Update on enzyme and molecular defects in porphyria

The endocrine systems of vertebrates and higher invertebrates may have evolved functionally from as far back on the evolutionary scale as bacteria and early multicellular organisms and their biological communities, which have been shown to produce a variety of cyclic nucleotides, peptides, fatty acids, prostaglandins and sterols with endocrine-altering effects in primative as well as more highly evolved species.     

Characterization of molecular defects in xeroderma pigmentosum group C

Xeroderma pigmentosum (XP) is a rare autosomal recessive disease of humans characterized by an accelerated chronic degeneration of sun-exposed areas of the body, including an elevated risk of developing cancers of the skin. We recently reported the isolation of a gene XPCC that complements the repair deficiency of cultured XP-C cells. Here we report the results of a characterization of XPCC at the nucleotide level in five XP-C cell lines. Each cell line exhibited a unique mutation that correlated well with the cellular DNA repair deficiency and the clinical severity of the disease. These results extend our previous observations and indicate that defects in XPCC cause Xeroderma pigmentosum group C.     

Possible role of autotransplantation in small cel bronchial carcinoma

Autologous bone marrow transplantation (ABMT) performed with recent achievements plays yet no established role in the treatment of small cell lung cancer (SCLC). The majority of treatment results obtained so far do not clearly suggest a superiority of high-dose therapy with autologous transplantation over conventional polychemo/radiotherapy. It is unknown, whether or not a subgroup of patients with, e.g., "limited disease" and chemosensitive tumor may benefit from ABMT. Randomized trials will be necessary to clarify this question.     

Possible role of decorin glycosaminoglycans in fibril to fibril force transfer in relative mature tendons--a computational study from molecular to microstructural level

Experimental studies on immature tendons have shown that the collagen fibril net is discontinuous. Manifold evidences, despite not being conclusive, indicate that mature tissue is discontinuous as well. According to composite theory, there is no requirement that the fibrils should extend from one end of the tissue to the other; indeed, an interfibrillar matrix with a low elastic modulus would be sufficient to guarantee the mechanical properties of the tendon. Possible mechanisms for the stress-transfer involve the interfibrillar proteoglycans and can be related to the matrix shear stress and to electrostatic non-covalent forces. Recent studies have shown that the glycosaminoglycans (GAGs) bound to decorin act like bridges between contiguous fibrils connecting adjacent fibril every 64-68 nm; this architecture would suggest their possible role in providing the mechanical integrity of the tendon structure. The present paper investigates the ability of decorin GAGs to transfer forces between adjacent fibrils. In order to test this hypothesis the stiffness of chondroitin-6-sulphate, a typical GAG associated to decorin, has been evaluated through the molecular mechanics approach. The obtained GAG stiffness is piecewise linear with an initial plateau at low strains (<800%) and a high stiffness region (3.1 x 10(-11)N/nm) afterwards. By introducing the calculated GAG stiffness in a multi-fibril model, miming the relative mature tendon architecture, the stress-strain behaviour of the collagen fibre was determined. The fibre incremental elastic modulus obtained ranges between 100 and 475 MPa for strains between 2% and 6%. The elastic modulus value depends directly on the fibril length, diameter and inversely on the interfibrillar distance. In particular, according to the obtained results, the length of the fibril is likely to play the major role in determining stiffness in mature tendons.     

Possible role of transforming growth factor-beta in relapsing-remitting multiple sclerosis

Cerebrospinal fluid (CSF) and serum levels of transforming growth factor (TGF)-beta and soluble intercellular adhesion molecule-1 (sICAM-1) were evaluated in ten patients with definite multiple sclerosis (MS) of the relapsing-remitting type. CSF TGF-beta levels of MS patients in remission were significantly (p < 0.01) higher than of MS patients in active phase, and there was a significant inverse correlation (p < 0.05) between TGF-beta and slCAM-1 levels in the CSF of patients in both remitting and relapsing type. This is consistent with a possible down-regulation of TGF-beta on ICAM-1 expression and suggests a possible synthesis in the central nervous system of TGF-beta.     

Possible mechanisms for the nucleation of primary fracture zones during deformation-induced phase transformations in solids: II. The role of phase transitions between the states of aggregation

The conditions of local phase transitions between the states of aggregation that occur in a solid phase during deformation are analyzed. A hypothesis is proposed that these transitions can play a key role in the nucleation of primary fracture zones in solids. The validities of this hypothesis and the traditional models used to describe the fracture processes in solids are compared using the available experimental data.