bluuebunny/crossref_metadata_2025 huggingface dataset:
Animal model for immune dysfunction associated with adenosine deaminase deficiency.
Authors: Tedde A , Balis M E , Ikehara S , Pahwa R , Good R A , Trotta P P
Published: May 2006

An in vivo murine model for immunodeficiency of both B and T cells is produced by continuous intraperitoneal infusion of 2'-deoxycoformycin (DCF), a specific tightly binding inhibitor of adenosine deaminase (ADase; adenosine aminohydrolase, EC 3.5.4.4). After DCF infusion, ADase of thymus, spleen, and lymph nodes was inhibited to varying degrees ranging from 57% to 100%. Immunodeficiency under these conditions was indicated by: (i) a striking decrease in lymphocyte response to the T-cell mitogens concanavalin A and phytohemagglutinin; (ii) an impairment of delayed hypersensitivity measured by the footpad reaction; (iii) a decrease in antibody production measured in both in vivo and in vitro plaque-forming cell assay; (iv) a significant prolongation of mouse skin allograft survival after transplantation into the C57BL/6J (H-2b) strain of skin from BALB/c (H-2d) mice; and (v) a marked lymphopenia. Histological examination indicated lymphoid degeneration in the thymus, lymph nodes, and spleen with no alterations in other tissues including bone marrow, kidney, lung, gastrointestinal tract, and liver except for the occurrence of hepatitis. A decrease in the number of Thy-1-positive cells in both spleen and lymph nodes further supported the fact of cytotoxicity of DCF to T cells. Anorexia and weight loss were observed within 5 days of continuous DCF infusion at 0.4 mg/kg body weight per day. These data indicate that this method provides an experimental model for future studies on the biochemical mechanisms responsible for the genetically determined severe combined immunodeficiency disease in man.
Simple and rapid measurement of human T lymphocytes and their subclasses in peripheral blood.
Authors: Hoffman R A , Kung P C , Hansen W P , Goldstein G
Published: May 2006

A simple and rapid method for the determination of human T lymphocyte subclasses in buffy coat preparations or whole blood is described. This technique uses flow cytometry to distinguish lymphocytes from other leukocytes on the basis of their light-scattering properties. Lymnphocyte subclasses were enumerated by cellular immunofluorescence; the immunofluorescent signals were produced by monoclonal antibodies to surface differentiation antigens on T cells. Conventional techniques of enumerating T lymphocyte subclasses entail time-consuming (up to 2 days) density gradient and E rosette enrichement, and require at least 20 ml of blood. The method described here uses as little as 50 microliters of whole blood for each antibody tested and produces results within in 2 hr.
Improving the anti-tumor activity of 5-fluorouracil by increasing its incorporation into RNA via metabolic modulation.
Authors: Spiegelman S , Sawyer R , Nayak R , Ritzi E , Stolfi R , Martin D
Published: May 2006

The experiments described here illustrate the use of metabolic modulation to improve the therapeutic effectiveness of 5-fluorouracil (5FUra) in two murine tumor systems (CD8F1 mannary carcinoma and CD2F1 colon tumor 26). The manipulations chosen were based on the assumption that a major fraction of the anti-tumor activity of 5FUra is due to its incorporation into RNA and that the resulting 5FUra-RNA creates difficulty for a variety of cellular mechanisms requiring RNA processing and function. This hypothesis leads to the prediction that thymidine would promote the anti-neoplastic effect of 5FUra due to the following possible interactions: (i) sparing 5FUra from catabolic degradation by saturating the relevant enzymes wit thymidine; (ii) selective arrest of normal cells due to feedback inhibition of robonucleotide reductase by the accumulating thymidine triphosphate (TTP); and (iii) the high levels of TTP would also be expected to repress the anabolic conversion of 5FUra to the deoxy derivatives, thus preserving it for entry into RNA. The data show that thymidine (and certain other nucleosides) does in fact markedly stimulate the incorporation of 5FUra into nuclear RNA and that this event is paralleled by a striking icrease in anti-tumor activity. Kinetic analysis reveals that, although the injection of 5FUra leads to an immediate cessation of thymidylate synthetase activity, DNA synthesis continues at a lower rate for 12 hr and then ceases completely. At this point, in contrast to the earlier partial inhibition, the addition of thymidine fails to restore the ability of the tumor cells to synthesize DNA.
Differential amplification of specific areas of phage T4 genome as revealed by hybridization to cloned genetic segments.
Authors: Kozinski A W , Ling S K , Hutchinson N , Halpern M E , Mattson T
Published: May 2006

Under various conditions, specific genetic areas of the phage T4 DNA molecule are preferentially and repeatedly replicated, resulting in the amplification of these areas. These areas are found to lie in the vicinity of the known origins of DNA replication.
Cell cycle regulation of dihydrofolate reductase mRNA metabolism in mouse fibroblasts.
Authors: Hendrickson S L , Wu J S , Johnson L F
Published: May 2006

