed1998

Methotrexate induces apoptotic cell death in human keratinocytes.

The mechanism by which low doses of methotrexate act in psoriasis to restore a clinically normal skin is poorly understood. Apoptosis is a programmed cell death activated when cell removal is needed. The purpose of the present work was to examine using an organotypical model of keratinocyte culture, the possibility that low doses of methotrexate can induce apoptosis of keratinocytes. Epidermal explants were cultivated on dead deepidermized dermis under air-exposed conditions. After 10 days, methotrexate (10(-7) M) was added. After a further 5 days, one part of each culture was fixed and submitted to routine histology, DNA nick end labelling (TUNEL) to detect DNA fragmentation (a molecular marker of apoptotic cell death) and immunohistochemical detection of p53 (a protein involved in apoptosis induced by DNA-damaging agents). The other part of each culture was processed for electron microscopy. A significant proportion of keratinocytes (1%) were damaged and exhibited the morphological features of apoptotic cell death. Immunohistochemical overexpression of p53 was detected in the basal layer of the cultures treated with methotrexate. Low doses of methotrexate induce apoptosis. This mode of action could explain the reduction in epidermal hyperplasia during treatment of psoriasis with methotrexate.

Apoptosis↗
PubMed1998

Verrucous carcinoma of the nail bed.

Verrucous carcinoma is a rare, highly keratinizing variant of squamous cell carcinoma of the skin or mucosae characterized by a local aggressiveness but a low potential for metastasis. The plantar form is also known as epithelioma cuniculatum. Fingers and toes are rarely affected, and tumors of the nail bed are exceptional. Clinically, the lesion presents like a wart and is then often misdiagnosed. Treatment of choice is wide surgical excision. A case of verrucous carcinoma of the nail apparatus is presented, and diagnosis is discussed.

Carcinoma, Verrucous↗
PubMed1998

Clinical characteristics of malignant melanoma.

Malignant melanoma represents a major public health concern. Its incidence is rising throughout the world; in Europe particularly, 13-21 people/100.000 are affected annually. Although the aetiology is multifactorial, excessive UV exposure (UVB 290-320 min.) appears to be one of the most important predisposing agent. Genetic predisposition plays also a fundamental role. Chromosome 9p has been implicated in familial melanoma via the inhibition of a cyclin-dependent kinase 4 which interferes with cell cycle. The early detection and recognition of malignant melanoma is the key for possible cure. Technical aids like photography, computer based systems, epiluminescence or biopsy increase the sensitivity of formally trained clinicians.

Chromosome Aberrations↗
PubMed1997

Overlap of sarcoidosis and rosacea.

Numerous descriptions have been applied to rosacea-like eruptions of the face, some of them remaining of questionable nosologic significance. A case of rosacea-like syndrome with lacrimal, ocular and salivary involvement is described. The differential diagnosis and therapeutic response of this unusual association are discussed.

Adult↗
PubMed1994

The heterogeneity of the germinative compartment in human epidermis and its implications in pathogenesis.

In mouse epidermis keratinocytes of the basal layer seem to belong to 3 different subpopulations: stem cells, transit cells and postmitotic cells. Each subpopulation assumes a specific role in epidermal homeostasis. Recent data tend to display a similar heterogeneity among basal keratinocytes in human epidermis. This concept opens the door to an integrated understanding of epidermal renewal but also suggests new hypotheses in pathogenesis. Psoriasis, a typical example of epidermal hyperplasia, is considered from this point of view.

Animals↗
PubMed1993

Sequence-specific deamidation: isolation and biochemical characterization of succinimide intermediates of recombinant hirudin.

