Biomedical subjects

Grace Lee

Publications and source records attributed to Grace Lee.

At least 19 recordsLinked to original sources

PubMed2006

Patterns of cerebral perfusion in patients with asymptomatic internal carotid artery disease.

BACKGROUND: The perfusion profile of patients with asymptomatic internal carotid artery (ICA) disease has not been well studied. The purpose of this study is to describe the perfusion patterns of patients with asymptomatic ICA disease using computed tomography perfusion (CTP) and its potential value in identifying patients at higher risk for transient ischemic attacks (TIAs) or strokes. METHODS: We analyzed 32 patients with asymptomatic high grade ICA disease who had CTP and computed tomography angiography (CTA) of the head and neck. Twenty-four patients had severe ICA stenosis and eight had ICA occlusion. The degree of ipsilateral external carotid artery (ECA) and contralateral ICA stenosis, patency of the anterior communicating artery (ACOM), A1 segment and posterior communicating artery (PCOM) were evaluated in all patients. RESULTS: Sixteen patients had normal CTP and the other 16 patients had cerebral hypoperfusion, characterized by abnormalities in one or more of the three perfusion maps. Ipsilateral hypoplastic A1 segment was more frequent in the group with cerebral hypoperfusion (p = 0.025). Ipsilateral TIAs occurred in two patients, both with cerebral hypoperfusion. CONCLUSION: Cerebral hypoperfusion is present in half of the patients with asymptomatic ICA disease, predominantly in patients with a hypoplastic ipsilateral A1 segment. These patients likely represent a higher-risk group for symptomatic brain ischemia.

Adult↗

PubMed2006

Gene expression signatures for predicting prognosis of squamous cell and adenocarcinomas of the lung.

Non-small-cell lung cancers (NSCLC) compose 80% of all lung carcinomas with squamous cell carcinomas (SCC) and adenocarcinoma representing the majority of these tumors. Although patients with early-stage NSCLC typically have a better outcome, 35% to 50% will relapse within 5 years after surgical treatment. We have profiled primary squamous cell lung carcinomas from 129 patients using Affymetrix U133A gene chips. Unsupervised analysis revealed two clusters of SCC that had no correlation with tumor stage but had significantly different overall patient survival (P = 0.036). The high-risk cluster was most significantly associated with down-regulation of epidermal development genes. Cox proportional hazard models identified an optimal set of 50 prognostic mRNA transcripts using a 5-fold cross-validation procedure. Quantitative reverse transcription-PCR and immunohistochemistry using tissue microarrays were used to validate individual gene candidates. This signature was tested in an independent set of 36 SCC samples and achieved 84% specificity and 41% sensitivity with an overall predictive accuracy of 68%. Kaplan-Meier analysis showed clear stratification of high-risk and low-risk patients [log-rank P = 0.04; hazard ratio (HR), 2.66; 95% confidence interval (95% CI), 1.01-7.05]. Finally, we combined the SCC classifier with our previously identified adenocarcinoma prognostic signature and showed that the combined classifier had a predictive accuracy of 71% in 72 NSCLC samples also showing significant differences in overall survival (log-rank P = 0.0002; HR, 3.54; 95% CI, 1.74-7.19). This prognostic signature could be used to identify patients with early-stage high-risk NSCLC who might benefit from adjuvant therapy following surgery.

Adenocarcinoma↗

PubMed2006

Identification of USF2 as a key regulator of Runx2 expression in mouse pluripotent mesenchymal D1 cells.

Runx2 is one of the most important transcription factors directing the osteogenesis of mesenchymal stem cells and osteoblastic functions. It is likely that the factors controlling Runx2 expression would trigger the early steps of osteoblast differentiation. By using a reporter gene assay for 4.5 kb Runx2 promoter, it was found that the first 305 bp of Runx2 promoter are active in D1 cells. Within this region, electromobility shift assays (EMSAs) delineated a 6 bp of CACATG bound specifically by the proteins from D1 cell nuclear extract. Antibody super-shift and DNA-coupling magnetic bead pull-down assay indicated that the protein bound to this sequence is USF2. Site-specific mutagenesis revealed that this sequence contributed to the activity of 305 bp Runx2 promoter. Thus, we suggest that USF2 might be one of the regulators for the expression of the Runx2 gene in D1 cells.