We have used the technique of DNA-excess filter hybridization to measure directly the content and metabolism of the mRNA for dihydrofolate reductase (DHFR; 5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3). The studies were conducted with a methotrexate-resistant derivative of mouse 3T6 fibroblasts (M50L3) that overproduces the enzyme and its mRNA by a factor of 300 but regulates the level of the enzyme during the cell cycle in the same manner as normal 3T6 cells. We found that, when resting (G0) M50L3 cells were serum-stimulated to reenter the cell cycle, the 10-fold increase in the rate of synthesis of DHFR that occurs at the beginning of S phase was the result of a corresponding increase in DHFR mRNA content. In pulse-labeling experiments, we found that there was a similar increase in the rate of production of the mRNA just prior to S phase. However, the half-life of the mRNA was the same (7.5 hr) in resting and exponentially growing cells. Therefore, the increase in DHFR mRNA content was due to an increase in the rate of production rather than an increase in the stability of the message. The delay between addition of [3H]-uridine to the culture medium and the emergence of DHFR mRNA from the nucleus was 15-20 min for both resting and growing M50L3 cells. A similar delay was observed for total mRNA. Therefore, the time required for the processing of newly synthesized DHFR heterogeneous nuclear RNA into DHFR mRNA is about the same as that for the average mRNA.
Electron paramagnetic resonance spectroscopy of Cu2+ in hen egg-white lysozyme.
Authors: Hutchison C A , Singel D J , Hadad M N , Kemple M D
Published: May 2006

We have obtained the electron paramagnetic resonance spectrum of Cu2+ bound in a tetragonal single crystal of hen egg-white lysozyme. A part of this spectrum has been shown to originate from Cu2+ ions bound at the site designated as B by Teichberg et al. [Teichberg, V.I., Sharon, N., Moult, J., Smilansky, A. & Yonath, A. (1974) J. Mol. Biol. 87, 357-368]. The values of the spin hamiltonian parameters that describe this part of the spectrum are reported. The implications of these values with respect to the chemical nature and configuration of ligands are discussed. The other features of the spectrum are also described.
Monoclonal antibodies against the major glycoprotein (gp350/220) of Epstein-Barr virus neutralize infectivity.
Authors: Thorley-Lawson D A , Geilinger K
Published: May 2006

Hybridomas producing antibodies against Epstein-Barr virus (EBV) have been produced. They have been screened for production of antibodies against the EBV-associated membrane antigens that are present on EBV producer cell lines. For the screening test we used a double-antibody radioimmunoassay with 125I-labeled rabbit anti-mouse Ig as the second step. Positive cultures were cloned and one such clone, C1, was used for further study. C1 antibody neutralizes EBV in vitro and immunoprecipitates both gp350 (the major glycoprotein in B95-8 cells) and gp220 (the major glycoprotein in P3HR-1 cells) from the membrane antigen complex, suggesting that these molecules are antigenically related. The presence of gp350/220 both on the plasma membrane and in the cytoplasm may be detected by immunofluorescence with C1 antibody.
Establishment of the interferon-mediated antiviral state: role of fatty acid cyclooxygenase.
Authors: Pottathil R , Chandrabose K A , Cuatrecasas P , Lang D J
Published: May 2006

Inhibitors of fatty acid cyclooxygenase 8,11,14-icosatrienoate, hydrogen donor:oxygen oxidoreductase, EC 1.14.99.1) were found to suppress the establishment of the interferon-mediated antiviral state. The prevention, by these compounds, of the development of interferon protection correlated with the degree as well as the duration of cyclooxygenase inhibition. Anti-inflammatory substances lacking cyclooxygenase inhibitory activity did not interfere with the establishment of interferon protection. The addition of exogenous prostaglandins was not found to replace the need for a functional cyclooxygenase and, in some instances, could be shown to diminish the establishment of interferon protection. It is proposed that fatty acid cyclooxygenase is an essential component in the optimal induction of the interferon antiviral state.
Molecular abnormality of phosphoglycerate kinase-Uppsala associated with chronic nonspherocytic hemolytic anemia.
Authors: Fujii H , Yoshida A
Published: May 2006

Inherited deficiency of phosphoglycerate kinase (PGK; ATP:3-phosphoglycerate 1-phosphotransferase, EC 2.7.2.3) is associated with chronic nonspherocytic hemolytic anemia and mental disorders in man. One such variant, PGK-Uppsala, was purified to homogeneity. PGK-Uppsala had a lower-than-normal specific activity (30% of normal in the backward reaction and about 20% of normal in the forward reaction) and higher-than-normal Michaelis constants for ATP, ADP, 3-phosphoglycerate and 1,3-diphosphoglycerate. Peptide mapping analysis revealed that the structural abnormality of PGK-Uppsala is a single amino acid substitution from arginine to proline at the 206th position. Based on the known complete amino acid sequence of the normal human PGK and the three-dimensional model deduced from horse PGK, correlations between the structural and functional abnormalities of PGK-Uppsala are discussed. Structural abnormalities of PGK-II, which is an electrophoretic variant not associated with enzyme deficiency, and PGK-München, which is associated with enzyme deficiency and heat instability but not associated with hemolytic anemia, are also discussed.
Biological reactivity of hypochlorous acid: implications for microbicidal mechanisms of leukocyte myeloperoxidase.
Authors: Albrich J M , McCarthy C A , Hurst J K
Published: May 2006

