Biomedical subjects

H Lee

Publications and source records attributed to H Lee.

At least 991 records · Page 55Linked to original sources

PubMedDate not supplied

Isolation of vindoline from Catharanthus roseus by supercritical fluid extraction.

Vindoline was extracted from the leaves of Catharanthus roseus over the ranges of 35-70 degrees C and 100-300 bar using supercritical carbon dioxide with and without the addition of 3 wt % ethanol as a cosolvent. The vindoline contents in the extracts were determined by HPLC and identified by LC/MS. The remarkable highest vindoline concentration, 58 wt %, was obtained at the lowest temperature, 35 degrees C, and the highest pressure, 300 bar, of this study. The use of a cosolvent only slightly improved the extraction yields or selectivities at some experimental conditions.

Biotechnology↗

PubMedDate not supplied

Conjugation of trypsin by temperature-sensitive polymers containing a carbohydrate moiety: thermal modulation of enzyme activity.

Novel temperature-sensitive polymers containing glucose units in their backbone were synthesized and covalently conjugated to trypsin. A series of copolymers based on N-isopropylacrylamide (NIPAAm) and glucosyoxylethyl methacrylate (GEMA) were prepared by using 4,4'-azobis(4-cyanovaleric acid) as an initiator, which resulted in one terminal carboxylic acid group per polymer chain. The polymers were conjugated to primary amine groups of trypsin with water-soluble carbodiimide as a coupling agent, which led to a star-shaped conformation. The polymer-enzyme conjugation was confirmed and characterized by size exclusion and reversed-phase chromatography. Almost of all amine groups in trypsin available for the conjugation were consumed and, consequently, a very dense layer of copolymers was actually coated around the enzyme surface. The conjugated enzymes exhibited reversible precipitation/resolubilization behaviors over a wide range of temperatures, depending on the content of GEMA in the copolymer. They also demonstrated no detectable self-digestion (autolysis) process, but the unconjugated enzyme showed very severe autolysis that led to a rapid inactivation in aqueous solution. When bovine serum albumin was used as a substrate, the protein substrate was not attacked by the conjugated enzyme, but completely digested by the unconjugated enzyme. This result was presumably caused by a steric repulsion process of the attached polymer chains around the enzyme toward the protein substrate. However, the enzyme retained sufficient activity against a low molecular weight substrate. Interestingly, the conjugated enzymes demonstrated very peculiar enzyme activity-temperature profiles, with two apparent optimal temperatures, indicating that a temperature-controlled collapse and flocculation of the copolymers around the enzyme surface modulated the mass transfer rates of substrate to the active site of the enzyme. The conjugated enzymes also exhibited improved thermal stability with increasing the amount of carbohydrate units in the polymer chain.

Animals↗

PubMedDate not supplied

Spectroscopic characterization of syn-5-methylchrysene 1,2-dihydrodiol 3,4-epoxide-deoxyribonucleoside adducts.

Eight deoxyribonucleoside adducts formed from reactions of syn-5-methylchrysene 1,2-dihydrodiol 3,4-epoxide with DNA or with nucleotides were characterized spectroscopically. The adducts arose from both cis and trans opening of the epoxide ring at C4 by the amino group of either deoxyadenosine or deoxyguanosine residues. NMR data indicated that the partially saturated 1,2,3,4-ring of the hydrocarbon residue adopted a boatlike conformation, with the purine residue being disposed pseudoaxially in all adducts. The cis and trans assignments for epoxide ring opening were readily made from coupling constants. Quantitatively, cis adducts predominated over trans adducts in both DNA and nucleotide reactions. Whereas deoxyadenylic acid appeared to trap this dihydrodiol epoxide more efficiently than deoxyguanylic acid, reaction with DNA led to more extensive reaction with deoxyguanosine than with deoxyadenosine residues.

Carcinogens↗

PubMedDate not supplied

Direct synthesis and identification of benzo[a]pyrene diol epoxide-deoxyguanosine binding sites in modified oligodeoxynucleotides.

