Mutual recognition between polymerized liposomes. IV. Polysaccharide-lectin system.

As a model of cell-cell recognition processes, the association processes of a polysaccharide (mannan)-carrying liposome with a lectin (Concanavalin A, Con A)-carrying polymerized liposome were followed by turbidimetry. The association process was strongly inhibited by the addition of a low molecular weight sugar, methyl-alpha-D-mannopyranoside, which shows that the association between the liposomes is due to the specific interaction between Con A and mannan. The association rate constant obtained was much smaller than the theoretical value for a diffusion-controlled binary association process. This implies that the association rate of liposomes is limited by the recognition between complementary ligands bound on the liposome surfaces. Another reason for the smaller association rate constant in the liposome-liposome system is the repulsive hydration effect. The effect of the surface density of the lectin immobilized on the liposome on the recognition was also examined.     

Age-related differences in muscle activity, stride frequency and heart rate response during walking in water.

This study aimed to examine whether walking in water produces age-related differences in muscle activity, stride frequency (SF), and heart rate (HR) response. Surface electromyography (EMG) was used to evaluate muscle activities in six older and six young subjects while they walked in water immersed to the level of the xiphoid process. The trials in water utilized the Flowmill which consists of a treadmill at the base of a water flume. The measurement of maximal voluntary contraction (MVC) of each muscle was made prior to the gait analysis. The %MVCs, which refer to the surface EMG measures, from the gastrocnemius of the older subjects were significantly lower than those of the young subjects, in every experimental condition (P<0.05). In contrast, the %MVCs from the rectus femoris (P<0.05) and the biceps femoris (P<0.001) of older subjects were significantly greater than those of young subjects in every experimental condition. Moreover, the SFs of older subjects were also significantly greater than those of young subjects (P<0.05), while the HR responses of older and young subjects were similar. In conclusion, the older subjects had increased hip musculature activity and decreased ankle plantar flexor activity while walking in water, compared with the young subjects.     

Mutagenicity of N4-aminocytidine and its derivatives in Chinese hamster lung V79 cells. Incorporation of N4-aminocytosine into cellular DNA

N4-Aminocytidine induced mutation to 6-thioguanine resistance in Chinese hamster lung V79 cells in culture. Previous studies with experimental systems of in vitro DNA synthesis and of phage and bacterial mutagenesis have shown that this nucleoside analog induces base-pair transitions through its incorporation into DNA, with its erroneous base-pairing property. Incorporation of exogenously added [5-3H]N4-aminocytidine into the DNA of V79 cells was in fact observed in the present study. N4-Aminodeoxycytidine was not mutagenic for the V79 cells. Several alkylated N4-aminocytidine derivatives were tested for their mutagenicity in this system. Those with an alkyl group on the N'-nitrogen of the hydrazino group at position 4 of N4-aminocytidine were mutagenic, but those having an alkyl on the N4-nitrogen were not. These results are consistent with those previously observed in the bacterial mutagenesis systems, and agree with a mechanism of mutation in which a tautomerization of N4-aminocytosine is the necessary step for causing the erroneous base pairing.     

Characterization of tumor-associated fucogangliosides from PC 12 pheochromocytoma cells

PC 12h pheochromocytoma cells were subcutaneously transplanted into rat. We found the transplanted tumors accumulated some fucogangliosides associated with PC 12 cells. These gangliosides were isolated and purified by DEAE-Sephadex A-25 and Iatrobeads column chromatographies. Their structures were determined by fast atom bombardment mass spectrometry, proton nuclear magnetic resonance spectrometry, permethylation study, and sequential degradation using various exoglycosidases and mild acid hydrolysis. Two tumor-associated fucogangliosides were found to possess the blood group B determinant as follows: G6: IV2Fuc alpha, IV3Gal alpha, II3NeuAc, GgOse4Cer; G11: IV2Fuc alpha, IV3Gal alpha, II3 (NeuAc)2, GgOse4Cer. A ganglioside with the similar structure as ganglioside G6 was isolated from rat hepatoma cells (Holmes, E.H., and Hakomori, S-I. (1982) J. Biol. Chem. 257, 7698-7703). However, ganglioside G11 has not previously been reported in the literature. These fucogangliosides reacted with the monoclonal antibody prepared by immunizing mice with PC 12h cells. Other fucogangliosides were also found to accumulate in the transplanted tumor tissues. They were identified as fucosyl-GM1 and fucosyl-GDlb. These fucogangliosides did not react with the monoclonal antibody against PC 12h cells.     

Kinetic analysis of the binding of guanine nucleotide to bovine brain smg p25A

Bovine brain smg p25A, a guanine nucleotide-binding protein with a Mr of about 25,000, bound specifically GTP, guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) and GDP. The initial velocities of the binding of GTP gamma S to GDP-bound smg p25A and the dissociation of GDP from this protein increased by decreasing Mg2+ concentrations or increasing NaCl concentrations. The initial velocity of the binding of GTP gamma S to GDP-free smg p25A was not affected by changing Mg2+ concentrations. These results indicate that the dissociation of GDP from smg p25A limits the binding of GTP to this protein, and suggest that there is a protein stimulating the dissociation of GDP from smg p25A and thereby stimulating the binding of GTP to this protein in mammalian tissues. In fact, the protein stimulating the dissociation of GDP, but not of GTP gamma S, from smg p25A was detected in bovine brain cytosol.     

