C-prolinylquercetins from the yellow cocoon shell of the silkworm, Bombyx mori

Two flavonoids containing the l-proline moiety, 6-C-[(2S,5S)-prolin-5-yl] quercetin (prolinalin A) and 6-C-[(2S,5R)-prolin-5-yl] quercetin (prolinalin B), were isolated from the cocoon shell of the silkworm, Bombyx mori. Their structural elucidation was achieved by application of acid hydrolysis and spectroscopic methods. These compounds were not found in the leaves of mulberry (Morus alba L.), the host plant of the silkworm, suggesting that the flavonoids are metabolites of the insect. This is the first time that flavonoids with an amino acid moiety have been found as naturally occurring compounds.     

Robustness of optimal mixed strategies

 Mixed strategies, or variable phenotypes, can evolve in fluctuating environments when at the time that a strategy is chosen the consequences of that decision are relatively uncertain. In a previous paper, we have shown several examples of explicit forms of optimal mixed strategies when an environmental distribution and payoff function are given. In many of these examples, the mixed strategy has a continuous distribution. In a recent study, however, Sasaki and Ellner proved that, if the distribution of the environmental parameter is modified in certain ways, the exact ESS distribution becomes discrete rather than continuous. This forces us to take a closer look at the robustness of optimal mixed strategies. In the current paper we prove that such strategies are indeed robust against small perturbations of the environmental distribution and/or the payoff function, in the sense that the optimal strategy distribution for the perturbed system, converges weakly to the optimal strategy distribution for the unperturbed system as the magnitude of the perturbation goes to zero. Furthermore, we show that the fitness difference between the two strategies converges to zero. Thus, although optimal strategies in ‘ideal’ and perturbed systems can be qualitatively different, the difference between the distributions (in a measure theoretic sense) is small. Received: 27 October 1996 / Revised version: 5 March 1997     

Isolation from a coastal fish of Vibrio hollisae capable of producing a hemolysin similar to the thermostable direct hemolysin of Vibrio parahaemolyticus.

A vibrio isolated from the intestine of a coastal fish was identified as Vibrio hollisae by its biochemical characteristics. The isolate reacted with the gene probe for the thermostable direct hemolysin of Vibrio parahaemolyticus. The hemolysin produced by the isolate from the fish had traits identical to those of the thermostable direct hemolysin-like hemolysin produced by a clinical strain of V. hollisae.     

Differentiated properties characteristic of renal proximal epithelium in a cell line derived from a normal monkey kidney (JTC-12)

Summary The JTC-12 cell, an established cell line derived from a normal monkey kidney, was studied in an attempt to characterize the epithelial qualities. Phase contrast microscopy showed dome formation in confluent monolayers and electron microscopic examinations revealed the presence of numerous microvilli on the apical membranes and desmosome between cells. Sonicated cells showed activities of γ-glutamyl transpeptidase, leucine aminopeptidase, alkaline phosphatase, and trehalase, marker enzymes of renal proximal epithelium. Alkaline phosphatase activity exhibited the characteristics of a renal type isozyme. Furthermore, confluent JTC-12 monolayers exhibited Na⁺-dependent transport of hexose, amino acid as well as inorganic phosphate. These findings indicate that JTC-12 cells in monolayer culture maintain ultrastructural, biochemical, and physiological properties of renal proximal epithelial cells. This cell line will be useful for further studies on cellular functions of renal proximal epithelium. This work was supported in part by grants from The Ministry of Health and Welfare of Japan and from the Ministry of Education, Science and Culture of Japan.     

Sensitivity of renal brush-border Na+-cotransport systems to anions

The effect of anions on Na+-cotransport of succinate, lactate, glucose, and phenylalanine was studied under voltage clamped conditions in brush-border membrane vesicles prepared from rabbit renal cortex. The initial rate of succinate uptake varied by an order of magnitude depending on the anion: the highest rates were obtained with fluoride and gluconate, and the lowest with iodide. The anion sequence corresponded with the inverse of the anion hydration energies. The kinetics of succinate uptake were measured in the presence of fluoride and chloride. There was no difference in the maximal rates of uptake, but the Kt in fluoride (0.30 mM) was less than half that in chloride (0.70 mM), i.e. Cl- behaved as a competitive inhibitor of succinate transport with a Ki of 150 mM. The uptake of L-lactate, D-glucose and L-phenylalanine was less sensitive to anions, and there was no correlation with hydration energies. We conclude that the anion effects on sugar and amino acid uptakes measured under open-circuit conditions are largely due to variations in membrane potential, but in the case of the dicarboxylate transporter anions behave as weak competitive inhibitors. The specificity of the anion inhibition suggests that the dicarboxylate binding sites have a weak field strength relative to water.     

