Pancreatic adenocarcinoma in a patient with Peutz-Jeghers syndrome: report of a case and literature review

We present a rare case of pancreatic adenocarcinoma in a 47-year-old man with the Peutz-Jeghers syndrome. The patient underwent pancreatoduodenectomy with partial resection of the portal vein. We also review the current literature concerning Peutz-Jeghers syndrome associated with malignant tumors, especially pancreatic cancer. To our knowledge, this is the first report of a Peutz-Jeghers syndrome patient with pancreatic cancer having pancreatoduodenectomy and pathologically diagnosed with invasive ductal adenocarcinoma of the pancreas. The Peutz-Jeghers syndrome patients with pancreatic cancer were relatively young. As the pancreatic cancer in these patients was advanced and most were unresectable at diagnosis, the prognoses of these patients were extremely poor. Surgical resection offers the only chance for cure or long-term survival for Peutz-Jeghers syndrome patients, if the tumor is localized without distant metastasis. Therefore, screening even for young patients with Peutz-Jeghers syndrome is necessary for early detection of cancer.

Seven-color fluorescence imaging of tissue samples based on Fourier spectroscopy and singular value decomposition

Seven-color analyses of immunofluorescence-stained tissue samples were accomplished using Fourier spectroscopy-based hyperspectral imaging and singular value decomposition. This system consists of a combination of seven fluorescent dyes, three filtersets, an epifluorescence microscope, a spectral imaging system, a computer for data acquisition, and data analysis software. The spectra of all pixels in a multicolor image were taken simultaneously using a Sagnac type interferometer. The spectra were deconvolved to estimate the contribution of each component dye, and individual dye images were constructed based on the intensities of assigned signals. To obtain mixed spectra, three filter sets, i.e., Bl, Gr, and Rd for Alexa488 and Alexa532, for Alexa546, Alexa568, and Alexa594, and for Cy5 and Cy5.5, respectively, were used for simultaneous excitation of two or three dyes. These fluorophores have considerable spectral overlap which precludes their separation by conventional analysis. We resolved their relative contributions to the fluorescent signal by a method involving linear unmixing based on singular value decomposition of the matrices consisting of dye spectra. Analyses of mouse thymic tissues stained with seven different fluorescent dyes provided clear independent images, and any combination of two or three individual dye images could be used for constructing multicolor images.

[A case of advanced gastric cancer with hepatic metastasis successfully treated by combined chemotherapy with UFT and lentinan]

We have experienced successful treatment of a hepatic metastasis of gastric cancer with UFT and lentinan. The patient was a 65-year-old male, who underwent distal gastrectomy for gastric cancer with hepatic and lymphatic metastases. After operation, administrations of UFT 300 mg/day and lentinan 2 mg/2 weeks were given, and the hepatic metastasis disappeared by 17 months. We performed a resection of the residual stomach and lymphatic metastasis at 52 months after operation. For over 5 years the patient has shown no evidence of a recurrence of the hepatic metastasis. This chemotherapy regimen was very effective and improved the patients quality of life.

L-selectin-specific autoantibodies in murine lupus: possible involvement in abnormal homing and polarization of CD4+ T cell subsets

One notable functional abnormality in murine and human systemic lupus erythematosus (SLE) is the defect in the production of IL-2 in association with the deficit in naive CD4+ T cells. The mechanism is unknown, but one idea is that naturally occurring autoantibodies with specificities to the naive CD4+ T cell subpopulation are related to this event. We selected hybridoma monoclonal autoantibodies from SLE-prone (New Zealand Black (NZB) x New Zealand White (NZW))F1 mice that reacted with restricted populations of CD4+ T cells. One of these, H32, was specific for L-selectin, as determined by 1) distribution of Ag H32 on lymphoid cells similar to Mel-14, an epitope of L-selectin; 2) shedding of 80-kDa molecules with epitope H32 from the surface of lymph node cells coincidentally with Mel-14, when stimulated with phorbol ester; 3) cross-inhibitory activities on Ag binding between H32 and Mel-14; and 4) reactivity of H32 with recombinant mouse L-selectin. Pretreatment of 51Cr-labeled lymphocytes from BALB/c mice with H32 significantly inhibited their homing to lymph nodes in vivo. The BALB/c splenic H32+ CD4+ T cell subset produced few cytokines except IL-2, thus corresponding to naive ThP-type cells. This subset was markedly selectively depleted in aged (NZB x NZW)F1 mice. There was an age-associated increase in frequencies and titers of anti-L-selectin autoantibodies in sera from (NZB x NZW)F1 mice. Thus, abnormalities of naive CD4+ T cell subset, including IL-2 production in subjects with SLE, are at least partly attributed to the generation of autoantibodies to L-selectin.

