bluuebunny/crossref_metadata_2025 huggingface dataset:
High blood pressure related to carcinogen-induced unscheduled DNA synthesis, DNA carcinogen binding, and chromosomal aberrations in human lymphocytes.
Authors: Pero R W , Bryngelsson C , Mitelman F , Thulin T , Nordén A
Published: May 2006

Unscheduled DNA synthesis (excision-repair) of N-acetoxy-2-acetylaminofluorene (NA-AAF) damage to the DNA of human lymphocytes was determined quantitatively for 92 individuals with diastolic blood pressures ranging from 65 to 120 mm of Hg (8,7 to 16 kPa). Measurements of NA-AAF-induced repair synthesis (incorporation of[3H]thymidine in the presence of 10 mM hydroxyurea) showed linear increase with the blood pressure in the individuals under study. Concurrent determinations for the levels of 3H-labeled 7,12-dimethyl-benz[a]anthracene bound to the DNAs of lymphocytes after 18 hr of culturing have shown that increased amounts of DNA bound carcinogen were linearly proportional to increased NA-AAF-induced repair synthesis values, and therefore were correlated to high blood pressure. The number of NA-AAF-induced chromosomal abberations in lymphocytes increased linearly with the diastolic blood pressures of the individuals. High NA-AAF-induced repair synthesis values also tended to be associated with increased NA-AAF-induced chromosomal damage. Together, these results suggest that individuals with elevated blood pressures have a greater potential for accumulating DNA damage, because of an increased chemical reactivity of lymphocytes to carcinogen exposure, than do individuals with normal blood pressure.
Morphine-like peptides in mammalian brain: isolation, structure elucidation, and interactions with the opiate receptor.
Authors: Simantov R , Snyder S H
Published: May 2006

A substance that competes for opiate receptor binding has been isolated from calf brain and identified as two pentapeptides, H-Tyr-Gly-Gly-Phe-Met-OH (methionine enkephalin) and H-Tyr-Gly-Gly-Phe-Leu-OH (leucine enkephalin), with about four times more leucine enkephalin than methionine enkephalin. Sodium and manganese effects on opiate receptor interactions show that both peptides are agonists, whereas leucine enkephalin may be a "purer" agonist than methionine enkephalin.
Calcium-dependent regulatory protein of cyclic nucleotide metabolism in normal and transformed chicken embryo fibroblasts.
Authors: Watterson D M , Van Eldik L J , Smith R E , Vanaman T C
Published: May 2006

The concentration of a calcium-binding protein modulator of 3':5'-cyclic-nucleotide phosphodiesterase (EC 3.1.4.17; 3':5'-cyclic-nucleotide 5'-nucleotidohydrolase) activity is increased in chicken embryo fibroblasts upon transformation by Rous sarcoma virus. This modulator protein from fibroblasts, which has roughly the same molecular size, charge, and functional properties as that isolated from chicken brain, comprises approximately 1.32% of the soluble protein in homogenates of fibroblasts infected and transformed by Rous sarcoma virus. In comparison, the modulator comprises approximately 0.30% of the soluble protein in homogenates of normal fibroblasts from confluent cultures and 0.36% of the soluble protein in homogenates of fibroblasts infected with a transformation-defective mutant of Rous sarcoma virus. Modulator levels in normal fibroblasts at subconfluent cell densities are 0.42-0.76% of the homogenate soluble protein, i.e., between that found in confluent normal fibroblasts and in fibroblasts transformed by Rous sarcoma virus. These observations suggest that the levels of the modulator protein are elevated under conditions in which chicken embryo fibroblasts are undergoing rapid growth and have decreased adenosine 3':5'-cyclic monophosphate levels.
Purine metabolism in adenosine deaminase deficiency.
Authors: Mills G C , Schmalstieg F C , Trimmer K B , Goldman A S , Goldblum R M
Published: May 2006

Purine and pyrimidine metabolites were measured in erythrocytes, plasma, and urine of a 5-month-old infant with adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) deficiency. Adenosine and adenine were measured using newly devised ion exchange separation techniques and a sensitive fluorescence assay. Plasma adenosine levels were increased, whereas adenosine was normal in erythrocytes and not detectable in urine. Increased amounts of adenine were found in erythrocytes and urine as well as in the plasma. Erythrocyte adenosine 5'-monophosphate and adenosine diphosphate concentrations were normal, but adenosine triphosphate content was greatly elevated. Because of the possibility of pyrimidine starvation, pyrimidine nucleotides (pyrimidine coenzymes) in erythrocytes and orotic acid in urine were measured. Pyrimidine nucleotide concentrations were normal, while orotic acid was not detected. These studies suggest that the immune deficiency associated with adenosine deaminase deficiency may be related to increased amounts of adenine, adenosine, or adenine nucleotides.
Evoked neurotransmitter release: statistical effects of nonuniformity and nonstationarity.
Authors: Brown T H , Perkel D H , Feldman M W
Published: May 2006

Recent studies of the mechanism of quantal neurotransmitter release have assumed that the number of quanta released at each stimulation is binomially distributed and have sought to estimate the binomial parameters n and p. Mathematical analysis and computer simulations show that temporal variation in the number of eligible or filled release sites and either spatial or temporal variation in the probability of release at a site can drastically bias such estimates, while the experimental histograms remain statistically indistinguishable from those predicted by the binomial law. Interpretation of the estimates n and p in terms of ultrastructural or physiological characteristics of the nerve terminal is liable to significant error if departures from the binomial assumptions are not suitably assessed.
A fetal protein in chromatin of Novikoff hepatoma and Walker 256 carcinosarcoma tumors that is absent from normal and regenerating rat liver.
Authors: Yeoman L C , Jordan J J , Busch R K , Taylor C W , Savage H E , Busch H
Published: May 2006

