Masaharu Domon

Two types of proliferating cell nuclear antigen (PCNA) complex formation in quiescent normal and xeroderma pigmentosum group A fibroblasts following ultraviolet light (uv) irradiation

We examined the relationship between the formation of proliferating cell nuclear antigen (PCNA) complex with DNA and nucleotide excision repair in human fibroblasts following ultraviolet light (uv) irradiation. PCNA complex formation was detected by the immunofluorescence method after methanol fixation and nucleotide excision repair activity was detected as the unscheduled DNA synthesis (UDS) by autoradiography labeled with [3H]thymidine. Quiescent normal cells showed a strong punctuated pattern of PCNA staining 5 min to 3 h and UDS 3 h after 10 J/m2 of uv irradiation, but they no longer showed PCNA staining and UDS 24 h after irradiation. In contrast, xeroderma pigmentosum group A (XP-A) cells, which lack UDS activity, did not show PCNA staining up to 30 min after irradiation; however, unexpectedly, they were stained 3 h and even 24 h after irradiation with their staining pattern being different from that in normal cells. Namely, the fluorescence spots in XP-A cells were larger in size and much smaller in number than those in normal cells. When XP-A cells were fused with normal cells with polyethylene glycol treatment, nuclei of XP-A cells showed a PCNA staining pattern similar to that of normal cells at 30 min, which was no longer detected 24 h after irradiation. These results suggest that there exist two types of PCNA complex formation, nucleotide excision repair-related and -unrelated, in human fibroblasts following uv irradiation.

A method for determination of fractal dimensions of sialographic images

A method for measuring the fractal dimension of radiographic images was devised by the modified pixel dilation (PD) method, and its accuracy was examined by two types of image analyzers: one controlled by a minicomputer and based on the hexagonal array of the pixels, and the other controlled by a personal computer and based on the square array of the pixels. It was shown that the fractal dimensions measured by using the image analyzers for three curves (straight line, Koch curve, and Sierpinski gasket) were deviated by less than 2.1% from the theoretical dimension. The time required for the measurements fell within 10 seconds by the minicomputer-controlled image analyzer, and within 12 minutes by the personal computer-controlled image analyzer, which contrasts to the 30 minutes or more required for measuring fractal dimensions by other available methods. Analysis of the ductal patterns in sialograms by this method indicated that the fractal dimensions were significantly different between normal parotids and parotids with Sjögren syndrome. The modified PD method can be used for measuring the fractal dimension of ductal patterns in sialograms. The measurements may serve as numerical gradings of the progression of disease.

A Changing Pattern of the Cell Cycle during the First Two Cleavage Divisions of the Mouse

The cell cycles of the early cleavage stages of the mouse were analyzed by examining Feulgen‐stained ova. The period from ovulation to the completion of second cleavage division was investigated. The ova donors were C57BL/6 × DBA/2 female mice, which were hormonally superovulated. To estimate the durations of DNA synthesis and mitotic phases of the cleavage divisions, the ova were pooled into culture medium, and as a function of time, aliquots were removed from the batch of pooled ova. The ova specimens were Feulgen‐stained and classified as the ova nuclei in G1, S, G2 or mitosis by use of a cytophotometric technique and then the durations of these phases were determined by probit analysis.

Fractal dimensions of ductal patterns in the parotid glands of normal subjects and patients with Sjögren syndrome.

RATIONALE AND OBJECTIVES.The sialographic ductal patterns of the parotid glands in patients with Sjögren syndrome were compared with those of normal patients by measuring the fractal dimensions. METHODS.Fractal dimensions were estimated using the modified pixel dilation method. RESULTS.The mean fractal dimension was 1.64 ± 0.06 for the normal glands and 1.39 ± 0.10 for the glands with Sjögren syndrome (P < .005). No correlation between the age or sex and fractal dimension was observed for both groups. In Sjögren syndrome, a significant difference in the fractal dimension was observed between the subgroup having punctuate fillings with a diameter less than 1 mm and the subgroup from 1 to 2 mm (P < .001). CONCLUSION.The fractal dimension is useful as a numeric grading of the complexity of the ductal pattern and the progression of parotid disease.

Dental radiographic signs characteristic to Hallermann-Streiff syndrome

A review of the literature and examination of a personally observed case led to the conclusion that anterior displacement of the temporomandibular joints provides a useful diagnostic criterion for the Hallermann-Streiff syndrome.

Modulation in protein phosphorylation during G2 phase of the cell cycle in two-cell mouse embryos.

The protein phosphorylation activities in extracts were assayed for 2-cell mouse embryos at three stages of the G2 phase of the cell cycle. The 2-cell embryos were unique in having a prolonged G2 phase and so easily staged at early G2 (EG2), middle G2 (MG2) and late G2 (LG2) by timing the embryo isolation from pregnant mice. The embryo extracts were used both as sources of protein kinases and their substrates. The phosphoproteins of the extracts were labelled with [gamma-32P]ATP and separated by electrophoresis on SDS-polyacrylamide gels. The present study revealed that protein phosphorylation increased 3-6-fold during the progression of 2-cell embryos from EG2 to LG2 and the level of protein phosphorylation at any stages was greatly decreased by the presence of cAMP. Thus, the protein phosphorylation system of 2-cell mouse embryos seems to differ from those reported systems in mammals in its negative dependence on cAMP.

Factors involved in the high radiographic sensitivity of E-speed films

A microscopic and densitometric analysis of the high speed and fog density of E-speed film was conducted. The grain sizes of silver bromide (AgBr) and developed silver metals were measured, and the optical densities of the film were compared by means of various development procedures. Silver bromide grains were found to be large and accounted for the high speed of the film. Development caused chains of silver metal clusters to form, which contributed to the larger fog density as well as the higher speed.