Precursor B cells for autoantibody production in genomically Fas-intact autoimmune disease are not subject to Fas-mediated immune elimination

The Fas/Fas ligand (FasL) system participates in regulation of the immune system through the apoptotic process. However, the extent to which abnormalities in this system are involved in the loss of self-tolerance and development of autoimmune disease not associated with Fas/FasL mutations remains unknown. The present study addresses this issue in Fas/FasL-intact, systemic lupus erythematosus (SLE)-prone (NZB x NZW) (NZB/W) F1 mice. While splenic B cells from 2-month-old mice before overt SLE expressed Fas poorly, in vitro stimulation with an agonistic anti-CD40 mAb up-regulated their Fas expression, thus revealing the existence of two populations: one was Fashigh and highly susceptible to anti-Fas mAb-induced apoptosis, and the other was Faslow and apoptosis-resistant. The Faslow cells were included in the CD5(+) B cell subpopulation and contained most of the cells that produced IgM anti-DNA antibodies. The isotype of anti-DNA antibodies switches from IgM to IgG in NZB/W F1 mice at ages beginning at about 6 months. These IgG anti-DNA antibodies were produced almost exclusively by a subpopulation of splenic B cells that spontaneously expressed low levels of Fas in vivo and were apoptosis-resistant. The findings indicate that precursor B cells for autoantibody production and presumably autoantibody-secreting cells in these mice are relatively resistant to Fas-mediated apoptosis, a finding supporting the concept that abnormalities of Fas-mediated apoptotic process are involved in the development of autoreactive B cells in Fas/FasL-intact autoimmune disease.

Is structural flexibility of antigen-binding loops involved in the affinity maturation of anti-DNA antibodies?

Effects of somatic mutations in Ig variable region genes on the affinity maturation of autoantibodies were investigated using single precursor B cell-derived anti-double-stranded DNA mAb generated from an autoimmune disease-prone (NZB x NZW)F1 mouse. Analyses of DNA sequences, homology modeling on a graphic computer and molecular dynamics simulation of antigen-binding sites showed that any single site of mutation and changes in the electrostatic or hydrogen-bonding potential of the residues and in the three-dimensional structure could not solely explain the difference in DNA-binding activities. However, a significant increase in the flexibility of antigen-binding Fv loops, particularly VL CDR1 and VH CDR3, was associated with affinity-maturated anti-DNA antibodies. Such high flexibility of the FV loops may provide the environment where the antibodies could effectively interact with antigen DNA, a model consistent with the 'induced-fit' hypothesis of antigen-antibody interactions.

Primary sequence of mitochondrial tRNA(Arg) of a nematode Ascaris suum: occurrence of unmodified adenosine at the first position of the anticodon

Mitochondrial tRNA(Arg) from a nematode, Ascaris suum, was purified and sequenced at the RNA level. An unmodified adenosine was found to exist at the anticodon first position, suggesting that, contrary to the conventional wobble rule, the anticodon ACG of the tRNA can translate all the CGN codons.

Mapping of a gene for the increased susceptibility of B1 cells to Mott cell formation in murine autoimmune disease

