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Carey RJ, Pinheiro-Carrera M, Dai H, Tomaz C, Huston JP. L-DOPA and psychosis: evidence for L-DOPA-induced increases in prefrontal cortex dopamine and in serum corticosterone. Biol Psychiatry 1995; 38:669-76. [PMID: 8555378 DOI: 10.1016/0006-3223(94)00378-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
L-DOPA can often induce psychotic reactions during treatment for Parkinson's disease. This study was undertaken to assess, in an animal model of Parkinson's disease, the impact of L-DOPA treatment on two potential biological risk factors for psychosis, namely, an increase in prefrontal cortex dopamine and an increase in the stress-related hormone corticosterone. Hemiparkinsonian rats with unilateral 6-hydroxydopamine (6-OHDA) lesions which resulted in severe unilateral denervation of dopamine neurons were treated with either saline or 25 mg/kg L-DOPA methyl ester (with 2 mg/kg carbidopa). Serum L-DOPA concentrations were found to be positively and highly correlated with serum corticosterone, with medial prefrontal cortex dopamine and with the dopamine metabolite homovanillic acid. Serum L-DOPA, however, was found not to be correlated with serum or brain concentrations of serotonin, 5-hydroxyindoleacetic acid, or norepinephrine. These findings support the possibility that chronic L-DOPA treatment can expose parkinsonian patients to two significant risk factors for psychosis: 1) increased levels of prefrontal cortex dopamine, and 2) increased levels of serum corticosterone.
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Affiliation(s)
- R J Carey
- State University of New York (SUNY) Health Science Center, USA
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202
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Wallace KK, Bao ZY, Dai H, Digate R, Schuler G, Speedie MK, Reynolds KA. Purification of crotonyl-CoA reductase from Streptomyces collinus and cloning, sequencing and expression of the corresponding gene in Escherichia coli. Eur J Biochem 1995; 233:954-62. [PMID: 8521864 DOI: 10.1111/j.1432-1033.1995.954_3.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A crotonyl-CoA reductase (EC 1.3.1.38, acyl-CoA:NADP+ trans-2-oxidoreductase) catalyzing the conversion of crotonyl-CoA to butyryl-CoA has been purified and characterized from Streptomyces collinus. This enzyme, a dimer with subunits of identical mass (48 kDa), exhibits a Km = 18 microM for crotonyl-CoA and 15 microM for NADPH. The enzyme was unable to catalyze the reduction of any other enoyl-CoA thioesters or to utilize NADH as an electron donor. A highly effective inhibition by straight-chain fatty acids (Ki = 9.5 microM for palmitoyl-CoA) compared with branched-chain fatty acids (Ki > 400 microM for isopalmitoyl-CoA) was observed. All of these properties are consistent with a proposed role of the enzyme in providing butyryl-CoA as a starter unit for straight-chain fatty acid biosynthesis. The crotonyl-CoA reductase gene was cloned in Escherichia coli. This gene, with a proposed designation of ccr, is encoded in a 1344-bp open reading frame which predicts a primary translation product of 448 amino acids with a calculated molecular mass of 49.4 kDa. Several dispersed regions of highly significant sequence similarity were noted between the deduced amino acid sequence and various alcohol dehydrogenases and fatty acid synthases, including one region that contains a putative NADPH binding site. The ccr gene product was expressed in E. coli and the induced crotonyl-CoA reductase was purified tenfold and shown to have similar steady-state kinetics and electrophoretic mobility on sodium dodecyl sulfate/polyacrylamide to the native protein.
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Affiliation(s)
- K K Wallace
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore MD, USA
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203
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Perl A, Colombo E, Dai H, Agarwal R, Mark KA, Banki K, Poiesz BJ, Phillips PE, Hoch SO, Reveille JD. Antibody reactivity to the HRES-1 endogenous retroviral element identifies a subset of patients with systemic lupus erythematosus and overlap syndromes. Correlation with antinuclear antibodies and HLA class II alleles. Arthritis Rheum 1995; 38:1660-71. [PMID: 7488288 DOI: 10.1002/art.1780381119] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To evaluate the correlation between the presence of antibodies to an endogenous retroviral element-encoded nuclear protein autoantigen, HRES-1, and the presence of other antinuclear antibodies and HLA class II alleles in patients with systemic lupus erythematosus (SLE) and overlap syndromes. METHODS Antibody reactivities to native and recombinant proteins and synthetic peptides were assessed by counterimmunoelectrophoresis, enzyme-linked immunosorbent assay, and Western blotting. HLA class II alleles were determined by oligonucleotide typing. RESULTS Forty-eight percent of the 153 patients with autoimmune disease, and 52% of the subgroup with SLE, had HRES-1 antibodies. In contrast, 3.6% of 111 normal donors, and none of 42 patients with the acquired immunodeficiency syndrome or 50 asymptomatic human immunodeficiency virus 1-infected patients, had HRES-1 antibodies. Chi-square analyses revealed a significant association between anti-HRES-1 and anti-RNP and an inverse correlation between HRES-1 and Ro/La autoantibodies in patients with SLE or overlap syndromes. Antigenic epitopes of HRES-1 and the retroviral gag-related region of the 70-kd protein component of U1 small nuclear RNP, which share 3 consecutive highly charged amino acids (Arg-Arg-Glu), an additional Arg, and functionally similar Arg/Lys residues, represent cross-reactive epitopes between the two proteins. Selective removal of HRES-1 antibodies from sera of HRES-1-seropositive/RNP-seropositive patients by absorption on recombinant HRES-1/glutathione-S-transferase-conjugated agarose beads had no effect on anti-RNP reactivities. A comparative multivariate analysis of HLA class II genes revealed a differential segregation of DQB1 alleles in HRES-1-seropositive versus HRES-1-seronegative patients (P = 0.04). While a relative increase of DQB1*0402 among HRES-1-seropositive patients was noted across ethnic groups (P = 0.02), a decrease of DQB1*0201 and DQB1*0301 was found in white HRES-1-seropositive patients (P = 0.04). CONCLUSION Autoantibodies to HRES-1 are detectable in a distinct subset of patients with autoimmune disease, primarily in those who do not have antibodies to Ro and La. Anti-HRES-1 and anti-RNP reactivities are mediated by cross-reactive but separate antibody molecules. HLA-DQB genes, rather than HLA-DRB or DQA genes, may have a more significant influence on generation of these antinuclear autoantibodies.
