A single-cell model for CHO cells.
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Animals↗
Biomedical subjects
P Wu
Publications and source records attributed to P Wu.
Orientation factor in steady-state and time-resolved resonance energy transfer measurements.
Resonance energy transfer measurements provide a way to estimate distances between chromophores attached to different sites of macromolecules. There are two unknowns involved in resonance energy transfer measurements, the distance between two chromophores and their relative orientation. When static orientational disorder exists, the orientation factor, kappa 2, can vary from 0 to 4, leading to considerable uncertainty in estimation of distances. Fluorescence polarization anisotropy measurements can reduce the degree of uncertainty [Dale & Eisinger (1974) Biopolymers 13, 1573]. There may still be substantial error bounds for the average distance measurements. Time-resolved fluorescence measurements provide an "apparent" average distance and distance distribution containing contributions by both distance and orientation. The contribution of orientation to observed "apparent" average distance and distance distribution widths has been estimated for both simulated and real data. With a single unique distance as input in the simulation and with random but static orientation of donor and acceptor, the recovered average distance is very close to that of the input when the input distance is close to or larger than the Förster distance. The recovered width of apparent distance distribution can be substantial and it changes as a function of Förster distance to average distance ratio and as a function of Förster distance. Similar conclusions apply to the case where there is a real distance distribution. Motional averaging of the orientation was simulated by the Monte Carlo method to estimate the contribution of orientation when chromophores have certain degrees of mobility.(ABSTRACT TRUNCATED AT 250 WORDS)
Chemical Phenomena↗
Alteration in T cell/macrophage ratio may reveal lymphocyte proliferation specific for the triggering antigen in reactive arthritis.
It has previously been shown that synovial fluid (SF) mononuclear cells (MNC) from patients with reactive arthritis (ReA) and some patients with undifferentiated oligoarthritis (UOA) respond specifically to the triggering bacterium (specific responders). However, in some patients there is a response to two or more bacteria (non-specific responders) and in a third group no response is found (non-responders). We assessed whether the proportion of synovial MNC which were macrophage-monocyte (MaMo) differed among the specific responder, non-specific responder and non-responder groups. There was no difference between the specific (33 +/- 9) and the non-specific (32 +/- 26) groups; non-responders had a higher percentage of MaMo (61.3 +/- 31%) although the difference was not significant. We also investigated whether the specificity of the response to antigen in ReA or UOA SF was altered by changing the T-cell/MaMo ratio. In all five specific responders the immune response remained specific whatever the ratio tested. However, four of the five non-specific responders, but none of the non-responders, developed a specific response to one of the tested antigens by increasing the T cell/MaMo ratio. We conclude that in some patients with a non-specific response, alteration of the T cell/MaMo ratio uncovers a specific response which may identify the triggering antigen.
Adult↗
Early detection of antibody to human immunodeficiency virus type 1 by using an antigen conjugate immunoassay correlates with the presence of immunoglobulin M antibody.
Sequential plasma samples obtained from 16 individuals who seroconverted were tested for the presence of antibody to human immunodeficiency virus type 1 (HIV-1) by an antigen conjugate enzyme immunoassay (EIA) and a conventional antibody conjugate assay. In 11 of these individuals, the antigen conjugate assay detected antibody to HIV-1 2 to 11 days (mean, 5.5 days) earlier than the antibody conjugate assay. In 11 individuals, HIV-1 p24 antigen was detected a median of 6.5 days (range, 3 to 14 days) prior to positivity by the antigen conjugate EIA. Using class-specific probes, we determined the profiles of immunoglobulin M (IgM), IgG, and IgA antibodies for each individual and correlated these profiles with the EIA signals from both assays. In general, the appearance of IgM exhibited a peak at about 1 week postseroconversion, which was followed by gradually declining levels. Absorbance levels for IgG antibody, however, rose steadily and reached a plateau after 3 to 5 weeks. The levels of IgA were generally low and variable. In contrast to the progressive increase in EIA absorbance observed by the antibody conjugate assay, the antigen conjugate assay displayed a rapid early rise in absorbance which generally coincided with the transient expression of IgM antibody. The subsequent gradual increase coincided with rising levels of IgG. Because the configuration of the antigen conjugate EIA allows for an increased sensitivity for IgM compared with that for other classes of immunoglobulins, these results suggest that earlier detection of antibody to HIV-1 is due to the detection of IgM antibody during the early phase of seroconversion.
Biomarkers↗
Aetiological role of bacteria associated with reactive arthritis in pauciarticular juvenile chronic arthritis.