Mott cells, a pathologic state of plasma cells containing intracellular inclusions of Igs (Russell bodies), are frequent in lymphoid tissues of murine and human autoimmune diseases. However, neither the genesis nor the significance of Mott cells in autoimmune diseases is well understood. We found that B1, but not B2, cells were induced in vitro to form Mott cells in the presence of LPS or IL-5, but not other stimulants, in a much higher frequency in autoimmune New Zealand Black (NZB) and NZB x New Zealand White (NZB/W) F1 than in non-autoimmune disease-prone mice and notably athymic nude NZB/W F1 mice. Cell surface phenotypes of Mott cells were B220+ CD5+ CD43+ CD11b(dull), while those of peritoneal macrophages were B220- CD5- CD43(dull) CD11b+. We mapped a locus (provisionally designated Mott-1) controlling Mott cell formation that was tightly linked to microsatellite marker loci, D4 Mit70 and D4 Mit48, of autoimmune NZB mice, which is in close proximity to our recently mapped locus Imh-1 for hypergammaglobulinemia. This region contains candidate genes that may be relevant to the aberrant B cell activation and differentiation. We suggest that while the Mott cell by itself is not the effector for autoimmune disease, the genetically determined aberrant maturational process of B1 cells that underlies the pathogenesis of autoimmune disease forms the basis for Mott cell formation in a T cell-dependent manner.

Mapping of a gene for the increased susceptibility of B1 cells to Mott cell formation in murine autoimmune disease

Mott cells, a pathologic state of plasma cells containing intracellular inclusions of Igs (Russell bodies), are frequent in lymphoid tissues of murine and human autoimmune diseases. However, neither the genesis nor the significance of Mott cells in autoimmune diseases is well understood. We found that B1, but not B2, cells were induced in vitro to form Mott cells in the presence of LPS or IL-5, but not other stimulants, in a much higher frequency in autoimmune New Zealand Black (NZB) and NZB x New Zealand White (NZB/W) F1 than in non-autoimmune disease-prone mice and notably athymic nude NZB/W F1 mice. Cell surface phenotypes of Mott cells were B220+ CD5+ CD43+ CD11b(dull), while those of peritoneal macrophages were B220- CD5- CD43(dull) CD11b+. We mapped a locus (provisionally designated Mott-1) controlling Mott cell formation that was tightly linked to microsatellite marker loci, D4 Mit70 and D4 Mit48, of autoimmune NZB mice, which is in close proximity to our recently mapped locus Imh-1 for hypergammaglobulinemia. This region contains candidate genes that may be relevant to the aberrant B cell activation and differentiation. We suggest that while the Mott cell by itself is not the effector for autoimmune disease, the genetically determined aberrant maturational process of B1 cells that underlies the pathogenesis of autoimmune disease forms the basis for Mott cell formation in a T cell-dependent manner.

Effects of transgenic mixed-haplotype MHC class II molecules A alpha d A beta z on autoimmune disease in New Zealand mice

The MHC haplotype heterozygosity (H-2d/H-2z) acts as one major predisposing genetic element for autoimmune disease resembling systemic lupus erythematosus (SLE) in the F1 hybrid of NZB (H-2d) and NZW (H-2z) mice. To determine a possible role of mixed-haplotype A molecules, we introduced a transgene A beta z into H-2d/H-2d homozygous (NZB x NZW.H-2d)F1 mice, in which, compared with the original H-2d/H-2z heterozygotes, the incidence and titer of IgG anti-DNA antibodies, serum levels of nephritogenic retroviral gp70/anti-gp70 immune complexes (ICs) and the associated incidence of IC-type lupus nephritis were reduced. Evidence for the formation of mixed-haplotype A alpha d A beta z molecules in the transgenic mice was obtained by A beta z molecule expression on the cell surface of splenic B cells and macrophages, thymic epithelial cells and mature B cells in the bone marrow. A alpha d A beta z-restricted T cell clones showed good proliferative responses to spleen cells from the transgenic mice, to an extent much larger than seen in cells from the original (NZB x NZW)F1 mice, suggesting that the expression of functional A alpha d A beta z molecules on cells in transgenic mice is considerably high. Compared with findings in transgene-negative littermates and the original (NZB x NZW)F1 mice, the A beta z transgene to a greater extent promoted serum levels of IgM anti-double-stranded (ds) DNA antibodies and IgM anti-gp70/gp70 ICs in the transgenic mice. None the less, the production of IgG anti-dsDNA antibodies and IgG anti-gp70/gp70 ICs as well as the development of renal disease was markedly suppressed. Possible mechanisms of such effects of the transgene are discussed.