Animals↗

PubMed2006

Effect of a qigong exercise programme on elderly with depression.

OBJECTIVES: This report released findings of a randomized controlled trial conducted in Hong Kong to further our understanding of the psychosocial effects of qigong on elderly persons with depression. DESIGN: Eighty-two participants with a diagnosis of depression or obvious features of depression were recruited and randomly assigned into the intervention and comparison group. The intervention group was given a 16-week period of Qigong practice while the comparison group participated in a newspaper reading group with same duration and frequency. RESULTS: After eight weeks of qigong practice, the intervention group participants outstripped themselves in improvement in mood, self-efficacy and personal well being, and physical and social domains of self-concept when compared with comparison subjects. After 16 weeks of practice, the improvement generalized to the daily task domain of the self-concept. CONCLUSIONS: This report shows that regular qigong practice could relieve depression, improve self-efficacy and personal well being among elderly persons with chronic physical illness and depression.

Activities of Daily Living↗

PubMed2006

Whole-genome genotyping with the single-base extension assay.

We describe an efficient, accurate and robust whole-genome genotyping (WGG) assay based on a two-color, single-base extension (SBE), single-nucleotide polymorphism (SNP)-scoring step. We report genotyping results for biallelic International HapMap quality control (QC) SNPs using a single probe per locus. We show scalability, throughput and accuracy of the system by resequencing homozygous loci from our 100k Human-1 Genotyping BeadChip.

DNA Primers↗

PubMed2005

A genome-wide scalable SNP genotyping assay using microarray technology.

Oligonucleotide probe arrays have enabled massively parallel analysis of gene expression levels from a single cDNA sample. Application of microarray technology to analyzing genomic DNA has been stymied by the sequence complexity of the entire human genome. A robust, single base-resolution direct genomic assay would extend the reach of microarray technology. We developed an array-based whole-genome genotyping assay that does not require PCR and enables effectively unlimited multiplexing. The assay achieves a high signal-to-noise ratio by combining specific hybridization of picomolar concentrations of whole genome-amplified DNA to arrayed probes with allele-specific primer extension and signal amplification. As proof of principle, we genotyped several hundred previously characterized SNPs. The conversion rate, call rate and accuracy were comparable to those of high-performance PCR-based genotyping assays.

Computational Biology↗

PubMed2005

In vivo confocal scanning laser microscopy of a series of congenital melanocytic nevi suggestive of having developed malignant melanoma.

OBJECTIVE: To determine the utility of confocal scanning laser microscopy (CSLM) in the in vivo evaluation of congenital melanocytic nevi (CMNs) that are suggestive of having developed melanoma. DESIGN: The CMNs suggestive of melanoma by clinical and dermoscopic examination were imaged by CSLM, and the findings correlated with the features seen on dermoscopic and histologic examination. SETTING: Dermatology clinic specializing in pigmented lesions. PATIENTS: Seven patients with clinically irregular small to medium CMNs. INTERVENTIONS: The areas imaged by CSLM were sampled with 3-mm punch biopsy specimens. The entire lesion was subsequently excised. The punch biopsy specimens were step sectioned horizontally to correlate with the CSLM images. Excised samples were step sectioned and processed routinely. Histologic features observed on CSLM were correlated with the features seen on dermoscopic and light microscopic examination. MAIN OUTCOME MEASURE: Correlation of the structures seen using CSLM with the dermoscopic and histologic features of CMNs and melanoma. RESULTS: The CSLM illustrated histologic characteristics of CMNs, including the presence of hyperpigmented keratinocytes, nevus cells, melanophages, and a normal "honeycomb" epidermal architecture. Features suggestive of melanoma were not evident by CSLM in 6 histologically proven benign CMNs. Histologic features associated with melanoma, such as an increased number of intraepidermal atypical melanocytes (pagetoid) and loss of normal epidermal cellular architecture, were identified by CSLM in 1 lesion, which on histologic analysis revealed melanoma in association with a CMN. CONCLUSION: Our results illustrate that CSLM may be useful for clinicopathologic correlations and for the preliminary noninvasive diagnosis of pigmented neoplasms in vivo.

Adolescent↗

PubMed2005

Cerebral vasospasm following intracranial hypotension caused by cerebrospinal fluid leak from an incidental lumbar durotomy. Case report.