BACKGROUND: The cause of juvenile chronic arthritis (JCA) is unknown. Pauciarticular JCA is the most common subtype and can be subdivided into early (type I) and late onset (type II) forms, the latter clinically resembling reactive arthritis. METHODS: The cellular immune responses to bacteria associated with reactive arthritis in blood and synovial fluid from 39 children with pauciarticular JCA, three children with classical reactive arthritis, and two children with psoriatic arthritis were examined. Specific titres of antibodies to bacteria in serum samples were measured in all patients. RESULTS: A bacteria specific synovial cellular immune response was found in two of three (67%) patients with reactive arthritis and 14 of 28 (50%) patients with pauciarticular JCA type II but only in one of 11 (9%) patients with pauciarticular JCA type I and none in patients with psoriatic arthritis. Six patients responded specifically to Chlamydia trachomatis and 11 to Yersinia enterocolitica. Antigen specific lymphocyte proliferation correlated poorly with the specific antibody response. CONCLUSIONS: These findings suggest that bacteria with associated reactive arthritis may have a causative role in pauciarticular JCA type II but not in JCA type I.
Adolescent↗
Astragalus membranaceus stimulates human sperm motility in vitro.
Poor sperm motility is an important cause of male infertility. In an attempt to identify Chinese medicinal herbs that might improve human sperm motility in vitro, we screened water extracts of 18 herbs with a trans-membrane migration method which measured the percentage of sperm that moved across the 5 micron pores of a Nucleopore membrane from a semen-drug mixture into phosphate buffered saline during 2 hours incubation. Astragalus membranaceus was the only herb that showed a significant stimulatory effect. At 10 mg/ml, it increased the motility of sperm in semen to 146.6 +/- 22.6% of control. It also increased the motility of washed sperm to 138.2 +/- 13.8% of control. Purification of the active component(s) from this herb as well as its application in assisted reproduction technology await further investigation.
Astragalus propinquus↗
Brain death in the neonate: assessment with P-31 MR spectroscopy.
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Brain↗
Biochemical studies of the actions of ethanol on acetylcholinesterase activity: ethanol-enzyme-solvent interaction.
1. Biochemical studies of the actions of ethanol on the activity of acetylcholinesterase (AChE), isolated from electric eel (Electrophorus electricus) and purified by affinity chromatography, were performed to elucidate ethanol-enzyme-solvent interactions. 2. Ethanol at a low concentration [( EtOH] = 2.7-200 mM) was found to enhance AChE activity slightly and systematically. 3. This observation was consistent with the result from enzyme-kinetic studies that ethanol might noncompetitively activate AChE activity at this lower concentration range. 4. If ethanol alters the hydrophobic site interaction on the enzyme and subsequently induces a favorable conformation for the active center of the enzyme, then a slight increase in the AChE activity in the presence of a low concentration of ethanol will be observed. 5. This speculation was supported by the finding of ethanol's ability to perturb the inhibition of AChE activity by tetrabutylammonium bromide and to affect hydrophobic interaction between this salt and AChE, as investigated by enzyme activity and microcalorimetric measurements. 6. The ethanol effect on the activity of this soluble AChE was found to be distinguishable from that on a membrane-bound AChE. 7. Furthermore, to elucidate the effect of ethanol-solvent interaction on AChE activity, enzyme activity in the presence of much higher concentrations of ethanol was also examined. 8. At [EtOH] greater than 800 mM, ethanol can perturb the structure of water around hydrophobic areas of AChE, causing an instability in the enzyme conformation and subsequently decreasing AChE activity.
Acetylcholinesterase↗
Mapping point mutations in the Drosophila rosy locus using denaturing gradient gel blots.
Mutations within the rosy locus of Drosophila were mapped using blots of genomic DNA fragments separated on denaturing gradient gels. DNA sequence differences between otherwise identical small rosy DNA fragments were detected among the mutants as mobility shifts on the blots. Mutations were mapped to within a few hundred base pairs of rosy sequence in 100 of 130 mutants tested--a 77% detection rate. The sequence changes in 43 rosy mutations are presented; all but six of these were single base changes. Thirty-four of 36 sequenced mutations induced by the alkylating agents N-ethyl-N-nitrosourea and ethyl methanesulfonate were transitions. All of the mutations mapped in the rosy transcription unit. Twenty-three of the 43 sequenced mutations change the predicted rosy gene polypeptide sequence; the remainder would interrupt protein translation (17), or disrupt mRNA processing (3).
Animals↗
Changes in rat pituitary POMC mRNA after exposure to cold or a novel environment, detected by in situ hybridization.
