bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibody-independent activation of the alternative complement pathway by measles virus-infected cells.
Authors: Sissons J G , Oldstone M B , Schreiber R D
Published: May 2006

When HeLa cells acutely infected with measles virus were incubated in a mixture containing only the six proteins of the alternative pathway of complement activation (C3, factors B and D, beta 1H, C3b inactivator, and native properdin) without antibody, there was activation of the alternative pathway as shown by progressive uptake of 125I-labeled C3b onto the cell surface. This C3b uptake was blocked by EDTA and was not shown by uninfected cells. The rate of 125I-labeled C3 uptake by infected cells was the same in the absence and presence of properdin; however, when antiviral IgG was bound to the cell surface, the rate of C3 uptake was increased in the presence of properdin. Significant 125I-labeled C3 uptake was first detectable when cells were studied at 12 hr after infection, when cells expressed viral polypeptides on their surface. There was also progressive uptake of 125I-labeled C3 onto measles virus-infected cells incubated in human serum depleted of both IgG and C4. Hence, the human alternative pathway of complement activation can be initiated on the surface of measles virus-infected cells independent of IgG antibody. However, lysis of the infected cells only occurs when antiviral antibody is present.
Insulin is ubiquitous in extrapancreatic tissues of rats and humans.
Authors: Rosenzweig J L , Havrankova J , Lesniak M A , Brownstein M , Roth J
Published: May 2006

Insulin has been detected, at levels higher than those in plasma, in a broad range of extrapancreatic tissues in both rats and humans. Rat liver insulin was shown to be indistinguishable from genuine insulin by radioimmunoassay, Sephadex chromatography, bioassay, and antibody neutralization. Liver insulin (like brain insulin) was unchanged in ob/ob mice, in rats treated with streptozotocin, or in fasted rats, despite marked alterations in pancreatic secretion of insulin and in liver content of insulin receptors. Insulin was found in cultured human IM-9 lymphocytes and cultured fibroblasts at concentrations greater than 100 times the levels in the media. IM-9 lymphocyte insulin also was shown to be indistinguishable from genuine insulin, by the same criteria used for liver insulin. The insulin concentration in cultured human cells was unaffected by depletion of insulin from the culture medium or by addition of beef insulin to the medium. The data suggest that a part, if not all, of the extrapancreatic tissue insulin is independent of plasma insulin and may be synthesized by the tissues themselves.
Association of coronary atherosclerosis with hyperapobetalipoproteinemia [increased protein but normal cholesterol levels in human plasma low density (beta) lipoproteins].
Authors: Sniderman A , Shapiro S , Marpole D , Skinner B , Teng B , Kwiterovich P O
Published: May 2006

Most patients with coronary artery disease do not have elevated plasma or low density lipoprotein (LDL) cholesterol. To test whether the protein moiety of LDL, LDL B, might be a parameter to identify ischemic heart disease, the plasma cholesterol, triglyceride, LDL cholesterol, and LDL B were measured in 100 consecutive patients undergoing cardiac catheterization. On the basis of coronary angiography, these patients were divided into two groups: group I, 31 patients without, and group II, 59 patients with significant coronary artery disease. Although cholesterol, triglyceride, and LDL cholesterol levels were all significantly higher in group II, discriminant analysis indicated that LDL B concentrations most clearly separated the two groups. In group I (noncoronary), LDL B was 82 +/- 22 mg/100 ml, whereas in group II, LDL B was 118 +/- 22 mg/100 ml. The B protein level in group I was similar to other normal groups studied (35 asymptomatic male physicians, 83 +/- 11 mg/100 ml; 90 normolipidemic medical students, 72 +/- 17 mg/100 ml). The results therefore indicate that not only does LDL B better separate coronary and noncoronary groups than other lipid parameters studied, but also, among those with coronary artery disease, there exists a group with normal LDL cholesterol but with levels of LDL B protein similar to those observed in type II hyperlipoproteinemia. The explanation for the altered LDL composition observed in this group remains to be elucidated.
Molecular cloning of infectious integrated murine leukemia virus DNA from infected mouse cells.
Authors: Lowy D R , Rands E , Chattopadhyay S K , Garon C F , Hager G L
Published: May 2006

The lack of an endonuclease EcoRI site in the AKR murine leukemia virus (MuLV) DNA genome was utilized to molecularly clone, in Charon 4A lambda DNA, integrated infectious AKR MuLV DNA isolated from productively infected mouse cells. Three lambda-mouse recombinants (clones 614, 621, and 623) were selected by virtue of their reactivity with AKR MuLV [32P]cDNA. Clones 614 and 623 contained the complete AKR MuLV DNA flanked by nonviral cell sequences of which no more than 100 base pairs beyond the viral DNA appear to be shared. DNAs from both clones 614 and 623 were highly infectious for mouse cells and yielded N-tropic ecotropic MuLV; the specific infectivity of the DNA and the titer of the derived virus was more than 10-fold higher with 623. Clone 621 contained only some viral DNA and was not infectious under similar conditions.
Characters of irreducible Harish-Chandra modules and Goldie ranks of their annihilators
Authors: King Donald R.
Published: May 2006