Radioimmunoassay for non-enzymatically glycated serum proteins

We have developed a radioimmunoassay (RIA) for nonenzymatically glycated serum proteins. The polyclonal antibodies prepared against reduced glycated human albumin were specific for the glucitollysine residues of serum proteins. Serum proteins from diabetic patients (n = 25) contained 5.3 +/- 2.8 nmoles of glucitollysine/mg protein, compared to 2.0 +/- 0.2 in controls (n = 20). The intra- and inter-assay variables were 3.2-6.2% and 4.4-8.6%, respectively. Results from this assay procedure correlated well with those from the boronate affinity chromatography procedure (r = 0.94; P less than 0.001). The data suggested that diabetic serum proteins contained at least 2.5 times as much immunochemically detectable glucitollysine residures as normal serum proteins after reduction of the proteins with sodium borohydride.     

A toxic substance produced by Nocardia otitidiscaviarum isolated from cutaneous nocardiosis

During our studies on toxic substances from clinically isolated Nocarida, a new isolate identified as Nocardia otitidiscaviarum from cutaneous nocardiosis was found to produce a toxic substance called HS-6 that had strong in vitro as well as in vivo toxicity. The mouse intraperitoneal LD₅₀ value was 1.25 mg/kg and the ED₅₀ value for L1210 cultured cells was 0.3 ng/ml. The structure of HS-6 was determined and found to belong to the 16-membered macrocyclic group with a molecular formula of C₄₃H₆₈O₁₂. HS-6 also showed activity against pathogenic fungi such as Cryptococcus neoformans.     

Studies on DNA markers (D4S10 and D4S43/S127) genetically linked to Huntington's disease in Japanese families

Summary This is the first full report on the genetic linkage between Japanese Huntington's disease and the DNA markers D4S10 and D4S43/S127. With use of the HindIII, BglI, and EcoRI polymorphisms detected at D4S10, and the combination of all these polymorphisms to give composite haplotypes, nine Japanese Huntington's disease families were found to be informative. Three recombinants for D4S10 were detected in these families, giving a maximum lod score of 1.662 at a of 0.10. Similarly, when we used the MspI and PvuII polymorphisms detected by D4S43/S127, five families gave informative results. No recombinant was detected in these families, giving a maximum lod score of 3.348 at a of 0.00. These results clearly support the view that the Japanese Huntington's disease gene may be identical with the Western gene, in spite of the lower prevalence rate in Japan.     

Antimutagenesis by factors affecting DNA repair in bacteria

The term 'antimutagen' was originally used to describe an agent that reduces the apparent yield of spontaneous and/or induced mutations, regardless of the mechanisms involved. The 'antimutagens' include 'desmutagens' and 'bio-antimutagens'. In this article, our attention was focused on the bio-antimutagens affecting DNA repair in bacteria. Cobaltous chloride reduced the frequency of mutations in Escherichia coli induced by MNNG. The possibility that metal compound inhibits the growth of mutagen-treated cells was examined. The results clearly showed that the antimutagen surely reduces the mutation rate. The target of cobaltous chloride was found to be cellular factors including Rec A. Vanillin and cinnamaldehyde had strong antimutagenic activities against UV, 4NQO and AF-2. They stimulated Rec A-dependent recombination repair functions in the mutagen-treated cells. Among plant materials, tannins possess antimutagenic activity against UV-induced mutations in E. coli. It has been found that tannic acid stimulates the excision repair encoded by the uvrA gene thereby reducing the yield of mutants. Substances which are antimutagenic in bacterial systems also had antimutagenic activity in cultured mammalian cell systems. Vanillin reduced the frequency of mutagen-induced chromosomal aberrations.     

Studies of Sl/Sld in equilibrium with +/+ mouse aggregation chimaeras. II. Effect of the steel locus on spermatogenesis

Mutant mice of Sl/Sld genotype are deficient in melanocytes, erythrocytes, mast cells and germ cells. Deficiency of melanocytes, erythrocytes and mast cells is not attributable to an intrinsic defect in their precursor cells but to a defect in the tissue environment that is necessary for migration, proliferation and/or differentiation. We investigated the mechanism of germ cell deficiency in male Sl/Sld mice by producing aggregation chimaeras from Sl/Sld and +/+ embryos. Chimaeric mice with apparent white stripes were obtained. Two of four such chimaeras were fertile and the phenotypes of resulting progenies showed that some Sl/Sld germ cells had differentiated into functioning sperms in the testis of the chimaeras. In cross sections of the testes of chimaeras, both differentiated and nondifferentiated tubules were observed. However, the proportions of type A spermatogonia to Sertoli cells in both types of tubules were comparable to the values observed in differentiated tubules of normal +/+ mice. We reconstructed the whole length of four tubules from serial sections. Differentiated and nondifferentiated segments alternated in a single tubule. The shortest differentiated segment contained about 180 Sertoli cells and the shortest nondifferentiated segment about 150 Sertoli cells. These results suggest that Sertoli cells of either Sl/Sld or +/+ genotype make discrete patches and that differentiation of type A spermatogonia does not occur in patches of Sl/Sld Sertoli cells.