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Affiliation(s)
- A Perl
- SUNY Health Science Center, College of Medicine, Syracuse 13210, USA
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204
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Dai H, Krost M, Carey RJ. A new methodological approach to the study of habituation: the use of positive and negative behavioral indices of habituation. J Neurosci Methods 1995; 62:169-74. [PMID: 8750099 DOI: 10.1016/0165-0270(95)00073-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This report details a new method to measure habituation in an open-field. In addition to the measurement of spontaneous locomotor activity, time spent per visit to the center zone (CZ) is also measured. Critically, a small object is placed in the CZ to modulate an animal's investigatory response. When an animal is first exposed to the open-field, the presence of the object does not affect the duration of its visits to the CZ but, if the animal is given one additional 10-min exposure to the open-field, then the presence of the object substantially increases the duration of its visits to the CZ. The presence of the object, however, has no effect on the rat's locomotor activity. Thus, habituation could be observed by two different measures: a decrease in locomotor activity and an increase in an animal's investigatory response to a stimulus object. A basic problem with a reliance solely upon a decrease in locomotor activity to measure habituation is that it represents a negative change in behavior. The present method circumvents this shortcoming by incorporating a positive behavioral measure of habituation in conjunction with the measurement of locomotor activity. This modification of the open-field test offers substantial utility for studies of neurotoxicology and memory because one can assess concurrently treatment effects on motor activity, attention to an object and memory.
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Affiliation(s)
- H Dai
- VA Medical Center, Syracuse, NY, USA
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205
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Abstract
Plasma levels of interleukin-1 beta (IL-1 beta) were measured in 10 normal subjects, in 11 nondialyzed end-stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL-1 beta were 10.73 +/- 5.24 pg/ml, 9.97 +/- 3.61 pg/ml, 13.17 +/- 4.04 pg/ml, 15.16 +/- 6.16 pg/ml, and 13.96 +/- 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p > or = 0.05). In contrast, the gene expression of IL-1 beta for peripheral blood mononuclear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL-1 beta for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 +/- 1.07, 3.34 +/- 0.74, and 3.27 +/- 0.64%, respectively. The levels of IL-1 beta gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p < or = 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p > or = 0.05). We suggest measuring the gene expression of cytokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.
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Affiliation(s)
- J Qian
- Renal Division, Renji Hospital, Shanghai, China
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206
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Abstract
Expectation of signal duration influences the signal detectability. This is demonstrated in two experiments in which percent correct was measured for both tonal and noise signals whose durations were either unexpected or uncertain. In both experiments, the signal at each duration was set to have a d' of about 1.5 when that duration was presented alone and expected. When the six subjects were led to expect a short- or a long-duration signal using the probe-signal method, the detectability of signals decreased to near chance as the signal duration deviated from the expected value (experiment 1). When the subjects were led to expect a range of durations, the detectability was only slightly worse than when each signal was presented alone (experiment 2). Those results suggest that listeners adjust their temporal-integration intervals according to the demand of the specific task. Finally, the results obtained with the noise signal were analyzed using the multiple-look model and a modified energy-detector model. Assuming that the integration interval is matched to the expected signal duration, both models predict the detection of signals having unexpected durations reasonably well. Both models, however, fail to predict the small effect of duration uncertainty.
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Affiliation(s)
- H Dai
- Department of Psychology, University of Florida, Gainesville 32611, USA
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207
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Abstract
Antagonism of the NMDA receptor with MK-801 is considered to be an effective pharmacologic manipulation to prevent the development of sensitization effects to drugs such as cocaine. The present study investigated this issue by comparing the behavioral response of separate groups of rats to three treatment cycles of either saline, 0.1 mg/kg MK-801, 10 mg/kg cocaine, or combined MK-801-cocaine (0.1/10 mg/kg). The treatments were spaced 1 week apart and were preceded by two nondrug baseline tests. In the first test cycle, the four groups had equivalent activity levels in the two nondrug tests. In the first drug test only the MK-801-cocaine group exhibited hyperactivity. By the third drug test, the MK-801-cocaine group exhibited an enhanced hyperactivity and the MK-801 group became hyperactive. Thus, behavioral drug sensitization developed but only with groups treated with MK-801. Antagonism of the NMDA receptor under some circumstances can be a highly effective treatment for the induction of behavioral sensitization effects.
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Affiliation(s)
- R J Carey
- SUNY Health Science Center, Syracuse, USA
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208
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Dai H, He Z. [Use of perfluorodecalin in giant retinal tear retinal detachment surgery]. Zhonghua Yan Ke Za Zhi 1995; 31:259-61. [PMID: 8745516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Perfluorodecalin is used for the treatment of 11 eyes with giant retinal tear retinal detachment surgery. Perfluorocarbon liquids can be used as an operative hydrodynamic tool during vitreous surgery. The high specific gravity of perfluorocarbon liquids allows an easy unfolding of the inverted flap and flattening of the retina, displacing the subretinal fluid and stabilizing the retina for membrane peeling. Endophotocoagulation may be performed under optimal visual condition. The success rate was 81.8% (9/11). The retina failed to reattach in patients with advanced proliferative vitreoretinopathy. The surgical techniques were discussed.
