L-Histidine decarboxylase (HDC) catalyzes the formation of histamine from L-histidine. This biogenic amine is known to exert various effects in physiological and pathological reactions. In contrast to the well-known mechanism of histamine action through its interaction with specific receptors, the mechanisms regulating HDC gene expression are not elucidated. We have purified HDC from mouse mastocytoma cells, and isolated mouse HDC cDNA, and found that the primary translated product is posttranslationally processed to yield a mature active enzyme. In mastocytoma cells, we demonstrated that the induction of HDC activity and HDC mRNA synergistically occurred on treatment with dexamethasone+TPA, and also cAMP+Ca²⁺. To clarify the mechanism of up-regulation by these stimuli of the transcription of the HDC gene, we have isolated a genomic DNA clone encoding 5'-flanking region sequence and the first two exons. The transcription start site and the nucleotide sequences of the promoter regions including TATA- and GC-boxes were determined. With mastocytoma cells transiently transfected with 5'deletion constructs of HDCCAT fusion gene, it was found that the sequences from -132 to -53 and -267 to -53 are essential for the regulatory elements involved in the increased transcription of the HDC gene with dexamethasone+TPA and cAMP+Ca²⁺, respectively. Furthermore, we have isolated a genomic DNA from human basophilic cells, and analysed its structure to elucidate the mechanisms regulating the tissue specificity of HDC gene expression.

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threo-Dihydroxyphenylserine (DOPS) is a synthetic amino acid which can be decarboxylated by L-aromatic amino acid decarboxylase to yield natural form of norepinephrine (l-NE), a principal neurotransmitter in both central and peripheral (sympathetic) nervous systems. Like L-Dopa as an agent for dopamine precursor therapy, DOPS was expected to have a potential as an agent for NE precursor therapy. Previous studies carried out by several groups in early 1970s, however, reached a negative conclusion that threo-DOPS was not an effective precursor of NE in the brain because of its low NE-increasing activity and weak pharmacological action. Since the latter half of 1970s, on the contrary, three Japanese research groups have successfully shown the possibility of DOPS as a useful NE-precursor. That is, Tanaka (Kobe Univ.) showed that L-threo-DOPS is the real l-NE precursor among four DOPS-enantiomers, and that it has several pharmacological activities such as a slow-onset and long-lasting pressor effect, an inhibitory effect on harmaline-induced tremor and so on. Hayashi and Suzuki (Osaka Univ.) found through the mobidity study on familial amyloid polyneuropatchy (FAP) that the progress of the disease develops NE-deficiency (NE-D), that severe orthostatic hypotention in FAP might be due to NE-D, and that L-DOPS has favorable effects on this symptom. Narabayashi (Juntendo Univ.) found that NE-D develops in patients with advanced Parkinson's disease (PD), that a freezing phenomenon in these patients might be associated with NE-D, and that L-DOPS improves the phenomenon. Based on these findings, the development of L-DOPS for registration had been undertaken by Sumitomo Pharmaceuticals Co., and an approval was given to it in 1989 as an agent for the treatment orthostatic hypotention in FAP or Shy-Drager syndrome and freezing phenomenon in PD. Preclinical and clinical studies done in the R & D confirmed that L-DOPS markedly restored NE-D and improved related-syndrome in the NE-deficient animals/patients, and that its actions were slow-onset, long-lasting and gentle. The R & D of L-DOPS described in this paper includes studies on industrial production, efficacy pharmacology (mode of action), metabolism and clinical trial of this agent.

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Retinoic acid acts as a specific modulator of cellular differentiation and proliferation. Its natural and synthetic analogs, classified as retinoids, can be applied to the chemotherapy in the field of dermatology and oncology. Various benzoic acid derivatives exhibited the specific biological responses of retinoic acid and were named retinobenzoic acids. Especially, the aromatic amides such as Am80 and Am580 have better therapeutic effects than retinoic acid. N-Methylation of these highly active aromatic secondary amides caused the disappearance of the activity due to the change of the amide conformation from trans into cis. From such observations, the conformation of the linking group between alkyl-substituted benzene ring and benzoic acid moiety is an important factor for the activity. Some retinobenzoic acids do not bind to the cellularretinoic acid-binding protein, but bind to nuclear retinoic acid receptors (RARs) with the binding affinity corresponding to the potency of their biological activities. Among them, Am80 can bind to two of the three RAR subtypes (RAR α and β). The selectivity is favorable for the clinical application of retinoid since it has possibility to elicit a part of a number of the biological activities of retinoic acid.

