Degenerating chondrocytes are often localized in the lower hypertrophic and calcifying zone of rat epiphyseal cartilage. The ability of these degenerating chondrocytes to synthesize and secrete sulfated proteoglycans was investigated using the light microscopic radiosulfate labeling method and the high-iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP) method for sulfated complex carbohydrates at the ultrastructural level. At 30 min following intraperitoneal (IP) injection of ³⁵SO₄, only intracellular autoradiographic labeling was observed, whereas both intracellular and extracellular radiosulfate labeling was seen at 1 h postinjection. A gradual increase in intracellular and extracellular labeling was seen at 3, 12 and 24h following IP injection of ³⁵SO₄. In ultrastructural cytochemical preparations, HID-TCH-SP weakly to moderately stained the chondrocyte Golgi vacuoles or immature and intermediate secretory granules but did not stain Golgi saccules. Mature secretory granules and extracellular matrix granules demonstrated strong staining. These results therefore indicate that proteoglycans are sulfated in the degenerating chondrocyte Golgi vacuoles, packaged in the secretory granules and then released into the extracellular matrix to form matrix granules.

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Various ultrastructural studies on the periodontal ligament (PDL) microvasculature have been reported. However, the lack of a systematic classification has led to much confusion in the terminology used to define vessel types. On the basis of morphological criteria, the author proposes that 3 vessel types are present in the PDL : terminal arterioles (Type A vessels), capillaries (Types B-1 & B-2) and postcapillary venules (Type C vessels). Morphometric analysis of the apical PDL revealed that the total vascular volume was 19.9%. Type C vessels predominated with a vascular volume of 16.4% while the other 2 vessel types made up the remainder of the vascular volume. The results of this study suggest that the apical PDL region is predominantly venous.

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Thyroid-stimulating hormone (TSH) potency was measured as thyroxine-releasing activity in cultured quail thyroid glands, each of which was preincubated with shaking for 2 h in 1 ml of medium 199, pH 7.4, under a constant flow of 95% O₂ and 5% CO₂ at 37°C. The gland was then incubated for 3 h in 250 μl of the medium, which contained a reference or sample preparation. The thyroxine (T₄) concentration in the medium was determined by radioimmunoassay and used as an index of the TSH activity. In this bioassay, 7.8 μg of acetone-dried chicken pituitary gland (A1D) induced a significant increase in T₄ secretion. A linear log-dose-response relationship in a dose range between 7.8 and 500 μg was observed. The precision index of this assay was 0.19. Intra- and inter-assay coefficients of variation were 55% and 59%, respectively. Partially purified chicken pituitary glycoprotein showed higher TSH activity than A1D. Bovine TSH also showed TSH activity. Human chorionic gonadotropin showed slight activity. Chicken follicle-stimulating hormone and quail brain extracts both indicated negligible activity. Some pituitary extracts of Columba livia domestica, Melopsittacus undulatus, and Coturnix coturnix japonica showed the same TSH activity as that of chicken. This microbioassay system offers sufficient sensitivity and will be availavle for the specific measurement of avian TSH.

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As a fundamental study on the electric method for measuring root canal length, the various factors which affect the measured impedance were investigated using a wide range of frequencies.
1) The impedance between two saliva ejectors in contact with the oral mucosa near the bilateral premolars in the lower arch generally showed low values. The difference between the maximum and minimum measured impedance was reduced and eventually approached zero as the frequency increased.
2) When a 1.0-mm length of the reamer tip was inserted into 2% agar containing 0.90% or 0.45% NaCl solution, the impedance in the former solution was lower than that in the latter.
3) When the impedance of a reamer covered with insulating tape except at the tip, and exposed in a glass tube containing 0.90% NaCl solution was compared, the former showed a higher value than the latter. The smaller the inner diameter of the glass tube into which the reamer was inserted, the higher was the impedance of the reamer.
In every case, the measured impedance and the difference between them decreased as frequency increased. With regard to the electric method for measuring root canal length, the application of high frequency of more than 30 kHz was considered to keep the influence of such factors to a minimum and contribute to the improvement of this method.