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Affiliation(s)
- H Dai
- Department of Ophthalmology, Beijing Hospital
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209
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210
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Arora K, Dai H, Kazuko SG, Jamal J, O'Connor MB, Letsou A, Warrior R. The Drosophila schnurri gene acts in the Dpp/TGF beta signaling pathway and encodes a transcription factor homologous to the human MBP family. Cell 1995; 81:781-90. [PMID: 7774017 DOI: 10.1016/0092-8674(95)90539-1] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Decapentaplegic (dpp), a TGF beta-related ligand, plays a key role in Drosophila development. Although dpp receptors have been isolated, the downstream components of the signaling pathway remain to be identified. We have cloned the schnurri (shn) gene and show that it encodes a putative zinc finger transcription factor homologous to the human major histocompatibility complex-binding proteins 1 and 2. Mutations in shn affect multiple events that require dpp signaling as well as the transcription of dpp-responsive genes. Genetic interactions and the strikingly similar phenotypes of mutations in shn and the dpp receptors encoded by thick veins and punt suggest that shn plays a downstream role in dpp signaling.
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Affiliation(s)
- K Arora
- Department of Molecular Biology and Biochemistry, University of California, Irvine 92717, USA
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211
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Abstract
This study examined the ability of trained listeners to discriminate coherent components in randomly varying spectral patterns. In each observation interval, the listener was presented with a sequence of bursts of multitone complexes having a fixed number of tones (m) in each burst. In the standard interval, the frequency of each tone in every burst was chosen randomly between 200 and 5000 Hz. In the signal interval, the frequencies of n tones were repeated throughout the burst sequence while the remaining m-n tones were chosen at random. The n tones were coherent in the sense that they were perceived as "sticking together" to form a pattern. The listener's task was to discriminate which burst sequence contained the n components. The results indicated that discrimination improved with increasing n/m, with increasing number of bursts per interval, and declined as the coherent components were increasingly perturbed in frequency. Further, for a fixed value of the ratio n/m discriminability was relatively independent of m. A model incorporating multichannel filtering and an optimum decision rule was reasonably successful in accounting for the experimental results.
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Affiliation(s)
- G Kidd
- Department of Communication Disorders, Boston University, Massachusetts 02215, USA
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212
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Dai H, Lo YS, Wang TS, Chiang KS. Variation in protein and RNA synthesis activity in isolated mitochondria of the developing rice (Oryza sativa L.) panicle. Theor Appl Genet 1995; 90:1112-1118. [PMID: 24173071 DOI: 10.1007/bf00222930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/1994] [Accepted: 08/18/1994] [Indexed: 06/02/2023]
Abstract
We have studied variation in mitochondrial protein and RNA synthesis during the development of a specialized rice (Oryza sativa L.) reproductive organ in a bacteria-free environment. Mitochondria were prepared from the maturing panicle during microsporogenesis when meiosis occurred and from etiolated seedlings at two growth stages. We found (1) that there was no discernible qualitative difference among the polypeptides synthesized by these three mitochondrial samples; (2) that the quantity of proteins synthesized by panicle mitochondria was approximately 3 times that of the seedling mitochondria, while the two seedling samples exhibited only a minor quantitative difference; (3) that panicle and seedling mitochondria samples synthesized qualitatively the same RNA but at distinctly different rates and that more RNA products were synthesized by panicle than by seedling mitochondria. These results, taken together, suggest that either the regulation of mitochondrial transcription and translation or the copy number of mitochondrial DNA per mitochondrion change discretely in the developing panicle and consequently that the level of mitochondrial gene expression increases considerably during the development of the reproductive structure in rice.
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Affiliation(s)
- H Dai
- Institute of Botany, Academia Sinica, Taipei, Taiwan 11529 ROC
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213
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Abstract
In this paper, we explore a two-filter model, the simplest version of multi-channel models for frequency discrimination of simple tones. According to this model, frequency discrimination is based on a change in the relative output levels of two auditory filters, one centered below and the other above the frequency of the tone. This idea can explain the experimental results that frequency discrimination is relatively unaffected by randomization of stimulus level. Moreover, it suggests a close relationship between the ability of listeners to perform frequency discrimination of simple tones and spectral-shape discrimination of two-tone complexes. The ability of three listeners to perform these two tasks was measured at six frequencies (from 0.25 to 8 kHz). The results from the spectral-shape-discrimination task were used to predict frequency-difference limens. There was a high correlation between obtained and predicted values.
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Affiliation(s)
- H Dai
- Department of Psychology, University of Florida, Gainesville 32611, USA
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214
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Carey RJ, Dai H, Huston JP, Pinheiro-Carrera M, Schwarting RK, Tomaz C. L-DOPA metabolism in cortical and striatal tissues in an animal model of parkinsonism. Brain Res Bull 1995; 37:295-9. [PMID: 7627573 DOI: 10.1016/0361-9230(95)00019-b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Rats with unilateral 6-hydroxydopamine lesions of the midbrain tegmentum were treated with 25 mg/kg L-DOPA methyl ester/2 mg/kg carbidopa. The effects of the L-DOPA treatment upon serum, neocortical, and striatal L-DOPA and 3-O-methyl dopa (3-OMD) concentrations were measured. The highest L-DOPA and 3-OMD concentrations were obtained in the serum and in a ratio of approximately 2:1. In the brain, there was a uniform distribution of 3-OMD but L-DOPA concentrations were highly nonhomogeneous. Regression line equations for the statistically significant correlation coefficients between L-DOPA and tissue dopamine concentrations suggested that L-DOPA generated 50-60 times as much dopamine in the intact striatum as in cortex. The regional variation of L-DOPA concentration appears related to the capability of the brain tissue to generate and store dopamine from L-DOPA. In addition, the findings suggest that the behavioral ineffectiveness of L-DOPA in intact animals is related to its capacity to transform L-DOPA to tissue bound dopamine.
