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Biomedical subjects

M Heenen

Publications and source records attributed to M Heenen.

At least 55 records · Page 3Linked to original sources
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

Iron as a potential co-factor in the pathogenesis of Kaposi's sarcoma?

The role of iron in the pathogenesis of several tumours is being increasingly investigated. In particular, its involvement in the pathogenesis of Kaposi's sarcoma (KS) is suggested by the distribution of the endemic form of KS corresponding to continental rifts and associated iron-oxide-rich volcanic clays. We investigated in vitro to what extent iron supplementation or withdrawal could affect the growth of KS-derived cells, by analysing the effects of adding iron salts (iron chloride and ferric nitrilotriacetate) and/or reducing iron by iron chelators (desferrioxamine) on KS-derived cell cultures. The addition of iron salts strongly stimulated the growth of KS cells, as reflected by increase in thymidine incorporation and cell number. Conversely, desferrioxamine and deferiprone inhibited cell growth. The inhibitory effect of iron chelation was more pronounced on rapidly dividing basic fibroblast-growth-factor-stimulated cells. These results may point to a novel therapeutic approach to KS.

Carcinogens↗
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

Overexpression of Bcl-2 in Kaposi's sarcoma-derived cells.

The pathogenesis of Kaposi's sarcoma (KS), a tumor of probable vascular origin, remains an enigma. It is still unclear whether KS is a true malignancy or whether it represents a reactive polyclonal process. Using both an immunohistochemical and an immunoblot approach, we found that cells derived from KS lesions express significant levels of Bcl-2, a protein known to prolong cellular viability and to antagonize apoptosis. Bcl-2 expression was found in AIDS-related KS-derived cells, as well as in cells derived from iatrogenic and sporadic KS, indicating that Bcl-2 upregulation may be important in the pathogenesis of KS regardless of its epidemiologic form. By contrast, fibroblasts and dermal microvascular endothelial, cells which are the probable vascular progenitors of KS cells, expressed low levels of Bcl-2. The expression of Bcl-2 in KS-derived cells was associated with a long-term survival in serum-deprived conditions, a situation that has been shown to induce apoptosis in various cell types. Incubation of fibroblasts or of dermal microvascular endothelial cells with KS cell-free supernatants did not enhance Bcl-2 expression, suggesting that Bcl-2 expression is not mediated by an agent released by KS cells. Analogously, KS supernatants failed to promote the viability of fibroblasts and of dermal microvascular endothelial cells cultured in serum-free conditions. Our findings suggest that the spindle cells derived from KS have a survival advantage and may adequately represent the tumor cells of KS.

Cell Survival↗
PubMed1998

Tuberculous inguinal and crural lymph nodes.

Non-respiratory forms of tuberculosis are frequently described in immigrants from endemic countries and in immunocompromised patients. Among the extrapulmonary forms of tuberculous disease, peripheral lymph node involvements, generally cervical, are the most common. Interestingly, only a few cases of tuberculous inguinal adenitis have been reported in the literature during the last 15 years. We report 2 cases of isolated inguinal inflammatory lymph-adenitis observed in immigrant immunocompetent women. The diagnosis of tuberculosis was confirmed by culture obtained by needle aspiration of a lymph node. The lesions completely healed after standard antituberculous therapy.

Adult↗
PubMed1998

Ki-67 immunostaining of normal human epidermis: comparison with 3H-thymidine labelling and PCNA immunostaining.

BACKGROUND: The size of the germinative growth fraction (i.e. the number of actively proliferating germinative cells) of normal human epidermis is still a subject of debate. Ki-67 antigen and PCNA, an auxiliary protein of d-polymerase, are considered as markers of the growth fraction when used under optimal conditions. METHOD: In the present work, we have compared Ki-67 expression (detected with MIB1 antibody) with PCNA expression (detected with PC10 antibody) in biopsies of normal human epidermis fixed in neutral formalin and using antigen retrieval by microwave processing. To obtain additional information, such as the percentage of cells in S phase, biopsies were also incubated in 3H-thymidine before immunostaining. RESULTS: Before microwave treatment, 8% of the basal cells were positive for MIB1 antibody and 7.8% were positive for PC10 antibody. The 3H-thymidine labelling index was 2.8%. The proportion of MIB1-positive cells rose to 19% after antigen retrieval by microwave processing. In the same way, the 3H labelling index rose to 9%. In contrast, PC10 became positive in all epidermal nuclei. CONCLUSION: These results suggest that the growth fraction of the germinative cell population of normal human epidermis is not larger than 20% and is composed of cells with a short cell cycle time.

Antibodies, Monoclonal↗
PubMed1997

Effects of low frequency pulsed electrical current on keratinocytes in vitro.

The effects of low frequency pulsed electrical current on epidermal repair in vitro were examined. Charge-balance current stimuli proposed for chronic wound treatment were tested on skin keratinocytes cultured at an air-liquid interface on dead human dermis. Results imply that the balance between proliferation and differentiation in electrically treated samples is significantly modified in favor of differentiation. More advanced differentiation, shown through epidermal histology, was obtained in cultures exposed to electrical current, whereas the culture growth, the result of keratinocyte migration and proliferation, was greater in control samples.

Adult↗
PubMed1997

Clinical efficacy and safety comparison of adapalene gel and tretinoin gel in the treatment of acne vulgaris: Europe and U.S. multicenter trials.

BACKGROUND: Adapalene is a new chemical entity that exhibits tretinoin-like activities in the terminal differentiation process. OBJECTIVE: We evaluated a dose range effect of two concentrations of adapalene gel as acne treatment and compared adapalene 0.1% gel with tretinoin 0.025% gel in the treatment of acne patients in two large multicenter studies. METHODS: Multicenter, investigator-masked, parallel group studies including 89 acne patients in the dose range study and 591 patients in the concurrent controlled studies were conducted. RESULTS: Adapalene gel 0.1% was significantly more effective in treating acne lesions than 0.03% adapalene gel. Adapalene gel 0.1% was significantly more effective than 0.025% or tretinoin gel in one study and of the same effectiveness in the other study. Adapalene gel was always better tolerated than tretinoin gel. CONCLUSION: Adapalene 0.1% gel is a safe and effective treatment of acne vulgaris.

Adapalene↗