The authors report on the unusual case of a patient with intracranial hypotension following an incidental durotomy complicated by an extensive but reversible cerebral vasospasm. Despite the dural tear repair and correction of the intracranial hypotension, the vasospasm ran its course. The precise mechanism of the cerebral vasospasm in this patient is unclear.

Adult↗

PubMed2004

Attenuation of cue-induced cigarette craving and anterior cingulate cortex activation in bupropion-treated smokers: a preliminary study.

In untreated smokers, exposure to cigarette-related cues increases both the intensity of cigarette craving and relative glucose metabolism of the perigenual/ventral anterior cingulate cortex (ACC). Given that treatment with bupropion HCl reduces overall cigarette craving levels in nicotine dependent subjects, we performed a preliminary study of smokers to determine if bupropion HCl treatment attenuates cue-induced cigarette craving and associated brain metabolic activation. Thirty-seven, otherwise healthy smokers (20 untreated and 17 who had received open-label treatment with bupropion HCl) underwent two (18)F-fluorodeoxyglucose positron emission tomography scanning sessions in randomized order--one when presented with neutral cues and the other when presented with cigarette-related cues. Bupropion-treated smokers had smaller cigarette cue-induced increases in craving scores on the Urge to Smoke (UTS) Scale and less activation of perigenual/ventral ACC metabolism from the neutral to the cigarette cue scan than untreated smokers. Thus, in addition to its known effects on spontaneous cigarette craving and withdrawal symptoms, bupropion HCl diminishes cue-induced cigarette craving and appears to attenuate cigarette cue-induced ACC activation. These results are consistent with the known effects of bupropion HCl, including its enhancement of catecholaminergic neurotransmission.

Adult↗

PubMed2004

Mutagenicity of the cytidine analog zebularine in Escherichia coli.

We have examined the mutagenic properties of zebularine, a cytidine analog lacking the amino group at C-4 that has potential use in chemotherapy. Because the hydrate is a strong inhibitor of cytidine deaminase, its use can enhance the potency of other cytosine based compounds such as 5-azacytidine (5AzaC) and cytosine arabinoside (ara-C) that are inactivated by cytidine deaminase. Using the newly developed rpoB/Rifr system in Escherichia coli, we examined base substitution mutations caused by zebularine in the chromosomal rpoB gene. Zebularine is a potent mutagen that causes mainly G : C --> A : T transitions and favors certain hotspots. Mutations are not specific to the rpoB gene, since there is also a strong induction of mutations in the thyA gene. In the absence of mismatch repair, zebularine induces both base substitutions and frame shifts at rates well above those seen in wild-type strains treated with zebularine or in mismatch repair deficient strains without treatment. The nature of these induced mutations indicates that zebularine is stimulating the induction of increased replication errors, in addition to the targeted G : C --> A : T mutations, and that these errors are normally repaired by the mismatch repair system.

Base Pair Mismatch↗

PubMed2004

Induction of human IgM and IgG anti-GM1 antibodies in transgenic mice in response to lipopolysaccharides from Campylobacter jejuni.

Campylobacter jejuni lipopolysaccharides (LPS) are implicated in the development of autoantibodies to GM1 ganglioside in patients with neuropathy following C. jejuni infection. CjLPS bears oligosaccharides that are cross reactive with GM1 ganglioside and presumably exerts its effects via molecular mimicry. To study the mechanisms that are involved in development of the autoantibody response, a transgenic mouse line was developed that expresses an IgM anti-GM1 antibody derived from a patient with multifocal motor neuropathy (MMN). In vivo stimulation of the transgenic mice with C. jejuni lipopolysaccharides (CjLPS), but not of wild-type mice readily elicited high serum titers of anti-GM1 IgM antibodies, followed by IgG anti-GM1 antibodies after two booster injections. In in vitro experiments, CjLPS stimulated the transgenic B-cells at lower concentration than control LPS. The increased sensitivity to CjLPS and the induction of IgG anti-GM1 by CjLPS but not control LPS are consistent with a mechanism of B-cell activation that involves both the LPS and the antigen-specific surface Ig receptors, with possible participation of T-cells.

Animals↗

PubMed2004

Changes in mortality for extremely low birth weight infants in the 1990s: implications for treatment decisions and resource use.