Polyethylene glycol-modified avidin: a novel agent for the selective extraction of biotinylated immune-complex in an aqueous two-phase system

Chicken avidin was chemically modified with 2,4-bis[O-methoxypoly(ethylene glycol)]-6-chloro-s-triazine (activated PEG2) to form PEG-avidin. The PEG-avidin, in which 78% of the amino groups were modified, retained 49% of the active biotin-binding sites. The modified avidin was partitioned preferentially into the PEG-phase in an aqueous two-phase system (PEG/dextran). Using PEG-avidin, the immune-complex formed between biotinylated anti-mouse IgG and its antigen IgG (mouse) molecules, was successfully transferred into the PEG-phase in an aqueous two-phase system. This finding leads to the effective isolation of a specific antigen among various kinds of antigens by partitioning with a two-phase system using PEG-avidin.

Functional CD4+ T cell subsets defined by expression of CD45RC and NTA260 antigens and age-associated polarization in murine lupus

Using two mAb, one specific to the alternative exon 6-dependent epitope of CD45 molecules (JH6.2) and one a natural thymocytotoxic autoantibody (NTA) with an unknown reactive epitope (NTA260), we subdivided splenic CD4+ T cells from 2-month-old BALB/c mice into five phenotypically distinct subsets. CD45RC+NTA260- (S I) cells were phenotypically analogous to CD4+ T cells predominating in newborn mice and produced a significant amount of IL-2, but not so IL-4, IL-10 or IFN-gamma when stimulated with immobilized anti-CD3 mAb in vitro. They appeared to consist mainly of naive ThP cells. The CD45RC+NTA260+ (S II) subset also produced IL-2, but not other cytokines; however, the IL-2 levels produced were much higher than seen with the S I subset, thereby suggesting the predominance of further maturated ThP cells. The CD45RC-NTA260+ (S III) subset mainly produced IL-4, IL-10, IFN-gamma and less IL-2, and contained memory cells that helped the secondary antibody response to a recall antigen, and hence contained Th2 and probably a mixture of Th0 and Th1 cells. The CD45RC-NTA260- (S IV) subset was a poor responder to the immobilized anti-CD3 mAb. The CD45RCbrightNTA260dull (S V) subset consisted of a small number of cells that were phenotypically analogous to activated CD4+ T cells. While an age-associated decrease in the proportion of S I and less markedly in S II and in turn increase in S III subsets of CD4+ T cells occurred in normal BALB/c mice, autoimmune disease-prone (NZB x NZW)F1 mice showed a marked age-associated decrease in the proportion of not only S I, II but also III subsets. As aged (NZB x NZW)F1 mice carry CD4+ T helper cells for IgG anti-DNA antibody production, such age-associated polarization to the S IV subset appears to be critical in the pathogenesis of autoimmune disease in these mice.

Mapping of a gene for hypergammaglobulinemia to the distal region on chromosome 4 in NZB mice and its contribution to systemic lupus erythematosus in (NZB x NZW)F1 mice

IgM class hypergammaglobulinemia develops spontaneously in the early life of NZB mice. To determine the chromosomal location of the NZB gene(s) linked to this hypergammaglobulinemia and possible contribution to systemic lupus erythematosus (SLE)-like autoimmune disease observed in (NZB x NZW)F1 hybrid mice, we examined (NZB x NZW)F1 x NZW backcross mice, using a mapping technique based on polymorphism in simple nucleotide sequence repeats. In light of our previous data, we directed attention to chromosome 4. A single NZB locus or tightly linked group of loci on the distal region (70-90 cM distal from the centromere), theoretically mapped to 14.3 cM distal from marker locus D4Mit48, had the strongest association with IgM hypergammaglobulinemia. The backcross progeny heterozygous for this locus on chromosome 4, in association with heterozygosity of the MHC haplotype (H-2d from NZB/H-2z from NZW) on chromosome 17, showed significantly higher serum levels of IgG anti-DNA antibodies and more severe lupus nephritis than did the progeny heterozygous for either one of the two loci or homozygous for both loci on chromosomes 4 and 17. The NZB gene in the distal region of chromosome 4 is likely to be responsible for terminal maturation of B cells and, in concert with the effect of H-2 heterozygosity, may predispose to the full expression of SLE in (NZB x NZW)F1 mice.