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The genetical and biochemical approach is used as a powerful tool for the elucidation of the metabolic regulation as well as the biological significance of various constituents in living cells. This technique has been successfully applied to the membrane phospholipids in mammalian cells, actually to phosphatidylserine, sphingomyelin, and cardiolipin, all of which are rather minor constituents in membrane phospholipids. Isolation and characterization of the mutant cells defective in biosyntheses and biosynthetic regulations of these phospholipids led to the new findings of the in vivo biosynthetic pathways and also of the biological significance of these phospholipids. By analyzing the five different kinds of mutant cells unusual in metabolisms of phosphatidylserine in CHO-K1 cells, we found a series of the following evidence. Phosphatidylserine is synthesized by the two kinds of base-exchange enzymes, namely serine-exchange enzyme I and II, through the chain reactions in participation of phosphatidylserine decarboxylase ; phosphatidylcholine→phosphatidylserine→phosphatidylethanolamine→phosphatidylserine. The substrates of serine-exchange enzyme I are phosphatidylcholine, and either choline, serine, or ethanolamine, while those of serine-exchange enzyme II are phosphatidylethanolamine, and serine or ethanolamine but not choline. The last phosphatidylserine produced in consequence of the chain reaction again becomes a substrate of phosphatidylserine decarboxylase, and so this metabolic flow of the biosynthesis of phosphatidylserine is finally connected to a cyclic reaction between phosphatidylethanolamine and phosphatidylserine catalyzed by serine-exchange enzyme II and phosphatidylserine decarboxylase. Localization of serineexchange enzyme I is on the cytoplasmic side of endoplasmic reticulum, while that of enzyme II is on its lumen side. There is a lot of evidence including our immunological observation that phosphatidylserine decarboxylase is exclusively located in the inner membrane of mitochondria. Thus, during the process of the above-mentioned reactions, phosphatidylserine have to move from endoplasmic reticulum to mitochondria, and phosphatidylethanolamine does from mitochondria to endoplasmic reticulum. The biological significance of these movements is now under investigation. Enveloped virus infection and its maturation are closely associated with the membrane functions of host mammalian cells. In order to get further information concerning the biological functions of phosphatidylserine and/or phosphatidylethanolamine in mammalian cell membranes, Sindbis virus infection system was examined. Deficiency of phosphatidylserine and/or phosphatidylethanolamine was found to give a profound effect on the maturation of the virus, mainly due to low efficiency of membrane fusion between the viral envelope and endosomal membranes of the host cells. All these results indicate that phosphatidylserine and/or phosphatidylethanolamine are essential to membrane fusion at least in enveloped viral infection. A temperature sensitive mutant of CHO-K1 cell with thermolabile serinepalmitoyl transferase, which catalyzes the first step in sphingolipid biosynthesis, was successfully isolated. Under the non-permissive condition the mutant cell has less than 1% of serine-palmitoyl transferase activity of the parent CHO cells and accordingly contains decreased amounts of all sphingolipids, namely sphingomyelin, glucosylceramide, and G_M3 ganglioside, indicating serine-palmitoyl transferase functions in the main pathway for sphingolipid biosynthesis. The temperature sensitive growth of this mutant suggested that sphingomyelin is responsible for cell growth, since only sphingomyelin (and sphingosine base) restored the growth of the mutant among the various sphingolipids. [the rest omitted]

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Benzylammonium N-alkylides were generated by reaction of N-[1-(trimethylsilyl) alkyl] benzylammonium salts with cesium fluoride in DMF or HMPA, and their rearrangement products were investigated. [2, 3] Sigmatropic rearrangement of the ylides initially occurred to give isotoluene derivatives and then they were transformed into Sommelet-Hauser rearrangement products and/or Stevens products. The isotoluenes having bicyclic structures were stable at room temperature and aromatized with the aid of a base. The relationship between the configuration of cyclic ammonium ylides and the rearrangement paths is described.

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The bacterial endotoxin content in human serum albumin (HSA) products measured by two different Limulus amebocyte lysate (LAL) test methods, colorimetric and kinetic turbidimetric methods, were compared. So far as endotoxin-specific LAL reagents which do not show a false-positive reaction with (1→3)-β-D-glucan are used, a definite correlation was found between the results with the two LAL test methods. Endotoxin added to HSA products was recovered in a quantitative manner showing neither inhibition nor enhancement by HSA to the both LAL test methods. Results of the LAL tests showed a significant correlation with that of the rabbit pyrogen test. The correlation was much improved with endotoxin-added HSA. The present results indicate the practical applicability of the LAL test as an alternative method for the rabbit pyrogen test.

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The suppositories of rifampicin (RFP) containing sodium para-aminosalicylate dihydrate (PAS-Na) were prepared in order to enhance the rectal absorption of RFP. By the addition of PAS-Na, the in vitro release of RFP from the suppositories was enhanced and the hardness of the suppositories decreased. The rectal absorption of RFP from the suppositories containing no PAS-Na (control suppositories) was significantly lower compared to oral administration of it (26%) in human subjects. When PAS-Na was added to the suppository (300 mg), both the area under the plasma concentration-time curve (AUC) and the maximum plasma concentration (C_max) increased significantly compared to those of the control suppositories. The rectal absorption of PAS-Na itself from the suppositories seemed to be fast. PAS-Na might increase the absorption of RFP dissolved in the rectal fluid from the suppositories, but not affect the undissolved RFP.

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Sesamol is a kind of antioxidant and exists in sesami oil. This paper describes the protective effect of sesamol against carbon tetrachloride (CCl₄)-induced liver injury in rats. Sesamol had a significant effect in case of intraperitoneal, subcutaneous and oral administration. In order to examine the relationship between the chemical constitution of sesamol and its protective effect, the protective effects of 20 kinds of sesamol related compounds against liver injury induced by CCl₄ were investigated in rats. Consequently, significant protective effects were found in methylenedioxybenzene, isosafrole, safrole, methylenedioxyaniline and methylenedioxyacetophenone. These five compounds had a methylenedioxy group in common. Though not all compounds having a methylenedioxy group had protective effects, it was considered that the protective effects of the methylenedioxy group were influenced by substituent groups on 4 position of methylenedioxy phenyl compounds. In addition, sesamol, methylenedioxybenzene and isosafrole showed significant protective effects against cholestasis induced by CCl₄.

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