OBJECTIVE: Much has changed in neonatal intensive care unit (NICU) care over the past decade. High-frequency oscillation, inhaled nitric oxide, and antenatal corticosteroids are now widely available. We wondered how these medical advances had affected both the epidemiology and ethics of life and death for extremely low birth weight (ELBW) infants in the NICU. METHODS: We identified 1142 ELBW infants (birth weight [BW] < 1000 g) consecutively admitted to our NICU between 1991 and 2001. We abstracted BW, gestational age, survival or death, and length of stay in the NICU. Statistical analyses were performed by using linear regression and 2-way analysis of variance. RESULTS: Both increasing BW and later year were significantly associated with improved survival. However, for larger ELBW infants, survival was approximately 90% for the entire decade, and large-scale improvement was hardly possible. For smaller infants, greater improvements were both possible and observed, at least early in the decade. From 1991 to 1997, overall ELBW survival increased steadily (approximately 4% per year). However, from 1997 to 2001, there was no significant improvement in survival for ELBW infants. There was no change in the distribution of deaths accounted for by BW subgroups within the ELBW population from 1991 to 2001. Median length of stay for infants who eventually expired before discharge rose from 2 days in 1991 to 10 days in 2001. As a consequence, during the past decade, the percentage of infants whose outcome was "undeclared" by day of life 4 rose from 10% to 20% for ELBW infants overall and to 33% for infants with BWs of 450 to 700 g. The percentage of ELBW NICU bed-days occupied by nonsurvivors remained very low (approximately 7%) from 1991 to 2001. CONCLUSIONS: 1) Fewer infants in all ELBW subgroups are dying, compared with a decade ago, and the improvement has been most prominent for BWs of 450 to 700 g, at which mortality was and remains to be greatest. 2) This progress seems to have slowed, or even stopped, by the end of the decade. 3) Although most NICU nonsurvivors still expire early, doomed infants are lingering longer. 4) Nonsurvivors continue to occupy a constant (and extremely small) fraction of NICU bed-days.

Humans↗

PubMed2003

Inhaled nitric oxide in premature infants with the respiratory distress syndrome.

BACKGROUND: Inhaled nitric oxide improves gas exchange, decreases pulmonary vascular lability, and reduces pulmonary inflammation. We hypothesized that the use of inhaled nitric oxide would decrease the incidence of chronic lung disease and death in premature infants with the respiratory distress syndrome. METHODS: We conducted a randomized, double-blind, placebo-controlled study of the effect of inhaled nitric oxide during the first week of life on the incidence of chronic lung disease and death in premature infants (less than 34 weeks' gestation) who were undergoing mechanical ventilation for the respiratory distress syndrome. Infants were randomly assigned to receive inhaled nitric oxide (10 ppm on day 1, followed by 5 ppm for six days) or inhaled oxygen placebo for seven days. We further randomly assigned the infants in each group to receive intermittent mandatory or high-frequency oscillatory ventilation. RESULTS: A total of 207 premature infants were enrolled. In the group given inhaled nitric oxide, 51 infants (48.6 percent) died or had chronic lung disease, as compared with 65 infants (63.7 percent) in the placebo group (relative risk, 0.76; 95 percent confidence interval, 0.60 to 0.97; P=0.03). There was no significant difference between the nitric oxide and placebo groups in the overall incidence of intraventricular hemorrhage and periventricular leukomalacia (33.3 percent and 38.2 percent, respectively), but the group given inhaled nitric oxide had a lower incidence of severe intraventricular hemorrhage and periventricular leukomalacia (12.4 percent vs. 23.5 percent; relative risk, 0.53; 95 percent confidence interval, 0.28 to 0.98; P=0.04). The type of ventilation had no significant effect on the outcome. CONCLUSIONS: The use of inhaled nitric oxide in premature infants with the respiratory distress syndrome decreases the incidence of chronic lung disease and death.

Administration, Inhalation↗

PubMed2003

Comparative studies of active site-ligand interactions among various recombinant constructs of human beta-amyloid precursor protein cleaving enzyme.