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Affiliation(s)
- R J Carey
- Research and Development Service, VA Medical Center, Syracuse, NY 13210, USA
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215
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Abstract
Separate groups of rats were given saline or MK-801 treatments (0.3 mg/kg) and tested for locomotion activity levels for 10 min at 30, 60, and 120 min postinjection. At each postinjection time interval the MK-801 rats exhibited a marked hyperactivity that was unchanged across the three postinjection intervals. Ex vivo biochemical assays were performed to assess the neurochemical effects of MK-801 at each injection interval. In the striatum, a marked increase in dopamine metabolism was observed in the 120 injection group, but, otherwise, no other changes in striatum were detected. In contrast, a significant increase in dopamine metabolism was observed after 30 min in the medial prefrontal cortex, and this effect persisted across all postinjection intervals. At 120 min, however, the biochemical impact of the MK-801 treatment on medial prefrontal cortex broadened to include a decrease in purine metabolism and norepinephrine. Serotonin metabolism was unaffected in striatum or medial prefrontal cortex across all injection intervals, and there was no effect of MK-801 on plasma corticosterone levels.
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Affiliation(s)
- H Dai
- SUNY Health Science Centerm Syracuse
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216
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Fornaguera J, Carey RJ, Dai H, Huston JP, Schwarting RK. Differentiation of motor inactivation from movement asymmetry effects in an animal model of hemi-parkinsonism. Neuroreport 1994; 6:173-6. [PMID: 7703408 DOI: 10.1097/00001756-199412300-00044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Rats subjected to unilateral 6-hydroxydopamine lesion of the pars compacta of the substantia nigra sustained a wide range of dopamine (DA) loss in the neostriatum. Residual DA levels of < 50% resulted in behavioural impairments which correlated with the degree of DA denervation, whereas no such effects occurred with residual DA levels of > 50%. Within 1 week after surgery the effects of the lesion on motor activation recovered whereas movement asymmetrics exhibited no recovery. In addition, movement asymmetry effects were not correlated with motoric inactivation effects. This finding indicates that dopamine denervation of the neostriatum disrupts sensory/motor integration and attentional processes rather than motor activation.
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Affiliation(s)
- J Fornaguera
- Institute of Physiological Psychology I, University of Düsseldorf, Germany
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217
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Abstract
Rats treated with 10 mg kg-1 cocaine exhibited hyperlocomotion. Individual variation in the magnitude of this response was not correlated with serum cocaine concentration. Brain cocaine concentration, particularly in the medial prefrontal cortex, was highly correlated with the cocaine-induced locomotor stimulant effect. These findings indicate that variation in the uptake of cocaine into the brain is a critical variable in determining individual variation in its stimulant effects.
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Affiliation(s)
- R J Carey
- SUNY Health Science Center, Syracuse
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218
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Frlan E, Wight JS, Janz S, Dai H, Chatenoud F, Buchanan M, Normandin R. High-resolution surface-emitting spectrometer and deformation sensors with nonlinear waveguides. Opt Lett 1994; 19:1657-1659. [PMID: 19855613 DOI: 10.1364/ol.19.001657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigate the limits of frequency resolution attainable in a nonlinear waveguide optical spectrometer, including the effects that are due to surface distortions and waveguide inhomogeneities, and demonstrate that the frequency-resolving capability is directly scalable with the radiating aperture length. The resolution of the waveguide is diffraction limited, and therefore the far-field radiation pattern can be used to characterize the phase variations along the waveguide that are due to surface distortions. The use of this device as a highly sensitive deformation sensor is demonstrated by application of a distortion to the waveguide and confirmation of the far-field diffraction pattern generated.
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219
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Dai H, Yoon S, Liu J, Budhani RC, Lieber CM. Simultaneous Observation of Columnar Defects and Magnetic Flux Lines in High-Temperature Bi
2
Sr
2
CaCu
2
O
8
Superconductors. Science 1994; 265:1552-5. [PMID: 17801531 DOI: 10.1126/science.265.5178.1552] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Columnar defects generated by heavy-ion irradiation are promising structures for pinning magnetic flux lines and enhancing critical currents in superconductors with high transition temperatures. An approach that combines chemical etching and magnetic decoration was used to highlight simultaneously the distributions of columnar defects and magnetic flux lines in Bi(2)Sr(2)CaCu(2)O(8) superconductors. Analyses of images of the columnar defects and flux-line positions provide insight into flux-line pinning by elucidating (i) the occupancy of columnar defects by flux lines, (ii) the nature of topological defects in the flux-line lattice, and (iii) the translational and orientational order in this lattice.
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220
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Abstract
Psychometric functions were measured for spectral-shape discrimination (profile analysis) with the signal frequency either fixed, what we call the signal-known condition, or randomly varied, what we call the signal-unknown condition. The functions were obtained using an adaptive, up-down procedure. In the signal-unknown condition, independent tracks for each signal frequency were interleaved within the same block of trials. The mean slope of the psychometric function [k in log d' = k log delta L+C, where delta L = 20 log(1 + delta p/p)] was 1.13 for the signal-known conditions and 1.19 for the signal-unknown condition. The mean signal-to-standard ratio at threshold (Pc = 79.4%) obtained in the signal-unknown condition was 3 to 4 dB higher than that obtained in the signal-known conditions. The psychometric functions of the ideal observer were derived for both the signal-known and signal-unknown conditions. A comparison of the measured and derived psychometric functions suggests that the internal noise component that is statistically independent across frequency channels contributes minimally to the total (internal and external) noise sources that are involved in the decision process.