Oxidative degradation of biological substrates by hypochlorous acid has been examined under reaction conditions similar to those found in active phagosomes. Iron sulfur proteins are bleached extremely rapidly, followed in decreasing order by beta-carotene, nucleotides, porphyrins, and heme proteins. Enzymes containing essential cysteine molecules are inactivated with an effectiveness that roughly parallels the nucleophilic reactivities of their sulfhydryl groups. Other compounds, including glucosamines, quinones, riboflavin, and, except for N-chlorination, phospholipids, are unreactive. Rapid irreversible oxidation of cytochromes, adenine nucleotides, and carotene pigments occurs when bacterial cells are exposed to exogenous hypochlorous acid; with Escherichia coli, titrimetric oxidation of cytochrome was found to coincide with loss of aerobic respiration. The occurrence of these cellular reactions implicates hypochlorous acid as a primary microbicide in myeloperoxidase-containing leukocytes; the reactivity patterns observed are consistent with the view that bactericidal action results primarily from loss of energy-linked respiration due to destruction of cellular electron transport chains and the adenine nucleotide pool.
Vascular smooth muscle cells differ from other smooth muscle cells: predominance of vimentin filaments and a specific alpha-type actin.
Authors: Gabbiani G , Schmid E , Winter S , Chaponnier C , de Ckhastonay C , Vandekerckhove J , Weber K , Franke W W
Published: May 2006

Smooth muscle cells of the digestive, respiratory, and urogenital tracts contain desmin as their major, if not exclusive, intermediate-size filament constituent and also show a predominance of gamma-type smooth muscle actin. We have now examined smooth muscle tissue of different blood vessels (e.g., aorta, small arteries, arterioles, venules, and vena cava) from various mammals (man, cow, pig, rabbit, rat) by one- and two-dimensional gel electrophoresis of cell proteins and by immunofluorescence microscopy using antibodies to different intermediate-sized filament proteins. Intermediate-sized filaments of vascular smooth muscle cells contain abundant amounts of vimentin and little, if any, desmin. On gel electrophoresis, vascular smooth muscle vimentin appears as two isoelectric variants of apparent pI values of 5.30 and 5.29, shows the characteristic series of proteolytic fragments, and is one of the major cell proteins. Thus vimentin has been demonstrated in a smooth muscle cell present in the body. Vascular smooth muscle cells are also distinguished by the predominance of a smooth muscle-specific alpha-type actin, whereas gamma-type smooth muscle actin is present only as a minor component. It is proposed that the intermediate filament and actin composition of vascular smooth muscle cells reflects a differentiation pathway separate from that of other smooth muscle cells and may be related to special functions and pathological disorders of blood vessels.
Unique V kappa group associated with two mouse L chain genetic markers.
Authors: Gottlieb P D , Tsang H C , Gibson D M , Cannon L E
Published: May 2006

The C.C58 and C.AKR congeneic strains of mice differ from BALB/c at loci on chromosome 6 which govern kappa light chain variable region (V kappa) polymorphisms and the Lyt-2 and Lyt-3 alloantigens. Amino acid sequence analysis of light chains of myelomas induced in these strains revealed one light chain, C.C58 M75, that had an NH2-terminal serine and differed sufficiently from published V kappa sequences to define a new V kappa group, V kappa (Ser), apparently not expressed by BALB/c mice. Peptide map analysis indicated that the M75 light chain contained the IB-peptide marker, a V kappa polymorphism expressed by C.C58 but not BALB/c mice, which is determined by the IgK-Trpa allele present on chromosome 6. This same light chain was found by isoelectric focussing to correspond to IgK-Ef1a, another V kappa genetic marker of C.C58 and C.AKR. Isoelectric focussing of approximately 200 C.C58 and C.AKR myeloma light chains revealed three additional C.C58 and four C.AKR light chains that corresponded to IgK-Ef1a-specific light chains. All three additional C.C58 light chains belonged to the V kappa (Ser) group and contained the IB-peptide marker. Thus, the differences in V kappa repertoires represented by the IB-peptide and IgK-Ef1a markers and controlled by genes on chromosome 6 appear to reflect expression (or failure of expression) of a distinct group of V kappa regions.
Can nutritional supplements help mentally retarded children? an exploratory study.
Authors: Harrell R F , Capp R H , Davis D R , Peerless J , Ravitz L R
Published: May 2006

To explore the hypothesis that mental retardations are in part genetotrophic diseases (diseases in which the genetic pattern of the afflicted individual requires an augmented supply of one or more nutrients such that when these nutrients are adequately supplied the disease is ameliorated), we carried out a partially double-blind experiment with 16 retarded children (initial IQs, approximately 17-70) of school age who wee given nutritional supplements or placebos during a period of 8 months. The supplement contained 8 minerals in moderate amounts and 11 vitamins, mostly in relatively large amounts. During the first 4- month period (double-blind) the 5 children who received supplements increased their average IQ by 5.0-9.6, depending on the investigator, whereas the 11 subjects given placebos showed negligible change. The difference between these two groups is statistically significant (P less than 0.05). During the second period, the subjects who had been given placebos in the first study received supplements; they showed an average IQ increase of at least 10.2, a highly significant gain (P less than 0.001). Three of the five subjects who were given supplements for both periods showed additional IQ gains during the second 4 months. Three of four children with Down syndrome gained between 10 and 25 units in IQ and also showed physical changes toward normal. Other evidence suggests that the supplement improved visual acuity in two children and increased growth rates. These results support the hypothesis that mental retardations are in part genetotrophic in origin.
Reinitiation of translation from the triplet next to the amber termination codon in the absence of ribosome-releasing factor.
Authors: Ryoji M , Berland R , Kaji A
Published: May 2006