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The present studies were carried out with the aim of developing monomers for dental resin, for which the authors synthesized 13 kinds of monomers with a P-N-bond skeleton, containing polymerizing groups and hydrophobic groups in the molecule.
The conditions of synthesis and the properties of the monomers were then examined and the results obtained were as follows :
1. Of the 13 kinds of synthesized monomer, PNC-EMA monomer showed a comparatively large unsubstituted chlorine value of 0.28, whereas the rest showed values between 0.04 and 0.17.
2. In the 2nd step of synthesis, it was possible to shorten the reaction time from 100h to 50 h by raising the reaction temperature from 50°C to 60°C, but even when the temperature was raised to 70°C, the amount of unsubstituted chlorine was almost the same.
3. The specific gravity of PNC-Ph-EMA monomer showed a tendency to decrease in accordance with the increase in the number of substituents, while conversely, its refractive index increased. The specific gravity of PNC-TF-EMA and PNC-OF-EMA monomers also increased in accordance with an increase in the number of their respective substituent hydrophobic groups, while conversely, the refractive index decreased.
4. The viscosity showed a tendency to increase in the following order : PNC-TF-EMA<PNC-OF-EMA<PNC-Ph-EMA.

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A case of aspergillosis of the maxillary sinus followed by odontogenic sinusitis is reported. The Japanese literature on paranasal fungus infection was reviewed and discussed. In Japan, aspergillosis is the most frequently occurring of all paranasal fungus infections, but paranasal aspergillosis followed by odontogenic sinusitis is relatively rare. Most cases of odontogenic paranasal aspergillosis are of the non-invasive type.

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Although the rat is often used in experiments on bone transplantation, very few immunohistochemical studies on the distribution and proportions of lymphocyte subpopulations and subsets in rat lymphoid organs have been performed, in comparison with other animals. A preliminary immunohistochemical investigation using the immunofluorescence and avidin-biotin-peroxidase complex methods was therefore undertaken to clarify this aspect in various lymphoid organs taken from rats.
The results obtained were as follows :
1. Ia-positive cells largely indicative of B cells were localized in the lymphoid follicles of lymph nodes, follicular areas of Peyer's patches and non-periarteriolar lymphatic sheath (PALS) areas of the spleen.
2. T cells were densely distributed in the lymphoid pulp of lymph nodes, interfollicular areas of Peyer's patches and PALS areas of the spleen.
3. Helper T-and asialo GM1-positive cells were localized in the lymphoid pulp of lymph nodes, interfollicular areas of Peyer's patches and spleen red pulp. The numbers of positive cells with these phenotypes were smaller than those of Ia-and pan T-positive cells.
4. These results indicate that the distribution and proportions of lymphocyte subpopulations and subsets in rat lymphoid organs are generally similar to those of other animals such as the mouse.

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In the previous studies, correlation between natural background radiation exposure rates and cancer mortality rates in 46 Japanese prefectures was statistically studied over the period of 1950-1978. With regard to the correlation between natural background radiation exposure rate and crude (non-age-adjusted) cancer mortality rate, statistically significant positive correlation coefficients were observed in most cases of cancers with only a few exceptions. However, the significance of the correlation mostly disappeared through age-adjustment with only three exceptions. We examined the cause of this apparent correlation and found that natural radiation levels are positively correlated with prefectural population component ratios for those inhabitants older than 40, 50 and 65 years.
The atomic bombings of Hiroshima and Nagasaki could have affected the cancer mortality in these prefectures and it is reasonable to question the validity of statistical analyses by including these areas together with other prefectures. Therefore, in the present investigation, we carried out recalculations while excluding the data for Hiroshima and Nagasaki prefectures. In most cases of cancers, the correlation did not show any change. However, in the case of female pancreas cancer in 1968-1978, the significance level of negative correlatilon changed from 5% to 10%, and total female cancers and liver cancer for both sexes in 1968-1978 came to show a significant positive correlation at the 10% level.

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