A thermal view of the arterial wall after coronary angioplasty.
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Angioplasty, Balloon, Coronary↗
Biomedical subjects
X Liu
Publications and source records attributed to X Liu.
Asbestos related diseases from environmental exposure to crocidolite in Da-yao, China. I. Review of exposure and epidemiological data.
BACKGROUND: Scattered patches of crocidolite, one form of asbestos, were found in the surface soil in the rural county of Da-yao in southwestern China. In 1983, researchers from the West China University of Medical Sciences (WCUMS) discovered that residents of two villages in Da-yao had hyperendemic pleural plaques and excessive numbers of pleural mesotheliomas. AIMS: To review and summarise epidemiological studies, along with other relevant data, and to discuss the potential contribution to environmental risk assessment. METHODS: This report is based on a review of several clinical/epidemiological studies conducted by WCUMS researchers since 1984, which included one cross sectional medical examination survey, one clinical/pathological analysis of 46 cases of mesothelioma, and three retrospective cohort mortality studies. Additional information acquired from reviewing original data first hand during a personal visit along with an interview of medical specialists from Da-yao County Hospital was also incorporated. RESULTS: The prevalence of pleural plaque was 20% among peasants in Da-yao over 40 years of age in the cross sectional survey. The average number of mesothelioma cases was 6.6 per year in the 1984-95 period and 22 per year in the 1996-99 period, in a population of 68 000. For those mesothelioma cases that were histology confirmed, there were 3.8 cases/year in the first period and 9 cases/year in the second. Of the 2175 peasants in this survey, 16 had asbestosis. Lung cancer deaths were significantly increased in all three cohort studies. The annual mortality rate for mesothelioma was 85 per million, 178 per million, and 365 per million for the three cohort studies, respectively. The higher exposed peasants had a fivefold increased mesothelioma mortality compared to their lower exposed counterparts. There were no cases of mesothelioma in the comparison groups where no crocidolite was known to exist in the environment. In the third cohort study, almost one of five cancer deaths (22%) was from mesothelioma. The ratio of lung cancer to mesothelioma deaths was low for all three studies (1.3, 3.0, and 1.2, respectively). CONCLUSIONS: The observation of numerous mesothelioma cases at Da-yao was a unique finding, due mainly to their lifetime exposure to crocidolite asbestos. The finding of cases dying at a younger age and the relatively high ratio of mesothelioma cases to lung cancer could also be another unique result of lifetime environmental exposure to crocidolite asbestos. Although the commercial use of crocidolite has been officially banned since 1984, the incidence of mesothelioma has continued to show a steady increase, particularly among peasants. Since the latency of mesothelioma is approximately 30-40 years, the ban had little effect in the 1990s. The increased awareness and changes in diagnosis over time may also contribute to the increase. Furthermore, exposure to asbestos stoves and walls continued. The government implemented reduction of these exposures. However, from a public health standpoint, the most important issue is the complete avoidance of further exposure to asbestos.
Asbestos, Crocidolite↗
Effect of visual information on step-tracking movements in patients with intention tremor due to multiple sclerosis.
The effect of visual information on step-tracking movements was studied in 18 patients with intention tremor due to multiple sclerosis (MS) and 15 healthy controls. Parricipants performed a slow wrist step-tracking task with stationary targets under five visual feedback conditions. The display of the target and movement cues was selectively withdrawn to examine the effects of visual information on intention tremor and movement accuracy. Results showed that intention tremor was most pronounced when visual display of both target and movement cues was available. Withdrawing visual information of the limb movement reduced tremor more than withdrawing the visual display of the target cues. Both the patient and control group was less accurate when the display of limb movement was occluded. Patients, however, were more dependent on visual information of the limb movement for accurate motor performance than healthy controls. When the visual display of the limb movement was partially occluded between or near to the targets, tremor decreased without deterioration of movement accuracy.
Adult↗
Synthesis, electronic properties, and applications of indium oxide nanowires.
Single-crystalline indium oxide nanowires were synthesized using a laser ablation method and characterized using various techniques. Precise control over the nanowire diameter down to 10 nm was achieved by using monodisperse gold clusters as the catalytic nanoparticles. In addition, field effect transistors with on/off ratios as high as 10(4) were fabricated based on these nanowires. Detailed electronic measurements confirmed that our nanowires were n-type semiconductors with thermal emission as the dominating transport mechanism, as revealed by temperature-dependent measurements. Furthermore, we studied the chemical sensing properties of our In(2)O(3) nanowire transistors at room temperature. Upon exposure to a small amount of NO(2) or NH(3), the nanowire transistors showed a decrease in conductance of up to five or six orders of magnitude, in addition to substantial shifts in the threshold gate voltage. Our devices exhibit significantly improved chemical sensing performance compared to existing solid-state sensors in many aspects, such as the sensitivity, the selectivity, the response time and the lowest detectable concentrations. We have also demonstrated the use of UV light as a "gas cleanser" for In(2)O(3) nanowire chemical sensors, leading to a recovery time as short as 80 seconds.
