Biomedical subjects

L Han

Publications and source records attributed to L Han.

At least 19 recordsLinked to original sources

PubMed2001

Use of medications with anticholinergic effect predicts clinical severity of delirium symptoms in older medical inpatients.

BACKGROUND: Use of anticholinergic (ACH) medications is a biologically plausible and potentially modifiable risk factor of delirium, but research findings are conflicting regarding its association with delirium. OBJECTIVES: To evaluate the longitudinal association between use of ACH medications and severity of delirium symptoms and to determine whether this association is modified by the presence of dementia. PATIENTS AND METHODS: A total of 278 medical inpatients 65 years and older with diagnosed incident or prevalent delirium were followed up with repeated assessments using the Delirium Index for up to 3 weeks. Exposure to ACH and other medications was measured daily. The association between change in medication exposure in the 24 hours preceding a Delirium Index assessment was assessed using a mixed linear regression model. RESULTS: During follow-up (mean +/- SD, 12.3 +/- 7.0 days), 47 medications with potential ACH effect were used in the population (mean, 1.4 medications per patient per day). Increase in delirium severity was significantly associated with several measures of ACH medication exposure on the previous day, adjusting for dementia, baseline delirium severity, length of follow-up, and number of non-ACH medications taken. Dementia did not modify the association between ACH medication use and delirium severity. CONCLUSION: Exposure to ACH medications is independently and specifically associated with a subsequent increase in delirium symptom severity in elderly medical inpatients with diagnosed delirium.

Aged↗

PubMed2001

Nongenotropic, sex-nonspecific signaling through the estrogen or androgen receptors: dissociation from transcriptional activity.

The relationship of the classical receptors and their transcriptional activity to nongenotropic effects of steroid hormones is unknown. We demonstrate herein a novel paradigm of sex steroid action on osteoblasts, osteocytes, embryonic fibroblasts, and HeLa cells involving activation of a Src/Shc/ERK signaling pathway and attenuating apoptosis. This action is mediated by the ligand binding domain and eliminated by nuclear targeting of the receptor protein; ERalpha, ERbeta, or AR can transmit it with similar efficiency irrespective of whether the ligand is an estrogen or an androgen. This antiapoptotic action can be dissociated from the transcriptional activity of the receptor with synthetic ligands, providing proof of principle for the development of function-specific-as opposed to tissue-selective-and gender-neutral pharmacotherapeutics.

Androgens↗

PubMed2001

Rare adult acute lymphocytic leukemia with CD56 expression in the ECOG experience shows unexpected phenotypic and genotypic heterogeneity.

Expression of CD56, a marker of natural killer (NK) cells, in acute lymphocytic leukemia (ALL) is rare and, to date, has been described only in non-B lineage ALL. Among 194 patients with CD56 analysis on the ongoing Eastern Cooperative Oncology Group (ECOG) ALL trial, E2993, 6 cases of CD56+ ALL were found (3.1%) with a median of 95% of blast cells expressing CD56, compared with a median of 1% of blast cells in CD56- ALL (P = 0.0001). FAB-L2 characteristics dominated, without granulation. Blast cells from four CD56+ patients expressed T-cell antigens at variable levels of maturation. A clonal rearrangement of the T-cell receptor beta (TCRbeta) gene was detected only in one patient. TCRbeta variable gene usage studies in this and one other CD56+ ALL patient demonstrated a significantly perturbed usage pattern in both patients when compared with control lymphocytes. The two remaining cases typed as early pre-B ALL (CD19+, CD10+), with one case co-expressing CD7. Cytogenetically, 4 patients were normal, 1 complex abnormal, and 1 Philadelphia chromosome positive. Epstein-Barr virus (EBV) sequences were detected in one T- and both B-lymphoid cases. Our data suggest that CD56 is expressed at a precursor stage common to the T- and the B-cell lineage.

Adult↗

PubMed2001

Fluorescent imaging and analysis with Typhoon 8600.

