Hajime Takagi

A wasp venom mastoparan‐induced polyphosphoinositide breakdown in rat peritoneal mast cells

The phospholipid metabolism of rat peritoneal mast cells stimulated with mastoparan, a secretagogue purified from wasp venom, was investigated. Mastoparan at 20 caused a rapid secretion of histamine. Mastoparan induced a transient decrease of phosphatidylinositol 4,5‐bisphosphate on 32P labeling and generation of a water‐soluble degradation product, inositol trisphosphate on [3H]inositol labeling, suggesting the activation of phospholipase C upon stimulation.

Prevalence of normal-tension glaucoma and primary open-angle glaucoma in patients with collagen diseases

PURPOSE To investigate the prevalence of normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG) in patients with collagen diseases and determine whether an immunocompromised condition is present in a subset of glaucoma patients. METHODS Three glaucoma specialists prospectively examined patients with collagen diseases. The diagnostic process included applanation tonometry, slit-lamp examination, gonioscopy, direct ophthalmoscopy, and automated static perimetry. Twenty-four-hour intraocular pressure monitoring was done when necessary. Using the results of a population-based survey conducted in Japan, we calculated an expected number of cases of NTG and POAG, and compared these with the actual number of cases. RESULTS Of the 153 patients with collagen diseases examined, we found 6 patients with NTG and 2 patients with POAG. Of these 8 patients, 2 with progressive systemic sclerosis (PSS), one with NTG, and the other, POAG, had a history of being on systemic steroidal therapy. The prevalence of NTG and POAG was significantly higher in women patients having collagen diseases as compared with normal women (P = .027). CONCLUSION Women patients with collagen diseases are highly susceptible to NTG and POAG.

Inhibitory action of phorbol myristate acetate on histamine secretion and polyphosphoinositide turnover induced by compound 4880 in mast cells

Rat peritoneal mast cells which had been preincubated with phorbol myristate acetate (PMA, 10 - 100 ng/ml) for 5 min did not elicit the full histamine secretion induced by a potent secretagogue, compound 48/80. Furthermore, this PMA-treatment was found to inhibit the agonist-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) in [32P]labeled cells. However, it was also observed that the level of [32P]PIP2 was markedly reduced by 5 min-incubation with PMA. This suggests the enhanced hydrolysis of PIP2 by PMA which was reflected in a greater formation of inositol trisphosphate (IP3). These observations indicate that the formation of IP3 may not be profoundly related to secretory response in mast cells.

Biphasic effect of phorbol myristate acetate on histamine secretion induced by compound 4880 in rat peritoneal mast cells

Rat peritoneal mast cells which had been preincubated with phorbol myristate acetate (PMA, 100 ng/ml) for 30 sec elicited an enhanced histamine secretion induced by a potent secretagogue, compound 48/80. But a longer (5 min) preincubation with PMA followed by the agonist-stimulation induced a suppressed histamine secretion. A 5 min-PMA-pretreatment inhibited the compound 48/80-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) in [32P]-labeled cells. PMA-treatment alone for 5 min induced an activation of Ca2+-efflux monitored by 45Ca2+. The inhibition of histamine secretion induced by a 5 min-PMA-pretreatment followed by the agonist-stimulation may partly be attributed to the decreased intracellular Ca2+ concentration, [Ca2+]i, probably due to the depressed PIP2 breakdown and enhanced Ca2+-efflux. On the other hand, a 30 sec-preincubation with PMA followed by compound 48/80-stimulation induced a slight but significant increase in histamine secretion. In this case, neither breakdown of PIP2 nor Ca2+-influx was enhanced to raise the [Ca2+]i. Although we are unable to explain the mechanism for the enhancement of histamine secretion by a short (30 sec) PMA-preincubation, these results suggest that the biphasic effects of PMA on histamine secretion are mediated by intracellular Ca2+ mobilization probably via protein kinase C activation.

Arachidonic acid release in rat peritoneal mast cells stimulated with antigen, ionophore A23187, and compound 48/80

Rat peritoneal mast cells respond to various types of secretagogues, such as antigen (receptor-mediated), A23187 (calcium mobilizing), and compound 48/80 (membrane perturbing), and release arachidonic acid from membrane phospholipids prelabeled with [3H]arachidonate. The rate of arachidonic acid liberation varied from one stimulant to the other. Ionophore A23187 (0.1 micrograms/ml) appeared to be most potent in releasing arachidonate among the three stimulants at which doses each secretagogue caused almost equivalent histamine secretion. However, upon stimulation with these three secretagogues, the radioactivity of phosphatidylcholine (PC) was markedly reduced with a concomitant increase of arachidonate radioactivity. Hydrolysis of PC by phospholipase A2 is likely to be the major route of arachidonic acid liberation in either IgE-mediated or non-IgE activation in mast cells.

