Far-infrared spectra of poly(-α-amino acids) with basic alkyl group side chains

Far-infrared spectra in the region from 700 to 60 cm^?1 have been measured for the α-helix structures of poly(L -α-amino-n-butyric acid), poly-L -norvaline, poly-L -norleucine, and poly-L -leucine and for the β-form structures of poly(L -α-amino-n-butyric acid), poly-L -valine, poly(DL -amino-n-butyric acid), poly-DL -norvaline, and poly-DL -norleucine. The changes of the spectra on N-deuteration have been measured in the region between 700 and 400 cm^?1. It is concluded that, the α-helix has characteristic bauds near 690, 650, 610, 380, 150, and 100 cm^?1, and that the β-form has characteristic bands near 700, 240, and 120 cm^?1. The main-chain vibrations in the region from 600 to 200 cm^?1 are strongly coupled with the side-chain deformation vibrations.     

The stem cells of a primordial germ cell-derived teratocarcinoma have the ability to form viable mouse chimeras

A euploid testicular teratocarcinoma line, STT-3, has been established from a tumor spontaneously occurring in the testis of a 129/Sv-ter male. Developmental ability of the STT-3 stem cells was tested by injecting these cells into mouse blastocysts. The frequency and the extent of chimerism were examined in mid-gestational fetuses and in live-born mice. STT-3 stem cells form viable chimeras at a high rate and differentiate into normal tissues. This is the first reported testicular teratocarcinoma-derived stem line with a proven capacity to form viable chimeric mice upon injection into the blastocysts.     

Effects of endotoxin (lipopolysaccharides) on experimental aspergillosis in leukemic mice

In an attempt to evaluate effects of bacterial endotoxin on systemic fungal infection, experimental systemic Aspergillus infection was induced in leukemic mice (AKR strain) with (Group B) or without (Group A) preceding intraperitoneal administration of Pseudomonas aeruginosa derived lipopolysaccharides. All mice in group A died within 4 days after intravenous inoculation of Aspergillus fumigatus spores and developed extensive and disseminated fungal lesions without inflammatory reactions. In contrast, 5 of 10 mice in group B were alive at day 4 and 1 mouse in group B was alive when the experiment was terminated on the 14th day. These mice showed less extensive fungal lesions with definite, albeit minimal, inflammatory reactions which were composed of macrophages and neutrophils. In addition, serum iron levels and iron saturation rates were significantly lower in mice in group B than in group A. These results indicate that P. aeruginosa endotoxin has a deterring effect on systemic Aspergillus infection in leukemic mice.     

Comparison of enzyme phenotypes in human bladder tumours and experimentally induced hyperplastic and neoplastic lesions of the rat urinary bladder

The expression of a number of enzymes involved in drug metabolism, membrane function etc. was compared in hyperplastic and neoplastic lesions of the rat bladder and in human bladder tumours. Transitional cell carcinomas (TCC) in both rat and Man were characterized by decreased alkaline phosphatase (ALP) and increased gammaglutamyl transpeptidase (GGT), β-glucuronidase (β-Gl), succinate dehydrogenase (SD) and glucose-6-phosphate dehydrogenase (G6PD) activities. In addition, binding for antibodies specific for different cytochrome P-450 species (UT₅₀, PB_3a, MC₁, MC₂) and microsomal epoxide hydrolase (mEHb) was elevated in both murine and human tumours. Comparison of the enzyme phenotype in hyperplastic lesions induced by freeze ulceration or uracil administration with that in preneoplastic papillary or nodular hyperplasia (PNH) and TCC suggested, however, that most of the alteration in enzyme content or activity was non-specific and related to requirements for epithelial cell proliferation. On the other hand, the decreased ALP, and increased GGT and β - Gl activity appeared more directly related to neoplastic transformation. The results suggested that qualitative differences exist between reactive hyperplasia and preneoplastic or neoplastic lesions in the urinary bladder. The finding of increased cytochrome P-450, in clear contrast to the reduction characteristic of preneoplastic hepatic lesions, may be important with regard to the observed difference in neoplastic transformation between the bladder and liver in response to drug metabolising enzyme inducers. Supported by Grants-in-aid for Cancer Research and a Comprehensive 10 Year Strategy for Cancer Control from the Ministry of Health and Welfare, for Cancer Research and Scientific Research from the Ministry of Education, Science and Culture, and by a grant from the Deutsche Forschungsgemeinschaft     

