[en] Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal unstressed cells as well as in many cancer cells where they are over-expressed. These proteins are characterized by cell physiology dependent changes in their oligomerization and phosphorylation status. These structural changes allow them to interact with many different client proteins that subsequently display modified activity and/or half-life. Nowdays, the protein interactomes of small Hsps are under intense investigations and will represent, when completed, key parameters to elaborate therapeutic strategies aimed at modulating the functions of these chaperones. Here, we have analyzed the potential pro-cancerous roles of several client proteins that have been described so far to interact with HspB1 (Hsp27) and its close members HspB5 (αB-crystallin) and HspB4 (αA-crystallin)

[en] The purpose was to identify human in vitro cell lines with a high relative cellular sensitivity to fast neutrons as compared to photons and to examine their relationship to intrinsic photon radiosensitivity and cellular proliferation kinetics. The clonogenic cell survival following exposure to low LET, 4 MeV photons or, high LET, 62.5 MeV (p → Be⁺) fast neutrons and the cell survival following exposure to low LET, 4 MeV photons or, high LET, 62.5 MeV (p → Be⁺) fast neutrons and the cell kinetic parameters of 30 human in vitro cell lines, covering a wide range of histologies, were analyzed alone and with previously published data of Fertil and Malaise. The relative survival at 1.6 Gy of neutrons (SF_1.6) compared to 2 Gy of photons (SF₂) and the cell kinetic parameters of the 30 cell lines were also compared. The relative lethality of 62.5 MeV fast neutrons was assessed by comparing the ratio α neutrons/α photons or SF_1.6 neutrons/SF₂ photons to SF₂ photons. Cellular proliferation kinetics were measured by flow cytometry following BrdU incorporation and the relationship of cellular proliferation to relative neutron lethality was measured by comparing the α neutron/α photon ratio to the labelling index (LI), potential doubling (T_pot) and ploidy. The majority of cell survival curves obtained following exposure to 62.5 MeV fast neutrons were curvilinear with beta values of similar order to those obtained with low LET 4 MeV photons. Comparison of alpha values for neutrons and photons revealed a relatively neutron sensitive subset of 9 out of 30 in vitro cell lines. This subset was not, however, distinguishable when 1.6 Gy of neutrons was compared to 2 Gy of photons. There was no correlation between cell survival with neutrons or photons and the cell kinetic parameters T_pot or LI or with DNA ploidy. 30 refs., 4 figs., 1 tab

[en] Autoradiographic techniques were used to investigate the characteristics of tritiated inositol(1,4,5)trisphosphate ([³H]IP₃) and inositol(1,2,3,4,5)tetrakisphosphate ([³H]IP₄) binding to human brain. In brain sections ([³H]IP₃) exhibited a two-site binding with K_D values of 87 nM and 9.3 μM respectively for the higher and lower affinity sites. [³H]IP₄, also bound to two sites with K_D values of 43 nM and 1.4 μM. respectively. With the conditions fixed in this study, [³H]IP₃ and [³H]IP₄ autoradiography in the cortex, caudate, hippocampus and cerebellum were performed. The most prominent [³H]IP₃ binding among these regions was found in the cerebellum, particularly in the molecular layer. Within the hippocampus, the subiculum and the CA1 region showed much more prominent binding than the other subfields. [³H]IP₄ binding was fairly homogeneous in the regions studied, with the exception of a slightly higher binding in the molecular layer of the cerebellum. (author)

[en] The relaxation kinetics of cell sorting are studied with the cellular Potts model. In contrast to previous reports, the increase in domain size is found to obey a power law (R(t)∼tⁿ). The growth exponent turns out to be n=1/3 for an even mixture of two cell types, where the domains for each cell type are interconnected and the kinetics are dominated by smoothing of the domain boundary. The exponent is n=1/4 for uneven mixtures where cell sorting proceeds via the diffusion-coalescence of circular cell domains. The exponent is explained by the decrease in motility of a cell cluster as a function of its size according to D(R)∼R^-2. Our results provide a theoretical framework for elucidating how cell populations migrate within tissue.