Plasma adrenocorticotropin (ACTH) levels increase after acute cold exposure. The purpose of this study was to determine if there were parallel changes in pituitary proopiomelanocortin (POMC) mRNA. Male rats were exposed to cold (3-5 degrees C) or a novel environment for 15 or 30 min. Others were unstressed. POMC mRNAs in frozen sections or dissociated cells were hybridized with a photobiotinylated oligonucleotide probe which was detected in situ by streptavidin-alkaline phosphatase. The percentage of area labeled for POMC mRNA was quantified by the Cue-3 color image analysis system. In frozen sections, 24-fold increases in the percentage of area labeled for POMC mRNA were evident in intermediate lobes (IL) 30 min after stress. No change was seen in anterior lobes (AL). If the ALs were dissociated, a 66-99% increase in percentage of labeled cells was detected 2-3 hr after the cold exposure. Fifteen min of cold stress (CS) also caused a 117% increase in the area of label for POMC mRNA per corticotrope. No change was seen after 30 min. Exposure to a novel environment caused a 73% increase in the percentage of area labeled for POMC mRNA per AL corticotrope and an 11-fold increase in the IL. These results indicate that both AL corticotropes and IL melanotropes are stimulated by acute exposure to cold and novel environments.
Adrenocorticotropic Hormone↗
Central nervous system abnormalities in Lyme neuroborreliosis.
Intrathecal production of anti-Borrelia burgdorferi antibody occurs frequently in CNS Lyme, yet reliable diagnosis of neuroborreliosis is still considered difficult and controversial. Therefore, we assessed the utility of this measurement in 103 Lyme patients. Among 15 patients with Lyme meningoradiculitis and 41 controls, diagnostic specificity was 93% and sensitivity 87%. Application of this method permits the identification of a rare B burgdorferi-associated multifocal encephalitis (brain infection) and its differentiation from a milder encephalopathy, or confusional state; the latter may not require CNS bacterial invasion. The encephalitis involves white matter more often than gray; severity varies widely. Of six patients with this antibiotic-responsive encephalitis, five were positive for HLA DQw3(DQw7). We conclude that (1) measurement of intrathecal antibody production is a reliable indicator of CNS infection, (2) North American neuroborreliosis includes the same spectrum of neurologic dysfunction as described in Europe, and (3) HLA typing may be useful in furthering our understanding of severe CNS involvement.
Adult↗
[Preoperative skin preparation with chemical depilation].
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Animals↗
Formation of a glutathionyl-conjugate of hepoxilin A3 and its action in rat brain.
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8,11,14-Eicosatrienoic Acid↗
Purification and characterization of an NAD(+)-dependent dehydrogenase that catalyzes the oxidation of thromboxane B2 at C-11 from porcine liver. Development and application of 11-dehydro-thromboxane B2 radioimmunoassay to enzyme assay.
11-Dehydro-thromboxane B2 has been identified as a major metabolite of infused as well as endogenous thromboxane B2 in mammalian plasma and urine. This metabolite is derived from thromboxane B2 by enzymatic oxidation at C-11 catalyzed by 11-hydroxythromboxane B2 dehydrogenase. A radioimmunoassay for 11-dehydro-thromboxane B2 has been developed and used for enzyme assay, purification and characterization. Antibodies were generated against 11-dehydro-thromboxane B2 conjugated to bovine thyroglobulin. Labeled marker was prepared by radioiodinating 11-dehydro-thromboxane B2-tyrosine methyl ester conjugate. A sensitive radioimmunoassay capable of detecting 10 pg of 11-dehydro-thromboxane B2 per assay tube was developed. The antibodies showed minimal crossreaction with thromboxane B2 (0.03%), prostaglandin D2 (2.76%) and other eicosanoids (less than 0.03%). The enzyme activity was determined by assaying NAD(+)-dependent formation of immunoreactive 11-dehydro-thromboxane B2 from thromboxane B2. The enzyme was found to be enriched in liver although significant activity was also detected in gastrointestinal tract and kidney in pig. The enzyme was purified from porcine liver cytosol to apparent homogeneity using conventional and affinity chromatography. The purified enzyme exhibited coenzyme specificity for NAD+ and used thromboxane B2 as a substrate. The enzyme also catalyzes NADH-dependent reduction of 11-dehydro-thromboxane B2 to thromboxane B2 indicating the reversibility of the enzyme catalyzed reaction. The apparent Km values for thromboxane B2, 11-dehydro-thromboxane B2 and NAD+ are 8.1, 8.0 and 23 microM, respectively. Subunit Mr was shown to be 55,000, whereas the native enzyme Mr was found to be 110,000 indicating that the enzyme is a dimer. The enzyme is sensitive to sulfhydryl inhibitions suggesting cysteine residues are essential to enzyme activity. The availability of a homogeneous enzyme preparation should allow further studies on the substrate specificity and the structure and function of the enzyme.
Animals↗
Primary amino acid sequence of alpha-trichosanthin and molecular models for abrin A-chain and alpha-trichosanthin.