Current technologies in laser-based imaging systems for life science applications offer highly sensitive and quantitative detection of multiple labels. Typhoon 8600 variable mode imager is capable of fluorescence, storage phosphor, and chemiluminescence detection of gels and blots. The system delivers sensitive fluorescent detection of nucleic acids and proteins in both agarose and polyacrylamide gel formats. Detection and discrimination of multicolor fluorescent signals in fragment analysis, electromobility shift assays, Western blotting and other applications enhance the speed and accuracy of analysis.

DNA↗

PubMed2001

Interleukin 4 content in chronic lymphocytic leukaemia (CLL) B cells and blood CD8+ T cells from B-CLL patients: impact on clonal B-cell apoptosis.

B-chronic lymphocytic leukaemia (CLL) clonal B cells are characterized by resistance to apoptosis. We evaluated clonal B cells and blood T cells for interleukin 4 (IL-4) content as IL-4 is able to increase CLL cell resistance to apoptosis. The content of IL-4 in CD8+ T cells of CLL patients (n = 9) ranged from 37% to 63% of the total CD8+ T cells (mean level of 49% +/- 3.4) compared with a range of 5-10% for control CD8+ T cells. Clonal B cells positive for cytoplasmic IL-4 ranged from 1% to 97% (mean value 57.8 +/- 6.9%). CD8+ T cells and clonal B cells secreted detectable levels of IL-4, but only clonal CLL B cells (n = 4) secreted IL-4 in association with increasing cell numbers. Fludarabine (F-ara-AMP, 0.1-100 micromol/ml) was able to downregulate the IL-4 content of CD8+ T cells, but not clonal B-cell IL-4. Culture supernatant from CLL CD8+ T cells decreased the spontaneous apoptotic rate of clonal B cells that was reversed with anti-IL-4 and soluble IL-4 receptor. These findings show that IL-4 is present in the microenvironment of B-CLL. In addition, use of agents that can interfere with IL-4 presentation to clonal B cells can be effective in increasing clonal B-cell apoptosis.

Antineoplastic Agents↗

PubMed2001

Protein binding protects sites on stable episomes and in the chromosome from de novo methylation.

We have utilized the Escherichia coli lac repressor-operator system to test whether protein binding can interfere with de novo DNA methylation in mammalian cells. We find that a DNA binding protein can protect sites on the episome as well as in the genome from the de novo methylation activity of Dnmt3a. Transcriptional machinery moving through the binding sites does not affect the de novo methylation of these sites, and it does not affect the binding protein protection of these sites from de novo methylation. This study and previous studies provide a possible mechanism for the observation that an Sp1 site can serve as a cis-acting signal for demethylation and for preventing de novo methylation of the CpG island upstream of the mouse adenine phosphoribosyltransferase (Aprt) gene. These findings also support the hypothesis that protein binding may play a crucial role in changes of CpG methylation pattern in mammalian cells.

Bacterial Proteins↗

PubMed2001

Influence of acupuncture upon expressing levels of basic fibroblast growth factor in rat brain following focal cerebral ischemia--evaluated by time-resolved fluorescence immunoassay.

We investigate the expression of basic fibroblast growth factor (bFGF) during ischemia-reperfusion with or without electroacupuncture (EA) treatment, and observe the effect of EA on ischemic cerebral injury. In the present study, a sensitive sandwich time-resolved fluoroimmunoassay (TR-FIA) method was developed to quantitatively analyze the levels of bFGF in rat brain. The results indicated that the obvious cerebral infarction and swelling were observed after ischemia-reperfusion, and the opening amount of cerebral blood micrangium was increased. In the meantime, the expression of bFGF was also improved in striatum and frontoparietal cortex. EA alleviated the ischemic injuries induced by MCAO and markedly upregulated the opening amount of the micrangium. Owing to application of EA, the expression of bFGF was notably enhanced in striatum and cortex. The results give us some hints for the neuroprotective mechanism of EA, that is, EA may partially exert protective effects on neurons through regulating the blood dynamics and the endogenous expression of bFGF.