Adducts derived from the reaction of the benzo[a]pyrene metabolite model compound (+)-anti-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene [(+)-BPDE] with the single-stranded oligodeoxynucleotide 5'-d(TATGCGTAT) were obtained according to direct synthesis techniques described earlier [Cosman, M., Ibanez, V., Geacintov, N. E., and Harvey, R. G. (1990) Carcinogenesis 11, 1667-1672]. Four major adducts, involving trans and cis addition (trans/cis adduct ratio approximately 4.5) of (+)-BPDE to the exocyclic amino groups of guanines G4 and G6 (the numbers denote the positions of the guanines counted from the 5'-side) were obtained. These adducts can be separated from one another by reverse-phase high-performance liquid chromatography methods. The site of BPDE binding on either G4 or G6 can be determined from the electrophoresis band patterns on 20% polyacrylamide gels of the BPDE-modified oligonucleotides subjected to the G+A and G Maxam-Gilbert strand cleavage reactions [Maxam, A. M., and Gilbert, W. (1980) Methods. Enzymol. 65, 499-560]. The electrophoresis gel band patterns are different for unmodified DNA and the two different BPDE-modified oligonucleotides because (1) the strand cleavage fragments bearing BPDE residues migrate slower than the corresponding fragments derived from the unmodified oligonucleotide and (2) strand cleavage tends to be inhibited on the 5'-sides of BPDE-modified guanines in the G+A, but not the G reaction.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMedDate not supplied

Reaction with DNA and mutagenic specificity of syn-benzo[g]chrysene 11,12-dihydrodiol 13,14-epoxide.

The spectroscopic characterization of purine deoxyribonucleoside adducts derived from the fjord-region syn-benzo[g]chrysene 11,12-dihydrodiol 13,14-epoxide and the mutagenic specificity of the latter compound for the supF gene in the pSP189 shuttle vector are described. This dihydrodiol epoxide preferentially forms adducts with deoxyadenosine residues in DNA and is preferentially opened trans in reactions with DNA or with deoxyribonucleotides. In common with other fjord-region syn-dihydrodiol epoxides, the most frequently observed mutational changes were A-->T and G-->T changes. This hydrocarbon dihydrodiol epoxide is structurally similar to syn-benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxide but has an additional benzene ring annelated distant from the reaction center. As anticipated, there were some common features in the chemistry and mutagenicities of these two compounds, but there were also substantive differences which indicate factors of importance in controlling reactions of these kinds of compounds with DNA.

Animals↗

PubMedDate not supplied

Stereoselectivity of activation of 7,12-dimethylbenz[a]anthracene- 3,4-dihydrodiol to the anti-diol epoxide metabolite in a human mammary carcinoma MCF-7 cell-mediated V79 cell mutation assay.

7,12-Dimethylbenz[a]anthracene (DMBA), one of the most carcinogenic polycyclic aromatic hydrocarbons in rodent bioassays, is metabolically activated in many tissues to "bay-region" DMBA-3,4-diol-1,2-epoxides (DMBADE). Unlike benzo[a]pyrene, for which the high biological activity of the (7R,8S)-diol-(9S,10R)-epoxide has been established, the low chemical stability of anti-DMBADE has made it impossible to evaluate the role of specific stereoisomers in the biological activity of DMBA. In order to characterize the role of formation of DMBADE diastereomers in the induction of mutations, postlabeling assays using [35S]phosphorothioate with adduct separation by HPLC and immobilized boronate chromatography analyses were developed to allow separation and quantitation of DNA adducts formed from each stereoisomer of DMBADE. In DMBA-treated hamster embryo cell cultures, large quantities of three major adducts (anti-DMBADE-deoxyguanosine, anti-DMBADE-deoxyadenosine, and syn-DMBADE-deoxyadenosine) along with five minor adducts were completely resolved and quantitated. The DNA isolated from a human mammary carcinoma MCF-7 cell-mediated V79 cell mutation assay treated with increasing doses of racemic DMBA-3,4-dihydrodiol contained large amounts of two anti-DMBADE-DNA adducts. The anti-DMBADE adducts accounted for more than 90% of the total adducts at all doses. The number of 6-thioguanine-resistant mutants was proportional to the amount of anti-DMBADE-DNA adducts.(ABSTRACT TRUNCATED AT 250 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗

PubMedDate not supplied

The prevalence of antibody to HTLV-I/II in United States plasma donors and in United States and French hemophiliacs.

Antibody to HTLV-I/II was detected in 19 (0.3%) of 6286 plasma donors from five regions of the United States (US). This seroprevalence rate is approximately 10 times that in whole blood donors. The regional distribution of infection was as follows: Southwest, 0.68 percent; Southeast, 0.45 percent; Midwest, 0.28 percent; Northwest, 0.1 percent; and Northeast, 0.0 percent. Rates of HTLV-I/II infection in blacks (0.74%) and Hispanics (0.66%) were higher (both, p less than 0.001) than those in whites (0.08%). All 19 infected units were donated by subjects aged 30 or older, even though 52.9 percent of the donations came from persons less than 30 years old. Equal rates of HTLV-I/II infection were found in men (0.31%) and women (0.29%). No HTLV-I/II antibody was detected in 154 French and 25 US hemophiliacs who were transfused regularly with noninactivated plasma or its derivatives. This suggests that the transfusion of HTLV-I/II-seropositive plasma products does not transmit the viral infection.

