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Biomedical subjects

H Lee

Publications and source records attributed to H Lee.

At least 343 records · Page 19Linked to original sources
PubMed1999

A comparison of different bedside tests for essential tremor.

OBJECTIVE: To compare the performance of different bedside tests for essential tremor (ET). BACKGROUND: Numerous tests (for example, writing, arm extension) may be used to elicit tremor in patients with ET. In large epidemiological surveys in which many patients must be evaluated efficiently, knowledge about the relative performance of these tests would be useful. METHODS: 154 subjects (42 with ET and 112 control subjects) were part of a community-based family study of ET in northern Manhattan, New York. Subjects underwent a tremor interview and a videotaped tremor examination which included six different tests for ET. Each of the six tests was performed with both the dominant and the nondominant arms. Two neurologists reviewed the videotaped examination and rated the severity of tremor during each test. Tremor ratings were 0 (none), +1 (mild), +2 (moderate), and +3 (severe). RESULTS: Among ET cases, there was considerable variation in the performance of each bedside test. With some tests (nondominant arm extension), as few as 48.8% of the ratings were >+2 and 29.8% of the ratings were 0 (no tremor). With other tests (finger-to-nose maneuver using nondominant arm), as many as 88.1% of the ratings were >+2 and only 2.4% were 0. Among the control subjects, there was also considerable variation in the performance of each test. Using some tests (finger-to-nose maneuver using nondominant arm), as many as 26.3% of the ratings were >+2, 72.8% were >+1 tremor, and only 27.2% of the ratings were 0. CONCLUSIONS: The performance of the tests varied considerably. In settings in which only one or two tests must be selected to screen a population, tests that are most likely to be abnormal in an ET case (finger-to-nose maneuver) could be used. In settings in which it is also desirable to exclude normal subjects, tests such as sustained arm extension, pouring water, or drawing a spiral could be used. Data regarding the performance of bedside tests for diagnosing ET are central to the design of research strategies for the clinical evaluation of patients with ET.

Aged↗
PubMed1999

Genotoxicity of fumes from heated cooking oils produced in Taiwan.

Epidemiologic investigations of lung cancer among Taiwanese nonsmoking women have found that exposure to fumes from cooking oils may be an important risk factor. Fume samples from three different commercial cooking oils (lard, soybean, and peanut oils) often used in Taiwan for preparing Chinese meals were collected for genotoxicity analysis in SOS chromotest and sister chromatid exchange (SCE) assays. The induction factors of the SOS chromotest in Escherichia coli PQ 37 were dependent on the concentrations of lard and soybean cooking oil extracts without S9 mix. In addition, when CHO-K1 cells were exposed to condensates of cooking oil fumes for 12 h, SCEs showed a dose-related increase in extracts of lard and soybean oil fumes. This result provides experimental evidence and is in accordance with the findings of epidemiologic studies that women exposed to the emitted fumes of cooking oils are at an increase risk of contracting lung cancer.

Animals↗
PubMed1999

Effects of chronic treatment with typical and atypical antipsychotic drugs on the rat striatum.

Human MRI studies have demonstrated that treatment with typical antipsychotics may increase the volume of the caudate nucleus while clozapine treatment is associated with either no change or a reversal of the previous volume increase. In this study four groups of seven rats were treated for 8 months with either the typical antipsychotic haloperidol, the atypical antipsychotic clozapine, the D2/D3 receptor antagonist raclopride, or vehicle (plain drinking water). Striatal sections were prepared using D1-like and D2-like receptor ligand autoradiography. Images (4-6 sections per rat, per ligand) were digitized and the area of the striatum was measured on each section. Rats treated with haloperidol did not have a larger mean striatum area than the control group on either D1- or D2-like ligand autoradiograms. Using the D2-like ligand autoradiograms, the clozapine treated animals had a smaller mean striatum area than the control group. Mean left striatum area was larger than mean right striatum area in each treatment group and in the control group. In contrast to the MRI findings reported in schizophrenia, the area of the striatum was not increased in rats treated with typical antipsychotic agents, but the clozapine-associated area reduction may parallel the clinical studies.

Animals↗
PubMed1999

Differential response to benzo[A]pyrene in human lung adenocarcinoma cell lines: the absence of aryl hydrocarbon receptor activation.