Animals↗

PubMed2001

Study of the fluoridated adhesive resin cement--fluoride release, fluoride uptake and acid resistance of tooth structures.

The objectives of this study, were to evaluate the fluoride release from fluoridate adhesive resin cement, fluoride uptake into surrounding tooth structures and the effect of their acid resistance. Several specimens were prepared using a plastic ring mould, from extracted human premolars, and prepared from enamel and dentin of the central area of the buccal surface of bovine teeth. The fluoride release rate of fluoridate adhesive resin cement (PN 200) per day was higher than other materials during the 7-day study period. Fluoride released and fluoride uptake by tooth structures was higher in the fluoridate adhesive resin cement. WDX analysis showed the fluoride concentration on dentin contact area was higher than that of enamel after 60 days of immersion in deionized water. The calcium release values were similar for enamel and dentin plates in the various test materials. The present findings indicated the important enhancement of tooth structure acid resistance by fluoridate material.

Animals↗

PubMed2001

Evaluation of the surface roughness of compomer by laser scanning microscopy.

The purpose of this study was to evaluate the effect of alcoholic and low pH soft drinks on the surface roughness of compomer restorative materials. There were five tested materials and four immersion media. Specimens were immersed in test solutions for a 10-day period at a temperature of 37 degrees C. Measurement of the surface texture was carried out using a laser scanning microscope (a non-contact laser stylus tracing method). This was also used to produce the Laser Scanning Microscope Image (LSM Image). Specimens immersed in orange juice and whisky displayed higher values for Ra & Rz than specimens immersed in soft drinks and deionized water. LSM Image showed a difference between the control and the examined side, especially for specimens immersed in low pH soft drinks this could be due to the erosive effect of the media. Alcoholic and low pH soft drinks caused deterioration of the materials surface, which may lead to a clinically detectable rough and dull surface.

Alcoholic Beverages↗

PubMed2001

[Quinoline removal in fluidized-bed bioreactor using immobilized cells].

Burkholderia pickettii, capable of using quinoline as sole source of carbon, nitrogen and energy, was immobilized by an innovative PVA-H3BO3-gauze method. A fluidized-bed bioreactor, in which immobilized cells were added, was constructed to degrade quinoline in wastewater. When the initial concentrations of quinoline were 100, 350 and 500 mg/L, the bioreactor can remove it completely within 2.5, 6 and 12 hours respectively. A series of zero-order reaction equations were proposed to describe quinoline biodegradation process in this bioreactor kinetically. In continuous flow experiments, the performance of the bioreactor was investigated at different HRT (dilution rate) for different quinoline concentrations in wastewater and the tolerance against shock loading was determined by increasing quinoline concentration from 100 to 300 to 500 mg/L at HRT 4 hours.

Bioreactors↗

PubMed2000

G protein-coupled receptor-induced sensitization of phospholipase C stimulation by receptor tyrosine kinases.

Activation of stably expressed M(2) and M(3) muscarinic acetylcholine receptors (mAChRs) as well as of endogenously expressed lysophosphatidic acid and purinergic receptors in HEK-293 cells can induce a long lasting potentiation of phospholipase C (PLC) stimulation by these and other G protein-coupled receptors (GPCRs). Here, we report that GPCRs can induce an up-regulation of PLC stimulation by receptor tyrosine kinases (RTKs) as well and provide essential mechanistic characteristics of this sensitization process. Pretreatment of HEK-293 cells for 2 min with carbachol, a mAChR agonist, lysophosphatidic acid, or ATP, followed by agonist washout, strongly increased (by 2-3-fold) maximal PLC stimulation (measured >/=40 min later) by epidermal growth factor and platelet-derived growth factor, but not insulin, and largely enhanced PLC sensitivity to these RTK agonists. The up-regulation of RTK-induced PLC stimulation was cycloheximide-insensitive and was observed for up to approximately 90 min after removal of the GPCR agonist. Sensitization of receptor-induced PLC stimulation caused by prior M(2) mAChR activation was fully prevented by pertussis toxin and strongly reduced by expression of Gbetagamma scavengers. Furthermore, inhibition of conventional protein kinase C (PKC) isoenzymes and chelation of intracellular Ca(2+) suppressed the sensitization process, while overexpression of PKC-alpha, but not PKC-betaI, further enhanced the M(2) mAChR-induced sensitization of PLC stimulation. None of these treatments affected acute PLC stimulation by either GPCR or RTK agonists. Taken together, short term activation of GPCRs can induce a strong and long lasting sensitization of PLC stimulation by RTKs, a process apparently involving G(i)-derived Gbetagammas as well as increases in intracellular Ca(2+) and activation of a PKC isoenzyme, most likely PKC-alpha.