Amyloid precursor protein (APP) cleaving enzyme (BACE) is the enzyme responsible for beta-site cleavage of APP, leading to the formation of the amyloid-beta peptide that is thought to be pathogenic in Alzheimer's disease (AD). Hence, BACE is an attractive pharmacological target, and numerous research groups have begun searching for potent and selective inhibitors of this enzyme as a potential mechanism for therapeutic intervention in AD. The mature enzyme is composed of a globular catalytic domain that is N-linked glycosylated in mammalian cells, a single transmembrane helix that anchors the enzyme to an intracellular membrane, and a short C-terminal domain that extends outside the phospholipid bilayer of the membrane. Here we have compared the substrate and active site-directed inhibitor binding properties of several recombinant constructs of human BACE. The constructs studied here address the importance of catalytic domain glycosylation state, inclusion of domains other than the catalytic domain, and incorporation into a membrane bilayer on the interactions of the enzyme active site with peptidic ligands. We find no significant differences in ligand binding properties among these various constructs. These data demonstrate that the nonglycosylated, soluble catalytic domain of BACE faithfully reflects the ligand binding properties of the full-length mature enzyme in its natural membrane environment. Thus, the use of the nonglycosylated, soluble catalytic domain of BACE is appropriate for studies aimed at understanding the determinants of ligand recognition by the enzyme active site.

Alzheimer Disease↗

PubMed2003

End-stage renal disease in the Asian-Pacific region.

Information on end-stage renal disease (ESRD) is important in assisting health care providers in planning renal replacement therapy. A questionnaire was sent to various countries in the Asian Pacific region and 10 countries responded. Data from Australia and New Zealand was obtained from their registry report. The questionnaire requested information on incidence, prevalence, transplantation rate, demographic data, causes of ESRD, causes of death, and mortality rates for the years 1998 to 2000. All the countries surveyed had national registries and there was a greater than 90% response rate in 7 of 12 countries. The incidence and prevalence rates of ESRD were linked to funding of dialysis, with higher reported rates in countries where dialysis was totally or heavily subsidized by the government. There was an increase in both incidence and prevalence rates between 1998 and 2000, with the mean annual percentage increase of 1.2% to 14.1% for incidence and 4.2% to 17.3% for prevalence. Diabetic nephropathy was the most common cause of ESRD in 9 of the 12 countries surveyed and 6 of the 12 countries had greater than 35% of their dialysis patients age 60 years and older. Peritoneal dialysis (PD) use varied between 3.9% to 81% of the dialysis population and reflected the health care policies of the individual countries. The transplantation rate was influenced by socioeconomic, religious, and cultural attitudes and varied between 3.1 per million population (pmp) to 32 pmp with the percentage of cadaveric transplants ranging between 0% of 85% of total transplants. Cardiovascular mortality remained the most common cause of death in the ESRD patients. Collaboration between the various national registries in the form of specific international studies may yield useful information of ESRD patients in the Asian-Pacific region.

Asia↗

PubMed2002

Serial assessment of mortality in the neonatal intensive care unit by algorithm and intuition: certainty, uncertainty, and informed consent.