Assume that
G
C
is a simply connected complex semi-simple Lie group with Lie algebra [unk]. Let
G
⊂
G
C
be a real form,
H
⊂
G
be a maximally split Cartan subgroup with Lie algebra [unk]
0
, [unk] = [unk]
0
[unk] C, and
P
⊆ [unk]
*
be the weight lattice. If
X
is an irreducible Harish-Chandra module with infinitesimal character λ ∈ [unk]
*
, one can associate to
X
a family {θ(μ): μ ∈ λ +
P
} of Z-linear combinations of distribution characters of
G
, so that θ(λ) =
X
. θ(μ) is irreducible when μ lies in
C
λ
, a certain positive “Weyl” chamber containing λ. In this case let Ann θ(μ) be its annihilator in
U
([unk]) and set
p
(μ) = Goldie rank of
U
([unk])/ Ann θ(μ). Let
d
= Gelfand-Kirillov dimension of
X
. For most
x
∈ [unk]
0
if exp
tx
is regular for small
t
> 0 then (
i
)
c
(μ) = lim

t
→0
+

t
d

θ(μ) (exp
tx
) exists for all μ ∈ λ +
P
; (
ii
)
c
(μ) extends to a homogeneous Weyl group harmonic polynomial on [unk]
*
of degree ½(dim
G
- dim
H
) -
d
; (
iii
) up to a constant,
c
= the polynomial extending
p
to [unk]
*
.
c
is said to be the character polynomial of Ann
X
.
In vitro synthesis of 1 alpha,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol by isolated calvarial cells.
Authors: Turner R T , Puzas J E , Forte M D , Lester G E , Gray T K , Howard G A , Baylink D J
Published: May 2006

The question of whether the skeleton metabolizes 25-hydroxycholecalciferol [25(OH)D3] to more-polar products was studied. Calvarial cells were dispersed from 16-day old chicken embryos by using collagenase and then grown in culture in serum-free medium. Confluent cell cultures were incubated with 7 nM 25(OH)[3H]D3 for 2 hr, and the vitamin D metabolites were then extracted. At least four polar metabolites were produced. Based on separation by Sephadex LH-20 chromatography followed by high-pressure liquid chromatography, two of these metabolites were identified as 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and 24,25-dihydroxycholecalciferol [24,25(OH)2D3]. These metabolites were also produced by cultured kidney cells but not by liver, heart muscle, or skin cells isolated from the same embryos. The specific activities of the calvarial 1- and 24-hydroxylases were similar in magnitude to those in isolated kidney cells. The specific activity of the calvarial 25(OH)D3:1-hydroxylase was inhibited by an 8-hr preincubation with 1,25(OH)2D3, whereas the 24-hydroxylase was enhanced. It is concluded that (i) vitamin D metabolism by isolated cells is organ-specific, (ii) calvarial cells produce active metabolites of vitamin D in significant amounts, (iii) vitamin D metabolism by calvarial cells is regulated by 1,25(OH)2D3, and (iv) locally produced, active metabolites could act locally, thereby adding a new dimension to the regulation of mineral metabolism by vitamin D metabolites.
Subunit neighbor interactions in enzyme kinetics: half-of-the-sites reactivity in a dimer.
Authors: Hill T L , Levitzki A
Published: May 2006

We consider an isologous enzyme dimer in which the subunits, if operating independently, would obey Michaelis-Menten kinetics. However, because of neighbor interactions, the rate constants of the kinetic cycle in either subunit depend on the state (E or ES) of the other subunit. The steady-state behavior of this dimer system, with interactions, is investigated. In what is probably the most important special case, ES x ES is destabilized considerably by the neighbor interaction compared to E x ES. This leads to half-of-the-sites reactivity (one subunit is in state ES; the other subunit cycles between E and ES), negative cooperativity, and a considerable enhancement of enzyme activity relative to the activity of independent subunits.
Differential efficacies of human type I and type II interferons as antiviral and antiproliferative agents.
Authors: Rubin B Y , Gupta S L
Published: May 2006

Treatment of human fibroblast FS-4 cultures with human type II interferon preparations induced the synthesis of at least four proteins that were similar in size to four of the five proteins induced by type I interferons (Mr 120,000, 88,000, 67,000, and 56,000). However, the Mr 67,000 and 56,000 proteins were induced more strongly by type II than by type I interferon, and a counterpart of a Mr 80,000 protein induced by type I interferons was not noticeably induced by type II interferon preparations. We therefore compared type I and type II interferons for relative antiviral activities against different viruses (vesicular stomatitis, encephalomyocarditis, and vaccinia viruses and reovirus) and for cell growth-inhibitory activities on various cell types. The replication of vesicular stomatitis and encephalomyocarditis viruses was inhibited more strongly by type I interferon, whereas reovirus and vaccinia virus showed greater sensitivity to type II interferon preparations. This indicates that viruses may differ in their sensitivity to human type I and type II interferons and that the antiviral mechanisms induced by type I and type II interferons may have significant differences. The type I and type II interferons may have significant differences. The type I and type II interferons may also differ in their efficacies as antiproliferative agents. Type II interferon preparations at 2.5 units/ml inhibited the incorporatin of [3H]thymidine to a greater extent than did type I interferon at 400 units/ml. (For both type I and type II interferons, the unit of interferon activity was defined as the concentration that decreased the yield of vesicular stomatitis virus by 50% in FS-4 cultures.) Furthermore, whereas type II interferon preparations had a reversible cytostatic effect on normal human fibroblasts at 10 units/ml, the transformed cells tested (HeLa, osteosarcoma, U-amnion) showed extensive cell death, thus indicating that it may have a cytocidal effect on certain tumor cells. It appears that human type II interferon (or a factor present in these preparations) may be a potent antitumor agent.
Amiloride inhibits murine erythroleukemia cell differentiation: evidence for a Ca2+ requirement for commitment.
Authors: Levenson R , Housman D , Cantley L
Published: May 2006