Ricin A-chain, abrin A-chain, and alpha-trichosanthin are members of a larger group of proteins called ribosome-inactivating proteins. These proteins all function to catalytically inactivate eukaryotic 60 S ribosomal subunits leading to rapid shutdown of protein synthesis. They are homologous in sequence and are probably evolutionarily related. We have determined the complete primary amino acid sequence of alpha-trichosanthin and have found it to be homologous, as expected, to that of abrin A-chain and ricin A-chain. A crystal structure for ricin, which includes ricin A-chain and ricin B-chain, has been determined from x-ray diffraction data. Based on the sequence homologies of these proteins, we fit the primary sequences of abrin A-chain and alpha-trichosanthin to the backbone structure for ricin A-chain and have generated energy-minimized molecular models for them. These models should prove useful in studying the structural-functional relationships of these proteins in particular and of the class in general.
Abrin↗
The dose dependent effect of cyclic AMP on ribonucleotide reductase in mitogen stimulated mononuclear cells.
Cyclic adenosine monophosphate arrests proliferating T lymphocytes in the G1 phase of the cell cycle. Here we demonstrate that exogenous and endogenous elevations in cyclic AMP concentration result in diminished mitogen stimulation, cell cycle arrest, and decreased ribonucleotide reductase messenger RNA concentrations in peripheral blood mononuclear cells. At lower concentrations (less than 1mM) of dibutyryl cyclic AMP that do not generate cell cycle arrest there is inhibition of ribonucleotide reductase activity without decreased messenger RNA concentration for the M2 subunit of ribonucleotide reductase. However, at higher concentrations of dibutyryl cyclic AMP there is G1 cell cycle arrest and reduced M2 specific messenger RNA concentration. Thus, cyclic AMP inhibition of lymphocyte activation may occur by different mechanisms that are dose dependent.
4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
Immunologic reactivity against Borrelia burgdorferi in patients with motor neuron disease.
Of 19 unselected patients with the diagnosis of amyotrophic lateral sclerosis (ALS) living in Suffolk County, New York (an area of high Lyme disease prevalence), 9 had serologic evidence of exposure to Borrelia burgdorferi; 4 of 38 matched controls were seropositive. Eight of 9 seropositive patients were male (8 of 12 male patients vs 2 of 24 controls). Rates of seropositivity were lower among patients with ALS from nonendemic areas. All patients had typical ALS; none had typical Lyme disease. Cerebrospinal fluid was examined in 24 ALS patients--3 (all with severe bulbar involvement) appeared to have intrathecal synthesis of anti-B burgdorferi antibody. Following therapy with antibiotics, 3 patients with predominantly lower motor neuron abnormalities appeared to improve, 3 with severe bulbar dysfunction deteriorated rapidly, and all others appeared unaffected. There appears to be a statistically significant association between ALS and immunoreactivity to B burgdorferi, at least among men living in hyperendemic areas.
Adult↗
A glutathione conjugate of hepoxilin A3: formation and action in the rat central nervous system.
Incubation of (8R)- and (8S)-[1-14C]hepoxilin A3 [where hepoxilin A3 is 8-hydroxy-11,12-epoxyeicosa-(5Z,9E,14Z)-trienoic acid] and glutathione with homogenates of rat brain hippocampus resulted in a product that was identified as the (8R) and (8S) diastereomers of 11-glutathionyl hepoxilin A3 by reversed-phase high performance liquid chromatographic comparison with the authentic standard made by total synthesis. Identity was further confirmed by cleavage of the isolated product with gamma-glutamyltranspeptidase to yield the corresponding cysteinylglycinyl conjugate that was identical by reversed-phase high performance liquid chromatographic analysis with the enzymic cleavage product derived from the synthetic glutathionyl conjugate. The glutathionyl and cysteinylglycinyl conjugate are referred to as hepoxilin A3-C and hepoxilin A3-D, respectively, by analogy with the established leukotriene nomenclature. Formation of hepoxilin A3-C was greatly enhanced with a concomitant decrease in formation of the epoxide hydrolase product, trioxilin A3, when the epoxide hydrolase inhibitor trichloropropene oxide was added to the incubation mixture demonstrating the presence of a dual metabolic pathway in this tissue involving hepoxilin epoxide hydrolase and glutathione S-transferase processes. Hepoxilin A3-C was tested using intracellular electrophysiological techniques on hippocampal CA1 neurons and found to be active at concentrations as low as 16 nM in causing membrane hyperpolarization, enhanced amplitude and duration of the post-spike train afterhyperpolarization, a marked increase in the inhibitory postsynaptic potential, and a decrease in the spike threshold. These findings suggest that these products in the hepoxilin pathway of arachidonic acid metabolism formed by the rat brain may function as neuromodulators.
8,11,14-Eicosatrienoic Acid↗