Antibodies to chromatin proteins of Novikoff hepatoma cells formed precipitin bands in the double-diffusion immunoprecipitation assay with chromatin proteins of Novikoff hepatoma, Walker 256 carcinosarcoma, and 18-day fetal rat liver. The antigen used for preparation of antiserum was the chromatin proteins initially extracted with 3 M NaCl-7 M urea and soluble after dialysis to 0.14 M NaCl-0.35 M urea. The chromatin proteins used for analytical studies were extracted with 0.6 M NaCl containing 0.01 M Tris-HCl (pH 8) and 100 muM phenylmethylsulfonyl fluoride. Corresponding chromatin proteins of normal and 18-hr regenerating rat liver, heart, and kidney did not form precipitin bands. The antigen was purified from the chrmatin of Novikoff hepatoma cells by exclusion chromatography on Sephadex G-150 and preparative nondenaturing polyacrylamide gel electrophoresis. Its migration on denaturing sodium dodecyl sulfate-polyacrylamide gels corresponded to a molecular weight of 26,000. Amino acid analysis showed that the ratio of acidic to basic amino acids was 1.4 to 1.0. Evidence for its homogeneity included its migration as a single protein spot on two-dimensional polyacrylamide gel electrophoresis and its single lysine amino-terminal amino acid. This protein is a glycoprotein, as shown by the presence of 15 moles of galactosamine per mole of antigen. These studies demonstrate the presence of a fetal glycoprotein in the chromatin of two tumors that may have an important role in determining their gene products.
Activation of histone gene transcription by nonhistone chromosomal proteins in WI-38 human diploid fibroblasts.
Authors: Jansing R L , Stein J L , Stein G S
Published: May 2006

The regulation of histone gene expression was examined after confluent, nondividing WI-38 human diploid fibroblasts were stimulated to proliferate. Histone mRNA sequences were assayed by hybrid formation with an 3H-labeled single-stranded DNA complementary to histone mRNAs. Histone mRNA became associated with polyribosomes concomitant with the activation of DNA synthesis. The ability of chromatin from WI-38 cells to serve as a template for in vitro transcription of histone mRNA sequences parallels the onset of DNA replication. A role for nonhistone chromosomal proteins in the control of histone gene readout is suggested because, when chromatin from confluent WI-38 cells was dissociated and then reconstituted in the presence of S phase nonhistone chromosomal proteins, a 500-fold activation of histone mRNA sequence transcription was observed.
Mechanism of a case of genetic coadaptation in populations of Drosophila melanogaster.
Authors: Hartl D L
Published: May 2006

A cryptic polymorphism found in natrual populations of Drosophila melanogaster has been examined in an artificial population maintained for over 200 generations. The polymorphism is selected because it is insensitive to the segregation distorter phenomenon, and it thereby largely preserves the Mendelian rules of segregation. Segregation distorter chromosomes and the cryptic polymorphism form part of a coadapted complex which is associated with linkage disequilibrium in natrual populations.
Development of tumor cell resistance to syngeneic cell-mediated cytotoxicity during growth of ascitic mastocytoma P815Y.
Authors: Biddison W E , Palmer J C
Published: May 2006

The immune reactivity to tumor cells within a progressively growing tumor mass in the syngeneic host has been analyzed by studying the cell-mediated cytolytic response of DBA/2 mice to the ascitic mastocytoma P815Y. Peritoneal cells from P815Y tumor-bearing hosts were fractionated by velocity sedimentation at unit gravity. Cell-mediated cytotoxicity of fractionated and unfractionated cells was measured by 51Cr-release from tumor target cells. The cell separation procedure revealed significant levels of specific cell-mediated cytotoxicity to P815Y within peritoneal cell populations at 8-16 days after tumor cell inoculation. Tumor cells purified from the peritoneal cell populations of mice injected with 10(3) tumor cells 10 days previously were as susceptible to syngeneic and allogeneic cell-mediated cytotoxicity as P815Y grown in vitro. However, tumor cells obtained from mice 16 days after tumor inoculation were resistant to cytolysis by syngeneic, but not allogeneic, effector cells. In addition, day 16 tumor cells did not inhibit syngeneic cell-mediated cytotoxicity against P815Y grown in vitro. Immunoglobulin was not detected on day 16 tumor cells and no circulating antibody to P815Y was found in the ascitic fluid of day 16 tumor-bearing mice. These results indicate that tumor cells may escape immune attack by loss of expression of cell surface tumor-associated antigens in the absence of circulating antibody against tumor.
Isolation and characterization of muscle membranes using surface-specific labels.
Authors: Barchi R L , Bonilla E , Wong M
Published: May 2006

Membranes were purified from rat muscle by a differential centrifugation method that avoids the use of salt extraction or incubations at elevated temperature. Three populations of membrane-limited vesicles were defined having average densities of 1.112 (fraction I), 1.141 (fraction II), and 1.158 (fraction III) g/ml in a continuous sucrose gradient. Lactoperoxidase-catalyzed iodination of intact muscle prior to isolation of membranes resulted in highest specific activity in fraction I, although all fractions could be equally labeled after isolation. 125I-Labeled wheat germ agglutinin incubated at low concentration with intact muscle preferentially labeled fraction I. Parallel studies on previously isolated fractions indicated that fraction I also contained the highest concentration of potential receptors for wheat germ agglutinin. In experiments on whole muscle, concanavalin A bound predominantly to sarcolemma with slight variable binding to T-tubular and nuclear membrane but no binding to sarcoplasmic reticulum or mitochondria. Parallel binding studies with isolated membrane fragments indicated heavy binding of concanavalin A by membranes in fraction I with scattered binding in fractions II and III. Na+K+Mg2+ ATPase was specifically enriched in fraction I but was also present in fraction II in a proportion similar to 125I labeling. Ca2+ ATPase was most active in fraction II but present in significant levels in fraction I. It is concluded from these and other data that fraction I contains predominantly sarcolemma membrane, while T-tubular membrane may represent a significant component of fraction II. Ca2+ ATPase activity in fraction I is intrinsic to the sarcolemma.
Development of the nervous system of Aplysia californica.
Authors: Kriegstein A R
Published: May 2006

