RBE of a thermal neutron beam and the 10B(n, alpha)7Li reaction on cultured B-16 melanoma cells

The RBE of a thermal neutron beam and the 10B(n, alpha)7Li reaction were determined in cultured B-16 melanoma cells. The Kyoto University Research Reactor (KUR) was used as a thermal neutron source which had a very low contamination of gamma-rays and fast neutrons. The cells were irradiated with the beam in the presence or absence of 10B-boric acid. The absorbed dose from the neutron capture reaction to the cells was calculated by a method of Kitao (1975). Survival curves in both conditions had no shoulder and Do values were 0.506 or 0.604 Gy in the presence or absence of 5 micrograms 10B/ml-medium, respectively. The Do value of the 10B(n, alpha)7Li reaction was also estimated at 0.466 Gy, assuming each component of radiation was additive. The RBEs of the KUR thermal neutron beam and the 10B(n, alpha)7Li reaction relative to 60Co gamma-rays were estimated as 4.62 and 6.01 at 0.1 surviving fraction, respectively. Using these results, we calculated the absorbed dose from the 10B-compound and estimated the specific accumulation in the cultured cells of 10B-compounds which we have previously reported but not quantified (Nakanishi et al. 1980, Ichihashi et al. 1982).

The corneal endothelium in xeroderma pigmentosum

The corneal endothelia of 8 xeroderma pigmentosum patients were evaluated by means of a specular microscope. All cases but 1 showed decreased cell density and all cases of this series showed an increased coefficient of variation in cell area, compared to that of normal persons. The regression analysis between the cell density and age revealed a close affinity to that of the normal aging process when the ultraviolet-survival lethal dose of each patient was taken into consideration. The loss of corneal endothelial cells in the xeroderma pigmentosum patients may be caused at an extraordinary high rate, in proportion to their clonogenic ultraviolet-survival rate.

Melanosomal antigenic expression on the cell surface and intracellular subunits within melanogenic compartments of pigment cells: analysis by antimelanosome-associated monoclonal antibody

Antimelanosome-associated monoclonal antibody has recognized the common antigenic determinant of melanosomes and cell surface of pigment cells, and it is suggested that melanosomes play a significant role as an antigen in progressive depigmentary disorders, in which melanocytes are selectively altered and disappear presumably by auto-antibodies in vivo. Mouse myeloma cells were fused with spleen cells from BALB/c mice immunized with a melanosomal fraction separated from human melanotic melanoma cells (Mm-1-JCK). The monoclonal antibody (MoAb) A4F11 has been found to react with premelanosomes, melanosomes, and probably with Golgi-associated endoplasmic reticulum lysosomes, but not with mitochondria, nuclei, and cytosol from human melanoma cells, by immunoelectron microscopy using the saponin permeation method, which was carried out together with indirect radioimmunoassay and quantitative absorption assay. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting using melanosome preparations have revealed the antigen(s) reactive with the MoAb A4F11 in 3 bands corresponding to Mr 50,000, 18,000, and 17,000. Cell binding assay has shown the reactivity of the MoAb A4F11 with the cell surface of human normal melanocytes and melanoma cells, but not with other mammalian melanoma cells or with human nonpigment cells examined. Indirect immunofluorescence on cultured cells and frozen sections has revealed distinct granular reactivity not only with human melanotic melanoma, but also with junctional and intradermal nevi, cultured malignant blue nevus cells, as well as normal melanocytes. The above evidence has indicated the presence of an antigenic determinant common to the intracellular melanogenic compartments and to the cell surface of human pigment cells, regardless of their oncogenic differentiation status.

Time-dependent suppression of melanoma metastases and natural killer cell activation by interferon

The effect of murine alpha/beta interferon (IFN) on experimental metastasis was investigated using B16-F10 melanoma cells. Since the outcome of metastasis of blood-borne tumor cells is mainly determined within the first 24 h after i.v. inoculation of tumor cells, i.p. injection of IFN was focused on this critical early phase. The inhibition of pulmonary metastases by IFN was found to be maximal when given 3 h prior to tumor cell inoculation, while mice with 24-h and 12-h pretreatment and simultaneous IFN treatment also showed a reduction in metastases, but to a lesser extent. However, mice receiving IFN 2 h after tumor cell inoculation did not show any reduction. Tumor cells cultured for 24 h in IFN-containing medium showed no reduction in metastases. Administration of anti-asialo GMl prior to IFN treatment was found to eliminate the inhibitory effect of IFN 3 h pretreatment. However, natural killer (NK) cell activity in vitro measured at 3 h, 13 h and 24 h after IFN administration was enhanced to the same extent, not paralleling the inhibitory effect on pulmonary metastases. These data indicate that prepared host status against blood-borne tumor cells is established by IFN pretreatment, being maximal when injected several hours prior to tumor cell inoculation, and that this effect is substantially dependent on NK cell activity, though the implication of other factors is not excluded.

A case of porphyria cutanea tarda with experimental light urticaria

Photobiological tests were carried out on a 32-year-old man who suffered from porphyria cutanea tarda (PCT). The patient developed an immediate type of skin reaction with erythema and whealing following monochromatic irradiation at 400 nm, but did not have any abnormal immediate skin reaction after exposure to natural sunlight. Pre- or simultaneous irradiation with visible light, wavelength greater than 650 nm, suppressed the development of urticaria induced by 400 nm monochromatic radiation. On the basis of these findings and our previous observation of an inhibitory spectrum in two cases of solar urticaria, we suggest that there is also an inhibitory spectrum in PCT. This could explain the extremely low incidence of immediate erythematous or urticarial reactions in sun-exposed skin in these patients.