[en] Cutaneous malignant melanomas share a number of molecular attributes such as limitless replicative potential that define capabilities acquired by most malignancies. Accordingly, much effort has been focused on evaluating and validating protein markers related to these capabilities to function as melanoma prognostic markers. However, a few studies have also highlighted the prognostic value of markers that define melanocytic differentiation and the plasticity of melanoma cells to trans-differentiate along several other cellular pathways. Here, we provide a comprehensive review and evaluation of the prognostic significance of melanocyte-lineage markers such as MITF and melanogenic proteins, as well as markers of vascular epithelial and neuronal differentiation

[en] This issue is the collection of the papers presented at the title symposium. The 7 of the presented papers are indexed individually. (J.P.N.)

[en] Pathways both mediated by and independent of transferrin(Tf) and the TfR have been described for the accumulation of iron. Although it is not clear whether the same systems take up iron and gallium, these pathways may suggest the contention that uptake of Ga-67 can, in fact, occur by both Tf-independent and Tf-dependent systems and may share with Fe-59 in part the same mechanism for uptake. The predominant system by which uptake of both radiometals occurs may be different in the degree of the transformation at tumor. Transformed (MMSV/3T3) and untransformed (BALB/3T3) cells were incubated with luM of Ga-67-citrate of Fe-59-chloride for 15 min. at 37 .deg. C in either the presence or absence of Tf. After then, the monolayers were washed with HBSS or PBS, and the cells were solubilized in 1% SDS for gamma well counting and protein determinations. There were similarities, as well as differences, in the pattern of uptake of Fe-59 and Ga-67 presented both in ionic from and as bound to Tf. Both radiometals appeared gain to cells in either ionic or Tf-bound forms. Transformed cells appeared to accumulate more radiometal, either Ga-67 or Fe-59 in the presence of Tf than do the their untransforemd counterparts. Conversely the presentation of either radiometal in ionic form resulted in significantly greater accumulation of metal by the untransformed cells than those transformed. The efficiency for uptake of Ga-67 or Fe-59 in the absence of Tf was greater than for uptake of the Ga-Tf or Fe-Tf. However, the magnitude of difference in efficiency of uptake was greater for Fe-59(10-fold) than for Ga-67 (3-fold). Our results Supports the theory that both Tf-independent and Tf-dependent systems for the uptake of Ga-67 both systems operate oppositely between transformed cells and those untransformed, with uptake by the predominating in transformed cells by the Tf-mediated system and in untransformed cells by the Tf-independent. The uptake of Ga-67 by tumor may share with Fe-59 in part the same mechanism.

[en] The purpose of this study was to investigate the defects of the low level irradiation on the mitotic index of the basal cells in the buccal pouch of hamsters (golden hamster: APG strain). After colchicine was administrated to the hamsters through the intraperitoneal, the low level radiation (5461 mR) was exposed in the buccal pouch of hamsters. The mitotic index of the basal cells was estimated 2 hours after irradiation. The results were as follows: 1. The mean mitotic index of the control group was 4.32. 2. The mean mitotic index of the irradiated group was 2.46. 3. T-test of data in the irradiated group showed significant difference from the mitotic endex in the control group. These results suggested the lowered mitotic index of the irradiated group resulted from the low level irradiation.

No abstract available

[en] The induction of enzymatic photorepair (EPR) in ICR 2A frog cells and a derived mutant cell line DRP36 hypersensitive to solar UV was studied. Using clonogenic assays, when induced wild-type cells demonstrated an 8-fold increase of EPR the mutant cells displayed a near-background level of inducible EPR. The constitutive EPR in mutant cells, however, was the same as in wild-type cells. A mixed culture of ICR 2A and DRP36 cells showed an intermediate inducible EPR depending upon the cell ratio. Inducible EPR was also detected at the DNA level in wild-type cells, but not in mutant cells. 29 refs.; 2 figs.; 2 tabs