Adenosine Triphosphate↗

PubMed2000

The M3 muscarinic acetylcholine receptor expressed in HEK-293 cells signals to phospholipase D via G12 but not Gq-type G proteins: regulators of G proteins as tools to dissect pertussis toxin-resistant G proteins in receptor-effector coupling.

The M(3) muscarinic acetylcholine receptor (mAChR) expressed in HEK-293 cells couples to G(q) and G(12) proteins and stimulates phospholipase C (PLC) and phospholipase D (PLD) in a pertussis toxin-insensitive manner. To determine the type of G protein mediating M(3) mAChR-PLD coupling in comparison to M(3) mAChR-PLC coupling, we expressed various Galpha proteins and regulators of the G protein signaling (RGS), which act as GTPase-activating proteins for G(q)- or G(12)-type G proteins. PLD stimulation by the M(3) mAChR was enhanced by the overexpression of Galpha(12) and Galpha(13), whereas the overexpression of Galpha(q) strongly increased PLC activity without affecting PLD activity. Expression of the RGS homology domain of Lsc, which acts specifically on Galpha(12) and Galpha(13), blunted the M(3) mAChR-induced PLD stimulation without affecting PLC stimulation. On the other hand, overexpression of RGS4, which acts on Galpha(q)- but not Galpha(12)-type G proteins, suppressed the M(3) mAChR-induced PLC stimulation without altering PLD stimulation. We conclude that the M(3) mAChR in HEK-293 cells apparently signals to PLD via G(12)- but not G(q)-type G proteins and that G protein subtype-selective RGS proteins can be used as powerful tools to dissect the pertussis toxin-resistant G proteins and their role in receptor-effector coupling.

Carbachol↗

PubMed2000

Ultradian oscillations in cranial thermoregulation and electroencephalographic slow-wave activity during sleep are abnormal in humans with annual winter depression.

The level of core body, and presumably brain temperature during sleep varies with clinical state in patients with seasonal affective disorder (SAD), becoming elevated during winter depression and lowered during clinical remission induced by either light treatment or summer. During sleep, brain temperatures are in part determined by the level of brain cooling activity, which may be reflected by facial skin temperatures. In many animals, the level of brain cooling activity oscillates across the NREM-REM sleep cycle. Facial skin temperatures during sleep in patients with winter depression are abnormally low and uncorrelated with rectal temperatures, although their relationship to EEG-defined sleep stages remains unknown. We therefore measured the sleep EEG, core body and facial skin temperatures in 23 patients with winter depression and 23 healthy controls, and tested the hypothesis that ultradian oscillations in facial skin temperatures exist in humans and are abnormal in patients with winter depression. We found that facial skin temperatures oscillated significantly across the NREM-REM sleep cycle, and were again significantly lower and uncorrelated with rectal temperatures in patients with winter depression. Mean slow-wave activity and NREM episode duration were significantly greater in patients with winter depression, whereas the intraepisodic dynamics of slow-wave activity were normal in patients with winter depression. These results suggest that brain cooling activity oscillates in an ultradian manner during sleep in humans and is reduced during winter depression, and provide additional support for the hypothesis that brain temperatures are elevated during winter depression.