A mild form of xeroderma pigmentosum assigned to complementation group G and its repair heterogeneity

The specific heterodikaryon complementation results allowed us to allocate a 37-year-old female patient with xeroderma pigmentosum (XP31KO) to complementation group G of rare incidence. A mild form of XP31KO as the third group G patient manifested normal skin reaction to phototest, no physical or neuromental abnormalities, and a basal cell epithelioma, in contrast to the reference group G XP2BI. XP31KO cells showed 25% unscheduled DNA synthesis (UDS) after 10 J/m2 UV compared to less than 5% UDS in XP2BI cells and less hypersensitive responses to UV radiation and 4-nitroquinoline-1-oxide killings than did XP2BI cells. Such a repair phenotype of XP31KO presents an intragroup-G heterogeneity.

Solar urticaria. Further studies on the role of inhibition spectra

A 27-year-old woman exhibited an urticaria only to monochromatic light in the range from 400 to 525 nm, but not to polychromatic light longer than 360-nm ultraviolet (UV) and visible light. An urticarial response induced by 475-nm monochromatic light was completely inhibited by preirradiation, simultaneous irradiation, and postirradiation with light having wave bands longer than 650 nm. Two other patients with sunlight-induced solar urticaria, who had an erythema-and-wheal reaction during and after exposure to sunlight, had no suppressive wave bands in either the UV or visible-light range. These observations strongly indicate an important role for inhibition wave bands in the development of light-induced immediate erythema and urticaria. In some cases of solar urticaria, preirradiation and postirradiation with longer visible light wavelengths could be useful in preventing the development of urticaria.

Assignment of 2 patients with xeroderma pigmentosum to complementation group E

Xeroderma pigmentosum (XP) fibroblast strains derived from XP24KO and XP26KO patients with mild clinical manifestations were similarly twice as sensitive to 254 nm UV killing as normal cells and had a reduced level of 30-55% unscheduled DNA synthesis (UDS) after irradiation with 10 J/m2. Complementation analysis in the hybridized heterodikaryons revealed that XP24KO and XP26KO cells were only unable to complement the reference XP2RO group E cells, despite sufficient complementation to give rise to the normal level of UV-induced UDS with cells of all the other reference XP groups. Nor did XP24KO cells complement XP26KO cells. Therefore, the above 2 unrelated XP patients were assigned to complementation group E. The present group E assignment is the first in Japan, and perhaps the second in the world, the first being the XP2RO/XP3RO second-cousin relationship in The Netherlands (now 4 patients in group E).

Glycosaminoglycan synthesis in untransformed and transformed Werner syndrome fibroblasts: a preliminary report

Glycosaminoglycan (GAG) synthesis was studied in untransformed and transformed normal and Werner syndrome (WS) fibroblasts, because WS manifests pleiotropic abnormalities in connective tissue. Continuous labelling of cells with [3H] glucosamine and [35S] sulfate for 48 hours revealed enhanced synthesis of cellular GAG, more rapid transfer of these into the pericellular fraction, and more accumulation of GAG in the medium in cultures of untransformed WS fibroblasts compared with cultures of normal diploid cells. Total GAG in the 24 hour medium from confluent cultures was composed of 80-90% hyaluronic acid (HA) and 10-20% sulfated GAG (S-GAGs) in both untransformed normal and WS fibroblasts, whereas it was approximately 50% each HA and S-GAG in transformed normal and WS cells. The proportional enhancement of [35S] GAG synthesis in response to exogenous beta-D-xylopyranosides was similar in normal and WS cells, although transformed cells demonstrated only approximately one-half the enhancement observed in non-transformed cells. Thus, the overall activity of GAG synthesis is not grossly altered by the WS gene mutation. Enhanced synthesis and accumulation of HA and dermatan sulfate (DS) in the medium was characteristic of untransformed WS fibroblasts, but appeared to be normalized in an SV40-transformed WS cell line (PSV811), as in transformed normal cells (WI38CT-1). We need more experiments to determine whether aberrant GAG metabolism in WS cells is a direct or indirect expression of the primary gene defect.

Abnormal fibroblast aging and DNA replication in the Werner syndrome

Cell and DNA replicative potentials were studied in 10 strains of skin fibroblasts from unrelated patients with the Werner syndrome (WS) and in a progeric CRL 1277 strain. The lifespans of all WS strains and of CRL 1277 cells are greatly abbreviated in vitro, due to large fractions of non-cycling cells and the basic process of progressive clonal attenuation during Phase II. In some WS strains, the population-doubling rate per day and the cloning efficiency fluctuated concurrently in random fashion during the cellular aging process, indicating alternating successions of adaptively well and poorly growing clones, probably resulting from various chromosome translocations. No detectable defect in excision repair was found in WS or CRL 1277 cells. However, the rate of increase in the molecular weight of pulse-chased DNA involving overall rates of chain elongation and replicon fusion was retarded in WS and CRL 1277 cells. Also, pulse-labelled DNA in WS fibroblasts was less enriched in the nuclear matrix and was more slowly chased out than in normal cells. These results led us to postulate a misfiring or delayed initiation due to the sticky attachment of replicating DNA to the nuclear matrix in the replisomes of WS fibroblasts. A suggested model for abnormal DNA replication is presented and discussed to explain the loss of DNA and the chromosome abnormalities in WS cells. The abnormal DNA-synthetic profiles so derived appeared to be normalized in SV40-transformed PSV811 (WS) cells as were in gamma ray-transformed wild-type WI38CT-1 cells.