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Affiliation(s)
- H Dai
- Department of Psychology, University of Florida, Gainesville 32611
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221
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Abstract
Rats with unilateral 6-hydroxydopamine (6-OHDA) lesions were exposed to L-DOPA treatments, 25 mg kg-1 L-DOPA methyl ester/2 mg kg-1 carbidopa, or to saline. Fourteen days later, both sets of animals were tested with the L-DOPA/carbidopa treatment. The L-DOPA pre-exposed animals exhibited behavioral sensitization as indexed by a higher frequency of contralateral rotations. Although striatal L-DOPA and HVA concentrations were equivalent in the two groups, the L-DOPA treatment induced a 10 fold variation in the range of L-DOPA concentrations in the 6-OHDA striatum in both sets of animals. Importantly, significant correlations between striatal L-DOPA concentration and behavior were obtained only for the L-DOPA pre-exposed animals.
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222
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Abstract
To assess whether the interval between injections affects the course of locomotor sensitization to quinpirole, groups of rats were injected every 2, 4, or 8 days with quinpirole (0, 0.025, 0.25, 0.5, and 2.5 mg/kg; n = 222) and their locomotor activity monitored after each injection for a total of 10 tests. Results indicate that the number of drug injections, rather than the interval between them, predominantly controls the development of locomotor sensitization to quinpirole. It is suggested that this may reflect a rapid induction but slow decay time for a response-enhancing factor stimulated by each injection of quinpirole, and that the effects of this putative factor are cumulative but saturable.
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Affiliation(s)
- H Szechtman
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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223
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Yoon S, Dai H, Liu J, Lieber CM. Surface Pinning as a Determinant of the Bulk Flux-Line Lattice Structure in Copper Oxide Superconductors. Science 1994; 265:215-8. [PMID: 17750661 DOI: 10.1126/science.265.5169.215] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Direct knowledge of crystal defects and their perturbation of magnetic flux lines is essential to understanding pinning and to devising approaches that enhance critical currents in superconductors with high critical temperatures (T(c)). Atomic force microscopy was used to simultaneously characterize crystal defects and the magnetic flux-line lattice in single crystals of Bi(2)Sr(2)CaCu(2)O(8). Images show that surface defects, which are present on all real samples, pin the flux-line lattice. Above a critical height, the pinning interaction is sufficiently strong to form grain boundaries in the bulk flux-line lattice. These results elucidate the structure of the defects that pin flux lines and demonstrate that surface pinning, through the formation of grain boundaries, can determine the bulk flux-line lattice structure in high-T(c) materials. The implications of these results to the bulk flux-line lattice structure observed in previous experiments and to enhancing critical currents are discussed.
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224
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Abstract
A new method was developed to measure locomotion and attention to a stimulus object in a typical open-field environment using a video image-analyzer system. A computer-generated central zone (CZ) composing 1/9 of the open-field floor area was monitored independently from the rest of the area. Intermittently, a 4 x 4 x 2 cm object was placed in the CZ. In 10 min test sessions, the presence of the object repeatedly and consistently increased the animal's time spent in the CZ as compared with tests when the object was absent. The presence of the object, however, did not increase either the number of entries to the CZ or overall locomotor activity. The object reliably elicited an investigatory response when the animal enter the CZ but otherwise was behaviorally neutral. Thus, by incorporating a stimulus object in a conventional open-field test environment, the present methodology extends the open-field test beyond the measurement of overall spontaneous activity to include an assessment of behavioral processes linked to attention mechanisms.
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Affiliation(s)
- H Dai
- VA Medical Center, Syracuse, NY
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225
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Abstract
Using a modified open-field method, we assessed the effects of MK-801 (0.01 to 0.3 mg/kg) on locomotion and on attention to a stimulus object located in a computer-generated central zone (CZ). The CZ comprised 1/9 of the open-field floor area and was monitored independently from the rest of the area. Intermittently, a 4 x 4 x 2 cm block was placed in the CZ. In 10-min trials, non-drug tests showed that the presence of the stimulus object repeatedly and consistently increased the rats' visit duration in the CZ as compared with tests when the object was absent. Locomotor activity and entries to the CZ were unaffected by the object. MK-801 induced dose dependent hyperlocomotion and increased CZ entries and, most important, a dose dependent decrease in the animal's response to the stimulus object in the CZ. The present investigation suggests that MK-801 impacts upon two major functions; (a) a blockade of processing of attentional information from the external world and (b) activation of locomotor response systems. These findings are consistent with the hypothesis that blockade of glutamate neurotransmission by MK-801 impairs the flow of information from the external world to response mechanisms in the striatum. The present study also suggests that MK-801's potential as a therapeutic agent for motoric activation in the treatment for Parkinson's disease would be contraindicated by its disruptive influence upon attention processing functions.