Benzo[a]pyrene (B[a]P) has been shown to produce DNA adducts and to initiate pulmonary carcinogenesis in animals. We observed differential susceptibility to B[a]P in two human lung adenocarcinoma cell lines, A427 and CL3. DNA adducts were induced by B[a]P treatment in CL3 cells, however, A427 cells were much less responsive to B[a]P treatment. Cytochrome P450 1A1 (CYP1A1) is involved in bioactivation of B[a]P in nonhepatic tissues. Cotreatment with alpha-naphthoflavone, a CYP1A1 inhibitor, abolished DNA adduct formation by B[a]P in CL3 cells. Nevertheless, CYP1A1 inducer beta-naphthoflavone, enhanced DNA adduct formation by B[a]P in both A427 and CL3 cells. Both enzyme activity and mRNA levels of CYP1A1 were highly induced by 1 or 10 microM B[a]P treatment for 24 hr in CL3 cells but not in A427 cells. Protein levels of AhR and aryl hydrocarbon receptor nuclear translocator (Arnt) were similar in A427 and CL3 cells before B[a]P treatment. However, B[a]P induced a retarded band with the [32P]-dioxin responsive element in CL3 cells, but not in A427 cells. This study demonstrated that variation in AhR-mediated CYP1A1 induction contributes to differential susceptibility to B[a]P-DNA adduct formation in human lung cells. Since AhR and/or Arnt function is impaired in A427 cells, this cell line offers a model for investigating the repression mechanisms of CYP1A1 induction by B[a]P in lung cells.

Adenocarcinoma↗
PubMed1999

Efficacy of oral sildenafil in patients with erectile dysfunction after radiotherapy for carcinoma of the prostate.

OBJECTIVES: To determine the efficacy of sildenafil for patients with erectile dysfunction after radiotherapy for localized prostate cancer. METHODS: Fifty patients with erectile dysfunction after radiotherapy were treated with sildenafil. Their median age was 68 years (range 54 to 78). All were treated with a three-dimensional conformal external beam radiotherapy approach, and the median dose prescribed to the planning target volume was 75.6 Gy. Patients were initially given 50 mg of sildenafil and instructed to use the medication on at least three occasions. They were then contacted to ascertain the efficacy of and tolerance to the medication. RESULTS: Significant improvement in the firmness of the erection after sildenafil was reported in 37 patients (74%), 2 (4%) had partial improvement, and 11 (22%) had no response. Significant improvement in the durability of the erection was reported in 33 patients (66%), 3 (6%) had partial improvement, and 14 (28%) reported no improvement. Patients with partial or moderate erectile function before using sildenafil were more likely to benefit from the medication compared with those with absent function. Among 29 patients with erections classified as partial after radiotherapy, 26 (90%) had a significant response to the medication. In contrast, only 11 (52%) of 21 with erections classified as flaccid after radiotherapy had a significant response to the medication (P = 0.007). CONCLUSIONS: Sildenafil improved erectile function in greater than two thirds of patients with postradiotherapy impotence. Patients with less severe dysfunction are most likely to benefit from this intervention.

Administration, Oral↗
PubMed1999

Three sample preparation protocols for polymerase chain reaction based detection of Cryptosporidium parvum in environmental samples.

Cryptosporidium parvum is a protozoan parasite responsible for an increasing number of outbreaks of gastrointestinal illness worldwide. In this report, we describe development of sample preparation protocols for polymerase chain reaction (PCR)-based detection of C. parvum in fecal material and environmental water samples. Two of these methods were found adequate for isolation of Cryptosporidium DNA from filtered water pellet suspensions. The first involved several filtration steps, immunomagnetic separation and freeze-thaw cycles. The second method involved filtration, addition of EnviroAmp lysis reagent, freeze-thaw cycles and precipitation of the DNA with isopropanol. Using nested PCR, we detected 100 oocysts/ml of filtered water pellet suspension, with either of the above sample preparation procedures. Nested PCR increased sensitivity of the assay by two to three orders of magnitude as compared to the primary PCR. The detection limit for seeded fecal samples was 10-fold higher than for filtered environmental water pellet suspension. Nested PCR results showed 62.4 and 91.1% correlation with immunofluorescence assay (IFA) for fecal samples and filtered environmental water pellet suspensions, respectively. This correlation decreased to 47.2% and 44.4%, respectively, when only IFA positive samples were analyzed. However, in fecal samples contaminated with a high number (> 10(5)/g) of C. parvum oocysts, this correlation was 100%.

2-Propanol↗
PubMed1999

Applications of the green fluorescent protein as a molecular marker in environmental microorganisms.