Crystallization↗
Induction of heat shock protein gp96 by immune cytokines.
Cytokines play a major role in regulating both humoral and cell-mediated immune responses. Recent advances in our understanding of cell-mediated immune responses have focused on the antigen presentation machinery and the proteins in the endoplasmic reticulum (ER). These proteins help the formation and stabilization of the major histocompatibility complex (MHC)-peptide interaction. A 96-kDa, ER-resident glycoprotein (gp96) is being evaluated as a therapeutic agent in cancer because of its ability to associate with a vast number of cellular peptides irrespective of size or sequence. Because the antigen presentation complex is assembled in the ER and a number of ER-resident proteins are modulated by cytokines, it is important to examine the regulation of gp96 in response to immune cytokines interferon gamma (IFN-gamma), and interleukin 2 (IL-2). Defects in signaling pathway in either of the cytokines can result in suboptimal immune response. We examined the effect of the cytokines IFN-gamma and IL-2 on the induction of gp96 in different cancer cell lines and examined the induction of DNA-binding proteins that recognize gamma interferon-activating sequence (GAS), present in the promoter region of gp96. The induction of GAS binding protein correlated with the induction of STAT 1 protein, a transcriptional regulator and mediator of IFN-gamma-mediated gene expression. The use of cytokines in inducing gp96 levels may have significance in maintaining high levels of gp96 for a sustained immune response.
Animals↗
Evaluation of metallothionein and p53 expression as potential prognostic markers for laryngeal squamous cell carcinoma.
The aim of the study was to determine the contribution of metallothionein (MT) and p53 expression in predicting laryngeal squamous cell carcinoma (SCC) recurrence. This was a retrospective study in which MT and p53 immunopositive staining in 32 laryngeal SCC paraffin-embedded sections, were correlated with clinical recurrence. Recurrence was observed in 8 cases with MT expression (42.1%) and 1 case with no expression (7.7%). Moderate and strong MT expression was associated with 14.3% and 58.3% recurrence, respectively. Recurrence was similar for both p53-negative (21.1%) and p53-positive (27.3%) groups. One third of the patients expressing both p53 and MT simultaneously had recurrence. Thus, the combined expression of p53 and MT did not improve the predictive value for recurrence compared to MT alone. MT over-expression may be an independent risk factor for laryngeal SCC recurrence.
Biomarkers, Tumor↗
Complete nucleotide sequence of a potyvirus causing maize dwarf mosaic disease in central China.
The full-length nucleotide sequence of a potyvirus causing the maize dwarf mosaic (MDM) disease in Henan province, central China, was obtained by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of the cDNA 5'-end (5'-RACE). The viral genome comprised of 9596 nucleotides except the polyA tail and encoded a putative polyprotein of 3603 amino acids. The entire genomic sequence of this isolate shared identities of 94.2% and 98.3% with Sugarcane mosaic virus (SCMV) HZ isolate at the nucleotide and deduced amino acid levels, respectively, but only a 69.1% identity with MDM virus (MDMV) Bulgarian isolate (MDMV-Bg) at the nucleotide level. Phylogenetical tree analysis of the complete nucleotide sequences indicated that the Henan isolate of a potyvirus causing MDM disease is in fact a Henan strain of SCMV (SCMV-HN).
Base Sequence↗
HeinzelCluster: accelerated reconstruction for FORE and OSEM3D.
Using iterative three-dimensional (3D) reconstruction techniques for reconstruction of positron emission tomography (PET) is not feasible on most single-processor machines due to the excessive computing time needed, especially so for the large sinogram sizes of our high-resolution research tomograph (HRRT). In our first approach to speed up reconstruction time we transform the 3D scan into the format of a two-dimensional (2D) scan with sinograms that can be reconstructed independently using Fourier rebinning (FORE) and a fast 2D reconstruction method. On our dedicated reconstruction cluster (seven four-processor systems, Intel PIII@700 MHz, switched fast ethernet and Myrinet, Windows NT Server), we process these 2D sinograms in parallel. We have achieved a speedup > 23 using 26 processors and also compared results for different communication methods (RPC, Syngo, Myrinet GM). The other approach is to parallelize OSEM3D (implementation of C Michel), which has produced the best results for HRRT data so far and is more suitable for an adequate treatment of the sinogram gaps that result from the detector geometry of the HRRT. We have implemented two levels of parallelization for four dedicated cluster (a shared memory fine-grain level on each node utilizing all four processors and a coarse-grain level allowing for 15 nodes) reducing the time for one core iteration from over 7 h to about 35 min.