Activity Cycles↗

PubMed2000

Tracking cognitive decline in Alzheimer's disease using the mini-mental state examination: a meta-analysis.

OBJECTIVES: To estimate the annual rate of change scores (ARC) on the Mini-Mental State Examination (MMSE) in Alzheimer's disease (AD) and to identify study or population characteristics that may affect the ARC estimation. METHODS: MEDLINE was searched for articles published from January 1981 to November 1997 using the following keywords: AD and longitudinal study or prognosis or cognitive decline. The bibliographies of review articles and relevant papers were searched for additional references. All retrieved articles were screened to meet the following inclusion criteria: (a) original study; (b) addressed cognitive decline or prognosis or course of AD; (c) published in English; (d) study population included AD patients with ascertainable sample size; (e) used either clinical or pathological diagnostic criteria; (f) longitudinal study design; and (g) used the MMSE as one of the outcome measures. Data were systematically abstracted from the included studies, and a random effects regression model was employed to synthesize relevant data across studies and to evaluate the effects of study methodology on ARC estimation and its effect size. RESULTS: Of the 439 studies screened, 43 met all the inclusion criteria. After 6 studies with inadequate or overlapping data were excluded, 37 studies involving 3,492 AD patients followed over an average of 2 years were included in the meta-analysis. The pooled estimate of ARC was 3.3 (95% confidence interval [CI]: 2.9-3.7). The observed variability in ARC across studies could not be explained with the covariates we studied, whereas part of the variability in the effect size of ARC could be explained by the minimum MMSE score at entry and number of assessments. CONCLUSIONS: A pooled average estimate of ARC in AD patients was 3.3 points (95% CI: 2.9-3.7) on the MMSE. Significant heterogeneity of ARC estimates existed across the studies and cannot be explained by the study or population characteristics investigated. Effect size of ARC was related to the initial MMSE score of the study population and the number of assessments.

Aged↗

PubMed2000

Heart rate variability of children with mitral valve prolapse.

Studies have indicated that adult patients with mitral valve prolapse (MVP) may have autonomic dysfunction. The purpose of this study was to evaluate heart rate variability (HRV) in children with MVP. Sixty-seven children with MVP (ages 6 to 18 years; 30 boys and 37 girls) were consecutively studied and subdivided into those with or without symptoms. Thirty-seven normal age-matched children (17 boys and 20 girls) were studied as controls. The patients were further divided into 4 age subgroups. HRV was measured using a 24-hour Holter electrocardiogram (ECG) system (Laser SXP Holter Analysis System, Marquette Electronics, Milwaukee, WI). The ECGs were analyzed in both time domain and frequency domain (spectral analysis). Symptomatic and asymptomatic children with MVP were combined for analysis because they were not significantly different in terms of their HRV. All time-domain indices, with the exception of SDANN (SD of the mean of RR intervals in all 5-minute segments of the 24-hour ECG), were significantly lower in children with MVP than in controls. Children with MVP showed significantly lower spectral power of the high frequency (HF) and low frequency (LF) components when compared with controls. The ratio of LF to HF (LF/HF) was significantly higher in children with MVP. Similar differences were observed in the 4 age subgroups. Sex differences in HRV were observed when girls had lower HRV compared with boys. Lower time-domain and frequency-domain indices of HRV in children with MVP are suggestive of decreased parasympathetic activity and a shift in sympathovagal balance. Various factors including differences in heart rate may contribute to sex differences in HRV.

Adolescent↗

PubMed2000

Changes in the mechanical properties and surface texture of compomer immersed in various media.