Natural hirudin variant 2 with a lysine residue in position 47 (rHV2-Lys47) was produced in a genetically engineered strain of Saccharomyces cerevisiae as a secreted protein of 65 amino acids and purified to greater than 99% homogeneity. Only reversed-phase high-performance liquid chromatography (RP-HPLC) using very shallow acetonitrile gradients indicated the presence of a component in the final product (approximately 1% of total protein) with a slightly increased retention time. Using successive RP-HPLC purification steps, this hydrophobic impurity was isolated and separated into two constituents defined as components A1 and A2 which differed from the parent molecule by mass reductions of 17.2 Da (A1) and 17.6 Da (A2), respectively, as determined by electrospray mass spectrometry (ESMS). Proteolytic digestion with endoprotease Glu-C from Staphylococcus aureus (V8 protease) and analysis of the peptide mixture by ESMS showed that the mass difference between rHV2-Lys47 and component A1 was due to a modification between amino acids 1 and 43, while the corresponding mass difference with component A2 was the result of a modification within the peptide fragment comprising residues 50-61. Further analyses using amino acid sequencing and ESMS in combination with collision-activated dissociation (CAD) detected modifications at residues Asn33-Gly34 in component A1 and at Asn53-Gly54 in component A2. Both of these sites were previously shown to be susceptible to spontaneous deamidation under slightly basic pH conditions. Thus, the mass reductions of approximately 17 Da and the fact that both asparagines, Asn33 in component A1 and Asn53 in component A2, proved to be resistant to Edman degradation provided strong support for them being stable succinimide intermediates of the corresponding deamidation reactions. Both intermediates were shown to have inhibition constants for human alpha-thrombin on the order of 1 pM, identical to that of rHV2-Lys47. The isoelectric point of component A2 was determined to be within 0.01 pH unit of that of the parent molecule by isoelectric focusing in an immobilized pH gradient.

Amides↗
PubMed1993

Malignant clear cell hidradenoma.

We report the case of a 77-year-old man with a recurrent malignant clear cell hidradenoma. Establishing histopathological criteria of malignancy for these tumors can be difficult as nuclear anaplasia may be slight to moderate or even absent; however, in contrast to the benign form, malignant clear cell hidradenoma tends to invade the surrounding tissue. As these tumors can show a high rate of local recurrence (50%) and may even metastasize to lymph nodes, bone or visceral organs, wide surgical excision should be performed after the initial diagnosis.

Adenoma, Sweat Gland↗
PubMed1991

Nails in light and electron microscopy.

The study and the diagnosis of nail disorders benefit from examination under light and electron microscopes. The alterations occurring in the matrix, bed, and hyponychium are comparable to those observed in the skin. Architectural and cellular alterations--loss of the cell's regular alignment, changes in stain affinity, parakeratosis, and changes in the intercellular spaces--are observed in the nail plate and subungual keratin. The intensity and singularities of these lesions are usually sufficient to orient the diagnosis from examination of the keratin alone. This microscopic examination is of particular interest in dealing with mycoses because it can specify the type of invasion of the keratin and avoid false-positive or false-negative results on culturing. Electron microscopy allows easy differentiation of melanin and ferric pigments.

Humans↗
PubMed1990

[Lichen planus: etiopathogenesis].

Lichen planus could result from a succession of immunological events: stimulation of Langerhans cells and keratinocytes by foreign antigen--production of interleukin 1 (IL 1)--activation, attraction and multiplication of helper T lymphocytes--production of interferon gamma--appearance of intercellular adhesion molecule-1 (ICAM 1) and HLA DR Antigen on keratinocytes membranes, allowing adhesion of T lymphocytes to keratinocytes and subsequent destruction of the latter.

Antigens, CD↗
PubMed1989

An inhibition enzyme-linked immunosorbent assay technique for the detection of endotoxins in proteins extracted from Escherichia coli K12 recombinant DNA.

An inhibition enzyme-linked immunosorbent assay (ELISA) was developed for the specific quantitation of rough (R) mutant E. coli K12 lipopolysaccharide (LPS). Since R-LPS binds poorly to polystyrene microplates, an LPS-BSA covalent complex was prepared following glutaraldehyde activation and used as a coating surface antigen. A 100-fold higher signal was observed using the LPS-BSA complex as solid-phase antigen instead of free LPS. The LPS detection limit obtained was 0.5 ng/ml. This test was applied to hGH extracts produced genetically engineered E. coli K12 and a good correlation was found with the LAL test. This new LPS titration technique will be useful for detecting LPS in complex mixtures and the antigen-antibody reaction will ensure the specificity of the detection.

Antigens, Bacterial↗
PubMed1988

Nail changes in alopecia areata: light and electron microscopy.

Fragments of nail keratin removed with tweezers from patients suffering from alopecia areata were examined using light microscopy and electron microscopy. The results obtained from these two techniques show nail changes which are slits, cupuliform dips of the upper edge and parakeratosis, under light microscopy; vacuoles, depletion of keratin fibers, and electron-dense fibrillary deposits, under electron microscopy. These changes predominate in the nail plate with a maximum in the upper part while the subungual keratin is preserved. A serious disorder of the matrix keratinization is probably the source of this preferential localization. To determine whether it is a disorder of the keratin fibers themselves or rather of the interfilamentary matrix and especially of the filaggrin system will require further biochemical and immunological studies.

Alopecia Areata↗