Algorithms↗
Anisotropy and interplane interactions in the dielectric response of graphite.
We determined the anisotropic dielectric response of graphite by means of time-dependent density-functional theory and high-resolution valence electron energy-loss spectroscopy. The calculated loss function was in very good agreement with the experiment for a wide range of momentum-transfer orientations with respect to the graphitic basal planes, provided that local-field effects were included in the response. The calculations also showed strong effects of the interlayer Coulomb interaction on the total pi+sigma plasmon. This finding must be taken into account for the explanation of recent loss spectra of carbon nanotube materials.
Journal Article↗
Experimental studies of pressure/temperature dependence of protein adsorption equilibrium in reversed-phase high-performance liquid chromatography.
The effect of the average pressure and temperature of the column on the adsorption equilibrium of insulin variants on a C8 bonded silica was studied in isocratic reversed-phase HPLC. Analytical injections of samples of four different insulins (bovine, porcine. Lys-Pro and human recombinant) were carried out at constant flow-rate but under increased average pressure. The temperature dependence of the retention parameters over the range 25-50 degrees C was studied under two different average column pressures (47 and 147 bar). Substantial increases of the retention time (up to 300%) were observed when the pressure and/or the temperature were increased. Similar adsorption-induced changes in the partial molar volume at constant temperature (deltaVm approximately 102 ml/mol) were found for all the variants studied. Furthermore, deltaVm was revealed to be practically independent of the temperature, which suggests that the temperature has no or very little influence on the mechanism of the pressure induced perturbations in the molecular structure of the solute. This conclusion was also derived from the observed temperature dependence of the logarithm of the retention factor (k) measured under different pressures. The relation between the temperature and In k was nonlinear with a parabolic shape. Moreover, the shapes of the plots corresponding to the low and high pressures were found to be exactly the same, except that the curves were vertically shifted, due to the difference between the two average column pressures. These results indicate that pressure and temperature affect the retention behavior of insulins in a different and separate way.
Adsorption↗
Functional deficits in patients with mild cognitive impairment: prediction of AD.
OBJECTIVE: To evaluate the predictive utility of self-reported and informant-reported functional deficits in patients with mild cognitive impairment (MCI) for the follow-up diagnosis of probable AD. METHODS: The Pfeffer Functional Activities Questionnaire (FAQ) and Lawton Instrumental Activities of Daily Living (IADL) Scale were administered at baseline. Patients were followed at 6-month intervals, and matched normal control subjects (NC) were followed annually. RESULTS: Self-reported deficits were higher for patients with MCI than for NC. At baseline, self- and informant-reported functional deficits were significantly greater for patients who converted to AD on follow-up evaluation than for patients who did not convert, even after controlling for age, education, and modified Mini-Mental State Examination scores. While converters showed significantly more informant- than self-reported deficits at baseline, nonconverters showed the reverse pattern. Survival analyses further revealed that informant-reported deficits (but not self-reported deficits) and a discrepancy score indicating greater informant- than self-reported functional deficits significantly predicted the development of AD. The discrepancy index showed high specificity and sensitivity for progression to AD within 2 years. CONCLUSIONS: These findings indicate that in patients with MCI, the patient's lack of awareness of functional deficits identified by informants strongly predicts a future diagnosis of AD. If replicated, these findings suggest that clinicians evaluating MCI patients should obtain both self-reports and informant reports of functional deficits to help in prediction of long-term outcome.
Activities of Daily Living↗
Ischemia/reperfusion injury induces acinar cell apoptosis in experimental pancreas transplantation.
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Animals↗
Up-regulation of cystatin C expression in the murine hippocampus following perforant path transections.