The ability to grow the marine molluse Aplysia under laboratory conditions allows a detailed study of the formation of the nervous system and of the development of specific identified cells. I have found that the ganglia develop in a specific temporal order. Cerebral and pedal ganglia develop at hatching, the abdominal, pleural, and osphradial ganglia 3 weeks after hatching, and the buccal ganglia at 4 weeks. The origin of the abdominal ganglion is complex; its anlage forms at 3 weeks from three larval ganglia that fuse to form the abdominal ganglion. Individual cells cannot be distinguished from one another by their location within the ganglion or by their appearance alone until metamorphosis at 5 weeks. After metamorphosis, the identified neuron, R2, suddenly becomes recognizable because of a significant increase in its size.
Measures of fitness and demographic stability.
Authors: Demetrius L
Published: May 2006

The concepts of entropy and reproductive potential of a genotype were introduced in a previous paper [Demetrius, L. (1974) Proc. Natl. Acad. Sci. USA 71, 4645-4647] and an analoge of the fundamental theorem of natural selection was derived. This paper relates to entropy of a population with the rate of convergence of the population to the stable age distribution. I show that (i) at maximal entropy, no oscillatory components exist and the birth sequence is unaffected by perturbations in the stable age distribution; and (ii) at zero entropy, oscillatory components occur and increase as rapidly as the real exponential component in the birth sequence. These results have implications towards (i) the relation between population fitness and adaptedness, (ii) modes of selection and the evolution of reproductive strategies, and (iii) the evolution of senescence.
Enzymatic synthesis of oligonucleotides of defined sequence: synthesis of a segment of yeast iso-1-cytochrome c gene.
Authors: Gillam S , Rottman F , Jahnke P , Smith M
Published: May 2006

The deoxyribooligonucleotide, d(pT-T-A-G-C-A-G-A-A-C-C-G-G), constituting a segment of yeast iso-1-cytochrome c gene, has been synthesized by a combination of chemical and primarily enzymatic methods. The starting primer, d(pT-T-A-G1, was chemically synthesized by the phosphodiester method and was extended stepwise, by reactions catalyzed by polynucleotide phosphorylase.
Electrophilic mercuration and thallation of benzene and substituted benzenes in trifluoroacetic acid solution
Authors: Olah George A. , Hashimoto Iwao , Lin Henry C.
Published: May 2006

The mercuration and thallation of benzene and substituted benzenes was studied with mercuric and thallic trifluoroacetate, respectively, in trifluoroacetic acid. With the shortest reaction time (1 sec) at 0°, the relative rate of mercuration of toluene compared to that of benzene was 17.5, with the isomer distribution in toluene of:
ortho
, 17.4%;
meta
, 5.9%; and
para
, 76.7%. The isomer distribution in toluene varied with the reaction time, significantly more at 25° than at 0°. The competitive thallation of benzene and toluene with thallic trifluoroacetate in trifluoroacetic acid at 15° showed the relative rate, toluene/benzene, to be 33, with the isomer distribution in toluene of:
ortho
, 9.5%;
meta
, 5.5%; and
para
, 85.0%. With increasingly higher reaction temperatures in both mercuration and thallation reactions of aromatics, isomerization (both intramolecular and intermolecular) within the relevant
ortho
- and
para
-metallated intermediate ions and/or of the isomers becomes more important. Competitive rates and isomer distributions of mercuration and thallation of benzene and substituted benzenes were also determined. The predominant
para
substitution in both mercuration and thallation of methylbenzenes reflects, besides some steric factors, the strong stabilizing effect of
para
methyl groups on the arenium ion intermediates. Under predominantly kinetically controlled conditions, no anomalous increase in the amount of
meta
substitution was observed.
Elimination of size and charge heterogeneities of human leukocyte interferons by chemical cleavage
Authors: Stewart II William E. , Lin Leo S. , Wiranowska-Stewart Marzenna , Cantell Kari
Published: May 2006

Human leukocyte interferon (HuLeIF) preparations contain distinct molecular forms of interferon exhibiting significant heterogeneties in sizes when analyzed by electrophoresis in sodium dodecyl sulfate (NaDodSO
4
)/polyacrylamide gels, migrating in two broad bands of activity with peaks at about 21,000 and 15,000 daltons. HuLeIFs exhibit extensive charge heterogeneities when analyzed by isoelectric focusing, resolving into several major peaks of approximately equal activity distributed from pH 5.7 to 7.0. When HuLeIF preparations are treated with 0.01 M sodium periodate buffer, pH 4.5, at 4°, both the size and charge heterogeneities rapidly disappear: periodate-treated HuLeIF migrates as a single, narrow band at 15,000 daltons in NaDodSO
4
/polyacrylamide gels and focuses as a single, narrow band at pH 5.7. Quantitative considerations suggest that either the larger, heterogeneously charged HuLeIFs are converted to the smaller, size- and charge-homogeneous interferon by extensive chemical deglycosylation, or, alternatively, the smaller, 15,000 dalton, pH 5.7 interferon is much more stable to periodate treatment than are the other interferon forms. However, the activity of each of the variously charged forms of HuLeIF isolated from focusing gels exhibited the same stability as the pH 5.7 component; similarly, the activity of each of the size-forms of HuLeIF isolated from NaDodSO
4
/polyacrylamide gels exhibited the same stability as the 15,000-dalton interferon.
Studies on the mechanism of phosphorylation of synthetic polypeptides by a calf thymus cyclic AMP-dependent protein kinase
Authors: Pomerantz Arthur H. , Allfrey Vincent G. , Merrifield R. B. , Johnson Edward M.
Published: May 2006