In this review, we examine numerous applications of the green fluorescent protein (GFP) marker gene in environmental microbiology research. The GFP and its variants are reviewed and applications in plant-microbe interactions, biofilms, biodegradation, bacterial-protozoan interactions, gene transfer, and biosensors are discussed. Methods for detecting GFP-marked cells are also examined. The GFP is a useful marker in environmental microorganisms, allowing new research that will increase our understanding of microorganisms in the environment.

Biotechnology↗
PubMed1999

PCR-based quantitation of Cryptosporidium parvum in municipal water samples.

A PCR method for the quantitation of Cryptosporidium parvum oocysts in municipal drinking water samples was investigated. Quantitative PCR uses an internal standard (IS) template with unknown target numbers to compare to standards of known concentrations in a standard curve. The IS template was amplified using the same primers used to amplify a portion of a 358 bp gene fragment that encodes a repetitive oocyst wall protein in C. parvum. Municipal water samples spiked with known numbers of C. parvum oocysts were tested by quantitative PCR using the IS and the Digene SHARP Signal System Assay for PCR product detection. The absorbance readings for target DNA and IS templates versus the number of molecules of the target DNA were plotted to generate standard curves for estimating oocyst numbers. The method allowed the quantitation of oocysts from log 3 to log 5 spiked into municipal water samples.

Animals↗
PubMed1999

Cytochrome P4502E1 genetic polymorphisms and lung cancer in a Taiwanese population.

Cytochrome P4502E1 (CYP2E1) is involved in metabolic activation of carcinogenic nitrosamines, benzene and low molecular weight halogenated hydrocarbons. In this study, we assessed the association between CYP2E1 RsaI and DraI genetic polymorphisms and lung cancer in a Taiwanese population. The RsaI genotype distribution was significantly different between 119 lung cancer patients and 231 non-cancer controls. The homozygote variants of RsaI genotypes were more common in controls (6.9%) than in lung cancer patients (0.8%). The estimated odds ratio (OR) was 0.11 (95% confidence interval (CI), 0.01-0.87). After adjusting for age, sex, and smoking status, the OR was 0.12 (95%, CI, 0.02-0.95). This is the first observation of a positive association between this locus and lung cancer in an Asian population. No significant differences in CYP2E1 DraI genotype distributions were found between cases and controls. The results of this study indicate that CYP2E1 RsaI polymorphism, but not DraI polymorphism, may contribute to the development of lung cancer in Taiwan.

Cytochrome P-450 CYP2E1↗
PubMed1999

The relationship between tobacco access and use among adolescents: a four community study.

The objective of this study was to examine the effectiveness of a longitudinal community intervention on the reduction of tobacco sales to minors and subsequent effects on tobacco consumption by youths. The study was conducted in Monterey County, CA. Four rural communities were randomized into treatment and comparison arms of the study and middle and high school students in each of these communities completed surveys assessing knowledge, attitude, and behavior. The main outcome measures were retail tobacco sales to minors as measured through store visits (tobacco purchase surveys) and self-reported consumption of tobacco. Over a three-year period, a diverse array of community interventions were implemented in the intervention communities. These included community education, merchant education, and voluntary policy change. In the treatment communities, the proportion of stores selling tobacco to minors dropped from 75% at baseline to 0% at the final post-test. In the comparison communities, the proportions were 64% and 39%, respectively. Although the availability of tobacco through commercial outlets was reduced substantially in intervention communities, youths reported still being able to obtain tobacco from other sources. Predicted treatment effects on reported use of tobacco among youths were observed cross-sectionally and longitudinally for younger students (7th graders). The intervention did not impact tobacco use among older students (9th and 11th graders) although the trends were in the predicted direction for 9th graders. A significant intervention effect was found for sex--females in the intervention communities were less likely to use tobacco post-intervention than females in the comparison communities. Tobacco sales to minors can be reduced through a broad-based intervention. To prevent or reduce tobacco use by youths, however, multiple supply-and demand-focused strategies are needed.

Adolescent↗
PubMed1999

Mitotic checkpoint inactivation fosters transformation in cells lacking the breast cancer susceptibility gene, Brca2.

The murine Brca2 gene encodes a nuclear protein implicated in DNA repair. Brca2 behaves as a tumor suppressor, but paradoxically, its truncation causes proliferative arrest and spontaneous chromosomal damage. Here, we report that inactivation of cell cycle checkpoints responsive to mitotic spindle disruption, by mutant forms of p53 or Bub1, relieves growth arrest and initiates neoplastic transformation in primary cells homozygous for truncated Brca2. Tumors from Brca2-deficient animals exhibit dysfunction of the spindle assembly checkpoint, accompanied by mutations in p53, Bub1, and Mad3L. The chromosomal aberrations precipitated by Brca2 truncation can be suppressed by mutant forms of Bub1 and p53. Thus, inactivating mutations in mitotic checkpoint genes likely cooperate with BRCA2 deficiency in the pathogenesis of inherited breast cancer, with important implications for treatment.