OBJECTIVES: Does predictive power for outcomes of neonatal intensive care unit (NICU) patients get better with time? Or does it get worse? We determined the predictive power of Score for Neonatal Acute Physiology (SNAP) scores and clinical intuitions as a function of day of life (DOL) for newborn infants admitted to our NICU. METHODS: We identified 369 infants admitted to our NICU during 1996-1997 who required mechanical ventilation. We calculated SNAP scores on DOL 1, 3, 4, 5, 7, 10, 14, 21, 28, and weekly thereafter until either death or extubation. We also asked nurses, residents, fellows, and attendings on each day of mechanical ventilation: "Do you think this child is going to live to go home to their family, or die before hospital discharge?" RESULTS: Two thousand twenty-eight SNAP scores were calculated for 285 infants. On DOL 1, SNAP for nonsurvivors (24 +/- 8.7 [standard deviation]) was significantly higher than SNAP for survivors (13 +/- 6.1). However, this difference diminished steadily and by DOL 10 was no longer statistically significant (12.7 +/- 4.9 vs 10.0 +/- 4.8). On each NICU day, at all ranges of SNAP scores, there were at least as many infants who would ultimately survive as would die. Consequently, the positive predictive value of any SNAP value for subsequent mortality was <0.5 on all NICU days. Prediction profiles were obtained for 230 ventilated infants reflecting over 11 000 intuitions obtained on 2867 patient days. One hundred fifty-seven (81%) of 192 survivor profiles displayed consistent accurate prediction profiles-at least 90% of their NICU ventilation days were characterized by 100% prediction of survival. Twenty-five (13%) of 192 surviving infants survived somewhat unexpectedly; that is, after at least 1 day characterized by at least 1 estimate of "death." Thirty-three (60%) of the 55 nonsurvivors died before DOL 10. Eighty-two percent of the prediction profiles for these early dying infants were homogeneous, dismal, and accurate. Twenty-two (40%) of the 55 nonsurvivors died after DOL 10. Seventeen (78%) of these 22 late-dying infants were predicted to live by many observers on many hospital days. Sixty-one (30%) of 230 profiled patients had at least 1 NICU day characterized by at least 1 prediction of death; 26/61 (43%) of these patients were incorrectly predicted; that is, they survived. Seventeen infants who were predicted to die during but survived nonetheless were assessed neurologically at 1 year. Fourteen (82%) of these 17 were not neurologically normal-8 were clearly abnormal, 1 suspicious, and 5 had died. CONCLUSIONS: If absolute certainty about mortality is the only criterion that can justify a decision to withhold or withdraw life-sustaining treatment in the NICU, these data would make such decisions difficult on the first day of life, and increasingly problematic thereafter. However, if we acknowledge that medicine is inevitably an inexact science and that clinical predictions can never be perfect, we can ask the more interesting question of whether good but less-than-perfect predictions of imprecise but ethically relevant clinical outcomes can still be useful. We think that they can-and that they must.

Age Factors↗

PubMed2000

Regulation of MDR1 gene expression: emerging concepts.

Drug resistance genes, such as MDR1, involved in drug efflux, and their regulation have been the subject of intense research efforts in the past 10 years. Many factors and cellular signalling pathways play a role in the regulation of MDR1 gene expression. Commonly used chemotherapeutic agents activate in vitro and in vivo general stress response pathways, potential targets of which include MDR1 and other drug resistance genes. The contribution of these agents to the emergence of drug-resistant tumour cells is of concern. Recent evidence points to a role for the epigenetic regulation of MDR1 gene expression. The identification of key components in the DNA methylation/chromatin system of gene regulation may in time lead to more informed and targeted approaches to treating drug-resistant tumours. Copyright 2000 Harcourt Publishers Ltd.

Journal Article↗

PubMedDate not supplied

Galantamine facilitates acquisition of hippocampus-dependent trace eyeblink conditioning in aged rabbits.

Cholinergic systems are critical to the neural mechanisms mediating learning. Reduced nicotinic cholinergic receptor (nAChR) binding is a hallmark of normal aging. These reductions are markedly more severe in some dementias, such as Alzheimer's disease. Pharmacological central nervous system therapies are a means to ameliorate the cognitive deficits associated with normal aging and aging-related dementias. Trace eyeblink conditioning (EBC), a hippocampus- and forebrain-dependent learning paradigm, is impaired in both aged rabbits and aged humans, attributable in part to cholinergic dysfunction. In the present study, we examined the effects of galantamine (3 mg/kg), a cholinesterase inhibitor and nAChR allosteric potentiating ligand, on the acquisition of trace EBC in aged (30-33 months) and young (2-3 months) female rabbits. Trace EBC involves the association of a conditioned stimulus (CS) with an unconditioned stimulus (US), separated by a stimulus-free trace interval. Repeated CS-US pairings results in the development of the conditioned eyeblink response (CR) prior to US onset. Aged rabbits receiving daily injections of galantamine (Aged/Gal) exhibited significant improvements compared with age-matched controls in trials to eight CRs in 10 trial block criterion (P = 0.0402) as well as performance across 20 d of training [F(1,21) = 5.114, P = 0.0345]. Mean onset and peak latency of CRs exhibited by Aged/Gal rabbits also differed significantly [F(1,21) = 6.120/6.582, P = 0.0220/0.0180, respectively] compared with age-matched controls, resembling more closely CR timing of young drug and control rabbits. Galantamine did not improve acquisition rates in young rabbits compared with age-matched controls. These data indicate that by enhancing nicotinic and muscarinic transmission, galantamine is effective in offsetting the learning deficits associated with decreased cholinergic transmission in the aging brain.

Acetylcholine↗