The effect of amiloride (an inhibitor of passive Na+ transport in many tissues) on the differentiation of murine erythroleukemia cells was investigated. Amiloride completely blocked the dimethyl sulfoxide (Me2SO)-induced erythroid differentiation of cells at a concentration (10 microgram/ml) that did not affect cell proliferation. Amiloride also prevented the decrease in cell volume normally observed afte a 20-hr exposure to Me2SO. The ratio of total cell Na+ to total cell water was essentially the same for control cells, Me2SO-treated cells, and cells treated with Me2SO plus amiloride. However, cells treated for 24 hr with Me2SO had a rate of Ca2+ uptake that was twice that of untreated cells and a similarly higher Ca2+ content. Addition of amiloride plus Me2SO prevented both the increase in Ca2+ uptake rate and the increase in Ca2+ content. Cells grown in the presence of Me2SO plus amiloride initiated differentiation immediately after removal of amiloride or addition of the Ca2+ ionophore A23187 (1 microgram/ml). Addition of sufficient ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to reduce free extracellular Ca2+ to submicromolar levels prevented Me2SO-induced differentiation while only slightly affecting cell proliferation. These results suggest that an increase in in the Ca2+ level is an essential step in Me2SO induction, that amiloride either directly or indirectly inhibits this process, and that Me2SO has an early effect on cells that is necessary for differentiation and is not mimicked by A23187.
Rate of spontaneous mutation at human loci encoding protein structure.
Authors: Neel J V , Mohrenweiser H W , Meisler M H
Published: May 2006

The techniques of electrophoresis were used in a search for evidence of mutation affecting protein structure, the indicators being hemoglobin and a set of serum proteins and erythrocyte enzymes. Among 94,796 locus tests on Amerindians from Central and South America, there was no evidence for mutation. Among 105,649 locus tests on newborn infants in Ann Arbor, Michigan, there was also no evidence for mutation. We have previously failed to encounter any mutations in a series of 208,196 locus tests involving Japanese children [Neel, J. V., Satoh, C., Hamilton, H. B., Otake, M., Goriki, K., Kageoka, T., Fugita, M., Neriishi, S & Asakawa,J. (1980) Proc. Natl. Acad. Sci. USA 77, 4221-4225], and H. Harris, D. A. Hopkinson, and E. B. Robson [(1974) Ann. Hum. Genet. 37, 237-253] found no mutations in 113,478 locus tests on inhabitants of the United Kingdom. This failure to demonstrate any mutations of this type in a total of 522,119 locus tests excludes, at the 95% level of probability, a mutation rate greater than 0.6 X 10(-5)/locus per generation in this combination of populations.
Human lysosomes can be purified from diploid skin fibroblasts by free-flow electrophoresis.
Authors: Harms E , Kern H , Schneider J A
Published: May 2006

Human diploid fibroblasts underwent lysis when resuspended in isotonic sucrose. After preparation of a granular fraction by differential centrifugation, lysosomes were almost completely purified by free-flow electrophoresis. Electron micrographs of the final fraction of fibroblast lysosomes (about 25-fold purified) showed mostly secondary lysosomes having an appearance identical to those in intact cells. There was no indication that the purification steps selectd for any lysosomal subpopulation. The lysomal nature of the isolated organelles was confirmed by cytochemical staining for acid beta-glycerophosphatase. As judged by a 92% structure-linked latency of beta-N-acetylglucosaminidase in the final fraction, the structural integrity of the isolated lysosomes was unaffected by the purification procedure.
Facilitation of membrane electrical excitability in Drosophila.
Authors: Salkoff L , Wyman R
Published: May 2006

Prior electrical activity in the indirect flight muscles of Drosophila facilitates membrane excitability. The mechanism of facilitation involves the inactivation of an early, fast, transient outward current by prior membrane depolarizaton. In the facilitated state the calcium-dependent spike-like response has a decreased current and voltage threshold. The facilitated state persists for 1.5 sec after a membrane active response. A single nerve-driven spike is sufficient to facilitate membrane excitability.
Differentiation of delta and mu opiate receptor localizations by light microscopic autoradiography.
Authors: Goodman R R , Snyder S H , Kuhar M J , Young W S
Published: May 2006

We have observed two discrete populations of opiate receptors that are differently localized in rat brain. Morphine-like (mu) receptors, labeled by 125I-labeled [D-Ala-2MePhe4Met(O)5-ol]enkephalin, are concentrated selectively in lamina IV of the cerebral cortex, certain thalamic nuclei, and the periaqueductal grey, while delta receptors, labeled by 125I-labeled [D-Ala2-D-Leu5]enkephalin, are more diffused, having high densities in cerebral cortex, corpus striatum, amygdala, and olfactory tubercle. Because of similarities in their localizations, we propose that mu and delta receptors are respectively the physiologic receptors for [Met]- and [Leu]enkephalin neurons. These distributions reflect the different physiological functions attributed to mu and delta receptors and thus represent discrete functions of [Met]- and [Leu]enkephalin neurons.
Dedicated-site, interim storage of high-level nuclear waste as part of the management system
Authors: Zen E-an
Published: May 2006