A case of calcitonin producing adenoma of the thyroid

A thyroid tumor about 4 cm in diameter was removed from a 53-year-old female. The clinical features were those of common thyroid adenomas, such as soft, smooth-surfaced and round contour of the tumor, no calcification and no lymph node metastasis. However, microscopically, the tumor was composed of compact cell nests rather similar to paraganglioma without any follicle formation. Histochemical examination revealed its C-cell nature, such as argyrophilia and calcitonin activity, although no amyloid deposit was demonstrated. Extremely high levels of calcitonin were found in the stored serum taken pre-operatively, but serum carcinoembryonic antigen levels were within normal limits. The calcitonin level dropped to the normal range soon after the operation, indicating the absence of residual tumorous tissues. Thus, the tumor behaves as an adenoma with a C-cell nature. Interestingly enough, the benign counterpart of medullary carcinoma of the thyroid seems to be quite rare in humans, and no similar tumors have ever been reported. Variations of C-cell tumors will be discussed in relation to their production and secretion of carcinoembryonic antigen.     

Use of nitrite and hypochlorite treatments in determination of the contributions of IQ-type and non-IQ-type heterocyclic amines to the mutagenicities in crude pyrolyzed materials

The mutagenic heterocyclic amines Glu-P-2, MeA alpha C and Phe-P-1, which possess a 2-aminopyridine structure in their molecule (non-IQ-type mutagens), were found to be inactivated by nitrite treatment under acidic conditions, as observed previously with Trp-P-1, Trp-P-2, Glu-P-1 and A alpha C. In contrast, MeIQx, 4,8- and 7,8-DiMeIQx, which were originally isolated from fried beef or heated model mixtures of creatinine, amino acids and glucose, and which have a 2-aminoimidazole moiety in their molecules (IQ-type mutagens), were very resistant to nitrite treatment like IQ and MeIQ. Both types of mutagenic heterocyclic amines were completely inactivated by treatment with hypochlorite. This differential inactivation of mutagenic heterocyclic amines by nitrite and hypochlorite was used in determination of the contributions of IQ-type and non-IQ-type mutagens to the total mutagenicities of various pyrolyzed materials. The percentage contributions of IQ-type mutagens to the mutagenicities of broiled sardine, fried beef, broiled horse mackerel, cigarette smoke condensate and albumin tar were 88, 75, 48, 6 and 4, respectively.     

High-performance liquid chromatographic determination of N1-alkylnicotinamide in urine

A simple high-performance liquid chromatographic method has been developed for determining N1-alkylnicotinamides, including C1-C5 alkyl derivatives, in urine. N1-Alkylnicotinamides were reacted with acetophenone in strong alkali medium at 0 degrees C and then formic acid was added. The reaction mixture was heated in acidic medium at above 93 degrees C, and the fluorescent product, 1-alkyl-7-phenyl-1,5-dihydro-5-oxo-1,6-naphthyridine, was chromatographed by HPLC, using a Zorbax SCX-300 column with a mixed mobile phase of acetonitrile-0.04 M ammonium phosphate, monobasic. N1-Alkylnicotinamides can be determined as 1,6-naphthyridine derivatives by a fluorometric detector at a level of 100 pg (signal/noise = 2). Recoveries of N1-alkylnicotinamides in urine were satisfactory. Interfering reaction products from NAD+ and NADP+ were clearly eliminated for determination of N1-alkylnicotinamides without pentyl derivatives.     

Role of macrophages as modulators but not as autonomous accessory cells in primary antibody response

The role of macrophages (M phi) in the in vitro primary antibody response of murine lymphocytes to sheep erythrocytes was investigated. Peritoneal M phi were activated to express Ia antigens either in vitro or in vivo. Nonactivated Ia- M phi were also examined. We observed that only Ia- M phi but also Ia+ M phi failed to trigger the antibody response, in contrast with splenic dendritic cells (DC) which served as potent and autonomous accessory cells, but that M phi modulated the level of response which was dependent primarily on the DC content of culture. The modulation appeared to incline to suppression rather than enhancement, when M phi were allowed to remain throughout the culture period for 4 days. A highly enhancing capacity of M phi, however, could be revealed by removing M phi 2 days after the initiation of culture, indicating that M phi exerted their suppressive effect more strongly in the late phase than in the early phase of in vitro antibody response. The modulatory activity seemed higher in Ia+ M phi than in Ia- M phi.     

Successful generation of cytotoxic T lymphocytes specific for self immunoglobulin-determinants on B lymphocytes

Cytotoxic T lymphocytes (CTL) specific for self immunoglobulin (Ig) determinants on B lymphocytes were successfully generated. These CTL were induced with stimulator B hybridoma cells bearing self Ig determinants in responders compatible with the stimulators in H-2 antigens but disparate in minor H antigens. Their specificities were directed toward the idiotype and probably the allotype structures of Ig receptors on stimulator B cells. However, no CTL specific for Ig structures other than the idiotype and the allotype were detected. These data indicate the presence of specific precursor CTL for self B cell clones and suggest the possible development and function of these CTL in certain situations.