Synthetic polypeptides were employed as substrates in kinetic analyses of the reaction mechanism for the catalytic subunit of a cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) from calf thymus. This enzyme preparation was shown to catalyze the transfer of phosphate from ATP to histone H1 from calf thymus, as well as to two synthetic polypeptides, Arg-Lys-Ala-Ser-Gly-Pro (H1-6) and Arg-Arg-Lys-Ala-Ser-Gly-Pro (H1-7), corresponding to the amino acid sequence about serine-38 in calf H1. A related, basic heptapeptide corresponding to a sequence from pig liver pyruvate kinase, Leu-Arg-Arg-Ala-Ser-Leu-Gly (K), was also a substrate. The stoichiometry of peptide phosphorylation was established in each case as the transfer of 1 mol of phosphate from the γ position of MgATP to the serine hydroxyl of 1 mol of the peptide. Steady-state, initial-velocity, kinetic parameters were determined for each substrate, using various concentrations of ATP. Under the conditions used, all synthetic peptides reacted with greater maximum velocities than whole histone H1. Nevertheless, the

K
m

for H1, 54 μM, was lower than the

K
m

values of the synthetic substrates. The most efficient substrate was peptide K, which had a
V
max
of 50.6 μmol/min per mg of kinase and a

K
m

of 63 μM. In the absence of peptide substrate no ATPase activity was detectable at a sensitivity of 0.05% of the rate of peptide phosphorylation, suggesting that ATP is not cleaved to form an unstable phosphoenzyme complex. The data are consistent with a sequential reaction mechanism involving a ternary complex between enzyme, polypeptide substrate, and ATP.
Cloning specific segments of the mammalian genome: bacteriophage lambda containing mouse globin and surrounding gene sequences.
Authors: Tilghman S M , Tiemeier D C , Polsky F , Edgell M H , Seidman J G , Leder A , Enquist L W , Norman B , Leder P
Published: May 2006

We have developed a general approach to the cloning of specific segments of the mammalian genome that involves a two-step purification of EcoRI fragments of mammalian DNA and their in vitro insertion into a suitably constructed EK2 derivative of bacteriophage lambda. The combination of fragment purification, exclusion of parental-type recombinants, and simple phage screening techniques permits the isolation of virtually any gene segment for which there is an identifying hybridization probe. We illustrate the approach by describing the cloning of an approximately 7000-base-long segment of mouse DNA containing globin and surrounding gene sequences.
Homology between a prolyl hydroxylase subunit and a tissue protein that crossreacts immunologically with the enzyme.
Authors: Chen-Kiang S , Cardinale G J , Udenfriend S
Published: May 2006

A protein, enzymatically inactive but immunologically related to prolyl hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate:oxygen oxidoreductase; EC 1.14.11.2) (cross-reacting protein), has been purified to near homogeneity from skin of newborn rats. The purified protein has a molecular weight of 60,000 on gel filtration and sodium dodecyl sulfate gel electrophoresis, corresponding to that of the smaller of the two dissimilar subunits of the enzyme. The two subunits of prolyl hydroxylase differ markedly from one another in their amino acid compositions, but crossreating protein and the smaller subunit are very similar in composition. On antibody-affinity chromatography both subunits reacted with the antibody developed against the intact enzyme. Neither crossreacting protein nor the 60,000 molecular weight subunit was adsorbed onto concanavalin A, which adsorbed the intact enzyme as well as the larger subunit. It would appear that crossreacting protein is identical to one of the subunits of prolyl hydroxylase or metabolically related to it.
Organic acid and potassium accumulation in guard cells during stomatal opening
Authors: Outlaw William H. , Lowry Oliver H.
Published: May 2006

Leaflets of
Vicia faba
L. with either open or closed stomata were quick-frozen and freeze-dried. Individual guard cell pairs and pure samples of palisade parenchyma, spongy parenchyma, and epidermis lacking guard cells were dissected from the leaflets, weighed, and assayed for organic acids or K
+
.K
+
was measured by a new enzymatic method. In guard cells of open stomata, as compared to closed stomata, K
+
was 2- to 4-fold higher, malic acid 6-fold higher, and citric acid 3-fold higher. Both aspartic and glutamic acids were also higher, but the amounts present were low compared to malic and citric acids. Isocitric acid was significantly higher in one experiment, but not in another. Glyceric acid was not increased. Succinic acid was too low to detect by the method used; but in guard cells of open stomata the concentration must have been less than 2% of that of malic acid. Malic acid was higher in the palisade parenchyma from the leaflet with open stomata. The ion balance shows that malic and citric acids provide much of the counter ion for the K
+
taken up during stomatal opening
Genetics of the connective tissue proteins: Assignment of the gene for human type I procollagen to chromosome 17 by analysis of cell hybrids and microcell hybrids
Authors: Raj Cholappadi V. Sundar , Church Robert L. , Klobutcher Lawrence A. , Ruddle Frank H.
Published: May 2006