Blood Donors↗

PubMedDate not supplied

Human T-cell lymphotropic virus in volunteer blood donors.

Serum samples collected in 1985 and 1986 from 18,257 donors to the Greater New York Blood Program were screened by enzyme-linked immunoassay for antibody to human T-cell lymphotropic virus (anti-HTLV). Fifteen samples (0.08%) were confirmed positive: 7 by radioimmunoprecipitation assay (RIPA) alone, 6 by Western blot alone, and 2 by combined results from both tests. One donor, whose original test result was uninterpretable because multiple nonspecific bands were present on RIPA, clearly tested positive on subsequent specimens. Follow-up testing of individuals with this type of result may be needed to resolve their HTLV status. Anti-HTLV prevalence increased with age and was significantly more common in black or Hispanic donors and in those born in the Caribbean than in other donors. All anti-HTLV-positive donors were negative for antibody to HIV-1, and only one donor (7% of those positive) would have been excluded by any of the routine donor screening tests used at that time.

Blood↗

PubMedDate not supplied

Effects of a 12-week cardiac rehabilitation exercise program on motivation and health-promoting lifestyle.

OBJECTIVE: The purpose of this study was to determine the effects of a 12-week cardiac rehabilitation exercise program on the motivation and lifestyle of persons recovering from a recent heart attack or cardiac-related procedures. DESIGN: The study design was a pretest and posttest quasi-experimental, nonrandom assignment. SETTING: The study was conducted at 4 cardiac rehabilitation centers in Northeast Ohio. SUBJECTS: The study included 57 participants in a cardiac rehabilitation exercise program (mean age = 64 years) and 57 comparisons (mean age = 64.6 years) who recently had a heart attack or underwent cardiac-related procedures. OUTCOME MEASURE: Motivation and health-promoting lifestyle were measured. INTERVENTION: A 12-week cardiac rehabilitation exercise program for small groups of participants (fewer than 12 persons) was conducted. The program provided arm and leg exercises 3 times a week for 30 to 60 minutes per session at an intensity of 60% to 90% of the maximum heart rate. RESULTS: Analysis of covariance was used to analyze the data. After controlling for education, income, and pretest scores, the exercise group scored significantly higher than the comparison group in most motivation-related variables. Regarding lifestyle, after adjusting for the control variables both groups showed positive changes during the 12-week period, but no significant difference was found between the 2 groups in overall lifestyle. CONCLUSION: The findings of the study confirmed that motivational variables were modifiable. Thus, when developing health promotion programs for initiating and maintaining a healthy lifestyle, the relative importance of different motivational variables should be considered.

Adult↗

PubMedDate not supplied

Expression of Wilms tumor gene (WT1) in children with acute leukemia.

Wilms tumor gene (WT1) expression occurs in various malignancies including adult leukemia. WT1 expression was studied in children with acute leukemia according to morphological types and immunophenotypes. RT-PCR was used to examine relative level of WT1 transcripts from the peripheral blood of 15 children diagnosed with acute leukemia: 12 acute lymphoblastic leukemias (ALLs) and 3 acute myelogenous leukemias (AMLs); 8 ALLs newly diagnosed, 2 ALLs in first marrow relapse, 2 ALLs in remission over 2 years, 2 AMLs newly diagnosed, and 1 AML in second marrow relapse. Six healthy adult volunteers were studied for controls. WT1 was detectable in 7 out of 10 ALLs and all 3 AMLs, but not in 2 ALLs in remission and the controls. The expression levels were higher for AMLs than for ALLs. According to the types of ALL, WT1 was detectable in 2 out of 2 non-T group II, 4 out of 6 non-T group III, but not in one CD20+ non-T group IV, while one T-ALL showed a relatively high level. WT1 expression was detectable more frequently in ALL-L2 than in ALL-L1 and with higher levels for ALL-L2. WT1 expression was frequently noted in children with acute leukemia. The results suggest that WT1 transcripts may prove to be a significant tumor marker, possibly as an MRD monitor in evaluating remission status and early relapse, and may also prove to be useful in predicting outcomes in acute leukemia in children.

Acute Disease↗

PubMedDate not supplied

A fatality due to injection of tiletamine and zolazepam.