Ribosome releasing factor (RR factor) releases ribosomes from mRNA at the termination codon in Escherichia coli. In the absence of this factor, polypeptides with molecular weights very close to the molecular weight of bacteriophage R17 coat protein were synthesized in vitro under the direction of a mutant R17 phage RNA having an amber mutation at codon 7 of the coat cistron. The major coat-protein-like product shared all the R17 coat protein sequence except that the seven NH2-terminal amino acids were missing. The minor product had the complete coat protein sequence starting from formylmethionine except for a probable amino acid substitution at codon 7 (UAG). Addition of RR factor inhibited the synthesis of the major protein. These results indicate that, in the absence of RR factor, the ribosome that has released the NH2-terminal hexapeptide at the amber codon stays on the mRNA and subsequently reinitiates translation "in phase" immediately after the amber codon without formylmethionine.
Asparagine amide metabolism in developing cotyledons of soybean
Authors: Schaefer Jacob , Skokut T. A. , Stejskal E. O. , McKay R. A. , Varner J. E.
Published: May 2006

Magic-angle single and double cross-polarization
13
C and
15
N NMR spectra have been obtained of lyophilized soybean cotyledons cultured on media containing, as the only nitrogen source, [4-
13
C,
amide
-
15
N]asparagine. Single cross-polarization NMR shows directly and unambiguously that both labels from asparagine are incorporated extensively and nonrandomly into protein by the developing cotyledon during a 2-week period. A stable-isotope double label tags a chemical bond. The metabolic fate of the asparagine double label was followed by double cross-polarization NMR using the latter's sensitivity to the dipolar coupling between directly bonded
13
C and
15
N. These experiments show that in culture the direct incorporation of asparagine (with no scrambling of label) accounts for about half of all asparagine residues in soybean protein. This conclusion implies the operation of a regulatory apparatus in soybeans for both direct utilization and degradation of asparagine in protein synthesis.
Adult chicken alpha-globin genes alpha A and alpha D: no anemic shock alpha-globin exists in domestic chickens.
Authors: Dodgson J B , McCune K C , Rusling D J , Krust A , Engel J D
Published: May 2006

Three alpha-type globin genes have been identified in the alpha-globin linkage group of chickens. No other alpha-type genes hae been directly shown to be within 10 kilobase pairs of any of these three closely linked genes. These three genes have been conclusively identified by DNA sequence analysis. The gene at the 5' end of the linkage group is an embryonic alpha-type globin gene, pi or pi', and the central gene corresponds to the minor adult alpha- globin, alpha D. The 3'-terminal gene sequence corresponds to the sequence of cDNA clones previously described as "alpha S", presumed anemic shock-induced alpha-globin gene [Salser, W. A., Cummings, I., Liu, A., Strommer, J., Padayatty, J. & Clarke, P. (1979) in Cellular and Molecular Regulation of Hemoglobin Switching, eds. Stamatoyannopoulos, G. & Nienheis, A. (Grune and Stratton, New York), pp. 621-643; Richards, R. I. & Wells, J. R. E. (1980) J. Biol. Chem. 255, 9306-9311]. Several groups of workers have isolated alpha S-type cDNA clones but no one has identified a cDNA clone corresponding to the published amino acid sequence of the major chicken alpha-globin, alpha A. We have identified the alpha S-type sequence as the only abundant alpha-like globin sequence in cDNA clones made from reticulocyte mRNA isolated from nonanemic chickens. Therefore, we suggest that the alpha S-type sequence corresponds to the true alpha A-globin species.
Characterization of sites for tyrosine phosphorylation in the transforming protein of Rous sarcoma virus (pp60v-src) and its normal cellular homologue (pp60c-src).
Authors: Smart J E , Oppermann H , Czernilofsky A P , Purchio A F , Erikson R L , Bishop J M
Published: May 2006

The transforming protein of Rous sarcoma virus (pp60v-src) and its normal cellular homologue (pp60c-src) appear to be protein kinases that phosphorylate tyrosine in a variety of protein substrates. In addition, pp60v-src and pp60-c-src are themselves phosphorylated on serine and tyrosine. It is likely that these phosphorylations serve to regulate the function(s) of pp60v-src and pp60c-src. We have therefore characterized the sites of tyrosine phosphorylation in the two proteins. Tyrosine phosphorylation of pp60v-src in infected cells occurs mainly (if not entirely) at residue 419 in the deduced amino acid sequence of the protein. Surrounding this residue is the sequence Leu-Ile-Glu-Asp-Asn-Glu-Tyr(P)-Thr-Ala-Arg. This peptide is distinguished by the fact that three out of the four amino acids that precede the phosphorylated tyrosine are acidic in nature. These results define what may prove to be a widely used site for tyrosine phosphorylation in the regulation of cellular function. The same site was phosphorylated when partially purified pp60v-src was used in a phosphotransfer reaction in vitro. The results with pp60c-src were more complex. The site of tyrosine phosphorylation in vitro appeared to be the same as that found in pp60v-src. By contrast, phosphorylation of pp60c-src in vivo apparently occurred at a different, and currently unidentified, tyrosine residue. It is therefore possible that pp60v-src and pp60c-src respond differently to regulatory influences in the intact cell.
Amino acid sequence of the first constant region domain and the hinge region of the delta heavy chain of human IgD.
Authors: Putnam F W , Takahashi N , Tetaert D , Debuire B , Lin L C
Published: May 2006