Somatic cell hybrids between mouse and human cell lines have been used to identify the specific chromosome that governs the synthesis of type I procollagen. Fourteen hybrid clones and subclones were derived independently from crosses between mouse parents [LM (thymidine kinase-negative) or A9 (hypoxanthine phosphoribosyltransferase-negative)] and human cells (human diploid lung fibroblasts WI-38 or diploid skin fibroblasts GM5, GM17, and GM9). The cultures were labeled with [
3
H]proline in modified Eagle's medium without serum. Radioactive procollagens were purified from the medium by the method of Church
et al.
[(1974)
J. Mol. Biol.
86, 785-799]. DEAE-cellulose chromatography was used to separate collagen and type I and type III procollagen. Human type I procollagen was assayed by double immunodiffusion analysis with type I procollagen antibodies prepared by immunizing rabbits with purified human type I procollagen. These analyses combined with karyology and isozyme analyses of each hybrid line have produced evidence for the assignment of the gene for human type I procollagen to chromosome 17. A human microcell-mouse hybrid cell line containing only human chromosome 17 was positive for human type I procollagen, lending further support to the assignment of the human type I procollagen gene to chromosome 17. Finally, by using a hybrid line containing
only
the long arm of human chromosome 17 translocated onto a mouse chromosome, the type I procollagen gene can be assigned more specifically to the long arm of chromosome 17.
Microviscosity modulation during the cell cycle of neuroblastoma cells.
Authors: de Laat S W , van der Saag P T , Shinitzky M
Published: May 2006

Microviscosity (n) of the cell membrane lipid layer was determined in synchronized C1300 mouse neuroblastoma cells (clone Neuro-2A) by fluorescence polarization of 1,6-diphenystratum. The determined n value was maximal in mitosis, decreased markedly in the G1 phase, remained constant at a low level during the S phase, and increased again during the G2 phase. These findings imply a direct role of the cell membrane fluidity in regulation of the cell cycle.
Myosin types during the development of embryonic chicken fast and slow muscles.
Authors: Rubinstein N A , Pepe F A , Holtzer H
Published: May 2006

We have studied the myosin types present in developing fast and slow muscles of the chicken embryo. Myosin light chains were characterized by their mobility on sodium dodecyl sulfate/polyacrylamide gels; myosin heavy chains were identified by their reaction with antibodies specific for adult fast or adult slow myosin heavy chains. During development, the pectoralis muscle, a fast muscle in the adult, contains heavy chains and two of the three light chains characteristic of adult fast muscle myosin. However, the anterior latissimus dorsi muscle, a slow muscle in the adult, also contains fast myosin light and heavy chains during early development. Only after the time of innervation does this muscle begin synthesizing predominantly the slow myosin heavy and light chains. We hypothesize that the synthesis of fast myosin in both early fast and slow muscles is the result of the endogenous program for muscle development; initiation of the synthesis of slow myosin, however, is dependent upon exogenous factors.
Mouse cytolytic T lymphocytes induced by xenogeneic rat stimulator cells exhibit specificity for H-2 complex alloantigens.
Authors: Burakoff S J , Ratnofsky S E , Benacerraf B
Published: May 2006

When mouse spleen cells were stimulated with irradiated xenogeneic, allogeneic, or trinitrophenyl-modified syngeneic lymphoid cells, the strongest cytolytic response was induced by alloantigens. Mouse cytolytic T lymphocytes generated to rat lymphoid cells demonstrated specificity for the immunizing rat strain, but extensive lysis of allogeneic target cells from certain mouse strains was also observed. Cold target inhibition studies indicated that separate clones of xenoantigen-induced cytolytic T lymphocytes lysed each of the allogeneic murine targets. [3H]Thymidine suicide of the effector cells generated to the rat stimulators revealed that only some of all potentially reactive mouse cytolytic T lymphocyte precursors with specificity for a given allogeneic target are activated by the stimulation with rat cells. This evidence that xenoantigens induce alloreactive cytolytic T lymphocyte receptor repertoire is directed at variants of autologous major histocompatibility complex antigens.
Detection of antibody to autologous human leukemia cells by immune adherence assays.
Authors: Garrett T J , Takahashi T , Clarkson B D , Old L J
Published: May 2006

The sera of 21 adult patients with acute leukemia were studied for the presence of antibody reacting with surface antigens of autologous leukemia cells. Sequential serum samples were obtained from patients and were tested on cryopreserved leukemia cells in immune adherence assays. Three patients showed autologous serum reactivity and the serum of one of them was analyzed in detail. This antibody reacted with autologous acute lymphocytic leukemia cells but not with autologous cells obtained from peripheral blood, bone marrow, or spleen during clinical remission. In absorption tests, the antigen could not be detected on normal autologous or allogeneic blood lymphocytes, lymphoblastoid lines of T- or B-cell origin, or cells infected with simian sarcoma virus, baboon C-type virus, or Mason-Pfizer virus. Leukemia cells from two other patients with acute lymphocytic leukemia and one patient with acute nonlymphocytic leukemia absorbed specific reactivity. These studies indicate that certain acute leukemia cells express a common antigen that elicits a humoral immune response in the autologous host.
A Waldenström macroglobulin that is both a cold agglutinin and a cryoglobulin because it binds
N
-acetylneuraminosyl residues
Authors: Tsai Chao-Ming , Zopf David A. , Yu Robert K. , Wistar Richard , Ginsburg Victor
Published: May 2006