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Affiliation(s)
- H Dai
- VA Medical Center, Syracuse, NY 13210
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226
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Szechtman H, Talangbayan H, Canaran G, Dai H, Eilam D. Dynamics of behavioral sensitization induced by the dopamine agonist quinpirole and a proposed central energy control mechanism. Psychopharmacology (Berl) 1994; 115:95-104. [PMID: 7862919 DOI: 10.1007/bf02244757] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The study characterizes the process of sensitization induced by intermittent administrations of quinpirole (0.5 mg/kg) in rats in a large open field. Sensitization was found to be self-limiting, with all measures of behavior reaching a plateau after the tenth twice-weekly injection. Kinetics of sensitization were a simple hyperbolic function of the number of drug injections for some measures (speed of locomotion, length of locomotor bouts) but showed positive co-operativity for others (distance travelled, duration of locomotion, frequency of stops, route stereotypy), suggesting potentiation of the effect by preceding injections. The pace of sensitization varied for different behaviors: locomotor speed changed fastest in the early portion of chronic treatment; stereotypy of route changed primarily during the late phase; mouthing did not sensitize. Sensitization evolved by a cascade of changes that included: advancing the onset of locomotor activation; prolonging the duration of locomotion; establishing new maxima of observable responses; altering the mode of locomotion; raising speed, rate and length of locomotor bouts; and increasing stereotypy of travel. These observations do not substantiate the prediction that development of behavioral sensitization is associated with emergence of disorganized activity and/or fractionation of response chains. Instead, it is proposed that development of sensitization may represent a build-up and strengthening of performance, reflecting enhanced central control of energy expenditure stimulated by repeated injections of quinpirole. Furthermore, it is suggested that for at least one response, the maximum observable amount of locomotion, development of sensitization requires only D2 stimulation, independent of D1 tone.
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Affiliation(s)
- H Szechtman
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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227
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Dai H, He ZP. [Treatment of macular hole retinal detachment with vitrectomy]. Zhonghua Yan Ke Za Zhi 1994; 30:204-6. [PMID: 7843002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pars plana vitrectomies were performed on 64 eyes with macular hole retinal detachment of which 20 with severe proliferative vitreoretinopathy (PVR C-D) and 18 with definite vitreoretinal traction on the maculae were found. Retinal reattachment occurred in 57 eyes in the follow-up (89.1%) of which the visual acuities improved in 43 (74.5%), unchanged in 13 and decreased in 1. The points for attention in the operation were discussed. The key factors influencing the success of the operation are severe PVR, the course of the retinal detachment.
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Affiliation(s)
- H Dai
- Department of Ophthalmology, Beijing Hospital
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228
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Zou G, Li W, Gan Q, Zou L, Xu J, Cai M, Wei J, Lei J, Dai H. [A new species of Pseudomonas]. Wei Sheng Wu Xue Bao 1994; 34:96-9. [PMID: 8073766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A strain No. 9191 isolated from fruit juice mineral drink is gram-negative short-rod. It differs from reported species of Pseudomonas in morphological, physiological and biochemical characteristics. Main characteristics of No. 9191 are single polar flagelled, oxidase and catalase positive, no acid from glucose but producing alkali, nitrate reduced to nitrite, inability to hydrolize gelatin and starch, arginine dihydrolase absent, no growth in presence of 0.85% NaCl. The G+C mol% of DNA is 65.15. It is named Pseudomonas halosensibilis Zou & Cai nov. sp. by the sensibility property for salt.
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Affiliation(s)
- G Zou
- Nanchang Sanitary & Anti-epidemic Station
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229
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Abstract
The detectability of short and long unexpected tones masked by a continuous wideband noise was assessed using a probe-signal method. This method leads the listener to expect a target frequency by presenting the signal most often at that frequency, and only occasionally at other unexpected probe frequencies. The probe-signal contour (percent correct as a function of probe frequency) was considerably broader with 5-ms than with 295-ms signals. However, auditory filter shapes measured using the notched-noise technique were very similar for those two signal durations, indicating that the results obtained in the probe-signal conditions do not simply reflect peripheral frequency selectivity. Further supporting this interpretation, probe tones having the same frequency but a different duration from the target were poorly detected. It is proposed that the subject listens through a time-frequency window whose location and shape in the time-frequency plane is determined by the duration and frequency of the target.
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Affiliation(s)
- B A Wright
- Department of Psychology, University of Florida, Gainesville 32611
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230
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Abstract
The effect of gating a wideband masker on the detectability of tones having unexpected frequencies was assessed using a probe-signal method. This method leads the listener to expect a target frequency by presenting the signal most often at that frequency, and measures sensitivity to other unexpected frequencies via occasionally presented probe tones. For 295-ms signals, the probe-signal contours (percent correct as a function of probe frequency) of two of four subjects were considerably broader for a 295-ms masker than for a continuous masker. For 5-ms signals, the probe-signal contours of four of five subjects were quite broad and similar for both gated and continuous maskers. When the probe-signal contours were expressed as the attenuation in decibels of the probes, the resulting "probe-signal filters" were frequently broader than auditory filters measured using notched noise in the same subjects. This suggests that subjects may monitor multiple auditory filters under some conditions in the probe-signal task. Signal threshold tended to be higher for conditions showing wider probe-signal filters, indicating a potential link between changes in signal threshold due to masker gating and the number of frequency channels that are monitored.
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Affiliation(s)
- B A Wright
- Department of Psychology, University of Florida, Gainesville 32611
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231
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Dai H, Liu J, Lieber CM. Surface pinning and grain boundary formation in magnetic flux-line lattices of Bi2Sr2CaCu2O8+ delta high-Tc superconductors. Phys Rev Lett 1994; 72:748-751. [PMID: 10056513 DOI: 10.1103/physrevlett.72.748] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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232
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Pinheiro-Carrera M, Tomaz C, Huston JP, Dai H, Carey RJ. L-dopa induced increases in brain uric acid in an animal model of Parkinson's disease: a relationship to behavioral activation. Life Sci 1994; 55:991-7. [PMID: 8084215 DOI: 10.1016/0024-3205(94)00633-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Rats with severe unilateral dopamine denervation (> or = 95% dopamine deficit), produced by intracerebral injection of 6-hydroxydopamine (6-OHDA) into the ventral tegmentum nigrostriatal dopamine neurons, were administered 25 mg/kg L-dopa (3,4-dihydroxyphenylalanine) methyl ester/2 mg/kg carbidopa. The neurochemical effects of the L-dopa treatment on uric acid in the cortex and striatum of the intact and 6-OHDA hemisphere were measured. In comparison to saline animals, uric acid concentrations in brain were increased in the L-dopa treated animals. There were no interhemispheric differences in the uric acid concentrations either in the L-dopa or in the saline treated animals. Interhemispheric differences were, however, observed in terms of the correlations obtained between L-dopa and uric acid concentrations in the intact vs. the 6-OHDA hemisphere. Statistically significant correlation coefficients were found in the striatal and cortex samples obtained from the 6-OHDA hemisphere. Furthermore, high correlation coefficients were observed between contralateral rotation frequencies and uric acid concentrations in the cortex and striatum of the 6-OHDA hemisphere. In contrast, only low and statistically non significant correlations were observed in the tissue samples obtained from the intact hemisphere. These observations suggest that L-dopa activation of the dopamine supersensitive receptors of the DA denervated hemisphere and the associated metabolism of purines with high energy phosphate bonds (e.g. ATP and GTP) increases uric acid as an end-product of purine metabolism. These findings are consistent with other findings indicating that uric acid in the brain can provide an index of metabolic activation in brain tissue.