Dedicated-site interim storage of high-level reprocessed nuclear waste and of spent fuel rods is proposed as a long-term integral part of the systems approach of the national nuclear waste isolation program. Separation of interim sites for retrievable storage from permanent-disposal repositories should enhance ensurance of the performance of the latter; maintenance of retrievability at separate sites also has many advantages in both safety and possible use of waste as resources. Interim storage sites probably will not be needed beyond about 100 years from now, so the institutional and technical considerations involved in their choice should be much less stringent than those for the selection of permanent sites. Development of interim sites must be concurrent with unabated effort to identify and to develop permanent repositories.
Phase separation in mixtures of ionized iron in a hydrogen plasma
Authors: Alder B. J. , Pollock E. L. , Hansen J. P.
Published: May 2006

The accuracy of the hypernetted chain theory for mixtures of iron nuclei and protons in a charge-neutralizing background is demonstrated by comparison with molecular dynamics calculations. Near critical conditions the Debye-Hückel approximation fails to converge, even with second-order concentration corrections. The critical conditions, determined by assuming a uniform electron gas background, have a critical temperature more than a factor of 2 lower than present estimates of interior solar conditions. Qualitative arguments are made that including the polarization of the electron gas background would not change this result significantly and thus phase separation of iron in the interior of the sun is unlikely.
Role of kidney tissue in the production of 25-hydroxyvitamin D3-26,23-lactone and 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone.
Authors: Tanaka Y , Wichmann J K , Paaren H E , Schnoes H K , DeLuca H F
Published: May 2006

Labeled 25-hydroxyvitamin D3-26,23-lactone was isolated from the serum of vitamin D-repleted rats given [3 alpha-3H]-25-hydroxyvitamin D324 hr prior to sacrifice. The metabolite was identified by cochromatography with the authentic lactone on straight-phase and reversed-phase high-performance liquid chromatography. Production of the lactone was abolished by nephrectomy indicating that the kidney is the site of synthesis. Homogenate of kidneys from chickens given large doses of vitamin D can carry out in vitro production of the lactone from 25-hydroxyvitamin D3. When 1 alpha, 25-dihydroxyvitamin D3 was used as substrate, this system produced only traces of a compound believed to be 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone. However, incubation of rachitic chicken kidney homogenates with 25-hydroxyvitamin D3-26,23-lactone produced substantial amounts of a compound that has been identified by mass spectrometry as 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone. Thus, the development of a functional group on C-26 and eventual lactone formation takes place in kidney by a system acting on 25-hydroxyvitamin D3.
Control of serum protein production in hepatocyte hybridomas: immortalization and expression of normal hepatocyte genes.
Authors: Szpirer J , Szpirer C , Wanson J C
Published: May 2006

"Hepatocyte hybridomas" have been isolated after fusion of adult hepatocytes and alpha-fetoprotein (AFP)-producing mouse hepatoma cells. The yield of viable hybrid clones was low but could be increased by culturing the cells in the presence of insulin. On the basis of their chromosome constitution, the hybrids were classified into two groups characterized by either a single or a double set of mouse (hepatoma) chromosomes. The hybrids segregated rat chromosomes and thus constitute an excellent material for gene mapping studies in the rat. Most of the hepatocyte hybridomas retained the production of one or more rat serum proteins, indicating that the corresponding structural genes, contributed by the normal hepatocyte parent, have been immortalized and maintained in the active state after fusion. However, these hybrids do not produce rat AFP, although mouse AFP synthesis is maintained. This result strongly suggests that silent rat (hepatocyte) AFP genes coexist in hepatocyte hybridoma nuclei with active mouse (hepatoma) AFP genes. Finally, on the basis of certain properties of these hepatocyte-hepatoma hybrids, we suggest that the nondividing state of the hepatocytes is actively controlled by a regulatory mechanism which prevents DNA synthesis or entry into mitosis or both.
Sequential addition of platelet factor and plasma to BALB/c 3T3 fibroblast cultures stimulates somatomedin-C binding early in cell cycle.
Authors: Clemmons D R , Van Wyk J J , Pledger W J
Published: May 2006

Recent studies have shown that confluent cultured fibroblasts must be rendered competent by a factor contained in platelets before they can respond to plasma components and progress from G0 to S phase of the cell cycle. Somatomedin-C is one of the components of platelet-poor plasma necessary for cell cycle progression, but other factors present in somatomedin-C-deficient plasma are also required. Because both competence and progression factors contained in somatomedin-C-deficient serum modulate somatomedin-C action in fibroblasts, this study was undertaken to examine their possible influence on the binding of 125I-labeled somatomedin-C. Exposure of BALB/c 3T3 fibroblasts to high concentrations of platelet-derived growth factor alone prevented the time-dependent decrease in somatomedin-C binding which occurs in serum-free medium. Lower concentrations of the growth factor or 5% (vol/vol) platelet-poor plasma reduced but did not abolish this decrease. In contrast, sequential addition of platelet-derived growth factor followed by platelet-poor plasma resulted in a 75% increase in 125I-labeled somatomedin-C binding over basal levels during the first 2 hr. Binding increased by 125% when somatomedin-C-deficient platelet-poor plasma was substituted for normal platelet-poor plasma. The hormonal induction of somatomedin-C receptors appears to be a mechanism whereby peptide growth factors such as platelet-derived growth factor may condition the cell to respond optimally to somatomedin-C.
Cellulose biogenesis: Polymerization and crystallization are coupled processes in
Acetobacter xylinum
Authors: Benziman Moshe , Haigler Candace H. , Brown R. Malcolm , White Alan R. , Cooper Kay M.
Published: May 2006