Cystatins are endogenous cysteine protease inhibitors that modulate the turnover of intracellular and extracellular proteins. These inhibitors are strongly implicated in a variety of pathological processes such as tumor metastasis and many degenerating CNS disorders. Here we report the expression of cystatin C, a major cysteine protease inhibitor of mammalian animals, in the murine hippocampus at 3, 7, 15 and 30 days following perforant path transections. Northern blot analysis showed that cystatin C transcripts were up-regulated in a transient manner with a significant increase at 7 and 15 days post-lesion (219% and 185% of control, respectively) in the rat hippocampus after entorhinal deafferentation. In situ hybridization and immunohistochemistry confirmed the time-dependent up-regulation of both cystatin C mRNA and protein expressions in a mouse model which initiated at 3 days post-lesion, reached maximal levels 7-15 days post-lesion, and remained slightly elevated by day 30 post-lesion. The modulation of cystatin C expression was observed to occur specifically in the entorhinally denervated zones: the stratum lacunosum-moleculare of the hippocampus and the outer molecular layer of the dentate gyrus. Double labeling by either a combination of in situ hybridization for cystatin C with immunohistochemistry for glial fibrillary acidic protein or double immunofluorescence staining for both proteins in mouse hippocampus at 7 and 15 days post-lesion revealed that most cystatin C-expressing cells are astrocytes. From these results we suggest that the spatiotemporal up-regulation of cystatin C in the hippocampus is induced by entorhinal deafferentation and that cystatin C may be involved in the astroglia-mediated neural plasticity events in the hippocampus following perforant path transections.
Animals↗
The oscillatory activity in the Parkinsonian subthalamic nucleus investigated using the macro-electrodes for deep brain stimulation.
OBJECTIVES: To investigate the oscillatory activity in the Parkinsonian subthalamic nucleus using the macro-electrodes for deep brain stimulation. METHODS: During bilateral deep brain stimulating electrode implantation, spontaneous and evoked field potentials were recorded from the subthalamic nucleus (STN) in two patients with Parkinson's disease (PD) during spontaneous resting tremor, passive manipulation of the wrist, and following electrical stimulation of the contralateral STN. RESULTS: Frequency analysis of the STN field potentials recorded during spontaneous resting tremor showed significant coherence with electromyographic activity in the contralateral arm, suggesting a close involvement of the STN in the generation of resting tremor in PD. The STN responded to passive movement of the contralateral wrist, but not to ipsilateral movement. High frequency (100 Hz) electrical stimulation of the STN induced tremor (4 Hz) in both forearms, and also oscillation of the contralateral STN (4 Hz). In contrast, low frequency (5 Hz) stimulation induced contralateral arrhythmic involuntary movement (3 Hz), but without altering the contralateral STN activity. CONCLUSIONS: We propose that the functional connection between the STN and arm muscles is mainly contralateral, but cross talk may occur between bilateral STN via a frequency-dependent pathway.
Animals↗
Reelin gene alleles and susceptibility to autism spectrum disorders.
A polymorphic trinucleotide repeat (CGG/GCC) within the human Reelin gene (RELN) was examined as a candidate gene for autism spectrum disorders (ASDs). This gene encodes a large extracellular matrix protein that orchestrates neuronal positioning during corticogenesis. The CGG-repeat within the 5' untranslated region of RELN exon 1 was examined in 126 multiple-incidence families. The number of CGG repeats varied from three to 16 in affected individuals and controls, with no expansion or contraction observed during maternal (n = 291) or paternal (n = 287) transmissions in families with autistic probands. Although the frequencies of the RELN alleles and genotypes in affected children were not different from those in the comparison group, a family-based association test (FBAT) showed that the larger RELN alleles (> or = 11 repeats) were transmitted more often than expected to affected children (S = 43, E(S) = 34.5, P = 0.035); this was particularly the case for the 13-repeat RELN allele (S = 22, E(S) = 16, P = 0.034). Affected sib-pair (ASP) analysis found no evidence of excess sharing of RELN alleles in affected siblings. The impact of genotypes with large alleles (> or = 11 repeats) on the phenotypes in individuals with ASD was analyzed by ANOVA in a subset of the families for which results of the Autism Diagnostic Interview-Revised were available. Children with large RELN alleles did not show any difference in scores for questions related to the core symptoms of autistic disorder, but there was a tendency for children with at least one large RELN allele to have an earlier age at first phrase (chi(2) = 3.538, P = 0.06). Thus, although the case-control and affected sib-pair findings did not support a role for RELN in susceptibility to ASD, the more powerful family-based association study demonstrated that RELN alleles with larger numbers of CGG repeats may play a role in the etiology of some cases of ASD, especially in children without delayed phrase speech.
Autistic Disorder↗
Cyclic AMP and cyclic GMP activate protein kinase G in cavernosal smooth muscle cells: old age is a negative factor.