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233
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Dai H, Normandin R, Janz S, Chatenoud F, Delage A. Design optimization of multilayer nonlinear antiresonant waveguides for blue - green surface normal second-harmonic generation. Opt Lett 1993; 18:2005. [PMID: 19829473 DOI: 10.1364/ol.18.002005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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234
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Abstract
In studies of auditory profile analysis [D. M. Green, Profile Analysis: Auditory Intensity Discrimination (Oxford U. P., New York, 1988)], the sounds are presented at random levels to discourage the listener from basing the discrimination on a difference in absolute level rather than on a difference in the shape of the spectrum. A difference in absolute level, however, can still provide an effective discrimination cue if the difference is comparable to the range of randomization. Using enormous ranges of random levels is not desirable, because it is distracting to normal listeners and may exceed the dynamic range of hearing for listeners with hearing loss. This article describes a new experimental procedure which permits the experimenter to greatly reduce the range of level randomization in roving-level tasks.
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Affiliation(s)
- G Kidd
- Department of Psychology, University of Florida, Gainesville 32611
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235
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Abstract
The predictions of two models for the pitch of two-tone complexes were compared to pitch matching results obtained in a previous study [Feth, O'Malley, and Ramsey, J. Acoust. Soc. Am. 72, 1403-1412 (1982)] and the present study. In one model, the pitch value of a waveform was calculated from the envelope-weighted average of instantaneous frequency of the waveform (the EWAIF model). In the other model, the pitch value was calculated from the squared-envelope-weighted average of instantaneous frequency (the SEWAIF model). The SEWAIF model better predicts the data.
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Affiliation(s)
- H Dai
- Department of Psychology, University of Florida, Gainesville 32611
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236
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Janz S, Fernando C, Dai H, Chatenoud F, Dion M, Normandin R. Quasi-phase-matched second-harmonic generation in reflection from AlxGa1-xAs heterostructures. Opt Lett 1993; 18:589. [PMID: 19802209 DOI: 10.1364/ol.18.000589] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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237
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Dai H, Lo YS, Charn CG, Ruddat M, Chiang KS. Characterization of protein synthesis by isolated rice mitochondria. Theor Appl Genet 1993; 86:312-316. [PMID: 24193475 DOI: 10.1007/bf00222094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/1992] [Accepted: 11/03/1992] [Indexed: 06/02/2023]
Abstract
Bacteria-free mitochondria were isolated from aseptically grown, etiolated and green seedlings of both cytoplasmic male-sterile (WA-type) and male-fertile rice (Oryza sativa L.). Protein synthesis in these isolated mitochondria was characterized by gel electrophoresis/fluorography and by the incorporation of [(35)S]-methionine into protein. In the presence of cycloheximide, a set of some 25 discrete polypeptides and an electrophoretically unresolved population were synthesized. This pattern of protein synthesis in organello was essentially the same in mitochondria isolated from both male-fertile and malesterile cytoplasms. Our data does not preclude the possibility, however, that the WA-type CMS possesses a tissue-specific and/or a low abundance mitochondrial protein(s), whose synthesis eluded detection under our experimental conditions. The synthesis of the mitochondria-encoded polypeptides by isolated rice mitochondria was inhibited by chloramphenicol and incompletely inhibited by erythromycin. A minor chloramphenicol-insensitive, cycloheximide-sensitive translation activity was found consistently to copurify with the mitochondria. This activity generated a reproducible electrophoretic profile of a poorly resolved, weakly labelled population of polypeptides and of a few conspicuous polypeptides, including a 42 kDa species.
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Affiliation(s)
- H Dai
- Institute of Botany, Academia Sinica, Taipei, Taiwan 11529, Peoples Republic of China
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238
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Abstract
Thresholds for discriminating the changes in the spectral shape of simultaneously presented components (profile analysis) are measured as a function of stimulus duration for various complex stimuli. For all stimuli, the threshold decreases with increasing duration until a transition time is reached, and thereafter the threshold remains constant. The amount of change in threshold and the value of transition time appear to be greater for complexes having narrower frequency spacing of the components. The results can be accounted for, at least qualitatively, by assuming that the bandwidth of the auditory filters decreases after the onset of the stimulus.
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Affiliation(s)
- H Dai
- Department of Psychology, University of Florida, Gainesville 32611
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239
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240
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Janz S, Frlan E, Dai H, Chatenoud F, Normandin R. Coherent phase and frequency detection by using sum-frequency mixing in nonlinear waveguides. Opt Lett 1992; 17:1718-1720. [PMID: 19798295 DOI: 10.1364/ol.17.001718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate a novel optical phase detector that uses sum-frequency mixing in a nonlinear waveguide. By monitoring the near-field pattern of the sum-frequency light radiated from the waveguide surface, the relative phase of two input light beams can be measured. By using an Al(x)Ga(1-x)As waveguide optimized for sum-frequency generation with lambda = 1.06 microm input light, we demonstrate a simple phase detector capable of resolving phase shifts of less than 0.2 rad. This phase detector is also used in an interferometer configuration as a gigahertz-resolution frequency monitor.