Calcofluor White ST, stilbene derivative used commerically as an optical brightener for cellulose, increased the rate of glucose polymerization into cellulose by resting cells of the gram-negative bacterium
Acetobacter xylinum
. This bacterium normally produces a ribbon of cellulose that is a composite of crystalline microfibrils. In concentrations above 0.1 mM, Calcofluor disrupts the assembly of crystalline cellulose I microfibrils and their integration into a composite ribbon by stoichiometric binding to glucose residues of newly polymerized glucan chains. Under these conditions, the rate of glucose polymerization increases up to 4 times the control rate, whereas oxygen uptake increases only 10-15%. These observed effects are readily reversible. If free Calcofluor is washed away or depleted below the threshold value by binding to cellulose as polymerization continues, ribbon production and the normal rate of polymerization resume. It is concluded that polymerization and crystallization are cell-directed, coupled processes and that the rate of crystallization determines the rate of polymerization. It is suggested that coupling must be maintained for biogenesis of crystalline cellulose I.
Antiviral response elicited by a completely synthetic antigen with built-in adjuvanticity.
Authors: Arnon R , Sela M , Parant M , Chedid L
Published: May 2006

In a previous study we demonstrated that antiviral response against the coliphage MS-2 can be elicited by immunization with a synthetic antigen consisting of a conjugate (P2-A -- L) of a synthetic fragment (P2) of the virus coat protein attached to a synthetic polymeric carrier. The antiviral response was induced when the antigen was administered in complete Freund's adjuvant or when it was administered in incomplete adjuvant, provided that a peptidoglycan was covalently attached to it. In the present study we demonstrate the adjuvant effect of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) in this system. Immunization with a mixture of MDP and P2-A -- L brought about only slight enhancement in the titer of neutralizing antibodies, as compared to the immunization with P2-A -- L in saline. The best results were achieved when the MDP was chemically conjugated to P2-A -- L. This completely synthetic material, when administered in aqueous solution, yielded highly inactivating antiserum with a titer similar to that obtained with complete Freund's adjuvant in the absence of MDP. MDP-P2-A -- L elicited also a humoral immune response to MDP, but with much lower titer than that induced by complete Freund's adjuvant containing P2-A -- L only. It was also observed that the capacity of MDP-P2-A -- L to increase resistance against infection was more than a 100-fold greater than that of unconjugated MDP.
T-cell lines established from human T-lymphocytic neoplasias by direct response to T-cell growth factor.
Authors: Poiesz B J , Ruscetti F W , Mier J W , Woods A M , Gallo R C
Published: May 2006

Long-term growth of lymphoblastoid T cells from tissue samples from six of six patients with cutaneous T-cell lymphoma (CTCL) and six of six patients with acute T-lymphoblastic leukemia (ALL) has been achieved by using partially purified mitogen-free human T-cell growth factor (pp-TCGF). One cell line, CTCL-2, is now independent of added growth factor; the others continue to show absolute dependency on its presence. All lines have been in continuous culture for at least 4 months and some for > 1 year. They are erythrocyte-rosette positive and are negative for Epstein-Barr virus nuclear antigen. Most of the lines are negative for Fc and complement receptors and for surface immunoglobulin except that CTCL-1 and CTCL-2 have some cells positive for these cell surface markers. Results of histochemical studies on these cell lines are similar to the known patterns for fresh cells from their disease of origin. Cell line CTCL-3 has an abnormal karyotype, but no detectable chromosomal abnormalities were found in the other lines, consistent with the karyologic features of their clinical sources. Because T cells from normal donors do not respond to pp-TCGF unless the cells are first "activated" by a lectin mitogen such as phytohemagglutinin or an antigen, the direct response to pp-TCGF of T cells from patients with T-cell neoplasias suggests that the cell lines represent a transformed neoplastic cell population. Although some of the cell lines may be normal T cells activated by the malignant cells, the morphologic and histochemical properties of the cell lines, the abnormal karyotype of CTCL-3, and the independent growth of CTCL-2 support the conclusion that most of these cell lines are of malignant origin.
Structural analysis of factor VIII antigen in von Willebrand disease.
Authors: Nachman R L , Jaffe E A , Miller C , Brown W T
Published: May 2006

The Factor VIII antigen molecules in the plasma of patients with classical type 1 and variant type 2A von Willebrand disease were compared to the Factor VIII antigen molecules in normal plasma. Factor VIII antigen was isolated from plasma by solid-phase immunoprecipitation and analyzed by NaDodSO4/polyacrylamide gel electrophoresis; the stained Factor VIII antigen bands were removed, radioiodinated, and subjected to tryptic digestion. Computerized analysis of autoradiographs revealed that the two-dimensional peptide maps of the different Factor VIII antigens were remarkably similar. The results suggest that the Factor VIII antigen molecules in these two forms of von Willebrand disease are probably identical to the Factor VIII antigen molecules present in normal plasma. It is thus likely that the differences observed in plasma Factor VIII antigen in classical and variant von Willebrand disease are not due to qualitatively abnormal molecules but rather represent quantitative shifts in the metabolism of normal Factor VIII antigen molecules.
Relationship of biosynthesis of slow reacting substance to intracellular glutathione concentrations.
Authors: Parker C W , Fischman C M , Wedner H J
Published: May 2006