We have determined the amino acid sequence of the first constant (C) region domain (C delta 1) and the hinge region of the delta heavy chain of human IgD WAH and also the sequence of the adjacent COOH-terminal portion of the variable (V) region, including the JH region. Together with the sequence of the Fc fragment already reported, this establishes the complete amino acid sequence of the C region of the human delta chain and confirms the presence of three C region domains in human IgD. Although the CH1 domains of the five classes of human heavy chains have the expected degree of homology (approximately 30%), the homology of the C delta 1 domains of the human and mouse chains is less than that exhibited by the CH1 domains of other pairs of human and mouse heavy chains. The hinge region of the human delta chain has an unusual structure; the NH2-terminal half has four (or five) GalN oligosaccharides attached, whereas the COOH-terminal half lacks carbohydrate, is dissimilar in sequence, and has a high charge. A computer search verified that the GalN-rich segment has a high degree of identity in sequence with the middle portion of the human C mu 2 domain and that the high-charge segment is related to the same sequence. We propose that the two segments of the human delta hinge have a common evolutionary origin and arose by duplication and independent mutation of a hinge exon derived from the ancestral gene for the C mu 2 domain.
Interactions among clonal subpopulations affect stability of the metastatic phenotype in polyclonal populations of B16 melanoma cells.
Authors: Poste G , Doll J , Fidler I J
Published: May 2006

Analysis of the metastatic properties of clones isolated from mouse B16 melanoma cell lines (B16-F1 and F10) shows extensive cellular heterogeneity and the presence of subpopulations that have widely differing metastatic abilities. This pattern of metastatic heterogeneity is maintained during serial passage in vitro and in vivo. In contrast, even a short serial passage of individual clones isolated from these heterogeneous parent lines results in rapid emergence of variant subclones that have different metastatic properties. If several clones are mixed and cocultivated, this instability is not expressed. These data suggest that, in polyclonal populations, the various clonal subpopulations somehow interact with one another to "stabilize" their relative proportions within the population. Restriction of clonal diversity by selective killing of the majority of clones in a polyclonal population eliminates the stabilizing restraints and stimulates rapid emergence of new subpopulations to create heterogeneous populations containing a new panel of phenotypically diverse subpopulations that then reach stable proportions until the next selection pressure(s) is encountered.
Reactivation of chicken erythrocyte nuclei in heterokaryons results in expression of adult chicken globin genes.
Authors: Linder S , Zuckerman S H , Ringertz N R
Published: May 2006

Activation of chicken globin gene transcription has been demonstrated in chicken erythrocyte--rat L6 myoblast heterokaryons. The globin mRNA is polyadenylylated and is translated into adult chicken alpha A-, alpha D-, and beta-globin polypeptides. No fetal globin mRNA or globin polypeptides were detected. Heterokaryons between chicken erythrocytes and mouse neuroblastoma cells or hamster BHK cells also synthesized adult chicken globins.
A general high-efficiency procedure for production of microcell hybrids.
Authors: Fournier R E
Published: May 2006

The relative efficiency of microcell-mediated chromosome transfer vs. somatic cell hybridization has been determined. The prolonged mitotic arrest generally used to micronucleate donor cells also reduced the fusion efficiency to 1/10th-1/5th of that in whole cell hybridizations. Here we report an alternative micronucleation protocol, involving sequential treatment of the donor cells with Colcemid and cytochalasin B, which yielded micronucleated cells that hybridized with the same efficiency as whole cells. The enucleation, purification, and fusion steps of the microcell procedure have also been refined. By using these modifications the practical yield of microcell hybrid clones can be increased 50- to 100-fold.
Selective loss of antigen-specific Ir gene function in IA mutant B6.C-H-2bm12 is an antigen presenting cell defect.
Authors: Lin C C , Rosenthal A S , Passmore H C , Hansen T H
Published: May 2006

Immune responses to several soluble antigens were compared between B6.C-H-2bm12 mutant and wild-type B6 mice by using a lymph node T-cell proliferation assay. B6.C-H-2bm12 mice failed to respond to beef insulin whereas other IA gene-controlled responses, such as response to poly(L-Tyr, L-Glu)--poly(DL-Ala, L-Lys) and collagen, were indistinguishable between mutant and wild-type mice. The responses to multideterminant antigens such as ovalbumin and purified protein derivative of tuberculin were also found to be comparable in B6.C-H-2bm12 and B6 mice, thus indicating that this mutation resulted in a selective loss of the ability to respond to a certain antigen(s)--e.g., beef insulin. Populations depleted of adherent cells have been used to examine the mechanism by which Ia molecules mediate Ir gene control of antigen recognition. We show that the nonresponsiveness to beef insulin in the mutant mouse is the result of defective antigen presentation. In addition, we find that F1 hybrids between two nonresponders--B6.C-H-2bm12 and B10.A or B10.AKM (IAk) mice--become responders to beef insulin, thus demonstrating gene complementation. These findings taken together with other serologic and biochemical studies in the B6.C-H-2bm12 present convincing genetic evidence for the direct association of the A beta polypeptide chain of the Iab molecules with the expression of immune responsiveness to beef insulin. Study of the B6.C-H-2bm12 mouse should provide new insight into the cellular and molecular mechanisms by which Ir genes determine the nature of the immune response.
Suppression of a "recurrent" idiotype results in profound alterations of the whole B-cell compartment.
Authors: Bernabé R R , Coutinho A , Cazenave P A , Forni L
Published: May 2006