A purified human monoclonal IgM(κ) (cold agglutinin MKV) has been characterized as both a cold agglutinin and a cryoglobulin. Since its reactivity with human erythrocytes but not with dog erythrocytes is reduced by treatment of the cells with ficin and its reactivity with both is abolished by treatment of the cells with neuraminidase, it has by definition Pr
2
specificity [Roelcke, D. (1974)
Clin. Immunol. Immunopath
. 2, 266-280]. Presumably, the membrane receptors for cold agglutinin MKV are sialic acid-containing glycoproteins in human cells and sialic acid-containing glycolipids in dog cells. Agglutination of erythrocytes is specifically inhibited by II
3
-
N
-acetylneuraminosyllactosylceramide (GM
3
) and
N
-acetylneuraminosylparagloboside but not by their
N
-glycolylneuraminosyl forms or by lactosylceramide or paragloboside, and the reactivity of neuraminidase-treated cells can be restored by allowing them to absorb either GM
3
or
N
-acetylneuraminosylparagloboside. When large amounts of ganglioside are absorbed, the cells are agglutinated not only in the cold, but also at 37°, showing that the density of receptor sites on the erythrocyte surface can influence the thermal amplitude of cold agglutinins. Liberation of sialic acid from cold agglutinin MKV by treatment with neuraminidase (acylneuraminosyl hydrolase; EC 3.2.1.18) does not affect its agglutinating properties but the asialoprotein is no longer a cryoglobulin. Apparently the physical basis for its precipitation in the cold is the intermolecular immune binding of
N
-acetylneuraminosyl residues.
Activation of cytotoxic T cells by nonstimulating tumor cells and spleen cell factor(s).
Authors: Talmage D W , Woolnough J A , Hemmingsen H , Lopez L , Lafferty K J
Published: May 2006

The ability of three cultured mouse tumor lines to stimulate a cytotoxic response in 5-day cultures of allogeneic lymph node cells was studied with a 51Cr release assay. Two lines of mesenchymal origin, P815 and EL-4, were found to be highly stimulatory, whereas the third cell line, CaD2, a mammary gland epithelial tumor, did not stimulate over a wide range of cell concentration. CaD2 cells were shown to contain major antigens similar to those of P815 cells by the specific lysis of both cells by lymphocytes activated to H-2d-bearing peritoneal cells.UV-irradiated P815-cells, like gamma-irradiated CaD2 cells, did not stimulate a cytotoxic response, but both cell lines were found to stimulate a full and specific response to allogeneic lymph node cells if these mixed cultures were supplemented with a supernatant harvested from concanavalin A-stimulated spleen cells.
Biogenic amine-ionophore interactions: Structure and dynamics of lasalocid (X537A) complexes with phenethylamines and catecholamines in nonpolar solution
Authors: Shen Cynthia , Patel Dinshaw J.
Published: May 2006

The ionophore lasalocid A forms 1:1 complexes with phenethylamines (1-amino-1-phenylethane and 1-amino-2-phenylethane) and catecholamines (dopamine and norepinephrine) in nonpolar solution. We have undertaken high-resolution proton nuclear magnetic resonance studies to deduce structural and kinetic information on the ionophore-biogenic amine complexes in chloroform solution. The coupling constant, chemical shift, and relaxation time data demonstrate that the lasalocid backbone conformation and the primary amine binding sites in the complexes are similar to those determined earlier for the alkali and alkaline earth complexes of this ionophore in solution. The exchange of lasalocid between the free acid (HX) and the primary amine complexes (RNH
3
X) in chloroform solution have been evaluated from the temperature-dependent line shapes at superconducting fields. The kinetic parameters associated with the unimolecular dissociation [Formula: see text] and the bimolecular exchange [Formula: see text] reactions have been deduced from an analysis of the lifetime of the complex as a function of the reactant concentrations. The relative stability of the complex decreases in the order phenyl >
n
-pentyl for substituents on the carbon α to the amino group (1-amino-1-phenylethane and 2-aminoheptane) and phenyl > 3,4-dihydroxyphenyl for substituents on the carbon β to the amino group (1-amino-2-phenylethane and dopamine). These results suggest that nonpolar interactions between the biogenic amine side chain and the lasalocid molecule contribute to the stability of the complex in solution.
Significant structure theory applied to liquid helium-3
Authors: Oh Youngie , Jhon Mu Shik , Eyring Henry
Published: May 2006

The significant structure theory of liquids is successfully applied to the quantum liquid
3
He. The partition function uses the Debye partition function for the solid-like molecules and the Fermi-Dirac partition function for the gas-like degrees of freedom. To evaluate the gas-like partition function, numerical calculations are performed and some integral functions appearing in the equation of state of the ideal Fermi-Dirac gas are tabulated. In the solid-like molecules, the molar volume

V
s

depends on the temperature, and a linear dependence is used.

The thermodynamic properties, such as molar volume, vapor pressure, entropy, heat capacity, and the critical constants as well as the surface tension of liquid
3
He are calculated. The agreement between theory and experiment is satisfactory.
Immunologic selection against simian virus-40 transformed cells: Concomitant loss of viral antigens and early viral gene sequences
Authors: Kuster Jürgen M. , Mora Peter T. , Brown Myles , Khoury George
Published: May 2006