To further elucidate the role of glutathione (GSH) in the biosynthesis of slow reacting substance (SRS), SRS generation was studied in rat basophilic leukemia cells that had been preincubated with 2-cyclohexen-1-one or diethyl maleate to decrease their intracellular GSH concentrations. At low GSH levels SRS formation was markedly inhibited. The formation of other lipoxygenase products was much less affected, although some decrease in 5-hydroxyicosatetraenoic acid formation also occurred, apparently due in part to less rapid reduction of the 5-hydroperoxide.
Regulation by secretin, vasoactive intestinal peptide, and somatostatin of cyclic AMP accumulation in cultured brain cells.
Authors: van Calker D , Müller M , Hamprecht B
Published: May 2006

Secretin stimulates the accumulation of cyclic AMP (half maximally stimulating concentration: 10-20 nM) in cultured mouse brain cells mainly consisting of glioblasts. Vasoactive intestinal peptide (VIP) is much less potent in raising the level of cyclic AMP in these cultures. The effect of secretin but not that of VIP is inhibited by secretin-(5-27), a synthetic antagonist of secretin. Stimulation of the adrenergic alpha-receptors and the adenosine A1-receptors present on the cells attenuates the increase in cyclic AMP evoked by secretin and VIP. Somatostatin at low concentrations inhibits the accumulation of cyclic AMP (half-maximally inhibitory concentration: 3 nM), in the absence or presence of secretin, VIP, or isoproterenol. The results suggest that secretin might regulate the concentration of cyclic AMP in brain and provoke the question of a possible involvement of glial cells in the action of peptide hormones in the brain.
Chemical composition of Earth, Venus, and Mercury
Authors: Morgan John W. , Anders Edward
Published: May 2006

Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of available data shows only a few gross trends for the inner planets: FeO decreases with heliocentric distance, whereas volatiles are depleted and refractories are enriched in the smaller planets.
Cloning and complete nucleotide sequence of human 5'-alpha-globin gene.
Authors: Liebhaber S A , Goossens M J , Kan Y W
Published: May 2006

We have cloned one of the two human alpha-globin genes and report its complete nucleotide sequence. The gene is 832 base pairs (bp) long from the 5'-cap site to the 3'-polyadenylylation site. The amino acid coding sequences are separated into three segments (exons) by two short (117 and 140 bp) intervening sequences. Highly conserved regions are identified in the 5'-flanking region, intron-exon junctions, and 3' noncoding regions that may have functional significance.
A change in the rate of transcription of a eukaryotic gene in response to cyclic AMP.
Authors: Williams J G , Tsang A S , Mahbubani H
Published: May 2006

The plasmid pDd812 contains the DNA copy of an mRNA sequence from Dictyostelium discoideum that undergoes first an increase and then a decrease in concentration during the first few hours of differentiation. We have recently shown that the mRNA sequence complementary to pDd812 encodes discoidin I, a developmentally regulated lectin that may play a role in cellular cohesion. By using pDd812 as a hybridization probe, we found that addition of cyclic AMP during the first few hours of development inhibited the accumulation of discoidin I mRNA. By measuring the rate of transcription in isolated nuclei, we showed that, at least in part, this inhibition results from a rapid and specific reduction in the rate of transcription of the discoidin I gene. Addition of cyclic AMP during the first few hours of development inhibited the accumulation of discoidin I mRNA. By measuring the rate of transcription in isolated nuclei, we showed that, at least in part, this inhibition results from a rapid and specific reduction in the rate of transcription of the discoidin I gene. Addition of cyclic AMP during the first few hours of development inhibited the accumulation of discoidin I mRNA. By measuring the rate of transcription in isolated nuclei, we showed that, at least in part, this inhibition results from a rapid and specific reduction in the rate of transcription of the discoidin I gene. Addition of high external concentrations of cAMP is known to increase the intracellular concentration to a level normally found later in development. This natural increase in cAMP concentration occurs at the time during development when transcription of the discoidin I gene ceases. We suggest, therefore, that changes in the intracellular concentration of cAMP act at the level of transcription to control gene expression during development. This hypothesis is supported by our observation that several poly(A)+RNA sequences that normally accumulate after transcription of the discoidin I gene has ceased are synthesized prematurely in cells exposed to exogenous cAMP.
Adenylate deaminase binding to synthetic thick filaments of myosin.
Authors: Koretz J F , Frieden C
Published: May 2006

Adenylate deaminase (AMP deaminase; AMP aminohydrolase, EC 3.5.4.6), a tetrameric enzyme found at particularly high concentrations in skeletal muscle, has previously been shown to bind strongly to the subfragment-2-portion of myosin in vitro and to the ends of the A band in vivo. It is shown here that when adenylate deaminase is dialyzed with skeletal myosin during formation of synthetic filaments at pH 7.0 it decorates the filament at 14.3-nm intervals, presumably in the region of exposed backbone between crossbridge levels. Optical diffraction of the aggregates reveals both enhancement of reflections arising from underlying myosin organization and other reflections arising from adenylate deaminase arrangement on the filament surface. Adenylate deaminase can thus be used as a specific label in the study of myosin presence and organization.
Molecular structure of an anticancer drug-DNA complex: daunomycin plus d(CpGpTpApCpG).
Authors: Quigley G J , Wang A H , Ughetto G , van der Marel G , van Boom J H , Rich A
Published: May 2006