A 22-year-old male with more than 28 needle marks on his right arm was found dead. First, he was suspected as a drug abuser. Blood, urine, spleen, and injection-site tissue was collected during autopsy. The blood and urine specimens were screened for drugs. Immunoassay studies did not show any illegal drugs. However, two unidentified peaks were isolated in both of these biological fluids by routine gas chromatography-flame-ionization detection (GC-FID) and thermionic specific detection. Additional gas chromatography-mass spectrometry analysis determined these two peaks to be tiletamine and zolazepam. These two agents are used in combination as veterinary anesthesia. The concentrations of these drugs in blood were quantitated by GC-FID and found to be 0.85 mg/L of tiletamine and 3.3 mg/L of zolazepam. In urine, tiletamine and its metabolite, 2-(ethylamino)-2-(2-thionyl) cyclohexanol, were identified to be present along with zolazepam. The concentrations of tiletamine and zolazepam in spleen were revealed to be 0.92 and 3.5 mg/kg, respectively. Injection-site tissue concentrations were determined to be 25.1 mg/kg tiletamine and 23.3 mg/kg for zolazepam. The cause of death in this case was determined to be due to the multiple drug intoxication of tiletamine and zolazepam.

Adult↗

PubMedDate not supplied

Cross-species amplification of Bovidae microsatellites and low diversity of the endangered Korean goral.

The Korean goral (Nemorhaedus caudatus) is an endangered species of wild goat. The conservation and management of this species could benefit from a better understanding of its genetic diversity and structure. Cross-species amplification of 34 Bovidae microsatellite loci was tested on a panel of 6 Korean gorals and 10 domestic goats. After polymerase chain reaction (PCR) optimization, 29 (85.3%) microsatellite loci amplified successfully for the Korean gorals and 27 (79.4%) for the domestic goats. Of the amplified products, 16 (55.2%) were polymorphic in the Korean goral and 22 (81.5%) in domestic goats. Nei's unbiased mean heterozygosity and mean allele number per locus were, respectively, 0.356 and 2.6 in the Korean goral and 0.636 and 4.8 in domestic goats. Low genetic diversity in the Korean gorals observed in this preliminary microsatellite survey suggests an urgent need for further detailed study of genetic diversity in Korean goral populations and a population management strategy based on these studies. Current results of cross-species amplification of domestic Bovidae microsatellites could be employed for the necessary population genetic studies on the Korean goral and other endangered Caprinae species.

Animals↗

PubMedDate not supplied

Leukemia in radiation-treated patients: cytogenetic studies in eight cases.

Abnormal chromosomes have been found in various clinical settings and in cancer patients. Eight patients developed leukemia several years after the diagnosis and treatment of a primary malignant disease. All the patients were being treated with irradiation, and five of them also received chemotherapy, notably, alkylating agents. The type of leukemias and the interval between irradiation and leukemia parallel very well with those reported from the atomic bomb casualties. Chromosomal abnormalities were seen in all the patients. These abnormalities have been reported in irradiated normal persons without developed leukemias. These findings suggest that the development of clinical cancer or leukemia may depend, not only on the presence of abnormal cells, but also on other factors. Perhaps the environment that allowed the original cancer to develop in our patients is capable of allowing the radiation-induced abnormal cells to be expressed as clinical leukemia.

Acute Disease↗

PubMedDate not supplied

Adjunctive hyperbaric oxygen therapy reduces length of hospitalization in thermal burns.

The use of adjunctive hyperbaric oxygen therapy as part of a comprehensive program of burn care at our institution has resulted in a statistically significant reduction in length of hospital stay (p = less than 0.012) with no increase in cost of hospital care in patients suffering burns over 18% to 39% of total body surface area.

Adolescent↗

PubMedDate not supplied

Adjunctive hyperbaric oxygen in the treatment of thermal burns. An economic analysis.

Current reimbursement for burn care underscores the importance of cost containment in the treatment of burn injuries. We evaluate the economic impact of adjunctive hyperbaric oxygen in burns of 19% to 50% total body surface area in patients admitted to our burn center from January 1982 to July 1987. Length of hospitalization, number of surgical procedures, and total cost of care, exclusive of surgical fees, were examined. Eleven patients did not receive adjunctive hyperbaric oxygen therapy, whereas 10 did. The hyperbaric oxygen-treated group had an average decrease in length of stay of 14.8 days, a reduction of surgical procedures of 39%, and an average saving per case of $31,600.

Adolescent↗

PubMedDate not supplied

Effects of maternal employment and prematurity on child outcomes in single parent families.