STATEMENT OF PROBLEM: Limited information is available about the mechanical behavior of compomer under intraoral conditions. PURPOSE: This in vitro study evaluated changes in the mechanical properties and surface texture of compomer and other materials, used in similar clinical circumstances, when immersed in various media. MATERIAL AND METHODS: Hardness measurement for 5 tested materials and 4 immersion media was obtained with a Vickers hardness testing machine. Compressive strength was measured using an Autograph at a crosshead speed of 0.75 mm/min. All readings were taken for up to a 60-day period. An electron probe microanalyzer was used to give an SEM image. RESULTS: The average compressive strength and Vickers surface hardness showed a significant difference between materials. Results showed an overall increase in the solubility of specimens immersed in low pH soft drinks. CONCLUSION: There was a difference in the mechanical properties and surface texture of the materials tested in this study when they were immersed in various media.

Alcoholic Beverages↗

PubMed2000

An acyl-coenzyme A carboxylase encoding gene associated with jadomycin biosynthesis in Streptomyces venezuelae ISP5230.

Analysis of a region of chromosomal DNA lying between jadR1 and jadI in the gene cluster for jadomycin biosynthesis in Streptomyces venezuelae ISP5230 detected an ORF encoding 584 amino acids similar in sequence to the biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) components of acyl-coenzyme A carboxylases. Multiple sequence alignments of the deduced Jad protein with acyl-coenzyme A carboxylases from various sources located the BC and BCCP components in the N- and C-terminal regions, respectively, of the deduced polypeptides. The organization and amino acid sequence of the deduced polypeptide most closely resembled those in other Gram-positive bacteria broadly classified as actinomycetes. Disrupting the gene, designated jadJ, severely reduced but did not eliminate jadomycin production. The disruption had no effect on growth or morphology of the organism, implying that the product of jadJ is not essential for fatty acid biosynthesis. It is concluded that jadJ supplies malonyl-coenzyme A for biosynthesis of the polyketide intermediate that is eventually processed to form the antibiotic jadomycin B.

Amino Acid Sequence↗

PubMed2000

Effect of alcoholic and low-pH soft drinks on fluoride release from compomer.

PURPOSE: The purpose of this study was to evaluate the amount of fluoride released from compomer restorative materials after immersion in various media. MATERIALS AND METHODS: In this test, four materials were used: three compomers (Dyract, Dentsply, Konstanz, Germany; Compoglass, Vivadent, Schaan, Principality of Liechtenstein; and Xeno, Sankins, Tochigi, Japan) and one resin-modified glass ionomer cement (Fuji II LC, GC, Tokyo, Japan). There were four test solutions: one alcoholic (whiskey), two low-pH drinks (Coca-Cola, orange juice), and one deionized water. Over a period of 60 days, the tested specimens were immersed in the test solution for 3 hours every day, then kept in deionized water. The fluoride released was detected by using a fluoride ion selective electrode connected to a microprocessor ion analyzer. The fluoride ion concentration (ppm) of the test solutions and deionized water was recorded after 1, 2, 3, 4, 7, 30, and 60 days. Electron probe microanalysis was used for surface analysis of the fluoride released. RESULTS: When immersed in low-pH soft drinks, compomer showed a significantly higher fluoride release than when immersed in deionized water (p < .0001). For specimens immersed in Coca-Cola, the fluoride release levels (microgram/cm2, mean +/- SD) at 1, 7, and 60 days for Dyract (91.6 +/- 1.8, 39.3 +/- 3.1, 10.5 +/- 0.9), Compoglass (129.5 +/- 0.9, 66.5 +/- 2.7, 19.0 +/- 0.3), Fuji II LC (147.0 +/- 4.2, 50.8 +/- 3.1, 27.6 +/- 3.0), and Xeno (73.6 +/- 3.2, 27.3 +/- 2.1, 6.6 +/- 0.6) demonstrated the trend of significantly lower releases with time in water solution. Over a 60-day period, materials immersed in 100% orange juice released the highest amount of fluoride, which could be attributable to the erosive effect of the medium. Materials immersed in deionized water released the least amount of fluoride. Among the tested compomers, Compoglass released the most fluoride.

Alcoholic Beverages↗