The structure of the crystalline daunomycin-d(CpGpTpApCpG) complex has been solved by x-ray diffraction analysis. The DNA forms a six-base-pair right-handed double helix with two daunomycin molecules intercalated in the d(CpG) sequences. The daunomycin aglycone chromophore is oriented at right angles to the long dimension of the DNA base pairs and the cyclohexene ring rests in the minor groove. Substituents on this ring have hydrogen bonding interactions to the base pairs above and below the intercalation site. These appear to be specific for anthracycline antibiotics. The amino sugar lies in the minor groove of the double helix without bonding to the DNA. The DNA double helix is distorted in a novel manner in accommodating the drug.
Relationship between x-ray exposure and malignant transformation in C3H 10T1/2 cells.
Authors: Kennedy A R , Fox M , Murphy G , Little J B
Published: May 2006

The appearance of transformed foci after x-irradiation of the C3H 10T1/2 line of murine cells requires extensive proliferation followed by prolonged incubation under conditions of confluence. When the progeny of irradiated cells are resuspended and plated to determine the number of potential transformed foci, the absolute yield is constant over a wide range of dilutions and is similar to that observed in cultures that have not been resuspended. In addition, for cells exposed to a given x-ray dose, the number of transformed foci per dish is independent of the number of irradiated cells. These observations suggest that few, if any, of the transformed clones occur as a direct consequence of the x-ray exposure and challenge the hypothesis that transformed foci are the clonal products of occasional cells that have experienced an x-ray-induced mutational change. Rather, it appears that at least two steps are involved. We suggest that exposure to x-rays result in a change, for example, the induction or expression of some cell function, in many or all of the cells and that this change is transmitted to the progeny of the surviving cells; a consequence of this change is an enhanced probability of the occurrence of a second step, transformation, when these cells are maintained under conditions of confluence.
Mouse immunoglobulin D: construction and characterization of a cloned delta chain cDNA.
Authors: Mushinski J F , Blattner F R , Owens J D , Finkelman F D , Kessler S W , Fitzmaurice L , Potter M , Tucker P W
Published: May 2006

TEPC 1017 is a BALB/c plasmacytoma that synthesizes IgD in large enough amounts to permit the isolation of mRNA for mouse delta chains. cDNA has been prepared from this mRNA, and an 880-base-pair fragment of it has been cloned by recombinant DNA techniques. The hybridization selection technique has been used to show that this cDNA clone specifically binds only mRNA that can be translated into immunoprecipitable delta chains. the sequence of a portion of this clone has been determined and, when translated, shows homology with the C delta 3 of a human myeloma protein. Using this cDNA clone as a probe, we have found that several different-sized delta RNAs are present in TEPC 1017 and in another IgD-secreting plasmacytoma, TEPC 1033.
Anti-AMP antibody precipitation of multiply adenylylated forms of glutamine synthetase from Escherichia coli: a model relating both concentration and density of antigenic sites with the antibody-antigen interaction.
Authors: Hohman R J , Rhee S G , Stadtman E R
Published: May 2006

Sheep antibodies directed against an AMP-bovine serum albumin conjugate exhibit highly specific binding toward AMP. These antibodies bind to the AMP moiety of adenylylated glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] from Escherichia coli and to no other antigenic determinant on the protein. E coli glutamine synthetase can exist in variously modified (isomeric) forms that differ with respect to the number (0-12) and the distribution of identically adenylylated subunits [Ciardi, J. E., Cimino, F. & Stadtman, E. R. (1973) biochemistry 12, 4321-4330]. Using this enzyme, together with the AMP-specific antibodies, we have investigated the effects of the total concentration, population density, and topographical distribution of multiple identical antigenic determinants on the antigen-antibody interaction. Stopped flow fluorescence measurements show that the rate and extent of initial binding of the antibodies to the antigen are a function of the total concentration of AMP groups and are independent of the number of AMP groups der dodecamer. However, the rate of lattice formation increases with increasing epitope density, and the maximal amount of glutamine synthetase precipitated is directly proportional to the average number of adenylylated subunits per dodecamer. The data suggest that partially adenylylated enzyme preparations are composed of subpopulations of glutamine synthetase molecules that differ in their tendency to form precipitable aggregates, due presumably to differences in the topographical distribution of antigenic determinants on the surface of the enzyme. The enzyme species that form soluble immune complexes do so possibly due to intramolecular crosslinkage of the bivalent antibodies with adenylylated subunits to the exclusion of intermolecular crosslinkage.
In vitro gamma irradiation of leukemic cells in mice, rats, and guinea pigs.
Authors: Gross L , Dreyfuss Y , Ehrenreich T , Feldman D , Limbert L M
Published: May 2006

