Synthesis and structure-activity relationships of bestatin analogues, inhibitors of aminopeptidase B.

Stereoisomers and analogues of bestatin, [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl]-L-leucine, were synthesized and tested for aminopeptidase B and leucine aminopeptidase inhibiting activity. Among the eight stereoisomers, the 2S stereoisomers exhibited strong activity. In a series of compounds in which the L-leucine residue of bestatin was substituted with other amino acids, only the one containing isoleucine showed more activity than bestatin. Norleucine, norvaline, methionine, valine, serine, glutamine, phenylalanine, glutamic acid, proline, and lysine analogues gave, in that order, decreasing activity. Alkyl and phenyl sub stitution for the benzyl group of bestatin decreased the activity markedly. p-Methyl-, p-chloro-, and p-nitrobestatins showed greater activity than bestatin.

Inhibitory effect of tripeptides containing L-Phe-L-Tyr on neuronal excitability.

Eight tripeptides containing L-Phe-L-Tyr were synthesized, and their effects on the excitability of a giant neurone (tonically autoactive neurone, TAN), identified in the suboesophageal ganglion of an African giant snail (Achiatina fulica Férussac), were examined. Of these tripeptides, the following three showed a marked inhibitory effect: L-Glu-L-Phe-L-Tyr (most effective; critical concentration: 3 X 10(-6)--10(-5) M), Gly-L-Phe-L-Tyr and sarcosine-L-Phe-L-Tyr. The TAN inhibition caused by L-Glu-L-Phe-L-Tyr was not due to an increased membrane permeability to chloride ions.

Synthesis of p-hydroxyubenimex.

p-Hydroxyubenimex, (2S,3R)-3-amino-2-hydroxy-4-p-hydroxyphenylbutyryl-L-leucine, was synthesized starting from D-tyrosine. The structure and stereochemistry of the synthesized product were confirmed by comparison with p-hydroxyubenimex that was chemically transformed from ubenimex, an aminopeptidase inhibitor of microbial origin. Compared to ubenimex, p-hydroxyubenimex is more active against aminopeptidase B but less active against leucine aminopeptidase. By using the synthetic p-hydroxyubenimex as a reference sample, one of the metabolites of ubenimex was identified as p-hydroxyubenimex. The (2R,3R)-stereoisomer of p-hydroxyubenimex was also prepared. However, its activity against aminopeptidases was much weaker.

A facile synthesis of bestatin.

Bestatin, an immunomodulator useful in cancer treatment with the structure: N-[(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl]-L-leucine, has been synthesized from N-acyl-alpha-aminoacetophenone. This novel method using readily available reagents and mild conditions can be applied to a large scale production of this useful agent. The overall yield of bestatin was 10.5% from N-acetyl-alpha-aminoacetophenone and 7.8% from N-benzoyl-alpha-aminoacetophenone.

Synthesis and biological activity of spergualin analogues. I.

Stable spergualin analogues were synthesized by substitutions of the alpha-hydroxyglycine residue of spergualin with various alpha- or omega-amino acids. The antitumor activity of these analogues against L1210 and their immunosuppressive effects on delayed-type hypersensitivity and antibody formation was then examined. Analogues substituted with glycine and L-serine showed significant biological activity but were less potent than 15-deoxyspergualin. Among the analogues synthesized so far, 10-[N-4-(4-guanidinophenyl)butyryl-L-seryl]-1,5,10-triazadecane has possessed the strongest antitumor and immunosuppressive activities.

Clinical significance and usefulness of quantification of telomerase activity in oral malignant and nonmalignant lesions.

We quantified telomerase activity (TA) in patients with oral and maxillofacial malignant and nonmalignant lesions, and compared it with their clinical status and grade of malignancy. Fifty-two malignant and 52 nonmalignant lesions were analyzed. All malignant lesions were pathologically diagnosed as oral squamous cell carcinoma (OSCC). Normal gingival tissue served as a control. These specimens were obtained by biopsy or surgical resection, and stored at -80 degrees C until use. TA was quantified by a fluorescence-based TRAP method. TA levels ranged from 0.00 to 95.24 (average 33.24)U/microgP in 52 malignant lesions, and from 0.00 to 79.35 (average 11.91)U/microgP in 52 nonmalignant lesions (P < 0.0001). TA was detected in 96.2% of malignant and 65.4% of nonmalignant lesions. There was no relationship between TA levels and clinical stages or YK classification. However, under WHO classification, there were significant differences (P < 0.05) between Grades I and III or II + III. Among nonmalignant lesions, epithelial dysplasia showed a significantly higher TA level than that of oral lichen planus (P < 0.05) and other benign lesions (P < 0.0001). Oral lichen planus also significantly differed from other benign lesions (P < 0.05). These results suggest that TA is related to the histological grade of malignancy, and is also useful as a prognostic predictor for precancerous lesions and conditions.