Is there circadian variation of plasma endothelin (ET-1) in patients with systemic scleroderma (SSc)?

Forty-three patients with systemic scleroderma (SSc), 10 with non-SSc (6 cases of systemic lupus erythematosus and 4 cases of dermatomyositis), 14 cases of mild- or non-sclerotic type of scleroderma with capillaroscopic abnormalities of nailfolds (SSD; scleroderma spectrum disorders) and 10 healthy volunteers (HC) were subjected to examination of plasma levels of endothelin-1 (ET-1). The sex ratios (male/female) in the patients with SSc, non-SSc and HC were 7:36, 4:6 and 0:10, and the ranges of their ages were 22-74, 19-78 and 33-62 years old, respectively. The plasma levels of ET-1 in SSD, SSc (Barnett I;15), SSc (Barnett II;16), SSc (Barnett III;12 cases), non-SSc and HC were 1.67 +/- 0.37 2.04 +/- 0.58 2.04 +/- 0.68 1.85 +/- 041 191 +/- 0.7 and 1.31 +/- 0.34 pg/ml, respectively, confirming previous results from other laboratories. The plasma levels of ET-1 statistically differ between each collagen disease (SSD, SSc and non-SSc) and HC using Students t-test (P < 0.05). Although a statistically significant difference was obtained in the plasma levels of ET-1 between the SSc group (6 cases) and HC (6 cases) measured at 06:00, 12:00, 18:00 and 24:00 h, there was no significant circadian variation of plasma levels of ET-1 at these times in both the SSc group and HC. The present study revealed that (1) the ET-1 level in HC showed no circadian fluctuation, and remained at a low level (0.8-1.6 pg/ml). (2) When compared to HC, ET-1 in blood plasma of patients with SSc was elevated (0.3-3 pg/ml) throughout the day and night (P < 0.05). (3) ET-1 tended to increase more at midnight (24:00 h) in the SSc group without PSL treatment, though no statistical significance was obtained. (4) TAT showed a significant increase at noon (12:00 h) suggesting coagulation activity in patients with SSc, but PlC did not show a significant increase compared to HC. In conclusion, the observed increase of vasoconstrictive ET-1 in the patients with SSc throughout the day and night may make maintenance of peripheral blood flow more difficult, may have some biological origin and should be further investigated.

Ganglioside-induced terminal differentiation of human keratinocytes : early biochemical events in signal transduction

Previous studies have indicated that GQ1b, a tetrasialoganglioside containing two disialosyl residues, may be an important regulator of cellular differentiation in murine keratinocytes. In the present study, we examined the effect of gangliosides on the differentiation of human keratinocytes. Current evidence indicates that GQ1b induces cornified envelope formation and enhancement of transglutaminase (TGase) activity, which are characteristic parameters of terminal differentiation in human cultured keratinocytes, while the other gangliosides, GT1b and GM1, are much less effective. The mass contents of inositol 1,4,5-trisphosphate (1,4,5-IP3) and the intracellular calcium concentration ([Ca+]i) were also measured in keratinocytes exposed to gangliosides. A rapid increase in 1,4,5-IP3 occurred at 30 s following stimulation, but no significant difference at the maximum level was observed among the three gangliosides in contrast to the finding in murine keratinocytes. In addition, [Ca+] increases occurred concurrently with the 1,4,5-IP3 generation by the three gangliosides. On the other hand, [Ca+] transients were unaffected by chelating extracellular Ca+ with EGTA. It is thus considered that the mobilization by 1,4,5-IP3 from internal stores plays a crucial role. These [Ca+]i profiles were also indistinguishable between the gangliosides. Taken together, in human keratinocytes, gangliosides differentially affect some other as yet unidentified site(s) in the post-calcium transmission pathway(s) which leads to TGase activation.

A case of soft tissue sarcoma in which complete remission was obtained when treated by the CYVADIC therapy.

症例: 25歳, 女性. 昭和61年3月中旬, 小指頭大. 弾性硬の皮下腫瘤を肛囲に気づいた。増大してくるため, 5月初旬に近医受診し, 右鼠径リンパ節腫脹を指摘され, リンパ節生検にてmalignant melanoma (リンパ節転移) を疑われ, 当科を紹介された。腫瘍は急速に増大し, 骨盤内を占めるようになり, 傍大動脈リンパ節, 左頸部リンパ節腫脹を認めた。リンパ節生検組織の病理学的検討からmalignant melanornaは否定され, 原発部Biopsy施行。デスミン陽性, 電子顕微鏡所見などより, 幼若な筋肉系肉腫と診断した。CYVADIC療法を6クール施行し, 腫瘍およびリンパ節腫脹は全く消失した。再発や転移をみとめず, 化学療法を追加し経過観察中。