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Results for “differential selection”

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At least 325 records · Page 18Linked to original sources
PubMed1990

The effects of a promoter of cell differentiation and selected hormones on human cytomegalovirus infection using an in vitro cell system.

The influence of factors that can regulate cellular developmental or metabolic processes in host tissue on cytomegalovirus (CMV) replication in vitro was determined. Hydrocortisone treatment of cells before viral infection resulted in a 12- to 13-fold increase in the expression of immediate early proteins at 4 h after virus inoculation. The addition of a phorbol diester 1.5 h after CMV infection resulted in an 8- to 13-fold increase in production of viral progeny. In contrast, beta-human chorionic gonadotropin treatment generally resulted in a 25%-72% suppression of both CMV-specific proteins and progeny. Effects on CMV infection with either progesterone or estradiol were minor and generally suppressive. The stimulating or suppressive effects of these factors on CMV replication in vitro may be important to CMV reactivation in humans. Further study of regulatory factors may lead to the development of therapeutic approaches to the prevention of CMV reactivation in patients at risk for severe disease.

Cell Differentiation↗
PubMed1985

A human B cell differentiation antigen selectively expressed on mature B cells identified by a monoclonal antibody (HB-2).

A monoclonal IgM antibody (HB-2), produced against a membrane antigen on the Raji, B cell line, reacted by indirect immunofluorescence with 2 to 40% of lymphoblasts from the B cell lines, Raji, Daudi, SN-1036, and SB but not with other types of cell lines, including pre-B, myeloid, melanoma, or T cells. HB-2 antibody reacted with 10 +/- 3% of normal blood mononuclear cells, and was unreactive with monocytes, granulocytes, platelets, or erythrocytes. Two-color immunofluorescence revealed that HB-2 antigen expression was confined to cells bearing surface Ig. An interesting finding was the fact that 25% of plasmablasts induced by pokeweed mitogen also expressed the HB-2 antigen. However, pre-B and plasma cells from normal bone marrow did not express the HB-2 antigen either on their membrane surface or in their cytoplasm. Analysis of 85 leukemias revealed that the HB-2 antigen was expressed on acute and chronic B cell leukemias and Burkitt's lymphomas, but not on malignancies of pre-B, T, myelocytic, or plasma cells. The results suggest that expression of the HB-2 antigen is confined to mature B cells.

Antibodies, Monoclonal↗
PubMed2006

A tale of two targets: differential RNA selectivity of nucleobase-aminoglycoside conjugates.

Aminoglycoside antibiotics are RNA-binding polyamines that can bind with similar affinities to structurally diverse RNA targets. To design new semisynthetic aminoglycosides with improved target selectivity, it is important to understand the energetic and structural basis by which diverse RNA targets recognize similar ligands. It is also imperative to discover how novel aminoglycosides could be rationally designed to have enhanced selectivity for a given target. Two RNA drug targets, the prokaryotic ribosomal A-site and the HIV-1 TAR, provide an excellent model system in which to dissect the issue of target selectivity, in that they each have distinctive interactions with aminoglycosides. We report herein the design, synthesis, and binding activity of novel nucleobase-aminoglycoside conjugates that were engineered to be more selective for the A-site binding pocket. Contrary to the structural design, the conjugates bind the A-site more weakly than does the parent compound and bind the TAR more tightly than the parent compound. This result implies that the two RNA targets differ in their ability to adapt to structurally diverse ligands and thus have inherently different selectivities. This work emphasizes the importance of considering the inherent selectivity traits of the RNA target when engineering new ligands.

Aminoglycosides↗
PubMed1979

Hypnotic susceptibility to various depressants in rats selected for differential ethanol sensitivity.

MA rats, bred for greater motor impairment following subhypnotic doses of ethanol, were found to be more sensitive to the hypnotic effects of phenobarbital and chloral hydrate than were LA rats. In addition, the previously reported finding of a difference between the two lines of rats in duration of loss of righting reflex following a hypnotic dose of ethanol was replicated. The results are discussed in terms of a phenotypic difference in central nervous systems sensitivity to a range of sedative-hypnotics.

Animals↗
PubMed2000

[Differential transplant selection in cruciate ligament surgery].

Over the past century numerous graft materials have been used for the reconstruction of the cruciate ligament of the knee. Among the autologous tissues that are currently recommended as graft materials, the central bone patellar tendon bone graft, a quadrupled hamstring graft and the central quadriceps tendon graft have the greatest clinical significance. With some limitations, allograft materials can also be used. Each of the three mentioned grafts has specific features regarding morphological and structural properties, graft fixation and graft incorporation. Clinical studies have failed to identify any of the three grafts as superior to the others. When choosing the graft for surgery the different anatomy and function of the anterior and posterior cruciate ligaments have to be considered. For the treatment of multiple ligament injuries and for revision cases, thorough preoperative planning is necessary and modified graft selection may be required.

Anterior Cruciate Ligament↗
PubMed1979

Differential and selective inhibition of cellular and herpes simplex virus DNA synthesis by arabinofuranosyladenine.