Localization in situ of c-myc mRNA and c-myc protein in adult mouse testis

Summary It has been suggested that c-myc, one of the proto-oncogenes, plays a role in normal somatic cell proliferation and differentiation. To define whether c-myc is only expressed during somatic cell division or is also expressed during meiotic cell division, the production of c-myc mRNA and protein were investigated in the mouse testis by usingin situ hybridization with non-radioactive DNA probes and enzyme immunohistochemistry respectively. Forin situ hybridization, T-T dimerized DNA probes were used and DNAs hybridizedin situ were detected immunohistochemically using specific antibody against T-T dimer. The results indicate that c-myc mRNA and protein are expressed in a cell-cycle-dependent manner only in spermatogonia and not in spermatocytes and spermatids.     

Restoration of Mismatch Repair Functions in Human Cell Line Nalm-6, Which Has High Efficiency for Gene Targeting

Gene targeting is a powerful approach in reverse genetics. The approach has been hampered in most of human cell lines, however, by the poor targeting efficiency. Nalm-6, a human pre-B acute lymphoblastic leukemia cell line, exhibits exceptionally high gene targeting efficiency and is used in DNA repair and the related research fields. Nonetheless, usage of the cell line is still limited partly because it lacks expression of MSH2, a component of mismatch repair complex, which leads to increased genome instability. Here, we report successful restoration of MSH2 expression in Nalm-6 cells and demonstrate that the recovery does not affect the high targeting efficiency. We recovered the expression by introduction of cDNA sequences corresponding to exons 9 to 16 at downstream of exon 8 of the MSH2 gene. Endogenous exons 9 to 16 were deleted in the cell line. The MSH2 expression substantially reduced spontaneous HPRT mutation frequency. Moreover, gene targeting efficiency in the MSH2-expressing cells was similar to that in the MSH2-lacking cells. In fact, we generated heterozygously REV3L knockout and the catalytically dead mutants in the MSH2-proficient Nalm-6 cells with efficiency of 20–30%. The established cell line, Nalm-6-MSH+, is useful for reverse genetics in human cells.     

Studies on the Bacterial α-Amylase,Especially in Regard to the Role of Calcium Contained

The role of calcium contained in crystalline bacterial α-amylase is observed, in part, from the effects on proteochemical properties of the enzyme caused by removal of the metal. The deprivation of calcium from the enzyme results, in fact, not only in loss of activity, but also in denaturation and change in electrophoretical properties of the enzyme protein. It indicates that the metal plays an important role just like a rivet on a fan to retain the native state as well as the activity of the enzyme.     

Raman spectra of copoly(D,L-alanines)

Raman spectra in the region 1000–150 cm^?1 were measured for copoly(D ,L -alanines) with the D -residue contents, 3, 7, 10, and 20%, and compared with the spectrum of the α-helical poly-L -alanine. The 532- and 378-cm^?1 peaks were assigned to the L -residues with a right-handed α-helix-like local conformation or to the D -residues with a left-handed α-helix-like local conformation. From the intensity of the latter peak the contents of these local conformations were estimated as a function of the D -residue contents for the copolymers. The 264-cm^?1 peak, which has been assigned to the breathing vibration of the α-helical poly-L -alanine, shows a marked decrease in its intensity upon the introduction of the D residues. This result suggests that the overall deformation vibration of the α-helix arises from rather long sequences of the L - and D -alanine residues with the α-helical conformation and that the intensity of this vibration depends on the content of these sequences in the copolymers.