Animals↗
PubMed1999

Cytotoxic polyacetylenes from the marine sponge Petrosia sp.

Three C46 (1-3) and three C30 (4-6) polyacetylenic alcohols with cytotoxic activity against a small panel of human solid-tumor cell lines have been isolated from the marine sponge Petrosia sp. Although compound 1 was identified as the stereoisomer of petrocortyne A, the structures of compounds 2-5 have not been previously reported and were established by spectral methods. Compound 6 was identified as the known compound petrosiacetylene D. The stereochemistry of compounds 1-5 was determined by the modified Mosher's method.

Acetylene↗
PubMed1999

Cloning and characterization of Chinese hamster CDC7 (ChCDC7).

The Cdc7 serine/threonine kinase is essential for entry into and to traverse through S phase. We have cloned the putative Chinese hamster CDC7 (ChCDC7) cDNA that is capable of encoding a protein of 572 amino acids with predicted molecular mass of 62.6 kDa. The ChCdc7 protein includes all 11 kinase domains that are conserved among the Cdc7-related protein kinases. In addition, the ChCdc7 protein kinase contains at least two kinase inserts that show substantial identity to those of huCdc7p. Overall, ChCdc7p shares 81, 56, 30, and 27% amino acid sequence identity with the Cdc7-related proteins of human, Xenopus, Saccharomyces cerevisiae, and Schizosaccharomyces pombe, respectively. Although the levels of ChCDC7 mRNA and protein are relatively constant throughout the cell cycle in the cycling cells, they are extremely low in the cells synchronized in the quiescent stage (i.e., G0). When cells in G0 are released into the cell cycle, the levels of ChCDC7 mRNA and protein increase slowly until the cells reach the G1/S border, at which time the increase is rapid. This suggests that a number of signal transduction pathways may have to be activated prior to CDC7 gene expression. Interestingly, the ChCdc7-GFP fusion protein formed discrete granules in the nuclei of cells arrested in early S phase by aphidicolin, raising the possibility that ChCdc7p is part of the "replication factory."

Amino Acid Sequence↗
PubMed1999

Combinatorial peptide on-resin analysis: optimization of static nanoelectrospray ionization technique for sequence determination.

The optimizations of static nanoelectrospray parameters to determine peptide or mimetic sequences released from resin were explored. Several different manufacturers of probe tips were utilized and a method was developed for the direct analysis of bead-bound peptides by nanoelectrospray. The method involved minimum sample handling to assure maximum recovery from individual beads. Parameters that were explored included an inside and outside wash of the probe tip, the distance from the probe housing to the probe tip, source temperature, drying gas flow, individual tips and presence of beads. The same soluble synthetic peptide was used in all comparisons, which had a molecular weight of 717 amu. The discovery of the sequence of a bead-bound peptide was achieved. The parameters that were found to effect signal were outside wash, presence of bead and distance. There was the need for pneumatic assist to initiate electrospray on some occasions, although this generally resulted in unsatisfactory performance.

Chemistry Techniques, Analytical↗
PubMed1999

Chlorophenol and nitrophenol metabolism by Sphingomonas sp UG30.

Sphingomonas sp UG30 is a pentachlorophenol (PCP)-degrading bacterial strain capable of degrading several nitrophenolic compounds, including p-nitrophenol (PNP), 2,4-dinitrophenol (2,4-DNP), p-nitrocatechol and 4,6-dinitro-o-cresol (DNOC). The ability to degrade both chlorophenolic and nitrophenolic compounds is probably not restricted to UG30, but may also be possessed by other pentachlorophenol-degrading Sphingomonas spp. The interesting question arises as to whether there is any point of convergence between the initial pathways of PCP and nitrophenol degradation in these microorganisms. There is some experimental evidence that PCP-4-monooxygenase is involved in metabolism of both p-nitrophenol and 2,4-dinitrophenol. Further studies are needed to confirm this and to examine the role(s) of other PCP-degrading enzymes in nitrophenol metabolism by this microorganism. In this paper, we review some of the taxonomic, biochemical, physiological and ecological properties of Sphingomonas sp UG30 with respect to biodegradation of PCP and nitrophenolic compounds.

Journal Article↗