A clonal line of highly oncogenic “spontaneously transformed” mouse cells (T AL/N clone 3) was transformed in tissue culture by simian virus 40 (SV40) and subsequently recloned. The clone of SV40-transformed cells (subclone 1) expressed SV40-specific T (nuclear) and transplantation antigens but was 100 times less tumorigenic than the parent T AL/N clone 3 cells. When large numbers of subclone 1 cells (10
4
-10
5
) were injected into syngeneic AL/N mice, tumors were produced. From the tumors, cell lines were established in culture, all of which were consistently negative for T antigen. Tumor lines tested were found not to contain SV40-specific transplantation antigen and had again become highly tumorigenic. The original subclone 1 cells contained about one copy of SV40 DNA per diploid amount of cell DNA, as well as RNA complementary to the early region of the SV40 genome. The T antigen-negative cells from tumor line 124 contained approximately 0.5 copy of SV40 DNA per diploid equivalent and did not synthesize any detectable virus-specific RNA. Reassociation kinetic analysis with restriction enzyme fragments of viral DNA demonstrated that the cells from tumor line 124 (and also the clones of this line) had lost DNA sequences predominantly from the early region of the SV40 genome. The results indicate that a set of stably integrated SV40 DNA sequences can be present in a cell without the expression of viral antigens.
HeLa cell poly(A)- mRNA codes for a subset of poly(A)+ mRNA-directed proteins with an actin as a major product
Authors: Kaufmann Yael , Milcarek Christine , Berissi Hanna , Penman Sheldon
Published: May 2006

Poly(A)+ and poly(A)- mRNA from HeLa cells were separated and translated in heterologous messenger-dependent protein synthesizing systems. Two-dimensional electrophoretic analysis revealed three classes of polypeptides. At the level of detectability in the electropherograms, a small number (about 10) of proteins were detected only among the poly(A)- mRNA products, a larger number (about 40) were produced by both poly(A)- and poly(A)+ mRNA, and a large number of polypeptides were found exclusively in the poly(A)+ mRNA products. The major product of both poly(A)+ and poly(A)- mRNA was shown to be the β form of actin.

Previous cross hybridization measurements suggested little homology between poly(A)+ and poly(A)- mRNA populations. In view of the apparent identity of many poly(A)- products with those of poly(A)+, the homology between poly(A)+ and poly(A)- mRNA sequences was examined in greater detail. cDNA complementary to only the most abundant poly(A)+ message sequences was prepared. About 10% of this cDNA hybridized to abundant sequences in the poly(A)- fraction. This corresponded to only 2% of the total mass of poly(A)+ mRNA and accounted for the failure to detect cross hybridization in previous experiments. Thus, a small number of poly(A)+ sequences appear to be present in relatively high concentration in poly(A)- mRNA as evidenced by both the translation products and the cross hybridization results.
Ribonuclease III cleavage of bacteriophage T3RNA polymerase transcripts to late T3 mRNAs.
Authors: Majumder H K , Bishayee S , Chakraborty P R , Maitra U
Published: May 2006

In vitro transcription of T3 DNA by T3 phage-induced RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) yields eight discrete RNAs (designated I-VIII) with molecular weights of approximately 6.2, 4.7, 4, 2.8, 1.8, 0.9, 0.52, and 0.21 X 10(6), respectively. Comparison of the size of in vitro T3 RNA polymerase transcripts with in vivo late T3 mRNAs indicates that several late RNAs produced in T3-infected cells do not correspond to any of the in vitro RNAs, and no RNAs as large as the three largest in vitro RNA species, I, II, and III, are observed. Escherichia coli RNase III cleaves these three high molecular weight T3 RNA polymerase transcripts to discrete RNAs that comigrate in polyacrylamide gel electrophoresis with some of the late T3 RNAs.
RNA polymerase binding sites in λp
lac
5 DNA
Authors: Jones Barbara B. , Chan Hardy , Rothstein Steven , Wells Robert D. , Reznikoff William S.
Published: May 2006

The
in vitro
binding of the
Escherichia coli
RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) to fragments of λp
lac
5 DNA generated by restriction endonucleases
Hin
dII and
Hin
dIII has been studied by a filter binding technique. The results are consistent with RNA polymerase binding at
p
R
′, the
INT
promoter (
p
I
), several sites in the
b2
region, the
mis
promoter, the
oop
promoter (or
p
O
), and
p
rm
. Binding was also observed on some fragments that are not known to contain active promoters, including the fragment from the
c
III-
t
L
region. Some of these binding reactions might also be explained by interaction of RNA polymerase with termination sites. Additional polymerase binding sites have been detected by examining which
Hin
dII and
Hin
dIII sites were not cleaved when digestion was performed after RNA polymerase had been bound to the DNA. This technique revealed polymerase binding at
p
L
, at
p
R
, at a site between
R
and
cos
, and at a site at the junction of the γ and
c
III-
t
L
fragments. A comparison of the location of polymerase binding fragments with the partial denaturation map of the λ genome indicates that RNA polymerase binding sites are located within A-T rich regions. It is suggested that RNA polymerase binding is a function both of specific sequences (where recognition occurs) and of the base composition of the surrounding regions (which affects the stability of the helix at the specific site).
Binding of the endogenous nonpeptide morphine-like compound to opiate receptors.
Authors: Blume A J , Shorr J , Finberg J P , Spector S
Published: May 2006

The endogenous central nervous tissue substance called MLC (morphine-like compound) is shown to bind to the opiate receptors of the mouse neuroblastoma X glioma hybrid cell line NG108-15. The interaction of MLC with these opiate receptors is noncooperative, as is the interaction of morphine, naloxone, and Leu-enkephalin with these receptors. A specific antibody to morphine will bind MLC but will not bind beta-endorphin, Leu-enkephalin, or Met-enkephalin. It would appear, therefore, that MLC can be considered to be a different type of endogenous ligand for the opiate receptor.
Isolation of a protein scaffold from mitotic HeLa cell chromosomes
Authors: Adolph K. W. , Cheng S. M. , Paulson J. R. , Laemmli U. K.
Published: May 2006

We have recently shown that, after the histones and most of the nonhistone proteins are gently removed from HeLa metaphase chromosomes, the chromosomal DNA is still highly organized and relatively compact. The structure of these histone-depleted chromosomes is due to the presence of a number of nonhistone proteins that form a central scaffold that retains the approximate size and shape of intact chromosomes and to which the DNA is attached, predominantly forming loops. We now demonstrate that the protein scaffold may be isolated independently of the DNA by treating HeLa chromosomes with micrococcal nuclease before removing the histones.