Primary and higher order structures of nematode (Ascaris suum) mitochondrial tRNAs lacking either the T or D stem

By fractionation using polyacrylamide gel electrophoresis and/or a preparative hybrid selection method employing solid-phase DNA probes, we prepared and characterized mitochondrial tRNAs from the body wall muscle of Ascaris suum, all of which are thought to lack either the T stem or the D stem from their gene sequences (Okimoto, R., and Wolstenholme, D. R. (1990) EMBO J. 10, 3405-3411). Some of the partially purified tRNAs were appreciably aminoacylated with an extract of A. suum mitochondria. The three species sequenced had CCA sequence at their 3'-ends, and tRNA(Met) had 5-formylcytidine at the anticodon first position, a new modified nucleoside found at the same position of bovine mitochondrial tRNA(Met) (Moriya, J., Yokogawa, T., Wakita, K., Ueda, T., Nishikawa, K., Crain, P. F., Hashizume, T., Pomerantz, S. C., McCloskey, J. A., Kawai, G., Hayashi, N., Yokoyama, S., and Watanabe, K. (1994) Biochemistry 33, 2234-2239). Enzymatic probing of these tRNAs supported the secondary structural model proposed by Okimoto and Wolstenholme in the reference cited above. Chemical probing of tRNA(Phe) demonstrated the existence of tertiary interactions between the (T arm-variable loop)-replacement loop and the D arm. The results suggest that these tertiary interactions enable the bizarre tRNAs of nematode mitochondria to maintain an L-shape-like structure in order to function in the nematode mitochondrial translation system.

Batchwise purification of specific tRNAs by a solid-phase DNA probe

A simple and efficient method for purifying a specific tRNA in a single microcentrifuge tube was developed. Oligodeoxyribonucleotides (about 30 mer) with sequences complementary to the 3' side of target tRNAs were synthesized with an aminohexyl linker at the 5' end, immobilized on a silica gel at a high concentration, and used as a solid-phase probe. A mixture of tRNAs was added to a suspension of the solid-phase probe in 2.4 M tetraethylammonium chloride and incubated for 10-30 min. Only a target tRNA hybridized with the immobilized probe at appropriate temperatures and was eluted out by heating. The solid-phase probe showed a large hybridization capacity (up to 17 A260 units/g dry gel) and specific and quantitative recovery of the target tRNA. The intactness of recovered tRNAs was ascertained by both Donis-Keller sequencing and aminoacylation experiments. These features show the usefulness of the solid-phase probe method as a reliable tool for purifying tRNAs whose gene sequences are known.

A unique murine CD43 epitope Lp-3: distinct distribution from another CD43 epitope S7

In foregoing studies, we found a unique B cell differentiation antigen Lp-3 which is expressed on pre-B and premature B cells in the bone marrow, but is negative on bone marrow mature B cells and peripheral resting B cells. Nonetheless, Lp-3 was clearly positive on the majority of CD5 B(B1) cells. When we examined the biochemical nature and partial amino acid sequences of purified 132-kDa Lp-3 molecules and the nucleotide sequence of the cDNA clones, we found that Lp-3 is an epitope of CD43. Thus, the monoclonal antibody (mAb) Lp-3 may be the first mAb to murine CD43 defined by primary target structure analysis. Comparison of tissue distribution of Lp-3 and S7, an epitope previously suggested to associate with murine CD43, showed that they were similarly distributed on thymocytes, peripheral B and T cells, granulocytes, and platelets. In the bone marrow, while both Lp-3 and S7 were negative on mature B cells, the former was positive on all B lineage cells at an early ontogeny and the latter was positive only on the minor population of pre-B cells and pro-B cells. Lp-3 and S7 epitopes also showed different distributions on basement membranes of renal glomerulus, bronchus, and endometrium, lining cells of choroid plexus and muscular cells of arterioles in a variety of tissues. As CD43 has various isoforms generated by different degrees of glycosylation of the common core peptide, it is likely that Lp-3 and S7 are associated with different CD43 isoforms.