The influence of 9-beta-D-arabinofuranosyladenine (beta araAdo) and of its anomer 9-alpha-D-arabinofuranosyladenine (alpha araAdo) was studied in non-infected cells and cells infected with herpes simplex virus type 1 (HSV-1) and HSV type 2 (HSV-2). alpha AraAdo is a strong inhibitor of proliferation of non-infected cells. Multiplication of HSV-1 and HSV-2 is not affected at all by alpha araAdo, while their growth is strongly inhibited by beta araAdo. alpha AraAdo exerts no effect on the incorporation of dThd into HSV DNA, but blocks the incorporation into host cell DNA. Its anomer, beta araAdo, affects the incorporation rate of both the viral DNA system and the host cell DNA system (the latter one to a lesser extent). alpha AraAMP is incorporated into newly synthesized cellular DNA but not into HSV DNA. Enzymic studies relevant that alpha araATP has no effect on the HSV DNA polymerase system but a high inhibitory potency in the host cell DNA polymerase alpha system. The anomeric form, beta araATP, is a sensitive inhibitor of HSV DNA polymerase while the cellular DNA polymerases alpha and beta are more refractory.

Adenosine Triphosphate↗
PubMed1983

Differential substrate selectivity of murine hepatic cytosolic and microsomal epoxide hydrolases.

The initial rates of hydration of sixteen epoxides in the presence of cytosolic and microsomal fractions of mouse liver were determined. 1,2-Disubstituted trans-epoxides were found to be excellent, selective substrates for the cytosolic epoxide hydrolase, while 1,2-cis-epoxides were poorly hydrated when one or more substituents was a phenyl moiety. Epoxides of cyclic systems including benzo[alpha]pyrene 4,5-oxide, and two cyclodiene analogs were hydrated almost exclusively by the microsomal epoxide hydrolase while monosubstituted epoxides were hydrated by both systems. Some epoxides which were mediocre substrates proved to be reasonable inhibitors of the cytosolic epoxide hydrolase, indicating that the structural requirements for substrate binding and turnover are different. Some reagents known to interact with sulfhydryl groups, including styrene oxide, proved to be good inhibitors. This work facilitates the design of radiochemical and spectrophotometric assays for both major forms of epoxide hydrolase as well as prediction of potential intrinsic substrates. Also such data may be meaningful in assessing the risk involved in human exposure to epoxidized xenobiotics.

Animals↗
PubMed1986

Neuronal membrane enzymes in rat lines selected for differential motor impairment by ethanol.

Neuronal membrane enzyme activities were determined in naive and ethanol-treated (30 min after 2 g/kg) male and female rats of lines developed for more (ANT) and less (AT) ethanol-induced motor impairment. Ethanol did not affect acetylcholinesterase, (Na+K)-ATPase or 5'-nucleotidase activities, but adenylate cyclase activities were lowered in both cerebellum and cerebrum. Cerebral acetylcholinesterase activities were higher in ANT than AT rats. No consistent line difference was observed regarding (Na+K)-ATPase activities. Slightly higher cerebellar 5'-nucleotidase activities were found in the ANT line. Cerebellar adenylate cyclase levels were substantially higher in the AT line. No line differences were displayed in the activation of adenylate cyclase activity by dopamine or norepinephrine. It is concluded that ethanol in vivo may inhibit neuronal adenylate cyclase activity and that cerebellar phosphorylation may be a regulator of motor impairment. Cholinergic mechanisms may also be connected to the ethanol-induced motor impairment.

5'-Nucleotidase↗
PubMedDate not supplied

[3H]MK-801 binding in various brain regions of rat lines selected for differential alcohol sensitivity.

N-Methyl-D-aspartate (NMDA) receptors are sensitive to ethanol at concentrations relevant to intoxication. To ascertain possible involvement of NMDA receptors in differential ethanol sensitivity between alcohol-sensitive ANT (alcohol-nontolerant) and alcohol-insensitive AT (alcohol-tolerant) rat lines, characterization of a noncompetitive NMDA antagonist [3H]MK-801 binding to brain membranes was carried out. Saturation analyses of [3H]MK-801 binding to cerebrocortical, hippocampal, and cerebellar synaptosomal membranes revealed no statistically significant differences in either the affinity constant (Kd) or binding site density (Bmax) between the rat lines. Autoradiographic analysis of [3H]MK-801 binding to ANT and AT brain sections revealed a regionally heterogenous distribution of binding, without any detectable differences between the AT and ANT sections whether these were prepared from the brains of acutely ethanol-treated or nontreated animals. Glutamate, glycine, or the two in combination greatly increased [3H]MK-801 binding to brain membranes. In extensively washed crude cerebrocortical membranes, the maximal effect (Emax), but not potency (EC50) of glycine to increase [3H]MK-801 was slightly greater (p < 0.01) in the ANT than AT rats. The effects of glutamate or glutamate in the presence of saturating concentration of glycine (30 microM) were not significantly different between the two lines. Association parameters (t1/2 and Beq values) of [3H]MK-801 to its cortical binding sites were also similar. These results do not indicate any clear qualitative difference in [3H]MK-801 binding to NMDA receptors or in its modulation by glutamate and glycine between the ANT and AT rat lines.

Animals↗