The chromosomal scaffolds may be isolated by sucrose density gradient centrifugation as a well-defined peak that is stable in 2 M sodium chloride, but is dissociated by treatment with proteases, 4 M urea, or 0.1% sodium dodecyl sulfate. Polyacrylamide gel electrophoresis reveals that the protein content of scaffold preparations is identical to that of histone-depleted chromosomes. Fluorescence microscopy of purified scaffolds in isolation buffer shows that the particles still possess the familiar chromosome morphology. When the scaffolds are examined in the electron microscope, a fibrous structure with the approximate size and shape of intact, paired chromatids is seen. Less than 0.1% of the chromosomal DNA and virtually no histones are associated with the purified scaffold structures.
Noncoincidence of histone and DNA synthesis in cleavage cycles of early development.
Authors: Arceci R J , Gross P R
Published: May 2006

The times of histone and DNA synthesis do not coincide in early cleavage of the sea urchin embryo. In fact, the production of histones increases during the interval after DNA synthesis (G2). Enucleate merogones, parthenogenetically activated, synthesize histones encoded upon maternal histone messenger RNA. The pattern of protein synthesis changes following fertilization, in part, but not solely, due to the increasing synthesis of histones relative to other proteins. Regulation of histone synthesis and the loading of newly replicated DNA with histones must themselves undergo change at the time of transition from cleavage cycles to cycles more typical of somatic cells.
Hemoglobin switching in sheep and goats: induction of hemoglobin C synthesis in cultures of sheep fetal erythroid cells.
Authors: Barker J E , Pierce J E , Kefauver B C , Nienhuis A W
Published: May 2006

Synthesis of HbF (alpha2gamma2) is replaced by synthesis of Hb A (alpha2betaA2) shortly before birth in sheep homozygous for the betaA globin chain whereas Hb C (alpha2betaC2) is produced transiently during the neonatal period. We have obtained a Hb F-to-Hb C switch by generating erythroid colonies at high erythropoietin concentration in plasma clot cultures of mid-gestation fetal bone marrow or liver. Furthermore, high erythropoietin concentration appeared specifically to activate the gene for betaC and not those for betaA or betaB globin in colonies grown from cells of an animal heterozygous for the betaA and betaB genes. Erythropoietic stress in the form of periodic bleeding or erythropoietin injection in utero did not stimulate production of Hb C (alpha2betaC2) in fetal sheep until shortly before birth, and then only in two of six animals. Thus, factors other than erythropoietin may influence the potential for betaC globin synthesis in vivo in fetal sheep.
Moloney leukemia virus-induced cell surface antigen: Detection and characterization in sodium dodecyl sulfate gels
Authors: Troy Frederic A. , Fenyö Eva Maria , Klein George
Published: May 2006

An experimental procedure for detecting and characterizing tumor-associated, virion, and histocompatibility antigens has been developed. The method takes advantage of the high resolution that proteins, solubilized by Triton X-100 and reduced, display after sodium dodecyl sulfate gel electrophoresis. The antigens can be detected as distinct molecular weight species by a highly sensitive inhibition of cytotoxic reaction. When coupled to the lactoperoxidase-catalyzed iodination of intact cells, the procedure permits the determination of externally exposed antigens.

In the present study, the method has been applied to the Moloney leukemia virus-induced YAC lymphoma cells of strain A mice, which express a Moloney leukemia virus-determined cell surface antigen (MCSA) in addition to the type C viral proteins gp71, p30, p15, p15(E), p12, and p10. MCSA was identified as an exposed surface protein distinct in size and antigenic determinants from the major envelope and core protein of Moloney leukemia virus and the histocompatibility antigens. Multiple molecular weight species possessing antigenic determinants for MCSA, gp71, and H-2
a
have been detected. These results provide direct confirmation that MCSA is unrelated to the known virion structural proteins or to the H-2
a
antigen.

This method should permit the direct identification and molecular weight characterization of any antigen whose determinants are not solely dependent on a complex quaternary structure and for which serological reagents are available.
Protein X is the product of the recA gene of Escherichia coli.
Authors: McEntee K
Published: May 2006

The inducible protein X of Escherichia coli has been compared to the recA+ protein made by specialized recA transducing phages. The molecular weights and isoelectric points of these proteins are identical. Two mutations located in the recA gene that alter the electrophoretic mobility or the isoelectric point of protein X have been studied. A recA12 mutant strain, deficient in homologous recombination and repair, produces a smaller-than-normal protein X. A transducing phage carrying the recA12 allele directs the synthesis of a smaller recA protein after infection of irradiated cells. A transducing phage carrying the recA region of a tif-1 mutant strain codes for a recA protein with an isoelectric point more basic than that of the lambdaprecA+ product. The protein X of a tif-1 mutant strain shows an identical shift in its isoelectric properties. Examination of several tsl- recA- strains indicates that protein X can be induced in several missense recA mutants but is not detected in tsl- strains carrying amber or deletion mutations of the recA gene. These results demonstrate that protein X is the product of the recA gene and that the tif-1 mutation alters the properties of the recA protein. A model is suggested for autoregulation of the recA protein in the induction of functions expressed in response to DNA damage (SOS functions).