The progeny of BALB/c female mice actively immunized with the trinitrophenyl-binding myeloma protein MOPC460 and producing anti-idiotypic antibodies during pregnancy were compared with mice born of normal mothers for several characteristics of B lymphocytes and their precursors. In all cases, maternal anti-idiotypic immunity resulted in the suppression of the expression of that idiotype by immunocompetent cells in the progeny, as shown by limiting-dilution analysis in single clones of mitogen-reactive IgM-secreting cells. At critical concentrations of circulating maternal antibodies, suppression of the antibody idiotype was found to be accompanied by a large increase in the total number of mature small B lymphocytes. This increase can be accounted for by the selective expansion of B cells bearing nonimmunoglobulin surface structures crossreactive with a MOPC460 idiotope recognized by a monoclonal antibody. In addition, the large majority of newly formed mature B lymphocytes, as well as a large fraction of immunoglobulin-negative cells in the bone marrow of suppressed mice, bear such nonimmunoglobulin MOPC460 crossreactive determinant(s). These results suggest that the suppression of a given "recurrent" idiotype has profound consequences for a large part of the immune system.
alpha-Hydroxylation pathway in the in vitro metabolism of carcinogenic nitrosamines: N-nitrosodimethylamine and N-nitroso-N-methylaniline.
Authors: Kroeger-Koepke M B , Koepke S R , McClusky G A , Magee P N , Michejda C J
Published: May 2006

Evolution of 15N2-labeled molecular nitrogen was used to gauge the extent of alpha-hydroxylation during rat liver homogenate metabolism of doubly 15N-labeled N-nitrosodimethylamine (DMN) and N-nitrosomethylaniline (NMA). These measurements were correlated with the extent of total metabolism as measured by the disappearance of the nitrosamines and by the formation of formaldehyde. The results indicate that approximately 34% of DMN and 19% of NMA were metabolized by the alpha-hydroxylation pathway. Positive controls utilizing doubly 15N-labeled N-nitroso-N-methylurea yielded 96% of labeled nitrogen. These results are in variance with previously published data which claimed that either less than 5% or about 100% of DMN is metabolized by that route in vitro. Formaldehyde formation was shown to be a poor measure of the extent of metabolism. Semicarbazide gave rise to both formaldehyde and nitrogen, which makes it an undesirable component of the in vitro metabolism mixtures, particularly when those two substances are being measured.
Sequence analysis of a cDNA coding for a pancreatic precursor to somatostatin.
Authors: Taylor W L , Collier K J , Deschenes R J , Weith H L , Dixon J E
Published: May 2006

A synthetic oligonucleotide having the sequence d(T-T-C-C-A-G-A-A-G-A-A) deduced from the amino acid sequence Phe-Phe-Trp-Lys of somatostatin-14 was used to prime the synthesis of a cDNA from channel catfish (Ictalurus punctatus) pancreatic poly(A)-RNA. The major product of this reaction was a cDNA fragment of 565 nucleotides. Chemical sequence analysis of the cDNA fragment revealed that it was complementary to a mRNA coding for somatostatin. The 565-nucleotide cDNA hybridizes strongly with a poly(A)-RNA estimated to be 1000 nucleotides in length. An amino acid sequence of the somatostatin precursor was predicted from the nucleotide sequence. Oyama et al. [Oyama, H., Bradshaw, R. A., Bates, O. J. & Permutt, A. (1980) J. Biol. Chem. 255, 2251-2254] have reported the isolation of a somatostatin from the catfish that is 22 residues in length (somatostatin-22). This peptide differs from somatostatin-14 in amino acid sequence. The cDNA sequence obtained by this laboratory codes for somatostatin-14 and predicts another somatostatin gene product from this species. Thus it would appear that there are at least two somatostatin gene products.
RETRACTED: Prolactin induces release of a factor from membranes capable of stimulating β-casein gene transcription in isolated mammary cell nuclei
Authors: Teyssot Bertrand , Houdebine Louis-Marie , Djiane Jean
Published: May 2006

Crude microsomes from lactating rabbit mammary gland were incubated with prolactin. The incubation mixture was centrifuged and the supernatant was incubated with isolated mammary cell nuclei from lactating rabbits treated for 4 days by bromocryptin to antagonize prolactin and to deinduce casein gene transcription. Nuclei were incubated with HgCTP, and the newly synthesized mercurated RNA was isolated on SH-Sepharose columns. The content of β-casein mRNA sequences in the fraction eluted with 2-mercaptoethanol was estimated with a [
3
H]cDNA probe obtained from partially purified β-casein mRNA. The supernatant markedly stimulated β-casein gene transcription but not 28S rRNA transcription. The same effect was obtained with other lactogenic hormones such as human growth hormone and ovine placental lactogen but was not observed with bovine growth hormone, insulin, parathyroid hormone, luteotropic hormone, or epidermal growth factor. Prolactin and human growth hormone were totally inactive when added directly to nuclei. The factor stimulating β-casein gene transcription was also generated by membranes containing prolactin receptors such as those from liver, ovary, adrenals, and brain but not by membranes from heart, lung, and muscle, which do not bind prolactin. The factor stimulated β-casein transcription when added to mammary nuclei from pseudopregnant or bromocryptin-treated lactating rabbits, in which the transcription rate is submaximal, but was ineffective on mammary nuclei prepared from untreated fully lactating rabbits. The factor was unable to induce β-casein gene transcription in nuclei isolated from rabbit liver and reticulocytes. The factor did not stimulate the transcription of globin genes in nuclei isolated from reticulocytes or the transcription of mammary “housekeeping” genes evaluated by a cDNA probe prepared from total mRNA isolated from an unstimulated mammary gland. The transcription of β-casein genes was abolished by adding α-amanitin to the medium in the presence or in the absence of the factor, indicating that the generation of mercurated β-casein mRNA sequences depended upon the transcriptional activity of RNA polymerase II. The addition of the factor to the incubation mixture did not enhance total and α-amanitin-sensitive RNA synthesis. These data suggest that the binding of prolactin to its receptor
in vitro
induces the formation of a second messager, which specifically stimulates the transcription of prolactin-sensitive genes.
Association of microtubules and intermediate filaments in normal fibroblasts and its disruption upon transformation by a temperature-sensitive mutant of Rous sarcoma virus.
Authors: Ball E H , Singer S J
Published: May 2006