In vitro gamma irradiation of virus-induced (Gross) mouse leukemia cells at doses of 350-1600 rads (1 rad = 0.01 gray) had no effect on their ability to induce leukemia, usually within 2 weeks, after transplantation into syngeneic mice. However, when cells irradiated at doses of 2000-20,000 rads were transplanted, they induced leukemia after a latency period exceeding 2.5 months, similar to the results observed in mice inoculated with filtered mouse leukemia extracts. Similar results were also obtained after irradiation of leukemic cells derived from rats in which leukemia had been induced by rat-adapted mouse leukemia virus. Apparently, gamma irradiation at a dose of, or exceeding, 2000 rads, inhibits the ability of mouse and rat leukemic cells to induce leukemia after transplantation into syngeneic hosts; however, it does not inactivate the virus carried by such cells nor prevent it from inducing leukemia. [In previous experiments, doses of more than 4,500,000 rads were needed to inactivate the passage A (Gross) leukemia virus carried in either mouse or rat leukemic cells.] In vitro gamma irradiation of L2C guinea pig leukemic cells at doses of 750-2500 rads had no apparent effect on their ability to induce leukemia after transplantation effect on their ability to induce leukemia after transplantation into strain 2 guinea pigs. However, irradiation at doses of 3250-20,000 rads inactivated their ability to do so. The morphology of mouse, rat, and guinea pig leukemic cells and the virus particles present in such cells was not affected by irradiation at doses of 20,000 rads.
Replication of the scrapie agent in ocular neural tissues.
Authors: Buyukmihci N , Rorvik M , Marsh R F
Published: May 2006

Optic nerves and retinas removed from hamsters experimentally inoculated with the scrapie agent contain a high titer of infectivity. Ophthalmoscopic examination of these animals revealed gross lesions of retinopathy as early as 3 weeks before the onset of clinical signs of brain degeneration. These results suggest that the scrapie agent may spread centrifugally in nerve fibers after intracerebral inoculation and that the scrapie-associated retinopathy seen in hamsters is directly induced by the agent rather than the result of retrograde degeneration from central neural damage.
Functional implantation of a solubilized β-adrenergic receptor in the membrane of a cell
Authors: Eimerl Sara , Neufeld Gera , Korner Mira , Schramm Michael
Published: May 2006

When the β-adrenergic receptor of turkey erythrocytes was solubilized by deoxycholate, it retained its potential to activate an adenylate cyclase system. Electron microscopy showed that true solubilization had apparently been achieved; no residual membrane or vesicle structure was found. After removal of deoxycholate and addition of phospholipid, the reprecipitated β-adrenergic receptor was implanted in the cell membrane of Friend erythroleukemia cells by using a chemical fusion method recently developed. Membranes prepared from the cells demonstrated 30-fold stimulation of the Friend cell adenylate cyclase by the implanted β-adrenergic receptor. The function of the indigenous prostaglandin E
1
receptor of the Friend cells was not much affected by the implantation of large amounts of the foreign receptor. Activity mediated by the β-adrenergic receptor reached 60% of the activity obtained with fluoride. The implanted receptor is therefore considered to be efficiently coupled to the adenylate cyclase system. The major difficulties hitherto preventing solubilization of hormone receptors and subsequent reconstitution of their function have been overcome by the approach developed in the present work. Conditions of solubilization need preserve only the receptor because all other components, even those unidentified as yet, can be supplied in excess by the adenylate cyclase system of the cell in which the receptor will be implanted. Subsequent recoupling of the receptor to the adenylate cyclase is performed in the native insoluble state of these molecules. Thus, the components need not be subjected to the hazards of solubilization in a common detergent as is usually required in reconstitution procedures. The importance of using implantation as an assay for a functional receptor in the course of purification and the likelihood that the procedure can be adapted to other receptors for hormones and neurotransmitters are discussed.
An Escherichia coli replication protein that recognizes a unique sequence within a hairpin region in phi X174 DNA.
Authors: Shlomai J , Kornberg A
Published: May 2006

Protein n', a prepriming DNA replication enzyme of Escherichia coli, is a phi X174 DNA-dependent ATPase. Restriction of phi X174 DNA have led to the identification of a 55-nucleotide fragment that carries the protein n' recognition sequence. Molecular hybridization and sequence analysis have located this sequence within the untranslated region between genes F and G, a map location analogous to that of the unique complementary strand origin of phage G4 DNA. Within the 55-nucleotide fragment is a sequence of 44 nucleotides that forms a stable hairpin structure. This duplex may be the signal for protein n' to initiate the prepriming events that led to the start of phi X174 complementary DNA strand replication.
Actin nascent chains are substrates for cyclic AMP-dependent phosphorylation in vivo.
Authors: Steinberg R A
Published: May 2006

Two-dimensional gel electrophoresis of extracts of S49 mouse lymphoma cells labeled with [35S]methionine in the presence of inducers or analogs of cyclic AMP reveals a protein that both affinity purification and peptide mapping show to be a form of nonmuscle actin. This actin species also exhibits cyclic AMP-dependent labeling with [32P]phosphate, and, after acid hydrolysis, 32P label is found associated with phosphoserine. Phosphorylated actin does not appear when cells prelabeled with [35S]methionine are treated with an inducer of cyclic AMP in the presence of emetine, an inhibitor of protein synthesis; this suggests that only the nascent form of actin is a substrate for cyclic AMP-dependent phosphorylation. As well as differing slightly in isoelectric points, beta and gamma actins are found to yield different partial proteolytic cleavage products with staphylococcal protease. This microheterogeneity in the major cellular actin component is repeated in both the metabolically labile delta/epsilon actin and phosphorylated actin, suggesting that these three forms of actin derive from the same two gene products.