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241
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242
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Abstract
This study measures the ability of observers to compare the intensities of two stimuli occupying different frequency regions. It includes three experiments, each experiment having two conditions. In one condition, the two stimuli to be compared were presented simultaneously within each interval; this condition has been called profile analysis. In the other condition, the two stimuli were presented successively within each interval. Because the overall level of the stimuli was randomized between intervals, the observers were encouraged to compare the intensities of the two stimuli within each observation interval rather than between intervals. The stimuli were two simple tones in experiment 1 and two tonal complexes in both experiments 2 and 3. The stimuli used in experiments 2 and 3 differed in frequency. The results show that simultaneous comparisons are superior to successive comparisons. For simple tones, the difference in threshold is about 8 dB; for complexes with 10 to 11 components, the difference in threshold is about 15 dB. These differences can be explained by assuming that internal noises in different channels were partially correlated when stimuli in those channels were presented simultaneously and were independent when the stimuli were presented successively. Cancellation of the correlated noise is therefore possible with simultaneous comparisons, making such discrimination better than that achievable with successive comparisons.
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Affiliation(s)
- H Dai
- Department of Psychology, University of Florida, Gainesville 32611
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243
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Urbach LE, Percival KL, Hicks JM, Plummer EW, Dai H. Resonant surface second-harmonic generation: Surface states on Ag(110). Phys Rev B Condens Matter 1992; 45:3769-3772. [PMID: 10001961 DOI: 10.1103/physrevb.45.3769] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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244
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245
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Dai H, Deng H, He X, Li L, Xia J. [RFLPs study of parental origin and mechanism of 3 cases with X chromosome structural abnormality]. Yi Chuan Xue Bao 1992; 19:298-303. [PMID: 1361346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
In this study, we analysed the parental origin and mechanism of X chromosome abnormalities in 3 cases by using RFLPs on short or long arm of X chromosome as genetic markers. Their karyotypes were 46,X,dup(X)(p21); 46,X,del(X)(p11); 46,X,i(Xq). The results demonstrated that the dup(X)(p21) and the del(X)(p11) were of paternal origin and i(Xq) was of maternal origin. The dup(X)(p21) arose from an unequal sister chromatid exchange. The del(X) (p11) occurred through X chromosome breakage and deletion mechanism. The i(Xq) resulted from X chromosome centromere misdivision in oocyte.
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Affiliation(s)
- H Dai
- State Key Laboratory of Medical Genetics of China, Hunan Medical University, Changsha
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246
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Yin YL, Hunan R, Zhong H, Chen CM, Dai H. Influence of different cannulation techniques on the pre-caecal digestibility of protein, amino acids and cell wall constituents from diets, containing different protein meals, in pigs. Anim Feed Sci Technol 1991. [DOI: 10.1016/0377-8401(91)90133-d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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247
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Dai H, Stafsudd OM, Dunn B. Measurement of stimulated emission cross section and fluorescence branching ratio for Nd(3+) in sodium-beta'' alumina. Appl Opt 1991; 30:4330-4336. [PMID: 20717204 DOI: 10.1364/ao.30.004330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Room-temperature measurements of laser emission cross sections of Nd(3+) ion in sodium-beta" alumina at 1.06 and 1.35 microm as well as the fluorescence branching ratios of (4)F(3/2) to (4)I(j) manifolds are reported. A theoretical calculation based on absolute absorption measurements when a modified Judd-Ofelt phenomenological intensity analysis was used is reported. The cross sections thus determined are sigma(1.06) = 3.1 +/- 0.3 x 10(-20) cm(2) and sigma(1.35) = 0.6 +/- 0.1 x 10(-20) cm(2), respectively. The emission cross section at 1.06 microm was also determined by small-signal-gain measurements and was found to be in good agreement with the above value.
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248
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Dai H, Chen H, Lieber CM. Weak pinning and hexatic order in a doped two-dimensional charge-density-wave system. Phys Rev Lett 1991; 66:3183-3186. [PMID: 10043720 DOI: 10.1103/physrevlett.66.3183] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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249
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Dai H, Lo YS, Wu CY, Tsou CL, Hsu GS, Chern CG, Ruddat M, Chiang KS. Protein Synthesis in Isolated Mitochondria of Rice (Oryza sativa L.) Seedlings. Plant Physiol 1991; 96:319-23. [PMID: 16668173 PMCID: PMC1080754 DOI: 10.1104/pp.96.1.319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
For studies of in organello mitochondrial protein synthesis in rice, Oryza sativa L., conventional surface-sterilization procedures were demonstrated to be ineffective. Because of the over-whelmingly efficient [(35)S]methionine utilization by contaminating bacteria, even "essentially bacteria-free" rice mitochondria were shown to be unsuitable for the study of in organello protein synthesis. We developed a procedure to obtain a bacteria-free preparation of rice mitochondria. Such mitochondria favored a membrane-dependent ATP-generating system over an external ATP-generating system as the energy supplement for in organello protein synthesis. Two distinct classes of [(35)S]methionine-labeled, cycloheximide-insensitive products were detected: an electrophoretically unresolved population and a set of some 22 to 27 discrete polypeptide species, each with a characteristic electrophoretic mobility and relative abundance.
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Affiliation(s)
- H Dai
- Institute of Botany, Academia Sinica, Taipei, Taiwan, Republic of China
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250
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