By double indirect immunofluorescence, using primary rabbit antibodies to tubulin and guinea pig antibodies to vimentin, we have simultaneously labeled microtubules and intermediate filaments in several types of cultured normal fibroblasts. With well-spread interphase cells there was an extensive but not complete correspondence of the labeling patterns for the two filamentous structures out to the cell periphery. This correspondence existed both at a gross level, where parallel but not coincident arrays of thickly labeled strands of the two types of filaments were observed, and at a fine level, where thinly labeled strands of the two were superimposed. The results suggest that there may be some type(s) of molecular linkages between microtubules and vimentin intermediate filaments that is under metabolic control. With NRK fibroblasts infected with a temperature-sensitive mutant (LA23) of Rous sarcoma virus, cells grown at the nonpermissive temperature (39 degrees C) showed the correspondence of the distributions of the microtubules and intermediate filaments characteristic of the normal phenotype but within 1 hr after a shift to the permissive temperature (33 degrees C) there was an extensive retraction of the intermediate filaments around the cell nucleus whereas the microtubules remained dispersed into the cell periphery. These results suggest that one of the functions carried out by p60src, the protein kinase responsible for transformation by Rous sarcoma virus, may be to modify the component(s) involved in the putative linkages between microtubules and intermediate filaments in the normal cells.
Allelic forms of rat κ chain genes: Evidence for strong selection at the level of nucleotide sequence
Authors: Sheppard H. W. , Gutman G. A.
Published: May 2006

The genes that code for two allotypic forms of the rat κ light chain constant region (C
κ
) have been cloned and the nucleotide sequence of 1172 base pairs of coding and flanking sequence has been determined for both alleles. These sequences have been compared to each other and to the corresponding sequences found in the mouse and human. Comparison of the LEW allele with mouse C
κ
reveals two surprising features: (
i
) There is an unusually large number of amino acid substitutions (21) relative to the total number of nucleotide changes (37) in the coding region. Comparision among several other mammalian genes reveals a larger proportion of “silent” changes. (
ii
) The rate of accumulation of base substitutions is the same within the coding region as it is in some 870 base pairs of noncoding sequence (including 3′ untranslated, 3′ flanking, and 5′ intervening sequences). Comparison of the two allelic forms of rat C
κ
shows the same unusual features in more extreme form. (
i
) Twelve base substitutions in the coding region determine 11 amino acid differences-only one “silent” change exists. (
ii
) There are 12 base substitutions in the 318 base pairs of coding sequence (3.7% difference) and only 9 in the remaining 854 base pairs of noncoding DNA (1.1%), a highly significant difference. This degree of conservation of noncoding sequences and of “silent” sites within the coding region is unique among the mammalian genes studied thus far. These patterns suggest that there has been strong selection for conservation of nucleotide sequences, both inside and outside the coding region, independent of the selection required to maintain the function and characteristic structure of the immunoglobulin domain itself. The functions of the nucleotide sequences that account for this selective pressure are unclear at the present time.
Developmental hierarchy of immunoglobulin gene rearrangements in human leukemic pre-B-cells.
Authors: Korsmeyer S J , Hieter P A , Ravetch J V , Poplack D G , Waldmann T A , Leder P
Published: May 2006

We have used a special class of human acute lymphocytic leukemias, the common "non-T/non-B" cell type, to define a hierarchy of genetic rearrangements that occur during the earliest stages of B-cell maturation. This has allowed us to identify intermediate cells predicted by a hierarchial model in which immunoglobulin heavy chain variable region gene formation precedes that of light chain and in which kappa light chain gene formation precedes that of lambda. The model emphasizes the flexible nature of immunoglobulin gene recombination that not infrequently produces aberrant or null genes that are phenotypically excluded from expression. Remaining alleles or isotypic genes can then be utilized as "spares" undergoing recombination until a valid gene is formed. Significantly, the excluded allele or isotype is frequently deleted from the genome. In addition to defining a pathway of genetic maturation, this analysis provides a powerful means to further classify cases of non-T/non-B-cell acute lymphocytic leukemia, most of which seem to reside at early stages along the B-cell pathway of differentiation.
The aging process.
Authors: Harman D
Published: May 2006

