Certain monomorphic cellular tumors that occur in the dermis have been called trabecular carcinomas or Merkel cell tumors. Forty‐six cases have been reported to date and the literature on these is reviewed here, with six additional cases reported. Cytologic features include sparse cytoplasm, dispersed chromatin with inconspicuous nucleoli in round nuclei and many mitoses. Trabeeulae and pseudorosettes may be identified. Electron microscopy is required for definitive diagnosis. Like normal Merkel cells, tumor cells contain electron‐dense granules (80–200 nm), 10 mm filaments and desmosomes. Filament‐rich cytoplasmic spikes were found in four tumors. These resemble corresponding protrusions of normal Merkel cells and have not been described in other APUDomas. Cancer 52:238‐245, 1983.

The structures of new antitumor antibiotics, glidobactins A (la), B (Ib) and C (Ic) were elucidated by a combination of chemical and enzymatic degradations and spectral analyses. They have in common a cyclized tripeptide nucleus composedof L-threonine, 4(S)-amino-2CE>pentenoic acid and (?ry^r

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Terpestacin, a new antibiotic which inhibits syncytium formation, was isolated from Arthrinium sp. FA1744(ATCC74132). The structure of terpestacin was elucidated as a bicyclic sesterterpene on the basis of spectroscopic data and chemical derivatization.

A novel complex of isotetracenone (angucyclinone) group antibiotics was discovered from the cultured broth of Streptomyces griseorubiginosus No. Q144-2. The antibiotic consisted of six related factors, designated rubiginones A1? A2, B^B2, Cx and C2. They significantly potentiated cytotoxicity of vincristine (VCR) against VCR-resistant P388 leukemia and Moser cells.

This system could assist surgeons in preserving the facial nerve and potentially contribute to enhanced patient safety in the surgery.

Sequence of reactions in the process of ternary complex formation of BMY-28864 with D-mannopyranosideand calcium was spectrophotometrically determined nnder more strict analytical conditions using metal-free preparations of sugars and the pradimicin derivative at a bandpass slit width of 1 nm. In the first phase of ternary complex formation, BMY-28864stereospecifically recognized and bound to D-mannopyranoside in the absence of calcium, which was revealed by a visible absorption maximumshift of ca. 8 nm. Subsequently, the BMY-28864-D-mannopyranoside conjugate reacted with calcium to yield the ternary complex, which was detected by an additional visible absorption maximumshift of ca. 8 nm. Whenthe three components were mixed at the same time, both phases simultaneously occurred to produce the ternary complex which was accompanied by a visible absorption maximumshift of 16 nm in total. Based on this two-phased reaction sequence, the mechanism of ternary complex formation of BMY-28864with D-mannopyranoside and calcium was reexamined in details. Terminal D-mannopyranoside was confirmed to be essential as BMY-28864-specific sugar receptor by in vitro analysis and animal cell experiments. While calcium, strontium and cadmium behaved similar in the in vitro ternary complex formation, the yeast and animal cell experiments showed that only calcium played a dual role as a base in the ternary complex formation and as an effector in physiological disturbances leading to cell death.In previous papers1~6), the antifungal activities of pradimicin derivatives were positively correlated with their lectin-mimic ternary complex formation by validating the essential roles of the C-18 carboxyl group and the C-5 thomosamine moiety of pradimicin derivatives. In consequence, characterization of the sugar-recognizing ability of pradimicin derivatives in the light of lectin biochemistry using highly-purified metal-free sugar and pradimicin preparations was considered to be informative and indispensable, as calcium and metal impurities in reagents probably interact or compete with the calcium componentof the ternary complex.The findings described in the preceding paper6) that BMS-184497 or BMY-28864methyl ester still retains as ability to showa visible absorption maximumshift of ca. 8nmin spite of the absence of the free C-18 carboxyl group; and that the breadth of the visible absorption peak shift depends on the status of the C-18 carboxyl group {ca. 8nm for the methyl ester and ca. 16nm for the free acid) allowed the hypothesis that the process of ternary complex formation might be divided into the sugar-recognization phase and the calcium salt formation phase. Therefore, the authors have attempted to elucidate the sequence of events in the visible absorption peak shift which seemed to be parallel with the process of ternary Correspondence should be addressed to Jun Okumura, Bristol-Myers

The structures ofantiviral antibiotics kistamicins A and B have been determined by a combination of chemical degradation and spectral analysis. They are commonly composed of D-tyrosine, 3,5-dihydrophenylglycine, a biphenyl ether bis-amino acid, and a diphenyl substituted indole tris-amino acid, forming a tricyclic ring structure. Kistamicin B possessed a phenethylamide at the amino terminal of kistamicin A. They are structurally related to the nuclei of the vancomycin group antibiotics particularly to antibiotic complestatin.In spite of the considerable effort expended to date, only a few compoundshave been discovered from natural sources that are effective against viruses. In our screening programfor fermentation metabolites, we have discovered two new antiviral antibiotics, designated kistamicins A and B in the culture broth of Microtetraspora parvosata subsp. kistnae subsp. nov. collected in India. The taxonomy of the producing organism and the production, physico-chemical properties and biological activities of kistamicins A and B, have been reported in preceding paper1}. In this report we present the structural studies on these antibiotics. Results and DiscussionKistamicins A (1) and B (2) were isolated from the fermentation broth of Microtetraspora parvosata subsp. kistnae subsp. nov. by 1-butanol extraction followed by column chromatography on silica gel and reversed phase silica gel1}. They were obtained as pale yellow powders; 1, C61H51N8O15C1, mp >300°C (dec), MS5 -1.8°(c 1.0, MeOH); 2, C70H60N9O16Cl, mp >300°C (dec), [a]^5 +22°(c 0.5, MeOH).The degradation and spectral studies for structure determination of kistamicins were first performed on 1. The UVspectrum of 1 exhibited absorption maxima at 231, 265, 284 and 305nmin MeOH, which moved to 244 and 286nm in alkaline solution. *H and 13C NMRspectra (Table 1) assisted with COSY experiments indicated the presence of seven aromatic and seven aliphatic units shown below.