Somatic diversification and affinity maturation of IgM and IgG anti-DNA antibodies in murine lupus

Molecular events occurring during the process of generation of pathogenic immunoglobulin (Ig)G anti-DNA antibodies in systemic lupus erythematosus (SLE) were studied using a newly established method. We analyzed the Ig variable (V) region gene sequence and DNA-binding activity of IgM and IgG anti-DNA monoclonal antibodies (mAb) from individual SLE-prone (NZB x NZW) F1 mice. The first event appeared to be clonal selection and expansion of IgM anti-DNA clones, in which several clones had intraclonal V gene mutations. Although the number of mutations was small, the mutated IgM clones were associated with an increase in DNA-binding activity. The somatic mutations located in complementarity-determining regions (CDR) and in framework regions (FR) of V genes were apparently related to changes in DNA-binding activity. IgG anti-DNA clones that progressively increased in number with aging had numerous somatic mutations in the V region genes and there was a pair of clones which showed an intraclonal accumulation of mutations, in association with increase in the DNA-binding activity. All these findings show that somatic mutations associated with affinity maturation of the V region begin immediately before isotype-switching from IgM to IgG of the clones that have been selected and expanded, in an antigen-driven manner and/or by other forces. We propose that further accumulations of intraclonal somatic hypermutation, in association with selection and expansion of high affinity IgG clones, may lead to formation of highly pathogenic anti-DNA antibodies.

DNA-DNA subtractive cDNA cloning using oligo(dT)30-Latex and PCR: identification of cellular genes which are overexpressed in senescent human diploid fibroblasts

We previously reported an efficient method for subtractive cDNA cloning using oligo(dT)30-Latex and polymerase chain reaction (PCR) (E. Hara et al., Nucleic Acids Res. 19, 7097-7104, 1991). The subtraction was performed by hybridization between mRNA of cell type B and the cDNA made from mRNA of cell type A using an oligo(dT)30 primer covalently linked to Latex particles in an Eppendorf tube. The mRNA common to both types of cells could be removed by a brief centrifugation. In the present paper, the method was improved by using the sense strand DNA instead of mRNA for hybridization to cDNA covalently linked to the particles to minimize mRNA degradation and by optimizing the hybridization condition. The sense strand DNA was made from cDNA-oligo(dT)30-Latex by asymmetric PCR. Using the improved method, a subtractive cDNA library with longer cDNA inserts was successfully constructed with higher probability than the original method.

Induction of E1A-responsive negative factors for transcription of the fibronectin gene in adenovirus E1-transformed rat cells

The level of fibronectin (FN) gene expression is very high in resting rat 3Y1 cells but greatly decreased in adenovirus E1-transformed cells. To study the mechanism of this down-regulation, nuclear factors binding to the 5'-flanking region of the FN gene were analyzed by gel retardation assay and DNase I footprinting. Nuclear factors that were present in the transformed cells but nearly absent in resting 3Y1 cells interacted with multiple sites of the promoter region. Oligonucleotide competition with the FN promoter-chloramphenicol acetyltransferase (CAT) reporter constructs (pFCAT) for these factors in the transformed cells indicated that all of them had a negative effect on FN gene expression. Of them, a factor(s) (G10BP) binding to the G10 stretch from positions -239 to -230 and to two GC boxes consisting of the G10 stretch with one internal C residue insertion from positions -105 to -95 and -54 to -44 had the strongest repressive activity. Introduction of substitutive mutations into these G-rich sequences resulted in the increase in CAT activity of pFCAT in the transformed cells. The recognition sequences of G10BP and Sp1 overlap in two GC boxes. G10BP has stronger affinity for heparin and GC boxes than does Sp1, suggesting that G10BP may repress FN gene transcription by displacing Sp1.

Differential expression of three CD45 alternative structures on murine T cells: exon 6-dependent epitope as a marker for functional heterogeneity of CD4+ T cells