OBJECTIVE: To investigate protein kinase G-I (PKG-I) expression and activation in cavernosal smooth muscle cells (CSMC) of young and old rats. MATERIALS AND METHODS: PKG-I expression in rat penis was examined by immunohistochemical staining, reverse transcription-polymerase chain reaction, and Western blot analysis. CSMC isolated from young (16-week-old) and old (28-month-old) rats were grown as monolayer cell cultures and treated with different dosages of cAMP or cGMP for different periods. Their proteins were then analysed for the expression of vasodilator-stimulated phosphoprotein (VASP), phosphorylated VASP (at serine 239), PKG-I, and protein kinase A (PKA). RESULTS: PKG-I expression was detected in the vascular and CSMC of the rat penis. There was little or no difference in the level of PKG-I expression between young and old rats. Treatment of CSMC with different dosages of cAMP or cGMP did not change the expression levels of VASP throughout the entire test period (up to 24 h). In contrast, the level of VASP phosphorylation at S239, i.e. the level of PKG-I activation, depended on the dosages of cAMP and cGMP and on the duration of treatment. Prolonged treatment (24 h) with either cAMP or cGMP resulted in down-regulation of both PKG-I and PKA. While cAMP and cGMP produced very similar results in nearly every aspect, there was a difference in one test, in which cGMP produced much less activated PKG-I than cAMP in the CSMC of 28-month-old-rats. CONCLUSIONS: For the first time we provide evidence for PKG-I activation in CSMC. Both cAMP and cGMP were capable of activating PKG-I in CSMC. Age seemed to compromise the ability of PKG-I in response to cGMP.
Age Factors↗
Electrophysiological confirmation of the zona incerta as a target for surgical treatment of disabling involuntary arm movements in multiple sclerosis: use of local field potentials.
Lesioning or chronic deep brain stimulation (DBS) of the nucleus ventralis intermedius results in abolition of tremor in the contralateral limbs in Parkinson's disease (PD) and also in essential tremor. Recently, chronic DBS of the subthalamic nucleus has also proved to be very effective in reducing contralateral limb tremor in PD. These targets have been less effective in controlling the complex limb tremor often seen in multiple sclerosis (MS). Consequently, other targets have been sought in cases of MS with tremor. We describe a patient with MS with disabling proximal and distal involuntary arm movements in whom we were able to obtain sustained control of contralateral arm tremor and achieve functional improvement of the affected arm by chronic DBS of the region of the zona incerta. We also highlight the important role played by local field potentials recorded from the brain, with simultaneous recording of corresponding EMGs, in target localisation.
Action Potentials↗
Effects of 17beta-estradiol on blood-brain barrier disruption during focal ischemia in rats.
This study was performed to test whether 17beta-estradiol could attenuate the blood-brain barrier disruption caused by middle cerebral artery occlusion in the ovariectomized rats. Rats aged twelve to fourteen weeks were used in this study. Their ovaries were removed one week prior to the implantation of the pellets. For the 17beta-estradiol group, a 500 microg 17beta-estradiol 21 day-release pellet was implanted and for the control group, a vehicle pellet was implanted 21 days before the experiments. One hour after middle cerebral artery occlusion under isoflurane anesthesia, the transfer coefficient of 14C-alpha-aminoisobutyric acid (104 Daltons) and the volume of 3H-dextran (70,000 Daltons) distribution were determined to represent the degree of blood-brain barrier disruption. Blood pressures and blood gases were similar between controls and 17beta-estradiol-treated rats. In both groups, the transfer coefficient of the ischemic cortex was higher than that of the corresponding contralateral cortex (control: Ischemic Cortex 12.5 +/- 5.9 microl/g/min, Contralateral Cortex 3.0 +/- 1.6, p < 0.001; 17beta-estradiol: Ischemic Cortex 6.7 +/- 3.3 micro l/g/min, Contralateral Cortex 2.2 +/- 0.9, p < 0.01). There was no significant difference in the transfer coefficient of the contralateral cortex between these two groups. However, the transfer coefficient of the Ischemic Cortex of the 17beta-estradiol-treated animals was 46 % lower than that of the control, vehicle-treated rats (p < 0.05). The increase of the volume of 3H-dextran distribution with middle cerebral artery occlusion was significant in the vehicle-treated rats (Ischemic Cortex: 6.4 +/- 2.7 ml/100 g, Contralateral Cortex: 3.8 +/- 0.8, p < 0.01) but not in the 17beta-estradiol-treated animals. Our data suggest that chronic 17beta-estradiol treatment was effective in reducing blood-brain barrier disruption during focal ischemia in the ovariectomized rats.
Aminoisobutyric Acids↗