Aging is the progressive accumulation of changes with time that are associated with or responsible for the ever-increasing susceptibility to disease and death which accompanies advancing age. These time-related changes are attributed to the aging process. The nature of the aging process has been the subject of considerable speculation. Accumulating evidence now indicates that the sum of the deleterious free radical reactions going on continuously throughout the cells and tissues constitutes the aging process or is a major contributor to it. In mammalian systems the free radical reactions are largely those involving oxygen. Dietary manipulations expected to lower the rate of production of free radical reaction damage have been shown (i) to increase the life span of mice, rats, fruit flies, nematodes, and rotifers, as well as the "life span" of neurospora; (ii) to inhibit development of some forms of cancer; (iii) to enhance humoral and cell-mediated immune responses; and (iv) to slow development of amyloidosis and the autoimmune disorders of NZB and NZB/NZW mice. In addition, studies strongly suggest that free radical reactions play a significant role in the deterioration of the cardiovascular and central nervous systems with age. The free radical theory of aging provides reasonable explanations for age-associated phenomena, including (i) the relationship of the average life spans of mammalian species to their basal metabolic rates, (ii) the clustering of degenerative diseases in the terminal part of the life span, (iii) the beneficial effect of food restriction on life span, (iv) the greater longevity of females, and (v) the increase in autoimmune manifestations with age. It is not unreasonable to expect on the basis of present data that the healthy life span can be increased by 5-10 or more years by keeping body weight down, at a level compatible with a sense of well-being, while ingesting diets adequate in essential nutrients but designed to minimize random free radical reactions in the body.
Plasma cell dyscrasia and peripheral neuropathy: identification of the myelin antigens that react with human paraproteins.
Authors: Latov N , Braun P E , Gross R B , Sherman W H , Penn A S , Chess L
Published: May 2006

In some cases of polyneuropathy and plasma cell dyscrasia, the monclonal antibodies react with human peripheral nerve myelin. To identify the myelin antigens involved, we separated the proteins of human central and peripheral nerve myelin by polyacrylamide gel electrophoresis, transferred the proteins onto nitrocellulose sheets, and used an immunoenzymatic technique to detect the reactive antigens. Serum IgM but not IgG from three patients with neuropathy and complement-fixing anti-human myelin IgM paraproteins immunostained a protein of approximately 100,000 daltons in human peripheral nerve myelin and a protein or closely migrating proteins of similar size in human central nervous system myelin. In a fourth patient, both IgM and IgG immunostained the antigen. Immunostaining was specific for the paraprotein light chain type, and absorption of the patients' sera with human peripheral nerve myelin eliminated the reaction with the central nervous system proteins. No reaction was seen with rabbit peripheral nerve myelin or with membranes prepared from human myotubes, human T cells, or human fibroblasts. Control sera from six patients with neuropathy and IgM paraproteins that did not react with myelin, from four patients with IgM paraproteins but no neuropathy, and from three normal subjects did not immunostain myelin.
Are the presynaptic membrane particles the calcium channels?
Authors: Pumplin D W , Reese T S , Llinás R
Published: May 2006

The number of large intramembrane particles associated with sites of synaptic vesicle release at the squid giant synapse was determined and compared to the average maximal presynaptic calcium current in order to derive an estimate of the conductance each particle would have if it were a calcium channel. This value, 0.21 pS, compares favorably with conductances of calcium channels in other preparations, substantiating the idea that the large intramembrane particles, which are concentrated at "active zones," represent calcium channels.
A new family of algebras underlying the Rogers-Ramanujan identities and generalizations
Authors: Lepowsky James , Wilson Robert Lee
Published: May 2006

The classical Rogers-Ramanujan identities have been interpreted by Lepowsky-Milne and the present authors in terms of the representation theory of the Euclidean Kac-Moody Lie algebra
A
1
(1)
. Also, the present authors have introduced certain “vertex” differential operators providing a construction of
A
1
(1)
on its basic module, and Kac, Kazhdan, and we have generalized this construction to a general class of Euclidean Lie algebras. Starting from this viewpoint, we now introduce certain new algebras [unk]

v

which centralize the action of the principal Heisenberg subalgebra of an arbitrary Euclidean Lie algebra [unk] on a highest weight [unk]-module
V
. We state a general (tautological) Rogers-Ramanujan-type identity, which by our earlier theorem includes the classical identities, and we show that [unk]

v

can be used to reformulate the general identity. For [unk] =
A
1
(1)
, we develop the representation theory of [unk]

v

in considerable detail, allowing us to prove our earlier conjecture that our general Rogers-Ramanujan-type identity includes certain identities of Gordon, Andrews, and Bressoud. In the process, we construct explicit bases of all of the standard and Verma modules of nonzero level for
A
1
(1)
, with an explicit realization of
A
1
(1)
as operators in each case. The differential operator constructions mentioned above correspond to the trivial case [unk]

v

= (1) of the present theory.
Incorporation into DNA of the base analog 2-aminopurine by the Epstein-Barr virus-induced DNA polymerase in vivo and in vitro.
Authors: Grossberger D , Clough W
Published: May 2006

The Epstein-Barr virus (EBV)-induced intracellular DNA polymerase was assayed in vitro for the ability to utilize the mutagenic nucleotide analog 2-aminopurine deoxyribose triphosphate (d2apTP), incorporating it as the corresponding monophosphate into DNA or poly[d)(A-T)] template. Bacteriophage T4, lymphocyte alpha, and the EBV particle-associated DNA polymerases were assayed simultaneously for direct comparison. Unlike these three polymerases, which were capable of distinguishing between d2apTP and dATP with a strong preference for the latter, the EBV-induced DNA polymerase only weakly distinguished between dATP and d2apTP and incorporated substantial amounts of d2apTP into template. Detergent-treated lymphocyte nuclei undergoing a high level of EBV DNA synthesis were shown to incorporate the 2-aminopurine analog of dATP into viral DNA. The relative inability of the EBV-induced DNA polymerase to distinguish between the two purine nucleotides reported here is consistent with previous reports on the ready incorporation of other nucleotide analogs into DNA polymerases induced by other herpesviruses. Because most antiherpes agents currently in use or under study are nucleotide analogs, the viral mutagenic properties of these drugs should be examined.