PubMed Health⌕ Search

Biomedical subjects

M Landau

Publications and source records attributed to M Landau.

80 records · Page 5Linked to original sources
PubMed1982

Construction, mathematical study and numerical simulation of a calcium turnover model during skeletal muscle contraction.

Starting from recent physiological data we establish a first order non-linear differential system which models the calcium turnover during skeletal muscular contraction. We describe the methods allowing one to calculate with a computer the non-experimentally directly-measured initial conditions. In order to ensure the consistency of the system with physiology we prove the positivity, a priori inequalities and both the existence and the uniqueness of the solutions. To obtain a complete knowledge of the system during a twitch, the aim is to identify, using the experimental data the calcium, two re-uptake constants and the function describing its ejection rate. We demonstrate the uniqueness of the identification problem, we establish an original algorithm for the identification of the two constants, and we show that the function to be identified is the solution of an integral equation for the resolution of which we give an algorithm whose convergence is proved. According to this mathematical study the model is numerically simulated on a computer; this allows us thus to find again experimental data in a consistent frame, and to predict the values of some non-measured constants and functions.

Actins↗
PubMedDate not supplied

Sicca syndrome and HTLV-I-associated myelopathy/tropical spastic paraparesis.

PURPOSE: The objective of this study is to describe the clinical and immunological aspects observed in patients with both human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis and ocular dryness. METHODS: In 15 such patients, clinical and biological examinations completed with a biopsy of secondary salivary glands were performed to assess the etiology of the ocular dryness. RESULTS: Histological study of the biopsy specimens indicated that 80% of the patients had grade 3 or grade 4 lesions, according to the Chisholm scale. Polyclonal hypergammaglobulinemia was found in 60% of patients and lymphocytic alveolitis in 80%. Three patients had past medical history of chronic uveitis. CONCLUSIONS: All findings in these patients were compatible with Sjögren's syndrome; however, no immunological disorders characteristic of the syndrome were found. Tests for antinuclear antibodies and rheumatoid factor proved negative in all cases.

Adult↗
PubMedDate not supplied

Palmoplantar eccrine hidradenitis: three new cases and review.

Palmoplantar eccrine hidradenitis (PEH) is characterized by painful erythematous papules and nodules of abrupt onset on the soles of young individuals. The histologic hallmark is a predominant neutrophilic infiltrate surrounding the eccrine gland apparatus. A total of 28 cases have been published since 1988, with a broad variation in the age of patients, symptomatology, associated diseases, clinical course, and histologic features. These different histologic pictures have resulted in several names for this entity, including idiopathic plantar hidradenitis, neutrophilic eccrine hidradenitis, recurrent palmoplantar hidradenitis in children, and idiopathic palmoplantar hidradenitis. We present three cases of this disorder and review the literature on the varying symptomatology, clinical course, and histology that have led to the myriad of names for this disease.

Adult↗
PubMedDate not supplied

Clinical significance of markedly elevated serum creatine kinase levels in patients with acne on isotretinoin.

Muscle-related complaints and high creatine kinase (CK) blood levels have been reported in 16-51% of patients with acne treated with isotretinoin. It has been suggested that this retinoid and exercise have a synergistic effect on muscle. The presence of marked hyperCKemia during the treatment raises concern about rhabdomyolysis. The objective of this report was to evaluate the incidence, course and clinical significance of severe hyperCKemia in isotretinoin therapy for acne. Out of 442 patients on isotretinoin, we reviewed 7 patients (1.58%) with CK values above 5,000 IU/l. Only two of them had myalgia. Physical activity or intramuscular injection prior to blood testing was reported in 6 patients. CK values returned to normal within 2 weeks and all subjects except 2, completed treatment. In conclusion, marked hyperCKemia with or without muscle-related complaints in isotretinoin-treated patients with acne is a benign phenomenon.

Acne Vulgaris↗
PubMedDate not supplied

Ethanol-modulated cytokine production and expression in skin cells exposed to methotrexate.

Evidence suggests a link between alcohol consumption, psoriasis and the response of psoriatic patients to methotrexate (MTX) therapy. Ethanol (EtOH) may play a role in the pathogenesis of psoriasis by upregulating the expression and inducing the local secretion of proinflammatory cytokines, e.g. interleukins IL-1alpha, IL-6, chemokine IL-8 and tumor necrosis factor alpha (TNF-alpha). We investigated whether EtOH or MTX or their combination influence the secretion of these cytokines using normal human primary skin cells (NHPSC) and epidermoid cell line A431. The objectives of this study were: (1) to quantify the differences in cellular changes induced by MTX, (2) to measure the effect of EtOH on MTX toxicity and (3) to determine the relationship between MTX and EtOH exposure and production of proinflammatory cytokines. NHPSC and A431 were incubated with 0-10 mM MTX or alpha-MEM (control) in the presence or absence of 40 mM EtOH. A formazan 3-(4,5-dimethylthiazole-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay was used as a marker for cell viability (control was 100%). Significance was calculated by ANOVA. Cytokine release into media was quantitated by ELISA. After 24 h of MTX exposure, the release of IL-1alpha was unchanged. IL-6 increased 1.7 times in both cultures, and IL-8 increased 1.7 times in NHPSC and 2.1 times in A431. TNF-alpha release increased twice in A431 but not in NHPSC. Human recombinant IL-1alpha and IL-6 for 24 h had no effect, while TNF-alpha reduced cytoviability by 30% in NHPSC and 22% in A431. Anti-TNF-alpha reversed the effect produced by TNF-alpha in NHPSC and reduced it in A431 (11.8%, p < 0.05). We concluded that in vitro in normal human primary keratinocytes, toxicity and inflammatory responses are enhanced by EtOH.

Antibodies, Monoclonal↗