BACKGROUND: Effects of maternal employment for preschool children vary based on specific characteristics of the mother's employment, the family's economic status, and the mother's attitudes about employment. However, there is limited research on a growing group of children at developmental risk-those born prematurely and living in a single-parent family. OBJECTIVE: To examine the effects of maternal employment and prematurity on child cognition and behavior in single-parent families. METHODS: Sixty preterm and 61 full-term preschool children were recruited through NICU admission records and birth records. Data were collected with the Kaufmann Assessment Battery for Children, Peabody Picture Vocabulary Test, Child Behavior Checklist, Parenting Stress Index, and the Life History Calendar. RESULTS: Greater hours employed was related to higher achievement and mental processing scores only. Less discrepancy between actual and desired employment was related to higher achievement, mental processing, and language scores and lower behavior scores. Prematurity was not related to child cognitive and behavioral performance. Only the relationship between discrepancy and language remained after statistical control. CONCLUSIONS: The concerns about negative effects of maternal employment on young children may be overstated, especially in low-income, single-mother families. These findings are especially important in the context of welfare reform.

Achievement↗

PubMedDate not supplied

Comparison of DNA amplification methods for the detection of Chlamydia trachomatis in first-void urine from asymptomatic military recruits.

OBJECTIVE: To evaluate the performance of DNA amplification-based tests for the diagnosis of urethral chlamydia infection from the urine of asymptomatic young men. DESIGN: First-void urine was analyzed by two amplified DNA technologies, the ligase chain reaction (LCR), the polymerase chain reaction (PCR), and enzyme immunoassay (EIA). Specimens yielding discrepant results were subjected to retesting using either the original or a newly processed sample, and for evaluation of truly infected persons they were analyzed by the direct fluorescence antibody assay and by a second LCR directed against a segment of the gene encoding for the major outer membrane protein of Chlamydia trachomatis. SETTING: The military hospital in which military recruits underwent medical examination before departing for a United Nations mission. STUDY GROUP: Asymptomatic military recruits (705 young men) were screened between January and May 1994. In addition to providing urine specimens, the recruits completed questionnaires concerning previous genital infections and number of sexual partners. RESULTS: Overall prevalence of urethral chlamydia infection in the study group was 4.1% (29/705), as determined by confirmed results in all tests collectively. The performance of the DNA amplification methods was markedly better than that of the EIA antigen detection methods. Using an expanded gold standard, the sensitivity of the LCx assay was 93.1% (27/29) compared to 62.1% (18/29) by the PCR assay Amplicor and 37.9% (11/29) by EIA. Repeat testing after freezing and thawing increased the number of positive PCR results to equal the number of positive LCR results. There were three false-positive Amplicor results and no false-positive LCR results. CONCLUSIONS: The LCx assay performed better than the Amplicor assay and appears reliable for urine testing. The low sensitivity of the Amplicor assay requires further evaluation of possible inhibitors of PCR in fresh specimens. It was found that freezing and thawing the specimens before testing enhanced the performance of PCR.

Adult↗

PubMedDate not supplied

Diagnostic approach using the expression profiling of the P53 tumor suppressor gene and its related proteins in ovarian epithelial tumors.

The initial aim of this study was to examine the expression profiles of P53 and its upstream genes, downstream genes, and cell cycle regulators to determine whether these markers are useful for making a differential diagnosis among the benign, borderline, and malignant ovarian epithelial tumors. Between borderline and malignant tumors, the increased expression levels of P53, Bax, Cyclin E, and cyclin-dependent kinase-2 as well as the decreased expression levels of growth arrest and DNA damage (GADD45) and murine double minute-2 (MDM2) were significantly associated with malignancy (P < 0.01, each). Using the receiver operating curve (ROC), the most reliable cutoff value of the added-up staining scores of those markers was 4.5 with 79% sensitivity and 89% specificity for malignancy. Between benign and borderline tumors, the P21 and Bax expression levels were significantly higher in borderline tumors, whereas the Bcl-2 expression level was much higher in benign tumors (P < 0.01, each). Using the ROC, the cutoff value of the added-up staining scores used to discriminate between the two groups was 2.5 with 70% sensitivity and 74% specificity for borderline tumors. Thus, for the differential diagnosis between borderline and malignant tumors, the cutoff value 4.5 of the cumulative staining scores can be used. However, the cutoff value 2.5 for discrimination between benign and borderline tumors may not be useful because of its relatively low sensitivity and specificity. In addition, the P53, GADD45, Cyclin E, and MDM2 expression levels in malignant ovarian tumors might be useful for determining the histologic grade and type.

Biomarkers, Tumor↗