Assessment of 14 functional gene polymorphisms in Japanese patients with oral lichen planus: a pilot case-control study.

Oral lichen planus (OLP) is a refractory mucosal disease. Its pathogenesis is thought to involve immunologic and genetic alterations. To gain a better understanding of the genetic risk factors, the authors evaluated associations between 14 functional gene polymorphisms and OLP. 32 Japanese patients with OLP and 99 unrelated healthy Japanese controls were genotyped for 14 single nucleotide polymorphisms (SNPs) of genes that regulate host immune responses. Genotyping was performed with a modified version of the serial invasive signal amplification reaction. A trend towards over-representation of tumor necrosis factor receptor 2 (TNFR2) +587 G allele was found in the patients compared with the controls (allele frequency: P=0.049). The other 13 SNPs were unassociated with OLP. These results suggest that TNFR2 +587 gene polymorphism may be associated with susceptibility to OLP.

[Incidence of anti-Rho(D) antibody production in Japanese Rho(D)-negative women by Rh incompatibility between mother and fetus, and prognosis of the infants (author's transl)].

The series was collected in 1973-1977 from 15 hospitals in Gunma Prefecture where all pregnant women were Rh-typed and blood samples were checked for antibodies by this laboratory. The total number of Rho(D) negative pregnant women was 435 and of these, 20 had developed antibodies. Three of these 20 patients had received blood transfusions. Six of the antibody containing patients were first immunized during the period of observation. Three of these 6 produced the antibody in the course of a first pregnancy and 2 in second pregnancy and 1 in third. The antibody titers increased after 20th gestational week, especially after 30th through 40th week in most of the patients. Three out of 9 infants, whose mother's antibody titers increased no more than 256 folds by papain treated red cells received phototherapy. In the cases of antibody titers more than 256 folds, 9 out of 11 babies received exchange blood transfusion. The mature infants were all alive healthily. There was no Rho(D) negative woman who repeated intrauterine fetal death by hemolytic disease of the fetuses.

A rat tRNA gene cluster containing the genes for tRNAPro and tRNALys. Analysis of nucleotide sequences of the genes and the surrounding regions.

A lambda clone carrying a rat DNA fragment of 11.9 kb was isolated from a rat gene library with total rat tRNA as a probe. Nucleotide sequence analysis revealed that the DNA fragment contained six tRNA genes, three for tRNAPro and three for tRNALys. Of the six genes all but one tRNAPro gene have the same polarity. Each tRNA gene is separated by a DNA region of 0.1 to 3.6 kb. The 5'-flanking regions of the six rat genes in the cluster do not have any significant sequence homology, but in the 3'-flanking region, each gene has a short T cluster, which is supposed to be a transcription termination signal.

Cloning and nucleotide sequences of the linear DNA killer plasmids from yeast.

The linear DNA killer plasmids (pGKL1 and pGKL2) isolated from a Kluyveromyces lactis killer strain are also maintained and expressed its killer character in Saccharomyces cerevisiae. After these killer plasmid DNAs isolated from S. cerevisiae were treated with alkali, four terminal fragments from each plasmid DNAs were cloned separately. Using these and other cloned DNA fragments, the terminal nucleotide sequences of pGKL2 and the complete nucleotide sequence of pGKL1 were determined. The inverted terminal repetitions of 202 bp and 182 bp were found in pGKL1 and pGKL2, respectively. The pGKL1 sequence showed an extremely high A + T content of 73.2% and it contained five large open reading frames. The largest of these open reading frame was suggested to code for a membrane-bound precursor of glycoprotein subunit of the killer toxin.