We prepared a novel rat mAb specific for CD45 molecules bearing the epitope coded for by the alternative exon 6 of the murine CD45 gene (CD45RC). Together with available mAbs to alternative exon 4- and 5-dependent epitopes (CD45RA and CD45RB respectively), we found that the three alternative exons show differential expressions on murine lymphocytes. Flow cytometry analysis revealed that although B cells were homogeneously CD45RA+B+C+, the CD4+ T cells clearly included two populations, CD45RA-B+C- and CD45RA-B+C+. The CD8+ T cells were separated into CD45RA-B+C+ and CD45RA+B+C+ populations. Such features of epitope expression on the cell surface correlate well with message levels of corresponding alternative exons. In the CD4+ T cells, messages of alternative exons were associated with either one or two exon forms of the CD45 transcript. In CD8+ T cells, there were transcripts with one, two, or three alternative exons. When stimulated by an immobilized CD3 mAb, the CD45RC+CD4+ T cell subset preferentially secreted IL-2 and CD45RC-CD4+ T cells produced IL-4. Upon stimulation with concanavalin A, CD45RC-CD4+ T cells converted to CD45RC+ cells, and the level of CD45RC expression on the CD45RC+CD4+ T cell subset was up-regulated. These changes were unidirectional and irreversible. Therefore, differential expression of CD45RC probably delineates the functional heterogeneity of murine CD4+ T cells that is associated with the stages of CD4+ T cell maturation or activation.

Effect of the higher-order structure of tRNAs on the stability of hybrids with oligodeoxyribonucleotides: separation of tRNA by an efficient solution hybridization

In the course of developing a method to purify a single tRNA species efficiently, we have examined hybridization efficiencies between some tRNAs and short oligodeoxyribonucleotide probes both by the filter and solution hybridization methods without denaturants. The hybridization efficiencies varied considerably among probes which are complementary to different regions of the tRNAs, although there was little efficiency variation in the probes toward DNA substrates including the same nucleotide sequence. This efficiency variation was shown to be due to tRNA-specific higher-order structures as well as a hypermodified nucleotide in the anticodon loop. Characterization of the tRNA-probe hybrids by both nondenaturing gel electrophoresis and chemical modification showed the existence of two stable hybridizing states as a function of ionic strength. Our results indicate that RNA molecules with a number of intramolecular base pairings are able to form stable hybrids with complementary sequences under nondenaturing conditions. On the basis of these data, an appropriate probe was designed to successfully purify yeast tRNA(Phe) by making a tRNA(Phe)-probe hybrid, which has a longer retention time in hydroxyapatite high performance liquid chromatography than the tRNA(Phe) itself.

Cooperative effect of antisense-Rb and antisense-p53 oligomers on the extension of life span in human diploid fibroblasts, TIG-1

Normal human diploid fibroblasts, TIG-1, which have a replicative life span of about 62 population doublings (PD), tended to senesce after about 50 PD with a gradual decrease in sensitivity to serum. Treatment of TIG-1 cells with the antisense-Rb oligomer, which completely depleted the retinoblastoma susceptibility gene product (RB), extended life span by about 10 PD. Treatment with the antisense-p53 oligomer alone had no effect; however, cotreatment with the antisense-Rb oligomer further potentiated the extension and the increased sensitivity to serum caused by the antisense-Rb oligomer alone, suggesting that p53 and RB function in separate, yet complementary pathways in signal transduction to senescence. The c-fos expression, which is presumed to be regulated negatively by RB, was not stimulated in partially senescent TIG-1 cells by treatment with the antisense-Rb oligomer.

A rapid and efficient cloning method with a solid-phase DNA probe: application for cloning the 5'-flanking region of the gene encoding human fibronectin

A rapid and efficient gene-cloning method was developed using oligodeoxyribonucleotide probes (approx. 30-mer) immobilized by their 5' terminal to the gel (LiChrosphare Si1000; used for high-performance liquid chromatography). The method allowed us to concentrate DNA fragments having a particular base sequence in an eppendorf tube with very high efficiency within 2 h. For example, genomic DNA encoding the human fibronectin gene (fn) was concentrated by this method and cloned into lambda Charon4A vector. Screening of the concentrated genomic DNA library for the 5' region of the human fn gene showed that approx. 30% of 3000 recombinant phages tested were positive clones. Various factors affecting cloning efficiency were investigated.

A hapten-induced conformational change accompanies the cryoprecipitation of an immunoglobulin

By simultaneous spectroscopic measurements (absorbance, light scattering, fluorescence and circular dichroism) the temp-dependent behavior of a cryoglobulin, the mouse monoclonal immunoglobulin G to N-acetyllactosamine, has been observed. The results show that a hapten-induced conformational change in the structure of a cryoglobulin can accompany its intermolecular association. This association of the immunoglobulin increases after hapten saturation of its two antigen-combining sites.